JP2005353529A - Manufacturing method for movable contact of electromagnetic contactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for movable contact of an electromagnetic contactor for improving a conforming article ratio by suppressing occurrences of junction failures of brazing. <P>SOLUTION: The method overlaps a reinforced base metal unit 3 made of steel (for example, made of SPPC) on a rear face of a cooper-made strip-shaped conductive plate 1 of which the opposed ends are provided with a pair of contacts 2, so as to braze each other. The method forms in advance a trapezoidal positioning dowel hole 3a at two places of plate face of the base metal unit 3, and forms a dowel hole 1a with which the dowel is engaged on the plate 1. The method also prepares a sheet-like brazing material 4 of which the thickness t is thinner than the height h of the dowel and which is cut in a size corresponding to an outer shape of the plate 1 to penetrate a dowel engaging hole 4a at a prescribed position. A brazing process overlaps a tip end of the dowel 3a of the base metal unit 3 onto the plate 1 in a state in which a tip end of the dowel 3a of the base metal unit 3 is engaged with the dowel hole 1a of the plate 1 with sandwiching the sheet-like material 4, assembles the materials to a tray-like jig 7 for oven, brazing and brazes by in this state by passing through a vacuum heating furnace. Whereby, a movable contact with excellent quality is provided, wherein the material 4 flows all over the entire area with the plate 1 and the base metal unit 3 overlapped each other therein to join them without leaving any gap. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a bridge-shaped movable contact provided in a contact mechanism of an electromagnetic contactor.

As is well known, in an electromagnetic contactor, as a movable contact of a contact mechanism, a bridge-shaped movable contact having a pair of movable contacts at both ends of a conductive plate is mounted on a contact holder, and an electromagnet for operation and a return spring are mounted. The movable contact is driven and operated to the open and closed positions, and at the contact closed position, the movable contact is further biased to press the movable contact against the fixed contact, The contact pressure required for energization is applied between the contacts.
Since a large operating force is applied to the movable contact during the closing operation, SPCC (ordinary steel cold-rolled steel) or the like is provided on the back surface of the copper conductor plate in order to ensure the necessary mechanical strength (rigidity). A laminated contact structure is known in which reinforcing base plates made of steel plates having higher rigidity than copper are stacked and brazed between the two (for example, see Patent Document 1).
FIG. 2 is a structural diagram of the above-described laminated movable contact, wherein 1 is a strip-shaped conductive plate made of copper, 2 is a movable contact brazed to both ends of the lower surface of the conductive plate 1, and 3 is a back surface of the conductive plate 1. Steel reinforcing bases such as SPCC with a thickness of about 1 mm, which are superposed and brazed, 4 is a brazing material (silver brazing) for joining the conductive plate 1 and the reinforcing base 3, and 5 is a contact with the conductive plate 1 2 is a brazing material (silver brazing), and a bridge-shaped movable contact 6 is constituted by these.

Next, a conventional method for manufacturing the movable contact 6 will be described with reference to FIGS. That is, dowels 3a that form two-stage trapezoidal protrusions are formed by pressing in the reinforcing base 3 at two locations along the longitudinal direction, and dowel holes corresponding to the dowels 3a are formed in the conductive plate 1. 1a is processed, and the two-stage dowel 3a is fitted into the dowel hole 1a for positioning. Here, the protruding height of the dowel 3a is approximately the same as the thickness (1 mm) of the reinforcing base 3 so that the dowel 3a can be easily fitted into the dowel hole 1a. In addition, a plate-like brazing material (commercially available product) is cut into a predetermined size and used for the brazing material 4. Further, the brazing material 5 is previously applied to the surface of the contact 2 on the side of the conductive plate 1 by, for example, rolling.
In the brazing step, first, as shown in FIG. 3, the contact 2, the conductive plate 1, the brazing material 4, and the reinforcing metal base 3 are sequentially stacked on a tray-like assembly jig (made of carbon) 7. 2 is set in a fixed position (furnace assembly) and then passed through a vacuum heating furnace to braze between the conductive plate 1 / contact 2 and the conductive plate 1 / reinforcement base 3 at the same time as shown in FIG. A movable contact 6 is obtained.
Japanese Patent Application Laid-Open No. 11-232980

Incidentally, among the movable contacts manufactured by the above-described conventional manufacturing method, when the movable contacts having poor bonding are examined and viewed, the conductive plate 1 and the reinforcing table are formed at the front end side of the movable contacts as shown in FIG. A gap g remains in a wide area G with the gold 3.
Therefore, the inventors have investigated the cause of the above-described bonding failure. As a result, in addition to the warp of the conductive plate 1 and the reinforcing base 3, the displacement of the set position on the jig, etc., the following occurs. It turns out that it is involved in the cause. That is, when the thick sheet-like brazing material 4 (see FIG. 3) placed concentrated on the central portion of the conductive plate 1 is melted by heating and heating in the brazing process in the furnace, ideally the brazing material As the metal melts, the reinforcing base 3 sinks due to its own weight, and the tab 3a fits into the tab hole 1a. The molten brazing material flows into the reduced gap between the conductive plate 1 and the reinforcing base 3 due to surface tension. , Diffused and brazed with almost no gap left to the tip of the contact.

  However, the copper conductive plate 1 and the steel reinforcing base 3 such as SPCC have different thermal expansion coefficients (the expansion coefficient of copper is approximately 1.6 times that of SPCC). Therefore, as shown in FIG. The difference between the thermal expansion of 1 (arrow A) and the thermal expansion of the reinforcing base 3 (arrow B) causes a relative shift in the longitudinal direction of the movable contact. For this reason, the sinking of the base plate 3 indicated by the arrow C is performed while the intermediate step portion of the two-stage dowel 3a contacts the edge of the dowel hole 1a and is hooked on the edge of the dowel hole 1a during the in-furnace brazing process. Stops and the entire dowel 3a is not properly fitted into the boss hole 1a. As a result, while the gap between the conductive plate 1 and the reinforcing base 3 is widened, the molten brazing material 4 is solidified while stopping the flow and diffusion due to the surface tension, and the brazing material 4 is initially placed. In the distal end side region G of the movable contact that is distant from the central position of the conductive plate 1, the large gap g remains between the conductive plate 1 and the reinforcing base 3 and is not joined (see FIG. 5).

  Accordingly, an object of the present invention is to provide an improved method of manufacturing a movable contact so as to prevent the occurrence of brazing joint failure and improve the yield rate.

In order to achieve the above object, according to the present invention, a movable electromagnetic contactor in which a steel reinforcing base metal is overlapped and brazed on the back of a copper strip-shaped conductive plate provided with a pair of contacts at both ends. The contact is manufactured by the following method. That is, a dowel for positioning is formed in advance on the plate surface of the reinforcing base metal, and a dowel hole for fitting the dowel is formed in the conductive plate, and the thickness of the brazing material is thinner than the height of the dowel, and the conductive plate Prepare a sheet-like brazing material that has been cut into a size corresponding to the outer shape and formed dowel insertion holes at predetermined positions, and in the brazing process, a reinforcing base metal is sandwiched between the sheet-like brazing material on the conductive plate. It is superposed at a fixed position, and the furnace is brazed in this state to perform brazing in the furnace (Claim 1).
In addition, trapezoidal dowels are formed on the reinforcing base metal at two plate surfaces along the longitudinal direction, and the reinforcing base metal is stacked on the conductive plate with the sheet-like brazing material sandwiched in the brazing process. When set together, the tip of the dowel is inserted into the dowel hole of the conductive plate so that the conductive plate and the base metal overlap each other at a fixed position.

  According to the brazing method described above, since the sheet-like brazing material is set to be thinner than the dowel height of the reinforcing base metal, the reinforcing base metal is overlapped in place with the brazing material sandwiched on the conductive plate. In the set state, a pair of dowel tip portions that penetrate the hole of the brazing material and protrude to the back surface side thereof are fitted into the dowel holes of the conductive plate and correctly positioned. Thus, even if a longitudinal thermal expansion difference occurs between the conductive plate and the reinforcing base metal in the subsequent heating and heating process of the furnace, the reinforcing base metal dowels come out of the dowel holes of the conductive plate and There is no such thing as hanging on the edge. As a result, the sinking of the reinforcing base due to the melting of the brazing material is not hindered, and the brazing material flows to the corners of the entire overlapping surface of the conductive plate and the reinforcing base by surface tension without leaving a gap. It is brazed. This eliminates the occurrence of poor bonding and greatly improves the yield of movable contacts.

Embodiments of the present invention will be described below based on the examples shown in FIGS. 1 (a) and 1 (b). In addition, (a) is a furnace assembly state in which the constituent members of the movable contact are set on a tray-like jig, and (b) is a diagram of the conductive plate, the sheet-like brazing material, and the reinforcing base in FIG. It is the perspective view which looked at each member from the lower surface side, and attaches | subjects the same code | symbol to the member corresponding to FIGS.
Here, the reinforcing base metal 3 is formed by pressing a single-stage trapezoidal dowel 3a that protrudes toward the conductive plate 1 at two locations along the longitudinal direction. The plate 1 has a dowel hole 1a in which a hole diameter larger than the outer diameter of the dowel 3a is set to set a clearance for the difference in thermal expansion. The sheet-like brazing material 4 extends to a thickness of about 0.2 mm whose thickness t is thinner than the height h of the dowel 3a, and the width and length are substantially the same as the outer size of the conductive plate 1. After cutting into a corresponding strip, a dowel fitting insertion hole 4a corresponding to the dowel 3a is opened on the surface.

In the brazing process, the members are sequentially stacked on the tray-like jig 7 in the same manner as described with reference to FIG. 3, and the brazing is performed by passing through a vacuum heating furnace on the furnace assembly set. Here, in the state of the furnace assembly set of FIG. 1A, the thickness t of the brazing material 4 is set to be thinner (t <h) than the height h of the dowel 3a of the reinforcing base 3, so the dowel 3a Is held in a laminated state in which the dowel tip protruding through the hole 4a of the brazing material 4 and projecting to the back side thereof is fitted into and engaged with the dowel hole 1a of the conductive plate 1.
As a result, even if a longitudinal thermal expansion difference occurs between the conductive plate 1 and the reinforcing base 3 in the heating and heating process in the subsequent furnace, the dowel 3a of the reinforcing base 3 becomes the dowel hole of the conductive plate 1. It does not slip out of 1a or get caught on the edge of the dowel hole 1a. As a result, the sinking of the reinforcing base 3 due to the melting of the brazing material 4 is not hindered, and the molten brazing material 4 has a corner of the entire overlapping surface of the conductive plate 1 and the reinforcing base 3 due to its surface tension. 5 and is brazed without leaving a gap g as shown in FIG. 5, and the entire overlapping surface of the conductive plate 1 and the reinforcing base 3 is brazed as shown in FIG. A contact 6 is obtained.

It is explanatory drawing of the brazing method of the movable contact by the Example of this invention, (a) is sectional drawing showing the furnace assembly state which set each member and brazing material of the movable contact to the tray-like jig | tool, (b) ) Is an external perspective view of the conductive plate, the sheet-like brazing material, and the reinforcing base metal as viewed from the back side in (a). Side view of a stacked movable contact which is an object of the present invention It is explanatory drawing of the conventional manufacturing method of the movable contact shown in FIG. 2, and the figure showing the furnace assembly procedure at the time of setting each member and brazing material of a movable contact to a tray-shaped jig | tool. FIG. 3 is an external perspective view of the conductive plate, the sheet-like brazing material, and the reinforcing base metal as seen from the back side. Enlarged cross-sectional view of a joint failure location generated on a movable contact by a conventional manufacturing method

Explanation of symbols

1 Conductive plate 1a Dowel hole 2 Contact 3 Reinforcement base 3a Dowel 4 Sheet-shaped brazing material 4a Dowel insertion hole

Claims (2)

A method of manufacturing a movable contactor of an electromagnetic contactor in which a steel reinforcing base plate is overlapped and brazed on the back of a copper strip-shaped conductive plate provided with a pair of contacts at both ends,
The dowels for positioning are formed in advance on the plate surface of the reinforcing base metal, and dowel holes for fitting the dowels are formed in the conductive plate, and the thickness of the brazing material is thinner than the height of the dowel and the outer shape of the conductive plate. Prepare a sheet-like brazing material that has been cut into a corresponding size and formed a dowel-insertion hole at a predetermined position. In the brazing process, the reinforcing base metal is placed in a fixed position with the sheet-like brazing material sandwiched on the conductive plate. A method for manufacturing a movable contact, characterized in that it is superposed and brazed in a furnace. 2. The method of manufacturing a movable contact according to claim 1, wherein trapezoidal dowels are formed at two locations on the plate surface along the longitudinal direction of the reinforcing base metal.

Images