JP2013243029A - Method of manufacturing electric contactor for circuit breaker - Google Patents

Abstract

A method of manufacturing an electrical contact for a circuit breaker having a joining structure that does not have a brazing layer or an intermediate metal layer and that does not limit the shape of a material to be joined.
2. A metal electrical contact 1 having a protrusion formed at a tip thereof, and a metal base metal 2 having a hardness lower than that of the electrical contact 1, and a yield stress of the metal base metal 2. The protruding side of the electrical contact 1 is pressed against the metal base metal 2 so that a load of 6 times or more is generated, and the metal base metal 2 is subjected to plastic deformation by the plastic deformation of the metal base metal 2. The protrusion of the electrical contact 1 is inserted, a new surface is created on the joint surface between the electrical contact 1 and the metal base metal 2, and the electrical contact 1 is joined and fixed on the metal base metal. I made it.
[Selection] Figure 1

Description

  The present invention relates to a method of manufacturing an electrical contact used for a circuit breaker.

  Conventionally, an electrical contact for a circuit breaker is composed of an electrical contact and a base metal, and joins an electrical contact containing silver and a base metal containing copper by brazing, resistance electrical welding, friction welding, caulking, or the like. For this reason, as a joint structure, in brazing and resistance electric welding, a brazing layer or an intermediate metal layer needs to be in the shape of a rod between the two metals, and in friction welding, either the electric contact or the mover needs to have a rod shape (for example, Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, Non-Patent Document 1, Non-Patent Document 2).

In Patent Document 1, by performing ultrasonic bonding in addition to caulking bonding of the electrical contactor for the electromagnetic circuit breaker, the hardness of the base metal is suppressed, and crack generation that may occur at the time of caulking bonding is eliminated, and the current carrying capacity is increased. We are working to improve workability and quality during manufacturing.
In Patent Document 2, a method of joining dissimilar metals by friction welding is described. In a rod-shaped material, the diameter of a material having a large thermal expansion coefficient is made larger than that of the other metal, thereby reducing the residual stress at the joining interface. This relaxes and increases the bonding strength.
In Patent Document 3, the fixed and movable arc contacts of the power circuit breaker are joined using a rod-like and tubular copper-tungsten alloy (contact part) and a copper-chromium alloy (other than the contact part) as shown in FIG. And joined by silver brazing.
Patent Document 4 shows a joining structure of dissimilar metals by a friction welding method, and the angle of the joining end is specified.

In Non-Patent Document 1, welding of a contact used for an electromagnetic circuit breaker is joined by resistance welding using a shielding agent and an intermediate metal with alcohol vapor.
In Non-Patent Document 2, as a necessary condition for solid-phase bonding, it is necessary to completely bond the interfaces of metals to be bonded. For complete adhesion, a load stress of about 3.6 times the yield stress is applied. There must be.

JP 59-16221 (Page 2, upper left column, line 16 to upper right column, line 15; FIG. 6) JP-A-6-47570 (page 3, left column, third line to right column, ninth line, FIG. 1) Japanese Patent Application Laid-Open No. 11-176268 (page 4, right column, lines 8 to 14; FIG. 9) JP 2000-246481 A (2nd page, left column, 2nd line to 19th line, FIG. 1)

Machida et al., Japan Welding Society Proceedings Vol. 4 (1986) No. 1, p. 42 Welding and Joining Handbook, 1990, Maruzen, page 184, right column, 2nd to 3rd lines

In such an electrical contactor for a circuit breaker, there is a joint structure as described in the above-mentioned document as a method for replacing the conventional brazing joint. However, in the method using the caulking structure, the electrical contact must be deformed, and the sintered material Such an electrical contact that can hardly be deformed cannot be summarized. In the method by friction bonding, the shape of the electrical contact or the base metal is limited to a rotationally symmetric shape such as a rod or a tube in order to rotate and generate friction. In the method by resistance welding, an intermediate metal is required and the temperature rises to 600 to 800 ° C. near the eutectic temperature, so that the mechanical properties on the base metal side may be lowered.
An object of the present invention is to solve the above problem by providing a method of manufacturing an electrical contact for a circuit breaker having a joining structure that does not have a brazing layer or an intermediate metal layer and the shape of a material to be joined is not limited. It is.

  A method of manufacturing an electrical contact for a circuit breaker according to the present invention comprises a metal electrical contact having a protrusion formed at a tip and a metal base metal having a hardness lower than that of the electrical contact. In order to generate a load of 3.6 times or more of the yield stress of the metal base metal, the protruding side of the electrical contact is pressed against the metal base metal, and the metal base metal is deformed by plastic deformation of the metal base metal. The protrusion of the electrical contact is inserted into the surface, a new surface is created on the joint surface between the electrical contact and the metal base metal, and the electrical contact is joined and fixed on the metal base metal. Is.

  According to the method for manufacturing an electrical contact for a circuit breaker according to the present invention, since the joining can be performed without using a brazing layer or an intermediate metal layer, softening of the base metal can be suppressed, and the electrical contact of the circuit breaker can be joined by pressure welding. In addition to making it possible, the wedge shape that induces plastic deformation of the base metal and the protrusion of the electric contact is recessed into the base metal improves the bondability, and by increasing the contact area between the electric contact and the metal base during bonding It is possible to increase the electrical conductivity during electrical energization. Further, the shape of the electric contactor or the base metal is not limited to a rotationally symmetric shape such as a rod or a tube.

It is a structure front view which shows the joining structure of the electrical contactor for circuit breakers in Embodiment 1 of this invention, (a) shows the form of the component before joining, (b) shows the form of the component after joining. A pair of circuit breaker electric contacts are arranged to face each other, and are side views for explaining the usage. It is the structure front view and side view which show the joining structure of the electrical contactor for circuit breakers in Embodiment 2 of this invention, (a) is the deformation | transformation form immediately after pressurization, (b) cut off this deformation shape by cutting etc. The latter form is shown. It is the structure front view and side view which show the joining structure of the electrical contactor for circuit breakers in Embodiment 3 of this invention. It is the structure front view and side view which show the joining structure of the electrical contactor for circuit breakers in Embodiment 4 of this invention. FIG. 10 is a diagram showing a geometric relationship between the joint surface length and the contact width W in the second embodiment. It is a figure which shows the geometric relationship between the joint surface length in Embodiment 4, and the contact width W. It is a front view which shows the joining apparatus which joins an electrical contact and a base metal and obtains the electrical contactor for circuit breakers shown in Embodiment 1,2,3,4.

Embodiment 1 FIG.
FIG. 1 is a configuration front view showing a junction structure for an electrical contact for a circuit breaker according to Embodiment 1 of the present invention. FIG. 1 (a) shows the shapes of an electrical contact 1 and a base metal 2 before joining, and FIG. The shape of the subsequent component is shown. An electrical contact for a circuit breaker (hereinafter abbreviated as an electrical contact) is constituted by joining an electrical contact 1 and a base metal 2. Both are dissimilar metals, and a metal having higher hardness is generally used for the electrical contact 1 as the voltage to be cut off increases. Metals having high hardness generally do not easily cause plastic flow and are brittle, and therefore, it is necessary to join them without applying a large impact load or plastic flow. When this electrical contact is separated from an electrical contact having a similar configuration on the other side, electricity is cut off.

  FIG. 2 is a side view illustrating a usage mode in which a pair of electrical contacts are arranged to face each other. In the drawing, the lower electrical contact is a fixed electrical contact, and the upper electrical contact is a movable electrical contact. When the electric contacts 1 and 1 of both electric contacts are pressed and contacted, current flows. When the movable electrical contact is rotated about the shaft 7, the electrical contacts 1 and 1 are separated and the current is interrupted.

  The electrical contact in the first embodiment is made of a metal electrical contact 1 having a projection on the joint surface (tip portion) and a metal having a hardness lower than that and capable of plastic deformation along the projection shape of the electrical contact 1. It consists of the base metal 2 The electrical contact 1 has a contact width (one side if a regular triangular prism) is W, the protrusion at the tip is a triangular triangular pyramid shape, and the protrusion height is h. The base metal 2 has a flat plate shape and an initial thickness A (in this case, A = W). The surface of the base metal 2 facing the protrusion of the electric contact 1 is flat, but the protrusion of the electric contact 1 is If it is a triangular pyramid shape, it may be a triangular pyramid concave shape in which only a part thereof is accommodated. The shape of the electrical contact 1 may be one in which a quadrangular pyramid is formed at the tip of the quadrangular column, a polygonal pyramid is formed at the tip of the polygonal column, and a cone is formed at the tip of the cylinder. As the protrusion shape of the electrical contact 1, a shape in which the joint surface length (the length of the joint surface in the contact width direction) is larger than the contact width W of the electrical contact 1 is selected. The principle of bonding is that the oily layer or oxide film on the metal surface is pressed against both metals, creating a surface without a contaminated layer (new surface), and the joint between the two. Is brought into close contact with the distance between the metals to achieve solid-phase bonding. Similar methods include pressure welding and friction welding, but in the embodiment, metals having different hardness differences are joined by being brought into close contact with each other by pressure welding without being rotated by a rotary tool or the like.

  For example, the electrical contact 1 and the base metal 2 are joined by a joining apparatus as shown in FIG. 8 to obtain an electrical contact. A part of the plate-shaped base metal 2 is fixed by the base metal holding device 3. The electrical contact 1 is fixed on the contact fixing base 4. The metal base 2 is pressed against the electrical contact 1 when the pressurization movable part 6 moves in the direction of the electrical contact 1 by driving by the pressurizing device body 5. The opposing tip portion of the electrical contact 1 has a protruding shape, which facilitates the expansion of the contact area of the pre-joining surface portion of the base metal 2 having a hardness lower than that of the electrical contact 1 with pressurization, and the area is increased. This increases the proportion of new surfaces created from the inside.

  In general, when a load of about 3.6 times or more of the yield stress of the metal is applied, the two metals can be brought into close contact with each other, and when the new surfaces are brought into close contact with each other, a metal bond is formed between the two and bonding is achieved. Therefore, a pressure higher than that is applied to the joint surface of the base metal 2. In order to enhance this adhesion, a heater may be placed in the contact fixing base 4 and the electrical contact 1 may be heated through the contact fixing base 4. By adopting such a shape, the reliability of bonding due to the increase in the bonding area is improved, and the electrical conductivity can be improved. At the same time, when an external force that peels off both metals is applied by the wedge shape that allows the protrusion of the electrical contact to be inserted into the base metal, it can be prevented by the frictional force or shape, and the electrical contact 1 can be fixed. Improvement is achieved.

で計算でき、図６に示すように変化する。接合面長さを長くとり、新生面をより多く創出させるためには、 ｈ≧０．１５Ｗ を満たす突起高さｈとすることが望ましい。 Embodiment 2. FIG.
FIGS. 3A and 3B are a configuration front view and a side view showing a joint structure of electric contacts according to Embodiment 2 of the present invention. (A) includes a bulge of the base metal 2 generated at the time of joining, and may be cut to the contact width W of the electrical contact 1 as shown in (b). Here, B is the maximum plate thickness after solid phase bonding of the base metal 2. The tip of the electrical contact 1 has a triangular pyramid-shaped protrusion. In selecting the shape of the triangular pyramid, if the protrusion height of the tip of the electrical contact 1 shown in FIG. 3 is h and the contact width is W, the ratio of the joint surface length and the contact width W is geometrically related,

And changes as shown in FIG. In order to increase the length of the joint surface and create more new surfaces, it is desirable that the projection height h satisfy h ≧ 0.15W.

  As an example, if the height is set to satisfy h = 0.16W, the length of the metal-bonding surface becomes 1.05 times the width of the base metal A (A = W). It was confirmed that the material existing on the gold 2 bonding surface has moved almost from the inside of the material, that is, a new surface.

  A silver-tungsten carbide sintered material is used as the electrical contact 1, and a copper alloy is used as the base metal 2, and both are fixed by pressure welding. At that time, a joining apparatus as shown in FIG. 8 may be used. By adopting such a shape, it is possible to improve the reliability of the joining due to the increase in the joining area, improve the electrical conductivity, and improve the fixability of the electrical contact 1 due to the wedge shape.

で計算できる。 Embodiment 3 FIG.
4A and 4B are a configuration front view and a side view showing a joining structure of electric contacts according to Embodiment 3 of the present invention, which are modifications of Embodiment 2. FIG. The swelling of the base metal 2 generated at the time of joining may be cut to the contact width W of the electrical contact 1. In the third embodiment, the protrusion formed at the distal end portion of the electrical contact 1 is a two-step protrusion shape in which the triangular pyramid protrusion on the joining surface side in FIG. 3 and the triangular pyramid protrusion with a smaller tip angle than that are combined. Have Assuming that the projection height of the entire projection of the electrical contact 1 is h, the contact width is W, the projection height of the small triangular pyramid on the tip side is h ₁ , and the junction width is W ₁ , the junction surface length and the contact width W Ratio is geometric

It can be calculated with

For example, in order to obtain high bonding strength, h = 0.16W, h ₁ = 0.08W, W ₁ = 0.08W
If it is set to a shape that satisfies the above, the joint surface length of the base metal becomes 1.08 times the base width A (A = W). The reason for this shape is that the joint surface can be made longer than the contact width W, and more new surfaces can be created. A silver-tungsten carbide sintered material is used as the electrical contact 1, and a copper alloy is used as the base metal 2, and both are fixed by pressure welding. At that time, a joining apparatus as shown in FIG. 8 may be used. By adopting such a shape, it is possible to improve the reliability of the joining due to the increase in the joining area, improve the electrical conductivity, and improve the fixability of the electrical contact 1 due to the wedge shape.

で計算でき、図７に示すように変化する。接合面長さを長くとり、新生面をより多く創
出させるためには Ｒ≦Ｗ とすることが望ましい。 Embodiment 4 FIG.
FIGS. 5A and 5B are a front view and a side view showing a structure for joining electric contacts according to Embodiment 4 of the present invention. The swelling of the base metal 2 generated at the time of joining is cut to the contact width W of the electric contact 1. Good. A chevron protrusion having a curved surface with a radius of curvature R is provided on the joint surface side of the tip of the electrical contact 1. Ratio of joint surface length to contact width W

And changes as shown in FIG. In order to increase the length of the joint surface and create more new surfaces, it is desirable to satisfy R ≦ W.

For example, if R = 0.83W, the base metal side joining surface length is 1.07 times the base metal width A (A = W), and the base metal 2 joining surface after pressurization is analyzed. It was confirmed that the material existing above has moved from the inside of the material, that is, a new surface. A silver-tungsten carbide sintered material is used as the electrical contact 1, and a copper alloy is used as the base metal 2, and both are fixed by pressure welding. At that time, a joining apparatus as shown in FIG. 8 may be used. By adopting such a shape, it is possible to improve the reliability of bonding due to an increase in the bonding area, improve the electrical conductivity, and improve the fixation of the electrical contact 1 due to the wedge shape.
It should be noted that within the scope of the present invention, the embodiments can be freely combined, or the embodiments can be appropriately modified or omitted.

DESCRIPTION OF SYMBOLS 1 Electric contact 2 Base metal 3 Base metal holding device 4 Contact fixing base 5 Pressurization apparatus main body 6 Pressurization movable part 7 Axis

Claims (5)

It is composed of a metal electrical contact with a protrusion formed at the tip, and a metal base metal having a lower hardness than the electrical contact,
Pressing the protruding side of the electrical contact against the metal base so that a load of 3.6 times or more the yield stress of the metal base is generated,
Due to the plastic deformation of the metal base metal, the metal base metal is made to have a projection of the electrical contact, creating a new surface on the joint surface between the electrical contact and the metal base metal, and A method of manufacturing an electric contactor for a circuit breaker which is bonded and fixed on the metal base metal.   2. The circuit breaker electrical contactor according to claim 1, wherein the protrusion formed at the tip of the electrical contact has a polygonal pyramid shape formed at the tip of the polygonal column or a cone formed at the tip of the cylinder. Production method.   The method of manufacturing an electrical contact for a circuit breaker according to claim 1, wherein the protrusion formed at the tip of the electrical contact has a triangular pyramid shape formed at the tip of the triangular prism.   The protrusion formed at the tip of the electrical contact forms a second-stage triangular pyramid-shaped protrusion that is sharper than the triangular-pyramidal protrusion on the first-stage triangular pyramid-shaped protrusion formed at the tip of the triangular prism. The method for manufacturing an electrical contact for a circuit breaker according to claim 3, wherein the circuit has a two-step projection shape.   The method of manufacturing an electrical contact for a circuit breaker according to claim 1, wherein the protrusion formed at the tip of the electrical contact has a curved surface facing the metal base metal.

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