METHOD FOR ROLLING HARD-FINE MACHINING OF A TOOTHING OF A WORKPIECE BY MEANS OF A GRINDING TOOL

Abstract

A method for rolling hard-fine machining of a toothing of a workpiece by a grinding tool, in which the grinding tool is mounted on a tool spindle and rotates while the grinding tool engages with the toothing. The grinding tool is guided relative to the toothing during machining to grind the toothing over its width. The grinding tool rotates at a non-constant rotational speed during its engagement with the toothing at least over a portion of the width. The rotational speed of the grinding tool during its engagement with the toothing has a constant basic value on which an additionally time-varying rotational speed function is superimposed, or the rotational speed of the grinding tool during its engagement with the toothing increases or decreases continuously or non-continuously over the entire width of the toothing or increases or decreases continuously or non-continuously over portions of the width of the toothing.

Claims

1-7. (canceled)

8. A method for rolling hard-fine machining of a toothing of a workpiece by means of a grinding tool, in particular by means of a grinding worm, in which the grinding tool is mounted on a tool spindle and rotates about the tool axis while the grinding tool is in engagement with the toothing, wherein the grinding tool is guided relative to the toothing during the machining in order to grind the toothing over its width, and wherein the grinding tool rotates at a non-constant rotational speed during its engagement with the toothing at least over a portion of the width, wherein the rotational speed of the grinding tool during its engagement with the toothing has a constant basic value on which an additionally time-varying rotational speed function is superimposed, wherein the time-varying rotational speed function is periodic or wherein the time-varying rotational speed function has a stochastic character.

9. The method according to claim 8, wherein the feed rate of the grinding tool changes relative to the toothing over the width of the toothing.

10. The method according to claim 8, wherein the grinding tool is shifted in the direction of the tool axis over at least a portion of the width during its engagement with the toothing.

Description

[0024] The figures show embodiments of the invention.

[0025] FIG. 1 shows a perspective view of a grinding worm used to grind the toothing of a workpiece,

[0026] FIG. 2a,

[0027] FIG. 2b,

[0028] FIG. 2c,

[0029] FIG. 2d and

[0030] FIG. 2e schematically show the progression of the rotational speed of the grinding worm over time during the grinding process for five different embodiments of the invention.

[0031] FIG. 1 shows an example of a generating hard finishing operation on a workpiece 2 with a toothing 1 by generative grinding with a grinding worm 3, which machines the flanks of the toothing 1 with its abrasive surfaces 4 of the individual worm threads. The grinding worm 3 rotates around the tool axis a and is in the illustrated engagement with the toothing 1. Accordingly, the workpiece 2 rotates simultaneously (and coupled via an electronic gearbox) around the workpiece axis b.

[0032] Here, the grinding worm 3 is moved relative to the workpiece 2 in the direction of the workpiece axis b at a feed rate v in order to grind the toothing 1 over the entire width B of the toothing 1.

[0033] In this respect, the grinding process described corresponds to the state of the art.

[0034] It is important to note that the tool, i.e. the grinding worm 3, is now not driven at a constant rotational speed as usual, but at a non-constant rotational speed n.

[0035] This is outlined for five example cases in FIGS. 2a, 2b, 2c, 2d and 2e.

[0036] FIG. 2a shows that the rotational speed n of the grinding worm 3 has a constant base value over time (and thus also over the width of the toothing due to the given feed rate), which is superimposed with a sinusoidal curve.

[0037] According to FIG. 2b, it is also possible for the rotational speed n to begin with a starting value and increase over time. Accordingly, grinding can begin with a starting speed, which then increases steadily over the width of the toothing (as shown in FIG. 2b) or decreases steadily. A linear progression can be provided for the increase or decrease in rotational speed, but also a non-linear progression.

[0038] FIG. 2c illustrates that a stochastic or randomly selected function curve is superimposed on a constant base value for the rotational speed. This can be white noise in particular.

[0039] According to FIG. 2d, the grinding process begins with a starting rotational speed, which then increases to approximately the centre of the width of the workpiece, only to drop back to the original value by the end of the workpiece.

[0040] Finally, FIG. 2e shows a process in which grinding starts at a rotational speed that increases (disproportionately or exponentially) over time and thus over the width of the toothing.

[0041] In addition to the described change in tool speed n, the feed speed v can be selected to be non-constant. Any progression is also possible here.

[0042] Finally, another additive option is to shift the grinding worm 3 during the machining of the toothing 1, i.e. to move it slightly in the direction of the tool axis b. Any course can also be specified for this movement.

[0043] As described, in addition to a constant change (also: in addition to a constant acceleration) of the input variables (rotational speed, feed, shift movement), any modulation of the aforementioned input variables is also conceivable. For example, this can be set via the order and amplitude (indirect phase position (decimal point order)). An acceleration can also be superimposed on this. The order and amplitude can be varied via the stroke (i.e. via the width of the toothing). The modulation can be free of a clear system (e.g. white noise). Similarly, the change in speed can be dynamic. A simultaneous or staggered combination of dynamic influencing of the input variables (rotational speed, feed, shift movement) is also possible.

[0044] Another (albeit equivalent and equally effective) realisation of the proposed solution for changing the rotational speed of the tool is to influence the electronic gearbox, which realises synchronous, coordinated rotation of the tool 3 about the tool axis a and the workpiece 2 about the workpiece axis b. In the corresponding control algorithm, which establishes the synchronisation between axes a and b, a superimposition function of the type outlined in FIGS. 2a, 2b and 20 can be specified, for example, so that the synchronisation between the axes is not as high as possibleas is usually the aimbut rather a targeted deviation from it. This can also achieve the stated objective.

LIST OF REFERENCES

[0045] 1 Toothing [0046] 2 Workpiece [0047] 3 Grinding tool (grinding worm) [0048] 4 Abrasive area [0049] a Tool axis (axis of the grinding worm) [0050] b Workpiece axis [0051] B Width of the toothing [0052] n Rotational speed of the grinding tool [0053] v Feed rate of the grinding worm relatively to the toothing