JP2007229773A - Laser beam welding method and laser beam welding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam welding method and a laser beam welding device, which enlarge a tolerance of a gap at a butt part without increasing the equipment cost of the laser beam welding device. <P>SOLUTION: Steel plates 21, 22 are butt-welded using a laser beam welding device 10 of a direct diode laser system, in which a diode directly emits a laser beam while forming a spot S of an oblong shape in such a way that long sides L2 of the shape are parallel to a welding line W, so that the spot S is made large enough for a gap G. Accordingly, since the tolerance of the gap G can be enlarged, machining precision of the steel plates 21, 22 need not be improved, so that machining cost is reduced. Further, since a displacement allowance of the scanning position of a laser beam L can be enlarged, a high-accuracy position measuring device, a high-precision controller, and the like are not required, so that the equipment cost of the laser beam welding device 10 is reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser welding method and a laser welding apparatus for performing welding by butting materials to be welded and performing irradiation while moving a laser along the butted portion.

2. Description of the Related Art Conventionally, in the automobile field, for the purpose of reducing the weight of a vehicle body and improving collision safety, a method of manufacturing automobile parts using a tailored blank in which steel plates having different thicknesses and materials are welded to each other has been adopted. As shown in FIG. 7 (A), the tailored blank sets the welding line W1 by abutting the steel plate 121 and the steel plate 122, and scans the spot S1 on which the laser is focused along the welding line W1 to melt. It is manufactured by welding using a laser welding method for forming the portion 123.
Here, in the laser welding method using a carbon dioxide laser or a YAG laser, the spot size is as small as about 0.3 to 0.6 mm. Therefore, when the gap (gap) between the abutting portions is large, as shown in FIG. In addition, the spot S1 may be removed from the butted portion, resulting in poor welding.
Therefore, it is necessary to control the gap of the butt portion to be 0.1 mm or less and the straightness of 5/100 or less, and there is a problem that the processing cost of the steel sheet increases.
Furthermore, it is necessary to control the position where the laser is focused and irradiated with high accuracy so as not to deviate from the abutting portion. For this purpose, a high-accuracy position measuring device and a laser head control device (feedback) are required. Mechanism) is required, which increases the size and complexity of the joining device and increases the equipment cost. Such equipment has a drawback in that the shape of the material to be welded is greatly limited and cannot be used for various types of welding.
As another method, there is a method of expanding the allowable value of the gap by expanding the width of the melting portion 123. As such a method, as shown in FIG. 7C, Patent Document 1 discloses a so-called twin spot in which a laser is dispersed to form a spot S1 and a spot S2 so that both of them overlap each other. As shown in FIG. 7D, Patent Document 2 discloses a method for obtaining the effect of increasing the spot diameter by vibrating a mirror for condensing the laser so that the spot S1 is at the butt portion. A method of scanning in a zigzag manner with respect to the welding direction, that is, a method of scanning the laser in a direction reciprocating between the steel plate 121 and the steel plate 122 is disclosed.
Japanese Patent No. 2902550 JP-A-8-290278

  However, in the method using the twin spot, the split mirror that splits the laser irradiates the laser by scanning the laser in a zigzag manner, and a mirror for scanning the laser and its driving unit are required. There is a problem that the cost increases and the cost is further increased due to the consumption of these parts.

  Therefore, an object of the present invention is to realize a laser welding method and a laser welding apparatus that can increase the tolerance of the gap of the butted portion without increasing the equipment cost of the laser welding apparatus.

  In order to achieve the above object, according to the first aspect of the present invention, a laser generator in which a diode directly emits a laser and a laser output from the laser generator are set as an object to be welded. A laser head for irradiating a vertically long spot on the welding line, a moving means for moving the laser head along the welding line, and an angle at which the long side of the spot forms the welding line can be changed. A control means for controlling the head, and the control means can change an angle between the spot on the welding line and the long side of the spot with the welding line. The welding means performs joint welding of the workpiece by scanning the laser beam while irradiating the welding line with the laser head. , Using the technical means of.

According to the first aspect of the present invention, a laser beam welding apparatus of a direct diode laser type in which a diode directly emits a laser is used to form a vertically long laser spot, and an angle between the long side of the spot and a welding line is set. Since joint welding of workpieces is performed under control so as to be changeable, the spot size can be sufficiently increased with respect to the gap between the workpieces. Accordingly, since the melt width during welding can be widened, it is possible to increase the tolerance of the gap and the positional deviation of the laser scanning position.
Since the gap allowance can be increased, it is not necessary to improve the processing accuracy of the workpiece, so that the processing cost can be reduced. In addition, since it is not necessary to tighten the laser scanning accuracy, a highly accurate position measuring device and a laser head control device are unnecessary, and the equipment cost of the laser welding apparatus can be reduced.
That is, it is possible to realize a laser welding method that can increase the tolerance of the gap of the butted portion without increasing the equipment cost of the laser welding apparatus.

  According to a second aspect of the present invention, in the laser welding method according to the first aspect, technical means is used in which the control means controls the long side of the spot to be parallel to the welding line.

  According to the invention described in claim 2, since the long side of the spot is parallel to the welding line, the time for the spot to pass through the point on the welding line is longer than when a circular spot is used. As a result, the welded portion can be sufficiently melted, and good welding without poor bonding can be performed. In addition, since the short side is perpendicular to the welding direction, the width of the fusion zone is not increased more than necessary, and the heat-affected zone due to welding can be reduced.

  According to a third aspect of the present invention, in the laser welding method according to the first aspect, in the welding of the workpieces having different thicknesses, the welding line is set on the thicker workpiece. Use technical means.

  According to invention of Claim 3, when welding the to-be-welded object from which thickness differs, for example, a thin plate and a thick plate, the welding line W is shifted and set to the thick plate side, and a spot is made into a thick plate. It can weld by shifting to the side and scanning. Thereby, since the area of the spot on the thick plate side can be increased, the heat input to the thick plate can be controlled to be larger than the heat input to the thin plate. Therefore, even when the difference between the thickness of the thin plate and the thick plate is large, it is possible to balance the amount of heat input to the thin plate and the thick plate by setting the welding line at an appropriate position, so that good welding is performed. be able to.

  According to a fourth aspect of the present invention, in the laser welding method according to the third aspect, the control means controls the long side of the spot to incline toward the thicker workpiece side in the welding direction. The technical means to do is used.

  According to the invention of claim 4, since the thick plate is heated prior to the thin plate, the temperature of the thick plate rises first, and the portion heated and melted first flows into the thin plate from the thick plate. Therefore, even when there is a step in the butt joint, good welding can be performed in which an unjoined portion is not formed.

  According to a fifth aspect of the present invention, in the laser welding method according to any one of the first to fourth aspects, the moving means is a robot having the laser head at the tip of an arm, and the arm Uses a technical means that is controlled by the control means.

  According to the fifth aspect of the present invention, a robot having an arm with a low equipment cost can be adopted as the moving means, so that the equipment cost of the laser welding apparatus can be suppressed.

  According to a sixth aspect of the present invention, in the laser welding method according to the fifth aspect, a complementary point for correcting the position of the laser head is set between a start point and an end point of the welding line, and the movement is performed. The technical means of sequentially scanning between the complementary points with the laser head is used.

  According to the sixth aspect of the present invention, even when the scanning position is shifted while the laser head scans the laser from the start point to the end point of the welding line, the position can be corrected at the complementary point. Can be scanned more accurately with respect to the welding line.

  According to a seventh aspect of the present invention, in the laser welding method according to any one of the first to sixth aspects, the laser generation source of the laser generator is configured by arranging a plurality of diodes in a row. Therefore, a technical means is used in which the vertically elongated spot is formed by the whole laser generated from each diode.

  According to the invention described in claim 7, a vertically long spot can be formed by configuring the laser generation source of the laser generator by arranging a plurality of diodes in a line.

  According to an eighth aspect of the present invention, there is provided a laser welding apparatus for laser welding an object to be welded, wherein the diode includes a laser generation source that directly emits a laser, and the laser generation apparatus that outputs the emitted laser, and the laser generation A laser head for condensing and irradiating a laser beam output from the apparatus onto a longitudinally shaped spot on a welding line set on the workpiece, and a moving means for moving the laser head along the welding line; And a control means for controlling the laser head so that the angle between the long side of the spot and the welding line can be changed.

  According to the invention described in claim 8, the same effect as that of the invention described in claim 1 can be obtained.

  According to a ninth aspect of the present invention, in the laser welding apparatus according to the eighth aspect, the laser generation source is configured by arranging a plurality of diodes in a line, and the entire laser generated from each diode. Thus, the technical means of forming the vertically long spot is used.

  According to the ninth aspect of the present invention, a vertically long spot can be formed by configuring the laser generation source of the laser generator by arranging a plurality of diodes in a line.

(First embodiment)
A first embodiment of a laser welding method according to the present invention will be described with reference to the drawings, taking as an example a laser welding method for a tailored blank produced by butt welding two steel plates.
FIG. 1 is an explanatory view of a laser welding apparatus according to the present invention. FIG. 1 (A) is an explanatory view schematically showing a laser welding apparatus according to the present invention, and FIG. 1 (B) is an explanatory view of a spot shape of a laser viewed from the A direction of FIG. 1 (A). . FIG. 2 is an explanatory diagram of the laser welding method according to the first embodiment. 3 and 4 are explanatory diagrams of a modified example of the laser welding method according to the first embodiment.

  As shown in FIG. 1A, a laser welding apparatus 10 used in the laser welding method of this embodiment includes a direct diode laser type laser generator 11 that outputs a laser L directly emitted by a laser diode, and a laser generator. 11, a rotatable laser head 12 that irradiates the welded portion with the laser L output from 11, a laser scanning portion 13 that guides the laser head 12 to the welded portion and scans the welded portion, and controls the operation of the laser head. And a control unit 14 for performing the operation.

Here, the laser generation source of the laser generator 11 is configured by arranging a plurality of diodes in a row, and a vertically long spot is formed by the whole laser generated from each diode.
While the spot diameter of a general carbon dioxide laser is about 0.3 mm and the spot diameter of a YAG laser is about 0.6 mm, in the direct diode laser of the present invention, as shown in FIG. A large substantially rectangular spot S having a side L1 of 0.9 mm and a long side L2 of 2.5 mm is formed. Here, since the direct diode laser does not condense the laser by concentrating the laser, the energy density is not greatly reduced at a position where the depth of focus is deep and slightly deviated from the focus.
Further, unlike a YAG laser or the like, a direct diode laser does not need to generate excitation light using a lamp or the like, and thus has high luminous efficiency and can reduce running costs.

  In order to produce a tailored blank using the laser welding apparatus 10, as shown in FIG. 2, first, the end portions of the steel plate 21 and the steel plate 22 are butted and fixed, and the center portion of the gap G of the butted portion The welding start point and the end point are set in, and the welding line W for welding is set. Next, the laser head 12 is arranged above the starting point of the welding line W with the focus of the laser L on the surface of the steel plate 21. Subsequently, the laser head 12 is scanned in the X direction by the scanning unit 13 so that the center P of the spot S of the laser L output from the laser generator 11 moves along the welding line W to the end point. The steel plate 21 and the steel plate 22 are welded by melting the butted portions of 21 and 22 to form the melted portion 23.

When the gap G is smaller than the short side L1 of the spot S, the short side L1 with the short width of the spot S is orthogonal to the welding line W by rotating the laser head 12 in order to make the heat affected zone by welding as small as possible. Then, the laser head 12 is scanned. Since the short side L1 of the spot S is 0.9 mm, which is larger than the spot diameter of a carbon dioxide laser or a YAG laser, the width of the melted portion 23 becomes wide. Therefore, even when the gap G is conventionally required, for example, larger than 0.1 mm. It is not necessary to provide facilities such as a split mirror for splitting the laser and a mirror for scanning the laser. Further, since the tolerance of the gap G can be increased, there is no need for a highly accurate position measurement device and control device for the laser head 12, and for example, the laser head 12 is attached to the tip of an arm controlled by the control unit 14. Good laser welding is possible even with a robot with low equipment costs. Thereby, the installation cost of the laser welding apparatus 10 can be suppressed.
Further, it is also effective for joining in which the gap G tends to be large, such as butt joining when the end is curved.

Since the long side L2 of the spot S is parallel to the welding direction, the time for the spot S to pass through a point on the welding line W is longer than when a circular spot is used. It is possible to form the melted portion 23 by being melted in a good manner, and it is possible to perform good welding with no poor bonding.
The direction of the spot S may be set so that the short side L1 of the spot S is orthogonal to the welding line W by controlling the direction of the scanning unit 13.
The present invention can be applied not only to butt welding of steel plates but also to various types of joint welding.

(Example of change)
As shown in FIG. 3, when the gap G is larger than the short side L1, the laser head 12 is rotated so that the long side L2 having the long width of the spot S is set to be orthogonal to the welding line W. The laser head 12 is scanned. At this time, since the long side L2 of the spot S is as large as 2.5 mm, the tolerance of the gap G can be further increased, so that precise control of the laser head 12 is unnecessary, and the equipment cost of the laser welding apparatus 10 is increased. Good welding is possible without an increase in.

Moreover, since the tolerance of the gap G can be increased in the present invention, for example, when a robot having a laser head 12 at the tip of an arm controlled by the control unit 14 is used in the laser welding apparatus 10, FIG. As shown in (A), the laser head 12 can be scanned in an arc shape.
Further, as shown in FIG. 4B, a complementary point M for correcting the position of the laser head 12 is set between the start point and the end point of the welding line W at every predetermined scanning interval. A configuration in which M is sequentially scanned by the laser head 12 may be used.
When this configuration is used, since the position can be confirmed at the complementary point M while the laser head 12 scans the laser L from the start point to the end point of the welding line W, the complementary point can be obtained even when the scanning position is shifted. Since the position can be corrected, the laser head 12 can be scanned more accurately with respect to the welding line W.
Here, the configuration in which the complementary point M is set is also effective for the butt joint when the end portion is a curve.

[Effect of the first embodiment]
Using a direct diode laser type laser welding apparatus 10 in which a diode directly emits a laser, a vertically long rectangular spot S is formed, and the long side L2 of the spot S is controlled to be parallel to the welding line W. Since the butt welding of the steel plates 21 and 22 is performed, the spot S of the laser L can be made sufficiently large with respect to the gap G. Therefore, since the width of the melting part 23 can be widened, the tolerance of the gap G between the steel plates 21 and 22 and the allowable displacement of the scanning position of the laser L can be increased.
Since the tolerance of the gap G between the steel plates 21 and 22 can be increased, it is not necessary to improve the processing accuracy of the steel plates 21 and 22, so that the processing cost can be suppressed. Further, since it is not necessary to make the scanning accuracy of the laser L strict, a highly accurate position measuring device and a control device for the laser head 12 are unnecessary, and the equipment cost of the laser welding device 10 can be suppressed.
That is, it is possible to realize a laser welding method that can increase the tolerance of the gap G of the butted portion without increasing the equipment cost of the laser welding apparatus 10.
Furthermore, since the long side L2 of the spot S is made parallel to the welding direction, the time for the spot S to pass through a point on the welding line W is longer than when a circular spot is used. Can be sufficiently melted to form the melted portion 23, and good welding without poor bonding can be performed. In addition, since the short side L1 is perpendicular to the welding direction, the width of the fusion zone 23 is not increased more than necessary, and the heat affected zone due to welding can be reduced.

(Second Embodiment)
In the present embodiment, a method for laser welding steel plates having different thicknesses will be described. FIG. 5 is an explanatory diagram of a method of laser welding steel plates having different thicknesses. FIG. 6 is an explanatory view of a modified example of a method of laser welding steel plates having different thicknesses.
When welding a thin plate and a thick plate, if the same heat input is applied to both, the heat capacity will be different, so the amount of heat will be excessive in the thin plate, causing the weld to melt away, and the amount of heat will be insufficient in the thick plate. There is a possibility that a phenomenon in which an unjoined part is generated because the welded part of the steel is not sufficiently melted.
Therefore, in order to form a good weld, considering the difference in heat capacity, the heat input to the thick plate is increased with respect to the heat input to the thin plate, and there is no excess or deficiency in both the thin plate and the thick plate. It is sufficient to balance the amount of heat input.

As shown in FIG. 5, when welding the thin plate 31 and the thick plate 32, the welding line W is set to be shifted to the thick plate 32 side, and the spot S is shifted to the thick plate 32 side for scanning. Then, the melted portion 33 is formed and welded. When this configuration is used, since the area of the spot S on the thick plate 32 side can be increased, the heat input to the thick plate 32 can be controlled to be larger than the heat input to the thin plate 31. it can.
Thereby, even when the difference in thickness between the thin plate 31 and the thick plate 32 is large, the heat input to the thin plate 31 and the thick plate 32 can be balanced by setting the welding line W to an appropriate position. Good welding can be performed.

Further, as shown in FIG. 6, the long side L2 of the spot S may be controlled to be inclined by, for example, 15 ° toward the thick plate 32 toward the welding direction (X direction).
If this structure is used, since the thick plate 32 is heated ahead of the thin plate 31, the temperature of the thick plate 32 rises first, and the part heated and melted from the thick plate 32 to the thin plate 31 side. Since it flows in, even if there is a step in the butted portion, it is possible to perform good welding in which an unjoined portion is not formed.
Here, the angle at which the long side L2 of the spot S is inclined toward the welding direction can be set to an appropriate value based on the width of the gap G, the difference in the plate thickness of the thin plate 31 and the thick plate 32, or the like.

(Effect of 2nd Embodiment)
(1) Since the area of the spot S on the thick plate 32 side can be increased by shifting the welding line W to the thick plate 32 side, the difference in thickness between the thin plate 31 and the thick plate 32 is large. However, since the amount of heat input can be balanced so that the heat input to the thick plate 32 becomes larger than the heat input to the thin plate 31, good welding can be performed.

(2) If a configuration is adopted in which the long side L2 of the spot S is controlled to incline toward the thick plate 32 toward the welding direction, the thick plate 32 is heated prior to the thin plate 31. Since the temperature of 32 first rises and the portion heated and melted first flows from the thick plate 32 to the thin plate 31 side, even if there is a step in the butted portion, good welding is performed in which an unjoined portion is not formed. Can do.

[Other Embodiments]
A gap sensor for detecting the position and width of the gap G is provided in front of the laser head 12 in the scanning direction of the laser welding apparatus 10, and feedback is applied to the laser head 12 based on the obtained information, along the welding line W. And may be controlled so that it can be scanned accurately. Here, the gap sensor is, for example, an image recognition unit configured by a CCD camera or the like, and an image processing unit that detects the gap as coordinates in a direction orthogonal to the weld line based on an image obtained by the image recognition unit. Etc. can be configured.
When this configuration is used, since the scanning position of the laser head 12 is controlled while confirming the position of the welding line W by the gap sensor, the laser head 12 can be scanned more accurately with respect to the welding line W.

It is explanatory drawing of the laser welding apparatus which concerns on this invention. FIG. 1 (A) is an explanatory view schematically showing a laser welding apparatus according to the present invention, and FIG. 1 (B) is an explanatory view of a spot shape of a laser viewed from the A direction of FIG. 1 (A). . It is explanatory drawing of the laser welding method which concerns on 1st Embodiment. It is explanatory drawing of the example of a change of the laser welding method which concerns on 1st Embodiment. It is explanatory drawing of the example of a change of the laser welding method which concerns on 1st Embodiment. It is explanatory drawing of the method of laser-welding the steel plate from which thickness differs. It is explanatory drawing of the example of a change of the method of laser-welding the steel plate from which thickness differs. It is explanatory drawing of the conventional laser welding method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser welding apparatus 11 Laser generator 12 Laser head 13 Scanning part (moving means)
14 Control unit (control means)
21, 22 Steel plate 23 Melting part 31 Thin plate 32 Thick plate 33 Melting part L Laser L1 Short side of spot L2 Long side of spot M Complementary point S Spot P Center of spot W Welding line

Claims (9)

A laser generator in which a diode directly emits a laser; and
A laser head that irradiates a laser beam output from the laser generator onto a vertically long spot on a welding line set on a workpiece,
Moving means for moving the laser head along the welding line;
Using a laser welding apparatus comprising a control means for controlling the laser head so that the angle formed by the long side of the spot and the welding line can be changed,
The control means controls the spot on the welding line and the angle formed by the long side of the spot to the welding line can be changed, and the moving means lasers the welding line with the laser head. A laser welding method characterized in that joint welding of an object to be welded is performed by scanning while irradiating.   2. The laser welding method according to claim 1, wherein the control means controls the long side of the spot to be parallel to the welding line. In welding workpieces with different thicknesses,
The laser welding method according to claim 1, wherein the welding line is set on a thicker workpiece.   4. The laser welding method according to claim 3, wherein the control means controls the long side of the spot to be inclined toward the thicker workpiece side in the welding direction.   The said moving means is a robot provided with the said laser head at the front-end | tip of an arm, The said arm is controlled by the said control means, The one of Claim 1 thru | or 4 characterized by the above-mentioned. Laser welding method.   A complementary point for correcting the position of the laser head is set between the start point and the end point of the welding line, and the laser head sequentially scans between the complementary points by the moving means. The laser welding method according to claim 5. The laser generation source of the laser generator is configured by arranging a plurality of diodes in a row,
7. The laser welding method according to claim 1, wherein the vertically long spot is formed by the whole laser generated from each diode. A laser welding apparatus for laser welding a workpiece,
A laser generator having a laser source that directly emits laser light, and a laser generator that outputs the emitted laser;
A laser head for condensing and irradiating a laser beam output from the laser generator onto a vertically long spot on a welding line set on a workpiece;
Moving means for moving the laser head along the welding line;
Control means for controlling the laser head such that the angle formed by the long side of the spot and the welding line can be changed;
A laser welding apparatus comprising: The laser generation source is configured by arranging a plurality of diodes in a row,
The laser welding apparatus according to claim 8, wherein the vertically long spot is formed by the whole laser generated from each diode.

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