Printing plate locking device

A printing plate locking device for clamping a first printing plate onto a circumferential surface of a plate cylinder, the locking device comprising:

• a first tensioning device disposed in the plate cylinder which is engageable with the first printing plate to apply tension to the first printing plate;
• a first manually movable lever operatively connected to the tensioning device for moving the first tensioning device into engagement with the first printing plate, said first lever having an opening therein;
• a first manually movable retaining device which holds the lever in a holding position at times when the first tensioning device is engaged with and applies tension to the first printing plate thereby preventing a movement of the first lever which would cause disengagement of the tensioning device and the first printing plate;
• a rotatable shaft which is disposed in the plate cylinder and runs substantially parallel to a rotational axis of the plate cylinder;
• wherein the first tensioning device is mounted on the rotatable shaft and rotates therewith, and includes a lock-up shaft connected to the rotatable shaft to be rotatable therewith, a leaf spring having an end portion, the leaf spring is connected to the lock-up shaft and is rotatable therewith, the end portion of the leaf spring engages with a trailing edge of the first printing plate at times when tension is applied to the first printing plate by the first tensioning device;
• and a rotatable hook which engages the opening in the first lever to hold the lever in the holding position.

A method for clamping a printing plate on a circumferential surface of a plate cylinder having an opening therein, a tensioning device deposited in the opening, and a pivotally movable hook, the tensioning device including a rotatable shaft running substantially parallel to a rotational axis of the plate cylinder and being operatively connected to a lever, the method comprising the steps of:

• (a) engaging a leading edge of the printing plate with an edge of the opening;
• (b) bending the printing plate around the circumferential surface of the plate cylinder;
• (b) bending the printing plate around the circumferential surface of the plate cylinder;
• (c) moving the lever to rotate the rotatable shaft such that the tensioning device engages a trailing edge of the printing plate and applies tension thereon;
• and
• (d) pivoting the hook into engagement with the lever thereby holding the lever and correspondingly the tensioning device in a position whereby the tensioning device applies tension to the printing plate and the lever cannot be moved without disengaging the hook.

A printing plate locking device for clamping a first printing plate onto a circumferential surface of a plate cylinder, the locking device comprising:

• a first tensioning device disposed in the plate cylinder which is engageable with the first printing plate to apply tension to the first printing plate;
• a first manually movable lever operatively connected to the tensioning device, for moving the first tensioning device into engagement with the first printing plate, said first lever having an opening therein;
• a first manually movable retaining device which holds the lever in a holding position at times when the first tensioning device is engaged with and applies tension to the first printing plate thereby preventing a movement of the first lever which would cause disengagement of the tensioning device and the first printing plate;
• a rotatable shaft which is disposed in the plate cylinder and runs substantially parallel to a rotational axis of the plate cylinder, wherein the first tensioning device is mounted on the rotatable shaft and rotates therewith;
• a rotatable lock-up shaft which is disposed in the plate cylinder and which runs substantially parallel to a rotational axis of the plate cylinder, and a second tensioning device disposed in the plate cylinder which is engageable with a second printing plate to apply tension to the second printing plate, said second tensioning device being connected to the rotatable lock-up shaft and being rotatable therewith;
• a second lever connected to the second tensioning device for moving the second tensioning device into engagement with the second printing plate;
• and
• a second movable retaining device which holds the second lever in a holding position at times when the second tensioning device is engaged with and applies tension to the second printing plate thereby preventing a movement of the second lever which would cause disengagement of the second tensioning device and the second printing plate;
• wherein the lock-up shaft has a hollow space running therethrough and the rotatable shaft passes through the hollow space and is rotatable therein such that the first and second tensioning devices are independently movable.