JPH06234089A - Laser beam seam welding machine - Google Patents

Abstract

(57) [Summary] [Objective] To establish laser seam welding that enables continuous seam welding instead of conventional spot seam welding. A clamp unit 11 for clamping an overlapping portion Wa of a workpiece W and a laser torch 12 for irradiating the workpiece W with a laser through the clamp unit 11.
The arm 31 of the robot 30 is provided with, and the clamp unit 11 has a configuration in which a plurality of balls 18 are arranged on the clamp surfaces of the pair of clamp members 15 and 16, and is mounted on the rotary table 41 by the clamp unit 11. After holding the overlapped portion Wa of the workpiece W, the clamp unit 11 is moved along the overlapped portion Wa by the robot operation, and the laser is emitted from the laser torch 12 during this time to perform continuous fusion welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser seam welding machine for carrying out laser seam welding, which is an advanced version of seam welding.

[0002]

2. Description of the Related Art Conventionally, fuel tanks for automobiles, for example, have been manufactured by utilizing seam welding. FIG. 3 shows a seam welding device used for manufacturing the fuel tank, and includes a work supporting device 1 for positioning and supporting the workpiece W, and a seam welding machine 2 installed adjacent to the work supporting device 1. It is composed of The workpiece W is
Upper container 3 and lower container 4 formed separately by drawing
And flanges 3a, 4a provided on the outer circumference of each container
The rotary table 5 of the work supporting device 1 in a state where they are overlapped with each other.
Placed on top. Rotary table 5 of work supporting device 1
Are rotatably supported by a support base 6 which is linearly movable in two horizontal directions. On the other hand, the seam welding machine 2 includes a pair of disc-shaped rotating electrodes 7 and an overlapping portion (3a, 3a,
4a) is provided with a pressing mechanism (not shown) that relatively moves the pair of rotating electrodes 7 and a power supply mechanism (not shown) that supplies electric power to the rotating electrodes 7. A similar seam welding machine 2 is disclosed in Japanese Utility Model Publication No. 59-49480 and Japanese Utility Model Publication No. 60-34381.

In the seam welding apparatus constructed as described above, the upper container 3 and the lower container 4 which are the objects to be welded W are superposed and placed on the rotary table 5 of the work supporting device 1, and then the seam welding machine. The pair of rotating electrodes 7 of 2 holds the overlapped portions (flange 3a, 4a) of the workpiece W, and thereafter, the linear movement of the support base 6 and the rotary table 5 are performed.
When the electric power is intermittently supplied to the rotating electrode 7 while moving the workpiece W by the rotating operation of the above, the superposed surfaces of the flange 3a of the upper container 3 and the flange 4a of the lower container 4 are spot-heated and resistance-heated. As shown in FIG. 4, the nugget 8 is continuously (spot-likely) formed on the overlapping surface, and the workpiece W is integrated.

[0004]

By the way, in such seam welding, the welding quality (adhesion) largely depends on the size and pitch of the nugget 8. Therefore, in order to secure a good welding quality, a desired welding quality is required. It is necessary to strictly control the welding conditions and the feed rate of the workpiece to obtain the nugget 8 having the desired pitch and pitch. However, when the upper container 3 and the lower container 4 obtained by drawing as described above are used as the objects to be welded, the electrode height is constantly changed due to the waviness (waviness) of the flanges 3a and 4a. Since the pressing force of the surface is constantly changing and there are subtle irregularities on the flanges 3a, 4a, it is unavoidable that gaps are created on the overlapping surfaces of the two, and the welding becomes unstable and the size of the nugget is increased. Variation occurs, or a weld cut occurs in which no nugget is formed, and it is difficult to stably secure good welding quality only by managing the above-mentioned welding conditions and the feed rate of the workpiece. there were. In order to solve this problem, the holding force by the pair of rotating electrodes 7 should be increased.
In this case, not only is it difficult to move the workpiece W,
Distortion easily occurs in the workpiece W, and a fundamental solution cannot be achieved.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to enable continuous seam welding instead of the conventional spot-like seam welding. It is to provide a laser seam welder that greatly contributes to secure stable welding quality.

[0006]

In order to achieve the above object, the present invention comprises a clamp unit for clamping an object to be welded and an irradiation unit for irradiating the object to be welded with a laser through the clamp unit. Is provided with a pair of clamp members arranged so that they can approach and separate from each other, and a rolling element arranged so as to be rollable on the clamp surface of each of the clamp members, and the irradiation unit,
A laser oscillator, a laser torch mounted on either one of the pair of clamp members so as to be orthogonal to the clamp surface, and an optical fiber for guiding the laser emitted from the laser oscillator to the laser torch. It is characterized by

[0007]

In the laser seam welding machine configured as described above, the penetration depth is intensively increased by irradiating with a laser having a high energy density, and there are undulations and some gaps in the overlapping portion of the objects to be welded. However, sufficient weldability can be ensured, and by continuously performing the laser irradiation on the overlapping portion of the objects to be welded, the weld beads are continuously formed.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2 show a welding apparatus including a laser seam welder according to the present invention. The present embodiment is used for manufacturing the fuel tank described above, and since the workpiece W is the same as that described above, the same reference numerals as above are used here.
In FIG. 1 and FIG. 2, 10 is a laser seam welding machine according to the present invention, 30 is a welding robot equipped with a clamp unit 11 and a laser torch 12 constituting the laser seam welding machine 10, and 40 is a welded object. It is a work supporting device for positioning and supporting the object W.

The clamp unit 11 includes a support block 13 attached to the tip of an articulated arm 31 of the robot 30,
A clamp cylinder (here, an air cylinder) 14 disposed below the support block 13 and having a tip of a piston rod 14a connected to the support block 14, a fixed clamp member 15 attached to the support block 13, There is provided a movable clamp member 16 attached to the outer wall of the cylinder 14 so as to face the fixed clamp member 15. A piston (not shown) that is coupled to the base end of a piston rod 14a is slidably arranged in the cylinder 14, and compressed air is supplied to and discharged from two chambers in the cylinder 14 defined by the piston. As a result, the cylinder moves along the piston rod 14a, so that the movable clamp member 16 moves toward and away from the fixed clamp member 15.

Fixed clamp member 15 and movable clamp member 16
Are formed in a U-shape, and the end surfaces (clamping surfaces) of the U-shaped legs are opposed to each other. As shown in FIG. 2, a pair of hemispherical grooves 17 are formed on the clamping surfaces of the fixed and movable clamp members 15 and 16, and a ball (rolling element) 18 rolls in each groove 17. It is installed as possible. As a result, the overlapping portion Wa of the workpiece W composed of the flanges 3a and 4a is positioned between the fixed and movable clamp members 15 and 16, and the movable clamp member 16 is moved relative to the fixed clamp member 15 by the operation of the cylinder 14. When the balls 18 are brought close to each other, the balls 18 come into contact with the workpiece W. That is, the pair of clamp members 15 and 16 indirectly hold the overlapped portion Wa of the workpiece W through the ball 18, and the clamp unit
11 can move on the overlapping portion Wa of the workpiece W while maintaining this holding state.

Further, the fixed clamp member 15 of the clamp unit 11 is provided with a through hole 19 which opens into a central groove having a U-shape extending in a direction orthogonal to the clamp surface (FIG. 2). The laser torch 12 is inserted in the through hole 19.
Is inserted and fixed. The laser torch 12 constitutes an irradiation unit for irradiating the object to be welded with a laser, to which a laser oscillator 20 installed apart from the robot 30 is connected via an optical fiber 21.

On the other hand, the work supporting device 40 comprises a rotary table 41 for placing and supporting the workpiece W and a pressure table 42 for pressing the workpiece W against the rotary table 41. The rotary table 41 is fixed to the upper end of a rotary shaft 45 that is rotationally driven by a driving means provided in a base 44 on the floor 43, and is designed to rotate integrally with the rotary shaft 45. The pressure table 42 is rotatably connected to a piston rod 47a of a cylinder 47 mounted on an upper portion of an L-shaped support frame 46 provided upright on the floor 43. As a result, the workpiece W is now placed on the rotary table 41,
When the pressurizing table 42 is moved downward by the operation of the cylinder 47, the main body of the workpiece W is held between the two tables 41 and 42, and if the rotary table 41 is rotated under this state, The object to be welded W rotates integrally with both tables 41 and 42.

However, the welding robot 30 is of a teaching playback type, and its operation is controlled by a robot controller 32 which is separately installed. The robot control device 32 has a work control circuit (not shown) for controlling the operation timing of the rotary shaft 45 incorporated therein.

The operation of the welding device configured as described above will be described below.

In welding, the upper container 3 and the lower container 4, which are the objects to be welded W, are stacked and placed on the rotary table 41 of the work supporting device 40, and then the pressure table 42 is lowered by the operation of the cylinder 47. The main body of the workpiece W is held between the two tables 41 and 42 by moving the table. Next, the welding robot
When the arm 30 is started, its arm 31 moves according to the teaching contents, and the clamp unit 11 causes the overlapping part W of the workpiece W to overlap.
It is moved to one end side of one straight line portion of a. At this time,
The fixed clamp member 15 of the clamp unit 11 is positioned at a position in contact with the upper surface of the overlapping portion Wa of the workpiece W via the ball 18, and the movable clamp member 16 is positioned at a position apart from the lower surface of the overlapping portion Wa. To be done. Then, at that position, the movable clamp member 16 approaches the fixed clamp member 15 by the operation of the clamp cylinder 14,
The ball 18 of the movable clamp member 16 contacts the overlapping portion Wa of the workpiece W, and the overlapping portion Wa of the workpiece W is sandwiched between the clamp members 15 and 16 via the ball 18.

Then, the laser oscillator 20 to the optical fiber 21
A laser is sent to the laser torch 12 via the robot torch 12, and at the same time, the arm 31 of the robot 30 moves according to the teaching contents, and the clamp unit 11 linearly moves along the overlapping portion Wa of the workpiece W at a constant speed. The laser sent from the laser oscillator 20 is fed from the laser torch 12 to the overlapping portion W.
a is irradiated vertically, whereby the irradiation portion of the flange 3a of the upper container 3 is first melted intensively, the melting proceeds to the flange 4a of the lower container 4, and then the movement of the clamp unit 11, that is, the laser torch. The molten material is sequentially solidified in accordance with the movement of 12, and the weld beads are continuously formed.

Then, when the laser torch 12 moves to the other end of one straight line portion of the overlapping portion Wa of the workpiece W, the work support device 40 is instructed by the robot control device 32.
The rotary table 41 inside rotates, and in synchronization with this, the robot
The arm 31 of 30 moves and the clamp unit 11 moves two-dimensionally with respect to the workpiece W, which causes the laser torch.
12 moves along the rotation locus of the corner portion of the overlapping portion Wa, and the welding of the corner portion is performed. After that, when the workpiece W is rotated by 90 degrees, the laser torch 12 is again linearly moved at a constant speed along the overlapping portion Wa by the operation of the robot 30, and during this, welding is continuously performed.
By repeating such an operation, laser welding is completed for the entire circumference of the overlapping portion Wa of the workpiece W. Then, since fusion is advanced from the flange 3a of the upper container 3 to the flange 4a of the lower container 4, fusion bonding is performed,
Sufficient weldability can be secured even if there are some gaps in the overlapping portion of the two, and there is no problem such as liquid leakage when used as a fuel tank.

Although the robot 30 is provided with the clamp unit 11 and the laser torch 12 in the above embodiment, this is because the versatility of the equipment is emphasized. It may be provided in a fixed facility such as the seam welder (Fig. 3). Further, in the above embodiment, the balls 18 are mounted on the clamp surfaces of the fixed and movable clamp members 15 and 16, but rollers may be used instead of the balls 18. Further, the application target of the present invention is arbitrary,
Of course, instead of manufacturing the fuel tank, it can be used for manufacturing other products.

[0020]

As described above in detail, according to the laser seam welding machine of the present invention, a laser having a high energy density is irradiated to continuously melt-bond the overlapping portions of the objects to be welded. Therefore, even if there are some gaps in the overlapped portion, sufficient weldability can be secured,
This has the effect of ensuring good welding quality in a stable manner. Moreover, unlike the conventional spot seam welding, it is not necessary to strictly control the welding conditions and the feed rate of the workpiece,
This has the effect of greatly improving workability.

[Brief description of drawings]

FIG. 1 is a perspective view showing a welding apparatus including a laser seam welder according to the present invention.

FIG. 2 is a cross-sectional view showing a main structure of the present laser seam welding machine.

FIG. 3 is a perspective view showing a welding device including a conventional seam welder.

FIG. 4 is a schematic diagram showing a welding mechanism in conventional seam welding.

[Explanation of symbols]

 10 Laser seam welder 11 Clamp unit 12 Laser torch 14 Clamping cylinder 15 Fixed clamp member 16 Movable clamp member 18 Ball (rolling element) 20 Laser transmitter 21 Optical fiber 30 Robot 40 Workpiece support device W Welding object Wa Overlapping part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B23K 37/047 501 A 7011-4E (72) Inventor Tsuneharu Umeda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd.

Claims (1)

[Claims] 1. A pair of clamps, each of which comprises a clamp unit for clamping an object to be welded and an irradiation unit for irradiating the object to be welded with a laser through the clamp unit, the clamp units being arranged so as to be able to approach and separate from each other. A member and a rolling element rotatably arranged on the clamp surface of each of the clamp members, and the irradiation unit includes a laser oscillator and one of the pair of clamp members which is orthogonal to the clamp surface. A laser seam welding machine, which is equipped with a laser torch mounted as described above, and an optical fiber for guiding the laser emitted from the laser oscillator to the laser torch.