JP2010201434A - Laser brazing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser brazing method for forming a joined part that has superior chemical convertibility. <P>SOLUTION: In joining steel plates 10, 12, a Cu-Si based molten material 50, which is a brazing filler metal supplied along the joining face I of the base material steel plates 10, 12, is fused by a laser beam L that moves along the joining face I. In this instance, a part of the steel plates 10, 12 which are situated on the side of the moving direction of the laser beam L from the supply part of the molten material 50, is directly fused by the laser beam, thereby forming the joined part 60 containing iron component that originates in the steel plate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a laser brazing method.

  A laser brazing method is applied to joining of steel plates for automobiles (see, for example, Patent Document 1). In the laser brazing method, the steel plates are joined by irradiating a laser beam onto the wires supplied along the mating surfaces of the butt-matched or superposed steel plates. A Cu—Si system is applied to the wire in consideration of strength, bead appearance and price.

JP 2003-225784 A

  However, Cu-Si-based wires have a problem in chemical conversion treatment because of their high copper content. For example, a bonded automobile steel sheet is coated after being subjected to a chemical conversion treatment, but since the chemical conversion film is not formed on the bonded portion, there is a risk of poor coating. On the other hand, when sealing the said junction part and suppressing generation | occurrence | production of a coating defect, the problem that manufacturing cost rises arises.

  The present invention has been made to solve the problems associated with the above-described prior art, and an object thereof is to provide a laser brazing method capable of forming a joint having good chemical conversion treatment. .

  In order to achieve the above object, the present invention is to melt a Cu-Si-based molten material, which is a brazing material supplied along a mating surface of a steel plate, which is a base material, by a laser beam that moves along the mating surface. And a laser brazing method for joining the steel plates. In the method, a part containing the iron component derived from the steel plate is directly melted by the laser beam, by directly melting a part of the steel plate located on the moving direction side of the laser beam from the molten material supply site. Form.

  According to the present invention, even when a Cu-Si-based molten material having a high copper content is applied as a brazing material, the joint portion contains an iron component derived from a steel plate, and thus a chemical conversion film can be formed. It is. That is, it is possible to provide a laser brazing method capable of forming a joint having good chemical conversion properties.

It is a perspective view for demonstrating the laser brazing apparatus concerning Embodiment 1. FIG. It is a side view for demonstrating the laser brazing apparatus based on Embodiment 1. FIG. FIG. 3 is a plan view for explaining the laser brazing method according to the first embodiment. FIG. 3 is a cross-sectional view for explaining a bead according to the first embodiment. It is explanatory drawing of the iron behavior in the chemical conversion treatment reaction which concerns on Embodiment 1. FIG. 6 is a plan view for explaining a first modification to the first embodiment. FIG. 10 is a graph for explaining a second modification of the first embodiment. FIG. 10 is a perspective view for explaining a third modification to the first embodiment. FIG. 10 is a plan view for explaining the third modification to the first embodiment. FIG. 10 is a cross-sectional view for explaining a fourth modification to the first embodiment. FIG. 10 is a cross-sectional view for explaining a fifth modification of the first embodiment. 6 is a perspective view for explaining a laser brazing method according to Embodiment 2. FIG. 7 is a plan view for explaining a laser brazing method according to Embodiment 2. FIG. FIG. 6 is a cross-sectional view for explaining a bead according to a second embodiment. FIG. 9 is a cross-sectional view for explaining a first modification according to the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 are a perspective view and a side view for explaining the laser brazing apparatus according to the first embodiment.

  The laser brazing apparatus 100 according to the first embodiment includes a machining head 110, an oscillator 120, a wire supply unit 130, a robot arm 140, and a control device 150. By irradiating a laser beam L to a wire (molten material) 50 supplied along 12 mating surfaces I, it is used to join the workpieces 10 and 12 and form a butt joint. The The workpieces 10 and 12 are parts forming a vehicle body panel such as a hood and a door panel of an automobile body, and are made of a galvanized steel plate. The wire 50 is a Cu—Si based brazing material and forms a bead (joint portion) 60.

  As will be described later, the output of the laser beam L and the spot diameter are set so as to form the bead 60 containing the iron component derived from the workpiece (derived from the steel plate) in consideration of the configuration of the workpieces 10 and 12 and the wire 50. Is set. Therefore, the bead 60 to be formed has a good chemical conversion treatment property even when a Cu-Si-based molten material having a large copper content is applied as a brazing material.

  The processing head 110 incorporates an optical system having a collimation lens, a condenser lens, a prism, and the like, and is used for irradiating the wire 50 with the laser light L from the oscillator 120. A bracket 112 for attaching the robot arm 140 is provided.

  For example, a YAG laser is applied to the oscillator 120, and an optical system, a power source, a control system, a cooling gas circulation system, and the like are built in. The generated laser light L is transmitted through an optical fiber cable 122 that is a light guide member. Used to supply the processing head 110. In the control system, for example, an output adjustment unit that adjusts the oscillation output by changing the electric power is arranged. As the oscillator 120, another solid-state laser such as a semiconductor laser, or a gas laser such as a carbon dioxide gas laser can be appropriately applied.

  The wire supply unit 130 includes, for example, a pair of guide rollers that are rotated by a servo motor, controls the supply speed of the wire 50 wound around the wire reel 132, and follows the mating surface I of the workpieces 10 and 12. Used to supply. Further, the wire supply unit 130 is connected to the processing head 110 via the bracket 112, and the supply angle of the wire 50 can be adjusted. The supply angle is defined by an inclination angle with respect to the workpiece surface and an intersecting angle with respect to the extending direction of the mating surface I of the workpieces 10 and 12.

  The robot arm 140 is an articulated (multi-axis) type, and is used to move the machining head 110 and the wire supply unit 130 along a mating surface I of the workpieces 10 and 12 by an autonomous operation, The irradiation angle and brazing speed of the laser beam L from the processing head 110 are set so as to be adjustable. The irradiation angle is defined by the angle between the perpendicular line perpendicular to the workpiece surface and the laser beam L. Note that the moving means of the machining head 110 and the wire supply unit 130 is not limited to the robot arm 140.

  The control device 150 includes a programmable controller having, for example, a central processing unit and a storage device, and is used to integrally control the processing head 110, the oscillator 120, the wire supply unit 130, and the robot arm 140.

  It is also preferable to arrange a mechanism for supplying a shielding gas (assist gas) such as argon gas to suppress the formation of an oxide film during brazing, or to provide a cooling mechanism to absorb heat generated during brazing. . Reference symbol S indicates a laser spot.

  Next, the laser brazing method according to Embodiment 1 will be described.

  3 is a plan view for explaining the laser brazing method according to the first embodiment, FIG. 4 is a cross-sectional view for explaining the bead according to the first embodiment, and FIG. 5 is according to the first embodiment. It is explanatory drawing of the iron behavior in a chemical conversion reaction.

  In the laser brazing method according to the first embodiment, first, the workpieces 10 and 12 made of a galvanized steel sheet are positioned and abutted to form a mating surface I serving as a joint. The control device 150 integrally controls the machining head 110, the oscillator 120, the wire supply unit 130, and the robot arm 140 to start laser brazing.

  The wire supply unit 130 pulls out the Cu—Si wire 50 wound around the wire reel 132. The robot arm 140 moves the machining head 110 and the wire supply unit 130 along the mating surface I of the workpieces 10 and 12 by autonomous operation. Therefore, the wire 50 is supplied along the mating surface I of the workpieces 10 and 12.

  On the other hand, the oscillator 120 supplies the generated laser light to the processing head 110 via the optical fiber cable 122. The processing head 110 irradiates the laser beam L from the oscillator 120. Since the processing head 110 is driven integrally with the wire supply unit 130 by the robot arm 140, the laser beam L is supplied along the mating surface I of the workpieces 10 and 12 while moving along the mating surface I. The wire 50 is melted (see FIG. 3).

  At this time, a part 60 of the workpieces 10 and 12 positioned on the moving direction side of the laser beam L from the supply portion of the wire 50 is directly melted by the laser beam L, whereby a bead 60 containing an iron component derived from a steel plate ( 4) and the workpieces 10 and 12 are joined. The bead 60 can form a chemical conversion film because it contains an iron component derived from a steel plate even when the Cu-Si wire 50 having a high copper content is applied as a brazing material.

  When the laser brazing is continued and the joining of the mating surfaces I of the workpieces 10 and 12 is completed and the butt joint is formed, the machining head 110, the oscillator 120, and the wire supply unit 130 stop operating, and the robot The arm 140 returns to the retracted position.

  The workpieces 10 and 12 on which the butt joints are formed are applied with, for example, a dip method or a continuous spray method in order to form a coating base layer having good corrosion resistance before coating, and a degreasing cleaning process and a chemical conversion process. Is given.

  In the degreasing and cleaning treatment, for example, an emulsion-based or alkaline-based degreasing agent or a zinc phosphate-based chemical conversion agent is used from the viewpoints of rust prevention, relevance to the undercoat, mass productivity, and the like.

  In the chemical conversion treatment, a zinc phosphate treatment solution having good compatibility with iron or zinc is applied. The zinc phosphate treatment liquid contains, for example, phosphoric acid and first zinc phosphate as main components, and includes an oxidizing agent (such as nitric acid, nitrite, and chlorate), a reducing agent, a metal salt, and the like as an accelerator.

In the chemical conversion treatment using the zinc phosphate treatment solution, as shown in FIG. 5, the iron on the surfaces of the workpieces 10 and 12 is etched by free phosphoric acid by being immersed in the zinc phosphate treatment solution. Dissolve. Then, dissolution by iron and phosphate ions in the treatment liquid react to form a coating containing Fe ₂ O _3. That is, a chemical conversion film is formed by a precipitation reaction (chemical reaction) by ion exchange. At this time, the beads 60 of the workpieces 10 and 12 are formed using the Cu-Si-based wire 50 having a high copper content as a brazing material. A film is similarly formed. Therefore, the occurrence of defective coating is suppressed, and it is not necessary to seal the bead 60, and an increase in manufacturing cost can be avoided.

  The coating process includes, for example, an undercoating process, an intermediate coating process, and an overcoating process. In the undercoating step, an undercoating film is formed by electrodeposition coating or powder coating. The undercoat coating film has a function of improving the rust prevention property of the coating film, for example. In the intermediate coating process and the top coating process, the intermediate coating film and the top coating film are formed by air spray, airless spray, or electrostatic coating, respectively. The intermediate coating film has, for example, a function of surface adjustment for compensating for defects in the undercoating film and improving the appearance of the top coating finish. The top coat film has, for example, a function of imparting aesthetics and durability to the environment (such as weather resistance, chemical resistance, and wear resistance).

  FIG. 6 is a plan view for explaining the first modification of the first embodiment.

  The workpieces 10 and 12 that are base materials can be easily melted by increasing the diameter D of the laser spot S. This is because, as shown in FIG. 6, the range in which the laser beam L is directly irradiated on the workpieces 10 and 12 is expanded. The enlargement of the diameter D can be achieved by separating the laser beam focal point from the workpiece surface or changing the laser beam focusing condition.

  The laser beam focus can be separated from the workpiece surface by, for example, changing the program of the robot arm 140 and adjusting the separation distance between the machining head 110 and the workpieces 10 and 12. The condensing condition of the laser beam can be changed by adjusting the optical system of the processing head 110, for example.

  Under the conditions that the laser output is 3 kW, the brazing speed is 3 m / min, the wire diameter is 1 mm, and the wire supply speed is 4.2 m / min, the base metal melting is performed with a laser spot diameter of 3 mm or more (relative to the wire diameter). 3 times or more). Therefore, the laser spot diameter is preferably the above value.

  FIG. 7 is a graph for explaining the modified example 2 in the first embodiment, and shows the relationship between the laser output, the laser spot diameter, and the base material melting.

  The workpieces 10 and 12 that are base materials can be easily melted by increasing the amount of heat input by the laser beam. Increasing the amount of input heat can be achieved by adjusting the output adjustment unit of the oscillator 120 to increase the laser output, or by changing the program of the robot arm 140 to reduce the brazing speed.

  For example, when the laser output is 3 kW under the conditions that the laser spot diameter is 2 mm, the brazing speed is 3 m / min, the wire diameter is 1 mm, and the wire supply speed is 4.2 m / min, the base material does not melt, When the power is 4 kW (1.3 times the laser output at which the base material does not melt) or more, the base material is melted. Therefore, the laser output is preferably the above value. In addition, in the case of a brazing speed | rate, it is preferable to reduce to 2 m / min or less. In this case, since the input heat amount is 1.3 times or more, the base material can be easily melted.

  8 and 9 are a perspective view and a plan view for explaining the third modification of the first embodiment.

Irradiation angle theta _L of the laser beam L which is defined by the angle between the perpendicular line P and the laser beam L perpendicular to the workpiece surface preferably also is inclined so that the forward angle. In this case, the shape of the laser spot S becomes an ellipse (see FIG. 9), and a part of the laser light L is irradiated to a wide range in front of the bead 60. Therefore, it is possible to easily melt the part 14 of the workpieces 10 and 12 located on the moving direction side of the laser beam L from the supply portion of the wire 50.

Under the conditions that the laser output is 3 kW, the laser spot diameter is 2 mm, the brazing speed is 3 m / min, the wire diameter is 1 mm, and the wire supply speed is 4.2 m / min, the base material melting is performed at an irradiation angle θ _L of 40 _L. Occurs at advancing angles greater than °. Therefore, the irradiation angle θ _L is preferably the above value.

  FIG. 10 is a cross-sectional view for explaining a fourth modification of the first embodiment.

  It is also preferable to arrange a gap C on the mating surface I of the workpieces 10 and 12. In this case, when the wire 50 is melted by the laser light L and the workpieces 10 and 12 are joined, the laser light L is introduced between the plates via the gap C. Thereby, since the workpiece | work 10 and 12 which are base materials are additionally heated, the melting | fusing becomes easy.

  Under the conditions that the laser output is 3 kW, the laser spot diameter is 2 mm, the brazing speed is 3 m / min, the wire diameter is 1 mm, and the wire supply speed is 4.2 m / min, the width of the gap C is 0 It occurred at 4 mm or more (0.4 times or more with respect to the wire diameter). Therefore, the width C is preferably the above value.

  FIG. 11 is a cross-sectional view for explaining a fifth modification of the first embodiment.

  It is also preferable that the wire 50 has an iron plating layer (a coating layer having an iron component) 52. In this case, when the wire 50 is melted by laser light and the workpieces are joined, a bead containing an iron component derived from the iron plating layer is formed. As a result, the bead contains the iron component derived from the iron plating layer in addition to the iron component derived from the workpiece, so that even if the amount of melting of the workpiece, which is the base material, is reduced, good chemical conversion treatment is maintained. can do. Therefore, by reducing the amount of input heat, it is possible to suppress distortion caused by laser brazing and improve the laser brazing speed. The iron plating amount is preferably 5% or more of the wire weight.

  As described above, in the first embodiment, workpieces can be joined to form a butt joint, and a bead is applied to a Cu-Si-based wire having a high copper content as a brazing material. Even so, it contains an iron component derived from a steel plate. Therefore, it is possible to form a chemical conversion film, suppress the occurrence of coating failure without sealing the bead, and avoid an increase in manufacturing cost. That is, it is possible to provide a laser brazing method capable of forming a bead having good chemical conversion properties.

  Further, when the laser spot diameter is enlarged by moving the laser beam focus away from the workpiece surface or changing the laser beam focusing condition to achieve melting of the workpiece, the laser beam on the workpiece is directly irradiated. Since the range is expanded, the workpiece can be easily melted. The laser spot diameter is preferably at least 3 times the wire diameter.

  When increasing the laser output or decreasing the brazing speed to increase the heat input by the laser beam and achieve melting of the workpiece, the input heat amount increases, so that the workpiece is easily melted. The input heat amount is preferably 1.3 times or more that when wire melting (workpiece bonding) occurs but base metal melting does not occur.

  When the irradiation angle of the laser beam is tilted so as to be a forward angle, a part of the laser beam is irradiated over a wide range in front of the bead, so that the workpiece positioned on the laser beam moving direction side from the wire supply site. It is possible to melt a part of these easily. The advance angle is preferably 40 ° or more.

  When a gap is disposed on the mating surface of the workpiece, laser light is introduced between the plates via the gap, and the workpiece as the base material is additionally heated, so that the melting is facilitated. The width of the gap is preferably 0.4 times or more with respect to the wire diameter.

  When an iron plating layer is provided on the wire, the bead contains an iron component derived from the iron plating layer in addition to the iron component derived from the workpiece. Sex can be maintained. Therefore, by reducing the amount of input heat, it is possible to suppress distortion caused by laser brazing and improve the laser brazing speed. The iron plating amount is preferably 5% or more of the wire weight.

  Next, a second embodiment will be described.

  12 and 13 are a perspective view and a plan view for explaining the laser brazing method according to the second embodiment, and FIG. 14 is a cross-sectional view for explaining the bead according to the second embodiment.

  The second embodiment is generally different from the first embodiment with respect to the structure of the joint to be formed, and the workpieces 20 and 22 are joined in a superposed state to form a lap fillet joint. That is, in the laser brazing method according to the second embodiment, the laser light that moves along the mating surface I is the Cu—Si-based wire 50 that is supplied along the mating surface I of the stacked workpieces 20 and 22. When the workpieces 20 and 22 are joined by being melted by L, a part 24 of the workpieces 20 and 22 located on the moving direction side of the laser beam L from the supply portion of the wire 50 is directly melted by the laser beam L, As FIG. 14 shows, the bead 62 containing the iron component derived from a workpiece | work is formed.

  Therefore, even if a Cu-Si-based wire having a high copper content is applied as a brazing material, the bead 62 contains an iron component derived from a steel plate, and thus a chemical conversion film can be formed. Without sealing, it is possible to suppress the occurrence of defective coating and avoid an increase in manufacturing cost.

  FIG. 15 is a cross-sectional view for explaining the first modification according to the second embodiment.

  It is also preferable to arrange a gap C on the mating surface I of the workpieces 20 and 22 as in the fourth modification according to the first embodiment. In this case, the laser beam L is introduced between the plates via the gap C, and the workpieces 20 and 22 which are the base materials are additionally heated, so that melting thereof is facilitated.

  As described above, in the second embodiment, the stacked workpieces can be joined to form a lap fillet joint. In addition, when a gap is provided on the mating surface of the workpiece, laser light is introduced between the plates via the gap, and the workpiece is additionally heated, so that the melting is facilitated.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, the modifications 1 to 3 and 5 according to the first embodiment can be applied to the second embodiment.

  The workpiece is not limited to a part that forms a body panel such as a hood or a door panel of an automobile body. Moreover, the steel plate which comprises a workpiece | work can also apply other than a galvanized steel plate. Furthermore, the joint formed by joining the workpieces is not limited to the butt joint (seeing joint) and the lap fillet joint.

10, 12, 20, 22 Workpiece (steel plate as base material),
14,24 Part of work,
50 wires (molten material),
52 Iron plating layer (coating layer having iron component),
60, 62 bead (joint),
100 laser brazing device,
110 processing head,
112 bracket,
120 oscillator,
122 optical fiber cable,
130 wire supply unit,
132 wire reels,
140 robot arm,
150 controller,
C gap,
D Laser spot diameter,
I mating surface,
L laser light,
P perpendicular,
S laser spot,
θ _L irradiation angle.

Claims (6)

  When melting the Cu—Si-based molten material, which is a brazing material supplied along the mating surface of the steel plate, which is the base material, with a laser beam that moves along the mating surface, A part containing the iron component derived from a steel sheet is formed by directly melting a part of the steel sheet located on the moving direction side of the laser light from a material supply site by the laser light. Laser brazing method.   The laser brazing method according to claim 1, wherein a part of the steel sheet is melted by enlarging a spot diameter of the laser light.   3. The laser brazing method according to claim 1, wherein a part of the steel sheet is melted by increasing an amount of heat input by the laser light. 4.   The laser beam irradiation angle defined by the angle between the perpendicular line perpendicular to the surface of the steel plate and the laser beam is inclined so as to be a forward angle. The laser brazing method described in 1. A gap is disposed on the mating surface of the steel plates,
The melted material is melted by the laser beam and the laser beam is introduced between the plates via the gap when the steel plates are joined. The laser brazing method described in 1. The molten material has a coating layer containing an iron component,
The melted material is melted by the laser beam, and when joining the steel plates, a joining portion containing an iron component derived from a coating layer is formed. Laser brazing method.

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