Method of producing a toothed workpiece having a modified surface geometry

Patent metadata

Field	Value
Publication number	US-10493546-B2
Application number	US-201615207339-A
Country	US
Kind code	B2
Filing date	Jul 11, 2016
Priority date	Jul 10, 2015
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

A toothed workpiece having a modified surface geometry may be produced by a diagonal generating method by means of a modified tool whose surface geometry comprises a modification. The modification may be described by a linear and/or quadratic function, with the coefficients of this linear and/or quadratic function. Pitch and/or crowning of the modification may vary in dependence on the angle of rotation of the tool and/or on the tool width position. The specific modification of the tool produces a corresponding modification on the surface of the workpiece by the diagonal generating method, with a desired modification of the surface geometry of the workpiece being specified and a modification of the surface geometry of the tool suitable for producing this desired modification being determined in combination with a diagonal ratio of the diagonal generating method suitable for producing the desired modification.

First claim

The invention claimed is:

1. A method of producing a toothed workpiece using a tool, the tool having an axis of rotation extending in an axial direction, and a tool width direction extending parallel to the axial direction, the method comprising the steps of:
specifying a desired modification of a surface geometry of the workpiece;
determining a modification of a surface geometry of the tool and a diagonal ratio of a diagonal generating method using said tool such that they are suitable for producing the desired modification, said modification of the surface geometry of the tool comprising at least one out of:
a modification that is, in a first direction of the tool extending at an angle ρ FS ≠0 with respect to the tool width direction, at least one out of a linear function and a quadratic function; wherein coefficient functions of said at least one out of a linear function and a quadratic function vary in a second direction of the tool which extends perpendicular to the first direction, and
a modification having, in a first direction of the tool extending at an angle ρ FS ≠0 with respect to the tool width direction, at least one out of a pitch and a crowning varying in dependence on a position in the tool width direction;

providing the tool having the determined modification of the surface geometry;
machining the workpiece by the diagonal generating method using the tool and the determined diagonal ratio, wherein the modification of the surface geometry of the tool by the diagonal generating method produces the desired modification on the surface of the workpiece
wherein the workpiece has an axis of rotation extending in a workpiece axial direction, and a tool width direction extending parallel to the workpiece axial direction, and the diagonal ratio is determined such that in the diagonal generating method the first direction of the tool is mapped onto a direction of the workpiece extending at an angle different from zero with respect to the workpiece width direction.

2. The method in accordance with claim 1 , wherein the workpiece has an axis of rotation extending in a workpiece axial direction, and a tool width direction extending parallel to the workpiece axial direction, and the desired modification of the surface geometry of the workpiece is specified as a modification comprising at least one out of:
a modification which is, in a first direction of the workpiece extending at an angle different from zero with respect to the workpiece width direction, at least one out of a linear function and a quadratic function, with coefficient functions of said at least one out of linear function and a quadratic function varying in a second direction of the workpiece which extends perpendicular to the first direction; and
a modification having, in a first direction of the workpiece extending at an angle different from zero with respect to the workpiece width direction, at least one out of a pitch and a crowning varying in dependence on the workpiece width position.

3. The method in accordance with claim 1 , wherein in the step of determining the modification of the surface geometry of the tool, at least one out of the following conditions apply:
the coefficient functions of the modification of the surface geometry of the tool are selectable from a range of coefficient values to produce the desired modification of the surface geometry of the workpiece; and
the at least one out of a pitch and a crowning of the modification of the surface geometry of the tool is selectable from a range of values as a function of the position in the tool width direction.

4. The method in accordance with claim 1 , wherein at least one of the following conditions apply:
for the step of determining the modification of the surface geometry of the tool from the desired modification of the surface geometry of the workpiece, an inversion of an association function which describes a mapping of the surface of the tool onto the surface of the workpiece in diagonal generating grinding is used, wherein the association function depends on the diagonal ratio;
the desired modification of the surface geometry of the workpiece is specified as a continuous function on a surface on the tooth flank and/or on a scatter plot spanning a surface on the tooth flank;
the modification of the surface geometry of the tool is determined as a continuous function on a surface on the tooth flank and/or on a scatter plot spanning a surface on the tooth flank;
the modification of the surface geometry of the workpiece is selectable at at least two or three rolling angles as a function of the position in the tool width direction and interpolation takes place for rolling angle regions disposed therebetween.

5. The method in accordance with claim 1 , wherein the step of providing the tool having the modified surface geometry comprises a step of modifying the surface geometry of the tool by dressing the tool with a dresser and modifying a relative position between the tool and the dresser during dressing, with the dresser being in line contact with the tool during dressing and the first direction of the modification of the surface geometry of the tool corresponding to a line of action of the dresser during dressing.

6. The method in accordance with claim 1 , wherein the step of providing the tool having the modified surface geometry comprises a step of modifying the surface geometry of the tool by dressing the tool with a dresser, wherein the modification of the surface geometry of the tool is produced by varying a position of the dresser with respect to the tool during dressing in dependence on the position in the tool width direction, wherein at least three degrees of freedom or at least four or five degrees of freedom are used for varying the position of the dresser with respect to the tool, with the degrees of freedom being varied independently of one another in dependence on the position in the tool width direction for producing the desired modification.

7. The method in accordance with claim 5 , further comprising the step of determining a suitable diagonal ratio and a suitable variation of a position of the dresser to the tool on dressing in dependence on the position in the tool width direction in dependence on the desired modification of the surface geometry of the workpiece.

8. The method in accordance with claim 1 , wherein in the step of specifying the desired modification of the surface geometry of the workpiece, a desired orientation of the modification of the surface geometry of the workpiece is specified and in the step of determining the diagonal ratio, the diagonal ratio is set such that the desired orientation of the modification is produced on diagonal generating machining.

9. The method in accordance with claim 1 , wherein in the step of machining the workpiece by the diagonal generating method, the diagonal ratio is varied in dependence on the position in the tool width direction.

10. The method in accordance with claim 1 , wherein the tool has a conical base shape, with a conical angle of the tool being larger than 0,5° and less than 50°.

11. The method in accordance with claim 10 , wherein the conical angle of the tool is larger than 1° and less than 20°.

12. The method in accordance with claim 10 , wherein the tool is a grinding worm.

13. The method in accordance with claim 1 , wherein the diagonal ratio is determined by curve fitting or analytically.

14. The method in accordance with claim 2 , wherein the step of specifying the desired modification of the surface geometry of the workpiece, at least one out of the following conditions apply:
at least one out of the coefficie

Assignees

• Liebherr Verzahntech Gmbh

Inventors

• Wuerfel Robert

Classifications

• G05B2219/36198

  Gear, thread cutting · CPC title

• G05B2219/35035

  Design gear, tooth surfaces · CPC title

• G05B19/40937

  concerning programming of machining or material parameters, pocket machining · CPC title

• G05B19/4097

  characterised by using design data to control NC machines, e.g. CAD/CAM (G05B19/4093 takes precedence) · CPC title

• G05B19/29

  for point-to-point control · CPC title