US2598246A

US2598246A - Apparatus for painting motorcar bodies

Info

Publication number: US2598246A
Application number: US125443A
Authority: US
Inventors: Fowler Alexander Proud
Original assignee: Haden Drysys International Ltd
Current assignee: Haden Drysys International Ltd
Priority date: 1948-11-09
Filing date: 1949-11-04
Publication date: 1952-05-27
Anticipated expiration: 1969-05-27
Also published as: GB652720A; FR999057A

Description

May'27, 1952 -A. P. FOWLER APPARATUS FOR PAINTING MOTORCAR BODIES Filed Nbv. 4. 1949 5 Sheets-Sheet 1 Inventor 'fiowfl' A Home y y 7 1952 A. P. FOWLER 2,598,246

' APPARATUS FOR PAINTING MOTORCAR BODIES,

Filed Nov. 4, 1949 5 Sheets-Sheet 2 Inventor %ra/4de/ ZZZ aa/dw' A Home v May 27, 1952

A. P. FOWLER

8, 4

APPARATUS FOR PAINTING MOTORCAR BODIES Filed Nov. 4, 1949 5 Shees-Sheet s Attorney May 27, 1952 A. P. FOWLER APPARATUS FOR PAINTING MOTORCAR BODIES Filed Nov. 4, 1949 5 Sheets-Sheet 4 Attorney May 27, 1952 A. P. FOWLER 2,598,246

APPARATUS FOR PAINTING MOTORCARBODIES Filed Nov. 4, 1949 I 1 5 Sheets-Sheet 5 Inventor ma/zafe/fiz wffi A Home y i a-t'ented May 2 7, 1952 UNITED TATJES PATENT pence ereesew FO TING B AB BODIES" Alexander Proud Fowler, London, Englandpas- -signor to 1 Carrier '{Engineering :Company iL'imited, London, England, a British vcompany :12 Claims. ;1

"T i i e i n: relates 2 5 993113 2 .fQ 51 -ing motor car-bodies, and hasffor-its, main object to achieve automatically the painting of rnotor car bodies when being prod ced on a quantity production basis.

Apparatus according to the present invention is s'6;oonstructed that paint can be 'appliedto motor -car -bodies by progressively applying the paint=i-n a helical band on'the bodysurface by moving the body in a: longitudinal direction a past apaint projecting v zone "andsin ultaneously rotatingthe body aboutalongitudinal axisinter- -;secting the body; the -distanceiof the area of contactef-paint at any part of the helical bandfrom :the projecting zo'ne being maintained constant andthe v'olu'me of paintjbeing projected from h fi n a n i g cQ B T 'F -QP fi l lated' to the speedof jthe respective area of contact w-h'ile passing' the said zone.

Preferably the rate of paintflow: from the proiecting acne is modified in accordance with the varying rad-ii the helical-band alongwhich the paint isprojected. "The paint-may eitherbe; pro- -ected-as a compactstrefam so thatfit isfflowed on to the body, or projected in particle f orm, i. e.

asxa spray.

Preferably,- when -the paint is flowed on to the body it is' projectedso as toffall on to-theupper part of v the body, where paint is projected asa spray it is preferred that the projecting zone is disposed -about the level of the longitudinal axiswaboutwhich the bodyisrotated and; to-one side thereof so -that as the -body is rotated it moves in an ppward direction -away fro x n the zone.

A booth f-fOI --pa;inting motor 'car :bodies *in accordance with a preferred embodiment of the present invention may be characterised-by the combination with means for passaging a body lengthwise through the booth, said'body being supported to rotate about a" longitudinal: axisintersecting the -body,;and means for; causing simul- "taneous'rotation of the'body about thesaid axis, of paint projecting means disposed to apply paint to the-body asitpasses the projectingfrheans, said projecting-means being 'mountedffor axial displacement? to and-fromthe body whereby the distance between the proj ecting means 7 and the body-part opposite -thereto= is maintained substantially constant, :themovement of 1 the --prodecting means being-synchronised with the respectivedinearand angular spe'eds'of the contact area-of-'the= body by 'arotating cam comprising an aetuating contour correspondingtattle-varydng radii iii the -he1ieal= -band of contact or paint "leavingthe projecting iineans, and avalve con- -trolli1ig the volume of-paint c'o ng' from--the 'proiedtingimeens en ra ed rom i ieeim ra having an actuating -contour,; corresponding to i the varying radii ort e b ddyportion'to e coated,

and an obturating contour corresponding {to the body parts not requiredto be coated, flvhereby the -flow of paint-is-regulated to obtain an even coating --and i arrested when the 7 areas not reouired -to-be coated' -become disposed opposite 13047116 paint proj ectingmeans.

In order that the invention 'may be more clearly understood pre'ferredembodirnents' therelof-will now be described byway of example -with of. the paint sprayer-shown in -l igure 1',

iEigure 7: is an end viewlooking' from therigh ofiFigur-efi,

Figure-8' is \a plan ofJFig-ure 16,

:Figure '9 is alpart elevat'ioniofv apparatus -.according to .the inventiomand-emplbying was an actuating-cam a small replica-oi the vehicle body to be painted,

Figure 10 is an-end view looking from theright of Figure- 9,

Figure-1 1 is a-partelevation of a;-boot-h for car bodies passaged thereetihrough, a o.

a Figure- 12 is anend view looking fromthe l e-ft iof Figure llgand a a figure 13 is aplanofapartofthe hqothshown in -Figure i'l. In the "drawings i s r i reese e 'ei eeieth same or similar parts.

-The spray booth I comprises an overhead rail 2 {ef i-section running lengthwise through-the booth and supported on rafters 3 which form part of the spray booth ofjwhich the-fiooris-ifndicated at 4. Stanchions for-theFrafters areindicated-at 5,--the walls mot; shown) of: the booth -being--fixed-= w the stanchions. 1

Pairs of whee-1&5 runon thebottom flangeand to each side of:the-web'ofithe-rail- L The' wheels 6 are mounted in co-axial pairs, two such pairs being carried on each of two stirrups I which are also each provided with a depending part 8 hingedly connected at the bottom to a beam 9 which is thus slung by the appropriate group of stirrups from the respective wheels 6 under the rail 2. The beam is slightly longer than a vehicle body, indicated by A, which is to be sprayed in the booth, and from each end of the beam flexible means depend and are connected to a horizontal shaft (8 on which a car body A is threaded so that the shaft intersects the dash, the body A being rigidly connected to the shaft l9 to prevent relative rotation therebetween.

As viewed in Figure 1, the left hand end of the beam supports a pair of chains ll, each having a hook l2 at the bottom which engages a bracket I3 on the shaft Hi, the bracket l3 including a bearing in which the shaft can rotate. At the other end of the beam 9 is mounted a toothed wheel l4 and at the similar end of the shaft (3 is keyed a toothed wheel [5, a chain it passing over both wheels. Thus chains H and I3 flexibly suspend the shaft 19 from the beam 9.

The toothed wheel I4 is keyed on a shaft ll, on which is a bevel I8 which gears with a bevel [9, Figure 2, and to the latter is connected a pinion 23; the bevels I8, l9 and the pinion 23 being mounted in bearings carried by the beam 9.

From the rafters 3 depend brackets 2 l, to which is secured a rack 22, this rack being intermittent and disposed to be engaged by the pinion at predetermined locations in the spraying stage, so that as the wheels and beam are passaged along the rail the shaft H] is moved lengthwise of the rail and is rotated.

The passaging of the body is effected in the direction of the arrow 13, Figure l, by a towing chain indicated at 23, Figure 1, which at suitable intervals carries forked elements 24 which carry wheels 25 disposed to run on the rail 2 for giving support at sufficient intervals to the chain, the chain being connected to the elements 2 The shaft It may be provided with an adjustable counter balance 26, Figures 1 and 3, for the body A.

The body A may be secured to the shaft It), as shown in Figure 4, by making the shaft in two parts each having a flange 2'5, 28 which flanges are suitably bolted together by the dash bulkhead 29 of the body A, and brackets 38 emanating from the shaft II] are bolted to the bumper strongpoints 3! of the body; thereby the body is secured to the shaft so that rotation of the latter is rigidly imparted to the body.

The shaft l0 may be provided with a ratchet device to prevent unintentional reverse rotation of the body A during its passage through the booth. This device comprises a notched plate 32, Figures 1 and 3, fixed to the shaft l0, and a ratchet arm 33 pivoted at 34 on an arm 35 emanating from the bracket l3. The operating end of the arm 33 carries a roller 36 held towards the plate 32 by a spring 31 so that when the roller engages a notch in the plate 32 and the shaft i0 is locked to the bracket and the chains 1 I prevent rotation of the bracket. The notches are spaced apart so that the body can be rotated to a limited extent as is usual, and locked against rotation when the shaft is under the mechanical control of the rack 22 and pinion 23.

To one side of the path of the motor car body A and at a suitable height in relation thereto, preferably at about the level of the axis of rotation, is arranged the spray forming device which 2,598,2246 1 s ".T "I 7' may consist of a group of spray guns or of a single spray gun 38 as indicated in the drawings, the gun or guns being carried on a pair of

arms

39, 49 arranged to oscillate in a vertical plane normal to the axis of rotation of the car body. The upper ends of the

arms

39, 43 are connected to the spray gun 38 and a link 41 also connects the arms.

The lower end of the arm 39 is pivoted at 42 and a support 33 extends from the arm and carries a follower A l to engage the contour of a cam 45 mounted for rotation with a spindle 46 the axis of which is parallel to the axis of the shaft l0 carrying the car body A. A spring 47 maintains the follower 44 in contact with the cam 45.

The spindle 45 is rotated by a motor 48 so that the angular speed of the cam 45 corresponds to the angular speed of the motor car body being painted and the contour of the cam is arranged with respect thereto so that the gun 38 is maintained at a substantially constant distance from the area of contact of the paint projected from the gun to that part of the motor body opposite to the gun.

The oscillating arm 39 may be mounted near the floor of the booth and the actuating cam 45 also supported from the floor, or both may be supported on a low carriage as described below, so that the oscillating arm 39 is given maximum length and, therefore, maximum axial adjustment for the spray for a minimum variation in the radii of the contour of the cam.

The gun 38 is hingedly connected to the arm 39 and is self controlled by a cam 49 supported by the arm 39, the cam 49 being rotated by the motor 48. By engaging the arm 40 the cam 49 maintains the axis of the gun as a normal to the car body during rotation of the latter in spite of the varying curvatures of the body presented to the gun.

From the foregoing it will be understood that as the car body is passaged past the spray gun, the area of contact of paint with the body traces a helical band C, Fig. 1, about the body from end to end thereof, and that the gun is maintained at a constant distance from the area of contact during the painting operation in spite of the varying radii of the body parts in the said helical band.

As regards the volume of paint projected from the gun 38 at any particular time, this is controlled so as to be related to the speed of the respective areas of contact while passing the paint projecting zone. To this end the flow of paint from the gun is controlled by a valve 50, of any suitable known construction, such for example as a needle valve, the valve being actuated by a cam 5i rotated in synchronism with the motor car body A by an electric motor 52. The actuating contour of the cam 51 corresponds to the varying radii in the helical band, and includes an obturating contour 53, Figure 6, for cutting off the flow of paint to the gun, for example, when the under surfaces of the motor car body are presented thereto.

In order to simulate the hand operation of a spraygun the pivot 42 of the arm 39 is mounted on a carriage 54 which is supported on wheels 55 to run on the floor of the booth or on rails or on guide tracks 56 disposed therein. The carriage 54 is given a reciprocating movement through a link 5'1 connected therewith and with a crank disc 58 on the motor shaft, and the tracks 58 guide the carriage for movement in a direction parallel to the axis of rotation of the motor car body A. The actuating cam 45 and the motorllfi axe alsd as shown in the drawineswmounted on ciprocab'le "carriage 54' similar to that described above, "and is'so operated that whenthebody A and the replica are moving" in the same direction their linearspeeds' are proportional totheir relative'sizes. The return movement of-the-carriage 'isiajquick one *so that when one body Ahasoeen completelrpainted under control of the replica the latter is returned to its startin osit-ion in "feeidinessto control the painting of the next-body ;pjass'ing 1' the painting -position. Control of the "volume of'paint ls similar'to that previously described.

fWhe're it isdes'iredto coat' the motor car body (by fiowingthe, paint on; it may not benecessary, according to the disposition of the: nozzles with .regard to the body, to arrange for adj ustmentnf the nozzles to and from the body. Figures 11' to 13 diagrammatically, show a booth for flowing paint onlto aicar body. In thisarran'gement the car body is suspended froma beamQ as described above but rotation of the shaftl'fl is effected by avtoothe'd wheel" 59 on the shaft I]; the toothed wheel engaging a rack '63 as the beam"? ispasysaged through the, boothby the towing chainZS.

lT-he .ipaint is flowed from two nozzles 6 l 62 mounted-in fixed. positions above the path of'the car i-bodyla-nd fed from a source of supply'ES through a valve' Mwv'hi'ch regulates the volumeof paint flowing from thenozzles according to the speed of 'the bodyspart onwhich the paint isto be fi'owe d. The valve maybe of any suitable known form such as a needle valve and is' controlled= by avcam 525bsecured tothe'side' otthe vbeam iis .The contour of' the cam igenga'geable bya'follower l lb ona support-63b connected'with the valvelandlis such that according to the: contou r of the cam the support regulates the valve in accordance with the surface speed of thebody lpartpresented to the nozzlesforpainting. "The cam-45b isso shaped that when partswhich it is desired not to'paint'are presented to'thenozzles tthelfiow of, paintlis obturated by the'valvefifi.

Anmotor car' body being painted according to the invention may be a body with oriwithout ,wingsrorbonnet-or sucha body with an'integral chassis (i. e. a body), sometimes known as ,a Vunitary' -or combined body and chassisor such? a dbody without chassis.

-By-the present invention motor car bodies may begdelivere'di'inesuccession into'the booth and theresautomaticallypainted in a quantitytpro- -duction system oi painting the bodies.

1.-,Apparatus for treating a body having irregular non-symmetric'al surfaces, comprising af'inovany supported 'de'vicefo'r projecting atreatin t6 Zliquld, 1a conveyorzmovablewpast isaidadevioeeand including aw-mount: adapteditosupport the :body substantially longitudinally :of conveyor zrmovement, sai'd 'mountrbeing 'rotatable about-an axis that is substantially longitudinal vet-conveyor unovementgmeans for rotatingsaid:mountasitis advanced by the I conveyor" to rotate the body--,a-s :it is carried longi-tudinally pastsaid deviceagand -medhanism :actuated in ="synchronism with tthe 'linear and axialaspeeds of thezcontact area ofizthe "body, -"and"='means operated by sa'i'dzmechanism and--operativ 1y connected with said device for moving said device toward aand from sai'd conveyon-to'maintain substantially constantspacing "between said ideviee sand "the bo'dy surface 1 and accommodate =-variations both loisrg-itudinally and circumferentially df the'body.

2. In apparatus for 'coating' motor car bodies wi-th paint, -a rotatableibody-=carryingrmount,ea conveyor system,'-suppor-t means "carried byssai'd conveyor 1 system and I rotatab1y=supporting said "mount for continuous axial movement thereby past a paint projecting position;meansitorotate --said-mount -about itsaxis, paint-projectingmeans L mounted adjacent thepath of said "moon-t valve means to control the -volume of paint =flowing -to the paint projecting -.-means, a ==cam havi'ng an -'actuating contour to control =said ya'lve- 'means, and means for actuating =said eam in synchronism with said mount to operate -sai d valve means to deliver a 'vol-ume'of' paint to"the=paint projecting means-accordingto the-varying radii of ai-body rotated 'by said-"mount.

3. fApparatus-as defined inclaim-z, whereirrsai'd cam-also has an actuat-i-ng'contour'to efiect obturation of the i'lovv' of *paint when there is 'pre- 'sented-to the paint dispensing means aportion-of a body to which paint ishot.tobe appliedt- 4. In -apparatus"for-coating motor car bo'dies with paint, a rotatable 'body carrying mount, a paint projecting station, a conveyorsystem-extending past said station;--support means-carried by said conveyor system and rotatively supporting said-mount for continuous axial movement past said-paint projecting station, means to-rotate said body mount about its axisas it is-moved-exial-ly, paint" projecting meansat said pain-t projecting station and mounted for displacement 1 towards and away from the-path of said-spindle,-=a cam and means for actuating saidcam in synchronisi'n with the linear and" angular speeds of-- the con-tact area :or-a body co-which paint is-=to -be=applied,

said oam" being operatively connected "with the paint projecting means toeffect said displacement thereof so i that the distance between 'the projecting "means and a body =on the-spindle' is maintainedsubstantially constant.

5. 1n apparatus forcoati-ngmotor can-bodies witlr paint,a rotatable'body carryingspindleyan elevated conveyor system, suspension means by which said spindle is suspended from the conveyor' syStem for continuous axial movement thereby past a paint projecting -position,'--mea-ns torotate said spindle about "its" axis; as spray gun disposed generally radially of" saidspindlerme'an's movably supporting saidf' gun for dispiacement towards and away from the path of 'said spindle, a cam- 'operativ'ely connected-with said spray ,gun and-means for actuating said cam in sy-nchronism with the linear and angular speedsof the-con- -tactarea ot a body 120 which paintis: to beep- "plie'dfto efiectsaid displacement of the spray gun =soi that thedistance-between the spray guneand -a body-on the -spiridle 'ismai-ntainedsubstan ally v6. In apparatus for coating motor car bodies with paint, a rotatable body carriage, a conveyor system, support means on said conveyor system and rotatably supporting saidcarriage for continuous axial movement thereby past a paint projecting position, means to rotate said carriage about its axis, a stanchion mounted at the paint projecting position for movement toward and from said conveyor system and carriage, means yieldingly pressing said stanchion toward said conveyor system, a spray gun disposed to project paint at about the level of the horizontal axis of said carriageand mounted on said stanchion for displacement towards and away from the path of said carriage, a cam operatively connected with said spray gun and means for actuating said cam in synchronism with the linear and angular speeds of the contact area of a body to which paint is to be applied to efiect movement of said stanchion and displacement of the spray gun so that the distance between the spray gun and a body on the carriage is maintained substantially constant.

7. In apparatus for coating motor car bodies with paint, a rotatable body carriage, a conveyor system, support means carried by said conveyor system and'rotatably supporting said carriage for continuous axial movement thereby past a paint projecting position, means to rotate said carriage about its axis, a spray gun mounted for displacement towards and away from the path of said carriage, a cam rotatable in synchronism with the linear and angular speeds of the contact area of a body to which paint is to be applied to effect said displacement of the spray gun so that the distance between the projecting means and a body on the spindle is maintained substantially constant, valve means to control the volume of paint flowing tothe spray gun, a cam having an actuating contour to control said valve means, and means for actuating said cam in synchronism with said mount to operate said valve means to deliver a volume of paint to the spray gun according to the varying radii of a body rotated by said carriage and to effect obturation of the flow of paint when there is presented to the spray gun a portion of a body to which paint is not to be applied. 8. In apparatus for coating motor car bodies with paint, a rotatable body carrying spindle, a conveyor system, support means carried by said conveyor system, and rotatabiy supporting said spindle for continuous axial movement thereby past a paint projecting position, means to rotate said spindle about its axis, a spray gun mounted for displacement towards and away from the path of said spindle and for oscillation in a path parallel to the axis of said spindle, a cam operatively connected with said spray gun, means for actuating said cam in synchronism with the linear and angular speeds of the contact area of a body to which paint is to be applied to eifect said displacement of the spray gun so that the distance between the gun and a body on the spindle is maintained substantially constant, means for oscillating said spray gun, and means for actuating said oscillating means in timed relation with the movements of the spindle to efiect said oscillation of the gun to simulate hand operation of the gun. v

9. In apparatus for coating motor car bodies with paint, a rotatable body carriage, a conveyor system, support means by which said carriage is supported from the conveyor system for continuous axial movement thereby past a paint projectmg position, means to rotate said carriage about its axis, a pair of interconnected arms spaced apart in a direction normal to the axis of said carriage for displacement towards and away from the path of the carriage and arranged for lengthwise movement relative one to the other, a spray gun supported by adjacent ends of said arms for movement therewith, a first cam co-operating with a first one of said arms, means for rotating said first cam in synchronism with the linear and angular speeds of the contact area of a body to which paint is to be applied to effect said displacement of the links so that the distance between the spray gun and a body on the carriage is maintained substantially constant, a second cam rotatably supported by the first said arm, and means for rotating said second cam in synchronism with said first cam for co-operating with the second-of said arms to vary the lengthwise disposition of the two arms and thereby maintain the axis of the gun substantially normal to a body on said spindle.

10. In apparatus for coating motor car bodies with paint, a rotatable body carriage, a conveyor system, support means by which said carriage is supported from the conveyor system for continuous axial movement thereby past a paint projecting position, means to rotate said carriage about its axis, a pair of interconnected arms spaced apart in a direction normal to the axis of said spindle for displacement towards and away from the path of the spindle and arranged for lengthwise movement relative one to the other, a spray gun supported by adjacent ends of said arms for movement therewith, a first cam co-operating with a first one of said arms, means for rotating said first cam in synchronism with the linear and angular speeds of the contact area of a body to which paint is to be applied to efiect said displacement of the links so that the distance between the spray gun and a body on the carriage is maintained substantially constant, a second cam supported for rotation by said first arm, and means for rotating said second cam in synchronism with said first cam to co-operate with the second of said arms to vary the lengthwise disposition of the two arms and thereby maintain the axis of the gun substantially normal to a body on said spindle, valve means to control the volume of paint flowing to the spray gun, a third cam having an actuating contour to control said valve means, and means for rotating said third cam to actuate said valve means to deliver a volume of paint to the gun according to the varying radii of a body rotated by said spindle and to effect obturation of the flow of paint when there is presented to the gun a portion of a body to which paint is not to be applied. e

11. In apparatus for coating motor car bodies with paint, a rotatable body carrying spindle, a conveyor system, support means by which said spindle is supported from the conveyor system for continuous axial movement thereby past a paint projecting position, means to rotate said spindle about its axis, a pair of arms spaced apart in a direction normal to the axis of said spindle for displacement towards and away from the path of the spindle and arranged for lengthwise movement relative one to the other, a spray gun supported by adjacent ends of said arms for movement therewith, a link connecting said arms between the ends thereof, an oscillatable carriage for said arms, guide means to guide said carriage for oscillation in a path parallel with the axis of said spindle, means for oscillating said carriage along said guide means, means for operating said oscillating means in timed relation with the movements of said spindle to effect oscillation of the carriage to simulate hand operation of the un, a first cam co-operating with a first one of said arms, means for rotating said first cam in synchronism with the linear and angular speeds of the contact area of a body to which paint is to be applied to efiect said displacement of the links so that the distance between the spray gun and a body on the spindle is maintained substantially constant, a second cam supported for rotation by said first arm, and means for rotating said second cam in synchronism with said first cam to co-operate with the second of said arms to vary the lengthwise disposition of the two arms and thereby maintain the axis of the gun substantially normal to a body on said spindle.

12. In apparatus for coating motor car bodies with paint, a rotatable body carrying spindle, an elevated conveyor system, suspension means by which said spindle is suspended from the conveyor system for continuous axial movement thereby past a paint projecting position, means to rotate said spindle about its axis, a pair of arms spaced apart in a direction normal to the axis of said spindle for displacement towards and away from the path of the spindle and arranged for lengthwise movement relative one to the other, a spray gun supported by adjacent ends of said arms for movement therewith and at a position such that it is disposed to project paint at about the level of the horizontal axis of said spindle, a link conmeeting said arms between the ends thereof, an

,oscillatable carriage for said arms, guide means to guide said carriage for oscillation in a path parallel with the axis of said spindle, a crank pin operable in timed relation with the movements of said spindle, a link connecting the crank pin to the carriage to effect oscillation of the carriage to simulate hand operation of the .gun, a first cam co-operating with a first one of said arms,

10 means for rotating said first cam in synchronism with the linear and angular speeds of the contact area of a body to which paint is to be applied to effect said displacement of the links so that the distance between the spray gun and a body on the spindle is maintained substantially constant, a second rotatable cam journalled on said first arm, means for rotating said second cam in synchronism with said first cam and co-operating with the second of said arms to vary the lengthwise disposition of the two arms and thereby maintain the axis of the gun substantially normal to a body on said spindle, valve means to control the volume of paint flowing to the spray gun, and a third cam having an actuating contour to control said valve means to deliver a volume of paint to the gun according to the varying radii of a body rotated by said spindle and to effect obturation of the fiow of paint when there is presented to the gun a portion of a body to which paint is not to be applied.

ALEXANDER PROUD FOWLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,256,599 Schoop Feb. 19, 1918 2,083,634 Brackett June 15, 1937 2,284,366 Bryant May 26, 1942 2,286,571 Pollard June 16, 1942 2,295,702 Wissler Sept. 15, 1942 2,345,834 Schweitzer Apr. 4, 1944 2,374,288 Hinkley et a1. Apr. 24, 1945 2,380,509 Emerson July 31, 1945 2,424,418 Rory July 22, 1947 2,427,874 Pilson Sept. 23, 1947 2,434,125 Schweitzer Jan. 6, 1948 2,434,176 Potthoff Jan. 6, 1948