CH659414A5 - METHOD AND DEVICE FOR PRODUCING HARDENED GEARS. - Google Patents

Description

The invention relates to a method according to the preamble of claim 1 and a device for carrying out the method according to the invention.

A toothing is produced and hardened in a manner known per se by cutting or non-cutting shaping. Any inaccuracies in shape after hardening are corrected by grinding if necessary.

The hardened toothing produced in a known manner leaves something to be desired in terms of its resilience.

The invention has for its object in the sense of enabling higher resilience with smaller or at most the same weight of the gear to create improved hardened teeth in this regard.

To achieve this object, the method defined in claim 1 and a device for carrying it out are proposed.

The non-cutting generation of gears according to the well-known GROB-METHODS (see e.g. DE-PS 1 016 222) results in increased tooth root alternating load resistance and tooth flank strength compared to the cutting production of a toothing from the same material. During the subsequent hardening, however, these increased strengths are at least partially lost again, which is attributed to the recrystallization process.

While any toothing produced in the unhardened state can be rolled over using a special GROB process in order to eliminate inaccuracies in shape, the improvements in the strength values already mentioned are also subject to degradation during hardening.

Attempts have therefore been made to carry out this re-rolling while correcting the shape, even with hardened toothing, but this has led to damage or destruction of the toothing because the hardened outer layer separated from the softer core.

It has now surprisingly been found that in the cold rolling process according to the invention (without a change in macro shape), a significant improvement in the tooth base alternating load strength and the tooth flank strength can be achieved.

The rollers are preferably allowed to hit the workpiece in such a way that there is only a temporary deformation on the workpiece in the elastic deformation range of less than 0.1 mm.

Any grinding grooves that are present can be smoothed in the method according to the invention, so that a much smoother running of such toothings can be achieved, which is otherwise sought to be achieved by an additional (and not strength-improving) complex treatment.

It is advantageous if you completely roll through a tooth gap before turning the workpiece further,

that you can roll another tooth gap with the rollers of the same roller head. It is possible to work with a high roller head speed and many rollers in the roller head, which allows correspondingly high feed speeds of the workpiece. The turning movement after the end of the rolling of a tooth gap can then take place, to a certain extent, calmly, without bringing about any significant interruption. You can then roll the workpiece in the reverse feed direction in the next tooth groove, or (if that would be considered favorable) also return the workpiece longitudinally in the starting position and roll it in the same rolling direction. When rolling back and forth, you can work with the roller head running in the same direction or by reversing the direction of rotation of the roller head.

However, you can also work in advance according to the basic method of the GROB process, whereby after each roller attack not only advance along, but also make a rotation of the workpiece.

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The action of the roller on the workpiece can be designed particularly favorably if practically only the roller with the inherent kinetic energy is allowed to act on the workpiece. The force effect can be increased or decreased as required by increasing or decreasing the speed of the roller heads. An elastic or damping support of the roller on the roller head can also be provided in such a way that the roller can move away from the workpiece. Otherwise, even relatively small inaccuracies in the toothing, which do not interfere with operation, could give rise to excessive deformation of the workpiece if the infeed of the roller head is carried out in such a way that even deep spots are still reached.

If you have hardened teeth with a hardness of z. B. 58 to 63 HRC (Rockwell) according to the invention, one will advantageously use rollers whose hardness in the range of z. B. 64 to 68 HRC. It can be rolls made of HSS steel (high-speed steel, alloy tool steel) and / or hard materials such as hard metals.

Suitable for carrying out the method according to the invention is a device which has on the machine frame a workpiece holder which is displaceable along an axis and rotatable about this axis, the drives for displacement and rotation being able to be coupled independently or synchronously, depending on whether one or the other variant of the proceedings. Furthermore, the device has at least one roller head which can be rotatably driven, and synchronization with the workpiece drives can also be provided here to the required extent. At least one roller is rotatably mounted in each roller head, so that it can be moved to a limited extent in the radial direction of the roller head between a peripheral (outer) and an inner stop.

A plurality of roller heads and a plurality of rollers can be provided in each roller head, the latter in particular for the process variant with rolling through each tooth gap from end to end.

The device therefore ensures that the roller (s) is not driven rigidly into the workpiece when it comes into contact with the workpiece, but rather retreats, i.e. e.g. can rebound, elastic or damping means can be provided for this. So you never want to force the power transmission to the full extent via the machine frame, because this could lead to undesirable material displacements in the plastic area.

The invention is discussed below with reference to the purely schematic drawing, for example. Show it:

1 is a plan view of a device according to the invention,

FIG. 2 shows an enlarged mounting of a roller in the roller head compared to FIG. 1, and

FIGS. 3 to 5 each have a similar tooth space contour with a roller contour of various types shown therein. S A machine frame 1 can be seen in FIG. 1, on which a clamping slide 2 can be displaced along the workpiece axis A by a motor-driven screw spindle 3. The workpiece 4 (here a hardened gear) is held by the clamping device 5. The Spannvor-io direction 5 is rotatably mounted in the clamping slide 2 via a gear 6. The drives of the spindle 3 and the clamping device 5 can (but need not) be synchronized with one another and / or the drive of the roller heads 7. On the other hand, a certain coordination of the drive of the spindle 15 3 with the speed and number of rolls of the roller heads 7 is necessary so that the individual rolling processes can overlap sufficiently.

Each roll head 7 contains a multiplicity of rotatably mounted rolls 8 (whose rotatable bearing will be entered with reference to FIG. 2). Each roller head 7 is mounted in its roller head slide 9, the roller head slide being able to be moved toward or away from the workpiece 4 via its hydraulics 10. The theoretically maximum possible depth of engagement of the rollers 8 in the workpiece 4 can thus be set, while the actual depth of engagement due to the mounting of the rollers 8 in the slots 11 (FIG. 2) results practically only from their kinetic energy. The rollers are prevented from flying out of the slots 11 by the guide ring 12 indicated in FIG. 2, which is stationary on the roller head slide 9. The rollers 8 receive a rotation by rolling off their steering knuckles 80 on the guide ring 12 so that they arrive on the workpiece in a rolling manner and are not first set in rotation by the workpiece. This rolling movement 35 also has a stabilizing effect on the shown guide of the roller stub 80 in the slots 11.

If you consider the kinetic energy of the rollers to be insufficient, you can z. B. install springs, which can then also transfer a portion of the energy of the 40 roller head 7 to the rollers 8 and from these to the workpiece 4. It is essential, however, that no macro-shape change in the workpiece may take place permanently. The smoothing of sanding marks should not be seen as a macro-shape change. 45 Depending on which surface parts of the tooth gap 40 are to be rolled over, one can e.g. B. use one of the three roller profiles 81, 82, 83 or other roller profiles shown in FIGS. 3 to 5. This can also be important if it is not possible to roll over all the desired parts according to the invention at the same time with a roll profile, because otherwise local overstressing and / or too little machining can take place.

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Claims (10)

659414 PATENT CLAIMS 1. A method for producing hardened toothing, in which a toothing is produced or hardened by cutting or non-cutting, characterized in that a workpiece with the hardened toothing is moved along its axis and at the same time with at least one ring-like profiled, rotating in a rotating driven planetary head Machined roll from the outside, with each roll in rapid succession of sudden single rolling processes in the same and mainly in the longitudinal direction of the teeth in at least one tooth gap in such a way that successively performed rolling processes overlap in terms of their attack on the workpiece in the same tooth gap, whereby one in all tooth gaps outside the macro-deformation range, compressive stresses are generated in the workpiece. 2. The method according to claim 1, characterized in that the grinding grooves generated by grinding are smoothed. 3. The method according to any one of claims 1 and 2, characterized in that the radial depth of engagement of the roller in the workpiece material is less than 0.1 mm. 4. The method according to any one of claims 1 to 3, characterized in that the workpiece surface is temporarily deformed when the roller hits the workpiece within the elastic deformation range. 5. The method according to any one of claims 1 to 4, characterized in that during the rolling of a certain tooth gap, the workpiece is shifted longitudinally without rotation, whereupon after completion of the rolling of this tooth gap, a workpiece rotation takes place and then another tooth gap is rolled while the workpiece is moved longitudinally without rotation, continuing until all tooth gaps have been rolled. 6. The method according to any one of claims 1 to 4, characterized in that the workpiece is longitudinally displaced and rotated during rolling, so that successive rolling operations, which are performed with rolls of the same rolling head, are arranged on a helix on the workpiece. 7. The method according to any one of claims 1 to 6, characterized in that the force effect of each roller on the workpiece is predominantly given off from the kinetic energy of the roller itself. 8. The method according to any one of claims 1 to 7, characterized in that the force effect of each roller on the workpiece is determined at least partially as a function of the speed of the roller head. 9. Device for carrying out the method according to one of claims 1 to 8, which on a machine frame (1) along an axis (A) displaceable and about this axis (A) arbitrarily rotatable workpiece holder (5) and at least one with respect to this axis ( A) adjustable, rotatably drivable roller head (7) and at least one roller (8) rotatably mounted in the roller head (7), characterized in that the roller (8) in the roller head (7) is mounted so as to be movable to a limited extent in the radial direction. 10. The device according to claim 9, characterized in that a plurality of rollers (8) in each roller head (7) are arranged along a common trajectory.