JP2004066268A - Laser welding method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the occurrence of defective welding by reducing a space between two overlapped members to be welded while maintaining an advantage that a work is welded only from one side thereof. <P>SOLUTION: In a lap welding in which a work 2 and laser beams 1a are moved in a direction of a welding line 21 while the work 2 with overlapped members 2a and 2b formed of a magnetic material is irradiated with laser beams 1a, and a portion near the welding line 21 of the work 2 is pressed by a press roller 3 from the laser beams irradiation side (a face side), a magnet roller 6 is provided on the face side. The magnet roller 6 is fitted to a torch 1 so as to rotatively travel on the work 2 while attracting the member 2b on a back side toward the member 2a on the face side by the magnetic force in a vicinity of the welding line facing the press roller 3 across the welding line 21. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser welding method and apparatus suitable for lap welding of a plurality of plate materials.
[0002]
[Prior art]
In recent years, laser welding using a laser beam has come to be adopted for overlap welding of a plurality of plate materials. For example, both joint portions of two panel members constituting a body of a vehicle such as an automobile are overlapped, and overlap welding of the joint portions is often performed by laser welding.
When performing overlap welding of such a plurality of plate materials using a laser beam, poor welding occurs if the overlapped joint portions that are welded portions are not sufficiently in close contact with each other.
However, in the case of lap welding of members that are easily bent and easily deformed, such as panel materials, and members that are prone to unstable processing shapes, such as press-worked products, Irregular gaps are likely to occur.
In view of this, there has been proposed a technique of performing laser welding while pressing the overlapped members with a pressure roller (see JP-A-10-225784, JP-A-11-267872, etc.).
[0003]
[Problems to be solved by the invention]
However, in the above prior art, a plurality of members are pressed only from one side where the pressure roller is provided, and the gap between the two members is to be corrected.
For this reason, when a plurality of members on which the pressure roller is overlapped are pressed, even if the member on the side in contact with the pressure roller is pressed, the member on the side away from the pressure roller moves away in the pressing direction. End up.
Therefore, the gap between the two members is not so much as you can imagine, and the generation of irregular gaps along the welding direction (gap fluctuation) causes a phenomenon of welding failure such as shrinkage and burnout.
In order to solve this problem, in addition to the laser irradiation side, a pressure roller or the like may be provided on the opposite side, and a plurality of overlapped members may be pressed from both sides to eliminate gaps. . However, this method does not take advantage of laser welding, which allows welding from only one side of the work piece (welding operation, installation of welding means), and pressurizes the side opposite to the laser irradiation side. There was an environment where a roller or the like could not be provided, and it could not be adopted.
[0004]
The present invention has been made to solve the above-described problems of the prior art, and maintains the advantage that welding from only one side of an object to be welded is possible, while maintaining a plurality of overlapped members to be welded. It is an object of the present invention to provide a laser welding method and apparatus that can reduce the occurrence of gaps, particularly the occurrence of irregular gaps (gap fluctuation) along the welding direction between the members to be welded, and the occurrence of poor welding.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is directed to irradiating the workpiece to be welded and / or the laser beam while irradiating the workpiece to which the plurality of workpieces made of a magnetic material are superimposed. In the laser welding method in which the welding object is overlapped and welded while moving in the welding line direction and pressing the vicinity of the welding line of the welding object from the laser beam irradiation side, the pressing is performed across the welding line of the welding object. A member to be welded located near the welding line opposite to the laser beam irradiation side and opposite to the laser beam irradiation side is attracted from the laser beam irradiation side to the welding member side of the laser beam irradiation side by a magnetic force. It is characterized by welding.
[0006]
According to a second aspect of the present invention, the workpiece and / or the laser beam is moved in the welding line direction while irradiating the workpiece to which the plurality of workpieces made of magnetic material are superimposed with each other, and In a laser welding apparatus that welds the workpiece to be welded while pressing the vicinity of the weld line of the workpiece from the laser beam irradiation side with a pressure roller, the laser welding device is positioned on the laser beam irradiation side and is welded during welding. While attracting a member to be welded located on the opposite side of the laser beam irradiation side in the vicinity of the welding line on the opposite side of the pressure roller across the welding line to the laser beam irradiation side of the welding member side by magnetic force, It comprises a magnet roller that rotates on the work piece.
[0007]
According to a third aspect of the present invention, in the second aspect of the present invention, the magnet roller is constituted by an electromagnet, and the magnet roller is positioned on the opposite side to the laser irradiation side of the member to be welded on the laser beam irradiation side. A through-hole for directly contacting and sucking a member to be welded is intermittently formed along the weld line, and the magnet roller is energized only while the magnet roller passes through the through-hole. It is characterized by being turned on.
[0008]
According to a fourth aspect of the present invention, in the third aspect of the present invention, the magnet roller is moved to a standby position during the energization OFF period of the magnet roller.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view of an embodiment of an apparatus (invention apparatus) to which a laser welding method according to the present invention is applied, and FIG. 2 is a plan view showing a part to be welded in FIG. In addition, the to-be-welded object of FIG. 1 is the enlarged view which looked at the II sectional view in FIG. 2 from the arrow direction.
In FIG. 1, reference numeral 1 denotes a laser welding torch which performs welding by irradiating a workpiece 2 with a laser beam (light) 1 a from the torch 1.
The work piece 2 has a plurality of welded members made of a magnetic material, in this case, a part (joint part) of two mild steel plates 2a and 2b having a thickness of about 0.5 to 1.5 mm. The welding is performed by irradiating the lap joint portion 2c of the workpiece 2 (soft steel plates 2a, 2b) with the laser beam 1a.
As the laser device, a carbon dioxide gas laser device or a YAG laser device is used, and either or both of the torch 1 and the workpiece 2 are moved, and welding is performed by moving the torch 1 in a direction perpendicular to the illustrated surface. The example which performs is shown.
[0010]
The pressure roller 3 presses the vicinity of the weld line 21 of the workpiece 2 as indicated by an arrow a so as to correct the gap between the two mild steel plates 2a and 2b during laser welding, while welding the workpiece. 2 A disk-shaped roller that rotates on the upper surface.
The pressure roller 3 is disposed so as to press the two mild steel plates 2a and 2b from the upper side to the lower side in the drawing, that is, press from the laser beam irradiation side, and welding from only one side of the workpiece 2 ( It is provided so as not to lose the advantage of laser welding that welding work and installation of welding means are possible.
Specifically, the pressure roller 3 is rotatably supported by the torch 1 via the pressing arm 4 (see arrow B), and the workpiece 2 is pressed from the laser beam irradiation side during laser welding. It is configured to satisfy the condition of performing.
The pressing arm 4 is provided with a pressure roller raising / lowering device 5 composed of, for example, a hydraulic drive mechanism for moving the pressure roller 3 to a desired position in the vertical direction (see arrow C) in the figure. During the welding, the pressure roller 3 is basically retracted so that the position level L1 of the lower surface thereof matches the position level L2 of the focal point of the laser beam 1a and away from the workpiece 2 when not in use. As described above, the position is controlled by the pressure roller lifting / lowering device 5.
[0011]
The magnet roller 6 is a disc-shaped roller that more reliably corrects the gap between the two mild steel plates 2a and 2b during laser welding. That is, the magnet roller 6 is a mild steel plate (back side mild steel plate) located on the opposite side of the laser beam irradiation side in the vicinity of the welding line 21 opposite to the pressure roller 3 across the welding line 21 of the workpiece 2. ) A roller that rotates on the work piece 2 while attracting 2b to the mild steel plate (front side mild steel plate) 2a side by the magnetic force (see arrow D).
This magnet roller 6 is arranged on the laser beam irradiation side so as to attract the back side mild steel plate 2b from the laser beam irradiation side, and welding (welding work, installation of welding means) from only one side of the workpiece 2 is possible. It is provided so as not to lose the advantage of laser welding.
Specifically, the magnet roller 6 is supported and fixed to the torch 1 via the suction side arm 7 so as to be freely rotatable (see arrow E), and the workpiece 2 is attracted from the laser beam irradiation side during laser welding. It is configured to satisfy the condition.
The attraction side arm 7 is provided with a magnet roller lifting / lowering device 8 composed of, for example, a hydraulic drive mechanism for moving the magnet roller 6 to a desired position in the vertical direction (see arrow) in the figure.
[0012]
In this example, the magnet roller 6 is composed of an electromagnet, and as shown in FIG. 2, the magnet roller 6 penetrates the front side mild steel plate 2a and directly contacts the back side mild steel plate 2b as shown in FIG. Through holes 22 are formed intermittently along the weld line 21.
Then, energization of the magnet roller 6 is turned on only while the magnet roller 6 is passing through the through-hole 22, and the magnet roller 6 is raised to the standby position during the energization OFF period of the magnet roller 6. It is configured. That is, the magnet roller 6 is lowered / synchronized with the portion with and without the through hole 22 such that the portion with the through hole 22 is lowered and energized ON, and the portion with the through hole 22 is raised and energized OFF. It is configured to turn up and turn on / off.
If the energization of the magnet roller 6 is turned off in synchronism with the portion without the through hole 22, a period in which the magnet roller 6 does not attract the back-side mild steel plate 2b occurs periodically, so that the welding speed can be increased. Further, if the magnet roller 6 is raised during the energization OFF period, a period in which the magnet roller 6 does not contact the back-side mild steel plate 2b occurs periodically, so that the welding speed can be further increased.
[0013]
Thus, the magnet roller 6 descends and rises, but the position level L3 of the descending point of the magnet roller 6 is basically the position level of the lower surface of the front mild steel plate 2a (the position level L1 of the lower surface of the pressure roller 3). It is controlled so as to be kept constant at a position level L4 including the thickness of the front mild steel plate 2a. In order to enable this control, for example, it is effective to control the attraction force (magnetic force) of the magnet roller 6 and the pressing force of the pressure roller 3 to be substantially equal. According to this, the focal position of the laser beam 1a is There is no change and welding is performed stably.
[0014]
In order to superimpose the front and back mild steel plates 2a and 2b without gaps, it is preferable that the magnetic force of the magnet roller 6 is strong. However, if it is too strong, there is a problem such as bending the laser beam 1a. It is set to an appropriate strength within a range where no occurrence occurs. The diameter, thickness, or strength of magnetic force (attraction force) of the magnet roller 6 is appropriately set depending on the thickness and weight of the mild steel plates 2a and 2b, the welding speed, and the like. Of course, the width dimension d1 of the through hole 22 is set to be equal to or greater than the thickness d2 of the magnet roller 6, that is, the width at which the lower end of the magnet roller enters the through hole 22.
[0015]
Next, the operation of the above apparatus will be described.
Now, it is assumed that the pressure roller 3 and the energized magnet roller 6 are in the state shown in FIG. 1 with respect to the lap joint portion 2c of the workpiece 2 (front, back side mild steel plates 2a, 2b).
In this state, the pressure roller 3 presses the upper surface of the workpiece 2 (front-side mild steel plate 2a) downward, and the magnet roller 6 attracts the back-side mild steel plate 2b toward the front-side mild steel plate 2a by magnetic force. .
In this case, the pressure roller 3 and the magnet roller 6 are located close to each other with the weld line 21 of the work piece 2 interposed therebetween. Therefore, the front and back side mild steel plates 2a and 2b are weld lines of the lap joint portion 2c. At 21 positions, they are pinched in alternating directions and overlapped with no gaps.
When the welding operation starts in this state, that is, when the torch 1 emits the laser beam 1a and moves on the welding line 21 in the forward direction (in the direction of the arrow in FIG. 2) with respect to the illustrated surface, the front and back mild steel plates As for 2a and 2b, the gap | interval (gap fluctuation | variation) between mutual is corrected, and overlap welding is performed, reducing.
[0016]
In the illustrated example, the magnet roller 6 is composed of an electromagnet, and is controlled so that the portion with the through hole 22 is lowered and energized ON (suction ON), and the portion not provided is raised and energized OFF (suction OFF). Depending on the welding conditions, the energization ON state may be always set at the lowered position regardless of the presence or absence of the through hole 22.
When the welding margin of the front side mild steel plate 2a is small and the welding line 21 on the side of the front side mild steel plate 2a is close to the edge of the front side mild steel plate, the through hole 22 may be omitted. In this case, the magnet roller 6 may be always energized at the lowered position. In an environment where the energization is always turned on, a roller made of a permanent magnet may be used as the magnet roller 6.
In FIG. 2, a portion surrounded by a two-dot chain line sandwiching the welding line 21 is a portion where a bead is formed after welding.
[0017]
【The invention's effect】
As described above, in the present invention, the workpiece / laser beam is moved in the welding line direction while irradiating the workpiece to which the workpieces made of a magnetic material are superimposed with each other, and welding of the workpiece is performed. When the workpiece is overlapped and welded while pressing the vicinity of the line from the laser beam irradiation side, the laser beam irradiation side is near the welding line on the opposite side of the welding line across the welding line of the workpiece The member to be welded located on the opposite side of the laser beam is attracted from the laser beam irradiation side to the welding member side on the laser beam irradiation side by a magnetic force.
According to this, while maintaining the advantage that welding from only one side of an object to be welded is possible, generation of a gap between a plurality of overlapped members to be welded, particularly along the welding direction between these members to be welded. It is possible to reduce gap fluctuations and reduce the occurrence of welding defects.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment of an apparatus to which a laser welding method according to the present invention is applied.
FIG. 2 is a plan view showing a part to be welded in FIG. 1 in a reduced scale.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Torch for laser welding 1a Laser beam 2 Workpiece 2a, 2b Mild steel sheet (front, back side mild steel sheet)
3 Pressure roller 6 Magnet roller 21 Welding wire 22 Through hole

Claims (4)

The workpiece and / or the laser beam is moved in the direction of the welding line while irradiating the workpiece to which the plurality of workpieces made of magnetic material are overlapped with each other, and the vicinity of the welding line of the workpiece is laser-treated. In the laser welding method of welding the workpiece to be welded while pressing from the beam irradiation side,
A member to be welded located near the weld line on the opposite side to the side to be pressed across the weld line of the workpiece to be welded and on the opposite side to the laser beam irradiation side is subjected to the same laser by a magnetic force from the laser beam irradiation side. A laser welding method, wherein welding is performed while suctioning to a member to be welded on a beam irradiation side. The workpiece and / or the laser beam is moved in the direction of the welding line while irradiating the workpiece to which the plurality of workpieces made of magnetic material are overlapped with each other, and the vicinity of the welding line of the workpiece is laser-treated. In the laser welding apparatus that welds the workpiece to be welded while pressing with a pressure roller from the beam irradiation side,
A member to be welded is located on the laser beam irradiation side and in the vicinity of the welding line opposite to the pressure roller and on the opposite side to the laser beam irradiation side across the welding line of the workpiece during welding. A laser welding apparatus comprising: a magnet roller that rotates on a workpiece while being attracted toward a member to be welded on a laser beam irradiation side by a magnetic force. The magnet roller is composed of an electromagnet, and the welded member on the laser beam irradiation side has a through-hole through which the magnet roller directly contacts and attracts the welded member located on the opposite side of the laser irradiation side. The laser welding apparatus according to claim 2, wherein the energization of the magnet roller is turned on only while the magnet roller passes through the through hole and passes through the through hole. 4. The laser welding apparatus according to claim 3, wherein the magnet roller is moved to a standby position during the energization OFF period of the magnet roller.

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