METHOD FOR PRODUCING A HELICAL ELECTRICALLY CONDUCTING BODY

Abstract

A method for producing a helical, electrically conducting body. The method including: producing a helical pattern as a lost mold made of a pattern material that can be at least one of liquefied and evaporated under the action of heat; covering the helical pattern with an insulating layer; embedding the helical pattern in foundry sand; pouring a metallic casting material into the lost mold, displacing the pattern material, and bonding with the insulating layer to form a cast body; and removing the cast body, together with the insulating layer adhering thereto, from the foundry sand.

Claims

1.-25.(canceled)

26. A method for producing a helical, electrically conducting body, the method comprising: producing a helical pattern as a lost mold made of a pattern material that can be at least one of liquefied and evaporated under the action of heat; covering the helical pattern with an insulating layer; embedding the helical pattern in foundry sand; pouring a metallic casting material into the lost mold, displacing the pattern material, and bonding with the insulating layer to form a cast body; and removing the cast body, together with the insulating layer adhering thereto, from the foundry sand.

27. The method of claim 26, wherein the insulating layer is applied to the helical pattern in the form of a foundry coating.

28. The method of claim 27, wherein the foundry coating includes a carrier liquid, a refractory component, and a binder.

29. The method of claim 26, wherein the insulating layer is applied to the helical pattern by way of at least one of dipping, squirting, and spraying.

30. The method of claim 26, wherein the insulating layer is deposited in the form of several consecutively applied sub-layers.

31. The method of claim 26, wherein the insulating layer is dried by one or more of heating and an air current, either sub-layer by sub-layer or after the last layer has been deposited.

32. The method of claim 26, wherein the helical pattern is produced in one of a casting process and a foaming process, the helical pattern being assembled from multiple parts.

33. The method of claim 32, wherein the helical pattern is produced as a blank, and thereafter is brought into the shape of a helix by creating a helical recess.

34. The method of claim 33, wherein the helical recess is created in the blank by way of a tool rotating about a first axis, which extends through the blank, while being steadily advanced along the first axis.

35. The method of claim 34, wherein the tool has a strand-shaped design, and during the creation of the helical recess, the tool does one of rotates about a second axis or carries out an oscillating movement along the second axis, the tool including at least one of saw-like and rasp-like teeth.

36. The method of claim 34, wherein the tool is heated to a temperature at which the material of the helical pattern softens or melts.

37. The method of claim 26, wherein material of the insulating layer is electrically insulating.

38. The method of claim 26, wherein material of the insulating layer is configured to be anti-corrosive.

39. The method of claim 26, wherein material of the insulating layer comprises a plastic material.

40. The method of claim 26, wherein material of the insulating layer comprises a ceramic material.

41. The method of claim 26, wherein material of the insulating layer comprises one or more of thermoplastic polyurethanes, thermoplastic polycarbonates, and polymethyl methacrylate.

42. The method of claim 26, wherein material of the insulating layer comprises one or more of material for powder coating and material for powder lacquering.

43. The method of claim 26, wherein material of the insulating layer comprises one or more of a polyamide, polyvinyl chloride, epoxy systems including polyester as a binder, polyester systems including TGIC as a hardener, acrylate, and polyurethane systems.

44. A helical body, produced in the method of claim 26 and including the metallic casting material and the insulating layer adhering thereto.

45. The helical body of claim 44, wherein the metallic casting material includes at least one of copper and aluminum.

46. The helical body of claim 44, wherein the insulating layer includes at least one of ceramic material and plastic material.

47. The helical body of claim 44, wherein the helical body has a longitudinal axis and a largest extension perpendicular to the longitudinal axis is between 0.02 m and 2 m.

48. The helical body of claim 44, wherein the helical body includes windings, and a largest cross-sectional extension perpendicular to a progression of at least one winding is between 0.3 mm and 5 cm.

49. The helical body of claim 44, wherein the metallic casting material includes one or more of copper, aluminum, silver, and magnesium and the insulating layer includes an insulating plastic material.

50. The helical body of claim 44, wherein the metallic casting material includes one or more of copper, aluminum, silver, and magnesium and the insulating layer includes a ceramic insulating material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The invention will be shown and described hereafter based on figures of an exemplary embodiment. In the drawings:

[0033] FIG. 1 shows a perspective view of a rectangular coil, according to embodiments of the disclosure;

[0034] FIG. 2 shows a perspective view of a strand section of a helical pattern, according to embodiments of the disclosure;

[0035] FIG. 3 shows a pattern as in FIG. 2, additionally comprising a first coating, according to embodiments of the disclosure;

[0036] FIG. 4 shows a pattern comprising a coating composed of two layers, according to embodiments of the disclosure;

[0037] FIG. 5 shows the coating of a pattern after the pattern has been removed, according to embodiments of the disclosure;

[0038] FIG. 6 shows a metallic cast body comprising a coating, according to embodiments of the disclosure;

[0039] FIG. 7 schematically shows a pattern in a perspective view and a device for producing the pattern, according to embodiments of the disclosure; and

[0040] FIG. 8 schematically shows the representation of a procedure for producing a helical, electrically conducting body, according to embodiments of the disclosure.

DETAILED DESCRIPTION

[0041] FIG. 1 shows a perspective view of a helical electrically conducting body in the form of a rectangular coil 1, which consists of a helical, strand-shaped body 2 having a rectangular cross-section, or comprises such a strand-shaped body. As an alternative thereto, in embodiments, helical bodies can be produced, for example, as coils twisted in a screw-like manner in a circular shape, or also as coils wound in a spiral-shaped manner or in other similar shapes. Such a body can be produced by way of lost mold metal casting.

[0042] FIG. 2 shows a short section of a strand-shaped pattern 3, which can be configured as a helical body having a circular cross-section. Such a pattern can, for example, be produced as a foamed plastic body, or also in the form of a wax. Such a pattern, or a pattern body, is used as a lost mold, which means that it is placed into a flask including foundry sand, wherein molten metal is poured into the volume of the pattern body, thereby dissolving the material of the pattern body by liquefaction or evaporation and displacing it.

[0043] Some embodiments, provide such patterns/pattern bodies with a coating to seal the possibly rough or porous surface of the pattern, and facilitate later demolding of the cast body from the foundry sand as well as the removal of the foundry sand stuck to the cast body.

[0044] FIG. 3 shows a perspective view of the strand-shaped pattern from FIG. 2, comprising a first layer 4 that surrounds the pattern and covers the lateral surface of the pattern and that is composed of an electrically insulating and/or an anti-corrosive insulating material.

[0045] To prepare for casting, the pattern 3 is embedded with the layer 4 in foundry sand, and the molten metal is poured into the lost mold thus configured. The layer 4, which is considerably more temperature-resistant than the material of the pattern 3, remains adhering to the surface of the cast body.

[0046] Coatings for the improved separation of the cast body from the foundry sand are known from the related art, which are removed from the cast body after the casting process. In contrast, the layer 4 described here is very stable and configured so as to adhere well to the cast body. It does not need to be removed from the cast body after the cast body has been removed from the foundry sand and, rather, can remain on the cast body, serving as an insulating layer. In this way, the need to provide the cast body later with an electrically insulating layer is eliminated.

[0047] FIG. 4 represents a variant in which the pattern body 3 is initially provided with an adhesion promoter layer 5, and only thereafter is coated with a layer 4 made of an insulating material. The adhesion promoter 5 is composed of a material that adheres well to the cast body on the one hand, and to the insulating layer 4 on the other hand. The adhesion promoter 5 is configured so as not to be destroyed when molten metal is poured in, but adheres to the metal cast body. The adhesion promoter can be made of an electrically insulating or also of an electrically conducting material. For example, the adhesion promoter can also be made of a metal that melts at the melting temperature of the metal to be cast. This metal of the adhesion promoter can be applied to the pattern in powder form, for example.

[0048] FIG. 5 schematically shows only the layer 4, from which the pattern body has been removed by way of evaporation or liquefaction, so that the molten metal flows into the space 6 surrounded by the layer 4.

[0049] FIG. 6 represents the cast body 7 to which the layer 4 firmly adheres, serving as an insulating layer.

[0050] The coating of the pattern body 3 with the layer 4 is carried out by applying a viscous, liquid or mash-like mass, for example in the form of a foundry coating comprising a carrier liquid, which can be water or alcohol, for example, and one or more refractory components, as well as optionally additives that set the viscosity. After the metal casting process, the layer 4 at least still contains the refractory components and optionally also binders, and together these form the insulating layer.

[0051] The coating 4 can also be achieved in multiple stages in liquid form, wherein individual layers set, or are dried or cured in between. In this way, overall larger layer thicknesses can be created in a short time.

[0052] For example, the pattern body 3 can be produced by foaming in a mold, or by casting or core shooting. Depending on the complexity, it may also be composed of multiple pieces, both of individual foamed sub-bodies and of individual cast sub-bodies.

[0053] One option for production is, for example, that a helical recess is cut out of a continuous, for example cylindrical or prismatic body, whereby a helical body remains. Such a variant is shown in FIG. 7 by way of example. A hollow cylinder 8 comprising a hollow cylinder wall 10 is shown there, which surrounds a cavity 9. A shaft 12 of a cutting device is inserted into the cavity 9 along the cylinder axis 11, wherein a tool 13 is arranged on the shaft 12, projecting radially therefrom. The tool 13 can be configured as a saw-like or rasp-like strand-shaped tool, which can be driven in a vibrating or oscillating manner, for example, by an oscillating drive 14 in the radial direction with respect to the axis 11. When the tool 13 is pivoted about the shaft 12 by rotating the same, on the one hand, and evenly and steadily advanced along the axis 11 by a further drive, on the other hand, the tool 13 follows a helical path, by which a helical recess 16 can be introduced into the hollow cylinder 8. When the helical recess 16 extends through the body of the hollow cylinder 8, a helical body of the pattern remains between the individual turns of the recess 16, which can then be coated with a layer 4 or a combined layer 4, 5. Thereafter, the pattern body thus created can serve as a lost mold for metal casting using molten metal, resulting in a round metal coil comprising an insulating coating.

[0054] Based on process steps, FIG. 8 schematically illustrates the production of a helical, electrically conducting body that is provided with an insulation.

[0055] In a first method step 17, the pattern body is produced from a foam or a wax. Thereafter, an adhesion promoter 5 is optionally applied to the pattern in a subsequent step 18. In the next method step 19, an insulating layer 4, for example in the form of a foundry coating, is applied either directly to the pattern or to the adhesion promoter layer and is allowed to set.

[0056] The lost mold thus created is placed in foundry sand in the following process step 20, and is filled with molten metal in process step 21. In this way, the conducting body comprising the insulating layer is completed.