Rivet contact, electrical contact, and method for manufacturing electrical contact

Abstract

The present invention relates to an electrical contact formed from an electrical contact member comprising a rivet contact and a terminal member, the rivet contact comprising: a head part provided with a contact material on at least a portion of the surface thereof; and a leg part which supports the head part and is inserted into the terminal member, the terminal member having an insertion hole into which the leg part of the rivet contact is inserted and which fixes the rivet contact. Furthermore, in the rivet contact, a flange part is formed between the head part and the leg part, the flange part becomes a riveting allowance and is wider than the leg part, and a counter bore is formed in the terminal member, and the flange part is embedded in the counter bore. The electrical contact of the present invention is manufactured in a state of good adhesion by caulking the flange portion of the rivet contact to the counter bore of the terminal member.

Description

Technical Field

[0001] The present invention relates to a rivet contact having a rivet shape and a combination with a terminal member suitably applied to the rivet contact and an electrical contact composed of the rivet contact, and more particularly to an electrical contact having good adhesion between the rivet contact and the terminal member, excellent heat dissipation and capable of ensuring stable operation and a manufacturing method thereof. Background Art

[0002] In the past, rivet contacts in the shape of rivets were used as electrical contacts (fixed contacts and movable contacts) mounted on relays, switches, etc. The rivet contacts are composed of a head that functions as an electrical contact and a leg that supports the head and is fixed to a terminal member. In addition to the structure (solid contact) in which the head and leg are composed of a contact material such as an Ag alloy, in recent years, in order to reduce material costs, a structure (tension contact) in which the contact material is applied to a portion of the head or the surface, and the other parts are applied with a Cu-based material (base material) (Patent Documents 1, 2) has been widely used.

[0003] When the rivet contact is fixed to the terminal member to form the electrical contact, after the leg of the rivet contact is inserted into the insertion hole pre-drilled in the terminal member, the leg protruding to the back side is compressed (riveted). Through this compression process, the leg inserted into the hole is enlarged and closely contacts the wall surface of the insertion hole, and the end of the leg becomes larger in diameter than the insertion hole. Fig.21 .

[0004] However, in the electrical contacts of relays, etc., there is a concern in the past that malfunctions are caused by heat generated during driving. The electrical conductivity of the contact material and base material that constitute the contact member is relatively high, but even so, it has the properties of a resistor and cannot completely suppress the heat generated when power is turned on. The amount of heat generated in the electrical contact is proportional to the contact resistance value of the contact material and the square of the current. Therefore, in high-capacity relays that open and close high currents, the increase in heat becomes a problem. If the heat generation becomes excessively large, there is a possibility that the contact material will deform or deteriorate, and in the worst case, it will become the main cause of fire, burning, etc.

[0005] Furthermore, as one of the measures to deal with the problem of heat generation in the electrical contact using the rivet contact, there is the improvement of heat dissipation by improving the adhesion between the rivet contact and the terminal member.

[0006] Fig.23 This is a cross-sectional photograph of an electrical contact in which a conventional rivet contact is fixed to a terminal member. Fig.21 Similarly, a riveting process is performed to compress the lower end of the leg of the rivet contact. Fig.23It is known that in this electrical contact, there is a gap between the bottom surface of the head of the contact member and the surface of the terminal member. Such a gap observed in the previous electrical contacts has become the main reason for hindering the heat generated in the head to the terminal member. In particular, in electrical contacts with high heat generation, an oxide film is generated in the gap between the head and the terminal member, which becomes high temperature, and the heat transfer is hindered. When the heat transfer to the terminal member is hindered, the heat dissipation of the contact member through the terminal member is reduced and it is difficult to suppress the temperature rise. Therefore, it is predicted that by eliminating the gap between the rivet contact, especially the head and the terminal member, the close contact is improved, thereby improving the heat dissipation and suppressing the heat generation.

[0007] As an electrical contact for improving the close contact between the rivet contact and the terminal member, there is an electrical contact described in Patent Document 3. In the electrical contact based on this prior art, a countersunk hole is formed at the position of the head of the rivet contact that fixes the terminal member. Then, the leg is riveted with the head of the rivet contact embedded in the countersunk hole. Fig. 22 As shown in FIG. 1 , the periphery of the countersunk hole of the terminal member is subjected to compression processing. By the compression processing around the countersunk hole, the adhesion between the rivet contact and the terminal member is improved.

[0008] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Laid-Open No. 5-282957 Patent Document 2: Japanese Utility Model Registration No. 3098834 Patent Document 3: Japanese Patent Application Publication No. 2007-122931 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, according to the research of the inventors, in the above-mentioned electrical contact, the close contact between the rivet contact and the terminal member is not necessarily sufficient. In the case where the peripheral portion of the rivet contact head on the surface of the terminal member is processed, it can be said that the close contact with respect to the processed portion is improved. However, it can be said that this is because it is difficult to eliminate the gap between the bottom surface and the side surface of the contact head and the inner surface of the countersunk hole in this processing form.

[0011] In addition, the manufacturing process of the electrical contact of the above-mentioned Patent Document 3 requires a processing step of the peripheral portion of the rivet contact head on the surface of the terminal member in addition to the riveting process of the leg of the rivet contact. The riveting process of the former leg is a process that has been performed in the past. In the manufacturing process of the electrical contact of Patent Document 3, a further processing step is required in the existing process. Such additional processing steps affect the manufacturing efficiency of the electrical contact.

[0012] As described above, the current situation is that no adequate countermeasures have been taken to solve the problem of improving the close contact of the electrical contact using the rivet contact. Therefore, the present invention provides an electrical contact using the rivet contact, in which the close contact between the rivet contact and the terminal member is improved compared with the past, and a rivet contact used to constitute the electrical contact, and the structure of the terminal member suitable for the rivet contact is clarified. In addition, the present invention provides an electrical contact based on the combination of the electrical contact members and a manufacturing method thereof.

[0013] Technical solutions to solve problems

[0014] As described above, in the conventional electrical contacts based on rivet contacts, the close contact between the head of the rivet contact and the terminal member is insufficient. The inventors of the present invention have studied a countermeasure based on the stress propagated from the foot to the head when the foot for fixing the rivet contact is subjected to compression processing (riveting processing). Furthermore, by modifying the structures of the rivet contact and the terminal member, the inventors have come up with the use of a rivet contact having a portion that is plastically processed in a manner of close contact with the terminal member by the stress of the foot processing and a terminal member corresponding to the rivet contact.

[0015] That is, the invention of this application for solving the above-mentioned problem is a rivet contact, comprising: a head, which has a contact material on at least a portion of the upper surface; and a foot, which supports the head and is inserted into the terminal member, characterized in that a flange portion is formed between the head and the foot, and the flange portion serves as a rivet allowance and is wider than the foot.

[0016] In the above-mentioned rivet contact, preferably, a ratio of a width W of the flange portion to a diameter D of the leg portion is 1.1 or more and 4 or less.

[0017] In addition, the present invention relates to a combination of an electrical contact component, which is composed of a rivet contact and a terminal component, wherein the rivet contact comprises: a head, which has a contact material on at least a portion of its surface; and a foot, which supports the head and is inserted into the terminal component, the terminal component having an insertion hole and fixing the rivet contact, the insertion hole being used for inserting the foot of the rivet contact, and is characterized in that in the rivet contact, a flange portion is formed between the head and the foot, the flange portion serves as a riveting allowance and is wider than the foot, and a countersunk hole is formed in the terminal component, the countersunk hole being used for embedding the flange portion.

[0018] In this case, the ratio of the width W of the flange portion of the rivet contact to the diameter D of the leg portion is preferably 1.1 to 4. Furthermore, the ratio of the height h of the flange portion of the rivet contact to the depth H of the counterbore of the terminal member is preferably 0.5 to 5.

[0019] Furthermore, the present invention provides an electrical contact using the above-mentioned rivet contact. The electrical contact is composed of a rivet contact and a terminal member, wherein the rivet contact comprises: a head, which has a contact material on at least a portion of the upper surface; and a foot, which supports the head and is inserted into the terminal member, wherein the terminal member has an insertion hole and fixes the rivet contact, wherein the insertion hole is used for inserting the foot of the rivet contact, and the rivet contact is fixed to the terminal member by riveting the lower end of the foot after inserting the foot into the insertion hole, and wherein the rivet contact is formed with a flange portion between the head and the foot portion, the flange portion being a riveting margin and being wider than the foot portion, and the terminal member is formed with a countersunk hole, wherein the countersunk hole is used for inserting the flange portion, and the flange portion is inserted into the countersunk hole and riveted.

[0020] The rivet contact of the electrical contact of the present invention has excellent adhesion to the terminal member. Specifically, the contact area ratio in any region of the joint interface between the side and bottom surfaces of the flange portion of the rivet contact and the side and bottom surfaces of the counterbore is preferably 50% or more.

[0021] Furthermore, the present invention relates to a method for manufacturing an electrical contact using the combination of the electrical contact members described above. That is, a method for manufacturing an electrical contact using the combination of the electrical contact members described above, wherein the method for manufacturing an electrical contact comprises the following steps: inserting a rivet contact into a terminal member; and performing plastic working on the lower end portion and flange portion of the leg portion of the rivet contact to fix the rivet contact to the terminal member.

[0022] In the above method, in the process of plastic processing the lower end portion and flange portion of the foot of the rivet contact, the lower end portion of the foot of the rivet contact is compressed while restricting the upper surface of the head and flange portion of the rivet contact, thereby riveting the foot and riveting the flange portion to the countersunk hole of the terminal member.

[0023] Furthermore, in the step of plastically working the lower end portion and the flange portion of the leg portion of the rivet contact, it is preferable that the working rate of the leg portion be set to 10% or more.

[0024] In addition, in the manufacturing method of the electrical contact involved in the present invention, the close contact between the rivet contact and the terminal member can be ensured by a single process such as the compression process of the leg, but subsequent processing can also be performed. That is, the present invention can include a process of compressing at least the upper surface of the flange portion of the rivet contact after the process of fixing the rivet contact to the terminal member.

[0025] Effects of the Invention

[0026] The rivet contact according to the present invention includes a flange portion serving as a caulking margin, and the flange portion is caulked to the counterbore of the terminal member to improve the close contact property. Thus, an electrical contact with good heat dissipation can be formed.

[0027] In addition, the caulking process of the flange of the rivet contact according to the present invention can be performed simultaneously with the caulking process of the leg of the rivet contact performed in the same manner as before. Since the rivet contact and the terminal member can be brought into close contact in this single process, the present invention can contribute to improving the manufacturing efficiency of the electrical contact. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The drawings are for explaining the structures of the rivet contact and the terminal member according to the present invention. Figure 2 The diagrams are for explaining the manufacturing process of the electric contact based on the rivet contact according to the present invention. Figure 3 It is a diagram showing the simulation results of stress distribution in the manufacturing process of the electrical contact according to the present invention. Figure 4 It is a diagram showing the simulation results of stress distribution in the manufacturing process of a conventional electrical contact. Figure 5 This is a diagram showing the simulation results of stress distribution in the manufacturing process of an electrical contact according to the prior art (Patent Document 3). Figure 6 The following are diagrams for explaining the dimensions of each part of the rivet contact and the terminal member according to the present invention. Figure 7 This is a diagram showing an example of simulation results regarding the relationship between the ratio of the flange width to the leg width (W / D) of the rivet contact point and the processing rate. Figure 8 This is a diagram showing an example of simulation results regarding the relationship between the ratio of the flange height of the rivet contact to the countersink depth of the terminal member (h / H) and the processing rate. Fig. 9 This is a photograph of the appearance of the electrical contact manufactured in Example 1. Fig.10 is a cross-sectional photograph of the electrical contact manufactured in Example 1. Fig.11 This is a photograph of the bonding interface when the electrical contact manufactured in Example 1 was heated to a high temperature. Fig.12 This is a photograph of a bonding interface and an oxide layer when a conventional electrical contact as a comparative example is heated at a high temperature. Fig.13 This is a graph showing temperature changes when electricity is supplied to the electrical contacts of Example 1 and the related art. Fig.14 is a cross-sectional photograph of the electrical contact manufactured in Example 2. Fig.15 is a cross-sectional photograph of the electrical contact manufactured in Example 3. Fig.16 This is a cross-sectional photograph of the electrical contact manufactured in Example 3 when it was heated at a high temperature. Fig.17 is a cross-sectional photograph of the electrical contact manufactured in Example 4. Fig.18 is a cross-sectional photograph of the electrical contact manufactured in Example 5. Fig.19 This is a cross-sectional photograph of the electrical contact manufactured in Example 5 when it was heated at a high temperature. Fig. 20 is a cross-sectional photograph of the electrical contact manufactured in Example 6. Fig.21 The following are diagrams for explaining the manufacturing process of conventional rivet contacts and electric contacts. Fig. 22 This is a diagram for explaining further processing steps performed after the riveting process of the rivet contact in the prior art (Patent Document 3). Fig.23 These are photographs showing a cross section of a conventional electrical contact (comparative example) and a gap at a bonding interface. DETAILED DESCRIPTION

[0029] Hereinafter, the details of the present invention will be described together with its embodiments. Figure 1 This is a diagram for explaining one mode of the rivet contact and terminal member involved in the present invention. The rivet contact involved in the present invention is different from the conventional rivet contact, and has a flange portion between the head portion and the foot portion having the contact material, which serves as a riveting margin when fixed to the terminal member. One terminal member has an insertion hole for inserting the foot portion of the rivet contact, and a countersunk hole is formed on the surface of the head side of the rivet contact, as in the conventional case. The countersunk hole of the terminal member can be inserted into the flange portion of the rivet contact.

[0030] Figure 2 It is based on Figure 1 FIG. 1 is a diagram illustrating the manufacturing process of the rivet contact and the electrical contact of the terminal member. Figure 2In the present invention, the rivet contact is temporarily fixed to the terminal member by inserting its foot into the insertion hole of the terminal member and embedding the flange into the countersunk hole. From this state, the end of the foot is compressed by abutting and fixing a clamp such as a rivet grinder in such a way that both the head of the rivet contact and the upper surface of the flange are restricted. The compression process itself can be performed by the same processing method as the riveting process of the conventional rivet contact. The compression process of the end of the foot flattens and deforms the area of ​​the foot protruding from the terminal surface while making it in close contact with the terminal surface, and expands the diameter of the foot in the insertion hole of the terminal member so that it is in close contact with the inner wall. The above deformation / close contact of the end of the foot and the expansion / close contact inside the insertion hole are the same as the riveting process of the conventional rivet contact.

[0031] Moreover, if Figure 2 As shown in , the flange portion of the rivet contact, which is buried in the terminal member through the countersink, is subjected to stress propagation with the end of the foot as a stress source and the resulting plastic flow. In the compression process, the head of the rivet contact and the upper surface of the flange portion are in a restricted state, so plastic flow occurs in the horizontal and vertical directions and the flange portion expands in diameter. As a result, the side surface of the flange portion and the inner wall of the countersink and the bottom surface of the flange portion and the bottom surface of the countersink are in close contact. As described above, in the present invention, in addition to the plastic processing (riveting processing) of the foot of the rivet contact, the plastic processing (riveting processing) of the flange portion is also performed through the compression processing of the foot end, thereby improving the overall close contact of the area where the rivet contact contacts the terminal member.

[0032] In addition, Figure 2 In the figure, regarding the protruding length of the leg of the rivet contact protruding from the back side of the terminal member, when the protruding length before the compression processing is set to L1 and the protruding length after the compression processing is set to L2, the change rate of the leg, i.e. (L1-L2) / L1×100 (%), is called the processing rate in the present invention.

[0033] Here, in order to confirm the close contact between the rivet contact involved in the present invention and the terminal member, the inventors and others conducted stress analysis simulating the processing process for the electrical contact based on the rivet contact of the present invention, the electrical contact based on the previous rivet contact, and the electrical contact of the above-mentioned patent document 3, and confirmed the effect of improving the close contact between the above-mentioned rivet contact and the terminal member. In this stress analysis, the shape / size of the rivet contact and the terminal member are made the same, and the stress distribution after the riveting process is performed by applying the same compressive stress to the end of the foot is analyzed / mapped. In addition, in the analysis of the electrical contact of patent document 3, the compression process around the countersunk hole of the terminal member after the riveting process of the foot is simulated, and stress analysis is performed. The simulation conditions used in these stress analyses are as follows.

[0034] (1) Rivet contacts ・The present invention Head size: diameter 5mm x height 1mm Flange size: diameter 6mm x height 1.1mm Foot size: diameter 4mm x length 3mm ・Prior art and patent literature 3 Head size: diameter 5mm x height 1mm Foot size: diameter 4mm x length 4mm ・As for the constituent materials, the contact material was set to Ag and the base material was set to Cu.

[0035] (2) Terminal components ・Size: 30mm×30mm, thickness 3mm Regarding the present invention, the countersunk hole size is: diameter 6mm×depth 1mm Regarding Patent Document 3, countersunk hole dimensions: 5 mm diameter x 0.2 mm depth ・All constituent materials were made of Cu.

[0036] (3) Compression processing conditions

[0037] The end surface of the leg portion was compressed using a lever pin (carbon steel) until the length (1 mm) of the leg portion protruding from the back surface of the terminal member was halved.

[0038] In Patent Document 3, after the leg portion is processed, compression processing is performed until a 1 mm portion around the countersunk hole of the terminal member is pressed in by 0.1 mm.

[0039] (4) Analysis software ・ANSYS Mechanical (ver.2022R1) made by ANSYS Inc. ・Analysis type: Time history response structural analysis (Mesh creation condition: Program control (default)) ・As material parameters for analysis, the density, Poisson's ratio, Young's modulus, and friction coefficient of the constituent materials of each component were input and analyzed.

[0040] Based on the above conditions, the stress distribution analysis results when the rivet contact according to the present invention is connected to the terminal member are shown in FIG. Figure 3 to Figure 5In these analysis results, the stress required for the close contact between the rivet contact and the terminal member is assumed to be 5000 MPa or more, and the range of the stress of 5000 MPa is shown in dark colors in each figure. In addition, the reference value of 5000 MPa is calculated based on the plastic working amount for making the rivet contact and the terminal member close to each other, assuming that the amount of plastic working is 0.05 mm, and the deformation amount and the Young's modulus of Cu, which is the constituent material of the base material.

[0041] from Figure 3 It can be confirmed that in the embodiment of the electrical contact to which the rivet contact according to the present invention is applied, sufficient stress is generated in the entire flange portion, thereby ensuring close contact with the inner wall of the counterbore of the terminal member. Figure 4 In the electrical contact based on the general rivet contact, insufficient stress is observed on the side and bottom of the head. Figure 5 In the electric contact in which the periphery of the countersunk hole is compressed as in Patent Document 3, the range of the prescribed stress is widened compared with the electric contact based on the general rivet contact, but insufficient stress also occurs at the head of the rivet contact.

[0042] The above simulation results also show that the rivet contact with the flange of the present invention can be highly closely attached to the terminal member while using the flange as a caulking margin. Furthermore, the rivet contact of the present invention can be fixed to the terminal member in the same process as the conventional rivet contact.

[0043] The rivet contacts involved in the present invention can be basically the same as the conventional rivet contacts in terms of their constituent materials, the structure of the head and the foot. The head only needs to have the contact material bonded to a portion of its surface. In addition, when a contact pair (a combination of a movable contact and a fixed contact, etc.) is formed after the rivet contact is joined to the terminal member, it only needs to be possible for the head to be in contact with the relative electrical contact. Moreover, the foot only needs to be in a shape that can be inserted into the insertion hole of the terminal member and formed in a manner that supports the head. In addition, the rivet contacts and electrical contacts involved in the present invention can be applied to both the movable contacts and the fixed contacts of relays, etc., and the present invention is applicable to either or both of the movable contacts and the fixed contacts.

[0044] On the other hand, the flange portion that is a feature of the rivet contact according to the present invention is a portion formed between the head and the foot portion and having a width wider than the foot portion. With regard to the fact that the flange portion is wider than the foot portion, when the width W of the flange portion and the diameter D of the foot portion are set, the ratio W / D of the two is preferably 1.1 or more and 4 or less (see Figure 6). W / D can be set within the above range according to the constituent materials (base materials) of the foot and the flange, the length of the foot, specific numerical dimensions, etc. However, when the value of W / D is too large, that is, when the flange is too wide than the foot, the stress propagation to the flange during processing is insufficient, and sometimes the close contact with the terminal member (countersunk hole) is insufficient. W / D is more preferably not less than 1.1 and not more than 2.5.

[0045] In addition, the side surface of the flange portion can be vertical, but can also be inclined in a conical shape. In this case, the width (W) of the flange portion is set to the width of the bottom surface that contacts the countersunk hole of the terminal member. In addition, regarding the size of the head, since the flange portion is set as a riveting allowance, the width of the head needs to be set smaller than the width of the flange portion, but there is no other size restriction. The width of the head can be the same as the diameter of the foot, or it can be smaller or larger than it. In addition, the length of the foot is set according to the terminal member determined by the specification size of the relay, etc., so there is no special restriction.

[0046] Regarding the constituent materials of the rivet contacts, the contact materials of the head use the contact materials commonly used in relay contacts, etc. As preferred contact materials in relay contacts, etc., Ag-based contact materials are known. As Ag-based contact materials, specifically, pure Ag and Ag alloys (Ag-Ni alloys, Ag-Cu alloys, etc.) can be cited. In addition, for Ag alloys, in addition to solid solution alloys, oxide-dispersed Ag alloys (Ag-SnO2 alloys, Ag-SnO2-In2O3 alloys, Ag-ZnO alloys, etc.) can also be applied. In addition, as the base materials for the head, flange, and foot other than the contact materials, there is no particular limitation as long as they are conductive metals / alloys. As the base material of the rivet contacts, Cu-based materials of Cu and Cu alloys (Cu-Ni alloys, Cu-Sn alloys, etc.) are mostly used. Cu-based materials have good conductivity and good processability, so when the above-mentioned rivet contacts are riveted to the terminal member, a good bonding state can be formed. In addition, it is preferred that the head, flange, and foot are formed in an integrated manner except for the contact material. In addition, the contact material only needs to be bonded to at least a portion of the surface of the head, and there is no particular restriction on its thickness. The type and size of the contact material are determined based on the specifications of the relay equipped with the electrical contact.

[0047] In order to form an electrical contact, the terminal member combined with the rivet contact involved in the present invention has an insertion hole for inserting the rivet contact as in the prior art. Moreover, the terminal member in the present invention is formed with a countersunk hole for the flange portion of the rivet contact to fit. The terminal member may also be formed with two or more insertion holes and countersunk holes.

[0048] The countersunk hole is formed to correspond to the shape / size of the flange portion of the rivet contact. The inner diameter of the countersunk hole can be any diameter as long as it can accommodate the flange portion. Preferably, the ratio (W / D2) of the inner diameter D2 of the countersunk hole to the width W of the flange portion is set to be greater than 1 / 2 and less than 1 / 1 (see Figure 6 ). More preferably, W / D2 is set to be greater than 7 / 10 and less than 1 / 1.

[0049] In addition, regarding the relationship between the depth H of the countersunk hole and the height h of the flange portion of the rivet contact, it is preferable to set h / H to be greater than or equal to 0.5 and less than or equal to 5 (see Figure 6 ). Regarding the range of h / H, it is more preferably set to be greater than 0.8 and less than 2.2. In addition, when h / H exceeds 1, after the rivet contact is joined to the terminal member, a height difference sometimes occurs between the flange portion and the surface of the terminal member, but the presence or absence of the height difference does not cause any particular problem for the function of the electrical contact. In addition, as described later, in the present invention, a processing step of pressurizing / compressing the upper surface of the flange surface can also be additionally performed after the rivet contact is joined, so even if h / H exceeds 1, the height difference can be reduced or eliminated.

[0050] The same materials as those of conventional terminal members are also applicable to the constituent materials of the terminal members. Specifically, Cu-based materials, Fe-based materials, etc. are used. In addition, these metals are sometimes plated (Sn plating, Ni plating, Ag plating, etc.).

[0051] The combination of the electric contact involved in the present invention is constituted by the rivet contact and the terminal member described above. Then, the electric contact is manufactured by the above-mentioned method using the combination of the electric contacts. In the above-mentioned method for manufacturing the electric contact involved in the present invention, the foot of the rivet contact is compressed while restricting the upper surface of the head and the flange of the rivet contact, so that the foot and the flange of the rivet contact are riveted and fixed to the terminal member. The restriction of the upper surface of the head and the flange of the rivet contact is to abut the rivet contact with a fixture such as a riveting grinder having a recessed portion of a shape that fits with the upper surface of the head and the flange of the rivet contact, so as to fix the fixture in a manner that does not move. For the fixture such as the riveting grinder, it is allowed to apply stress for restricting the head of the rivet contact, but it is not necessary to apply stress such as processing the head. In the present invention, it is a method to improve the adhesion between the rivet contact and the terminal member without processing the head, especially the contact material.

[0052] The riveting process of the leg of the rivet contact and the processing of the flange are performed by compressing the end surface of the leg. The compression process is performed by bringing a compression member such as a rod pin into contact with the end surface of the leg of the rivet contact and applying pressure. The surface of the compression member may be flat or may have a recessed portion for suppressing the displacement of the leg of the rivet contact. By using a compression member with a recessed portion, the close contact between the flange and the countersunk hole is sometimes improved.

[0053] The pressure applied for the compression processing of the rivet contact foot can be adjusted by the processing rate (flattening amount) of the foot protruding from the back of the terminal member. The significance of the processing rate has been explained above. In the present invention, the deformation / expansion of the rivet foot and the flange portion occurs simultaneously through the propagation and plastic flow of the compressive stress imparted in this one process. Moreover, in order to deform the flange portion and make it closely contact with the inner wall of the countersunk hole of the terminal member, the compression processing is preferably performed in a manner that the processing rate is 10% or more. The processing rate is more preferably 30% or more, and even more preferably 50% or more. In addition, in the compression processing of the foot, pressure may be applied until the deformed foot end is buried in the terminal member. Therefore, as an upper limit of the processing rate, up to 100% is allowed.

[0054] The point that the deformation capacity of the flange of the rivet contact can be improved by increasing the processing rate of the leg can also be inferred from the simulation results of the rivet contact and terminal member of the above-mentioned specific size / material. The research results on the relationship between the processing rate and the size of the flange and the countersunk hole in the above-mentioned simulation results are shown in Figure 7 , 8 Shown in. Figure 7 : is a diagram showing the setting range of the ratio (W / D) of the width W of the flange portion of the rivet contact point to the diameter D of the leg portion when the processing rate during leg compression is increased. Figure 8 The following are graphs showing the setting range of the ratio of the height h of the flange portion of the rivet contact point to the depth H of the countersunk hole (h / H) when the processing rate during leg compression is increased. As can be seen from these graphs, the setting range of the ratio of the width W of the flange portion to the diameter D of the leg portion (W / D) and the ratio of the height h of the flange portion to the depth H of the countersunk hole (h / H) is expanded by increasing the processing rate of the leg portion during processing.

[0055] In the manufacturing method of the electric contact involved in the present invention, the leg end and the flange of the rivet contact can be riveted to the terminal member through the above-mentioned leg processing step, thereby firmly joining / fixing the rivet contact. After the primary compression processing step, it is not necessary to process the terminal surface as in the prior art (Patent Document 3).

[0056] However, after the rivet contact is fixed to the terminal member, an additional processing step for the flange portion may be added. For example, when the height of the flange portion of the rivet contact is greater than the depth of the countersunk hole of the terminal member (h>H), a height difference is sometimes formed between the flange portion and the terminal member. In order to reduce or eliminate the height difference, at least the upper surface of the flange may be additionally compressed. In addition, by performing additional compression processing, the close contact between the flange portion and the terminal member may sometimes be further improved. In this additional processing step, at least only the upper surface portion of the flange portion is compressed and the flange portion is plastically processed. However, both the upper surface portion of the flange portion and the head portion may be compressed within a range that does not deform the head portion. As a specific method, the flange portion can be processed by pressurizing the rivet contact using a compression member such as a riveting grinder used in the above, or by pressurizing the upper surface of the flange portion using a compression member having a shape corresponding to the upper surface of the flange portion.

[0057] In the electrical contact composed of a rivet contact and a terminal member manufactured by the method described above, the side and bottom surface of the flange portion of the rivet contact are in a state of high close contact with the inner wall and bottom surface of the countersunk hole of the terminal member. This close contact state means that for the bonding interface between the side surface of the flange portion and the side surface (inner wall) of the countersunk hole and the bonding interface between the bottom surface of the flange portion and the bottom surface of the countersunk hole, when observing any area, the close contact area ratio in the observed area is preferably 50% or more, and more preferably 70% or more. The so-called close contact area ratio refers to the ratio of the area of ​​the range where the flange portion and the countersunk hole are in contact with each other without a gap to the area of ​​the entire area where the flange portion and the countersunk hole are in contact. In the present invention, the so-called gap is set to a space with a width of 3μm or more. The close contact area ratio can be obtained by measuring the area ratio of the gap at the bonding interface and calculating "100 (%) - the area ratio of the measured gap". In addition, in the determination of the area ratio of the gap, it is simple to observe any area of ​​the cross section of the electrical contact using a metal microscope or an electron microscope (SEM). Furthermore, the length of the bonding interface and the length of the gap in the observed image are measured, and the ratio of the two can be set as the area ratio of the gap. Observing the bonding interface means that it is preferred to set observation areas for the side surface and the bottom surface of the flange part respectively. In addition, it is preferred to observe multiple parts in each part.

[0058] In addition, the presence or absence of a gap at the joint interface between the rivet contact and the terminal member can also be confirmed by whether an oxide layer is formed at the joint interface by heating the electrical contact at a high temperature. In this case, when the electrical contact is heated at 200°C or more in an air / oxidizing atmosphere, the surface of the terminal member and / or the rivet contact is oxidized in the gap connected to the atmosphere to form an oxide. Such an oxide is easier to observe than the gap itself, so the presence or absence of the gap can be confirmed. The area ratio of the oxide layer measured in the same way as the above-mentioned gap observation method can be used as the area ratio of the gap.

[0059] Example

[0060] Example 1 : A specific embodiment of the rivet contact and the electrical contact involved in the present invention is described. Among the constituent materials of the rivet contact of this embodiment, the contact material is an Ag-based oxide material, and the base material of the foot and the flange is Cu. The rivet contact is manufactured by processing the contact material and the base material into a contact shape by header processing. In addition, the terminal member is made of Cu, and a countersink is formed by cutting the Cu plate, and the center of the countersink is punched to form an insertion hole. The dimensions of each part of the rivet contact and the terminal member are as follows.

[0061] ・Rivet contacts Head size: diameter 5mm x height 1mm Flange size: diameter (width W) 7mm x height (H) 1mm Foot size: diameter (D) 4mm x length 3mm W / D=1.75

[0062] ・Terminal components Overall size: 40mm×16mm, thickness 3mm Counterbore size: diameter 7.1mm x depth (h) 1mm h / H=1.0

[0063] Then, the rivet contact is inserted into the terminal member, and a rivet grinder having a concave portion that can be integrally fitted with the head is covered on the head, and fixed by the rivet grinder to restrict the head of the rivet contact. In this state, the lower end of the leg is pressed by the rod pin to compress the leg. In this embodiment, the compression is performed with the processing rate of the compressed leg set to 90%.

[0064] In addition, here, as a comparative example, an electrical contact based on a rivet contact of a conventional shape was also produced. The contact material and base material used were the same as those in the embodiment. The dimensions of the rivet contact were set as follows, and the rivet contact was produced by the same processing method as in the embodiment.

[0065] ・Rivet contacts Head size: diameter 5mm x height 1mm Foot size: diameter 4mm x length 4mm

[0066] ・Terminal components Overall size: 40mm×16mm, thickness 3mm

[0067] Then, the rivet contact was inserted into the terminal member (without the countersunk hole) and the leg portion was compressed to perform joining in the same manner as in Example 1. The leg portion was compressed in the same manner as in the Example, and the processing rate was set to 90%.

[0068] exist Fig. 9 2 shows a photograph of the appearance of the manufactured electrical contact of Example 1. In addition, the electrical contact was cut along the center line of the head of the rivet contact and the cross section was observed. Fig.10 A cross-sectional photograph and a partial enlargement thereof are shown in FIG.

[0069] As from Fig.10 As confirmed, in the electrical contact of Example 1, there is almost no gap at the joint interface between the flange and the leg, so it can be seen that extremely good adhesion is obtained. In contrast, the cross-sectional photograph of the electrical contact of the comparative example is as described above. Fig.23 . In the electrical contact based on the conventional rivet contact, a linear gap was confirmed at the joint interface at the bottom of the head and the side of the foot of the rivet contact. The gap is about 4 μm in width. In addition, the close contact area ratio of the joint interface between the flange portion and the countersunk hole of the rivet contact in this embodiment is 95%. On the other hand, for the rivet contact of the conventional shape as a comparative example, the close contact area ratio of the joint interface between the bottom surface of the head and the surface of the load-bearing member was measured, and the result was approximately 0%, resulting in a gap of more than 3 μm on substantially the entire surface. Therefore, it can be said that there is a significant difference in adhesion between the present embodiment and the comparative example.

[0070] Furthermore, the electrical contacts of Example 1 and the comparative example were subjected to high temperature heating to confirm the presence or absence of oxide formation at the bonding interface. In this heating test, the electrical contacts were heated at 500°C for 60 minutes (in the air) in a tubular furnace, and then the cross-section was observed in the same manner as above. The results are shown in Fig.11 , 12 As shown in the figure, in the comparative example, the electrical contacts ( Fig.12 ), a black oxide layer is formed near the bonding interface at the bottom of the head of the rivet contact. In contrast, in the electrical contact ( Fig.11), the formation of an oxide layer was not observed at all at the bonding interface. Therefore, the close contact area ratio was estimated based on the area where the oxide layer existed. The close contact area ratio based on the presence of oxide was obtained by measuring the area ratio of the area where the oxide layer at the bonding interface was observed and calculating "100 (%) - the area ratio of the measured oxide layer". The close contact area ratio based on the oxide layer was 93.5%.

[0071] Next, the electrical contacts of the embodiment and comparative example were assembled into a relay, and the heat transfer performance of the electrical contacts when the relay was energized was confirmed. In this energization test, a relay with a double-break structure having two pairs of movable contacts and fixed contacts was prepared, and the electrical contacts of the embodiment and the previous example were connected to the fixed terminal and the movable terminal. Then, each contact was connected and energized at DC100V, 200A. Then, the temperature of the movable terminal was measured as the temperature of the electrical contact, and the temperature was measured from the start of energization to 30 minutes (1800 seconds). This energization test was performed on 3 samples. The evaluation results are shown in Fig.13 Shown in.

[0072] from Fig.13 It can be seen that the temperature rise of the electrical contacts of the embodiment is significantly lower than that of the electrical contacts of the comparative example. Regarding the temperature rise value after 30 minutes of power-on, the embodiment is reduced by 21% on average compared with the comparative example. The rivet contacts of the embodiment are larger in volume than the comparative example due to the presence of the flange part, so it is believed that the heat dissipation is improved by this, but it is believed that the heat transfer effect brought about by the improved adhesion between the rivet contacts and the terminal member helps to suppress the temperature rise of the contacts.

[0073] Example 2 In this embodiment, a rivet contact having a ratio (W / D) of 1.1 between the width W of the flange and the diameter D of the foot is manufactured. The contact material of the rivet contact, the base material of the foot and flange, and the material of the terminal member are the same as those in Embodiment 1. The dimensions of the rivet contact and the terminal member of this embodiment are as follows.

[0074] ・Rivet contacts Head size: diameter 5mm x height 1mm Flange size: width (W) 3.3mm x height (H) 1.1mm Foot size: diameter (D) 3mm x length 2.5mm W / D=1.1

[0075] ・Terminal components Overall size: 40mm×16mm, thickness 3mm Counterbore size: diameter 3.4mm × depth (h) 1mm h / H=1.1

[0076] Then, the rivet contact was inserted into the terminal member, and the lower end of the leg was pressed and compressed while the head of the rivet contact was restrained, as in Example 1. In this example, the processing rate of the compressed leg was set to 30%.

[0077] The electrical contact of Example 2 was cut along the center line of the head of the rivet contact and observed in cross section. Fig.14 A cross-sectional photograph and a partial enlargement thereof are shown in FIG. In the electrical contact of this embodiment, almost no gap is observed at the joint interface between the flange and the leg, indicating that extremely good adhesion is obtained. The close contact area ratio of the joint interface between the flange and the countersunk hole of the rivet contact was measured and the result was 85.7%.

[0078] Example 3 In this embodiment, a rivet contact of the following dimensions is manufactured, in which the ratio (W / D) of the width W of the flange portion to the diameter D of the foot portion is 4.0. The materials of the rivet contact and the terminal member are the same as those in the embodiment 1. Then, as in the embodiment 1, the rivet contact is inserted into the terminal member, and the lower end of the foot portion is pressurized / compressed while restricting the head of the rivet contact. In this embodiment, the processing rate of the compressed foot portion is set to 10%.

[0079] ・Rivet contacts Head size: diameter 1.5mm × height 0.3mm Flange size: width (W) 4.8mm x height (H) 0.3mm Foot size: diameter (D) 1.2mm x length 1.5mm W / D=4.0

[0080] ・Terminal components Overall size: 40mm×16mm, thickness 0.7mm Counterbore size: diameter 4.9mm × depth (h) 0.2mm h / H=1.5

[0081] The cross-sectional photo of the electrical contact of Example 3 and its partial enlargement are shown in FIG. Fig.15 In the electrical contact of this embodiment, there is almost no gap at the joint interface between the flange and the leg, and extremely good adhesion is achieved. The close contact area ratio of the joint interface between the flange and the countersunk hole of the rivet contact is 99.6%.

[0082] The electrical contact of Example 3 was heated at high temperature to confirm whether an oxide layer was formed at the bonding interface. The heating conditions were the same as those of Example 1, and the heating was performed at 500°C for 60 minutes (in the air). Fig.16The results of cross-sectional observation are shown in . In this Example 3, as in Example 1, almost no oxide layer was observed to be formed at the bonding interface. The close contact area ratio based on oxide in this Example is 98.8%. This value is a value that can be approximated to the value of the close contact area ratio (99.6%) measured by observing the gap described above.

[0083] Embodiment 4, Embodiment 5 :In these embodiments, a rivet contact of the following dimensions was manufactured in which the ratio of the flange height of the rivet contact to the countersunk depth of the terminal member (h / H) was 0.5. The materials of the rivet contact and the terminal member were the same as those in Example 1. Then, as in Example 1, the rivet contact was inserted into the terminal member, and the lower end of the foot was pressurized / compressed while restricting the head of the rivet contact. In these embodiments, the processing rate of the compressed foot was set to 20% (Example 4) and 10% (Example 5).

[0084] ・Rivet contacts Head size: diameter 5mm x height 1mm Flange size: width (W) 7mm x height (H) 1.1mm Foot size: diameter (D) 4mm x length 3mm W / D=1.75

[0085] ・Terminal components Overall size: 40mm×16mm, thickness 4.2mm Counterbore size: diameter 7.1mm x depth (h) 2.2mm h / H=0.5

[0086] The cross-sectional photographs of the electrical contacts of these embodiments and their partial enlargements are shown in FIG. Fig.17 and Fig.18 In these examples, although there is a gap near the corner of the flange, there is no gap at the joint interface of the bottom surface of the flange, confirming good adhesion. The close contact area ratio of the joint interface between the flange and the countersunk hole of the rivet contact point is 85.0% in Example 4 (processing rate 20%) and 71.7% in Example 5 (processing rate 10%).

[0087] Fig.19 The results of a heating test (500° C.×60 min) on the electrical contact of Example 5. The close contact area ratio based on the oxide layer was also measured for the electrical contact of Example 5 after the heating test. The close contact area ratio based on the oxide layer was 76.6%.

[0088] Example 6In this embodiment, a rivet contact of the following dimensions was manufactured, in which the ratio of the flange height of the rivet contact to the countersunk depth of the terminal member (h / H) was 5. Then, the rivet contact was inserted into the terminal member in the same manner as in Embodiment 1, and the lower end of the leg was pressurized / compressed while the head of the rivet contact was restrained. In these embodiments, the processing rate of the compressed leg was set to 10%.

[0089] ・Rivet contacts Head size: diameter 5mm x height 1mm Flange size: width (W) 7mm x height (H) 1.1mm Foot size: diameter (D) 4mm x length 3mm W / D=1.75

[0090] ・Terminal components Overall size: 40mm×16mm, thickness 2.22mm Counterbore size: diameter 7.1mm × depth (h) 0.22mm h / H=5

[0091] The cross-sectional photographs of the electrical contacts of these embodiments and their partial enlargements are shown in FIG. Fig. 20 In Example 6, it can be said that the flange and the countersunk hole are in close contact over the entire surface of the contact area. The measurement result of the close contact area ratio of the joint interface between the flange and the countersunk hole at the rivet contact point is also 100%.

[0092] Table 1 below shows the results of summarizing the dimensions (W / D, h / H) and the close contact area ratio of the electrical contacts (rivet contacts and terminal members) of Examples 1 to 6 described above.

[0093] [Table 1]

[0094] As described above, the electrical contacts of Examples 1 to 6 all show a high close contact area ratio, have good close contact between the rivet contact and the terminal member, and can be expected to have excellent heat dissipation. In addition, in Examples 1, 3, and 5, the electrical contacts were heated at high temperatures, and the close contact area ratio based on the oxide layer of the bonding interface was evaluated, but their values ​​were very similar to the values ​​of the close contact area ratio based on the gap observed at the bonding interface. The oxide layer becomes an obstacle to heat transfer from the rivet contact to the terminal member. The electrical contacts involved in the present invention are assumed to be applied to high-voltage and high-current relays with a large heat generation, so it can be said that confirming the formation of an oxide layer is of great significance. Moreover, as described above, the observation of the oxide layer at the bonding interface is easier than the discovery / observation of the gap, so by measuring the area ratio of the oxide layer, the close contact can be easily evaluated.

[0095] Industrial Applicability

[0096] The rivet contact and the electrical contact of the present invention can improve the close contact between the rivet contact and the terminal member, and can dissipate the heat generated when the electrical contact is driven more effectively than before. In addition to being useful for electrical contacts mounted on general relays, switches, etc., the present invention is also useful for electrical contacts with higher heat generation, such as high-voltage and high-current relays.

Claims

1. A rivet contact, comprising: a head, at least a portion of the upper surface of which is provided with a contact material; and a foot, which supports the head and is inserted into a terminal member, characterized in that: A flange portion is formed between the head portion and the leg portion. The flange portion serves as a caulking margin and is wider than the leg portion.

2. The rivet contact according to claim 1, wherein: The ratio of the width W of the flange portion to the diameter D of the leg portion is greater than or equal to 1.1 and less than or equal to 4.

3. A combination of electrical contact members, consisting of a rivet contact and a terminal member, The rivet contact comprises: a head portion having a contact material on at least a portion of a surface thereof; and a leg portion supporting the head portion and inserted into the terminal member. The terminal member has an insertion hole for inserting the leg of the rivet contact and fixes the rivet contact. It is characterized in that In the rivet contact, a flange portion is formed between the head portion and the leg portion, the flange portion serves as a caulking margin and is wider than the leg portion. The terminal member is formed with a countersunk hole into which the flange portion is inserted.

4. The combination of electrical contact members according to claim 3, wherein: The ratio of the width W of the flange portion of the rivet contact to the diameter D of the leg portion is 1.1 or more and 4 or less.

5. The combination of electrical contact members according to claim 3 or claim 4, wherein: The ratio of the height h of the rivet contact flange portion to the depth H of the counterbore of the terminal member is 0.5 or more and 5 or less.

6. An electrical contact consisting of a rivet contact and a terminal member, The rivet contact comprises: a head portion having a contact material on at least a portion of an upper surface; and a leg portion supporting the head portion and inserted into the terminal member. The terminal member has an insertion hole for inserting the leg of the rivet contact and fixes the rivet contact. The rivet contact is fixed to the terminal member by performing riveting processing on the lower end of the leg portion after the leg portion is inserted into the insertion hole, It is characterized in that The rivet contact has a flange portion formed between the head portion and the leg portion, the flange portion serving as a rivet margin and being wider than the leg portion. The terminal member is formed with a countersunk hole, and the countersunk hole is used for the flange portion to be embedded. The flange portion is fitted into the counterbore and riveted.

7. The electrical contact according to claim 6, wherein: The close contact area ratio in any region of the joint interface between the side surface and the bottom surface of the flange portion of the rivet contact and the side surface and the bottom surface of the counterbore is 50% or more.

8. A method for manufacturing an electrical contact, using the combination of electrical contact components according to claim 2, wherein: The manufacturing method of the electrical contact comprises the following steps: inserting the rivet contact into the terminal member; and The rivet contact is fixed to the terminal member by plastic working the lower end portion and the flange portion of the leg portion of the rivet contact.

9. The method for manufacturing an electrical contact according to claim 8, wherein: In the process of plastically processing the lower end portion and the flange portion of the leg of the rivet contact, the lower end portion of the leg of the rivet contact is compressed while restricting the upper surface of the head and the flange portion of the rivet contact, thereby riveting the leg and the flange portion to the countersunk hole of the terminal member.

10. The method for manufacturing an electrical contact according to claim 8 or claim 9, wherein: In the step of plastically working the lower end portion and the flange portion of the leg portion of the rivet contact, the working rate of the leg portion is set to 10% or more.

11. The method for manufacturing an electrical contact according to claim 8 or claim 9, wherein: After the step of fixing the rivet contact to the terminal member, the method further includes the step of compressing at least the upper surface of the flange portion of the rivet contact.

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