Patent GB-419738-A (GB)
Title: Improvements in or relating to clamping mechanism for printing plates, fudge boxes and the like
IPC: B41F27/10
Filed: 1933-05-18
Abstract: 419,738. Printing-surfaces. QUICK, C. G., BALL, D. A., and MARSHALL, C. W., 109, Borough Road, London. May 18, 1933, No. 14412. [Class 100 (ii).] Relates to plate-clamping mechanism for printing-cylinders of the kind wherein a slidable operating member is permitted only a small movement in the plate release direction of movement with respect to a slidable plateclamping member and wherein a spring operates in the plate-clamping position, on the clamping- member to maintain it in engagement with the plate and also on the operating-member to tend to take up the small movement of the latter with respect to the clamping-member, and to hold an over-centre device for actuating the operating - member in an " over - centre " position, the arrangement being such that the operating-member when operated by the overcentre device to release the plate moves first relatively to the clamping-member, whereafter, when the operating-member reaches its limit of movement with respect to the clamping- member, the two members and the spring are moved bodily so that the only force expended on the spring is that required to move the overcentre device into or out of over-centre locking position, when the clamping-member is in engagement with the plate. According to the invention there is provided a second spring which so operates on the over-centre device as to hold it in a second or over-centre position corresponding to the non-clamping position of the actuating and clamping members. The printing-plate or fudge box 2 is clamped to the cylinder 1 by a clamp block 3 which is slidably mounted in a T-shaped recess in the cylinder and is formed with a guide portion 5 bored to receive an operating-rod 7 which extends beyond the guide portion and is screw-threaded to receive nuts 8, 9. The outer end of the rod 7 is provided with a head 10 against which abuts a compression spring 11 housed within a counter-bore formed in the guide portion 5, and the head is formed with a jaw piece 12 to which is pivoted one end of a link 14, to the other end of which is connected an operating-lever 15, pivoted at 16 to the support 17, rigid with the cylinder wall. The lever 15 and the adjacent end of the link 14 are so formed that, in the clamping position, they abut against one another, while a stop for limiting the unclamping movement is formed by the abutting surfaces of the members 15 and 17. The link connection constitutes an over-centre device and in clamping the plate or fudge box a clearance is provided between the nut 8 and the guide part 5 so that the plate is clamped resiliently and is locked by the over-centre device. In unclamping the plate, on rocking the lever 15, the link 14 is moved to the other side of the dead-centre line and the spring 11 presses back the member 7 until the nut 8 engages the part 5, when further movement of the operating-lever withdraws the clamp 3. The second weaker spring 18 assists in the unclamping movement and serves to maintain the device in a second over-centre position corresponding to the non-clamping position of the mechanism. The spring 18 also assists the spring 11 in maintaining the over-centre lock in its clamping position. The lever 15 is preferably so shaped as to be within the diameter of the cylinder at all times and lies close to the surface when in the clamping position. In a modified form, the axes of the pivot pins 13, 14<1>, 16 are arranged radially, so that the link 14 moves tangentially, the operating-lever 15 being caused to engage abutments formed on its support 17 at the limits of its movements.