CS217601B1 - Commutator segment - Google Patents

Abstract

The hardness of the insulating layer required for the assembly of dimensionally accurate commutators ]e associated with the problem of ensuring that each lamella also has a high dimensional and shape accuracy. This is achieved according to the invention in that in the case of a commutator lamella with insulation from an electrically insulating, pressure-resistant metal oxide layer, in particular a corundum layer, placed directly on a copper base body, a copper layer is applied to the metal oxide layer, so that only the copper layer is ground to the prescribed thickness of the lamella.

Description

The invention relates to a commutator lamella with insulation from an electrically insulating pressure-resistant metal oxide layer, in particular a corundum layer, placed directly on the lamella base body.

It is already known to provide commutator slats directly with a hard insulating layer and not to use insulating slats as described in German patent 938 199. Metal oxide layers, in particular Al2O3, or corundum, are particularly suitable as insulating layers. Such insulating layers are known from French Patent 973 525 for separate insulating layers and are sprayed according to NSR-AS 1 259 170 by flame or plasma. In the hard insulating layer, a recess is provided in the wear zone, which is filled with insulating sealant, as also described in German Patent 938 199.

The hardness of the insulating layer required to assemble dimensional commutators is associated with the problem of ensuring that each lamella also has high dimensional and shape accuracy. It is obvious to achieve this accuracy by grinding the hard insulation layer to the required degree. However, for the hardness of the insulating layer, especially for corundum, it is necessary to grind with a diamond grinding wheel. Due to the considerable unevenness of the sprayed insulating layer and due to the required tolerances, the time and material costs during grinding are unsuitably high.

SUMMARY OF THE INVENTION The object of the invention is to reduce the time and material costs of grinding.

According to the invention, this object is achieved by the application of a thin copper layer on the metal oxide layer so that the desired lamella thickness can be achieved by grinding a thin copper layer.

The solution according to the invention avoids the difficult and expensive grinding of the hard insulating layer a

601 instead, a soft copper layer is ground. There is no need to work with expensive diamond grinding wheels. At the same time, the sanding time is shortened, which brings considerable additional savings with a high number of slats. Practically, this means that only after eliminating the need to treat the hard insulating layer achieved by the invention, the use of the hard insulating layer directly on the commutator slats is economical and cost-effective.

The invention will be explained in more detail with reference to the embodiment shown in the drawing.

The drawing shows a cross-section through a copper commutator lamella provided with an insulating layer 2 of corundum. This insulating layer 2 extends only as far as the commutator can be turned. A thin layer of copper 3 is placed on the corundum insulating layer 2. Before the application of the corundum insulation layer 2, the commutator lamella base body 1 is roughened on one side by the corundum current. Thereafter, the corundum powder is sprayed with flame onto the area to be provided with the insulating layer 2, up to a thickness of about 0.04 mm less than it is. The desired thickness of the insulation layer 2 is then sprayed onto the insulation layer 2 with a thickness of about 0.06 millimeters. This copper layer 3 is finally sanded with a conventional corundum grinding wheel so that the insulated commutator lamella has the prescribed overall dimension of the copper layer 3 and the insulating layer 2. The insulated commutator lamellas thus produced are now folded into the commutator vault. By the preceding grinding, all commutator slats of the same thickness are achieved, so that a very precise slat spacing is also achieved. Thereafter, the commutator is formed only once and finally the recess in the corundum layer is filled with insulating sealant.

Claims (1)

Commutator lamella with insulation from an electrically insulating pressure-resistant metal oxide layer, especially a corundum layer, placed directly on the lamella base body Copper, characterized in that a copper layer (3J) is applied to the metal oxide layer (2).