KR19980086409A - Laser optical system comprising a beam splitter made of individual members having reflective surfaces, welding apparatus and welding methods using the system - Google Patents

Abstract

The laser optical system includes a laser source for generating a laser beam, and a beam splitter for separating the generated laser beam into a plurality of subbeams having individual different optical axes, the beam splitters corresponding to the subbeams. It includes a plurality of individual members having a reflecting surface composed of a plurality of portions, and assembled together to provide a plurality of portions of the reflecting surface, respectively. In addition, the present invention also introduces a laser welding apparatus and method using the above laser optical system.

Description

Laser optical system comprising a beam splitter made of individual members having reflective surfaces, welding apparatus and welding methods using the system

The present invention relates to a technique of splitting a laser beam into subbeams using a mirror.

BACKGROUND Optical systems using laser beams are used in laser processing apparatuses for performing various operations using laser beams such as welding, cutting or machining, surface treatment and boring. Such optical systems are also used in inspection or test equipment and speed measurement equipment.

As disclosed in Japanese Utility Model No. 62-105780 published in 1987, a laser optical system is known in which a laser beam is divided into sub-beams by a mirror. In general, this type of laser optical system comprises a reflecting surface consisting of (a) a laser source for generating a laser beam and (b) a plurality of portions for reflecting while splitting the laser beam into sub-beams having different optical axes. It has a non-reflective and separating mirror having. When this type of laser optical system is used to work on a weldment, the subbeams will irradiate different areas or irradiation points on the surface of the weldment.

In the above laser optical system, it is desirable to facilitate the arrangement of the irradiation point of the sub-beam, in particular, the relative position and spacing of the irradiation point and the change in the position and arrangement direction of the irradiation point relative to the object to be welded. . In the conventional system disclosed in the above publication, the beam reflector and the separating mirror have an integral structure in which portions of the reflecting surfaces cannot move relative to each other. Therefore, when the irradiation points of the sub beams need to be arranged differently, in the optical system, different beam reflection and separation mirrors are required in which parts of the reflecting surface are arranged differently. Thus, the reflectors and separators must be replaced as needed and the laser optical system becomes less versatile.

Accordingly, a first object of the present invention is to provide a laser optical system having high versatility with beam reflection and separation mirrors.

It is a second object of the present invention to provide a laser welding device having such a laser optical system.

A third object of the present invention is to provide a laser welding method using the laser laser optical system of the present invention.

The third object is achieved according to any one of the aspects, embodiments, features or modes of the invention as follows (hereinafter referred to as the aspect of the invention). Serial numbers are assigned to these aspects of the invention and, as the claims also show, which embodiments depend on which aspect to show possible combinations of the various aspects of the invention.

1 is a perspective view of a laser welding device according to an embodiment of the present invention.

2A and 2B are enlarged plan and side views of a parabolic mirror used in the welding apparatus of FIG.

3A and 3B are front and side views for explaining the principle of laser beam separation by parabolic mirrors.

4 is a perspective view showing three planes in which the welding head of the laser welding device is located;

5A is a plan view of a parabolic mirror.

5B and 5C are cross-sectional views taken along the lines A-A and B-B of Fig. 5A, respectively.

FIG. 6 is a plan view for explaining the relative positions of sub-beam irradiation points P ₁ and P ₂ formed on the surfaces of two welded objects by two sub-beams reflected by parabolic mirrors in FIGS. 5A, 5B and 5C;

7A, 7B and 7C are a perspective view, side view and plan view for showing a parabolic mirror and a rocking plane mirror of a laser welding device and for explaining the principle of laser beam separation.

8 is a plan view showing a path of irradiation points of two sub-beams formed on the surfaces of two workpieces by a welding apparatus;

9 is a perspective view showing a laser welding device according to another embodiment of the present invention.

FIG. 10 is a plan view showing a path of irradiation points of two sub-beams formed on the surfaces of two welded objects by the laser welding device of FIG. 9; FIG.

11 is a view schematically showing a laser welding device according to another embodiment of the present invention.

12 is a perspective view showing a laser welding device according to another embodiment of the present invention.

FIG. 13 is a plan view showing the relative positions of two sub-beam irradiation points formed on the surfaces of two to-be-welded objects by the laser welding device of FIG. 12 and a region where plasma is generated by irradiation of the sub-beams; FIG.

14 is a front view showing an example of butt welding using the laser welding device of FIG.

15 is a front view showing another example of butt welding using the laser welding device of FIG.

FIG. 16 is a front view showing still another example of butt welding using the laser welding device of FIG. 12;

FIG. 17 is a graph illustrating the improvement on the limit of welded butt clearance, which is presented as an advantage of the laser welding device of FIG.

FIG. 18 is a graph for explaining the improvement of the limit of alignment error of the sub-beam irradiation point with respect to the weld butt line, which is presented as another advantage of the laser welding apparatus of FIG.

19 is a front view schematically showing a twin-focusing laser welding device according to another embodiment of the present invention.

FIG. 20 is a plan view showing the relative positions of two sub-beam irradiation points formed on the surfaces of two welded objects by the laser welding device of FIG. 19 and the area where plasma is generated by irradiation of the sub-beams; FIG.

* Explanation of symbols for main parts of the drawings

10 laser welding head 11 frame

12 laser source 14 parabolic mirror

16: flat mirror 18: welded object

22: weld line 28: center bore

30, 32: inner and outer member 34: reflecting surface

46: position adjusting mechanism 48: axis displacement adjusting device

50: angular displacement adjusting device 52: spindle

54: operating part 56: connection / mounting

64: rotating member 66: screw

(1) a laser generation source for generating a laser beam, and a beam separation mirror for separating the laser beam generated at the laser generation source into a plurality of sub-beams having individual different optical axes, wherein the beam separation mirror includes the plurality of sub-beams. In a laser optical system having a reflecting surface including a plurality of portions corresponding to a beam, the beam separation mirror includes a plurality of individual members that are assembled together to provide a plurality of portions of the reflecting surface, respectively.

In the laser optical system according to the first aspect of the present invention as described above, the individual members are assembled together to form a beam splitter, thereby providing each part of the reflecting surface of the beam splitter. Since the individual members of the beam splitter can make relative displacements with respect to each other, the relative position of the surfaces of the parts of the reflecting surface as necessary to change the arrangement of the irradiation points of the plurality of sub-beams reflected by each part of the reflecting surface. Can be changed. In this way, the versatility of the beam separation mirror becomes large.

In addition, since one of the plurality of individual subheads of the beam separator can be replaced with another, the versatility of the beam separator is further improved.

(2) In the laser optical system according to the first aspect, the plurality of individual members are (a) the angle of the axis of each subbeam relative to the axis of the laser beam incident on the reflecting surface of the beam splitter, or (b ) Is constructed and assembled so that the relative positions of the plurality of portions in the axial direction of the laser beam incident on the reflective surface can be changed.

(3) The laser optical system according to the first or second aspect, wherein the plurality of individual members provide at least one planar interface that intersects the reflecting surface of the beam splitter so that at least one straight line crosses between them. And the intersection line serves as one or more straight boundary lines dividing the reflective surface into the plurality of parts.

In the third aspect, the plurality of individual members of the beam splitter may provide one planar interface, where the beam splitter is divided into individual members that are capable of relative displacement with respect to each other. The planar interface that intersects the reflective surface provides a straight boundary line that divides the reflective surface into two parts. In order to obtain two parts with different surface areas, the straight boundary passes through a point biased from the center of the reflecting plane of the beam splitter, so that the straight boundary line has a different surface area with the edges of the reflecting plane. It will define two parts. The part with small surface area is biased from the center of the reflecting surface.

(4) The laser optical system according to the first or second aspect, wherein the plurality of individual members provide at least one planar interface that intersects the reflecting surface of the beam splitter so that at least one cross loop is formed therebetween. This loop serves as one or more boundary loops that divide the reflecting surface into the plurality of parts.

In the fourth aspect of the laser optical system, the beam splitter includes a plurality of individual members, wherein the individual members adjacent to each other are in sliding contact with each other at a corresponding cylindrical interface, and one of the adjacent individual members is the other member. It will serve as a guide. With this configuration, no special mechanism is needed to displace the individual members relative to each other. Therefore, the configuration of the beam separation mirror can be simplified, and the versatility regarding the arrangement of the irradiation points of the sub-beams reflected by the portion of the reflecting surface becomes very large.

The diameter of the laser beam generated at the laser source also changes with the change in the energy amount of the laser beam. Therefore, the energy of the laser beam at the outer side of the reflecting surface of the beam splitter is significantly changed due to the diameter change of the laser beam. Thus, as mentioned in relation to the third aspect described above, when the reflective surface is divided into two parts by a straight boundary line, a portion of the laser beam, in which the energy is significantly changed due to the change in diameter of the laser beam, is the part of the reflective surface. It is incident on the part having the smallest surface area. Thus, the energy at the irradiation point of the sub-beam reflected by the smallest portion of the reflecting surface changes relatively well as the diameter of the laser beam changes. This is undesirable in order to obtain a laser optical system that can achieve a given purpose with high stability or reliability.

Unlike the beam splitter according to the third aspect, the beam splitter according to the fourth aspect does not need to place the smallest portion in a position biased from the center of the reflecting surface, and also does not affect the diameter change of the laser beam. It is suitable for providing the smallest portion at the center of the receiving reflective surface.

In this way, irrespective of the area of the portion of the reflecting surface of the beam splitter, the amount of energy at the irradiation point of the sub beam can be easily stabilized.

(5) The laser optical system according to the fourth aspect, wherein the beam splitter consists of a parabolic mirror having a parabolic reflecting surface for focusing and reflecting an incident laser beam, the parabolic mirror having an outer member having a cylindrical central bore. And an inner member fitted to the central bore to allow relative displacement with respect to the outer member, the outer member providing an annular outer reflecting surface, the inner member of the parabolic mirror together with the annular outer reflecting surface. It provides a circular inner reflective surface that will form a parabolic reflective surface.

(6) The laser optical system according to the fourth aspect, wherein the beam splitter consists of a planar mirror having a flat reflecting surface that reflects an incident beam, the planar mirror having an outer member having a cylindrical central bore and an outer member. An inner member fitted to the central bore with a relative displacement relative to the central bore, the outer member providing an annular outer reflecting surface, the inner member forming a flat reflecting surface of the planar mirror with the annular outer reflecting surface; To provide a circular inner reflective surface.

(7) The laser optical system according to any one of the first to sixth aspects, further comprising a position adjusting mechanism for adjusting the relative positions of the plurality of individual members of the beam separation mirror.

In the laser optical system according to the seventh aspect, since the relative position between the plurality of individual members of the beam splitter can be changed by the positioning mechanism, the relative position between the plurality of individual members of the beam splitter according to the specific application of the system is determined. Easy to change. Therefore, the versatility of the beam separator is remarkably improved.

A second object of the invention can be achieved in any of the following aspects.

(8) A laser welding device for welding two welded objects by laser,

(a) a welding comprising a laser optical system according to any one of the first to seventh aspects, for forming irradiation points of a plurality of sub-beams on which the centers are spaced from each other on the surfaces of the two workpieces. Head,

(b) a relative movement device for exercising the irradiation points of the plurality of sub-beams and the two workpieces relative to each other.

According to the laser welding device of the present invention, it is possible to easily change the arrangement of the irradiation points of the sub-beams as necessary with the beam separation mirror having the above-described configuration. In addition, the present laser welding device can perform various welding operations by changing the arrangement of the sub-beam irradiation point. In this way, the versatility of the welding apparatus can be improved in terms of the welding function and the workpiece to be handled.

(9) The laser welding device according to the eighth aspect, wherein the relative movement device is irradiated in a direction parallel to a weld line in which the two welded objects are welded to each other such that the irradiation points of the plurality of sub-beams move with respect to the two welded objects. And a conveying device for imparting relative motion between the point and the two welded objects.

(10) The laser welding apparatus according to the eighth or ninth aspect, wherein the relative motion device is further configured so that the irradiated points of the plurality of sub-beams oscillate in a direction intersecting a welding line in which the two welded objects are welded to each other. And a rocking device for imparting a relative motion between the irradiation point and the two welded objects such that the center of the rocking stroke of the irradiation point is substantially on the weld line.

(11) The laser welding apparatus according to the eighth to tenth aspects, further comprising a position adjusting device for adjusting the distance between the welding head and the surfaces of the two workpieces.

A third object of the invention can be achieved in any of the following aspects of the invention.

(12) A laser welding method in which two welded objects are laser welded using the laser welding device according to any one of the eighth to eleventh aspects.

(13) The laser welding method according to the twelfth aspect, wherein the plurality of sub-beams consist of two sub-beams respectively reflected by two portions of the beam separation mirror, and the irradiation points of the two sub-beams are divided into two welded objects. Located in a direction parallel to a defined weld line welded to each other, the irradiation points are spaced apart from each other in a direction parallel to the weld line and are moved relative to the two welded objects along the weld line by the relative motion device.

In the configuration of the thirteenth aspect, two portions of the beam splitter are determined such that, among the two sub-beams, the sub-beam whose irradiation point precedes the irradiation point of the other sub-beam has more energy at its irradiation point than the other sub-beams. In such a configuration, the welded object is initially heated in advance by the irradiation point of the preceding welded object, and then welding is performed by the irradiation point of the following sub-beam.

(14) The laser welding method according to the twelfth aspect, wherein the plurality of sub-beams consist of two sub-beams respectively reflected by two portions of the beam separation mirror, and the irradiation points of the two sub-beams are the two welded objects to each other. Positioned in a direction parallel to the defined weld line to be welded, the irradiation points being spaced apart from each other in a direction parallel to the weld line, which irradiates and welds the welding line to the two weldments along the weld line by the relative motion device. Relative movement.

The laser welding method according to the fourteenth aspect enables excellent butt welding even if there is a butt gap at the boundary of the two welded parts, because the irradiation points of the sub-beams swing in the direction crossing the weld line, This can lead to misalignment, which reduces the amount of light passing through the butt gap.

(15) The laser welding method according to the fourteenth aspect, wherein the irradiation points move on the surfaces of the two welded bodies along two separate paths that intersect the weld line at prescribed intervals in a direction parallel to the weld line, The two paths will have a phase difference corresponding to half of the prescribed interval.

In the welding method, the movement speed of each sub-beam irradiation point becomes maximum at each point whose path intersects the weld line, and the amount of energy of the sub-beam per unit time becomes minimum at the intersection point. However, since the paths following the irradiation points of the two sub-beams cross each other at the weld line, the total amount of energy of the two sub-beams in the vicinity of the weld line is sufficiently large. In addition, since the phase difference between the paths of the two sub-beam irradiation points corresponds to half of the crossing interval, the half interval of one path is placed between adjacent half gaps of the other path, so that the two irradiation points are welded butt welded together. It will occupy the same area on both sides of the weld line. Thus, this area is uniformly irradiated with the two sub beams along the respective paths. It is possible to reliably butt weld with this welding method without reducing the movement speed of the sub-beam irradiation point, that is to say without reducing the welding speed.

(16) The laser welding method according to the twelfth aspect, wherein the plurality of sub-beams are composed of two sub-beams respectively reflected by two portions of the beam separation mirror, wherein the irradiation points of the two sub-beams have two welded objects to each other. Located in a direction intersecting a defined weld line to be welded, the irradiation points have a center lying on both sides of the weld line and are moved relative to the two welded objects in a direction parallel to the weld line by the relative motion device.

In the case where the irradiation point of the sub-beam is arranged along the weld line, in order to improve the stability of welding, it is preferable to swing the irradiation point in the direction crossing the weld line while keeping the center of the swing stroke on the weld line. In the sixteenth aspect of the present invention in which the irradiation point of the sub-beams is arranged in the direction intersecting the welding line, it is sufficient to move these irradiation points along the welding line without swinging the irradiation point. Therefore, the swinging device for rocking the irradiation point is not necessary in this method, and the cost and weight of the laser welding device can be reduced. Although the swinging device can also be used in this method, the load of the swinging device is relatively low at this time.

(17) The laser welding method according to the sixteenth aspect, wherein the distance between the weld head and the surfaces of the two workpieces is determined differently from the focal lengths of the two sub-beams so that the focal points of the two sub-beams form the irradiation points of these sub-beams. The distance between the surfaces of the two welded objects, and also the distance between the centers of the irradiation points, is determined to together form a continuous irradiation area of sub-beams in which the irradiation points of the two sub-beams are at least adjacent to each other and formed across the weld line.

In the welding method according to the above aspect, the necessity of oscillating the sub-beam irradiation point across the welding line and the use of the rocking device is further reduced, since the two irradiation points form a continuous irradiated area on the surface of the welded object. Because.

(18) The laser welding method according to the sixteenth aspect, wherein the two welded bodies each have a cross section and are butt welded to each other at this cross section along a welding line, and the distance between the centers of the two sub-beam irradiation points is that these irradiation points are inside the cross section. It is determined so as to be located on both sides of the welding line.

In the welding method according to the above aspect, the sub-beams do not pass through the butt gap between the two welded objects to be butt welded to each other. Since the entire irradiated point of each subbeam is located within the area of the corresponding weldment, an appropriate local portion of the weldment can be sufficiently melted and the molten metal fills the butt gap, resulting in the undercut or other welding. It can be well butt welded without defects. In this way, with this welding method, even if there is a butt gap in the end face of the workpiece to be welded, satisfactory butt welding can be performed without swinging the sub-beam irradiation point.

(19) The laser welding method according to the sixteenth or eighteenth aspect, wherein the two welded bodies each have a cross section and are butt welded to each other at this cross section along a welding line, and the distance between the centers of the two sub-beam irradiation points is two sub beams. The plasmas generated by irradiating localized portions on the surface of the welded object are determined to associate with each other to form a substantially continuous plasma region.

In the laser welding method according to the nineteenth aspect, the butt gap can be filled with a molten metal by effectively utilizing heat generated in the plasma region. Also in this way, a satisfactory butt weld is achieved even if a butt gap exists between the workpieces.

According to the present invention, there is provided a laser welding method in which two welded bodies each having a cross section are butted in the cross section, and the surfaces of the two welded welds are irradiated with a laser along a weld line to which the welded portions are butt welded. The welding method is presented. In other words, the welding method is such that the two laser beams formed on the surfaces of the two welded objects are positioned in a direction intersecting the welding line and the centers of these irradiation points are on both sides of the welding line. Positioning a irradiation point of the; determining a distance between the centers of the irradiation points such that each irradiation point is located inside the corresponding cross section; and relatively moving the irradiation points and the two welded objects along the weld line. .

In the welding method, the sub-beams do not pass through the butt gap between the two welded objects to be butt welded together. Since the entire irradiated point of each subbeam is located within the area of the corresponding weldment, an appropriate local portion of the weldment can be sufficiently melted and the molten metal fills the butt gap, resulting in the undercut or other welding. It can be well butt welded without defects. In this way, with this welding method, even if there is a butt gap in the end face of the workpiece to be welded, satisfactory butt welding can be performed without swinging the sub-beam irradiation point.

In one of the laser welding methods, the distance between the centers of the irradiation points is determined so that the plasmas generated by the two sub-beams irradiating a localized portion on the surface of the object to be welded together form a substantially continuous plasma region.

In the above configuration, the butt gap can be filled with the molten metal using the heat generated in the plasma region effectively. Also in this way, a satisfactory butt weld is achieved even if a butt gap exists between the workpieces.

Details of the present invention as described above and other objects, features, advantages and technical and industrial significance will be well understood from the following detailed description with reference to the accompanying drawings.

Referring first to FIG. 1, there is shown a laser welding apparatus including a laser optical system constructed in accordance with one embodiment of the present invention. The laser welding device is provided with a laser welding head 10 that is coupled with the laser optical system, and the generated laser beam is focused and reflected at the welding head and irradiated to a part of the welded object 18. The laser welding head 10 includes a beam separating mirror consisting of a frame 11, a laser generating source 12, a parabolic mirror 14, and a rocking mirror composed of a plane mirror 16. The laser source 12 generates a laser beam, such as a carbon dioxide gas laser in the form of a simplified parallel beam. The parabolic mirror 14 is disposed below the laser source 12 and has a parabolic reflective surface, which reflects all of the incident laser beams generated by the laser source 12. The reflecting surface is inclined at about 45 ° with respect to the axis of the incident laser beam.

The planar mirror 16 is disposed downstream of the parabolic mirror 14 and reflects all of the laser beam reflected by the parabolic mirror 14 again. The reflecting surface is inclined at about 45 ° with respect to the axis of the laser beam reflected by the parabolic mirror 14. The laser beam reflected by the planar mirror 16 is irradiated to a designated local part of the surface of the welded object 18. The welded object 18 consists of two steel plate welded objects 18a and 18b which face each other. In this embodiment, the laser welding device is adapted to butt weld two welded objects 18a and 18b along a defined weld line 22. The welding operation is carried out by moving the spot of the laser beam along the welding line 22, so that the two welded objects 18a and 18b are heated along the welding line 22 to be welded to each other.

As shown in Figs. 2A and 2B, the parabolic mirror 14 has two separate members which cooperate with each other to form the reflecting surface 34. Figs. These two individual members consist of an inner member 30 and an outer member 32 having a cylindrical central bore 28, which is referred to as the axis of incidence laser beam Z _IN (hereinafter referred to as “incident beam axis”). Abbreviated). The cross sections of the inner and outer members 30 and 32 are circular and annular, respectively. The inner member 30 fits into the cylindrical central bore 28.

The reflection surface 34 of the parabolic mirror 14 is composed of a circular inner portion 36 provided by the inner member 30 and an annular outer portion 38 provided by the outer member 32. These inner portions 36 and outer portions 38 are bounded by a boundary loop 35, which becomes circular when the reflecting surface 34 is viewed in the direction of the incident beam axis Z _IN . The inner portion 36 and the outer portion 38 are both parabolic. The cylindrical central bore 28 provides a cylindrical boundary surface, which provides a boundary loop 35 and divides the parabolic mirror 14 into an inner member 30 and an outer member 32.

In order to make the parabolic mirror 14, the precursor of the inner member is first inserted into the precursor of the outer member so that the precursors of the inner member 30 and the outer member 32 can make relative sliding movements with each other. Fit. The corresponding end surfaces of the two precursors are then processed simultaneously and ground with a suitable machine to form parabolic surfaces serving as the inner and outer portions 36, 38 of the reflecting surface 34 of the parabolic mirror 14. These parabolic surfaces are called "reflective surfaces of the inner and outer members 30, 32" or "inner and outer reflective surfaces". Since the inner and outer reflective surfaces 36 and 38 are formed by simultaneously machining and grinding the two precursors, when the reflective surfaces 36 and 38 are formed independently of each other before the precursors are assembled to each other In addition, the manufacturing time of the parabolic mirror 14 is shortened, and the accuracy of the dimensions and the shape of the reflecting surfaces 36 and 38 is further improved, so that the speed of light collection is improved.

The inner and outer members 30 and 32 of the parabolic mirror 14 are capable of displacement and rotation along the axis. As shown in FIG. 2, the outer member 32 is fixed to the frame 11 and the inner member 30 is connected to the outer member 32 via the positioning mechanism 46. The position adjusting mechanism has an axial displacement adjusting device 48 and an angular displacement adjusting device 50.

The axial displacement adjusting device 48 is constructed according to the micrometer principle, in which the movement distance of the screw is proportional to its rotational angle. The axial displacement adjusting device 48 comprises (a) an axially movable spindle 52, (b) an actuating portion 54 rotated by an operator of the laser welding device, and (c) the spindle 52 And a connection / mounting portion 56 which operably connects the operating portion 54 and is fixedly supported by the rotating member 64. The linkage / mounting portion 56 is configured such that the spindle 52 can move in the axial direction and cannot rotate relative to the linkage / mountation portion 54, and the actuating portion 54 can rotate but not connect / mount. It cannot move axially with respect to the mounting part 56. This connection / mounting portion 56 is installed such that the spindle 52 moves axially when he rotates. The spindle 52 is fixed to the inner member 30 by pins 58 passing through the inner member 30 and the spindle 52 at their ends away from the connection / mounting 56, so that the spindle 52 ) Rotates with respect to the inner member 30 as well as cannot move in the axial direction. In order to facilitate the rotation of the operating part 540, the lever 60 extends in the radial direction of the operating part 54 and is fixed to the operating part 54.

On the other hand, the angular displacement adjusting device 50 has a rotating member 64 to which the connection / mounting portion 56 of the axial displacement adjusting device 48 is fixed, the axial displacement adjusting device 48 has an angular displacement adjusting device ( It is possible to rotate together with the rotating member 64 of 50. This rotating member 64 is fixed to the frame 11 by fixing means consisting of a plurality of screws 66, but rotation is possible with respect to the frame 11. The rotating member 64 is formed with a plurality of elongated holes penetrating it, and these holes are formed along a circle having a center on its axis. Each long hole has a width slightly larger than the diameter of the screw 66. The long holes are formed apart from each other in the circumferential direction of the rotating member 64. The screw 66 is screwed into the frame 11 and the outer member 32 through each long hole.

In the angular displacement adjusting device 50, when the screw 66 is released, the rotating member 64 can rotate with respect to the outer member 32 together with the inner member 30. Therefore, the inner member 30 can be rotated with respect to the outer member 32 by rotating the rotating member 64 together with the axial displacement adjusting device 48. After the inner member 30 is fixed in the circumferential direction with respect to the outer member 32, the screw 64 is tightened to fix the inner member 30 to the outer member 32. In order to easily rotate the rotating member 64, the lever 68 extends in the radial direction of the rotating member 64 and is fixed to the rotating member 64.

As described above, the parabolic mirror 14, which functions as a beam reflection and separation mirror, consists of two separate inner and outer members 30, 32, and operates the axial displacement and angular displacement adjusting devices 48, 50. Thereby allowing the members to axially move and rotate relative to one another. Accordingly, the direction of the reflection surface 36 of the inner member 30 with respect to the direction of the reflection surface 38 of the outer member 32 and the axis Z _IN direction of the inner member 30 with respect to the outer member 32. Since the axial position of the beam can be changed as necessary, as described below, the axial displacement and the angular displacement adjusting devices 48 and 50 are operated to control the irradiation points P ₁ and P ₂ of the two sub beams. The relative position on the surface of the workpiece 18 can be changed.

As shown in FIG. 3B, the inner member 30 is in an initial position, in which position the inner reflective surface 36 is parallel to the outer reflective surface 38 (without rotating relative to the outer member 32). Below), the axial position of the reflecting surface 36 on the incident beam axis Z _IN is lowered. As a result, as shown in FIG. 3B, the axis Z _{OUT ′} of the laser beam reflected from the inner reflective surface 36 includes the incident beam axis Z _IN and the axis Z _OUT shown in FIG. 4. It is lowered below the axis Z _OUT of the laser beam reflected at the outer reflecting surface 38 in the plane PL ₁ . The axis Z _OUT is called the “primary reflection beam axis” and the axis Z _{OUT ′} is called the “secondary reflection beam surface”. Since the inner reflective surface 36 is below the outer reflective surface 38, the laser beam L ₀ generated at the laser source 12 is reflected to reflect the first or the inner side with the secondary reflected beam axis Z _{OUT ′} . A second or outer sub-beam L ₂ having a sub-beam L ₁ and a primary reflection beam axis Z _OUT is to be separated. The direction DR _{1 in} which the secondary reflection beam axis Z _{OUT ′ of} the first sub-beam L ₁ is relatively moved with respect to the primary reflection beam axis Z _OUT of the secondary sub-beam L ₂ is an inner member ( 30 is equal to the direction DR ₂ in the relative motion with respect to the outer member 32. This direction DR ₂ is parallel to the incident beam axis Z _IN .

When the inner member 30 is rotated from the initial position shown in Figs. 5A, 5B and 5C in the state without axial displacement, as shown in Fig. 5B, the incident beam axis Z_INFirst sub-beam for L_OneOf the secondary reflection beam axis (Z)_{OUT ′}) Will change the angle. 5B is a cross-sectional view taken along line A-A in FIG. 5A, that is, as shown in FIG. 4, the incident beam axis Z_IN) And the second sub-beam L₂Primary reflection beam axis (Z)_OUT2nd plane perpendicular to)₂Is a view from). As a result, the third plane (PL₃As shown in FIG. 5A corresponding to), the incident beam axis Z_INThe third plane (PL) perpendicular to₃Secondary beam reflection axis (Z) (see Figure 4)_{OUT ′}) Is the primary reflection beam axis (Z)_OUTIncident beam axis (Z)_IN) To rotate around. Thus, the two sub-beams L reflected by the inner and outer reflecting surfaces 36, 38_One, L₂Of) Survey Point (P_One, P₂) Are separated from each other. Secondary Beam Reflection Axis (Z_{OUT ′}The primary reflection beam axis (Z)_OUTDirection of rotation about₃Is the direction in which the inner member 30 rotates with respect to the outer member 32 (DR₄)

When the inner member 30 rotates with respect to the outer member 32, the secondary reflection beam axis Z _{OUT ′ of} the first sub-beam L ₁ is in the direction DR ₃ with respect to the primary reflection beam axis Z _OUT . In addition, as shown in the cross-sectional view of FIG. 5C taken along the line BB of FIG. 5A, it also rotates in the direction DR ₅ within the first plane PL ₁ . In other words, the axis Z _{OUT ′} of the first sub-beam L ₁ reflected by the inner reflective surface 36 is one straight line with respect to the primary reflection beam axis Z _OUT in the first plane PL ₁ . This straight line passes through the point of incidence of the incident laser beam L ₀ on the inner reflective surface 36 and is perpendicular to the incident beam axis Z _IN and the primary reflected beam axis Z _OUT . to be.

Therefore, as shown in FIG. 5A, when the inner member 30 rotates counterclockwise with respect to the outer member 32 in the direction DR ₄ , the secondary reflection beam axis Z _{OUT ′} is as shown in FIG. 5A. Similarly it rotates counterclockwise with respect to the primary reflection beam axis Z _OUT in the third plane PL ₃ and the secondary reflection beam axis Z _{OUT ′} is the primary reflection ratio in the first plane PL ₁ . It rotates in a clockwise direction with respect to the axis Z _OUT . Thus, as shown in FIG. 5C, the axis Z _{OUT ′} becomes close to the axis Z _OUT .

Therefore, when the inner member 30 is rotated counterclockwise as shown in FIG. 5A, as shown in FIG. 6, the irradiation point P ₁ of the first sub-beam L ₁ is the welded object 18. Away from the irradiating point P ₂ of the second sub-beam L ₂ on the surface of, specifically speaking, the irradiating point P ₁ is used for the welding along the welding line 22. Not only as the displacement distance S ₁ in the conveying direction or welding direction F in which the welded object 18 is conveyed with respect to P ₁ , P ₂ ), but also in the direction perpendicular to the conveying direction F ( S ₂ ) is separated from the irradiation point P ₂ . The conveying direction F can be expressed by the negative value of the cross product A × B of the vectors A and B shown in FIG. 4. The vector (A) represents the direction of travel of the laser beam (L ₀ ) along the incident beam axis (Z _IN ), and the vector (B) is of the second sub-beam (L ₂ ) along the primary reflection beam axis (Z _OUT ). Indicates the direction of travel. In other words, the conveying direction F is opposite to the direction that proceeds when the right screw rotates in the direction in which the vector A is rotated to coincide with the vector B at an angle of 180 degrees or less.

In order for the irradiation point P ₁ of the first sub-beam L ₁ to be separated from the irradiation point P ₂ only in the conveying direction F, the inner member (in the direction away from the laser beam generating source 12). 30) the need to clear the clockwise rotation of the outer member incident beam axis about (32) (Z _iN) by the axial movement in the direction of the primary reflection beam axis (Z _OUT) the secondary reflection beam axis (Z _{OUT ')} of the do. In other words, in order to rotate the secondary reflection beam axis Z _{OUT ′} only within the third plane PL ₃ , the inner member 30 is axially oriented as well as the rotational movement with respect to the outer member 32 from the initial relative position. You should also exercise.

Irradiation point (P _1, P ₂₎ is the distance to the conveying direction (F) projecting point in a state separated from each other by (P ₁₎ the transport direction irradiation point in a direction perpendicular to the _{(F) (P 2) (} S 2 ), It is not necessary to adjust the axial relative position between the inner member 30 and the outer member 32, even if it is biased by), and also the relative between the inner member 30 and the outer member 32 By adjusting only the angular position, the incident laser beam L ₀ can be separated into the first and second sub beams L _{1 and} L ₂ .

In the laser welding apparatus of the present invention, the welding operation is performed by the first and second subs reflected by the inner and outer portions 36 and 38 of the reflecting surface 34 of the parabolic mirror 14, as shown in FIGS. 1 and 7A. The first and second irradiation points P _1, P ₂ of the beams L ₁ , L ₂ are performed so as to be spaced apart from each other in the feed direction F in parallel to the defined weld line 22. Rotating about the outer member 32 to inner member 30. As shown for this purpose, in Fig. 7c of the first irradiation points (P ₁₎ of the second sub-beam (L ₂₎ of the sub-beam (L ₁₎ The inner reflecting surface 36 is moved away from the irradiation point P _{2 in the} feeding direction F and also moved in the axial direction with respect to the outer member 32 as shown in FIG. 7B. Move relative to the outer reflecting surface 38 along the incident beam axis Z _{IN in a} direction away from. In this configuration, the irradiation point P ₁ is biased from the irradiation point P ₂ only in the feed direction F parallel to the welding line 22.

The inner reflective surface 36 is determined by the diameter d _{2 as} viewed in cross section, which diameter d ₂ is the diameter of the laser beam L ₀ incident on the reflective surface 34 of the parabolic mirror 14. d ₁ ). More specifically, the irradiation point (P ₁₎ a first sub-beam the energy of the (L ₁₎ is smaller than the energy of the second sub-beam (L ₂₎ at the irradiation point (P ₂₎ In addition, these energy is defined in the The diameter (d ₂ ) is determined so as to have a ratio.

The outer member 32 of the parabolic mirror 14 combines a cooling device having a water jacket network for cooling the inner member 30 and the outer member 32. The water jacket network has a passage formed through the outer member 32 in the circumferential direction. The inner member 30 whose front outer circumferential surface is in contact with the inner circumferential surface of the outer member 32 can be effectively cooled by a coolant circulating in the water jacket network in the outer member 32.

As shown in FIG. 1, the planar mirror 16 reflects the first and second sub-beams L ₁ , L ₂ incident from the parabolic mirror 14 toward the surface of the welded object 18. This plane mirror 16 is positioned relative to the parabolic mirror 14 such that the subbeams L _1, L ₂ are reflected by the plane mirror 16 only within the first plane PL ₁ .

The plane mirror 16 has a mirror portion 70 and a mounting portion 72 on which the mirror portion 70 is mounted. One end of the support shaft 74 parallel to the welding line 22 is attached to the mounting portion 72. The other end of the support shaft 74 is attached to the device (first relative motion device) of the galvanometer 76 fixed to the frame 11. The plane mirror 16 is oscillated about the axis of the support shaft 74 by the galvanometer 76, whereby the irradiation points P ₁ , P _{2 of} the two sub-beams L ₁ , L ₂ are The distance W is oscillated in the direction perpendicular to the welding line 22, wherein the two irradiation points P ₁ and P ₂ have a distance d defined in the welding line 22 direction (feed direction F). Will be maintained. The center of the rocking stroke is substantially on the weld line 22. As a result, when the welded object 18 is conveyed in the conveying direction F, each irradiation point P ₁ moves along a sinusoidal path in the welding operation, but in general, the sinusoidal path is defined by the defined weld line ( 22) Follow. The sub-beams L ₁ , L ₂ reflected from the turning mirror 16 pass through the interior of the protective sleeve 78 attached to the frame 11 and reach the weld 18.

The galvanometer 76 is controlled by the controller 80. By controlling the number of fluctuations and the amplitude of the galvanometer 76 by the controller 80, the number and angle of the fluctuations of the plane mirror 16 are controlled.

The laser welding device has a to-be-welded device 84 that functions as a second relative motion device, which supports the to-be-welded material 18 (welded material in which the to-be-welded materials 18a and 18b are opposed to each other). X, Y in the plane substantially perpendicular to the direction in which the first and second sub-beams L ₁ , L ₂ emerging from the plane mirror 16 are incident on the weld 18. It is made to move in the axial direction. The welded object transfer device 84 includes (a) a table 86 on which the welded object 18 is fixed thereon, and (b) an X-axis displacement device for moving the table 86 in the X-axis direction ( 88) and (c) a Y-axis displacement device 90 for moving the table 86 in the Y-axis direction. Each sub-beam irradiation point of the first sub beam (L _1), the swing center of the irradiation point (P _1, P ₂₎ of the (L _1, L ₂₎ is moving on the weld line (22) also having a relatively low energy (P ₁ ) The displacement devices 88, 90 are connected to the control device 80 and subjected to their adjustment so that this relatively large energy precedes the irradiation point P ₂ of the second sub-beam L ₂ . 86) in the feed direction (F).

The laser welding device is also equipped with a Z-axis displacement device 92 for adjusting the vertical distance between the welding head 10 and the welded object 18 in the Z-axis direction. This Z-axis displacement device 92 moves the welding head 10 to adjust this vertical distance to a defined distance, while monitoring the vertical distance with an appropriate sensor. In the present embodiment, the welded object (with the laser beam energy sufficient to irradiate each local portion of the surface of the welded object corresponding to the irradiation points P ₁ and P _{2 with} the first and second sub-beams L ₁ , L ₂ ) The vertical distance between the welding head 10 and the object to be welded 18 is adjusted so as to be concentrated at the irradiation points P ₁ and P ₂ on the upper surface of 18). The irradiated local part is moved by the conveyance movement of the welded object 18.

In the laser optical system used in the welding head 10 of the present laser welding device, the inner and outer members 30 and 32 of the parabolic mirror 14 having the inner and outer reflecting surfaces 36 and 38, respectively, are axially oriented. Since the movement can be rotated with respect to each other as well, the distance d between the irradiation points P ₁ and P _{2 of the} two sub beams L ₁ and L ₂ and the conveying direction F of the welded object 18. The separation direction of the irradiation point (P ₁ , P ₂ ) with respect to) can be easily adjusted as needed without the need to replace the parabolic mirrors (14). Thus, the versatility of the laser optical system and the laser welding device is improved.

In this embodiment, the boundary between the inner and outer members 30, 32 having inner and outer reflecting surfaces 36, 38, respectively, is given by the cylindrical surface of the cylindrical bore 28, so that the irradiation point P ₁₎ a first energy content of the sub-beam (L ₁₎ is less susceptible to the diameter change of the first sub beam (L ₁₎ is reflected by the inner reflection surface 36, and thus the inner reflecting surface (36 in) Irrespective of the area of the area of the energy is constant, the laser welding work can be made as intended.

In the present apparatus, the positioning mechanism 46 is provided for the fixed parabolic mirror 14 composed of the individual inner and outer members 30 and 32, and the flat mirror 16 oscillating by the galvanometer 76 is provided. Not for With this configuration, the flat mirror 16 can be made relatively light, so that the flat mirror 16 can be smoothly shaken. Further, according to the welding head 10 of the present device, the irradiation point (P _1, P ₂₎ are as round trip across the weld line 22 is moved along the weld line 22, and thus, the solid line in FIG. 8 As indicated by and dashed lines, respectively, the front irradiation point P ₁ and the rear irradiation point P2 follow the sinusoidal paths 94 and 96, respectively. Irradiation point (P _1, P ₂₎ can swing to and from across the (transport in the direction F), the weld line 22, the speed and these irradiation point (P _1, P _2), the weld line 22 when moved along, the Two sinusoidal paths 94, 96 are determined to intersect each other at the weld line 22. The paths 94 and 96 intersect with the weld line 22 at prescribed intervals in a direction parallel to the weld line 22, and as such can be seen in FIG. 8, the two sinusoidal paths 94 and 96. ) Has a phase difference of 180 °, that is, a phase difference corresponding to half of the interval. The movement speed in the swinging direction of each irradiation point P ₁ , P ₂ is maximum at the point at which the sinusoidal paths 94, 96 intersect the weld line 22, and thus, of the subbeams L ₁ , L ₂ . The amount of energy is minimum at the intersection of the sinusoidal paths 94 and 96. It can be seen in this connection that the two subbeams (L ₁ , L ₂ ) are irradiated at the local near the intersection of the sinusoidal paths 94, 96, but the amount of energy is minimal at these intersections, thus the weld (18) can uniformly receive the irradiation of the sub-beams (L ₁ , L ₂ ) over the entire swing width (W) of the irradiation points (P ₁ , P ₂ ) without reducing the movement speed near the welding line (22). This improves the stability and accuracy of the weld. If the reflecting surface 34 of the parabolic mirror 14 is divided into several small regions by one or more closed boundary lines, that is, regardless of whether the parabolic mirror consists of two or more members that can be displaced relative to each other, that is, the parabolic mirror is an incident laser beam. Even when the unitary structure has two or more reflecting surfaces that divide the beam into two or more sub-beams, the energy amount of the sub-beam reflected by the smallest of the two or more portions 36 and 38 is this sub-beam. It is less affected by the change in diameter.

A second embodiment of the present invention will be described with reference to FIGS. 9 and 10. Since most of the components used in the second embodiment are the same as in the first embodiment, the same reference numerals are given to the same components. Therefore, only the features of the second embodiment will be described in comparison with the first embodiment.

According to the laser welding apparatus of the first embodiment, as shown in FIG. 1, the irradiation points P ₁ and P _{2 of the} two sub-beams L ₁ and L ₂ are spaced apart from each other in a direction parallel to the welding line 22. However, in the welding apparatus according to the second embodiment, as shown in FIGS. 9 and 10, the inner member 30 of the parabolic mirror 14 moves axially from the initial position in a direction away from the laser source 12. By doing so, the centers of the two irradiation points P ₁ and P ₂ are spaced apart from each other in the direction perpendicular to the weld line 22. In addition, the table 86 of the two irradiation points (P _1, P _2), the weld line 22, the welding head 10 to be positioned on either side of the weld and the target transfer device 84 is disposed.

In the first embodiment, the irradiation point (P _1), the first sub beam (L _1), the irradiation point (P _2), the second parabolic path (14) so as to have a smaller amount of energy than the sub-beam (L ₂₎ in at The areas of the reflective surfaces 36, 38 of the inner and outer members 30, 32 of are determined so that the two subbeams L ₁ , L ₂ have a defined energy ratio. However, in the second embodiment, the areas of the inner and outer reflecting surfaces 36 and 38 are such that the first and second sub beams L _{1 and} L ₂ have the same amount of energy at the irradiation points P ₁ and P ₂ . Is determined.

In the first embodiment, the welding is such that the sub-beams L ₁ , L ₂ are concentrated on the surface of the welded object 18 and the irradiation points P ₁ , P ₂ are formed on the surface of the welded object 18. The vertical distance between the head 10 and the surface of the workpiece 18 is controlled by the Z-axis displacement device 92. In the second embodiment, the vertical distance is adjusted so that the subbeams L ₁ , L ₂ are not exactly concentrated on the surface of the workpiece 18. That is, the concentration points of the sub beams L ₁ and L ₂ are shifted in the vertical direction from the surface of the welded object 18 on which the irradiation points P ₁ and P ₂ are formed. With this configuration of the second embodiment, the irradiation points P ₁ , P ₂ on the surface of the workpiece 18 have a larger size or diameter than in the first embodiment.

In the first embodiment, the distance d between the centers of two irradiation points P ₁ and P ₂ on the surface of the welded object 18 is determined so that these irradiation points P ₁ and P ₂ are separated from each other. . In the second embodiment, the irradiation point (P _1, P ₂₎ center-to-center distance, as shown in Figure 10, an area (SP _1, SP ₂₎ are partially overlapping each other in the irradiation point (P _1, P ₂₎ of the Is determined. The irradiation point areas SP ₁ , SP ₂ together form a generally long continuous region AL to which the sub-beams L ₁ , L ₂ are to be irradiated. This continuous irradiation area AL extends in the direction perpendicular to the weld line 22. As the continuous irradiation area AL moves along the weld line 22, a weld bead BW is formed along the weld line 22.

In the second embodiment of Figs. 9 and 10, the welding head 10 is not equipped with the galvanometer 76 used in the first embodiment, and the plane mirror 16 is directly attached to the frame 11. That is, since the welding apparatus of the second embodiment does not use a high precision complicated mechanism for swinging the flat mirror 16, the manufacturing cost and weight of the welding apparatus are reduced.

Further, by modifying the welding apparatus of the first embodiment, the distance d between the centers of the irradiation points P ₁ and P ₂ on the surface of the welded object 18 is generally formed so that a long continuous irradiation area AL is formed. These irradiation points P ₁ and P ₂ may be positioned in the direction perpendicular to the welding line 22 while adjusting. Such a configuration is possible in the first embodiment because, as described above in connection with the first embodiment, the axial and circumferential positions of the inner member 30 of the parabolic mirror 14 with respect to the outer member 32. This is because the position of the irradiation point (P ₁ , P ₂ ) can be adjusted as needed.

In addition, the above configuration capable of forming the welding beam at a relatively high speed without swinging the two sub-beams across the welding line 22 can be used without dividing the incident laser beam into two sub-beams. That is, fluctuations are not required if the generally long areas on the surface of the workpiece perpendicular to the weld line are irradiated by two adjacent irradiation points of two laser beams each generated by two separate laser sources.

A third embodiment of the present invention will be described with reference to FIG. Since this embodiment is somewhat similar to the second embodiment of FIG. 9, only the features of the third embodiment will be described with reference to the second embodiment.

In the first and second embodiments of FIGS. 1 and 9, parabolic mirror 14 has an outer member 32 having a cylindrical central bore 28 and an inner member 30 that engages with the bore 28. The inner and outer members 30, 32 are axially movable and rotatable relative to one another. The inner and outer members 30 and 32 have reflective surfaces 36 and 38, respectively, which together form a reflective surface 34. That is, the reflecting surface 34 of the parabolic mirror 14 has inner and outer portions 36, 38, which are given by the inner and outer members 30, 32. These inner and outer reflecting surfaces 36 and 38 serve to divide the incident laser beam L ₀ into first and second sub beams L ₁ and L ₂ . Thus, the parabolic mirror 14 functions as a beam separation mirror that divides the incident laser beam L ₀ into two sub beams L ₁ and L ₂ .

On the other hand, the laser welding apparatus according to the third embodiment of FIG. 11 uses a parabolic mirror 120 that only functions to focus and reflect the incident laser beam L ₀ . This parabolic mirror 120 has an integral structure. The laser beam L ₀ reflected by the parabolic mirror 120 is incident on the plane mirror 122 having the outer member 124 and the inner member 126. The outer member 124 has a cylindrical central bore in which the inner member 126 fits into the bore and the outer and inner members 124 and 126 can rotate as well as axially move relative to each other. The outer and inner members 124 and 126 have outer and inner reflecting surfaces 128 and 130, respectively, which together form a planar reflecting surface. Thus, the planar mirror 122 serves as a beam splitter that divides the laser beam L ₀ into two sub-beams L ₁ and L ₂ .

In the first and second embodiments, the sealing-type central bore 28 of the outer member 32 has an axis coinciding with the incident beam axis Z _IN (FIG. 2), in which the incident beam axis is “Z _{IN. -0} ”. The inner and outer members 30 and 32 can move relative to the axis Z _IN and can also rotate relative to the axis Z _IN . In the third embodiment of FIG. 11, the cylindrical central bore of the outer member 124 of the planar mirror 122, which serves as the beam splitter 122, has an axis coinciding with the primary reflection beam axis Z _OUT , The outer and inner members 124, 126 can move relative to this axis Z _OUT and can also rotate relative to the axis Z _OUT . The flat mirror 122 is provided with a positioning mechanism similar to the mechanism 46 used for the parabolic mirror 14 in the first and second embodiments. By appropriately operating this position adjustment mechanism, the axis Z _OUT with respect to the axis Z _IN-1 of the laser beam L ₀ which enters the reflecting surface 130 of the inner member 126 into the plane mirror 122 is obtained. to be moved along, and also it is possible to change the angle of the axis (Z _iN-1) of the secondary reflection beam axis (Z _{OUT ')} of the sub-beam (L ₁₎ is reflected by the inner reflecting surface (130).

A fourth embodiment of the present invention will be described with reference to FIGS. 12 to 18. The laser welding apparatus according to the fourth embodiment is the apparatus of the second embodiment of Figs. 9 and 10, except that the distance d between the centers of the two sub-beam irradiation points P _{1 and} P ₂ is set. Is basically the same as In the fourth embodiment, the same reference numerals are used for the same elements as those of the second embodiment, and a detailed description thereof will be omitted.

As shown in Fig. 12, the laser welding apparatus according to the fourth embodiment includes a parabolic beam separation mirror 14 which receives a laser beam L ₀ generated from a suitable laser source (not shown), and two sub beams ( L _1, L ₂₎ has a plane mirror (16) receiving the. As in the second embodiment of FIG. 9, the parabolic mirror 14 has a circular reflecting surface made up of inner and outer portions respectively given by the inner and outer members 30 and 32. The relative positions of the inner and outer members 30, 32 in the axial direction and the circumferential direction are determined as follows: the irradiation points of the two sub-beams L ₁ , L ₂ reflected by the plane mirror 14 ( P ₁ , P ₂ are located on both sides of the welding line 22 on the surface of the welded object 18, and the irradiation points P ₁ , P ₂ are mutually perpendicular in the direction perpendicular to the welding line 22. To be apart, the relative positions of the inner and outer members are determined.

In a conventional laser welding apparatus, a plasma may be formed when a local portion of a welded object to which the laser beam is irradiated is heated, and the plasma tends to absorb the energy of the laser beam, so that the energy is irradiated to the welded object. Will interfere with delivery to the site. In view of these problems, techniques for preventing the generation of plasma and techniques for efficiently utilizing the heat of the plasma have been proposed. This embodiment is adapted to implement the latter technique, that is, a technique capable of efficiently utilizing the heat of plasma.

In butt welding, the butt gap may be placed between the two welded parts to be opposed to each other. In this case, it is important to prevent the laser beam from passing through the butt gap during the butt welding operation. If a laser beam passes through the butt gap, an undercut or other weld defect may occur because the laser beam energy is not sufficiently delivered to both welds.

In the present embodiment, the distance d between the centers of the irradiation points P ₁ and P _{2 of the} two sub-beams L ₁ and L ₂ is the irradiation point P formed on the surfaces of the two welded objects 18a and 18b. ₁ , P ₂ is determined to be located within the surface of each welded object 18a, 18b as a whole as shown in FIG. In other words, the separation distance d is determined so that the periphery of each of the irradiation points P ₁ and P ₂ is inwardly separated from the end face of the corresponding to-be-welded object among the to-be-welded objects 18a and 18b which are butted together. In the present embodiment in which the inner and outer reflecting surfaces of the parabolic mirror 14 are each circular and annular, all of the irradiation points P ₁ and P ₂ are circular as shown in FIG.

The separation distance d between the irradiation points P ₁ and P ₂ is also determined as follows. That is, the plasma generated by the sub-beams L ₁ and L ₂ irradiated to the localized portions of the welded objects 18a and 18b are associated with each other, and thus has a short axis (a) and a long axis (b) as shown in FIG. The separation distance is determined such that an elliptical continuous plasma region is formed.

According to this embodiment, even when there is no butt gap at the butt boundary of the welded object as shown in FIG. 14, and even when there is a butt gap as shown in FIG. 15, the plasma and the molten portion are formed at the butt boundary of the welded object. The welds 18a and 18b are suitably welded to each other. That is, even if a butt gap exists between two to-be-welded objects 18a and 18b, this welding apparatus is able to perform excellent butt welding.

Also, when the center of irradiation (intermediate point between the centers of the irradiation points P ₁ and P ₂ ) is aligned with the butt line, the deviation from the butt line as shown in FIG. Even in this case, excellent butt welding of the to-be-welded objects 18a and 18b is possible with this welding apparatus.

17 and 18 show test results when butt welding two thin steel plates with the laser welding apparatus according to the fourth embodiment of FIGS. 12 to 15. The graph of FIG. 17 shows the limit butt clearance of the steel sheet, ie the maximum butt clearance that was performed with satisfactory results. The graph of FIG. 18 shows the critical center deviation distance between the irradiation line and the butt line, that is, the maximum center deviation distance that the butt weld performed with satisfactory results. In addition, the graph of FIG. 17, 18 shows the result of the test using the welding apparatus of FIG. The result with the word "oscillation" is the result when the welding apparatus of FIG. 1 is used, and the result with the word "twin-focusing" is the case when the welding apparatus according to the fourth embodiment is used. The result is.

The test on this welding apparatus was performed under a combination of different welding conditions. Welding conditions include steel sheet thickness, output of carbon dioxide gas laser, welding speed, focal length of laser beam, and de-focusing amount of laser beam. The defocusing amount is expressed as T / F, where “F” represents the focal length of the parabolic mirror 14 and “T” represents the difference between the distance between the parabolic mirror 14 and the steel plate surface and the focal length F. ). The difference is equal to the vertical distance between the steel plate surface and the focal point of the subbeam. If the defocusing amount (T / F) is present, the focus of the sub-beam is shifted perpendicularly from the surface of the steel sheet on which the irradiation point of the sub-beam is formed. The defocusing amount (T / F) affects the size of the irradiation point of the sub beam on the steel plate surface. More specifically, the size of the sub-beam irradiation point increases as the defocusing amount (T / F) increases. In this test, the welding speed and the defocusing amount (T / F) were changed. The test on the welding apparatus of FIG. 12 was performed under the following welding conditions.

Steel Plate Thickness (mm): 1.0

Welding speed (m / min): 3.0, 4.0, 5.0

Laser power (kW): 3.0

Focal Length (mm): 254

Defocusing amount (T / F): 0.2, 0.3, 0.4

The test on the welding apparatus of FIG. 1 was performed with the defocusing amount (T / F) being 0.2.

As can be seen from FIG. 17, the limit butt gap present in the present welding device of FIG. 12 is equal to or greater than the butt gap in the welding device of FIG. 1. The marginal butt gap is improved in this welding system because the subbeam does not pass through the butt gap in the steel plate, thus increasing the amount of fused metal at both sides of the butt gap and at each irradiated local area adjacent to the gap. It seems to be because The fused metal forms a bridge between the localized areas to be irradiated, which bridges the butt gap.

As can be seen from FIG. 18, the limit center deviation amount in this apparatus is equal to or larger than the deviation amount in the welding apparatus of FIG. The reason why the limit center deviation is improved in this welding apparatus is considered to be due to the elliptical plasma and the molten portion formed in the direction perpendicular to the butt line of the steel sheet.

In this way, in the present welding apparatus, the plane mirror is provided so that the irradiation points P ₁ and P ₂ of the sub beams L ₁ and L ₂ swing across the welding line 22 for the purpose of improving the limit butt clearance and the center deviation amount. It is not necessary to swing (16) to a high swing rate. Thus, the apparatus does not require a complicated and expensive apparatus for oscillating the flat mirror 16 as used in the welding apparatus of FIG. 1, thereby reducing the cost of the welding apparatus and extending its life.

Since the limit butt clearance and the center deviation are increased in the welding apparatus according to the fourth embodiment of the present invention, the maximum welding speed can be increased as compared with the case of the welding apparatus using the beam swing apparatus, thereby improving the efficiency. Will be.

As can also be seen in the graphs of Figs. 17 and 18, the limit butt clearance and the center deviation amount also become large with the increase in the defocusing amount (T / F).

As described above, the welding apparatus of FIG. 12 executes the following laser welding method. That is, the local portions of the two weldments with their cross sections butted together are irradiated with the respective irradiation points of the laser beams whose centers are separated from each other in the direction perpendicular to the defined weld line, and the laser beam is used to butt weld the two weldments along the weld line. The irradiation point is moved on the surfaces of the two weldments, and the distance between the centers of the irradiation points of the laser beams is determined as follows, i.e. the two laser beams are positioned inward from the end faces of the corresponding weldments as a whole. The distance is determined such that the plasma generated by irradiating a localized portion of the welded object is associated with each other to form a continuous plasma region crossing the butt line of the welded object. However, this laser welding method involves a beam splitter comprising individual members for providing two or more reflecting surfaces—for example, the beam reflecting / separating parabolic mirror 14 used in the embodiments of FIGS. 1, 9 and 12. And a laser welding device that does not use the beam separation plane mirror 122 used in the embodiment of FIG. 11.

For example, the laser welding method can also be performed with the welding apparatus of FIG. 19 configured according to the fifth embodiment of the present invention.

The laser welding apparatus in FIG. 19 has a laser source 100, a focusing and reflecting parabolic mirror 102, and a plane mirror 104, and these components are disposed on the optical path in this order. The planar mirror 104 serves as a beam separation mirror for dividing the laser beam L ₀ into two sub-beams L _{1 and} L ₂ having different optical axes. Specifically, the plane mirror 104 has a circular reflective surface composed of two parts surrounded by a straight line BL extending in the radial direction of the circle of the reflective surface parallel to the welding line 22. The two portions of the reflecting surface are two straight lines or planes which are inclined with respect to each other at a predetermined angle θ such that the straight line boundary line BL forms one circumference. The laser beam L ₀ reflected by the parabolic mirror 102 is reflected by the plane mirror 104 and separated into two sub-beams L _{1 and} L ₂ , wherein the sub-beams L _{1 and} L ₂ The axis is at an angle of about 90 ° with respect to the axis of the laser beam incident on the plane mirror 104. The irradiation points P ₁ and P ₂ of the sub-beams L _{1 and} L ₂ on the workpiece 18 are spaced apart from each other in a direction perpendicular to the weld line 22 as shown in FIG. 20. The irradiation points P ₁ and P ₂ have a semicircular shape in FIG. 20 because the reflecting surface of the plane mirror 104 is divided into two semicircular portions by the straight boundary line BL. Also in the fifth embodiment, the center distance d of the two irradiation points P ₁ and P ₂ is irradiated by the welded object 18 corresponding to the irradiation points P ₁ and P ₂ , as shown in FIG. 20. It is determined that the plasma generated at the localized areas are coalesced to form an elliptical plasma region.

However, the above butt welding method can be implemented with a welding apparatus that does not use any type of beam separation mirror that divides the laser beam into two sub beams. For example, the welding method may be performed by a welding apparatus in which the laser beam is separated into sub-beams by any suitable means other than the separating mirror, or in which a plurality of laser beams are generated at each laser source.

1, 9, and 12, when the relative axial and circumferential positions of the inner and outer members 30, 32 are properly adjusted, the inner and outer reflecting surfaces 36, 38 together are parabolic mirrors 14 Will form a single continuous parabolic reflective surface 34. Similarly, once the relative axial and circumferential positions of the outer and inner members 124, 126 are properly adjusted, the outer and inner reflecting surfaces 128, 130 of the planar mirror 122 in the embodiment of FIG. 11 are united together. A continuous planar reflecting surface is formed. However, the inner and outer reflecting surfaces need not be able to form a single continuous reflecting surface. For example, the inner and outer reflecting surfaces can be planar and parabolic surfaces, respectively.

As mentioned above, although preferred embodiments of the present invention have been described with reference to the accompanying drawings, various modifications and improvements can be made without departing from the scope of the present invention as set forth in the following claims.

According to this aspect, the individual members of the beam splitter can make relative displacements with respect to each other, so that if necessary the position of the reflecting surface can be changed to alter the arrangement of the irradiation points of the plurality of sub-beams reflected by each part of the reflecting surface. You can change the relative position of the surface of the parts. In this way, the versatility of the beam separation mirror becomes large.

In addition, since one of the plurality of individual subheads of the beam separator can be replaced with another, the versatility of the beam separator is further improved.

According to another aspect, no special mechanism is needed to displace the individual members relative to each other. Therefore, the configuration of the beam separation mirror can be simplified, and the versatility regarding the arrangement of the irradiation points of the sub-beams reflected by the portion of the reflecting surface becomes very large. Further, irrespective of the area of the portion of the reflecting surface of the beam splitter, the amount of energy at the irradiation point of the sub beam can be easily stabilized.

According to another aspect, good butt welding is possible even if there is a butt gap at the boundary of the two welded joints, since the irradiated points of the sub-beams swing in the direction crossing the weld line, so that they do not align with the butt gap. This reduces the amount of light that passes through the butt gap.

According to another aspect, since the phase difference between the paths of the two sub-beam irradiation points corresponds to half of the cross interval, half the intervals of one path are placed between adjacent half gaps of the other path, whereby the two irradiation points are welded. They occupy the same area on both sides of the butt welded seam. Thus, this area is uniformly irradiated with the two sub beams along the respective paths. It is possible to reliably butt weld with this welding method without reducing the movement speed of the sub-beam irradiation point, that is to say without reducing the welding speed.

According to another aspect, the subbeams do not pass through the butt gaps between the two workpieces to be butt welded together. Since the entire irradiated point of each subbeam is located within the area of the corresponding weldment, an appropriate local portion of the weldment can be sufficiently melted and the molten metal fills the butt gap, resulting in the undercut or other welding. It can be well butt welded without defects. In this way, with this welding method, even if there is a butt gap in the end face of the workpiece to be welded, satisfactory butt welding can be performed without swinging the sub-beam irradiation point.

According to another aspect, the butt gap can be filled with molten metal by effectively utilizing heat generated in the plasma region. Also in this way, a satisfactory butt weld is achieved even if a butt gap exists between the workpieces.

According to another aspect, the subbeams do not pass through the butt gaps between the two workpieces to be butt welded together. Since the entire irradiated point of each subbeam is located within the area of the corresponding weldment, an appropriate local portion of the weldment can be sufficiently melted and the molten metal fills the butt gap, resulting in the undercut or other welding. It can be well butt welded without defects. In this way, with this welding method, even if there is a butt gap in the end face of the workpiece to be welded, satisfactory butt welding can be performed without shaking the sub-beam irradiation point.

Claims (21)

A laser beam generator for generating a laser beam, and a beam splitter for separating the laser beam generated at the laser beam into a plurality of sub-beams having individual different optical axes, wherein the beam splitter corresponds to the plurality of sub-beams. In a laser optical system having a reflecting surface comprising a plurality of parts, And the beam separation mirror includes a plurality of individual members that are assembled to each other to provide a plurality of portions of the reflective surface, respectively. The method of claim 1, wherein the plurality of individual members are (a) the angle of the axis of each sub-beam relative to the axis of the laser beam incident on the reflecting surface of the beam splitter, or (b) the laser incident on the reflecting surface. And configured and assembled such that the relative positions of the plurality of portions in the beam axial direction can be changed. The method of claim 1, wherein the plurality of individual members provides at least one planar interface that intersects the reflecting surface of the beam splitter, thereby forming at least one straight intersection line between the plurality of individual members, the intersecting line defining the reflecting surface of the plurality of individual members. And act as one or more straight boundaries dividing into parts. 2. The apparatus of claim 1, wherein the plurality of individual members provides at least one cylindrical interface that intersects the reflective surface of the beam splitter so that at least one cross loop is formed therebetween, and the loop forms the reflective surface in the plurality of portions. And act as one or more boundary loops to divide into. 5. The beam separating apparatus according to claim 4, wherein said beam splitter consists of a parabolic mirror having a parabolic reflecting surface for focusing and reflecting an incident laser beam, said parabolic mirror having an outer member having a cylindrical central bore, and relative to the outer member. An inner member that is displaceably fitted to the central bore, the outer member providing an annular outer reflecting surface, the inner member forming a parabolic reflecting surface of the parabolic mirror together with the annular outer reflecting surface And a circular inner reflective surface. 5. The beam splitter according to claim 4, wherein said beam splitter consists of a planar mirror having a flat reflecting surface that reflects an incident beam, said planar mirror having an outer member having a cylindrical center bore and said center to permit relative displacement with respect to said outer member. An inner member fitted to the bore, the outer member providing an annular outer reflecting surface, and the inner member providing a circular inner reflecting surface that together with the annular outer reflecting surface form a flat reflecting surface of the plane mirror. Laser optical system, characterized in that. The laser optical system of claim 1, further comprising a positioning mechanism for adjusting the relative position of the plurality of individual members of the beam separation mirror. In the laser welding equipment for welding two welded objects by laser, A welding head comprising a laser optical system according to any one of claims 1 to 7, for forming irradiation points of a plurality of sub-beams on which the centers are spaced apart from each other on the surfaces of the two workpieces; And a relative movement device for moving the irradiation points of the plurality of sub-beams and the two welded objects with respect to each other. The relative movement device of claim 8, wherein the relative motion device comprises: a relative motion between the irradiation point and the two welded objects in a direction parallel to a weld line in which the two welded objects are welded to each other such that the irradiation points of the plurality of sub-beams move with respect to the two welded objects. Laser welding device comprising a transfer device for giving. 9. The relative motion device of claim 8, wherein the relative motion device swings the irradiation points of the plurality of sub-beams in a direction that intersects the weld line to which the two welded objects are welded to each other, and the center of the rocking stroke of each irradiation point is substantially on the weld line. And a rocking device for imparting a relative motion between the irradiated point and the two welded objects. 9. The laser welding device according to claim 8, further comprising a positioning device for adjusting a distance between the welding head and the surfaces of the two workpieces. A laser welding method for welding two welded objects with a laser by using the laser welding device according to any one of claims 8 to 11. The method of claim 12, wherein the plurality of sub-beams consist of two sub-beams each reflected by two portions of the beam splitter, wherein the irradiation points of the two sub-beams are parallel to a defined weld line where the two welded objects are welded to each other. Positioned in one direction, the irradiation points being spaced apart from each other in a direction parallel to the weld line and being moved relative to the two welded objects along the weld line by the relative motion device. The method of claim 12, wherein the plurality of sub-beams consist of two sub-beams each reflected by two portions of the beam splitter, the irradiating points of the two sub-beams being parallel to a defined weld line where the two welded welds are welded to each other. Direction, the irradiating points are spaced apart from each other in a direction parallel to the weld line, the irradiating points are moved relative to the two welded objects along the weld line by the relative motion device while shaking the weld line. Laser welding method. 15. The method of claim 14, wherein the irradiation points move on the surface of the two welded joints along two separate paths that intersect the weld line at defined intervals in a direction parallel to the weld line, wherein the two routes are defined above. Laser welding method characterized in that it has a phase difference corresponding to half. 13. The method of claim 12, wherein the plurality of sub-beams consist of two sub-beams each reflected by two portions of the beam splitter, wherein the irradiation points of the two sub-beams intersect a prescribed weld line where the two welded welds are welded to each other. And the irradiation points are centered on both sides of the welding line and are moved relative to the two welded objects in a direction parallel to the welding line by the relative motion device. 17. The method of claim 16 wherein the distance between the weld head and the two surfaces to be welded is determined differently from the focal lengths of the two subbeams such that the focus of the two subbeams is biased from the surfaces of the two weldments where the irradiation points of these subbeams are formed. And wherein the distance between the centers of the irradiation points is determined such that the irradiation points of the two sub-beams together form a continuous irradiation region of the sub-beams formed at least adjacent to each other and across the weld line. 17. The welded joint of claim 16 wherein the two welded bodies each have a cross section and are butt welded together at this cross section along the weld line, the distance between the centers of the two sub-beam irradiated points being located on both sides of the weld line inside the cross section. Laser welding method characterized in that it is determined to. 17. The method of claim 16 wherein the two weldments each have a cross section and are butt welded together at this cross section along the weld line, wherein the distance between the centers of the two subbeam irradiation points is generated by irradiating a local portion on the surface of the weld target. And the plasmas are determined to associate with each other to form a substantially continuous plasma region. A laser welding method in which two welded objects each having a cross section are butted in the cross section, and the surfaces of the two welded welds are irradiated with a laser along a weld line to which the welded portions are butt welded. Positioning the irradiation points of the two laser beams such that the irradiation points of the two laser beams formed on the surfaces of the two welded portions are positioned in the direction intersecting the welding line and the centers of these irradiation points are on both sides of the welding line. Wow, Determining a distance between the centers of the irradiation points such that each irradiation point is located inside the corresponding section; And relatively moving the irradiation point and the two welded objects according to the welding line. 21. The laser according to claim 20, wherein the distance between the centers of the irradiation points is determined so that the plasmas generated by the two sub-beams irradiating a localized portion on the surface of the workpiece to associate with each other to form a substantially continuous plasma region. welding method.