US2624276A - Screen printing machine - Google Patents

Description

Jan. 6, 1953 1. D. KLoPFENsTl-:IN

SCREEN PRINTING MACHINE 8 Sheets-Sheet l Filed Dec. 16, 1947 mm' r Q N. 5 Vl 1 ,1. r i J/ G x n o. mm, mm .S @QN 1-.---- .ww mm Jan. 6, 1953 J. D. KLoPFENsTElN SCREEN PRINTING MACHINE 8 Sheets-Sheet 2 Filed Dec. 16, 1947 IN V EN TR. JSSJ. Klolvfen 5 Zezm Jan. 6, 1953 J. D. KLoPFENsTElN SCREEN PRINTING MACHINE 8 Sheets-Sheet 5 Filed Dec. 16, 1947 lllllll-IIIIIIIIIII llullll In- INVENTOR.

Jan 6, 1.953 J. D. KLOPFENSTEIN scREEN PRINTING MACHINE 8 Sheets-Sheet 4 Filed Dc. 1e, 1947 Sw.. @Nw @EN A JSSDf Jan. 6, 1953 Jy. D. KLoPr-'ENSTEIN 2,624,276

SCREEN PRINTING MACHINE Filed Deo. 1e, 1947 8 .sheets-sheet 5 Jan. 6, 1953 .1. D. KLOPFENSTEIN SCREEN PRINTING MACHINE 8 Sheets-Sheet '7 Filed Dec. 16, 1947 VN l Jan. 6, 1 953 J. D. KLOPFENSTEIN 2,624,276 1 SCREEN PRINTING MACHINE Filednec. 16, 1947 8 Smets-sheet 8 IN V EN TOR.

Patented Jan. 6, 19.53

SCREEN PRINTING MACHINE Jess D. Klopfenstein, Oak Park, Ill., assignor to The Meyercord Company, Chicago, Ill., a corporation of Illinois Application December 16, 1947, Serial No. 791,955

14 Claims.

This invention relates to a screen printing machine and more particularly to a novel form of squeegee mechanism adapted to be reciprocated over a stencil screen and to a novel form of clutch mechanism by means of which the operation of the squeegee mechanism and other moving parts of the machine may be stopped with the machine in open position for adjustment without eiiecting stoppage of the entire machine.

One of the principal objects of the present invention is to provide a screen printing machine having a squeegee mechanism in accordance with which the squeegee prints in one direction only and not on its return stroke.

Another object of the invention is to provide a reciprocating -squeegee mechanism for a screen printing press having a squeegee adapted to print in one direction only and a scoop adapted to pick up a quantity of the printing ink at the end of the printing stroke and to transport it on the return stroke to the other end of the screen where it is spilled in front of the squeegee prior to the beginning of the printing stroke.

Another object is to provide a reciprocating squeegee mechanism for a screen printing machine having a squeegee adapted to engage the stencil screen and print in one direction only and to be disengaged therefrom on the return stroke, and also having a movable scoop adapted to pick up a quantity of printing in k at the end of the printing stroke and transport it to and deposit it at the other end of the screen, said squeegee and said scoop being movable to their various positions 'by automatic means at the kends of the printing and return strokes.

A further object of the invention is to provide a screen printing machine having a printing bed movable to and from printing position and under a stencil screen and a squeegee mechanism adapted to be reciprocated over the stencil screen for printing in one direction only and for return movement in the otherV direction, the squeegee mechanism being provided with a printing squeegee adapted to engage the screen on the printing stroke only and an ink spreading member adapted to engage the stencil screen only on the return stroke when the screen is unsupported by the printing bed which is in withdrawn, inoperative position.

A still further object is to provide a squeegee mechanism for a screen printing machine having a squeegee adapted to print against the stencil device being adapted to pick up a quantity of ink at the end of the printing stroke and transport and deposit the ink at the other end of the screen on the return stroke, and the ink spreading member being adapted to engage the stencil screen on the return stroke and to spread ink thereover and therein when the screen is unsupported by the printing (bed which is in withdrawn position.

Another further object is to provide a squeegee mechanism of the character referred to in the foregoing object and having automatic means operable at the ends of the printing and return strokes for moving the squeegee, the scoop or the ink spreading member to their various operating positions.

Another object is to provide a screen printing machine in which the moving parts, which may include a reciprocating squeegee mechanism, a movable .printing bed, a rocker cradle and a squeegee elevating mechanism, are driven oi of a common shaft and in which a novel form of clutch mechanism is interposed in the driving connections between the source of power and the shaft, the clutch providing means by which the squeegee mechanism and the other moving parts may be stopped without causing stoppage of the other elements of the machine.

A further object is to provide a novel form of clutch mechanism by which certain moving parts of a screen printing machine may be caused to cease operation without causing stoppage of the entire machine, thereby .permitting adjustment of the machine while still in partial operation and when in open position.

Still another object of the present invention is -to provide novel means and structures by which the foregoing objects may be accompli-shed.

Other and further objects and advantages of the invention will become apparent as this description progresses, reference ,being had to accompanying drawings, in which:

Figure 1 is a side elevational view of a rocker screen printing machine on which are operably mounted the novel squeegee mechanism and the novel clutch mechanism for stopping operationv of the squeegee mechanism as Well as other movable parts and comprising the present invention;

Fig. 2 is an enlarged, fragmentary, side perspective view of the upper portion of the machine showing a squeegee mechanism comprising one embodiment of the present invention;

Fig. 3 is an enlarged, fragmentary side elevational vieW of the squeegee mechanism shown in Fig. 2, certain of the parts thereof being shown in broken lines and the mechanism being shownl in its position as it approaches the end of the printing stroke;

Fig. 4 is a view similar to Fig. 3 but showing the relative positions of the squeegee and scoop during the return stroke;

Fig. 5 is a fragmentary, elevational view of one end of the squeegee mechanism as viewed from the feeding end of the machine;

Fig. 6 is a side elevational View taken on the line 6 6 in Fig. 5, looking in the direction of the arrows, and showing the scoopoperating mechanism and showing the scoop in horizontal, ink supporting position on the return stroke;

Fig. 7 is a view similar to Fig. 6 but showing th scoop in its depending, ink-depositing position on the printing stroke;

Fig. 8 is an axial, fragmentary view of a novel type of clutch mechanism comprising one embodiment or" the present invention and mounted on the shaft for driving the squeegee mechanism and certain other moving parts of the machine, the parts being shown in driving, clutched position;

Fig. 9 is a view similar to Fig. S showing the parts latched in declutched position;

Fig. 10 is a side elevational view of the clutch mechanism shown in Figs. 8 and 9;

Fig. 11 is a vertical sectional view of the clutch mechanism taken on the line H-II in Fig. 9, looking in the direction of the arrows;

Fig. 12 is a fragmentary, top View taken on the line l2-i2 in Fig. 1, looking diagonally downwardly in the direction of the arrows:

Fig. 13 is a fragmentary, perspective View of one end portion of a second form of squeegee mechanism comprising the present invention in which a scoop or an ink spreading member may be interchangeably mounted;

Fig. 14 is a vertical sectional view taken on the line M-lfi in Fig. 13 and showing the printing squeegee, the scoop and ink spreading member as they appear during the printing stroke;

Fig. 15 is a vertical sectional view similar to Fig. 14 but showing the relative positions of the parts on the return stroke;

Fig. 16 is a side elevational view of the second embodiment of squeegee mechanism as viewed from the left in Fig. 13 and showing the relative positions of the parts-during the printing stroke; and

Fig. 17 is a View similar to Fig. 16 but showing the relative positions of the parts during the return stroke.

General construction of machine Referring more particularly to Figs. 1, 2 and 12 of the drawings, the rocker screen press therein illustrated comprises a main upright frame of generally rectangular character. This frame includes four corner upright members 2Q, longitudinal top and lower rails 2l and 22, respectively, and transverse rails 23. The source of power for operating the machine is an electric motor 244 which drives a pulley by means of a belt drive 2. The pulley 26 is secured on one end of the main drive shaft 2% of the press, the shaft 25 being rotatably supported by bearing members 29 carried by the main frame. A large gear 30 is secured for rotative movement on the main shaft 28 and is in constant mesh with another large gear 3l loosely carried on another rotatable shaft 32 journaled in bearing members 33 also supported by the main frame. Rotation of the shaft 32 is eected by the gear 3! through a novel form 4 of clutch mechanism indicated generally by the numeral 3d in Fig. 12 and to be described more fully hereinafter by reference to Figs. 8 to 11, inclusive, wherein the mechanism is shown in enlarged detail.

The upper central portion of the press is provided with an opening adapted to receive a vertically movable table or bed 3% carried by triangularly shaped side supports 3l connected at their pointed lower ends by a transverse rod 33. A link 39 is pivotally secured at one of its ends to the rod 33 and at its other end the link 3S is fixed to a rotatable shaft et# journaled in bearing brackets il mounted on the main frame. A lever 42 has its lower end fixed to the shaft i and its upper or free end is provided with a roller 43 which, under the weight of the printing bed 3b and the supports El, is adapted to be maintained in constant bearing engagement with a rotating cam is secured on the main drive Shaft 28. Thus, as the lever d2 is rocked downwardly in a counterclockwise direction or is permitted to move upwardly by the cam i3d, the bed supports 3l and the bed 35 are raised or lowered in timed relation to movement by other parts of the machine during operation. The vertical reciprocal movement of the platen supports 3l is controlled and guided by spaced rollers i5 carried by the supports 37 and adapted for rolling movement in vertical tracks formed in spaced upright members d5 and 45a secured in vertical position between the upper and lower frame rails 2i and E on each side of the machine.

Over the platen table 3%, as shown in Figs. l and 2, there is a stencil screen 47 stretched within a frame ed secured within a curved support or cradle dii, the cradle de being adapted for rocking movement in a longitudinal direction on the upper portion of the press. The rocking movement of the screen cradle i9 is accomplished by means of semi-circular brackets 50 secured to the under side thereof at each side of the machine, the brackets having depending plates 5i pivotally connected at their lower ends to the right ends of horizontal links 52. The other ends of the links 52 are pivotally and eccentrically secured to a rotatable disc 53 secured on the rotatable shaft 32, and consequently, upon rotation of the disc 53 the screen cradle t9 is rocked through the links 52, the plates 5l and the brackets 5o. By such rocking movement the stencil screen li'i is caused to be peeled cleanly and without smudging from the imprinted sheet supported on the printing bed St.

Preparatory to printing, a plurality of sheets may be placed upon a table 5d at the feed end of the press, which is the right side thereof as viewed in Fig. l, where the operator may be stationed. The sheets are adapted to be fed into the press by the operator and their forward ends are engaged in the usual manner by a plurality of gripper bars 5S carried in spaced relation by spaced conveyor chains 57 extending around sprocket wheeis 58 rotatably supported at the feed and delivery ends of the press. Movement of the conveyor chains 5l isin the direction of the delivery end of the machine, or to the left as viewed in Fig. l, so that the gripped sheets .are moved from the table 54 to the printing position on the platen 36 from which they are moved, after printing, to the delivery end of the machine from which they are removed for drying.

Movement of the conveyor chains 5l is eiected by movement of the sprocket wheels 53 at the delivery end of the press which are fixed on a rotatable'cross shaft 59 to which is also fixed a sprocket wheel 60 engaged by a chain 6l. The chain 6I passes over an idler sprocket 62 and is driven by a sprocket Wheel 63 secured on a spindle 64. A gear 66 is also secured on the spindle 64 and meshes with another gear 61 mounted on the main drive shaft 28, which upon rotation causes movement of the conveyor chains 51 through the above described driving mechanism.

The squeegee mechanism The squeegee mechanism, indicated generally by the numeral 68 in Figs. l and 2 of the drawings, extends transversely across the top of the press and is adapted to be reciprocated over and against the stencil screen 41 to cause an imprint to be made in the usual manner on the sheet supported therebelow on the platen bed 36. In accordance with the novel means to be described in detail hereinafter the squeegee 68 is adapted to engage the stencil screen for printing only as it moves from its left hand position adjacent the delivery end toward the operator alt the feed or right end of the press. Upon its return movement to the left, the squeegee mechanism 68 is maintained in raised position above and out of contact with the screen 41 so that printing is accomplished only in one direction with the result that the sheets need not be segregated as is -the case where the squeegee prints in both directions of movement. Ivt has been found that a slight stretching or distortion of the stencil screen occurs in the direction of movement of a squeegee and, hence, it is necessary that all prints on a sheet be made in the same direction in order to prevent overlapping of the colors of the various prints constituting the completed design.

The reciprocal printing and return movement of the squeegee mechanism 68 is, like the vertical movement of the bed 36 and the rocking movement of rocker cradle 49, accomplished by driving connections with the rotatable shaft 32. These connections comprise a short crank 69 eccentrically pivoted at one end to the rotating disc 53 on the shaft 32 and having its other'end pivotally secured to the end of a vertical link 10 which extends downwardly into pivotal engagement with the end of a crank 1|. The other end of the crank 1I is fixed to a rocker shaft 12 journaled in a bracket 13 on the main frame and likewise the lower ends of a pair'o-f large vertically directed levers 14 are also fixed to the rocker shaft. The levers 14 extend upwardly on the outside of the main frame adjacent the delivery end of the press and their respective upper ends are pivoted to the left ends of horizontal links 16 which extend to the right in secured engagement with the squeegee mechanism 68. Thus, as the shaft 32 is rotated in a clockwise direction as viewed in Fig. 1, the link 10 is moved downwardly causing the crank 1l to also turn in a clockwise direction.V As a result, the shaft 12 is also rotated in a clockwise direction which moves the upper ends of the vertical levers 14, the links 16 and the squeegee mechanism 68 toward the right on its printing stroke. Upon continued rotation of the shaft 32 in the clockwise direction, the vertical link 10 is pulled up-wardly causing movement of the vertical levers 14 to the left, thus pulling the squeegee mechanism 68 to the left on its return, non-printing stroke..

4The squeegee mechanism 68, as shownmore particularly in enlarged detail in Figs. 2 to 7, inclusive, of the drawings, comprises an elongated angular plate 11 which extends transversely of the press and has its respective ends rigidly secured to the upper portions of vertical end plates 18, the end plates 18 and the transverse plate 11 constituting the squeegee frames. The lower portions of the end plates 18 are pivotally secured to the right ends of the horizontal links 16, respectively, and this assembly is braced by an angular strap member 19 extending between a transverse rook shaft and an upstanding bar element 8l rigidly secured at one side of the machine to the inner surface of one of a pair of horizontal links. The respective ends of the rock shaft 88 are journaled in the upper ends of the end plates 18 immediately beneath the angular plate 11.

The squeegee support proper comprises a transversely extending angular plate member 82 bolted to the left portion of the main angle plate 11 and to which two spaced handles 83 are secured to facilitate handling for installation and adjust- 'ment of the squeegee unit. The squeegee blade 84, which may be composed of rubber or other suitable flexible material, is clamped to the lower end portion of the angular plate 82 by means of an elongated, at plate 86 bolted to the upper surface of the angular plate 82 and it extends downwardly beyond the plates 82 and 86 so as to flexibly engage the stencil screen 41 on its printing stroke.

On the lower right side of the squeegee mechanism 68 adjacent to and ahead of the squeegee blade 84, there is provided a pivotally movable scoop 81 extending across the stencil screen 41 and adapted to scoop up a quantity of the printing ink from the mass thereof :at the right or fountain end of the screen and to transmit the ink to the left end of the screen upon the return stroke of the squeegee mechanism. As the end of the return stroke is reached, the scoop 81 is tipped so as to spill its contents onto the stencil screen 41 ahead of the squeegee and thus afford an adequate supply of ink for the squeegee blade 84 on its printing stroke. 'I'he scoop 81 is shown in depending, spilling position in Fig. '1 and in horizontal, ink transmitting position in Fig. 6. The scoop 81 is rigidly secured by means of bolts 88 and an angle plate 89 to an elongated bar 98 which is rectangular in cross section and has reduced cylindrical ends 9| journaled in a pair of depending bearing plates 92. The bearing plates 92 are rigidly secured at their upper ends to another elongated angle iron 93 which is in turn rigidly secured to the right portion of the main angular supporting member 11 of the unit. It will thus be seen that the scoop 81 is adapted for' pivotal rocking movement relative to the squeegee unit by the pivotal mounting of the scoop supporting bar 96 on the bearing plates 92.

As shown in Figs. 2, 5, 6 and 7, the rocking movement of the scoop 81 is effected by means of a segment 94 rigidly secured to and depending from the main rock shaft 80 for rotation therewith adjacent the outer side of one of the end plates 92. This segment 94 meshes with a small gear segment 96 secured on one of the journaled ends of the rotatable cross bar so that upon rotation of the main cross shaft 80 the scoop will be caused to pivot in one direction or the other depending upon which end of its stroke the squeegee mechanism is being moved. Rotation of the main shaft 80 is accomplished by means of a.pendu1umshaped rocking'arm 91 fixed on the main. shaft; 80 for rotation therewith between the one end plate 18. and the bracing strap 19; The

arm 9.1 is provided intermediate its ends withan arcuate s1ot'98 through which projects the stud t9 connecting the horizontal link i6 to the end plate-1B, this construction permitting the arm 91 to rock freely relative to the end plate 18 and'l the. stud 9e. The lower end 97a or" the rocker arm 9! is heart shaped and is adapted to engage spaced stops i' which may be. secured on the upper ends of the rocker screenV bracket 5U. The stops |00 project upwardly into the path ofmovement of the arm @l adjacent each end of the squeegee stroke with the result that the arm 91 will be rocked as the squeegee unit approaches either end of' its stroke, thus causingthe scoop 81 to be pivoted up or down from the depending to horizontal position and return.

in Fig. l the rocker arm 9i is illustrated in its posi-tion just after it` has been rocked'. tothe right in a counterclockwise direction at the end of its return stroke by engagement with the left stop |99. By such rocking action, the scoop 31 has been turned downwardly to the position shown in Figs. 3 and 7, so as to spill a major portion or its ink contents ahead of the squeegee 8d. In this position the scoop i'i is still in spaced position above the stencil fil. However as the squeegee starts back on. its printing stroke in engagement with the stencil screen, some of the printing ink is still contained in the inclined scoop 87| and it continues to drip therefrom ahead of the squeegee 8s during the printing stroke, thus further insuring an adequate supply of print-. ing ink ahead of the squcegee, which, of. course, is also pushing before it the ink supply spilled by the scoop.

in Fig. 3 of the drawings, the squeegee mechanisrn is shown as it appears at the end of its printing stroke just as the rocker arm Si? engages the right stop 'iil but before it has been rocked thereby. Upon continued movement of the sdueegee mechanism 68 to the right, the rocker arm 9.? is swung to the left, as shown in which causes thev scoop 8'! to pivot in a counterclockwise direction until it assumes` the horizontal position shown in Figs. i and 6. As the scoop al moves from its downward orv depending position to its horizontal position, its iront iip is caused to scrape against the top of the stencil screen at its right end under the mass of printing ink so as to cause a quantity of the printing ink to pass onto the scoop. The scoop 87 remains. in its horizontal, ink-retaining position all during the return, non-printing stroke away from the operator, and during the return stroke some printing ink drips from the front lip of the scoop onto the stencil screen, thus providing an additional. small quantity of ink for spreading by the squeegee 8d on its printing stroke. The scoop ed is of such extent that it will be held in elevated position from the stencil screen tl during the printing and return strokes but upon rotation is capable of extending downwardly into scraping contact with the screen. di. In order that the scoop Bl may be retained in either its horizontal or downward positions, there is provided a yieldable latch mechanism. shown in detail in Figs. 3 and. 4 andv comprising. a horizontal arm itil pivotally secured on a stud E62 carried by the upright bar elementi 8|. This pivoted latch arm lli! is constantly. urged upwardly into engagement with a roller m3', c-arried on` the intermediate portion of the` rocker.

arm. 91, by, means of a spring; I M` supported.

aroundv the stud |02 and` engaging' the arm I (1| intermediate itsends. The yieldablevlatch arm |0| is provided onv its upper surface intermediate its ends with a raised abutment |06 so that the roller IGS may be retained on the top surface of the arm Il on one side or the other of the abutment |66. `When the scoop 81 is in its down position, the roller |93y is positioned on the right side or the abutment |66, as shown in Figs. i and 3, and when the scoop 81 is in its horizontal position the roller |03 is on the left side in engagement therewith, as shown in Fig. 4. Hence, as the rocker arm Sl is rocked by engagement with the stops lill), the roller |03 moves downwardly in an arcuate path and depresses the latch arm lill and passes over the abutment |06. The roller |53 engages the abut-ment IE6 when scoop 8l is in horizontal position, but is considerably beyond the abutment when the scoop is in downward position, the yieldable engagement between. the roller |03 and the latch arm itl being suilicient to retain the rocker arm 9| in its respective positions.

|The squeegee 84 being rigidly mounted remains in the same angular position at all times as shown in Figs. 3 to 7, inclusive, of the drawings. iiowever, it is in contact with the stencil screen li only during the printing stroke to the right and during the return stroke it is held in elevated position out of screen Contact; Elev-ation of the squeegee 8e is accomplished by elevation of the entire squeegee mechanism 63 in the following manner.. Each of the end plates 'I8 is provided with a roller lill on its inner side which respectively engage the top surfaces of slidable tracks its mounted on each side of the machine along the top of the frame, and, yas the squeegee mechanism E8 reciprocates on its printing and return strokes, the rollers l'l roll `along the tracks Hi8 rst in one direction. and then the other. rEhe rollers ill are held down on the tracks |36 by spring tensioned rods |05 pivotally secured to the ends of the squeegee rock shaft 89.

The tracks HiB, as shown in Figs. l and Y2, are provided at their left ends with inwardly directed studs its slidably mounted in diagonal slots Hl) formed in opstanding brackets I|| secured to the longitudinal frame member 2 I.. At their right ends the tracks |68 are each provided with integral arms H2 which extend downwardly and rearwardly toward the feeding end of the machine adjacent the, operator. The lower ends oi the track arms il? are pivotally secured to one end of short links lit` which have their other ends xed to a cross rock shaft H journaled in brackets i le secured to the. right upright members 23. Another short vertical linkv has its lower end fixed to the rock shaft ||4 and its upper end is pivotally secured to the right end of a long horizontal link H3 which extends to the left over the shaft 32 into pivotal engagement with the upper end of a vertical lever |I9. This latter lever I9 is pivotally supported at its lower end on Va. stud- H25 supported on the main frame and it is provided intermediate its ends with a roller [2| which is in constant bearing engagement with a cam 22 rotatably carried on the shaft. 32.

As, the cam |22 rotates, the long link ||8 is moved back and forth, rocking the short links ||1 .and I |.3 and raising and lowering the tracks Hi8; When the tracks IS are raised lat the end of the printing stroke, the studs |09 in their left ends slide upwardly in-to theupper end of the bracket vslots ||il Where they remain. during-i the entire return stroke of the squeegee mechanism 88, the lower ends of the tracks being supported against downward movement by the link mechanisrn under the urge of the cam |22. At the end of the return stroke, the tracks |08 are lowered, thus causing the squeegee 84 to engage the stencil screen 41 for the printing stroke.

In addition to the above-described 'automatic means for elevating the tracks |08 and consequently the squeegee mechanism 68, there is provided a treadle mechanism accessible to the operator at the feed end of the machine, as shown in Fig. l. This mechanism comprises a vertically movable treadle |23 on the end of a lever |24 pivotally secured to one upright frame member 20. A vertical link |26 is pivoted to the lever |24 intermediate the ends thereof and extends upwardly through a block |21 in slidable relation therewith, the block |21 being secured on the end of a short link |28 which has its other end fixed on the rock shaft ||4 for movement therewith. The vertical link |26 in normal position extends "above and beyond the block |21 and on its upper end has an enlarged head |29 adapted to engage the block |21 when the treadle |23 is depressed by the operator. By reason of this lost motion lconnection, the rocking movement of the short link |28, which is occasioned, through the automatic linkage by the cam |22, does not cause unwanted movement of the link |26 or the treadle |23. However, should the operator for anyreason desire to elevate the squeegee mechanism 68 during its printing stroke,. he may do so by depressing the treadle mechanism which rocks the shaft H4 and hence raises the tracks |08.

At the top of the machine and on each side thereof, the horizontal, leveling links |30 are rigidly connected at their right ends to the stud-s 99 of the end plates 18 of the squeegee mechanism 68 and their left ends are pivoted to the upper ends of vertical levers |3| disposed inwardly adjacent the vertical levers 14. The lower ends of the levers 3| are in turn pivoted to short cranks |32 fixed on a cross rock shaft |33. A gear I 34 is also fixed to the shaft |33 and meshes with a gear segment |36 fixed on the shaft 12. Thus when the shaft 12 is rocked by movement of the lever 1| and the link 12, the segment |36 also is rocked so as to reciprocate the vertical lever |3| in a vertical direction. This vertical movement of the lever |3| draws down or raises the left end of the horizontal link |30 and hence the link |30 is maintained in substantially -a straight line relative to the scueegee as the vertical lever 14 reciprocates the lsqueegee mechanism 68 on its printing or Vreturn strokes. By m-aintaing the link |30 in such a straight line, the snueegee is held in proper angular position for printing.

The clutch mechanism During operation of the press, it quite often becomes necessary for the operator to have immediate and ready access to the interior of the machine. Frequently, splinterS, specks or other foreign matter become lodged in the under surface of the stencil screen 41 or on the upper surface of the bed 33 so :as to interfere with the printing operation. Also it frequently happens that the sheet guides become out of registry and other parts become misadjusted, al1 of which require readjustment. It is, therefore, an important feature of the present invention to provide a means by which the machine may be opened up and the squeegee mechanism 68 and certain other elements thereof stopped in their movement without stopping the entire machine operation. Such means is provided by driving all the machine elements which are required to be stopped during the period of adjustment or cleaning, by the rotatable shaft 32 and by providing a novel type of clutch mechanism 34 by which the driving connection between the main drive shaft 28 and rotatable shaft 32 may be completed or broken under control of the operator. It is apparent that lsince the respective movements of the rocker cradle 40, the printing bed 36, the squeegee mechanism -68 and the tracks |08 are all effected by rotation of the shaft 32, the breaking of the driving connection to the shaft 32 through the clutch 34 will result in stoppage of al1 those elements simultaneously. 1

The clutch mechanism 34 is so constructed and arranged with respect to the operation of the above-named elements that when the driving connection is broken, the bed 36 is stopped in its lowered position and the squeegee unit 68 is at the end of its printing stroke with the squeegee blade 84 still in contact with the top surface of the stencil screen 41, thus serving as a dam to prevent the flow of the mass of printing ink material from the fountain end of the stencil out over the screen while adjustment is being made. An important feature of the clutch mechanism 34 is that the point of clutching and declutching is always constant'so that the bed 36, squeegee unity 68 and blade 84 will always be stopped in the same desired positions. But at the same time provision is made for the operator to actuate the clutch mechanism at any point in the cycle in anticipation of clutching or declutching at the constant point in the cycle.

The clutch mechanism l34, shown in detail in Figs. 8 to 11, inclusive, of the drawings, comprises a rotatable sleeve |40 having portions |4| and |42 of different diameters and an annular ange |44, the sleeve |40 being mounted on bushings |43 and |45 carried on the rotatable shaft 32 for free relative rotative movement independently thereof. The sleeve |40 is confined on the shaft 32 against axial movement by a collar |46 xed to the shaft 32 on the right side of the sleeve, as viewed in Fig. l1, and by other clutch mechanism fixed on the shaft 32 on the left side thereof. The large gear 3| and its hub portion 3|a are carried on the sleeve portion |4| and the sleeve portion |42 extends through a stationary cam plate |48, being spaced therefrom for free rotative movement relative thereto by a bushing |48a. The annular flange |44 of the sleeve |40 is disposed between a cam lock plate |41 and the end of the bushing |4811. The gear 3|, the cam lock plate |41, and the sleeve |40 are secured together for rotation as a unit by means of ka plurality of axially extending bolts |49,A the bolts extending through the cam plate |41, the enlarged sleeve portion |42 and into the gear 3|. The stationary cam plate |48 extends downwardly and adjacent the gear 3| and the lower end |48?) is bolted to a horizontal stationary base plate |50. The cam plate 48 is thus xed against rotation Whereas the sleeve |40 and the gear 3| and the cam lock plate |41 are capable of rotation as a unit relative thereto, the opposed surfaces between the said stationary and moving parts being machined for a running t on the bushings |43, |45 and |48a. When the machine motor 24 is in operation, the gear 3|, the sleeve |40 and the cam lock plate |41 are in constant rotation and remain in rotation even when the out of clutched position. Conversely, when the operator desires to restore the parts to clutched position, the shaft is rocked in the other direction or counterclockwise so as to turn the side cam 18 and the dog |66 out of their operable vertical positions, thus freeing the rocking lever lug |64 and permitting rocking movement of the lever |56 in a clockwise direction under the urge of the spring I6I. Thus, the roller |51 is free to and does drop into the recess |59 into locking engagement therewith as the cam lockplate |41 rotates relative to the rocking lever |56. Simultaneously, the locking plate |69 is carried by the clamp shaft arm away from the curved locking spring |68, thus releasing the slidable spring holder |19 for movement to the left, such movement to the left being permitted by the earlier restoration of the side cam |16 to normal position. As the spring holder |19 slides to the left, the curved spring |68 is likewise carried to the left out of the path of movement of the locking plate |69.

It is thus apparent that a simple and eicient clutch mechanism has been provided by which the squeegee mechanism 68 and the other elements operated off the shaft 32 may be readily thrown into and out of operation whenever the screen 41 or the bed 36 require attention or Whenever other parts of the machine require adjustment. When the operator notes that the machine requires such attention, he may immediately depress the treadle |84 in order to declutch the mechanism without waiting for the moving parts to reach the exact and desired points in their cycles. It is consequently unnecessary that he pay close attention to the moving parts in order that the mechanism be declutched at any exact point of time, for as soon as the treadle |84 is depressed the dog |66 is turned upwardly into active position where it is thereafter engaged by the lug |64 of the rocking lever |56 upon continued rotation of the clutch parts. During continued rotation of the clutch parts after depression of the treadle |84, the printing bed 36, the squeegee mechanism 68, the rocker cradle 49 and the tracks |08 continue in their movement to their desired inoperative positions and when such positions are reached by the parts it is at that instant that the dog |66 is engaged by the lug |64 thereby declutching the parts as above described. All of the other parts driven off the main shaft 28, however, remain in operation when the clutch mechanism is in declutched position, thus enabling the operator to adjust the sheet guides properly during operation of any other parts.

Second embodiment of squeegee mechanism In Figs. 13 to 17, inclusive, of the drawings, there is illustrated another form of squeegee mechanism which is generally .similar in principle and operation to the squeegee mechanism 68 disclosed in Figs. 1 to 6, inclusive, but which has additional features and advantages. This second embodiment comprises a pair of hook-shaped end plates 200 secured at each side yof the machine to an elongated plate 202 extending across the machine and being inclined at an angle of approximately 45 to the stencil screen 41. As shown in Fig. 13, the end plates 200 are provided on their inner faces with rollers 203 which are adapted to engage the top surfaces of the tracks |06 and to support the entire squeegee mechanism on its printing and return strokes as do the rollers |01 of the squeegee mechanism 68. The end plates 200 also serve as bearing supports for a transverse rock shaft 204, the respective ends of which are journaled in the upper portions of the end plates. The left end plate 200, as viewed in Fig. 13, further serves as a support for a short rock shaft 206, one end of which is journaled in the end plates 200 and the other end of which is supported for rotative movement in a depending bearing support '201 secured to the under surface of the inclined transverse plate 202 some distance inwardly from the left end plate 200.

The end plates 200 are adapted to be secured at the lower portions of their outer faces to the ends of the horizontal links 16, the movement of which will control and effect movement of this form of squeegee mechanism in the same manner as in the first form 60. A flat squeegee supporting plate 208 is secured to the inclined upper surface of the transverse plate 202, extending angularly downwardly toward the stencil screen 41, and at its lower end there is a flexible squeegee 200 clamped thereto by a at clamping plate 210. The squeegee 202 is of sufficient length as to engage and bear against the stencil screen 41 on the printing stroke and to be spaced therefrom when elevated by the tracks |06 for the return stroke.

Similar to the squeegee mechanism 68, there is provided 4a readily detachable and pivotally supported scoop 2II which is secured on an elongated bar 2|2 of rectangular cross section whose reduced respective ends 2|2a are journaled in depending bearing brackets 2I3 secured to the under inclined surface of the transverse plate 202. As shown particularly in Figs. 13 and 14, a gear segment 2|4 is secured on one end of the rock bar 2|2 and meshes with a segment 2I6 mounted on the inner end of and depending from the short rock shaft 206. Thus, upon rocking movement of the shaft 206, the scoop 2|| may be caused to move from depending vertical, ink-spilling position to horizontal. ink-retaining position in precisely the same manner as described above with respect to the squeegee mechanism 68.

Rocking movement of the short shaft 206 in first one direction and then the other is accomplished as shown clearly in Figs. 13, 16 and 17 by a depending actuating arm 2|1 p-ivoted at its upper end on a stud 2 I8 to the left end plate 200 and having a roller ZIS on its lower end for engagement with the stops |00 lat either end of the machine. Intermediate its ends, the arm 2|1 is secured to the end of a triangular plate 220 by means of a, headed stud 22| having a projecting shank in constant bearing engagement with the upper surface of a yieldable locking arm 222. This arm 222 is pivoted at its left end to the outer side of the left end plate 200 on a pin 223 and at its right, free end it is connected to a tension spring 224 extending upwardly and having its upper end secured to a stud 226 on the left end plate 200, the spring 224 serving to maintain the iocking arm 222 in horizontal position and to resist its pivotal movement in a downward or clockwise direction.

The left end of the triangular plate 220 is connected by means of studs 221 and 228 to the ends of toggle links 229 and 230, respectively. The lower end of the link 229 is pivoted to the end plate 200 by a stud 225 and the upper end of the link 230 is secured to the right end of an arm 23| by means of a stud 232. The left end of the arm 23| is secured -to the end of the short rock shaft 206 which projects beyond the outer faceofthe endplate 200.

Inaccordancewith the foregoing arrangef ment of parts, when the squeegee mechanism approaches the end of its printing stroke, the roller 2 l will first engage the stop it@ and continued movement of the squeegee mechanism under the control of the link '5S will cause the actuating arm Eil to be rocked in a clockwise direction from the Fig. 16 position to the Fig. 17 position. This movement forces the triangular plate 226 to the left, the stud 22! on the arm 2li moving slightly downwardly in an arcuate path so as to depress and slide along the top edge of the locking arm 222 until it becomes engaged in a recess 233. At this point, the lparts are in the position shown in Fig. 17. As the plate 220 is moved to the left the adjacent ends of the toggle links 229 and are also moved to the left, movement of the link Z-l being also downwardly so as to pull down the arm 23l in a clockwise direction which in turn rocks the short shaft 2te in the same direction so as to raise the scoop 2| l. Conversely, when the squeegee mechanisrn approaches the end of its return stroke to the left, the actuating lever 2li is forced to the right in a counterclockwise direction by the other stop itil, thus restoring the moving parts to their Fig. lo position and lowering the scoop 2| l.

The ink spreading member The form of squeegee mechanism shown in Figs. 13 to 17, inclusive, of the drawings also has provision for the removal of the scoop 2H from its square supporting bar 2li? and for the attachrnent of a special form of a second flooding squeegee or ink spreading member, as shown particularly in Figs. i4 and 15. IThe additional squeegee and the scope 2li are not intended to be carried and operated at the same time, but it is intended that one be removed while the other is in operation. However, in Figs. lll and l5 of the drawing and for the purposes of this description both the elements are shown mounted on the squeegee frame at the same time. This ink; spreading member comprises a vertically arrange-:l flexible squeegee 2te clamped to the lower end of a transverse plate 23'! by a clamping plate 2t the transverse plate 23'! being bolted to a bar 239 extending transversely of the machine in front of and over the scoop supporting bar 2&3. The respective ends of the squeegee supporting bar 23e are rigidly secured to horizontal levers 2da adjacent the ends thereof and the other ends of the levers 2de, which pro ject under and beyond the main cross plate 22 toward the delivery end of the machine, are pivoted to the ends of fixed inclined arms 24! secured to the upper inclined surface of the main cross plate 2%.

The ends of the levers Zdiii adjacent the bar 239 are pivotally connected by pairs of links M2 to the ends of rock arms 2% iixed on the long rock shaft Zeil, so that upon rotation of the shaft Ritt in a clockwise direction the rocker arms tilt will be moved downwardly from their Fig. 14 position to their Fig. 15 position wherein the flat bar is in lowered position ahead of the scoop bar 2 i2 and the pairs of links are in parallel alignment with the rocker arms 21433. When the fiat bar y23E is lowered, the needing squeegee 236 which it supports will consequently be forced down into engagement with the upper surface of the stencil screen where it remains during the return stroke.

In order to effect rotation of the long shaft 29e and consequent-raising and lowering of the squeegee 23E, there is provided a lever 24e fixed at one end on the shaft 2cd adjacent theA end plates the lever Efili being provided at its other end with a pair of downwardly extending plates :ist between the lower ends of which a roller 2li? is rotatably supported. The roller 2li? is adapted to bear against and ride the upper surface of a lever 2&5 which is fixed at its other end to the short rock shaft 235, the roller 2e? being caused to bear downwardly against the lever 2638 only by gravity and not by any auxiliary means.

Thus, when the short roel; Chaft is rotated in the manner described above upon actuation of the lever Zi'i by the stops ide, the long shaft 2nd will also be rotated so asto actuate the supporting plate 23 of the ink spreading member 23S. As the short shaft 2te is rocked in a clockwise direction, the arm 2553 will be rocked downwardly which permits the arm 2M also to follow downwardly under the force of gravity, thereby rocking the long shaft 296i in a clockwise direction and lowering the flooding sdueegee it for the ink-spreading return stroke. Conversely, upon rotation of the short rock shaft 2&6 in a counterclockwise direction the arm Zit will raise the arno 2M and rock the long shaft 2M in a counterclockwise direction so as to raise the sdueegee 236 for the printing stroke.

The squeegee 23%? is a non-printing squeegee in that it is in elevated position over the stencil screen il during the printing stroke when the main printing squeegee Zell engages the screen as it moves toward the operator. However, during the return stroke when the main squeegee 2te has been raised off the screen by elevation of the tracks ict, the auxiliary squeegee' is low# ered into engagement'with the screen. 1t is to be noted that when the squee'gee 23d is rst lowered at the end of the printing stroke, it engages that portion of the screen which is' sup ported by the fountain plate (not shown) and consequently at this time the'squeegee 23% has not reached its lowermost position. As a 'result the roller 257i is supported away from the arm ttt a slight distance. However, as the squeegee 236 begins the return stroke and passes beyond the fountain plate to where the stencil screen is unsupported because of the lowering of the platen bed 36, the screen yields slightly so as to permit the squeegee to move down to its lowermost position and exert the desired degree of pressure on the upper surface of the screen.

As the squeegee 2% is lowered at the beginning of return, non-printing stroke, it dips down into the mass of ink material, and then as it .moves on the return stroke, it spreadsa supply of' ink before it over the stencil screen and down in the interstices thereof. Because the platen bed 3S is in lowered position below the screen on the return stroke and no sheet is below the screen to take the ink therefrom, the ink remains in and on the screen until the main squeegee 2M engages the screen during the printing stroke at which time additional ink material is again forced over the screen by the main squeegee. By flooding or predepositing the ink material in and on the stencil screen prior to the printing stroke, an adequate supply of ink material will be insured for a full clear print at every point on the sheet, the ink material being on, within the screen and at the under surface thereof for ready application to the sheet when the printing pressure is applied by the main squeegee 209. Although the 17 screen during the return stroke is not supported by the bed, the pressure of the ooding squeegee 23B thereagainst is of lesser degree than that exerted by the main squeegee 239 during the printing stroke, thus preventing permanent distortion of the stencil screen and insuring that no ink'will be squeezed down through the stencil screen so as to drip :on the upper surface of the bed 36. It has been found that ink of the normal consistency used for screen printing will not pass through a screen having interstices of average size when the ink material is ooded by the squeegee 239, nor will any droplets or concentrations of the ink form on the under surface of the screen so as to cause blotting or smudging of the sheet when printed.

Although the present invention has been illustrated in the drawings and described above with relation to several embodiments of the reciprocal squeegee mechanism and an embodiment of the clutch mechanism for stopping operation of the squeegee mechanism and other machine parts, it will be understood that changes and modications in the details of structure and operation may be resorted to without departing from the spirit and scope of the appended claims.

I claim:

1. In a screen printing machine, l a stencil screen having a supply of printing ink at one end thereof for continuous machine operation, a squeegee mechanism adapted to be reciprocated over a stencil screen for printing in one direction toward the supply of ink and for return movement in the reverse direction, said mechanism comprising a movable Vframe extending transversely of the screen, a squeegee carried by said frame in engagement with the screen during the printing stroke and out of said engagement during the return stroke, a scoop pivotally mounted on said frame out of engagement with and spaced abovesaid screen on the printing and return strokes, apivotal connection between said scoop and said frame, means on said frame for supporting said scoop in spaced relation out of contact with said screen on said printing and return strokes, said scoop being pivotal at the end of the printing stroke through the supply of printing ink at the one end of the screen for picking up a quantity of said ink and for movement into horizontal ink retaining position and said scoop being maintained in horizontal ink retaining position during said return stroke and pivotable at the end of the return stroke into inclined discharging position for depositing said quantity of in k ahead of the squeegee at the other end of the screen opposite the supply of ink for use during the printing stroke and for return to the ink supply by the squeegee, means for retaining said scoop in horizontal ink retaining and in inclined discharging positions during said strokes, respectively, means operable at the end of the printing stroke for actuating said scoop through the supplyV of ink into horizontal ink retaining position, and means operable at the end of the return stroke for actuating said scoop to discharging'position to deposit said ink at the other end ofthe screen, said pivotal connection of said' scoop with said frame being spaced a suiiicient distance from said screen and said scoop being of suchextent relative to such spacing that said scoop in horizontal ink retaining position and in discharging position during the printing and return strokes is retained out of contact with said screen.

2. `In a printing machine, a squeegee mechai8 nism adapted to be reciprocated over a stencil screen for printing in one direction and for return movement in the reverse direction, said mechanism comprising a movable frame extending transversely of the screen, a squeegee carried by said frame in engagement with the screen during the printing stroke and out of said engagement during the return stroke, a scoop pivotally mounted on said frame out of engagement with the screen on the printing and return strokes and movable from open depending position to closed, substantially horizontal position, a pivotal connection between said scoop and said frame, means on said frame for supporting said scoop in spaced relation out of contact with said screen on said printing and return strokes and said scoop having an upstanding rear Wall secured to said frame and upstanding end and front walls forming a receptacle with said rear Wall and the upper edge of the front wall comprising the scraping edge of the scoop, said scoop being movable at the end of the printing stroke from inclined discharging position to horizontal position through the mass of printing ink at the one end of the screen for picking up a quantity of said ink and being 'maintained in ink-retaining, horizontal position during said return stroke and movable at the end of the return stroke to open inclined discharging position for depositing said quantity of ink at the other end of the screen, means operable'at the end of the printing stroke for actuating said scoop from inclined discharging to horizontal position, and Y means operable at the end of the return stroke for actuating said scoop from horizontal to inclined discharging position, said scoop also being open and unobstructed at its scraping edge to permit a limited quantity of ink to dribble onto the stencil screen during said return movement and to permit visual observation by the operator as to the contents thereof during the return stroke, said pivotal connection of said scoop with said frame being spaced a suiiicient distance from said screen and said scoop being of such extent relative to such spacing that said scoop in horizontal ink retaining position and in discharging position during the printing and return strokesis retained out of contact with said screen.

3. In a screen printing machine, a squeegee mechanism adapted to be reciprocated over a stencil screen for printing in one direction and for return movement in a reverse direction, said mechanism comprising a reciprocable frame extending transversely of the screen, a squeegee carried by said frame in engagement with the screen during the printing stroke and out of said engagement during the return stroke, a scoop rockably mounted on said frame out of engagement with the screen on the printing and return strokes and rockable from open depending position to closed, substantially horizontal position, said scoop being rockable at the end of the printing stroke from depending position to horizontal position through the mass of printing ink at one end of the screen for picking up a quantity of said ink and being maintained in ink retaining horizontal position during said return stroke and rockable at the end of the return stroke to open depending position for depositing said quantity of ink at the other end of the screen, a shaft rotatably mounted in said frame, a segment secured to said shaft, a gear segment secured to said scoop and in mesh with said segment for eiecting pivotal movement of said scoop, an actuating lever secured on one end of said shaft and movable .with said frame, and stop means at each end of therscreen in the path of movement of said level and adapted to be engaged thereby as the lever; approaches the ends of the printing and return, strokes and to force movement f said actuating lever upon limitedv continued movement of the frame to the ends of the respective strokes for` effecting rocking movement of the scoop to its respective positions.

4. In a screen printing machine, a squeegee mechanism comprising a movable frame extendingV transversely of the screen and adapted to be reciprocated thereover for printing in one direction and for return movement in the reverse direction, bearing members carried by said frame, trackways adapted to be moved vertically relativeto the screen and to be engaged by said bearing; member for supporting said frame for horizontal reciprocal movement therealong, means for raising said trackways at the end of the printing stroke relative to the screen, means for lowering said trackways at the end of the return stroke realtive to the screen, and a squeegee carried by said frame and adapted to engage the screen during the printing stroke and to be elevated therefrom during the return stroke by elevation of said trackways.

5,. In a screen printing machine, a squeegee mechanism comprising a movable frame extendingV transversely of the screen and adapted to be reciprocated thereover for printing in one direction and for return movement in the reverse direction, spaced supporting members adapted for vertical reciprocal movement relative to the screen and to support said frame for horizontal reciprocal movement relative thereto, means for raising said frame supporting members at the end of the printing stroke relative to the screen, means for lowering. said members at the end of the return stroke relative to the screen, and a squeegee carried by said frame and adapted to engage the screen during the printing stroke and to be elevated therefrom during the return stroke by elevation of said supporting members.

6. A screen printing'v machine comprising a stencil screen, a squeegee mechanism adapted to be reciprocated over the screen for printing in one direction and for return movement in the reverse direction, andY a movable printing bed adapted to be moved to printing position. under the screen during the printing stroke and to be moved way from the screen during the return stroke, means for movingV said bed away from the screen at the end of the printing stroke and for returning said bed adjacent said screen at the end of the return stroke, said screen being unsupported on its under surface during the return stroke, said squeegee mechanism comprising a movable frame extending transversely ofY the screen, a squeegee carried by said frame and adapted to engage the screen during the printing stroke and to be out of said engagement during the return stroke, an ink spreading member pivotally carried by said frame and l*adapted to be pivoted into pressing engageing member, said pivotal connection beingspaeed from said screen a distance shorter than4 the height of said ink spreading memberwhereby during the return stroke said'screen is depressed by engagement with said ink spreading member and the ink is forced down into the interstices of said screen for ready application on the next printing stroke.

7. In a screen printing machine having a rotatable shaft for driving a moving part thereof and a source of power for rotating said shaft, a clutch mechanism adapted to be interposed in the driving connectionvbetween said source of power and the shaftand comprising a sleeve adapted to be mounted on said shaft for rotative movement independently thereof, a'driver member secured on said sleeve and in constant operating engagement with the driving connections to said source of power, a flat, annular cam plate secured on said sleeve and having a; single recess in its outer periphery, an arm adapted to be secured on said shaft for rotation therewith, a rocking lever pivotally supported on said` arm and having a projecting portion engageable with said cam plate around its outer periphery and in said recess and a lug portion at its outer periphery, resilient means for urging said rocking lever into recess engaging position, a movable stop member adapted to be movedfrom normal retractedv position into the path of movement of said lug portion for engagement therewith and for stopping rotation of said arm and shaft and for rocking said lever to withdraw said projecting portion from said recess.

8. In a screen printing machine havingal rotatable shaft for driving a moving part thereof and a-source of power for rotating said shaft,y

a clutch mechanism adapted to be interposed in the riving connection between said source of power and the shaft and comprising a sleeve adapted to be mounted on said shaft for rotative movement independently thereof,l a driver mem,- ber secured on said sleeve and in constant operating engagement with the driving connections to said source of power, a cam flat, annular plate secured on said sleeve and having a single recess in its.Y outer periphery, an arm adapted to be secured on said shaft for rotation therewith,v a rocking lever pivotallyv supportedon said arm and having a projecting portion engageable with said cam plate around its outer periphery and in said recess and a lug portion at its outer periphery, resilient means for urging said rocking lever into recess engagingposition, a movable stop member adapted to be moved fromnormal retracted position into thel pathl of. moven'renty 0f said lug portion for engagement therewith; and

for stopping rotation of said arm and shaft and-y for rocking said lever to withdraw said project,-

ing portion from said recess, and means forlocking said rockinglever in declutched positions.

9,. In a screen printing machine having a rotatable shaft for driving a moving part thereof and a source of power for, rotating said shaft,v a clutch mechanism adapted to be interposed in the driving connection between said sourcevof power and the shaft and comprising av sleeve` adapted to be mounted on said shaft for rotative movement independently thereof, a driver member secured on said sleeve and in constant operating engagement with the driving conf-motions to said source of power, a cam plate,-securedyon said sleeve andv having a single. recess. in its outer periphery,A an arm adapted to be secured on said shaft for rotation therewith, a rock-- ing lever pivotally supported on said arm and having a projecting portion engageable with said cam plate in said recess and a lug portion at its outer periphery, resilient means for urging said rocking lever into recess engaging position, a movable stop member adapted to be moved from normal retracted position into the path of movement of said lug portion for engagement therewith and for stopping rotation of said arm and shaft and for rocking said lever to withdraw said projecting portion from said recess, and means for locking said rocking lever in declutched position, said locking means comprising a locking plate secured on said arm and another movable stop element adapted to engage said locking plate to prevent rotation thereof, and said locking plate being adjustable relative to said arm'for adjusting the point of engagement between said plate and said stop element.

v`10. In a screen printing machine having a rotatable shaft for driving a moving part thereof and a source of power vfor rotating said shaft, a clutch mechanism adapted to be interposed in the driving connection between said source of power and the shaft and comprising a sleeve adapted to be mounted on said shaft for rotative movement independently thereof, a driver member secured on said sleeve and in constant operating engagement with the driving connections to said source of power, a cam plate secured on said sleeve and having a single recess in its outer periphery, a stationary member disposed adjacent said sleeve and having a recess in its outer periphery, an arm adapted to be secured on said shaft for rotation therewith, a rocking lever pivotally supported on said arm and having a projecting portion at one end engageable in the recess of the cam plate and a projecting portion at the other end engageable in the recess of the stationary member, said rocking lever also having a lug portion engageable with a stop member, resilient means for urging said rocking lever into driving engagement with said cam plate, a stop memberl adapted to be moved from normal retracted position into the path of movement of said lug portion for engagement therewith and for stopping rotation of said arm and shaft for rocking said rocking lever to declutched position and moving said second projecting portion of said lever into the recess of said stationary member.

11. In a screen printing machine having a rotatable shaft for driving a moving part thereof and a source of power for rotating said shaft, a clutch mechanism adapted to be interposed in the driving connection between said source of power and the shaft and comprising a sleeve adapted to be mounted on said shaft for rotative movement independently thereof, a driver member secured on said sleeve and in constant operating engagement with the driving connections to said source of power, a cam plate secured on said sleeve and having a single recess in its outer periphery, an arm adapted to be secured on said shaft for rotation therewith, a rocking lever pivotally supported on said arm and having a projecting portion engageable with said cam plate in said recess and a lug portion at its outer periphery, resilientl means for urging said rocking lever into recess engaging position, a movable stop member adapted to be moved from normal retracted position into the path of movement of said lug portion for engagement therewith and for stopping rotation of said arm and shaft and for rocking said lever to withdraw said projecting portion from said recess,

and means for maintaining said lever in declutched position and preventing rotation of said shaft in either direction comprising a stationary member disposed adjacent said sleeve and having a recess in its outer periphery, a second projecting portion on said rocking lever engageable in the recess of said stationary plate upon declutching rocking movement of said lever, a locking plate secured on said arm and another movable stop element adapted to be moved into locking engagement with said locking plate simultaneously with movement of said first stop means.

12. In a printing mechanism having a rotatable shaft for driving a moving part thereof and a source of power for rotating said shaft, a clutch mechanism adapted to be interposed in the driving connection between the source of power and the shaft and comprising a sleeve adapted to be mounted on said shaft for rotative movement independently thereof, a driver member secured on said sleeve and adapted to be in constant operating engagement with the driving connections to said source of power, a cam plate secured on said sleeve and having a recess at one predetermined point in its outer periphery, an arm adapted to be secured on said shaft for rotation therewith, a rocking lever pivotally supported on said arm and having a projecting portion adapted to be interengaged with said single recess on said cam plate and also having a second engaging element adapted to engage a stop means at a constant point in the cycle of operation, means for urging said rocking lever into cam plate engaging position, and a movable stop means mounted on a non-rotatable support and adapted to be movedinto the path of movement of said second engaging element at any point during the cycle of operation for engagement thereafter with said second engaging element upon continued rotation of said clutch mechanism, said engagement between said stop means and said second engaging element stopping further rotation of said arm and shaft and causing said lever to be rocked out of engagement with said cam plate.

13. In a screen printing machine having a rotatable shaft for driving a moving part thereof and a source of power for rotating the shaft, a clutch mechanism adapted to be interposed in the driving connection between said source of power and the shaft and comprising a driver member mounted on said shaft for rotative movement independently thereof and adapted to be in constant operating engagement with the driving connections to said source of power, a flat, annular cam plate secured to said driver member and having a recess in its outer periphery, an arm adapted to be secured on said shaft for rotation therewith, a rocking lever pivotally supported on said arm and having a projecting roller engageable around the outer periphery of said cam plate and in said cam plate recess and a lug portion at its outer periphery, resilient means for urging said rocking lever and roller into recess engaging position, and a movable stop member adapted to be moved into the path of movement of said lug portion for engagement therewith and for stopping rotation of said arm and shaft and for rocking said lever to withdraw the roller from said recess, said roller upon release of said rocking lever toward cam plate engaging position being adapted to rollably engage the outer periphery of the cam plate upon rotation thereof and to thereafter enter the recess therein upon registry therewith.

madam;

V1315A screen printing machine comprising a stencil screen aprinting bedadapted to be moved to and from printing position under the screen, a squeegee adapted to be reciprocated over said screen, means for moving said squeegee over said screen to operative position and return, means for moving said bed from operative to open inoperative position and return, a rotatable shaft in driving connection with said squeegee and said bed moving means, a main drive shaft for driving said machine, other movable operating parts operablyconnected with and driven by said main drive shaft, and a clutch mechanism between said main drive shaft and said rotatable shaft for completing or breaking the driving connection to said rotatable shaft for starting or stopping operation of said squeegee at the end of its stroke and said'bed in open inoperative position Without affecting operation of said other moving parts of the machine, said clutch mechanism comprising a clutch plate mounted on said main drive shaft for rotation relative thereto and being drivingly connected to said rotatable shaft and having a single clutching element rotatable therewith, a

pivoted lever secured adjacent said clutch plate to said main drive shaft for rotation therewith and for pivotal movement relative thereto and engageable with the clutching element of said clutch plate for completing the driving connection from said main drive shaft to said rotatable shaft, and

amovablestop memberadapted .to be mov'edfrom normall retracted position into .the'path of movement of said lever for engagement therewith at any time in the cycle of rotation of said lever and for rocking the lever out of clutched engagement with said clutch plate ata constant poi-nt in the cycle of rotation ofsaid clutch mechanism for stepping operation of said squeegee and said bed at said constant point.

JESS D, KLOPFENSTE-IN.

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

UNITED STATES PATENTS Number Name Date 356,847 McKinney Feb. 1, 1887 626,113 Vaughnk May 30, 1899 1,459,851 Morse June 26, 1923 1,832,828 Borregard Nov. 17, 1931 1,840,073 Williams Jan. 5, 1932 1,922,710 Owens Aug. 15, 1933 1,966,416 Parmele et al July 10, 1934 2,039,909 Kem et a1. May 5, 1936. 2,196,678 Klopfenstein Apr. 9,1940

FOREIGN PATENTS Number Country Date 603,328 Germany Aug. 8, 1931

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