US1880840A - Screw feeding device - Google Patents

Description

Och 4 1932 A. L. CURRIER SCREW FEEDING DEVICE- Filed June 8.' 1928 Patented Oct. 4, 1932 UNITED STATES PATENT OFFICE ARTHUR L. CURRIEB, F ASHBURNHAII, MASSACHUSETTS, ASSIGNOR, BY MESNE AS- v SIGNMENTS, T0 CORNELL BAG CORPORATION, A CORPORATION OF DELAWARE SCREW FEEDING DEVICE Application led June 8, 1928. -Seria1 No. 283,785.

This invention relates to conveyors and the interior thereof a funnel shaped hopper more specifically to screw conveyors. The or container,11,which is adapted to contain invention possesses many inherent advantages 'the material to be fed into the bag. The which render it suitable for various uses, butl method of introducing the material into the 5 it is herein illustrated as applied for feeding container 11, such as, for instance, that of 55 powdered, granular, or other finely divided providing predetermined charges by weight, substances. constitutes no part of the present invention,

The principal object of this invention is and it is to be understood that this may be to provide a conveyor which is highly practiaccomplished in any suitable manner.

1o cal and eiicient in operation, cheaply and The amount of material contained in the 60 easily constructed and maintained and one hopper at any one time is also a matter which which conveys or feeds a maximum amount does not concern the present invention, this of material through an opening of predeterhaving bearing on other conditions such as mined limited size. i the size of the bag, etc., and is accordingly The merits of the present invention will varied to the conditions in any particular 65 appear from the following disclosure of one case. For the purpose of illustration, it may embodiment thereof, which is given merely be considered that. the line 12 represents the by way of example and the utility of the inheight of the material at a period during ventionwill appear from the advantages which the device is in operation.

3 which are realized in the particular embodi- Located at the bottom of the container 7o ment illustrated, 1 1 is a tube 13 which projects in both direc- The following description will be more tions beyond the container 11 and extends at readily understood by referring to the acopposite Eoints through the outer can 10, as companying drawing, in whichat 15. T e tube throughout that portionA of Figure 1 is a cross-sectional side elevation its length which is positioned in the container 75 of a hopper, conveyor screw, and feeding 11 is provided with an open top so as to form nozzle of a bag filling machine illustrating a semi-cylindrical trough 14. Connecting the present invention. the upper edges of the trough 14 and the sides Figure 2 is a cross-sectional view of Figure of the container 11 are shedding surfaces 16 33 1, taken on the line 2-2 and looking in the which may be either separatepiecesorformed 80 direction of the arrows. from the metal .out fromthe tube in the for- Figure 3 is a fragmentary, enlarged side mation of the trough. In the latter instance elevation partly in crosssection of the conthe metal may be bent back and secured to Veyi'lg SC1` W ShOWIl 111 Flgulfe 13 the sloping side walls of the container. The

5 l* igure 4 'is a fragmentary VleW 11% @FOSS Seo' outer end of the tube 13 is illustrated as pro-v S5 'tion of a side elevation of a modified form Vined With a tapering portion 17 terminating of this HYQDOU- in an outlet nozzle 18 of less diameter than The various novel features of the invention the tube 13. The4 Ontiet nozzle is of usual 40 Wl appear as the following description pro' construction and is provided with its under cee s.

B referring to the drawing it will be poltlon cut away .as at 19. S0- that the ma'. noted that thelinvention is illustrated as ap- ,ml lmay bedreadll-V depgslte mbo the be plied to a bag filling device of the type in e e Ongafe upper sur ace as a wooo which the material is introduced into a bag on@ 20 Profldod for the Purpose of osslstlflg having n Vaive fiiiing Opening The mate in introducing the bag on to the nozzle which 5 rial isv fed through the nozzle positioned in nozzle Servos to oltjhor Wholly o1' Partlauy the Hive Opening as illustrated support the bag while mounted thereon dur- It will be noted that the particular device 111g the flhng Operation. The particular shown comprises a housing or can l0, which manner of supporting the bag will depend, is of any desired shape, having mounted in however, on theother features of the filling 100 the screw 25.

core.

machine and constitutes no part of the present invention.

Surrounding the tube adjacent the tapered portion 17 is the collar 21, which may be of metal or any other suitable material which acts to reinforce the tube and to close the opening between the tube and the can 10. At the opposite end of the tube 13 a bearing 22 is provided which is mounted on suitable su porting means in such manner that it serves to support the screw shaft 23. Inasmuch as the screw in the present illustration is provided with no bearing at its opposite end, the bearing 22 is constructed to adequately support the screw for operation. A shoulder 24 is provided on the screw shaft, having a ybearing Contact with the end of the bearm 22 in a manner to take the axial thrust of the screw in operation. The screw 25 which is illustrated as an integral part of the shaft, but which may be an independent part rigidly attached therewith is of a general helith cal construction, but is of particular conguration, the advantages and functions of which will be hereinafter more fully pointed out. Located immediately above the feedin screw 25 is a second screw 26 illustrated as having a double blade terminating in a shaft mounted in a suitable bearing 28 supported in any desired manner by the -frame of the machine. It will be noted that in the present illustration the feeding is accomplished by a clockwise rotation from the screw 25, as shown in Figure 2, and in such case the upper screw 26 is constructed in such manner and located in such direction that its feeding is in the opposite direction to that of he particular direction of rotation of the screw, of course, may be varied, provided, however, that the upper screw 6 causes a feeding of material opposite to that of the outward feed through the tube 1?.. Either of the shafts 23 or 27 may constltute a driving shaft, or each may be independently driven, but in either case it is preferable to time their relative speeds so that the feeding screw 25 rotates consideraby faster than the upper screw 26.

t has been found well in practice to gear the shafts 23 and 27 together so that the uper screw makes approximately one revo- Y ution to nine revolutions of the lower screw.

It is further contemplated that any form of upper screw 26 beprovided-in that the in` vention is not limited to the double blade screw illustrated, but includes any type of screw which will function to convey the material inthe manner indicated.

By referring to Figure 3, the particular construction of the 'feeding screw will be understood as being oner having a hollow The cross-sectional shaft of the screw is likewise important and it will be noted that it has the outer surface30, the back surface '31, the comparatively narrow rounded inner surface 32 and the conveying thrust surface 33.

The modified form shown in Figure 4 is similar, in all details not shown, to the construction shown in Figure 1. The can or housing 35 is provided with a container 36 mounted therein, having a tube 37 extending along its bottom projecting through the housing 35 as at 38. The tube is provided with the shedding surfaces 39, similar to the shedding surface 16 previously described. A tapering portion 40 of the tube is provided which terminates in the nozzle 41 having the downwardly disposed cut away portion 42 and rounding end 43 similar in construction to the device shown in Figure 1. The ,collar 44 is the tapered portion 1n a manner similar to collar-21. The screw 45 in this form is provided with an extension 46 extending into the nozzle 41 for the purpose of assisting in e conveying action. The screw portions 45 and 46 are preferably made in the form of a single screw and their outside dimensions are so selected that the screw properly7 fits the g tube, the tapered portion 40 and thenozzle 41, respectively.

The advantages in the present screw reside, among other things, in the curved or angular disposition of the conveying thrust surface 33, which has its upper or outer edge overlapping the remaining portions of the surface. The surface is so constructed and disposed that upon rotation the axialthrust imparted thereby will have an inward component of force tending to force and hold inwardly the material located between the flights of the screw. A maximum'of material can be conveyed by this form of screw'in that a relatively small portion of the convey- -ing tube 13 is occupied by the screw itself,

due to the elimination of the screw shaft and `the relatively small volume of the screw itself. Further, due to the inward forces created during the feeding action, the hollow core is maintained substantially filled with material being conveyed. The inner column of material located within the core is carried along with the outer material in engagement with the flights in the screw, and in this manner the entire volume of material which occupies the space both in and around the screw flights is conveyed into the feeding nozzle.

It is further found that the component forces which tend to direct the material inwardly of the screw act in opposition to centri fugal forces to such an extent that it is possible to increase the feeding action by increasing the R. P. M. of the screw considerably beyond the point heretofore possible. With known types of screws no increased feeding action is realized by Vincreasing the R. P. M. of the screw beyond a certain poi nt, due to the centrifugal force set up by such increase of the screw speed.

An additional advantage is realized in the feeding action of the prese device in providing a screw/ of larger iameter than the outlet nozzle 18. It is well known that the valve opening vof bags is limited within certain predetermined limits to sizes which will be readily and properly closed by the material itself when the filled bag is removed from the nozzle of a filling machine. With this limiting feature to consider, the problem encountered is that of introducing through an opening of a particular size material to fill the bag in the smallest possible time interval. Consequently, the limitation as to speed on filling machines heretofore has been that of the feeding screw employed for introducing material through the valve opening. In the present construction it has been found possible to convey material at such a. rate that the nozzle 18 contains a maximum of material during the filling operation as regards fullness of the nozzle and that the rate of flow is greatly in excess of that previously obtained. The dierence in volume of the interior of the nozzle 18 per unit length and that of the tube 13 is substantially equal to the volume occupied by the screw 25, so that the material conveyed by the screw 25 is substantially that which will'fill thenozzle 18.

In the modification shown in Figure 4 it will be obvious that the screw extension 46 will assist in conveying the material to the outlet nozzle. This form may be preferred in some instances in which, due to the nature of the material conveyed and other circumstances a better feeding action is accomplished. I-Iere, like in the modification shown in Figure 1, it is contemplated that the relative sizes of the tube, nozzle and screw portions be so selected that the nozzle is maintained filled to maximum capacity in operation. This may result in providing a relatively large core for this portion of the screw so that the screw will occupy a relatively small part of the space in the nozzle. Although it is found highly desirable in practice to employ a construction in which a portion of the screw is larger than the nozzle for the purpose of conveying a maximum of material through an opening of limited size, it is contemplated that many of the advantages of the present invention may be realizedby providing a screw of the construction shown in Figure 3 of the same size of the filling nozzle and either extending the screw beyond the end of the container into the nozzle in a manner similar to the device in Figure 4 or terminating the screw at the entrance to the nozzle as shown in Figure 1.

In addition to the above advantages, there is a combined operation between the upper screw '26 and the lower feeding screw 25. is well known that when material is introduced laterally iiights of a feeding screw there is a tendency for a maximum of material to be taken from the back end of the screw. This results in some instances in the screw being'only partially lled. In the present devicethe upper screw 26 conveys material from'the forward end of the container 11to the rear thereof in a manner to feed it into the side of the screw throughout its entire length.' This operation combines peculiarly with the type of feeding screw illustrated to produce unexpected result-s in that the amount of material fed is greatlyl increased thereby. v It appears that the back feeding action of the screw 26 is more than that of a mere agitator, but is one of feeding into the screw 25 which latter screw retains substantially all of the material introduced between its flights againstA outward movement, such as would be caused by centrifugal forces or other influencing factors.

Astonishing results are produced by the present mechanism and it is found in practice that bags such as cement bags can be filled by such a machine in only a fraction of the time required by machines heretofore known and that excellent results are realized when the screw 25 is rotated at a speed as high as 2100 It. P. M. A machine in which the feeding screw 25 is rotated at approximately 1900 R. P. M. and the upper screw 26 is rotated approximately 100 R. P. M. has been found to give admirable results and has been employed to fill bags holding substantially 100 pounds with cement in only a fraction of the time heretofore consumed for a similar operation.

The above disclosure is given merely as one Yembodiment of the'present invention and' is not to be considered as limiting the invention in any way. The scope of the invention will be determined by an understanding of the present disclosure as one embodiment thereof and will be particularly pointedout in the appended claims.

I claim:

1. The method of discharging material which comprises introducing material into a tube, exerting inward and forward pressure on the material adjacent the tube wall and thereby forcing forward a compacted column within the tube and discharging this compacted column from the end of the tube.

2. In a device of the character described, the combination of a tube having a discharge opening and a conveyor screw in said tube, said conveyor screw being constructed with a hollow core in line with said opening and conveying surfaces disposed to exert an inward component upon the material being conveyed, whereby to urge the material lying adjacent the tube surfaces into the space provided by the hollow core in said screw and to into the side between the I and having a conveying surface constructed to exert an inward component upon the material being conveyed.

4. In a device of the character described, the combination of a hopper having a tube in side communication therewith, and an eX- tension for said tube of smaller diameter, constituting a filling nozzle, a spiral, hollow cored screw in the large portion of said tube adapted for rotation to feed material out through said filling nozzle, the conveying surface of said screw being constructed to exert an inward component on material being conveyed.

5. In a device of the the combination of a hopper having a tube in side communication therewith, and an extension for said tube of smaller diameter, constituting a filling nozzle, a spiral, hollow cored screw in the large portion of said tube adapted for rotation to feed material out through said filling nozzle, the capacity of said filling nozzle being substantially equal to that of said tube minus the volume of said screw.

6. A filling machine comprising in combination, a hopper, a tube in side communication with said hopper and a filling nozzle disposed as a continuation of said tube, a screw having a hollow core disposed in said tube, said filling nozzle having a diameter adapting it for insertion into4 a bag valve opening, and said tube and screw being so proportioned as to size as to have a capacity substantially equal to the capacity of said filling nozzle.

7. In a device of the character described, the combination of a hopper having a screw adjacent the bottom wall thereof and material shredding surfaces for feeding material into said screw through the side thereof, an outlet nozzle in axial communication withsaid screw, and a second screw disposed parallel with but above said first screw and adapted to feed material in the opposite direction.

8. In a device of the character described,

the combination of a hopper havmg a screw adjacent the bottom wall thereof, an outlet nozzle in axial communication with said screw, and a second screw disposed parallel with but'above said first screw and adapted to feed material in the opposite direction.

9. In a device of the character described,

character described, i

means for driving said first screw at a greater speed than said second screw.

10. A ban' filling .machine having in combination, a opper, a filling nozzle, extending horizontally from said hopper, and of a size adapting it for insertion into the valve openingof a nozzle, said screw having a reduced portion to fit within said nozzle and a larger portion within said hopper, the portion of said screw in said hopper having a capacity such as will complet-ely fill said nozzle.

11. A conveying element having a broad substantially helical face, a plow-point edge along said face, a substantially helical moldboard face extending inwardly of said plowpoint edge, and ay cylindrical opening extending axially through said conveying element.

Signed at Fitchburg, Mass., this 4th day of June, 1928.

ARTHUR L. CURRIER.

the combination of a hopper having a screw adjacent the bottom wall thereof, an outlet nozzle in` axial communication with said screw, and a second screw disposed parallel with but above said first screw and adapted to feed material in the opposite direction and A bag and a screw in said hopper andl

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