METHOD AND DEVICE FOR INDUCTION HARDENING

Abstract

The invention relates to a method for the induction hardening of a workpiece, in particular a toothed and/or corrugated and/or ribbed workpiece such as a gear or saw blade, wherein a matchingly shaped induction loop is guided or set over the workpiece surface to be hardened, the induction loop being formed layer-by-layer by the additive application of material, and the induction loop being shaped to match the surface to be hardened.

Claims

1. A method for the induction hardening of a toothed and/or corrugated and/or ribbed workpiece comprising a gear, sprocket wheel, or saw blade, wherein the workpiece has a surface, the method comprising: guiding or setting over the workpiece surface a matchingly shaped induction loop, forming the induction loop layer by layer by the additive application of material, wherein the induction loop is shaped to match the surface of the workpiece.

2. The method of claim 1, wherein the forming comprises a 3D printing process by a 3D printing head and matchingly shaping the induction loop to the surface of the workpiece to be hardened during the 3D printing process, further comprising building up the induction loop comprising a layer-by-layer construction in the 3D printer and, if necessary, a thermal post-treatment comprising solidifying the induction loop.

3. The method of claim 1, wherein the matchingly shaping of the induction loop comprises matchingly shaping to more than three tooth gaps or wave troughs of the workpiece, and further comprising simultaneously hardening more than three tooth gaps of the workpiece by the induction loop.

4. The method of claim 1, wherein forming of the induction loop further comprises forming a hollow in layers by the additive material application in such a way that a coolant passage running through the induction loop is formed, and cooling the induction loop by a cooling medium located in the coolant passage during hardening.

5. The method of claim 1, further comprising simultaneously enclosing and simultaneously hardening by the induction loop more than 25% of a total toothing and/or corrugation and/or ripple contour to be hardened.

6. The method of claim 1, further comprising shaping the induction loop by the additive application layer-by-layer to two different toothing contours of the toothed workpiece which are axially spaced from one another and/or have different diameters, and hardening the different toothing contours of the toothed workpiece simultaneously by the induction loop.

7. A device for induction hardening of a toothed and/or corrugated workpiece comprising a gear, sprocket wheel, or saw blade, wherein the workpiece has a surface, the device comprising: an induction loop adapted in shape to the surface of the workpiece to be hardened, wherein the induction loop has a layered structural body having material layers, and wherein the material layers are individually consolidated layer-by-layer.

8. The device of claim 7, wherein the induction loop is 3D printed by a 3D printer.

9. The device of claim 7, wherein the induction loop has a coolant passage in an interior of the induction loop.

10. The device of claim 7, wherein the induction loop is matchingly shaped to more than three tooth gaps or wave troughs of the toothed and/or corrugated workpiece and encloses more than three adjacent tooth gaps or wave troughs simultaneously.

11. The device of claim 7, wherein the induction loop has at least one portion with a continuously varying curvature.

12. The device of claim 7, wherein the induction loop has at least one straight portion and at least one curved portion interconnected by a bent portion.

13. The device of claim 7, wherein the induction loop has loop sections matchingly shaped to different sectors of a gear having different diameters from one another.

14. The device of claim 7, wherein the induction loop is matchingly shaped to a toothing comprising a plurality of tooth gaps and a plurality of teeth, and wherein a gap between the induction loop and the toothing has a constant and even gap dimension across the plurality of tooth gaps and the plurality of teeth.

15. The device of claim 7, wherein the induction loop is matchingly shaped to a toothing comprising a plurality of tooth gaps and a plurality of teeth, and wherein a gap between the induction loop and the toothing has a continuously varying gap dimension across the plurality of tooth gaps and the plurality of teeth that cyclically increases and decreases.

16. The device of claim 7, wherein the induction loop extends over more than 25% of the length of a toothing of the workpiece.

17. The device of claim 7, wherein workpiece comprises a gear and/or a rack toothing, and wherein the induction loop extends over an entire toothed circumference of the gear or over an entire length of the rack toothing.

18. The device of claim 7, wherein the induction loop has two separate induction loop sections axially spaced from each other and having enveloping contours of different diameters, wherein the two induction loop sections are matchingly shaped to different teeth of a stepped ring gear.

19. The device of claim 18, wherein each induction loop section surrounds more than three tooth gaps enclosing the entire toothing in each case.

20. The device of claim 7, wherein the induction loop has at least one coolant passage inside.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will be explained in more detail in the following with respect to preferred embodiments and to associated drawings. The drawings show:

[0024] FIG. 1: A side view of an induction loop of a device for induction hardening of a gear, which extends over the entire outer circumference of the gear and is precisely matchingly shaped to the contour of the tooth gaps and teeth, with the axis of view corresponding to the representation of the axis of rotation of the gear;

[0025] FIG. 2: a perspective view of the induction loop surrounding the gear to be hardened in a viewing direction obliquely with respect to the axis of rotation of the gear, showing the contour of the induction loop adapted to the shape of the toothing;

[0026] FIG. 3: a side view of a gear and an induction loop matchingly shaped to its toothing, which in contrast to the explanations according to FIGS. 1 and 2 is matchingly shaped only at three or more tooth gaps and has inlets and outlets for a coolant at the end;

[0027] FIG. 4: a perspective view of the induction loop of FIG. 3 partially surrounding the gear to be hardened in a viewing direction obliquely with respect to the axis of rotation of the gear;

[0028] FIG. 5: A side view of a gear and an induction loop adapted in shape to its toothing, the induction loop comprising two partial induction loops for simultaneous hardening and being contoured in such a way that the gap between the induction loop and the toothing surface contour has a non-constant, predetermined gap dimension;

[0029] FIG. 6: a perspective view of the gear and the surrounding induction loop from FIG. 5 in a viewing direction obliquely with respect to the axis of rotation of the gear;

[0030] FIG. 7: a side view of a two-stage toothed gear for simultaneous hardening and an induction loop adapted to the shape of different toothed areas for simultaneous hardening of the different tooth stage areas; and

[0031] FIG. 8: a perspective view of the gear and the surrounding induction loop from FIG. 7 in a viewing direction obliquely with respect to the axis of rotation of the gear rim;

DETAILED DESCRIPTION

[0032] As shown in FIGS. 1 and 2, the induction loop 2 can be used to partially harden the toothing 8 of a toothed workpiece 1, said toothed workpiece 1 being a gear or a rack. As explained at the beginning, however, other workpieces with similar corrugated or grooved contours or with differently contoured surfaces can also be induction hardened in a corresponding manner.

[0033] Advantageously, the induction loop 2 can simultaneously cover at least a large part of the toothing 8, in particular also the entire toothing 8, as shown in FIGS. 1 and 2.

[0034] The induction loop 2 is produced in an additive material deposition process, in particular with a 3D printing process, wherein the induction loop can be built up by layer-by-layer build-up in the 3D printer and, if necessary, solidified by thermal post-treatment. The induction loop is advantageously made of an electrically conductive, in particular metallic, material.

[0035] The induction loop 2 can be formed with a round or rounded, flattened, for example elliptical, but also an angular, in particular rectangular or square cross-section. Furthermore, the induction loop can have any cross-section if required by the geometric conditions of the workpiece to be hardened.

[0036] As FIGS. 1 and 2 show, the induction loop 2 can be precisely matchingly shaped to the toothing 8 by the additive, layer-by-layer application of material, and in particular can be precisely matchingly shaped to the tooth gaps 5 and the teeth 6 of the toothing 8, so that a gap 9 between the induction loop 2 placed over the toothing 8 and the tooth and tooth gap contours can be maintained exactly constant, so that a gap dimension along the longitudinal extent of the induction loop 2 remains at least substantially constant. In this way, a desired hardening result, for example an even hardening depth, can be achieved.

[0037] However, the induction loop 2 can also be specifically shaped deviating from the contour of the surface to be hardened, in particular the toothing 8, by the additive material application and the layer-by-layer formation in order to achieve a defined course of the gap dimension of the gap 9, for example a slightly larger gap dimension at the tips of the teeth 6 than at the bottom of the tooth gaps 5, as shown in FIGS. 5 and 6. In particular, the induction loop 2 can be formed in the 3D printing process such that the gap dimension along the induction loop 2 changes continuously and/or cyclically to achieve the desired hardening depth profile.

[0038] As shown in FIGS. 1 and 2, the induction loop 2 can extend around the entire circumference of the gear and/or extend across the entire toothing 8, matching the contours of the teeth and tooth gaps.

[0039] As shown in FIGS. 1 and 2, the width of the induction loop 2 can be smaller than the thickness of the workpiece 1. In the induction hardening process, the induction loop 2 can be guided by an advancing movement across the entire width of the workpiece 1, and such an advancing movement can be performed in the direction of the rotation axis of the gear by the induction loop 2 and/or by the workpiece 1 to be hardened. The induction loop 2 is shifted across the workpiece 1 parallel to the tooth flanks of the teeth 6 or parallel to the bottom of the tooth gaps 8 in order to harden the toothing 8 over its entire width.

[0040] Alternatively, however, it would also be possible to make the induction loop 2 wider, so that the width of the induction loop 2 corresponds to the thickness of the workpiece 1 or is even greater.

[0041] As FIGS. 1 and 2 shown, the induction loop 2 may advantageously have a coolant inlet 3 and a coolant outlet 4 to be able to feed into a coolant passage 7 extending inside the induction loop 2, in particular to be able to circulate through said coolant passage 7 and to cool the induction loop 2 by the coolant in the coolant passage 7 during hardening.

[0042] Said coolant passage 7 is formed inside the induction loop 2 during the layer-by-layer formation of the induction loop 2 by additive material deposition.

[0043] As FIGS. 3 and 4 shown, however, the induction loop 2 can, if necessary, also cover only a partial section of the toothing 8, for example extending across three adjacent tooth gaps 5. Here, too, it can be advantageously provided that the induction loop 2 fits precisely to the contours of the tooth gaps 5 and the teeth 6 bounding the tooth gaps 5, so that a gap 9 with a constant gap dimension is achieved. Said gap dimension can be essentially constant from the bottom of the tooth gaps 5 over the tooth flanks to the tips or heads of the teeth 6, as shown in FIG. 3.

[0044] In order to harden the entire toothing 8, after the hardening cycle of the tooth gaps 5 covered by the induction loop 2, the workpiece 1 can be further rotated by an angle corresponding to the angle between the outermost tooth gaps covered by the induction loop 2. In other words, the gear is rotated further by three teeth in order to be able to insert the induction loop 2 into three not yet hardened tooth gaps 5. Alternatively, the gear can also be rotated further by an integral multiple of the said angle, for example by six or nine teeth. Alternatively or in addition to turning the gear further, the induction loop 2 can also be turned accordingly, i.e. moved further in the circumferential direction of the gear.

[0045] As FIGS. 5 and 6 show, the shape of the induction loop 2 can also be adapted to the contour of the toothing 8 in such a way that the gap 9 between the induction loop 2 and the toothing 8 does not remain exactly constant but varies, in particular continuously and/or steadily increasing and decreasing again, in order to achieve different hardening results, in particular different hardening depths, at different sections of the toothing 8.

[0046] Separately, as FIGS. 5 and 6 show, two or more induction loops 2 may also be used simultaneously, each of which may have a coolant inlet 3 and a coolant outlet 4. Advantageously, the coolant inlet ports 3 and the coolant outlet ports 4 can each be supplied from a common inductor base.

[0047] As FIGS. 7 and 8 shown, separate contour sections can also be hardened simultaneously on a workpiece 1. One or more induction loops 2 can be matchingly shaped to different contour sections of the workpiece 1, wherein said contour sections can in particular have different diameters and/or be axially spaced from one another.

[0048] As FIGS. 7 and 8 show, a toothed workpiece 1 may have two separate toothings 8, which may, for example, have different numbers of teeth and/or different pitch diameters. For example, a stepped ring gear with two teeth 8 can be hardened by assigning an induction loop 2 to both teeth 8 simultaneously. Each induction loop 2 can be adapted exactly to the shape of the toothing contour in said manner, if necessary with a desired variation of the gap dimension.

[0049] Advantageously, the induction loop 2 can completely surround both toothings 8, although, similar to FIGS. 3 to 6, only a partial sector of one or both toothings 8 can be covered by the induction loop 2.

[0050] As FIGS. 7 and 8 show, two separate inductor loops 2 can be used, each of which can have a coolant inlet 3 and a coolant outlet 4 that can be supplied from a common inductor base. Alternatively, however, it would also be possible to form a continuous induction loop 2 that encloses both toothings 8 in a correspondingly matchingly shaped manner.