JP2012045570A - Method for manufacturing aluminum joined body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an aluminum joined body, capable of welding an aluminum material containing Mg at high productivity and making a welded portion excellent in welding quality.SOLUTION: A pair of materials to be welded made of an aluminum material are disposed so as to abut to each other, and the abutting portion is irradiated with a laser beam having two or three focal points on a single optical axis. A first focal point position of a first laser beam is set to be a position within 0.2 mm in an optical axis direction from a datum plane which is the surface of the materials to be welded, a second focal point position of a second laser beam is set to be a position of 0.2-0.9 mm toward the inside of the materials to be welded in the optical axis direction from the datum plane, and a third focal point position of a third laser beam is set to be a position of 0.2-0.5 mm toward the upper part of the materials to be welded in the optical axis direction from the datum plane.

Description

  The present invention relates to an aluminum joined body manufacturing method for manufacturing a structural member made of an aluminum joined body by laser welding aluminum or an aluminum alloy (hereinafter referred to as an aluminum material).

  In order to reduce the weight of battery cases such as lithium ion batteries used in mobile phones and automobiles, an aluminum material made of pure aluminum such as Al-Mn based aluminum alloy or JIS A1050 is used. . This battery is manufactured by housing a battery part inside a casing of a battery case, and then joining a lid to the opening by welding to seal the battery part. This battery case is composed of a housing and a lid, both of which are made of an aluminum material.

  In such battery cases, defects such as spatter, cracks, and blowholes that occur during welding greatly deteriorate the quality and performance of the battery. Therefore, extremely strict management is required to improve and maintain the quality of welds. Required.

  On the other hand, the demand for lighter weight for battery cases is increasing, and both high-strength materials are required for both mobile phone batteries and in-vehicle batteries. Attempts have been made to reduce the thickness of the glass by reducing its thickness.

  As a conventional battery case made of aluminum material, when the sealing part of the casing and the lid is fused by laser welding, a region with a small amount of penetration is formed, and this is cleaved when the pressure inside the battery increases. A sealed battery having a pressure release portion has been proposed (Patent Document 1). In addition, an irradiation spot-shaped laser beam having a major axis such as an ellipse or a rectangle is placed at the junction between the casing and the lid with the spot center point, and the major axis direction of the spot extends in the direction in which the junction extends. There has been proposed a battery manufacturing method in which a pulse laser beam is irradiated to the entire circumference of the joint portion (Patent Document 2). Furthermore, in order to prevent the occurrence of cracks by reducing the thermal stress during welding, a lid having a rib along the circumference is fitted to the opening edge of the outer can (housing), and the outer can A method of manufacturing a sealed battery in which laser welding is performed between the opening edge of the lid and the rib at the edge of the lid has been proposed (Patent Document 3).

JP 2001-155698 A JP 2004-63406 A Japanese Patent No. 3594555

  However, although some improvement in welding quality is expected by devising the joint shape, in order to improve the strength of the battery case, it is necessary to improve the material strength of the battery case itself. Elements that improve the strength of the aluminum material include Mg and Cu. Al alloys containing a large amount of these elements, for example, Al alloys such as JIS 3004, 3104, 5052, and 5182 are particularly affected by the generation of Mg vapor. With aluminum materials that cannot suppress spatter generation, and the weld quality deteriorates due to cracks in the weld and residual blowholes in the weld, and the aluminum material satisfies all of the weld strength, welding workability, and weld quality. There wasn't.

  In addition, pulse lasers that are conventionally used for joining thin-walled materials such as batteries for mobile phones are prone to problems such as weld cracking, and the welding speed is significantly slower than continuous laser light. There is a problem that the nature is low.

  The present invention has been made in view of such problems, and provides a method for manufacturing an aluminum joined body that can weld an aluminum material containing Mg with high productivity and that has excellent weld quality of a welded portion. For the purpose.

  A first aluminum joined body manufacturing method according to the present invention is a laser in which a pair of materials to be welded made of an aluminum material are arranged in an aspect to be welded and have two focal positions on one optical axis. Light is irradiated to the welding position of the material to be welded to melt weld the material to be welded. At this time, the first focal position having a shorter focal length is used as a reference surface for one surface of the material to be welded. And the second focal position having the longer focal length is directed from the reference surface toward the inside of the workpiece to be welded in the optical axis direction. The position is set to be 0.2 to 0.9 mm.

  According to the second method of manufacturing an aluminum joined body according to the present invention, a pair of welded materials made of an aluminum material are arranged in an aspect to be welded, and a laser having three focal positions on one optical axis. Light is irradiated to the welding position of the material to be welded to melt weld the material to be welded, and at this time, the first focal position having an intermediate focal length is set as one of the surfaces of the material to be welded as a reference surface. The position is set to be within 0.2 mm in the optical axis direction from the reference surface, and the second focal position with the longer focal length is set to 0 from the reference surface toward the inside of the welded material in the optical axis direction. .2 to 0.9 mm, and the third focal position with the shorter focal length is set to 0.2 to 0 from the reference surface to above the workpiece in the optical axis direction. It is set to be a position of 5 mm.

  In the third method for producing an aluminum joined body according to the present invention, a pair of materials to be welded made of an aluminum material are arranged to face each other, and laser light having two focal positions on one optical axis is obtained. The welding position is irradiated to the welding position of the material to be welded, and the welding material is melt-welded. At this time, the first focal position having a shorter focal length is set to the surface of the material to be welded as a reference surface, and the optical axis from the reference surface. The second focal position having the longer focal length is set to 0.2 to 0.9 mm from the reference surface toward the inside of the welded material in the optical axis direction. It is set to become the position of.

  In the fourth method for producing an aluminum joined body according to the present invention, a pair of materials to be welded made of an aluminum material are arranged to face each other, and laser light having three focal positions on one optical axis is obtained. Irradiating the welding position of the material to be welded to melt weld the material to be welded. At this time, the first focal position having an intermediate focal length is set to the surface of the material to be welded as a reference surface, and the optical axis direction from the reference surface The second focal position with the longer focal length is set to 0.2 to 0.9 mm from the reference surface toward the inside of the workpiece to be welded in the optical axis direction. The third focal position with the shorter focal length is set to a position of 0.2 to 0.5 mm from the reference surface toward the upper side of the welded material in the optical axis direction. It is characterized by setting to.

  In these methods for producing an aluminum joined body, the aluminum material is, for example, JIS 1000 series, 3000 series or 5000 series.

  Further, in these aluminum joined body manufacturing methods, one aluminum material is JIS1000 series, the other aluminum material is JIS3000 series or 5000 series, and a battery case lid is made of the one aluminum material, A case of the battery case can be made of the other aluminum material, and the lid can be joined to the case.

  According to the present invention, even an aluminum material containing a large amount of Mg can be laser-welded with high productivity, and a high-quality weld can be obtained.

It is a schematic diagram which shows the manufacturing method of the aluminum joined body of embodiment of this invention. It is a figure which shows the focus position of 3 types of laser beams. It is sectional drawing which shows a to-be-welded material and a welding part. (A), (b) is a figure which shows the arrangement | positioning relationship between the housing | casing and lid | cover of a battery case. It is sectional drawing which shows the molten pool formed by irradiation of the laser beam. It is a figure which shows a keyhole. It is a figure which shows the effect of this invention, (a) shows the magnitude | size of the molten pool in the case of the conventional single focus, (b) shows the size of the molten pool in the case of the double focus of this invention.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a schematic view showing an apparatus used in a method for producing an aluminum joined body according to an embodiment of the present invention. The laser light source 1 is provided with an oscillator 2 that emits a first laser beam having a first wavelength, and an oscillator 3 that emits a second laser beam having a second wavelength. Two types of laser light having a wavelength and a second wavelength are emitted. The laser light source 4 is provided with an oscillator that emits a third laser beam having a third wavelength. The laser beams from these light sources 1 and 4 are supplied to the optical combiner 6 through the optical waveguides 5a and 5b, and the first to third laser beams are combined on the same optical axis. The laser light emitted from the light combiner 6 is converged on the surface of the material to be welded by the optical systems 7a and 7b.

  At this time, as shown in FIG. 2, the focal point of the first laser beam is set in the vicinity of the processed surface of the workpiece, and the second laser beam is inside the material more than the processed surface of the workpiece. The focal position is set on the side, and the focal position of the third laser beam is set above the processed surface of the workpiece. That is, the first laser beam converges at the first focal position, the second laser beam converges at the second focal position, and the third laser beam converges at the third focal position. These first to third laser beams are emitted from the optical systems 7a and 7b on the same optical axis, but the focal length of these laser beams is the longest for the second laser beam, and then The first laser beam and the third laser beam are the shortest, and the focal length of the second laser beam is the shortest. The first focal position of the first laser beam is in the vicinity of the surface of the welded material. If the surface of the welded material is the reference surface, the optical axis is 0.2 mm above the reference surface. Is set in a range from a position of 0.2 mm to a position 0.2 mm below. The second focal position of the second laser beam is a position that enters the inside of the material to be welded from the surface of the material to be welded, and enters the inside of the material by 0.2 to 0.9 mm from the reference surface on the optical axis. It is a position. Further, the third focal position of the third laser beam is a position above the surface of the material to be welded, and is a position above the material by 0.2 to 0.5 mm from the reference surface on the optical axis. is there. The laser beam may be a mixture of the first and second types of laser beams, or may be a mixture of the first to third types of laser beams. .

  In this case, as shown in FIG. 4A, the battery case has an opening at the upper end of the casing 10, and a lid 11 is placed on the upper end opening of the casing 10, and an arrow indicates As shown, the position between the lower surface of the lid 11 and the upper end of the housing 10 is joined, or the lid 11 is fitted into the upper end opening of the housing 10 as shown in FIG. It has a size, and the lid 11 is fitted into the housing 10, and the position between the edge of the lid 11 and the inner surface of the upper end of the housing 10 is joined as indicated by an arrow.

  Therefore, for example, in the case of FIG. 4B, the welded portion 12 is formed between the upper end surface of the housing 10 and the upper end portion of the lid 11 as shown in FIG. 3. These welded materials (the lid 11 and the housing 10) are basically flush with the surface irradiated with the laser beam in the welded portion. For this reason, as shown in FIG. 2, the position of the reference surface of the welding material used as the reference | standard for setting the focus position of the 1st thru | or 3rd laser beam is the same with both welding materials. However, as described above, when the surfaces of the workpieces are not flush, that is, when there are steps on the surfaces of the workpieces, the reference for setting the focal positions of the first to third laser beams. As the reference surface, the surface of one of the materials to be welded is adopted.

  Next, the operation of the embodiment of the present invention will be described. First, for example, the housing 10 and the lid 11 are arranged as shown in FIG. 3 to form a butt joint. Then, as shown in FIG. 1, laser light is emitted from the light source 1 or the light source 1 and the light source 2, and the first laser light having the first focal position and the second laser light having the second focal position are obtained. Irradiating the welded portion 12 on the same optical axis, or a first laser beam having a first focal position, a second laser beam having a second focal position, and a third having a third focal position. Is irradiated to the welded portion 12 on the same optical axis. The portion irradiated with the laser beam is heated and melted by the energy of the laser beam to form a molten pool, and the irradiation position of the laser beam is moved along a welding line that is perpendicular to the paper surface of FIG. Thereby, the edge part of the lid | cover 11 is joined to the upper end part of the housing | casing 10 in the whole region.

  In laser welding, as shown in FIG. 5, a keyhole 21 is formed with the irradiation of the laser beam 20, and the molten pool 22 is positioned at a position opposite to the laser beam traveling direction (welding direction) from the keyhole 21. Is formed. Then, bubbles 24 are generated in the formation process of the keyhole 21, and when the bubbles 24 cannot be lifted up in the molten pool 22 and are taken into the weld metal when the molten pool 22 is solidified, porosity or blowhole or the like is generated. A defect 23 occurs. At this time, an aluminum alloy containing a large amount of Mg, for example, JIS 3004 alloy, JIS 3104 alloy, JIS 5052 alloy, or JIS 5182 alloy, tends to evaporate Mg. Therefore, blowy hole defects 23 are caused by bubbles 24 generated by Mg evaporation. Is likely to occur. In addition, an aluminum alloy containing a large amount of Mg is likely to cause sputter defects formed by the molten pool splashing due to Mg evaporation. Furthermore, in the case of laser welding, weld cracking is likely to occur due to thermal expansion and contraction of the welded portion of the material due to sudden application of energy.

  Conventionally, in order to prevent the occurrence of such welding defects or spatter, welding is performed by increasing the energy density of the laser beam and decreasing the beam diameter, or conversely, by defocusing the laser beam and reducing the beam diameter. Attempts have been made to make it larger and weld it. However, when welding with a beam having a high energy density, the above-mentioned problems of spatter and weld cracking become large. Conversely, when the laser beam is defocused, the penetration depth necessary to obtain sufficient joint strength is obtained. There is a problem that it is difficult to obtain. Note that the keyhole 21 is not always maintained in a fixed shape, but is locally blocked or expanded as shown in FIG. 6 as the laser beam moves.

  In the present invention, in order to solve the above-mentioned problems when laser welding an aluminum material containing a large amount of Mg, two or three types of laser beams having different focal positions are used with the same optical axis. At the same time, the material to be welded is irradiated. In order to obtain two or three types of laser beams having different focal positions, two or three types of laser beams having different wavelengths are superimposed and combined, and the same lens is transmitted and irradiated onto the material to be welded. Thereby, two or three kinds of laser beams having different focal positions are irradiated on the welded material on the optical axis.

  At this time, since the focal position of the first laser beam is in the vicinity of the surface position of the workpiece, the portion near the surface of the workpiece is heated and melted. The irradiation with the first laser beam has the same effect as when the laser beam having a high energy density (focused on the surface of the material to be welded and the beam diameter is small on the surface) is irradiated on the material to be welded. On the other hand, the second laser beam whose focal position is located inside the material is also irradiated. Thereby, the inside of the material to be welded is heated and melted. The irradiation with the second laser beam has the same effect as that when the defocused laser beam is irradiated. By irradiating the laser beam having such two kinds of focal positions, the weld pool becomes longer in the welded material. That is, in the case of the conventional single focus shown in FIG. 7A, the width of the molten pool in the laser traveling direction (welding direction) is small, whereas the focus position is two double focuses as in the present invention. In this case, as shown in FIG. 7B, the molten pool extends rearward in the laser traveling direction (welding direction), and the width of the molten pool in the laser traveling direction is increased. As described above, in the case of the present invention, as a result of the molten pool spreading long in the laser traveling direction, the generated bubbles rise in the molten pool and are easily separated from the surface of the molten pool. The occurrence of defects such as blow holes and porosity in the weld is suppressed. For this reason, even if it is the aluminum material which contains Mg abundantly, the bubble which generate | occur | produced tends to detach | leave from a molten pool and it is prevented that defects, such as a blowhole, generate | occur | produce in the welding part after solidification. In addition, the expansion of the molten pool suppresses bubbles from escaping in the molten pool and prevents spattering.

  On the other hand, when the third laser beam having a short focal length is irradiated in addition to the first and second laser beams, the defocused laser beam is further irradiated to further expand the molten pool. Thereby, a welding part defect can be reduced further. Furthermore, spatter can be further reduced.

  Next, examples demonstrating the effects of the present invention will be described in comparison with comparative examples that are out of the scope of the present invention. Semiconductor laser light was emitted from the oscillators 2 and 3 of the laser light source 1, and continuous YAG laser light or pulsed YAG laser light was emitted from the laser light source 4. The semiconductor laser light is emitted from the oscillators 2 and 3 and has wavelengths of 808 nm and 940 nm, respectively. The YAG laser beam has a wavelength of 1064 nm.

  The emission conditions of the semiconductor laser are as follows: the laser output is 2.8 to 3.5 kW, the welding speed is 10 m / min, the shielding gas is Ar gas, and the flow rate is 20 liters / min. , 7b) was transmitted by an optical fiber (waveguides 5a, 5b) having a diameter of 0.4 mm.

  A continuous YAG laser is an optical fiber having a laser output of 3.0 to 4.0 kW, a welding speed of 10 m / min, a shielding gas of Ar gas, a flow rate of 20 liters / min, and a diameter of 0.4 mm from the oscillator to the lens. Was transmitted. The pulse YAG laser had a laser output of 300 W, a welding speed of 1 m / min, a shielding gas of Ar gas and a flow rate of 20 liters / min, and was transmitted from an oscillator to a lens by an optical fiber having a diameter of 0.4 mm.

  As shown in Table 1 below, the materials were combined and welded. The weld joint is a downward joint of an I groove formed between the housing 10 shown in FIG. 3 and the lid 11 fitted to the upper end opening of the housing 10, and has a cross section perpendicular to the weld line. Is L-shaped. Among the lid 11 and the housing 10, the lid 11 is on the thick plate side, the housing 10 is on the thin plate side, the thick plate side aluminum material has a thickness of 1.0 to 1.5 mm, and the thin plate side aluminum material is The thickness is 0.3 to 0.8 mm. The type column in Table 1 shows the alloy type of the aluminum material on the thick plate side and the alloy type of the aluminum material on the thin plate side by JIS symbols. The focal positions are positions A, B, and C in FIG.

  The amount of spatter was determined by measuring the number of spherical molten metal solidified substances adhering to the appearance of the weld. Then, when the number of sputtered particles is 10 per 10 mm length, the amount of sputter was evaluated as ◎, when it is 1 or less, ◯ when it exceeds 1 and △ when it is 5 or less, and x when it exceeds 5 .

  The determination of porosity and weld cracking is performed by polishing the cross section of the weld parallel to the weld line direction and expanding the polished surface at the groove position before this welding 10 times with a magnifying glass. Cracks were observed. The porosity was evaluated as 0 for a 10 mm length, ◯ for 1 or less, ◯ for 1 or less, and Δ for 5 or less, and x for 5 or less. When even one crack existed, it was set as x. In the evaluation column of Table 1, in the welding quality, ◎ if there are 2 or more, ◎, if there are 2 or more, ×, if X is 1 or if there are 2 △, × and Δ are not present ○.

  As shown in Table 1, Examples 1 to 12 of the present invention were excellent in that the welding quality was either ○ or ◎, and the evaluation was ◎ or ○. On the other hand, in Comparative Examples 1 to 14, which are out of the scope of the present invention, either welding quality was x or Δ, and the evaluation was also x or Δ.

DESCRIPTION OF SYMBOLS 1,4: Light source 2, 3: Oscillator 7a, 7b: Optical system 10: Housing | casing 11: Lid 20: Laser beam 21: Keyhole 22: Molten pool 23: Defect (blowhole)
24: Bubble

Claims (6)

A pair of materials to be welded made of an aluminum material are arranged in a mode to be welded, and a laser beam having two focal positions on one optical axis is irradiated to the welding position of the material to be welded. The material to be welded is melt-welded, and at this time, the first focal position having a shorter focal length is defined as a position within 0.2 mm in the optical axis direction from the reference surface with either surface of the material to be welded as the reference surface. The second focal position with the longer focal length is set to a position of 0.2 to 0.9 mm from the reference surface toward the inside of the welded material in the optical axis direction. A method for producing an aluminum joined body, comprising: A pair of materials to be welded made of an aluminum material are arranged in a mode to be welded, and a laser beam having three focal positions on one optical axis is irradiated to the welding position of the material to be welded. The material to be welded is melt-welded, and at this time, the first focal position having an intermediate focal length is defined as a position within 0.2 mm from the reference surface in the optical axis direction with any one surface of the material to be welded as the reference surface. Set so that the second focal position of the longer focal length is set to a position of 0.2 to 0.9 mm from the reference surface toward the inside of the welded material in the optical axis direction, The third focal position having a shorter focal length is set to be a position of 0.2 to 0.5 mm from the reference surface toward the upper side of the welded material in the optical axis direction. Manufacturing method of aluminum joined body. A pair of materials to be welded made of an aluminum material are arranged to face each other, and laser light having two focal positions on one optical axis is irradiated to the welding position of the material to be welded to form the material to be welded. At this time, the first focal position having a shorter focal length is set so that the surface of the material to be welded is a reference surface, and the position is within 0.2 mm from the reference surface in the optical axis direction, The second focal position having the longer focal length is set to be a position of 0.2 to 0.9 mm from the reference surface toward the inside of the welded material in the optical axis direction. Body manufacturing method. A pair of materials to be welded made of an aluminum material are arranged to face each other, and laser light having three focal positions on one optical axis is irradiated to the welding position of the material to be welded to form the material to be welded. At this time, the first focal position with an intermediate focal length is set so that the surface of the material to be welded is a reference surface, and the position is within 0.2 mm in the optical axis direction from the reference surface, The second focal position with the longer focal length is set to a position of 0.2 to 0.9 mm from the reference surface toward the inside of the welded material in the optical axis direction, and the shorter focal length is set. A method for producing an aluminum joined body, wherein the third focal position is set to a position of 0.2 to 0.5 mm from the reference surface toward the upper side of the welded material in the optical axis direction. The said aluminum material is a JIS1000 type | system | group, 3000 type | system | group, or 5000 type | system | group, The manufacturing method of the aluminum joined body of any one of Claim 1 thru | or 4 characterized by the above-mentioned. One aluminum material is a JIS 1000 series, the other aluminum material is a JIS 3000 series or 5000 series, the one aluminum material is a battery case lid, the other aluminum material is a battery case housing, and the housing The method for producing an aluminum joined body according to any one of claims 1 to 5, wherein a battery case in which the lid is joined to a body is produced.

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