JP2017123318A - Method for manufacturing heterogeneous conductive member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive member having high strength and conductivity and high degree of freedom of layout of members when manufacturing heterogeneous conductive members such as bus bars by abutting an aluminum member and a copper member and laser-welding them.SOLUTION: An aluminum member 1 and a copper member 2 are abutted against each other, and an abutted portion is irradiated with a laser beam 5 while moving the laser beam along the abutted portion, and the aluminum member 1 and the copper member 2 are laser-welded. During the laser welding, the laser beam 5 is moved a plurality of times along the abutted portion to melt an end portion of the aluminum member 1 to form a linear fused portion 6 along the abutted portion, and the aluminum member 1 and the copper member 2 are pressed in the abutting direction, and the fused portion 6 is caused to flow outside the abutted portion. After the laser welding, the burr 8 formed outside the abutted portion is removed.SELECTED DRAWING: Figure 1

Description

   The present invention relates to a method of manufacturing a dissimilar conductive member such as a bus bar used for connecting electronic / electrical parts by abutting and welding an aluminum member and a copper member.

Capacitor devices used in vehicles such as hybrid vehicles and electric vehicles repeatedly charge and discharge, so electrodes are provided on capacitor elements wound in a spiral shape, and the electrodes are connected by a bus bar that is a conductive member. doing. Conventionally, a copper material (pure copper or copper alloy) has been used for such a conductive member in order to ensure high conductivity.
However, in recent years, it has been required to reduce the weight of automobiles in order to realize environmental reductions and reduce exhaust gas. For this reason, particularly in conductive members such as terminal connectors and bus bars, attempts have been made to reduce the weight by replacing part or all of the heavy copper material with aluminum material (pure aluminum or aluminum alloy).

For example, Patent Document 1 describes a method of manufacturing a different conductive member by overlapping and joining ends of a first metal plate (copper material) and a second metal plate (aluminum material). Specifically, a convex crest and a concave trough are formed at the ends of the first and second metal plates, respectively, and the crest and trough are overlapped with the ends of the first and second metal plates. And the overlapped portion is rolled and pressed with a pair of upper and lower rolls, and diffusion-annealed to join the first and second metal plates.
Patent Document 2 describes that end portions of an aluminum member and a copper member are butted together, and the butted portion is laser-welded to manufacture a dissimilar conductive member. At the time of laser welding, the center position of the laser beam is offset from the butt line to the aluminum member side so that the irradiation area of the laser beam on the aluminum member is larger than the irradiation area of the copper member.

Patent Document 3 describes that a copper material and an aluminum material are brought into surface contact and are extruded and joined in an ultrahigh hydrostatic pressure environment to produce a different conductive member (bus bar). Further, it is described that the copper material and the aluminum material are metallicly bonded by an extrusion process under an ultra-high hydrostatic pressure environment.
Patent Document 4 describes that aluminum materials having different alloy systems (1000 series and 6000 series) are friction stir welded and integrated to manufacture a dissimilar conductive member (bus bar).

Japanese Patent Laid-Open No. 2008-6696 JP2011-5499A JP 2011-210480 A Japanese Patent Laying-Open No. 2015-15211

The manufacturing method of the dissimilar conductive member described in Patent Document 1 requires time since the end surfaces of the first metal plate and the second metal plate need to be processed in advance, and the first and second metal plates depend on the width of the rolling stand. The width of is limited. Moreover, when there is a difference in plate thickness between the first and second metal plates, there is a problem that press contact is difficult.
In the method of manufacturing a different conductive member described in Patent Document 2, a binary intermetallic compound of copper and aluminum is formed in a laser welded portion, thereby preventing electrical conduction between the copper member and the aluminum member. The bonding strength between the copper member and the aluminum member may be reduced.

The manufacturing method of the different electroconductive member described in patent document 3 is considered that high electroconductivity is acquired because the copper material and the aluminum material are carrying out the metallic connection. However, since the extrusion shape is restricted by the shape of the die hole, the degree of freedom in designing the shape of the different conductive member is restricted.
In the manufacturing method of the dissimilar conductive member described in Patent Document 4, since aluminum materials having different alloy systems are joined by friction stir welding, the strength as a joined body can be obtained, but the aluminum materials have a metallic bond. Not done. For this reason, the dissimilar conductive member joined by friction stir welding has a problem that sufficient conductivity for use as a bus bar cannot be secured.

  In the case of manufacturing a different conductive member such as a bus bar by joining an aluminum member and a copper member, the present invention can ensure the strength as the conductive member, has high conductivity, and has a high degree of freedom in layout of the member. An object is to provide a member.

According to the present invention, an aluminum member and a copper member are abutted, a laser beam is irradiated to the abutting portion while being moved (scanned) along the abutting portion, and the aluminum member and the copper member are laser-welded to manufacture a different conductive member. In the method, at the time of laser welding, the laser beam is moved a plurality of times along the abutting portion, an end portion of the aluminum member is melted to form a linear melted portion along the abutting portion, and the aluminum member And the copper member are pressed against each other in the abutting direction, the material of the melted portion is caused to flow outside the abutting portion, and burrs formed outside the abutting portion after laser welding are removed.
In the present invention, an aluminum member means a member made of pure aluminum or an aluminum alloy, and a copper member means a member made of pure copper or a copper alloy.
In the manufacturing method, the laser beam may be reciprocated once or more along the abutting portion, or may be moved a plurality of times only in one direction.
In the manufacturing method, the aluminum member and the copper member may be pressed while forming the melted portion, or may be pressed after forming the melted portion.
In the said manufacturing method, it is preferable to make the plate | board thickness of an aluminum member thicker than the plate | board thickness of a copper member.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method (laser welding method) of a different electroconductive member with high electroconductivity and a high freedom degree of member layout can be provided, ensuring the intensity | strength as electroconductive members, such as a bus bar. The dissimilar conductive member obtained by the production method of the present invention is obtained by laser welding an aluminum member and a copper member, and can be suitably used as a conductive member such as an in-vehicle battery unit and a bus bar for electrical connection of a capacitor.

It is a perspective view which shows the outline | summary of the manufacturing method of this invention. It is a top view which shows the outline | summary of the manufacturing method of this invention. It is a schematic diagram which shows the plate | board thickness direction cross section of the laser weld part (at the time of fusion | melting part formation) by the manufacturing method of this invention. It is a schematic diagram which shows the plate | board thickness direction cross section of the laser welding part (at the time of a fusion | melting part flow) by the manufacturing method of this invention. It is a schematic diagram which shows the plate | board thickness direction cross section of the laser welding part (at the time of solidification) by the manufacturing method of this invention. It is a schematic diagram which shows one Embodiment of the manufacturing method of this invention. It is a schematic diagram which shows other embodiment of the manufacturing method of this invention. It is plate | board thickness direction sectional drawing (micrograph) of the laser welding part by the manufacturing method (1 pass welding) of a comparative example. It is plate | board thickness direction sectional drawing (micrograph) of the laser welding part by the manufacturing method (3 pass welding) of this invention. It is plate | board thickness direction sectional drawing (micrograph) of another laser welding part by the manufacturing method (3 pass welding) of this invention. In this example, the copper member and the aluminum member have different plate thicknesses.

Hereinafter, with reference to FIG. 1 to FIG. 5C, the method for manufacturing the different type conductive member according to the present invention will be described more specifically. Note that the present invention is not limited to the embodiments described below.
As shown in FIGS. 1 and 2, in the manufacturing method of the present invention, the aluminum member (aluminum plate) 1 and the copper member (copper plate) 2 constitute a butt joint in a state where the end surfaces are butted against each other (butting line 3). . In the joint portion, the aluminum member 1 and the copper member 2 are pressed in the butting direction, and laser welding is performed in this state.
In FIG. 1, reference numeral 4 denotes a galvano head of a scanner laser apparatus, which includes a galvano mirror inside and irradiates the abutting portion while moving (scanning) the laser beam 5 along the abutting portion (abutting line 3). In the present invention, when one movement (scanning) of the laser beam is one pass, a plurality of passes are performed in the present invention. The laser beam 5 may be reciprocated once or more along the abutting portion in the irradiated state (two reciprocations for two passes), or may be moved a plurality of times only in one direction. In FIG. 2, the moving direction of the laser beam 5 in the latter case is indicated by an arrow. When the laser beam 5 moves a plurality of times in the direction of the arrow (or in the opposite direction), the end of the aluminum member 1 is melted over the entire region in the plate width direction at the butt portion, and linear melting occurs. Part is formed.

Most of the metal melted in the melting part is aluminum, but depending on the heat input, a small amount of copper melts. As shown in FIG. 3A, the melting part 6 includes an aluminum melting area 6a existing on the aluminum member 1 side and a mixing area 6b existing at the boundary between the copper member 2 and the aluminum melting area 6a. The mixed region 6b is a region where copper is dissolved in molten aluminum, and an Al—Cu binary intermetallic compound is formed in a film shape at the end of the mixed region 6b on the copper member 2 side.
In addition, in the dissimilar conductive member in which the aluminum member 1 and the copper member 2 are welded, if the Al—Cu binary intermetallic compound layer is present between the members 1 and 2, the aluminum member 1 and the copper member 2 The electrical continuity is inhibited. In addition, the presence of a thick Al—Cu binary intermetallic compound layer significantly reduces the bonding strength between the aluminum member 1 and the copper member 2. A conductive member such as a bus bar is bent or the like, and therefore requires a predetermined bonding strength. For this reason, it is desirable to eliminate as much as possible the Al—Cu binary intermetallic compound present in the melting part 6.

Since the aluminum member 1 and the copper member 2 are pressed in the abutting direction, as shown in FIG. 3B, the material of the melting part 6 (the aluminum melting area 6a and the mixing area 6b) flows out of the abutting part (extruded). ). As the molten part 6 flows, the Al—Cu binary intermetallic compound generated at the end of the mixing zone 6 b is also pushed out of the butt part and eliminated.
Subsequently, when the irradiation of the laser beam 5 is stopped, as shown in FIG. 3C, the material of the melted portion 6 existing at the butt portion immediately solidifies to become the weld metal 7 and is pushed out of the butt portion. The resulting material is also solidified to form burrs 8. FIG. 3C schematically shows a state in which most of the material of the melted part 6 is eliminated and the aluminum member 1 and the copper member 2 are joined via the weld metal 7 having a very thin thickness.
In addition, since the Al-Cu binary intermetallic compound is formed when the material of the mixing zone 6b (molten aluminum containing copper) is solidified, the material of the mixing zone 6b can be excluded from the butt portion as much as possible. preferable.

According to the laser welding method, after laser welding, the Al—Cu binary intermetallic compound layer is not formed at the butt portion of the aluminum member 1 and the copper member 2, and even if formed, the layer remains very thin. . This is presumed to be because when the molten part 6 flows, all or most of the material in the mixing zone 6b is pushed out of the butted part. As a result, the aluminum member 1 and the copper member 2 can be joined metallically via the weld metal at the butted surfaces, and good electrical conductivity and joint strength can be obtained.
In addition, when the plate | board thickness of the aluminum member 1 is thicker than the copper member 2, since the aluminum member 1 will fuse | melt much and the quantity of the metal pushed out of a butt | matching part will increase, the discharge | emission of the material of the mixing zone 6b is more effective. Can be done automatically.
After the laser welding, the material (flash 8) pushed out of the abutting portion can be removed with a cutter or the like to obtain a different conductive member.

The type of the laser beam 5 emitted from the scanner laser device is not particularly limited, and a YAG laser, a CO ₂ laser, a fiber laser, a disk laser, a semiconductor laser, or the like can be used. The beam diameter (diameter) of the laser beam 5 is not particularly limited and can be appropriately changed, but is preferably in the range of 0.1 to 0.6 mm. The output of the laser beam 5 is not particularly limited as long as the aluminum member 1 can be melted linearly. In order to form a so-called penetrating bead at the butted portion, the laser beam output is preferably 2000 W or more, more preferably 10 kW or more, and the moving speed of the beam is preferably 10 m / min or more, and more preferably 50 m / min or more.
The laser beam welding may be keyhole welding or may be performed by so-called heat conduction type beam welding by defocusing and irradiating the laser beam, but keyhole welding is preferable.

  The center of the laser beam 5 may coincide with the abutting portion (butting line 3) of the aluminum member 1 and the copper member 2, and as described in Patent Document 2, it is shifted to the aluminum member 1 side (offset). ). In the latter case, the amount of heat supplied to the aluminum member 1 is increased, and the generation of highly brittle Al—Cu binary intermetallic compounds can be reduced. A preferred offset amount (distance between the center of the laser beam 5 and the butt line 3) is d / D × 100 = 10 to 45 (%) where D is the beam diameter and d is the offset amount.

When pressing the aluminum member 1 and the copper member 2 in the butting direction, it is necessary to press both the members 1 and 2 uniformly over the entire width. For that purpose, the end of the aluminum member 1 is linearly formed along the butting line 3. It is necessary to melt and form the linear melted part 6 with the full width.
Since the aluminum member 1 and the copper member 2 have high thermal conductivity, the solidification of the molten part 6 in contact with both members starts immediately after the laser beam 5 passes. For this reason, when only one pass of the laser beam 5 is scanned, the melted state in the width direction varies. In that case, the molten part and the solidified part are mixed in the width direction, and it is difficult to press the aluminum member 1 and the copper member 2 uniformly in the width direction, and the material of the mixed zone 6b (molten aluminum containing copper and The aluminum Al—Cu binary intermetallic compound) cannot be discharged well.

On the other hand, when the linear melted portion 6 along the butt line 3 is formed by performing a plurality of passes of scanning of the laser beam 5 on the butt portion, both members 1 and 2 can be pressed with a uniform force over the entire width. . Specifically, the laser beam 5 is reciprocated once or more along the abutting portion (abutting line 3) between the aluminum member 1 and the copper member 2, or is repeatedly moved in one direction a plurality of times. Thereby, the linear fusion | melting part 6 can be formed along the butt | matching line 3, and the discharge | emission of the material of the mixing zone 6b can be performed smoothly from the butt | matching part of both the members 1 and 2. FIG.
In the case where the aluminum member 1 and the copper member 2 are wide, a plurality of scanner laser devices can be arranged along the width direction, thereby forming the linear melted portion 6.

In the laser welding method described above, the aluminum member 1 and the copper member 2 are pressed in the abutting direction before irradiation with the laser beam 5, and the laser beam 5 is irradiated in this state to form a linear melting portion 6 along the butting line 3. Was forming. In this case, the formation of the molten portion 6 and the flow of the material of the molten portion 6 (discharge from the butt portion) proceed substantially in parallel, and when irradiation with the laser beam 5 is stopped, the molten aluminum remaining in the butt portion is solidified. Begins immediately.
On the other hand, after irradiating the laser beam 5 to form the linear melted portion 6, the aluminum member 1 and the copper member 2 can be pressed in the butting direction so that the material of the melted portion 6 can flow (discharge from the butted portion). . The irradiation of the laser beam 5 can be stopped at an appropriate timing, for example, immediately before the aluminum member 1 and the copper member 2 are pressed together. Also in this case, the material of the mixing zone 6b is excluded from the abutting portion, and the Al—Cu binary intermetallic compound layer is not formed in the abutting portion of the aluminum member 1 and the copper member 2, but is temporarily formed. But it stays in a very thin layer.

  The aluminum member 1 is made of pure aluminum or an aluminum alloy. As pure aluminum, JISA1000 series or the like can be used, and among them, A1050 having high workability is preferable. Aluminum alloys include JIS A2000 (Al-Cu alloy), JIS A3000 (Al-Mn alloy), JIS A4000 (Al-Si alloy), JIS A5000 (Al-Mg alloy), JIS. A6000 series (Al-Mg-Si based alloy), JIS A7000 series (Al-Zn-Mg based alloy, Al-Zn-Mg-Cu based alloy) and the like can be used, and among them, the conductivity is excellent. JISA6101 is preferred.

The copper member 2 is made of pure copper or a copper alloy. As pure copper, for example, OFC (Oxygen-Free Copper / oxygen-free copper), tough pitch copper, phosphorous deoxidized copper, or the like can be used. As the copper alloy, for example, a Cu-Fe-P system, a Cu-Ni-Si (Corson alloy) system, or the like can be used.
The material of the aluminum member 1 and the copper member 2 may be a bare material that has not been surface-treated, or a material that has been subjected to surface treatment such as Sn plating, electroplating such as zinc plating, or zinc spraying. May be.

An example of a specific method when the aluminum member 1 and the copper member 2 are butted and laser-welded will be described with reference to FIGS. 4A and 4B.
In the method shown in FIG. 4A, both the aluminum member 1 and the copper member 2 are abutted in a flat plate state. The aluminum member 1 is sandwiched between a pair of pinch rolls 11 and 11, and the copper member 2 is sandwiched between pinch rolls 12 and 12. The laser beam 5 is reciprocated along the abutting portion, and the pinch rolls 11, 11, 12, and 12 are operated while the linear melted portion 6 is formed in the abutting portion, so that the aluminum member 1 and the copper member 2 are abutted. Then, the irradiation with the laser beam 5 is stopped.

In the method shown in FIG. 4B, the aluminum member 1 and the copper member 2 which are both plate materials are temporarily fixed (temporary fixing portion 13), bent into a pipe shape, and then moved forward by the drum-shaped squeeze rolls 14 and 14. However, the end portions are butted together, and the laser beam 5 is reciprocated along the butted portion. A linear melted portion 6 is formed along the abutting portion, and both members 1 and 2 are pressed against each other by the squeeze rolls 14 and 14 and move forward in that state. After laser welding, the temporary fixing portion 13 is released, and the pipe shape is formed (bent back), for example, from a pipe shape as necessary.
In addition, when the width W (refer FIG. 4A) of the aluminum member 1 and the copper member 2 is narrow, also by the method shown to FIG. 4A, the fusion | melting part 6 is formed uniformly in the width direction, and both the members 1 and 2 are made into the width direction. Can be pressed uniformly along. However, when both the members 1 and 2 are wider, the method shown in FIG. 4B can press both the members 1 and 2 more uniformly along the width direction.

EXAMPLES Hereinafter, the Example of the manufacturing method of the dissimilar electrically conductive member based on this invention is shown, and this invention is demonstrated still in detail. In addition, the Example described below is only an example of this invention, and the range of this invention should not be interpreted narrowly by this.
As the aluminum member and the copper member, flat plates (strip strips) each having a width of 20 mm and a length of 100 mm were used, and the end surfaces on the width side were butted together. Table 1 shows the composition of aluminum and copper (both are JIS alloy numbers) and the plate thickness of both members.
While pressing the aluminum member and the copper member in the abutting direction, a laser beam was irradiated from the upper surface along the abutting portion to melt the end portion of the aluminum member and form a molten portion linearly along the abutting portion. Thereby, the material of the fusion | melting part was extruded to the outer side of the butt | matching part, and both members were joined.

  The scanner laser device used was a Trudisk 4002 made by Trump Co., Ltd. as an oscillator, and a galvano head scanner unit made by YE Data Co., Ltd. as a welding head. The laser beam moves in a linear direction by a mirror operation in the head. In Examples 1 to 7, the laser beam was scanned a plurality of times along the abutting portion over the entire width, and multiple pass welding was performed. In Comparative Examples 1 and 2, one-pass welding was performed by scanning the laser beam once. Table 1 shows the laser welding conditions. The flash was removed after laser welding.

Using the obtained joining member (dissimilar conductive material), a tensile test, a bending test, and measurement of electric resistance were performed as follows. The results are also shown in Table 1. In addition to the evaluation of individual characteristics, Table 1 lists overall evaluations of excellent (）), good (◯), and unacceptable (x).
In the tensile test, the strip test piece after joining was pulled using a tensile tester until it was broken, and the breaking load (N) was measured. The tensile strength of the joint was obtained by dividing the breaking load by the cross-sectional area (1 × 20 mm ² ) of the test piece.
In the bending test, the weld line portion of the joining member is directed to a round bar having a diameter of 10 mm (the direction of the weld line is parallel to the length direction of the round bar), and the joining member is pressed against the round bar at 90 degrees. Until bent. Those that could be bent without breaking were evaluated as good (◯).
The electrical resistance was measured by using a four-terminal method and measuring the electrical resistance between points 25 mm away from the center of the weld line when a current of 100 A was passed (length between measurements: 50 mm).

  In Comparative Examples 1 and 2 in which the number of passes of the laser beam is 1, the formation of the melted portion is not uniform along the butted portion, and the melted portion is not crushed. As shown in FIG. It solidified without being extruded from. Note that the black linear portion seen in FIG. 4A is an Al—Cu binary intermetallic compound. As a result, in Comparative Examples 1 and 2, the butt part (joint part) was very brittle, and as shown in Table 1, the joint part was broken during the tensile test, and the tensile strength could not be measured. The joint part broke along the way, and the bending strength could not be evaluated. Further, the conductivity of the joint portion was poor (electrical resistance was relatively large).

On the other hand, in the first to seventh embodiments of the present invention in which the number of passes of the laser beam is multiple, the melted portion formed along the butt portion is crushed, and the material of the melted portion is extruded outward in the plate thickness direction. Eliminated and burrs formed on the outside. As a result, at the butt portion (joint portion) of Examples 1 to 7, the Al—Cu binary intermetallic compound is not formed or even when formed, the thickness is about 10 μm at maximum, and high joint tensile strength is obtained. The bending workability was good and the conductivity of the joint was good (low electrical resistance). In particular, Examples 6 and 7 in which the plate thickness of the aluminum member was larger than the plate thickness of the copper member were excellent in all properties (particularly tensile strength), and the overall evaluation was also excellent.
In Examples 1 to 5 and Examples 6 and 7, as shown in FIG. 5B and FIG. 5C, the material of the melted part was discharged well to the outside in the plate thickness direction at the butt part.

1 Aluminum member 2 Copper member 3 Butt line 5 Laser beam 6 Melting part 6a Aluminum melting part 6b Mixing part

Claims (2)

In the method of abutting an aluminum member and a copper member, irradiating the abutting portion while moving a laser beam along the abutting portion, and laser welding the aluminum member and the copper member to produce a different conductive member, in laser welding, The laser beam is moved a plurality of times along the abutting portion, the end portion of the aluminum member is melted to form a linear melted portion along the abutting portion, and the abutting direction of the aluminum member and the copper member A method of manufacturing a dissimilar conductive member, wherein the material of the melted portion is caused to flow to the outside of the abutting portion, and burrs formed on the outside of the abutting portion are removed after laser welding. 2. The method for producing a dissimilar conductive member according to claim 1, wherein both the aluminum member and the copper member are made of a plate material, and the plate thickness of the aluminum member is larger than the plate thickness of the copper member.