EP3168944A1 - Sliding contact - Google Patents

Abstract

The invention relates to a sliding contact (10), in particular micro-grinding contact for electrically conductive contacting a sliding track, a slip ring or the like, wherein the sliding contact has a spring wire (11) which serves as an electrical conductor, wherein by means of the spring wire, a contact force of the sliding contact on the sliding track is formed, wherein the sliding contact comprises a contact piece (12), which serves for contacting the slideway, wherein the contact piece is connected to a free end of the spring wire, such that the spring wire holds the contact piece for abutment against a slideway, wherein the contact piece in one piece trained and positively and / or non-positively connected to the spring wire.

Description

The invention relates to a sliding contact, in particular micro-grinding contact for electrically conductive contacting a sliding track, a slip ring or the like, wherein the sliding contact has a spring wire which serves as an electrical conductor, wherein by means of the spring wire, a contact force of the sliding contact can be formed on the sliding track.

So-called micro-grinding contacts are regularly formed by spring wires, which are gold-plated and in direct contact with a sliding track. The slideway can also be gold plated, so that a reliable electrical contact is possible. The slideway may be rod-shaped, round, for example, designed as a slip ring, or have any other geometric shape or extension, which is in principle contactable by means of a sliding contact. It is essential that a relative movement of the grinding path and sliding contact can take place. In particular, in the case of spring wires coated with gold, another metallic coating, for example nickel, is galvanically applied under an electrodeposited gold layer. By a relative movement of the spring wire resting directly on the slideway on the slideway, abrasion of the gold layer takes place as a function of a movement intensity leads to a more or less severe wear of the gold layer. When the gold layer is worn, the underlying metallic layer is exposed, which is then in direct contact with the slideway. However, this results in a poorer conductance of a sliding contact connection thus formed and a reduced corrosion resistance. A wear resistance increased by the wear can lead to poorer power transmission, incorrect measured values or signals as well as contact interruptions. It would therefore be necessary to replace such worn sliding contacts. However, micro-grinding contacts are often installed in such devices or applications that an exchange is not readily possible. Also, a wear of a micro-grinding contact is not obvious, that is, it is not noticed that a micro-grinding contact is worn by abrasion of its gold layer, as continues to be an inadequate power transmission.

It is therefore an object of the invention to provide a sliding contact, a sliding contact arrangement and a method for producing a sliding contact, which allows a reliable contact.

The object is achieved by a sliding contact with the features of claim 1, a sliding contact arrangement with the features of claim 16 and a method for producing a sliding contact with the features of claim 17.

The sliding contact according to the invention, in particular micro-grinding contact for electrically conductive contacting a sliding track, a slip ring or the like, has a spring wire which serves as an electrical conductor, wherein by means of the spring wire, a contact force of the sliding contact can be formed on the sliding track, wherein the sliding contact has a contact piece, that is used for contacting the grinding path, wherein the contact piece is connected to a free end of the spring wire, such that the spring wire, the contact piece to the plant holds on a sliding track, wherein the contact piece is integrally formed and positively and / or non-positively connected to the spring wire.

Due to the fact that not only the spring wire of the sliding contact can be contacted with the grinding path, no abrasion can occur on the spring wire. Rather, the contact piece of the sliding contact with the grinding path can be contacted, wherein the contact piece can be easily formed so that it wears less during a lifetime of the grinding path or a device in which the sliding contact is installed. The spring wire then serves only to transmit electrical energy to the contact piece and to form a spring force with which the contact piece can be pressed against the grinding path. The spring wire therefore does not necessarily have to be coated with gold, so that the sliding contact can also be formed in a particularly cost-effective manner. Further, the contact piece is connected to the grinding path facing the free end of the spring wire. Under a free end can be understood here also a portion of the spring wire. Due to the direct connection of the contact piece and the spring wire, the spring wire holds the contact piece without the contact piece having to be received in a further holder or guide. Essential for a cost-effective production of the sliding contact and the one-piece design of the contact piece and its direct, positive and / or non-positive and electrically conductive connection with the spring wire.

The consumable contact piece can form a contact surface for engagement with a grinding path. The contact piece can be designed so that it is consumed by an abrasive removal, wherein the contact piece can provide a sufficient amount of material for abrasive removal, so that a service life of the sliding contact is substantially increased and the sliding contact during a total useful life of a device less frequently or not replaced must become. Furthermore, the contact surface can also be formed on the contact piece, which contact surface is designed to rest against a sliding track. If the grinding path is a slip ring or the grinding path is formed by the slip ring, the contact surface can also be adapted to a surface contour of the slip ring.

The contact piece is particularly easy to produce when the spring wire is inserted with its end in a groove formed in the contact piece and pressed with the contact piece. Thus, first, the spring wire and the contact piece can be made independently, wherein in the contact piece then a groove is formed, which is adapted to a geometry or a diameter of the spring wire, so that the spring wire can be inserted into the groove.

Subsequently, it may be provided to plastically deform the contact piece, for example, by a punch, which compresses the material of the contact piece in the groove and the spring wire in the groove receives or connects the contact piece positively and / or non-positively with the spring wire. The stamp may, for example, have a semi-circular stamp surface, so that a bead surrounding the spring wire is formed during the deformation. Alternatively, the stamp may also have a smooth or flat stamp surface, so that the contact piece in the region of the groove is flat or straight deformed. Compared with, for example, introducing a hole in the contact piece for receiving the spring wire, the formation of the groove, this is a much simpler production engineering process for producing the connection of contact piece and spring wire.

Thus, by pressing the contact piece may be plastically deformed. When the pressing is performed with a punch, the material of the contact piece is displaced in a region of the groove or in a region surrounding the groove and flows in the direction of the spring wire, so that the spring wire is embedded substantially in the groove of the material of the contact piece ,

Optionally, by compressing the spring wire may be plastically deformed at its free end. If the spring wire has, for example, a round cross-sectional shape, this cross-sectional shape, for example oval, can be deformed by the pressing. Thus, by pressing not only a positive connection with the spring wire but also a positive connection can be formed. Also, the spring wire can be deformed at its end transverse to its longitudinal extent with a deviating angle or arc by the pressing, so that the spring wire can not be pulled out of the groove. In principle, however, it is also possible to deform the spring wire already before the pressing at its end, so as to obtain a positive connection of contact piece and spring wire.

Advantageously, the material of the contact piece can surround the end of the spring wire predominantly or completely. Depending on a depth of the groove or a displaced by the pressing amount of material of the contact piece, this material may surround the end of the spring wire, at least to the extent that the spring wire is positively connected with respect to its cross-section with the contact piece. When the material of the contact piece surrounds the spring wire with respect to its cross section, the end of the spring wire is completely accommodated in the contact piece.

The contact piece may also be materially connected to the spring wire, preferably by means of gluing, welding or soldering. By the cohesive connection of the contact piece with the spring wire, a connection of spring wire and contact piece can be secured. As a result, it can be prevented that the contact piece is released from the spring wire in the course of its service life or possibly twisted relative to the spring wire. For example, an adhesive material can be introduced into the groove before pressing. It is too possible to form a fuse by means of adhesive material, by welding or soldering after pressing.

Depending on the requirements of the sliding contact arrangement, the sliding contact can also have a plurality of spring wires. Thus, two or more, for example, arranged parallel to each other spring wires relative to the contact piece. The spring wires can each be attached to the sliding contact in the same way or differently. Optionally, the spring wires may each have a different shape.

It is particularly advantageous if the contact piece is sintered, and if a precursor of the contact piece is formed by pressing a powder mixture. A material composition of the contact piece can then be easily determined by the powder mixture. First, then the precursor or a green body can be formed by pressing, in which case, for example, a groove for inserting the spring wire by the shape of a mold can be particularly easily formed in the formation of the precursor. The precursor or the green body can subsequently be sintered by high-temperature treatment. The sintered contact piece then also has particularly advantageous properties relating to the contacting of the grinding path.

The contact piece may comprise carbon and metal, with a metal content of at least 80, preferably at least 90, more preferably at least 97 to 99 wt .-% may be. The contact piece can therefore also be produced from a powder mixture of carbon and metal. If the proportion of metal is particularly high, the contact piece can also be well deformed and connected to the spring wire. At the same time, the carbon can cause a good lubrication of the contact piece when moving on a sliding track. The carbon may preferably be graphite.

The metal may be copper, silver, silver-plated copper, gold, as well as a mixture or alloy of any of these metals. In particular, a mixture can be easily formed when the metals are in powder form.

Further, the spring wire may be free of gold. Since the spring wire is no longer directly contacted with the grinding path, a surface of the spring wire must not necessarily be protected from corrosion or have advantageous electrical properties. It can therefore be dispensed with a galvanic coating with gold and other layers of metals, such as nickel. Thus, significant cost savings in the production of the sliding contact can be achieved.

A cross section of the spring wire may have a thickness of 0.1 to 0.8 mm. The thickness of the cross section is understood to be a maximum extent of the cross section of the spring wire. If the spring wire is round, the thickness is a diameter of the spring wire. The fact that comparatively thin spring wires are used to produce a sliding contact, the sliding contact can be made particularly small.

The same applies to the contact piece, in which a cross section may have a thickness which is 0.1 to 0.5 mm greater than a thickness of the spring wire. The thickness of the contact piece is understood to be the smallest extent of the contact piece relative to its cross section. The contact piece may be formed, for example, in the form of a plate having a rectangular or square cross-section. The relevant cross section of the contact piece is preferably in a plane with the cross section of the spring wire. Since then the cross section of the contact piece is always greater than the thickness or a cross section of the spring wire, the spring wire can always be embedded in the contact piece positively and / or non-positively. In addition, it becomes possible to form the contact piece particularly flat, so that no constructive change of a device or a device by the use of the sliding contact with the contact piece is required because the contact piece is not substantially thicker than the spring wire.

At the end of the spring wire, a connection zone may be formed, wherein the connection zone may be reshaped, roughened or coated. When the connection zone is reshaped, d. H. the spring wire is not straight running at the end, a positive connection of spring wire and contact piece can be made particularly simple. Even if the end of the spring wire is roughened material of the contact piece, for example, during pressing, penetrate into a roughened surface of the spring wire and produce a particularly intimate connection with the spring wire.

The sliding contact arrangement according to the invention comprises a sliding track or a slip ring, a sliding contact holder and a sliding contact according to the invention, wherein an end facing away from the slip ring of the spring wire is connected to the sliding contact holder, and wherein the contact piece is contacted with the slip ring. Advantageous embodiments of the sliding contact arrangement result from the subclaims referring back to the device claim 1.

In the inventive method for producing a sliding contact, in particular micro-grinding contact for electrically conductive contacting a sliding track, a slip ring or the like, the sliding contact on a spring wire, which serves as an electrical conductor, wherein by means of the spring wire, a contact force of the sliding contact can be formed on the sliding track, wherein the sliding contact has a contact piece that serves for contacting the sliding track, wherein the contact piece is connected to a free end of the spring wire, such that the spring wire holds the contact piece for abutment with a sliding track, wherein the contact piece is integrally formed and positively and / or positively connected to the spring wire becomes. Advantageous embodiments of the method will become apparent from the dependent claims on the device claim 1 dependent claims.

The invention will be explained in more detail with reference to the accompanying drawings.

Fig. 1

eine perspektivische Darstellung eines Schleifkontakts;

Fig. 2

eine Vorderansicht des Schleifkontakts;

Fig. 3

eine Draufsicht des Schleifkontakts.

Show it:

Fig. 1

a perspective view of a sliding contact;

Fig. 2

a front view of the sliding contact;

Fig. 3

a plan view of the sliding contact.

A synopsis of Fig. 1 to 3 shows a sliding contact 10, which is designed for contacting a grinding path or a slip ring, not shown here. The sliding contact 10 is formed from an electrically conductive spring wire 11 and a contact piece 12. The contact piece 12 is formed in one piece, and has a contact surface 13 which can be brought into contact with a sliding track. An end 14 of the spring wire 11 facing away from the contact piece 12 can be fastened to a holder (not illustrated here) so that the contact piece 12 can be pressed against the sliding track under prestress with a spring force of the spring wire 11. A free end 15 of the spring wire 11 is fixedly connected to the contact piece 12. For this purpose, in the production of the contact piece 12 by sintering from a powder mixture of carbon and metal, with a predominant metal content, a green body is first pressed, which has a groove into which the spring wire 11 can be inserted. After sintering of the green body, the contact piece 12 is obtained, in which case the spring wire 11 is inserted with the end 15 in the groove. By means of a punch not shown here, the contact piece 12 and the spring wire 11 is pressed. That is, the punch penetrates into a surface 16 of the contact piece 12 and deforms or displaces the material of the contact piece 12 by simply pressing in the punch, that the end 15 of the spring wire is surrounded by material of the contact piece 12. By the penetration of the punch in the surface 16, two parallel grooves 17 are formed in the contact piece 12 and each bead 18 formed with the thus displaced material of the contact piece 12, covering a top 19 of the end 15 as far as possible. Optionally, the stamp may also have a smooth or flat stamp surface, so that a flat surface, not shown here, of a contact piece is obtained. The deformation with the stamp creates a frictional connection between the end 15 and the contact piece 12. It also comes to a non-illustrated deformation of the spring wire 11 and the end 15, so that a positive connection between the spring wire 11 and the contact piece 12 is formed. A periphery 20 of the end 15 is substantially surrounded by the material of the contact piece 12, leaving only a gap 21 at which the end 15 is not covered with the material of the contact piece 12.

Claims (17)

Sliding contact (10), in particular micro-grinding contact for electrically conductive contacting a sliding track, a slip ring or the like, wherein the sliding contact has a spring wire (11) which serves as an electrical conductor, wherein by means of the spring wire, a contact force of the sliding contact can be formed on the sliding track,
characterized,
in that the sliding contact has a contact piece (12) which serves for contacting the sliding track, wherein the contact piece is connected to a free end (15) of the spring wire, such that the spring wire holds the contact piece for engagement with a sliding track, wherein the contact piece is in one piece trained and positively and / or non-positively connected to the spring wire. Sliding contact according to claim 1,
characterized,
in that the consumable contact piece (12) forms a contact surface (13) for engagement with a sliding track. Sliding contact according to claim 1 or 2,
characterized,
that the spring wire (11) is inserted with its end (15) into a groove formed in the contact piece (12) and pressed with the contact piece. Sliding contact according to claim 3,
characterized,
that the contact piece (12) is plastically deformed by the pressing. Sliding contact according to claim 3 or 4,
characterized,
in that the crimping of the spring wire (11) at its end (15) is plastically deformed. Sliding contact according to one of claims 3 to 5,
characterized,
in that the material of the contact piece (12) predominantly or completely surrounds the end (15) of the spring wire (11). Sliding contact according to one of the preceding claims,
characterized,
that the contact piece (12) is materially connected to the spring wire (11), preferably by means of gluing, welding or soldering. Sliding contact according to one of the preceding claims,
characterized,
in that the sliding contact (10) has a plurality of spring wires (11). Sliding contact according to one of the preceding claims,
characterized,
that the contact piece (12) is sintered, and that a precursor of the contact piece is formed by pressing a powder mixture. Sliding contact according to one of the preceding claims,
characterized,
that the contact piece (12) comprises carbon and metal, wherein a metal content of at least 80, preferably at least 90, particularly preferably from at least 97 up to 99% by weight. Sliding contact according to claim 10,
characterized,
that the metal is copper, silver, silver-plated copper, gold, a mixture or an alloy of one of these metals. Sliding contact according to one of the preceding claims,
characterized,
that the spring wire (11) is free of gold. Sliding contact according to one of the preceding claims,
characterized,
that a cross section of the spring wire (11) has a thickness of 0.1 to 0.8 mm. Sliding contact according to one of the preceding claims,
characterized,
that a cross section of the contact piece (12) has a thickness which is 0.1 to 0.5 mm greater than a thickness of the spring wire. Sliding contact according to one of the preceding claims,
characterized,
in that a connection zone is formed at the end (15) of the spring wire (11), wherein the connection zone is deformed, roughened or coated. A sliding contact assembly comprising a slip path or a slip ring, a sliding contact holder and a sliding contact (10) according to any one of the preceding claims, wherein an end (14) of the spring wire (11) facing away from the slip ring is connected to the sliding contact holder, and wherein the contact piece (12) contacted with the slip ring. A method for producing a sliding contact (10), in particular micro-grinding contact for electrically conductive contacting a sliding track, a slip ring or the like, wherein the sliding contact comprises a spring wire (11) which serves as an electrical conductor, wherein by means of the spring wire, a contact force of the sliding contact on the sliding track can be trained,
characterized,
in that the sliding contact has a contact piece (12) which serves to contact the sliding track, wherein the contact piece is connected to a free end (15) of the spring wire, such that the spring wire holds the contact piece for engagement with a sliding track, the contact piece being in one piece trained and positively and / or non-positively connected to the spring wire.

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