JPH01309221A - Manufacture of contact spring - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method of manufacturing a contact spring constituting a switching section of an electromagnetic contactor, an electromagnetic relay, etc., and particularly relates to a means for restoring the strength of a leaf spring that has been softened by welding the contacts.

[Conventional technology]

One of the components of switching devices such as electromagnetic contactors and electromagnetic relays is a contact spring in which a contact is bonded to one or both ends of a leaf spring serving as a contact base metal. As a method for joining contacts, there is a resistance welding method called spot welding or projection welding. As shown in Fig. 5, the contact 1 and the leaf spring 2 are sandwiched between a pair of upper and lower electrodes 3a and 3b, and electricity is applied while applying pressure in the direction of arrow P, thereby generating heat at the interface between the contact 1 and the leaf spring 2. This is a method of bonding the two using this heat.

[Question B that the invention attempts to solve]

Although this method is metallurgical joining and can provide highly reliable joining, there is a problem in that the leaf spring softens near the welded part due to the heat generation. When such a leaf spring is incorporated into the opening/closing device to perform opening/closing operations, the leaf spring may break at the softened portion due to fatigue. Since contact springs serve as conductive paths in electromagnetic contactors and electromagnetic relays, copper alloys such as phosphor bronze are often used. The alloy is used in a highly rolled condition. As is well known, the strength of materials given strength by rolling increases as the degree of rolling increases.
On the other hand, it also becomes easier to soften due to heat. Therefore, softening of the contact spring due to welding is a major problem. A conventional method to deal with this problem is to increase the thickness of the leaf spring to reduce the stress generated in the leaf spring during opening and closing operations. However, this method has the problem of being disadvantageous in terms of material cost. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a contact spring that solves the above problem by restoring the strength of a temporary spring that has been softened by welding the contacts.

[Means to solve the problem]

To achieve the above object, the present invention provides a contact spring in which a contact is joined to a leaf spring by resistance welding, and after the contact is welded to the leaf spring, the contact and the leaf spring are compressed together.

[Function 1] After the resistance welding step, a step is provided to press the contact and the leaf spring together, thereby plastically deforming the temporary spring and work-hardening the softened portion. [Example] The present invention will be described in detail below based on FIGS. 1 to 4. Copper-zinc-tin alloy temporary spring 2 (thickness 0.5 mm x width 5.
Resistance weld a silver-nickel contact 1 (diameter 2.5 mm x thickness 3.2 mm) to the 0 mm x length 27.0 mm) using the method shown in Figure 5, and then connect the contact 1 and leaf spring 2 as shown in Figure 1. were sandwiched together between a pair of compression jigs 4a and 4b, and compressed by applying a load of about 800 kg in the direction of arrow Q. As shown in FIG. 3, the degree of plastic deformation of the leaf spring 2 was such that the width of the compressed portion 2a slightly increased by about 0.15 mm, and no substantial change was observed in the plate pressure. On the other hand, as shown in FIG. 4, the hardness of the compression-processed leaf spring 2 was significantly improved to about 170 on the indicated hardness measurement line, with the conventional product without compression being 100. When an opening/closing test was conducted using this leaf spring 2, the conventional product broke after about 2 million cycles, whereas the example did not crack until about 10 million cycles. In the above embodiment, a compressive load of 800 kg was described, but since this load changes depending on the dimensions or materials of the contacts and temporary springs, it is necessary to determine it experimentally depending on the combination of these. FIG. 4 shows another embodiment of a jig on the leaf spring side used for compression processing, and this jig 5 is provided with a groove 50 in the center that matches the width of the leaf spring 2. As per leaf spring 2
It is designed to accommodate. By using such a jig 5, it is possible to limit the expansion of the leaf spring 2 in the width direction. [Effect of the invention 1] This invention is a simple method in which the contact and the leaf spring are compressed together after contact welding, and plastic deformation is applied to the leaf spring to restore the strength of the leaf spring that has been softened by welding. By adding additional processes, the opening and closing life of contact springs can be greatly improved without increasing the plate thickness of the leaf spring.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of compression processing showing an embodiment of the present invention, Fig. 2 is a plan view showing the contact spring after compression processing according to Fig. 1, and Fig. 3 is a recovery of the strength of the contact spring shown in Fig. 2. A line diagram showing the situation, FIG. 4 is a perspective view showing another embodiment of the compression processing jig,
FIG. 5 is an explanatory diagram showing resistance welding of a contact point to a leaf spring. 1: Contact, 2: Leaf spring, 4a, 4b: Compression processing jig. Figure 3 Figure 4 ■ Figure 5

Claims (1)

[Claims] 1) A method for manufacturing a contact spring in which a contact is joined to a leaf spring by resistance welding, the contact spring being welded to the leaf spring and then compressed together with the contact and the leaf spring.