METHOD AND TOOL FOR REMOVING A COATING FROM A SUBSTRATE

Abstract

The present invention relates to a method and a tool for removing a partial region of a coating from a substrate, in which the partial region to be removed is removed by a machining process in such a way that an undercutting of the partial region of the coating that is to be removed takes place. For the undercutting of the partial region of the coating that is to be removed, at least one machining tool that is rotating relative to the substrate about an axis of rotation is moved relative to the substrate along a direction of advancement that runs parallel to a surface having the coating, wherein a layer of the substrate that is directly adjacent to the coating is also removed together with the coating. Considered in the direction of advancement, the tool thereby penetrates deeper into the substrate than into the coating to be removed.

Claims

1. A method for removing a partial region of a coating from a substrate, wherein the partial region to be removed is removed by a machining process such that the partial region of the coating to be removed is undercut, wherein to undercut the partial region of the coating to be removed, at least one machining tool rotating relative to the substrate about an axis of rotation is moved relative to the substrate along a direction of advancement (V) which runs parallel to a surface having the coating, wherein together with the coating, a substrate layer directly adjacent to the coating is also removed and the tool, considered in the direction of advancement (V), penetrates deeper into the substrate than into the coating to be removed.

2. The method according to claim 1, wherein the machining tool is a cutting insert.

3. The method according to claim 1, wherein the direction of advancement (V) further runs parallel to the axis of rotation.

4. The method according to claim 1, wherein the substrate is a cylinder wall of a cylinder of a crankcase, wherein the direction of advancement (V) runs in the axial direction of the cylinder.

5. The method according to claim 1, wherein the tool is held on a rotating spindle.

6. The method according to claim 1, wherein the tool is mounted in a non-rotating manner and the substrate is rotated.

7. The method according to claim 1, wherein the tool is adjustable along the direction of advancement (V).

8. The method according to claim 1, wherein the substrate is adjustable along the direction of advancement (V).

9. The method according to claim 1, wherein the tool is held such that a cutting edge of the tool provided for removing the coating runs obliquely to the direction of advancement (V).

10. The method according to claim 1, wherein the removal of the partial region of the coating comprises a generation of a groove free of undercuts, in a partial section of the partial region of the coating to be removed, wherein the groove is generated using a tool other than the tool provided for undercutting the partial region of the coating to be removed.

11. A chipping tool, for performing a method according to claim 1, comprising a tool holder fastened to a spindle, which tool holder has at least one radially opposite cutting edge, which cutting edges are radially adjustable.

12. The method according to claim 9, wherein the tool is held such that a cutting edge of the tool provided for removing the coating runs at an angle of 30 to 60 to the direction of advancement (V).

13. The method according to claim 10, wherein the removal of the partial region of the coating comprises a generation of an annular groove.

14. The method according to claim 11, wherein the chipping tool is a grinding tool.

15. The method according to claim 11, wherein the tool holder has two radially opposite cutting edges.

16. The method according to claim 11, wherein the radially opposite cutting edge is a cutting edge arranged on a cutting insert.

Description

DRAWINGS

[0025] Further advantages result from the present description of the drawing. Exemplary embodiments of the invention are illustrated in the drawing. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into useful further combinations.

[0026] Shown are:

[0027] FIGS. 1 to 7 show sectional views of a workpiece to be machined and the necessary tools and explain the sequence of the method over time;

[0028] FIG. 8 shows different views of a tool holder with two tools according to a first embodiment;

[0029] FIG. 9 shows various views of the tool holder of FIG. 8;

[0030] FIG. 10 shows different views of a tool holder with two tools according to a second embodiment;

[0031] FIG. 11 shows a sectional view of a tool during the removal of a coating of a substrate;

[0032] FIG. 12 shows an enlarged section of the sectional view of FIG. 11.

[0033] An exemplary sequence of the method according to the invention is illustrated in FIGS. 1 to 7.

[0034] In the figures, identical or similar components are numbered with the same reference numerals.

[0035] The removal of a partial region 22 of a hard coating 20, which was applied by a thermal spray process on a soft substrate, namely an inner surface or cylinder wall 12 of a cylinder 10 of an aluminum crankcase 14 of an internal combustion engine, is explained by way of example.

[0036] In step 1 (FIG. 1), a rotatable, in the embodiment conical, grinding tool 16 is inserted into the cylinder 10 a central position.

[0037] In step 2 (FIG. 2), the rotating grinding tool 16 is guided along an increasingly circular path along the coated cylinder wall 12 in order to grind an annular groove 18 or chamfer into the coating 20 in the radial direction. Tool wear is limited since the partial section of the annular groove 18 to be ground is small compared to a partial region 22 of the coating 20 to be removed.

[0038] In step 3 (FIG. 3), the rotatable grinding tool 16 is moved back into the central position and withdrawn from the cylinder 10.

[0039] In step 4 (FIG. 4), a tool holder 26 fastened to a spindle 24 is retracted into the cylinder 10 against a direction of advancement V. The spindle 24 is adjustable in and opposite to the direction of advancement V and rotatable about an axis of rotation corresponding to the axis of symmetry S of the cylinder 10.

[0040] Two opposing, radially adjustable clamping jaws 28 are provided on one end or front face of the tool holder 26, in which clamping jaws a respective cutting insert 30 is held as a machining tool. The tool holder 26 is illustrated again in FIG. 10 with the clamping jaws 28 retracted (above) and extended (below).

[0041] In step 5 (FIG. 5), the spindle 24 is rotated with the workpiece holder 26 and the clamping jaws 28 are extended or driven out radially, so that the cutting inserts 30 with their cutting edges 32 dip into the previously ground chamfer or annular groove 18.

[0042] In step 6 (FIG. 6), the rotating workpiece holder 26 is moved in the direction of advancement V along the axis of rotation or symmetry S. The cutting edges 32 of the cutting inserts 30 thereby undercut the coating 20 and remove it laterally, which is also illustrated in detail in FIGS. 11 and 12. A thin layer of the substrate, that is, the crankcase 14, is also removed. The removal of the coating 20 by one of the cutting edges 32 is illustrated enlarged in FIGS. 10 and 11.

[0043] In step 7 (FIG. 7), the clamping jaws 28 are radially retracted or driven into their starting positions. The workpiece holder 26 is extended out of the cylinder 10 in the direction of advancement V.

[0044] An alternative embodiment of a tool holder 126, which also has two radially adjustable clamping jaws 128, in which a respective cutting insert 130 with a cutting edge 132 is held as a machining tool, is shown in FIGS. 8 and 9. While in the tool holder 26, the cutting inserts 30 are arranged on a side of the tool holder 26 facing the spindle 24, the cutting inserts 130 in the tool holder 126 according to FIGS. 8 and 9 the cutting inserts 130 are arranged on the side facing away from a spindle 124, so that depending on the application, the coating 20 can be removed in a direction of advancement which is opposite to the direction of advancement V of FIGS. 1 to 7.

[0045] The tool holder 26 or 126 can advantageously have internal cooling, in which coolant is supplied to the cutting inserts 30, 130 via coolant channels provided in the interior of the spindle 24, 124 and the tool holder 26, 126.

[0046] The tool arrangement and the geometry of the cutting insert are illustrated in detail in FIGS. 10 to 12.

REFERENCE LIST

[0047] 10 cylinder [0048] 12 cylinder wall [0049] 14 crankcase, substrate [0050] 16 grinding tool [0051] 18 annular groove [0052] 20 coating [0053] 22 partial region [0054] 24, 124 spindle [0055] 26, 126 tool holder [0056] 28, 128 clamping jaw [0057] 30, 130 cutting insert [0058] 32, 132 cutting edge