WO1992005890A1

WO1992005890A1 - Surface structure of a roller and process and device for producing it

Info

Publication number: WO1992005890A1
Application number: PCT/DE1991/000762
Authority: WO
Inventors: Gerald Sermund; Michael Wilharm; Wolfgang Boppel
Original assignee: Linotype-Hell Ag
Priority date: 1990-09-28
Filing date: 1991-09-26
Publication date: 1992-04-16
Also published as: AU8538591A; DE4102984A1

Abstract

The surface structure is generated on a roller (2) designed for application to a material. The roller (2) has recesses (22) produced by an electron beam (3) and consisting of depressions and crater walls (62) surrounding them. There is to be a plurality of recesses, the diameters and depths of which vary within a predeterminable range. Thus the distances between the recesses (22) vary in both the circumferential and longitudinal directions of the roller (2). There is provision for mutually overlapping, adjacent and spaced recesses. In the process for producing the surface structure recesses are produced on the roller surface by an electron beam and the position of the electron beam in relation to the surface is controlled in at least one spatial dimension dependently upon at least one parameter established by a random generator.

Description

Surface structure of a roller and method and device for producing the surface structure

The invention relates to the surface structure of a roller intended to act on a material, which consists of recesses in the form of craters produced by an electron beam and the crater walls surrounding the craters.

The invention also relates to a method for producing the surface structure on a roller, in which the recesses are produced by an electron beam in the surface area of the roller.

Finally, the invention relates to a device for producing the surface structure on a roller, which has a beam generator that generates an electron beam, a focal length setting, a focusing and a deflection unit that positions the electron beam relative to the roller.

Various methods have been used in the past to produce such surface structures on rollers, in particular on texture or dressage rollers for roughening steel sheets. On the one hand, particle grazing was carried out with steel gravel in accordance with a shot, on the other hand, depressions were carried out on the roller with the aid of electroerosion or with the aid of lasers. However, electro-erosion and particle exposure to steel gravel lead to recesses with sharp edges, the edges of which tend to break off and thus tend to develop dust. In the case of electroerosion and laser application, oxidation of the roller metal and thus ash formation also occur. The number of indentations to be produced on the roller surface is limited by the inertia of the mirrors used when processing with lasers.

DE-OS 2840702 discloses a method and a device for improving the quality of thin steel sheets. This publication states that a surface structure is created on the roller surface with the aid of intermittent energy radiation along a spiral path. In particular, it is stated that a laser beam can be used as energy radiation. However, it is also on the

Possibility pointed out to use basically an electron beam. However, no specific information is given on the course of a method using an electron beam or on the construction of a device using this method.

From EP-A-0 119 182 it is known to apply laser radiation or electron radiation to a roller surface. This radiation creates a spiral path on the roller. In particular, the idea here is to blow a gas, for example oxygen, into the area of radiation exposure. As a result of the oxygen admission, the roller metal is oxidized in the area of the radiation exposure. This largely avoids the formation of a crater wall, which encloses a recess created by the radiation, since the material which evaporates or is ejected in the liquid state from the recess reacts very quickly with the oxygen. In FR-PS 902 850 the technical teaching is given to carry out the surface structuring of a texture roller with the aid of laser radiation and to avoid the use of mirrors in that the roller to be acted upon is moved past a stationary laser in a rotational and translatory manner.

From EP-B-0 108376 it is known to carry out an engraving of printing rollers with the aid of an electron beam and to ensure post-engraving relative to an engraving that has already taken place by means of a special single-phase process. The local arrangement of the recesses on the engraving roller produced with the aid of the device described in this document is, however, predetermined by the print image to be generated. The size and placement of the individual recesses is thus precisely determined before the start of the engraving process.

DE-PS 519414 describes a method according to which a roller is provided with a surface structure with which a surface of a metallic object can be contoured. For this purpose, the roller has a uniform structure pattern, which essentially consists of recesses which are elongated in the circumferential direction and which are adapted to elevations in the region of a counter-roller.

From GB-PS 279413 it is known to roll plates to produce a uniform surface structure. The surface structure can consist, for example, of elongated, cross-shaped or cylindrical elevations which are distributed uniformly and spaced over the plate. The surface structuring for texture or skin-pass rolls known from the prior art cannot meet all the requirements which occur in particular in processing plants when sheet metal loaded with the rolls is used. As a rule, these requirements consist in the fact that preferred directions on the material surface are undesirable, excellent adhesion of any surface coatings that may be necessary must be ensured and that dust formation due to material abrasion must be avoided. The combination of these requirements could not be satisfactorily met with the help of the previously known surface structures.

It is therefore an object of the present invention to improve a surface structure of the type mentioned in the introduction in such a way that both requirements with regard to avoiding a preferred direction and requirements with regard to material resistance can be met at the same time.

This object is achieved in that a plurality of recesses are provided with diameter and / or depth differences lying within a predefinable range of variation, that both the spacing of the recesses in the circumferential direction of the roller and the spacing of the recesses vary in the longitudinal direction of the roller , and that both overlapping as well as adjacent and spaced recesses are provided.

This formation of the surface structure makes it possible to generate the surface contour of craters and crater walls, which can be generated by electron beam exposure, and which are firmly attached are connected to the roller material, to be combined with a distribution and dimensioning of the recesses, which largely produce a surface contouring that corresponds to a contouring that occurs when steel gravel is applied. This has the essential advantage that, in the area of further processing operations, methods and processing sequences adapted to such surface structuring can be maintained and that no time-consuming and costly conversions are necessary. Significant disadvantages of the exposure to steel gravel, namely the possible development of dust on the finished product due to the breaking off of material particles, the energy expenditure for handling the steel gravel and the not inconsiderable noise development can thereby be avoided.

Another object of the present invention is to improve a method of the type mentioned in the introduction so that it is suitable for generating the surface structure according to the invention.

This object is achieved in that the electron beam is controlled with respect to its positioning relative to the roller surface at least in one spatial dimension as a function of a parameter defined via a random generator.

The control of the electron beam with the aid of a random generator avoids a uniform distribution and formation of the recesses. In particular, with a variation in the positioning of the electron beam relative to the roller surface both in the circumferential direction and in the longitudinal direction of the roller, and with a variation in the depth and diameter of the recesses, one can use the method Surface structuring are generated, which, apart from a qualitatively better version, is largely identical to a surface structuring created with the aid of steel gravel inspection.

Another object of the present invention is to construct a device of the type mentioned in the introduction so that it is suitable for carrying out the method according to the invention.

This object is achieved in that a control unit that positions the electron beam with respect to at least one spatial dimensioning is connected to at least one random generator that specifies at least one positioning parameter.

The random generator, which can be designed, for example, as a commercially available digital module or as a digital computer program, generates an output value after a corresponding clock signal, the amplitude of which follows a random distribution within a predeterminable amplitude spectrum when temporally considering successive amplitude values.

According to a preferred embodiment of the invention it is provided that an additional random contouring of the roller surface is brought about by an uneven cooling contraction resulting from a rapid cooling of the crater walls of the roller material forming the crater walls. The material from the craters, which forms the respective crater walls, does not have a uniform material distribution immediately after the generation of the crater along the periphery of the crater, but is in consequence of ongoing ejection and evaporation processes distributed unevenly. If the crater wall cools down quickly, the material does not have sufficient time to distribute itself evenly within the crater wall. A possible pre-tempering of the roller area receiving the crater wall can thus ensure firm adhesion of the crater wall to the roller surface, but the crater walls are not evenly structured due to the short cooling time.

According to a further preferred embodiment of the invention it is provided that the electron beam is tracked in the circumferential direction during the generation of the recesses of the rotation of the roller. This tracking prevents deformation of the recess in the circumferential direction of the roller and thus the formation of a recognizable preferred direction.

Further details of the present invention will become apparent from the following detailed description and the accompanying drawings, in which preferred embodiments of the invention are illustrated by way of example.

The drawings show:

1: a section of the surface structure on a roller with a stochastic distribution of recesses,

2: a cross section through a recess,

3: a diagram, 4 shows a basic illustration of a device for producing a surface structure,

5: a schematic diagram of the beam generation,

6: a block diagram of the control of the device,

7: a block diagram of the lens control,

8: a schematic diagram of a focused electron beam,

Fig. 9: a schematic diagram of a focused electron beam u n d

Fig. 10: a basic block diagram to illustrate the randomly controlled positioning of the electron beam.

FIG. 1 shows a section of the surface structure on the surface (1) of a roller (2) in the form of a large number of

Recesses (22) shown. The recesses (22) or craters are surrounded by crater walls (62) or ridges. The recesses (22) are distributed stochastically in the area of the surface (1), and there are partial overlaps of at least two recesses (22), recesses (22) and crater walls (62) or at least two crater walls ( 62).

Figure 2 shows the detail through a recess (22) or through a crater, from which it can be seen that the crater is surrounded by a crater wall (62) rising above the surface (1). The diameter of the almost circular Crater wall (62) is designated with "D", the height of the crater wall (62) with "H", the width of the crater wall (62) with "B" and the depth of the crater (22) with "T".

FIG. 3 shows in a diagram the preferred range of values (hatched area) for the depth T and the diameter D in micrometers.

FIG. 4 shows an exemplary embodiment of a device for producing a surface structure on a roller (2). This device essentially consists of a beam generator (4) generating an electron beam (3), a lens system (5) and a vacuum chamber (6) accommodating the roller (2). The beam generator (4) and the lens system (5) are arranged in a beam device (7) which is divided into a main chamber (8) and an intermediate chamber (9). The beam generator (4) and a focal length adjustment (10) are arranged in the main chamber (8) and are designed as part of the lens system (5). In the intermediate chamber (9) there is essentially an interchangeable diaphragm (11) and a focusing (12) which, together with the focal length setting (10), form the essential elements of the lens system (5). The main chamber (8) is separated from the intermediate chamber (9) by a vacuum throttle (13) which has a recess (14) arranged essentially centrally and permitting the passage of the electron beam (3). The vacuum throttle (13) makes it possible to achieve different pressure ratios in the main chamber (8) and the intermediate chamber (9). For example, it is possible to achieve a pressure of approximately 8 x 0.00001 bar in the main chamber (8) and a pressure of approximately 8 x 0.001 bar in the intermediate chamber (9). The beam generator (4) consists essentially of a cathode (15), a Wehnelt cylinder (16) and an anode (17). An anode centering device (18) which deflects the electron beam (3) in two dimensions is arranged in the area of the anode (17). In the direction of propagation (19) of the electron beam (3), a subsequent centering device (20) is arranged behind the anode (17), which likewise performs a two-dimensional deflection of the electron beam (3) and avoids scattering losses. The cathode (15) is connected via lines (15 ") to a high-voltage unit (21) shown in FIG. 5, which has a voltage of up to approximately

- 50 kilovolts generated. A typical value is around

- 35 kilovolts. With such a voltage, recesses (22) with a typical depth of approximately 7 micrometers can be produced on the surface (1) with an exposure time of approximately one microsecond. When the high voltage is reduced to approximately - 25 kilovolts, the typical depth of the recess (22) is approximately 3 to 4 micrometers. The cathode (15) is also connected to a heating current supply (23) shown in FIG. The Wehnelt cylinder (16) is fed via a line (16 ') by a voltage generator (24), which generates a potential of approximately - 1000 volts compared to the voltage applied to the cathode (15). In the area of the anode (17), in addition to the centering coils forming the anode centering device (18), an ion barrier (25) is provided, which removes ions occurring in the area of the anode (17) from the area of the electron beam (3). The anode (17) is connected to a ground connection (27) via a resistor (26). The high-voltage unit (21) is also connected to ground via a resistor (28). Tungsten wires are particularly suitable as the material for the cathode (15).

The focal length setting (10) is made up of a first zoom lens (29) and a second zoom lens (30), which in Direction of propagation (19) are arranged one behind the other. The first zoom lens (29) consists of a dynamic lens (31) and a static lens (32). The second zoom lens (30) is designed without a dynamic lens (31). The vacuum in the main chamber (8) is maintained by a vacuum pump (33) and the vacuum in the intermediate chamber (9) by a vacuum pump (34). In particular, it is contemplated to design the pumps (33, 34) as turbomolecular pumps. A centering device (35) is provided in the intermediate chamber (9) between the changeable diaphragm (11) and the focusing (12), which avoids scattering losses of the electron beam (3). The focusing (12) consists essentially of a static lens (36) and a dynamic lens (37). The dynamic lenses (32, 36) are each arranged in the region of the inner surfaces of the static lenses (32, 36) facing the electron beam (3). On the side facing the vacuum chamber (6), the device (7) has an outlet opening (38) in which a nozzle (39) is arranged.

In order to control the reproducible placement of the recesses (22) on the surface (1) there is a raster disk (40) which is synchronized with the rotary movement of the roller (7) and is shown in FIG. is connected to an evaluation (42). The evaluation (42) provides a clock for subsequent control elements, which enables the current position of the roller (2) to be recorded precisely. A reference point is defined in a defined manner with the aid of a zero point detection (43). The evaluation (42) is connected to a controller (44), which can be designed, for example, as a phase-locked loop circuit. The

Control (44) feeds a sawtooth generator (45) and a feed cycle generation (46). The sawtooth generator (45) has an engraving sawtooth connection (47) and a feed sawtooth connection (48). The feed clock generation (46) is provided with a feed stepper motor connection (49). The control output (73) of the control (44) is connected to the sawtooth generator (45) and, via a control connection (50 '), to a lens control (50). The lens driver (50) has a zoom lens connector (51), a focus lens connector (52) and a control connector (53).

In Figure 6, a random control is also provided, which is formed from a random generator (65) for the engraving depth and a random generator (66) for the position of the electron beam (3). The random generator (65) is connected to the lens control (50) via the control input (53). The random generator (66) has control outputs for both an X and a Y coordinate and is connected to the sawtooth generator (45) via these control outputs. The X coordinate corresponds to the longitudinal direction of the roller (2) and the Y coordinate corresponds to the circumferential direction. The control (44) is provided with a connection (67) for a parameter setting for the position. The controller (44) provides a control signal for deflecting the electron beam (3) in the longitudinal direction of the roller (2) in the area of a control output (79) and a control signal for deflecting the electron beam (3) in the area of a control output (80). in the circumferential direction of the roller (2).

To control the lens system (5), several characteristic curve elements for signal shaping are provided in the lens control (50) according to FIG. A sharpness element (55), timer stages (56a, 56b, 56c) and a zoom element (58) are controlled via a linearization (54) provided with a control connection (53). The control signal present at the control input (53) influences the geometry of the recesses (22) to be produced. The specified control variable is converted in the focus element (55) by means of characteristic curves into setting values for the focusing (12), which are fed to the dynamic lens (37) for focusing. The characteristic of the zoom element (58) converts the control variable into corresponding setting values for the focal length setting (10), which reach the dynamic lens (31).

The relative movement of the roller (2) with respect to the nozzle (39) can be compensated for by tracking the electron beam (3). As a result, the electron beam (3) remains precisely aligned with the area to be acted upon and leads to the formation of very symmetrical recesses (22).

Due to the very short time delays in controlling the lens system (5), approximately 150,000 recesses (22) can be produced per second. When using suitably fast control devices, it is also possible to realize clock frequencies for the generation of 300,000 to 600,000 recesses per second. In order to achieve these clock frequencies, the roller (2) is rotated at about 10 revolutions per second and moved axially at a corresponding speed. With a time span of approximately 16 microseconds to produce a recess (22), a complete roller (2) can be processed within approximately 45 minutes. The energy consumption by the roller (2) is only about 500 watts during this time. Unwanted changes on the surface (1) due to thermal

Tensions or similar processes are therefore excluded with a high degree of probability. FIG. 8 shows an electron beam (3) focused to produce a recess (22). In this focusing state, the electron beam (3) has a high energy density in the area of the surface (1).

The electron beam (3) is shown focused in FIG. 9 and is not able to carry out structural changes on the surface (1) due to the lower energy density compared to the focusing according to FIG. This defocused state of the electron beam makes it possible to change the position of the electron beam (3) relative to the surface (1) during a further movement of the roller (2), without damaging the surface area between two recesses (22) to be produced.

FIG. 10 shows a random generator (68) which summarizes the functions of the random generator (65) and the random generator (66) according to FIG. 6, which is connected to a control unit (69) coordinating it and depending on an internally generated random signal on parameters of the Accesses memory modules containing electron beam setting. A zoom memory (70), a focus memory (71), a shot time memory (72), an X deflection memory (73) and a Y deflection memory (74) are provided. In the stores

(70, 71, 72, 73, 74) memory cells (75) are arranged, in which special setting values for the electron beam (3) are contained. The memory cells (75) for the zoom memory (70) and the focus memory (71) are advantageously coupled. To trigger a parameter setting for the electron beam (3), the control unit (69) is provided with a clock connection (76). Determined parameters for the setting of the electron beam (3) are via a parameter connection (77) transmitted to the lens control (50). The control lines combined in the area of the parameter connection (77) can be routed, for example, to the connections (53) shown in FIG. 6 and to the X and Y connections of the sawtooth generator (45). The random generator (68) is controlled via the connecting line (78), which is designed as a cable consisting of several wires and also parameter information selected by the random generator (68) from the memories (70 to 74) to the control unit (69). can transfer back.

The memories (70 to 74) can contain different numbers of memory cells (75). For example, it can be designed such that in the area of the zoom memory (70) and the focus memory (71) there are thirty memory cells each and in the area of the X deflection memory (73) and the Y deflection memory (74) 4096 memory cells ( 75) are provided. For example, 256 memory cells (75) can be provided for the shot time memory (72).

The random generator (65, 66, 68) can be constructed from digital components in accordance with Tafel, Datentechnik, Hanser Verlag, 1978, pages 101 and 102. However, it is also possible to implement the random generator (65, 66, 68) as a digital computer program. A corresponding one

The algorithm is based, for example, on the auxiliary function "RANDOM" described in the TurboPascal 4.0 manual, Heimsoeth + Borland, October 1987, Volume 2, page 314.

Claims

1. Surface structure of a roller intended to act on a material, which consists of recesses produced by an electron beam in the form of

There are craters and crater walls surrounding the craters, characterized in that a plurality of recesses (22) with differences in diameter and / or depth lying within a predefinable range of variation are provided, that both the

Distances of the recesses (22) in the circumferential direction of the roller (2) and the distances of the recesses (22) in the longitudinal direction of the roller (2) vary, and that recesses (22) which are overlapping as well as adjacent and spaced apart are provided.

2. A method for producing a surface structure on a roller provided for the application of a material, in which recesses are produced on the surface of the roller by an electron beam, characterized in that the electron beam (3) is positioned at least in relation to its position relative to the surface (1) a spatial dimension is controlled as a function of a parameter defined via a random generator (65, 66, 68).

3. The method according to claim 2, characterized in that at least one deflection in a circumferential direction of the roller (5) is set randomly.

4. The method according to at least one of claims 2 and 3, characterized in that at least one deflection in the longitudinal direction of the roller (2) is determined randomly.

5. The method according to at least one of claims 2 to 4, characterized in that at least the focusing of the electron beam (3) is determined randomly.

6. The method according to at least one of claims 2 to 5, characterized in that at least the focus setting of the electron beam (3) is determined randomly.

7. The method according to at least one of claims 2 to 6, characterized in that the random

Determination of the focus and the focus adjustment is made coupled.

8. The method according to at least one of claims 2 to 7, characterized in that the exposure time of the

Electron beam (3) on the surface (1) is set randomly.

9. The method according to at least one of claims 2 to 8, characterized in that at least one of the parameters defining the random setting is taken from a memory cell (75), the selection of which is carried out randomly.

10. The method according to at least one of claims 2 to 9, characterized in that depending on the randomly controlled setting of the electron beam (3) of crater walls (62) enclosed recesses (22) are generated.

11. The method according to at least one of claims 1 to 10, characterized in that a random surface contouring on the surface (1) is generated by rapid cooling of the crater walls (62).

12. The method according to at least one of claims 2 to 11, characterized in that the positioning of the recesses (22) on the surface (1) varies such that an overlay of crater walls (62) and

Recesses (22), or from adjacent crater walls (62) is made possible.

13. The method according to at least one of claims 2 to 12, characterized in that the randomly controlled

Surface structure is generated on a roller (2) designed as a texture roller.

14. Device for producing a surface structure on a surface provided for the application of a material

Roller which has a beam generator generating an electron beam, a focal length setting and a focusing, characterized in that a control unit (69) positioning the electron beam (3) with respect to at least one spatial dimension with at least one random generator (65, 66, 68) is connected.

15. The apparatus according to claim 14, characterized in that the control unit is connected to a deflection unit for positioning the electron beam (3) in the circumferential direction of the roller (2)

16. The device according to at least one of claims 14 and 15, characterized in that the control unit (69) is connected to a deflection unit for deflecting the electron beam (3) in the longitudinal direction of the roller (2).

17. The device according to at least one of claims 14 to 16, characterized in that the control unit (69) is connected to the focusing (12).

18. The device according to at least one of claims 14 to 17, characterized in that the control unit (69) with the focal length setting (10) is connected.

19. The device according to at least one of claims 14 to 18, characterized in that a tracking unit is provided which tracks the electron beam (3) in the direction of rotation of the roller (2) and compensates for the rotational movement of the roller (2) relative to the beam generator (4).