US2757606A

US2757606A - Silk-screen printing machines

Info

Publication number: US2757606A
Application number: US258310A
Authority: US
Inventors: Dubuit Louis Gilbert
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-01-02
Filing date: 1951-11-27
Publication date: 1956-08-07
Anticipated expiration: 1973-08-07

Description

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3M van, uhm man@ United States Patent SILK-SCREEN PRINTING MACHINES Louis Gilbert Dubuit, Paris, France Application November 27, 1951, Serial No. 258,310

Claims priority, application France January 2, 195,1

9 Claims. (Cl. 101-126) The present invention relates to machines for silk-screen printing particularly upon rotational bodies having conical or up to and including cylindrical surfaces.

The known machines of that type had many disadvantages. Particularly it was diicult, if possible at all, to synchronize the displacement of the screen with the rotation of the body to be printed upon, so that such machines could hardly be used for multicolor printing.

The object of my invention is to eliminate the said and other disadvantages of the known machines and to provide a machine which operates exactly, easily and efciently, particularly permitted to locate the printing upon the body in any predetermined position thereupon thus making the machine applicable for multicolor printing.

The said and other objects of my invention will be more fully understood from the following specification when read with the accompanying drawing in which three embodiments of my new machine are illustrated.

In the drawing:

Fig. 1 is a longitudinal section of a first embodiment of the device according to the invention; j

Fig. 2 is a plane view of this same embodiment.

Fig. 3 is a perspective View of the pulley which drives the object to be printed;

Fig. 4 is a similar view of the suport of said part of the object cooperating with said pulley;l y

Fig. 5 is a longitudinal section view of a third embodimen-t of the invention with the screen supporting elements supposed to be removed;

Fig. 6 is a partial plane view of this embodiment;

Figj7 is a partial sectional view on a larger scale along line X--X of Fig. 6; .f

Fig. 8 is a side elevational view with a partial section along line )G-XI of Fig. 9, of a modified embodiment of the device shown in Figs. 5 to 7;

Fig. 9 is a top view corresponding toFig. 8. l

Fig. 10 is a view on a larger scale of a detail of Fig. 8.

Figs. 1 .to 4 illustrate a machine for the printing of objects provided with a conical surface. This machine comprises a frame 1 on which is secured a supporting pillar 2 which carries at its upper portion two arms 3 and 4 extending towards the rear and towards the front of the machine, respectively.

At the rear end of arm 3 is articulated around a vertical axle 5 a triangular support 6 on which are articulated around horizontal axles 7 and 7u two arms 8 and 8a connected by a crosspiece 9 in the shape of a circular arc, center of curvature coinciding with axle 5. Arms Si and 8a carrying supports 1t) and 10a to which frame 1l of the silk screen 12 of the machine is secured.

On arm 4 is articulated around a horizontal axle 13 a lever 14 on which is secured, in a maner known per se, a rubber scraper 15 cooperating with screen 12. Under the lever 14 is arranged a projection 16 which cooperates with two ramps 17 and 17a arranged on the upper face of cross piece 9 in order to lift scraper 15 with respect to screen l2 at both ends of the travel ofthe latter.

ice

other ramps 18 similar to ramps 17 and 17a are arranged on the lower face of cross piece 9 opposite said ramps 17 and 17a, and cooperate with a stop 18a carried by arm 4 in order to lift the screen itself at each end of travel, arms 8 and 8a pivoting around axles 7 and 7a. Said ramps 18 are provided with stop studs which cooperate with stop 18a in order to limit the travel of the screen.

On frame 1 is secured -by means of a wedge shaped support 19, an oblong plate 20, the longitudinal axis of which is in the same plane as that of arms 3 and 4 and on which is slidingly mounted a counter plate 21 laterally guided by rollers 22 pivoting around axles 23 secured to plate 20.

Plate 20, `at its upper end, carries a support 24 having a fixed shaft 25 on which a pulley 26 with a wide cylindrical groove is rotatively mounted. This pulley is engaged by a cable 26a which passes over

transfer pulleys

27, 28 and 27a, 28a carried by

arms

29, 30 and 29a, 30a secured on plate 20, the ends of this cable being attached, respectively, to lugs 31 and 31a laterally extending at the ends of arms 8 and 8a.

Two supports 32 and 33 are secured on counter plate 21. Support 32 comprises a bearing 34 in which a shaft 35 is rotatively mounted coaxially with shaft 25 of pulley 26 and which carries, on the one hand, facing this latter pulley, a plate 36 and, on the other hand, at its opposite end, a member 37, hereinafter called a socket, arranged to lit exactly the bottom of the object to be printed, in the present case a bottle 38 of frusto-conical shape ilaring upwards. In a bore 39 provided in support 33 coaxially with shafts 25 and 35 a spindle 40 is slidingly mounted, which carries on one end a control knob 4l and on the other end through a ball bearing 42r a movable head 43,0r counter-socket of a :conical shape, capable of partly entering the neck of the bottle to be printed. A Spring 44 housed inside bore 39 and bearing on the one hand on a notch provided in said bore and on the other hand on a shoulder of spindle 40 tends to push spindle 40 and its head 43 towards the bottle, thus holding the latter between head 43 and cap 37.

On support 32 is articulated a lever 45 With two arms 45a and 45b forming a lock, arm 45a being subjected to the action of a spring 46 which tends to press it against the outer face of cap 37 thus immobilizing the latter, while arm 45b of said lever terminates in a hook 47 which cooperates with a roller 48 carried by support Z4 of the shaft 25 of pulley 26; said roller 48 effects a tipping over of lever 45 against the action of spring 46 thus releasing cap 37. Furthermore, hook 47 while engaging roller 48 holds the counter-plate 2l at its high position as shown in Fig. 1.

Pulley 26 is provided on its front face with a radial groove 49,for engagement with a corresponding projecttion 50 provided on the side face 'of plate 36 (Figs. 3 and 4).

Plate 20 is suciently long to allow a downward sliding of counter-plate 21 so that the bottle to be printed can be completely disengaged from the screen carrying frame 11.

The machine described before operates as follows:

Screen 12, which shows in free meshes the design or drawing to be printed on the bottle, is arranged along a lcircular segment centered on axle 5, and corresponds to the development of the conical surface to be printed. The unit comprising the inked screen 12 and its supporting` elements is pushed to one side of the machine. Counter plate 21 is pulled downwards by sliding on plate 20, so as to bring socket 37 beyond screen 12 and its supporting elements. At the beginning of this sliding motion, hook 47 of arm 45b of lever 45 is released from roller 4S and arm 45a of said lever rises under the action ci' spring 46 and immobilizes cap 37.

Thereafter control knob 41 of spindle 40 is pulled back against the action of spring 44. A bottle is then introduced by placing its bottom on cap 37, and said knob 41 of spindle 40 is released, so that the bottle is being held in position ybetween cap 37 and conical head 43. If the precaution has been taken of drawing a marking line on the bottom of the bottle to be printed, and a corresponding line on cap 37, it is possible to place each bottle exactly in the same position with respect to the immobilized cap 37 and, consequently, to pulley 26 and with respect to the screen.

Counter plate 21 is then pushed upwards to bring the bottle under the screen 12. Projection 50, upon plate 36 engages groove 49 in pulley 26; hook 47 of lever 45 engages roller 48 thus releasing cap 37 and counter plate 21 is being held in its high position.

The printing is then eected in usual manner, by rotating by hand the screen carrying elements about axle 5. At the beginning the screen 12 is lifted with respect to the object 38 and the scraper 15 with respect to the screen by means of the described set of ramps 17 and 18. The screen, as soon as its displacement begins due to the action of said ramps, moves downward and contacts the bottle 38 and the scraper 15 itself moves down upon the screen. The bottle is rotated in synchronism with the displacement of the screen owing to the connection between the screen and pulley 26 ensured by cable 26a and to the connection between pulley 26 and socket 37 ensured by groove 49 of the pulley 26 and projection 50 of the socket 36.

When the screen has been swung to the other end of its travel, the bottle which has executed a complete revolution is printed and ramp 17a, as well as the corresponding ramp 18 lift the screen and the scraper. Countenplate 21 is then disengaged by sliding it downwards and socket 37 is immobilized by lever 45 from the start of this motion and before projection 50 of plate 56 has disengaged groove 49 of pulley 26. The bottle is then removed from its supporting elements by actuating spindle 40 through its control knob 41 and a new bottle is so placed in position, that its marking coincides with a marking on cap 37, whereafter a new printing may be started by pivoting the screen in the opposite direction.

Figs. 5, 6, and 7 illustrate an automatic machine for silk screen printing, upon objects having a conical surface, such as glass tumblers.

This machine comprises a frame 201, which is only partly shown and which carries, at its upper portion, elements for holding and displacing the screen, as well as a scrapcr-carrying lever. 'Ihese various elements are substantially similarly arranged to the corresponding elements of the embodiment shown in Figs. l to 4, with the only diterence that a known mechanical device, for instance a connecting rod and crank, is provided in order to ensure the automatic displacement of the screen under the action of the driving motor of the machine. To avoid an overloading of the drawings, these various elements have not been shown, only frame 202 of screen 203 having been represented.

The machine frame 201 supports by means of arms 204 a vertical shaft 205 on the upper end of which s keyed a plate 206 which extends under screen 203.

Shaft 205 is driven by a motor (not shown) and intermittently actuated by known means such as a maltese cross (also not shown). Plate 206 is provided with a rectangular windows 207, the longitudinal axis thereof being arranged substantially radially with respect to said plate. These windows 207 are designed to be successively positioned under screen 203 after each displacement of plate 206. Parallel with the longer sides of each window is arranged a shaft 208 which is trunnioned in bearings 209 carried by the plate and on `which are keyed two arms 210 connected by a terminal crosspiece 211. On this crosspiece 211 is secured a support 212, the longitudinal axis of which coincides with a radius of plate 206. On this support is arranged a bearing 213 in which is trunnioned a shaft 214 which bears, on the one hand, a plate 215 hereinafter called a socket, and on which may t the bottom of a tumbler 216 to be printed, and on the other hand a plate 217 in which is yprovided an axial groove 218. An arm 220, terminating in .a bearing `2.21, provided with a control finger 222 is articulated about an axle 219, at the other end of support 212. `In bearing 221 is trunnioned a shaft 223 which carries a plate 224 designed to t over the edges of the tumbler 216 to be printed, this plate comprising a frustoconical boss 225, which `is capable of entering said tumbler to ensure its centering on the common axis of

shafts

214 and 223. Shaft 223 is held in the bearing 221 by a check ring 226. A spring 227, the ends of which rest in a depression 228 provided in the support 212 and in a depression 229 provided in the arm 220 respectively, tends to press the plate 224 against tumbler 216.

ln the bearing bracket 230 arranged under support 212 is rotatively mounted a roller 231, which cooperates with a plate 232 mounted on the end of a rod 233. This rod slides in sleeve 234 carried by arm 204 of the frame 201 and carries at its lower portion a bearing bracket 23S in which is rotatively mounted a roller 236 which cooperates with one end of a lever 237, articulated about a shaft 238, on frame 201 of the machine, while its other end carries a roller 239 which cooperates with a cam 240 keyed on a vertical shaft 241 driven by the not shown motor of the machine. On frame 201 and in the middle transverse plane of the latter, i. e. in the same plane as the scraper, which cooperates with the screen 203, is articulated about an axle 242 a lever 243 with two arms 243a and 243b. Arm 243a of said lever carries at its end an axle 244 on which is rotatively mounted a pulley 245 in the circumferential groove of which passes a cable 247, the ends of which are secured on the support of frame 202 of screen 203, in a similar manner as shown in Figs. l and 2. Pulley 245 carries on its outer face a radial rib 248 which may engage a groove 218 provided in each plate 217. Arm 243b of lever 243 carries at its end a roller 249 which cooperates with a cam 250 keyed on said shaft 241. A spring 251 which bears with one end on a transverse extension of frame 201 and with its other end, at the bottom of a bore 252 provided in arm 243b of lever 243, tends to tip over the latter in the direction which moves the pulley 245 closer to the plate 206. Arm 243a also carries a finger 253 which cooperates with a roller 254 carried at the end of an arm 255 articulated at 256 'on each of said supports 212. said arm 255 comprising a hook 257 which, when roller 254 is not subjected to the action of finger 253 is brought under the action of a spring 258 against plate 215 in order to block the same and to prevent the rotation thereof.

The machine shown iu Figs. 5, 6 and 7 operates :ls follows:

T'umblers 216 to be printed are secured successively between socket 215 and counter-socket 224 carried by each support 212 when said supports are withdrawn from under screen 203; in order to do so, the operator acts on the control nger 222 to tip over arm 220 against the action of spring 227. He applies the bottom ol tumbler 216 against socket 215, then releases finger 222 in order to apply plate 224 against the edge of thel tumbler. Cam 250 acting on roller 249 tips lever 243 moving pulley 245 away from clutch plate 217, plate 206 turns one notch bringing a support 212 under screen 203 which is at one end of its reciprocating path. Rod 233 is then raised under the action of cam 240 and lever 237, and plate 232 acting on roller 231 raises support 212 mounted on the swing arrn 21.0 pivoted on shaft 208, thus raising the tumbler 216 to be printed up to the screen 203. Immediately afterwards cam 250 releases roller 249 and lever 243 tips over under the action of spring 251. Projection 248 carried by pulley 245 engages groove 218 of plate 217 which is opposite said pulley and nger 253 acts on roller 254 tipping over lever 253 against the action of spring 258 which releases socket 215. The screen is then displaced from one end of its path to the other end by its driving mechanism and the printing is effected, in a manner known per se, tumbler 216 being driven synchronously rotated with the displacement of the screen by the operation of pulley 245, which is driven by cable 247 and engages the clutch plate 217. When the screen has reached the opposite end of its path cam 250 acts once again on roller 249 to tip over lever 243 against the action of spring 251. Finger 253 releases roller 254 and hook 257 of lever 255 again immobilizes socket 215, whereafter pulley 245 is disconnected from plate 217. In continuation, cam 240 allows roller 239 to rise, so that rod 233 with its plate 232 moves downward, and support 212 is again lowered thus separating tumbler 216 from screen 203. The frame plate 206 is then driven for a fraction of turns and the above described operations are repeated in order to print another tumbler after the printed tumbler has been removed from socket 215 and counter socket 224.

It is apparent that, owing to the immobilization of socket 215 and to the motion of pulley 245, tumblers 216 may always be brought under screen 203 in the same position by the use of positioning marks drawn on the tumblers, on the one hand, and on socket 215 on the other hand.

Another modiiied embodiment is shown in Figs. 8 to 10. Frame 301 of the machine carries the same elements to hold and displace the screen, as well as the scraper-carrying lever already described in connection with the previous figures. These various elements are arranged substantially like the corresponding elements in the example illustrated by Figs. l to 4, a known mechanical device being also provided in order to ensure the automatic displacement of the screen under the action of the driving motor of the machine, these various elements not being represented in order to simplify the drawings.

A support 302 associated with the machine frame 301 traversed by av rotary shaft 305 rotatively and intermittently driven like shaft 205 in Figures to 7, by a mechanism, not shown. A head 306 rotatively mounted on support 302 and carrying twelve horizontal arms is keyed on shaft 305.

On each arm 307 is rotatively mounted a sleeve 308 longitudinally immobilized on said shaft by collars 309. Said sleeve 306 carries through the medium of a lug 310 a plate 311, which is secured to said lug 310 by studs 312 engaging stud holes 313 in plate 311 and making it possible to adjust the position of said plate with respect to lug 310. Plate 311 carries a spindle 314, the free end of which cooperates with a plate 315 mounted at the end of a shaft 316 sliding vertically in frame 301 and subjected to the action of a mechanism similar to

mechanisms

236, 237, 239, 240, illustrated in Fig. 5.

On plate 311 opposite head 306 is rotatively mounted on a stud 317 resting in a stud-hole 318 a lever 319 carrying a roller 320 coated with rubber and fitting in the upper aperture of the tumbler to be printed. Lever 319, which is provided with a stop hook 321 cooperating with plate 311 and which is loaded by a spring, not shown in Figure 10, comprises an arm 322 on which a lever 323 is articulated.

A spring 324 rests with one end in a housing 325 provided in lever 323 and with its other side on said lever 319. Lever 323 further comprises an arm 326, capable of pressing against lever 319 and the free end of said lever 323 is provided with two set

screws

327 and 328. Screw 327 cooperates with an eccentered cam 329 associated with support 302, said cam being arranged to cause the tipping over of the lower portion of lever 323 from left to right (Figure 8). When the corresponding arm 307 reaches a position diametrally opposed to the screen of the machine, this tipping over causes arm 326 to press against lever 319 thus causing the latter to pivot around stud 317 pushing roller 320 aside.

The set screw 328 cooperates with a plate 330 associated with frame 301 and tends to hold lever 323 in the position shown on the right hand side of Fig. 8.

At the other end of plate 311 is mounted a support 331 provided with a bearing 332 in which is rotatively mounted a shaft 333 which carries, on the one hand, a plate 334 capable of receiving the bottom of the tumbler to be printed, and, on the other hand, a plate 335 in which is provided an eccentered bore 336. In addition, on support 331 is swivellingly mounted a bell crank lever 337 having, on the one hand, a boss 338 capable of engaging a radial groove 339 provided in plate 334 and, on the other hand, a rotary roller 340. A spring 341 tends to pivot lever 337 in the direction to engage boss 338 in groove 339 of plate 334.

On frame 301 is secured a support 342 rotatively holding a shaft 343 which carries, on the one hand, a lever 344 provided at its end with a roller 345 cooperating with a cam 346, similar to cam 250 of Figure 5 and, on the other hand, a lever 347 terminating into a supporting plate 348 in which is secured an axle 349 perpendicular thereto. On this supporting plate is rotatively and freely mounted a pulley 350, in the groove 351 of which passes a cable 352, the ends of which are secured to the support of the screen frame in a manner similar to that shown in Figures l and 2. The pulley 350 carries an eccentered projection 336g, designed to enter the said bore or recess 336 in plate 335.

Plates 311 carry two cradle shaped parts 353 adapted to receive the tumblers to be printed, holding each tumbler in the axis of the corresponding plate 334.

Said plates 311 may rest on a plate 354 associated with the support 302v during the rotation of head 306.

The machine illustrated in Figs. 8 to 10 operates in the following manner:

Head 306 is intermittently rotated in order to present each of the articulated assemblies on each shaft 307 under the screen of the machine, at each displacement of said screen. When one of said assemblies reaches a position diametrally opposed to the screen (this position being represented on the right hand side of Fig. 8), set screw 327 on lever 323 causes the tipping over of the latter as previously described, and plate 320 moves away from plate 334. The operator then places a tumbler to be printed on the cradle shaped parts 353, the bottom of the tumbler being turned towards plate 334. While head 306 continues to rotate in the direction of the arrowv in Fig. 9, rod 327 leaves cam 329 and plate 320 under the action of spring 322 enters the opening of the tumbler, holding the latter against plate 334. Said plate 334 is prevented from rotating owing to the fact that boss 338 of lever 337 engages groove 339 under the action of spring 341.

When the assembly comes under the screen of the machine, pulley 350 is moved aside (position in broken lines in Figure l0) under the action of

levers

344 and 347, set screw 328 comes into contact with plate 330 and is immobilized, spring 324 rmly maintaining in position lever 319 by means of arm 326. Further, plate 315 rises, the control elements for shaft 316 being designed tothis offset. Said plate 315 acts on rod 314 in order to slightly raise the small plate 311 and to cause the tipping over of the assembly carried by this plate around shaft 307 so as to bring, on the one hand, the tumbler mounted between

plates

320 and 334 in contact with the screen of the machine and, on the other hand, the shaft 333 in coaxial alignment with shaft 349. Cam 346 permits roller 345 to rise thus tilting lever 344, pulley 350 moves againstplate 335 and projection 336:1 enters recess 336; at the same time lever 347 acts on roller 340 of lever 337 tilting the same so that boss 338 disengages from groove 339 and thus releases plate 334.

The screen is then displaced by the control mechanism of the machine and cable 352 rotates pulley 350 synchronously with the displacement of the screen. Pulley 350, associated with plate 335 through projection 336:1 entering recess 336, drives said

plates

335 and 334 with the tumbler mounted between the latter and plate 320; said tumbler is thereby rotated synchronously with the screen displacement, and thus receives the desired printing.

When the displacement of the screen is ended, the control cam for lever 344 again causes said lever 344 to tip over and lever 347 pushes aside pulley 350 from the plate 335. At the same time roller 340 is released and spring 341 causes a return tilting of lever 337, so that projection 338 on lever 337 reenters groove 339 of plate 334, the latter thus being again immobilized in the marked position.

While head 306 continues to rotate set screw 327 of lever 323 again comes into contact with cam 329 and, plate 320 swings to release the tumbler. The operator removes the printed tumbler, replaces it with a new one and the operating cycle is repeated.

While specific embodiments of my invention have been shown and described in detail to illustrate the application of the principles of my invention, it will be well understood that the same may be otherwise embodied without departing from such principles and without avoiding the scope of the appended claims.

What I claim is:

l. In a silk screen printing machine of the type described for printing upon conical, up to and including cylindrical surfaces of rotational bodies, the combination comprising a machine frame; a silk screen stencil; a carriage for said stencil to support the same in a substantially horizontal position; a flexible scraper cooperating with said stencil; displacing means for said carriage; a rotatably mounted chuck to support the body to be printed upon; a clutch disc rotating with said chuck; a pulley coaxially mounted with said clutch disc and adapted to cooperate therewith; driving means for said pulley to rotate the same synchronously with said displacing means for the stencil carriage; supports for said chuck with clutch disc and for said pulley, respectively, mounted in the machine frame for relative displacement of each other to effect engagement and disengagement of said clutch disc with said pulley; means to effect such relative displacement; locking means to immobilize said chuck when said body is not in printing position; and actuating means for said locking means operating synchronously with said means to effect the said relative displacement of said supports and holding the locking means in operative position when said pulley and said clutch disc are disengaged and in inoperative position when said pulley and said clutch disc are engaged.

2. In a silk screen printing machine of the type described for printing upon conical, up to and including cylindrical surfaces of rotational bodies, the combination comprising a machine frame; a silk screen stencil; a carriage for said stencil to support the same in a substantially horizontal position; a tlexible scraper cooperating with said stencil; rotatably mounted means to displace said carriage; a rotatably mounted chuck to support the body to be printed upon; a pulley mounted upon the machine frame and rotated synchronously with said displacing means for the stencil carriage; a clutch disc rotating with said chuck and adapted to cooperate with said pulley; locking means to immobilize said chuck when said body is not in printing position; and actuating means to engage and disengage said clutch disc and said pulley in order to exactly position the chuck relative to the stencil carriage and thus to insure coincidence of succeeding printing impressions upon said body; said actuating means comprising a stationary inclined rst plate integral with the frame of the machine; a second plate slidable upon said tirst plate in longitudinal direction, and supports for said chuck with clutch disc and for the said locking means, respectively, mounted upon said slidable second plate.

3. In a silk screen printing machine of the type described for printing upon conical, up to and including cylindrical surfaces of rotational bodies, the combination comprising a machine frame, a silk screen stencil; a carriage for said stencil to support the same in a substantially horizontal position; a llexible scraper cooperating with said stencil; rotatably mounted means to displace said carriage; a rotatably mounted chuck to support thc body to be printed upon; a pulley rotated synchronously with said displacing means for the stencil carriage; a clutch disc integral with said chuck and adapted to cooperate with said pulley; locking means to immobilize said chuck when said body is not in printing position; actuating means to engage and disengage said clutch disc and said pulley in order to position the chuck relative to the stencil carriage and thus to insure coincidence of succeeding printing impressions upon said body; said locking means including a swing lever mounted upon thc machine frame, a lug on one arm of said lever, a radial groove in the chuck cooperating with said lug, and a spring acting upon said lever holding said lug in said groove when said pulley and said clutch disc are in disengaged position.

4. ln a silk screen printing machine ot the type described for printing upon conical, up to and including cylindrical surfaces of rotational bodies, the combination comprising a machine frame; a silk screen stencil; a

carriage for said stencll to support the same in a substantially horizontal position; a exible scraper cooperating with said stencil; rotatably mounted means to displace said carriage; a rotatably mounted chuck to support the body to be printed upon; a pulley mounted upon the machine frame and rotated synchronously with said displacing means for the stencil carriage; a clutch disc rotating with said chuck and adapted to cooperate with said pulley; a locking means to immobilize said chuck when said body is not in printing position; and actuating means to engage and disengage said clutch disc and said pulley in order to exactly position the chuck relative to the stencil carriage and thus to insure coincidence of succeeding printing impressions upon said body; said actuating means comprising a knee lever rockingly mounted on the machine frame and having a substantially vertical arm and a substantially horizontal arm, the said vertical lever arm supporting the said pulley in axial alignment with said clutch disc; a roller mounted at the outer end of said horizontal lever arm; a rotatable cam mounted upon the machine frame and actuating said roller synchronously with the displacing means for the stencil carriage to etect a timely predetermined engagement and disengagement of said clutch and said pulley; said knee lever also actuating said locking means for said chuck when the body is not in printing position.

5. ln a silk screen printing machine for printing upon conical, up to and including cylindrical surfaces of rotational bodies, the combination comprising a machine frame; a silk screen stencil; a carriage for said stencil to support the same in a substantially horizontal position; a flexible scraper cooperating with said stencil; rotatably mounted means to displace said carriage; a rotatably mounted chuck to support the body to be printed upon; a pulley rotated synchronously with said displacing means for the stencil carriage; a radial groove in said pulley; a clutch disc integral with said chuck and coaxial with said pulley; a projection on said clutch disc to enage said radial groove; locking means to immobilize said chuck when said body is not in printing position;

and actuating means to engage and disengage the projection of said clutch disc with and from the radial groove in said pulley in order to exactly position the chuck relative to the stencil carriage and thus to insure coincidence of succeeding printing impressions upon said body; said actuating means comprising a stationary inclined rst plate integral with the frame of the machine; a second plate slidable upon said first plate in longitudinal direction, and supports for said chuck with the clutch disc integral therewith and for the said locking means, mounted upon said slidable second plate.

6. A silk screen printing machine according to claim 1, wherein the said locking means to temporarily immobilize said chuck comprise a brake acting upon the chuck and a spring actuating said brake when said clutch disc and said pulley are disengaged.

7. A silk screen printing machine according to claim 6 comprising a stationary member adaptedv to disengage said brake when the said clutch disc and the said pulley are being engaged.

8. A silk screen printing machine according to claim 2 comprising a support for said pulley mounted upon said stationary second plate, said locking means comprising Ia brake that acts on the chuck, a stationary member l0 adapted to disengage said brake when the slidablc second plate is moved into a position effecting the coupling between the clutch disc and the pulley, said stationary member being integral with said support, and means integral with said brake and adapted to secure said slidable second plate in said position.

9. A silk screen printing machine according to claim 1 wherein the actuating means to engage and to disengage said clutch disc and said pulley include a rockable shift lever supporting said pulley, said shift lever actuating the said locking means.

References Cited in the file of this patent UNITED STATES PATENTS Martin July 12, 1951