JP2004358529A - Laser beam welding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam welding device capable of obtaining uniform and excellent welding quality over the whole length directions of flanges 1a, 2a in the laser beam welding device in which the flanges 1a, 2a each other of two members 1, 2 to be welded are joined by laser beam welding. <P>SOLUTION: The laser beam welding device is provided with upper and lower pressurizing rollers 6, 7, which are constituted so as to respectively roll and move in the flange length direction on each face on the side opposite to the mating faces in two flanges 1a, 2a while clamping both flanges 1a, 2a by being respectively pressed to each face on the side opposite to the mating faces in the flanges 1a, 2a whose mating faces are fitted to each other, and a laser head 8, which is constituted so as to move in the flange length direction along the face on the side opposite to the mating face in one flange 1a by interlocking with the movement of the pressurizing roller 6 located at one flange 1a side and which emits a laser beam toward the vicinity of the pressurizing roller contact part on the face. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser welding apparatus, and particularly, to a technical field of joining two flanges of two members to be joined together by a flange such as a fuel tank by laser welding.
[0002]
[Prior art]
Conventionally, seam welding or spot welding by resistance welding is well known as a method of welding the flanges of two members to be joined that are joined together by flanges. For example, a fuel tank that is mounted on a vehicle or the like is a flange that is provided so that two bottomed cylindrical members protrude outward in the radial direction around the entire opening edge of the bottomed cylindrical members. When manufacturing such a fuel tank, the flanges of the two bottomed cylindrical members are joined using a seam welder by resistance welding (for example, Patent Document 1).
[0003]
However, in the resistance welding method, in order to increase the cooling efficiency of the electrode surface and obtain stable welding quality, a large-diameter and wide welding electrode is required. It needs to be relatively large, such as about 20 mm.
[0004]
In addition, seam welding by resistance welding requires a large electrode as described above, and the drive device is also large. Therefore, there is a possibility that a portion where the seam welding cannot be applied due to interference between the welding device and the fuel tank. is there. For this reason, when sealability is required over the entire circumference of the flange as in a fuel tank, it is necessary to use adhesive application, arc welding, or the like in combination with a portion where seam welding cannot be applied.
[0005]
Further, in the resistance welding method, since the electrode contacts the flange, when the flange is plated, depending on the material of the plating, the plating may adhere to the surface of the welding electrode or may be alloyed. A part becomes an insulator and there exists a problem of reducing a welding quality by this.
[0006]
Therefore, for example, as disclosed in Patent Document 2, it is conceivable to join the flanges of two members to be joined by laser welding. That is, with the mating surfaces of both flanges aligned with each other, the laser beam is continuously applied in the flange length direction (direction perpendicular to the flange protruding direction (width direction)) to the surface opposite to the mating surface of one flange. Irradiation can solve the above problems if laser welding is performed over the entire flange length direction.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-241684 [Patent Document 2]
[Patent Document 1] Japanese Patent Laid-Open No. 2003-21012
[Problems to be solved by the invention]
By the way, in order to obtain good welding quality in the above laser welding method, the gap between two overlapped workpieces is considerably reduced (for example, 0.1 mm or less), and the laser condensing lens in the laser head is used. The distance between the machining surface and the processing surface must always be substantially the same as the focal length of the laser condenser lens, and the incident angle of the laser beam on the processing surface must be maintained constant.
[0009]
However, since the surface accuracy of the flange provided on the bottomed cylindrical member of the fuel tank is usually not so high, it is very difficult to satisfy the above conditions over the entire length of the flange. is there. For this reason, there is a problem that the welding quality varies only by performing laser welding, and uniform and good welding quality cannot be obtained over the entire flange length direction.
[0010]
The present invention has been made in view of such points, and the object of the present invention is to solve the above-mentioned problems in laser processing when the flanges of two members to be joined are joined together by laser welding. The object is to overcome and to obtain a uniform and good weld quality over the entire length of the flange.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a laser welding apparatus that joins the flanges of two members to be joined that are joined together by flanges by laser welding in a state where the mating surfaces of the flanges are joined together. In the two flanges in which the mating surfaces are mated with each other, the two flanges are pressed against each other on the opposite side of the mating surfaces, and the two flanges are sandwiched between the flanges in the flange length direction. A plurality of pressure rollers each configured to roll and move along a surface opposite to the mating surface of the one flange in conjunction with the movement of the pressure roller located on the one flange side. The laser head is configured to move in the flange length direction and emits laser light toward the vicinity of the pressure roller contact portion on the surface.
[0012]
With the above configuration, the two flanges are sandwiched between the plurality of pressure rollers, so that the mating surfaces are in close contact with each other in the pressure roller contact portion or in the vicinity thereof. Since the welding is performed by irradiating the vicinity of the pressure roller contact portion with the laser beam, the welding quality does not deteriorate due to the large gap between the two flanges. Further, the laser head moves in the flange length direction along the surface with which the pressure roller abuts in conjunction with the movement of the pressure roller located on one flange side, so that the pressure roller abutting portion is always provided. The distance between the laser condensing lens in the laser head and the surface where the pressure roller abuts (the processing surface on which the laser light is irradiated) and the laser light on the processing surface can be irradiated with laser light in the vicinity. The incident angle can be kept constant. Therefore, when the pressure roller is moved over the entire flange length direction while emitting laser light from the laser head, laser welding is performed over the entire flange length direction, and this welding quality is determined in the flange length direction. It becomes uniform and good throughout.
[0013]
According to a second aspect of the present invention, in the first aspect of the invention, there is provided a rotational speed detecting means for detecting the rotational speed of the pressure roller, and the light is emitted from the laser head in accordance with the rotational speed detected by the rotational speed detecting means. It is assumed that the output of the laser beam is changed.
[0014]
Thereby, even if the moving speed of the pressure roller is not constant, the actual speed of the processing point can be fed back to the laser output in real time, and the amount of heat generated at the processing point can be made constant. Therefore, the welding quality can be made more uniform and at a high level.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 schematically shows a laser welding apparatus according to an embodiment of the present invention. This laser welding apparatus joins flanges respectively provided on two members to be joined by laser welding. In this embodiment, the joined members are two bottomed cylindrical members 1 and 2 constituting a fuel tank mounted on a vehicle or the like.
[0017]
The fuel tank includes an upper bottomed cylindrical member 1 that opens downward and constitutes the upper half of the fuel tank, and a lower bottomed cylindrical member that opens upward and constitutes the lower half of the fuel tank. 2 are joined by flanges 1a and 2a provided so as to protrude outward in the radial direction (horizontal direction) around the entire periphery of the opening edge of the bottomed cylindrical members 1 and 2, respectively. That is, the lower surface of the flange 1a of the upper bottomed tubular member 1 and the upper surface of the flange 2a of the lower bottomed tubular member 2 are aligned with each other so that the openings of the two bottomed cylindrical members 1 and 2 face each other. In this state, the flanges 1a and 2a are joined by laser welding. Thus, the lower surface of the flange 1a of the upper bottomed tubular member 1 and the upper surface of the flange 2a of the lower bottomed tubular member 2 become the mating surfaces of the flanges 1a and 2a, respectively. Both the bottomed cylindrical members 1 and 2 are made of a metal plate, and the flanges 1a and 2a are integrally formed with a main body portion which is a bottomed cylindrical portion by plastic working.
[0018]
The laser welding apparatus includes an attachment member 5 attached to the tip of an arm of a multi-axis robot (not shown), and two flanges 1a and 2a in which the mating surfaces are mated with each other on the opposite side of the mating surface. The upper and lower pressure rollers 6 and 7 sandwich the flanges 1a and 2a by being pressed against the surfaces, respectively, and a laser head 8 that emits laser light.
[0019]
The mounting member 5 is moved upward by a predetermined distance from the upper surface of the flange 1a of the upper bottomed tubular member 1 by the arm of the multi-axis robot (the upper pressure roller 6 is a flange of the upper bottomed tubular member 1). It is configured to move in the circumferential direction of the flange (flange length direction) along the upper surface at a position separated by a distance abutting the upper surface of 1a. A roller support member 11 is fixedly attached to the lower surface of the mounting member.
[0020]
The upper pressure roller 6 is in contact with the upper surface of the flange 1a of the upper bottomed cylindrical member 1, and a rotating shaft 6a formed to project at the center of the upper pressure roller 6 has the roller support member. 11 is supported by a bearing 12 disposed at the lower end of the shaft 11 so that it can rotate around the rotary shaft 6a. Grooves 6 b are formed on the entire outer peripheral surface of the upper pressure roller 6.
[0021]
On the other hand, the lower pressure roller 7 is located directly below the upper pressure roller 6, and a rotating shaft 7 a formed to project at the center of the lower pressure roller 7 is the roller support member. 11 is pivotally supported by a bearing 22 disposed on a movable member 21 located on the lower side of the motor 11, so that it can rotate around the rotary shaft 7a. Grooves 7 b similar to those of the upper pressure roller 6 are also formed on the entire outer peripheral surface of the lower pressure roller 7.
[0022]
The movable member 21 is configured to be movable in the vertical direction relative to the roller support member 11. That is, a cylinder 14 is fixed to the roller support member 11, and a cylinder rod 14a of the cylinder 14 is extended and contracted in the vertical direction. The movable member 21 is connected to the tip (lower end) of the cylinder rod 14a, and the movable member 21 is vertically moved relative to the roller support member 11 by the vertical expansion and contraction operation of the cylinder rod 14a. To move to. Two thrust shafts 24 having a circular cross section extend upward on the upper surface of the movable member 21, while two thrust bearings 16 for guiding the vertical movement of the thrust shaft 24 are provided on the roller support member 11. The movable member 21 is smoothly moved up and down by this.
[0023]
The lower pressure roller 7 is pressed against the lower surface of the flange 2a of the lower bottomed tubular member 2 with a constant pressing force by the contraction operation of the cylinder rod 14a of the cylinder 14. The pressing force of the lower pressure roller 7 is received by the arm of the multi-axis robot, so that the upper pressure roller 6 does not move upward, and the upper surface of the flange 1a of the upper bottomed tubular member 1 does not move upward. Will be pressed. As a result, the upper and lower pressure rollers 6 and 7 are fixed to the upper surface of the flange 1a of the upper-bottomed tubular member 1 and the lower surface of the flange 2a of the lower-bottomed tubular member 2, respectively. The flanges 1a and 2a are clamped by being pressed with a pressing force that is such that there is no gap between the two flanges 1a and 2a in the portion pressed by the lower pressure rollers 6 and 7 or in the vicinity thereof. Then, the upper and lower pressure rollers 6 and 7 are moved by the arm of the multi-axis robot in the circumferential direction of the flange along the upper surface of the flange 1a of the upper bottomed cylindrical member 1, While sandwiching both flanges 1a and 2a, the upper bottom cylindrical member 1 is moved on the upper surface of the flange 1a and the lower bottom cylindrical member 2 on the lower surface of the flange 2a in the circumferential direction of the flange. Become. At this time, the upper and lower bottomed cylindrical members 1 and 2 are fixed by fixing members (not shown) so as not to move with the movement of the arm of the multi-axis robot.
[0024]
The laser head 8 is supported by a head support member 31 that is mounted and fixed across the mounting member 5 and the upper end portion of the roller support member 11. In the laser head 8, a laser condenser lens 35 and a focus adjusting mechanism (not shown) for adjusting the focus by moving the laser condenser lens 35 are disposed. The distance between the laser condenser lens 35 and the upper surface of the flange 1a of the upper bottomed cylindrical member 1 is adjusted in advance so as to be substantially the same as the focal length of the laser condenser lens 35. As a result, the laser light introduced into the laser head 8 by the optical fiber 36 is emitted from the laser head 8 through the laser condensing lens 35, and is roughly on the flange 1 a of the upper bottomed tubular member 1. Focus on the top surface.
[0025]
Since the laser head 8 is attached and fixed to the roller support member 11 together with the upper pressure roller 6, the laser head 8 is connected to the flange 1a of the upper bottomed cylindrical member 1 in conjunction with the movement of the upper pressure roller 6. It moves in the flange circumferential direction along the upper surface. The laser head 8 moves in the circumferential direction of the flange together with the upper pressure roller 6, and in the vicinity of the upper pressure roller contact portion at the substantially center portion in the flange width direction on the upper surface of the flange 1 a of the upper bottomed tubular member 1. In this embodiment, the laser beam is emitted toward the rear side in the movement direction of the upper pressure roller 6 and is continuously welded in the circumferential direction of the flange (see FIG. 2). . Thereby, the laser beam is always irradiated to the portion where the mating surfaces of the two flanges 1a and 2a are in close contact with each other by the pressing of the upper and lower pressure rollers 6 and 7. When the upper pressure roller 6 makes one round of the upper surface of the flange 1a, the groove 6b of the upper pressure roller 6 does not press the welded portion (bead) on the upper surface of the flange 1a. The pressure roller 7 is also configured not to press the welded portion (bead) on the lower surface of the flange 2a by the groove 7b.
[0026]
The roller support member 11 is fixedly attached with a gas supply pipe 41 for supplying a shield gas to the irradiated portion of the laser beam on the upper surface of the flange 1a of the upper-bottomed cylindrical member 1. The gas supply pipe The upstream end of 41 is connected to a shield gas supply source (not shown), while the downstream end is positioned in the vicinity of the laser light irradiation portion.
[0027]
A rotation speed detection mechanism 45 (rotation speed detection means) for detecting the rotation speed of the upper pressure roller 6 is attached to the tip of the rotation shaft 6a of the upper pressure roller 6 and this rotation speed detection mechanism. The output of the laser beam emitted from the laser head 8 changes in accordance with the rotational speed detected by 45. That is, when the rotation speed of the upper pressure roller 6 is slow and the movement speed is slow, the output of the laser beam is reduced. On the other hand, when the rotation speed of the upper pressure roller 6 is high and the movement speed is high, the laser is reduced. By increasing the light output (that is, increasing the output of the laser light as the rotational speed of the upper pressure roller 6 increases), the amount of heat generated at the processing point is made constant. The rotational speed detecting mechanism 45 may be provided on the rotary shaft 7a of the lower pressure roller 7 instead of being provided on the rotary shaft 6a of the upper pressure roller 6, or both rotational speeds. The output of the laser light emitted from the laser head 8 may be changed according to the average value of the rotational speeds detected by the detection mechanism 45.
[0028]
In order to laser weld the flanges 1a and 2a of the two bottomed cylindrical members 1 and 2 using the laser welding apparatus, first, the mounting member 11 is positioned at a predetermined position by an arm of a multi-axis robot, The cylinder rod 14a of the cylinder 14 is extended to separate the upper pressure roller 6 and the lower pressure roller 7 from each other.
[0029]
Subsequently, both flanges 1a and 2a are inserted between the upper pressure roller 6 and the lower pressure roller 7 with the mating surfaces aligned with each other, and then the cylinder rod of the cylinder 14 is inserted. 14a is contracted, and both flanges 1a and 2a (which may be any part in the circumferential direction of the flange) are sandwiched between upper and lower pressure rollers 6 and 7. Further, both the bottomed cylindrical members 1 and 2 are fixed by a fixing member so as not to move with the movement of the arm of the multi-axis robot.
[0030]
Next, the mounting member 11 is moved from the predetermined position along the upper surface of the flange 1 a of the upper bottomed tubular member 1 in the circumferential direction of the flange by the arm of the multi-axis robot, and laser light is emitted from the laser head 8. As a result, the upper and lower pressure rollers 6 and 7 move on the upper surface of the flange 1a and the lower surface of the flange 2a while rolling between the flanges 1a and 2a in the circumferential direction of the flange. Laser light is irradiated in the vicinity of the upper pressure roller contact portion on the upper surface of 1a and is continuously welded in the circumferential direction of the flange.
[0031]
At this time, the laser beam is irradiated in the vicinity of the upper pressure roller contact portion where the mating surfaces of the two flanges 1a and 2a are in close contact with each other by pressing of the upper and lower pressure rollers 6 and 7. Therefore, the welding quality does not deteriorate due to the large gap between the flanges 1a and 2a. Further, since the laser head 8 moves in the circumferential direction of the flange along the upper surface of the flange 1a of the upper bottomed cylindrical member 1 in conjunction with the upper pressure roller 6, the laser beam is always near the upper pressure roller contact portion. The distance between the laser condensing lens 35 in the laser head 8 and the upper surface (processed surface) of the flange 1a of the upper bottomed cylindrical member 1 and the incident angle of the laser beam on the processed surface (In this embodiment, laser light is incident at a right angle to the processing surface) can be maintained constant. As a result, the welding quality does not vary due to the change in the distance and the incident angle.
[0032]
Then, when the mounting member 11 returns to the original predetermined position, the movement of the mounting member 11 and the emission of the laser light are stopped. By the above operation, the two flanges 1a, 2a are welded over the entire circumference of the flanges 1a, 2a (entire flange length direction).
[0033]
Therefore, in the above embodiment, since the flanges 1a and 2a of the two bottomed cylindrical members 1 and 2 are laser-welded, the width (radial direction) of each flange 1a and 2a is compared with the conventional resistance welding. Projecting amount) can be reduced, and the material cost can be reduced and the fuel storage efficiency per unit area can be improved. In addition, interference between the welding apparatus and the fuel tank hardly occurs, the degree of freedom in designing the fuel tank can be improved, and sealing performance can be ensured only by laser welding. Furthermore, depending on the laser output, the welding speed can be improved compared to resistance welding, and low heat input is sufficient, and deformation of the bottomed cylindrical members 1 and 2 due to heat can be suppressed. In addition, unlike resistance welding in which electrodes are brought into contact with each other, stable welding quality can be obtained without changing welding conditions (resistance at the electrode tip) due to the influence of plating or the like.
[0034]
On the other hand, although laser welding is advantageous as compared with resistance welding as described above, since the surface accuracy of the flanges 1a and 2a is relatively low only by performing laser welding, there is a gap between the flanges 1a and 2a. Or the distance between the laser condensing lens 35 in the laser head 8 and the processing surface and the incident angle of the laser beam on the processing surface are changed, and uniform and good over the entire circumference of the flanges 1a and 2a. There is a high possibility that a high welding quality cannot be obtained.
[0035]
However, in the above embodiment, the upper and lower pressure rollers 6 and 7 irradiate the laser beam to the portion where the gap between the flanges 1a and 2a is eliminated, and the laser head 8 is interlocked with the upper pressure roller 6. Thus, the distance between the laser condensing lens 35 and the processing surface and the incident angle of the laser beam on the processing surface are kept constant, so that there is no cause for deterioration of the welding quality, and the flanges 1a and 2a are all Uniform and good welding quality can be obtained over the circumference.
[0036]
In the above embodiment, only one upper and lower pressure rollers 6 and 7 are provided. However, as shown in FIG. 3, for example, the upper pressure roller 6 is connected to the laser head 8 in the flange circumferential direction. Two lower pressure rollers 7 are provided at lower positions corresponding to the upper pressure rollers 6, respectively, on the upper surface of the flange 1 a of the upper bottomed tubular member 1. A laser beam may be irradiated between the two upper pressure roller contact portions (the two upper pressure rollers 6 are configured not to press the welded portion on the upper surface of the flange 1a by the groove 6b. In addition, the two lower pressure rollers 7 are also configured not to press the welded portion on the lower surface of the flange 2a by the groove 7b). Alternatively, as shown in FIG. 4, two upper pressure rollers 6 are provided, and one relatively large-diameter lower pressure roller 7 capable of sandwiching both flanges 1 a and 2 a together with the upper pressure rollers 6. You may make it provide. Thus, if both the flanges 1a and 2a are clamped at two locations in the circumferential direction of the flange and the portion between them is irradiated with the laser beam, the joining surface of the two flanges 1a and 2a in the irradiated portion of the laser beam Adhesion can be further improved.
[0037]
In the above embodiment, the laser head 8 is interlocked with the upper pressure roller 6. However, the laser head 8 is attached to and fixed to the movable member 21 to be interlocked with the lower pressure roller 7. The bottom cylindrical member 2 may be moved in the flange circumferential direction along the lower surface of the flange 2a. In this case, the laser head 8 may be configured to emit laser light toward the vicinity of the lower pressure roller contact portion on the lower surface of the flange 2a of the lower bottomed cylindrical member 2.
[0038]
Furthermore, in the above embodiment, the laser welding apparatus laser welds the flanges 1a and 2a of the two bottomed cylindrical members 1 and 2 constituting the fuel tank. The members to be joined are not limited to the two bottomed cylindrical members 1 and 2 constituting the fuel tank, and may be any member, and may not have a flange formed over the entire circumference. . And when sealing property is not required, it is also possible to perform stitch welding by irradiating laser light (pulse irradiation) intermittently while moving the laser head 8 in the flange length direction. In comparison with the conventional continuous spot welding method, the welding speed can be improved.
[0039]
【The invention's effect】
As described above, according to the laser welding apparatus of the present invention, while the two flanges are pressed against the respective surfaces opposite to the mating surfaces of the two flanges mated with each other, A plurality of pressure rollers configured to roll and move on each surface in the length direction of the flange, and the alignment in the one flange in conjunction with the movement of the pressure roller located on the one flange side. A laser head configured to move in the flange length direction along a surface opposite to the surface, and to emit laser light toward the vicinity of the pressure roller contact portion on the surface. Thus, the flanges of the two members to be joined that are joined together by the flange can be laser-welded uniformly and satisfactorily over the entire length direction of the flange.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a laser welding apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a positional relationship between a pressure roller and a laser head.
FIG. 3 is a view corresponding to FIG. 2 when two upper and lower pressure rollers are provided.
FIG. 4 is a view corresponding to FIG. 2 when two flanges are sandwiched between two upper pressure rollers and one lower pressure roller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper bottomed cylindrical member 1a Flange 2 Lower bottomed cylindrical member 2a Flange 6 Upper pressure roller 7 Lower pressure roller 8 Laser head 45 Rotational speed detection mechanism (rotational speed detection means)

Claims (2)

A laser welding apparatus that joins the flanges of two members to be joined that are joined together by a flange by laser welding in a state where the mating surfaces of the two flanges are joined to each other.
The above-mentioned mating surfaces are rolled against each other in the length direction of the flange while holding both flanges by being pressed against the opposite surfaces of the two flanges mated to each other. A plurality of pressure rollers configured to:
In conjunction with the movement of the pressure roller located on the one flange side, it is configured to move in the flange length direction along the surface on the opposite side of the mating surface of the one flange. A laser welding apparatus comprising: a laser head that emits laser light toward the vicinity of the pressure roller contact portion. The laser welding apparatus according to claim 1, wherein
A rotation speed detecting means for detecting the rotation speed of the pressure roller;
A laser welding apparatus configured to change an output of laser light emitted from a laser head in accordance with a rotational speed detected by the rotational speed detecting means.

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