US3045865A - Hopper and feeder for spiral items - Google Patents

Description

July 24, 1962 L. J. TROTTA 3,045,865

HOPPER AND FEEDER FOR SPIRAL ITEMS Filed Nov. 12, 1958 5 Sheets-Sheet 1 IN VEN TOR.

ZOA/ARD J. 7/?07'74 July- 24, 1962 L. J. TROTTA HOPPER AND FEEDER FOR SPIRAL ITEMS 3 Sheets-Sheet 2 Filed Nov. 12, 1958 INVENTOR. 150M420 J. rfiorrn ATTORNEY July 24, 1962 L. J. TROTTA 3,045,865

HOPPER AND FEEDER FOR SPIRAL ITEMS Filed Nov. 12, 1958 3 Sheets-Sheet 3 ATTOA United States Patent HOPPER AND FEEDER FOR SPIRAL ITEMS Leonard J. Trotta, Southfield, Mich, assignor, by direct and mesne assignments, of one-half to Motor City Spring Company, Detroit, Mich, a corporation of Michigan, and one-half to The United States Bedding Company, St. Paul, Minn., a corporation of Minnesota Filed Nov. 12, 1958, Ser. No. 773,274 15 Claims. (Cl. 221-13) This invention relates to hoppers and feeders and more particularly pertains to a hopper for mass storing and individually positioning spiral items, such as helical wire lengths, and an associated feeding means for moving an individual spiral item out of the internested mass, the hopper with the feeding means being operated automatically, semi-automatically, or manually.

Hoppers and feeders have been employed heretofore to facilitate the storing and feeding of various items; however, the several devices of the prior art have not proven capable of storing and/or individually feeding spiral items, such as helical wire lengths, which internest in a tangled mass. Moreover the devices of the prior art are unsuitable, complicated in design and construction, expensive to manufacture, and difficult to use.

With the foregoing in view, the primary object of the invention is to provide a hopper for storing spiral items in mass having a dimensionally sized area, such as a trough, for locating an individual spiral item for coaction with variously operated driving means which is simple in design and construction, inexpensive to manufacture, easy to install, easy to use, and which is substantially fool-proof in operation.

An object of the invention is to provide means for vibrating the hopper to shake and dislocate the mass to eifect moving a single spiral item into the trough area for individual coaction with driving means.

An object of the invention is to provide spiral item drive means on the hopper normally retracted out of driving position to permit proper location of the spiral item relative to the driving means and also to provide for an idle non-driving relationship during dwell or periods of non feeding when other operations are occurring.

An object of the invention is to provide spiral item drive means for the hopper which is selectively actuated to drivingly engage a single spiral item to angularly rotate the item threadwise relative to a key to axially move the item out of the hopper.

An object of the invention is to provide a key capable of engaging only the bottom-most spiral item in the hopper so that no other spiral item has threadwise axial reaction to angular rotation.

An object of the invention is to provide means for moving the drive means relative to the spiral item in the engaging direction.

An object of the invention is to provide a circuit for energizing the moving means.

An object of the invention is to provide a normally open switch in the circuit closable by the proper positioning of a spiral item relative to the drive means.

An object of the invention is to provide a normally closed switch in the circuit located on a machine being fed which is opened by the presence of a spiral item in the machine in proper location to de-energize the drive means.

.An object of the invention is to provide drive means which can be actuated manually, semi-automatically, or automatically.

An object of the invention is to provide at least one movable drive and/or idler wheel for actuating and deactuating the drive.

These and other objects of the invention will become apparent by reference to the following description of a 3,645,865 Patented July 24, 1962 hopper, feeder, and associated machine embodying the invention taken in connection with the accompanying drawings, in which:

FIG. 1 is an end elevational view of two hopper-feeder devices, partly in cross-section such as on the line 11 of FIG. 2.

FIG. 2 is a cross-sectional view of FIG. 1 taken on the line 2-2 thereof showing the means for powering the drive wheels.

FIG. 3 is a cross-sectional view of FIG. 2 taken in the direction of arrow 3 thereof showing the power means from the top side.

FIG. 4 is a cross-sectional view of FIG. 1 taken on the line 4-4 thereof.

FIG. 5 is a schematic view showing the hopper, spiral item, machine, receiver, circuit, and associated switches, motors, vibrators, and solenoids.

FIG. 6 is a cross-sectional view of FIG. '2 taken on the line 66 thereof showing the drive wheels in the advanced engaging position.

FIG. 7 is a view similar to FIG. 6 showing the drive wheels in the non-engaging retracted receiving position.

FIG. 8 is a cross sectional view of FIG. 2 taken on the line 8-8 thereof showing the power gearing.

FIG. 9 is a cross sectional view of the hopper trough area taken on the line 9-9 of FIG. 2. showing a peg or vertical key.

FIG. 10 is a view of the showing of FIG. 9 taken in the direction of the arrow 10.

FIG. 11 is a view similar to FIG. 9 showing a horizontal or cross key.

FIG. 12 is a view of the showing of FIG. 11 taken in the direction of the arrow 12; and

MG. 13 is a longitudinal cross sectional view of FIG. 12 showing the bottom spiral item or helix engaging the key and the next above nested helix out of engagment with the key.

Referring now to the drawing wherein like numerals refer to like and corresponding parts throughout the several views, FIG. 1 shows a preferred dual embodiment wherein each of the oppositely disposed devices singly embodies the invention and illustrates that a plurality of devices can be used together to feed a plurality of spiral items to a machine as required at one time. Both devices have a hopper 2G for holding a mass of nested spiral items terminating downwardly in a reduced area or trough 21 which is capable of receiving and holding a single helical wire length or spiral item 22 at the bottom thereof, an idler wheel 23 leading through the hopper case for contacting the spiral item 22, drive wheels 24 leading through the hopper case for contacting the spiral item, jaw arms 25a and 25b pivotally disposed and rotatably and sidewise moveably supporting the drive wheels 24 into and out of engagment with the spiral item 22, means 38 and 39 pivotally supporting the arms 25a and 25b, and a rotation reaction key 26a and 26b, FIGS. 9 to 13, for reacting against a rotating spiral item 22 to impart axial movement thereto by a threading action when the wheels 24 and 23 rotate a spiral item.

More particularly each hopper 20 comprises a front wall 30, a back wall 31, end walls 32, and a bottom wall 33 with the front wall 30 and back wall 31 converging downwardly relative to one another and terminating in a reduced area such as the trough 21 which is dimensionally sized to receive a single spiral item 22 at the bottom thereof; and the end wall 32 at the feeding end of the hopper has an opening 34, FIGS. 3 and 5, for emitting the spiral item 22 toward the machine receiver 35. The hoppers 20 are equipped with mechanical or electrical vibrators 36 for shaking the mass of internested spiral items in the hoppers to move a spiral item 22 into the bottom of the trough 21 with the upper spiral item lying thereon 3 and thereabove as seen in FIGS. 9, 11 and 13. The idler wheel or roll supporting brackets 37]) and 37a are respectively mounted on the upper hopper on the front wall 30 and on the lower hopper on the back wall 31 and support the idler wheel or roll 23 so as to project a portion of the wheel periphery into the trough 21 area to engage the spiral item 22 therein on one side thereof; the jaw arm 25b lower end is pivotally connected at 38 to the bracket 37b and the jaw arm 25a is pivotally connected at 39 to the bracket 37a. The solenoid 4t) pivots the arm 25a and the solenoid 41 pivots the arm 25!) so that when the solenoids 40 and 41 are energized they so move the arms to so cause the drive wheels 24 to move toward the idler wheels 23 to close on the spiral items '22, as the wheels 24 are mounted on the arms 25a and 25b for movement therewith.

It is to be noted that solenoids 40 and 41 act oppositely when energized as the drive wheels 24 on the arms 25a and 25b respectively are on opposite sides of the pivot points 39 and 38 and that the hopper walls are open in the area 44 of the drive wheels 24 to permit penetration of a peripheral portion of the drive wheels 24 to engage a spiral item 22 and rotate the same.

In the lower hopper 20, FIG. 2, drive wheels 24 are equipped with shafts 45 and gears 46 which engage with gear 47 on shaft 48 which has a pulley 49 engaging the belt 50 Which is driven by a motor 51. Upper hopper 20, FIG. 3, is similarly equipped with the motor 51 driving the belt 50 to the pulley 49 on shaft 48 to drive the gears leading to the drive wheel-s 24 and a suitable housing 54 enclosing the gears in both instances is provided and the drive wheels may have knurled surfaces to provide increased frictional engagement as shown.

The motor 51 and vibrator 36 of each hopper 20 are disposed in a circuit, FIG. 5, preferably for constant operation as the device must be constantly ready to feed; the solenoids 40 or 41 (shown at S in FIG. is disposed in a circuit including the normally open switch 55 and the normally closed switch 56 requiring that both switches be closed before the solenoid is energized.

Normally open switch 55, FIG. 5, is disposed with its operating member 57 in the trough 21 so that when a spiral item 22 is properly located therein it depresses the member 57 closing the switch 55. Normally closed switch 56 is disposed adjacent the machine driving means such as'in the receiver 35 and has an operating member 58 actuated by the presence of a spiral item in driven relationship to the machine driving means so as to open the switch 56. Each hopper preferably is equipped with such a circuit.

In the movement of the drive wheels 24 on the arms 25a and 25b the drive belts 50 provide sufficient flexibility to permit the slight movement of the shafts 48 and associated gears and housings. FIG. 7 illustrates that when the solenoid is not energized the spiral item 22 can move into the bottom of the trough 21 without interference from the drive wheels 24 as they have fallen via gravity out of engaging position and a spring may be provided to so move the arm 25a or 25b if gravity is not suitable. FIG. 6 illustrates that when the solenoid is energized it moves the arm 25a or 25b to advance the drive wheels 24 into engagement with the spiral item 22 to impart angular rotation thereto and both FIGS. 6 and 7 illustrate that it is preferable to locate the centers of the idler Wheel 23 and top drive wheel 24 above the center of the spiral item 22 so that the radially engaging peripheral surfaces of the wheels are above the engaged portion of the spiral item 22 so as to urge the spiral item 22 downwardly trapping it in the bottom of the trough against the bottom drive wheel 24 thereby preventing its escape. It is to be noted that the wheel centers are not high enough to efiect engagement with spiral items above the bottom spiral item 22. While the trough 21 is shown having parallel side walls 60 and 61 and a bottom wall 62, FIGS. 9 to 12, it is obvious that modifications can be made.

Due to the internal disposition of the drive wheels and associated parts on the upper hopper 20 (FIG. 1), like hoppers can be located with their emitting openings close together to feed machine receivers which are close together and since most furniture and mattress spring unit fabricating machines use helicals both at the top and bottom of a unit at the same time, it is necessary to feed two receivers on the machine to keep the machine loaded. As seen in FIG. 1, the hopper emitting openings can be moved close together or further apart and aligned as desired by adjusting the supporting means (not shown) for the hoppers. The following description of the oper tion of the hopper includes the association of one or more hoppers with a machine which has a receiver, spiral item rotating and axially driving means, and a cycle of operation which includes preparing the machine with other parts to receive the spiral items and then moving or driving the spiral items into integrated association therewith.

Prior to operation, each hopper 2t is located adjacent a machine with its emitting opening 34 aligned with and spaced from the machine receiver 35 and then the normally closed switch 56 is positioned in the receiver 35, as shown, or otherwise disposed adjacent the machine driving means so as to open the switch 56 when a spiral item is in engagement with the machine driving means.

In operation, the hopper 20 is loaded with a mass of internested spiral items called helicals and the circuit energized to power the vibrator 36 so as to shake the mass and to power the motor 51 so as to rotate the drive wheels 24. As the trough 21 is initially unoccupied, the switch 55 is open with the solenoid 40 deenergized so that the arm 25a on the lower hopper 20 ('FIG. 1) is retracted moving the rotating drive wheels 24 out of the trough area so that the trough 21 is open to receive a helical. The vibrator then moves a helical into the trough 21 depressing the member 57 and closing the normally open switch 55 to close the circuit to the solenoid 40 which extends the arm 25a on one side of the pivot point 39 to move the drive wheels 24 on the other side of the pivot point 39 toward the helical 22 for engaging therewith whereby the drive wheels 24 angularly rotate the helical 22 against the idler wheel 23 which angular rotation of the helical 22 against the key 2611 or 26b causes the angularly rotating helical to threadwise drive thereagainst to move the helical axially outwardly of the hopper through the emitting opening 34 and into the machine receiver 35 where the extending end of the helical is engaged by the machine helical drive mechanism, not shown. The member 58 is depressed by the helical when engaged by the machine driving means to open normally closed switch 56 breaking the power circuit to the solenoid permitting the drive wheels to drop out of engagement with the helical to stop the hopper drive on the helical. When the machine next operates, the machine drive means moves the helical angularly and axially through the machine and completely out of the hopper at the same proportional angular and axial feed rate since the diameter and lead on the helical are the same in both the hopper and the machine so that the machine drive easily threads the helical 22 remainder out of the mass and past the key 26a in the hopper.

When the machine removes the remainder of the helical from the hopper and drives the same into the spring unit or workpiece, the absence of a helical 22 permits switches 55 and 56 to assume their normal positions and, since the helical feed rate of the machine is extremely fast, both switches act substantially simultaneously as the helical travels axially faster, almost, that the eye can see. This places both the hopper and machine in position for the next operation.

As soon as the helical moves out of the hopper trough 21, the vibrator 36 moves another helical 22 into the trough closing the switch 55 whereupon the solenoid 40 moves the drive wheels 24 into drive position and the helical moves out of the hopper emitting opening 34 and into the machine receiver 35' into engagement with the machine drive contacting member 58 to open switch 56 to de-energize the solenoid as and then to stop the hopper feed to the machine thereby leaving the machine loaded for the next operation. The hopper drive and machine drive then remain inactive while the operator loads the machine as the hopper feeds the machine immediately and even before the operator can move the workpiece into the next station position. After the operator loads the machine, the machine drive moves the helicals into the workpiece and the operations are then repeated with the hopper automatically feeding the machine with a helical, thereby eliminating the necessity of the operator obtaining the helical and inserting it into the machine.

While the above operation is described relative to the lower hopper 20, FIG. 1, the upper hopper 20 operates identically with the exception that the solenoid 41 thrusts upwardly to move the drive wheels into driving relationship with the helical 22 whereas solenoid 40 thrusts downwardly. In the upper hopper the arm 37b and drive wheels 24 are on the same side of the pivot point 38.

Usually two hoppers 2b are employed to feed helicals to a machine as the machine feeds one helical at the top and another helical at the bottom of the spring unit being made and both helicals are driven into the workpiece at the same time.

Due to the fact that helicals in mass are internested and tangled, one hopper 20 may not position a helical in the trough at the same time as the other, requiring that the drive wheels be engaged at different times as the switches 55 are closed at different times and for this reason a circuit is preferred for each hopper used. However, this can easily be modified by using one circuit for two or more hoppers with the switches 55 and 56 associated with each hopper connected in series into a common circuit so that both helicals will be fed upon the last switch closing. This and other modifications are considered within the purview of the invention such as separate mechanical vibrators, slides to move the drive wheels, and mechanical, hydraulic, or pneumatic means to move the drive wheels. Obviously the drive wheel or wheels can be fixed and the idler wheel or wheels can be moved by the slide, arm, or jaw into and out of engagement with a spiral item or helical. While the device has been disclosed as an automatic pre-loader, it is well within the purview of the invention to provide a manual means for engaging the driving members to feed a helical or to connect the hopper circuit with the machine circuit so that both are activated at the same time to feed and drive a helical.

The inventive mass storage hopper and individual helical feed constitute a simple, inexpensive, useful, and very adaptable device to feed helicals individually out of an internested mass automatically, semiautomatically, or manually, as desired. While other hoppers and feeders may employ somewhat similar means, none of them are capable of handling internested helicals and feeding them one at a time.

Although but two similar embodiments of the invention have been disclosed and described in detail, it is obvious that many changes may be made in the size, shape, detail, and arrangement of the various elements of the invention within the scope of the appended claims.

I claim:

1. A feeding device particularly suitable for feeding items having a spiral surface such as helical wire lengths one at a time from 'a group of internested helical wire lengths to a machine such as a spring section fabricating machine making spring sections for mattresses and furniture comprising a hopper for holding a plurality of internested helical wire lengths; a trough at the bottom of said hopper of such width dimension to receive only a single helical wire length at the bottom thereof, an idler wheel on said hopper partially leading through said trough for rotatably engaging a helical wire length at the bottom of said trough with said idler Wheel center being slightly above the center of said single helical wire length to engage the same on one side thereof, a jaw and jaw arm pivotally mounted on said hopper, a pair of drive wheels on said jaw partially leading through said trough with one drive bottom wheel being located at the bottom of said trough to engage the helical wire length at the bottom thereof and the other drive side wheel being located at the side of said trough opposite said idler wheel to engage the helical wire length on the other side thereof with said side drive wheel center being slightly above the center of the helical wire length at the bottom of said trough; means for powering said drive Wheels; said side idler wheel and said side drive wheel trapping a helical wire length at the bottom of said trough with downwardly directed forces; means for pivoting said jaw for moving said drive wheels into and out of driving engagement with a helical wire length at the bottom of said trough; means for vibrating said trough to cause an internested helical wire length to drop to the bottom of said trough, said driving and idler wheels being adapted to angularly rotate a helical wire length at the bottom of said trough when said jaw pivots said drive wheels into engagement therewith, a rotation reaction key in the bottom of said trough for engaging the spiral of a rotating helical wire length to cause the same to move axially out of said trough, said pivoting means comprising said arm on said jaw and a solenoid on said arm for moving said jaw in the engaging direction; a circuit energizing said solenoid; and a normally open switch in said circuit having means associated with said trough for closing said switch when a helical wire length is located in the bottom of said trough.

2. In a device as set forth in claim 1, a receiver located on the machine being fed for receiving the end of a helical wire length, and a normally closed switch disposed in said circuit located adjacent said receiver adapted to be opened by the presence of a helical wire length being fed from the trough to the receiver to release the drive wheels from the helical wire length.

3. A feeding device particularly suitable for feeding helical wire lengths one at a time from a group of internested helical wire lengths to a machine such as a spring section fabricating machine making spring sections for mattresses and furniture comprising a hopper for holding a plurality of internested helical wire lengths; a reduced trough at the bottom of said hopper of such Width dimension to receive only a single helical wire length at the bottom thereof, at least one idler 'wheel on said hopper partially leading through said trough for rotatably engaging a helical wire length at the bottom of said trough, at least one jaw mounted drive wheel partially leading through said trough to engage a helical wire length lying at the bottom of said trough on the opposite side of said helical wire length from said idler wheel, means for powering said drive wheel; means for pivoting said jaw for moving said one drive wheel into and out of driving engage ment with a helical wire length at the bottom of said trough; said driving and idler wheels being adapted to angularly rotate a helical wire length at the bottom of said trough when said jaw pivots said drive wheel into engagement therewith, a rotation reaction key in the bottom of said trough for engaging the spiral of a rotating helical Wire length to cause same to move axially out of said trough, said pivoting means comprising an arm on said jaw and a solenoid on said arm for moving said jaw in the engaging direction; a circuit energizing said solenoid, and a normally open switch in said circuit having means associated with said hopper bottom trough for closing said switch when a helical wire length is located. in the bottom of said trough.

4. In a device as set forth in claim 3, a receiver located on the machine being fed for receiving the end of a helical wire length, and a normally closed switch disposed in said circuit located adjacent said receiver adapted to be opened by the presence of a helical Wire length in the receiver to break said circuit to said solenoid to release the drive on a helical wire length being fed.

5. A feeding device particularly suitable for feeding helical wire lengths one at a time from a group of internested helical wire lengths comprising a hopper for holding a plurality of internested helical wire lengths; a trough at the bottom of said hopper of such width dimension to receive only a single helical wire length at the bottom thereof, paired driving and idler wheels on said hopper partially leading through said trough for rotatably engaging a helical wire length at the bottom of said trough; at least one of said wheels being a drive wheel, a pivotally mounted jaw arm supporting said drive wheel, means for driving said drive wheel; means for moving said arm and said drive wheel into and out of driving engagment with a helical wire length at the bottom of said trough, means for vibrating said hopper to cause an internested helical wire length to drop to the bottom of said trough, said driving and idler wheels being adapted to rotate a helical wire length at the bottom of said trough when said jaw pivots said drive wheel into engagement therewith, and a rotation reaction key in the bottom of said trough for engaging the spiral of a helical wire length to cause same to move axially in conjunction with rotation out of said trough.

6. In a device as set forth in claim 5, said moving means comprising an arm and said jaw and a solenoid on said arm for moving said jaw in the engaging direction; a circuit powering said solenoid; and a normally open switch in said circuit having means associated with said hopper closing said switch when a helical Wire length is located in the bottom of said trough.

7. In a device as set for in claim 6, a receiver located on the machine being fed for receiving the end of a helical wire length, and a normally closed switch disposed in said circuit located adjacent said receiver adapted to be opened by the presence of a helical wire length in the receiver to break said circuit to said solenoid to release the drive on a helical wire length being fed.

8. A hopper feed device for feeding helical wire lengths having a spiral peripheral surface'co'mprising a hopper adapted to hold a plurality of spiral items in mass internested relationship, a trough at the bottom of said hopper of such reduced dimension as to receive and hold only one spiral item, vibrating means attached to said hopper to shake a spiral item at the bottom of the nested mass into said trough, means for axially moving said spiral item from the bottom of said hopper including at least one drive wheel on said hopper projecting into said trough to engage the bottom-most spiral item to rotate same, at least one idler wheel on said hopper projecting into said hopper to engage rotationally the bottommost spiral item relative to said drive wheel, and a key at the bottom of said trough for engaging the bottommost spiral item at the bottom thereof to provide a threadwise reaction point to the bottom-most spiral item being rotated by said Wheels to cause the rotating bottommo-st spiral item to spirally drive against said key thereby axially moving the bottom-most spiral item out of said hopper.

9. In a device as set forth in claim 8, which includes wheel moving means for moving said wheels into driving relationship relative to a spiral item a solenoid powering said wheel moving means into driving relationship, a circuit powering said solenoid, and a normally open switch in said circuit having means adjacent the bottom of said hopper co-ntactable by the bottom-most spiral item when in proper wheel driving relationship to close said switch and circuit to power said solenoid to move said wheel moving means and wheels into driving engagement with the bottom-most spiral item.

10. In a device as set for in claim 9, including a nor- 8 mally closed second switch in said circuit attached to a machine receiver being fed by said device, said receiver having means contactable by the spiral item fed into the receiver for breaking said circuit thereby to stop the feeding of said spiral item.

11. A hopper feeder device particularly suitable for feeding items having a spiral peripheral surface comprising a hopper adapted to hold a plurality of spiral items, a sized trough at the bottom of said hopper of such dimension to receive and hold only one spiral item, at least one drive wheel on said hopper at the sized trough thereof projecting into said trough to engage the bottom-most spiral item to rotate same, at least one idler wheel on said hopper at the sized trough thereof projecting into said hopper to engage rotationally the bottom-most item relative to said drive wheel, and a key at the bottom of said reduced trough for engaging the bottom-most spiral item at the bottom thereof to provide a threadwise reaction point to the bottom-most spiral item being rotated by said wheels to cause the rotating bottom-most spiral item to spirally drive against said key thereby axially moving the bottommost spiral item out of said hopper.

12. In a device as set forth in claim 11, also comprising means for moving at least one said wheel into and out of engaging relationship with the bottom-most spiral item to permit added space for the easy dropping of a spiral item into bottom-most relationship; and to move same out of said hopper when said wheel is engaging relationship with said bottom-most spiral item.

13. In a device as set forth in claim 12, also comprising a solenoid powering said wheel moving means into driving relationship, a circuit energizing said solenoid, and a normally open switch in said circuit having means adjacent the bottom of said hopper contactable by a bottom-most spiral item when in proper wheel driving relationship to close said switch and circuit to energize said solenoid to move said Wheel moving means and wheel into driving engagement with a bottom-most spiral item when properly located in driving position with said key and wheels.

14. In a device as set forth in claim 13, also comprising a normally closed second switch in said circuit attachable to a machine receiver being fed by said device constituting means contactable by a spiral item fed into a machine receiver for breaking said circuit to stop device feed to permit the machine receiver to control further movement of the spiral item.

15. A device as set forth in claim 8 which includes a receiving means, said receiving means which receives the spiral item axially removed from the bottom of the hopper being adapted to disengage the means for axially moving said spiral item whereby another spiral item may be positioned into the bottom of the hopper.

References Cited in the file of this patent UNITED STATES PATENTS 693,933 Webb Feb. 25, 1902 1,012,106 Seavey Dec. 19, 1911 1,980,815 McBean Nov. 13, 1934 2,065,888 Du Bnll et al Dec. 29, 1936 2,275,209 Turgeon Mar. 3, 1942 2,532,443 Freundlich Dec. 5, 1950 2,630,145 Stevens Mar. 3, 1953 2,632,588 Hoar Mar. 24, 1953 2,675,031 Penny Apr. 13, 1954 2,675,237 Willcox Apr. 13, 1954 2,913,098 Zellinsky et al Nov. 17, 1959 FOREIGN PATENTS 893,878 France Feb. 28, 1944 956,520 France Aug. 8, 1949 1,136,555 France Dec. 29, 1956

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