JPH0256215B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for securing a rubber blanket to a blanket cylinder of an offset printing press.

A fastening device for a rubber blanket known from German Patent Application No. 11 24 051 has two identical clamping elements for the front and rear edges of the rubber blanket.
Each clamping element has a clamping shaft with an axial receiving slot in each case for accommodating a respective rubber blanket edge with a reinforcing strip. In this case, the reinforcing strips, which in each case project laterally beyond the rubber blanket, are each held approximately parallel to the axis of the blanket cylinder via a rotatable friction ring. The tightening is
This is done by rotating the tightening shafts in opposite directions.

It is difficult to always cut the flexible material of a rubber blanket at a 90 degree angle to the side edges of the rubber blanket, and when installing reinforcing strips, the reinforcing strips must be cut at a 90 degree angle to the side edges of the rubber blanket. It may be tilted slightly. When a rubber blanket with reinforcing strips on its front and rear edges, which reinforcing strips do not extend exactly at an angle of 90 degrees to the side edges of the rubber blanket, is tightened to the blanket cylinder, Different tensions occur in different areas of the rubber blanket, which results in double or smudged areas during printing.

In addition, the Federal Republic of Germany Patent Application Publication no.
In the case of the fastening device for rubber blankets known from German Patent No. 2,631,119, the ends of the rubber blanket are not provided with reinforcing strips. Such a device has only one radially movable clamping strip with a common slot for both rubber blanket ends. A plurality of clamping members distributed over the entire length of the slit are supported on both sides of the slit, which clamping members, when the clamping strips are moved radially inwards, are supported by an inclined stationary surface. It is moved at right angles to the slit side walls and thereby clamps both rubber blanket ends between the slit walls. At the same time as the clamping strip moves radially inward, the rubber blanket is tensioned.

With such devices, there is also the risk of non-uniform tightening in different areas of the rubber blanket. Wrap a rubber blanket around your torso,
If the leading and trailing edges are then inserted into a common slit, it is not ascertained whether both edges actually extend parallel within the slit. Moreover, the slit must be oriented upwardly for the introduction of the rubber blanket end, so that the lower half of the rubber blanket is free to sag. Even if one were to attempt to smooth the rubber blanket along the circumference of the blanket cylinder - which is inherently difficult due to the obstruction of adjacent press cylinders - the rubber blanket would Due to its elasticity, it cannot be completely guaranteed that the blanket will lie evenly and evenly on the cylinder over its entire circumference. However, if this is not guaranteed, the individual areas of the rubber blanket will have different tensions during tightening.

The object of the invention is to provide a method and a device with which rubber blankets can be tightened reliably and uniformly with little operating effort.

The object of the invention is a method for fixing a rubber blanket on the blanket cylinder of an offset printing press, the rubber blanket having reinforcing strips mounted immovably approximately at right angles to the side edges of the rubber blanket. Insert the front edge into a narrow cylinder slit extending along the generatrix of the blanket cylinder and widening inwardly into the recess, up to a stop on a first clamping member arranged in the cylinder slit; The front edge of the blanket is thus positioned parallel to the blanket cylinder axis and the unreinforced rear edge of the blanket is positioned by a second clamping member which is operated independently of the first clamping member. In the case of a type in which the front edge is fixed, the rubber blanket is rotated at approximately the same circumferential speed by a blanket cylinder and another cylinder that is in contact with the blanket cylinder, which corresponds to the pressure during printing. Wrap it around the blanket while applying pressure and stretching it along the circumference of the blanket, then loosen the rear edge of the rubber blanket into the tightening member of the blanket at the position obtained by the stretching. The problem was solved by inserting the rubber blanket into the recess, then pushing the rubber blanket completely into the recess and fixing it to the rubber cylinder by means of a second tightening member.

The device for implementing the method according to the invention is characterized by a device for fixing a rubber blanket on the blanket cylinder of an offset printing press, which extends along the generatrix of said blanket cylinder and expands inwardly into a recess. and a narrow body slit with a narrow body slit, within which are provided two separately operated clamping members for the front and rear edges of the rubber blanket, each clamping member The rubber blanket is of the type consisting of a clamping shaft with a receiving slot for each end edge of the blanket, and in which the bottom of the receiving slot for the front edge of the rubber blanket forms a stop. The receiving slit for the rear edge of the rubber blanket passes completely through the tensioning shaft and is arranged asymmetrically, and the part with the receiving slit of the tensioning shaft for the rear edge of the rubber blanket and the rubber cylinder are provided. A groove-shaped hollow chamber is provided between them, the cylindrical limiting walls of which are separated from each other by the thickness of the rubber blanket, and the tensioning shaft for the rear edge of the rubber blanket is relaxed. A groove is provided in the rubber cylinder which, when in position, is an extension of the receiving slot of the tensioning shaft, the depth of the groove being longer than the maximum length of the rear end section of the rubber blanket into which it is to be introduced. and the clamping shaft for the rear edge of the rubber blanket is held at both ends in bearing rings, which reduce the mutual spacing of the two cylindrical limiting walls of said hollow chamber. It is eccentrically adjustable.

With the method and device of the present invention, the rubber blanket is reliably and evenly tightened to the blanket cylinder, thereby eliminating blurred printing and double printing caused by uneven tightening of the rubber blanket, and improving the quality of printing. be able to.

The invention will be explained below with reference to the exemplary embodiments shown.

The fastening device shown in the exemplary embodiment is provided for tensioning a rubber blanket 1 on a blanket cylinder 2, the front edge 3 of which has a reinforcing strip fixedly connected to the rubber blanket. 4. In this case, the reinforcing strips 4 extend at right angles to the side edges of the rubber blanket. The rear edge 5 of the rubber blanket 1 is formed by an unreinforced cut edge.

The fastening device has two clamping elements designed as clamping shafts 6, 7, which clamping elements are connected to the rubber cylinder 2.
It is arranged in a recess 8 in . The recess 8 is
A narrow cylinder slit 9 extending along the generatrix of the rubber cylinder 2
connected to the outside world via. The tensioning shaft 7 is mounted at each end in an eccentric bearing ring 10, which itself is rotatably arranged in the side wall 11 of the blanket cylinder 2.
The axis of the tensioning shaft 7 and the axis of the eccentric bearing ring 10 are offset from each other as shown in FIG.
Therefore, when the eccentric bearing ring 10 is rotated by a handle (not shown), the axis of the tensioning shaft 7 is caused to move in the direction of the arrow a. The tightening shaft 6 is
It is supported in a stationary bearing (not shown) in the side wall 11. Furthermore, both tightening shafts 6, 7 are
They can be manually rotated individually and independently of one another in the direction of arrows b, c or vice versa via known adjusting devices (not shown).

The tightening shaft 6 is provided with an accommodation slit 12, which accommodates the two side walls 13, 14.
and a bottom part forming a stop 15 for the reinforcing strip 4. The stopper 15 extends parallel to the axis of the blanket cylinder 2. This ensures that the reinforcing strip 4, which is completely inserted into the receiving slot 12, also extends parallel to the axis of the blanket cylinder 2. The mutual spacing of the two side walls 13, 14 is designed such that the reinforcing strip can be easily inserted into the receiving slot 12. In order to prevent the reinforcing strip 4 from slipping out of the receiving slot 12 unintentionally, the side walls 13, 14 are preferably roughened. A rectangular hollow chamber 16 is formed between the tightening shaft 6 and the rubber cylinder 2, and the outer cylindrical limiting wall 17 of the hollow chamber extends from the limiting wall of the tightening shaft 6 to the thickness dimension of the rubber blanket 1. are separated by only

The clamping shaft 7 is passed through by a receiving slot 18 over the width of the rubber blanket. Tightening shaft 7
in the relaxed position shown schematically in FIGS. 3 and 4, the receiving slit 18 is aligned with the groove 19 in the blanket cylinder 2. Furthermore, a rectangular hollow chamber 20 is formed between the clamping shaft 7 and the stationary part of the blanket cylinder 2, and the outer limiting wall 21 of this hollow chamber extends from the wall of the clamping shaft 7 by the thickness dimension of the rubber blanket 1. separated from

To tension the rubber blanket 1, the tensioning shaft 6 is first brought into the relaxed position, in which the receiving slot 12 is directed towards the body slot 9. The front edge of the rubber blanket 1 with the reinforcing strip 4 is then pushed into the receiving slit 12 until said reinforcing strip 4 completely abuts the stop 15 of the receiving slit 12.
manually introduced into the body. The tensioning shaft 6 is then rotated, also by hand, to the position shown in FIG. This ensures that even if in the next operating step the rubber cylinder 2 and the further cylinder 22 are pressed against each other via an adjusting device acting at least on the support of the cylinders, the rubber blanket 1 remains It will no longer fall out of the containment slit. The further cylinder 22 may be an impression cylinder or, if configured as a printing device for a double-sided printing press, a further blanket cylinder. The above-mentioned application is carried out to the extent that printing can be carried out. Thereafter, both cylinders are rotated together through approximately 330 degrees in the direction of the arrows d and e at approximately the same circumferential speed via the drive motor of the printing device and the transmission drive chain connected subsequently thereto.
In this case, the rubber blanket 1 is stretched along the circumference of the blanket cylinder, as can be seen in FIG.

Once the position shown in FIG. 4 has been reached, the rear edge 5 of the rubber blanket 1 is again manually inserted into the preferably asymmetrically arranged receiving slot 18. The blanket cylinder 2 and the further cylinder 22 are then rotated further to the position shown in FIG. In this case, the rear edge 5 of the rubber blanket 1 is inserted through the receiving slot 18 into the groove 19. Groove 19
is formed to such a depth that the rear edge 5 does not reach the bottom of the groove 19. The tightening shaft 7 is now rotated in the direction of the arrow c, so that the rear end of the rubber blanket 1 is fixed in the extended position and at the same time tightened (see FIG. 1). In parallel with this, rear tightening of the front end of the rubber blanket 1 is carried out by further rotating the tightening shaft 6 in the direction of arrow b. This concludes the tightening process of the rubber blanket 1.

In the illustrated embodiment, the rear end of the rubber blanket is mounted eccentrically between the clamping shaft 7 and the limiting wall 21 in order to ensure that the rear end of the rubber blanket is fixed after the tightening process has ended. Tightening is possible by rotating the ring 10.

As mentioned above, it is important that the front edge 3 of the rubber blanket is fixed to the tensioning shaft 6 exactly parallel to the axis of the blanket cylinder 2. On the other hand, the rear end of the rubber blanket 1
is stretched by another body 22 and loosely tightened on the shaft 7
and then tightened in this position. This has the advantage that the tension in the rubber blanket can be almost completely uniform after the tightening process has been carried out.

Another advantage of the invention is that the width of the body slit 9 can be made very small. This width should be designed such that the reinforcing strip 4 on one side and the two layers of the rubber blanket 1 on the other side can pass freely through it. The smallest possible width of the shell slit 9 is determined by adding to both of these values a dimensional increment that ensures that the movement of the reinforcing strip or rubber blanket is not hindered by friction on the walls of the shell slit. There is.

FIG. 6 schematically shows a further advantageous embodiment of the receiving slot 12. In this case, the receiving slot 12 is made relatively wide and has a projection or projection 23. When the tightening shaft 6 is rotated, the rubber blanket 1 abuts against the projection 23 with one upper edge of the reinforcing strip 4 and is positioned.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the fixing device according to the invention taken through the center of the blanket cylinder, FIG. 2 is a sectional view corresponding to FIG. 1 at the edge of the blanket cylinder, FIGS. 3, 4 and 5. The figure is a schematic view showing the fixing process, and FIG. 6 is a sectional view showing another embodiment of the tightening shaft. 1...Rubber blanket, 2...Rubber body, 3...
...front edge, 4...reinforcement strip, 5...rear edge, 6,
7...Tightening shaft, 8...Recess, 9...Body slit,
10... Eccentric bearing ring, 11... Side wall, 12...
...Accommodation slit, 13, 14...Side wall, 15...
Stoppa, 16...Hollow chamber, 17...Limiting wall, 1
8... Accommodation slit, 19... Groove, 20... Hollow chamber, 21... Outer restriction wall, 22... Body, 23...
…protrusion.

Claims (1)

[Scope of Claims] 1. A method for fixing a rubber blanket to a blanket cylinder of an offset printing machine, comprising a reinforcing strip immovably attached substantially perpendicular to the side edge of the rubber blanket. inserting the front edge of the butt into a narrow barrel slit extending along the generatrix of the rubber barrel and widening inwardly into a recess, up to a stop in a first tightening member disposed in the barrel slit; by positioning the front edge of the blanket parallel to the blanket cylinder axis, and by positioning the unreinforced rear edge of the blanket by
In a type in which the blanket is fixed by a second tightening member that is operated separately from the first tightening member, the rubber blanket is rotated at approximately the same circumferential speed after the front edge is fixed. Then, with another cylinder attached to the blanket cylinder, a pressure corresponding to the pressure during printing is applied, and the blanket is rolled around the blanket cylinder while being stretched along the peripheral surface of the blanket cylinder, and then the rear edge of the rubber blanket is wrapped around the blanket cylinder. Loosely insert it into the tightening member of the rubber cylinder at the position obtained by the extension,
A method for fixing a rubber blanket to a blanket cylinder of an offset printing press, characterized in that the rubber blanket is then pushed completely into the recess and fixed to the blanket cylinder by a second clamping member. 2. A device for fixing a rubber blanket to a blanket cylinder of an offset printing press, comprising a narrow cylinder slit extending along the generatrix of said blanket cylinder and expanding inwardly into a recess; Two separately operated clamping members are provided for the front and rear edges of the rubber blanket, each clamping member having a receiving slit for each one end edge of the rubber blanket. In a version in which the receiving slot 18 for the rear edge 5 of the rubber blanket has a tensioning shaft and in which the bottom of the receiving slot for the front edge of the rubber blanket forms a stop, the receiving slot 18 for the rear rubber blanket edge 7 and which is arranged asymmetrically and furthermore has a receiving slot 18 of the clamping shaft 7 for the rear edge 5 of the rubber blanket, and between the rubber cylinder 2 there is a tongue-like groove. A hollow chamber 20 is provided, the cylindrical limiting walls of which are separated from each other by the thickness of the rubber blanket 1, and the tightening shaft 7 for the rear edge 5 of the rubber blanket is in a relaxed position. In some cases, a groove 19 is provided in the blanket cylinder 2 which is an extension of the receiving slot 18 of the clamping shaft 7, the depth of which corresponds to the rear end section of the rubber blanket 1 into which it is to be introduced. The tightening shaft 7 for the rear edge 5 of the rubber blanket is longer than the maximum length.
is held at both ends in a bearing ring 10, which bearing ring is arranged eccentrically adjustable in order to reduce the mutual spacing of the two cylindrical limiting walls of said hollow chamber. Characterized by
A device that fixes a rubber blanket to the blanket cylinder of an offset printing machine.