US2653056A - Method of making brooms - Google Patents

Description

Sept. 22, 1953 B. MONTERO ET A1. 2,653,056

METHOD oF MAKING BRooMs Filed De'c. 20. 1948 Patented Sept. 22, 1953 f' UNITED STATES PATENT ori-*ics METHOD F MAKING` BROOMS Bruno Montero, Los Angeles, and Raymond J.

Palmer, Long Beach, Calif., assgnors to Modgln Company, Inc., Los Angeles, Calif., a

corporation of California Application. December 20, 194:8,V Serial No. 66,7216

(Cl. 30u-21) 3 Claims. l

Our invention relates. general to amethod of making such articles. as.v brooms, brushes. and the like and, more particularly,` to. a method of securing tufts of bristlesfto. the handle, head, or the like, of such. an article.

`Considering terminollgy to be employed' hereinafter, since, as. suggesteds inthe preceding paragraph, the method of our 'invention 'is applicable tothe manufacture of articlesof thet type which includes brooms, brushes and the like, articles o f this type will be referred to as broomsas a matter of convenience. The element of 'the -broom to which tufts` of bristlesv are to, be` secured will be referred 'to as the head of 'the broom, it being understood that the term` head 'is intended to include the tutt-carrying element of any article of the type under consideration. Also, the term "tuft, as used hlereinafter,v is intended toinclude groups of bristles of various. sizes and shapes.

A primary object of the. present Vinvention is to provide an improved method of securing 'a tuft of bristles of thermoplasticmaterial lin a cavity in a. broom head.r

More specifically, "a primary 'object Yof the invention is to provide, a method of securing a tuft of thermoplastic bristles in. a 'cavity which Yinvolves fusing that. end of the tuftwhich is insorted into the cavity s'ov as'to.v bond the bristles together and to anchor the tuft in the cavity.

An important object is to. provide. a method wherein the end ofthe tuft which isinserted into the cavity is heated electrically toa temperature at least equal to that at which4 the thermoplastic material becomes. plasticso as tobond the bristles together and to anchor thejtuft in'the'cavity..

Another Objectis to, provide'a method, offfusing the tuft end inthe cavity by resistance heating. K Still another object iste/provide a-method of fusing the tuft end in the cavity vby induction heating.

A further object of ourr inventionis'to. providea method which involves only locallheating 'of 'the end of the tuft in theoavity.

The foregoing objects of our invention and the advantages suggested thereby, together with various other objects andV advantagesfwhich will, become apparent, may be attainedtl'irough the employment ofthe exemplary embodiments of the invention yvvhichare'illustrated in the accompanying drawing and which are described in -detail hereinafter. Referringto the drawing;

Fig. 1 is a side elevational -vew of a broom manufactured in accordance; with the method of the e invention ;V

Fig. 2 is an end elevationalrview 'ef the broom illustratedin Fig. 1 of the drawing.; n Figs. 3 and 4 are enlarged; fragmentarysectional'views showing tufts of bristles inserted in cavities in -a' broom head, Fig.A 'Sfshowing the tufts of "bristles before fusing and'FigfLl showing'the tufts after fusing;

Figf5 is faf'semidiagrammatic:vvicw ilistrating an embodiment of. the method of the invention which involves resistance heating; and`y Figs. 6 `and 7 areA semidiagramm'ati'c views illustrating embodiments offthe metiiodY of the invention which involves induction. heating.

Referring particularly to Figs.V 1v and' 2. of the drawing, We show abrocm I0. which includes a head 'Il having a. handle I2.' suitably connected thereto, tufts I3 of. thermoplastic bristles [i4-'being secured tothe head in accordance with the method of they invention. In the particular construction illustrated, the tufts I3 take the form of relatively thin sheets off bristles llt',y although the tufts4 may have any Aconfiguration without departing from the spirit. of the invention.

Referring particularly to Fig. 3' offthe drawing, we show ends I6' of the tufts [3 inserted intocavities li in the broom head I'I prior Vto fusing of the tufts to anchor them in the cavities, 'the cavities being grooves inthe particular construction illustrated to accommodate the particular con.- figura'tions shown. In Fig. 4' of. therdrawing, We show the ends I6, ofthe tufts i3. as fused. to bond the bristles ld togetherwithin the cavity H and to anchor the tufts in. thecavity. The method of fusing the ends It of' the tuftswill be `considered in the following paragraphs.`

Considering the method of the invention in more detail, we prefer, for reasons which will be discussed in more detail hereinafter,y to, 'employ for the broom head lH a material 'which is non-.- conductive,l or substantially nonc'onductiyaelec'- trically and which is substantially a nonconductor, or at leasta. poor conductor; of heat. After the cavities 11 of a size Yandyshape corresponding to the size and shape of the tufts f3 have been formed in thebroom'h-ead-I I,Weinsert into each cavity an electrical conductor IB. The conductors It mayftalze various forms. Forexample, the conductorsl8- may be formed-byplac ing in the cavities lil powdered metal in sucient quantities to form continuous electric'l current paths connecting the ends-of the cavities. Alternatively, the Walls ofthe cavities maybepainted with a materialwhichiscapable of conducting electricity to lformthe'conductors I8. However, as a matter of convenience, We prefer toempl'oy conductors i8 having lthe form of 1 pieces of Wire which are placediinfthe'cavitiesfl T. n

In naccordancewith the method 'ofthe invention, the conductors lil are'heated electrically to `fuse the ends It ofthe tuftsl3 to'bondtogether those ^portionsv ofthe bristles i4 Which-form the ends I6 of the'tufts andv to anchorfthe tufts in 'the cavities. The conductors lmaybeheated electrically in various ways. For example, in Fig. 5 of the drawing, `Wesliovv`V leads I'Sconnectedlto the opposite ends-ofthefconduct'ors i8', the leads I9` beingfadapteditoibefconne'cted to a `suitable sourcerof electricity "to: effect resistance heating ofthe conductors`,theflatterfactsing asresistors. 'InevFigsiGrandinofrthe drawing,

we have illustrated inductive heating of the conductors I8. In Fig. 6, the broom head II having the tufts I3 inserted into the cavities II-Al` i therein is shown placed in an induction furnace represented schematically by a coil 20 which may be connected to an alternating. current source of suitable frequency. In Fig. 7, we show A Whichare poor conductors of heat.

the broom head I I with the tufts I3 inserted into the cavities II therein as placed in an induction furnace represented schematically by platesZl which may be connected to a source of alternating current of suitable frequency. The broom heads II may be placed in the induction furnaces shown in Figs. 6 and 7 of the drawing one at a time, or may be moved continuously therethrough if desired.

The conductors IB are heated in either of the foregoing ways to an extent and for a length of time sufficient to elevate the temperatur-e of the tuft ends I6 to a value at least equal to that at which the thermoplastic material becomes softened or plastic. The temperatures at which various thermoplastic materials become plastic are well known in the art so that a recitation thereof herein is thought to be unnecessary. When the tuft ends I6 have been heated sufficiently to render them plastic, the bristle ends forming tuft ends I6 merge to render the tuft ends substantially homogeneous, thereby bonding the bristles I4 of each tuft together to form a substantially integral unit, which is a feature of the invention. Also, as the tuft ends I6 are fused by electrical heating of the conductors IB, the tuft ends are securely anchored in their cavities I1. We have found that the anchoring of Athe tuft ends I 6 in the cavity I'I israpparently due to the fact that, as the tuft ends are fused,

or plasticized, they tend to shorten axially of I0 is to be put.

As previously indicated, we prefer to employ for the broom head II materials which are at least substantially nonconductive electrically and The reason for preferring a material for the broom head which is substantially nonconductive electrically is to minimize the amount of electrical power required to fuse the bristle end I6. Also, the purpose of using a material which is substantially nonconductive electrically and which is a poor conductor of heat is to insure that the tufts I3 will fuse only locally in the vicinities of the conductors I3. This further reduces the amount of electrical power required and also prevents fusing of and possible damage to the bristles I4 of the tufts exteriorly of the broom head II. For

example, wood, various plastic materials, and the like are among those which we prefer to employ for the broom head Il. However, in instances where the foregoing factors normally in favor of substantially nonconductive materials for the broom head may be disregarded, various conductive materials, such as metals, may be employed if desired.

It will be apparent that the present invention provides a simple method of securing tufts of bristles in cavities therefor without the use of any fastening devices, such as clips, staples, or the like, which must be driven into the material of thebroorn head. Although we have disclosed exemplary embodiments of our invention for purposesl of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention.

We claim as our invention:

1. A method of securing a tuft of thermoplastic bristles to an element having a cavity therein, said thermoplastic bristles becoming plastic at a temperature lower than that required to alter i the physical structure of said element, including We have found that when the tufts I3 ,I

are anchored in this manner, they cannot be withdrawn from the cavities I'I without applying thereto forces much larger than those which would normally be encountered during use of the broom I0. If desired, resistance to withdrawal of the tufts I3 may be further increased by undercutting the cavities, i. e., by making the cavities of lesser width at their outer ends than at their inner ends.

Presumably, the tendency of the tuft ends I6 to expand laterally when plasticized is due to the action of surface tension, although we do not wish to be bound by this theory.

Although the method of the present invention is not limited to application to any particular thermoplastic material, it is preferable to employ for the bristles I4 thermoplastic materials suitable for the particular purpose for which the broom I0 is to be used. We have found that polystyrene, or copolymers of polystyrene, for example, are particularly suitable for bristles of a broom to be used for sweeping purposes, although other thermoplastic materials may be more desirable for bristles in brooms to be used for other purposes. For example, such thermoplastic materials as vinyl resins, cellulose plastics, and the like maybe employed for the bristles the steps of placing an electrical conductor in said cavity; placing an end of said tuft in said cavity; and electrically heating said conductor to elevate the temperature of said end of said tuft to a value at least equal to that at which those portions of said thermoplastic bristles which form said end of said tuft become plastic, whereby to bond said bristle portions together and to secure said end of said tuft in said cavity.

2. The method set forth in claim l wherein said electrical conductor comprises a resistor and wherein the step last defined comprises flowing an electric current through said resistor.

3. The method set forth in claim 1 wherein the step last defined comprises heating said conductor inductively.

BRUNO MONTERO. RAYMOND J. PALMER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,190,206 Churchill Feb. 13, 1940 2,294,480 Rohweder Sept. 1, 1942 2,303,800 Swann Dec. 1, 1942 1 2,341,823 SmithA Feb. 15, 1944 2,397,471 Cox Apr. 2, 1946 2,406,732 Hardman Aug. 27, 1946 2,426,328 Wandel Aug. 26, 1947 2,438,156 Dodge Mar. 23, 1948 2,472,003 Cunningham May 31, 1949

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