JP5064688B2 - Resistance welding equipment - Google Patents

Description

  The present invention relates to a workpiece to be welded made of various kinds of the same or different metal materials, in particular, a second workpiece to be welded made of a metal material having a higher melting temperature (melting point) than the first workpiece to be welded, and the first The present invention relates to a resistance welding apparatus capable of resistance welding a workpiece.

  Various methods for joining dissimilar metal materials with different characteristics such as melting point and conductivity, such as metal materials of the same type, iron-based materials and stainless steel materials, iron-based materials and copper materials, or iron-based materials and aluminum materials, have been proposed. However, joining of dissimilar metal materials is considered difficult compared to joining of metal steel plates made of, for example, iron-based materials, that is, joining of the same material. In particular, since resistance welding of dissimilar metal materials has many technically difficult surfaces, they are often joined by hard soldering, ultrasonic joining, or mechanical joining such as caulking and bolting. Bonding of copper material and aluminum material with very good conductivity has been performed by the same means, but in such a joining method, from the use of using copper material and aluminum material with very good conductivity. Seen, the interface resistance cannot be made so small that it can be ignored. Therefore, among the dissimilar metals, resistance welding between copper material and aluminum material with very good electrical conductivity is considered to be particularly difficult, and efforts to conduct resistance welding that can reduce the interface resistance have already been made. An improved technique is also disclosed that enables resistance welding between a copper material and an aluminum material by performing such a processing step in advance (see, for example, Patent Document 1).

In this method, the copper material and the aluminum material cannot be directly resistance welded. Therefore, before the resistance welding, the bonding surface of the copper material is coated with tin in advance, and further processing is performed on the interface between the copper material and tin. After forming a tin coating layer that forms a solid solution of copper and tin, the tin coating layer is brought into contact with the aluminum material, and the tin coating layer that is formed into a solid solution is placed between the copper material and the aluminum material. Pressure is applied in an intervening state, and resistance welding is performed by flowing a welding current. In addition, in resistance welding of dissimilar metals, a resistance welding method and a resistance welding apparatus have been reported that can obtain a good welding result by processing a joint of dissimilar metals into an optimal special shape in advance (for example, patents). Reference 2-5).
JP 2001-087866 A Japanese Patent Laid-Open No. 08-1118040 Japanese Patent Laid-Open No. 10-128550 Japanese Patent Laid-Open No. 10-156548 Japanese Patent Laid-Open No. 11-033737

  However, in the resistance welding method disclosed in Patent Document 1, the step of forming tin on the bonding surface of the copper material and the step of generating a solid solution of copper and tin at the interface between the copper material and tin Is necessary, and the cost is increased due to the apparent increase in manufacturing processes. Further, as described in Patent Document 1 mentioned above, the copper material and the aluminum material are melted to form a nugget during the resistance welding, and at this time, it is necessary to prevent tin from being ejected to the outside. Although tin is easily ejected in this way, although there is a difference between tin and zinc, it is only experienced when welding zinc-coated steel sheets. The thickness of the tin, the magnitude of the welding current, and the energization time so that tin does not eject In addition, various conditions such as the magnitude and timing of the applied pressure must be strictly controlled, and it is difficult to incorporate such a welding process into an actual manufacturing process because strict control must be maintained. Moreover, although the structure of the junction part described in patent documents 2-5 mentioned above is suitable for the to-be-welded object which consists of a dissimilar metal material of a specific structure, it is as it is especially for resistance welding of a copper material and an aluminum material. It is difficult to apply, and good welding results cannot be obtained even with the resistance welding apparatus disclosed in the above-mentioned patent document.

  Therefore, the present invention solves the above-mentioned problems, and has a melting temperature higher than that of the first workpiece made of aluminum material as well as welding of the workpieces made of the same kind of metal material as between steel plates. The main purpose is to provide a resistance welding apparatus capable of performing resistance welding with a second workpiece made of a high copper material, etc., capable of obtaining a welding result that is simple, inexpensive, and has high welding quality. Yes.

According to a first aspect of the present invention, an annular projection formed on a strip-shaped first workpiece or second workpiece made of a different metal material is used as the second workpiece or the first workpiece. In a state where the first workpiece and the second workpiece are sandwiched between the first welding electrode and the second welding electrode and pressurized, and pulse welding is performed between them. A resistance welding apparatus for welding an electric current to weld the first workpiece and the second workpiece, the first welding material comprising a metal material having a melting point lower than that of the second workpiece. the object to be welded has a short width D smaller than 3 times the ring diameter or cyclic width d of the annular projection, respectively the short width direction at both ends of the strip of the first object to be welded abuts, expansion in the short width direction the part of the short width D of the first object to be welded is plastic flow during welding Providing resistance welding apparatus characterized by comprising a first inhibiting jig and the second width expansion suppressing member having a suppression jig restrain the that.

According to the present invention, not only the same type of material but also different types of metal materials, in particular, an aluminum material having good conductivity, which is difficult to directly resistance weld, and a melting temperature (melting point) and conductivity higher than that of the aluminum material. A high copper material can be easily resistance-welded, and a welding result with high welding quality can be obtained at substantially the same welding cost as in the case of resistance welding of ordinary workpieces such as steel materials. Moreover, even when the short width of the workpiece is small, an intended welding result can be obtained without being deformed by heat.

[Embodiment 1]
A first embodiment of resistance welding according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining an annular projection according to the first embodiment, and FIG. 2 is a diagram showing an outline of an example of a capacitor storage type resistance welding apparatus suitable for realizing the present invention. First, the range to which the present invention can be applied can be applied to resistance welding of various general metal materials of the same kind or to-be-welded objects made of various different kinds of metal materials, but resistance welding is particularly difficult in the first embodiment. Examples of copper or copper alloy and aluminum or aluminum alloy are described below. Therefore, in this specification, “copper material” means “copper or copper alloy”, and “aluminum material” means “aluminum or aluminum alloy”.

  In general, a copper material often has a higher melting temperature (melting point) and higher electrical conductivity than an aluminum material. In addition, an oxide film is easily formed on the surface of the aluminum material. As a result of various experiments conducted by the inventor in consideration of such characteristic differences, the weld surface of the aluminum material is kept flat, and the conductivity and the melting temperature are higher than those of the aluminum material. An annular projection is formed on the copper material, and a pulsed welding current, for example, a welding current having a pulse width of about 30 ms or less, preferably about 10 ms or less, is passed between welding electrodes having a good pressure response to the workpiece. As a result, good welding results could be obtained. Here, a workpiece made of an aluminum material is referred to as a first workpiece W1, and a workpiece made of a copper material is referred to as a second workpiece W2. 1 and 2, the first work piece W1 is not shown, but the first work piece W1 has, for example, a short width and thickness similar to those of the second work piece W2. It is a strip-shaped one.

  As shown in FIG. 1A, an annular projection, preferably an annular projection P, is formed at the welding location of the second workpiece W2 which is a strip-shaped copper plate. This annular projection P forming apparatus uses a general projection forming apparatus and will not be described in detail. However, the annular projection P forming apparatus is a mold apparatus that forms the annular projection P by narrowing down the welded portion of the second workpiece W2. is there. This projection forming apparatus may be in the vicinity of a capacitor energy storage type resistance welding apparatus (FIG. 2), which will be described later, or a place different from the place where the capacitor energy storage type resistance welding apparatus is installed. The annular projection P may be formed on the second work piece W2. Here, the width in the longitudinal direction of the strip-shaped second workpiece W2 is referred to as a long width, and the width perpendicular to the longitudinal direction is referred to as a short width. For example, the second workpiece W2 has a short width D that is 30 mm or less. The distance between locations that are substantially the top of the annular projection P is indicated by d. When the annular shape of the projection P is an annular shape, the diameter of the annular shape is called an annular diameter, and the annular shape of the projection P is a quadrangular shape. For example, the width between opposite sides of the square ring is called an annular width. An annular diameter or an annular width of the annular projection P is indicated by d. FIG. 1B shows a cross section of the second workpiece W2 at the portion where the annular projection P is formed. The cross section shows a shape cut by a line extending in the horizontal direction, that is, in the short width direction, through the center point c of the annular projection P shown in FIG. The annular projection P protrudes so as to surround a small surface area A on the outer surface of the second workpiece W2. FIG. 1C is an explanatory diagram thereof, and the projection P has an inclination extending from the top at an angle θ, that is, an angle extending from the surface area A to the top at approximately (180−θ) / 2 degrees.

When this spreading angle θ is described, the angle θ is preferably 80 degrees or more. The second object to be welded (Cu) W2 higher melting temperature than the first object to be welded (Al) W1, because in general conductivity is high, that put the second object to be welded W2 during welding before the ring-shaped projection P starts plastic flow, the first object to be welded W1 starts plastic flow. Therefore, when the spread angle θ is smaller than 80 degrees, the annular projection P that has not started plastic flow may sink into the first work piece W1 that has started plastic flow. Therefore, the desired resistance welding is not performed, so that the required welding strength cannot be obtained. That is, when both the first work piece W1 and the second work piece W2 are plastically flowed, diffusion bonding that provides the desired welding strength is performed for the first time, whereas the spread angle θ is 80. If it becomes smaller than the degree, it becomes a halfway joining and the desired welding strength cannot be obtained. Therefore, the expansion angle θ of the annular projection P is preferably 80 degrees or more. This is related to other welding conditions and will be described later. Although the height of the projection P is not particularly limited, for example, the height is about 0.5 to 3 mm for ease of production of the projection, and the maximum value of the spread angle θ is less than 180 degrees, and practically about 130 degrees or less. preferable.

  Next, an example of a capacitor accumulating resistance welding apparatus suitable for resistance welding of the second workpiece W2 and the first workpiece W1 on which such an annular projection P is formed is illustrated. 2 will briefly explain. This resistance welding apparatus is substantially the same as that described in Patent Document 4 described above. A support mechanism 2 is fixed to a floor or base member 1 on which the resistance welding apparatus is installed. A pressurizing mechanism 3 made of a cylinder device or the like is attached to the support mechanism 2, and a movable block 4 made of a metal material is attached to the tip of the pressurizing mechanism 3. A pressurizing auxiliary member 5 such as a spring or an electromagnetic pressurizing device is provided between the movable block 4 and the support member 6 and plays an auxiliary role to improve the pressurization response of the welding electrode. Here, the supporting member 6 is made of a metal material such as copper which is directly or indirectly coupled to the lower end portion of the pressure assisting member 5 and also functions as a power feeding portion. The upper welding electrode 7 is supported by the support member 6, and the lower welding electrode 8 is disposed at a position facing the upper welding electrode 7. An L-shaped intermediate connecting member 9 is fixed to the movable block 4 positioned at a height that is not affected by the expansion and contraction of the pressure assisting member 5. A flexible first flexible conductive member 10 that connects between the support member 6 and the L-shaped intermediate connection member 9 is provided, and a conductor 11 is provided between the L-shaped intermediate connection member 9 and one power supply conductor 12. It is connected. The conductor 11 is a second flexible conductive member that is longer than the first flexible conductive member 10.

  The secondary winding N2 of the welding transformer 14 is connected between the power supply conductor 12 and the other power supply conductor 13 connected to the lower welding electrode 8, and the primary winding N1 magnetically coupled thereto is connected to the primary winding N1. A discharge circuit 15 such as an inverter circuit or a semiconductor switch circuit is connected. Connected to the discharge circuit 15 are an energy storage capacitor 16 and a charging circuit 17 for charging the capacitor. Here, the pulse width of the welding current is about 30 ms or less, preferably about 10 ms or less in resistance welding of a copper material and an aluminum material. In order to allow such a steep pulse current with a narrow pulse width to flow between the copper material and the aluminum material, the energy storage capacitor 16 such as the discharge circuit 15, the welding transformer 14, and the power supply conductors 12 and 13 may be used. The energization path through which the discharge current flows has a circuit configuration that minimizes inductance. For this purpose, for example, the power supply conductors 12 and 13 are shortest, and the conductor serving as the wiring is arranged so as to cancel out the inductance. In this structure, the upper welding electrode 7 is supported by a supporting member 6 that can move up and down with a slight external force, and at the same time, is coupled to a pressurizing auxiliary member 5 that can provide highly responsive elastic force. Therefore, the upper welding electrode 7 can immediately respond to a slight change in the applied pressure due to plastic flow between the first workpiece W1 and the second workpiece W2. Symbols 18 to 20 represent three-phase AC input terminals.

  Next, resistance welding according to the first embodiment will be described with reference to FIG. First, the second workpiece (Cu) W2 in which the annular projection P is formed as described above is stacked on the first workpiece (Al) W1 placed on the lower welding electrode 8 to form an annular shape. The projection P is brought into contact with the upper surface of the first workpiece W1. Next, the pressurizing mechanism 3 in FIG. 2 operates to operate downward, and accordingly, the entire upper welding head composed of the movable block 4, the pressurizing auxiliary member 5, the support member 6 and the upper welding electrode 7 is lowered. Then, the upper welding electrode 7 applies a predetermined pressure to the second workpiece W2. During the application of the predetermined pressure, or when the pressure becomes substantially constant, the discharge circuit 15 is turned on, and the charge already charged in the energy storage capacitor 16 by the charging circuit 17 is welded. It is discharged to the primary winding N1 of the transformer 14. Along with this, a large current is generated in the secondary winding N2 of about 1 or 2 turns, which has a significantly smaller number of turns than the primary winding N1, and is sandwiched between the upper welding electrode 7 and the lower welding electrode 8. A pulsed welding current flows through the first work piece W1 and the second work piece W2. As described above, this pulsed welding current is a single current pulse that increases rapidly at 30 ms or less, preferably 10 ms or less, and rapidly decreases after a short time.

  Such a pulsed welding current concentrates on the annular projection P of the second workpiece W2 and flows for a short time. Although the resistance of the contact surface between the annular projection P of the second workpiece W2 and the first workpiece W1 is small, the contact area is small, so that the current density is increased accordingly, and resistance welding is performed. . Unlike the small circular point contact of the conventional projection, the contact area between the annular projection P of the second workpiece W2 and the first workpiece W1 is an annular thin line contact. The heat generated in the annular projection P of the second workpiece W2 starts plastic flow of the annular projection P and also plastically flows the contact portion of the first workpiece W1. At that time, the heat conduction between the first workpiece and the second workpiece is extremely good, so that the heat obtained by plastic flow of the annular projection P is not only in the outer direction of the annular projection P, It is also transmitted to the inner surface area A side. In this respect, the small circular contact of the conventional projection only transfers heat to the outside, and only the small circular contact portion is joined, so the required welding strength cannot be obtained. In addition, if the contact area of the circular contact portion is increased, the current density is reduced in the welding of the first work piece and the second work piece having high conductivity, so a projection is provided. In the end, good welding results cannot be obtained. Further, even if the welding current is simply increased, a satisfactory welding result cannot be obtained, which is why it is said that resistance welding between a copper material and an aluminum material is difficult.

  In the present invention, even if the contact area between the annular projection P of the second workpiece W2 and the aluminum plate W1 is about the same as that of the conventional projection, the annular line contact area of the annular projection P is Compared to the conventional point-like case, the surface area is substantially wider, and as described above, the heat generated in the annular projection P plastically flowed is not only in the outer direction of the annular projection P but also in the area A side of the annular projection P. Therefore, not only the heat balance is good, but also the contact portion of the aluminum plate W1 that is in line contact with the annular projection P also plastically flows, so that a good welding result can be obtained. Here, regardless of the annular diameter or annular width d of the annular projection P, if the line contact area between the annular projection P and the aluminum plate W1 is substantially the same, good diffusion can be achieved with substantially the same pulse welding current. Bonding can be performed. Also, even if the annular diameter or annular width d of the annular projection P is increased to increase the line contact area, it is equally good if the peak value of the pulsed welding current is increased so that the current density can be made substantially constant. The welding result can be obtained. The reason for this is that heat generated in the annular projection P is transmitted to the inner portion along the annular projection P, that is, not only to the outside but also to the inside. This is because the plastic flow is preferable and good diffusion bonding is performed.

  In the resistance welding of the first work piece W1 and the second work piece W2, good welding results are largely obtained by the annular projection P described above. There is also a place to bear. The operation of the resistance welding apparatus shown in FIG. 1 will be described. First, when the pressurizing mechanism 3 operates and operates in the downward direction, the entire upper welding head including the movable block 4, the pressurizing auxiliary member 5, the support member 6 and the upper welding electrode 7 is lowered. On the other hand, although not shown, the first workpiece W1 is set on the lower welding electrode 8, and the second workpiece W2 clamped on the upper welding electrode 7 becomes the first workpiece W1. Abutted. The upper welding electrode 7 and the support member 6 stop at that position, but as the pressurizing mechanism 3 further descends, the pressurizing auxiliary member 5 contracts, and the metal block 4 descends together with the pressurizing mechanism 3. To do.

  Further, as the movable block 4 is lowered, the second flexible conductive member 11 is greatly bent, and the first flexible conductive member 10 is moved together with the movable block 4 and the support member 6, so that it is lowered in the initial state. As described above, when the support member 6 is stopped and the movable block 4 is lowered while the pressurizing auxiliary member 5 is contracted, it is slightly deformed from the initial state. However, as described above, the first flexible conductive member 10 is made to be more easily bent than the second flexible conductive member 11, so that the power supply conductor is formed by a single flexible conductor corresponding to the second flexible conductive member 11. Compared with the conventional case in which 12 and the support member 6 are connected, adverse effects on the movement of the support member 6 and the upper welding electrode 7 are reduced. Therefore, the responsiveness of the upper welding electrode 7 is improved.

  In a state where the pressurizing mechanism 3 is pressurized, the gap between the metal block 4 and the support member 6 is reduced after the upper welding electrode 7 and the like are stopped, and the pressurizing auxiliary member 5 stores downward mechanical energy. They also act to absorb upward forces above a certain level. As described above, the pressure assisting member 5 contracts during the downward movement of the pressure mechanism 3 and the pressure between the upper welding electrode 7 and the lower welding electrode 8 reaches a predetermined level. Then, a pulsed welding current having a short pulse width is supplied from the welding transformer 14 and the power supply conductors 12 and 13 to the upper welding electrode 7 and the lower welding electrode 8. By applying a pulse welding current having a short pulse width in a state of being pressurized with a predetermined pressure, the contact portion between the first workpiece W1 and the second workpiece W2 and its adjacent portion are plastically flowed. However, the other parts are hardly affected. When the pressure assisting member 5 is a spring as the plastic flow starts, the spring instantaneously absorbs the expansion of the joining portion at the initial stage of welding, and the spring always joins the joining portion in a state where the pressing force is working. Since pressure is applied to the first and second workpieces W1 and W2, it is possible to apply pressurization that is extremely quick in response to the sink due to plastic flow between the first workpiece W1 and the second workpiece W2. it can.

  As the response speed of the pressure assisting member 5 increases, the pulse welding current having a short pulse width, that is, the current energy is concentrated in a short time, and the first workpiece W1 and the second workpiece W2 are welded. Even a material having a very good thermal conductivity such as a copper material or an aluminum material can be plastically flowed in a preferable state, so that satisfactory diffusion bonding can be achieved. One means that works so as not to lower the response speed of the pressure assisting member 5 than the conventional one is the first flexible member 10 that is easily bent, and the other means is the pressure assisting member 5. The response speed of the pressure assisting member 5 is preferably faster than the pulse width of the pulsed welding current. As described above, the response speed of the welding electrode is high, the width of the pulsed welding current is as narrow as 30 ms or less, and the annular projection P as described in detail is formed on the copper material. The material can be resistance-welded more stably and satisfactorily.

[Embodiment 2]
Next, a second embodiment of resistance welding according to the present invention will be described with reference to FIGS. FIG. 4 is a diagram for explaining an annular projection according to the second embodiment, and FIG. 5 is an example of a preferred welding electrode used in a capacitor energy storage type resistance welding apparatus suitable for realizing resistance welding according to the present invention. It is a figure which shows a cross section. 4 and 5, the same symbols as those used in FIGS. 1 to 3 indicate members having the same names as those used in the drawings. Since the annular projection P in the second embodiment is the same as the annular projection P in the first embodiment, the upper surface of the second workpiece W2 in FIG. Since the annular projection P is formed, the upper surface is flat in the first embodiment, whereas an annular groove V having a conical or pyramidal tapered surface Ta is formed on the upper surface corresponding to the annular projection P. Is formed. The annular projection P is also preferably an annular projection. In this case, the annular groove V is an annular one having a conical tapered surface Ta.

  The upper welding electrode 7 has an annular protrusion 7A on the surface that comes into contact with the second workpiece W2. The annular protrusion 7A has a tapered surface Tb having substantially the same inclination as the tapered surface Ta of the annular groove V of the second work piece W2 and a top portion 7a substantially the same as or somewhat higher than the depth of the groove V. Therefore, when the annular groove V of the second workpiece W2 is positioned and supported on the annular projection 7A of the upper welding electrode 7, as shown in FIG. 5, the second workpiece W2 is welded. The bottom surface Va of the annular groove V is in contact with the top portion 7a of the annular protrusion 7A, and the conical tapered surface Ta of the groove V of the second workpiece W2 is in contact with the tapered surface Tb of the protrusion 7A. . At this time, the other portions may have a slight gap, for example, a minute gap of about 1 to 1/10 of the depth of the annular groove V, or may be in contact with each other.

  When the upper welding electrode 7 is lowered or the lower welding electrode 8 is raised so that there is no space between the first workpiece W1 and the second workpiece W2, the upper surface of the first workpiece W1 is first displayed. The top of the annular projection P of the second work piece W2 comes into contact with and is pressurized. When the applied pressure further increases to a predetermined value, the annular projection P of the second workpiece W2 is also somewhat deformed in close contact with the upper welding electrode 7, but in this state, the first workpiece W1 is deformed. And the second welding object W 2, the pulse-shaped welding current as described above flows between the upper welding electrode 7 and the lower welding electrode 8. The energization of the pulsed welding current is the same as in the first embodiment, but is performed while the annular projection P is not crushed by the applied pressure (forging pressure) between the welding electrodes 7 and 8. First, the pulsed welding current flows in a concentrated manner on the annular projection P, and the contact portion between the annular projection P and the first workpiece W1 starts plastic flow. Along with this, the parts that started plastic flow due to the applied pressure subside, and the outer adjacent part and the inner surface area of the annular projection P also start plastic flow and resistance welding is performed, so that good welding strength is obtained. It is done. Even with such an annular projection P, the same effect as in the first embodiment can be obtained.

[Embodiment 3]
Next, a resistance welding apparatus that is particularly suitable when the short width of the first workpiece W1 and the second workpiece W2 is narrow will be described with reference to FIG. In FIG. 6, the same symbols as those used in FIGS. 1 to 5 indicate members having the same names as those used in the drawings. Also in the third embodiment, the first workpiece W1 is made of an aluminum material, and the second workpiece W2 is made of a copper material. The second workpiece W2 has a structure as shown in FIG. 1, and the short widths of the first workpiece W1 and the second workpiece W2 are substantially the same and are D. .

  As described in the first and second embodiments, it has already been described that even when the pulse width of the pulsed welding current is as small as 30 ms or less, the abutting portion of the annular projection P and the vicinity thereof plastically flow. . Even when the heat input time is short, the heat generated by plastic flow at the contact portion of the annular projection P and the vicinity thereof is the first work piece W1 and the second work piece W2 having good heat conduction. In some cases, not only the contact portion of the annular projection P and the plastic flow portion in the vicinity thereof, but also the surrounding portions may be plastic flowed. The degree of plastic flow is not so high that diffusion bonding is performed. Particularly, when the short width of the first work piece W1 having a lower plastic flow temperature than the second work piece W2 is small, the resistance welding portion May flow plastically to the end in the short width direction, and in this state, the end in the short width direction may expand due to the applied pressure (forging pressure) between the upper welding electrode 7 and the lower welding electrode 8. This is because by preventing the end in the short width direction from expanding, it is possible to prevent the shape of the work piece from being changed, and since uniform plastic flow is performed, it is not necessary to lower the diffusion strength. .

  Therefore, the resistance welding apparatus according to the third embodiment includes the width expansion suppressing member 60 that prevents the short width of the first workpiece W1 or the second workpiece W2 from expanding. The width expansion suppression member 60 is roughly divided into a first suppression jig 61, a second suppression jig 62, and a linear motion drive member 63. The first suppression jig 61 is fixed on the lower welding electrode 8 and extends in the longitudinal direction of the first workpiece W1 and the second workpiece W2, that is, in the long width direction (the front and back direction on the paper surface). ing. The first restraining jig 61 has at least a surface abutting against the first workpiece W1 and the second workpiece W2 to have a height of the first workpiece W1 and the second workpiece as shown in the drawing. What is lower than the sum of the thickness of the work piece W2 and hindering the upper welding electrode 7 and the lower welding electrode 8 from applying a predetermined pressure to the first work piece W1 and the second work piece W2? Don't be. The first restraining jig 61 and the second restraining jig 62 are made of a metal material such as brass or an inorganic material. The second restraining jig 62 is the same as the first restraining jig 61, but the first restraining jig is that the second restraining jig 62 can move in the left-right direction on the lower welding electrode 8 in FIG. Different from 61. The second suppression jig 62 is driven by a linear drive member 63 made of a cylinder member or a motor drive member. When the first restraining jig 61 and the second restraining jig 62 are made of a conductive material, the surfaces that come into contact with the first workpiece W1 and the second workpiece W2 are not shown. It is preferably coated with an electrically insulating material.

Next, the operation of this apparatus will be described. Initially, the upper welding electrode 7 is stopped at the upper original position, and the linear drive member 63 moves the second restraining jig 62 to the left original position in the drawing. Has been stopped. When the width expansion suppressing member 60 needs to be operated, the following conditions are particularly satisfied. Referring to FIG. 1, when the short width D of the first workpiece W1 is smaller than about three times the annular diameter or annular width d of the annular projection P formed on the second workpiece W2. In particular, when it is smaller than about twice, the entire short width corresponding to the welded portion of the first workpiece W1 having a melting temperature lower than that of the second workpiece W2 due to the reasons described above. Since there is a high possibility of expanding in the short width direction due to plastic flow, it is effective to operate the width expansion suppressing member 60. When you back described based on, as shown in FIG. 6, stacked with the first object to be welded W1 and the projection P of the annular bottom and a second weld object W2, the left and right their short width paper of It is placed on the lower welding electrode 8 in the direction. Next, by driving the linear drive member 63 and moving the linear motion portion 63A forward (leftward in FIG. 6), the second restraining jig 62 is pushed and moved leftward in FIG. The second restraining jig 62 is brought into contact with the side surfaces of the workpieces W1 and W2 on the right side of the drawing.

  By this operation, the first workpiece W1 and the second workpiece W2 can be aligned and positioned on the lower welding electrode 8. The contact state of the second suppression jig 62 against the right side surface of the first workpiece W1 and the second workpiece W2 in the drawing indicates that the second suppression jig 62 has a force with the first welding target. The object W1 and the second workpiece W2 may be pressed against the right side of the drawing or may be in contact with each other. However, since the first workpiece W1 and the second workpiece W2 must be prevented from spreading in the short width direction when they are only in contact with each other, the second restraining jig 62 is used. Must have a reverse movement suppression function that does not move to the right unless it receives a force greater than the set value in the right direction in FIG. Therefore, if the width expansion suppressing member 60 is used, the short width D of the first workpiece W1 having a lower melting temperature (melting point) than that of the second workpiece W2 is formed in the second workpiece W2. Even when the annular projection P is smaller than approximately three times the annular diameter or annular width d, the first workpiece W1 does not expand and deform in the short width direction.

  In the third embodiment, the first workpiece W1 and the second workpiece W2 have been described as having substantially the same short width. However, the first workpiece W1 has a short width D of the annular projection P. In some cases, the short width of the second workpiece W2 is smaller than approximately three times the annular diameter or the annular width d, and in this case, the first restraining jig 61 and the second restraining jig may be larger. It is desired that the jig 62 is lower than the thickness of the first workpiece W1 so as not to contact the second workpiece W2. Further, the short width D of the second workpiece W1 is somewhat larger than the annular diameter or annular width d of the annular projection P, and the short width of the first workpiece W1 is the annular diameter of the annular projection P. Alternatively, in some cases, the first workpiece W1 and the second workpiece W2 are turned upside down so that the second workpiece W1 is turned upside down. The short width D may be suppressed from both sides by the first suppression jig 61 and the second suppression jig 62 as described above. In addition, when welding the 1st to-be-welded object W1 and the 2nd to-be-welded object W2 with which the short width was decided, without using the linear motion drive member 60, the upper welding electrode 7 and the lower welding electrode 8 are used. However, the structure may serve as both the first suppression jig 61 and the second suppression jig 62. In this case, it is convenient to adopt an electrode structure in which the first workpiece W1 and the second workpiece W2 are taken in and out from the front and back direction of the paper. In particular, an electrode tip that can be easily attached to and detached from each of the upper welding electrode 7 and the lower welding electrode 8 is used, and these electrode tips have a structure in which the first workpiece W1 and the second workpiece W2 can be taken in and out. In this case, the practicality becomes higher.

In any of the embodiments described above, an annular projection P is provided in the copper material, and the copper material side is described as an example in which a part of the annular projection P is plastically flowed from the front end portion to the middle, and is diffusion-bonded. The projection P may be plastically flowed to almost the base, that is, almost the whole of the annular projection P. Outside this case, either providing a groove in and out along the annular flop Roger transfection P, or is surrounded by a surface zone A in projection P a recess provided an annular flop Roger action P is plastic flow It is possible to obtain a preferable welding result when the structure is configured to receive the plastic flow portion pushed inward. Moreover, in the above embodiment, resistance welding of the 1st to-be-welded object W1 which consists of aluminum materials and the 2nd to-be-welded object W2 which consists of copper materials is said that resistance welding is very difficult in all. However, it is needless to say that the method and apparatus of the present invention can be applied to welding between different kinds of metals or resistance welding of the same kind of metal material. And also about these to-be-welded objects, welding strength can be improved. In addition to welding of dissimilar metals of copper material and aluminum material, in the resistance welding (diffusion bonding) of other dissimilar metals, the annular projection P is welded on the side having a higher plastic flow temperature. It is preferable to form. Of course, the first workpiece W1 and the second workpiece W2 may be disposed upside down in the embodiment described above and welded. Of course, the first workpiece W1 and the second workpiece W2 may be supported by the upper welding electrode 7 and the width expansion suppressing member 60 may be provided on the upper welding electrode 7 side.

It is a figure which shows the to-be-welded object for demonstrating the resistance welding method which concerns on Embodiment 1 of this invention. It is a figure which shows an example of the resistance welding apparatus for implement | achieving the resistance welding method which concerns on embodiment of this invention. It is a figure for demonstrating the resistance welding method which concerns on Embodiment 1 of this invention. It is a figure which shows another to-be-welded object for demonstrating the resistance welding method which concerns on Embodiment 2 of this invention. It is a figure for demonstrating the resistance welding method which concerns on Embodiment 2 of this invention. It is a figure which shows the resistance welding apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

W1 ... first workpiece W2 ... second workpiece P ... annular projection A ... area of the second workpiece surrounded by the annular projection V .. -Annular groove Va ... Bottom of annular groove Ta ... Tapered surface of annular groove of workpiece to be welded Tb ... Tapered surface of welding electrode 1 ... Base member 2 ... Support mechanism 3. ··· Pressure mechanism 4 ··· movable block 5 ··· pressure auxiliary member 6 ··· support member 7 · · · upper welding electrode 8 · · · lower welding electrode 9 · · · L-shaped intermediate connection member 10 ... First flexible conductive member 11 ... Second flexible conductive member 12, 13 ... Feeding conductor 14 ... Welding transformer 15 ... Discharge circuit 16 ... Energy storage capacitor 17 ... Charging circuit 60... Width expansion suppressing member 61. Suppression jig 62 ... second suppression jig 63 ... linear motion drive member 63A ... linear motion part of linear motion drive member

Claims (1)

An annular projection formed on a strip-shaped first workpiece or second workpiece made of a different metal material is brought into contact with the second workpiece or the first workpiece, and the first In a state in which the first workpiece and the second workpiece are sandwiched between the first welding electrode and the second welding electrode and pressurized, a pulsed welding current is passed between them to A resistance welding apparatus for welding a workpiece to be welded to the second workpiece to be welded,
The first work piece made of a metal material having a lower melting point than the second work piece has a short width D smaller than three times the annular diameter or the annular width d of the annular projection. And
Respectively in the short width direction at both ends of the strip of the first object to be welded abuts the portion of the short width D of the first object to be welded is plastic flow during welding from spreading in the short width direction A resistance welding apparatus, comprising: a member for suppressing width expansion having a first suppression jig and a second suppression jig for suppressing the above.

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