JP2006082133A - Metal body joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the joining method of metallic bodies by which fine joining state is attained even for metal having high reflectance such as copper, there is no problem that the required time of a joining stage is lengthened and downsizing of a motor including a conductor is attained by reducing the interval between conductors to be joined. <P>SOLUTION: In the joining method of metallic bodies including a stage where brazing filler metal is attached to the joining part of the metallic bodies and the brazing filler metal is irradiated with an electromagnetic wave or an electron beam, the surface of the brazing filler metal is covered with a material having lower reflectance of the electromagnetic wave or the electron beam than that of the brazing filler metal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for joining metal bodies, characterized by using a brazing material and irradiating the brazing material with an electromagnetic wave or an electron beam.

  A drive motor for a hybrid vehicle or a fuel cell vehicle is required to be small and have a high output. In order to reduce the size of the motor, it is preferable that the space between the conductors in the motor and the space required for joining between the conductors is small, and development of a method for reducing these to the minimum is desired.

Conventionally, resistance welding, cold welding, ultrasonic bonding, or the like has been adopted for bonding between conductors such as copper. (Yoshifumi Suezawa, Advanced Welding Engineering, Kyoritsu Shuppan, pages 105-108, pages 154-155, Non-Patent Document 1)
However, in any of these joining methods, it is necessary to directly apply the joined probe to the vicinity of the joined portion. Therefore, it is necessary to have a space for the bonding probe to enter, and it is difficult to reduce the distance between the conductors and reduce the size of the motor.

As a method of joining between conductors such as copper, welding or brazing by irradiation of an electromagnetic wave such as a laser can be considered.
According to welding by electromagnetic wave irradiation, for example, laser welding, since bonding can be achieved by irradiation from a position away from the joint, it is not necessary to apply a joint probe or the like in the vicinity of the joint (indirectness). Moreover, it is also easy to limit the melted part at the time of welding to a narrow range (locality). However, a metal having high electromagnetic wave reflectivity, such as copper, has a problem that it is difficult to heat by electromagnetic wave irradiation and is difficult to melt.

  On the other hand, in the case of brazing, melting of the brazing material is easy, but in order to obtain good bonding, it is necessary to ensure the familiarity (wetting property) between the metal to be bonded and the molten brazing material. For this reason, it is necessary to heat the metal to be bonded over a wide range including the bonded portion, resulting in a problem that the required time for the process becomes longer.

Japanese Patent Application Laid-Open No. 3-155463 (Patent Document 1) discloses a metal made by attaching a brazing material to a joint, and heating and melting the brazing material with an electron beam in a tightly focused state. A method for welding a vacuum vessel is disclosed (claim 1). However, in this method, the joint portion needs to be in a vacuum state, and it has been difficult to apply the joint portion between conductors in a small motor.
JP-A-3-155463 (Claim 1) Suezawa Yoshifumi, “Advanced Welding Engineering”, Kyoritsu Shuppan, June 1, 1988, pp. 105-108, pp. 154-155

  The present invention can achieve a good bonding state for a metal having a high reflectivity with respect to electromagnetic waves or electron beams, such as copper, has no problem of increasing the time required for the bonding process, and reduces the interval between the conductors to be bonded, It is an object of the present invention to provide a metal body joining method that can achieve miniaturization of a motor including the conductor.

The present inventor has focused on the indirectness and locality of welding by electromagnetic wave irradiation and electron beam irradiation, and has found that the above object can be achieved by using these in combination.
The present invention provides, as claim 1 thereof, a method for joining a metal body, comprising a step of attaching a brazing material to a joint portion of the metal body and irradiating the brazing material with an electromagnetic wave or an electron beam, the surface of the brazing material However, the present invention provides a method for joining metal bodies characterized in that the reflectance of electromagnetic waves or electron beams is covered with a material lower than that of the brazing material.

  The metal body joining method of the present invention is characterized in that a brazing material is first attached to the joint portion of the metal body, and the brazing material is irradiated with an electromagnetic wave or an electron beam. Typical examples of the conductor material in the motor include copper and silver. However, since these metals have high reflectivity of electromagnetic waves or electron beams, heating by electromagnetic wave irradiation or electron beam irradiation, for example, melting by laser heating. Is difficult and the welding efficiency is not high. In the present invention, instead of these metals, welding efficiency is improved by irradiating a brazing material having a melting point lower than these metals with an electromagnetic wave or an electron beam, and to the metal base material itself such as copper or silver. Bonding can be obtained more efficiently than irradiation.

  That is, the brazing material is melted by irradiation with electromagnetic waves or electron beams, and covers the joint between the two metal bodies. Moreover, the joint part of the metal which adjoins or adheres to a brazing material is heated by irradiation of electromagnetic waves or an electron beam, and the excellent wettability which enables favorable joining can be obtained. Therefore, when the brazing material covering the joint is solidified, good joining is achieved.

  The metal body joining method of the present invention is further characterized in that the surface of the brazing material is covered with a material having a lower reflectivity of electromagnetic waves or electron beams than the brazing material.

  In the above method, the inventor covers the surface of the brazing material with a material having a lower reflectivity of electromagnetic wave or electron beam than the brazing material, thereby reducing the time required for the joining process and improving the welding efficiency. I found out. This is considered to be because the reflection of electromagnetic waves or electron beams on the surface of the brazing material can be reduced, and the energy amount of electromagnetic waves or electron beams used for heating the brazing material can be increased. For example, when silver brazing is performed by laser irradiation, silver brazing is mainly composed of a metal having a high laser reflectivity, so that a high amount of laser energy is required for melting the brazing material, which increases the time required for the joining process. Although it is likely to occur, this problem can be prevented by covering the surface of the silver solder with a material having a laser reflectance lower than that of the silver solder.

  Examples of a method for covering the surface of the brazing material with a material having a lower reflectivity of electromagnetic wave or electron beam than the brazing material include, for example, a metal having a lower reflectivity of electromagnetic wave or electron beam than that of the brazing material. The method of plating with is mentioned. Claim 2 of the present invention corresponds to this aspect, and is a method for joining the metal bodies, wherein the surface of the brazing material is plated with a metal having a lower electromagnetic wave or electron beam reflectance than the brazing material. The present invention provides a method for joining metal bodies.

The metal whose reflectivity of the electromagnetic wave or electron beam is lower than that of the brazing material is a metal that can be plated on the brazing material, and the preferred type varies depending on the type of brazing material and electromagnetic wave or electron beam used. When a brazing material is silver brazing using a CO ₂ laser or YAG laser that is an electromagnetic wave, tin, chrome, tungsten, nickel, and aluminum are exemplified. Of these, tin is particularly preferable.

  As another method of covering the surface of the brazing material with a material having a lower reflectivity of electromagnetic wave or electron beam than the brazing material, the surface of the brazing material is a paint having a lower reflectivity of electromagnetic wave or electron beam than the brazing material. The method of applying by the method is also exemplified. Claim 3 of the present invention corresponds to this embodiment, and is a method of joining the metal bodies, wherein the surface of the brazing material is applied with a paint having a lower electromagnetic wave or electron beam reflectance than the brazing material. The present invention provides a method for joining metal bodies.

The paint having a lower reflectivity of electromagnetic wave or electron beam than the brazing material is a paint that can be applied onto the brazing material, and the preferred type varies depending on the kind of brazing material and electromagnetic wave or electron beam used. When a CO ₂ laser or YAG laser that is an electromagnetic wave is used and the brazing material is silver brazing, 1,1,1-trichloroethane and the like are exemplified.

  The thickness of the material having a lower electromagnetic wave or electron beam reflectance than the brazing material may be any thickness that prevents reflection of the electromagnetic wave or electron beam from the surface of the brazing material. In the case of using a laser that is, a few μm is sufficient. Further, there may be a part of the brazing material surface that is not covered with a material whose reflectivity of electromagnetic wave or electron beam is lower than that of the brazing material, but sufficient reflection of electromagnetic wave or electron beam from the brazing material. Therefore, it is preferable that all or most of the surface of the brazing material is covered with the material, and it is particularly preferable that the surface of the brazing material is uniformly covered.

  Attaching the brazing material to the joint portion of the metal body means that the brazing material is brought close to and in close contact with the boundary portion of the metal body or the vicinity thereof and the joint portion is covered by melting of the brazing material. (Similar to so-called fillet welding). It is preferable that the brazing material is as close as possible to or close to the joint of the metal body.

  The method for attaching the brazing material to the joint portion of the metal body is not particularly limited. For example, a method of placing small pieces of brazing material along the joint at regular intervals can be employed. However, in this method, when the installation interval of brazing filler metal lumps and the irradiation conditions of electromagnetic waves or electron beams are inappropriate, the molten brazing filler material cannot cover the entire length of the joint, resulting in insufficient joining. is there. Therefore, a method in which the brazing material is formed into a wire shape and the wire is attached along the joint portion is preferable.

  Claim 4 of the present invention corresponds to this preferred embodiment, and provides a method for joining metal bodies, characterized in that the brazing material is wire-shaped. .

  The brazing material includes a solder having a melting point of less than 450 ° C. and a so-called hard solder having a melting point of 450 ° C. or more, but includes any brazing material used in the present invention. By covering the surface of the brazing material with a material having a reflectance of electromagnetic waves or electron beams lower than that of the brazing material, the time required for the joining process can be shortened. However, the effect of the present invention is particularly exerted in the case of a brazing material having a high reflectivity for electromagnetic waves or electron beams, particularly silver brazing. Claim 5 of the present invention corresponds to this aspect, and provides the method for joining metal bodies, wherein the brazing material is silver brazing. .

  As the irradiation of electromagnetic waves or electron beams, laser irradiation that is electromagnetic waves is preferable, and irradiation using a YAG pulse laser is particularly preferable. Claims 6 and 7 of the present invention correspond to this preferred embodiment. That is, claim 6 provides the method for joining metal bodies, wherein the irradiation of electromagnetic waves or electron beams is laser irradiation, and the method for joining metal bodies is characterized in that: 7 further provides a method for joining metal bodies, wherein the laser is a YAG pulse laser. When using a YAG pulse laser, the irradiation energy is preferably about 5 to 100 J.

  According to the method for bonding metal bodies of the present invention, even when a metal having a high electromagnetic wave or electron beam reflectivity such as copper or silver is bonded, an electromagnetic wave or electron beam reflectivity such as silver brazing is further used as a brazing material. Even when a material mainly composed of a high metal is used, a good bonding state can be achieved without a problem that the time required for the bonding process becomes long. In addition, the interval between conductors to be joined can be reduced, and it is not necessary to secure a space necessary for the joining, so that the motor can be reduced in size.

Next, based on an Example, the best form of this invention is demonstrated.
FIG. 1 is a schematic diagram showing an outline of an embodiment of the present invention.
In this example, a wire-like brazing material 4 is attached to a joint 3 where two flat copper wires 1 and 2 intersect. The brazing material 4 is irradiated with laser (electromagnetic waves), and the brazing material 4 is melted.

  The wire-like brazing material 4 is tin-plated with a thickness of 2 μm. It may be plated with another metal having a low laser (electromagnetic wave) reflectivity instead of tin, that is, a laser absorption rate is high, or the brazing material 4 is covered with a paint having a low laser reflectivity instead of metal plating. It may be.

  FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG. 1, and shows that the wire-like brazing material 4 is close to the joint 3. FIG. 3 is a schematic cross-sectional view showing a state after the brazing material 4 is melted. In FIG. 3, a flat copper wire 5 adjacent to the copper wire 2 is also shown.

The amount of the brazing material to be used needs to be equal to or more than the amount that the molten brazing material covers the joint and can be joined by solidification.
On the other hand, when a plurality of joints are formed at a narrow interval, if the amount of the brazing material is large, it melts and the solidified brazing material spreads to the position of the adjacent conductor, which is not preferable. Therefore, the amount of brazing material to be used must be more than an amount that can achieve good bonding and should be in a range where contact with an adjacent conductor does not occur.

  When the brazing material is in the form of a wire, the size of the spread of the molten and solidified brazing material depends on the cross-sectional area of the wire. That is, the cross-sectional area of the brazing material 4 is almost the same before melting (FIG. 2) and after (FIG. 3). Therefore, the length of a in FIG. 3 is defined by the cross-sectional area of the brazing wire. Therefore, a brazing material with a wire cross-sectional area is selected so that a is shorter than the distance between adjacent copper wires (b in FIG. 3), that is, the melting of the brazing material 4 does not spread to the adjacent copper wires. Is done.

  The laser irradiation amount is selected as the irradiation amount necessary for melting the brazing material. By further increasing this irradiation amount, the laser irradiated portion of the metal body is melted, and the deformed portion such as the concave portion or the through hole is removed. It can also be formed. (In this example, a laser is used, but the same applies when another electromagnetic wave or electron beam is used.) In this case, the brazing material has a function as an endothermic agent as well as a function as an adhesive, The deformed portion can be easily formed due to the endothermic property of the brazing material.

  Furthermore, the brazing filler metal in the deformed portion and the brazing material covering the joint are integrated by eluting the brazing material into the deformed portion, preferably filling the deformed portion with the brazing material and then solidifying the brazed material. A strong bond can be obtained. In particular, when the deformed portion is a through hole, so-called through welding can be achieved, and a stronger bond can be obtained. In the penetration welding, the position where the brazing material is attached may be a laser irradiation position that enables penetration welding, and does not necessarily need to be a joint boundary surface.

  FIG. 4 is a schematic sectional view showing an example in which such a deformed portion of the metal body is formed. In this example, the amount of laser irradiation is increased to form a through hole 6 in the metal body, the brazing material 4 is eluted in the through hole 6, and the through hole 6 is filled with the molten brazing material.

  FIG. 5 is a schematic cross-sectional view showing an example in which the peripheral part of the joint part 3 of the metal body is covered with a copper tape 7 as a protective material. In laser irradiation, the joint, that is, the vicinity of the laser irradiation part, is affected by heating by the laser irradiation to some extent, and further causes surface burning due to plasma generation during welding. 7 to prevent those harmful effects. Further, by laser reflection from the copper tape 7, it is possible to increase the laser irradiation efficiency at the joint (3 'in FIG. 5) that receives the laser reflection. Here, the protective material is preferably a tape made of a metal having a high reflectance with respect to a laser such as copper. A thickness of about 200 μm is sufficient. In addition, the method of preventing surface burning using a highly reflective metal tape, and the improvement of irradiation efficiency are the same also when irradiating electromagnetic waves or electron beams other than a laser.

  The metal body joining method of the present invention can be carried out using a metal body joining apparatus comprising an electromagnetic wave or electron beam irradiation means and a brazing material supply means. Here, the brazing material supplying means is means for attaching the brazing material to the metal body to be joined. Since such an apparatus has means for attaching an electromagnetic wave or electron beam irradiation means and a brazing material in one apparatus, the metal body joining method of the present invention can be easily performed by using this means. it can.

  FIG. 6 is a perspective view showing an example of a metal body joining apparatus used in the practice of the present invention. This apparatus comprises a brazing filler wire feeder A and a laser irradiation means B, and a joining portion where two flat copper wires 1 and 2 intersect is joined by this apparatus. That is, first, a wire-like brazing material (brazing material wire 8) is supplied from the brazing material wire feeder A as shown in the figure, and the brazing material wire feeder A moves in the direction of the arrow in FIG. The brazing wire 8 is attached to the joint. The brazing wire 8 attached is melted by laser irradiation by the laser irradiation means B. The laser irradiation means B moves integrally with the brazing wire feeder A in the direction of the arrow in FIG. The molten brazing material 9 is then cured and the copper wires 1 and 2 are joined.

  The motor manufactured by the metal body joining method of the present invention is suitably used as a small motor for a vehicle driven by a motor such as a hybrid vehicle or a fuel cell vehicle.

It is the schematic which shows the outline | summary of an example of this invention. It is a schematic sectional drawing of the AA part of FIG. It is a schematic sectional drawing which shows the state after the brazing material 4 was fuse | melted. It is a schematic sectional drawing which shows the outline | summary of the other example of this invention. It is a schematic sectional drawing which shows the outline | summary of the other example of this invention. It is a perspective view which shows an example of the metal body joining apparatus used for implementation of this invention.

Explanation of symbols

1, 2, 5 Copper wire 3 Joint 4 Brazing material 6 Through hole 7 Copper tape 8 Brazing material wire 9 Melted brazing material A Brazing material wire feeder B Laser irradiation means

Claims (7)

  A method of joining a metal body including a step of attaching a brazing material to a joint portion of a metal body and irradiating the brazing material with an electromagnetic wave or an electron beam, wherein the surface of the brazing material has an electromagnetic wave or electron beam reflectivity. A metal body joining method characterized by being covered with a material lower than the brazing material.   2. The method for joining metal bodies according to claim 1, wherein the surface of the brazing material is plated with a metal having a lower reflectivity of electromagnetic waves or electron beams than the brazing material.   2. The method for joining metal bodies according to claim 1, wherein the surface of the brazing material is coated with a paint having a lower reflectivity of electromagnetic waves or electron beams than the brazing material.   The metal brazing method according to any one of claims 1 to 3, wherein the brazing material has a wire shape.   The method for joining metal bodies according to any one of claims 1 to 4, wherein the brazing material is silver brazing.   6. The method for joining metal bodies according to claim 1, wherein the irradiation with electromagnetic waves or electron beams is laser irradiation. 7. The method for joining metal bodies according to claim 6, wherein the laser is a YAG pulse laser.

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