METHOD AND SYSTEM FOR METAL-COATING

Abstract

The invention relates to a method and to a system for metal-coating at least one surface of a workpiece, in which before coating, a surface structure with peaks and troughs in the surface to be coated is detected by means of a measuring apparatus, the coating is carried out by means of at least one deposition apparatus, which is moved relative to the surface and applies coating material in the process, and the deposition apparatus is controlled by a control apparatus on the basis of the detected surface structure, wherein more material is applied in the region of troughs and less material is applied in the region of peaks.

Claims

1. Method for metal-coating at least one surface (6) of a workpiece (5), in which before coating, a surface structure with peaks and troughs in the surface (6) to be coated is detected by means of a measuring apparatus (42), the coating is carried out by means of at least one deposition apparatus (25), which is moved relative to the surface (6) and coating material is applied in the process, and the deposition apparatus (25) is controlled by a control apparatus on the basis of the detected surface structure, wherein more material is applied in the region of troughs and less material is applied in the region of peaks.

2. Method according to claim 1, characterized in that a substantially level surface (8) is formed during the coating.

3. Method according to claim 1, characterized in that the coating is carried out as laser deposition welding.

4. Method according to claim 3, characterized in that during the laser deposition welding, metal powder is deposited on the surface (6) to be coated by means of the deposition apparatus (25) and in that, by means of a laser, the applied metal powder is locally melted, with the coating (7) being formed.

5. Method according to claim 4, characterized in that during the coating, the quantity of applied metal powder and/or a power of the laser is controlled by the control apparatus.

6. Method according to claim 1, characterized in that at least two deposition apparatuses (25) simultaneously deposit a coating (7) on the workpiece (5).

7. Method according to claim 6, characterized in that the workpiece (5) is disc-shaped or planar and in that a coating is carried out on two opposite surfaces (6).

8. Method according to claim 7, characterized in that the deposition apparatuses (25) are directly opposite one another and the coating is carried out on both sides simultaneously.

9. Method according to claim 1, characterized in that during the coating, the surface (6) to be coated is oriented approximately in parallel with the gravitational force.

10. Method according to claim 1, characterized in that after the coating, the coated surface (6) is measured by means of an output measuring apparatus (52), with a surface structure being detected.

11. Method according to claim 10, characterized in that material-removing post-processing of the coated surface is carried out, wherein a material-removing tool is brought to the workpiece (5) depending on the surface structure detected in the output measuring apparatus (52).

12. Method according to claim 11, characterized in that the post-processing includes grinding, honing, lapping and/or polishing.

13. System for the metal-coating of at least one surface (6) of a workpiece (5), in particular according to a method according to claim 1, comprising a measuring apparatus (42), by means of which a surface structure with peaks and troughs in the surface (6) to be coated is detected, at least one deposition apparatus (25) for depositing a coating, wherein the deposition apparatus (25) can be moved relative to the surface (6) of the workpiece (5) during the coating, and a control apparatus, which is designed to control the deposition apparatus (25) on the basis of the detected surface structure, wherein more material is applied in the region of troughs and less material is applied in the region of peaks.

14. System according to claim 13, characterized in that an output measuring apparatus (52) is provided, by means of which a surface structure of the coated surface (6) can be detected.

15. System according to claim 14, characterized in that a post-processing station (64) comprising at least one material-removing processing device (66) is arranged.

Description

[0027] The invention is explained in greater detail in the following on the basis of preferred embodiments shown schematically in the drawings, in which:

[0028] FIG. 1 is a schematic view of a system according to the invention;

[0029] FIG. 2 is a schematic view for coating a workpiece according to the invention;

[0030] FIG. 3 is a perspective view of another system according to the invention based on the system according to FIG. 1;

[0031] FIG. 4 is a schematic view of a measuring arrangement; and

[0032] FIG. 5 is a schematic view of the result of coating according to the invention.

[0033] A first embodiment of a system 10 according to the invention is shown in FIG. 1. Said system comprises four coating modules 20, which form a module group 30 in a parallel arrangement beside one another. An input measuring station 40 is arranged upstream of the module group 30, to which station workpieces (not shown here) are conveyed by means of a main conveying apparatus 60. By means of a handling apparatus 32, which is configured in the present embodiment as a multi-axis robot, the workpieces are picked up from the main conveying apparatus 60 and supplied to the box-shaped input measuring station 40.

[0034] The workpieces, in particular a surface to be coated, are measured using the measurement apparatus 42 in the input measuring station 40. In this process, a surface structure of the surface to be coated can in particular be detected, with peaks and troughs in the surface in particular being detected and measured.

[0035] The measured workpiece can then be transferred out of the input measuring station 40 via the handling apparatus 32, or directly out of the input measuring station 40, to a linear conveying apparatus 36 which runs along the coating modules 20. A supply apparatus 38 is arranged on the conveying apparatus 36, designed as a linear conveyor, upstream of each coating module 20, by means of which supply apparatus a workpiece is introduced into an inlet opening 24 in a box-shaped housing 21 of the selected coating module 20.

[0036] The coating modules 20 are designed to be the same or substantially the same and comprise a transport frame 22. With this transport frame 22, the coating modules 20 can be moved and relocated by means of an indoor crane or forklift truck. This makes it possible, for example in the event of a capacity change, to add or remove additional coating modules 20 or to replace an existing coating module 20 with a new coating module 20 for repair or maintenance purposes.

[0037] In the coating module 20, at least one surface of the workpiece 20 is provided with a metal coating, as will be explained in greater detail in the following in conjunction with FIG. 2. After the coating, the workpiece is guided back through the inlet opening 24 onto the conveying apparatus 36. This can also be carried out by the supply apparatus 38. By means of the conveying apparatus 36, the coated workpiece is transported to a common output measuring station 50, in which the coated surface of the workpiece is measured. After this final measurement in the output measuring station 50 by means of an output measuring apparatus 52, the workpiece is placed back onto the main conveying apparatus 60, by means of which the workpiece can be conveyed to further processing. The workpiece can likewise be transferred from the conveying apparatus 36 into the output measuring station 50 and again to the main conveying apparatus 60 by a handling apparatus 32 in the same way as on the input measuring station 40, but this is not shown in FIG. 1.

[0038] The measured values determined in the input measuring station 40 for a specified workpiece are transmitted to a central control apparatus. By means of the control apparatus, the conveying apparatus 36 is also controlled by the respective supply apparatus 38 such that the measured workpiece is guided to a specified coating module 20 of the module group 30. At the same time, the measured values of the specified workpiece are forwarded to the selected or specified coating module 20 by the control apparatus, such that the workpiece can be coated depending on the input measured values. After the coating, the workpiece is measured in the box-shaped output measuring station 50, the determined measured values likewise being forwarded to the central control apparatus and to the data set for the specified workpiece. A comparison of the input measured values and the output measured values as well as the coating parameters can be carried out in the control apparatus in order to determine whether a correct coating has been taken place. If necessary, operating parameters of a coating module 20 can be readjusted by the control apparatus during the coating.

[0039] According to FIG. 2, a disc-shaped element can be provided as a workpiece 5 to be coated, in particular a brake disc having one or two surfaces 6 to be coated. The metal coating can be applied by two deposition apparatuses 25, each comprising one coating nozzle 26, by means of plasma coating or laser deposition welding. The coating nozzle 26 is arranged on a carrier 27. In plasma spraying, metal particles are melted in an arc and are applied to the surface 6 at high speed. In deposition welding, coating material, in particular a metal powder, is initially applied and then locally melted by means of a laser. In the process, the coating can be carried out in multiple steps and multiple layers. In particular, the layers can also be applied with different layer thicknesses, different materials and different methods in order to achieve desired properties, in particular in terms of adhesion, abrasion resistance and/or corrosion resistance.

[0040] In principle, it is possible to carry out the coating using a coating nozzle 26, which is moved along the surfaces 6 to be coated by means of the carrier 27. In addition to plasma spraying and/or laser deposition welding, other thermal metal coating methods may also be used as alternatives or in combination with one another. As shown in FIG. 2, it is preferable for the coating to be deposited on two surfaces 6 of the disc-shaped workpiece 5 simultaneously by two coating apparatuses 25 which are arranged directly opposite one another.

[0041] A development of a system 10 according to the invention comprising a total of three module groups 30, which are each made up of four coating modules 20, is shown in FIG. 3. Here, the individual module groups 30 are designed according to the embodiment in FIG. 1, with an input measuring station 40 and an output measuring station 50 being assigned in each module group 30. The total of three module groups 30 are arranged along a linear main conveying apparatus 60, such that, in this parallel arrangement, workpieces can be processed in parallel in the individual module groups 30 and in the individual processing modules 20. After passing through the respective output measuring station 50, a workpiece which has finished being coated is guided back to the main conveying apparatus 60, by means of which the workpiece is fed to a post-processing station 64.

[0042] In the embodiment shown according to FIG. 3, the post-processing station 64 comprises a total of four post-processing devices 66, in particular grinding devices, arranged in parallel. By means of the grinding devices, the at least one coated surface of the workpiece can be processed and ground as a final step. In order to ensure efficient post-processing, the detected measured values for each workpiece can be forwarded to the specified grinding device in the post-processing station 64 which has been selected by the control apparatus for processing the workpiece. Depending on the detected final height of the coated surface of the workpiece, for example, the grinding tool can thus be efficiently advanced towards the workpiece in the respective grinding device.

[0043] It can be seen in particular from the embodiment according to FIG. 3 that even for larger increases in capacity that are potentially required, not only individual coating modules 20 but also whole module groups 30 which each comprise a plurality of coating modules 20 and associated input measuring station 40 and output measuring station 50 can be readily added to a total system.

[0044] FIG. 4 shows a measuring apparatus 42 comprising two measuring sensors 44 when measuring a workpiece 5 before coating. In this figure, the workpiece 5 is a schematically shown brake disc, which comprises two opposite surfaces 6 to be coated. The opposite sensors 44, which can each be arranged on a carrier of the measuring apparatus 42, can be designed as confocal sensors or triangulation sensors comprising a measuring laser.

[0045] The sensor 44 for detecting the surface structure 6 preferably moves precisely over the path along which the deposition apparatus 25 will subsequently move in order to deposit the coating.

[0046] In order to further increase the measurement quality, a line scan camera can be arranged which covers a radial region of the surface 6 of the workpiece 5. This measuring arrangement can be provided both in the input measuring station 40 and in the output measuring station 52.

[0047] FIG. 5 highly schematically shows part of a workpiece 5 after the coating. The surface 6 of the workpiece 5 to be coated has a surface contour having peaks and troughs, which are shown in an exaggerated manner in FIG. 5. Reference sign 3 denotes a schematic surface contour of a coating if said coating were to be uniformly deposited according to a conventional method. In doing so, the peaks and troughs of the surface 6 to be coated would also become apparent on the coated surface with the surface contour 3.

[0048] By means of the method according to the invention, more material can be applied to the surface 6 to be coated in the regions of troughs and less material can be applied in the regions of peaks, such that a coating 7 having a substantially level surface 8 results.

[0049] Using the method and system according to the invention, a high-quality coating can thus be deposited in a particularly economical manner.