CS269527B1 - Mixture for preparation of electrographed brushes - Google Patents

Abstract

The mixture for the preparation of electrographitized brushes from lamp soot and wood flour serves as the starting material for carbon brushes for the heaviest commutation activity. Until now, electrographites were most often used for this, the filler of which contained a combination of coke, carbon black and graphite. These switched their role only to an insufficient extent, especially in difficult loads. The mixture contains 48 to 55% by weight of lamp soot, 4 to 8% by weight of wood flour, 40 to 50% by weight of electrode pitch and 0.5 to 2% by weight of anthracene oil.

Description

The invention provides a mixture for the preparation of electrographed brushes.

The existing compositions for the preparation of electrographed brushes as fillers include either only coke or carbon black, but most often a combination of these powdered raw materials. Anthracene oil pitch is used as the binder.

A drawback of the blend of said powdered raw materials is that the brushes produced therefrom are not sufficiently suitable for the heaviest commutation, especially in large electrical machines powered by pulsed currents. They often also have a relatively large wear.

These drawbacks are eliminated by the composition for the preparation of electrographed brushes of the present invention. The solution is that the mixture contains 48 to 55% by weight of carbon black, 4 to 8% by weight of wood flour, 40 to 45% by weight of electrode pitch and 0.5 to 2% by weight of anthracene oil.

Lamp carbon blacks used in the blend have a relatively large surface area. This is sufficiently wetted by the melted electrode pitch binder and anthracene oil when mixed. The wood flour added to the mixture burns in the firing process, leaving openings in the moldings, very suitable for further impregnation of the brushes. The advantages of a mixture of lamp carbon black and wood flour for the preparation of electrographed brushes are that, at the end of the manufacturing process, the brushes receive the toughest commutation of large electric motors and generators, as well as brushes for large electrical machines with demanding power conditions from semiconductor pulsed technique. Another advantage is the few types of raw materials in said mixture with relatively unchanged properties. Brushes of the same technical characteristics are obtained in this way throughout their cross section, which is very necessary for the operation of large electrical appliances.

As an example of a mixture of such electrographed lamp carbon brushes and wood flour, the following can be mentioned: " Example " - wood flour ............. 6% by weight. - electrode pitch ........... 41% wt. - anthracene oil ........... 1% wt. Example 2: - lamp carbon black .......... 50% wt. - wood flour ............ 6% by weight. - electrode pitch ..... ...... 42% w / w - anthracene oil ........... 2% wt.

Brushes of said mixtures are substantially porous after firing and graphing. A suitable impregnating agent is pressed into these pores to obtain brushes suitable for heavy commutation. Such commutation is, for example, in the case of electric locomotives in winter, mining trolleys, or rolling mills in ironworks.

Claims (1)

DISCLOSURE OF THE INVENTION A composition for the preparation of electrographed brushes, comprising from 48 to 55% by weight of the composition. % of carbon black, 40 to 45 wt. electrode pitch and 0.5 to 2 wt. anthracene oil, characterized in that it further comprises 4 to 8 wt. wooden flour.