GB2032349A - Screen printing machines - Google Patents

Abstract

A screen printing machine of the flat bed type in which at least one of the parallel members (2) of the master frame carries a removable saddle clamp (1) for securing a screen printing frame (5) within the master frame. Each clamp is slidable along the associated member to position the screen printing frame, which may be of any suitable length, and is manually operable to grip the master frame and secure the printing frame in a desired position. <IMAGE>

Description

SPECIFICATION Screen printing machines This invention relates to screen-printing machines of the flat-bed type and its principal object is to enable relatively lightweight printing screens of different lengths to be readily attached to and removed from the machine without disturbing the setting of the usual counter-balanced master frame.

To this end, according to the invention, we propose a screen printing machine in which at least one, and preferably both of two parallel members of the master frame has one or more removable clamping devices for supporting and detachably securing a screen printing frame to the master frame, each device being slidable along the associated master frame member to position the printing frame and manually operable to securely grip both the master frame and the printing frame when the latter is correctly positioned for printing.

A preferred form of the invention will be described, by way of example, with reference to the accompanying drawing in which: Figure 1 is a plan view of one corner of a screen printing machine showing one of the clamping devices securing the screen printing frame to the master frame; and Figure 2 is a cross-section through one side of the master frame showing the clamping device in end elevation.

Each clamping device is made of mild steel and includes a saddle in the form of an inverted channel-section member which fits loosely over one of two parallel longitudinally extending members 2 of a welded steel master frame which is pivotally mounted in usual manner on the base frame of the machine and counter-balanced by springs. The innermost (with respect to the frame) limb 3 of the saddle 1 is formed at its lower end with an inwardly directed flange 4 which is adapted to form a seat for one side member 5 of a screen printing frame which is lighter in weight than the master frame and is made of wood or metal.

Between the outermost limb 6 of the member 1 and the outer surface of the frame member 2, is a clamp plate 7 which passes through an aperture in the web portion of the member 1 and is provided at its lower end with a flange 8 which engages the lower end of the frame member 2. The upper end of the clamp plate 7 is hook-shaped and forms a pivotal mounting for a pin 9 welded to the under surface of a clamping element 10 which extends at right angles to the axis of the pin, through a central aperture in the hooked end of the clamp plate.

The clamping element 10 extends transversely above the frame member 2 and is provided at its outer end with a tapped hole for the passage of a threaded shaft 11 provided at its outer end with a manually operable knob 12 and at its inner end with a domed nut 13 which engages the outer limb 6 of the saddle 1.

It is preferred to employ two clamping devices on each of two parallel master frame members 2, which devices are positioned to support the corners of a printing frame which is then seated on the flanges 4 of the saddles 1. When each device is in position supporting the printing frame, the knob 12 is turned to rotate the shaft 11 which acts through the nut 13 to clamp the device to the frame member 2. When the shaft 11 can no longer move axially relative to the clamping element 10 the outer end of the latter moves outwardly relatively to the shaft and the clamping element rocks about the axis of the pin 9 to force the outer end of the clamping element into firm engagement with the upper end of the printing frame member 5 which thus becomes clamped between the clamping element and the flange 4 on the saddle 1.

The machine is then ready for printing and when printing is completed it is a simple matter to release the clamping devices and remove the printing frame for replacement by another.

1. A screen printing machine of the flat bed type in which at least one of two parallel members of the master frame has one or more removable clamping devices for supporting and detachably securing a screen printing frame to the master frame, each device being slidable along the associated master frame member to position the printing frame manually operable to securely grip both the master frame and the printing frame when the latter is correctly positioned for printing.

2. A machine according to claim 1 wherein the clamping device comprises a saddle which fits over the associated master frame member and supports a pivoted clamp element straddling the said master frame member wherein one end of the clamp carries a clamping screw acting to tighten the saddle or the said master frame member and the other end bears upon the printing frame when the clamp element pivots as the screw is tightened.

3. A machine according to claim 2 wherein the saddle comprises an inverted channel section member provided on its innermost (with respect to the master frame) side, a flange affording a seat for the associated side member of the screen printing frame.

4. A machine according to claim 2 or claim 3 wherein the clamping element is pivoted upon a plate passing through an aperture into the hollow of the saddle, the lower end of the plate being formed with a flange adapted to engage beneath the said associated master frame member.

5. A screen printing machine constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Screen printing machines This invention relates to screen-printing machines of the flat-bed type and its principal object is to enable relatively lightweight printing screens of different lengths to be readily attached to and removed from the machine without disturbing the setting of the usual counter-balanced master frame. To this end, according to the invention, we propose a screen printing machine in which at least one, and preferably both of two parallel members of the master frame has one or more removable clamping devices for supporting and detachably securing a screen printing frame to the master frame, each device being slidable along the associated master frame member to position the printing frame and manually operable to securely grip both the master frame and the printing frame when the latter is correctly positioned for printing. A preferred form of the invention will be described, by way of example, with reference to the accompanying drawing in which: Figure 1 is a plan view of one corner of a screen printing machine showing one of the clamping devices securing the screen printing frame to the master frame; and Figure 2 is a cross-section through one side of the master frame showing the clamping device in end elevation. Each clamping device is made of mild steel and includes a saddle in the form of an inverted channel-section member which fits loosely over one of two parallel longitudinally extending members 2 of a welded steel master frame which is pivotally mounted in usual manner on the base frame of the machine and counter-balanced by springs. The innermost (with respect to the frame) limb 3 of the saddle 1 is formed at its lower end with an inwardly directed flange 4 which is adapted to form a seat for one side member 5 of a screen printing frame which is lighter in weight than the master frame and is made of wood or metal. Between the outermost limb 6 of the member 1 and the outer surface of the frame member 2, is a clamp plate 7 which passes through an aperture in the web portion of the member 1 and is provided at its lower end with a flange 8 which engages the lower end of the frame member 2. The upper end of the clamp plate 7 is hook-shaped and forms a pivotal mounting for a pin 9 welded to the under surface of a clamping element 10 which extends at right angles to the axis of the pin, through a central aperture in the hooked end of the clamp plate. The clamping element 10 extends transversely above the frame member 2 and is provided at its outer end with a tapped hole for the passage of a threaded shaft 11 provided at its outer end with a manually operable knob 12 and at its inner end with a domed nut 13 which engages the outer limb 6 of the saddle 1. It is preferred to employ two clamping devices on each of two parallel master frame members 2, which devices are positioned to support the corners of a printing frame which is then seated on the flanges 4 of the saddles 1. When each device is in position supporting the printing frame, the knob 12 is turned to rotate the shaft 11 which acts through the nut 13 to clamp the device to the frame member 2. When the shaft 11 can no longer move axially relative to the clamping element 10 the outer end of the latter moves outwardly relatively to the shaft and the clamping element rocks about the axis of the pin 9 to force the outer end of the clamping element into firm engagement with the upper end of the printing frame member 5 which thus becomes clamped between the clamping element and the flange 4 on the saddle 1. The machine is then ready for printing and when printing is completed it is a simple matter to release the clamping devices and remove the printing frame for replacement by another. CLAIMS

1. A screen printing machine of the flat bed type in which at least one of two parallel members of the master frame has one or more removable clamping devices for supporting and detachably securing a screen printing frame to the master frame, each device being slidable along the associated master frame member to position the printing frame manually operable to securely grip both the master frame and the printing frame when the latter is correctly positioned for printing.

2. A machine according to claim 1 wherein the clamping device comprises a saddle which fits over the associated master frame member and supports a pivoted clamp element straddling the said master frame member wherein one end of the clamp carries a clamping screw acting to tighten the saddle or the said master frame member and the other end bears upon the printing frame when the clamp element pivots as the screw is tightened.

3. A machine according to claim 2 wherein the saddle comprises an inverted channel section member provided on its innermost (with respect to the master frame) side, a flange affording a seat for the associated side member of the screen printing frame.

4. A machine according to claim 2 or claim 3 wherein the clamping element is pivoted upon a plate passing through an aperture into the hollow of the saddle, the lower end of the plate being formed with a flange adapted to engage beneath the said associated master frame member.

5. A screen printing machine constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.