Workpiece holding device and induction hardening system

Abstract

A workpiece holding device for holding a workpiece in a heat treatment system, in particular a hardening system for hardening at least a portion of a workpiece, the workpiece having a closed curved profile and having a substantially radial inner surface and a substantially radial outer surface, being holdable in the workpiece holding device so as to be rotatable about an axis of rotation and being heatable by means of a heating device, the workpiece being subjected to thermal expansion and / or contraction, the workpiece holding device having at least three support units designed such that the workpiece rests on the support units, and the workpiece holding device comprising at least three contact units designed to position the workpiece in the workpiece holding device at a predetermined radial position, two of the three contact units being designed as passive contact units, one of the three contact units being designed as an active contact unit, the active contact unit being designed to exert a radial clamping force on the workpiece.

Description

Technical Field

[0001] This invention relates to a workpiece holding device for holding a workpiece in a heat treatment system, in which the workpiece undergoes thermal expansion and / or contraction due to density differences generated in the structure during heat treatment or due to phase transformation. The invention also relates to an induction hardening system. Background Technology

[0002] For heat treatment of workpieces, such as heating or quenching, the workpieces must be securely and precisely positioned in the appropriate location within the processing facility to achieve very precise heat input in the processing zone and the subsequent defined quenching process. For this purpose, conventional clamping means, such as so-called three-jaw or four-jaw chucks, can be used. These chucks have three or four clamping jaws mounted on a worktable and grouped around the workpiece to be held. Before processing, the workpiece is clamped and held in these clamping jaws, where the jaws can be adjusted to compensate for thermal shrinkage and / or expansion, or for shrinkage and / or expansion caused by density differences during phase transitions within the structure. It is also known in such arrangements to move the entire worktable, along with the clamping jaws, past a fixed heat source (such as an inductor) to simplify the adjustment of the required heat supply lines.

[0003] However, a drawback of this device is that the force required to adjust the grippers may be too low due to thermal expansion or contraction to compensate for, or due to expansion or contraction caused by density differences resulting from phase transitions in the structure. Consequently, the grippers may no longer be in contact with the workpiece and therefore cannot hold it securely enough, or the force applied by the grippers may be too high, leading to workpiece deformation or unfavorable internal stress states. Furthermore, all grippers must be actuated, resulting in a very high control workload.

[0004] Another problem with the known apparatus is that the large mass to be moved, consisting of the table, clamping jaws, and workpiece, results in very high energy consumption and wear on the table's drive system, necessitating frequent replacement of table components or complete replacement of the drive. Furthermore, due to the large mass to be moved and the overall size of the apparatus, process parameters (such as the relative velocity between heat sources (e.g., inductors) and the workpiece) are limited, making it impossible to consistently achieve optimal heat input to the workpiece.

[0005] However, heat input and its distribution within the workpiece are extremely important to achieve the desired workpiece performance in the processing zone and to control the resulting dimensional and shape changes (workpiece deformation). In the case of induction heating, known ways influencing heat input and temperature distribution include, for example, the appropriate selection of process parameters or process design (electrical power, heating time, heating frequency, coupling distance between the inductor and the workpiece, inductor material, inductor design, targeted use of the magnetic field concentrator, workpiece material, initial conditions of the workpiece material, relative velocity of the workpiece to the inductor, etc.).

[0006] Therefore, the key component of heat treatment facilities and successful heat treatment is the workpiece holding device.

[0007] Therefore, the object of the present invention is to provide a workpiece holding device, particularly a workpiece clamping system, wherein the workpiece holding device preferably performs the following functions as a whole:

[0008] - Ensure the predetermined coupling distance between the inductor and the workpiece.

[0009] - Position the workpiece at a defined location;

[0010] - Keep the workpiece in a defined position throughout the entire process time, counteracting any forces (such as magnetic fields) acting on the workpiece.

[0011] - Ensure good reproducibility of heat treatment;

[0012] - It can perform heat treatment at all locations on the workpiece (inner, outer, top, and bottom sides);

[0013] - Prevent cracking;

[0014] - Minimizes workpiece distortion or deformation;

[0015] - To enable the workpiece to move safely at a defined speed, which can be changed during the process;

[0016] - Apply clamping force that can be changed during the process. Summary of the Invention

[0017] This objective is achieved by the workpiece holding device according to technical solution 1 and the induction hardening system according to technical solution 11.

[0018] The following describes a workpiece holding device for holding a workpiece in a heat treatment system, particularly a hardening system for hardening at least a portion of a workpiece, wherein the workpiece held in the workpiece holding device undergoes thermal expansion and / or contraction or expansion and / or contraction caused by density differences generated during phase transformation in the structure. In the following description, reference will be primarily made to thermal expansion or contraction, as a heat component is typically also present during phase transformation.

[0019] The workpiece itself has a closed curved profile and has a substantially radial inner surface and a substantially radial outer surface, and can be heated by means of a heating device, thereby undergoing thermal expansion and / or contraction. The workpiece is preferably designed to be rotationally symmetric, such as elements of sliding or rolling bearings, bearing rings, gears, bolts, sleeves, discs, etc.

[0020] To reduce wear on the components of the workpiece holder (especially due to its high quality) and optimize heat input to the workpiece, the workpiece held in the holder is mounted to be rotatable about a rotation axis. Since only the workpiece needs to be moved, rather than the entire unit consisting of the workpiece, table, clamping unit, and other equipment, a significant reduction in the weight of the moving components can be achieved, even for large workpieces. This, in turn, allows for more precise adjustment of process parameters (such as rotational speed), in addition to lower loads on the components and therefore less wear on the drive system components, and thus improved heat input to the workpiece. Furthermore, less energy is required to rotate the workpiece compared to conventional systems, resulting in reduced costs.

[0021] In addition, the workpiece holding device has at least three support units designed to support the workpiece and at least three contact units designed to position the workpiece at predetermined radial and axial positions within the workpiece holding device.

[0022] To simplify actuation and control and provide the most robust and operable heat treatment system possible, while also providing precise radial positioning of the workpiece within the heat treatment system, it is proposed to design two of the three contact units as passive contact units and one of the three contact units as an active contact unit, wherein the active contact unit is designed to actively apply radial clamping force to the workpiece.

[0023] It should be noted that, in the context of this application, the terms "open-loop control" and "closed-loop control" are not strictly technical jargon used in electrical engineering. Therefore, "control" is used to describe both situations.

[0024] Surprisingly, it has been shown that using only actively controllable contact units is sufficient to hold the workpiece in a predetermined position while still ensuring that the workpiece remains held and positioned in a defined radial position throughout the entire process time, even against any forces acting on the workpiece, such as the magnetic field from the inductor. Simultaneously, three contact units can be used to apply a particularly uniform clamping force to the workpiece and fix it in position with high precision. This also allows for setting a predetermined coupling distance between the inductor and the workpiece. This, in turn, enables excellent reproducibility of heat treatment. Because only three contact units are used, heat treatment can be easily performed at all locations on the workpiece (inner, outer, top, and bottom sides).

[0025] The radially adjustable active contact unit alone is sufficient to accommodate different workpiece sizes. This significantly simplifies workpiece mounting, as only one contact unit needs to be adjusted according to the workpiece size. It also ensures that the workpiece remains centered in the workpiece holder regardless of its size.

[0026] As an alternative, as shown in another advantageous exemplary embodiment, it is also preferable that, in order to adapt the workpiece holder to workpieces of different sizes, the three contact units themselves are designed to be radially movable, for example by means of an electric or hydraulic actuator, and to move toward the workpiece before heat treatment until the workpiece is securely held between the clamping units. However, during operation, two of the contact units are radially fixed and represent passive contact units, while the third active contact unit is also radially movable during operation, thereby securing the workpiece in its position with high precision and compensating for manufacturing tolerances during operation. Additionally, the active contact unit can be mounted such that it can be eccentrically displaced. This allows the active contact unit to follow the thermal expansion / contraction of the workpiece. Eccentric mounting allows both radial and tangential movement of the contact unit.

[0027] Furthermore, the following exemplary embodiments are advantageous, wherein each contact unit has a contact element designed to bear against the radial inner surface and / or radial outer surface of the workpiece, wherein the contact element of the passive contact unit is designed to be a passive contact element fixed in the radial direction during operation, and the contact element of the active contact unit is designed to be an active contact element movable in the radial direction during operation to apply a radial clamping force to the workpiece and fix the workpiece in its radial and axial positions with high precision.

[0028] With the aid of active contact elements, workpieces can be clamped using defined forces and defined points of force application. Furthermore, this allows for compensation for workpiece shrinkage or reduced workpiece growth due to thermal shrinkage in the temperature range of the phase transformation from ferrite / α-ferrite to austenite / γ-ferrite (A1 to A3 temperatures, approximately 740°C to 860°C depending on the steel, microstructure, and heating rate) and / or due to subsequent cooling. However, the active contact elements can also be used to monitor workpiece shrinkage or reduced workpiece growth due to volume increase during quenching in the phase transformation range from austenite / γ-ferrite to martensite and / or bainite / pearlite / ferrite (this temperature range for martensite formation is typically between approximately 400°C and 100°C, depending on the solution state and the steel).

[0029] Of particular advantage is that, when the workpiece is handled in a substantially circular manner, the active contact element is movable not only radially but also axially and / or tangentially. This allows for the absorption of thermal expansion / contraction of the workpiece during heat treatment and also allows for compensation of manufacturing tolerances, such as a certain degree of ovality of the workpiece during clamping. This adjustment is particularly advantageous for workpieces with closed curved profiles, such as components of sliding or rolling bearings, bearing rings, gears, bolts, sleeves, discs, etc.

[0030] Another embodiment provides axially acting hold-down devices that can also follow the axial direction of the workpiece's thermal expansion / contraction. These hold-down devices enable the workpiece to be securely held in place even with lightweight workpieces and strong magnetic fields from the induction coil.

[0031] According to another preferred exemplary embodiment, the three contact units in the workpiece holding device are arranged equidistantly from each other at an angle of substantially 120°. This makes it possible to generate a uniform contact force at all contact units.

[0032] However, as an alternative, it is also preferable that the contact units are arranged in the workpiece holding device such that an angle of less than or greater than 120° is formed between the passive contact units, and the active contact units are arranged at equidistant distances from the two passive contact units. This allows the two passive contact units to be fixed radially, regardless of the size of the workpiece. For larger workpieces, the angle between the two passive contact units is thus reduced, while for smaller workpieces, the angle is increased. However, the active contact units equidistant from the passive contact units ensure that a uniform clamping force is always applied to the workpiece.

[0033] According to another advantageous exemplary embodiment, at least one of the contact units is designed as a driven rotatable contact unit, which is driven by a drive unit and designed to rotate the workpiece held in the workpiece holding device. The driven rotatable contact unit can be an active contact unit and / or a passive contact unit. Preferably, all contact units (two passive contact units and an active contact unit) are driven.

[0034] Preferably, a single drive unit can be provided to drive at least one rotatable contact unit. This makes it possible to provide a workpiece holding device that is particularly easy to actuate.

[0035] Furthermore, the following exemplary embodiments are preferred, wherein at least one rotatable contact unit has a rotatable drive element, such as a friction wheel or friction roller, which is designed to bear against the workpiece with a determinable frictional force and interact with the workpiece in a frictional engagement manner to rotate the workpiece. This allows for a particularly simple and cost-effective drive for the workpiece.

[0036] Of particular advantage is that the frictional force applied between the drive element (especially the friction wheel or friction roller) and the workpiece is limited by the contact force applied directly between the active contact element and the workpiece and / or the indirect contact force between the passive contact element and the workpiece. This ensures optimized drive for the workpiece even in the event of thermal contraction or expansion.

[0037] A particularly advantageous aspect is that a measuring device (e.g., a pressure sensor) for determining the contact force is provided on at least one of the contact units (especially on the active contact unit). Another advantage is that, based on the measured contact force, the control unit can control the active contact unit such that the contact force, and therefore the frictional force, is optimized. This ensures that the workpiece is always driven under a constant force, even under conditions of thermal expansion or contraction or structural irregularities (such as imbalance). Damage due to excessive force acting on the workpiece is also avoided.

[0038] Furthermore, this ensures that slippage between the workpiece and the contact unit is minimized. The determined contact force also minimizes wear between the workpiece and the contact unit. This also minimizes workpiece torsion and / or prevents or minimizes workpiece plastic deformation. Additionally, the defined frictional force allows for precise adjustment of the rotational speed, making it possible, in particular, to allow the workpiece to rotate at a defined speed.

[0039] According to another advantageous exemplary embodiment, the contact unit has at least one measuring device for detecting changes (torsion) in shape and size during and after the heating process. The recorded data can also be used in subsequent machining processes to make workpiece-specific adjustments for the process. In a preferred exemplary embodiment, at least one contact unit (particularly an active contact element) has at least one force measuring device that interacts with a control unit and is designed to measure the contact force between the contact unit (particularly the active contact element) and the workpiece.

[0040] Another advantage is the preloading of the active contact elements. Preloading of the active contact elements can be achieved using mechanical preloading elements (such as springs). Mechanical preloading elements are easy to install and require no additional actuation, making the workpiece holding device easy to operate and generally inexpensive.

[0041] The mechanical preloading element can be at least one spring element that interacts with the active contact element and preloads the active contact element in the direction of the workpiece. The spring element can be, for example, a wire spring, a disc spring, a helical spring, and / or a leaf spring, but plastics (such as elastomers) can also be used.

[0042] Mechanical preloading can also be designed as a friction device, which only allows the active contact element to move when a certain coefficient of friction has been exceeded. This means that, based on the pressure applied to the moving element during heat treatment by causing the workpiece to expand / contract, the active contact element only moves when a certain threshold has been exceeded.

[0043] Instead of mechanical preloading devices, active contact elements can be preloaded using devices actuated via a control unit. Preloading can be applied, for example, by means of hydraulically, pneumatically, and / or electrically operated elements that follow thermal expansion / contraction or expansion / contraction caused by density differences generated in the structure during phase transitions. For example, the active contact element can be an oil- or gas-operated pressure damper.

[0044] By employing preloading actuated by the control unit, contraction / expansion can already be followed with exceptional precision. To further enhance the accuracy and sensitivity of the following, as mentioned above, the contact unit, support unit, and / or drive unit can be equipped with at least one force measuring device. This force measuring device interacts with the control unit and is designed to measure contact forces, clamping forces, and / or frictional forces. Based on the measured forces, the control unit can then actuate the contact unit, support unit, and / or drive unit to apply a uniform force to the workpiece during processing. The force measuring device also allows for adjustment of manufacturing inaccuracies when the workpiece is clamped in the workpiece holder, ensuring uniform pressure is achieved across the individual clamping units once the workpiece is clamped.

[0045] Alternatively, the control unit can also actuate the contact unit, support unit, and / or drive unit based on a pre-calculated numerical table to compensate for calculated and anticipated expansion / contraction. The numerical table can be determined empirically and / or stored in a database accessible to the control unit. This means the database can be stored internally within the control unit itself or in an external database.

[0046] In a preferred embodiment, the control unit can also respond to forces acting on the workpiece by the processing system and specifically increase or decrease the preload based on the measured force or in a predictive manner. For example, in the case of anticipated temporary electrical, mechanical, or magnetic forces acting on the workpiece, the current preload can be specifically controlled and increased or decreased by a preload value. This temporary superposition of controlled preload due to thermal expansion and controlled offset can preferably be turned on and off as needed. Here, the contact unit, support unit, and / or drive unit can also be actuated based on a numerical table to reliably absorb and / or compensate for calculated and anticipated forces on the workpiece. Furthermore, the control unit can be designed to switch from closed-loop control operation to open-loop control operation and correspondingly switch back from open-loop control operation to closed-loop control operation, in which the preload force is set based on measurements from a force measuring device (e.g., a force sensor), and in open-loop control operation, the preload force is set based on a numerical table. For example, the preload can be controlled to a specific preload pressure as much as possible or completely during thermal expansion, and the preload pressure can be increased to a fixed value during subsequent thermal contraction (such as rapid quenching).

[0047] The clamping force, contact force, and / or friction force set by a numerical table or based on values ​​in a numerical table may depend in particular on the expected temperature changes of the workpiece or the diameter changes measured or calculated tactilely or optically during the machining process in the workpiece.

[0048] According to another preferred embodiment, the contact element is designed as a sliding shoe, which preferably has contact surfaces that rest against the radially inner and / or radially outer surfaces, wherein the contact surfaces preferably have curvature adapted to the curvature of the radially inner and / or radially outer surfaces. This sliding shoe enables particularly precise guiding and uniform clamping of the workpiece, wherein the clamping force is distributed over a relatively large area. Particularly preferred is that the passive contact element is designed as a sliding shoe. This embodiment is particularly advantageous if any distortion during heat treatment (including due to the clamping force) is to be avoided.

[0049] According to another preferred exemplary embodiment, at least one of the contact elements is designed to rest against a rotatable contact element resting on the workpiece. Preferably, the axis of rotation of the contact element is substantially parallel to the axis of rotation of the workpiece. Of course, an axis of rotation that is inclined relative to the axis of rotation of the workpiece is also possible.

[0050] Alternatively, each support unit has at least one rotatable support element on which the workpiece rests, and the axis of rotation of the rotatable support element is preferably perpendicular to the axis of rotation of the workpiece. This reduces friction between the workpiece and the support element, allowing the workpiece to rotate rapidly within the workpiece holder. Additionally, it reduces energy consumption for rotating the workpiece.

[0051] Advantageously, all support elements are passively designed, meaning they rotate solely through the rotation of the workpiece. Particularly advantageous is the design of the support elements as spheres. This enables simple passive rotation. Furthermore, due to the point contact of the workpiece on the sphere, the sphere allows for virtually frictionless, reduced / no-slip installation of the workpiece during rotation and heat treatment.

[0052] Of course, at least one of the support elements can also be designed as a drive element, such as a friction wheel or friction roller, and actively driven. This can be provided as an alternative to or supplement to at least one driven contact element. It is particularly advantageous that all drive elements (whether they are support elements and / or contact elements) are driven by a single drive unit. Of course, each drive element can also be driven individually by a drive unit.

[0053] Furthermore, as indicated above, a preferred exemplary embodiment is one in which only one of the rotatable contact element and / or support element is actively driven, while the other two rotatable contact elements / support elements are passively rotated by the movement of the workpiece. This enables the workpiece to perform particularly low-friction and energy-efficient movements.

[0054] A particularly preferred exemplary embodiment is one in which all rotatable support elements are passively designed and rotate only with the rotation of the workpiece resting on the support element. Alternatively, the rotation of the workpiece is achieved via driven contact elements. It is also preferred that all contact elements or contact units are driven, regardless of whether they are designed as active or passive contact elements / units. The terms "active contact unit" and "passive contact unit" / "contact element" in the sense of this application refer to radial mobility and adjustability during operation, as described above.

[0055] As mentioned above, the driven contact element is preferably driven synchronously by a single drive unit.

[0056] According to another preferred exemplary embodiment, at least one speed measuring unit is also provided, which determines the speed of the drive unit or drive element. The drive unit or drive element may be implemented on a contact unit or contact element, and / or may also be implemented on a support unit or support element.

[0057] In addition, another speed measuring unit can preferably be set on one of the passive rotating contact element / support element, and determine the speed of the passive driven contact element and / or support element.

[0058] Furthermore, a control unit is preferably provided, which is designed to determine workpiece slippage based on the speed difference between the actively driven contact element / support element and the passively driven contact element / support element. In addition to the contact force determination described above, rotational speed measurement can also be used to determine whether there is sufficient frictional / contact force from the drive element, or whether the clamping force applied by the contact unit / contact element is sufficient to securely hold the workpiece in the workpiece holder. For example, the control unit can be designed to control the drive unit and / or the contact unit and / or the support unit to optimize the contact force or clamping force and minimize slippage.

[0059] Of particular advantage, the control unit is also designed to increase the contact force of the contact elements (such as friction rollers / friction wheels) and / or the clamping force of the contact units when the speed difference exceeds a predetermined speed difference, and / or to issue a message about the increase in slippage.

[0060] Alternatively, the rotation axes of the contact elements and / or support elements may be oriented parallel to the surface of the workpiece to be rotated. For example, when the workpiece moves, these rotatable contact elements / support elements may move passively along with the workpiece, thereby reducing friction during workpiece movement.

[0061] According to another advantageous exemplary embodiment, at least one of the contact element and / or support element has a cylindrical, conical, spherical, and / or ball-shaped form. The exact shape can depend on several factors. On the one hand, the shape can be adapted to the shape or curvature of the radially inner or outer surface (contact surface) and / or the shape or curvature of the axial support surface of the workpiece. Particularly preferred is that the rotating contact element / support element contacts the workpiece along a line. This achieves pure rotational motion between the rotating contact element(s) / support element and the workpiece without any slippage. However, shapes for minimal contact but with sufficient contact / support force can also be selected. The shape can also be selected based on rotational considerations. Furthermore, the contact unit / support unit can have different rotatable contact elements / support elements. Additionally, it can be proposed that the rotatable contact element / support element only has a friction liner or friction coating that provides active actuation.

[0062] According to another preferred exemplary embodiment, at least one of the contact elements / support elements is detachably fastened to an associated contact unit / support unit. The associated contact unit / support unit has a pin or rod to which the contact element / support element can be attached, and the contact element / support element is designed as a sliding sleeve. This allows for easy replacement of the contact element / support element, for example, adapting the contact element / support element to the workpiece to be processed and / or replacing the contact element / support element during maintenance work.

[0063] Furthermore, it is advantageous that the position of the replaceable contact / support elements can be adjusted as needed, particularly the radial distance of the replaceable support element from the center point of the workpiece retainer and / or the axial range of the contact element. This allows workpieces of different shapes and sizes (especially those with different diameters and / or different heights) to be accepted by the workpiece retainer.

[0064] According to another preferred exemplary embodiment, at least one contact unit and / or support unit further includes an adjustment device designed to adjust the angular position of the contact element and / or support element. This also allows the contact element / support element to be adapted particularly well to the geometry of the workpiece. For example, with the aid of the adjustment device, even for inclined radial surfaces, cylindrical contact elements / support elements can be used, and the contact element / support element guiding rotation on the workpiece still maintains line contact. Alternatively, a tapered sleeve can also be used here.

[0065] Furthermore, preferably, the rotatable contact element and / or support element is designed as a sleeve, which can be attached to the contact unit or support unit and has a straight or curved outer surface, particularly cylindrical, conical, spherical and / or annular shapes.

[0066] In particular, the following exemplary embodiment is preferred, wherein the contact element has a tapered shape that protrudes beyond the upper edge of the workpiece in the direction of the workpiece, such that the contact element functions not only as a radial contact element but also as an axially acting contact element. This axial contact ensures that the workpiece is held in the workpiece holder in the direction of the support unit, thus enabling the contact element to function as a pressing device.

[0067] Another aspect of the invention relates to an induction hardening system for hardening a workpiece having a closed curved profile, the workpiece having a substantially radial inner surface and a substantially radial outer surface. Furthermore, the induction hardening system includes a workpiece holding device as described above and an induction coil for heating the workpiece. The induction coil is designed to induce a current in the workpiece, and thus achieve a definable heat input in the workpiece to heat it. Particularly in the case of an induction hardening system, there is a need for a workpiece holding device that firmly holds the workpiece during the heating process while allowing for simple and robust control of the clamping force applied to the workpiece by the workpiece holding device, even in the event of anticipated thermal expansion or contraction. To this end, as discussed in detail above, the workpiece holding device has at least three contact units, wherein only one contact unit is designed as an active contact unit, which can be actively actuated to follow thermal expansion or contraction, while the other contact units are passively designed and do not move in the radial direction during operation.

[0068] Particularly preferred is that the inductor is positioned between two passive contact units. This means that the inductor only needs to be aligned with the workpiece to be processed once before the curing process, and can then be held in that position during the curing process, as no further radial displacement or only a very small radial displacement of the workpiece is expected between the fixed passive contact elements. This eliminates the need for active control of the inductor and adjustment based on the thermal expansion / contraction of the workpiece, which significantly simplifies the control of the induction curing system. Alternatively, the inductor can, of course, be calibrated and adjusted if desired.

[0069] According to another preferred exemplary embodiment, a laser measuring device is also provided, which is designed to determine the coupling gap between the induction coil and the workpiece. Furthermore, a control unit is provided for controlling the active contact unit, particularly the active contact element of the active contact unit, wherein the control unit is designed to control the contact force of the active contact unit, particularly the contact force of the active contact element, and / or the position of the inductor based on the coupling gap size determined by the laser measuring device, such that the coupling gap between the workpiece and the induction coil is substantially constant. This eliminates the need for active control of the inductor and allows for adjustment of the inductor based on the thermal expansion / contraction of the workpiece, significantly simplifying the control of the induction hardening system.

[0070] The contact unit, support unit, and / or drive unit of the tool holding device can be actuated individually or in combination.

[0071] To prevent the contact units, support units, and / or drive units themselves from undergoing excessive thermal expansion / contraction, they are advantageously made of heat-resistant materials such as ceramics, polymer ceramics, aluminum silicate, stone, refractory clay, or special steel alloys.

[0072] Further advantages and advantageous embodiments are indicated in the specification, drawings, and claims. In particular, the combinations of features indicated in the specification and drawings are merely illustrative here, and therefore these features may exist individually or in other combinations. Attached Figure Description

[0073] The invention will be described in more detail below with reference to exemplary embodiments shown in the accompanying drawings. Here, the exemplary embodiments and combinations shown in the exemplary embodiments are merely illustrative and are not intended to limit the scope of the invention. The scope of the invention is defined only by the appended claims.

[0074] In the attached diagram:

[0075] Figure 1 : A schematic diagram of a first exemplary embodiment of the workpiece holding device is shown;

[0076] Figure 2 : A schematic diagram of another exemplary embodiment of the workpiece holding device is shown;

[0077] Figure 3 : A schematic diagram of another exemplary embodiment of the workpiece holding device is shown;

[0078] Figure 4 : A schematic diagram of another exemplary embodiment of the workpiece holding device is shown;

[0079] Figure 5 A perspective view of another exemplary embodiment of the workpiece holding device is shown;

[0080] Figure 6 : A schematic cross-sectional view of various embodiments via contact elements or support elements is shown;

[0081] Figure 7 A schematic cross-sectional view of another exemplary embodiment of the workpiece holding device is shown;

[0082] Figure 8 A schematic cross-sectional view of another exemplary embodiment of the workpiece holding device is shown; and

[0083] Figure 9 : A schematic cross-sectional view of yet another exemplary embodiment of the workpiece holding device is shown.

[0084] List of reference numerals

[0085] 100 Hardening System

[0086] 2. Workpiece

[0087] 4. Induction coil

[0088] 6. Workpiece holding device

[0089] 8 contact units

[0090] 10 Contact elements

[0091] 12 Support Units

[0092] 14 drive units

[0093] 16 Supporting elements

[0094] 160 ball element

[0095] 161 Ball bearing component

[0096] 162 ball bearing

[0097] 163 Sleeve Components

[0098] 164 Rolling Bearing

[0099] 165 Rolling element

[0100] 166 Clamping Ring

[0101] 22. The radial inner side of the workpiece

[0102] 24. Radial outer side of the workpiece

[0103] 60 load-bearing components

[0104] 62 axes

[0105] 63 hubs

[0106] 64 installation points Detailed Implementation

[0107] In the following text, elements that are identical or functionally equivalent are indicated by the same reference numerals.

[0108] Figure 1 A schematic perspective view of a workpiece holding device 6 is shown. The workpiece holding device 6 can be used in an induction hardening system 100 to induction harden a workpiece 2 (e.g., a bearing ring) with the aid of an inductor 4. Figure 1 The induction hardening system 100 shown is designed as a hardening system in which the inductor 4 heats only a portion of the workpiece 2 at a time as the workpiece 2 moves past the inductor 4. For this purpose, the workpiece 2 is held in a workpiece holding device 6 and moves past the inductor 4. The workpiece holding device 6 has at least three contact units 8-1, 8-2, and 8-3 for receiving the workpiece 2, and the contact units 8-1, 8-2, and 8-3 are designed to hold the workpiece 2.

[0109] In the exemplary embodiment shown, Figure 1 It is also shown that workpiece 2 is rested on three support units 12-1, 12-2, and 12-3.

[0110] The accompanying drawings also show that contact units 8-2 and 8-3 are designed as so-called passive contact units, which are radially fixed at least during operation (work / run). On the other hand, contact unit 8-1 is designed as an active contact unit and can be adjusted in the radial direction, even during operation, to adapt the workpiece holding device 6 to different sizes of the workpiece 2 and to follow thermal expansion / contraction during heating.

[0111] Especially in Figure 1 and Figure 2 Between and Figure 3 and Figure 4 As shown in the comparison, the larger bearing ring 2 (see Figure 1 and Figure 3 ) and the smaller bearing ring 2' (see Figure 2 and Figure 4 They are held in the same workpiece holder 100. However, this also means that, starting from the center points M, M' of the bearing rings 2, 2' or the workpiece holder 100, the contact units 8-2 and 8-3 do not form the same angle α. Figure 1 and Figure 2 or Figure 3 and Figure 4 As can be seen, for the smaller bearing ring 2' (see...) Figure 2 and Figure 4 The angle α' between the passive contact units 8-2 and 8-3 is greater than that for the larger bearing ring 2 (see...). Figure 1 , Figure 3 (From the angle of) Figure 2 and Figure 4 middle, Figure 1The center point M' and angle α' are shown as dashed lines to show that contact units 8-2 and 8-3 remain in the same position for both the smaller bearing ring 2' and the larger bearing ring 2.

[0112] Since only the active contact unit 8-1 needs to be radially adjustable to accommodate the different sizes of workpieces 2, 2', the entire workpiece holding device 6 is significantly simplified, as only a single contact unit 8-1 needs to adapt to the dimensions of workpieces 2, 2'. This also ensures that the workpiece is always centered in the workpiece holder regardless of its size.

[0113] To enable the workpiece 2 to move along the inductor 4, a drive unit designed to rotate only the workpiece 2 is provided, instead of rotating the entire device 6 as in the prior art. Figures 1 to 4 In the exemplary embodiment shown, contact units 8-1, 8-2, and 8-3 are designed as driven contact units 14-1, 14-2, and 14-3 (e.g., as friction wheels or friction rollers). These driven contact units 14-1, 14-2, and 14-3 form a drive unit 14 and act directly on the workpiece 2, causing it to rotate (see arrow). For this purpose, contact units 8-1, 8-2, and 8-3 have, for example, driven contact elements (friction rollers). The driven contact units 14 or driven contact elements are preferably all driven by a single motor (not shown). This ensures that all driven contact elements 14 rotate at the same speed, so that the workpiece 2 is driven uniformly.

[0114] One or more measuring devices (not shown) may also be attached to one or more of the contact units 8 and / or support units 12, the measuring devices being designed to measure the contact force and / or clamping force and / or frictional force between the contact units 8 and / or support units 12 and the workpiece 2. A control device (not shown) may also be provided, interacting with units 8, 12, and 14 such that the contact units 8 and / or support units 12 interact with the workpiece 2 with predetermined contact force, clamping force, and / or frictional force, or that the drive unit 14 provides a corresponding rotational speed.

[0115] Figure 5 A schematic perspective view of this workpiece holding device 6 is shown. The workpiece holding device 6 can be used for, for example... Figures 1 to 4 The induction hardening system 100 is schematically shown in the diagram. In the exemplary embodiment shown, the workpiece holding device 6 includes three carriers 60-1, 60-2, 60-3 and three shafts 62-1, 62-2, 62-3, which respectively carry the contact unit 8 (carrier 60) and the support unit 12 (shaft 62). The carriers 60 and shafts 62 can also be designed as a single integrated component, such as... Figures 1 to 4As schematically shown. The shaft 62 and the carrier 60 are then attached to the mounting point 64 such that the carrier 60 extends radially outward and is offset axially from the rotation center M, which is determined by the rotation of the workpiece 2 in the workpiece holding device 6. The shaft and the carrier can be rotatably attached to the mounting point 64.

[0116] also, Figure 5 Support elements 16-1, 16-2, and 16-3 are shown disposed in the area where the workpiece 2 rests on the shaft 62. In the illustrated embodiment, the support elements are designed as cylindrical sleeves rotatably disposed on the shaft 62. Due to the rotatability of the support element 16, the workpiece 2 can be easily rotated.

[0117] also, Figure 5 Contact units 8-1, 8-2, and 8-3 are shown arranged on the carrier 60 in the form of contact elements 10-1, 10-2, and 10-3, and are designed to fix the workpiece 2 in its position. Contact unit 8-1 is designed as an active contact unit and can be moved radially before and during the actual hardening process. On the other hand, contact units 8-2 and 8-3 are designed as passive contact units, which cannot move radially, at least during the operation of the induction hardening system. In order to compensate for very large differences between workpieces, the passive contact elements can also be designed to be radially movable to coarsely adjust the workpiece, such that the passive contact elements can move radially on the carrier 60 or on the shaft 62 until they contact the workpiece 2 and fix the workpiece in place.

[0118] Furthermore, it is shown that the contact unit 8 has a contact element 10 in the form of a contact roller 10. The contact element 10 can be designed as a sleeve and can be detachably and rotatably mounted on the hub 63. The active contact element 10-1, together with its hub 63, is designed to be radially displaceable along the carrier 60-1 (see arrow) to accommodate different workpieces 2. In addition, during operation, the active contact element can be actuated so that the active contact element follows the workpiece and compensates for the thermal expansion or contraction of the workpiece, so that the contact element 10 always bears against the workpiece with the same contact force.

[0119] Especially preferred is, such as Figure 6 As shown, the contact element 10 is designed as a slip-on sleeve. The slip-on sleeve 10 may be cylindrical ( Figure 6 a, Figure 6 b) Conical ( Figure 6 c to Figure 6 e) Spherical ( Figure 6f) and / or spherical form. The exact shape can depend on several factors. On the one hand, the shape can be adapted to the shape or curvature of the radial inner surface 22 or the outer surface 24 of the workpiece 2. Particularly preferred is that the sliding sleeve contacts the workpiece 2 along a line oriented parallel to the axis of rotation. This allows for pure rotational movement between the rotating element and the workpiece without any sliding movement. However, shapes that provide minimal contact but sufficient clamping force can also be selected. The shape can also be selected based on rotational considerations. Furthermore, the sliding sleeves of contact units 8-1 to 8-3 can have different designs. In particular, it can be proposed that the sliding sleeve 10-1 of the active contact unit 8-1 is of a different design than the sliding sleeves 10-2 and 10-3 of the passive contact units 8-2 and 8-3.

[0120] According to another preferred exemplary embodiment, the hub 63 can also be angled with the aid of an adjusting device (not shown), and so on. Figure 6 This is schematically indicated in b. This also allows the rotating element to be adapted particularly well to the geometry of the workpiece. For example, with the aid of an adjusting device, a cylindrical rotatable element can be used even for inclined radial surfaces, and the rotating element is still guided by line contact on the workpiece. Alternatively, a similar element can also be used here. Figure 6 The tapered sleeve shown in c to 6d.

[0121] Alternatively, or additionally, contact unit 8, or at least one of contact units 8, can be designed as driven contact unit 14. In this case, it is particularly preferred that contact element 10 is designed, for example, as a friction roller that rubs against workpiece 2 and actively rotates to cause workpiece 2 to rotate. The friction roller can also have cylindrical, conical, spherical, annular, and / or spherical shapes, such as... Figure 6 As shown. Alternatively, or additionally, in addition to the driven contact element 10, a driven support element 16 may also be provided.

[0122] The rotatable support element 16 of the support unit 12 can also be designed, for example, to have Figure 6 Interchangeable sleeves of the shape shown. This allows the support element to ensure low-friction and anti-tilt mounting of workpiece 2, while also providing particularly good accessibility to the surface to be processed. On the other hand, the flexible design using interchangeable sleeves also allows for adaptation to the shape of the workpiece itself.

[0123] A particularly preferred exemplary embodiment is one in which the contact element 10 has a tapered shape, such as... Figure 7 As shown. Figure 7 and Figure 8As shown, this in particular ensures that the workpiece is held on the support element 16, as it reliably prevents any upward movement caused by the inductor 4. If the contact element 10 is designed as a cylinder, such as... Figure 8 As shown, the workpiece may move upward away from the support element 16. Therefore, the tapered contact element 10 also serves as a hold-down device.

[0124] Of course, a separate pressing device (not shown) can also be used to apply axial tension to the workpiece 2. The pressing device is specifically designed for lightweight workpieces and the high magnetic field strength of the inductor 4 to hold the workpiece firmly and accurately in the proper position within the workpiece holding device 100.

[0125] also, Figure 7 and Figure 8 An exemplary embodiment is shown in which the support element 16 is designed as a ball 160. Therefore, the workpiece 2 contacts the support element 16 only at one point P. The ball 160 is then rotatably mounted in the ball carrier 161 (e.g., by means of another ball 162, such as...). Figure 7 and Figure 8 (as shown), or it is slidably installed in the ball receptacle.

[0126] Point-based mounting allows the workpiece 2 to rest on the support element 16 in a particularly frictionless and slip-free manner, enabling the workpiece to rotate quickly without consuming excessive energy through the support element 16.

[0127] Instead of the ball element 160, the support element 16 can also be designed via a rotatably mounted sleeve element 163, wherein the sleeve element 163 has a spherical shape, and the sleeve element thus contacts the workpiece 2 only at a single point P. Of course, the sleeve element can be mounted to the shaft 62 under sliding friction, but it can also be as follows: Figure 9 As shown, the sleeve element 163 can be mounted via the rolling bearing 164, wherein, for example, the sleeve element 163 can be designed as the outer ring. In this case, the shaft 62 can continue to serve as the inner ring of the rolling bearing 164. The rolling element 165 then rolls inside the sleeve element 163 and outside the shaft 62. To axially fix the sleeve element to the shaft 62, a clamping ring 166 can also be provided, which clamps the rolling element 165 and thus also the sleeve element 163 in their positions axially.

[0128] Of course, instead of clamping ring 166, the inner ring can also be mounted on shaft 62, and the rolling element 165 can roll on the inner ring.

[0129] Both the clamping ring 166 and the inner ring are preferably mounted on the shaft 62 so that they can move axially to position the sleeve element 163 relative to the workpiece 2. However, in the exemplary embodiment shown, the sleeve element 163 and the ball 160 are designed as passive support elements that move only by the rotation of the workpiece 2.

[0130] To enable the workpiece 2 to rotate, at least one of the contact elements 10 is designed as a drive element. However, in addition, the workpiece 2 may move slightly back and forth axially on the ball element 160 or the sleeve element 163 to, for example, follow and / or compensate for thermal expansion and / or contraction during heating and / or create related imbalances.

[0131] Overall, the flexible design of the clamping and support units allows the workpiece holding device to adapt particularly well to workpieces of various shapes. Meanwhile, designing a single contact unit as an active contact unit that can follow thermal expansion or contraction ensures a particularly easy-to-adjust and robust system. This makes it possible to provide an easy-to-use, individually adjustable device that can be universally used for a wide range of workpieces.

Claims

1. A workpiece holding device for holding a workpiece in a heat treatment system, the heat treatment system being particularly a hardening system for hardening at least a portion of the workpiece, wherein, The workpiece has a closed curved profile and has a substantially radial inner surface (22) and a substantially radial outer surface (24), and can be held in the workpiece holding device (6) so as to be rotatable about a rotation axis, and can be heated by means of a heating device to cause the workpiece to undergo thermal expansion and / or contraction, wherein the workpiece holding device (6) has at least three support units (12) designed such that the workpiece (2) rests on the support units, and the workpiece holding device (6) includes at least three contact units designed to position the workpiece (2) at a predetermined radial position in the workpiece holding device (6), characterized in that two of the three contact units are designed as passive contact units, and one of the three contact units is designed as an active contact unit, wherein the active contact unit is designed to apply a radial clamping force to the workpiece (2).

2. The workpiece holding device (6) according to claim 1, characterized in that, Each contact unit has a contact element designed to support the radial inner surface (22) and / or radial outer surface (24) of the workpiece (2), wherein the contact element of the passive contact unit is designed to be a passive contact element fixed in the radial direction during operation, and the contact element of the active contact unit (8) is designed to be an active contact element movable in the radial direction during operation to apply a radial clamping force to the workpiece (2).

3. The workpiece holding device (6) according to claim 1 or 2, characterized in that, At least one of the contact units (8) is designed to be a rotatable contact unit (8), which is driven by a drive unit (14) and designed to rotate the workpiece (2) held in the workpiece holding device (6). Preferably, at least one rotatable contact unit has a rotatable drive element, in particular a friction wheel or friction roller, which is designed to support the workpiece (2) with a determinable frictional force and interact with the workpiece (2) in a frictional engagement manner to rotate the workpiece.

4. The workpiece holding device (6) according to any one of the preceding claims, characterized in that, At least one of the contact elements (10) is designed to support a rotatable contact element (10) against the workpiece (2).

5. The workpiece holding device (6) according to any one of the preceding claims, characterized in that, Each of the support units (12) further includes at least one rotatable support element (16), on which the workpiece (2) rests.

6. The workpiece holding device (6) according to claim 5, characterized in that, The rotatable support element is designed as a passive, non-driven support element, and in particular, the rotatable support element is designed as a spherical sleeve element (163) or ball (160) with point-based contact.

7. The workpiece holding device (6) according to any one of the preceding claims, characterized in that, At least one of the contact element (10) and / or support element is detachably fastened to the associated contact unit / support unit.

8. The workpiece holding device (6) according to any one of the preceding claims, characterized in that, At least one contact unit (8) and / or at least one support unit further includes an adjustment device designed to adjust the angular position of the contact element (10) and / or the support element.

9. The workpiece holding device (6) according to any one of the preceding claims, characterized in that, The active contact element (10) is also designed to preload in the direction of the workpiece (2) such that the active contact element (10) supports against the workpiece (2) with a predetermined contact force, wherein the active contact element (10) is preferably also designed to follow the thermal expansion and / or contraction of the workpiece caused by the heat treatment in the workpiece (2).

10. The workpiece holding device (6) according to any one of the preceding claims, characterized in that, It also includes a control unit designed to control the active contact unit, particularly the active contact element, with respect to contact force and / or clamping force and / or friction force, and / or to control the drive unit with respect to the rotational speed of the workpiece.

11. An induction hardening system (100) for hardening a workpiece (2) having a closed curved profile, the workpiece (2) having a substantially radial inner surface (22) and a substantially radial outer surface (24), the induction hardening system (100) having at least one workpiece holding device (6) for holding the workpiece (2) and an induction coil (8) for heating the workpiece (2), wherein, The induction coil (8) is designed to induce current in the workpiece (2) and thus achieve a definable heat input in the workpiece (2) to heat the workpiece, characterized in that the workpiece holding device is a workpiece holding device according to any one of claims 1 to 10, and has a passive contact unit and an active contact unit.

12. The induction hardening system according to claim 11, characterized in that, The inductor (4) is positioned between the two passive contact units.

13. The induction hardening system according to claim 11 or 12, characterized in that, A laser measuring device is also provided, which is designed to determine the coupling gap between the induction coil and the workpiece, and a control unit is provided for controlling the active contact unit, particularly the active contact element of the active contact unit, wherein the control unit is designed to control the contact force of the active contact unit, particularly the contact force of the active contact element and / or the position of the inductor based on the coupling gap size determined by the laser measuring device, so that the coupling gap between the workpiece and the induction coil is substantially constant.

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