US2879919A - Apparatus for feeding loose-leaf metal arches - Google Patents

Description

March 31, 1959 R. E. KNCCHE APPARATUS FOR FEEDING LOOSE-LEAF METAL ARCHES 3 Sheets-Sheet 1 March 31, 1959 R. E. KNOCHE APPARATUS FOR FEEDING LOOSE-LEAF" METAL ARCHES 3 Sheets-Sheet 2 Filed Sept. 5, 1951 un-E R. QEIKNOCHE APPARATUS FOR FEEDING LOOSE-LEAF METAL ARCHES Filed Sept. 5, 1951 March 31, 1959 5 Sheets-Sheet 3 5W .n M a fl wivf Z m 19 0 FL M W \X 2 J\ M a W A y mi 0 a l n/ fi 9 6 2 l LI W N k A m F United States Patent APPARATUS FOR FEEDING LOOSE-LEAF METAL ARCHES Raymond E. Knoclie, Overland, Mo. Applicationseptember s, 1951,,Serial No. 245,131 11 Claims. Cl. 221-277 This invention relates generally tothe manufacture of loose-leaf metals of the character employed in loose-leaf notebooks and particularly to an apparatus for automatically feeding such parts to a riveting machine as and when they are needed. I v i In the manufacture of loose-leaf metals, it is customary to rivet the so-called arches (which constitute respectively one-half of a ring) to a backing strip. The number of arches riveted to such a backing strip depends upon the number of rings in the notebook so that two such strips, each with the appropriate number of arches secured thereto, may be arranged side by side to provide the desired number of rings. Suitable jigs have heretofore been provided for receivmg and maintaining, in proper assembled relationship, such-a strip and the appropriate number of arches' while the latter are beingriveted tothe'forrner as for example in a press.

conventionally, the arches are inserted in such a jig manually one at a time but during the last'fifteen years, various efforts have been made to feed the arches automatically. into such a jig. Such efforts have involved the provision of a barrel having internal baffies of relatively short extent, adapted to contain a supply of arches and to rotate about a horizontal axis. A plurality oflshafts, corresponding in number to the number of arches intended to be riveted onto a given strip extended'through the open end of the barrel in a downwardly and outwardly sloping. direction. One or more chutes were arranged to intercept arches cascaded from the flanges within the. barrel anddirect those arches axially of the shafts to a position where they spilled upon the shafts. Each shaft then conveyed the arches on it to a chute leading to the appropriate position in the'assembly jig. To secure the proper orientation of the arches on the shafts aforesaid, and to eliminate from the shaft all such arches which were improperly oriented thereon, a mechanism was provided which involved a pair of rails extending longitudinally of each shaft and arranged so as to maintain the arches level and, centered on the shaft, upon which they were riding; and one oflthe rails. was interrupted so as to permit arches riding on the shaft in improper orientation to drop therefrom. Such dropping was accomplished under the force of gravity by virtue of the. fact that while the body position of such arches is substantially circular, one end thereofis provided with a tail, the weight of which tends to cause the arch to rock on the shaft unless otherwise restrained. The rejector mechanism above-mentioned removed such restraint against rocking of archeswhose tails extended in the wrong direction, and consequently permitted themto fall free of the shaft and return to the stock within the barrel.

Devices of the character above-described were not successful in cornmercial'operation for two reasons. First, the severalshafts would not becomeuniformly loadedlwith arches, with the result. that one rJmQre of the chutes (into which the respective shafts fed) might be empty when it was desired to charge a jig. Secondly, the rejector mechanism was uncertain in its operation; when the shaft rotated in one direction, itstendency was to retain all of the arches on the shaft; and when it rotated in the opposite direction, its tendency was to discharge the properly oriented ones alongwith the improperly oriented ones.

The object of the present invention generally stated is to provide a device for automatically feeding such arches to a riveting jig in proper orientation and to avoid the objections encountered with devices of the character generally described above.

Another object of the invention is to'provide anautomatic feeder for feeding such arches to a plurality of positionsv on a riveting jig at high speed.

' Other objects will become apparent to those skilled in the art when the following description is read' in connection'with' the accompanying drawings, in which:

Figure 1 is a view in side elevation of an automatic arch feeder constructed in accordance with the present invention.

Figure 2 is a longitudinal sectional view of the device shown in Figure l.

Figure 3 is a sectional view taken along line 3-3 of Figure 2.

Figure 4 is a sectional view taken alongside line 4-4 of Figure 3.

Figures 5, 6, and 7 are sectional views taken along lines 5-5, 6-6, and 7-7 respectively of Figure2.

Figure 8 is a'view corresponding to Figure 7 but showing the parts in ejecting position.

Figure 9 is a perspective view of the ejector.

Figure 10 is a perspective'view ofone typical form of archintended to be handled by the apparatus.

Figure 11 is a longitudinal sectional view of a chute and showing a gate therefor.

Figure 12 is a sectional view taken of Figure 11.

Figure 13 is a view corresponding to Figure 11' but showingthe parts in a different position.

Figure 14 is a planviewof another form of ejector.

Figure 15 is a sectional'view takenalong line 15-15 of Figure 14.

Figure l6'i's a view corresponding to Figure 15 but showing the parts in ejecting position.

Generally stated, the invention'contemplates the pro vision of a truncated conical receptacle arranged for rotation about heads and having on the interior thereof a plurality of obliquely extending baffles, the inner edges of which are conformed so as to terminatesubstantially parallel with the axis of the receptacle and relatively. close to such axis. In cross section, thesaid baffles. are of trough shape, each having its radiallyoutward portion departing substantially from radial relationship with the axis of the receptacle but terminating in a lip which extends in a direction substantially radial to the axis of the receptacle; The trough thus provided is open to dip and retain quantities of arches and carry them upward from the bottom of the receptacle toward the top thereof duringrotation of the receptacle about its axis.

A conveying shaft driven for rotation about its axis, which is preferably concentric with the axis of the receptacle aforesaid, extends through the truncated end of'the' receptacle to a position between the inner edges of'the several .baflles" aforesaid, and extends outwardly to a position remote from the receptacle. A pair. of rails extendslongitudinally alongside the shaft, and the upper surfaces thereof are arranged. to make contact respec tively with the ends, of arches riding upon the shaft. At a position well within the truncated end of the receptacle,

along line 12-12 surfaces one of the rails is interrupted so as to permit arches whose tails are riding upon the interrupted rail to rock (under the influence botli ofgravity acting upon the" tail, and of friction from the rotating shaft acting upon the body) about the axis of the shaft and free themselves, thus ref turning to the stock within the receptacle. The invention particularly contemplates, however, that the arches whose tails are riding upon the uninterrupted rail be retained in position on the shaft by depressing the uninterrupted rail so that it is out of level with the interrupted rail, immediately ahead 'of and at the interrupted section of the opposite rail. With such an arrangement, and with the shaft rotating in a direction such as to tend to rock the aches riding thereon toward the interrupted section of rail, the propeerly oriented arches (i.e., those whose tails are resting on the uninterrupted rail) are held in position thereon, the extra weight of their tails being disposed below the horizontal diameter of the shaft, restraining them against movement in the direction of rotation of the shaft. Alternatively, the uninterrupted 'properly oriented arches from the conveying shaft in multiple, and discharging them respectively into different chutes, each of which leads to an appropriate position in an assembly jig. The present invention particularly contemplates that such an ejector be arranged so as to provide a part in alignment with the pair of guide rails aforesaid over which the arches pass while riding on the shaft and are thereby intercepted and ejected in multiple. Such an ejector may be selectively movable about the shaft as an axis, in whole or in part to remove the support under those arches which at the time of ejection are riding upon that increment of shaft which is underlaid by the movable arch supporting portions of the ejector. If said portion of the ejector is long enough (in the direction axially of the shaft) to accommodate but two arches, two and two only will be ejected, but it will be understood that such portion of the ejector may be made long enough (in the axial direction of the shaft) to accommodate any desired number of arches. Adjacent the ejector and in position to receive arches ejected thereby, a plurality of chutes is provided, the number thereof depending upon and being equal to the number of arches intended to be ejected at each operation of the ejector.

Each chute leads to a different arch receptacle in a suitable jig, and the several chutes may be provided with a gate capable of passing (in any one chute) but one arch at a time. The gates for the several chutes are preferably arranged for simultaneous operation, but may also be individually operated.

Having thus generally described the machine, reference may be had to the drawings for an illustrative embodiment thereof.

A truncated conical receptacle 1, having an open end 2 and a closed end 3, is mounted upon a suitable support 4, and driven in rotation about its axis which in the embodiment shown slopes downwardly from horizontal.

From the interior of the wall of receptacle 1, a plurality of baffles project so as to terminate adjacent and substantially parallel with the axis of rotation of receptacle end 3 thereof, said shaft being supported by support 4 and driven exterially thereof as through a pulley 7.

Beneath shaft 6, a concave stationary bar 8, having rail 9 and 10, is arranged. The end of bar 8 adjacent bottom 3 of receptacle 1 is carried by a plate 11 which 4 embraces shaft 6 and permits the latter to rotate freely therewithin while the bar 8 remains stationary. The outer end of bar 8 is carried by a suitable support 12, which support likewise carries a bearing 13 for shaft 6. As clearly shown in Figure 5, the rail surfaces 9 and 10 of bar 8 are arranged with reference to shaft 6 so as to make contact with the opposite ends of an arch 14 riding on the shaft 6. As clearly shown in Figures Sand 10, the arch 14, while in the main substantially circular, is provided at one end with a tail 15 which, when the arches are properly oriented on shaft 6, makes contact with rail 10. Arches whose tails 15 make contact with rail 9 are improperly oriented, and are rejected from shaft 6 within receptacle 1 by the arrangement now to be described. Bar 8 is cut away so as to eliminate rail 9 between positions 16 and 17, shown clearly in Figure 2. The gap 18 thus provided in rail 9 permits improperly oriented arches riding on shaft 6 to rock in the direction of the arrow in'Figure 6, and thus be dislodged from shaft 6, falling back into the bottom of receptacle 1. In order to minimize the probability that improperly oriented arches in being thus discharged from shaft 6 drag the then properly oriented arches, the invention contemplates that rail 10 be depressed below the level of rail 9 immediately ahead of (i.e., toward bottom 3) position 16, for a distance sufficient to permit the properly oriented arches to rock away from rail 9 before gap 18 is reached by them. This arrangement frees the improperly oriented arches to move in the opposite direction without dragging properly oriented arches with them. For added assurance that no improperly oriented arch shall pass gap 18, a feeler 60 is mounted on bar 8 with its tip in the path of the tail on any improperly oriented arch (but clearing properly oriented arches). The tip of feeler 60 may be bent to cam downwardly any tails engaging it.

In order to prevent the arches riding on shaft 6 from over-riding each other, as they approach the gap 18, a prong 61 is mounted on bar 8 with its free end overhanging shaft 6 at a clearance suflicient to pass but one arch. Immediately ahead of gap 18 and there-beyond towards the ejector to be described later, bar 8 may be provided on the side of rail 10 with a member 20, which overhangs rail 10 and provides there-between a channel 21, proportioned so as to accommodate tail 15 of one arch 14 at each increment of cross-section.

Shaft 6 may be, and preferably is, provided with a shallow groove .22 spiraled about the shaft in a direction tending to urge the arches 14 riding thereon out through the open end 2 of receptacle 1 as said shaft turns in rotation. Accordingly, the arches on shaft 6 are progressively moved outwardly from receptacle 1 toward an ejector now to be described.

At the end of shaft 6, there is an ejector comprising a block 23, bored at 24 to receive shaft 6, and mounted so as to be rotatable about said shaft. The rearward end of block 23, which faces toward receptacle 1, is shown facing the reader in Figure 9. The rearward end of block 23 is cut away so as to provide a semi-cylindrical projection 27, having flat shoulders 25 and 26, in prolongation of rails 9 and 10 respectively. The axial dimension of shoulders 25 and 26 is determined by the number of arches which it is desired to eject at each operation of the ejector, which is to say that if three arches each A" wide be desired to be ejected together. the axial dimension of shoulders 25 and 26 is /8" plus tolerance. Thus, anincrernent of shaft 6 of corresponding axial dimension is exposed above shoulders 25 and. 26, and the arches being conveyed by said shaft from receptacle 1 proceed immediately over shoulders 25 and 26 until further movement is interrupted by end face 28 of block 23. Block 23 is provided with an arm 29 extending radially-therefrom, and adapted to be rocked (in the counterclockwise direction as seen in Figures 7 and 9) through an angle of by any suitable operatorcontrolled me hanism (not shown) when and as it is desired to eject the archesfrom the increment of shaft 6 exposed above shoulders and 26.

A multiple chute 3 0, suitably sub-divided so. as to accommodate the thickness of one arch 14, is provided with its mouth adjacent the semi-cylindrical part 27 of the ejector, so. that when block 23 is rotated 90 in. the counterclockwise direction from the position shown in Figure 7, and shoulders 25 and, 26 become nearly vertical (as shown in Figure 8), arches resting thereon will be discharged, tail aft, into the chute 38, each, of the several arches being deposited into a separate subdivision of the chute. As shown in Figure 2, the chute 30 is sub-divided into three sections 31, 32, and 33; but it will be understood that any appropriate number 'of such sub-divisions may he provided depending upon the number of arches accommodated by shoulders 25 and 2 6, and

the number of arches which it is desired to rivet into a single strip. A gate 40 in the form of a thinstrip of metal is arranged to separate the arches which are positioned above shoulders 25 and 26, from those arches which are riding on shaft 6 immediately in advance thereof, at each operation of the ejector. In the embodiment shown, the gate 40 is carried by an arm 41 pivoted at 42 to a lug 43 mounted on bar 8. The forward end of arm 41 normally (i.e., when the ejector is in the position shown in Figure 7) rides upon a hump 44 on block 23, but. as the latter is rotated as above-described, the forward end of the arm falls into a depression 45. The amplitude of such movement need be only sufficient that the normal position of gate .40 is elevated out of contact with the advancing arches, but, when block 23 is rotated to. eject, gate 40 falls into position ahead of that arch which is next to be accommodated by the ejector.

In alignment with the partitions separating chute section 32 from sections 31, and 33, divider blades 450 extend into position to separate the arches as they fall from the ejector. When it is desired to maintain a working supply of arches in the several chute sections 31, 32, and 33, a gate is provided in each such section, and arranged so that, upon each manipulation, one, and only one arch will pass the gate. In Figures 11, 12, and 13, such a gate is shown in association with chute section 31 but it will be understood that all other chute sections are similarly equipped. The gate consists of ashoe 46 shaped to approximate the contour of arch 14 but embracing less than 90 thereof. The shoe 46 extends through a slot'47 in the top wall of chute section 31 and is provided with an exterior handle 48 pivoted on pin 49 located near the center of an arch engaged by the arcuate portion of shoe 46, as shown in Figure 11. When in the position shown in Figure 11, the shoe 46 prevents downward movement of the arch 14 engaged by it and all other arches 14 therebehind. When the shoe 46 is moved to the position shown in Figure 13, however, the arch 14 is released, but arch 14 cannot move fully into the position previously occupied by arch 14 until the shoe 46 is restored nearly to the position shown in Figure ll. The handles 48 for the gates in the several chute sections are preferably arranged for concomitant movement as by the provision of an actuator (not shown) arranged to engage and move all such handles at once; but it is desirable that the several handles also be individually movable by hand as to replace a defective arch delivered through one chute.

An important feature of the invention resides in the contour of the bafiles 5. As clearly shown in Figure 3, the baffles are trough-shaped, having their innermost section 50 extending substantially radially and their outward section 51 inclined with reference to a radius. Thus, between the sections 50 and 51, a trough is provided which is open on the leading side of the baflle and hence scoops from the bottom of receptacle 1 a quantity of archesand transports them upwardly until they are cascaded over the lip section 50 toward shaft 6. To assure that the great- I eat numher of arches thus cascaded be caught by shaft 6,

thefree' edge of lip section 50 preferably extends very nearly parallel with the axis of shaft 6 and in as close as; possible relationship thereto, which is to say that the edges of the b afiles 5 just clear the exterior contour of b'ar 8., The body portions 51 of the baffles 5 are arranged. outo f parallel relationship with the axis of receptaclel, so as to incline in a direction such that the free ends thereof (toward end 2 of receptacle 1) lead the opposite ends.

' Any suitable chute 52 may be arranged to extend through open end 2 of receptacle 1 in laterally off-set relationship'to shaft. 6 so as to facilitate the periodic charging of receptacle 1 with a new supply of arches and without interrupting operationof the mechanism.

As the. alternative to the ejector mechanism abovedesc'ribed, or in cases where it, is desired to eject arches from, the'shaft 6, at a station immediately intermediate receptacle 1 and the above-described mechanism, an ejector of the character shown in Figures 14, 15 and 16 may be employed. In this case, the bar 8 is provided with one or more slots, three, 81, 82, and 83 being shown in Figure 14. In the embodiment shown, the several slots 81, 82, and 83 are proportioned axially of the shaft 6 so as to correspond to the thickness of a single arch plus clearance, but, it will be understood that a single such slot, having a dimension axially of the shaft 6 corresponding to any desired multiple of arches may be utilized. The slots 81, 82, and 83 extend approximately half-way throughv the bar 8 and form gaps in the rail 9 thereof. A member 84 is mounted for transverse movement relative to shaft 6 and, is provided with shoulder parts 85, 86, and 87 arranged to move in and out of the slots 81, 82, and 83 respectively. The shoulder parts 85, 86, and 87 have their upper surfaces arranged so that when they are in the slots, the upper surfaces of these parts complete the continuity of rail 9. As shown in the drawings, member 84 is mounted for sliding movement on support 12, and is guided in such movement by guide rails 88 suitably affixed to support 12. Block 89 is also mounted for sliding move ment between rails 88 under the impetus of a suitable actuating mechanism not shown. When block 89 is moved between the positions shown in Figures 15 and 16, a part 90 integral with member 84 is received within a recess 91 block 89 and moved therewith toward bar 8. Member 84. is constantly urged toward the position shown in Figures 14 and 15 by suitable springs 92. Block 89 carries a series of paired divider blades 92, 93, and 94, aligned respectively with slots 81, 82, and 83, and disposed so that when block 89 is in the position shown in Figure 15, the blades are clear of arches advancing along shaft 6; butwhen block 89 is moved to the position shown in Figure 16,'each pair of divider blades intercepts an arch progressing along shaft 6, and retains it in alignment with the respective slots 81, 82, and 83, until member 84 is moved into the position shown in Figure 16 and back again to the position shown in Figure 15. In order that, the arches advancing along shaft 6 be progressively intercepted, the pair of blades 92 (which is most remote from receptacle 1,) is made longer than 93, and 93 longer than 94. Consequently, an arch is intercepted by blades 92 before one is intercepted by blades 93, and the latter before one is intercepted by blades 94.

Member84 is slotted at 95, and support 12 is slotted at 96 to provide a, passageway beneath slots 81, 82, and 83 which is fully open when the parts are in the position shown in Figure 16. Suitable chutes are connected with support 12 so that their interiors are aligned respectively' with the aforesaid passageway. Accordingly, when the block 89 is moved from the position shown in Figure 15 toward that shown in Figure 16, the desired number of arches is intercepted by the divider blades and held in position respectively adjacent slots 81, 82 and 83 until member 84 is moved, until the position shown in Figurel d-isreached where the shoulders 85, 86, and 87 are removed from the slots 81, 82, and 83 and the rotation of shaft 6 rocks the intercepted arches into position where they fall through the slots in members 8, 84, and

12, and into the chutes 130.

The operation of the devices may be briefly summarized as follows: A suitable charge of arches is deposited into receptacle 1 and by virtue of the conical shape thereof together with the inclination of bafiies 5, move toward the which lands astride shaft 6 (and others which land otherwise) will fall back into the bottom of a receptacle 1.

Some of the arches, which fall astride shaft 6, will have their tails 15 extending in one direction, others in the other direction, but all are advanced down shaft 6 toward gap 8 where those arches which are improperly oriented will be rejected, while the others proceed and are conveyed by shaft 6 to the ejector and are thereby ejected from shaft 6 in multiples, depending upon the number desired for simultaneous forwarding into a riveting jig.

While one complete embodiment of the invention has been described in detail, such embodiment is to be regarded as merely illustrative of the invention, and not to be considered as a limitation upon the invention. While in the drawings the ejector device has been illustrated as handling three arches at a time, it is to be understood that any desired number may be simultaneously ejected by appropriately increasing or decreasing the capacity of the ejector. Neither is the invention limited to the particular style or size of arch illustrated. It is to be distinctly understood, therefore, that such modifications, adaptations and variations and the substitution of equivalents for the several elements disclosed as may occur to those skilled in the art without departing from the spirit of the invention are, although not specifically described herein, contemplated by and within the scope of the appended claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. In a device for ejecting arches from a moving shaft having a pair of aligned guide rails extending therealong, said guide rails respectively engaging the opposite ends of arches riding on said shaft and maintaining the arches astride said shaft despite movement of said shaft, the improvement which comprises, one of said rails being interrupted at a position intermediate the ends of the shaft, and means movable into and out of alignment with said one rail at said interruption to retain the arches on the shaft when in such alignment but release the same from the shaft when out of such alignment.

2. The combination of claim 1 wherein the interruption in the rail extends axially of the shaft for a distance sufiicient to accommodate a plurality of arches oriented contiguously on said shaft, a plurality of chutes each having a mouth adjacent said shaft at said interruption, said mouths being aligned axially of said shaft and dis- .posed to concurrently receive each an arch from said shaft as said means is moved out of alignment with said rail.

3. In a device for ejecting arches from a rotatable shaft having a pair of aligned guide rails extending therealong, said guide rails respectively engaging the opposite ends of arches riding on said shaft, the improvement which comprises, one of said rails being interrupted at a posi tion intermediate the ends of the shaft, means movable into and out of alignment with said one rail at said interruption to retain the arches on the shaft when in such alignment but release the same from the shaft when out of such alignment, and means for rotating said shaft in a direction such that the top of said shaft moves toward said interrupted rail.

4. The combination with a shaft for conveying arches thereastride with their ends guided by a pair of aligned rails, of an ejector comprising, a member having a shoulder alignable with one of said rails, the upper half of said shaft being exposed adjacent said shoulder, and means for moving said member to disalign said shoulder with said rail and dislodge arches from said shaft adjacent said shoulder.

5. The combination with a shaft for conveying arches thereastride with their ends guided by a pair of aligned rails, of an ejector comprising, a member having a shoulder alignable with one of said rails, the upper half of said shaft being exposed adjacent said shoulder, a divider blade normally clear of arches moving on said shaft, and means for concomitantly moving said shouldered member relative to said rails and said divider blade into the path of arches on said shaft at the edge of said shoulder.

6. The combination of claim 4 wherein the member is rotatable about the shaft as an axis.

7. The combination of claim 4 wherein the member is translatable relative to the shaft.

8. The combination with a shaft for conveying arches thereastride with their ends guided by a pair of aligned rails, of an ejector at the ends of said rails comprising, a member having a pair of shoulders alignable respectively with said rails, the upper half of said shaft being exposed for the full length of said shoulders, said member having a part in the path of arches traveling on said shaft at the end of said shoulders, and said member being rotatable about the axis of said shaft to dislodge arches resting on said shoulders astride said shaft.

9. The combination with a rotating shaft for conveying arches thereastride with their ends guided by a pair of aligned rails, of an ejector intermediate the ends of said rails, comprising, one of said rails having a gap therein, said gap having a dimension lengthwise of the rail corresponding to the cumulative thickness of the number of arches to be ejected at said gap plus clearance, and a member movable into and out of said gap to open and close the same selectively, said member having a shoulder arranged to align with said rail when said member is closing said gap.

10. In a device for ejecting arches from a moving shaft having a pair of aligned guide rails extending therealong, said guide rails respectively engaging the opposite ends of arches riding on said shaft and maintaining the arches astride said shaft despite movement of said shaft, the improvement which comprises, one of said rails being interrupted, and means movable into and out of alignment with said one rail at said interruption to retain the arches on the shaft when in such alignment but release the same from the shaft when out of such alignment, said means being proportioned in the direction lengthwise of said rail to accommodate a plurality of arches and to release the same concurrently.

11. The improvement defined in claim 10 wherein said means comprises an arcuate member embracing substantially the lower half of said shaft when in alignment with said rail, and said arcuate member being rotatable about the axis of said shaft to move out of alignment with said rail and release arches therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 1,728,454 Sterling Sept. 17, 1929 2,272,669 Johnson Feb. 10, 1942 2,288,031 Schaefer June 30, 1942 2,336,606 Everett Dec. 14, 1943 2,385,618 Ekstrand Sept. 25, 1945 2,403,862 Lasko July 9, 1946 2,433,096 Doris Dec. 23, 1947 2,471,402 Bates May 21, 1949 2,502,227 Makenny Mar. 28, 1950 2,504,236 Underwood Apr. 18, 1950

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