WORKPIECE HOLDING DEVICE

Abstract

A workpiece holding device for holding a workpiece in a heat treatment system while the workpiece undergoes a thermal expansion and/or contraction includes at least two clamping units configured to apply a radial and/or an axial clamping force to the workpiece to hold the workpiece in the workpiece holding device in a predefined position and a drive unit configured to rotate the workpiece in the workpiece holding device. The at least two clamping units may be configured to adjust their position relative to the holding device to maintain the clamping force during the thermal expansion and/or contraction of the workpiece.

Claims

1. A workpiece holding device for holding a workpiece in a heat treatment system while the workpiece undergoes a thermal expansion and/or contraction, the workpiece holding device comprising: at least two clamping units configured to apply a radial and/or an axial clamping force to the workpiece to hold the workpiece in the workpiece holding device in a predefined position, and a drive unit configured to rotate the workpiece relative to the workpiece holding device.

2. The workpiece holding device according to claim 1, wherein the drive unit comprises a friction wheel or a friction roller configured to abut against the workpiece and frictionally engage the workpiece in order to rotate the workpiece.

3. The workpiece holding device according to claim 2, wherein a friction force between the drive unit and the workpiece is defined by a contact force between the drive unit and the workpiece.

4. The workpiece holding device according to claim 1, including at least three support units configured to support the workpiece.

5. The workpiece holding device according to claim 4, wherein the at least three clamping units each include a rotatable clamping cylinder abutting against the workpiece, and the support units each include a rotatable support cylinder on which the workpiece rests.

6. The workpiece holding device claim 5, wherein the drive unit is comprises an actively rotationally driven one of the at least two clamping cylinders.

7. The workpiece holding device according to claim 5, wherein the drive unit is comprises an actively rotationally driven one of the at least two support cylinders.

8. The workpiece holding device according to claim 5, wherein a first one of the at least two clamping cylinders or a first one of the at least three support cylinders is actively driven, and wherein a second one of the at least two clamping cylinders and a second one of the at least three support cylinders is passively driven by a rotation of the workpiece.

9. The workpiece holding device according to claim 8, including a first rotational speed measuring unit configured to measure a rotational speed of the drive unit, and a second rotational speed measuring unit is configured to measure a rotational speed of the second one of the at least two clamping cylinders or a rotational speed of the second one of the at least three support cylinders, and a controller configured to determine a rotational speed difference between the rotational speed of the drive unit and the rotational speed of the second one of the at least two clamping cylinders or a rotational speed difference between the rotational speed of the drive unit and the rotational speed of the second one of the at least three support cylinders.

10. The workpiece holding device according to claim 9, wherein the controller is configured to produce an output indicative of the rotational speed difference between the rotational speed of the drive unit and the rotational speed of the second one of the at least two clamping cylinders exceeding a predetermined value or indicative of a rotational speed difference between the drive unit and the rotational speed of the second one of the at least three support cylinders

11. The workpiece holding device according to claim 1, wherein a portion of the at least one clamping unit is biased against the workpiece with a predetermined abutment force and configured to maintain the predetermined abutment force as the workpiece thermally expands and/or thermally contracts.

12. The workpiece holding device according to claim 11, including a controller configured to set the predetermined abutment force.

13. The workpiece holding device according to claim 12, including a force measuring device operably connected to the controller and configured to measure the contact force.

14. The workpiece holding device according to claim 1, including: a main body portion supporting the at least two clamping units and the drive unit, and at least three support cylinders supported by the main body portion and configured to axially support the workpiece, wherein the drive unit comprises a friction wheel or a friction roller configured to abut against the workpiece and frictionally engage the workpiece in order to rotate the workpiece, wherein the at least three clamping units each include a rotatable clamping cylinder abutting against the workpiece, and wherein the at least three clamping units are configured to maintain a predetermined clamping force against the workpiece during the thermal expansion and/or contraction.

15. A method comprising: providing a workpiece holding device according to claim 1, placing the workpiece into the workpiece holding device, moving the at least two clamping units into abutment with the workpiece, and clamping the workpiece with a predetermined force, powering the drive unit to rotate the workpiece held by the at least two clamping units at a predetermined rotational speed, performing a heat treatment on at least a portion of the rotating workpiece, starting the thermal treatment, maintaining the predetermined clamping force during the heat treatment while the workpiece thermally expands and/or thermally contracts.

16. The method according to claim 15, wherein maintaining the predetermined clamping force comprises passively maintaining the predetermined clamping force.

17. The method according to claim 15, wherein maintaining the predetermined clamping force comprises actively maintaining the predetermined clamping force.

18. A workpiece holding device for holding a workpiece in a heat treatment system while the workpiece undergoes a thermal expansion and/or contraction, the workpiece holding device comprising: a main body portion, at least three support cylinders extending from the main body portion and configured to axially support the workpiece, and at least three clamping cylinders configured to apply a radial clamping force to the workpiece to hold the workpiece in the main body portion, and wherein a first one of the at least three clamping cylinders is configured to be actively driven to rotate the workpiece in the main body portion and all other ones of the at least three clamping cylinders are passively driven by contact with the workpiece, and wherein the at least three clamping cylinders are configured to move to maintain the radial contact force during the thermal expansion and/or contraction of the workpiece.

19. The workpiece holding device according to claim 18, wherein the at least three support cylinders are passively driven by contact with the workpiece.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 is a schematic plan view of an induction hardening system with a workpiece holding device according to a first exemplary embodiment of the present disclosure.

[0057] FIG. 2 is a schematic view of a workpiece holding device according to a second exemplary embodiment of the present disclosure.

[0058] FIG. 3 is a schematic view of a workpiece holding device according to a third exemplary embodiment of the present disclosure.

[0059] FIG. 4 is a schematic view of a workpiece holding device according to a fourth exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

[0060] In the following, identical or functionally equivalent elements are designated by the same reference numbers.

[0061] FIG. 1 schematically shows a plan view of an induction hardening system 100 that is designed to inductively harden a workpiece 2, e.g., a bearing ring, with the aid of an inductor 4. The induction hardening system 100 depicted in FIG. 1 is formed as a hardening system in which the inductor 4 always heats only one part of the workpiece 2 while the workpiece 2 is moved past the inductor 4. For this purpose the workpiece 2 is clamped into a main body portion 5 of a workpiece holding device 6 and moved along the inductor 4.

[0062] The workpiece holding device 6 includes clamping units 8-1, 8-2, 8-3 that are designed to hold the workpiece 2 in its position in a positionally accurate manner. For this purpose, the clamping units can be moved radially, axially, and/or tangentially in order to abut against the workpiece 2 and to secure its position. This radial, axial, and/or tangential movability of the clamping units also ensures that the clamping units can track or follow an expansion/contraction of the workpiece 2 induced by the heat treatment. For this purpose, movable elements (not depicted) can be provided on the clamping units; the movable elements are preloaded, for example, toward the workpiece and thus preferably abut against the workpiece with an adjustable clamping force.

[0063] Furthermore, FIG. 1 shows that in the exemplary embodiments depicted, the workpiece 2 lies against three support units 12-1, 12-2, 12-3.

[0064] Instead of now rotating the entire system 6 as in the prior art, according to the invention a drive unit 14 is furthermore provided that is designed to rotate the workpiece 2.

[0065] Here the drive unit 14 can be, for example, a friction wheel or a friction roller that acts directly on the workpiece 2 and sets it in rotation. In order to ensure that the movement of the workpiece 2 is not hindered or impeded by a friction against the clamping units 8 or support units 12, both the clamping units 8 and the support units 12 are advantageously equipped with rotatable elements. For this purpose, in the depicted exemplary embodiment of FIG. 1, the clamping units 8 include rotatable clamping elements in the form of clamping cylinders 10-1, 10-2, 10-3 that are rotatably supported and both facilitate the rotation of the workpiece 2 and form the above-described movable elements that apply the clamping force onto the workpiece 2.

[0066] In an analogous manner thereto, the support units 12 can also include rotatable support cylinders 16, in particular rotatable sleeves, that on the one hand provide a good contact surface of the workpiece 2 and an easy movability of the workpiece 2.

[0067] Of course, it is also possible to combine the clamping elements 10 and support cylinders 16.

[0068] The clamping unit 8, the support units 12, and/or the drive unit 14 can be moved radially, axially, circumferentially and/or tangentially in order to optimally abut against the workpiece 2. Furthermore, at at least one of the of the preferably multiple units 8, 12, 14, it is possible to attach at least one measuring device 13 that is configured to measure a contact force and/or clamping force and/or friction force between the clamping units and/or the support units and/or the drive unit, and the workpiece 2. Furthermore, a controller 15 can also be provided that interacts with the units 8, 12 and 14 such that the units 8, 12, 14 interact with the workpiece 2 with a predetermined contact force, clamping force, and/or friction force.

[0069] Instead of a separate drive device 14 as depicted in FIG. 1, one of the clamping units 8 and/or of the support units 12, in particular a rotatable clamping element 10 and/or a rotatable support cylinder 16, can also be configured as a drive unit 14.

[0070] Thus, for example, the clamping element 10 or the rotatable support cylinder 16 can itself be designed as friction wheel or friction roller that in turn acts directly on the workpiece 2 and sets it in rotation.

[0071] FIGS. 2 and 3 each show exemplary embodiments in which the clamping elements 10 are configured as clamping cylinders. Furthermore, FIGS. 2 and 3 show that a clamping element 10, in particular, for example, the clamping cylinder 10-1, is configured as an actively rotating clamping cylinder and thus as drive unit 14. The other clamping cylinders 10-2, 10-3 and 10-4 (see FIG. 3) here are merely passively driven via the friction with the rotating workpiece 2. Furthermore, it can be seen from FIGS. 2 and 3 that the clamping units 8 need not be distributed along the workpiece 2 at the angular distance, rather, non-uniform distributions are also possible.

[0072] Furthermore, as indicated in FIG. 2, at least one measuring unit 30, 32 can be provided that, for example, measures a contact force, friction force, and/or clamping force, and provides it to a controller 15 which, based on the measurement, controls the clamping units 8, support units 12, or drive unit 14, in order to maintain a predetermined clamping force, friction force, and/or contact force during the heat treatment, even with a thermal expansion and/or contraction of the workpiece 2.

[0073] Furthermore, the measuring units 30, 32 can be configured as rotational speed measuring units in which the measuring unit 30 determines a rotational speed of the clamping cylinder 10-1 configured as drive unit 14. In addition, a further rotational speed measuring unit 32 is provided on one of the passively rotating clamping cylinders, here clamping cylinder 10-2, that determines a rotational speed of the passively driven clamping units 10-2, 10-3. The measured rotational speeds can in turn be provided to a controller 15, wherein the controller is configured to determine a slippage of the workpiece from a rotational speed difference between the actively and passively driven clamping cylinders 10. With the aid of the rotational speed measurement, it can be determined whether there is sufficient friction force/contact force of the drive unit 14, or whether the clamping force applied by the clamping units 8 is sufficient to attach the workpiece sufficiently firmly in the workpiece receptacle. Thus, for example, the controller can be designed to control the drive unit and/or the clamping unit and/or the support unit in order to optimize the contact force or the clamping force, and to minimize the slippage.

[0074] In particular, when a predetermined rotational speed difference is exceeded, it is advantageous when the controller is furthermore designed to increase a contact force of the friction roller/of the friction wheel and/or a clamping force of the clamping units and/or to issue a notification about an increased slippage.

[0075] FIG. 4 shows a further exemplary embodiment, in which the rotatable support cylinder 16 of the support unit 12 is equipped with a friction wheel 18. Here the friction wheel 18 abuts against a radial outer surface 22 of the workpiece and can thus simultaneously exert a clamping force (see arrow) on the workpiece 2. Thus the friction wheel 18 also assumes the function of the clamping unit 8. During rotating of the sleeve about its longitudinal axis A, the friction wheel 18 is simultaneously rotated. Due to the abutment (friction) of the friction wheel 18 against the outer surface 22 of the workpiece, the rotational movement of the support cylinder 16 is also transmitted via the friction wheel 18 onto the workpiece 2 so that the workpiece 2 is also rotated. During rotating of the friction wheel 18 or of the support cylinder 16, the workpiece 2 is thus rotated by the support unit 12 and along the friction wheel 18. A combined clamping, contact and drive unit can thereby be provided.

[0076] Overall, by the moving of the workpiece 2 alone instead of the entire workpiece holding device, it can be achieved that the wear and also the energy expenditure during the operating of an induction system is significantly reduced, since only the workpiece itself, but no longer the entire work table, need be set into motion. This also makes it possible that a relative speed of the workpiece with respect to the inductor can be set particularly precisely, which in turn leads to an improvement of the hardening result.

[0077] As used herein, a controller may be a programmable hardware component that can be formed by a processor, a computer processor (CPU=central processing unit), an application-specific integrated circuit (ASIC), an integrated circuit (IC), a computer, a system-on-a-chip (SOC), a programmable logic element, or a field programmable gate array (FGPA) including a microprocessor.

[0078] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved workpiece holding devices.

[0079] Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

[0080] All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

REFERENCE NUMBER LIST

[0081] 100 Induction hardening system [0082] 2 Workpiece [0083] 4 Inductor [0084] 5 Main body [0085] 6 Workpiece holding device [0086] 8 Clamping unit [0087] 10 Clamping element [0088] 12 Support unit [0089] 13 Measuring device [0090] 14 Drive unit [0091] 15 Controller [0092] 16 Rotatable support cylinder [0093] 18 Friction roller [0094] 22 Outer surface of the workpiece