Method and tool for roughening a cylinder bore wall to be coated, and component for guiding a cylinder piston

Abstract

A method for roughening a cylinder bore wall to be coated of a component, at least one groove, running around the central longitudinal axis, and at least one associated groove web, are generated such that the at least one groove web, in a radial direction directed toward the central longitudinal axis, forms first undercuts for a coating which is to be applied. Axial grooves running in the cylinder bore wall transversely to the at least one groove are generated such that the at least one groove web, in a peripheral direction about the central longitudinal axis, forms respective second undercuts for the coating which is to be applied. An adhesion of the coating which is to be applied, in the peripheral direction, is improved, so that stress cracks or detachments owing to a different thermal expansion of the component and of the coating which is to be applied are avoided.

Claims

1. A method for roughening a cylinder bore wall to be coated, the method comprising the following steps: providing a component having a cylinder bore and a cylinder bore wall extending around a central longitudinal axis; producing at least one groove, extending around the central longitudinal axis in the cylinder bore wall, and at least one associated groove web, such that the at least one associated groove web, in a radial direction, directed toward the central longitudinal axis, forms first undercuts for a coating which is to be applied; producing axial grooves, extending transversely to the at least one groove in the cylinder bore wall, such that the at least one associated groove web forms respective second undercuts for the coating which is to be applied in a peripheral direction about the central longitudinal axis, and the at least one associated groove web beside at least one of the axial grooves forms at least one material projection, the at least one material projection extending into the at least one groove and, the at least one material projection forming a respective further undercut in the peripheral direction for the coating which is to be applied; moving a tool for producing the axial grooves, having at least one deformation roller, along the central longitudinal axis; and rotating the at least one deformation roller about a rotational axis, extending transversely to the central longitudinal axis, such that on the cylinder bore wall the at least one deformation roller plastically deforms the cylinder bore wall for producing the axial grooves.

2. A method as claimed in claim 1, wherein the at least one groove has a groove depth T.sub.N and the axial grooves have a groove depth T.sub.A, wherein: 0.05 T.sub.A/T.sub.N≤2.

3. A method as claimed in claim 1, wherein the at least one associated groove web has a groove web width and the axial grooves extend over a whole of the groove web width.

4. A method as claimed in claim 1, wherein the at least one groove has a groove width B.sub.N and the axial grooves have a groove width B.sub.A, wherein: 0.05≤B.sub.A/B.sub.N≤2.

5. A method as claimed in claim 1, wherein the axial grooves form with the central longitudinal axis an angle α, wherein: −60°≤α≤60°.

6. A method as claimed in claim 1, wherein producing the at least one groove comprises a machining.

7. A method as claimed in claim 1, wherein adjacent axial grooves have an angular spacing Δφ in the peripheral direction, wherein: 0.5°≤Δφ≤24°.

8. A method as claimed in claim 1, wherein the axial grooves have a tapered cross section.

9. A method as claimed in claim 8, wherein the tapered cross section has a wedge-shaped configuration.

10. A method as claimed in claim 1, wherein the at least one associated groove web has a plurality of groove web windings extending in the peripheral direction over 360°, and the axial grooves configured in the plurality of groove web windings are oriented along straight lines such that the axial grooves cross the plurality of groove web windings.

11. The method as claimed in claim 1, wherein the at least one deformation roller is rotatably mounted on a tool main body and the at least one deformation roller is radially displaceable relative to the tool main body.

12. A method as claimed in claim 1, wherein producing the axial grooves comprises the following steps: moving the tool, having the at least one deformation roller, along the central longitudinal axis, such that the at least one deformation roller plastically deforms the cylinder bore for forming a first part of the axial grooves; pivoting the tool, if the at least one deformation roller is disengaged from the cylinder bore wall; and moving the tool along the central longitudinal axis such that the at least one deformation roller plastically deforms the cylinder bore for forming a second part of the axial grooves.

13. A method as claimed in claim 12, wherein the at least one deformation roller plastically deforms the at least one associated groove web for forming the first part and of the second part of the axial grooves.

14. A method as claimed in claim 1, wherein the at least one groove has a spiral angle ß, wherein: 0°<ß≤4°.

15. The method as claimed in claim 1, wherein the at least one deformation roller plastically deforms the at least one associated groove web for producing the axial grooves.

16. A method as claimed in claim 1, wherein the at least one deformation roller has a roller main body, on which is configured at least one deformation projection, running around the rotational axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings:

(2) FIG. 1 is a segmental top view of a component or guiding a cylinder piston having a cylinder bore wall bounding a cylinder bore, according to a first illustrative embodiment;

(3) FIG. 2 is a perspective view of the cylinder bore wall having a helical groove and an associated groove web, and having axial grooves running transversely thereto, wherein the cylinder bore wall is represented in one plane for better illustration;

(4) FIG. 3 is a top view of the cylinder bore wall according to FIG. 2;

(5) FIG. 4 is a sectional view through the cylinder bore wall along the sectional line IV-IV in FIG. 3;

(6) FIG. 5 is a sectional view through the cylinder bore wall along the sectional line V-V in FIG. 3;

(7) FIG. 6 is a perspective view of a cylinder bore wall according to a second illustrative embodiment, wherein the cylinder bore wall is represented, in accordance with FIG. 2, in one plane;

(8) FIG. 7 is a side view of a tool for roughening the cylinder bore wall and for generating the axial grooves; and

(9) FIG. 8 is a sectional view through the tool along the sectional line VIII-VIII in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) Below, a first illustrative embodiment of the invention is described with reference to FIGS. 1 to 5. A component 1 for guiding a cylinder piston has a main body 2, in which at least one cylinder bore 3 is configured. The cylinder bore 3 has a central longitudinal axis 4. The cylinder bore 3 is bounded by a cylinder bore wall 5, which runs around the central longitudinal axis 4. The component 1 is, for instance, a cylinder crankcase or a cylinder liner of an internal combustion engine. The component 1 or the main body 2 is preferably formed of a light metal, in particular of aluminum.

(11) In the cylinder bore wall 5 is configured a groove 6, which runs helically around the central longitudinal axis 4 and which is bounded by an associated helically running groove web 7. The cylinder bore wall 5 defines a peripheral direction Φ, which runs in a plane E running, in turn, perpendicular to the central longitudinal axis 4. A position in the peripheral direction Φ is characterized by the angle φ. The groove 6 forms with the peripheral direction Φ a spiral angle ß, wherein, for the spiral angle ß: 0°<ß≤4°, in particular 0.1°≤ß≤3°, and in particular 0.2°≤ß≤2°.

(12) The groove 6 has a groove bottom 8, and groove flanks 9, 10 arranged to the side thereof. The groove bottom 8 defines a groove depth T.sub.N relative to the cylinder bore wall 5. The groove flanks 9, 10 define between them a groove width B.sub.N. The groove width B.sub.N increases in the direction of the groove bottom 8, so that the groove flanks 9, 10 form, in a radial direction R directed toward the central longitudinal axis 4, first undercuts 11 for a coating S which is to be applied. This is illustrated in FIG. 4. The groove flanks 9, 10 form, at the same time, the groove web side walls. The coating S which is to be applied is indicated in FIGS. 1, 4 and 5.

(13) In the cylinder bore wall 5 are further configured axial grooves 12. The axial grooves 12 run transversely to the groove 6 and are thus configured in the groove web 7. The axial grooves 12 run, in particular, parallel to one another and/or perpendicular to the groove 6. The axial grooves 12 form with the central longitudinal axis 4 an angle α, wherein: −60°≤α≤60°, in particular −20°≤α≤20°, and in particular −10°≤α≤10°. The axial grooves 12 form with the at least one groove 6 an angle γ, wherein preferably: 30°≤γ≤150°, in particular 70°≤γ≤110°, and in particular 80°≤γ≤100°.

(14) The axial grooves 12 have a cross section which tapers in the direction of a respective groove bottom 13 and is of wedge-shaped configuration. The axial grooves 12 have, starting from the respective groove bottom 13 up to the cylinder bore wall 5, a groove depth T.sub.A. For the ratio of the groove depths T.sub.A/T.sub.N:0.05≤T.sub.A/T.sub.N≤2, in particular 0.1≤T.sub.A/T.sub.N≤1, and in particular 0.2≤T.sub.A/T.sub.N≤0.9. In addition, the axial grooves 12 have respective groove flanks 14. Between the respective groove flanks 14, the axial grooves 12 have a respective groove width B.sub.A. For the ratio of the maximum groove widths B.sub.A/B.sub.N:0.05≤B.sub.A/B.sub.N≤2, in particular 0.2≤B.sub.A/B.sub.N≤1.5, and in particular 0.4≤B.sub.A/B.sub.N≤1.

(15) The groove web 7 has in the peripheral direction Φ a plurality of groove web windings W extending respectively over 360°. The axial grooves 12 are configured along straight lines G in the groove web windings W. The groove web 7 has a groove web width B.sub.S. The axial grooves 12 thus extend over the whole of the groove web width B.sub.S. The axial grooves 12 are arranged at a distance apart in the peripheral direction Φ. The axial grooves 12 are distributed in particular in the peripheral direction Φ over the whole of the periphery of the cylinder bore wall 5. The axial grooves 12 have an angular spacing Δφ, wherein: 0.5°≤Δφ≤24°, in particular 0.5°≤Δφ15°, and in particular 0.5°≤Δφ≤2°. Preferably, the axial grooves 12 run along the straight line G and/or, in the peripheral direction Φ, adjacent axial grooves 12 run parallel to one another.

(16) The groove flanks 14 of the respective axial groove 12 form for the coating S which is to be applied, in the peripheral direction Φ, respective second undercuts 15. The groove flanks 14 form, at the same time, groove web walls, which, for a coating S which is to be applied, enable adhesion in the peripheral direction Φ. This is illustrated in FIG. 5.

(17) In an axial direction A which runs parallel to the central longitudinal axis 4, the groove 6 additionally forms third undercuts. The third undercuts 16 are formed, in particular, by the groove flanks 9, 10, which at the same time are groove web side walls. This is illustrated in FIG. 5.

(18) Below, a second illustrative embodiment of the invention is described with reference to FIG. 6. Unlike the component 1 according to the first illustrative embodiment, the groove web 7 beside the axial grooves 12 forms respective material projections 17, which extend into the groove 6. The material projections 17 form in the peripheral direction Φ respective fourth undercuts 18 for the coating S which is to be applied. With respect to the further structure and the further working method of the component 1 according to the invention, reference is made to the preceding illustrative embodiment.

(19) Below, a method for roughening the cylinder bore wall 5 to be coated is described:

(20) In the cylinder bore wall 5, the helically running groove 6 and the associated groove web 7 are generated. To this end, a machining tool is inserted into the cylinder bore 3, which tool rotates relative to the component 1 about the central longitudinal axis 4 and, at the same time, is moved linearly along the central longitudinal axis 4. The machining tool is configured as a metal-cutting machining tool and/or shaping machining tool. The groove 6 is accordingly generated by a machining and/or a plastic deformation of the cylinder bore wall 5. The groove 6 is generated, for instance, solely by machining by means of a metal-cutting machining tool having a profiled cutting edge. The first undercuts 11 are generated, in particular, by the profiled cutting edge of the metal-cutting machining tool and/or by the shaping machining tool. The spiral angle ß is set by the ratio of the rotation speed to the linear speed of the machining tool.

(21) Furthermore, the axial grooves 12 are generated. To this end, a tool 19, which is hereinafter also referred to as a roughening tool, is inserted into the cylinder bore 3 and, for the generation of the axial grooves 12, moved relative to the component 1 along the central longitudinal axis 4. In addition, the roughening tool 19 can be rotated about the central longitudinal axis 4, so that the axial grooves 12 form with the central longitudinal axis 4 the angle α.

(22) The generation of the axial grooves 12 can be realized before or after the generation of the groove 6. Preferably, the generation of the axial grooves 12 is realized after the generation of the groove 6. The generation of the axial grooves 12 can be realized by a machining and/or by energy irradiation and/or by plastic deformation. Preferably, the generation of the axial grooves 12 is realized by a plastic deformation of the groove web 7.

(23) Below, a roughening tool 19 for generating the axial grooves 12 by plastic deformation of the cylinder bore wall 5, as well as a corresponding method for roughening the cylinder bore wall 5, is described. The roughening tool 19 has a substantially cylindrical tool main body 20, which at a machine-side end is configured in a conventional manner for clamping into a tool spindle of a machine tool. The tool main body 20 has a main body central longitudinal axis 21, along which an actuating rod 22 is mounted in an axially displaceable manner within the tool main body 20. At a workpiece-side end, on the tool main body 20, on the periphery, a plurality of deformation rollers 23 are mounted rotatably about a respectively associated rotational axis 24. The roughening tool 19 has, for instance, four deformation rollers 23. The rotational axes 24 run perpendicular to the main body central longitudinal axis 21. The deformation rollers 23 are displaceable by means of the actuating rod 22 radially to the main body central longitudinal axis 21. To this end, the actuating rod 22 is, for instance, conically configured, so that a linear movement of the actuating rod 22 along the main body central longitudinal axis 21 results in a radial movement of the deformation rollers 23. An alternative embodiment of the roughening tool 19 has, instead of the actuating rod 22, deformation rollers 23 spring-mounted on the tool main body 20, so that these are displaceable radially to the main body central axis 21. By a radial displacement of the deformation rollers 23, a contact pressure of the deformation rollers 23 against the cylinder bore wall 5 is settable.

(24) The respective deformation roller 23 has a roller main body 25, on which is configured at least one deformation projection 26, running around the rotational axis 24. In FIG. 8, a plurality of deformation projections 26 are represented by way of example. The deformation projections 26 serve for the plastic deformation of the cylinder bore wall 5 or of the groove web 7. Accordingly, the deformation projections 26 are configured in accordance with the desired cross section of the axial grooves 12.

(25) Below, the generation of the axial grooves 12 by means of the roughening tool 19 is described:

(26) The roughening tool 19 is inserted into the cylinder bore 3. The deformation rollers 23 are radially displaced by means of the actuating rod 22 or a spring device such that they bear with a desired contact pressure against the cylinder bore wall 5. The roughening tool 19 is displaced relative to the component 1 linearly in the direction of the central longitudinal axis 4. In addition, a rotational movement of the roughening tool relative to the component 1 can be superimposed on the linear movement. By the deformation projections 26 of the deformation rollers 23, the cylinder bore wall 5 or the groove web 7 is plastically deformed, so that a first part of the axial grooves 12 is generated. By the contact pressure, the groove depth T.sub.A and groove width B.sub.A of the wedge-shaped axial grooves 12 are set. If the first part of the axial grooves 12 has been generated, then the roughening tool 19 is disengaged from the cylinder bore wall 5. This is realized, for instance, by virtue of the fact that the roughening tool 19 is located outside the cylinder bore 3, or the deformation rollers 23, through displacement of the actuating rod 22, no longer bear in a plastically deforming manner against the cylinder bore wall 5. After this, the roughening tool 19 is pivoted about the main body central longitudinal axis 21, so that the deformation rollers 23 are arranged in a region of the cylinder bore wall 5 in which no axial grooves 12 have yet been generated.

(27) Next, a second part of the axial grooves 12 is generated. To this end, the deformation rollers 23 are displaced radially outward by means of the actuating rod 22 or a spring device, so that these bear with the desired contact pressure against the cylinder bore wall 5. After this, the roughening tool 19 is again displaced linearly along the central longitudinal axis 4, so that the deformation projections 26 plastically deform the cylinder bore wall 5 and generate the second part of the axial grooves 12. The linear movement of the roughening tool 19 can once again be superimposed by a rotational movement. Preferably, the first part of the axial grooves 12 is generated by displacement in a first direction, whereas the second part of the axial grooves 12 is generated by a displacement in an opposite, second direction. Through the plastic deformation of the groove web 7, the material of the main body 2 is displaced into the groove 6, so that the material projections 17 are obtained. By the roughening tool 19, the axial grooves 12 and the material projections 17 can thus be generated in a simple manner.

(28) For the coating S which is subsequently to be applied, which coating is indicated, by way of example, in FIGS. 1, 4 and 5, the groove 6 and the associated groove web 7, as well as the axial grooves 12, form undercuts 11, 15, 16 and 18, so that the coating S has good adhesion in the radial direction R, in the axial direction A and, in particular, also in the peripheral direction Φ. By the axial grooves 12 and the material projections 17, in particular the adhesion in the peripheral direction Φ is markedly improved, so that thermally induced stress cracks or detachments are effectively avoided. As a result of the thermal coating and/or in motor-powered operation, the component 1 is subject to large temperature fluctuations. The temperature fluctuations are in particular, therefore, pronounced, since the component 1 has a low mass. Moreover, the component 1 is made of a light metal and therefore has, in comparison to the iron-containing coating S, a significantly greater coefficient of thermal expansion. The component 1 according to the invention, as well as the method according to the invention for roughening, thus enables a markedly improved adhesion of the coating S which is to be applied to the cylinder bore wall 5.

(29) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.