US2658267A - Spring winding machine - Google Patents

Description

Nov. 10, 1953 P. .1. BIANCO SPRING WINDING MACHINE 4 Shjeets-Sheet 1 Filed Nov. 2, 1949 Nov. 10, 1953. P. J. BIANCO 2,658,267

SPRING WINDING MACHINE Filed Nov. 2, 1949 4 Sheets-Sheet 2 y @z i a attorneys 3nvenfor Nov. 10, 1953 P. J. BIANCO 7 7 spams wmnmc MACHINE Filed Nov. 2, 1949 4 Sheets-Sheet s A R A Nov. 10, 1953 P. J. BIANCO SPRING WINDING MACHINE 4 Sheets-Sheet 4 Filed Nov. 2, 1949 lnvcntor @1 2 cfffkwcv Patented Nov. 10, 1953 UNITED PATENT OFFICE Peter J. Bianca, Detroit, Mich a'ssignor to General Motorsfcorporation, Detroit, Mich., a corpor'ation of Delaware Application November'2, 1949, Serial No. 125,077

i i'claim's.

This invention relates to spiral or clock type springs and more particularly to a machine for automatically winding such springs and installing them in wound condition in the mechanisms in which they are to function. I

Suck clock type springs have come into fairly general use in manuallyoperated wfindow lift mechanisms, deck lid-supports. door hinges, etc", of automotive vehicles "for example wherein the clock spring exerts -a biasing force 'to fold or unfold a pair of 'hin'gedlinks. Since these springs are most commonly "emailed a pre-stressed or partially wound condition, a definite 'need has arisen for power actuated means to efiec't initial spring winding operation and the instal-- lation of the Dre-wound springs in the 'mechar nisms in which they are to function. This, particularly the case with springs which are relatively stiff and -difiicu'lt or impossible to prewi'nd manually. i 7. Accordingly, it "the principal object. 01E my invention to provide a ower operated'macnine for automatically windingclockftype springs and installing them inthe mechanisms in which they are to function.

In the drawings: i I c Figure 1 is a. front "elvational view of apreferred embodiment 'offa machine in accordance with my invention forfwindi'ng and installin springs in automotive vehicle'window regulating devices, certain parts being shown in section.

'Figure 2 is an enlarged detail view similar to Figure 1 showing the relation of the parts just prior to the start. ar a springwinding operation.

Figure 3 is an exploded view in'p'e'rspec'tive of certain parts associated withv the lower end of the spring winding rain. 4 I

Figure 4 is a'per'spective view of the-cam'member for effecting windup of 'the spring during the. driving'stroke of therain. v v Figure 5is an enlarged detail view similar to Figure 1 showing'the'transfer of'the-wound clock spring from the camfto'the window regulating device. V I g Y, r Figure 6 is a detail sec'tion'al 'view taken on line 6-6 of Figure 1 showing the relationship of the clock spring with'the cam duringthe spring winding operation. I

Figure 7 is a fragmentaryplan view of a conventional window regulator device with its wound clock spring installed. 4 g

Figure 8 is a sectional plan view taken substantially on'line8- 8 of Figure l. h

Figure/9 is'fan enlargeddetail sectional view taken substantialb' on line.9,9 ofFigure 1.

CJI

Figure 10 is an enlarged sectional plan view taken substantially on line l0-l0 .of Figure 1.

Before beginning a. detailed description of the elements shown in the drawings, my machine may be briefly described as comprising a stationary frame supporting a horizontally reciprocating carriage which includes a cam in the form of a hollow tube through which the clock spring to be wound is delivered to the window regulator assembly held in a fixture below. In the initial position of the carriage said tube shaped cam receives one spring from a gravity fed magazine above. Upon-starting the machine, the carriage moves horizontally to a position at which the tube is aligned with thespring center post of the window regulator mechanism, following which a vertical ram automatically moves downward and pushes the spring through the tube. In so doing the spring is wound up by the ram holding its inner end against rotation while the outer end of the spring travels in a helical camming slot formed in the wall of the tube. Continued downward movement of the ram pushes the Wound spring finally out of the camming tube and onto the window regulator assembly. The ram then automatically-retracts and after reaching its upper positionthe carriage including the camming tube returns to its initial position at whic'hfitreceives another springfrom the magazine. The operator can now replace the regulator assembly with its wound spring with another and the operation repeated.

Referring now to Figure 1 the numerals 1, 2, 3 and] designate generally the frame of my machine, the horizontally reciprocable. carriage, the vertically reciprocable ram, and the window regulating mechanism, respectively. 'It will be understood that while I have referred to the carriage 2 and ram 3 as horizontally and ver'tie cally reciprocable respectively, it is appreciated that these directions of movement could be in.- terchanged. without departing from the principles of my'invention. l

The machine frame I comprises vprincipally aback plate 5 supporting upper and lower shelves 6 and 1'. 8 and 9- 'are gusset "plates servin glto brace the upper shelf '6. on the back platej li. Similarly, anchor pl'ates T0, H, [2 and i3 secure the lower shelf in place. The :upper shelft is apertured at for passage of the vertically reciprocable 'ram =3 and adjacent theglatter is provided with an opening through which the. lower end of a. cylindrical magazine 1.6, extends. Thismagazine, which-has a-slot 1;! in its gside wall.;and extending the full length thereof, is

secured to the upper shelf 6 and back wall of the machine frame as by suitable upper and lower brackets l8 and I9. On the lower shelf 1 and directly opposite the ram 3 is provided a platform 26 which is suitably arranged to support and locate the window regulating mechanism 4 while the latter is being delivered its wound clock spring 21.

The carriage 2 includes a plate 38 which as shown in Figure 9 is slidably guided at its front and rear edges between ways 3|, 32 and 33 supported in downwardly hanging brackets 34 from the upper shelf 6. This plate 38 is apertured adjacent one of its ends to receive the upper end of the camming tube 36 through which the ram 3 passes in effecting the winding and delivering of a clock spring to the window regulator mechanism 4 below. Directly above the entrance to the upper end of the camming tube 36 is a ring 31 having a slot 31' and bore 38 providing a free sliding fit for the clock spring 21 in its initial unwound condition. The upper end of this bore 38 is chamfered as at 39 (Figure 2) to facilitate the spring dropping into place when the carriage 2 is positioned with the ring 31 directly under the spring magazine |6, at which time the slot 31 in the ring is also aligned with the slot IT in the magazine. The lower extremity of this bore 38 is provided with an inturned conical shoulder 48 which serves as a shelf for temporarily retaining the spring within the bore 38 during travel of the spring with the carriage from the magazine I6 to its subsequent position under the ram 3. The camming tube 36 which is fixedly secured to the carriage plate 38 directly below and aligned with the ring 31 has a bore 42 of the same diameter at its upper end as that of the restriction provided by the conical shoulder 48. This bore 42 is preferably tapered inwardly from its upper end towards its lower end in order to compensate for the reduction in out side diameter of the springs as they are wound up in being passed through the camming tube 36.

As best shown in Figure 4, this camming tube 36 is provided with a helical slot 43 in its cylindrical wall 44, the helical pitch of this slot being selected to effect the desired degrees of windup of the spring, which in the particular embodiment shown amounts to approximately 130. The purpose of the slot 43 is to cam the hook shaped outer end 46 of the clock spring 21 rotatively about the axis of the tube 36 during the passage of the spring therethrough. The engagement of the hook shaped outer end 46 of the clock spring with the slot 43 is shown in Figure 6.

The vertically reciprocable ram 3 which serves to push the spring through the camming tube comprises a shaft 58 to the lower end of which is attached a swiveled head 5|, the latter being retained thereon by a pin 52 anchored in the head 5| and engaging a peripheral groove 53 formed on the shaft 58. This head 5| as best shown in Figure 3 is generally cylindrical in shape to receive the lower end of the shaft 58 and is provided with a plurality (3 as shown) of slots 54 extending through its side wall and upwardly from its lower end. Hinged fingers 55 swingably carried on pins 56 in the head 5| are positioned in the slots. The upper ends of the fingers 55, above the hinged pins 56, are urged toward each other by a garter type spring 51 which engages the fingers in grooves 58 provided therein and encircles the head 5| within a peripheral groove 59. The lower end of each of the fingers 55 carries a foot 68 which abuts the upper surface of the clock spring at circumferentially spaced positions thereon for forcing the spring through the camming tube 38. One of the feet 68 is preferably provided with an outwardly extending projection 6| which also engages the helical groove 43 in the camming tube and bears downwardly on the clock spring outer end 46 during winding to insure against any possibility of distortion of the clock spring as might result from the springs outer end 46 binding in the camming slot 43. A conventional ball thrust bearing 62 (Figure 1) is interposed between the the interaction of the finger projection 6| with the camming slot. It will be understood that the pin 52 has a sufliciently loose fit in the groove 53 to permit the bearing 62 to take the thrust loads on the head during downward movement of the ram. Screws 64 are carried by the upper ends of the fingers 55 in position to abut the periphery of the ram shaft 58 for adjustably limiting the action of the garter spring 51.

Referring to Figure 8 it will be seen that the ram shaft 58 is keyed against rotation about its axis by a key 66 in a slide 61 which is guided for slidable vertical movement in ways 68 and 69 attached to the back wall 5 of the machine frame. An enlargement or collar 18 formed on the upper end of the shaft 58 anchors the latter against longitudinal movement in the slide 61 and is retained in place therein by a cap 1|.

Means for effecting the raising and lowering of the ram 3 is provided in the form of a double-acting fluid operated cylinder 14 (Figure 1) in which is mounted a piston (not shown) having a piston rod 15 which is fixedly connect ed to the slide 61. The laterally extending arm 16 carried by the slide is provided with upwardly and downwardly extending switch actuating cam members 11 and 18.

A similar double-acting fluid operated cylinder 88 (Figure 1) attached to the underside of the upper shelf 6 is provided for eifectingthe horizontally reciprocating movement of the carriage 2. The piston rod 8| of this cylinder is fixedly connected to one end of the carriage plate 38, and a bolt 82 extending from the opposite end of this plate is arranged to slidably pass through a side portion 83 of the machine frame during carriage reciprocation, the head 84 of this bolt serving as a stop for limiting travel of the carriage to the right as viewed in Figure 1. For limiting travel of the carriage in the opposite direction, there is provided cooperating abutments 85 and 86 which are anchored opposite each other in the carriage plate 38 and the frame portion 83. Other abutments (not shown) may be similarly employed to limit the extreme positions of the vertical ram 3. The carriage plate 38 carries by means of the bracket 81 a switch actuating cam 88.

As means for holding the inner end 88 of the clock spring 21 from rotating during its windup while being pushed through the camming tube 36, the extreme lower end of the ram shaft 58 carries a nose piece I88. This nose piece is in the form of a short rod telescopically slidable in a socket |8| provided in the end of the ram shaft 58. Key I82 carried by the nose piece and slidable in a groove I83 in the wall of the socket |8| serves to prevent rotation of the nose piece in the latter. To provide for retrac- -conical shelf 48 in the bore of the ring .31.

menace? tion at the nose piece into the socket m upon the clock spring 21' being delivered to the window regulator mechanism, a compression spring I84 is located between the nose piece and the inner extremity of the socket I8I. A set screw I85 projects through the wall of the ram shaft 58 and into an elongated slot I88 in the surface of the nose piece to retain the latter against dropping out of the socket when the ram is in elevated position. The lower end I81 of the nose piece I88 is bifurcated to receive and hold the inner end 89 of the clock spring against turning during the winding operation. As shown in Figure 5, the bifurcation at the lower end of the nose piece is disposed in the same vertical plane as the bifurcation in the pivot pin I88 which forms a part of the window regulator assembly 4. To ensure against any downward strain upon this pivot pin I88 during installation of the wound clock spring, there is provided an adjustable fixed abutment member I89 having a head I I8 at its upper extremity which serves to support the pivot pin I88 as the clock spring reaches its seated position thereon.

Mounted to the back wall 5 of the machine frame are three electric current limit switches 88, 9| and 92 positioned such that depression of their respective spring biased switch operating buttons (93 and 94 for switches 9| and 92 being shown) is subject to engagement by the cams I1, 18 and 88 respectively. By means of conventional electrically responsive valves and interlocking circuit connections (not shown), these switches serve to control the pressurizing of the respective ends of cylinders I4 and 88 to obtain the sequential timing of events in the operation of my machine as will now be described.

,In the initial position, i. e., with the machine at rest, the carriage 2 is at its extreme lefthand position with the camming tube 38 directly under the spring magazine I6 from which the lower-most spring 21 will drop by gravity into the ring 31. Ram 3 at this time is at its extreme upper position, its switch actuating cam 11 depressing the switch actuating button of switch 98. Upon the operator manually actauting a starting switch (not shown), fluid under pressure is admitted to the left-hand end of cylinder 88, causing the carriage 2 to travel to the right to its position as viewed in Figure 1. The clock spring to be Wound is thus transferred by the ring 31 to a position directly below the ram 3, and the carriage npon reaching this position effects the actuation ofswitch 92 by the switch actuating cam 88 which in turn causes fluid under pressure to be admitted to the upper end of cylinder 14. As a result, the ram 3 is moved downward, the fingers 55 and nose piece I88 moving into contact with the clock spring in the ring 31 and forcing the spring into and through the camming tube 36. At the startof this downward movement of the ram the switch actuating cam 'I'I carried therewith moves out of engagement with the contact button (not shown) of switch 98, causing the latter to set up a holding circuit which maintains the pressurizing of the left- .hand end of cylinder 88.

The initial downward movement of the clock sprin by the ram fingers 55 and nose piece I88 cause the clock spring to contract slightly in passing through the restriction provided bythe As the clock spring continues on downward through ithe inwardly tapered bore 42 of the camming tube 36 the clock springs outer end travels'inthe helical slot 43 while its inner end is held against rotation by the nose piece I88, and the feet 88 on the ram fingers 55 are caused to bear against the upper surface of the clock springs outermost convolution due to the lever action produced by the garter spring 51 engaging-the upper ends of the fingers 55.

As the ram approaches its lower-most position the clock spring is forced out of the lower endof the camming tube 36 and into its assigned position in the window regulator assembly 4, the upstanding lug III of the latter serving to an chor the outer end 43 of the spring as it leaves the camming s-lot- 4-3 and the bifurcated upper end of the regulator pivot pin I88 simultaneously anchoring the clock spring inner end 89 as it leaves the bifurcation in the nose piece I88 of the ram; As will be clear from Figure 5,- the nose piece I88 contacts the regulator pivot pin I88 in advance of the ram fingers 55 moving the clock spring to its fully seated position on the regulator assembly, the nose piece biasing spring I84 serving to accommodate the retraction of the nose piece into its socket I8'l as the fingers 55 continue moving downward to the limit of travel of the As the ram reaches its lower-most position, the switch actuating cam' I38 carried thereby trip the button 93 of switch 9|, reversing the valvesetting controllin the pressurizin-g of cylinder I4 such that fluid is now introduced into the lower end of the latter and the ram 3 thereupon returns to its fully upraised position. Upon the switch actue ating cam I1 re-engaging the button of switch 98, the pressurizing of cylinder 88 is similarly reversed and the carriage ,2 returns to its initialex' treme position atwhich time .the lower-most clock spring in the magazine IIidrops into place in .the ring 31 preparatory to repeating the cycle just described.

The camming tube 38 now being displacedclear of the window regulator assembly on the plat form 26, this assembly can be removed and re: placed with another to which a clock spring is to be assembled.

I claim:

1. In a spiral spring winding machine, means for supporting a window regulator device in position for and pending the assembly therewith of a pre-wound clock spring, a cylinder having a helical cam track in its side wall for camm-ing the outer end of the clock spring rotatively about its inner end as the spring is passed coaxially through the cylinder, .a ram for effecting vthe passage of the Spring through the cylinder and into assembled relationwith the window regulator device, a nose piece projecting from the spring engaging end of said ram and anchored against rotation about the r'am axis during said passage of the spring, said nose piece having a portion adapted to engage and prevent rotation of the nner end of the spring during the passage or the spring through the cylinder.

2. In a spiral spring winding machine, a reciprocable ram having means for holding the inner xtremity of a clock type spring against rotation aboutthe spring axis whileapplying an axial force to the outer convolution of the spring, a tube through which the ram is reciprocated provided with a helical cam surface for ca'mming the outer extremity of the springabout itsinne'r extremity during movement of the rain in one direction, and means for effecting the reciprocationof the ram.

3. In a. spiral spring .wlndingmachine, aneurotatable helically slotted member through which a spiral spring may be passed with the outer end of the spring slidably following the helical slot, a ram receivable in said member for effecting the passage of the spring therethrough, means on one end of said ram in abutment with the outer-most convolution of the sprin during its passage through the member, and other means on said ram restraining rotation of the inner end of the spring during its passage through the member.

4. In a spiral spring winding machine, a member accommodating the endwise passage therethrough of spiral springs to be wound, a helical cam track within said member for camming the outer ends of the spiral springs about their spiral axis during passage of said springs through the member, a ram arranged to apply endwise thrust to the springs for effecting their passage through th member, and means securing the inner ends of the springs against rotation about the helical axis of the cam track during passage of said springs through the member.

5. In a spiral spring winding machine, a frame, a ram reciprocably mounted thereon including a shaft portion restrained by the frame from rotation about the longitudinal axis of the ram, a head swiveled to one end of said shaft portion, a plurality of spring driving fingers recessed in the outer periphery of said head and hinged thereto intermediate their ends, said fingers extending generally longitudinally of the ram axis and provided with resilient means urging their extended ends outwardly from each other, mean limiting the outward movement of said finger ends, a nose piece slidably socketed in the shaft and keyed thereto against rotation about the ram axis, said nose piece having a bifurcated end adapted to rotatively lock the inner end of a spiral spring to be wound, resilient means urging the nose piece outwardly of its socket in the shaft, an inwardly tapered tube into which said ram is reciprocable, said tube being mounted on the frame for reciprocation transversely of the ram, the internal wall surface of said tube being provided with a helical track rotatively camming the outer end portion of the spiral spring being wound during movement of the spring through the tube by the ram, power means for reciprocating the ram, a cylindrical magazine fixed to the frame adjacent the ram for feeding springs to be wound to the tube, and means for reciprocating said tube between positions of alignment with the magazine and ram respectively.

6. In a spiral spring winding machine, a reciprocable carriage including a tube having its longitudinal axis perpendicular to the reciprocatory path of the carriage, said tube having a helical slot in its wall for rotatively camming the outer end portion of a. spiral spring about said axis during passage of the spring coaxially therethrough, a stationary spring feeding magazine positioned to register with one end of the tube when the carriage is at one end of its stroke, a reciprocable ram positioned to move coaxially into and out of the tube when the carriage is at the opposite end of its stroke, means on the ram for transmitting end-wise thrust to the outer convolution of the spiral spring, a member on the ram arranged to engage and prevent rotation of the inner end of the spring during movement of the spring through the tube by the ram, means for supporting a spring receiving device in position to receive the spring as the ram ejects it from the tube, and power means for effecting the reciprocatory strokes of the'carriage and ram in timed relation to each other.

7. In a spiral spring winding machine, a frame, a member mounted thereon and provided with a generally cylindrical bore accommodating the endwise passage of spiral springs during winding, the Wall defining said bore having a helical slot engageable by the outer ends of the spiral springs during their passage through the bore, said member having a portion provided with an aperture coaxial with said bore through which spiral springs to be wound may be axially advanced into one end of said bore, said aperture including a slot in registry with the adjacent end of said helical slot and an inclined shelf for temporarily retaining a spiral spring prior to its advancement into the bore, a ram mounted on said frame for reciprocation coaxially of said bore, a head swiveled to the ram, fingers pivotally connected intermediate their ends to said head, said fingers having ends adapted to transmit axial thrust to the spiral springs for effecting the advancement of the springs through said aperture and bore, one of said finger ends having a portion arranged to travel in the slots of said aperture and bore during advancement and retraction of the ram, a garter type spring engaging the fingers adjacent their opposite ends and urging their spring driving ends outwardly of each other toward the wall of said bore, and means carried by the ram operative to hold the inner ends of the spiral springs from rotating during their passage through the bore.

8. In a spiral spring winding machine, a frame, a member mounted thereon provided with a generally cylindrical bore for guiding the axial passage of the springs during winding, the wall defining said bore having a helical slot engageable by the outer ends of the spiral springs during their passage through the bore, a ram reciprocably mounted on the frame and rotatively carry ng a plurality of fingers arranged to transmit thrust to the outer convolutions of the springs in the bore, one of said fingers having its spring thrust transmitting portion arranged to project into the helical slot, means for urging the thrust transmitting portions of all the fingers outwardly of each other, and a means carried by the ram and slidably keyed to the frame for holding the inner ends of the springs from rotating during their passage through the bore.

9. In a machine for winding spirally preformed springs the opposite ends of which terminate in radially projecting portions, a frame, a ram reciprocably mounted on the frame, a carriage reciprocably mounted on the frame for movement transversely to the ram, said carriage having a spring receivable opening accommodating passage of the ram therethrough when the carriage is at one end of its reciprocatory stroke, a spring magazine fixed to the frame and in spring feeding registry with said opening when the carriage is at the opposite end of its stroke, means within said opening for supporting a spring to be wound while said spring is being transferred from its position opposite the magazine to its position opposite the ram, a camming tube carried by the carriage having a bore aligned with said opening through which the spring may be driven by the ram, the surface of said bore being helically slotted to receive and cam the outer end portion of the spring rotatively about the spiral axis of the spring during passage of the spring therethrough, said ram including a member keyed to the frame against rotation about said axis, said member terminating in a bifurcation receiving and restraining rotation of the inner end of the spring during its passage through the tube, and means for alternately reciprocating said ram and carriage.

10. In a spiral spring winding machine, a reciprocable carriage including a tube through which the springs are coaxially driven during winding, said tube having an annular bore perpendicular to the reciprocatory path of the carriage, a helical slot formed in the surface of said bore having a continuous rotative camming engagement with the outer ends of the springs during their passage through the tube, a ring mounted on the carriage having means for temporarily supporting an unwound spring in position to enter said tube, a stationary spring magazine in spring feeding relation with said ring when the carriage is at one end of its stroke, a spring driving ram mounted for reciprocation into and out of said ring and tube when the carriage is at the opposite end of its stroke, a frame fixedly supporting the magazine and slidably supporting the carriage and ram, a ram carried member slidably keyed to the frame and adapted to restrain rotation of the inner-ends of the springs as the springs are driven through the tube, and means for reciprocating said carriage and ram.

11. In a spiral spring winding machine, means for guiding axial movement of the spring during winding, a ram for imparting said movement to the spring and having means thereon to restrain rotation of the inner end of the spring about the spring axis during said movement, and a helical cam rigid with said means adapted to impart rotation to the outer end of the spring in response to said movement.

12. In a spiral spring winding machine, a frame, an open ended annular tube mounted on said frame'having a bore slidably accommodating the coaxial passage of the springs during winding, a spring driving ram supported on the frame for longitudinal reciprocation into and out of said tube, said ram having a member keyed to the frame and adapted to restrain rotation of the inner end of the spring during passage of the spring through the tube, and a helical cam track on the bore of the tube imparting rotation to the outer end of the spring during passage of the spring through the tube.

13. In a machine for winding spirally preformed springs, a frame, a spring driving ram reciprocably mounted on the frame, a tube open at both ends through which a, spring to be wound may be axially driven by the ram, said ram having a member on its spring driving end holding the inner end of the spring from rotating during axial advancement of the spring through the tube, said tube having a helical cam surface on its inner periphery adapted to slidably guide the outer end of the spring in a rotary direction during axial advancement of the spring through the tube, and means on the frame supporting said tube during reciprocation of said ram.

14. In a machine for winding spirally preformed springs, a frame, an open ended tube mounted on the frame for lateral reciprocation, said tube having a bore accommodating the coaxial passage therethrough of springs to be Wound, said bore being provided with a helical slot for receiving and camming the outer end of the spring rotatively about the axis of the tube in response to axial movement of the spring through the tube, a ram mounted on the frame for reciprocation into and out of the tube when the tube is at one end of its reciprocatory stroke, said ram including a, shaft portion extending longitudinally thereof and keyed to the frame against axial rotation, a head swiveled to the extended end of said shaft portion, a plurality of circumferentially spaced spring driving fingers recessed in the outer periphery of the head and hinged thereto intermediate their ends, said fingers extending generally longitudinally of the ram and provided with means resiliently urging their'spring engaging portions outwardly from each other, a nose piece projecting longitudinally from said extended end of said shaft portion and adapted to lock the inner end of the spring against rotation during movement of the spring through the tube by the ram, means for reciprocating the ram when the tube is at said one end of its stroke, means for reciprocating the tube when the ram is withdrawn from the tube, and means opposite the ram entering end of the tube for temporarily supporting a spring to be wound during movement of the tube toward said end of its stroke.

PETER J. BIANCO.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 797,331 Stambaugh Aug. 15, 1905 812,779 Ackley Feb. 13, 1906 1,790,218 Appleby Jan. 27, 1931 2,296,964 Ushakoif Sept. 29, 1942 2,390,54 Lang Dec. 11, 1945

Images