METHOD FOR DRESSING A GRINDING TOOL

Abstract

Method for dressing a grinding tool by means of a machine tool including dressing the grinding tool with a form dressing roller and generating a tool profile on the grinding tool by a contact between the rotating grinding tool and the rotating form dressing roller along a dressing path, and generating relative movement therebetween along the dressing path automatically with the aid of two or more NC axes, wherein during the relative movement along the dressing path and during the contact between the form dressing roller and the grinding tool, each of the NC axes has an axial velocity with an absolute value greater than zero, and none of these NC axes carries out a directional reversal or comes to a standstill.

Claims

1. A method comprising: mounting a dressable grinding tool in a machine tool; mounting a form dressing roller in the machine tool; rotating the grinding tool, rotating the dressing roller; and dressing the grinding tool with the form dressing roller, and generating a tool profile on the grinding tool by relative movement and contact between the rotating grinding tool and the rotating form dressing roller along a dressing path, wherein the method includes generating said relative movement along the dressing path automatically using at least two NC axes of the machine tool; and wherein, during the relative movement along the dressing path and during the contact between the form dressing roller and the grinding tool, each of the at least two NC axes defines an axial velocity with an absolute value greater than zero, and none of the at least two NC axes reverses direction or comes to a standstill.

2. The method according to claim 1, wherein the dressable grinding tool defines a dressable grinding wheel.

3. The method according to claim 2, wherein the grinding wheel defines a wheel profile defining a wheel profile cross section defining at least one local minimum and/or at least one local maximum, wherein the local minimum and/or local maximum are dressed in a continuous pass.

4. The method according to claim 1, wherein the grinding tool defines a dressable grinding worm.

5. The method according to claim 4, wherein the grinding tool defines a grinding worm defining a worm profile defining a worm profile cross section defining a plurality of local minima and/or local maxima, and wherein the dressing step includes dressing at least one local minimum and/or one local maximum in a continuous pass.

6. The method according to claim 1, wherein the grinding tool defines a profile defining a profile cross section defining at least one local minima and/or local maxima, and the step of generating relative movement includes generating two-dimensional axial movement using two of the at least two NC axes of the machine tool, and using a third of said at least two NC axes to define the dressing path as a three-dimensional dressing path.

7. The method according to claim 3, wherein the grinding tool defines a profile defining a profile cross section defining at least one local minima and/or local maxima, and the step of generating relative movement includes generating a two-dimensional axial movement using two of the at least two NC axes of the machine tool, and using a third of said at least two NC axes to define the dressing path as a three-dimensional dressing path.

8. The method according to claim 1, wherein one of the NC axes defines a linear axis.

9. The method according to claim 1, wherein one of the at least two NC axes defines a pivot axis or rotational axis.

10. The method according to claim 8, wherein one of the at least two NC axes defines a pivot axis or rotational axis.

11. The method according to claim 1, wherein at least one of the at least two NC axes define linear axes, wherein the axial velocity of each of the linear axes defines an absolute value of at least 1 m/s.

12. The method according to claim 11, wherein the absolute velocity is at least 10 m/s.

13. The method according to claim 1, wherein at least one of the at least two NC axes defines a rotational axis or a pivot axis, wherein each of the at least one of the at least two NC axes defining a rotational axis or pivot axis defines a rotational velocity or pivot velocity defining an absolute value of least 1*10.sup.6/s.

14. The method according to claim 13, wherein the absolute value of said rotational velocity or pivot velocity is at least 10*10.sup.6/s.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 schematically shows the fundamental problem of the present disclosure on the basis of two linear axes (prior art);

[0054] FIG. 2A schematically shows a grinding tool profile cross section of a grinding tool;

[0055] FIG. 2B schematically shows a side view of the grinding tool from FIG. 2A;

[0056] FIG. 2C schematically shows the grinding tool profile cross section from FIG. 2A having a dressing roller;

[0057] FIG. 2D schematically shows a side view of the grinding tool from FIG. 2C having the dressing roller in two positions;

[0058] FIG. 2E schematically shows a further side view of the grinding tool from FIG. 2C having the dressing roller in two positions;

[0059] FIG. 3 schematically shows a three-dimensional illustration of two dressing path profiles along a surface of the grinding tool.

DETAILED DESCRIPTION

[0060] Terms are used in conjunction with the present description which are also used in relevant publications and patents. However, it is to be noted that the use of these terms is merely to serve for better comprehension. The inventive concepts and the scope of protection of the claims are not to be restricted in the interpretation by the specific selection of the terms. The invention may be readily transferred to other term systems and/or technical fields. The terms are to be applied accordingly in other technical fields.

[0061] FIG. 1 has already been discussed at the outset to disclose a fundamental problem. In summary, a deviation 4 of the actual route 2 from the target route 1 can be avoided by avoiding a directional reversal of an NC axisaccording to FIG. 1 the Y axis. An implementation of the solution according to at least some embodiments means that the relevant grinding tool is dressed in such a manner that the target route does not have a local minimum for any of the participating NC axes in the Y direction and Z direction, although the profile cross section of the grinding wheel to be dressed has such a local minimum. A solution to this problem is disclosed by way of example on the basis of FIGS. 2A-2E and FIG. 3.

[0062] FIG. 2A shows a grinding tool profile cross section 10 of a dressable grinding tool 12. The grinding tool profile cross section 10 shown here can be a portion of a part of a profile cross section of a grinding worm, the profile cross section of which extends in the positive and negative Z direction over a multiple of the portions shown in FIG. 2A. The grinding tool profile cross section 10 shown here can be a portion of a profile cross section of a grinding wheel, which also extends further in the positive and negative Z direction beyond the portion shown in FIG. 2A. The grinding tool profile cross section 10 shown here can be the profile cross section of a grinding wheel.

[0063] The coordinate axis (Z axis) identified with Z represents, on the one hand, a coordinate of the Cartesian coordinate system X, Y, Z shown in FIG. 2A. On the other hand, Z represents an NC linear axis of a machine tool 14, which enables a linear and/or translational movement of the grinding tool 12 along the coordinate direction Z. This applies similarly to the axes X and Y, so that the Cartesian coordinate system X, Y, Z is not to be understood solely as a virtual reference system, but rather is spanned by three NC linear axes X, Y, Z oriented perpendicularly to one another.

[0064] The grinding tool profile cross section has a local minimum 16, which is illustrated in the side view according to FIG. 2B by the dashed circular line.

[0065] If this grinding profile 10 is now to be dressed using a form dressing roller 18 according to FIG. 2C, the form dressing roller 18 is typically moved two-dimensionally, i.e., exclusively within the Y-Z plane spanned by the Y axis and Z axis, specifically from a first contact point 20, toward a second contact point 22 located in the minimum 16, up to the contact point 24. The dressing path thus resulting, which is indicated by the hollow arrows, therefore identically images the profile cross section of the grinding tool 12 in the Y-Z plane. The linear axis Y passes through the described, disadvantageous directional reversal. The dressing path represented by the hollow arrows and contact points 20, 22, 24 is therefore not according to disclosed methods.

[0066] It is self-evident that the described dressing path represents a continuous pass along the profile of the grinding tool 12 and the contact points 20, 22, 24 are solely used as support points to illustrate the course of the continuous dressing path. The relative movement could alternatively extend proceeding from the contact point 24 via the contact point 22 toward the contact point 20.

[0067] A three-dimensional dressing path 26 is now used to dress the grinding tool 12.

[0068] For this purpose, a movement in the X direction is additionally superimposed on the movement in the Y direction and Z direction. In this case, a dressing path 26, which is represented by the solid arrows and the contact points 28, 30, 32, does not comprise a local minimum. The dressing path can therefore be traveled along continuously without directional reversal and standstill of one of the linear axes X, Y, Z, wherein nonetheless the local minimum of the profile cross section 10 is dressed in a continuous pass.

[0069] In other words, the form dressing roller 18 is additionally moved along a profile of the grinding wheel R(Z) in the circumferential direction of the grinding tool, as indicated by the angle .

[0070] A method for dressing the grinding tool 12 by means of the machine tool 14 is therefore carried out, having the following method steps.

[0071] Providing the dressable grinding tool 12; dressing the grinding tool 12 by means of the form dressing roller 18, wherein the tool profile 10 to be generated on the grinding tool 12 is formed by a contact between the rotating grinding tool 12 and the rotating form dressing roller 18 along a dressing path 26, wherein a travel along the dressing path 26 takes place automatically with the aid of three NC axes X, Y, Z of the machine tool 14, which generate a relative movement between the rotating grinding tool 12 and the rotating form dressing roller 18; and wherein it is provided during the travel along the dressing path 26 and while the form dressing roller 18 is in forming contact with the grinding tool 12 that each of the NC axes X, Y, Z generating the relative movement between the rotating grinding tool 12 and the rotating form dressing roller 18 has an axial velocity, the absolute value of which is greater than zero, wherein none of these NC axes X, Y, Z carries out a directional reversal or comes to a standstill.

[0072] FIG. 2E illustrates three positions of the form dressing roller 18, which the dressing path 26 assumes in the continuous forming contact with the grinding tool in an overview illustration.

[0073] A comparison of a two-dimensional dressing path and the three-dimensional dressing path according to disclosed methods is shown in FIG. 3. The form dressing roller is not shown in FIG. 3 to improve the comprehensibility.

[0074] The hollow circles and arrows again represent a two-dimensional dressing path along the shaded surface of the grinding tool 12 to be dressed and the solid circles and arrows represent the dressing path for carrying out methods disclosed herein. R(z) is the radius of the grinding tool.

[0075] To illustrate the required movement routes of the linear axes X, Y, Z for the two-dimensional and the three-dimensional dressing path, the dressing paths have been projected on the Y-Z plane and the X-Z plane. It is apparent that the Y axis for the two-dimensional dressing path has to carry out a directional reversal to approach point 24 from the point 22. Furthermore, it is recognizable that no movement of the X axis is required for the two-dimensional dressing path. The profile of the grinding tool 12 is therefore dressable in a two-dimensional movement.

[0076] According to at least some embodiments, the dressing path 26 is selected according to the filled circles 28, 30, 32, wherein the dressing path 26 does not comprise a local minimum in its projection on the Y-Z plane and the X-Z plane. Each of the participating linear axes X, Y, Z is therefore exclusively moved in one direction, so that the dressing path 26 is traveled along without standstill or directional change of one of the NC axes X, Y, Z generating the relative movement between the form dressing roller and the grinding tool.

[0077] Therefore, the following condition can be established to determine a dressing path according DY/DZ<=0 and DX/DZ>=0:

[0078] as long as DR/DZ<=0: X=0, Y(Z)=R(Z), Z=Z(T), and YMIN=Min(Y(Z));

[0079] if DR/DZ>0: X(Z)=SQRT(R.sup.2(Z)YMIN.sup.2), Y(Z)=YMIN, Z=Z(T), wherein T corresponds to the processing time, so that Z functions as a guide axis for the synchronization of the participating NC axes.

[0080] The arrangement of three linear axes X, Y, Z corresponding to a Cartesian coordinate system is to be understood solely as an example and is used to illustrate the fundamental principle of the invention.

[0081] According to at least some embodiments, the method can be implemented with the aid of linear axes which are arranged inclined and/or skewed in relation to one another, i.e., for example, are not arranged perpendicularly to one another. Alternatively or additionally, pivot and/or rotational axes can be used.

[0082] In this case, the relative arrangement of the respective NC axis or to what extent the relevant NC axis effectuates a rotational and/or translational relative movement is not decisive, but rather that the condition required is met that during the travel along the dressing path and while the form dressing roller is in forming contact with the grinding tool, it is provided that each of the NC axes generating the relative movement between the rotating grinding tool and the rotating form dressing roller has an axial velocity, the absolute value of which is greater than zero, wherein none of these NC axes carries out a directional reversal or comes to a standstill.

[0083] While the above describes certain embodiments, those skilled in the art should understand that the foregoing description is not intended to limit the spirit or scope of the present disclosure. It should also be understood that the embodiments of the present disclosure described herein are merely exemplary and that a person skilled in the art may make any variations and modification without departing from the spirit and scope of the disclosure. All such variations and modifications, including those discussed above, are intended to be included within the scope of the disclosure.