Contact component and method for the production thereof

Abstract

An electrical contact component and a method for the production thereof. The contact component has a sintered contact element and a contact carrier cast onto the contact element. The grains of the contact element are oriented in a preferential direction.

Claims

1. An electrical contact component, comprising: a sintered contact element; and a contact carrier cast onto said contact element; said contact element and said contact carrier being elements in a cold-worked state; and said contact element having grains oriented in a preferential direction.

2. The contact component according to claim 1, wherein said contact element is a cold-worked element to orient said grains of said contact element in the preferential direction.

3. The contact component according to claim 1, wherein said grains of said contact element are elongate in form and oriented along the preferential direction.

4. The contact component according to claim 1, wherein the preferential direction is parallel to, or substantially parallel to, one or both of a current conducting direction and a longitudinal axis of said contact component.

5. The contact component according to claim 1, wherein said contact element is formed of a material selected from the group consisting of WCu, MoCu, and CuCr.

6. The contact component according to claim 5, wherein said contact carrier is formed of a material selected from the group consisting of Cu, CuCr, and CuCrZr.

7. The contact component according to claim 1, wherein said contact carrier is formed of a material selected from the group consisting of Cu, CuCr, and CuCrZr.

8. The contact component according to claim 1, wherein said contact carrier is formed of a hardenable copper alloy.

9. A method of producing an electrical contact component, the method comprising the following steps: providing a sintered contact element; casting a contact carrier onto the contact element ; and cold working the contact element to orient grains of the contact element in a preferential direction.

10. The method according to claim 9, which comprises producing the contact component according to claim 1.

11. The method according to claim 9, which comprises cold working the contact element after the casting-on of the contact carrier.

12. The method according to claim 9, which comprises cold working the contact element and the contact carrier after the casting-on of the contact carrier.

13. The method according to claim 9, which comprises forming the grains of the contact element into an elongated shape.

14. The method according to claim 9, which comprises defining the preferential direction to lie parallel to, or substantially parallel to, a current conducting direction and/or a longitudinal axis of the contact component.

15. The method according to claim 9, which comprises: cold-working the contact element to thereby subject the contact element to forces that lie perpendicular or substantially perpendicular to a longitudinal axis of the contact element and/or to a current conducting direction of the contact element; or cold working the contact component to thereby subject the contact component to forces that lie perpendicular or substantially perpendicular to a longitudinal axis of the contact component and/or to a current conducting direction of the contact component.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) An embodiment of the invention is explained in more detail on the basis of the figures, in which:

(2) FIG. 1 shows a schematic cross-sectional representation of a vessel with the starting materials for a contact component before a melting process or infiltration process,

(3) FIG. 2 shows the vessel from FIG. 1 after the melting process for

(4) FIG. 3 shows a schematic representation of cold working of the contact component blank from FIG. 2,

(5) FIGS. 4a-b show a schematic representation of the contact component blank from FIG. 2 after the cold working and a finishing step,

(6) FIG. 5 shows an image of the microstructure of a contact component after a melting or infiltration process, and

(7) FIGS. 6a-b show images of the microstructure of the contact component from FIG. 5 after a working process.

DESCRIPTION OF THE INVENTION

(8) FIG. 1 shows a schematic cross-sectional representation of a vessel 8, such as for example a graphite crucible, with the starting materials for producing a contact component 1b (FIG. 4b). There follows a description, by way of example, of the production of a contact component in the form of an erosion tulip.

(9) In a first step, a sintered blank 2a is provided as a contact element in the vessel 8. In this example, the sintered blank 2a has the form of a ring, in order to save sintering material, since the finished contact component has a central through-hole (FIG. 4b). For example, a ring of a tungsten alloy, such as for example WCu, is provided. Arranged over the sintered blank 2a or the contact element is a block of carrier material 6, for example a block of copper. As an alternative to the block of material 6, comminuted carrier material, such as for example smaller offcuts or powder or granules, may also be used. In other words, metal processing remains may be (re)used, or granules or powder, which is less expensive than for example solid material in bar form.

(10) Subsequently, the carrier material is melted and the sintered blank 2a is infiltrated with the carrier material, or the sintered blank 2a is encapsulated in the carrier material, so that a contact component blank 1a is formed. As represented in FIG. 2, the excess carrier material forms the contact carrier 4.

(11) After the casting-on of the contact carrier 4 or the infiltrating of the sintered blank 2a, the contact component blank 1 a is removed from the vessel 8 and subjected to cold working. As schematically indicated in FIG. 3 by arrows, the contact component blank 1a is moved between two (or more) counter-running rollers 10a-b parallel to a longitudinal axis A of the blank 1a. By reducing the rolling gap, that is to say the distance between the rollers 10a-b, the cross section of the blank 1a is reduced or the blank 1a is deformed in an elongated manner. In this case, the grains 14a-c (arranged or formed arbitrarily due to the sintering process) of the sintered blank 2a are rolled flat, that is to say deformed in an elongated manner, pulled out or stretched out in the direction of the longitudinal axis A. After the rolling, the grains 16a-c of the blank 2a are in a state in which they are oriented along the longitudinal axis A of the contact component. In other words, the grains 16a-c of the contact element 2b or of the worked sintered blank 2a are oriented along a preferential direction B (parallel or substantially parallel to the longitudinal axis A or to the current conducting direction).

(12) The elongated grains 16a-c oriented along the preferential direction B have the effect that the contact element 2b or the contact component 1b has improved conductivity and a lower electrical resistance in the direction B, since the current flowing through the elongated grains 16a-c in the preferential direction B has to overcome fewer grain boundaries.

(13) Furthermore, the contact carrier 4 is hardened by the cold working or cold rolling. In other words, predetermined and reproducible mechanical properties can be achieved over the entire volume or the length of the contact component 1a by way of the degree of working of the contact carrier 4 or of the contact component 1a, irrespective of properties of the starting materials that may deviate from these predetermined properties. In other words, by means of the method described above, a reproducible profile of properties can be achieved for each individual contact component 1b in a simple, quick and consequently low-cost way.

(14) The contact component 1b schematically represented in FIG. 4a after the cold working is subsequently provided with a central hole 12 (FIG. 4b) and the contact element 2b or the contact component 1b is shaped appropriately for the forming of an erosion tulip (not represented).

(15) According to an alternative refinement, provided in the vessel 8 is a central mandrel (not represented), over which the annular sintered blank 2a is fitted. The mandrel creates a hollow space in the contact component blank during the casting-on, so that, after the infiltration of the carrier material 6, the hollow space forms the hole 12, or the hollow space only has to undergo minor finishing to obtain the hole 12. In this way, less carrier material has to be melted during production, thereby saving time and energy.

(16) In a way corresponding to the method described above, an erosion pin (not represented) matching the tulip described can be produced with a contact element and a contact carrier cast on it. As a difference from the method described above, in this case the sintered blank does not have the form of a ring, but for example the form of a (solid) cylinder, which forms the contact tip of the pin after the forming of a contact component according to the method described above (without the provision of a hole 12) and is designed to engage in the hole 12 in order to close a switch contact of an electrical switch.

(17) FIG. 5 shows a depiction of the microstructural state of a contact component in the region of a WCu 80/20 contact element 2a after a sintering process and an infiltration process with a carrier material. It can be seen well that grains 14a-c of the contact element 2a are formed and arranged arbitrarily.

(18) FIG. 6a and FIG. 6b show the microstructural state of the contact component from FIG. 5 in the region of the contact element after a working process; in this case, the contact component was round-hammered. It can be clearly seen that, as a result of the working, the grains 16a-c have a preferential direction B or are in a state of having been deformed in an elongated manner. The electrical conductivity parallel to the preferred orientation B of the worked structure is measurably higher than at right angles thereto. In the present case, this was an improvement of the electrical conductivity of at least 1.5 MS/m.

LIST OF REFERENCE SYMBOLS

(19) 1a Compact component blank 1b Compact component/tulip 2a Sintered blank 2b Contact element 4 Contact carrier 6 Block of carrier material 8 Vessel/crucible 10a-b Roller 12 Hole 14a-c Grain after sintering 16a-c Grain after working A Longitudinal axis of the contact component B Preferential direction