JPH071166A - Method for laser beam welding and welding equipment - Google Patents

Abstract

PURPOSE:To obtain a weld zone of good quality with complete penetration by detecting the height of reinforcement of the weld zone right after solidification of a welding pool in a laser beam welding method and controlling the intensity of a laser beam or the degree of movement of the laser beam so that the detected height is not lower than the sheet surface. CONSTITUTION:A butt part of two sheets 4 is irradiated with the laser beam 2 which is relatively moved for the sheets 4 and while a filler wire 6 is supplied to a molten pool generated by irradiation of the laser beam 2, welding is performed. When a detected value of the reinforcement height is higher than a set value whice is an experimental value of the reinforcement height, the intensity of the laser beam 2 is increased or the moving speed of the laser beam 2 for the sheets 4 is decreased and when the detected value of the reinforcement height is lower than the experimental value, control is executed so that the intensity of the laser beam is decreased or the moving speed of the laser beam 2 for the sheets 4 is increased. Consequently, the weld zone of good quality with complete penetration can be obtained stably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method and apparatus for supplying a filler wire to butt weld plate materials.

[0002]

2. Description of the Related Art Laser welding for butt-welding a plate material to be welded is a laser output, a welding speed, a shield gas flow rate, etc. which are preset depending on the material of the welded object, the plate thickness and the shape of the width, etc. Weld using the welding conditions of.

However, when the root interval at the butt portion of the objects to be welded is not uniform and changes in the longitudinal direction of the butt (referred to as the welding line direction), undercut often occurs due to welding. Further, when the optical components forming the laser light oscillator are deteriorated or thermally deformed, the amount of heat applied to the abutting portion is changed, resulting in defective penetration. Furthermore, as welding progresses, the temperature of the butted part of the work piece rises due to the heat conduction from the already solidified weld part, which increases the penetration depth and the heat generated by the change in the width shape of the work piece. The penetration depth changes due to the difference in conduction, which causes poor penetration. This penetration state changes with time as the welding progresses, and greatly affects the quality of the welded portion. Since laser welding has a narrow melting width, problems of welding quality are likely to occur.

By the way, as a method of butt-welding steel strips by laser welding and determining the quality of the welded portion, as shown in Japanese Patent Laid-Open No. 3-189083, the height of surplus after welding solidification and the back bead There is known a method of determining the quality of a welded portion by measuring the height of the weld and comparing the measured value with the value of a good shape obtained by an experiment in advance.

[0005]

Depending on the shape of the object to be welded, it may be difficult to inspect the formation state of the back bead from the back side of the welded portion. In such a case, it becomes necessary to judge the formation state of the back bead from the formation state of the front bead.

However, the invention described in the above publication is a method in which both the extra height and the back bead are used for determining the quality, and therefore for the shape of the welded portion where it is difficult to measure the shape of the back bead, Not applicable. Further, as a method of increasing the tolerance to the dimensional change of the root interval, there is known a method of welding while feeding a filler wire to a welding portion as described in the Manual for Welding and Joining (1990). The described invention does not consider welding with filler wires.

Therefore, an object of the present invention is to feed a filler wire to a fusion zone and to measure a bulge height for complete butt welding, and measure the bulge height from the measured value of the bulge height. It is an object of the present invention to provide a laser welding method and apparatus for performing welding while determining a bead state and controlling welding conditions.

[0008]

In order to achieve the above object, a first laser welding method of the present invention irradiates a butt portion of two plate members with a laser beam, and the laser beam is moved relative to the plate member. It is a laser welding method of welding while supplying the filler wire to the molten pool generated by the irradiation of the laser beam while supplying the filler wire, and detecting the extra height of the weld portion immediately after solidification of the molten pool, It is characterized in that the intensity of the laser light or the moving speed of the laser light with respect to the plate material is controlled so that the height of the plate does not fall below the plate surface level.

This control increases the intensity of the laser beam or decreases the moving speed of the laser beam with respect to the plate material when the detected value of the extra height is larger than the set value, and when the detected value is smaller than the experimental value. It is preferable to reduce the intensity of the laser light or increase the moving speed of the laser light with respect to the plate material.

The second laser welding method of the present invention is
Welding while irradiating the abutting portion of two l alloy plates with a laser beam, moving the laser beam relative to the Al alloy plate, and supplying the Al alloy filler wire to the molten pool generated by the laser beam irradiation. A laser welding method for detecting a surplus height of a welded portion immediately after solidification of a molten pool, so that a detected value of the surplus height from a plate surface level is within a range of 0 to 0.2 mm. It is characterized in that the intensity of light or the moving speed of the laser light with respect to the Al alloy plate is controlled.

Further, the third laser welding method of the present invention is
Laser for irradiating a butt portion of two stainless steel plates with laser light, moving the laser light relative to the stainless steel plates, and welding while supplying a filler wire for stainless steel to a molten pool generated by the irradiation of the laser light. A welding method, in which the excess height of the welded portion immediately after solidification of the molten pool is detected, and the detected value of the excess height from the plate surface level is 0.
It is characterized in that the intensity of the laser light or the moving speed of the laser light with respect to the plate material is controlled so as to fall within a range of up to 0.6 mm.

In order to achieve the above object, the first aspect of the present invention
Laser welding apparatus of the above, laser irradiation means for irradiating the abutting portion of two plate materials with laser light, moving means for moving the laser irradiation means from the plate material along the abutting portion at a constant height, and laser light irradiation. A laser welding device equipped with a filler wire feeding means for feeding a filler wire to the molten pool generated by the method, which measures the distance to the center of the weld immediately after solidification behind the molten pool attached to the laser irradiation means. Measuring means, a calculating means for calculating the difference between the distance from the preset measuring means to the plate material and the distance measured by the measuring means as a surplus height, and a calculated value of the surplus height was previously obtained. Compare with the setting value of extra height,
It is characterized in that control means is provided for controlling the intensity of the laser light or the moving speed of the laser light with respect to the plate material so that the calculated value of the extra height becomes a set value.

A second laser welding apparatus of the present invention is a laser welding apparatus including a laser irradiation means, a moving means and a filler wire feeding means, like the first laser welding apparatus. The first measuring means for measuring the distance to the central portion of the welded part immediately after being attached and solidified behind the molten pool, and the vicinity of the welded part immediately after solidified by being attached to the laser irradiation means at the same level as the first measuring means Second measuring means for measuring the distance to the surface of the plate material, calculating means for calculating the difference between the measured value by the second measuring means and the measured value by the first measuring means as the extra height, and the extra height A control means for comparing the calculated value of the height with a preset value and controlling the intensity of the laser beam or the moving speed of the laser beam with respect to the plate material so that the calculated value of the extra height becomes the set value. Features To.

The second laser welding apparatus is suitable when the plate material has a curved surface in the longitudinal direction of the abutting portion.

[0015]

According to the present invention, when butt welding of complete penetration is performed under predetermined welding conditions, if the surplus height on the front side of the weld bead becomes too high, the penetration failure occurs. It is focused on the fact that molten metal becomes insufficient and so-called underfill occurs when the temperature becomes lower than the surface. Therefore, in the case of an appropriate extra height, a sound back bead is also formed and a highly reliable weld is obtained.

For this reason, in the first laser welding method of the present invention, the surplus height when a good weld is formed by complete penetration is previously obtained by experiments. Therefore,
Even if the shape of the back bead is not measured, the height of the front bead can be detected, and the quality of the back bead can be determined from this height of the back bead. (Or range) by controlling the intensity of the laser beam or the moving speed of the laser beam so that good laser welding can be achieved with complete penetration.

In the second laser welding method for butt welding two Al alloy plates, the extra height is 0 to 0.
By controlling the intensity of laser light or the moving speed of laser light so that it is within the range of 2 mm, it is possible to completely melt
In addition, good welding can be performed without porosity which is a welding defect inside.

Further, in the third laser welding method in which two stainless steel plates are butted to each other, the intensity of the laser beam or the moving speed of the laser beam is set so that the detected value of the extra height is in the range of 0 to 0.6 mm. By controlling the, it is possible to perform good welding with complete penetration.

In the first laser welding apparatus of the present invention,
The measuring means attached to the laser irradiation means measures the distance to the central portion of the weld formed by solidification of the molten metal immediately behind the molten pool, and the calculation means is the laser irradiation means /
The difference between the distance between the measuring means and the plate materials set based on the constant height between the plate materials and the distance measured by the measuring means is calculated as the extra height, and the control means calculates the calculated value of the extra height. , Comparing with the set value which is the experimental value of the extra bank height at the time of complete melting, the intensity of the laser beam or the moving speed of the laser beam with respect to the plate material is controlled so that the calculated value of the extra bank height becomes the set value. . Thus, according to the present welding device, the extra height becomes a predetermined value, and good welding can be performed with complete penetration.

In the second laser welding apparatus of the present invention, the first measuring means attached to the laser irradiating means measures the distance to the central portion of the welded portion immediately after solidification in the rear of the molten pool and laser irradiates. The second measuring means, which is attached to the means at the same level as the first measuring means, measures the distance to the surface of the plate material in the vicinity of the weld immediately after solidification, and the calculating means measures the measured value of the second measuring means and the second value. The difference between the measured value of the measuring means 1 and the measured value is calculated as the surplus height, and the control means compares the calculated value of the surplus height with a set value which is an experimental value of the surplus height at the time of complete melting. The intensity of the laser light or the moving speed of the laser light with respect to the plate material is controlled so that the calculated value of the extra height becomes the set value. This second laser welding apparatus is suitable for welding curved plate materials. Since a measurement error is likely to occur on a curved surface, it is better to directly measure the distance between the base metal surface in the vicinity of the weld and the center of the weld surface by the first and second measuring means and obtain the difference as the extra height. , More accurate value can be obtained from the distance to the center of the weld surface measured by a single measuring means and the distance to the base metal surface set in advance. Based on the above, the laser output or welding speed is automatically controlled to obtain a good quality weld.

[0021]

【Example】

[First Embodiment] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a laser welding apparatus according to an embodiment of the present invention.

As shown in FIG. 1, a laser beam 2 oscillated from a laser oscillator 1 is condensed by a condensing optical system 3 and a workpiece 4 made by abutting two metal flat plates having the same plate thickness.
And the filler wire 6 is supplied by the wire feeding device 5 to the molten pool generated in the butt portion by the laser light irradiation, while moving the laser light radiated portion along the welding line in the longitudinal direction of the butt portion. Let's weld. At the time of this welding, the condensing optical system 3 is installed in advance so as to move while maintaining a predetermined height above the surface of the workpiece 4. The direction in which the laser light irradiation unit moves with respect to the workpiece 4 is referred to as the front, and the opposite direction is referred to as the rear.

While welding is in progress, the central height of the weld formed by the solidification of the molten metal behind the molten pool is measured by the optical displacement meter 7 attached to the focusing optical system 3. As the optical displacement meter 7, a red semiconductor laser (wavelength 670 nm) in the visible light range is used in this embodiment. The height of the central portion of the welded portion is a so-called extra height, where the surface of the workpiece 4 is 0, and the distance from the optical displacement meter 7 to the surface of the workpiece 4 in the vicinity of the welded portion and the optical displacement meter 7 are measured. The difference in the distance to the center of the welded part is the extra height. Here, the penetration failure portion is determined by the data processing device 8 based on the data obtained by previously obtaining the relationship between the height (excessive height) of the weld bead surface and the height of the back bead. In order to avoid the influence of plasma generated from the molten pool, the optical displacement meter 7 is separated from the laser light irradiation portion by 50 mm in the rear side in this embodiment, and the distance from the surface of the workpiece is 100 mm.
It was installed at a height of mm. When welding a material such as an Al alloy that easily causes spatter, in order to prevent a detection error caused by the spatter blocking the optical path of the detection laser light,
A partition plate may be provided between the plasma and the optical path of the detection laser light.

FIG. 2 shows an example of the relation between the extra height and the penetration state. Welding is butt welding, the plate thickness is 4.0 mm, and the material is stainless steel (SUS304). Filler wire is SU
S309 was used. Extra platter height d ₁ becomes insufficient excess prime for weld than the weld object surface is lowered in the following 0 mm. In addition, it was previously confirmed by experiments that if the surplus height d ₁ is 0.6 mm or more, the melt-in is poor. Therefore, d ₁ is 0 to 0.
If it is out of the range of 6 mm, it is judged to be defective welding.

[Second Embodiment] An example of determining a welding defect from the relationship between the front side of the weld and the back bead width will be described. Welding is butt welding, the plate thickness is 3.8 mm, and the material is Al alloy (A6N01). A4043 was used as the filler wire. If the surface bead height is 0 mm or less, the surface of the melted portion will be lower than the surface of the workpiece, and the excess will be insufficient. In the first embodiment described above, the relationship between the surplus height of the front bead and the back bead shown in FIG. 2 is used to determine whether the back bead is present or not, but in the present embodiment, the back bead shown in FIG. 3 is used. This is an example of determining the quality of welding using the bead width. This is because there is a correlation between the width of the back bead and the number of porosities generated in the weld. The result of confirming the correlation experimentally is shown in FIG. When the back bead width d ₃ is 4 mm or less, the number of porosities increases.
Therefore, in order to prevent porosity, the extra height is 0.2
Must be less than mm. Furthermore, from the viewpoint of preventing undercut, the extra height must be 0 mm or more. Therefore, when the extra height is 0.2 mm or more or 0 mm or less, it is determined that the welding is defective. In addition, in this welding, as shown in FIG. 3, when the surplus height is 0.2 mm, the back bead width is
At 4 mm, the back bead width increases as the surplus height becomes smaller, and the surplus height becomes 0 and the back bead width becomes 6 mm.

[Third Embodiment] FIG. 4 shows welding of an object 4 made of a curved plate material. In this case, in order to make the power density of the laser light constant with respect to the workpiece 4, it is necessary to move the condensing optical system 3 in the height direction with respect to the workpiece 4. Alternatively, it is necessary to move the object to be welded 4 along the welding line at a constant speed with respect to the focusing optical system 3. However, since the surface of the object to be welded 4 is a curved surface, it is difficult to keep the distance between the surface of the object to be welded 4 and the condensing optical system 3 constant. Therefore, the measurement error of the height of the bead on the welded part becomes large, and the penetration Defect detection becomes difficult. In this case, two optical displacement meters, an optical displacement meter 9 for measuring the height of the plate surface near the welded portion and an optical displacement meter 7 for measuring the surplus height, are used for measurement, and the difference is measured by the data processing device 8. The detection error can be improved by calculating

[Fourth Embodiment] Next, an example of the application of the present invention will be described. FIG. 5 is a diagram showing a railway vehicle whose body is composed of honeycomb panels made of Al alloy, FIG. 6 is a diagram showing a situation in which the honeycomb panels are laser-welded, and FIG. 7 is a butt portion of the honeycomb panels orthogonal to the welding line. It is a figure which shows the cross-section structure. The honeycomb panel has two face plates 11 facing each other.
And a honeycomb-shaped core material 1 brazed between them
In the abutting portion of the two honeycomb panels, a U-shaped coupling member 14 is provided by brazing to the face plate 11 so that the U-shaped openings abut. With such a groove joint shape, the back side of the weld cannot be accessed after welding, and it is extremely difficult to visually inspect the state of penetration, and if a penetration failure occurs, repair welding is performed. Is difficult. In the case of such an object to be welded, it is particularly necessary to detect the height of the embankment to determine the quality of the welded portion. Here, an example is shown in which, in order to prevent defective penetration, the height of the bulge on the surface of the welded portion is detected and the laser output is controlled based on the detected information. Based on the information from the optical displacement meter 7, an appropriate laser output is obtained by the data processing device 8 according to an algorithm obtained in advance by an experiment, and the laser output controller 12 controls the laser power supply 13 to output the laser output of the laser oscillator 1. To control the penetration of the welded portion to a constant value. Therefore, a stable weld with good quality can be obtained. Instead of changing the laser output to control the heat input to the object to be welded, the moving speed of the laser light can also be changed and controlled.

[0028]

As described above, according to the laser welding method and apparatus of the present invention, the abutting portion of two plate materials is irradiated with laser light to move relative to the plate material, and the laser light is irradiated. While supplying the filler wire to the generated molten pool, welding is performed, and during welding, the excess height of the welded portion immediately after solidification of the molten pool is detected, and the excess height detected value and the complete value obtained by experiments in advance. Compared with the set value which is the experimental value at the time of melting, the intensity of the laser light or the moving speed of the laser light with respect to the plate material is controlled so that the detected value of the extra height becomes the set value. It is possible to stably obtain a high quality welded portion by penetration.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a laser welding apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an excess height and a penetration state in laser welding of a stainless steel plate.

FIG. 3 is a diagram showing a relationship between the back bead width and the number of generated porosities in laser welding of an Al alloy plate.

FIG. 4 is a configuration diagram showing a laser welding apparatus according to another embodiment of the present invention.

FIG. 5 is a railway vehicle assembly having a laser welded vehicle body panel.

FIG. 6 is a diagram showing laser welding of a honeycomb panel for a rail car structure.

7 is a cross-sectional view taken along the line AA of the honeycomb panel shown in FIG.

[Explanation of symbols]

 1 Laser Oscillator 2 Laser Light 3 Condensing Optical System 4 Workpiece 5 Wire Feeding Device 6 Filler Wire 7 Optical Displacement Meter 8 Data Processing Device 9 Optical Displacement Meter 10 Core Material 11 Face Plate 12 Laser Output Controller 13 Laser Power Supply 14 Coupling Member 15 Honeycomb panel

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area B23K 103: 04 103: 10

Claims (9)

[Claims] 1. A laser beam is applied to the abutting portion of two plate materials, the laser beam is moved relative to the plate materials, and welding is performed while supplying a filler wire to a molten pool generated by the laser beam irradiation. In the laser welding method, the excess height of the weld immediately after solidification of the molten pool is detected, and the intensity of the laser light or the moving speed of the laser light relative to the plate material is controlled so that the detected excess height does not fall below the plate surface. A laser welding method characterized by: 2. When the detection value of the extra height is larger than the set value, the intensity of the laser beam is increased or the moving speed of the laser beam with respect to the plate material is decreased, and the detection value of the extra height is smaller than the experimental value. The laser welding method according to claim 1, wherein control is sometimes performed so as to reduce the intensity of the laser light or increase the moving speed of the laser light with respect to the plate material. 3. A laser beam is irradiated to the abutting portion of two Al alloy plates, the laser beam is moved relatively to the Al alloy plate, and a filler wire is supplied to the molten pool generated by the laser beam irradiation. However, in the laser welding method of welding, the excess height of the welded portion immediately after solidification of the molten pool is detected, and the laser light is adjusted so that the detected value of the excess height from the plate surface is in the range of 0 to 0.2 mm. Of the laser beam or the moving speed of the laser beam with respect to the Al alloy plate is controlled. 4. Welding is performed by irradiating a butt portion of two stainless steel plates with a laser beam, moving the laser beam relative to the stainless steel plate, and supplying a filler wire to a molten pool generated by the irradiation with the laser beam. In the laser welding method described above, the excess height of the welded portion immediately after solidification of the molten pool is detected, and the detected value of the excess height from the plate surface is 0 to 0.
A laser welding method, characterized in that the intensity of laser light or the moving speed of laser light with respect to a plate material is controlled so as to be within a range of 6 mm. 5. A laser irradiating means for irradiating a butt portion of two plate members with a laser beam, a moving means for moving the laser irradiating means along the butt portion at a constant height from the plate member, and a laser beam irradiating means. In a laser welding device having a filler wire feeding means for supplying a filler wire to the molten pool, a measuring means attached to the laser irradiation means for measuring the distance to the central portion of the weld immediately after solidification behind the molten pool and The calculating means for calculating the difference between the distance from the preset measuring means to the plate material and the distance measured by the measuring means as the surplus height, and the calculated surplus height calculated as the surplus height Compared with the set value of, the control means for controlling the intensity of the laser light or the moving speed of the laser light with respect to the plate material is provided so that the calculated value of the extra height becomes the set value. Laser welding equipment. 6. A laser irradiating means for irradiating a butt portion of two plate materials with a laser beam, a moving means for moving the laser irradiating means along the butt portion at a constant height from the plate material, and a laser beam irradiating means. In a laser welding apparatus provided with a filler wire feeding means for feeding a filler wire to the molten pool, the first means for measuring the distance to the central portion of the welded portion which is attached to the laser irradiation means and has solidified behind the molten pool. Measuring means, second measuring means for measuring the distance to the surface of the plate material in the vicinity of the weld immediately after solidification by attaching to the laser irradiating means at the same level as the first measuring means, and the measured value of the second measuring means And a calculation means for calculating the difference between the measured value of the first measuring means and the surplus height, and comparing the calculated value of the surplus height with a preset value of the surplus height, Sasan calculation A laser welding apparatus comprising a control means for controlling the intensity of laser light or the moving speed of laser light with respect to a plate material so that the output value becomes a set value. 7. The laser welding apparatus according to claim 6, wherein the plate material is a curved surface in the longitudinal direction of the abutting portion. 8. The control means increases the intensity of the laser beam or decreases the moving speed of the laser beam with respect to the plate material when the detected value of the extra height is larger than the experimental value, and the detected value of the extra height is 8. The laser welding apparatus according to claim 5, wherein when the measured value is smaller than the experimental value, the intensity of the laser beam is reduced or the moving speed of the laser beam with respect to the plate material is increased. 9. A railcar structure having a plate material welded by the laser welding apparatus according to claim 5 as a panel of a vehicle body.