RU2109380C1 - Process of manufacture of collector of electric machine - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: in agreement with invention bushing of collector is manufactured from aluminium alloy and then insulation coat on surface of bushing is formed on base of aluminium oxide. Finally bushing is equipped with current conductive bars that are anchored or formed on surface of bushing. EFFECT: decreased labor input, improved quality of collectors due to their increased strength. 2 cl, 2 dwg

Description

 The invention relates to electrical engineering and can be used in the manufacture of collectors of electrical machines.

 Known methods for the manufacture of collectors, in accordance with which collector plates (lamellas) are made of copper or alloys, placed in a mold for pressing or casting, then filled with plastic connecting lamellas [1]. Thus, a monolithic cylinder is formed. Inside it, in the process of filling with plastic, a metal sleeve can be pressed in, which is directly mounted on the armature shaft of the electric machine. Thus, in this method, the supporting and insulating element of the collector is plastic, in which the lamellas are placed. For great lamella fastening, the latter are supplied with various configurations (such as a "dovetail", hooks, etc.) with protrusions recessed in plastic. The lamellas are also equipped with structural elements "cocks" for connecting the wires of the winding.

 This method has less laboriousness compared to the previously created one, involving the assembly and joint fastening of lamellas and insulating gaskets of mechanical methods using coupling rings and studs, but does not provide sufficient collector strength at high speeds of rotation (40 m / s and above).

 There is also known a method [2], according to which the collector plates are made of aluminum alloy, oxidized to provide electrical insulation between the plates, then assembled on a fixture and tightened with an adhesive bandage. Then the working surface of the collector is machined on a lathe in order to remove the oxide film from it and a chemical treatment is carried out to obtain a conductive film.

 The wires of the armature winding are connected to the collector plates using the petals pre-pressed into them.

 The disadvantage of this method, selected as a prototype, is, firstly, the use of collector plates of aluminum as a material (its electrical resistance is one and a half times higher than that of copper), and secondly, the considerable complexity in the operations of plate assembly, winding and gluing bandages chemical treatment.

 There is also known a method of manufacturing collectors of electrical machines [3], according to which conductive lamellas are fixed on a collector sleeve made of an electrically conductive material (titanium), and then an insulating coating in the form of an oxide film is formed on the surface sections of the sleeve between the lamellas.

 This method is characterized by a large set of technological operations and structural elements that make up the collector, which complicates the manufacturing process of collectors and reduces their strength.

 The proposed method is aimed at ensuring high collector strength and at the same time reducing the complexity of its manufacture.

 The essence of the proposed method is as follows.

 The collector body in the form of a cylindrical sleeve is made of aluminum alloy (longitudinal dovetail grooves can be made on the outer cylindrical surface of the sleeve). The sleeve is oxidized to form an electrical insulating coating in the form of fragments of a cylindrical adjacent sleeve and has longitudinal dovetail protrusions placed in grooves on the aluminum sleeve. In this case, they can be manufactured separately and pressed into the grooves of the aluminum sleeve. In another embodiment, the lamellas can be formed by applying to the aluminum sleeve (both having dovetail grooves and without them) a copper conductive coating, for example, by plasma spraying with its subsequent division into strips (lamellas) parallel to the axis of the sleeve. In addition, the lamellas of the described construction can be formed using a mask also by plasma spraying. Elements for connecting the wires of the armature winding are formed on the lamellas.

 Thus, high collector strength and rigidity, intensive heat removal from the lamellas are achieved, which increases their wear resistance (and the collector as a whole) and the collectors can operate at very high rotation speeds (above 40 m / s).

 Figure 1 shows a cylindrical sleeve 1 of an aluminum alloy with an electrical insulating coating in the form of an oxide film 2 and with conductive lamellas 3 having "cockerels" 4; figure 2 - sleeve 1 with grooves "dovetail" and lamellas 3 with protrusions "dovetail".

 According to the proposed method, collectors were manufactured using all the described options. Bushings with an outer diameter of 25 mm, an inner diameter of 10 mm and a length of 20 mm were made of D16 alloy; dovetail grooves were made on parts of them on a mortising machine. Then the bushings were subjected to electrochemical oxidation to a depth of 80 μm. The breakdown voltage of such a film, which is an electrical insulating coating, is at least 1.6 kV. A 1.8 mm thick copper conductive coating was applied to the bushings without grooves in the plasma spraying unit, then it was processed on a lathe to a thickness of 1.5 mm, and then on a cutting EDM machine a wire with a diameter of 0.3 mm was cut into the coating to form an oxide film . The width of the lamellas was 3 mm. A less electrically conductive coating was applied to the same bushings by the same method through a molybdenum mask, while lamellas were formed during the application of the electrically conductive coating. From one edge of the sleeve, the coating was 4 mm thick over a length of 3 mm, the protrusion did not extend on the lathe, and a groove was formed on it for connecting the armature winding wires. The adhesion of the copper coating to the oxide film exceeded 3 MPa.

 Two bushings with dovetail grooves were made by extruding from the copper a lamella with a longitudinal dovetail protrusion, which were then pressed into the sleeve grooves. The ends of the lamellas, protruding on one side of the collector beyond its limit, with a cut-off protrusion, were bent to the side of the cylindrical surface of the collector, forming “cocks” for connecting the wires of the armature winding.

 Such collectors have successfully passed tests at a speed of rotation of 55 thousand rpm (77 m / s).

Claims (3)

 1. A method of manufacturing a collector of an electric machine, according to which a sleeve is made of an electrically conductive material with an electrical insulating coating on its surface and the sleeve is provided with conductive lamellas, characterized in that the sleeve is made of aluminum alloy, after which an insulating coating is formed based on aluminum oxide, and then conductive lamellas fasten or form on the surface of the sleeve.  2. The method according to claim 1, characterized in that the conductive lamellas are formed by applying an electrically conductive coating to the surface of the sleeve of the sleeve, followed by its separation into strips parallel to the axis of the sleeve by the erosion method.  3. The method according to claim 1, characterized in that the conductive lamellas are formed by applying to the surface of the sleeve of the electrically conductive coating in the form of strips isolated from each other parallel to the axis of the sleeve by plasma spraying using a mask.

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