ROLLER MOLDING METHOD FOR PRODUCING A SPIRAL STRUCTURE

Abstract

The present application creates a roller molding method for producing a spiral structure or a coil, in particular a spiral structure for use in electric machines, wherein material is supplied between a first roller and a second roller running opposite thereto, wherein the first roller has first teeth, and the second roller has second teeth, said first and/or second teeth having tooth flanks with cavities for receiving the supplied material, wherein the teeth are designed and aligned such that the cavity of at least one tooth is at least temporarily delimited by the surface of a tooth of the other roller when the rollers are rotating such that the supplied material is molded between the teeth into a portion of the spiral structure or the coil.

Claims

1. A roller molding method for producing at least one of a spiral structure and a coil, the roller molding method comprising: supplying material between a first roller and a second roller running opposite to the first roller, wherein the first and second rollers rotate one of continuously and at varying speed, wherein the first roller has first teeth, the second roller has second teeth, and at least one of the first teeth and the second teeth have tooth flanks with cavities for receiving the supplied material, wherein the first teeth and the second teeth are aligned such that a cavity of at least a first tooth of one of the first teeth and the second teeth is at least temporarily delimited by a surface of a second tooth of the other of the first teeth and the second teeth when the first and second rollers are rotating such that the supplied material is molded between the first teeth and the second teeth into a portion of the one of the spiral structure and the coil.

2. The roller molding method according to claim 1, wherein the supplied material is one of liquid, thixotropic and solid.

3. The roller molding method according to claim 1, wherein the supplied material at least one of (1) is a flat material with one of a round and rectangular cross-section and (2) has a meandering structure if the supplied material is not in a liquid state.

4. The roller molding method according to claim 1, wherein the supplied material comprises at least one of a metal and a plastic.

5. The roller molding method according to claim 4, wherein the metal comprises at least one of iron, aluminum, copper, and alloys thereof.

6. The roller molding method according to claim 1, further comprising heating the material before supplying the material between the first roller and the second roller.

7. A roller molding device for producing at least one of a spiral structure and a coil, the roller molding device comprising: at least a first roller with first teeth and a second roller, running opposite to the first roller, with second teeth, wherein at least one of the first teeth and/or second teeth have tooth flanks with cavities for receiving supplied material, wherein the first teeth and second teeth are aligned such that a cavity of at least a first tooth of one of the first teeth and the second teeth is at least temporarily delimited by the surface of a second tooth of the other of the first teeth and the second teeth when the first and second rollers are rotating in order to mold the supplied material into a portion of the one of the spiral structure and the coil.

8. The roller molding device according to claim 7, wherein the first teeth and the second teeth have, in portions, a straight toothing and an inclined toothing.

9. The roller molding device according to claim 7, further comprising a supply device for aligning the supplied material provided to the first and second rollers.

10. A spiral structure produced by the roller molding method of claim 1.

11. A plurality of spirals produced by compression of a spiral structure produced according to claim 1 in a direction of a central spiral axis of the central spiral structure.

12. The roller molding method according to claim 6, wherein heating the material comprises at least one of applying current and voltage between the first and second rollers and a supply device and inductively heating the material.

13. The roller molding device according to claim 8, wherein the first teeth and the second teeth have a sequence of “straight toothing/inclined toothing/straight toothing.”

14. The roller molding device according to claim 9, wherein the supply devices is configured for inclining and rotating flat material relative to the first and second rollers.

15. The plurality of spirals according to claim 11, wherein the spirals are rectangular spirals.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments are disclosed in the accompanying drawings.

[0018] In the drawings:

[0019] FIG. 1 shows a typical coil geometry;

[0020] FIGS. 2a, 2b, 2c, and 2d show details of a geometry of a spiral structure as the result of the roll molding process;

[0021] FIG. 3 shows the principle of the roller molding process;

[0022] FIG. 4 shows the “straight toothing-inclined toothing-straight toothing” combination; and

[0023] FIG. 5 shows opening and closing cavities in the roller molding process.

DETAILED DESCRIPTION OF THE DRAWINGS

[0024] A typical geometry of the coil is shown in FIG. 1. This coil is described in detail in EP 2 387 135 A2.

[0025] In order to produce this geometry, in accordance with the present patent application, a geometry that is pulled apart (“stretched”) in the z height direction is firstly produced and is then reshaped by subsequent upsetting in the z direction to give the geometry shown in FIG. 1. Therein, there is no twisting along the individual winding limbs. The resultant deformation region for the subsequent upsetting to give the end geometry lies in the transition region from the narrow to the long winding limbs. The subsequent upsetting process merely requires very small degrees of deformation.

[0026] FIGS. 2a-2d show a typical geometry illustrating the “stretched” coil produced in the roller molding process.

[0027] The principle of the roller molding process is shown in FIG. 3. In particular, the following features are applicable for the roller molding process: [0028] a) The two rollers having toothed-wheel-like geometries rotate oppositely to one another. They close and open the cavities for the coil winding due to the rolling movement of the tooth flanks. The cavities are formed in the various tooth flanks and may be different from tooth to tooth so as to allow variable cross-sections of the resultant turns, through which a flow may pass as necessary. [0029] b) A typical geometry shown in FIGS. 2a-2d results, for example due to a toothing combination on each roller consisting in each case of: [0030] “straight toothing—inclined toothing—straight toothing”, [0031] similarly to a herringbone toothing, in which the two inclined toothings are combined. FIG. 4 explains such a toothing arrangement on roller 1 (toothed wheel 1) and roller 2 (toothed wheel 2).

[0032] A particular advantage of roller molding is that the produced coil geometry does not contain any twisting, and after the shaping of the coil there is merely the need for an upsetting process in the z direction. There is no need for any twisting about the longitudinal axis of the turns in the case of the roller molding process. [0033] c) Following a complete revolution of the two rollers, a coil of varying cross-section of the turns in a stretched geometry is produced. The coil may be separated after one revolution and then processed further. Since the process may be performed continuously, the coils may also be separated at a later moment in time of the manufacturing chain. [0034] d) The shaping cavity is both closed and opened due to the kinematics of the tooth flanks (for example in the toothing combination shown in FIG. 4). Once the coil has left the rolling region, the coil geometry of varying cross-section of the turns is demolded. [0035] e) As the material is supplied to the roller molding process, the supply device may traverse the coil geometry in the x-y direction (for example in a cyclical rectangular movement) and may thus assist the supply process in a manner coordinated with the roller movements. In this case, a movement of the supply device that lies vertically above the cavity opening into the rolling tooth flanks is expedient. This path generally corresponds to the coil geometry when viewed from above (for example a rectangular path). Furthermore, the supply device may assist this vertical position by appropriate (peripheral) tilting, so that the supplied material may enter at a flat angle (similarly to the way a paintbrush is guided when painting), thus simplifying and optimizing the filling of the cavity.

[0036] This may be implemented for example by robot-guided supply devices or other movement devices that can be coordinated selectively. The movement of the supply device must be coordinated with the rotation of the rollers. The roller movement may be continuous/uniform here or may be adjusted with an optimized speed profile to the conditions of the material supply or the solidification process. [0037] f) The material may be supplied in principle in liquid, thixotropic or solid phase or also in all intermediate phases. These possibilities are described in greater detail in supplementary invention disclosures or patent applications of the inventors. [0038] g) In principle, all electrically conductive materials are suitable as materials for the coil, in particular aluminum, copper and their respective alloys, all metallic materials, but also hybrid materials such as electrically conductive plastic composites. [0039] h) If the material is supplied not in liquid form (see parallel patent application in the name of the same applicant), a heating of the material may facilitate and support the supply to the roller molding process. Therefore, both the material supply and the process of the shaping of the particular turn portion may be significantly facilitated or optimized in the supply device by heating the material as necessary, for example to just below the solidus temperature or by selectively adjusting the thixotropic material state. [0040] i) The supplied material may be heated for example in the supply device. All known heating methods are possible for this purpose. In particular when heating and adjusting the thixotropic material state, inductive heating of the material is possible, amongst other things. In this case, the material is heated continuously during the supply process so as to allow the material to be introduced in controlled fashion into the mold cavities. [0041] j) Alternatively to the heating of the material in the supply device, the material may be heated by applying an electrical voltage. In this case, the voltage is applied between the supply device and the tooth flanks (with the cavities). By appropriately controlling current/voltage, the supplied material may thus be heated selectively directly over the path from the supply device until inside the mold cavities. [0042] k) The tooth flanks with the mold cavities may optionally also be temperature-controlled. On the one hand, this may be a controlled heating of the mold cavities in the tooth flanks. The shaping process may thus be supported after the material has been supplied. On the other hand, a controlled cooling of the tooth flanks may also be provided, for example so as to influence the solidification in the mold cavity as the liquid material (casting) or thixotropic material is supplied. Due to accelerated cooling, improved joining properties may be achieved on the one hand, and on the other hand the productivity of the roller molding may be increased because with a larger material throughput (quicker speed of rotation of the rollers) the solidification or cooling and stabilization of the produced coil may be achieved. [0043] l) By spraying a suitable release agent onto the rotating rollers in the region of the shaping cavity, the demolding of the stretched coil as it exits from the rolling region may be simplified, on the one hand. On the other hand, the release agent may have, for example, an oxidizing effect on the surface of the coil turns, which intensifies the electrical insulation of the turns from one another (anodizing effect) and at the same time may have a supporting effect for the subsequent coating for insulation of the coil. [0044] m) A coating may be applied in order to electrically insulate the coil. This coating may be performed on the one hand by a downstream roller pair with comparable tooth flank geometry, into which the stretched coil is drawn once more. The insulation material is first introduced continuously into the cavities in this second roller pair, such that, as the stretched coil passes through, the insulation material is applied to the turns, possibly at elevated temperature, similarly to a roll cladding process. [0045] n) Alternatively to the coating in a second roller pair (see above bullet m), the insulation material may also be applied in the same roller pair in which the actual shaping is also performed. To this end, before the electrically conductive coil material is introduced, the insulation layer is introduced into the mold cavities, for example as described under bullet m). [0046] o) Alternatively to bullet m), the coating may also be provided by not demolding the coil from the shaping cavities following the shaping process, but instead winding it axially onto one of the two rollers. Following one or more revolutions, the coil geometry thus arrives again axially in the engagement region due to the winding on one of the two rollers and may be coated there as described under bullet m). Only then is the already coated coil then demolded in this option by being unwound from the roller. [0047] p) The techniques for coating are further differentiated and described in greater detail in supplementary invention disclosures. These methods are alternatives to known coating processes for which patents have already been filed.