US2936705A

US2936705A - Silk screen printing press

Info

Publication number: US2936705A
Application number: US508130A
Authority: US
Inventors: Gardner V Hall
Original assignee: PACE Manufacturing Co
Current assignee: PACE Manufacturing Co
Priority date: 1955-05-13
Filing date: 1955-05-13
Publication date: 1960-05-17
Anticipated expiration: 1977-05-17

Description

May 17, 1960 ca. v. HALL SILK SCREEN PRINTING PRESS 4 Sheets-Sheet 1 Filed May 13, 1955 INVENTOR. GAAD/YE/P l HALL BY X/SiMaZ ,4 TTOR/YEK May 17, 1960 Filed May 13, 1955,

G. v. HALL 2,936,705

SILK SCREEN PRINTING PRESS 4 Sheets-$heet 2 J6 d5 /Z7 a2 fdg 49 fee 30 62 '5 f I I: v 0? W 1 E 59 59 6/ 07 72 46 46 45 9e 4 9 I 42 I7 I Z5 28 42 i l I 9 A V I o V l8 35 32 26 ""fl'h 5/ i INVENTOR.

Z GARDNER V. HALL G. v. HALL 2,936,705

SILK SCREEN PRINTING PRESS May 17, 1960 Filed May 13, 1955 4 Sheets-Sheet 3 99 J uvmvrox. bi [fl/ .0 n. U 93 GARDNER l HALL BY :saznkw-(Z.

K I W n z ATTORNEY.

SILK SCREEN PRINTING PRESS Gardner V. Hall, Des Moines, Iowafassigrior to Pace Mfg. Co., Des Moines, Iowa, a corporation of Iowa Application May 13, 1955, Serial No. 508,130

3 Claims. (Cl. 101- 123) This invention relates generally to printing presses and more particularly to a silk screen printing press.

An object of this invention is to provide an improved silk screen printing press.

A further object of this invention is to provide a silk screen printing press which :can be used either for a regular printing operation or'a' flood printing operation.

Another object of this invention is to provide a silk plate 29 extended transversely of the main frame 21 screen printing presswhich includes a screen mounted for up and down movement relative'to the material to be printed upon and a squeegee member movable across the screen in a timed relation with the up and down movement of the screen.

Still another object of this inventionis to provide a Fig. 1 is a side elevational view of the printing press of this invention showing the chase therefor in a raised position, with some parts broken away'and other parts shown in section for the purpose of clarity;

Fig. 2 is an enlarged diagrammatic view of a portion of the printing press of this invention, showing a moved position of the squeegee supporting frame at the rear end of the stroke therefor;

Fig. 3 is a top plan view of the printing press of this invention in the position shown in Fig. 1;

Fig. 4 is an enlarged side elevational view of a portion of the printing press. of this invention, showing a moved position .of the squeegee supporting frame. at .the front end of the stroke therefor during a. flood'printing operation; U 7 1 Fig. 5 is an enlarged side elevational view illustrated similarly to Fig. 4 and showing the position .ofgthe squeegee supporting frame during a regular printing operation; g V

Fig. 6 is a diagrammatic view showing the path of travel of the squeegee in a regular printing operation;

Fig 7 is a diagrammatic view showing the path of travel of the squeegee 'in a flood printing operation;

Fig. 8 is a bottom view of the bed frame inthe printing press of this invention showing the centering devices carried thereby and the depending material supporting structure engaged by the centering devices;

Fig. 9 is an "enlarged top plan view of one of the cent ering devices shown in Fig. 8, with some "parts broken 2,936,705 Patented May 17, 1960 ice away and other parts shown in section for the purpose of clarity;

Fig. 10 is an enlarged top plan view, illustrated similarly to Fig. 9 of another one of the centering devices shown in Fig. 8;

Fig. 11 is an end view of a centering device; and

Fig. 12 is a fragmentary sectional view looking along the line 12'12 in Fig. l.

' With reference to the drawing, the printing press of this invention, indicated generally at 20, is illustrated in Fig. 1 as including a main frame 21 for supporting an inclined bed frame 22 for holding a sheet material which is to be printed. For convenience of description, the end 23 of the main frame 21 will be referred to hereinafter as the front end of the machine 20 and the opposite end 24 will be referred to as the rear end of the machine. Pivotally supported on a shaft 26, arranged transversely of the bed frame 22, is a screen supporting frame or chase 27 which extends forwardly from the shaft 26. A squeegee supporting frame 30 is movably mounted on the chase 27 for back and forth movement thereon. The driving mechanism A motor 28 (Figs. land 3), carried on a supporting below the bed frame 22, drives a shaft 16 for a gear reduction unit 17. A second shaft 18 for the unit '17 drives a sprocket Wheel '31 secured to the shaft 26 for rotation in a counter-clockwise direction as viewed in Fig. 1. A cam 32, secured to the shaft 26, engages a follower roller 33 carried on one end of a link member 34. The opposite end of the link 34 is pivoted at 37 to an upright bracket 38 secured to themotor supporting plate 29. A link '39, rigidly connected to the link'34 is pivotally connected to'one end of a link 41, the op posite end of which is pivotally connected at 36 to the chase 27. Y

It is seen, therefore, that on rotation of the cam 32, with the, enlarged side 35 thereof in contact with the roller 33, the chase 27 is maintained in a raised position by the

links

34, 39 and 41. A counterweight 55, secured to and extended rearwardly from the chase 27 and positioned on the opposite side of the shaft 26 facilitates the maintaining of the chase 27 in araised position.

The weight of the chase 27 provides for a following movement of the roller 33 along the small side 40 of the, cam 32 in the lowered position of the chase 27. In response to rotation of the follower 33 on inclined portions 45 of the cam 32, the chase 27 is moved upwardly and downwardly during predetermined portions of the rotation of the cam 32. By virtue of the shape of the cam 32, with the substantially

constantdiameter side portions

35 and 40, and the relatively short inclined pordowndirections about the shaft 26 relatively quickly and is maintained in an up or down position for a predetermined time period. In a down position, the chase 27 is parallel to and adjacent the bed frame 22 for print:

22 and a next piece of stock material to a predetermined angular relation with the cam 32, are

a pair of crank arms 42, arranged outwardly of the bed frame22. A pair of links-43, corresponding to the crank arms 42, are pivotally connected to and extend'between the crank arms 42 and the squeegee frame 30 to provide for driving of the frame 30 in directions longitudinally of the chase.27, in responseto a rotation of theorem:

arms42. j r

It is seen, therefore, that upon rotation of the shaft 26, the chase 27 is rocked up and down about the-shaft 26 and the squeegee frame 30 is concurrently moved back and forth along the chase 27. By virtue of the predetermined angular relation of the crank arms 42 and the cam 32, the chase 27 is in a down position during travel of the squeegee frame 30 toward the front end 23 of the machine 20. During a return movement of the frame 30 toward the rear end 24 of the machine 20, the chase 27 is in an up position spaced above the bed frame By virture of the downward movement of the chase 27 at a time correspondingf to the reversal of the direction of travel of the squeegee frame 30, the frame 30 is momentarily maintained in a substantially stopped position on the chase 27. In other words the links 43, which move the frame 30 on the chase 27, are travelling upwardly from a dead center relation with the cranks 42 at a time when the chase 27 is moving downwardly. As a result, the downward rotational movement of the chase 27 compensates for the upward rotational movement of the links 43 to provide for a stopped position. of the frame 30 on the chase 27 during the time the chase 27 is moving downwardly.

The squeegee supporting frame As best appears in Figs. 1 and 3 the squeegee supporting frame 30 includes a pair of rectangular end plates chase 27 and the screen 67 on swinging movement of the support units 53 about the pivots 57 therefor. Stated otherwise, on downward swinging movement of the units 53, as viewed in Fig. 1, the plate 63 is moved downwardly toward the screen 67. As best appears in Figs. 4 and 5, in the engaged positions of the units 53 with the stop pins 61, the squeegee blade 66 is spaced above the screen 67.

For maintaining the plate 63 in a downwardly moved position corresponding to a position of the squeegee 66 in wiping engagement with the screen 67, a hook 68 (Figs. 2, 4 and 5), provided on one of the end plates 46 is engaged with an inwardly directed pin 69 on one 46 connected together by a pair of spacer bars 48 exeach end plate 46 are positioned on opposite sides of the top flange 52 for the corresponding frame member 49 to provide for a longitudinal rolling movement of the squeegee frame on the chase 27.

A supporting unit 53 (Figs. 1, 4 and 5), consisting of a pair of pivotally connected

scissor members

54 and 56, is mounted on the outer side of each end plate 46. The

scissor members

54 and 56 in a unit 53 are pivotally connected by a transverse pivot 57 extended through the adjacent end plate 46 for pivotally supporting the unit 53. Each member 54 is of a reduced thickness adjacent the pivot 57 (Fig. 12) to thus form a stop 58 which is engaged with the. cooperating member 56 to limit pivotal movement of the

members

54 and 56 in directions toward each other. A spring 59 extended between the member 54 in a unit 53 and a transversely extended stop pin 61 on the adjacent end plate 46 biases the unit 53 into engagement with the stop pin 61. The spring 59 also maintains the

members

54 and 56 in a unit 53 in positions in which the stop 5.8 engages the member 56.

A spring 62 extended between the free ends of the

members

54 and 56, in a supporting unit, 53, further biases the

scissor members

54 and 56 toward the closed position in which the member 56 engages the stop 58. As will more clearly appear herein, the

members

54 and 56 are maintained in a closed position during operation of the machine 20. However, for safety. purposes, the

members

54 and 56 are movable in directions away from each other against the action of the

springs

59 and 62 when it becomes necessary. For a purpose to appear later, a roller 65 is carried on an inwardly extended shaft 70 on the free end of each of the members 54.

A'supporting plate 63 (Figs. 1 and 3), secured to and extended between the free ends of the scissor members 56 adjustably supports a wooden holder 64 for a depending squeegee blade 66 formed of a flexible material such as rubber or the like. In one position of the plate 63, the holder 64 is vertically adjusted on the plate 63 to provide for a desired wiping engagement of the squeegee 66 with the silk screen 67 carried by the chase 27 at a position below the squeegee 66.

It is apparent that the plate 63 and the squeegee 66 carried thereby are vertically movable relative to the of the scissor members 56. The hook 68 is positioned between the plate 46 and the member 56 and is secured to a pivot 71 journaled in and extended through the end plate 46. An L-shape lever 72 secured to the pivot 71 at a position inwardly of the plate 46 acts as a counterweight biasing the hook 68 toward a position engaged with the pin 69. The curved top end 60 of the hook 68 provides for a forward movement of the book 68 on the engagement thereof by the pin 69, as the pin 69 moves downwardly. The hook 68 is thus movable forwardly and then rearwardly to an engaged position on the pin 69, on downward movement of the pin 69. On rotation of the lever 72 in a clockwise direction as viewed in Fig. 2, the hook" 68 is movable out of an engaged position on the pin 69.

A roller 76 is provided on the free end 77 of the lever 72 for a purpose to appear later. A spring 78, loosely extended between an endplate 46 and the lever 72 acts to return the lever 72 to a position resting on one of the spacer bars 48.

A dog 73 (Figs. 4 and 5), pivoted at 75 to the lower end of the hook 68 is movable into engagement with the lower end 74 of the hook 68 on rearward movement of the dog 73 relative to the hook 68. On further rearward movement of the dog 73, the hook 68 is moved forwardly off the pin 69. By virtue of the location of the pivot 75 adjacent the forward side of the hook 68, the dog 73'is freely movable in a forward direction without affecting the position of the hook 68.

vIt is apparent, that. on movement of the hook 68 01f the pin 69, the plate 63 is moved by the springs 59 to a stop. position corresponding to the engaged position of the units 53 with the stop pins 61.

It. is seen, therefore, that the squeegee blade 66 is movable both longitudinally of the screen 67 and up and. down relative to the screen 67.

An upper position of the squeegee 66, corresponding to the. engagement of the supporting units 53 with the stop pins 61 on the end plates 46, provides for a location of thesqueegee 66 spaced above the screen 67 The lower position of the squeegee 66 in engagement with the screen 67 corresponds to a downwardly moved position of the units 53 which position is maintained by the engagement of the hook 68 with the pin 69. Upward rotation of the lever 72 or rearward movement of the dog 73 operates to disengage the hook 68 from the pin Mechanism for moving the squeegee blade up and down relative to the silk screen During the operation of the machine 20 the squeegee blade 66 is moved up and down relative to the silk screen 67 at. predetermined intervals during the travelof the squeegee 66 back and forth along the chase 27. For convenience. in describing the position of the blade 66 relative to the. chase 27, the position of the squeegee 66 at the rear end of the screen 67 will be referred to as constituting, the rear end of the stroke of the squeegee 66.. The. position of the squeegee 66 adjacent the front end 23 of the machine 20 will be referred to as the front end of the stroke of the squeeege 66.

For moving the squeegee 66 downwardly to a. position in engagement with the screen 67 at the rear end of, the stroke, downwardly and rearwardly inclined earns 81 are secured to and extended downwardly from the chase side frame members -49 at positions spaced forwardly of the chase rear end frame member 80 (Figs. 1 and 3). The earns 81 are engaged by the rollers 65 on the support units 53. On rearward movement of the rollers 65 into contact with the cams 81, the rollers 65 are moved downwardly, by virtue of the downward inclination of the cams 81, to in turn move the units 53 and the squeegee 66 downwardly to a position in which the hook 68 is engaged on the pin 69. i

- An outwardly projected plate 82 (-Figs. 1, 4 and 5) arranged on a chase side frame member 49, intermediate the ends thereof, engages the dog 73 prior to the movement of the squeegee 66 to the forward end of the stroke therefor. On engaging the plate 82, the dog 73 ads to disengage the hook 68 from the pin 69. ln rresponseto such disengagement, the squeegee 66 is quickly moved upwardly by the springs 59 out of contact with the screen 67.

Pivotally supported at 84 (Figs. 1, 4 and 5) on a block 87 secured to the side frame member 49 at .a position forwardly of. the plate 82, is a cam 83 having an inclined face 85. A handle 86 secured to the cam 83 facilitates the manual movement of the cam 83 between the generally horizontal position A (Fig. 5) and the generally vertical position B (Fig. 4). A stop pin 88 on the block 87 engages the cam 83' to define the positions A and B.

In the position A, the cam 83 is in a clearance relation with all of the parts of the squeegee frame-30 so as not to affect the movement thereof.

In the position B the inclined face 85 of the cam 83 is engaged by one of the rollers 65 during the forward travel of the squeegee frame 30. As a result of the downward and forwardinclination of the face 85, the roller 65 moves downwardly and forwardly along the face 85 to in turn move the supporting units 53 downwardly to a position in which the pin 59 is engaged by the hook 63 on an end plate 46. The hook 68 maintains the units 53 and the. squeegee 66 in a down position during rearward travel of the squeegee 66.

A11 L-Shape member 91 (Figs. 1 and 2), secured to one of the chase side frame members 49 at a position between the chase end frame member 80 and the crank arm 42, extends forwardly therefrom and has an 'upwardly and rearwardly inclined cam face 92 at its forward end; During rearward travel of the squeegee 66,

the roller 76' on the hook operating lever 72 travels upwardly on the cam face 92 prior tothe above described engagement of the rollers 65 with the cams 81.

I -In response to the upward travel of the roller 76 on the cam face 92, the lever 72 is rotated ina clockwise in an up position, the travel of the roller 76 on the.

.cam face 92 is without any effect on the position of the squeegee 66.

Immediately following the upward travel of the roller 76, the roller 65 engages the cam 81 to provide for movement of the squeegee 66 to the down position therefor.

"The operation of the machine for regular printing For a regular printing operation using an opaque ink or paint, the squeegee 66 moves rearwardly'ina spaced relation with the screen 67 (Fig. 6). When thesqueegee 66 reaches a position above an accumulated reservoir of 67, the squeegee 66 is moved downwardly into thepaint reservoir 93 for forward travel in engagement with the screen 67 so as to force the paint through the screen 67. A masking or the like on the screen 67 provides for the printing of the paint, forced through the screen 67, in a predetermined pattern on the sheet material (not shown) which is releasably held on the bed frame 22. At the forward end of its stroke, the squeegee 66 is moved upwardly for rearward travel above the screen 67. To set the machine 20 for a regular printing opera tion, the lever 86, on the cam 83 is moved downwardly so that the cam 83 is in its position shown at A.

Assume that the chase 27 is in the raised position therefor illustrated in Figs. 1 and 3, in which case the squeegee supporting frame 30 is moving rearwardly thereon, and the squeegee 66 is in the upper position shown in Fig. 1. Immediately prior to reaching the rear end of the stroke for the squeegee 66, the roller 76 on the hook operating lever 72 rides upwardly on the cam face 92 on the member 91 to swing the hook 68 forwardly about the pivot 71 therefor. However, since the squeegee 66 is already in'its up position, corresponding to the position of the pin 69 above the hook 68, such.

to the fact that the angular movement of the crank arms 42 to reciprocate the squeegee frame 30 is negatived by the downward movement of the chase 27. i

The cams 81 act to feed or direct the rollers 65 to positions between the outwardly projected flanges 94 of channel shaped track members 96 carried on and arranged outwardly of the bed frame 22, on downward movement of the chase 27. Such downward movement 1 of the rollers 65 provides for a corresponding downward movement of the support units 53 and the squeegee 66. As a result, the pin 69 on one of the units 53 ,is moved downwardly to a position in which the hook 68 on the adjacent end plate 46 is engaged therewithto maintain the squeegee 66 in a down position in engagement with the screen 67. v

The rollers 65 then travel forwardly, riding on the underside of the top track flanges 94. As best appears in Fig. 5, in this position of the rollers 65, the plate 63 is moving along the top side of the chase 27 and cooperates with the rollers 65 to maintain the chase 27 in a down position against the bed frame 22. As a result, a stationary position of the screen 67 on the chase 27 is assured during the forward printing stroke of the squeegee 66 to insure a uniform printing operation. In the event the operators hand should enter between the chase 27 and the bed frame 22, the chase 27 is manually movable upwardly against the pressure of the

springs

59 and 62 to free the operators hand.

The rollers 65 ride on the flanges 94 until they reach the forward ends 97 of the tracks 96 at which time the rollers 65 are free to move upwardly. Concurrently with the travel of the rollers 65 off the flanges 94, the dog 73 is moved into engagement with the outwardly projecting plate 82 on the chase side frame member 49. By virtue of this engagement and the forward travel of the frame 30, the dog 73 is moved rearwardly relative. to the book 68 to swing the hook 68 off the pin 69. The springs 59 then operate to pull the units 53 upwardly to thus move the squeegee 66 upwardly off the screen 67 at a position of the screen 67 corresponding substantially,

to the rear side of the accumulated paint reservoir 99 at or paint 93 (Fig; 6 at the rear end of the screen, 7 the front end of the screen 67.?

The extent of forward movement of the squeegee 66 prior to such upward movement thereof is adjustable on manipulation of a slide plate 101 (Fig. 1) on one of the top track flanges 94. The plate 101 1s sl1dably sup ported on the front end of the track 26 and 1s maintained in an adjusted position by the frictional contact of the plate 101 with a retaining strap 102 carrier by the track 96 and engaged with the top side of the plate 101. L The upwardly curved free end 103 of the plate 101 facilitates manual adjustment of the plate 101 and travel of a roller 65 off the plate 101.

The slide plate 101 constitutes an adjustable extension of the track flange 94. Until a roller 65 travels off the free end 103 of the plate 101, the squeegee 66 is restrained against any upward movement. Thus, the slide plate 101 is adjusted to regulate the extent of movement of the squeegee 66 into the accumulated paint reservon 99 prior to a raising of the squeegee 66 off of the screen 67 The frame 30 then moves forwardly with the squeegee 66 spaced above the screen 67 and the paint reservoir 99. Concurrently with this upward and forward movement of the squeegee 66, the chase 27 is moved upwardly by the action of the cam 3-2 on the follower 33. The frame 30' then moves rearwardly on the case 27 in a position spaced above the screen 67 and with the chase 27 in a raised position.

It can be seen, therefore, thatduring a regular printing operation, the squeegee 66 operates to force paint through the screen 67 onto the stock material (not shown) onthe bed frame 22 during the forward stroke of the squeegee 66. During rearward travel of the squeegee 66, in a spaced relation with the screen 67,- some paint may drip from the squeegee 66 onto the screen 67. However, since opaque paint is being used, any unevenness of paint on the screen 67 caused by this dripping will not affect the appearance of the printed material.

The operation f the machine for a flood printin operation A flood printing operation (Fig. 7) is normally used when a large area is being printed so that large amounts of paint must be forced through the screen 67, or a transparent or reflective type paint is used which must be uniformly applied. 'For such a printing operation, paint is distributed over the screen 67 during rearward travel of the squeegee 66. In all other respects, a flood operation is identical to the regular printing operation hereinbefore described.

' To set the machine 20 for a flood printing operation, the lever 86 on the cam 83 is moved upwardly to move the cam 83 to its position B.

Assume that the chase 27 is in the down position. illustrated in Fig. 4 and that the squeegee 66 is moving for-. Wardly. Further assume that the dog 73 has engaged the plate 82 and the rollers 65 have trtveled off the track flanges 94. The squeegee 66 has therefore moved upwardl'y 0d the screen 67 and forwardly over the paint reservoir 99 concurrently with the raising of the chase 27.

One of the rollers 65 then moves along the downwardly.

and forwardly inclined face 85 on the cam 33 to thus move the units 53 downwardly to a position in which the hook 68 engages the pin 69. The squeegee 66 is thus lowered into the paint reservoir 99 concurrently with the beginning of the rearward stroke of the squeegee 66.

The squeegee 66 thus acts to evenly spread or distribute paint from the reservoir 99 over the screen 67 during rearward travel of the squeegee 66. By virtue of the flexibility of the screen 67,. none of this paintis forced through the screen 67 by the squeegee 66. During printing, the screen 67 is moved or flexed downwardly by the squeegee 66 into contact with the rigidly supported stock material (not shown) on the bed frame 22- to force paint through the screen 67 as the squeegee 66 moves along:

8 material to serve as a backing for the screen 67eliminate's any forcing of paint through the screen 67 during rearward travel of the squeegee 66.

Immediately prior to engagement of the rollers 65 with the cams 81 at the rear end of the stroke of the squeegee 66, theroller 76 on the hook operating lever 72 rides upwardly onthe cam face 92 on the member 91. The hook 68 is thus rotated forwardly to a position off the pin 69 to thus cause raising movement of the squeegee 66 at a position corresponding to the front side of the paint reservoir 93 at the rear end of the screen 67.

The squeegee 66 moves rearwardly above the paint reservoir 93 until it moves downwardly into the paint reservoir 93 in response to a downward travel of the rollers 65 on the earns 81. The chase 27 moves downwardly to feed the rollers 65 into the spaces between the track flanges 94 for forward travel of the squeegee 66 on the'screen 67 as above described in connection with the regular printing operation.

It is seen, therefore, that in a flooding operation (Fig. 7) the squeegee 66 travels-back and forth on the chase 27 in contact with the screen 67 between the paint reservoirs 93 and 99. At the end of each stroke, the squeegee 66 jumps over a paint reservoir for travel in the opposite the screen 67. The absence-ofv any such rigidly supported 715 direction to spread such paint. relatively large amounts of printed is thus formed.

The centering devices A supporting structure 111 (Fig. 8) is mounted on the bed frame 22 for holding the sheet material to be printed upon in a. fixed position. Retractible stop means (not shown) on the top side of the structure 111 provides for the positioning of sheet material in a predetermined location on the structure 111 for a printing operation.

a A depending rectangular frame 112, illustrated diagrammatically in dotted lines in Fig. 8, secured to the A uniform application of paint to the material being bottom side 113 of the structure 111 is spaced inwardly.

of the bed frame 22. The frame 112 is adjustably movable longitudinally and transversely of the bed frame 22 to provide for a centering of the .sheet material on the structure 111 relative to the silk screen 67. Such centering provides for a printing on a predetermined portion of the sheet material.

For adjusting the position of the frame 112, three manually adjustable centering devices 114 (Figs. 8 and 9) are secured to and extended inwardly of the bed frame 22. Each device 114 is arranged substantially opposite a corresponding non-adjustable centering device 116 (Figs. 8 and 10) also carried on and extended inwardly of the bed frame 22.

As best appears in Figs. 9 and 11 each device 114 includes a flatrectangular mounting plate 117 secured to the bed frame 22. A tubular cylinder member 118, of a rectangular shape in transverse section, is secured at its inner end 119 to the plate 117. Received within the opposite or outer end 121 of. the cylinder 118 is a piston member 1220f a rectangular shape in transverse section. The piston 122 is of a size to provide for the free move ment thereof longitudinally of the cylinder 118.

A pair of short screws 123, removably mounted on transversely opposite sides of the piston 122, adjacent the inner end 124 thereof, are received in slots 126, only one of which is shown, extended longitudinally of the cylinder 118. Engagement of the screws 123 with the cylinder 118 at the ends of the slots 126 limits the longitudinal movement of the piston 122 within the cylinder 118.

An elongated screw 127, received within and extended longitudinally ofthe cylinder 118, is threadably received in a tapped opening 128 in the inner end 124 of the piston 122. A tapered. head 129 on the screw 127 is received within. a similarly tapered opening 131 in the mounting plate 117 and is positioned'against the bed frame 22.

It can thus be seen that on rotation of the screw 127 the piston: 122 is: movable: longitudinally of the cylinder 118'.

For rotating the screw 127, a socket 132-for receiving a wrench. is formed in the screw head 129 at a position aligned with an opening (not shown) in the bed frame 22. To rotate the screw 127, the wrench is extended through the bed frame opening and positioned in the socket 132.

A roller 134 is rotatably mounted on a bolt 136 extended transversely through the piston 122 adjacent the outer end 137 thereof. projects outwardly of the piston end 137. a

A centering device 116 (Figs. 8 and is identical with a centering device 114 except for the substitution of a compression spring 138 in a device 116 for the screw 127 in a device 114. A spring 138, in a device 116, is positioned within the cylinder 118 and extends between the plate 117 and the inner end of an opening 141 in the piston 122. Like numerals are used, therefore, on the devices 116 to designate like parts on the devices 114.

In use, a device 114 is assembled on the bed frame 122 opposite a device 116, with the rollers 134 for such devices in engagement with the depending frame 112. Also, the springs 138 for the devices 116 are initially compressed sufficiently to provide for substantial expansion of the springs 138.

To adjust the position of the structure 111, the screws 127 for the devices 114 are selectively rotated to provide for a movement of the structure 111 to a desired position. It is apparent that on rotation of a screw 127 in a direction to move the piston 122 thereon outwardly of the corresponding cylinder 118 the frame 112 is moved away from the piston 122 and against the action of the spring 138 in the opposite device 116. On rotation of a screw 127 in the opposite direction, the frame 112 is moved in an opposite direction by a spring 138. To turn or rotate the frame 112 relative to the bed frame 22, the screws 127 for adjacent ones of the devices 114 are rotated in opposite directions.

The provision of the rollers 134 on the

devices

114 and 116 reduces friction between the

devices

114 and 116 and the frame 112 and thus facilitates adjustable movement of the frame 112 in contact with the rollers 134.

From the above description, it is seen that this invention provides an improved silk screen printing press 20 which is useable both for a regular printing operation and a flood printing operation. By moving the cam 83 between the positions A and B therefor, the press 20 is readily changed from one such operation to the other. Further, by virtue of the up and down movement of the chase 27 in a timed relation with the movement of the squeegee 66 on the screen 67, a press operator can readily place material to be printed upon the bed frame 22 and remove the previously printed material.

Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited since changes can be made therein which are within the full intended scope of this invention as defined by the appended claims.

I claim: 1. A silk screen printing press comprising a main frame, a bed frame for holding material to be printed upon, guide track means mounted on said bed frame, a screen supporting frame movably mounted on said main frame for up and down movement toward and away from said bed frame, a screen mounted on said supporting frame, guide flange means mounted on said bed frame, a squeegee adapted for co-action with said screen, and means mounting said squeegee for reciprocal movement across and parallel to the surface of said bed frame including a pair of units secured at each end of said squeegee mounting means, each unit comprising a plate reciprocally movable on one of said guide flanges, a pair of upper and lower scissors members pivotally connected together at one ends thereof to said plate, said As shown in Fig. 9 the roller 134 lower member for reciproml movement along said 'guide track means, first spring means connected between said scissors members whereby to maintain them in a closed position relative each other and pivotally movable'about said roller as. a unit, second spring means connected between said plate and said secondv member whereby to pivot said members as a unitand thus said squeegee downwardly toward the surface of said bed frame upon upper member having a pin secured thereto, the free upward movement of. said plate relative to said bed frame, and hook means connected to said plate and engageable with said pin whereby to pivot said members as a unit and thus said squeegee upwardly and away from the surface of said bed frame upon downward movement of said end plate relative to said bed frame.

2. A silk screen printing press comprising a main frame, a bed frame for holding material to be printed upon, guide track means mounted on said bed frame, a screen supporting frame movably mounted on said main frame for up and down movement toward and away from said bed frame, a screen mounted on said supporting frame, guide flange means mounted on said bed frame, a squeegee adapted for co-action with said screen, and means mounting said squeegee for reciprocal movement across and parallel to the surface of said bed frame including a pair of units secured at each end of said squeegee mounting means, each unit comprising a plate reciprocally movable on one of said guide flanges, a pair of upper and lower scissors members pivotally connected together at their one ends to said plate, the upper member connected at its free end to said squeegee gee, roller means rotatably connecting the free end of the lower member to said guide track means for recip rocal movement thereon, resilient means biasing the free ends of said members together whereby the members are pivotally movable as a unit about said roller means to thus vary the position of said squeegee relative to the; surface of said bed frame, spring means connected be tween said lower member and said plate whereby upon:

upward movement of said plate relative to said bed.

frame, said spring means pivots said members as a unit: about said roller means in a direction toward said bedi surface, and hook means mounted on said plate: and engageable with said pin, whereby upondownward. movement of said plate relative to said bed surface, said:

hook forceably rotates said members as a unit about said;

roller means in a direction away from said bed surface.

3. A silk screen printing press comprising a main: frame, a bed frame'for holding material to be printed upon, guide track means mounted on said bed frame, a; screen supporting frame movably mounted on said main frame for up and down movement toward and away from said bed frame, a screen mounted on said supporting frame, guide flange means mounted on said bed frame, a squeegee adapted for co-action with said screen; and means mounting said squeegee for reciprocal movement across and parallel to the surface of said bed frame including a pair of units secured at each end of said squeegee mounting means, each unit comprising a plate reciprocally movable on one of said guide flanges, a pair of members pivotally connected to said plate whereby the free ends of said members are movable in a scissors-like movement relative to each other, the free end of one member connected to said squeegee and the free end of the other member movably mounted on said guide track means, means biasing said free ends toward; each other whereby said members are movable as a; closed unit about the free end of said other member, means connected between said plate and said other mem' ber for biasing said members as a unit in a direction to move said squeegee toward the surface of said bed. frame upon an upward movement of said plate relative to said bed frame, and hook means connected between said plate and said one member whereby to rotate said members as a unit in a direction away from said surface of said bed frame upon a downward movement of said 2,076,023 Halsted Apr. 6, @937 plate relative to said bed frame. 2,263,966 Greenleaf NOV, 25, 1941 References Cited in the file of this patent Louft May 1947 UNITED STATES PATENTS 5v 2,704,510 Walsh Mar. 22,1955 1,922,710 Owens Aug. 15', 1933 2,581,775 Wade Jan. 8, 1952