JPH0716776A - Laser welding method and device of lap joint part - Google Patents

Abstract

PURPOSE:To improve the accuracy of a lap joint shape and to increase a welding area in the case of tight laser beam welding of sinks, fuel tanks for automobiles, etc. CONSTITUTION:The joint parts of members to be welded are powerfully clamped and are welded by irradiating the joint parts with a laser beam 6 from an extension line 5 of the contact surfaces of the clamped and superposed welded joint parts or a line having a slight angle with this extension line 5 in the case of welding of the joint parts of metallic plates 1, 2 superposed on each other by the laser beam. The gap between the plates of the lap joint parts is thus eliminated. Since the extremely marginal point of the weld line is clamped, the distortion at the time of welding is suppressed and dislocation is prevented. Since penetration is possible broadly in the extension line direction of the contact surfaces of the lap joint parts, the welding strength is additionally enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for welding a lap joint of a member to be welded by a laser beam.

[0002]

2. Description of the Related Art Conventionally, for example, a sink of a sink or a fuel tank of an automobile is composed of a plurality of welding members as shown in FIG.
The electrode wheel E is provided with a joint portion in which the metal plate 1 and the metal plate 2 are overlapped.
The seam welding method, in which pressure welding is performed while crushing by 1 and the electrode wheel E2, has been adopted. The reason for adopting this seam welding or the like is to facilitate the polishing work in the post process in the case of a sink sink and to ensure the welding strength. In addition, it is a big condition that the welding result can be surely obtained even if the accuracy of the joint shape is not good.

On the other hand, in laser beam welding, for example, as shown in FIG. 6, the end face of one of the members to be welded or the lap joint as shown in FIG.

[0004]

However, the former seam welding has the following problems. 1) Since the sink is pressed, the accuracy of the lap joint will deteriorate if the corner of the sink is distorted, and the welding electrode force for seam welding during welding will rise above a certain level due to the welding conditions. However, dust is sometimes generated due to insufficient pressurization, which may cause internal defects in the blowhole tower. 2) In seam welding, the cooling water of the electrode wheel disperses around and affects the working environment. 3) The electrode wheel must be maintained as a consumable item. 4) Since the seam weld has a wide heat-affected zone, thermal strain increases. 5) The seam welder is heavy and has limited automation.

On the other hand, the latter laser welding has the following problems. 1) In the end face welding shown in FIG. 6, it is necessary to improve the accuracy of the end face joint shape, and similarly to the laser penetration welding shown in FIG. 7, if there is a gap in the contact surface, the welding strength becomes extremely weak. 2) The melting width is narrow and it is difficult to grind after welding. 3) Further, in the case of continuous welding in the welding methods shown in FIGS. 6 and 7, there is a possibility that the focus will shift toward the welding end point due to welding distortion. In particular, in the case of FIG. 6, the welding line is misaligned.

[0006]

The present invention has developed a welding method and apparatus for solving the above-mentioned problems, and takes the following technical means. That is, when welding a lap joint with a laser beam, the joint of the members to be welded is strongly clamped, and the extension line of the contact surface of the welded portion that is clamped and overlapped or a line having a minute angle with the extension line. The main feature is to irradiate a laser beam to the joint and weld.

As an apparatus for carrying out the above method, a clamping device for clamping the lap joint portion of the member to be welded, and a tilt direction parallel or small with respect to the extension line of the contact surface of the clamped lap joint portion. To provide a laser welding apparatus equipped with an industrial robot that irradiates a laser beam from a laser beam and moves the laser beam along the locus of the welding line or an automatic machine such as a laser welding manipulator.

[0008]

According to the welding method of the present invention, a laser beam is irradiated from the direction of the extension line of the contact surfaces of the superposed metal plates or the direction of a slight inclination angle with respect to the extension line to perform welding. Therefore, it is possible to strongly clamp the place very close to the welding line, completely eliminate the gap between the plates of the lap joint, improve the joint accuracy, suppress distortion during welding, and prevent eye misalignment. It can be prevented. Further, since the penetration can be formed in the extension line direction of the joint portion, the fusion width of the joint portion is widened and the welding strength can be remarkably enhanced. In addition, if the melting width is wide, grinding finish processing becomes easy as well as seam welding.

Further, according to the apparatus for carrying out the method of the present invention, since the welding head portion is light and the automatic machine such as the industrial robot and the manipulator can be used, the manufacturing efficiency of the sink sink and the fuel tanks can be improved. Can be increased. In addition, it does not affect the working environment due to cooling water compared to seam welders. Further, since the chiller can be used for the clamp device, the heat capacity of the member to be welded can be adjusted, so that it can be prevented from falling off.

[0010]

1 to 4 are explanatory views showing an embodiment of the method of the present invention. Further, FIG. 5 is a schematic view of an apparatus for carrying out the present invention.

FIG. 1 shows a state in which a metal plate 1 and a metal plate 2 are overlapped with each other and a joint portion is clamped by an upper clamp 3 and a lower clamp 4. In this case, since the joint portion is pressed with a strong clamping force, for example, even if the metal plate is distorted due to the press working in the previous step, the welding line trajectory can be accurately secured without being affected by the distortion. That is, in the prior art, as shown in FIGS. 6 to 7, the laser beam 6 is directly above the joint (at right angles).
Since the irradiation is performed from above, it was not possible to install the clamp position as close as possible to the welding line, but with the method of the present invention, even if the end surface accuracy of the welding member is poor, the welding line is approached and welding is performed with sufficient clamping force. Since the wire is clamped, a highly accurate welded joint can be obtained and good welding results can be obtained.

FIG. 2 shows the irradiation angle of the laser beam 6 at the lap joint. In this case, even if the accuracy of the fillet end surface of the welded member is poor, after the joint is strongly clamped from the plate thickness direction as shown in Fig. 1, the extension line 5 of the contact surface on which the laser beams are overlapped is 0. Weld by irradiating from an angle of °. Therefore, since the clamp and the laser beam do not interfere with each other, the welding work is not hindered.

FIG. 3 shows a case where a laser beam 6 is irradiated to a processing position from an arbitrary inclination angle (for example, within a range of 10 ° to 20 °) with respect to an extension line 5 of a contact surface of two lap joints and welding is performed. An example is shown.

In the method described above, even if the metal plate on one side is a joint part that is overlapped with the flange plate having the sink part, the welding end face is clamped to the end of the weld end face with a strong clamping force from the plate thickness direction. Even if distortion occurs during press forming in the previous process, continuous welding can be performed without being affected by it, so as shown in Fig. 4, the melting width of the joint part spreads in the extension line direction, ensuring welding strength. To

Next, an apparatus for carrying out the method of the present invention will be described based on the embodiment shown in FIG. Reference numeral 7 denotes a laser oscillator, which generates an output laser energy set by a signal from a laser output setting device. Numerals 8 and 9 are light-reflecting mirrors for changing the laser beam 6 emitted from the laser oscillator by the reflection angle and irradiating it to a target processing position. Reference numeral 10 is an automatic machine such as an industrial robot or a manipulator that drives a laser beam along with a welding line along with a reflecting mirror for projection. Reference numeral 11 denotes a transmission path from the laser oscillator 7 to the processing position of the laser issued. Reference numeral 12 is a clamp device composed of upper and lower cooling bars 13 and 14.

Now, the two metal plates 1 and 2 are held between the upper and lower chills 13 and 14 with a strong clamping force. The laser beam 6 emitted from the laser oscillator with respect to the welded joint secured by this is changed by a reflecting mirror, and an arbitrary inclination angle (for example, 10 ° to 10 ° to the extension line 5 of the contact surface of the lap joint) is changed. Irradiate from within 20 ° range). Then, the laser beam is driven in the welding line direction by an automatic machine to weld the entire circumference of the welding. During this time, the heat capacity of the member to be welded can be adjusted by the chill of the clamp device, so that it can be prevented from falling off. In addition, the present invention is a laser
Since it is a lap welding method of beam welding, the grinding and finishing process in the post process is easy.

[0017]

As described above, according to the method of the present invention, when welding a continuous lap joint portion in the circumferential direction of a plurality of assembled products by press working such as a sink or an automobile fuel tank, Since the laser beam is emitted from 0 ° or an arbitrary inclination angle to the extension line of the overlapping contact surfaces, the clamp does not interfere with the laser beam, so it is sufficient from the plate thickness direction to the edge of the joint. Since it can be reliably clamped by the clamping force, the gap between the plates of the joint can be completely eliminated, the precision of the joint shape can be dramatically improved, distortion during welding can be suppressed, and eye misalignment can be prevented. In addition, since the penetration can be formed in the extension line direction of the joint portion, the fusion width of the joint portion can be widened and the welding strength can be dramatically improved. In addition, if the melting width is wide, grinding finish processing becomes easy as well as seam welding.

Further, according to the apparatus for carrying out the method of the present invention, since automatic machines such as industrial robots and manipulators can be used, it is possible to further improve the manufacturing efficiency of sinks and the like. In addition, compared to a dedicated seam welder, the working environment is not affected by cooling water at all, and the cost of automated equipment such as robots can be reduced by replacing the dedicated machine. Further, since a chiller can be used for the clamp device, the heat capacity of the member to be welded can be adjusted, so that it can be prevented from falling out, which can greatly contribute to ensuring stable welding quality.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a clamped lap joint shape according to the method of the present invention.

FIG. 2 is an explanatory diagram showing a lap joint shape and a laser beam irradiation angle according to the method of the present invention.

FIG. 3 is an explanatory view showing an irradiation angle of a laser beam with respect to an extension line of a contact surface of a lap joint according to the method of the present invention.

FIG. 4 is a diagram showing the size of a fusion area of a welded joint portion according to the present invention. is there.

FIG. 5 is a schematic view showing an apparatus for carrying out the method of the present invention.

FIG. 6 is a view showing a welded portion of a conventional fillet joint portion.

FIG. 7 is a view showing a penetration welded portion of a conventional lap joint.

FIG. 8 is a diagram showing a welded portion formed by conventional lap seam welding.

[Explanation of symbols]

1 Metal Plate 2 Metal Plate 3 Upper Clamp 4 Lower Clamp 5 Extension Line 6 Laser Beam 7 Laser Oscillator 8 Projection Reflector 9 Projection Reflector 10 Automatic Machine 11 Transmission Route 12 Clamp Device

Claims (3)

[Claims] 1. When welding a lap joint by a laser beam, the joint part of the members to be welded is strongly clamped, and the extension line of the contact surface of the lap welding that is clamped and superposed or a minute extension line thereof. A laser welding method for a lap joint part in which a laser beam is applied to a joint part from a line having an angle to perform welding. 2. A clamp device for clamping a lap joint portion of a member to be welded, and a laser beam radiated from a direction parallel to or smaller than an extension line of a contact surface of the clamped lap joint portion, and a laser beam. -A laser welding device consisting of an industrial robot or an automatic machine such as a manipulator that moves the beam along the trajectory of the welding line. 3. The laser welding device according to claim 2, wherein the clamping device is a chill for clamping from both sides of the lap joint.