Device and method for compensating for press differences

Abstract

The invention relates to a device, particularly for use in printing press construction, comprising at least two rollers (1, 2) rolling against each other, wherein at least one first roller (1) has at least two journals (3, 4), the first roller (1) being designed as a hollow roller. According to the invention, at least one of the two journals (3, 4) is inserted into the first roller (1), the journal (3) having at least two different diameters (5, 6). Furthermore, the invention also includes a method for compensating for pressure differences between rollers (1, 2).

Description

[0001] The invention relates to a device, particularly in printing press construction, comprising at least two rollers rolling against each other, wherein at least one first roller has at least two pins, wherein the first roller is designed as a hollow roller, and to a related method.

[0002] When two axially parallel rollers are pressed together, the rollers deform under line pressure along their central axes in such a way that the distance between the centers of the rollers is smaller at the roller edges than at the center. The inhomogeneity of the pressure profile leads to inconsistent contact pressure and transmission behavior across the width of the rollers.

[0003] From CH 525 090 A, a method for influencing the printed image produced by a gravure printing cylinder and a device for carrying out the method are known. A bending moment is exerted on the gravure printing cylinder, bending its axis, whereby the position, length and maximum deflection of the bending line are adapted to the desired change in the printed image.

[0004] A replaceable roller is known from WO 86 / 05447 A1. The roller body is hollow and cylindrical, and coated with an elastic material. The bearing journals for clamping the roller are detachably clamped inside the roller body. For this purpose, clamping elements that can be locked from the outside are used. These advantageously consist of elastic rings that can be pressed together by means of a clamping sleeve, thereby pressing forcefully against the inner wall of the roller body. The bearing journals thus secured can be reused multiple times, while the roller body, with a worn or damaged coating, can be discarded as a consumable item.

[0005] The purpose of the invention is therefore to provide a device and a method for compensating for pressure differences between rollers.

[0006] The SolutionThe device, in conjunction with the preamble of claim 1, is characterized in that at least one of the two journals is inserted into the first roller, wherein one journal has at least two different diameters, and the position of the journal in the hollow roller is defined by an insertion depth, the insertion depth being variable. Thus, to compensate for the uneven distribution of pressure between the rollers, it is proposed to change the shape of the bending curve by inserting the journals of the roller deeper into the hollow roller. Preferably, the insertion depth is 30 mm, 60 mm, 90 mm, or particularly preferably 120 mm.

[0007] According to the further development, at least part of the lateral surface of the largest diameter of one of the pins is designed as a contact surface. The contact surface is preferably cylindrical.

[0008] Advantageously, one of the pins is firmly connected to the roller via the contact surface. This firm connection can be achieved, for example, by screwing, welding, or gluing. A bolt-and-pin connection or a suitable fit is also conceivable. The firm connection can also be made at a single point. The contact surface should be of an appropriate size depending on the connection.

[0009] According to the further development, the journals are designed to have different cross-sections, with the journal sections having different diameters and lengths depending on the insertion depth. The journal extends beyond the edge of the roller to allow for roller support. Therefore, the overall length of the journal must be adapted to the insertion depth. Consequently, the further the journal is inserted into the hollow roller, the greater its overall length. The sections of the journal that do not form the contact surface have their own deflection curve. The contact surface between the journal and the hollow roller should be wide enough to fully transfer the bending moment acting on the roller during rolling, while maintaining the component strength. Furthermore, the contact surface should be dimensioned such that the roller's stiffness is not proportionally increased.Various designs of the pin are conceivable, as can be seen, for example, in the figures. The pins can also have a bore, preferably a blind hole. The pins can also have several sections with different diameters; however, at least the portions of the pin's outer surface with the largest diameter must be designed as contact surfaces. The portion of the pin with the largest diameter that forms the contact surface with the first roller can also have grooves, so that only parts of the largest diameter are in contact with the first roller.

[0010] According to the further development, at least one of the rollers is provided to have an additional elastic layer, wherein this elastic layer is a coating or a lift. The elastic layer can be made of a compliant material, such as rubber.

[0011] The SolutionThe method for compensating for pressure differences, in conjunction with the preamble of claim 6, is characterized in that the resulting deflection curve is influenced by changing the insertion depth of the journals or by changing the stiffness of the journal and / or the roller. The stiffness of the journal is in a compatible relationship to the stiffness of the roller. The effect of the insertion depth increases disproportionately.

[0012] Further training stipulates that the pressure between the two rollers in the roller center and the roller edges will be changed.

[0013] According to further training, it is intended that the deflection curve is influenced by changing the area moments of inertia and / or the material of the pin.

[0014] According to the further development plan, the natural frequency of the rollers is to be influenced. The greater the insertion depth of the journal, the lower the natural frequency of the roller-journal assembly.

[0015] Between the edges of the rollers and the journals, a mechanical arrangement of two bending springs is created on both sides, exhibiting greater compliance with increasing insertion depth. In this way, the central bending line of one roller is partially decoupled from the bending line of the other roller along the contact line at the edges. A portion of the deformation energy induced by the contact pressure is stored in the deformation of the journals. Consequently, a flatter bending line profile is created at the contact line of both rollers, resulting in lower edge pressure. This reduces the pressure difference between the roller center and the roller edges. These properties allow for a reduction in edge lubrication, which is inherent in printing press construction, for example. The described decoupling of the two bending lines can be moderated using the following parameters: Insertion depth of the journal into the hollow roller, area moment of inertia of the journal cross-section (outer-inner diameter of the journal) or section-by-section introduction of additional compliance areas.

[0016] The invention is particularly suitable for improving the print quality in printing presses, especially offset printing presses, since it offers a solution for compensating for pressure differences between rollers, e.g., between the plate cylinder and the dampening roller. The roller with at least one inserted pin could, for example, be the dampening roller and / or anilox roller.

[0017] The drawings schematically show a device according to the invention: Fig. 1 shows rollers rolling against each other with at least two journals. Fig. 2 shows a journal inserted into a hollow roller. Fig. 3 shows a journal with a bore inserted into a hollow roller. Fig. 4 shows a journal with a bore and several different diameters inserted into a hollow roller. Fig. 5 shows a side view of a hollow roller with journals.

[0018] Figure 1Figure 1 shows two rollers 1 and 2 rolling against each other. The first roller 1 is designed as a hollow roller. The first roller 1 has two journals 3 and 4, with at least one of the journals 3 and 4 being inserted into the first roller 1. The second roller 2 can be designed as either a hollow roller or a solid roller. If the second roller 2 is designed as a hollow roller, it can have one or more journals that can be inserted into the hollow roller. At least one of the rollers 1 and 2 additionally has an elastic layer 8, which can be a coating or a lift. The journal 3 and 4 can be designed differently, as shown, for example, in the following illustrations. Figures 2 to 5 shown here in Figure 1The depicted journal 3 has at least two different diameters 5 and 6. At least part of the outer surface of the largest diameter 5 of the journal 3 is designed as a contact surface 7. The journal 3 is rigidly connected to the first roller 1 via the contact surface 7. The journal projects beyond the end face of the roller 1 to allow for roller support. The position of the journal 3 in the first roller 1 is defined by the insertion depth a, which is variable. The length b of the largest diameter 5 of the journal 3 depends on the type of rigid connection between the journal 3 and the first roller 1 to ensure a minimum contact area. The length c of the remaining journal 3 depends accordingly on the insertion depth a and the chosen support.

[0019] Figure 2 shows a more detailed view of an inserted pin 3 in a first roller 1 designed as a hollow roller. Figure 1The journal 3 projects beyond the end face of the hollow roller with a portion of its smaller diameter 6, serving as a bearing for the roller 1. The length c of this portion of the journal must be adapted to the chosen bearing arrangement, the insertion depth a of the journal 3, and the length b of the largest diameter 5 of the journal 3. The position of the journal 3 within the roller 1 is defined by the insertion depth a. At least a portion of the largest diameter 5 of the journal 3 forms a contact surface 7 with the first roller 1. The journal 3 is firmly connected to the roller 1 via this contact surface 7.

[0020] Figure 3 The figure also shows a first roller 1 designed as a hollow roller with an inserted pin 3. In contrast to Figure 2 This inserted pin 3 has a bore 9. The bending stiffness of the pin 3 and the area moment of inertia can be adjusted by means of this bore 9. The bore is designed as a blind bore.

[0021] Figure 4 shows how the Figures 2 and 3 a first roller 1 designed as a hollow roller with an inserted pin 3. This pin 3, however, has at least one further section with a further diameter.

[0022] Figure 5 Figure 1 shows a side view of a first roller 1 designed as a hollow roller with a journal 3. The journal 3 has at least two different diameters 5, 6. The largest diameter 5 of the journal 3, for example, has grooves, so that parts of the outer surface of the journal 3 form a contact surface 7 with the hollow roller.

[0023] The in Figures 2 to 5 The described embodiment can also be implemented analogously for pin 4 or for both pins 3 and 4. Reference symbol list

[0024] 1. First roller 2. Second roller 3. First pin / one pin 4. Further pin / other pin 5. Largest diameter 6. Diameter 7. Contact surface 8. Elastic layer 9. Bore a) Insertion depth b) First length / length of the largest diameter of the pin c) Second length / length of the remaining pin

Claims

1. A device, in particular in printing press manufacturing, comprising at least two rollers (1, 2) rolling on each other, wherein at least a first roller (1) has at least two journals (3, 4), wherein the first roller (1) is formed as hollow roller, wherein at least one of the two journals (3, 4) is inserted in the first roller (1), wherein the one journal (3) has at least two different diameters (5, 6), characterized in that the position of the one journal (3) in the hollow roller is defined via an insertion depth (a), wherein the insertion depth (a) is variable.

2. The device according to claim 1, wherein at least parts of the jacket surface of the largest diameter (5) of the one journal (3) is formed as contact surface (7).

3. The device according to claim 2, wherein the one journal (3) is firmly connected to the first roller (1) via the contact surface (7).

4. The device according to at least one of claims 1 to 3, wherein the journals have different cross sections, wherein the parts of the journal with the different diameters (5, 6) have different lengths (b, c), wherein the different lengths (b, c) depend on the insertion depth (a).

5. The device according to at least one of the preceding claims, wherein at least one of the rollers (1, 2) additionally has an elastic layer (8), wherein the elastic layer is a coating or an application.

6. A method for compensating for press differences between two rollers (1, 2), in particular in the printing press manufacturing, with a device according to claim 1, wherein by changing an insertion depth (a) of the journals (3, 4) or by changing the stiffness of the journal and / or of the roller the resulting bending line is influenced.

7. The method according to claim 6, wherein the pressing between the two rollers (1, 2) is changed in the roller center and the roller edges.

8. The method according to at least one of the preceding claims, wherein by changing the area moments of inertia and / or the material of the journal (3, 4) the bending line is influenced.

9. The method according to at least one of the preceding claims, wherein the natural frequency of the combination of roller (1) and journal (3, 4) is influenced.

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