Patent GB-402103-A (GB)
Title: Improvements in or relating to means for clamping printing plates, fudge boxes and the like
IPC: B41F27/10
Filed: 1932-05-24
Abstract: 402,103. Printing surfaces. LOUGEE, F. G. and PATTINSON, T. E., 109, Borough Road, London. May 24, 1932, No. 21302. [Class 100 (ii).] In power-actuated printing-plate, fudge box, and like clamping-mechanism a single control member is movable to effect control of power for moving a clamping-member into and out of clamping position and also to render operative and inoperative means providing a mechanical lock for holding the clamping-member in clamping position independently of power. In the pneumatic arrangement shown a printing-cylinder 1, of the kind provided with floating clamps or dogs in addition to the usual central fixed abutment so that it can accommodate four half-plates 18 on each half of the cylinder, is provided at each end with four cylinders 3 in which slide pistons 4, these cylinders being sealed by cover plates 5 secured to the printing-cylinder The printing-cylinder is slotted and provided with guides 6 for the reception of dogs 21, which are connected to the end clamps 2. The end clamps 2 are connected through the dogs 2<1> to the pistons. The opposite ends of each. cylinder are open to passages 7, 8, the passages 7 of each pair of cylinders branching from a common chamber 9 and the passages 8 branching from a common chamber 10. The chambers 9 and 10 can be placed in communication alternately with a common compressed-air supply passage 11 and with exhaust passages 12 by cocks 13. Positive retaining-means provided for maintaining each end clamp 2 in clamping-position in the case of a breakdown in the air supply include two extensions 19 on each clamp, and a retaining-segment 20 provided with two apertures 21 which can be moved, by rocking the segment, into line with the extensions 19 to permit the latter and the clamp to move out of clamping position. The engaging portion of each segment is tapered to allow for any variation in the length of the printing-plate 18. Each segment 20 is normally prevented from moving out of retaining position by three pawls 22, pivotally mounted at 23 on the cylinder, having teeth which are adapted under the action of spring plungers 25 to engage teeth 24 on the inner periphery of the segment. The three pawls are staggered so that a small movement is required from one retaining position to the next. To reverse the movement of the segments apertures 26 are located in the segments into which tools may be inserted to depress the pawls and move the segment. The movement of the segments 20 into and out of retaining-position also moves simultaneously the corresponding cocks 13 by the provision of pins 27 on the segments which engage the limbs of forked arms 28 secured to the cocks. The initial movement of each segment 20 towards retaining-position is employed solely to actuate the corresponding cock to allow air to be admitted to the right hand ends of the grouped pair of pistons, the apertures 21 being long enough to clear the extensions 19 during this initial movement. During the reverse movement of each segment 20 its tapered surfaces are moved clear of the extensions 19 on the clamp 2 and the apertures 21 brought into alignment before the cock is reversed. The pawls 22 acting on the segments 20 also serve as a means for preventing movement of the cocks. To enable printing-plates of different widths to be clamped the clamps 2 are formed with internal mutilated shoulders 50 which engage mutilated shoulders 51 on the extensions 19, the latter being rotatable but not movable axially in brackets 52 which pass through openings in the cylinders and are secured to the pistons 4, so that by partially rotating the extensions 19 the clamps 2 can be moved axially. Locking-means, such as setscrews 54, are provided to connect the extensions 19 to the pistons 4. The opening in the top of back cylinder is closed for any position of the piston. Instead of providing tapered surfaces on the segments to engage the clamp extensions adjustable screw-threaded studs may be arranged on the extensions, and the studs being adjusted to abut plane-faced segments when the latter are in retaining position. The segments may be replaced by two rings arranged side by side on the cylinder, one for each pair of end clamps 2, the rings bring provided with apertures which can be brought by movement of the rings into and out of line with the extensions on the end clamps, the inner ring having another pair of clearance apertures for the passage of the extensions 19 to the outer ring. Each ring is provided with a radial recess which is counterbored to receive spring-loaded locking-pins provided in the cylinder for holding it in either the clamp-retaining position or in a position where the apertures are in alignment with the extensions of the clamps. The spring-pins are depressed by tools thrust in the radial recesses, and to prevent the withdrawal or insertion of the tools at intermediate positions of the rings fixed plates are provided on the cylinder. The rings are cut away to receive projections on arms secured to the cocks so that as the rings are moved the corresponding cocks are simultaneously moved. To allow a printing-plate to be gripped between the floating dogs and the central fixed abutment each piston may be provided with a rod which engages an abutment on the corresponding floating dog to move it into clamping position. The supply of air to the passages may be effected through any form of rotary coupling 66. A non-return valve 67 is provided in the supply means, and also an automatic cut-out may be attached to shut down the motors and stop the printing-press if there is any failure of air pressure. The common supply passage may be fitted with a cock to allow the escape of air which is trapped by the non-return valve 67. Additional exhaust passages for the pistons, opened by the initial movement of the latter, may be provided to reduce the damping-effect during exhaust. Manually-operated clamping- means may be provided in addition to the power-operated means.