ROLLER BURNISHING TOOL

Abstract

The invention relates to a roller burnishing tool (10) having a roller support (12), which projects in an advancement direction (V) and on which, in a circumferential direction, at least one burnishing roller (14) for machining a workpiece surface is provided such that it can rotate about a roller axis (A), wherein the at least one burnishing roller (14) has a contact surface for coming into contact with the workpiece. According to the invention, the at least one burnishing roller (14) has a basic cylindrical shape and the at least one burnishing roller (14) is mounted such that it can be moved in a radial direction (R).

Claims

1. A roller burnishing tool comprising a roller support which projects in a feed direction and on which a plurality of substantially cylindrical burnishing rollers for machining a workpiece surface are circumferentially arranged, wherein each of said plurality of burnishing rollers is rotatable about a roller axis, wherein each of said plurality of burnishing rollers has an outer surface for contacting the workpiece surface, wherein each of said plurality of burnishing rollers is mounted so as to be displaceable in a radial direction, wherein the roller support comprises an annular roller cage that rotatably bears said plurality of burnishing rollers, wherein a substantially annular inner roller is disposed in the roller cage, wherein the inner roller has an outer surface, wherein the outer surface of the inner roller interacts with the outer surfaces of said plurality of burnishing rollers, and wherein the inner roller is connected to a drive shaft of the roller burnishing tool so as to transfer driving force.

2. The roller burnishing tool according to claim 1, wherein the roller support has a rotational axis that runs substantially parallel to the roller axis of each of said plurality of burnishing rollers.

3. The roller burnishing tool according to claim, wherein the inner roller is disposed within the roller cage with a clearance fit.

4. The roller burnishing tool according to claim 1, wherein the inner roller is releasably disposed within the roller cage.

5. The roller burnishing tool according to claim 1, wherein the roller cage is made of a different material than the inner roller.

6. The roller burnishing tool according to claim 1, wherein the roller cage is made of a different material than said plurality of burnishing rollers.

7. The roller burnishing tool according to claim 1, wherein the inner roller includes liquid-conveying ducts.

8. A roller burnishing tool set comprising: a roller burnishing tool according to claim 1, and a plurality of additional exchangeable inner rollers, said additional exchangeable inner rollers having different outer diameters.

9. The roller burnishing tool according to claim 1, wherein each of said burnishing rollers comprises a roughening section with elevations that project radially outward relative to the roller axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will be further explained below with reference to the drawing. In the drawing,

[0025] FIG. 1 shows an exploded view of an exemplary embodiment of a roller burnishing tool.

DETAILED DESCRIPTION OF THE INVENTION

[0026] The roller burnishing tool 10 according to the present exemplary embodiment has a roller support 12, a holder 28, a first spacer disc 30, a second spacer disc 32 and a cross nut 34.

[0027] The roller support 12 has a roller cage 22 that is annular and which rotatably bears a plurality of burnishing rollers 14. For this purpose, the roller cage 22 in the present exemplary embodiment is formed from two roller cage halves 36a, 36b with the same design which together form a number of burnishing roller seats 38 that correspond to the plurality of burnishing rollers 14. The burnishing roller seats 38 are designed in this case such that the inserted burnishing rollers 14 are mounted with play in a radial direction R.

[0028] The burnishing rollers 14 have a substantially cylindrical basic shape, wherein the lateral surface has a section with elevations 20 that for example are formed by a diamond coating.

[0029] Together with an inner roller 24, the roller support 12 forms an assembly 44, wherein the inner roller 24 also has an annular basic shape which is inserted in an interior of the roller cage 22 designed in the shape of a ring. A clearance fit exists between the roller support 12 and the inner roller 24. Accordingly, the inner diameter of the roller support 12 in the present exemplary embodiment is greater than the outer diameter of the inner roller 24. Consequently, the inserted inner roller 24 limits the displaceability of the burnishing rollers 14 inserted into the burnishing roller seats 38 in a radial direction R, i.e., in a radial inward direction, whereas the burnishing rollers 14 still have play in a radial outward direction.

[0030] The burnishing roller seats 38 in the present exemplary embodiment are arranged on the outer surface of the roller cage 22 spaced evenly from each other in the circumferential direction. Between two burnishing roller seats 38 in each case, two holes each are also formed in the present exemplary embodiment in which pins are inserted in a press fit in order to connect the two roller cage halves 36a, 36b to each other.

[0031] The roller cage 22 and the inner roller 24 are made of a material pair having different materials. In the present exemplary embodiment, the roller cage 22 is made of red brass, and the inner roller 24 is made of steel. Furthermore the roller cage 22 and the inserted burnishing rollers 14 are also made of a material pair having different materials. In the present exemplary embodiment, the burnishing rollers 14 are made of solid carbide.

[0032] Accordingly, through a suitable material pair selection, the friction between the roller cage 22 and the inner roller 24, as well as between the roller cage 22 and the burnishing rollers 24, can be reduced.

[0033] The inner roller 24 furthermore has liquid-conveying ducts 40 in the present exemplary embodiment in order to supply the roller support 12 with a lubricant and/or coolant such as a water/oil emulsion in the present exemplary embodiment to lubricate and cool.

[0034] In the present exemplary embodiment, the liquid-conveying ducts 40 each comprise a peripheral groove on the axial end faces of the inner roller 24 and duct sections extending in a radial direction.

[0035] The liquid-conveying ducts 40 are supplied with lubricant and/or coolant through an exit opening 42 which in the present exemplary embodiment is arranged on an end face of a drive shaft 26 of the holder 28.

[0036] In the present exemplary embodiment, the first spacer disc 30 is arranged at the proximal end of the roller burnishing tool 10, whereas the second spacer disc 32 and the cross nut 34 are arranged at the distal end of the roller burnishing tool 10.

[0037] The first spacer disc 30 has a greater thickness than the second spacer disc 32 so that the roller burnishing tool 10 can be easily lowered to the bottom of a cylinder formed as a blind hole in order to machine sections of the inner wall of the cylinder located there.

[0038] The cross nut 34 shown in FIG. 1 represents a nonrotating connection in the present exemplary embodiment between a drive shaft 26 of the holder 28 also shown in FIG. 1 and the inner roller 24.

[0039] During operation, the roller burnishing tool 10 is introduced in a feed direction V into a workpiece such as a cylinder of a cylinder block of a reciprocating engine, the inner surface of which is to be machined as a workpiece surface. That is, the inner cylinder surface is the surface to be machined.

[0040] The drive shaft 26 causes the inner roller 24 to rotate about the rotational axis D of the roller support 12. The rotation of the inner roller 24 in turn causes the burnishing rollers 14 to rotate about their respective roller axis A that are parallel to each other in the present exemplary embodiment.

[0041] Due to the rotation of the burnishing rollers 14 about their respective roller axis A, they roll on the cylinder inner surface to be machined. In other words, the roller burnishing tool 10 forms a planetary gear-like arrangement with the inner surface of the cylinder to be machined as a fixed outer hollow shaft.

[0042] The inner roller 24 prevents a displacement of the burnishing rollers 14 radially inward in a radial direction R so that contact between the burnishing rollers 14 and the inner surface to be machined is ensured.

[0043] Due to the play between the inner roller 24 and the roller cage 22, individual burnishing rollers 14 can be displaced in a radial direction R radially outward by displacing the inner roller 24 in the annular roller cage 22 in order to reestablish contact between the burnishing rollers 14 and the inner surface to be machined.

[0044] In order to decrease or increase the play that prevents the displacement of the burnishing rollers 14, the inner roller 24 can be removed from the roller can 24 and replaced with another second inner roller selected from a plurality of inner rollers with different outer diameters.

[0045] Alternatively, the inner roller 24 removed from the roller cage 24 can be machined to reduce its outer diameter and thereby increase the play that prevents the displacement of the burnishing rollers 14. This is advantageous when an inner diameter of the completely machined workpiece (inner diameter of a cylinder) is greater than a predetermined threshold.

[0046] Due to the cylindrical basic shape of the burnishing rollers 14 and their radial displaceability for ensuring contact between the burnishing rollers 14 and the inner surface to be machined, there are no sections with different circumferential speeds so that there is only one rolling movement of the burnishing roller 14 on the surface to be machined. The roller burnishing tool 10 is therefore subject to less wear, and the machining of the surface to be machined can be carried out with greater precision.