Apparatus for smoothing a toothing system and production process

Abstract

An apparatus for smoothing an inner toothing and/or an outer toothing of a component part. At least two radially adjustable smoothing gears, which engage in the inner toothing and/or outer toothing, are rotatably arranged inside the inner toothing and/or outside of the outer toothing. During smoothing, the component part is not firmly clamped but rather only rests loosely on a support. A thrust ring is provided at least at one of the smoothing gears for limiting axial movements of the component part, which occur during smoothing.

Claims

1. An apparatus for smoothing an inner toothing and/or an outer toothing of a component part, comprising: at least two adjustable smoothing gears configured engage in the inner toothing and/or outer toothing, the at least two adjustable smoothing gears are rotatably arranged inside the inner toothing and/or outside of the outer toothing, a thrust ring connected to at least one of the at least two adjustable smoothing gears and configured to limit axial movement of the component part, wherein the component part is not firmly clamped in the apparatus during smoothing.

2. The apparatus according to claim 1, wherein each of the at least two adjustable smoothing gears has a respective thrust ring.

3. The apparatus according to claim 1, wherein three smoothing gears are provided that are arranged offset relative to one another in each instance by 120.

4. The apparatus according to claim 1, wherein at least one smoothing gear is arranged on a movable slide.

5. The apparatus according to claim 3, wherein a first smoothing gear is arranged on a first slide and a second smoothing gear and a third smoothing gear are arranged on a second slide, wherein the first slide and the second slide are displaceable opposite one another.

6. The apparatus according to claim 5, wherein the second smoothing and the third smoothing gear are mounted in a rotatable and floating manner relative to the second slide.

7. The apparatus according to claim 5, wherein the first smoothing gear is rotatably mounted with respect to the first slide and configured to be driven in rotational direction.

8. The apparatus according to claim 1, wherein teeth of each of the at least two adjustable smoothing gears have different tooth profiles.

9. The apparatus according to claim 8, wherein a profile angle correction in the range of 030 and/or a profile crowning in the range of from 20 to +30 m is provided at one of the at least two adjustable smoothing gears at the tooth profiles thereof considered in vertical direction of the tooth.

10. The apparatus according to claim 8, wherein a flank angle correction in the range of 010 and/or a width crowning in the range of from 30 to +50 m is provided at one of the at least two adjustable smoothing gears at the tooth profiles thereof considered in horizontal direction of the tooth.

11. The apparatus according to claim 8, wherein tooth flanks of a first smoothing gear has a depth crowning.

12. The apparatus according to claim 11, wherein a tooth profile of a second smoothing gear has a root relief.

13. The apparatus according to claim 12, wherein a tooth profile of a third smoothing gear has a tip relief.

14. The apparatus according to claim 1, wherein the component part is a ring gear with an inner toothing or as a sun gear ring with an inner toothing and an outer toothing.

15. A method for producing an inner toothing and/or outer toothing at a component part, comprising forming the inner toothing and/or the outer toothing by a cutting process; machining the inner toothing and/or the outer toothing by soft-smoothing immediately following the forming, wherein the soft-smoothing is carried out with an apparatus comprising: at least two adjustable smoothing gears configured engage in the inner toothing and/or outer toothing, the at least two adjustable smoothing gears are rotatably arranged inside the inner toothing and/or outside of the outer toothing, a thrust ring connected to at least one of the at least two adjustable smoothing gears and configured to limit axial movement of the component part, wherein the component part is not firmly clamped in the apparatus during smoothing.

16. The method according to claim 15, wherein the soft-smoothing is carried out simultaneously in different zones of the tooth profile of the component part that adjoin one another.

17. The method according to claim 16, wherein a flank region between the tip and root of the tooth is smoothed as first zone.

18. The method according to claim 17, wherein the tip region of the tooth is smoothed as second zone.

19. The method according to claim 18, wherein the root region of the tooth is smoothed as third zone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiment examples of the invention are shown in the drawings and described more fully in the following. Further features and/or advantages can be gathered from the description and/or the drawings. The drawings show:

(2) FIG. 1 is a schematic view of an apparatus according to the invention for smoothing an inner toothing;

(3) FIG. 1B is a detail of the apparatus according to the invention from FIG. 1; and

(4) FIG. 2 is a further apparatus according to the invention for smoothing an inner toothing and an outer toothing.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(5) FIG. 1 shows a schematic top view of a first embodiment example of the invention, namely, an apparatus 1 for smoothing an inner toothing. The apparatus 1 comprises a first tool slide 2, referred to as slide 2 for the sake of brevity, which is movable in direction of arrow P1 and a second tool slide 3, referred to as slide 3 for the sake of brevity, which is movable in direction of arrow P2. A first smoothing gear A, referred to hereinafter as smoothing wheel A, is mounted on the first slide 2 around a rotational axis a which is arranged perpendicular to the drawing plane. A second smoothing gear B is arranged on the second slide 3 so as to be rotatable around a rotational axis b and a third smoothing gear C is arranged on the second slide 3 so as to be rotatable around a rotational axis c. The smoothing gears A, B, C are tools of the apparatus 1 and have hardened involute teeth (no reference numeral) on their circumference. The first smoothing gear A which has a rigidly arranged rotational axis a is driven by a motor, not shown. The rotational axes b, c of the second smoothing gear B and third smoothing gear C are arranged in a floating manner, i.e., they can follow the course of the tooth gap. A component part 4, the workpiece, which is formed as a ring gear 4 is arranged above the two slides 2, 3 and is freely disposed on a plate, not shown. The ring gear 4 has an inner toothing formed as an involute toothing that is machined by broaching. The inner toothing 4a is preferably formed as helical teeth produced by helical broaching, i.e., by a helical movement of the broaching tool. The smoothing gears A, B, C are arranged inside the ring gear 4 similar to planet gears in a planetary gearset, engage by their outer teeth in the inner toothing 4a of the ring gear 4 and accordingly also cause the freely disposed ring gear 4 to be centered. An adjusting device, not shown, preferably a pneumatic cylinder is arranged between the first slide 2 and the second slide 3 and moves the two slides 2, 3 apart so as to apply the required pressing force between the smoothing gears A, B, C and the inner toothing 4a.

(6) The smoothing process is soft-smoothing that proceeds in the following manner: The ring gear 4 is placed on the apparatus 1 immediately after the broaching process, i.e., in soft condition (without being surface-hardened). In so doing, the smoothing gears A, B, C are still in their retracted position, i.e., not engaged with the inner toothing 4athe slides 2, 3 are still moved together. After the ring gear 4 is positioned on the apparatus 1, the smoothing gears A, B, C are meshed to the inner toothing 4a by moving slides 2, 3 apart from one another; only a relatively small pressing force need be applied. The first smoothing gear A then drives the ring gear 4, while the second smoothing gear B and third smoothing gear C roll along the inner toothing 4a. Owing to the floating axes b, c, the smoothing gears B, C can follow the inner toothing 4a in an optimal manner.

(7) The toothing microgeometry of the three smoothing gears A, B, C can be varied to achieve optimal smoothing results in certain flank regions. Geometry variations of this type can be carried out in vertical direction of the tooth as profile angle correction (pressure angle corrections, preferably in the range of approximately 0 30), as profile crowning (preferably in the range of from 20 to +30 m) and as a combination of these parameters. In the horizontal direction of the tooth, these kinds of geometry variations can be carried out as flank angle corrections (preferably in the range of approximately 0 10), as width crowning (preferably in the range of from 30 to +50 m) and as a combination of these parameters. Additionally, variations in geometry in the vertical direction of the tooth and in the horizontal direction of the tooth can be combined or overlapped.

(8) Correspondingly, different profile corrections are provided at the teeth of the smoothing gears A, B, C in the embodiment example shown in FIG. 1. The tooth profile of the first smoothing gear A has a depth crowning; the tooth profile of the second smoothing gear B has a comparatively large root relief, and the tooth profile of the third smoothing gear C has a comparatively large tip relief. Therefore, the three smoothing gears machine or smooth different regions or zones of the inner toothing 4a, namely the flank middle, the root, and the tip. By the smoothing process, particularly profile peaks that occur on the surface of the inner toothing 4a as a result of the broaching process are leveled through deformation of the still soft material so as to provide an improved surface quality with increased material contact area. The toothing of the ring gear 4 can be hardened after the soft-smoothing.

(9) The axial drift effect in a helically toothed ring gear is effectively combatted in that a supporting ring limiting the axial movement of the ring gear is arranged at the smoothing gears which also have helical teeth. This will be explained more fully in the following referring to FIG. 1B. Another possibility for countering this effect and improving the machining results is to alternately reverse the rotating direction of the workpiece to be machined during smoothing.

(10) FIG. 1B shows a detail of the embodiment example of an apparatus according to the invention described with reference to FIG. 1. FIG. 1B shows a cross section through the apparatus 1 provided for smoothing an inner toothing and/or outer toothing. The workpiece which is constructed in this case as ring gear 4, by way of example, lies loosely on a preferably hardened support 5 and, as is indicated by arrow P1, is meshed to the smoothing gears, only one of which smoothing gear A with its rotational axis ais shown in cross section. The rotational axis of the ring gear 4 is designated by d.

(11) In case of a helically toothed workpiece, the radial pressing force F and the driving torque M give rise to a resultant axial force component that presses the workpiece on the support 5 or raises the workpiece from the support 5 depending on the rotational direction. A thrust ring 6, which is preferably fashioned from hardened steel, is fixedly connected to the smoothing gear A and limits possible axial backlash 7 to a few tenths of a millimeter. Preferably, only one of the smoothing gears is driven; in the present embodiment example, smoothing gear A is driven. The inclined position of the ring gear 4 resulting from the driving smoothing gear A, which is preferably rigidly mounted, can be compensated by a floating bearing support of the rest of the smoothing wheels. As discussed above, a regular change in rotational direction, for example, after every 360-degree revolution of the workpiece, is advantageous for uniform machining results.

(12) FIG. 2 shows a schematic top view of a second embodiment of the invention, namely, an apparatus 11 for smoothing an inner toothing and/or outer toothing. The same reference numerals, increased by ten, are used for similar parts. The apparatus 11 comprises a first slide 12 and a second slide 13 that can be moved toward or away from one another similar to the embodiment example according to FIG. 1. The first slide 12 has a driven smoothing gear Ai and the second slide 13 has two floating smoothing gears Bi, Ci. The workpiece, which is smoothed on the apparatus 11, is a component part 14 which is formed as a ring gear and sun gear and which has an inner toothing 14a and an outer toothing 14b. The inner toothing 14a is preferably produced by helical broaching, i.e., cutting, while the outer toothing 14b is produced, for example, by milling, i.e., likewise by cutting. For purposes of smoothing the outer toothing 14b, a drivable smoothing gear Aa is rotatably arranged on the first slide 12 and a smoothing gear Ba as well as a third smoothing gear Ca are rotatably arranged on the second slide 13. The outer teeth of the smoothing gears Aa, Ba, Ca, also called smoothing wheels hereinafter, mesh with the outer toothing 14b of the component part 14. When smoothing the outer toothing 14b, as is shown in FIG. 2, the two slides 12, 13 are accordingly moved toward one another to generate the pressing force for the smoothing process. The two slides 12, 13 are subsequently moved apart so that the outer smoothing gears Aa, Ba, Ca disengage and the inner smoothing gears Ai, Bi, Ci mesh with the inner toothing 14a. The inner smoothing gears Ai, Bi, Ci and outer smoothing gears Aa, Ba, Ca are profile-corrected similar to the embodiment according to FIG. 1.

(13) Due to the different profile geometries of the smoothing wheels, different regions or zones of the tooth flanks of the workpiece are machined, which also results in reduced deformation forces. Due to the above-mentioned profile corrections, the smoothing gears acting as tools have only a reduced line contact with the tooth flanks of the workpiece. This ensures the highest possible area pressure and, therefore, optimal machining results over the entire tooth flank of the workpiece. As has already been mentioned, the teeth of the workpieces are machined in unhardened condition, i.e., immediately following upon the broaching process. The smoothing results are the outcome of a superposition of the pressure and the rolling-sliding movement of the involute toothing. Accordingly, material bulges and roughness peaks (profile peaks) are smoothed out and tooth damage is eliminated.

(14) The surface quality achieved by the disclosed apparatus and method can be characterized particularly by two surface parameters according to DIN EN ISO 4287, namely, the Rmr parameter, which describes the material contact area of the profile, and the Rsk parameter (skewness), which defines a surface having good bearing behavior, i.e., with a low profile peak count. The surface of the tooth flanks showed a significant improvement in these two parameters after soft-smoothing.

(15) Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.