JP2001266692A - Electric contact shape and caulking mold punch and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve efficient caulking by completely preventing generation of caulking breakage (processing crack) such as a crack, etc., at the time of caulking of a spring material (a base material) of an electric contact. SOLUTION: An upstand part 21 is provided on a lower part of a contact head part 1, and a construction part 8 is formed on the top of an upper contact, so that transition of a work strain curve at the time of caulking is smooth without generating an acute angle part and that a phenomenon of caulking breakage (processing crack) such as generation of a crack, etc., is prevented. Specifically, by completely preventing generation of caulking breakage (processing crack) such as a crack, etc., at the time of caulking of the spring material (the base material) of the electric contact, manufacturing yield is improved and reduction of costs can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The disclosed technology belongs to the technical field of electrical contacts used for relays, switches, breakers and the like.

[0002]

2. Description of the Related Art As is well known, recently, there are many electric appliances, and they are widely used not only in civil society but also in industrial society. Therefore, naturally, relays, switches and breakers are also widely used. Numerous technologies relating to the relays, switches, and breakers have been developed and studied. For example, Japanese Patent Application Laid-Open Nos.
Japanese Patent Application Laid-Open Nos. 8512 and 3-8226 disclose inventions.

[0003] As shown in Fig. 1, a conventional general contact has a trapezoidal cross section of a contact head 1 so that the contact head 1 has a trapezoidal shape when it is used for making electrical contacts used for relays, switches, breakers, and the like. Regarding caulking breakage (working crack) that occurs when processing by caulking in the mounting hole of the spring material (base material), even if it has minute cracks that are acceptable for electrical contacts, The degree of cracking is increased, and in severe cases, it may reach up to about two-thirds of the contact head. In extreme cases, the crimped electrical contacts may fall off.

The tendency is remarkable in silver tin oxide based materials which are difficult to process.

[0005]

However, most of the prior arts of the prior art relate to a method and a technique for manufacturing a rivet type electric contact, and a technique relating to the shape and performance of a new contact itself is disclosed. Although the function that originally affects the performance of the electrical contact is mostly derived from the shape of the electrical contact,
Only the material and the method of caulking were disclosed from its manufacture.

For example, in the invention disclosed in Japanese Patent Application Laid-Open No. 50-156677, there is a description that cracking is caused by cracking (work cracking) at the time of crimping an electric contact. However, the purpose of the invention is a manufacturing method, which is described below. As a result, the manufacturing process has a disadvantage that it is complicated.

[0007] In addition, the manufacturing efficiency is low, and the cost is increased.

Japanese Unexamined Patent Application Publication No. 60-68512 relates to a fixing method for preventing caulking breakage (work cracking) of a crack which occurs at the time of manufacturing an electrical contact. A constricted portion is formed, and there is a stepped portion at a right angle or near a right angle at a peripheral portion thereof, and since the stepped portion is close to a right-angled shape, there is a problem that the caulking damage (work cracking) cannot be completely prevented.

Japanese Patent Application Laid-Open No. Hei 3-8226 discloses a technique in which a clad rivet contact is provided at a narrowed portion, and the clad rivet portion is relatively weak during crimping work, and crimping breakage (work cracking). There was also a disadvantage that it could result in

As described above, in the method of manufacturing an electric contact according to the prior art, caulking breakage (work cracking), that is, the occurrence of cracks becomes large or small, and the crack portion is minute enough to be allowed for the electric contact. Even if
At the time of caulking, the degree of cracking increases, and in extreme cases, there is a problem that is remarkable in silver tin oxide based materials which are difficult to process.

When the rivet-type electric contact is crimped, the shape of the forming punch used for the caulking is to prevent the electric contact from sticking to each part of the contact at the time of caulking. The punch shape must be slightly larger than the outer diameter of the head.In practice, however, in this case, when crimping is performed, the contact head comes into contact with the forming punch to be caulked, and the plastic deformation pressure is applied to the entire contact. Becomes large and deforms, and a stage of tightly bonding to the spring material (base material) is obtained.
As shown in FIG. 2, the contact head 1 receives the pressure of the upper forming punch 3 and the lower forming punch 6 at the caulking portion almost at the same time, and is tightly bonded to the spring material (base material) 4. When the pressure applied to the contact head 1 at that time reaches a large internal pressure toward the periphery of the contact head, which is the area where the contact can be easily escaped, the opening phenomenon occurs when the contact material cannot withstand the internal pressure for caulking. There was a drawback that would lead to large cracks.

In particular, in the case of a material made of a silver oxide material having a weak bonding force with an additive element, this was remarkable.

[0013]

SUMMARY OF THE INVENTION An object of the invention of this application is to solve the above-mentioned problems of the electric contacts based on the prior art.
A rising portion is provided at the periphery of the electric contact head, and has a peripheral edge taper angle several times the normal taper angle, and
A shape with a squeezed portion on the upper side of the contact head prevents processing cracks during the production of electrical contacts, and also prevents crimping damage (processing cracking) that occurs during caulking, benefiting the use of contact structure technology in the electrical industry. It is an object of the present invention to provide an excellent electric contact shape, a swaged punch shape, and a method of manufacturing the same.

[0014]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the contact head and the contact foot are formed integrally with each other. In a rivet-type electric contact shape, a first base is to form a narrowed portion having a tapered portion including 0 degree on the peripheral portion at the top of the contact head and to have a tapered portion from the terminal end of the contact peripheral rising portion. A contact portion having a tapered portion including 0 degree at the top of the rivet-shaped electric contact shape in which the contact head and the contact foot are integrally formed, and a contact peripheral edge rising portion; A rivet forming punch having a rivet type electrical contact shape characterized by having a tapered portion from the end and a caulking punch having a shape substantially the same as that of the rivet forming punch are used as a second main body, and are in contact with the contact head. In the method for manufacturing a rivet-type electrical contact forming a foot portion, a rising portion having a tapered portion is formed from the peripheral portion of the contact so that a processing strain curve smoothly transitions from the peripheral portion to the peripheral portion. It is a technical measure that takes the third core as its main purpose.

[0015]

In the above configuration, in the electrical contacts used for the relay, the switch and the breaker, a rivet-type electrical contact is formed by a spring material (base material) using an upper forming punch and a lower forming punch.
When caulking the hole provided in the contact hole, the rising portion of the outer edge of the contact head is formed through a predetermined rising taper portion so that cracking stress does not propagate, and further, a narrowed portion is formed at the top of the contact. A rivet contact that has a tapered portion of a predetermined throttle portion formed at the peripheral portion of the throttle portion to increase the density, exhibits a damping effect by the above throttle portion, prevents cracks from spreading, exhibits an assembling effect, and has no throttle portion. Cracking can be suppressed even when caulking is performed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a description of embodiments of the present invention as embodiments of the present invention, with reference to the accompanying drawings.

FIGS. 12 and 13 are cross-sectional photographs of processing strain curves received by the rivet-type electrical contacts instead of ordinary drawings, and FIG. 14 is a secondary electron beam image (SE) after the crushing test.
It is a photograph figure of (M image).

First, a contact head 1 and a contact foot 5 for relays, switches, breakers and the like, which are the core of the invention of this application.
Is formed integrally, and in the manufacture of a normal rivet type contact 1 as shown in FIG. 3, since the processing is started from the boundary between the contact head 1 and the foot 5, the processing strain curve is 3 is formed at an acute angle toward the peripheral portion 2 of the contact head (the actual processing strain curve in the cross section of the contact appears as shown in Photo 1 of FIG. 12). During the further processing such as caulking, the processing strain is concentrated and a crack occurs in the peripheral portion 2 of the contact head. However, the shape of the electric contact according to the invention of this application is as follows. As a result, as shown in Photo 2 of FIG. 13, the sharp angle of the processing strain curve 7 can be eliminated and the transition can be made smooth, and the sharp edge concentration at the peripheral portion 2 of the contact head can be eliminated, thereby causing the processing strain. No further processing during rivet type contact manufacturing In this case, it is also possible to prevent the occurrence of processing cracks and caulking breakage (working cracks) in advance, and by providing the narrowed portion 8 at the top of the contact head, the contact head peripheral edge 2 can be formed at the time of manufacturing the contact. It was confirmed that no crack was propagated even when the contact having the generated minute crack was swaged.

It has been found that the formation of the constricted portion 8 is involved in the propagation of caulking breakage (work cracking) and has an effect of preventing the crack from expanding.

It is desirable that the drawing portion 8 and the drawing height 24 be 8% to 30% of the contact top thickness. That is, if it is 8% or less, according to an experiment, the forming process is controlled during forming by a forming punch. This is because it was found that it was difficult to perform, and that it was shaved in the subsequent polishing step with no effect.

The angle 23 of the aperture 8 is
According to experiments, it is preferable that the angle is about 0 to 10 degrees,
If it is 0 degrees or more, the material density cannot be sufficiently increased, and crack propagation during caulking cannot be prevented.

As for the angle 20 of the rising dimension 21 of the rivet contact head peripheral portion 2, the taper angle is 0.
According to experiments, it is most appropriate to set it to 5 degrees or less, which means that if it is 5 degrees or more, processing strain during header processing tends to concentrate on the peripheral edge portion 2 of the contact point contact head, and the effect is lost. Because I understood.

It has been found through experiments that it is most preferable that the thickness of the rising portion 21 of the contact head 1 be 15% to 60% of the thickness of the contact head 1.
If it is less than 5%, the rising dimension 21 is too small, and when the relay, switch, breaker, or the like is in operation, there is a turn-up phenomenon. If it is more than 60%, it is impossible to prevent cracking of the contact head peripheral portion 2. This is because the.

Further, it has been experimentally found that the tapered portion angle 22 from the end of the rising portion 21 is set to reduce the amount of deformation during caulking and to prevent cracking at that time. 3 for the taper angle 22
0 ° to 60 ° is the most preferable. That is, if the angle is 30 ° or less, there is no effect. If the angle is 60 ° or more, the effective smooth surface dimension 19 of the contact head 1 becomes extremely small. Because it was found to hinder their movement.

As shown in the following photograph 1 (FIG. 12), the working strain curve at the actual contact cross section tends to become an acute angle, and the contact head where working strain concentrates during further working in caulking. In some cases, cracks occurred in the peripheral portion 2.

On the other hand, in the shape of the electric contact according to the invention of this application, as shown in photograph 2 of FIG. 2, without causing a processing strain curve concentrated at an acute angle, it is possible to prevent the occurrence of processing cracks at the time of rivet contact manufacturing and at the time of further processing.
In addition, it was confirmed that the provision of the squeezed portion 8 on the top of the contact head 1 did not cause the propagation of cracks even when the electrical contact having a small crack was formed on the peripheral portion 2 of the contact head.

As described above, the rivet contact shape of the invention of this application has a rising portion at the periphery of the contact head, so that the processing strain stress at the time of manufacturing the rivet contact can be processed without concentrating on the periphery of the contact head. It can be seen that, by making the taper portion angle larger than the normal setting angle, the taper has a role of a buffer zone that receives the processing pressure received during caulking without concentrating on the peripheral portion of the contact head.

The narrowed portion at the top of the contact head has the intelligence to reduce the propagating properties of the crack when a contact having a fine crack that can be tolerated at the periphery of the contact head is processed by caulking. Further, the same effect can be obtained by forming the caulking punch with substantially the same shape as the electric contact.

An experimental example according to the above embodiment will be described.
A wire rod of 87% Ag-13% SnO _{2 having} a diameter of 1.5 mm was cut into a chip shape having a length of 1.61 mm by a header machine, and processed into a preformed shape shown in FIG. 7 by ordinary header processing. In order to make the shape of the electrical contact of the invention of the present application, a drawing portion is formed by using a knockout pin 14 of an upper forming punch 12 and a lower fixed punch 13 which form the center of one aspect of the present invention shown in FIG. Height 24 is 0.05
mm, the taper angle 23 is 0 degree, the taper angle 22 is 40 degrees, the height 21 of the rising portion is 0.15 mm,
The rising part angle 20 is 0 degree and the thickness of the contact head 1 is 0.3
5 mm, the outer diameter of the contact was 2.5 mm, the diameter of the contact foot 5 was 1.6 mm, and the length of the contact foot 5 was 0.8 mm to obtain the shape of the electric contact of the invention of this application. .

As a comparative example, the same material as the conventional example was used.
The punch 15 of the present invention shown in FIG.
The contact head thickness is 0.35 mm, the contact outer diameter is 2.5 mm, the contact foot diameter is 1.6 mm, the length is 0.8 mm and the taper angle is 5 degrees using the fixed punch 13 and the knockout pin 14. Table 1 below shows the results of comparison of the crack condition of the contact head 1 and the peripheral portion 2 and the crack condition of the crushing test at the time of manufacturing the contacts of the double rivet type electrical contacts obtained in the conventional manner. , (Each machining number 20
0) and Table 2 (50 processed pieces).

[Table 1]

[Table 2]

The crushing test is a test method devised so that actual caulking can be easily tested.
As shown in FIG. 10, the drop block 17 on which the flattening punch 16 is mounted is swaged to damage the test rivet contact 18 placed on the punch 10 or 11 when the contact 18 is crushed with an impact force of 1.2 N. This is a test method for observing (mainly the periphery of the contact head is received, and the processing crack condition at that time is as shown in FIG. 14).

At this time, the punches 11 and 10 are used for
This is because the shape of the crimping punch actually used and the shape of the contact processing portion are substantially the same.

As is clear from Table 1 and Table 2 above, when the header is processed with the shape of the invention of the present application, it is 100% that there is no crack at all due to cracking of the peripheral portion of the contact head. In contrast, in the conventional example, the stereoscopic microscope 2
The length that can be recognized by magnifying with a 0x magnification lens is 0.1m
The rate of occurrence of fine cracks of about m to 0.2 mm is 76%, the cracks that can be visually confirmed is 24%, and the crimping punch 10 having the shape of the invention of this application by a crushing test.
The probability of not cracking at all when using is 100%, while the conventional example has a caulking punch 1 having the invention of this application.
The data when 0 is used is a reference value because the contact volume is larger than the forming punch volume. However, in the normal case, although it is easy to cause processing cracks, the degree of fine cracking is reduced. It can be seen that the ratio is increasing.

When a conventional punch 11 having a conventional shape is used, fine cracks are 6%, and cracks with large cracks are 94%, indicating the same tendency as the result of header processing.

[0035]

As described above, according to the invention of this application, it is possible to completely eliminate caulking breakage (work cracking) at the time of caulking a spring material (base material), and the caulking of electrical contacts is performed as designed. An excellent effect of being able to perform efficiently is exhibited.

Therefore, even during actual operation, the electrical contacts do not fall off due to the cracks, and an excellent effect that the performance of the relays, switches, breakers, and the like can be exhibited as set is exhibited.

Further, if the caulking forming punch of the present invention is used, caulking distortion flowing to each part of the contact at the time of caulking can be minimized, caulking breakage (work cracking) can be prevented, and contact damage can be prevented. There is an effect that it can be prevented, and an excellent effect that the caulking state can be performed as designed.

That is, in the normal caulking process, when the contact head comes into contact with the forming punch, the entire contact is plastically deformed, and the step of closely contacting the spring material (base material) is taken, as shown in FIG. As shown in the figure, the pressures of the upper and lower forming punches are received almost simultaneously and are tightly connected to the spring material (base material). Although this caused run-out and caulking breakage (work cracking), the use of the caulking forming punch of the invention of this application has the effect of preventing cracking.

Further, according to the manufacturing method of this application, by forming a rising portion having a tapered portion from the peripheral edge of the contact, the processing strain curve is smoothly continuous from the peripheral portion of the head toward the peripheral edge. Since the processing pressure of the header does not concentrate on the peripheral edge of the contact, there is an effect that cracking does not occur during the processing of the header.

[Brief description of the drawings]

FIG. 1 is an external side view of a rivet-type electrical contact in a normal operating state.

FIG. 2 is a side view of a conventional mode showing a state during swaging.

FIG. 3 is a cross-sectional view of a contact showing a processing strain curve received during production of a rivet-type electric contact.

FIG. 4 is a sectional view showing an electric contact of the invention of this application.

FIG. 5 is a side sectional view of a forming punch for swaging.

FIG. 6 is a side sectional view of a forming punch for caulking based on the prior art.

FIG. 7 is an external side view of the shape of the rivet-type electric contact at the time of preforming of the peripheral portion header processing.

FIG. 8 is a side sectional view at the time of forming according to the invention of this application.

FIG. 9 is a side sectional view of the rivet type electric contact of the invention of this application.

FIG. 10 is an external side view of a crushing test.

FIG. 11 is an external side sectional view of an electric contact according to the invention of this application.

FIG. 12 is a cross-sectional view of a rivet contact showing a processing distortion processing curve received at the time of manufacturing a rivet contact based on the prior art, and is a 1/4 size photograph instead of a drawing.

FIG. 13 is a cross-sectional view of the electric contact of the present invention;
It is a 1/4 size photograph instead of a drawing.

FIG. 14 is a photograph of a secondary electron beam image of the electric contact of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Contact head 5 Contact foot 14 Narrow part 23 Taper part

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[Procedure amendment]

[Submission date] March 21, 2000 (200.3.2
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3 is a contact cross-sectional view showing a processing strain curve received during manufacture of a rivet-type electric contact.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Fig. 9

[Correction method] Change

[Correction contents]

FIG. 9 is a side sectional view at the time of a conventional forming process. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission Date] May 12, 2000 (2000.5.1)
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

For example, in the invention disclosed in Japanese Patent Application Laid-Open No. 50-156677, there is a description that cracking is caused by cracking (work cracking) at the time of crimping of an electric contact. As described above, the manufacturing process has a disadvantage that it is complicated.

Claims (3)

[Claims] In a rivet-type electric contact shape in which a contact head and a contact foot are integrally formed, a narrowed portion having a tapered portion including 0 degree on a peripheral portion is formed at the top of the contact head. A rivet-type electric contact shape having a tapered portion from the narrowed portion to a rising edge portion of the contact head. 2. A rivet-shaped electrical contact having a contact head and a contact foot formed integrally with each other, and a narrowed portion having a tapered portion including 0 degree on a peripheral portion is formed at the top of the contact head. A rivet-type electric contact-shaped forming punch having a tapered portion from the drawn portion to a contact head peripheral edge rising portion, wherein the formed contact portion of the electric contact and the drawn portion formed shape portion And a rivet-type electric contact forming punch characterized by being formed continuously, and a caulking formed punch having substantially the same shape as the contact shape. 3. A method of manufacturing a rivet-type electrical contact for forming a contact head and a contact foot, wherein a rising portion having a tapered portion is formed from the peripheral edge of the contact, and a processing strain curve is smooth from the peripheral edge to the peripheral edge. A method of manufacturing an electrical contact, characterized in that the electrical contact is formed so as to have a shape that transitions to.