JP3626085B2 - Projection-to-projection diffusion bonding method and welded article - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a projection butt diffusion bonding method for a welded article made of aluminum, magnesium, or an alloy thereof, and a welded article.
[0002]
[Prior art]
In general, an aluminum material or an alloy thereof is often resistance-welded. For example, the method described in Japanese Patent Application Laid-Open No. 10-193132 is spot welding in which an alternating current is passed between aluminum materials or alloys thereof for a certain cycle to form a nugget in a welded portion, and spot welding is performed. Therefore, there is a feature that no defect caused by thermal stress is generated around the weld nugget portion. Japanese Patent Laid-Open No. 9-38782 discloses a method in which an insert material made of a specific metal powder is interposed between aluminum materials to be welded, and resistance spot welding is performed at a low current. Further, JP-A-8-39265 discloses a similar spot welding method for aluminum alloy.
[0003]
[Problems to be solved by the invention]
All of these are spot welds, and an appropriate projection is generally formed only on one of the aluminum materials or alloys thereof to be welded, and the welding current is concentrated on the projection and the vicinity thereof, so that Welding was performed by melting an aluminum material or an alloy thereof to form a nugget. However, in the case of such resistance spot welding, a pretreatment is required to remove the oxide film formed on the contact surface between one work piece and the other work piece. In addition, there is a case where it is regarded as a problem in appearance in order to form a nugget.
[0004]
It is an object of the present invention to eliminate such problems in the prior art, and pressurizes the projections formed on both of the objects to be welded together so that the tops of the projections are in contact with each other. This is a new high-quality projection that does not require pre-treatment or post-treatment without forming a nugget by extruding the oxide film and dirt sandwiched by the joint surface at the top of the projection to the periphery. It is an object to provide a butt-diffusion diffusion bonding method.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the first invention is the method of diffusion bonding the first and second articles to be welded, wherein at least one of the first and second is made of aluminum, magnesium, or an alloy thereof. Each of the articles to be welded has a projection and an surrounding wall on the inner surface side lower than the height of the projection , each of which includes an annular or ring-shaped groove formed by the projection and the surrounding wall, The tops of the projections formed on both of the first and second articles to be welded are pressed against each other and pressurized, and in the pressurized state, the electric energy stored in the energy storage capacitor is reduced to 30 ms or less in a short time. by releasing, the pulsed current first, flow between the projection of the second welded article Wherein said top projection and is plastically fluidize the vicinity thereof, thereby characterized Rukoto confined oxide film and dirt sandwiched the bonding surface of said top portion of said projection in said groove extruded from the joint surface Te A projection-to-projection diffusion bonding method is provided.
[0006]
Further, according to the second invention, in the first invention or the second invention , at the time of diffusion bonding , one top surface of the surrounding wall is equal to or lower than a top surface of the other surrounding wall. the Rukoto caused to enter into the groove of the other party to be in, to provide a projection between butt diffusion bonding method characterized by confining the protruding portion to be pushed out from the joining portion between the dust and the projection generated in the groove.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG. In FIG. 1A, 1 is a first work piece positioned on the upper side, 2 is a second work piece located on the lower side, and these are made of aluminum, magnesium, or an alloy thereof. It is a metal material. The first and second workpieces 1 and 2 have projections 1a and 2a each having a trapezoidal cross section. The projections 1a and 2a are annular, that is, ring-shaped, and are formed in a virtual circle shape having the same diameter. The first and second workpieces 1 and 2 are disposed between the upper electrode 3 and the lower electrode 4 so that the top surface 1b of the projection 1a and the top surface 2b of the projection 2a are abutted with each other. In addition, in FIG. 1, the cross section of each of these members is shown.
[0013]
In this state, a downward pressing force is applied to the upper electrode 3 by a pressurizing mechanism (not shown), and between the first and second workpieces 1 and 2, that is, the top surface 1 b of the projection 1 a and the projection 2 a. A predetermined pressing force is applied to the top surface 2b. In this state, electric energy stored in an energy storage capacitor of a general power supply device (not shown) is released in a short time, and a pulsed current is passed between the top surface 1b of the projection 1a and the top surface 2b of the projection 2a. Shed. This pulsed current is smaller than the current peak value or current amount enough to melt the projections 1a and 2a and the metal material in the vicinity thereof to form a nugget as in the spot welding described above, and the top of the projection 1a and the projection 2a. And a short pulse width that raises the metal to a temperature that causes the metal to flow plastically below its melting point.
[0014]
By passing a pulsed current having such a short time width, for example, a pulse width of 30 ms or less, preferably 15 ms or less, the top of the projection 1a, the top of the projection 2a, and the metal in the vicinity thereof are deformed by plastic flow. Since the oxide film on the contact surface is destroyed and the broken oxide film or foreign matter is pushed out of the joint portion with the deformation, the oxide film or the foreign matter is not formed on the final joint surface between the projection 1a and the projection 2a. It becomes the joint surface by the metal material of the 1st and 2nd to-be-welded objects 1 and 2 in which a foreign material does not exist, diffusion of electrons between metal materials is promoted, and high-quality diffusion bonding with strong mechanical bonding force is obtained. .
[0015]
According to such projection-to-projection diffusion bonding, the joint metal centering on the top surface 1b of both projections 1a and the top surface 2b of the projection 2a is deformed by plastic flow and pushed outward. Since there is no oxide film or foreign matter on the joint surface between the top surface 1b of the final projection 1a and the top surface 2b of the projection 2a, a spot where a projection is formed only on one of the objects to be welded as in the prior art. Compared to welding or the like, post-processing such as pre-processing for removing oxide films and foreign matters and clean-up of the appearance are not required. In addition, since no nugget is formed and only the projection is heated substantially, the thermal distortion is very small, and a welded product with high dimensional accuracy is obtained, and the temperature of the welded product does not increase, so it can be touched immediately, It is also possible to take it out.
[0016]
Next, FIG. 1B shows another embodiment of the projection, and the projection 1a or 2a of the workpiece 1 or 2 has a semicircular cross section in the case of the ring projection, and the workpiece 1 or 2 is welded. In the case of multi-projection in which a large number of projections are formed, a hemispherical shape is obtained. The semicircular shape and the hemispherical shape referred to here indicate including a part of a circle or a spherical surface. Another embodiment of the projection shown in FIG. 1C has a U-shaped cross section in the case of ring projection, and a rectangular body extending from the surface of the projection 1a or 2a in the case of multi-projection. The projections 1a and 2a of the workpieces 1 and 2 do not necessarily have the same size and shape, and may be a combination of projections having the shapes shown in FIGS. 1A to 1C or projections having other shapes. .
[0017]
【Example】
An embodiment of the projection butt diffusion bonding method according to the present invention will be described with reference to FIGS. 2 and 3 show cross sections of the workpieces 1 and 2, the upper electrode 3, and the lower electrode 4. In this embodiment, annular tapered surfaces 1A and 2A are formed at one end of each of the cylindrical rod-shaped workpieces 1 and 2, and each end has a larger diameter than the other portions. It is part 1B, 2B. Ring projections 1a and 2a each having a trapezoidal cross section are formed on the end faces of the large-diameter portions 1B and 2B that face each other, and an annular surrounding wall 1c that is lower in height than the ring projections 1a and 2a is formed on the inner and outer sides thereof. 1d, annular surrounding walls 2c and 2d are formed. Annular grooves 1e and 1f are formed between the ring projection 1a and the inner and outer enclosure walls 1c and 1d, respectively, and between the ring projection 2a and the inner and outer enclosure walls 2c and 2d. Are formed with annular grooves 2e and 2f, respectively. The surrounding walls 1c and 1d and the surrounding walls 2c and 2d are crushed by the plastic flow of the ring projections 1a and 2a at the time of diffusion bonding, so that the ring projections 1a and 2a are crushed around the joint surface. As shown, the protruding portions 1g and 2g pushed out to the periphery perform a function of confining them in the grooves 1e and 2e and the grooves 1f and 2f.
[0018]
Further, the upper electrode 3 and the lower electrode 4 have annular tapered surfaces 3A and 4A that match the respective annular tapered surfaces 1A and 2A of the workpieces 1 and 2 along their inner peripheral surfaces. The upper electrode 3 and the lower electrode 4 apply pressure to the annular tapered surfaces 1A and 2A of the workpieces 1 and 2 through the tapered surfaces 3A and 4A, and apply a pulsed current. When a pulsating current flows between the upper electrode 3 and the lower electrode 4, the pulsating current flows through the joint surfaces 1b and 2b of the projections 1a and 2a, and the joint generates heat due to the resistance, and instantly plastic fluidizes. To do. The pulsed current at this time varies depending on the junction area between the projections 1a and 2a, but has a current peak value and a pulse width immediately before the nugget is formed, and the pulse width is, for example, 30 ms or less, preferably 15 ms or less. is there.
[0019]
As described above, as the joint portion of the projections 1a and 2a plastically fluidizes, the portion including the joint surfaces 1b and 2b of the plastic fluidized projections 1a and 2a as shown in FIG. However, the surrounding walls 1c and 1d of the work piece 1 and the front end surfaces of the surrounding walls 2c and 2d of the work piece 2 come into contact with each other, and the projections 1a and 2a and the grooves 1e and 1f and the grooves 2e and 2f are formed. It becomes a form of confinement. Therefore, dust generated from the joint portion during diffusion bonding and the extruded portions 1g and 2g can be confined, and adverse effects due to dust can be prevented, and at the same time, the appearance of the joint portion can be made clean.
[0020]
In order to realize such projection-to-projection butt diffusion bonding, the upper electrode 3 or the lower electrode 4 needs to respond at a high speed to the instantaneous plastic fluidization of the joint portions of the projections 1a and 2a. Therefore, in carrying out this method, a device having a structure as disclosed in Japanese Patent Application Laid-Open No. 8-118040 is used, and the upper electrode 3 responds at high speed using the elastic force of the spring. . Due to the high-speed response of the upper electrode 3, good projection-to-projection diffusion bonding can be performed, and dust generated in the diffusion bonding and extruded protrusions 1g and 2g can be confined.
[0021]
Next, FIG. 4 shows that the annular surrounding wall 1c of the first workpiece 1 such as an aluminum metal pipe is formed into the annular shape of the second workpiece 2 such as an aluminum metal plate at the time of projection-to-projection diffusion bonding. The inner diameter of the annular surrounding wall 1c is larger than the diameter of the annular surrounding wall surface 2c ′ of the second workpiece 2 so as to enter the groove 2e (shown by a chain line), and the outer diameter of the annular surrounding wall 1d. Shows an embodiment in which the diameter is smaller than the diameter of the annular surrounding wall surface 2d 'of the work piece 2. The surrounding wall surface 2c ′ and the surrounding wall surface 2d ′ of the second workpiece 2 are formed so as to be substantially perpendicular to the surface of the workpiece 2 by forming annular grooves 2e and 2f on the inner surface side and outer surface side of the projection 2a. It extends in the thickness direction. Since the relationship between the projections 1a and 2a is the same as that in the above-described embodiment, description thereof is omitted. In this embodiment, the projection 2a and the annular groove 2e of the second workpiece 2 are formed by press molding. FIG. 4 shows a cross section of the first and second workpieces 1 and 2.
[0022]
Extruded portions and dust generated due to plastic flow of the joint between the projections 1a and 2a during the diffusion bonding are the same as in the previous embodiment. The annular surrounding wall 1c, the annular surrounding wall 2c ', and the annular surrounding wall It is confined by 1d and the annular surrounding wall surface 2d ′ and does not leak to the outside.
[0023]
FIG. 5 shows another embodiment of the projection-to-projection diffusion bonding method according to the present invention. The first and second workpieces 1 and 2 that are aluminum pipes are third welded pieces that are aluminum discs. This is an example of joining through the object 5. FIG. 5 shows a cross section of a part of these workpieces 1, 2 and 5. The third workpiece 5 includes an annular projection 5a corresponding to the annular projection 1a of the first workpiece 1, and an annular projection 5a ′ corresponding to the annular projection 2a of the second workpiece 2. Have The projection 1a and the projection 5a are abutted, and the projection 2a and the projection 5a ′ are abutted. In this embodiment, the surrounding walls 1d and 2d are provided only on the outer surface side of the first and second workpieces 1 and 2 and the surrounding wall is not provided on the inner surface side. The surrounding walls 1d and 2d of the first and second workpieces 1 and 2 cooperated with the surrounding wall surfaces 5c ′ and 5d ′ of the third workpiece 5 to cause dust and the like generated during diffusion bonding to be extruded. Enclose the protruding part. On the inner surface side, if dust generated at the time of diffusion bonding does not become a problem, the surrounding wall is unnecessary.
[0024]
In this embodiment, the first and second objects to be welded 1 and 2 are described as aluminum pipes, and the third object to be welded 5 is described as an aluminum disk. However, other conductive materials such as magnesium or their alloys are used. Diffusion bonding is possible even with a good metal material, and projection-to-projection diffusion bonding is similarly performed even if these workpieces are not pipes or metal plates, but are rods or rods and pipes or metal plates. be able to. If dust is a problem on the inner surface side of the work piece, an enclosing wall or an enclosing wall surface may be provided only on the inner surface side.
[0025]
【The invention's effect】
As described above, the projection-to-projection butt diffusion bonding according to the present invention has the following effects.
(1) Diffusion bonding with good quality such as aluminum, magnesium, or alloys thereof is possible.
(2) Since the oxide film and dirt on the joint surface at the top of both projections are pushed out from the joint surface during diffusion joining, pretreatment such as pickling is unnecessary.
(3) Since no nugget is formed in the weld as in spot welding, there is almost no thermal distortion, and in particular, when a metal plate is subjected to multi-projection diffusion bonding, the appearance is beautiful and no post-treatment is required.
(4) Since an electric current is passed through both projections and the projections are diffusion-bonded to each other, the amount of current is small compared to spot welding and the like, which is excellent in economic efficiency.
(5) Since both projections are instantly diffusion-bonded together, the temperature of the weldment hardly rises, it is possible to perform the joining work even with a bare hand supported, and the joining process can be taken out immediately. .
(6) Furthermore, since the shape of the article to be welded according to claims 2 to 4 has an enclosing wall or an enclosing wall surface, it always generates dust during welding or diffusion bonding, or plasticity during bonding. The flowing metal can be confined in the metal material constituting the article to be welded, and adverse effects due to dust can be prevented, and at the same time a clean appearance can be maintained.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an embodiment of projection-to-projection diffusion bonding according to the present invention.
FIG. 2 is a diagram for explaining an embodiment of the present invention.
FIG. 3 is a diagram for explaining an embodiment of the present invention.
FIG. 4 is a diagram for explaining another embodiment of the present invention.
FIG. 5 is a diagram for explaining still another embodiment of the present invention.
[Explanation of symbols]
1. 1st work piece 1a .. Projection 1c, 1d .. Enclosure wall 1e, 1f .. Groove 1A .. Annular taper surface 2. .. Second work piece 2a .. Projection 2c, 2d. · Enclosure walls 2e, 2f · · Groove 2A · · Annular taper surface 3 · · Upper electrode 4 · · Lower electrode 5 · · Third workpiece 5a, 5a '· · Projection 5c', 5d '· · Enclosure Wall

Claims (2)

In the method of diffusion bonding the first and second articles to be welded,
Each of the first and second welded articles, at least one of which is made of aluminum, magnesium, or an alloy thereof, has a projection and an surrounding wall on the inner surface side that is lower than the height of the projection,
An annular or annular groove formed by the projection and the surrounding wall;
The tops of the projections formed on both the first and second articles to be welded are pressed against each other and pressurized, and in the pressurized state, the electrical energy stored in the energy storage capacitor is short for 30 ms or less. , A pulsed current is caused to flow between the projections of the first and second articles to be welded to plastically fluidize the top portion of the projection and the vicinity thereof, and thereby the top portion of the projection. projection each other butt diffusion bonding wherein the Rukoto confined in the groove of the oxide film and dirt sandwiched bonding surface extruding from the joint surface. In claim 1,
During the diffusion bonding, by Rukoto caused to enter into the groove of the other party so that one top surface of the surrounding wall below the other of the surrounding top surface of the wall and the equivalent or lower levels, dust and the projection between generated projection each other butt diffusion bonding method characterized by confining the protruding portion to be pushed out from the joining portion to the groove.

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