US3349698A

US3349698A - Clamp assembly for use on screen printing machines

Info

Publication number: US3349698A
Application number: US436847A
Authority: US
Inventors: Matthew L Jaffa; Jaffa David
Original assignee: Individual
Current assignee: PRECISION ACQUISITION Inc A DE CORP (NOW KNOWN AS PRECISION SCREEN MACHINES Inc
Priority date: 1965-03-03
Filing date: 1965-03-03
Publication date: 1967-10-31
Anticipated expiration: 1984-10-31

Description

Oct. 31, 1967 M. L. JAFFA ETAL 3,349,698

CLAMP ASSEMBLY FOR USE ON SCREEN PRINTING MACHINES Filed March 5, 1965 3 Sheets-Sheet 1 FIG! I JNVENTORS Marrhew L.Jaffa BY David Jaff'a ATTORNEY 06b 1967 M. L. 'JAFFA ETAL 3,

CLAMP ASSEMBLY FOR USE ON SCREEN PRINTING MACHINES Filed March 5, 1965 3 Sheets-Sheet 2 FIG.4

22 37A 32c K 970 13 INVENTORS Marrhew L. Jaffa David Jaffa ATTORNEY Oct. 31, 1967 M. L. JAFFA ETAL 3,349,698

CLAMP ASSEMBLY FOR USE ON SCREEN PRINTING MACHINES Filed March 5, 1965 v 5 Sheets-Sheet 5 INVENTORS I David Jaffa ATTORNEY Mafihew L. Jaffa United States Patent 3,349,698 CLAMP ASSEMBLY FOR USE ON SCREEN PRINTING MACHINES Matthew L. Jaifa, 92 Clark St., Rutherford, NJ. 07070, and David Jada, 38-26 Allwood Place, Fair Lawn, NJ. 07410 Filed Mar. 3, 1965, Ser. No. 436,847 5 Claims. (Cl. 101-126) ABSTRACT OF THE DISCLOSURE This invention is directed to a screen printing machine having a frame on which an endless belt is mounted for indexing the material to be printed whereby the width of the belt defines the available printing area of the material to be supported thereon and a printing carriage including a screen frame having a screen supported thereon normally mounted on the machine frame for movement between a printing and non-printing position wherein the improvement resides in the utilization of a clamping means mounted on the machine frame and on the printing carriage which is adapted to grip the printing belt so as to permit maximum utilization of the width of the belt for effecting a screen print for a given size belt. This is attained by a clamping means comprising a fixed jaw member and a jaw member movably mounted with respect thereto. The arrangement is such that each of the respective jaw member is provided with complementary inclined surfaces for gripping the marginal edge portion of the belt and whereby one of the jaw members is provided with an outer surface which is rendered substantially flush with the horizontal surface of the belt so as to enable maximum utilization of the belt width for a given size belt during operation of the screen printing machine.

This invention relates, in general, to a screen printing machine; and more specifically to a novel clamping arrangement for use on a screen printing machine.

In a screen printing machine, particularly of the type disclosed in a copending application Ser. No. 159,956, filed Dec. 18, 1961, now Patent No. 3,199,449, the screen printing operation is performed on a moving printing belt or blanket with the printing occurring as the belt and material thereon is being indexed. As exemplified in the disclosure in the above mentioned copending application the material to be printed is disposed between a printing carriage, which carries the printing screen, and the printing belt or blanket. The arrangement is such that the printing screen is rendered movable between a printing and nonprinting position relative to the printing belt and material thereon. Accordingly, the moving belt functions both as the means for supporting the material to be printed and as the means whereby the material is indexed so that successive printing operations may be performed on a continuous strip of material. In this manner, a continuous strip of material may be successively printed with repeating designs or the like.

In such screen printing apparatuses a clamping means is usually disposed along the frame of the machine on either side of the belt for maintaining the belt fixed to the frame as the carriage and the printing screen carried thereon, is returned to its initial starting position after a printing operation has been completed. Cooperatively associated with the carriage are other clamping means which are adapted to engage the belt when the printing screen carried thereon is lowered into printing position. Thus, the printing belt, carriage, and material disposed therebetween are secured in printing position to prohibit relative movement therebetween during a printing and indexing operation. The belt, the carriage, and the material 'ice secured therebetween are thus simultaneously advanced or indexed in the direction of the belt travel during a screen printing operation by a suitable driving means. In operation when the first mentioned frame clamps are rendered inoperative the second mentioned carriage clamps are rendered operative, and when the carriage clamps are rendered inoperative, the frame clamps are rendered operative. In this manner the printing operation is simultaneously performed during the indexing operation of the material, with registration of succeeding designs or repeats being assured by positive clamping means to secure the belt and material as the printing carriage is returned to its initial starting position.

Heretofore, the known clamping construction, utilized for securing the printing carriage to the belt during the printing operation, or for holding the belt fast when the printing carriage is returned to its initial start position upon the completon of a printing operation, greatly reduced or minimized the usual surface area of such printing blanket. For this reason the effective printing area of the material was limited a corresponding amount. Heretofore, the largest known belt width that can be employed with present known technology is approximately 115 inches. Utilizing the known clamping constructions with such belt then, the maximum usable printing surface of the belt was normally reduced to a width of approximately inches to inches. The useful width of such belt was reduced because the marginal portions of the belt were rendered useless as a printing surface as this portion of the belt had to be used as the portion to be gripped by clamping means to secure the belt. The useful surface area of the printing belt blanket was further restricted by the width of the frame supporting the silk screen of the belt. Thus, with the known construction the useful width of a belt or blanket was reduced by the width of the clamp necessary to secure the belt to either the frame of the machine or to the printing carriage, and width of the frame supporting for the printing screen. Accordingly, the smaller width belts had their respective useful Working area proportionally reduced.

It is therefore the object of this invention to provide an improved clamping arrangement whereby the useful printing surface of a printing belt or blanket of a screen printing machine is enhanced without increasing the overall standard widths of known printing belts.

It is another object of this invention to provide relatively simple and positive acting clamp construction that is specifically adapted for use on screen printing machines to make it possible to use the maximum surface area of a printing belt or blanket.

It is another object of the invention to provide a specific clamping arrangement constructed and arranged so as to enhance the useful printing area of a printing bed or blanket by approximately 10 percent without increasing the overall standard width of such belts or printing blankets.

Still another object of this invention is to provide a clamp construction utilized in conjunction with a screen printing apparatus which underlies the frame of the printing screen so that the useful width of the belt is not diminished by the width of the screen frame.

Another object of this invention is to ing arrangement whereby the width or marginal portion of a printing belt o blanket heretofore reserved for accommodating the width of a printing screen frame is now rendered useful as a printing surface, and whereby the useful printing width or area of the belt is enhanced by an amount approximating twice the width of the screen printing frame.

In accordance with this invention, the foregoing objects, and other features and advantages are attained by providing a novel clamping assembly comprising of a means provide a clampfor mounting the clamp means either to the frame of the screen printing machine, or to the printing carriage mounted for movement along the frame of the machine. The clamping means fixed to the frame of the machine are cooperatively associated with respect to the belt so that when rendered operative, it maintains the moving belt or printing blanket fixed relative to the frame of the machine. A similarly operating clamping assembly adapted to be connected to the carriage, is cooperatively associated with the belt or blanket for securing the carriage thereto so that the carriage, the belt, and the material disposed therebetween may be moved in unison durind a screen printing and indexing operation as more particularly set forth in the copending patent application Ser. No. 159,956, filed Dec. 18, 1961.

In accordance with this invention clamping means comprise a mounting means by which the clamping assembly is secured to its associated structure. The clamping assembly includes a fixed jaw member provided with a substantially flat head portion disposed in substantially coplanar relationship with the upper surface of the printing belt or blanket. The fixed jaw is further provided with a downwardly incline gripping surface which is disposed in overlying relationship to the top surface of the printing belt or blanket. A movable jaw member is mounted for movement toward and away from the fixed jaw member, and it is provided with a complementary inclined gripping surface disposed beneath the blanket. Thus movement of the movable jaw toward the fixed jaw secures the printing blanket therebetween in a manner so that the gripped portion of the belt is angled downwardly. If desired, a non-skid surface may be disposed along the respective gripping surfaces of the respective jaws. A means in the form of a piston and cylinder assembly is cooperatively associated with the movable jaw so as to effect the actuation thereof between clamping and unclamping position with respect to the belt disposed therebetween.

Accordingly, the arrangement of the clamping means relative to the belt is such that the clamping jaws grip the belt at an angle with respect to the horizontal. Consequently, the arrangement is such that the frame of the printing screen overlies the gripping jaws so that both the width of the screen frame and the jaw members utilize or occupy the same marginal portion of the printing belt or blanket. For this reason the useful surface area of the printing blanket is enhanced by the width of the screen printing frame. Accordingly the useful printing surface area of the belt is enhanced without increasing the standard width of a known belt construction. With the con struction described the width of a present 115 inch wide printing belt or blanket can be increased approximately percent.

A feature of this invention resides in the provision of an improved clamping assembly that is specifically adapted for use on a screen printing machine wherein the respective clamping jaws thereof are provided with complementary inclined surfaces for gripping therebetween a marginal portion of a printing belt or blanket so that in an operative printing position the width of a screen frame overlies the jaws of the clamp to enhance the use ful printing area of the belt by an amount equal to substantially twice the width of the screen printing frame.

Another feature of this invention resides in the provision whereby the clamping assembly is relatively simple in construction, positive in operation, and which is particularly useful for application on screen printing machines.

Other features and advantages will become more readily apparent when considered in view of the drawings and description in which:

FIGURE 1 is a side elevation view of a clamp assembly adapted for use on a screen printing machine, wherein the clamping assembly is shown in the inoperative or open position.

FIGURE 2 is a right end view of the clamping assembly of FIGURE 1.

FIGURE 3 is a plan view of the clamping assembly of FIGURE 1.

FIGURE 4 illustrates an elevation view of a modified clamp construction adapted for use on a screen printing machine wherein the clamp assembly is illustrated in its closed or operative position.

FIGURE 5 is an end view of the clamping assembly of FIGURE 4.

FIGURE 6 is an elevation view of still another modified form of the invention.

FIGURE 7 is an end view of the clamping assembly of FIGURE 6.

Referring to the drawings there is shown in FIGURES 1 to 3, a clamping assembly 10 which in accordance with this invention is adapted to be utilized on a screen printing apparatus of the type disclosed in copending application Ser. No. 159,956, filed Dec. 18, 1961. Briefly, the screen printing apparatus in the mentioned copending application comprises a frame assembly 11 on which there is mounted over end rollers an endless printing belt or blanket 12. cooperatively associated with the printing belt or blanket 12 is a carriage (not shown) which supports thereon the printing screen 13 for movement between a raised non-printing position and lowered printing position with respect to the moving belt or blanket. Accordingly, a clamping means 10 is required to maintain the printing belt or blanket 12 fixed relative to the frame assembly 11 of the machine as the printing carriage and printing screen 13 carried thereon are moved to their initial starting position after the completion of a printing operation to its initial start position. Also, the printing carriage is provided with clamping means adapted to fixedly secure the carriage to the printing blanket so that during the printing operation, the printing blanket, the carriage and material disposed therebetween may be moved in unison to effect the printing operation as the material is being indexed or advanced a distance equal to the repeat of the design to be printed as more fully set forth in copending application Ser. No. 159,956, filed Dec. 18, 1961. Since the instant invention is merely concerned with the construction of the clamping assembly, a further detailed description of the screen printing apparatus is not considered to be pertinent to an understanding of the invention herein described.

Referring more specifically to FIGURES 1 to 3, a clamping assembly 10 disclosed is adapted to be secured to the frame 11 of the screen printing apparatus. Accordingly, the clamping assembly 10 comprises a mounting bracket 14 which is adapted to be suitably secured to the associated frame 15 of a screen printing machine. As shown, the mounting bracket comprises a plate suitably fixed to the frame of a screen printing machine. Connected to the extended end of the bracket 14 is the relatively fixed jaw member 16 of the clamping assembly. In the illustrated embodiment it is constructed as an inverted L-shaped member having a substantially flat head portion 16A and a downwardly inclined gripping surface 16B which defines with the flat head thereof a toe 17 portion that extends in overlying relationship to the marginal portion 12A of the printing belt or blanket 12. If desired, a suitable non-slip surface 18, as for example, a rubber pad or the like may be suitably secured to the inclined gripping surface 16B of the fixed clamp member 16.

Supported on the bracket 14 for relative movement toward the fixed clamp member 16 is a movable jaw member 19. As shown, the movable jaw member 19 is provided with a complementary inclined surface 19A which is adapted to be moved toward and away the inclined surface 16B of the fixed jaw member 16. The arrangement is such that the inclined surface 19A of the movable jaw member 19 is disposed beneath the lower surface of the moving belt or blanket and it too may be provided with a non-skid surface or pad 20. Means in the form of a piston and cylinder assembly 21 is supported on the mounting bracket 14 so as to effect the movement of the movable jaw member 19 toward and away the fixed jaw member 16 between clamping and non-clamping position. The arrangement is such that in the clamping position of the belt 12, the marginal gripped portion 12A of the belt is inclined downwardly between the respective inclined surfaces of the jaw members. In the operative or clamped position of the assembly, it is to be noted that the head 16A of the fixed jaw 16 member is rendered substantially flush with the horizontal surface area of the belt or blanket 12. Accordingly, the frame 22 of the printing screen 13 in printing position is disposed over the flat head portion 16A of the fixed clamp member 16. In this manner the width of the printing screen frame 22 does not occupy any portion of the horizontal printing surface of the printing belt or blanket 12. For this reason, the width or useful printing area of the printing belt or blanket 12 can be enhanced by twice the width of the printing screen frame 22, since the width of the printing screen frame 22 does not occupy any portion of the horizontal area of the belt. As the width of a printing frame 22 is 4 to 5 inches, it is to be noted that the useful width of a blanket resulting from the clamp construction herein described may be enhanced approximately 8 to 10 inches, (i.e. twice the width of the screen frame). Thus, the useful printing surface of a belt can be substantially increased.

FIGURES 4 and 5 illustrate a modified form of the invention. In this form of the invention the clamping assembly is adapted to connect to the printing carriage of a screen printed and it comprises a mounting means formed of a pair of spaced, angled

structural members

31, 32 in which the vertical legs portion thereof are spaced from one another. Interconnected between the vertically spaced leg portion of the mounting

members

31, 32 is channel member 33 to provide a base support for the piston and cylinder assembly 34 to actuate the movable jaw member 35 as will hereinafter be described. Fixed between the vertical legs of the mounting means and adjacent the end of the channel 33 is a standard 36 which extends upwardly therefrom. The fixed jaw member 37 of the clamp is secured to the standard 36. Means in the form of a pin and slot connection is provided to effect vertical adjustment of the fixed jaw member 37 along the standard 36. As shown, the standard 36 is provided with an elongated slot 36A adapted to receive suitable fasteners 38 by which the fixed jaw member 37 may be adjustably secured thereto. 7 -'The fixed jaw member37 comprises an inverted L shape member, having a horizontal leg portion 37A and vertical leg portion 37B, the vertical leg portion 37B being adapted to receive to fasteners 38 by which it is adjustably fixed to the standard 36. The horizontal leg 37A is provided with a flat top 37C and an inclined gripping surface 37D which inclines downwardly therefrom to define therebetween a toe portion that overlies a marginal portion 12A of a printing blanket 12. If desired, a non-skid surface as for example, a rubber pad 39 or the like may be suitably secured to the gripping surface of the fixed jaw member.

The movable jaw member is connected to a piston and cylinder assembly 34 which is suitably supported on the channel base 33 disposed between the angled mounting means 31, 32. Accordingly, the piston 40 of the pistoncylinder assembly 34 is connected to the movable jaw member 35. As hereinbefore described the movable jaw is provided with an incline surface 41 which complements the gripping surface 37D of the fixed jaw member. The movable jaw member 35 is disposed beneath the printing blanket 12, and it too provides a non-skid pad 42 or surface similar to that of the fixed jaw 37. The arrangement is such, that when the piston and cylinder assembly 34 is actuated, the movable member 35 is moved toward or away the fixed member. Thus as described in reference to the FIGURES 1 and 3, the fixed jaw member 37 is disposed so that its flat head portion 37C is substantially in co-planar relationship to the printing surface of the belt or blanket 12. Accordingly, the frame 22 of the printing screen 13 is disposed in overlying relationship to the fixed jaw member, thereby occupying the same portion of the belt as the gripping jaws. Thus the working area of the printing belt or blanket is not reduced by the frame width of the printing screen.

FIGURES 6 and 7 illustrate still another modified form of the invention. In the form of the invention the clamp assembly 50 comprises a pair of spaced,

angled members

51, 52 in which the vertical leg portions are spaced from one another. Secured between the vertical leg portion of the mounting means 51, 52 is a mounting block 53 which is provided with a bore 54. A standard 55 is supported in the bore 54 and a set screw 56 threaded through a tap opening formed in the side of the block 53 firmly secures the standard 55 in position therein. Connected to the block 53 is a vertical extending threaded stud 57 having a pair of adjusting

nuts

58, 59 threaded thereon. Accordingly, the adjusting

nuts

58, 59 form positioning means whereby a yoke 60 fitted on the stud 57 may be adjustably positioned in respect thereto. The yoke 60 is also provided with an aperture to embrace the standard 55 and it is fixed thereto by a suitable pin or fastener 61. Accordingly, the standard 55 may be vertically adjusted by setting the position of the yoke 60 relative to the threaded screw 57 by varying the set position of the locating

nuts

58, 59 thereon.

Fixed to the upper end of the standard 55 is an inclined jaw member 62 which functions as the fixed jaw member of the clamping assembly 50. If desired, a nonskid surface 63 may be suitably secured to the inclined surface of the fixed jaw member 62. A guide pin 64 may be connected to the yoke 60 to extend upwardly therefrom.

Mounted on the base 65 between the mounting

bracket members

51, 52 is a piston and cylinder assembly 66 which forms the support and actuator for the movable jaw member 67. Accordingly, the movable jaw member 67 comprises of a plate having an inclined surface to complement the incline of the fixed jaw member. If desired the movable jaw is also provided with a non-skid surface 68. The arrangement is such that in the clamping position, the marginal portion 12A of the belt 12 is securely held at an angle with respect to the horizontal between the inclined gripping surfaces of the

respective jaw members

62, 67. Consequently, the arrangement is such that the frame 22 of the printing screen 13 overlies the clamping jaw members and thereby does not minimize the useful horizontal width or area. of the printing belt or blanket 12.

In operation the movable jaw 67 is guided by the guide pin 64 secured to the yoke 60. Accordingly, in this form of the invention the elevation of the fixed jaw member 62 may be readily set by adjusting the yoke 60 and standard 55 secured thereto by setting the

positioning nuts

58, 59 accordingly.

From the foregoing it will be readily apparent that the respective improved clamping assemblies of the instant invention is such that the printing blanket 12 is securely gripped during the printing operation of the screen printing machine, and in a manner so that the screen printing frame 22 occupies the same portion of the belt which is gripped by the clamping means. In this manner the maximum horizontal width of the printing blanket of a given standard size is utilized.

While the instant invention has been described with reference to several embodiments thereof, it will readily be understood and appreciated that variations and modifications thereof may be made without departing from the spirit or scope of the invention.

What is claimed is:

1. In combination a screen printing machine having a frame and an endless belt mounted on said frame for indexing a material to be printed, the width of said belt defining the available printing area of a material supported thereon and a printing carriage including a screen frame and screen supported on said screen frame movably mounted on said machine frame for movement between a printing and non-printing position, the improvement comprising a clamping assembly mounted on said frame and on said printing carriage, each of said clamping assemblies including:

(a) a mounting means,

(b) a fixed jaw member supported on said mounting means,

(c) a movable jaw movably mounted on said mounting means,

(d) means for moving said movable away from said fixed jaw,

(6) said fixed jaw and movable jaw having complementary inclined gripping surface adapted for gripping the marginal edge portion of said belt therebetween, whereby said marginal edge portion is inclined to the horizontal surface of said belt,

(f) and said fixed jaw having an outer surface substantially flush with the horizontal surface of said belt so that said screen frame overlies the outer surface of said fixed jaw when said screen frame is moved into printing position whereby a maximum portion of the belt for a given belt is rendered available for effecting a screen print.

2. The invention as defined in claim 1 and including means for effecting adjustment of said jaw members relative to said belt.

3. A clamping assembly adapted to be used in combination with an endless printing blanket of a screen printing machine and comprising:

(a) a mounting bracket including a mounting block,

said block having a bore therein,

(b) a vertical adjustment means connected to said block,

(c) a yoke adjustable connected to said vertical adjustment means,

(d) a movable jaw means including a standard carried by said yoke,

(c) said standard having its lower end receivable in said bore,

(f) an inclined jaw member fixed to the upper end of said standard whereby the said fixed jaw member overlies a marginal portion of said blanket,

(g) a movable jaw member, said movable jaw having an inclined surface underlying said blanket,

(h) a piston and cylinder assembly mounted on said mounting bracket, the piston of said piston and cylinder assembly being connected to said movable jaw for effecting the movement of said movable jaw toward said fixed jaw for securing said blanket between said jaws when said piston is actuated,

(i) and means for guiding the movement of said movable jaw.

4. A clamping assembly adapted to be used in combination with an endless printing blanket of a screen printing machine and comprising:

(a) a mounting bracket including a mounting block having a bore therein,

(b) a threaded stud connected to said block,

(c) a yoke adjustably mounted on said threaded stud,

(d) nut means threaded on said stud for setting the position of said yoke thereon,

(e) a movable jaw means including a standard carried by said yoke,

jaw toward and (f) said standard having its lower end receivable in said bore,

(g) a set screw for securing the standard in said bore,

(h) an inclined jaw member fixed to the upper end of said standard whereby the said fixed jaw member overlies marginal portion of said blanket, said fixed jaw having a flattened corner portion,

(i) a movable jaw member having a complementary inclined surface underlying said blanket,

(j) a piston and cylinder assembly mounted on said mounting bracket, the piston of said piston and cylinder assembly being connected to said movable jaw for effecting the movement of said movable jaw toward said fixed jaw for securing said blanket between said jaws when said piston is actuated,

(k) and means for guiding the movement of said movable jaw between clamping and unclamping position.

5. In combinaton, a screen printing machine having a movable printing blanket with predetermined area to define the printing surface of said machine, and a printing head including a printing screen movable into printing and non-printing relationship with said blanket, and said printing screen including a frame, the improvement of:

(a) a clamping assembly for securing the printing head to said printing blanket during a screen printing operating of the machine,

(b) said clamping assembly including a mounting means by which said clamping assembly is fixedly secured to the printing head for movement therewith,

(c) a standard fixed to said mounting means,

(d) a fixed jaw member,

(e) said jaw member having a fiat upper surface and gripping surface inclined relative to said fiat surface whereby with said gripping surface overlies said blanket, said flat surface is disposed substantially coplanar with the surface of said blanket for accommodating the frame of said screen,

(f) a movable jaw member,

(g) said movable jaw member having an inclined gripping surface underlying said blanket,

(h) and means including a piston and cylinder assembly for moving said movable jaw member relative to said fixed jaw member to grip therebetween a marginal portion of said blanket, said marginal portion being inclined relative to the horizontal printing surface of said blanket,

(i) the cylinder of said assembly being fixedly secured to said printing head, and

(j) said movable jaw being carried on the piston of said piston and cylinder assembly.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 6/ 3 Australia. 7/ 1948 Great Britain. 1/ 1955 Great Britain.

ROBERT E. PULFREY, Primary Examiner.

J. R. FISHER, Assistant Examiner,

Claims

5. IN COMBINATION, A SCREEN PRINTING MACHINE HAVING A MOVABLE PRINTING BLANKET WITH PREDETERMINED AREA TO DEFINE THE PRINTING SURFACE OF SAID MACHINE, AND A PRINTING HEAD INCLUDING A PRINTING SCREEN MOVABLE INTO PRINTING AND NON-PRINTING RELATIONSHIP WITH SAID BLANKET, AND SAID PRINTING SCREEN INCLUDING A FRAME, THE IMPROVEMENT OF: (A) A CLAMPING ASSEMBLY FOR SECURING THE PRINTING HEAD TO SAID PRINTING BLANKET DURING A SCREEN PRINTING OPERATING OF THE MACHINE, (B) SAID CLAMPING ASSEMBLY INCLUDING A MOUNTING MEANS BY WHICH SAID CLAMPING ASSEMBLY IS FIXEDLY SECURED TO THE PRINTING HEAD FOR MOVEMENT THEREWITH, (C) A STANDARD FIXED TO SAID MOUNTING MEANS, (D) A FIXED JAW MEMBER, (E) SAID JAW MEMBER HAVING A FLAT UPPER SURFACE AND GRIPPING SURFACE INCLINED RELATIVE TO SAID FLAT SURFACE WHEREBY WITH SAID GRIPPING SURFACE OVERLIES SAID BLANKET, SAID FLAT SURFACE IS DISPOSED SUBSTANTIALLY COPLANAR WITH THE SURFACE OF SAID BLANKET FOR ACCOMMODATING THE FRAME OF SAID SCREEN, (F) A MOVABLE JAW MEMBER, (G) SAID MOVABLE JAW MEMBER HAVING AN INCLINED GRIPPING SURFACE UNDERLYING SAID BLANKET, (H) AND MEANS INCLUDING A PISTON AND CYLINDER ASSEMBLY FOR MOVING SAID MOVABLE JAW MEMBER RELATIVE TO SAID FIXED JAW MEMBER TO GRIP THEREBETWEEN A MARGINAL PORTION OF SAID BLANKET, SAID MARGINAL PORTION BEING INCLINED RELATIVE TO THE HORIZONTAL PRINTING SURFACE OF SAID BLANKET, (I) THE CYLINDER OF SAID ASSEMBLY BEING FIXEDLY SECURED TO SAID PRINTING HEAD, AND (J) SAID MOVABLE JAW BEING CARRIED ON THE PISTON OF SAID PISTON AND CYLINDER ASSEMBLY.