EP0492138B1 - Quick clamping device - Google Patents

Abstract

A quick-action clamping device for fastening a printing plate on a plate cylinder in a printing machine by a fixed clamping bar and a displaceable clamping bar which are able to be brought into a clamping position and a plate-changing position, respectively, includes a spring device for resiliently pressing the displaceable clamping bar into the clamping position with a holding force for clamping a printing plate between the displaceable clamping bar and the fixed clamping bar, and at least one re-set element for returning the displaceable clamping bar to the plate-changing position against the holding force.

Description

The invention relates to a quick clamping device for fastening printing plates in printing presses by means of a fixed upper clamping bar and a displaceable lower clamping bar, which can be moved into a clamping position and a plate changing position.

Such a quick clamping device is known from DE-OS 34 01 351, in which the lower clamping strip is pressed against the upper clamping strip by means of an eccentric while clamping the pressure plate. By turning the eccentric in the opposite direction, the lower clamping strip is pulled back and the plate can be changed.

With such quick clamping devices, it is necessary that the printer for the plate change actuate the eccentric by means of a tool, for example using a mandrel. When clamping the plate, no defined clamping force can be set and the upper bar is bent open indefinitely. As a result, an exact, reproducible plate position is not achieved.

From CH-A 454 912 a device for fastening and tensioning a printing plate is known. A control element provided acts directly on an axially displaceable carrier of a lower terminal block.

A device for clamping printing plates is known from US Pat. No. 4,250,810. Control elements and reset elements are not provided.

From DE-OS 26 06 773 a device for fastening a printing plate on a cylinder of a printing press by means of a fixed upper clamping bar and a radially displaceable lower clamping bar is known. In this case, the lower clamping strip can be pressed into a clamping position by spring elements and can be brought into a plate changing position by means of the restoring elements provided against the holding force of the spring elements.

The invention has for its object to make a quick clamping device available, in which a defined clamping force for plate clamping can be achieved and which is well suited for automatic plate clamping.

The object is achieved by the characterizing features of claim 1.

The advantages of the invention are that a defined clamping force for clamping the pressure plate is achieved by the force of the spring element and this clamping force is ensured even if the power supply to the actuating element fails. Due to the defined clamping force, an exact position is achieved, whereby the fixed clamping strip does not bend, or only slightly, but then always reproducibly. The plate can be clamped at the push of a button. The printer therefore no longer needs any tools to insert the plate. An automatic clamping in cooperation with an automatic plate feed is also conceivable.
One embodiment provides that the quick-clamping device is designed such that the restoring element is at least one rocker that can be actuated by at least one adjusting element, which is supported on the cylinder housing and is operatively connected with its ends to the lower terminal strip and the adjusting element. This control element can be designed to be automatically actuated, for example in the form of a pneumatic or hydraulic control element such as one or more pneumatic cylinders or hydraulic cylinders. The rocker can be a continuous element over the length of the terminal strip, which engages with several finger-like ends in the terminal strip and is actuated by one or more adjusting elements. However, several rockers, each with one control element, can also be provided.

A further embodiment provides that the restoring element is at least one lever which can be actuated by adjusting elements and which is supported at one end on a support surface which is firmly connected to the cylinder housing, with a short lever arm with the lower terminal block and with a long lever arm with the actuator in operative connection.

There are various ways of making the operative connection between the actuating elements and the lever. It is possible that the lever engages in an opening in the lower terminal block. However, the operative connection can also be designed in such a way that the lever engages with its short lever arm between the spring element and the lower terminal block and that return springs, which are firmly connected to the cylinder housing, press the lower terminal block against the lever. The return springs must be designed to overcome the friction and gravity of the terminal block.

Another possibility of the operative connection between the restoring elements and the adjusting element is that the adjusting element is arranged between the lever and the one end of a rocker which is supported on the cylinder housing and engages with its end opposite the adjusting element in a cavity in the lower terminal strip and that the lever engages with its short lever arm between the spring element and the lower terminal strip.

The particular advantage of this embodiment is that multiple power amplification is possible in a very small space. The control element acts on both the lever and the rocker, which means that the power transmissions from the rocker and lever add up to the sliding lower terminal block. If, for example, the force of the actuating element is doubled by the lever and simply passed on through the rocker, this construction leads to the displaceable lower terminal strip being actuated with three times the force of the actuating element.

It must be emphasized that, as with the rocker, different configurations of the lever are possible. The lever can be a continuous element over the length of the terminal block, since with several finger-like ends it is supported on a support surface which is firmly connected to the cylinder housing and which is actuated on the long lever arm by one or more adjusting elements. However, it is also possible to arrange a plurality of levers along the length of the displaceable lower terminal strip, each of which is assigned an adjusting element. With the combination of rocker and lever, each of these elements can be designed in one way or another. All that is required is that each control element acts on both the lever and the rocker.

The lever can be held in a fixed position in that a locking pin protrudes from the support surface, which engages in a bore of the lever, with sufficient play being provided for the mobility of the lever.

A very exact positioning of the pressure plate is achieved in that a pressure spring is inserted between a carrier connected to the cylinder housing and the displaceable lower clamping bar, which ensures a clean contact of the clamping bar with the cylinder housing in the direction of the clamped pressure plate. In this way it is prevented that the exact position of the pressure plate in contact with the registration plate is deteriorated when the pressure plate is clamped and clamped by a play between the displaceable lower terminal strip and the cylinder housing.

The exact insertion of the pressure plate is possible in that one of the two clamping bars carries register bolts for the precise insertion of the pressure plates, which are opposite recesses for receiving the register bolts in the clamping position on the other terminal block. This exact location can be reproduced at any time. If the pressure plate is U-shaped Has recesses, the registration bolts do not need to move out of the recesses for inserting the pressure plate.

Another embodiment provides that the clamping surfaces of the terminal strips are coated with a material that has a high coefficient of friction. Tungsten carbide cobalt is particularly suitable for such a coating. An embodiment is also possible in which one of the clamping surfaces of the clamping strips is designed as a smooth metal surface and the other is provided with a cross-section. With the aid of such clamping surfaces, the plate is held in place without the plate being deformed in the clamping area. In this way it is easy to use multiple plates.

In particular for automatic insertion of the plates, it is expedient that at least two sensors are arranged which detect whether an inserted plate is in the desired position.

If the quick clamping device is used in printing machines with a large printing format, the other end of the printing plate must be held and clamped by a clamping and tensioning device. For such machines, the quick clamping device is particularly well suited due to its exact fixing of the pressure plate with high forces, since a large clamping force is possible through the clamping device. This in turn serves to fix the printing plate in the correct position in order to achieve a register-containing print.

Fig. 1

einen radialen Schnitt durch den Plattenzylinder mit der erfindungsgemäßen Vorrichtung,

Fig. 2

einen Schnitt in axialer Richtung durch die Schnellklemmvorrichtung,

Fig. 3

einen radialen Schnitt durch eine Weiterbildung mit Kraftverstärkung,

Fig. 4

eine weitere Ausführungsform und

Fig. 5

eine Weiterbildung mit kompakter hoher Kraftverstärkung

Embodiments of the invention are shown in the drawing. Show it:

Fig. 1

a radial section through the plate cylinder with the device according to the invention,

Fig. 2

a section in the axial direction through the quick release device,

Fig. 3

a radial section through a training with power amplification,

Fig. 4

a further embodiment and

Fig. 5

further training with compact high power amplification

Figure 1 shows a section that is made so that it goes through the quick-clamping device in the region of a spring element 3, a return element 4 and an actuating element 5. The upper terminal strip 1 is fixed, for example it is arranged on a support 26 which is connected to the cylinder housing 6 by means of a fastening screw 12. To clamp a plate 11, the upper terminal block 1 interacts with a lower terminal block 2, which is designed to be displaceable. One or more spring elements 3 are arranged between the cylinder housing 6 and the displaceable lower clamping bar 2 and press the clamping bar 2 with the desired clamping force against the upper clamping bar 1. By means of one or more restoring elements 4, the lower clamping bar 2 is overcome while overcoming the force of the spring elements 3 brought into a plate changing position, in this plate changing position there is a sufficient receiving gap between the clamping surfaces 9 and 10 of the terminal strips 1 and 2. Registration bolts 7 can be provided in the Corresponding U-shaped punchings of the printing plates 11 can be inserted with a precise fit and thus always guarantee the same exact printing plate position. The register bolts 7 are opposite recesses 8 as a space for the register bolts. If the restoring element 4 - which, as shown in FIG. 2, can be a plurality of elements arranged in the axial direction - releases the lower, displaceable clamping strip 2, the lower clamping strip 2 is pressed against the force of the spring elements 3 by clamping the pressure plate 11 upper terminal strip 1 pressed.

In this exemplary embodiment, the restoring element is designed as a plurality of rockers 4, which have their fulcrum on the cylinder housing 6, with one end engaging in a cavity 13 in the lower terminal strip 2 and with the other end interacting with an adjusting element 5 in each case. By actuating the actuating elements 5, the rockers 4 press the displaceable lower terminal strip 2 downward and release the terminal strip 2 by resetting the actuating elements 5, as a result of which the plate tension takes place in the manner described above by means of the spring elements 3. The adjusting elements 5 can be designed as automatically actuating adjusting elements, for example as a pneumatic cylinder or hydraulic cylinder.

In all of the exemplary embodiments, the clamping surfaces 9, 10 of the clamping strips 1, 2 can be coated with a material which has a high coefficient of friction, or a smooth metal surface is provided on one side and a cross-ground surface is provided on the other side. Two sensors, not shown, can be provided to monitor whether the pressure plate is in its target position.

FIG. 2 shows the quick-clamping device in the section II-II in the axial direction, the quick-clamping device being in the clamping position without pinching a plate. Here the fixed upper terminal strip 1 and the displaceable lower terminal strip 2, cut in the region of the center line of the lower terminal strip 2, can be seen. Depending on the length of the terminal strip, a number of spring elements 3, return elements 4 and fastening screws 12 are provided. Appropriately, two register bolts 7 are arranged at a sufficient distance in a quick clamping device. The following exemplary embodiments can also have a larger number of individual elements which are arranged distributed over the length of the terminal strips.

Fig. 3 shows a section as in Fig. 1, but through an embodiment with force amplification by a lever 4 '. In this exemplary embodiment, a lever 4 'which can be actuated by the adjusting element serves as the restoring element. The actuating element 5 is mounted in the cylinder housing 6, the actuating member being directed in the direction of the cylinder interior. The lever 4 ′ engages in an opening 18 in the displaceable lower terminal strip 2, a spherical pressure surface 19 being arranged in the direction of the spring element 3. The end of the lever 4 ′ opposite the actuating element 5 is supported on a support surface 14 which is firmly connected to the cylinder housing 6. In the exemplary embodiment, it is arranged on a carrier 26 which is connected to the cylinder housing 6 by means of a fastening screw 12. A locking pin 17 protrudes from the support surface 14 and engages in a bore in the lever 4 ', with sufficient play being provided for the mobility of the lever 4'.

The function is as follows:
If the actuating element 5, for example a pneumatic cylinder, without compressed air, the spring element 3 presses the displaceable lower terminal block 2 against the full force fixed upper terminal block 1 and thereby fixes a pressure plate 11. Registration bolts 7 and recesses 8 have the function already described. To release the pressure plate 11, the actuating element 5 is actuated, which, via the lever 4 ′, presses the lower clamping bar 2 with its part arranged below the opening 18 against the spring element 3 and thereby compresses it. Simultaneously with this compression of the spring 3, the terminal strip 2 is inevitably moved with the release of the pressure plate 11. In the example shown, the lever 4 ', measured from the support surface 14, has a short lever arm 15 to the spherical pressure surface 19 and a long lever arm 16 extends to the actuating element 5. The long lever arm 16 has twice the length of the lever arm 15, whereby the force of the actuator 5 is doubled. Of course, the leverage ratios can be chosen at will.

Figure 4 shows a further embodiment with force amplification. The parts with the same reference numerals as the parts described so far have the same function. In contrast to the exemplary embodiment according to FIG. 3, in this exemplary embodiment the lever 4 'with its short lever arm 15 is arranged between the spring element 3 and the lower terminal strip 2. When actuating the actuating element 5, the spring element 3 is compressed and the spherical pressure surface 20 withdraws. Return springs 4 ″, which are firmly connected to the cylinder housing 6 and serve in the return direction, therefore in the direction of the spring element 3, are used to move the lower terminal block 2. In the illustrated embodiment, a holder 21 is inserted in at least two recesses 22 of the lower terminal strip 2, which is fastened to the carrier 26 by screws 23. The holder 21 is open at the bottom and a return spring 4 ″ is arranged so that it presses on the lower surface of the recess 22. This Return springs 4 '' must be designed so that they overcome the friction and gravity of the terminal block and let it follow the receding lever 4 '. This increases the gap between the terminal strips, an old pressure plate 11 can be removed and a new pressure plate can be inserted. A withdrawal of the actuating element 5 has the result that the spring element 3 presses the lower clamping strip 2 back into its clamping position while compressing the return springs 4 ″.

In this embodiment, a pressure spring 24 is inserted between a carrier 26 connected to the cylinder housing 6 and the displaceable lower terminal strip 2. To accommodate the pressure spring 24, the displaceable lower clamping strip 2 is provided with a blind hole 25 which is open in the direction of the carrier 26. The displaceable lower clamping strip 2 is thereby pressed by the carrier 26 in the direction of the cylinder housing 6, that is to say in the direction of the clamped pressure plate. This additional device is used for a clean contact of the terminal block 2 with the cylinder housing 6. This prevents play which could lead to an inaccurate position of the pressure plate. The pressure spring 24 can also be inserted in the other exemplary embodiments.

FIG. 5 shows a further development with compact, high force amplification. In principle, this is a combination of the rocker 4 explained in FIG. 1 with the lever 4 'explained in FIG. 3. The purpose is to take advantage of the counterforce that the control element 5 exerts on the cylinder housing 6 in the embodiment according to FIG. 3 so that an additional force is applied to the displaceable lower terminal strip 2. For this purpose, a lever 4 'is arranged in the manner already described in FIG. 3, the actuating element 5 being connected directly to the lever 4' and to its adjustable part at the end of the long lever arm 16 presses on a rocker 4, which is arranged as described in Figure 1. When actuating the actuating element 5, the rocker 4 in turn presses on the corresponding cavity 13 in the lower terminal strip 2, which thereby moves downward. At the same time, the actuating element 5 actuates the lever 4 'in such a way that the spring element 3 is pressed together. Thus, the spring element 3 is pressed together by the lever 4 'and the lower terminal block 2 is pressed down by the rocker 4. In the case of double power amplification of the lever 4 'and simple power transmission by means of the rocker 4, these forces add up to a restoring force on the lower clamping strip 2, which corresponds to three times the force of the actuating element 5. Of course, the travel of the actuating element 5 must be chosen to be correspondingly large, since with triple force amplification, a triple travel of the actuating element 5 is also required in order to achieve a corresponding reset of the lower terminal strip 2. Otherwise, the parts and functions correspond to those already described above.

Also in the exemplary embodiments according to FIGS. 3 to 5, the elements are expediently arranged in a larger number distributed over the length of the terminal strip, so that clamping and releasing of the pressure plate takes place uniformly over the entire terminal strip.

REFERENCE SIGN LIST

1

(fixed) upper terminal block

2nd

(sliding) lower terminal block

3rd

Spring element

4.4'4 ''

Reset elements

4th

Seesaw

4 '

lever

4 ''

Return spring

5

Actuator

6

Cylinder housing

7

Registration bolt

8th

Recesses

9

Clamping surface

10th

Clamping surface

11

printing plate

12th

Fastening screw

13

Excavation

14

Support surface

15

short lever arm

16

long lever arm

17th

Locking pin

18th

Breakthrough

19th

convex pressure surface

20th

convex pressure surface

21

bracket

22

Recess

23

screw

24th

Pressure spring

25th

Blind hole

26

carrier

Claims (15)

1. Quick-acting clamping device for attaching a printing plate on a cylinder of a printing machine by means of a fixed upper clamping rail (1) and a radially displaceable lower clamping rail (2) which can be brought into a clamping position and a plate-exchange position, the lower clamping rail (2) being pressed into the clamping position by spring elements (3) with the holding force for printing plates and being able to be brought into the plate-exchange position by restoring elements (4, 4') counter to the holding force of the spring elements (3), characterized in that at least one restoring element (4, 4') is provided, which is designed as a rocker or lever and is supported pivotably on the cylinder housing (6) or on a supporting surface (14) which is firmly connected to the cylinder housing, in that the restoring element or elements (4, 4') can be actuated by means of at least one adjusting element (5) which can be acted upon by an actuating medium.
2. Quick-acting clamping device according to Claim 1, characterized in that the restoring element designed as a rocker (4) can be actuated by at least one adjusting element (5), in that the rocker (4) is operatively connected by its ends to the lower clamping rail (2) and the adjusting element (5).
3. Quick-acting clamping device according to Claim 1, characterized in that the restoring element designed as a lever (4') can be actuated by at least one adjusting element (5), and in that the lever (4') is operatively connected to the lower clamping rail (2) by means of a short lever arm (15) and to the adjusting element (5) by means of a long lever arm (16).
4. Quick-acting clamping device according to Claim 3, characterized in that the lever (4') is mounted in an opening (18) in the lower clamping rail (2).
5. Quick-acting clamping device according to Claim 3, characterized in that the lever (4') is arranged with its short lever arm (15) between the spring element (3) and the lower clamping rail (2), and in that there are provided restoring springs (4'') which are firmly connected to the cylinder housing (6) and press the lower clamping rail (2) against the lever (4'), in that a force of the restoring springs (4'') is designed such that it is greater than a force of the clamping rail (2) raised by friction and the force of gravity.
6. Quick-acting clamping device according to Claim 3, characterized in that the adjusting element (5) is arranged between the lever (4') and the one end of a rocker (4) which is supported on the cylinder housing (6) and engages with its end located opposite the adjusting element (5) in a hollow (13) in the lower clamping rail (2), and in that the lever (4') engages with its short lever arm (15) between the spring element (3) and the lower clamping rail (2).
7. Quick-acting clamping device according to one of Claims 3 to 6, characterized in that a retaining pin (17) protrudes out of the supporting surface (14) and engages in a bore in the lever (4'), sufficient clearance being provided for the mobility of the lever (4').
8. Quick-acting clamping device according to one or more of Claims 1 to 7, characterized in that a contact-pressure spring (24) is inserted between a carrier (26), connected to the cylinder housing (6), and the displaceable lower clamping rail (2) and ensures clean contact of the clamping rail (2) against the cylinder housing (6) in the direction of the tensioned printing plate (11).
9. Quick-acting clamping device according to one or more of Claims 1 to 8, characterized in that the adjusting element (5) is a pneumatic adjusting element.
10. Quick-acting clamping device according to one or more of Claims 1 to 8, characterized in that the adjusting element (5) is a hydraulic adjusting element.
11. Quick-acting clamping device according to one or more of Claims 1 to 10, characterized in that one of the clamping rails (1, 2) bears register pins (7) for the positionally precise insertion of the printing plates, opposite which there are recesses (8) located on the other clamping rail (2, 1).
12. Quick-acting clamping device according to one or more of Claims 1 to 11, characterized in that the clamping faces (9, 10) of the clamping rails (1, 2) are coated with a material which has a high coefficient of friction.
13. Quick-acting clamping device according to Claim 12, characterized in that the clamping faces are coated with tungsten carbide cobalt.
14. Quick-acting clamping device according to one or more of Claims 1 to 11, characterized in that one of the clamping faces (9, 10) of the clamping rails (1, 2) is designed as a smooth metal face, and the other is provided with a cross-grinding.
15. Quick-acting clamping device according to one or more of Claims 1 to 14, characterized in that there are arranged at least two sensors which record whether there is a plate inserted in the intended position.

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