DRUM SUPPORT ASSEMBLY FOR A PRINTING MACHINE AND PRINTING MACHINE

Abstract

A drum support assembly (30, 32) for a printing machine is presented. It comprises a drum support body (30a, 32a) having a bearing interface (30b, 32b) for a drum, a lower guide (34) supporting the drum support body (30a, 32a) at a lower end thereof, and an upper guide (36) supporting the drum support body (30a, 32a) at an upper end thereof. Additionally, a pre-tensioning unit (50) is provided pre-tensioning the drum support body (30a, 32a) against the lower guide (34) and/or the upper guide (36). Furthermore, a printing machine is described, comprising a drum and a drum support assembly (30, 32) as described above.

Claims

1. A drum support assembly for a printing machine, the drum support assembly comprising: a drum support body having a bearing interface for a drum, a lower guide supporting the drum support body at a lower end thereof, an upper guide supporting the drum support body at an upper end thereof, and a pre-tensioning unit for pre-tensioning the drum support body against the lower guide and/or the upper guide, wherein the pre-tensioning unit comprises a pressure piece and a spring element, wherein the spring element is adapted for applying a spring force on the pressure piece, and wherein the pressure piece is mounted on the drum support body and frictionally engages the lower guide and/or the upper guide, or wherein the pressure piece is mounted on one of the upper guide and the lower guide and frictionally engages the drum support body.

2. The drum support assembly according to claim 1, wherein the pre-tensioning unit comprises a pre-tensioning force variation unit being adapted to adjust the pre-tensioning force to a pre-defined value.

3. The drum support assembly according to claim 1, wherein the pre-tensioning unit comprises an active system.

4. The drum support assembly according to claim 1, wherein the lower guide comprises a lower rail, on which the lower end of the drum support body is supported.

5. The drum support assembly according to claim 4, wherein a low friction material is interposed between the lower rail and the drum support body.

6. The drum support assembly according to claim 4, wherein the lower rail has a substantially triangular cross section, when regarded along a main direction of the lower rail, wherein the drum support body is supported on both triangle side surfaces of the cross section.

7. The drum support assembly according to claim 1, wherein the upper guide comprises an upper rail, on which the upper end of the drum support body is supported.

8. The drum support assembly according to claim 7, wherein a low friction material is interposed between the upper rail and the drum support body.

9. The drum support assembly according to claim 7, wherein the upper rail has a substantially triangular cross section, when regarded along a main direction of the upper rail, wherein the drum support body is supported on both triangle side surfaces of the cross section.

10. The drum support assembly according to claim 9, wherein the pre-tensioning unit comprises a pre-tensioning force variation unit being adapted to adjust the pre-tensioning force to a pre-defined value, and wherein a contact surface of the drum support body being in contact with the upper rail comprises a first contact surface portion being provided on the drum support body and a second contact surface portion being provided on the pressure piece, wherein the first contact surface portion and the second contact surface portion are in contact with one triangle side surface respectively.

11. The drum support assembly according to claim 1, wherein the drum support body is made of cast iron.

12. A printing machine, especially a flexographic printing machine, comprising: a drum, and the drum support assembly according to claim 1, wherein the drum is supported in the drum support assembly via the bearing interface.

13. The printing machine according to claim 12, wherein the drum is a central impression drum, a cliché drum or an ink application drum.

14. The printing machine according to claim 12, further comprising: an actuation unit being coupled to the drum support assembly and being adapted for moving the drum support body relative to the upper guide and the lower guide.

Description

[0029] The invention will now be explained with reference to an embodiment which is shown in the attached drawings. In the drawings,

[0030] FIG. 1 shows a printing machine according to the invention comprising drum support assemblies according to the invention,

[0031] FIG. 2 shows the functional principle of the printing machine according to FIG. 1,

[0032] FIG. 3 shows two drum support assemblies of the printing machine of FIG. 1,

[0033] FIG. 4 shows section IV-IV of FIG. 3,

[0034] FIG. 5 shows detail V of FIG. 4, and

[0035] FIG. 6 shows detail VI of FIG. 4.

[0036] FIG. 1 shows a printing machine 10, which is a flexographic printing machine in the examples shown.

[0037] It comprises a web feeding unit 12, where a web of carrier material may be stored before the printing process takes place, a printing unit 14 adapted for printing on the web of carrier material, and a storage unit 16, where printed web is stored after the printing process.

[0038] The printing machine 10 also has a dryer unit 18, which is adapted for drying printed web of carrier material after the printing process.

[0039] Details of the printing unit 14 may be seen in FIG. 2.

[0040] The printing unit 14 comprises an ink chamber 20, where ink to be applied to a web 22 of support material is stored.

[0041] In a first step of the printing process ink is provided to an ink application drum 24, which may also be called an anilox roller. On the outer circumference of this drum a plurality of recesses are provided, which are designed such that they can receive an amount of ink adapted to a print job.

[0042] On the side of the ink application drum 24 opposing the ink chamber 20 a cliché drum 26 is provided. On the cliché drum 26 a printing plate is mounted. The printing plate is made of rubber or polymer material and comprises a positive mirrored master of the required image as a 3D relief. The image areas are raised with respect to the non-image areas.

[0043] In operation the ink application drum 24 applies ink to the raised areas of the cliché drum 26 in a uniform manner.

[0044] Next to the cliché drum 26, a central impression drum 28 or central impression cylinder is mounted.

[0045] The web 22 is located between the cliché drum 26 and the central impression drum 28 and both drums 26, 28 are configured such that the image is transferred from the printing plate to the web 22 during operation of the printing machine 10.

[0046] All drums 24, 26, 28 are supported inside the printing machine 10 by a respective drum support assembly.

[0047] FIG. 3 shows a drum support assembly 30 on which the cliché drum 26 is supported and a drum support assembly 32 on which the central impression drum 28 is supported. It is understood that these drum support assemblies 30, 32 have been chosen for illustrative purposes only. Other drums of the printing machine 10 are supported therein in an analogous manner.

[0048] The drums 26, 28 itself are not shown in FIG. 3. Only a shaft 26a appertaining to the cliché drum 26 and a shaft 28a appertaining to the central impression drum 28 are illustrated.

[0049] Each of the drum support assemblies 30, 32 comprises a drum support body 30a, 32a, wherein each of the drum support bodies 30a, 32a is equipped with a bearing interface 30b, 32b for a drum.

[0050] In the example shown, both drum support bodies 30a, 32a are made of cast iron.

[0051] In detail, drum support body 30a supports shaft 26a via the bearing interface 30b and drum support body 32 supports shaft 28a via bearing interface 32b.

[0052] Each of the drum support assemblies 30, 32 also comprises a lower guide 34 supporting the respective drum support body 30a, 32a at a lower end thereof and an upper guide 36 supporting the respective drum support body 30a, 32a at an upper end thereof.

[0053] In the example shown in FIG. 3 the drum support assembly 30 and the drum support assembly 32 make use of a common lower guide 34 and a common upper guide 36.

[0054] The drum support bodies 30a, 32a are able to slide on the upper guide 36 and the lower guide 34 in a direction indicated by arrow 37.

[0055] In this context, a sliding movement of the drum support body 30a is actuated by a first actuation unit 38 being coupled to the drum support assembly 30 and being adapted for moving the drum support body 30a relative to the upper guide 36 and the lower guide 34.

[0056] A sliding movement of the drum support body 32a is actuated by a second actuation unit 40 being coupled to the drum support assembly 32 and being adapted for moving the drum support body 32a relative to the upper guide 36 and the lower guide 34.

[0057] Details of the drum support assemblies 30, 32 are shown in FIGS. 4 to 6. For better readability only drum support assembly 30 is described. It is understood that the following explanations apply to drum support assembly 32 in an analogous way.

[0058] The upper guide 36 comprises an upper rail 36a, on which the upper end of the drum support body 30a is supported.

[0059] In between the upper rail 36a and the drum support body 30a a low friction material 42 is interposed.

[0060] Furthermore, the upper rail 36a has a substantially triangular cross section, when regarded along a main direction of the upper rail 36a. This can best be seen in FIG. 5.

[0061] The drum support body 30a is supported on both triangle side surfaces 44a, 44b of the cross section.

[0062] On the drum support body 30a, a first contact surface portion 46a is in frictional engagement with the triangle side surface 44a.

[0063] A second contact surface portion 46b is in frictional engagement with the triangle side surface 44b. This contact surface portion 46b is provided on a pressure piece 48, which is mounted on the drum support body 30a.

[0064] The pressure piece 48 is part of a pre-tensioning unit 50, which is adapted for pre-tensioning the drum support body 30a against the upper guide 36.

[0065] Besides the pressure piece 48 the pre-tensioning unit 50 also comprises a spring element 52, wherein the spring element 52 is adapted for applying a spring force on the pressure piece 48. Consequently, the spring element 52 generates a pre-tensioning force, which substantially equals the spring force.

[0066] The spring element 52 is fixed to the drum support body 30a by a screw 54, which can be used for varying the pre-tensioning force. Consequently, the screw 54 not only is a means for mounting the spring element 52 on the drum support body 30a but also constitutes a pre-tensioning force variation unit 56 being adapted to adjust the pre-tensioning force to a pre-defined value.

[0067] At the lower end of the drum support body 30a the lower guide 34 comprises a lower rail 34a, on which the lower end of the drum support body 30a is supported.

[0068] Also the lower rail 34a has a substantially triangular cross section, when regarded along a main direction thereof. This can be seen in FIG. 6.

[0069] The drum support body 30a is supported on both triangle side surfaces 58a, 58b of this cross section.

[0070] On the drum support body 30a respective counter surfaces are provided. A first contact surface portion 60a is in frictional engagement with the triangle side surface 58a and a second contact surface portion 60b is in frictional engagement with the triangle side surface 58b.

[0071] As has already been explained with respect to the upper guide 36, a low friction material 62 is interposed between the lower rail 34a and the drum support body 30a. In the example shown the low friction material 62 covers both triangle side surfaces 58a, 58b.