US20090083925A1

US20090083925A1 - Device and packaging for precision brushing and combing and method and tool for obtaining same

Info

Publication number: US20090083925A1
Application number: US12/132,224
Authority: US
Inventors: Jean-Louis Mathiez
Original assignee: Cinqpats
Current assignee: Cinqpats
Priority date: 2007-06-15
Filing date: 2008-06-03
Publication date: 2009-04-02
Also published as: FR2917276B1; EP2002753B1; EP2002753A3; EP2002753A2; FR2917276A1

Abstract

The invention proposes a precision brushing and combing device, allowing a top-quality, consistent, faultless and industrial implementation. To do this, the invention provides a geometrical bristle structure adjusted with precision distance-wise and angle-wise with respect to a reference, as well as dimension-wise, with mold implementation by wire spark erosion.

In an example embodiment, the plastic-injection tool comprises at least one block assembly consisting of several steel plates, at least one row of cavities each intended to form the main portion of a bristle, machined either side of the surface separating two adjacent plates, and a closing-up element, disposed at the end of at least one row of cavities, in order to form the free end surface of the bristles. A space of calibrated thickness is made between the plates forming the main portion of the bristle and the plate or bar forming the free end surface of the bristle, so as to allow the air to escape at the time of the injection whilst avoiding leakage of plastic. An ejection mechanism is provided for extracting the device from the cavity after solidification of the plastic.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to French Application No. 0755794, filed Jun. 15, 2007.

BACKGROUND AND SUMMARY

The invention relates to a device for precision brushing and combing comprising a plurality of bristles of reduced cross-section namely substantially less than 1 mm, formed on a support, rod or plate, by molding plastic. The invention also relates to packaging comprising such a device, and a method for obtaining and a tool for making this device, comprising molding block assemblies made according to a particular method.
Combing means the operation consisting of combing or untangling any type of hair or fiber. The device according to the invention is intended for cleaning or treating any surface, in particular brushing teeth, hygiene in general, body care or make-up. It is particularly adapted to cleaning delicate surfaces such as parts of the human body, the skin, teeth, hair or eyelashes, without risk of injury, and for fragile objects such as jewelry, fabrics or electronic equipment without risk of damage. This device is also adapted to the application of a precise measure of a liquid or semi-solid substance for cleaning, treating or decorating these fragile surfaces.
The invention also relates to packaging comprising such a device, and to the method for obtaining and the tool for making such a device. Within the context of the invention, the term “bristles” means outgrowths inserted on an axis substantially at right-angles to the surface of a support, having a small cross-section compared with their length of extension along said axis, by a factor of at least ten. When the bristles are rigid on account of their configuration or material, the term “teeth” is generally used.
For so-called “precision” brushing or combing, the bristles of small cross-section are considered as having a regular change of cross-section over the major part of their length. This term also underlies a great dimensional and geometrical precision, as well as a disposition of the bristles according to a regular and reproducible pattern, with no defects or pointed or sharp elements that would risk injuring the user or damaging a surface. In general terms, there is a great variety of brushing and combing devices that can be classified according to the following three main categories.
A first category covers brushes with inserted bristles such as toothbrushes, hairbrushes, paintbrushes and brooms. They consist of a wooden, metal or plastic support handle, comprising a large number of bristles disposed in groups of bristles or “tufts”.
The manufacturing method consists of inserting tufts of bristles made of flexible material, for example extruded polyamide fibers (Nylon®), into holes made in the support handle. Before insertion, the tufts of bristles are generally folded in two and connected by a small metal staple that provides a strong connection in the hole. Where stapling is not suitable, adhesive can be added in the assembly zone. It is also often necessary to level off the surface formed by the end of the bristles by passing over a cutting tool or cropping machine. This method is slow and expensive since the tufts of bristles are inserted successively one by one by a machine. Mass production requires a lot of labor or many automatic machines as well as sophisticated checking equipment to verify that the brush is complete and free from defects.
In use, these brushes are effective for scrubbing, cleaning or applying a liquid substance such as paint or varnish, but are not suitable for combing in a precise manner since the bristles are tightly packed together in the tufts and allow entry into the fibers to be separated with difficulty. In addition, the whole is not uniform since the bristles are more tightly packed in the middle of each tuft than on the periphery and the empty spaces between each tuft create discontinuities. The varied materials used to make up the handle, bristles, staple or adhesive make it difficult to recycle such a brush at the end of use.
Twisted brushes constitute a second category. In general they have a cylindrical or conical shape, like cleaning bottle-brushes and brushes for applying mascara on the eyelashes.
The method of manufacturing these twisted brushes consists of inserting a plurality of flexible plastic fibers, for example extruded polyamide (Nylon®) fibers, between the two strands of a steel wire folded back on itself in the form of a hairpin and then of twisting the assembly while holding it by the two ends, so as to trap the fibers, generating a helix shape. It is then necessary to cut the end of the bristles in order to level off the shape of the outer surface and cut off the metal wire to the correct length. For final assembly on a plastic rod or handle, it is necessary to bring the end of the twisted metal wire to red heat and put it in a small aperture in the handle or rod.
This method is slow and difficult to implement since it consists of a series of operations that are tricky to reproduce on a unit basis on each brush. The number of bristles and their rigidity can vary substantially during production, the resilience of the metal wire and its elasticity can influence the shape of the twist, and the wear of the cutting tools that have the task of leveling off the end of the bristles also leads to variations and a risk of uncut bristles. Temperature variations and clogging up due to dust also have a negative effect on production consistency. There is therefore a requirement for very sophisticated machines and monitoring throughout production in order to adjust the settings and avoid drifts. In practice, the complexity of this manufacturing method and the variations resulting therefrom do not allow absolutely identical brushes to be obtained. Variations are dimensional (standard tolerance of ±0.4 mm on the diameter of a small brush, i.e. ±5%), but also in number of bristles (standard tolerance of ±10%). The disposition of the bristles along the twisted helix can also be subject to large variations according to the machine settings which produce a crushing of the fibers at the point of trapping in the metal hairpin and a greater or lesser dispersion.
In use, these brushes are effective for scrubbing, cleaning or applying a semi-solid substance such as mascara, but are not suitable for a precise and delicate use on account of the variations caused by the manufacturing method. The combing performance of such a brush is poor since the distribution of the bristles in a spiral cannot produce a regular spacing between the bristles. The varied materials used to make up the handle, twisted wire and bristles make it difficult to recycle such a brush at the end of use.
There also exist, in a third category, brushes entirely molded in plastic which have, as the main characteristic, a continuity of material between at least part of the support and the bristles. They can have quite varied configurations including hairbrushes, certain clothes brushes and certain mascara applicators.
The method of manufacturing molded brushes consists of making a steel mold whereof the internal cavities have a profile specially adapted to the formation of a brush geometry. Molten plastic is injected under pressure, on one or more occasions, into the mold, according to known methods, to form the support and bristles. After solidification of the plastic, the mold is opened by moving at least one of its parts, and the brush is extracted by pushing movable ejection plates or rods.
This method allows brushes to be made at low cost with great consistency since the shape depends essentially on the quality of implementation of the mold. It allows brushes of different hardnesses to be obtained with the same mold, depending on the choice of material. For example a hard material such as cellulose acetate will be used to produce a rigid brush which will be referred to as a “comb” when it has only one or two rows of bristles aligned on a flat or slightly curved support. With a flexible material such as a thermoplastic elastomer (TPE), the same mold will make it possible to produce a softer brush for brushing textiles for example.
The major drawback of these last brushes is a relatively crude configuration with relatively large, conical and not very flexible bristles which do not permit delicate and precise brushing or combing. This is because it is impossible to obtain, by molding, bristles as fine as the fibers obtained by extrusion and drawing as in the other categories of brush described previously. This lack of fineness is as much due to the limitations known to persons skilled in the art in the implementation of metal injection molds, as to the technical limitations of thermoplastic material injection methods. Here is a non-exhaustive list of these limitations.
The traditional methods for removing metal for making the very fine cavities corresponding to forming bristles in the mold suffer from a lack of precision and do not allow a perfectly smooth surface finish to be obtained. Drilling or milling leaves serrations, and the electrode sinking spark erosion method leaves many small craters which will, on this small scale, be very harmful to the molding. It is also very difficult to polish a multiplicity of small cavities. Furthermore, the separating partitions between these cavities cannot be very thin without risking weakening the mold. This results in a distance between two bristles which is not as small as could be wished for precision combing.
During the operation of injecting material into the mold, three simultaneous phenomena oppose complete filling of the cavities forming the bristles in the mold:
1) pressure drops related to the viscosity of the liquid material and friction on the surface of the mold become greater, the narrower the cavity;
2) cooling of the material through contact with the metal of the mold tends to reduce its fluidity and set it prematurely; and
3) the air present naturally in the cavity has a tendency to be compressed at the bottom of the cavity during filling of the mold by the molten material, causing heating that may go as far as burning the exposed surface of the material. This results in an incomplete and blackened part, and carbon deposits that accumulate on the functional surfaces of the mold, progressively spoiling the quality of the production.
During output of the molded part from the mold after solidification of the material, an operation commonly referred to as “ejection”, any imperfection or roughness at the surface of the bristle-molding cavity will tend to retain all or part of this bristle in the cavity, risking deforming or breaking it. A broken bristle in the cavity will make this partially or totally unusable and will force long and expensive dismantling for cleaning. In order to succeed in forming the bristles in their entirety, a mold should be manufactured with a lot of “draft”, that is to say having material passage cross-sections as large as possible at the input of the bristle cavities, and continuously narrowing to the end of the bristle. Air leaks should also be made on all the mold parting lines, sometimes over the entire length of the bristle. In this way, the molten material keeps sufficient pressure to supply the end of the bristle, the air escapes as the material moves forward, and the bristle will be sufficiently strong to overcome the forces of adhesion onto the surface of the mold at ejection.
Thus, the patent EP 1 161 159 attempts to resolve the difficulties of injection molding a brush by claiming a conical bristle shape. This proposal runs counter to obtaining a precision brush since the conical shape increases the cross-section of the base of the bristle, which reduces its flexibility and increases the distance between the centers of two consecutive bristles.
Furthermore, the document US 2003/0163884 describes an original method for injecting bristles through apertures made in a support handle. This method requires molding the support handle with precise apertures, before molding the bristles in a second injection operation, which slows down production and increases the costs, especially for small-sized brushes, which do not require a handle molded in another material. Moreover, this technology imposes a relatively large distance between the bristles since the apertures in the support must have sufficiently thick profiles to be able to withstand the second injection for forming the bristles. For these reasons, this invention does not allow a precision brush to be made at low cost.
Furthermore, the U.S. Pat. No. 6,732,398 describes a tiered configuration bristle for a toothbrush, having several parts with increasingly smaller diameters as the free end of the bristle is approached. This configuration makes it possible to facilitate the filling of material as well as removal from the mold in the case where the injection method is used for its production. However, this configuration has the same negative effects for obtaining a precision brush as the conical shape.
There are also known from the documents EP 1 070 465, EP 1 070 466 and EP 1 070 467 injected plastic combs comprising series of teeth offset alternately either side of a geometrical separation surface. According to this configuration, provided that the parting line of the mold is made to coincide with the separation surface, it is possible to form each row of teeth in a different plate of the mold, with a pitch twice that of the comb finally obtained by juxtaposition of the two rows. Although efficient, these devices have the drawback of having sharp corners along the edge of the teeth and a pointed end which can injure the user, or at least suggest to them a notion of danger, more particularly for cosmetic use on the face, close to the eyes.
Furthermore, the U.S. Pat. No. 4,422,986 describes a method for producing a brush by plastic injection so that the bristles are formed between two juxtaposed parts of a mold. In order to remove the brush from the mold after solidification of the material, the parts of the mold are separated and an ejection rod is actuated. According to the description of the mold, at least part of the bristles is formed between two parts of the mold movable with respect to each other during the opening and ejection phases.
The repetitiveness of the movement at each cycle inevitably causes surface wear of the moving parts, which after prolonged use produces small gaps into which the material will enter, causing burrs along the edges of the bristles, variable as a function of the temperature and pressure parameters. Furthermore the removal of the air present in the die cavity before filling not being channeled, it takes place automatically through the gaps between the parts constituting the bristle-molding parts, more or less efficiently depending on the wear and heating of the mold.
On a multi-die-cavity mold, it is known that the temperature can vary throughout a production period, over the entire mold, or over only part of the mould, or even over a single die cavity. As the same flow of molten material is injected into the entire mold, this results in great difficulty in adjusting sufficient pressure to push the material to the end of each of the bristles on each of the die cavities without causing the appearance of burrs on any one of the bristles.
The molding burrs on the bristles are altogether harmful to precision brushing or combing. This is because these burrs, according to the use assigned to the device, can:
completely close up the interval between two teeth with a “web” of plastic, therefore reducing the effectiveness of the device;
form a fringe of thin and sometimes sharp material which could injure the skin of the user; or
sever part of the combed hair or eyelashes.
Despite the good control of certain of the technologies mentioned above, the prior art does not allow simple precision brushing or combing devices to be made industrially at low cost.
The invention aims to remedy the drawbacks of the prior art described above by proposing a precision brushing and combing device, allowing a top-quality, consistent and faultless implementation and capable of being produced industrially simply and at low cost. To do this, the invention provides a geometrical bristle structure adjusted with precision distance-wise and angle-wise with respect to a reference, as well as dimension-wise; this structure can be obtained in particular by an appropriate use of wire spark erosion.
More precisely, the subject-matter of the present invention is a brushing or combing device molded by plastic injection comprising a plurality of bristles on a support, disposed according to geometrically regular patterns, each bristle having a base attached to the support, a flexible main portion extending on a longitudinal axis substantially orthogonal to the surface of the support at its anchorage point, and a free end, in which the majority of bristles have:
a main portion defined geometrically by travel of a straight generator around the longitudinal axis, the distance between the generator and this axis being at any point less than 0.5 mm and the angle between the generator and the longitudinal axis being less than 2° at any position around said axis;
a free end defined by a transverse surface intersecting the longitudinal axis of the main portion;
and a total length lying between 1.5 and 15 mm.
Under these conditions, the brushing or combing device is sufficiently precise and regular to be used on delicate surfaces and is also adapted to the application of a precise measure of a liquid or semi-solid substance for cleaning, treating or decorating any fragile surface.
According to particular embodiments of this brushing or combing device:
the plurality of bristles and part of the support are formed by injection of a thermoplastic material chosen from amongst polyethylenes (PE), polypropylenes (PP), polyoxymethylenes (POM), polyamides (PA), polyesters (PET, PCTA, PETG, etc.), elastomers (TPE) or silicones (SI);
the main portion of the bristles has a cross-section defined by a geometrical shape that is round, elliptical, rectangular, square, lozenge-shaped, in the form of a three-lobed or four-lobed cross, or semicircular for example;
the main portion of the bristles has a changing cross-section, going progressively from one of the cross-section shapes described previously in a zone close to the base to another of the cross-section shapes in the zone close to the free end of the bristle;
the bristles are connected to the support by a flared base have a shape generated by revolution around the axis of the main portion, by a straight or curved generator, the resulting volume being a cone or a truncated torus, either convex or concave;
the bristles are connected to the support by a flared base having a changing shape around the axis of the main portion, generated by a straight or curved generator, the resulting volume possibly being a laterally flattened cone or a volume broadening in the direction of the support;
the main portion of the bristles has a flat free end perpendicular or inclined with respect to the axis of the main portion;
the main portion of the bristles has a free end embodied by a curved surface with a cylindrical, concave or convex profile, with an axis substantially perpendicular and centered with respect to the axis of the main portion;
the main portion of the bristles has a free end embodied by a curved surface with a concave cylindrical profile, with an axis substantially perpendicular to the axis of the main portion but off-center so as to form a point;
the plurality of bristles is formed into a row disposed on a support, for example elongated, flat, cylindrical or prismatic, the axes of the main portions being substantially parallel and the distance between two adjacent bristles being substantially constant;
the plurality of bristles is formed into several parallel rows disposed on a flat support attached to a handle intended to be held in the hand;
the plurality of bristles is formed into several non-parallel rows disposed on a flat support attached to a handle intended to be held in the hand;
the plurality of bristles is formed into several parallel or non-parallel rows disposed on a support attached to a rod, itself attached to the member for closing a container;
the plurality of bristles is formed on several faces of a prismatic support;
the plurality of bristles is formed into rows disposed radially around a support in the form of a cylindrical or conical rod;
the support of the plurality of bristles is axially in line with the rod;
the support of the plurality of bristles is offset angularly with respect to the rod.
Another aspect of the invention relates to packaging comprising a precision brushing or combing device connected to a rod, immersed in a container containing a semi-solid composition. The container comprises a narrow opening, which is closed up by a cap attached to the rod. Upon opening, the device is wiped on passing through the narrow opening of the container, possibly equipped with a flexible member making it possible to measure out the amount of semi-solid composition left in the gaps between the bristles. The assembly is intended for make-up for the eyelashes or eyebrows, of the mascara packaging type.
Another aspect of the invention relates to the method for obtaining a precision brushing or combing device as described above consisting of injecting plastic into a metal mold, by filling first a cavity forming a support, and then multiple cavities forming the bristles, driving out the air through vents located at the end of each cavity forming a bristle. In particular, the invention relates to a plastic-injection tool for implementing the method capable of producing a precision brushing or combing device as described above, comprising at least one block assembly in which cavities capable of molding the plurality of bristles are hollowed out.
The block assembly consists of several steel plates assembled permanently during use of the mold and able to be dismantled periodically for cleaning and maintenance. The block assembly comprises at least one row of cavities each intended to form the main part of a bristle, machined either side of the surface separating two adjacent plates. A closing-up element, in the form of a plate or bar, can be disposed at the end of at least one row of cavities, in order to form the free end surface of the bristles. A space of calibrated thickness, of between 0.005 mm and 0.050 mm, is made between the plates forming the main portion of the bristle and the plate or bar forming the free end surface of the bristle, so as to allow the air present in the cavity to escape at the time of the injection whilst avoiding leakage of plastic.
The tool can comprise an ejection mechanism for extracting the device from the cavity after solidification of the plastic by exerting pressure on the support parallel to the main axis of at least some of the plurality of bristles. The steel constituting the plates of the block assembly is chosen for its great hardness, preferably greater than 50 HRC, like for example the special steel for tools with heat treatment. As the hardness of the steel does not permit conventional machining by removal of slivers, the plates of the block assembly are shaped by a spark erosion method or more precisely as regards the cavities intended to form the internal surface of the cavities corresponding to the molding of the main portion of the bristles, by wire spark erosion. This method uses a current-conducting metal wire as an electrode to cut out a steel part. The complete equipment is known to persons skilled in the art and comprises a machine capable of unwinding the wire as it wears, controlling the voltage and inclination of the wire in order to orient the cut zone according to an angle, and move a table on which the part is fixed, in order to describe the desired cutting path. In an optimized manner, several plates constituting a block assembly are machined by spark erosion from the same block of steel, so as to ensure precise positioning of all the microcavities constituting at least some of the plurality of bristles.
The successive operations of a particular method for making a block assembly can advantageously take place as follows:
external rough machining of a steel block in order to obtain at least one reference face;
drilling of at least one hole running through the block by die sinking in order to allow the passage of the cutting wire;
rough machining cutting in order to approach the desired profile quickly, with a 0.3 mm diameter wire for example;
successive finishing passes, with an increasingly finer wire, of diameter 0.15 mm and 0.07 mm by way of a non-limiting example, until a good surface quality is obtained in the cavities and on the other functional surfaces cut;
spark erosion rework of the portions of surfaces constituting the flared bases of the bristles;
slicing of the block in order to separate the plates;
rework using wire spark erosion or conventional sinking spark erosion of various surfacings and drillings necessary for the venting of the cavities, ejection of the molded part and fixing of the block assembly; and
assembling of the block assembly and integration in a steel casing comprising molding parts complementary to those of the block assembly in order to form a complete device with a support, a rod or a handle.
The venting, or air leakage, intentionally located according to the invention at the free end of each bristle is advantageously obtained by a plate closing up all the cavities of a block assembly, with a clearance calibrated by inserts of added thickness, or integrated “in the mass”. In this case, all the free ends of the row or group of rows of bristles are geometrically disposed in one plane, perpendicular to the main axis of the bristles, or with an angle. In certain cases, it is advantageous to use venting bars disposed without the block assembly so as to each close up one row of cavities. Depending on the geometry of the bar, its polygonal, curved or circular cross-section, it is easy to give a complex shape to the free end of the bristle, and if necessary offset a row of bristles lengthwise with respect to the adjacent rows. The bars, which can be dismantled and replaced, are inserted in housings made either side of the surface separating two adjacent plates of a block assembly, perpendicular to the main axis of at least some of the bristles, or with an angle. The cross-section of the housings is intentionally larger than the cross-section of the bars so as to make the calibrated clearance necessary for the venting. The ejection mechanism is conventionally a set of sliding rods substantially parallel to the main axis of the majority of bristles and actuated by a mechanical or hydraulic system that exerts a pressure on the support of the brushing or combing device after solidification of the thermoplastic material, in order to extract the bristles from their cavities without breaking or deforming them.
On a tool according to the invention, the sliding rods advantageously have the shape of blades disposed parallel to certain rows of bristles so as to push on the small peripheral edge of the support. The vents situated close to the free end of the bristles also play a part in the ejection by allowing air to enter the bristle cavities and avoiding creation of a vacuum that would hold the bristles in the cavities by suction. In the case of a mold for a device comprising several groups of rows of bristles, the part should be held on the side of the mold comprising the ejection mechanism, in order that they can work correctly. The holding means are generally shapes intentionally created in counter-draft form on the side where it is wished to hold the molded part. The fixing to one another of the plates constituting a block assembly is particularly tricky because of the small dimensions of the assembly and the bulk of the ejection mechanisms and the venting plates or bars.
According to the invention, the system consists of several transverse screws for keeping the plates of each block assembly clamped. The head of each screw is countersunk in a counterbore made in an end plate of the block assembly, and the thread is screwed directly into a tapping made in the plate situated at the other end of the block assembly. Centering elements, pins and bars advantageously ensure correct positioning of the plates with respect to one another, even in the event of dismantling for cleaning. The fixing of the block assemblies on a mold die-cavity support plate is also advantageously performed by means of screws disposed so as to be able to be removed with “mold open”, without dismantling the mold casing.
The invention also relates to the finishing operations of the production method which can be carried out additionally on the brushing or combing device after molding and ejection from the mold in order to give it original and advantageous characteristics, for example tapering, burning or curving. Amongst these finishing operations, tapering consists of progressively thinning the free end of the bristles by removal of material and thus obtaining a bristle flexibility comparable to that of natural bristles or certain extruded synthetic fibers. The tip of a natural bristle used in traditional brush-making, or “[fleur du poil]”, has a cross-section distinctly less than 0.1 mm, perhaps even less than 0.01 mm, and it is not possible with current technologies to produce such fineness directly by molding of thermoplastic material. Tapering can be carried out mechanically or chemically, according to the type of thermoplastic material used. Mechanical tapering, which is well suited to certain materials such as polyoxymethylene (POM) or polyamide (PA), consists of removing material from the side of the main portion of at least some of the bristles, progressively and more and more when the free end of these bristles is approached, by rubbing on an abrasive surface, a disk, an abrasive wheel or a band.
Preferably, a force should be exerted between the abrasive surface and the bristles so as to bend them progressively while exposing part of the main portion to the removal of material. The force exerted, as well as one or more relative movements between the brushing or combing device and the abrasive surface, are a determining factor for removing exactly the desired amount of material from the bristles.
The shape of the tapered tip depends on the relative translational movements applied, thus:
a movement in one direction makes it possible to cut a single chamfer on the exposed bristles;
a movement in two directions so as to cut a double chamfer on the exposed bristles;
a movement in multiple directions so as to cut the exposed bristles into a point, with a polygonal cross-section, or substantially conical.
Chemical tapering is practicable on thermoplastic materials such as polyamide (PA), polypropylene (PP), polyester (PET), polybutylene terephthalate (PBT) or elastomers (TPE) capable of being dissolved by liquid solvents such as for example methylbenzene (toluene), di-methylbenzene (xylene) or a concentrated aqueous solution of phenol, formic acid or phosphoric acid. Soaking the bristles in a chosen solvent, such as phosphoric acid for polyamide, makes it possible to dissolve the plastic constituting said bristles and therefore thin them in the zone close to their end.
Preferably, soaking the end of the bristles in the liquid solvent is done with a vertical translational movement, in a direction substantially parallel to the main axis of the majority of the bristles and with a speed set so as to expose the free end of the bristles for a time sufficient to obtain a fine and progressive point. A sustained movement of the solvent is provided by a pumping or agitation device so as to renew the liquid in contact with the surface of the bristles and extract the dissolved plastic. This operation is followed by rinsing and drying in order to neutralize the chemical effects of the solvent.
Burning is another finishing operation consisting of forming small approximately spherical outgrowths at the end of at least some of the bristles in order to give different functional characteristics to the brushing or combing device. The method consists of exposing the end of at least some of the bristles to an intense heat source until there is local melting of the thermoplastic material and formation of a drop at the end of each bristle, and of letting it cool down. This operation produces the reverse effect of tapering, since the free ends of the bristles are made fatter instead of being thinned. A device treated in this way will be suitable for brushing or combing particularly fragile or delicate surfaces, by avoiding scratches or injuries which could be caused by non-rounded free ends of bristles. In practice, burning of the free ends of the bristles can be performed by the rapid passage of a flame, by blowing hot air, or by exposure from an infrared radiation generator panel. In all cases, the intensity of the energy supplied and the duration of the exposure should be regulated in order to form outgrowths of the desired size, without risk of welding between adjacent bristles.
Curving is another finishing operation which consists of deforming the support of the brushing or combing device in order to give an angle of convergence or divergence to the plurality of bristles constituting at least one row. It is thus possible according to the invention to produce a device comprising a plurality of bristles whereof the main axes are all parallel to one another and to give an angle between the adjacent bristles by an operation of curving the support after the molding and removal from the mold operations. This method makes it possible to avoid making a specific mold for a curved device.
According to the invention, an angle of divergence is obtained by curving the support with the bristles on the outside of the radius of curvature. Divergence makes it possible to space apart the free ends of adjacent bristles whilst retaining a pitch measured at the base of the bristles close to the pitch before curving. This allows quicker use of the combing device on account of the larger opening between the bristles.
According to the invention, an angle of convergence is obtained by curving the support with the bristles on the inside of the radius of curvature. Convergence makes it possible to compress the free ends of adjacent bristles whilst retaining a pitch measured at the base of the bristles close to the pitch before curving. This allows more precise use of the combing device on account of the smaller opening between the bristles. It is possible to obtain converging zones and diverging zones on the same device by making several alternate radii of curvature.
A device comprising two groups of bristles either side of a support has, after curving, both a diverging group on the outside of the radius of curvature and a converging group on the inside of the radius of curvature. It is also possible to carry out curving after another finishing operation, such as tapering or burning. More particularly, curving is advantageously carried out by gripping the support of the plurality of bristles between two complementary jaws so as to bend it beyond its elastic limit and retain a residual deformation. Curving can have a small deformation, with a large radius (for example from 50 to 100 mm) forming a curve or with a small radius (for example from 5 to 10 mm) in conjunction with a suitable angle of convergence, or a large deformation with a large radius (curve) or with a small radius (allowing bending up to 180°). Curving can be performed directly after molding, when the part is still hot, or later, when it has completely cooled.
When the brushing or combing device is molded in a flexible material such as elastomer (TPE), or a material with a poor memory such as a polyolefin (PP or PE), the residual deformation after mechanical curving risks being zero, but also risks being small or irregular. According to the invention, in this case thermal energy should be supplied to the support before or during the gripping by the jaws, so as to soften it sufficiently to mark the curving. The thermal energy can for example by supplied by blowing hot air, or by heating the jaws with an electrical resistance. Another quick and reliable method for ensuring the residual deformation of certain materials is the application of ultrasound at the time of gripping. In this case, one of the jaws is changed into a sonotrode, connected to a source of ultrasound energy.
Advantageously, it is possible to carry out several finishing operations on the same brushing or combing device:
tapering followed by burning makes it possible to obtain bristles with flexible ends since they are progressively thinned and not aggressive since they are terminated by small bulges of molten material;
tapering followed by divergent or convergent curving makes it possible to have a maximum opening between the bristles for better combing;
tapering followed by burning followed by curving makes it possible to combine the advantages of the different methods.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will emerge from a reading of the following detailed description, relating to non-limiting examples, with reference to the accompanying figures that depict, respectively:

FIG. 1, a schematic view in perspective of a brush with inserted bristles, according to the prior art;

FIG. 2, a schematic view in perspective of a twisted brush, according to the prior art;

FIG. 3, a partial view in perspective of a tool intended to produce a brush entirely molded in plastic, according to the prior art;

FIGS. 4 to 6, schematic perspective depictions of a bristle for a brushing and combing device according to the invention;

FIGS. 7 to 11, schematic views in perspective of different shapes of the main portion of a bristle for a brushing and combing device according to the invention;

FIGS. 12 to 15, schematic views in perspective of different shapes of the base of a bristle for a brushing and combing device according to the invention;

FIGS. 16 to 20, schematic views in perspective of different shapes of the free end of a bristle for a brushing and combing device according to the invention;

FIGS. 21 a to 21 c and 22, detail views of a particular case of a bristle with changing geometry for a brushing and combing device according to the invention;

FIGS. 23 to 26 a and 26 b, schematic views in perspective of different configurations of rows of bristles for a brushing and combing device according to the invention;

FIGS. 27, 28 a, 28 b, 29 a and 29 b, perspective or top schematic views of different configurations of groups of rows of bristles for a brushing and combing device according to the invention;

FIGS. 30 a to 30 d, schematic views in perspective of a brushing and combing device according to the invention comprising rows of bristles not parallel to one another;

FIGS. 31 a to 31 d, schematic views in perspective of a brushing and combing device according to the invention whereof the support rod is angularly inclined;

FIGS. 32 a to 32 c, schematic views in perspective of a toothbrush comprising bristles according to the invention;

FIGS. 33 a to 33 e and 34 a to 34 c, schematic and partial (FIG. 34 c) views in perspective of an applicator for a cosmetic product for the eyelashes comprising a brushing and combing device according to the invention;

FIGS. 35 to 37, schematic views, in partial section, of packaging comprising a brushing and combing device according to the invention intended for eyelash make-up;

FIGS. 38 a to 38 c and 39 a to 39 c, schematic views in perspective of a brushing and combing device according to the invention configured in the form of a paintbrush;

FIG. 40, a schematic view showing the principle of machining a mold element intended to produce a brushing and combing device according to the invention;

FIGS. 41 a to 41 e, schematic views in exploded perspective showing the different steps in making a mold block assembly intended to produce a brushing and combing device according to the invention;

FIG. 42 a, a partial view in exploded perspective showing an example molding block assembly intended to produce a brushing and combing device according to the invention;

FIG. 42 b, an enlarged detail view of the previous view;

FIG. 43, a perspective view showing a partially dismantled example block assembly in conjunction with a brushing and combing device according to the invention depicted in the molding position, before ejection;

FIGS. 44 a to 44 d and 45, views in perspective showing a set of 4 block assemblies in combination, intended to mold a complex device comprising several rows of bristles disposed radially around a central axis, the different views illustrating the relative movements possible between the block assemblies;

FIGS. 46 to 49, views in perspective showing bristles that have undergone different tapering operations after the molding operation;

FIGS. 50 and 51, front and perspective views showing an example brushing and combing device that has undergone an operation of finishing by tapering;

FIGS. 52 a and 52 b, schematic views of a tapering operation using an abrasive wheel;

FIG. 53, a schematic view of a tapering operation using an abrasive band;

FIG. 54, a schematic view of a tapering operation using an abrasive disk;

FIGS. 55 a and 55 b, schematic views of a chemical tapering operation;

FIG. 56, a schematic view of a burning operation using a flat heating element;

FIG. 57, a schematic view of a burning operation using a concave heating element;

FIG. 58, a schematic view of a burning operation using a convex heating element;

FIGS. 59 to 61, perspective schematic views of brushing and combing devices that have undergone burning operations;

FIG. 62, a front schematic view of a brushing and combing device that has undergone a convex curving operation;

FIG. 63, a front schematic view of a brushing and combing device that has undergone a concave curving operation;

FIGS. 64 and 65, front schematic views of brushing and combing devices that have undergone complex curving operations;

FIG. 66, a perspective schematic view of a brushing and combing device with two opposite rows of bristles before undergoing a curving operation;

FIGS. 67 a and 67 b, front schematic views of a brushing and combing device with two opposite rows of bristles after having undergone a curving operation;

FIG. 68, a front schematic view of a brushing and combing device with two opposite rows of bristles after having undergone a complex curving operation;

FIG. 69, a schematic view of an operation for curving a brushing and combing device between movable wedges;

FIGS. 70 a to 70 c, schematic views of an operation for curving a brushing and combing device between other movable wedges;

FIGS. 71 a and 71 b, front views of brushing and combing devices made according to the invention;

FIGS. 72 a and 72 d, front views of brushing and combing devices that have undergone a burning operation;

FIG. 73, a front view of a brushing and combing device that has undergone a tapering operation;

FIG. 74, a front view of a brushing and combing device that has undergone an angular curving operation;

FIGS. 75 a and 75 d, front views of brushing and combing devices that have undergone curving operations; and

FIGS. 76 a and 76 h, front views of brushing and combing devices that have undergone curving operations of various magnitudes.

DETAILED DESCRIPTION

In the figures, identical reference numbers relate to identical or corresponding elements. As illustrated in FIG. 1, a brush with inserted bristles according to the prior art comprises:
a plurality of bristles 100, generally grouped together in tufts 4, each bristle 1 being a piece of extruded synthetic fiber;
a support 2 comprising apertures into which the bristle tufts 4 are inserted;
a handle or haft 3 connected to the support, consisting of the same material or a different material.
Another example of a device according to the prior art, illustrated in FIG. 2, is a twisted brush, consisting of a metal wire 6 bent over into the form of a hairpin and mechanically twisted so as to trap a plurality of bristles 100. Each bristle 1 has two ends 20 a and 20 b offset angularly in a random manner with respect to the ends of the bristles that are adjacent to it owing to deformations in the central part of the bristle, caused by the gripping of the metal wire. The whole is fixed to the end of a rod 5 by hot fitting of part of the metal wire.
A tool, intended to produce brushes entirely molded in plastic according to the prior art, partially depicted in FIG. 3, consists of metal blocks 7 to 16 assembled with one another and held by a casing capable of allowing all movements necessary between the blocks for molding and removal from the mold on an injection molding machine. The blocks are arranged in two sub-assemblies, 7 to 11 and 12 to 16.
The joining surfaces between these sub-assemblies, such as the surfaces 18 a, 18 b, 18 c and 18 d respectively of the blocks 7, 11, 12 and 16, are referred to as “parting lines”. A hollow volume 17 a comprising multiple extensions 17 b, 17 c constitutes the molding cavity, or die cavity. During operation, the following steps are carried out by an automatic machine:
closing of the mold with the surface 18 a being brought into contact with the surface 18 c and the surface 18 b being brought into contact with the surface 18 d;
injection of molten plastic into the cavity 17 a with sufficient pressure to fill the cavity extensions 17 b and 17 c, the air escaping through gaps between the blocks;
cooling of the plastic until it solidifies;
opening of the mold by translational movement of one of the sub-assemblies of blocks 7 to 11 or 12 to 16; and
ejection of the plastic part by displacement of the block 9 according to the movement M9 and of the block 14 according to the movement M14.
The bristle 1 x, an element of a brushing and combing device according to the invention, is described precisely with reference to FIGS. 4, 5 and 6. It comprises a main portion 21 extending along the longitudinal axis XX′ and having a straight generator g inclined by an angle α with respect to this axis. The angle α is equal to 0.4° in the example embodiment, preferably lying between 0.1° and 2° more generally. One end of the bristle 1 x is connected to a support surface 2 by its base 22 and the other, free, end is terminated by a surface 20 intersecting the axis XX′. The total length “l” is large compared with the distance “a” measured between the axis XX′ perpendicularly thereto and any point whatsoever of the generator g. In the example, l is equal to 4 mm and the ratio l/a is equal to 16. The ratio l/a can vary between 5 and 100.
The main portion 21 can have a simple shape generated by revolution as in FIG. 4, defined by rotation of the generator g around the axis XX′ while keeping the same angle α all around this axis. The bristle 1 x will thus have an identical bending modulus in all directions perpendicular to the axis XX′. In certain cases (illustrated by FIGS. 5 and 6), it is advantageous to have a flexibility of the bristle 1 x that is different along perpendicular force axes f and f′. This result can be obtained with a changing shape of the main portion 21 around the axis XX′, between two positions g and g′ of the generator which are perpendicular to each other with respectively angles α and α′ and distances a and a′. The cross-section of the bristle perpendicular to the axis XX′ is oval or elliptical, as in FIG. 5, and a force along f will produce less bending of the bristle than a force along f′.
Another advantageous geometrical shape of the main portion 21, shown in FIG. 6, is defined by the travel of a generator around the axis XX′ while describing a curve between extreme positions g and g′ with respectively angles α and α′ and distances a and a′. The cross-section of the bristle perpendicular to the axis XX′ is four-lobed, which makes it possible on the one hand to have a good “responsiveness” of the bristle whilst economizing on the plastic and on the other hand to retain a liquid or semi-solid substance in the longitudinal serrations by capillary action.
FIGS. 7 to 20 depict examples of bristles having various variants of main portions, bases and free ends. The bristle can have a main portion 21 with a circular cross-section and a conical-shaped base 22 a, as depicted in FIG. 7. The bristle can have a main portion 21 b with a rectangular cross-section with rounded corners, and a base 22 b with a progressively broadened shape, as depicted in FIG. 8. The bristle can have a main portion 21 c with a cross-section defined by 2 arcs of a circle, and a base 22 c with a progressively broadened shape, as depicted in FIG. 9. The bristle can have a main portion 21 d with a four-lobed cross-section, and a base 22 d with a shape progressively broadened from each lobe, as depicted in FIG. 10. The bristle can have a main portion 21 e with a four-lobed cross-section, and a conical-shaped base 22 e, as depicted in FIG. 11.
The bristle can have a base 22 f with a broad trumpet shape, as depicted in FIG. 12. The bristle can have a base 22 g with a narrow trumpet shape, as depicted in FIG. 13. The bristle can have a base 22 h with a changing shape generated by a curved generator around the axis XX′, as depicted in FIG. 14. The bristle can have a base 22 i with a changing shape generated by a straight generator around the axis XX′, as depicted in FIG. 15.
The bristle can have a flat free end 20 perpendicular to the axis XX′, as depicted in FIG. 16. The bristle can have a flat free end 20 b inclined with respect to the axis XX′, as depicted in FIG. 17. The bristle can have a concave cylindrical free end 20 c, with axis perpendicular to the axis XX′, as depicted in FIG. 18. The bristle can have a concave cylindrical free end 20 d, with axis perpendicular to the axis XX′, but offset in another plane so as to create a dissymmetric point, as depicted in FIG. 19. The bristle can have a convex cylindrical free end 20 e, with axis perpendicular to the axis XX′, as depicted in FIG. 20.
The bristle illustrated in FIG. 21 a has a main portion 21 with a particular changing shape which will be better understood in the schematic FIG. 21 b showing the profiles formed by different cross-section planes: the straight generator g changes between the profiles s1 and s5 each consisting of two curves. The main portion is therefore defined geometrically by two regular surfaces connected in a plane represented by the lines c and c′ which can be straight or curved. FIG. 21 c is an enlarged view of the free end 20 of the main portion 21, which in this configuration is very small, its thickness “e” being in the example equal to 0.05 mm. The bristle depicted in FIG. 22 comprises a main portion 21 with a shape changing along the axis XX′between a circular cross-section towards the free end and a four-lobed cross-section towards the connection with the base 22.
A brushing and combing device comprises a plurality of bristles 100 disposed in a single row of bristles 1 on an elongated support 2, as illustrated in FIG. 23, or in several rows of bristles 1 aligned one behind another on an elongated support 2, as in FIG. 24. The rows of bristles can advantageously be offset in staggered rows on the elongated support 2, as shown in FIG. 25.
A particularly efficient brushing and combing device comprises bristles 1 that are very tightly packed, that is to say with a distance between centers p of low value, with changing main portions 21 and very small free ends 20, as illustrated in FIGS. 26 a and 26 b. Thus, the concentration of bristles 100 is very dense and the spaces between the free ends 20 remain sufficiently large to allow the passage of fibers in the case of combing, or bending of the bristles in the case of brushing. Advantageous variants of the brushing and combing device comprise several groups of bristles 100 disposed either side of, or radially around, an elongated support 2, as illustrated in FIGS. 27, 28 a, 28 b, 29 a and 29 b.
The example of FIG. 27 in a perspective view comprises two groups of bristles 100 a and 100 b each having different characteristics and able to be used separately or successively. The group 100 a allows quick and coarse combing with a single row of bristles spaced relatively far apart and the group 100 b allows finer combing with several rows of tightly packed bristles.
The example depicted in FIG. 28 a (perspective view) and 28 b (top view) comprises four groups of bristles 100 a, 100 b, 100 c, 100 d, distributed around an elongated support 2 of square cross-section. The four groups each consist of three rows of bristles disposed symmetrically. The extension 3 of the support 2 is intended for mounting on a handle, or some other gripping member.
The example depicted in FIG. 29 a (perspective view) and 29 b (top view) comprises four groups of two rows of bristles 100 a, 100 b, 100 c, 100 d, and four groups of a single row of bristles 100 e, 100 f, 100 g, 100 h distributed alternately around an elongated support 2 of round cross-section. This disposition is particularly advantageous for replacing a twisted brush of the prior art as depicted in FIG. 2. Unlike the twisted brush whereof the number and disposition of the bristles are random, here there is a given number of bristles, with a precise disposition. The extension 3 of the support 2 is intended for mounting on a handle, a rod, or some other gripping member, not depicted. This mounting can be provided by a multitude of known methods: gluing, crimping, welding, overmolding or stapling, for example.
The example brushing device presented in FIGS. 30 a to 30 d according to different viewing angles comprises 3 rows of bristles not parallel to one another, forming an angle φ. The example brushing device presented in FIGS. 31 a to 31 d according to different viewing angles comprises a rod 3 angularly offset (angle ψ) with respect to the support 2 of the plurality of bristles.
A variant specially adapted to more intensive brushing, illustrated by FIGS. 32 a to 32 c, comprises a single group or bristles 100 consisting of multiple rows very close together, on a flat elongated support 2. This disposition is particularly advantageous for replacing a brush with inserted bristles of the prior art as depicted in FIG. 1. Unlike the brush with inserted bristles, the bristles are here disposed precisely and regularly, and can be molded in a single operation, with a single material. The handle 3 adapted for holding in the hand can be molded in the same plastic material as the bristles, or be subject to overmoldings with other materials of different colors and hardnesses in order to improve the comfort thereof. When it is suitably dimensioned, this brush can be used for brushing the teeth.
Packaging adapted to the application of a semi-solid substance on the eyelashes, in particular mascara, illustrated by FIGS. 33 a to 37, comprises a group of bristles 100 consisting of several rows, on an elongated support 2 (FIGS. 33 a to 33 e). A rod 3 in line with the support 2 is connected to a screw fitting 35 by a centering bulb 31, a retaining ring 32 and possibly a stop plate 33 (FIG. 33 a). A cover 34 mounted on the screw fitting 35 by corrugations 36 or any other connecting means acts as a gripping member (FIG. 34 a).
Advantageously, the following characteristics, taken individually or in combination, make it possible to improve the performance of the device for application of a semi-solid substance on the eyelashes:
the free ends 20 of the bristles constituting the plurality of bristles 100 are disposed parallel to a straight line “L”, inclined with respect to the support 2, as illustrated in FIG. 33 c, and have bristle lengths varying between l1 and l2 for the same row;
at least one row 37 comprises longer bristles than the bristles of the adjacent rows, as illustrated in FIG. 33 e, so as to allow easier engagement of the eyelashes in the device;
the bristles disposed in staggered rows as illustrated in FIG. 33 d make it possible to catch hold of the eyelashes during combing, so as to exert slight traction in order to curve them up;
the free ends 20 have a pointed shape as illustrated in FIG. 34 c so as to allow easier engagement of the eyelashes in the device, without however risking causing injuries to the user.
With reference to FIGS. 35 to 37 illustrating sectional views (partial for FIGS. 35 and 37), the plurality of bristles 100 and the rod 3 are immersed in a container 37 containing a semi-solid substance (not depicted) so as to fill the gaps between the bristles with said substance. The closing of the container 37 is provided by the screw fitting 35 which collaborates with a narrow part 38 of the container 37, comprising a thread 39. Before use, the plurality of bristles 100 is partially wiped by a wiper 40 made of flexible material, located in the opening of the container 37 and comprising a wiping lip 41. This wiping phase, illustrated in FIG. 35, characterized by an elastic deformation of the lip 41 of the wiper 40 and by a bending of the bristles through the action of the force F exerted manually, will have the effect of measuring out a consistent amount of semi-solid substance on the plurality of bristles 100. Another action of the lip 41 of the wiper 40 is to wipe the cylindrical part of the rod 3. A reduction in diameter 42 of the rod 3 is intended for the resting of the lip 41 of the wiper 40 in the storage position.
According to other example embodiments, illustrated by FIGS. 38 a to 39 b, the plurality of bristles 100 is disposed so that the longitudinal axis XX′ of each bristle is substantially parallel to the longitudinal axis YY′ of the rod 3. This “paintbrush” type configuration is adapted to the application of a paint, varnish or make-up product on a surface. The plurality of bristles 100 can for example have a rectangular profile, as in FIG. 36 c, or a hexagonal profile, as in FIG. 39 c. The free ends 20 of the bristles can all be aligned in one plane, as illustrated in FIGS. 37 a and 38 b, or tiered progressively as illustrated in FIGS. 39 a and 39 b.
In order to obtain a plurality of bristles 100 as described previously, use is made, with reference to FIG. 40, of an injection mold comprising at least one block assembly 200 consisting of several metal blocks 210 in which there are made cavities 202 intended to mold thermoplastic material to form the bristles. A method of making a block assembly 200 capable of producing a brushing and combing device according to the present invention is described by FIGS. 40 to 41 e.
The schematic depiction of FIG. 40 shows the principle of adaptation to wire machining for the formation of bristles using the spark erosion method used for machining a metal block 201: a conductive wire 204 supplied with electric current removes particles of material from the surface 203 of the block 201, so as to successively create cavities 202. In order to limit its wear, the wire 204 is renewed continuously by a translational movement (arrow V), and the whole is immersed in a cooling fluid. The wire 204 is drawn tight between the two points A and B which each describe a programmed path so as to generate the desired surface of the cavity 202. For example, in FIG. 40, the points A and B move in circles c1 and c2 of slightly different diameters, generating the slightly conical profile 205 depicted.
When a cavity 202 has been created, the wire moves by the distance corresponding to the inter-center distance p in order to machine the next cavity. On the block 201 as depicted, only half-cavities capable of forming bristles are machined in the surface 203. Another block (not depicted), comprising half-cavities on one surface, will be put in correspondence to form complete cavities.
In an optimized manner, in order to have a good surface finish of the cavities 202, the machining is done in several passes, with a wire 204 of increasingly fine diameter. For example for the first pass, or rough machining pass, a wire of diameter 0.2 mm can be used, keeping a distance with respect to the final surface of the cavities 202, and for the finishing pass, a wire of diameter 0.06 mm, perhaps even 0.03 mm, can be used. The fineness of the wire 204, associated with a very slow movement and a current strength controlled in a known manner, makes it possible to obtain a good surface finish of the cavities 202, with micro-grooves oriented in the direction of the axis XX′, the main axis of a bristle. These micro-grooves will not oppose the removal from the mold of the thermoplastic material. By this method, cavities can be obtained with diameters lying between 0.1 mm and 1 mm, for lengths lying between 1.5 and 15 mm.
The main steps for making a block assembly 200 for molding a plurality of bristles 100 are depicted schematically in FIGS. 41 a to 41 e:
with reference to FIG. 41 a, a piece of treated steel 206 is roughly machined so as to obtain several blocks constituting the same block assembly 200; rectangular recesses 207 are first made by sinking of a spark erosion electrode or by cutting with the rough machining wire after drilling of a pilot hole; the wire 204 machines several rows of half-cavities;
with reference to FIG. 41 b, multiple machining operations using spark erosion are carried out in the piece of steel 206 in order to obtain: recesses 208 a and 208 b, suitable for receiving ejector blocks 223 a and 223 b, tapped holes 209 a and 209 b, suitable for receiving assembly screws 221 a and 221 b, and a smooth hole 210 suitable for receiving a centering pin 222; the fact of carrying out all these machining operations in the same piece of steel makes it possible to obtain optimum positioning precision between them;
in FIG. 41 c, the piece of steel 206 is cut so as to obtain the blocks 211, 212 and 213, the blocks 220 a and 220 b being discarded;
in FIG. 41 d, the blocks 211, 212 and 213 are positioned by a centering pin 22, then assembled using screws 221 a and 221 b, a plate 214 is disposed so as to close up the end 224 of the cavities, and ejection blocks 223 a and 223 b are slid into the recesses 208 a and 208 b;
in FIG. 41 e, the block 200 is assembled; strong tightening of the screws 221 a and 221 b makes it possible to eliminate any gap between the blocks 211, 212 and 213, thus avoiding leaks and burrs of thermoplastic material during the injection operation. On the other hand, a gap v is intentionally made between the closing-up plate 214 and the three molding blocks 211, 212 and 213 in order to drive out the air present in the cavities during the injection operation; this gap (arrows v) will be for example 0.02 mm; the ejection blocks 223 a and 223 b sliding freely in the recesses 208 a and 208 b are actuated translationally by an external mechanism, not depicted.
A variant block assembly 200 is depicted in the detailed FIGS. 42 a and 42 b. So as to form 3 parallel rows of bristles, the block assembly consists of 4 main blocks, 211, 212 a, 212 b and 213. The closing-up plate 214 (FIG. 41 d) is here replaced by closing-up bars 224 a, 224 b and 224 c responsible for fulfilling the same functions of venting the mold and forming the free end of the bristles. Each bar is inserted between two blocks in hollowed-out housings on either side: the bar 224 a is placed between the blocks 211 and 212 a in the complementary housings 225 a and 225 b, the bar 224 between the housings 225 c and 225 d, and the bar 224 c between the housings 225 e and 225 f. As the bar 224 a has a diameter slightly smaller than its complete housing constituted by the two cavities 225 a and 225 b (the difference in diameter being for example 0.01 mm), the air can escape into the gap at the time of injection of the thermoplastic material.
Advantageous provisions are also illustrated by the exploded view of FIG. 42 a:
the holes 209 a and 209 b intended for the assembly screws (not depicted) are alternate so as to save space, one screw in the hole 209 a has its head housed in the block 211 and its thread screwed into the block 213, the other screw in the hole 209 b has its head housed in the block 213 and its thread screwed into the block 211;
two holes 227 a and 227 b are intended for the passage of screws for fixing the block assembly onto the mold comprising the complementary parts (not depicted) necessary for molding a brushing and combing device.
Other advantageous provisions are revealed in the enlarged view of FIG. 42 b:
the axis of the housings 225 a and 225 b is not centered in the parting line between the blocks 211 and 212 a so as to form an offset free end of bristle, as described previously;
each cavity intended to form a bristle is divided into three zones in a block 212 a for example, the zone 226 a, flared for forming the base of the bristle, the zone 226 b for forming the main portion of the bristle, and the zone 226 c, non-molding since it is situated after the closing-up bar but necessary for evacuation of the air;
the three closing-up bars 224 a, 224 b and 224 c are inclined with respect to the base surface of the blocks so as to form bristles of different lengths on the same row, the free ends being aligned along a slope;
the central closing-up bar 224 b is disposed higher than the other two in order to form a central row of longer bristles.
FIG. 43 depicts a view of the partially dismantled block assembly, with a brushing and combing device placed as it is molded. The free ends 20 of the bristles are aligned with the location on the housing 225 b of the closing-up bars (absent in this view). After solidification of the thermoplastic material, an ejection block (not depicted) slides in the recess 208 b so as to apply force on the surface 2 and drive the molded device downwards.
With reference to FIGS. 44 a to 44 d, a set of 4 block assemblies in combination 250, 251, 252 and 253 are depicted at different stages of an operation for molding a complex set of brushing or combing bristles 100, of the type illustrated by FIG. 29 a. This set comprises several rows of bristles 100 r disposed radially around a central axis AA′ (FIG. 45). The different views 44 b to 44 d illustrate the successive relative movements between the block assemblies from the position before removal from the mold (FIG. 44 a), where the block assemblies 250 to 253 form a compact block. The block assemblies are formed from elementary blocks 261, 262 (FIG. 44 a) assembled by conventional fixing means, not depicted. The tube comprising the material injection point 264 is mounted centrally. Another tube 265 is mounted on the same axis, on the other side of the device.
The opposite block assemblies 250 and 252 are first moved apart (arrows D1 and D2, FIG. 44 b) revealing the venting bars 266 and corresponding grooves 267. Then the other two opposite block assemblies 251 and 253 are moved apart (arrows D3 and D4, FIG. 44 c). After dismantling of the tubes 264 and 265, the brushing assembly is made visible in FIG. 44 d.
FIG. 45 depicts in a more detailed manner in perspective the tubes 264 and 265 disposed along the central axis A′A, opposite the rear block assembly 250 provided with its ribs 266. FIGS. 46 to 49 depict views in perspective showing a bristle 21 on a support 2, having undergone different tapering operations after the molding operation: a single 300 or double 300 a-300 b “flat surface” (FIGS. 46 and 47) ending with a flat end 20, multiple flat surfaces 300 a to 300 d (FIG. 48) and a conical tapering 300 e (FIG. 49).
The bristles that have undergone a finishing operation by tapering, for example double tapering with reference to FIG. 47, form a brushing and combing device as depicted in FIGS. 50 and 51. The operations for tapering the bristles 21 are carried out for example using:
an abrasive wheel 400 by passage in a direction of movement S1 parallel to the support 2 (FIG. 52 a: formation of a first flat surface 300 a) and then in the opposite direction S2 (FIG. 52 b: formation of the opposite flat surface 300 b);
an abrasive band 401 moving (arrow D7) by driving from two rotating shafts A1 and A2 (arrow F1 (FIG. 53)); or
a disk 402 with abrasive surface (FIG. 54) driven rotationally R2 from an offset shaft A3 for a conical type tapering (with reference to FIG. 49).
Alternatively, the tapering can be carried out by chemical attack: with reference to FIGS. 55 a and 55 b, a brush 500 provided with bristles 21 is dipped (arrow F1) into a bath of acid 501 disposed in a tank 502, and then removed from this bath (arrow F2); the immersion time and the dipping and removal speeds are adjusted to obtain the desired conical tapering.
As illustrated by FIGS. 56 to 61, it is advantageous to use a heating element to obtain a particular shape of a broadened tip 505 of the bristles 21 of a brush 500, with a particular shape of the profile of these tips. Thus:
FIG. 56 illustrates a burning operation with a flat heating element 510 in order to obtain a flat profile of the tips 511;
FIG. 57 shows a burning operation with a concave heating element 520 in order to obtain a concave profile 521; and
FIG. 58 depicts a burning operation with a convex heating element 530 in order to obtain a convex profile 531.
With reference to FIGS. 62 to 65, different brushing and combing devices according to the invention are depicted, the support 2 of these devices 602 to 605 having undergone respectively:
convex (FIG. 62) or concave (FIG. 63) curving operations;
complex, that is to say alternate convex and concave, curving operations (FIGS. 64 and 65).
Other variant devices 606 to 608 with two rows of bristles, disposed in the same plane on each opposite side of the support 2, are illustrated respectively in FIGS. 66, 67 a-67 b and 68:
before undergoing an operation for curving the support 2, the two rows 100R and 100 R′ are disposed symmetrically with respect to the support 2 (FIG. 66);
with reference to FIGS. 67 a and 67 b, the support 2 of the two opposite rows 100R and 100R′ has undergone a single curving operation;
with reference to FIG. 68, the support 2 of the two opposite rows 100R and 100R′ has undergone a complex curving operation with alternate curvings.
In order to obtain devices with a curved support as illustrated previously, operations for curving the support 2 are carried out by mechanical deformation, with optional supply of thermal energy:
between movable wedges 60, 61, 62 and 63 outside the rows R of bristles (FIG. 69) of the device 500 of FIG. 69, having one or more rows disposed on the same side of the support; or
between two movable wedges 64 and 65, in a slot 6F of which each row R1 and R2 of bristles is inserted, in the case of the device 607 of FIGS. 70 a and 70 b having opposite rows.
Before deformation, the wedges 64 and 65 are placed on each side of the support 2, facing each row R1 and R2 of bristles, the wedges having suitable complementary curvatures, convex K1 and concave K2. The wedges are then placed side by side (FIG. 70 b) in order to obtain curving of the support after molding by mechanical deformation, the rows of bristles being disposed in the slots of the corresponding wedges. Finally, the wedges 64 and 65 are moved apart and the device 607 then has the desired curvature (FIG. 70 c). The multiple curvatures of the devices 604, 605 and 608 (respectively illustrated in FIGS. 64, 65 and 68) are obtained using wedges of the preceding type having the appropriate complementary multiple curves.
FIGS. 71 a to 76 h illustrate respectively variant brushing and combing devices (the devices have the same reference numbers as the corresponding figures):
with rows of bristles R_lof linearly varying height; devices 71 a and 71 b;
with rows of bristles R1 _bto R4 _bhaving undergone a burning operation: brushing and combing devices respectively 72 a to 72 d;
with a row of bristles R_ehaving undergone a tapering operation: device 73;
with a support having undergone an angular bending operation: brushing and combing device 74;
with supports having undergone curving operations: devices 75 a to 75 d; and
with supports having undergone curving operations of various magnitudes possibly going as far as folding back (FIGS. 76 e to 76 h): devices 76 a to 76 h.
The invention is not limited to the example embodiments described and depicted. It is possible for example to provide devices with multiple supports or whereof the support or supports have series of rows disposed at the ends or in an intermediate position. Furthermore, the devices according to the invention can be adapted for applications in a large number of fields: medical, mechanical, decoration, clothing accessories, etc.
Also according to particular embodiments of this brushing or combing device:
the bristles constituting a row have a length of main portion substantially different from that of the adjacent bristles of the same row, so that the free ends of the bristles lie on an inclined slope or a curve;
several rows of bristles are disposed parallel to one another to form at least one group of rows, all the free ends of the bristles forming a geometrically regular pattern;
at least one row has bristles having a main portion with a length greater than that of the bristles of some rows so that the free ends of this row go beyond those of the other rows;
at least one group consisting of at least one row of bristles is disposed either side of the support;
several rows of bristles or groups of rows are disposed radially around a support of elongated shape;
the support of the plurality of bristles is secured to a gripping member chosen from amongst a handle, a haft and a rod;
the gripping member is connected to the support parallel to said support;
the gripping member is connected to the support perpendicular to said support.

Claims

1. A brushing or combing device molded by plastic injection comprising a plurality of bristles on a support, disposed according to geometrically regular patterns, each bristle having a base attached to the support, a flexible main portion extending on a longitudinal axis substantially orthogonal to the surface of the support at its anchorage point, and a free end, wherein the majority of bristles further comprising:

a main portion defined geometrically by travel of a straight generator around the longitudinal axis, the distance between the generator and this axis being at any point less than 0.5 mm and the angle between the generator and the longitudinal axis being less than 2° at any position around said axis;

a free end defined by a transverse surface intersecting the longitudinal axis of the main portion; and

a total length lying between 1.5 and 15 mm.

2. A brushing or combing device as claimed in claim 1, wherein all the bristles and at least part of the support are formed by injection of the same thermoplastic material into a metal mold.

3. A brushing or combing device as claimed in claim 1, wherein the main portion has, in a cross-section transverse to the longitudinal axis, a geometrical shape chosen from amongst round, elliptical, rectangular, square, lozenge, cross and semicircular shapes.

4. A brushing or combing device as claimed in claim 1, wherein the base connecting the main portion to the support comprises a portion of flared shape defined geometrically by the changing path of a straight or curved generator around the longitudinal axis of the main portion.

5. A brushing or combing device as claimed in claim 1, wherein the free end of the bristle is defined by a plane surface that is perpendicular or inclined with respect to the axis of the main portion.

6. A brushing or combing device as claimed in claim 1, wherein the free end of the bristle is defined by a curved surface with a cylindrical profile with an axis substantially perpendicular to the axis of the main portion.

7. A brushing or combing device as claimed in claim 1, wherein at least some of the plurality of bristles is disposed in at least one row on the support, the axes of the main portions being substantially parallel and the distance between two adjacent bristles being substantially constant.

8. A brushing or combing device as claimed in claim 7, wherein the bristles constituting a row have a length of main portion substantially different from that of the adjacent bristles of the same row, so that the free ends of the bristles lie on an inclined slope or a curve.

9. A brushing or combing device as claimed in claim 7, wherein several rows of bristles are disposed parallel to one another to form at least one group of rows, all the free ends of the bristles forming a geometrically regular pattern.

10. A brushing or combing device as claimed in claim 9, wherein at least one row has bristles having a main portion with a length greater than that of the bristles of some rows so that the free ends of this row go beyond those of the other rows.

11. A brushing or combing device as claimed in claim 9, wherein at least one group comprises at least one row of bristles is disposed either side of the support.

12. A brushing or combing device as claimed in claim 7, wherein several rows of bristles or groups of rows are disposed radially around a support of elongated shape.

13. A brushing or combing device as claimed in claim 1, wherein the support of the plurality of bristles is secured to a gripping member chosen from amongst a handle, a haft and a rod.

14. A brushing or combing device as claimed in claim 13, wherein the gripping member is connected to the support parallel to said support.

15. A brushing or combing device as claimed in claim 13, wherein the gripping member is connected to the support perpendicular to said support.

16. A brushing or combing device as claimed in claim 1 any one of the preceding claims, wherein the main portion of at least some of the bristles comprises a reduction in thickness by tapering into a chamfer or point, made by removal of material.

17. A brushing or combing device as claimed in claim 1, wherein the free end of at least some of the bristles comprises tips made by local melting of the thermoplastic material.

18. A brushing or combing device as claimed in claim 1, wherein the support of the device is curved according to at least one radius of curvature, by application of a mechanical force after the molding operation.

19. A plastic-injection tool capable of producing a brushing or combing device, the tool comprising at least one block assembly in which cavities capable of molding a plurality of bristles are hollowed out, wherein:

the block assembly comprises several steel plates assembled permanently during use of the mold, and able to be dismantled periodically;

the block assembly comprises at least one row of cavities each intended to form the main portion of a bristle, machined either side of the surface separating two adjacent plates;

a closing-up element, in the form of a plate or bar, is disposed at the end of at least one row of cavities, in order to form the free end surface of the bristles;

a space of calibrated thickness, of between substantially 0.005 mm and 0.050 mm, is made between the plates forming the main portion of the bristle and the plate or bar forming the free end surface of the bristle, so as to allow the air present in the cavity to escape at the time of the injection whilst avoiding leakage of plastic; and

an ejection mechanism is provided for extracting the device from the cavity after solidification of the plastic by exerting pressure on the support parallel to the main axis of at least some of the plurality of bristles.

20. A tool as claimed in claim 19, wherein the steel constituting the plates of the block assembly has great hardness, equal to or greater than 50 HRC after heat treatment, and wherein the machining of the plates is performed mainly by wire spark erosion.

21. A tool as claimed in claim 20, wherein at least one row of cavities is machined by wire cutting through the same block of steel which is then sliced so as to obtain at least two plates, subsequently assembled.

22. A tool as claimed in claim 19, wherein at least one block assembly is integrated in a steel casing comprising molding parts complementary to those of the block assembly in order to form a complete device with a support, a rod or a handle, and wherein it comprises an ejection system consisting of at least one pushing device situated along the edge of a row of bristles.

23. A tapering method for a brushing or combing device, the tapering method comprising removing material from a side of a main portion of at least some bristles, progressively in order to form a point at a free end of these bristles.

24. A tapering method as claimed in claim 23, wherein the material is removed mechanically by rubbing the bristles on an abrasive surface, a disk, an abrasive wheel or a band, while exerting sufficient force between the abrasive and the bristles in order to bend them progressively in at least one direction and thus expose part of the main portion to the removal of material.

25. A tapering method as claimed in claim 23, wherein the material is removed chemically by dipping the end of at least some of the bristles in a liquid solvent capable of dissolving the plastic constituting said bristles, for a time sufficient to obtain a fine and progressive point, the dipping being followed by a rinsing operation in order to neutralize the chemical effects of the solvent.

26. A burning method for a brushing or combing device, the burning method comprising exposing an end of at least some bristles to an intense heat source chosen from amongst a direct flame, blowing of hot air and an infrared radiation generator panel, until there is local melting of the thermoplastic material and formation of a tip at the end of each bristle.

27. A curving method for a brushing or combing device the curving method comprising gripping a support of a plurality of bristles between two jaws so as to bend it beyond its elastic limit and thus retain a residual deformation.

28. A curving method as claimed in claim 27, wherein the gripping operation is performed with a supply of thermal energy to the jaws.

29. A curving method as claimed in claim 27, wherein the gripping operation is performed with a supply of ultrasound energy to the jaws.

30. A brushing or combing device as claimed in claim 1, further comprising packaging for a hygiene, body care, make-up or pharmaceutical treatment product comprising the device, immersed in a liquid or semi-solid material intended to be applied on the skin, eyelashes or hair.