METHOD FOR DRESSING A MULTIPLE THREAD GRINDING WORM

Abstract

A method for dressing a multiple thread grinding worm by a dressing tool, in which the abrasive surfaces of the individual threads of the grinding worm are successively profiled with the dressing tool. The dressing is carried out in at least two threads with different dressing parameters so that the profiling of the abrasive surfaces of the threads differ from each other. The dressing parameters are selected so that the abrasive surfaces of at least two threads, viewed in the direction of the helix of the thread, differ from one another, and/or that the abrasive surfaces of the individual threads are profiled by topological dressing. A plurality of linear dressing strokes are performed over the height of the abrasive surface. The dressing tool is guided in the radial direction of the grinding worm at predetermined distances. The distances are constant in each thread but differing in at least two threads.

Claims

1. A method for dressing a multiple thread grinding worm by means of a dressing tool, in which the abrasive surfaces of the individual threads of the grinding worm are successively profiled with the dressing tool, wherein the dressing is carried out in at least two threads with different dressing parameters so that the profiling of the abrasive surfaces of the threads differ from each other, wherein the dressing parameters are selected in such a way that the abrasive surfaces of at least two threads, viewed in the direction of the helix of the thread, differ from one another, and/or that the abrasive surfaces of the individual threads are profiled by topological dressing, wherein a plurality of linear dressing strokes are performed over the height of the abrasive surface, in which the dressing tool is guided in the radial direction of the grinding worm at predetermined distances, wherein the distances are constant in each thread but differing in at least two threads.

2. The method according to claim 1, wherein the dressing is carried out with different dressing parameters in all threads.

3. The method according to claim 1, wherein the grinding worm rotates at a rotational speed during the dressing process, wherein the rotational speed of the grinding worm during dressing of the abrasive surfaces of a thread differs in at least two threads.

4. The method according to claim 1, wherein the dressing tool is a dressing roller rotating at a rotational speed during the dressing process, wherein the rotational speed of the dressing roller during dressing of the abrasive surfaces of a thread differs in at least two threads.

5. The method according to claim 1, wherein the grinding worm rotates at a rotational speed during the dressing process and the dressing tool is a dressing roller which rotates at a rotational speed during the dressing process, wherein the ratio of the rotational speeds is constant during dressing of the abrasive surfaces of a thread, but differs in at least two threads.

6. The method according to claim 5, wherein the ratio of the rotational speed of the grinding worm and the rotational speed of the dressing roller differs between at least two threads by at least 5%, preferably by at least 10% and particularly preferably by at least 15%.

7. The method according to claim 1, wherein the distances between at least two threads differ by at least 5%, preferably by at least 10% and particularly preferably by at least 15%.

8. The method according to claim 1, wherein the grinding worm rotates during the dressing process and the dressing tool is a dressing roller which rotates during the dressing process, wherein the dressing is performed in one thread in synchronism of grinding worm and dressing roller and the dressing is performed in at least one other thread in counter-rotation of grinding worm and dressing roller.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0033] In the drawing:

[0034] FIG. 1 shows a perspective view of a multiple thread grinding worm which is dressed by a dressing roller,

[0035] FIG. 2 shows schematically for three threads of the grinding worm the procedure for dressing according to the state of the art,

[0036] FIG. 3 shows schematically for three threads of the grinding worm the procedure for topological dressing according to the state of the art,

[0037] FIG. 4 shows schematically for three threads of the grinding worm the procedure for dressing according to an embodiment of the invention, and

[0038] FIG. 5 shows schematically the procedure for topological dressing according to another embodiment of the invention for three threads of the grinding worm.

DETAILED DESCRIPTION OF THE INVENTION

[0039] FIG. 4 shows an example of an embodiment of the invention analogous to FIG. 2. The abrasive surface 3, which was profiled by means of the dressing roller 2, is shown schematically for three worm threads 4, 5 and 6 of the grinding worm 1 (see FIG. 1). It can be seen that the ratio of the rotational speed n.sub.R of the dressing roller to the rotational speed n.sub.S of the grinding worm is different in the three worm threads. In the first worm thread 4, said ratio n.sub.R/n.sub.S is 18, in the second worm thread 5 it is 14.4, and in the third worm thread 6 it is 12. Accordingly, different profiling results in the three worm threads 4, 5, and 6, since dressing was performed with different dressing parameters in the different threads.

[0040] In FIG. 5, analogous to FIG. 3, another embodiment of the invention is shown, whereby here the abrasive surface 3 was profiled by means of topological dressing. As can be seen from the three illustrations in FIG. 5 for the worm threads 4, 5 and 6, a different value was selected for the distance x (measured in the radial direction r of the grinding worm 1) of the individual linear dressing strokes in each case, so that the coverage of the profiling is different in the individual threads.

[0041] The proposed concept is therefore based on the fact that during dressing (in particular with a conventional combination dressing roller or with a flexible dressing roller) the rotational speed of the dressing tool and/or the rotational speed of the grinding tool or the path speed is selected differently in each thread of the worm, so that different dressing parameters are present. Thus, the impressions of the dressing roller and thus the topography on the shell surface of each worm thread will be different.

[0042] If the number of threads of the grinding worm and the number of teeth of the workpiece are not divisible by an integer (which corresponds to the intended and thus most frequent machining case), all the threads of the grinding worm are used in succession in a tooth space of the workpiece. Since all the worm threads have a different topography, the generation of the surface on the tooth flank becomes less periodic and more variable, especially in the flank line direction.

[0043] In a very advantageous way, the proposed process does not have any negative effect on productivity, since the desired changes (i.e. the change of dressing parameters) are only specified differently by the machine control.

[0044] In topological dressing (see FIG. 5), the degree of overlap is selected differently in each thread of the worm. As in the case of conventional dressing, the differences in tool topography are reflected in each thread, which is then reflected on the tooth flanks of the workpiece after grinding. However, in this case, the variability of the surface created in this way is more in the flank profile direction (i.e. it changes in the radial direction r).

[0045] The changed rotational speed ratio n.sub.R/n.sub.S or the changed distance x (i.e., the degree of overlap) need not, of course, be varied in descending order from thread to thread, as illustrated in FIGS. 4 and 5. An ascending trend or an entirely variable design can also be provided.

[0046] The change in dressing parameters from thread to thread is preferably varied in such a way that the best result is achieved with regard to the smooth running of the gear teeth.

[0047] Thereby, it is also possible that some threads of the grinding worm are machined with the same parameters and only one thread or several other threads are profiled with the changed dressing parameters.

[0048] While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.