US2917991A - Packaging apparatus - Google Patents

Description

A. B. SEGUR PACKAGING APPARATUS Dec. 22, 1959 2 Sheets-Sheet 1 Filed Feb. 11, 1957 Dec. 22, 1959 A. B. SEGUR 2,917,991

PACKAGING APPARATUS Filed Feb. 11, 1957' 2 Sheets-Sheet 2 INVENTOR/ Evy/(9M 47M ATTORNEYS.

United States Patent ice 2,917,991 PACKAGING APPARATUS Asa B. Segur, Oak Park, I11. I Application February 11, 1957, Serial No. 639,428

13 Claims. (31. 100-7 This invention relates to a packaging apparatus, and more specifically, to an improved apparatus for arrange ing bricks or other discrete ceramic units so that such units may be stacked together to form packages.

One of the principal objects of the present invention is to provide an easily operated and relatively inexpensive apparatus adapted to arrange ceramic units for strapping into transportable packages, the apparatus being effective to maintain the top surface of the stack at a substantially constant elevation while successive groups of units are added to the stack. In this connection, it is a specific object to provide an apparatus equipped with a vertically movable platform for supporting a stack of brick, the platform being movable downwardly as the size (and weight) of the stack is increased. Another object is to provide a strapping apparatus wherein the binding strap is cut to a predetermined length before a stack of bricks is fully formed upon a vertically movable platform and is automatically drawn about the bottom and sides of the stack as the platform descends. A further object is to provide an apparatus wherein all of the bricks approaching the stacking mechanism are oriented with their faces disposed in the same direction, the apparatus being operative to then rearrange the brick with the faces in opposing relation, thereby concealing and protecting the faces of the bricks in each stack. A still further object is to provide an apparatus having a flop-over cradle mechanism for simultaneously straightening rows of brick and for stacking the rows with the faces of the brick in opposing relation. Other objects will appear from the specification and drawings in which: I

Figure 1 is a broken side elevation, taken partly in section, and showing an apparatus embodying the present invention; Figure 2'is a broken and partly sectional rear elevation of the apparatus taken along lines 22 of Figure 1; and Figure 3 is a vertical sectional view of the apparatus taken along lines 33 of Figure 1 and showing, in addition, the strap reels, and cutoff mechanisms which form a part of the apparatus.

' In the embodiment of the invention shown in the drawings, the numeral generally designates a packaging apparatus having a verticalfframe portion 11 and a conveyor frame portion 12.

The conveyor ,frame 12 comprises a 2,917,991 Patented Dec. 22, 1959 The vertical frame 11 comprises a pair of rear frame members 15 and a pair of upstanding front frame members 16. Horizontal frame members 17 extend between the front and rear members adjacent the upper ends thereof and at substantially the same level as the proximate endof the conveyor frame. The lower ends of the upstanding frame members may be imbedded in the floor or ground surface 18, or may be secured thereto in any other appropriate manner.

Preferably, the paired rear frame members 15 each has a generally U-shaped cross-section to provide opposing channels which receive and guide the wheels 19 of a vertically movable strapping platform 20 (Figure 1). In the illustration .given, the movable platform comprises a pair of- L shaped cantilever arms 21, the vertical portions of the'arms being connected to wheels 19 while the horizontal'portions of the arms project forwardly towards the front'frame members 16. Spaced, parallel beams 22 extend horizontally and transversely across the horizontal portions of the arms and are rigidly secured thereto by means ofbrackets 23. Between each of the two sets of parallel beams are journaled a series of rollers 24 for movably. supporting a stack of ceramic units during a strapping operation.

a The strapping platform 20 is movable along the vertical frame between afully raised position wherein rollers 24 are at substantially the same elevation as the nearest of the transverse rollers carried by the conveyor .frame and a fully lowered position wherein the transverse beams 22. are aligned with a roller-providing discharge conveyor 25. Counter-weights 26, 27 and 28 are spaced along a chain 30 which in turn is connected to a cable 31 entrained about pulley 32 and connected at its opposite end to an ear 33 projecting rearwardly from the strapping platform. These counterweights urge the platform into its raised position and serve to maintain the platform at selected elevations as successive groups or loads of ceramic units are stacked thereon. Preferably, at least one solenoid actuated stop assembly 34 (Figure 2) is provided by the upstanding rear frame members 15 and is engageable with the strapping platform to prevent further descent of that platform when it supports a full complement of stacked brick and while the complete stack carried by the platform is being strapped. The stop is electrically actuated into releasing position by depression of control button 35 (Figure 1) so that when the control button is pressed by an operator the loaded platform will drop downwardly into its lowermost discharging position,

adjacent discharge conveyor 25. p

'As noted above,-rows of bricks are placed upon the conveyor-frame portion 12 with the smooth edges or faces of the bricks directed upwardly. The apparatus of the present invention is equipped with a flop-over pair of parallel frame members 13'inclined slightly from show each transverse row composed of ten adjacent bricks, it will be understood that. a smaller or greater number O f bl'lgk? may be provided in each row.

mechanism, designated generally by the numeral 36, for reorienting the bricks of selected rows in faceop posing relation; The flop-over mechanism essentially comprises a power driven cradle 37 having a generally U-shaped configuration and extending across the conveyor frame at a spaced distance thereabove. The cradle is provided with a central shaft 38 journaled in a pair of upstanding arms 39 secured to the conveyor frame members 13. As shown in Figure 1, the cradle is carried by the arms 39 for pivotal movement about a degree are between two positions, each parallel with the plane defined by the conveyor frame; a first or receiving position wherein the cradle faces rearwardly along the conveyor frame, and a second or releasing. 'position (shown in dotted lines in Figure 1) wherein oted. between its first and second positions by a hydraulically actuated rack 40 and pinion 41, the pinion being secured to shaft 38 and the rack being an extension of a piston shaft carried by hydraulic cylinder 42. It will be understood, of course, that means other than the specific hydraulic cylinder and piston arrangementshown may be provided for shifting the cradle between receiving and releasing positions.

In Figure. 1,,it will be seen that the legs of the cradle are provided with transversely extending rollers 43 and that thecradle is dimensioned to freely receive a full row of bricks when it is in its first position and to release that row when the cradle is in its second position. In addition, it is to be noted that the cradle is disposed well above the rollers 14 of the conveyor frame and imposes no restriction upon the forward movement of rows of brick'svcarried by the frame rollers beneath the cradle. Preferably, the flop-over mechanism is secured to the inclined conveyor frame so that the ends of the cradle legs are spaced one row away from the end of that frame when the cradle is in brick-releasing position.

The flow of pressure fluid into and out of cylinder 42 through conduits 44 is controlled by solenoid valves 45 and 46 adjacent the cylinder. When push button 47 is depressed, the solenoid valves are actuated to permit upward movement of. piston rack40 under the influence of hydraulic pressure and pivotal movement of the cradle from its brick-receiving position to its second or releasing position. Reverse operation of the flop-over mechanism is actuated by a switch 48 carried adjacent the upper edge of a retractable gate or stop plate 49 atthe end of the conveyor frame and between the brickinverting mechanism and the strapping platform.

From Figures 1 and 3, it will be seen thatplate ceived by 'an aperture'd transverse beam 51 rigidly se-" cured'to therear members of'vertic'al' frame 1-1. Helicalcompression springs 52 coil upwardly about the support" bars 50 and are interposed between beam -1 and enlargements 53 of the supports. Consequently, these springs urge the stop plate 49 into the normally raised position illustrated in the drawings. 7 p Near the lower ends of the rear frame members are a pair of brackets 54 which rotatably receive a transverse shaft 55, A pulley 56 is carried centrally by the shaft 55 and rotates 'with that shaft upon depression of foot lever 57. A flexible cable 58 is connected at its opposite ends to stopplate 49 and to pulley'56so that as the foot lever pivots downwardly the lower end of the cable will wind about pulley 56 and draw the stop plate into 'a'retr'acted position below the conveyor frame. If desired, an additional pulley 59 may be carriedby beam 51 to direct the cable about that beam.

Along the conveyor frame and directly behind the flop-over mechanism is a lift mechanismdesignated generally by the numeral 60 for feeding rows of bricks into cradle 37. The lift mechanism comprises a carriage 61 which is movable in generally .vertical directions and which is equipped with transverse rollers 62 for movablysupporting a full row of bricks. The carriage is supported by a shaft 63 which is reciprocable in. a depending cylinder 64 secured to the conveyor frame. When solenoid 65 is actuated, pressure fluid flows through conduits 66 to lift the carriage into a raised position and in, alignment .with cradle 37 wheu'tlie' cradle is "in brick receiving position, as illustrated Figure '1.. O'ntheother hand, when solenoid valve '67 v is actuated, the piston shaft and carriage are moved downwardly under .the influence of hydraulic pressufe into .a lowered position wherein the carriage is disposed between the parallel members of the conveyor frame and the rollers 62 of the carriage are aligned with the rollers 14 provided by the conveyor frame.

I Solenoid f valve 65 is electiically actuated by-the-switch148oinj stop plate '49 (which also actuates" solenoid vaivewsar' engaged by the end of a strap carried by the channel cylinder 42) while solenoid valve 67 is actuated .by switch 68 within the confines of U-shaped cradle 37. Hence, as a row of bricks rolls from the raised, inclined carriage into the cradle and strike switch 68 therein, the hydraulic lift mechanism descends into its lowered position with carriage 61 in alignment with the conveyor frame. When the gate switch 48 is engaged by a load of stacked brick upon the conveyor frame, the carriage 61 again moves upwardly to feed a roW of ceramic units into the flop-over mechanism.

In Figure 1, it will be seen that carriage 61 is equipped with a depending stop plate 69 extending along the rear edge thereof and adapted to engage a row of bricks carried by the conveyor frame behind the lift mechanism when the carriage is in raised position. Therefore, advancement of bricks along the inclined conveyor frame is prevented by the stop member 69 whenever the movable carriage is in a position other than a fully lowered or retracted position.

Referring now to the somewhat diagrammatic illustration of Figure 3, spools or reels 70 and 71 are shown adjacent the vertical frame and carry metal straps 72 and 73 which are unwound from the spools during a strapping operation. The free end of strap 72 extends about a pulley 74, then between drive wheels 75 and the teeth of solenoid cutter 76 and finally into a channel support 77 provided by the vertical strapping frame. Preferably, the channel support has a generally U-shaped cross-section (Figure 1) for receiving and supporting the strap, and comprises two laterally-extending portions secured to the horizontalframe members 17 and projecting outwardly from oppositeside's of the vertical frame. As shown in Figure'S channel 77 is equipped at'its endwitha terminal switch 78 which actuates solenoid cutter 76upon engagement withfth'e free end of a strap carried'by the'channel. Switch 78 also operates to'i'nterrupt the rotation of drive wheels 75, th e wheels being rotated byany suitable power means, such as an electric motor (not shown).

Similarly, thefree end of the strap 73 carried by spool 71 extends about a pulley 79, then between drive wheels 80 and the teeth of cutter 81, and finally into the laterally extending portions of a U-shaped channel support 82. In Figure 1, it will be seen that the aligned lateral portions of this channel support are secured to the respective parallel members 13 of the conveyor frame and are disposed substantially midway between the front and rear ends or surfaces of a stack of bricks supported by the conveyor frame and disposed in strapping position against support. 7

Figure 3 also shows, in diagrammatic fashion, a table or stand 84 which supports a stack of sheets 85 formed Y of a somewhat resilientmaterial, such as paper or card board. Adjacent the vertical frame (Figure 1) is an adjustable standard 86 equipped at its top with a horizontal arm 87 upon which a conventional strapping machine 88 may be hooked. The strapping machine is equipped with levers '89, and 98 which may be manipulated by an operator 'to tighten and cut a strap extending about the stack of brick carried by the vertically movable platform 20. Since the construction and operation of such strapping machines are entirely conventionaha more detailed description herein is believed unnecessary. v v

Ifdesircd, the inclined conveyor frame 12 may be equipped with a standard 91 for releasablysupporting another strapping machine 92. This strapping machine is entirely conventional'and is similar in structure and operation to the strapping machine 88 which is detachably hooked upon horizontal arm 87.

mechanism is switched to an"on" positio'nby afli'rnit switch 93 (Figure 1) secured to vertical frame 11- ad jacent the top thereof and engageable with platform 20 when that platform reaches a fully raised position. The power means for rollers 80 is switched on by depression of push button 47 (Figure 1) which also actuates movement of the cradle 37 from receiving to releasing position.

a In the operation of the packaging apparatus, bricks or other ceramic units are placed upon the conveyor frame in a series of transverse rows and these rows of bricks then move downwardly along the conveyor towards the gate or stop plate 49. The rows of bricks, designated in the drawings by the letter X, pass over the retracted lift carriage 61 and beneath the cradle 37, and come to a standstill upon that portion of the conveyor frame illustrated in Figure 1. As counterweights 26, 27 and 28 pull the vertically movable platform 20 into a fully raised position between horizontal frame members 17, switch 93 is engaged by the platform and actuates the driving means for wheels 75 which then feed strap 72 into channel support 77. The operator, standing in front of the vertical frame 11, then presses switch 48 which causes the hydraulically operated cradle to pivot into brick-receiving position and, at the same time, actuates the hydraulic cylinder which lifts carriage 61. When the inclined carriage has moved into the raised positionillustrated in Figure 1, the row of bricks supported thereby move downwardly and forwardly into cradle 37 and trip switch 68 Within the cradle. When switch 68is engaged, the flow -of pressure fluid in cylinder 64 is reversed and carriage -61 begins to move downwardly towards retracted position.

As the carriage moves downwardly, the operator presses push button 47 which initiates operation of strap feeding wheels 80 and also causes cradle 37 to begin pivoting along its arc of movement between receiving and releasing positions. While the cradle swings towards its second or brick-releasing position, the operator draws a sheetof paper from stack 85 and places it upon the foremost row of upwardly facing brick disposed against stop plate 49. Upon movement of the cradle into its second position, the row of inverted bricks carried thereby begin to slide downwardly and forwardly out of the inclined cradle and are guided by the operator onto the papercovered row of bricks in the foremost position. As a result, a stack is formed composed of two rows of bricks arranged with their faces in opposing relation with a sheet of resilient material therebetween.

When the top row of inverted bricks slides into engagement with stop plate 49, switch.48' again'c'auses the cradle to move into its brickreceiving position and also causes carriage 61 to move upwardly. into'its raised position. Meanwhile, strap 73 has passed along channel support 82 below and on opposite sidesof the stack of bricks andhas engaged switch 83 which 'actuates cutter 81. The operator simply drawsv the opposite ends offthe cut section of strap about the group of stackedbrick and manipulatesthe strapping machines; to draw the bricks into a tightpackage. Foot pedal 57 is .then depressed to retract gate 49 andthe strappedj'package 'o f bricks is.

moved onto platform 20. i p K Preferably, foot pedal 57 is released shortly before the package of stacked brick clearsstop plate49 so that springs52 will operate to raisejthe plateorgate immediatelyafter the strapped packag'ehajs passed over it. Con sequently, the row of bricks immediatelyfollowing the strapped group will engage the gate and be held in position at the strapping station 'Since carriage 61 is above the level of the conveyor frame at the time the strapped package is placed upon the vertically 1 movable platform,

However, the weight of the platform and the group of strapped bricks carried thereby is less than the weight of counterweigh ts 26 and 27 combined. Therefore, the partially loaded platform moves downwardly a distance equal to the length of chain 30 between weights 26 and 27 to position the top surface of the strapped package at the level. of horizontal frame members 17. It will be noted that as the platform descends, the cut sectionof strap v72 moves downwardly between horizontal frame members 17 and is pulled snugly against the sides of the package. I i

.The above procedure is then repeated, the operator pressing push button 47 to actuate the flop-over mechanism and position a row of inverted bricks on top of the foremost row carried by the conveyorframe- After the second group composed of two rows of bricks in faceopposing relation has been strapped, gate 49 is again dropped and the strapped package is placed upon the first package supported by the vertically movable platform. The platform descends under the additional weight of the second package and stopsat a lower position wherein the weight of the two packages plus the platform itself is sufiicient only to overcome the weight of counterweights 26 and 27. When the third strapped package is placed upon the platform, all three counterweights are lifted off of the floor surface and the platform descends into the position illustrated inthe drawing wherein the platform engages solenoid stop assembly 34 and is held in a position suitable for the strapping of the entire load by strapping machine 88. When the platform supports a full load and engages stop assembly 34, the ends of the cut segment of strap 72 will point upwardly because of the engagement between that strap and horizontal frame members 17, as represented by broken lines in Figure 3. grasped by an operator and inserted into the strapping machine 88. Manipulation of handles 89 and 90 draws the strap segment tightly about the entire stack carried by the platform and forms a single large package of brick. After the entire stack has been strapped, the operator depresses button 35 to retract the stop member of solenoid stop assembly 34. The loaded platform then descends to its fully lowered position wherein rollers 24 are at substantially the same elevation as the rollers of discharge conveyor 25. The operator urges the fully strapped package off of the platform and onto the discharge conveyor, and the above-described operation is then repeated.

To provide a means for picking up and moving the large strapped packages at a job site by a warehouse loading truck and to facilitate removal of the strapped packages from the discharge conveyor by means of a fork-lift truck or other carrier, finger brick designated by the letter Z may be interposed between two of the smaller package units of the stack to provide space between the component package units for receiving the lifting and supporting mechanism. Preferably, these finger bricks are manually placed upon the first or lowermost unit and at opposite ends thereof after that unit has been shifted on to the vertically movable platform 20.

While the drawings illustrate a machine for arranging three groups of face-opposing brick to form a single large package, it is to be understood that the present invention is applicable to a packaging machine adapted for the strapping of a greater or smaller number of such groups.

place a metal screen or other suitable divider between the I Therefore, the ends of the strap may be easily air' of rows in face 7' finger brick and jthe'intermedia te group to prevefiitthe bricks of that group: from iii'oving'into the space intended to 'accbmii odate' thesupponin'g mechanism-of a 'lifttruck or b h' i's f sn It will benoted that the" op{ ver mechanism performs the dual function of inverting rows of bricks to place a i V posing r ela tiongand of'straight'eninga row of bricks during invertingoperation. In other ords, whenthecradle reachesthe top of its arc tal move ch t, any-loosely held bricks which do not engage thebase of th dle will shift downwardly under their own weight sothatfthe ends of all the bricks within the confines of thecradle' are aligned. Since 'stop plate 49 tends to 'longit allyalig n all "of thebricks of the foremoSt'row ted b y conveyor frame 12, the present apparatus 'operates 'to arrange the bricks of the two tac'e-dppbsihg rows ihto' neat packages 'at the first strapping station. A l I 7 V The structure of the invention is concerned primarily with the arrangement andstrapping of single-face brick. However, it is evident that thispackaging apparatus may also be usedin connection'with the packaging of double-fac'e'orfaceless 'brickpand that other discrete ceramic units, such as-tile, rnay 'also be packaged by an apparatus embodyin'gthe present invention.

While in the foregoing lhave disclosed my invention in considerable detail forfpufposes of illustration, it will be understood by those skilled in the art that many of these details may be varied considerably without departing-from the spirit and scope of the invention.

1. "In a brick :strapping apparatus, an elongated and inclined conveyor ad ped for supporting a group of upwardly-facing bri ks arranged initransversely extending rqws, said conveyor"providinga carriage having an inCIinedbrick suppor surface atfall times parallel with said conveyor and "being movable between lowered and raised positions for lifting at least one row of bricks above said group, and brick-inverting means provided above said conveyor'for receiving a row of bricks lifted by said carriage and inverting'and stacking the same into face-opposing relatidn with a row of bricks carried by said conveyor thereibelow. V p

2. The structure of claim l in which said brick-invertin'g means comprises a iradle pivotally 'mou'nted upon said conveyor for pivotal movement about a transverselyex-tending line and between 'abrick receiving position facing said carriage anda brik releasing"position facing away from said carriage, said cradle providing a bricksupporting surface parallel 'with sai'd 'conveyo r when said cradle 'is both in said brick receiving-position and said brick-releasing position;

3. The stnlcturebf claim 1 in which said conveyor is equipped with transvers ely ex te'nding roller's for rnovably supporting said group of bricks.

4. The struc ture of claim 1 'in which stop'means are provided "said "carriage' for' preventing movement of bricks beneath tliesarne when said carriage is-in raised position. v

5. In a brick strapping' app'aratus, an elongated'conveyor frame for supporting a longitudinally extending seriesof upwardly facing brick arranged in transversely extendingrows, a cradle 'a'daptedto carry at least one row of said bricks fand'bein'gfmount'ed in spaced'relation above's'aid frame for pivotal im ov'erne'nt about an upweirdly ext ending between 'fo'ppe' ing first and second.

positions, a carriagecoinpr'ising a movable section of said conveyor frame, said eenage being movable between a raised position for liftingat least'one row of bricks above said series Yand'f'or feeding said row into said cradle when the cra'dleisin its firstp'ositi'on and a lowered position for' 'permi'ttin g the' passage'of rows 'of bricks faljo'ng said-eddy r-fianie below said {cradle means for "pivoting ciadIe; and "m'e'anflor lifting and lowering said carriage, whereby as said cradle is pivoted'between first and second positions a row of brickscarried thereby is inverted and disposed in face-opposing relation with a row of bricks carried by said frame there below;

6 The structure of claim 5 in which said carriage is inclined and is equipped with transversely extending rollers' for movably supporting said row of brick.

7. The structure of claim 5 in which said carriage is inclined and is provided with a lower end, said frame I also providing releasable stop means at the lower end thereof for holding a row of bricks in position upon said frame while said pivotal cradle directs an inverted second row thereupon.

8. The structure of claim 7 in which a vertical frame is provided adjacent said releasable stop means, said vertical frame being equipped with a strapping platform I mounted for vertical movement into selected vertical positions therealong, whereby, when said stop means is released groups of bricks arranged in face-opposing rows are movable from said inclined frame and onto said vertically movable platform.

9. The structure 'of claim 8 in which counterbalancing means are connected to said platform for controlling the vertical position thereof as successive groups of brick are stacked thereon "and for maintaining a top of a stack supported by said platform at substantially the same elevation as the lower end of said conveyor frame.

10. In a brick packaging apparatus, a vertical frame, a strapping platform mounted upon said frame for vertical movement into selected vertical positions therealong, a conveyor adjacent said frame for delivering successive groups of ceramic units to said platform for stacking-the same thereon, and counterbalancing means comprising a series ofcounterbalancing weights connected to above said platform, said channel supports slidably receiving opposite end portions of the metal strap with a central portion of said strap disposed between said platform and a stack of bricks supported thereon for directing said end portions upwardly along opposite sides of the stack as the strapping platform descends.

11. In a brick strapping apparatus, a frame, a ver tically movable strapping platform, carried by said frame, aninclined'conveyor adjacent said frame for delivering successive groups of ceramic units to said platform for v stacking the same thereon, a releasable stop disposed between said inclined conveyor and said frame, said stop being movable between raised and lowered positions and when in raisedpositionproviding a surface'facing, said inclined conveyor at substantially right angles thereto for preventing advancement of bricks from said conveyor to said platform under theinfluence of gravity, and'means cooperating with said platform for controlling vertical movement thereof as successive groups of ceramic units are stacked upon the same and for maintaining a top 'of a stack of units supported upon said platform at a substantially constant elevation as the platform descends,

said'frarne'being' provide'd with a pair of longitudinally aligned channels for guiding a strap across the frame and above said platform, said channels being spaced longitudinally apart and slidably receiving opposite end portions of said strap for directing said end portions upwardly alongside the stack of units carried by the plat-" form as said platform descends.

Y 12. In a brickpackagingfapparatus, a 'vertic'al frame? =a 'st'rappingplatforin mounted =u'pon said frameforvrtical movement into selected vertical positions therealong, and a conveyor adjacent said frame for delivering successive groups of ceramic units to said platform for stacking the same thereon, said frame being provided with a pair of laterally extending and longitudinally aligned channel supports for guiding a metal strap across said frame above said platform, said channel supports slidably receiving opposite end portions of the metal strap with a central portion of the same disposed between said platform and a stack of bricks supported thereon for directing said end portions upwardly along opposite sides of the stack as the strapping platform descends.

13. In a brick strapping apparatus, an elongated conveyor adapted for supporting a group of upwardly-facing bricks arranged in transversely extending rows, said conveyor providing a carriage having a brick-supporting surface at all times parallel with said conveyor and be ing movable between lowered and raised positions for lifting at least one row of bricks above said group, and

brick-inverting means provided above said conveyor for receiving a row of bricks lifted by said carriage and for inverting and stacking the same in face-opposing relation with a row of bricks carried by said conveyor therebelow.

References Cited in the file of this patent UNITED STATES PATENTS 1,341,798 Graham June 1, 1920 1,639,576 Semashko Aug. 16, 1927 1,661,969 Semashko Mar. 6, 1928 2,234,990 Todhunger Mar. 18, 1941 2,324,930 Joa July 20, 1943 2,593,588 McDonald Apr. 22, 1952 2,667,259 Parker Jan. 26, 1954 2,814,397 Connell Nov. 26, 1957 FOREIGN PATENTS 612,761 Great Britain Nov. 17, 1948

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