JP2006150416A - Cold pressure-welding method, and metal joined body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold pressure-welding method capable of suppressing reduction in thickness at a weld part. <P>SOLUTION: When a first metallic plate 11 and a second metallic plate 12 are subjected to cold pressure-welded to manufacture a metal welded body 1, the first metallic plate 11 and a second metallic plate 12 are arranged in an overlapping manner, and held and fixed by a constraint tool 31 and a lower die 32, the metallic plates 11, 12 are pressed by penetrating a punch 2 through an opening part 311 formed in the constraint tool 31, the first metallic plate 11 is deformed in a drawing manner and allowed to enter the inside of the second metallic plate 12 to deform the second metallic plate 12 in a recessed manner. At least a part of the volume of the metallic plates 11, 12 displaced by the punch 2 is released to a recess 321 formed in the lower die 32. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cold welding method and a metal joined body, and more particularly, a cold welding method suitable for locally joining metal members together and joining, and a metal joined body produced by the method. About.

  When cold welding metal members together, the metal oxide film present on the joining surface of each metal member to be joined is removed, unoxidized metal is exposed, and minute gaps existing between the metal members It is necessary to close the exposed non-oxidized metals to the distance where the atomic force works.

  For this reason, for example, after removing the oxide film existing on the bonding surface of each metal member with a wire brush or the like, these metal members are overlapped with each other, and the overlapped portion is pressed and deformed to be bonded. It is used. At this time, the dimension of the part joined by the pressure deformation is set to, for example, about 20% of the thickness dimension before the pressure (see Patent Document 1).

  According to such a method, the metal member is deformed so as to be stretched by pressurization and the unoxidized metal is exposed, and the non-oxidized metals are brought close to each other by the pressurization, and the atomic force works. The exposed metal atoms are bonded together. Therefore, in order to join metal members using cold pressure welding, it is necessary to sufficiently stretch the metal at the joint. In the conventional cold welding, as a measure of the amount of extension, as described in Patent Document 1, a reduction in the dimension in the thickness direction of the joint is used as a measure. This is because in conventional cold welding, pressurization for exposing unoxidized metal by reducing the thickness of the joint by plastic deformation and crushing the minute gaps existing between the metal members to be joined. This is because the pressurization for bringing the atomic force close to the working distance was not separated.

  However, the crushing of the oxide film on the surface of the metal member due to plastic deformation and the unexposed metal exposure accompanying it are caused by the force in the direction parallel to the joint surface (that is, the interface) between the metal members. On the other hand, the pressure perpendicular to the bonding surface contributes to the pressurization for bringing the metal atoms close to the distance where the interatomic force works. For this reason, it is considered that these forces can be considered separately.

  Further, in the conventional cold welding, the dimension in the thickness direction of the joined portion after joining is greatly reduced, for example, to about 20% before joining. For this reason, the strength of the joint portion is lower than that of the other portion (that is, the portion that is not deformed), and the mechanical characteristics are deteriorated. In addition, when current is passed between metal members through the joined portion, the joined portion has a smaller cross-sectional area and higher electrical resistance than the other portions, so that the electrical characteristics only deteriorate. In other words, the bonded portion may locally generate heat. For the same reason, the joined portion may be a heat flow bottleneck between the metal members.

JP-A-2-25287

  In view of the above circumstances, the problem to be solved by the present invention is to provide a cold welding method capable of suppressing a decrease in the thickness direction of the joined members at the joint, or joined by cold welding. Another object of the present invention is to provide a metal joined body in which a reduction in dimension in a direction perpendicular to a joining surface at a joined portion is small.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a plurality of stacked metal members are pressed by a punch from a direction intersecting the overlapping surface of the metal members, and a recess is formed on the surface of the metal member. And at least a part of the volume of the metal member displaced by the pressing of the punch is deformed and joined so as to raise the opposite surface pressed by the punch. Is a summary.

  The invention according to claim 2 is configured such that a plurality of metal members stacked are pressed by a punch from a direction intersecting the overlapping surface of the metal members so that a recess is formed on the surface of the metal member. It is manufactured by deforming and joining at least a part of the volume of the metal member displaced by the pressing of the punch while deforming so as to raise the opposite surface pressed by the punch. Is a summary.

  According to the first or second aspect of the present invention, when the metal members are stacked and pressed with a punch, the surface of one of the metal members directly pressed by the punch is concaved by the penetration of the punch. In addition, it sinks into a columnar shape inside the other metal member. The other metal member is recessed and deformed by the one metal member, and at least a part of the volume displaced by the penetration of the punch projects from the opposite surface. For this reason, the reduction | decrease of the thickness direction dimension of a junction part can be suppressed. Therefore, it is possible to suppress a decrease in mechanical strength, an increase in electrical resistance, or an increase in thermal resistance at the joint portion.

  In addition, since the reduction in the dimension in the thickness direction after bonding is suppressed, the penetration depth of the punch is increased in order to increase the bonding strength between the metal members while suppressing the decrease in mechanical strength at the bonded portion. be able to.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is an external perspective view schematically showing the main part of an embodiment of the cold welding method according to the present invention, FIG. 1 (a) is an exploded perspective view, and FIG. 1 (b) is an exploded perspective view. FIG.

  As shown in FIG. 1 (a) or (b), in this embodiment, the first metal plate 11 and the second metal plate 12, which are members to be joined, are overlapped and sandwiched between the restraining jig 31 and the lower die 32. Then, the metal plates 11 and 12 that are superposed are pressed and deformed by the punch 2 and joined to obtain a metal joined body.

  As shown in FIG. 1A, the restraining jig 31 is formed in a substantially block shape, and a restraining groove 312 capable of restraining the first metal plate 11 or the second metal plate 12 is formed. Further, an opening 311 through which the punch 2 can be inserted is formed in the restraining jig 31 in a direction substantially perpendicular to the bottom surface of the restraining groove 312. The lower mold 32 is also formed in a substantially block shape, and a restraining groove 322 that can be restrained by engaging the first metal plate 11 or the second metal plate 12 is formed. A concave portion 321 that is recessed in a step shape is formed on the bottom surface of the restraining groove 322. The dimension and shape of the recess 321 will be described later. In addition, in a state where the restraining jig 31 and the lower die 32 are overlapped, the axis of the opening 311 formed in the restraining jig 31 and the center of the recess 321 formed in the lower die 32 are formed to coincide with each other. The

  And as shown in FIG.1 (b), when the 1st metal plate 11 and the 2nd metal plate 12 are piled up and the restraining jig 31 and the lower mold | type 32 are mounted | worn, the 1st and 2nd metal plate 11 will be shown. , 12 are fitted into the restraining jig 31 and the restraining grooves 312 and 322 of the lower mold 32 and restrained so that they cannot be separated or deformed in the surface direction. In this state, the punch 2 is inserted from the opening 311 formed in the restraining jig 31 as indicated by an arrow a, and the metal plates 11 and 12 are pressed and joined. In the present specification, of the two metal plates 11 and 12, the metal plate that is disposed on the restraining jig 31 side and is directly pressed by the punch 2 is referred to as a “first metal plate 11”. The metal plate disposed on the lower mold 32 side and indirectly pressed by the first metal plate 11 is referred to as “second metal plate 12”.

  In addition, what was generally used conventionally can be applied to the punch 2. Further, as the restraining jig 31, the lower die 32, the driving mechanism and the power source (not shown) of the punch 2, etc., the same ones used in conventional cold welding are applied. Therefore, these descriptions are omitted.

  The materials of the first metal plate 11 and the second metal plate 12 that are the members to be joined are not limited. For example, the same kind of metals such as aluminum, copper, aluminum alloys, and copper alloys may be used, or different metals such as aluminum and copper, pure copper and copper alloy may be used.

  Next, the implementation procedure of this embodiment and the bonding mechanism will be described. FIG. 2 is a cross-sectional view schematically showing the procedure of the present invention and the structure of the metal joined body to be manufactured. Here, FIG. 2A shows a state in which the metal plates 11 and 12 are overlapped with each other and the restraining jig 31 and the lower mold 32 are attached and before joining. FIG. 2B shows a state where the punch 2 is being joined. FIG. 2C shows the metal joined body 1 formed after the joining is completed. Although the shape of the punch 2 to be used is not particularly limited, a cylindrical punch is used for convenience of explanation.

  First, as shown in FIG. 2A, the first metal plate 11 and the second metal plate 12 are overlapped and sandwiched and fixed by a restraining jig 31 and a lower mold 32. Then, the punch 2 is inserted into the opening 311 formed in the restraining jig 31 and moved in the direction indicated by the arrow a, and the first metal plate 11 and the second metal plate 12 are pressed.

  As shown in FIG. 2B, when the stacked metal plates 11 and 12 are pressed by the punch 2, the first metal plate 11 is narrowed at a portion where the end surface of the punch 2 abuts and its vicinity. The concave portion is formed by being deformed, and the narrowed portion becomes a cylindrical shape and enters the inside of the second metal plate 12. On the other hand, the second metal plate 12 is pushed away by the first metal plate 11 entering the columnar shape to form a recess, and at least a part of the pushed volume is formed in the lower mold 32. Escape into the recess 321. Note that, depending on the penetration depth of the punch 2, the portion of the first metal plate 11 that is narrowed in a columnar shape may reach the inside of the recess 321 formed in the lower mold 32.

  As a result, as shown in FIG. 2C, a recess was formed on the surface of the first metal plate 11 by the penetration of the punch 2, and the surface of the second metal plate 12 was pushed away by the punch 2. The metal joined body 1 in which the volume escapes into the concave portion 321 of the lower mold 32 and the convex portion is formed is obtained.

  The structure of the joint portion of this embodiment will be described in a simplified manner. As shown in FIG. 2 (b), the portion of the first metal plate 11 pressed by the punch 2 has a cylindrical shape with an outer diameter of r and a height of h, and is placed inside the second metal plate 12. Suppose you are sinking. Thereby, the contact area between the first metal plate 11 and the second metal plate 12 is the area of the side surface of the submerged cylinder (2 × π (circumferential ratio) × r (radius of the cylinder) × h ( Increasing by the height of the cylinder)).

Here, while the metal plates 11 and 12 are pressed by the punch 2 and are in contact with each other, the contact surfaces of the metal plates 11 and 12 are not exposed to the outside air. Moreover, since the oxide film already existing on the surfaces of the metal plates 11 and 12 has a low ductility, the oxide film is crushed and unoxidized metal is exposed. The increase rate of the contact area between the metal plates 11 and 12 in the joint and its vicinity is (area of the side surface of the cylinder) / (area of the end face of the cylinder) = 2πrh / πr ² = 2h / r. Since the increased area is an active metal surface and has a strong bonding force, in order to firmly join the metal plates 11 and 12, the insertion depth h of the punch 2 can be increased to increase the area increase rate. preferable.

  Then, at least a part of the volume of the metal plates 11 and 12 pushed away by the punch 2 escapes to the recess 321 formed in the lower mold 32. For this reason, the thickness of the joined part after joining is a volume obtained by subtracting the insertion depth of the punch 2 from the original thickness obtained by superimposing the two metal plates 11 and 12, and the volume escaped to the concave part 321 of the lower mold 32. The thickness is added. For this reason, compared with the case where the recessed part 321 is not formed in the lower mold | type 32, the thickness dimension of a junction part can be enlarged. Therefore, the increase in the insertion depth of the punch 2 in order to increase the contact area between the metal plates 11 and 12 can suppress the reduction in the thickness dimension at the joint.

  Moreover, since the reduction of the thickness dimension of a junction part can be suppressed small, the fall of the mechanical strength by the reduction of a thickness dimension can be suppressed. In addition, when an electric current is passed between the first metal plate 11 and the second metal plate 12 through the joint portion, an increase in local electrical resistance due to a decrease in the cross-sectional area and a heat generation associated therewith are generated. Can be suppressed. Similarly, the resistance of the heat flow between the first metal plate 11 and the second metal plate 12 can be reduced. Therefore, the metal joined body 1 manufactured in this way is excellent in mechanical characteristics, electrical characteristics, or thermal characteristics.

  Note that the volume change due to elastic deformation of the metal plates 11 and 12 and the volume of the voids existing on the contact surface are extremely small compared to the volume of the metal plates 11 and 12 pushed away by the punch 2. Therefore, ignoring the volume of the gap, the volume that the punch 2 has pushed away, the volume that the first metal plate 11 has entered the second metal plate 12, and the volume of the recess 321 that is formed in the lower mold 32. Are all considered equal. Therefore, the size and shape of the recess 321 formed in the lower mold 32 is appropriately determined based on the diameter of the punch 2 and the insertion depth.

  However, in actuality, the volume of the recess 321 formed in the lower mold 32 is taken into consideration in consideration of elastic deformation of the metal plates 11 and 12 and the volume of a minute gap existing on the contact surface between the metal plates 11 and 12. It is preferable to make the volume slightly smaller than the volume displaced by inserting the punch 2. If it does in this way, it will become easy to apply the pressure required in order to make the contact surface of each metal plate 11 and 12 close to the distance which crushes the minute space which exists, and atomic force works.

  Next, examples of the present invention will be described. FIG. 3 is an external perspective view showing an embodiment of a metal joined body according to the present invention, where (a) is an example used for connection between a terminal and a conductor, and (b) and (c) are called bus bars. This is an example used to connect large current conducting wires.

  Briefly describing each of them, the metal joined body 1a shown in (a) includes a conducting wire 42 for passing a current and a terminal 41 for connecting the conducting wire 42 to another conducting wire, another device, or the like. For example, the conducting wire 42 is made of pure copper having a low electrical resistance, and the terminal 41 is made of a copper alloy having good spring properties. When such a material is selected, the power transmission efficiency in the conducting wire can be improved and the connection reliability at the terminal 41 can be improved. The metal joined bodies 1b and 1c shown in (b) and (c) are applied to joining the bus bars 43 and 45 formed of copper or aluminum and the bus bars 44 and 46 formed of the same or different metals. It is what is done. Thereby, a planar or three-dimensional wiring structure can be easily assembled.

  As described above, the method according to the present invention is used in place of conventional joining means such as bolting, rivet caulking, and welding, and is unique to cold rolling, such as simplicity and applicability to materials that are difficult to weld. Benefits can be exploited. And the metal joined body 1a, 1b, 1c manufactured in this way has little reduction of the cross-sectional area in the junction part of the conducting wire 42 and the terminal 41, and the junction part of the bus bars 43 and 44 (or 45, 46). Therefore, an increase in electrical resistance at the joined portion and accompanying heat generation can be suppressed. Moreover, since the conducting wire 42 and the terminal 41 or the bus bars 43 and 44 (or 45 and 46) are firmly joined, the mechanical strength is high and the reliability of the joined portion can be improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention. . For example, the number of metal members to be joined is not limited to two. Further, the shape of the metal member is not limited to a plate shape.

It is the external appearance perspective view which showed the outline of the principal part typically about the joining method which concerns on embodiment of this invention, (a) shows the state which decomposed | disassembled, respectively, (b) shows the state couple | bonded. It is sectional drawing which showed typically the implementation procedure of the joining method which concerns on embodiment of this invention, and the structure of the metal joined body which concerns on this invention, (a) is the state before joining, (b) is joining (C) shows the structure of the manufactured metal joined body. It is the external appearance perspective view which showed schematic structure of the metal conjugate | zygote which concerns on the Example of this invention, (a) is an example applied to joining of a terminal and a conducting wire, (b), (c) is for large currents It is an example applied to joining of conducting wires.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal joined body 11 1st metal plate 12 2nd metal plate 2 Punch 31 Restraint jig 32 Lower mold 311 Opening 312 Restraint groove 321 Recess 322 Restraint groove

Claims (2)

  The stacked metal members are pressed by a punch from a direction intersecting the overlapping surface of the metal members to be deformed so that a concave portion is formed on the surface of the metal member, and pushed by the punch. A cold pressure welding method, wherein at least a part of the volume of the metal member is joined while being deformed so as to raise the opposite surface pressed by the punch.   A plurality of superimposed metal members are pressed by a punch from a direction intersecting the overlapping surface of the metal members to be deformed so that a concave portion is formed on the surface of the metal member, and pushed by the punch. A metal joined body produced by joining at least a part of the volume of the formed metal member while deforming so that the opposite surface pressed by the punch is raised.

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