DE478021C - Gleit- or Schleifkoerper z. B. for dynamo brushes made of mechanically crushed metal, e.g. B. copper or copper alloys, and an admixture of graphite - Google Patents

Description

Sliding or grinding body z. B. for dynamo brushes on 'mechanical Ways crushed metal, e.g. B. copper or copper alloys, and an admixture of graphite The object of the invention relates to bodies, which are made of finely ground Metal produced with the addition of other components, for example graphite and are so far burned or sintered at a suitable temperature that. they one have sufficient cohesion or strength. Such bodies are used, among other things, to produce electrical sliding contacts, Pantographs, etc. They are also used as bearing metal, specifically for fast moving and sloping waves.

The metals copper, brass, Bronze etc., possibly also as a mixture with other metals, e.g. B. tin, Zinc, iron, etc. The addition of graphite was made to meet various needs adjusted and averaged about 10 to 20%. The finely divided metal was obtained by crushing massive pieces, as there is a solid, heat and electricity must have a highly conductive structure. So far, metals have been used, some of them Particles = in the crushed state have a shape that is characterized by that one or more dimensions are particularly strongly developed at the expense of the other and the individual particles were in the form of sheets or rods. This explains easily because they were won in the same way as the so-called bronze colors are produced, spatially in hammer or mortar devices, which naturally. create thin and elongated particles.

In contrast, the invention has a metal powder as the starting material, that, although they are also produced mechanically, but are as spherical as possible, There are massive granules, the fabrication of which is only possible through newer processes was made possible. The size of the individual granules is the purpose customized. It is essential that the same - compared to the earlier material with stretched Shape have a shape as close as possible to the spherical shape. The resulting The advantages are manifold.

It is known that the mode of action of such pressed bodies on the fine distribution of metals -based. From this it follows without further ado that also the shape of the individual particles must be of influence. To the closer Explanation are provided in Fig. Z and a, which are a schematic representation of sections by pressing bodies, once in the known design, the other time according to the invention illustrate, and in a very substantial enlargement.

The elongated metal corpuscles in Fig. R, which in detail, like As luck would have it, they are stored, partly lying flat on top of each other, partly flat Part of them are bulky, butt against each other and form proportionately large cavities, which are filled by the admixtures, mainly graphite. The bodies therefore have a relatively uneven structure, they show either a fibrous structure, or alternating places that contain a lot of graphite are, with those that contain a lot of metal. The wear and tear when sanding is therefore an irregular one. If the bodies are used as sliding contacts, so the uneven structure easily favors a fire - and burns form in the contact itself or in the pieces of power line sliding on it. In addition there is also the fact that the electrical resistance of the contact pieces is uneven is.

When used as a bearing metal, the uneven structure forms also the cause of various disadvantages. The strength is reduced, and since these are also abrasive parts, the wear increases if leaflets that have just been stored flat reach the plant. The same can with stronger burdened. Storage can also cause other malfunctions. Due to the uneven Porosity also affects the bearing shell's ability to absorb and release oil, which play an important role precisely for such camps.

In contrast, Fig. Z illustrates how the use of spherical Prevents the formation of larger voids and a relatively large one Uniformity of the structure of the body in all directions is achieved. The individual corpuscles are considerable in relation to the abrasive surface better anchored in the compact, and their premature detachment is prevented. However, the use of grains that are as uniform and round as possible has the advantage much larger and more even bond and therefore more even wear.

The invention therefore achieves a number of advantages: A uniform structure is achieved, which gives the pressed body greater strength gives and consequently reduces its wear and tear. When used as a Sliding contact, the new body has a more uniform electrical resistance and accordingly improved conductivity. Ex can therefore be in smaller dimensions being held. The current transfer becomes more uniform, as does the wear on the pressed body.

When used as a bearing metal, the heat dissipation becomes more uniform and improves the oil suction.

According to recent research (see L. Binder, about the processes at the Brushing of slip rings and commutators, Scientific publications from the Siemens concern, volume z, page 158/161) the current transfer takes place between a brush and the contact piece underneath it does not cover the entire contact surface instead of. Rather, small particles are detached from the brush, some of which are cylindrical or assume spherical shape such that. the brush rolls on them. at If the effect is uneven, the small particles are overloaded with electricity until they glow. This worsens the current transfer and the formation of burns brought about the grinding surfaces. In the case of a grinding wheel that has the familiar structure owns, must. accordingly the individual metal particle initially after its detachment be brought into spherical or cylindrical shape. Depending on the location of the individual particles in the sliding contact, no matter how slight an increase the same, since the elongated bodies must first be reshaped. At a Sliding contact according to the invention, this reshaping work is saved, since the individual Metal particles already have spherical shapes. The sliding contact therefore runs more smoothly with less wear and tear and largely avoids firing, too accordingly the wear in both the contact and the one below Slider less.

The processes that take place in the plain bearing are naturally similar, and therefore the new invention also makes this field of application considerable Benefits achieved.

It is particularly advantageous if the size of the individual is convex Grain is kept as evenly as possible.

One should initially assume that one is made up of a mixture of larger ones and smaller spherical grains a particularly dense and therefore particularly good should receive running compact. In contrast, it has been shown that a uniform grain is preferable, especially with regard to the last-mentioned process when sliding the contact piece or the Camp. If the grain size is uniform, the small rolls that are in between also fall the contact surfaces are more evenly located, and as a result it finds a more uniform application of the pressed body over the entire surface instead. Through this Of course, wear and tear is also prevented, and the load on the contact strips, be it by weight or by current, higher can be chosen.

Claims (1)

PATRNTANSPRUCI3: sliding or grinding body z. B. for dynamo brushes from mechanically crushed metal, e.g. B. copper or copper alloys, and an admixture of graphite which sintered together at a suitable temperature is, characterized in that the individual particles are used as the starting material metal powder used are approximately spherical and as equally large as possible.