METHOD FOR GRINDING A BEVEL GEAR

Abstract

Method for grinding a bevel gear, comprising the method steps of clamping a bevel gear (14) to be ground on a workpiece spindle (12) of a bevel gear grinding machine (2); first grinding of the tooth flanks (16, 18) of the bevel gear (14) with a first grinding tool (6), wherein the first grinding tool (6) is arranged on a first tool spindle (4) of the bevel gear grinding machine (2); fine grinding of the tooth flanks (16, 18) of the bevel gear (14) with a second grinding tool (10), wherein the second grinding tool (10) is arranged on a second tool spindle (8) of the bevel gear grinding machine (2).

Claims

1. A method for grinding a bevel gear comprising: clamping a bevel gear workpiece to be ground on a workpiece spindle of a bevel gear grinding machine; performing a first grinding of tooth flanks of the bevel gear with a first grinding tool located on a first tool spindle of the bevel gear grinding machine; and performing a fine grinding of the tooth flanks of the bevel gear with a second grinding tool located on a second tool spindle of the bevel gear grinding machine.

2. A method according to claim 1, further including (i) after performing the first grinding and before performing the fine grinding, performing a second grinding of the tooth flanks of the bevel gear; and/or (ii) after performing the first grinding and before performing the fine grinding, dressing the second grinding tool and generating thereby a dressed grinding tool topography of the second grinding tool adapted for said fine grinding.

3. A method according to claim 2, further including dressing the first grinding tool after performing the first grinding and before performing the second grinding and generating thereby a dressed grinding tool topography of the first grinding tool adapted for said second grinding.

4. A method according to claim 3, further including dressing the first grinding tool before performing the first grinding and generating thereby a dressed grinding tool topography of the first grinding tool adapted for said first grinding, wherein the dressed grinding tool topography adapted for said first grinding is different from the dressed grinding tool topography adapted for said second grinding.

5. A method according to claim 4, including performing the step of dressing the first tool before performing the first grinding at a higher or lower relative speed between a dressing tool and the first grinding tool compared to the during the step of dressing the first dressing tool after performing the first grinding and before performing the second grinding.

6. A method according to claim 4, wherein the step of dressing the first grinding tool before performing the first grinding comprises an eccentric movement between a dressing tool and the first grinding tool, and the step of dressing the first grinding tool after performing the first grinding and before performing the second grinding either (a) does not include eccentric movement or (b) includes a second eccentric movement different from the eccentric movement, or the step of dressing the first grinding tool after performing the first grinding and before performing the second grinding comprises an eccentric movement between a dressing tool and the first grinding tool, and the step of dressing the first grinding tool before performing the first grinding either (a) does not include eccentric movement or (b) includes a second eccentric movement different from the eccentric movement.

7. A method according claim 2, wherein the first and second grindings are performed with same or different process parameters.

8. A method according to claim 1, wherein (i) before said fine grinding, each of said tooth flanks defines an allowance for a nominal geometry thereof to be produced of about 0.01 mm up to and including about 0.02 mm; and/or (ii) after said fine grinding, said tooth flanks define a surface roughness Ra of about 1.6 m or less.

9. A method according to claim 8, wherein said surface roughness Ra is about 0.7 m or less.

10. A method according to claim 1, wherein the step of performing the first grinding defines a completing or a semi-completing process and includes grinding convex and concave flanks of the tooth flanks; and the step of performing the fine grinding defines a completing or a semi-completing process and includes grinding convex and concave flanks of the tooth flanks.

11. A method according to claim 1, wherein the first grinding tool includes a first abrasive grain and the second grinding tool includes a second abrasive grain that differs from the first abrasive grain by grain size and/or grain material.

12. A method according to claim 7, wherein the process parameters are the rotational speed or the rolling speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In the following, the invention is described in more detail on the basis of a drawing illustrating embodiment examples, which schematically show in each case:

[0043] FIG. 1 shows a machine tool with two tool spindles;

[0044] FIG. 2A shows a bevel gear in a perspective view;

[0045] FIG. 2B shows an enlarged section of the bevel gear from FIG. 2A;

[0046] FIG. 3 shows a flow chart of the method according to the invention.

DETAILED DESCRIPTION

[0047] FIG. 1 shows a double spindle machine 2, which is a bevel gear grinding machine 2. The double spindle machine 2 has a first tool spindle 4 and a first grinding tool 6 is held on the first tool spindle 4. The double spindle machine 2 has a second tool spindle 8. A second grinding tool 10 is held on the second tool spindle 8.

[0048] The first tool spindle 4 is set up to drive the first grinding tool 6 (rotational axis Al). The first tool spindle 4 is displaceable in a translatory manner along the X1, Y and Z axes.

[0049] The second tool spindle 8 is set up to drive the second grinding tool 10 (rotational axis A2). The second tool spindle 8 is displaceable in a translatory manner along the X2, Y and Z axes.

[0050] A pre-toothed and hardened bevel gear 14 or bevel gear workpiece 14 is held on a workpiece spindle 12 of the double spindle machine 2. The terms bevel gear and bevel gear workpiece are used synonymously.

[0051] The workpiece spindle 12 can be pivoted (swivel axis C). The bevel gear 14 can rotate around its longitudinal axis by means of workpiece spindle 12 (rotational axis B).

[0052] The bevel gear 14 has concave flanks 16 and convex flanks 18 (FIG. 2A, FIG. 2B). A respective concave flank 16 extends from a tip edge 20 of a tooth tip 22 of a tooth 24 of the bevel gear 14 to a tooth root 26 of the tooth 24, and a respective convex flank 18 extends from a tip edge 28 of the tooth tip 22 of the tooth 24 to a tooth root 30.

[0053] FIG. 3 shows a flowchart of a method according to the invention.

[0054] In a first method step (I), the pre-toothed and hardened bevel gear 14 is first clamped on the workpiece spindle 12 of the bevel gear grinding machine 2.

[0055] In a second method step (II) a first grinding of the tooth flanks 16, 18 of the bevel gear 14 is carried out with the first grinding tool 6, which is arranged on the first tool spindle 4. Before the first grinding, the grinding allowance for the nominal geometry to be produced is 0.100 mm per tooth flank. After the first grinding and before the second grinding, the grinding allowance for the nominal geometry to be produced is 0.025 mm per tooth flank.

[0056] In a further method step (III), after the first grinding and before a fine grinding, a second grinding of the tooth flanks 16, 18 of the bevel gear 14 is carried out, whereby the first grinding tool 6 is first dressed after the first grinding and before the second grinding, wherein a dressed grinding tool topography is generated for the second grinding.

[0057] The first grinding tool 6 has also been dressed before the first grinding, wherein a dressed grinding tool topography is generated for the first grinding.

[0058] The dressed grinding tool topography for the first grinding is different from the dressed grinding tool topography for the second grinding. These differing grinding tool topographies can be produced by a differing relative speed of the grinding tool relative to a dressing tool during dressing and/or by different kinematics during dressing, such as eccentric motion or the like.

[0059] After the second grinding, the fine grinding of the tooth flanks 16, 18 of the bevel gear 14 with the second grinding tool 10, which is held on the second tool spindle 8 of the bevel gear grinding machine 2, takes place in a further method step (IV).

[0060] Since the bevel gear grinding machine 2 has two separate grinding tools 6, 10 on separate tool spindles 4, 8, the bevel gear 14 can remain on the workpiece spindle 12 in one and the same clamping and can be machined alternately or first with the first grinding tool 6 and then with the second grinding tool 10.

[0061] After the second grinding and before fine grinding, there is an allowance of 0.015 mm per tooth flank for the nominal geometry to be produced. After fine grinding, the tooth flanks have a surface roughness Ra=0.7 m.

[0062] The grinding operation with the first grinding tool 6 can be carried out as a completing or semi-completing process, wherein both the convex and concave flanks 16, 18 of the bevel gear 14 are completely machined with the first grinding tool 6, without having to dress the grinding tool 6 for a change from the concave to the convex flank or vice versa. The grinding tool 6 in its form dressed for the first grinding is therefore suitable for machining both the concave flanks 16 and the convex flanks 18.

[0063] Similarly, the first grinding tool 6, with its shape dressed for the second grinding, is suitable for machining both the convex flanks 18 and the concave flanks 16. Grinding tool 6 therefore does not have to be dressed in a flank-specific manner.

[0064] Furthermore, the second grinding tool 10 is also set up to machine the tooth flanks 16, 18 in the completing or semi-completing process, so that the second grinding tool 10 is also set up for the complete machining of both the convex flanks 18 and the concave flanks 16 without the need for flank-specific dressing when changing from the concave to the convex flank or vice versa.

[0065] The grinding tool 6 in this case is a cup grinding wheel 6 for machining bevel gears. The grinding tool 10 is in this case a cup grinding wheel for machining bevel gears.

[0066] The first grinding tool 6 has a first abrasive grain and the second grinding tool 10 has a second abrasive grain, wherein the second abrasive grain differs from the first abrasive grain in its grain size and/or grain material.

[0067] It may be provided that a respective tooth root 26, 30 of a respective tooth 24 of the bevel gear 14 is also ground.

[0068] It may be provided that a respective tooth tip 22 of a respective tooth 24 of the bevel gear 14 is also ground.