DE4329125C1 - Device for renewing a printing foil on the outer surface of a forme cylinder - Google Patents

Abstract

The invention relates to a device for renewing a printing foil on the outer surface of a forme cylinder which allows the printing foil to be attached homogeneously. The invention consists in the fact that, outside a forme cylinder (1), a device (10, 11, 12) is provided for lifting an unwinding roll (4) out of the forme cylinder (1), said unwinding roll (4) remaining coupled to a brake device, and it being possible for a winding roll (3) to be fixed during the rotation of the forme cylinder (1) to prevent rotation relative to the forme cylinder (1). The invention can be used in printing machines or printers which use foil-like printing formes.

Description

The invention relates to a device for renewing a Printing film on the surface of a forme cylinder. The Invention is applicable to printing presses on the Forme cylinder a stretched printing film is used and the by unwinding from a supply roll and by winding on a roll for the used printing film is renewed.

It is already known from DE 42 24 332 A1, a Unwinding and one winding roll in one insert to accommodate which is interchangeable in a channel one Forme cylinder is held. The ends of the printing film are each set on the reel bodies, being for renewal and tensioning the printing film with special winding Transport rollers is driven and the unwinding roller is braked. To the friction when clamping over the To reduce channel edges are in the periphery of the Form cylinder two deflection rollers provided with the Interacting transport rollers.

The disadvantage here is that when tensioning the printing film, the Printing film on the entire surface of the forme cylinder and glides over the channel edges. As a result of Coefficient of friction between the printing film and the Lateral surface and the surface of the channel edges, the Printing film is insufficiently tensioned, causing the printing film does not lie smoothly on the entire surface. This Deficiency can also not be caused by a smoothing device roller rolling off the forme cylinder when the printing film is tensioned will eliminate. When structuring the printing film and when  subsequent printing with the printing film are due to the inhomogeneous tensions within the printing film printing error to be expected because the printing film with rolling contact with a transfer cylinder or directly with a substrate partial relative movements on the lateral surface of the Executing forme cylinders.

The object of the invention is a device for renewal a printing film on the outer surface of a forme cylinder develop a homogeneous application of the printing film enables.

The task is characterized by the objective characteristics of the Part of claim 1 solved.

To replace the printing film, the unwind roll is first dug out of the forme cylinder. The form cylinder will then set in rotation, the used printing film wound up on the take-up roll is and the printing film from the outer surface of the Form cylinder is withdrawn. After reaching the end position the take-up roll is held and the Forme cylinder rotating in the opposite direction transferred. This rotation creates new printing film material removed from the unwind under tension and in essentially tangential to the lateral surface of the Form cylinder placed. The clamping forces result from the braking forces acting on the unwinding cylinder. By the The printing film can be placed tangentially under high Tension, but applied without friction to the forme cylinder become. After reaching the end position for hanging up the can correspond to the starting position for the peeling  brought the unwinding roll back into the forme cylinder and locked there.

A can be used to raise and lower the unwind roll Gripping mechanism can be used with grippers on the Axis attaches to the side of the unwind roll. After this The gripper mechanism is replaced by renewing the printing film Moving and pivoting disengaged so that the forme cylinder can move freely for the following printing process is.

An embodiment of the invention is based on a Drawing will be explained in more detail. Show it:

Fig. 1 shows a device in the starting and end positions for renewing the printing film and

Fig. 2 u. 3 two different positions of a forme cylinder when clamping new printing film.

Fig. 1 shows a forme cylinder 1 , in the channel of an interchangeable magazine 2 with a take-up roll 3 and a take-off roll 4 for a printing film 5 is seated. The ends of the printing film 5 are fixed on the roll bodies of the winding roll 3 and the unwinding roll 4 . The printing film 5 is drawn over the channel edges 6 , 7 over the outer surface 8 of the forme cylinder 1 . The take-up roll 3 is coupled to a drive, not shown, and can be held in place if necessary. The unwinding roll 4 has coupling elements 9 on the side for gripping elements 10 , 11 of a gripper arm 12 . The rotation of the unwinding roller 4 in the direction 13 is braked. The gripper arm 12 is pivotable about an axis 14 and displaceable in the direction 15 for coupling into the coupling elements 9 . The forme cylinder 1 can be rotated in the directions 16 and 17 by means of a drive, not shown, preferably the machine drive.

The renewal of the printing film 5 will be described in the following:

In the starting position of the forme cylinder 1 , the gripper arm 12 is displaced in the direction 15 such that the gripping elements 10 , 11 are connected to the coupling elements 9 . Then the gripper arm 12 pivots into the position shown in dashed lines, so that the unwinding roll 4 is lifted out of the channel of the forme cylinder 1 with a supply of new printing film 5 . In this position, the unwinding roll 4 lies outside the outer diameter of the forme cylinder 1 . In a next step, the forme cylinder 1 is rotated in the direction 16 and at the same time the winding roll 3 is driven in the direction 18 , so that the old printing film 4 unwinds from the outer surface 8 and is wound onto the winding roll 3 . The unwinding roll 4 does not perform any rotary movement. In FIG. 2, the form cylinder 1 is in the final position for the unwinding of the printing ribbon 5 from the circumferential surface 8. In a further step, the take-up roll 3 is locked so that it cannot perform any rotational movement relative to the forme cylinder 1 . To draw new printing film 5 onto the outer surface 8 , the forme cylinder 1 is rotated in the direction 17 . As shown in FIG. 3, the new printing film 5 is drawn tangentially onto the lateral surface 8 under tension. The unwinding roll 4 rotates in the direction 13 under the action of braking forces.

After reaching the end position for pulling on the jacket surface 8, which also corresponds to the initial position shown in Fig. 1 for unwinding the spent printing ribbon 5 from the circumferential surface 8, the unwinding roller 4 is pivoted back in the changing magazine 2 by means of the gripper arms 12 and locked there. In a last step, the gripper arm 12 is pulled out of the engagement area of the coupling element 9 by moving it away from the forme cylinder 1 in the direction 15 and then pivoting it out of the working area of the forme cylinder into the position shown in broken lines. Thereafter, the renewed printing film 5 can be used for printing.

Reference list

1 forme cylinder
2 exchange magazine
3 take-up roll
4 unwinding roll
5 printing film
6 , 7 channel edge
8 outer surface
9 coupling elements
10 , 11 gripper elements
12 gripper arm
13 direction
14 axis
15 , 16 , 17 , 18 direction

Claims (4)

1. Device for renewing a printing film on the outer surface of a forme cylinder, consisting of an unwinding roller and a winding roller for the printing film, on which the ends of the printing film are fixed and which are arranged parallel to the axis of rotation inside the forme cylinder, the winding roller and the forme cylinder is each coupled to a controlled drive and the unwinding roller is coupled to a braking device, characterized in that a device ( 10 , 11 , 12 ) for lifting the unwinding roller ( 4 ) out of the forme cylinder ( 1 ) is provided outside the forme cylinder ( 1 ) , The unwinding roller ( 4 ) remains coupled to the braking device and the winding roller ( 3 ) can be locked during the rotation of the forme cylinder ( 1 ) to prevent rotation relative to the forme cylinder ( 1 ). 2. Device according to claim 1, characterized in that the device consists of pivotable gripping arms ( 12 ), the gripping mechanism ( 10 , 11 ) with the axis of the unwinding roller ( 4 ) can be coupled. 3. Device according to claim 2, characterized in that the gripper arms ( 12 ) are displaceable perpendicular to the axis of rotation of the forme cylinder ( 1 ). 4. Device according to claim 1, characterized in that the unwinding roller ( 3 ) by means of the device ( 10 , 11 , 12 ) can be lifted so far that the printing film ( 5 ) tangentially attaches to the rotating forme cylinder ( 1 ) under tension.