METHOD FOR INSPECTING A DRESSABLE WORM GRINDING WHEEL

Abstract

A method for inspecting a dressable worm grinding wheel, having the following method steps: providing a dressable worm grinding wheel in a machine tool, wherein the worm grinding wheel has at least one worm thread and wherein the machine tool comprises a dressing tool for dressing the worm grinding wheel; traveling along a thread head of the worm thread in contact with a region of the dressing tool; measuring and analyzing at least one signal during the travel along the thread head, which is characteristic for the contact between the dressing tool and the thread head of the worm thread, such as a contact force, a displacement, a structure-borne noise, a power consumption of a drive, or the like.

Claims

1. A method comprising: chucking a dressable worm grinding wheel in a machine tool, wherein the worm grinding wheel defines at least one worm thread defining a thread head; chucking a dressing tool in the machine tool, wherein the dressing tool is adapted to dress the worm grinding wheel; moving a surface of the dressing tool in contact with and along the thread head of the worm thread; and during the moving step, measuring and analyzing at least one signal representing a characteristic of said contact between the dressing tool and the thread head of the worm thread.

2. The method according to claim 1, wherein said surface defines an outer-diameter-side surface of the dressing tool.

3. The method according to claim 1, wherein said analyzing step includes comparing the at least one signal to a reference signal.

4. The method according to claim 3, further including automatically determining a thread number of the worm grinding wheel, a thread direction of the worm grinding wheel, and integrity of the thread head of the worm thread of the worm grinding wheel during the moving, measuring, and comparing steps.

5. The method according to claim 1, including performing the moving step after the chucking of the worm grinding wheel; after scanning the worm grinding wheel; after dressing the worm grinding wheel with the dressing tool; and/or before grinding machining with the worm grinding wheel a workpiece of a series of workpieces.

6. The method according to claim 1, wherein the worm grinding wheel defines at least two worm threads, and the method includes sequentially performing the moving step and the measuring step with each of the at least two worm threads.

7. The method according to claim 1, wherein the dressing tool defines a disk-shaped dressing roller defining a V-shaped or a trapezoidal profile.

8. The method according to claim 1, wherein the dressing tool defines a multi-groove dressing roller adapted to simultaneously dress multiple worm threads, and during the moving step, an axis of rotation of the multi-groove dressing roller is oriented inclined relative to an axis of rotation of the worm grinding wheel.

9. The method according to claim 1, wherein the method further includes, when a deviation of the measured at least one signal from a reference signal therefor exceeds a predetermined maximum deviation, or an analysis of the at least one signal shows one or more anomalies: preventing grinding machining of a workpiece with the worm grinding wheel; informing an operator; adapting a shift strategy for the grinding machining; and/or dressing the worm grinding wheel with the dressing tool.

10. The method according to claim 9, wherein the one or more anomalies include at least one local maximum, at least one local minimum, and/or a at least one worm gear thread interruption

11. The method according to claim 2, wherein said analyzing step includes comparing the at least one signal to a reference signal.

12. The method according to claim 11, further including automatically determining the thread number of the worm grinding wheel, the thread direction of the worm grinding wheel, and the integrity of the thread head of the worm thread of the worm grinding wheel during the moving, measuring, and comparing steps.

13. The method according to claim 2, including performing the moving step after the chucking of the worm grinding wheel; after scanning the worm grinding wheel; after dressing the worm grinding wheel with the dressing tool; and/or before grinding machining with the worm grinding wheel a workpiece of a series of workpieces.

14. The method according to claim 3, including performing the moving step after the chucking of the worm grinding wheel; after scanning the worm grinding wheel; after dressing the worm grinding wheel with the dressing tool; and/or before grinding machining with the worm grinding wheel a workpiece of a series of workpieces.

15. The method according to claim 4, including performing the moving step after the chucking of the worm grinding wheel; after scanning the worm grinding wheel; after dressing the worm grinding wheel with the dressing tool; and/or before grinding machining with the worm grinding wheel a workpiece of a series of workpieces.

16. The method according to claim 2, wherein the worm grinding wheel defines at least two worm threads, and the method includes sequentially performing the moving and measuring step for each of the at least two worm threads.

17. The method according to claim 3, wherein the worm grinding wheel defines at least two worm threads, and the method includes sequentially performing the moving and measuring step for each of the at least two worm threads.

18. The method according to claim 2, wherein the dressing tool defines a disk-shaped dressing roller defining a V-shaped or a trapezoidal profile.

19. The method according to claim 3, wherein the dressing tool defines a disk-shaped dressing roller defining a V-shaped or a trapezoidal profile.

20. The method according to claim 1, wherein the at least one signal represents (i) a contact force between the dressing tool and the worm grinding wheel, (ii) a relative displacement between the dressing tool and the worm grinding wheel, (iii) an absolute displacement of the dressing tool and/or the worm grinding wheel; (iv) a noise of the dressing tool and/or the worm grinding wheel generated during the moving step, and/or (v) a power consumption of a drive driving the dressing tool and/or the worm grinding wheel during the moving step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Exemplary embodiments, which are understood not to be limiting, will be described in greater detail hereafter with reference to the drawings.

[0056] FIG. 1 schematically shows a worm grinding wheel and a gear wheel to be ground;

[0057] FIG. 2 schematically shows a worm grinding wheel and a dressing tool traveling along a worm thread;

[0058] FIG. 3 schematically shows the worm grinding wheel and the dressing tool of FIG. 2 in a subsequent position;

[0059] FIG. 4 schematically shows a multi-thread worm grinding wheel and a multi-groove dressing tool.

DETAILED DESCRIPTION

[0060] FIG. 1 shows a worm grinding wheel 2 and a gear wheel 4 to be ground. For fine machining of the tooth flanks 6 of the gear wheel 4, the worm grinding wheel 2 and the gear wheel 4 execute a coupled generating grinding movement in a known manner.

[0061] Before the grinding of the gear wheel 4, the worm grinding wheel 2 has been dressed to generate a shaping profile 8 of the worm grinding wheel. The profile 8 comprises a single worm thread 10 in the present case, which is wound in a spiral around a cylindrical middle part 12 of the worm grinding wheel

[0062] The worm thread 10 has a left flank 14, a right flank 16, and a thread head 18 connecting the flanks 14, 16. Like the flanks 14, 16, the thread head describes a spiral path wound around the cylindrical middle part 12 and the axis of rotation R of the worm grinding wheel 2.

[0063] The method according to at least some embodiments is described hereafter with reference to FIGS. 2, 3, and 4.

[0064] A method for inspecting the dressable worm grinding wheel 2 shown in FIG. 1 is carried out. For this purpose, the worm grinding wheel 2 is firstly provided in a machine tool 20, wherein in the present case it is a gearing grinding machine.

[0065] The machine tool 20 has a dressing tool 22 for dressing the worm grinding wheel 2.

[0066] To check the thread number, the thread direction, and the integrity of the thread head 18, the thread head 18 of the worm thread 10 is traveled along in contact with an outer diameter of the dressing tool 22, in the present case an outer-diameter-side surface 24 of the dressing tool 22. In this case, this involves continuous rolling of the essentially cylindrical outer surface 24 of the dressing tool 22 on the spiral path surface which the thread head 18 describes.

[0067] It is obvious that in addition to the trapezoidal profile of the dressing tool shown here, according to alternative exemplary embodiments, a dressing tool having V-shaped or rounded profile can be used.

[0068] The relative movement between the dressing tool 22 and the worm grinding wheel 2 is indicated by the directional arrows. The disk-shaped dressing tool 22 and the worm grinding wheel 2 thus rotate in opposite directions, wherein the dressing tool 22 is moved axially along the slope of the worm thread 18.

[0069] During the travel along the thread head 18, signals are measured which are characteristic for the contact between the dressing tool and the thread head of the worm thread, for example a contact force, a displacement, a structure-borne noise, and the power consumption of the drives.

[0070] The contact force between the dressing tool 22 and the thread head 18 is measured during the travel along the thread head. If a sudden drop of the contact force results because the dressing roller 22 rolls over damage 26, 28 of the thread head 18 (cf. FIG. 2), the damage 26 or 28 can be detected. In this case, for example, it can be predetermined that a deviation of +/ 10% of a predetermined target contact force, which forms the reference, triggers an error message or interruption of a program sequence.

[0071] In a similar manner, a target axial distance between the axis of rotation, a target structure-borne noise excitation during the travel along, or a target power consumption of the axial drives can be used to form a reference for the travel along the thread head and to use deviations thereof as an indication of damage to the thread head.

[0072] The measured signal is accordingly compared to an above-described reference to recognize damage of the thread head.

[0073] It is apparent that the above parameters are similarly suitable for detecting an incorrect thread number or thread direction of the worm grinding wheel, for which a contact between the dressing roller and the worm grinding wheel would break away completely, since the dressing roller travels along a predetermined target path of a target worm grinding wheel geometry having correct thread direction and thread number.

[0074] The method is carried out completely automatically in the present case, so that the thread number of the worm grinding wheel 2, the thread direction of the worm grinding wheel 2, and the integrity of the thread head 18 of the worm thread 10 of the worm grinding wheel 2 are checked automatically by the steps of traveling along, measuring, and comparing.

[0075] The travel along the thread head 18 of the worm grinding wheel 2 is performed in the present case as an additional work step after dressing of the worm grinding wheel 2 and before grinding machining of a workpiece of a series of workpieces to be manufactured, for example before every grinding machining of a workpiece of a series of workpieces to be manufactured.

[0076] FIG. 4 shows a variant of the method according to at least some embodiments in which a worm grinding wheel 38 has three threads 32, 34, 36, with a respective thread head 38, 40, 42. The worm threads 32, 34, 36 are checked sequentially here by a separate pass of the travel along and measuring being performed for every thread head 32, 34, 36.

[0077] A dressing tool 44 is used for this purpose, which is a multi-groove dressing roller 44 for simultaneously dressing the worm threads 32, 34, 36. An axis of rotation A of the multi-groove dressing roller 44 is oriented inclined in relation to the axis of rotation R of the worm grinding wheel 30 during the travel along a respective thread head 38, 40, 42 of a respective worm thread 32, 34, 36, wherein in the present case the travel along the thread head 38 of the worm thread 32 is shown by way of example.

[0078] Damage 46 of the thread head 40 of the worm thread 34 is therefore first recognized when the thread head 40 of the worm head 34 is traveled along or scanned in a separate pass using the dressing tool 44, while the damage 48 of the thread head 38 of the worm thread 32 is recognized in the pass of the dressing tool 44 along the spiral path of the thread head 32 shown in FIG. 4.

[0079] For the case that, for one of the worm grinding wheels 2, 30 shown, a deviation of the measured signal from the reference signal exceeds a predetermined maximum deviation, in the present case one or more of the following steps are carried out: interrupting a program sequence before grinding machining of a workpiece to be ground; informing an operator; adapting a shift strategy for the grinding machining; dressing the worm grinding wheel.

[0080] 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.