JP3126790B2 - Laser welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding apparatus, and more particularly to a laser welding apparatus capable of controlling the injection angle of an assist gas from an assist gas nozzle to a laser weld.

[0002]

2. Description of the Related Art A laser welding apparatus for performing welding such as butt welding by irradiating a workpiece with a laser beam from a laser processing head is conventionally known.

[0003] In laser welding using a laser welding apparatus, the temperature of a workpiece to be welded is increased due to the irradiation of the workpiece with a laser beam. It is known that a high-intensity plasma cloud is generated, which has an adverse effect of absorbing and diffusing the laser beam, thereby reducing the energy or the density of the laser beam reaching the workpiece. .

For this reason, an assist gas consisting of an inert gas such as an argon gas or a nitrogen gas is injected into the laser welding portion from the front in the traveling direction of the laser processing head using an assist gas nozzle, and the assist gas blows out the plasma cloud and eliminates it. In addition, it has been conventionally performed to suppress the generation of a plasma cloud around a laser weld.

The injection of the assist gas, besides the removal of the plasma cloud, promotes the flow of the molten metal in the laser-welded portion of the workpiece, and enhances the homogeneity of the material of the laser-welded portion and the uniformity of the shape of the weld bead. This also has the effect.

[0006]

The injection of the assist gas promotes the flow of the molten metal in the laser-welded portion of the workpiece, thereby improving the homogeneity of the material of the laser-welded portion and the uniformity of the shape of the weld bead. To get the effect positively,
There is an optimum value of the assist gas injection angle for the laser weld. The optimum value of the assist gas injection angle changes according to the welding conditions such as the material of the workpiece, the plate thickness, the shape of the welding surface, the laser intensity, and the welding speed.

The present invention has been made in view of the above-mentioned problems in the conventional laser welding apparatus, and can set the assist gas injection angle to an optimum value in various laser weldings. It is an object to provide an improved laser welding device.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides an assist gas nozzle mount movably up and down ahead of a laser processing head for performing laser welding on a workpiece. A vertical actuator for automatically moving the mount up and down is provided, and an assist gas nozzle for injecting an assist gas to a laser welded portion of the workpiece is rotatably mounted on the assist gas nozzle mount in a vertical direction. And a servo motor for automatically rotating the assist gas nozzle in the vertical direction, and the injection angle of the assist gas from the assist gas nozzle without changing the injection position of the workpiece to the laser welded portion. Can be changed.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 4 shows an example of a laser welding apparatus to which the present invention is applied. This laser welding apparatus is basically a laser welding apparatus of a three-optical axis moving system, and has a fixed work table 1 on which a workpiece W is fixedly mounted, and straddles the work table 1 in the Y coordinate axis direction. The gate-shaped X-axis movable frame 5 guided by the X-coordinate axis guide portion 3 of the worktable 1 and movable in the X-coordinate axis direction with respect to the worktable 1, and the Y-coordinate axis guide portion 7 formed on the X-axis movable frame 5 A Y-axis carriage 9 that is engaged with the X-axis movable frame 5 and is movable in the Y-coordinate axis direction. The laser machining head mounting member 11 is movable in the Y-axis carriage 9 in the Z-coordinate direction (vertical direction). Attached to.

X-axis movable frame 5 moves in X-coordinate direction,
As shown in FIG. 3, the movement of the Y-axis carriage 9 in the Y-coordinate direction and the movement of the laser processing head mounting member 11 in the Z-coordinate direction are respectively performed by the X-axis servo motor 13, the Y-axis servo motor 15, and the Z-axis servo. This is performed by a motor 17.

A laser processing head 19 is mounted on the laser processing head mounting member 11. Laser processing head 1
Reference numeral 9 denotes an A-axis, a B-axis, and a C-axis as shown in FIGS.
It is a three-axis movable type with a horizontal B
A bent mirror case member 23 rotatably mounted in a predetermined angle range around the axis, for example, in an angle range of 180 degrees, and an upper head member rotatable around the A axis orthogonal to the B axis by 360 degrees on the bent mirror case member 23; 25, and a lower head member 27 attached to the upper head member 25 so as to be able to expand and contract in the axial direction of the A-axis, that is, the C-axis direction. A laser beam irradiation hole 29 is formed at the tip of the lower head member 27. ing. The laser processing head 1 is provided in the laser beam irradiation hole 29.
The laser beam arrives via a laser beam passage space (not shown) formed in each of the above-mentioned members 9.

The A-axis rotation of the upper head member 25, the B-axis rotation of the bent mirror case member 23, and the C-axis movement of the lower head member 27, as shown in FIG. The operation is performed by a B-axis servomotor 33 and a C-axis servomotor 35.

The optical axis of the laser beam at the upper head member 25 and the optical axis of the laser beam at the lower head member 27 extend on the same axis. The A axis matches each other. Therefore, the upper head member 25 and the lower head member 27 rotate with respect to the bent mirror case member 23 around the optical axis of the laser beam extending on the same axis as the A-axis. The irradiation position of the laser beam on the workpiece W, that is, the laser welded portion P does not change.

One side of the upper head member 25 is provided with an assist gas nozzle mount 3 by a vertical actuator 37.
9 is mounted so as to be able to move up and down. An assist gas nozzle 43 is attached to the assist gas nozzle mount 39 by a horizontal pivot 41 so as to be vertically movable.
The assist gas nozzle 43 can be tilted up and down within a predetermined range by pivoting about the pivot 41 with respect to the assist gas nozzle mount 39. The assist gas nozzle 43 has a slit-shaped injection port 45 extending at a lower end portion with a predetermined width of about 10 to 20 mm in the horizontal direction. The assist gas made of argon gas, nitrogen gas or the like supplied from a gas hose 47 is slit-shaped. The laser beam from the laser beam irradiating hole 29 is radiated to the workpiece W, that is, to the laser welding portion P and its vicinity, with a band-shaped flat jet flux from the nozzle hole 45.

In this case, the injection direction of the assist gas to the laser welded portion P by the assist gas nozzle 43 is variable around the laser welded portion P within a 360 ° rotation range by the A-axis rotation of the upper head member 25. By this rotation, the assist gas injection direction of the assist gas to the laser welding portion P by the assist gas nozzle 43 is set forward of the laser processing head 19 in the traveling direction.

A servo motor 4 for tilting the nozzle is provided on the pivot 41.
9 is drivingly connected to the servo motor 4 for tilting the nozzle.
Reference numeral 9 designates the assist gas nozzle 43 via the pivot 41
By rotating around the center 1, it is tilted vertically by a predetermined range.

As shown in FIG. 2, the assist gas nozzle 43 has a slit formed by combining tilting about the pivot 41 and vertical movement by the assist gas nozzle mount 39 without changing the injection position with respect to the laser welding portion P. In other words, the injection angle of the assist gas from the injection nozzle 45 is changed. The injection angle of the assist gas that can be changed is 4 degrees when viewed from the injection angle θ of the assist gas with respect to the workpiece W.
It may be about 0 to 60 degrees.

FIG. 3 shows a control system configuration of the assist gas injection control device according to the present invention and the N of the laser welding device related thereto.
C device is shown. The NC unit of the laser welding device is N
An NC program analysis unit 51 for taking in the C program and analyzing the NC program is included. The NC program analysis unit 51 converts the X-axis command signal, Y-command signal, Z-axis command signal, A-axis command signal, B-axis command signal, and C-axis command signal into an X-axis servo control unit 53 and a Y-axis servo control unit 55, respectively. , Z-axis servo controller 57, A-axis servo controller 59, B-axis servo controller 61, and C-axis servo controller 63.

The NC program analysis unit 51 stores assist gas optimum injection angle information based on welding conditions written in the NC program based on welding conditions such as the material of the work to be welded, plate thickness, irregularities and other welding surfaces, laser intensity, and welding speed. And outputs a nozzle vertical movement command signal found therefrom to the nozzle vertical movement servo controller 65 of the vertical movement actuator 37, and outputs the nozzle tilt command signal to the nozzle tilt servo motor 4.
9 to the nozzle tilting servo control section 67.

Each servo system may be of a closed loop type by feedback control using an encoder or the like, and the configuration of the closed loop type servo system may be of a known configuration. Omitted.

According to the above configuration, the X-axis movable frame 5 is moved in the X-coordinate direction by the X-axis servomotor 13 according to the NC program, and the Y-axis carriage 9 is moved in the Y-coordinate direction by the Y-axis servomotor 15. Accordingly, the laser processing head 19 moves while tracking the predetermined welding line L of the work W to be welded on the work table 1, whereby the laser welding portion P by the laser processing head 19 moves along the welding line L. It moves and laser welding is automatically performed along the welding line L.

Under the laser welding as described above, the A-axis servo motor 31 is driven based on the A-axis command signal from the NC program analysis unit 51 input to the A-axis servo control unit 59. 25 rotates the A-axis, and the assist gas nozzle 43 is always positioned forward in the traveling direction of the laser processing head 19.

The vertical movement actuator 37 is driven by a nozzle vertical movement command signal from the NC program analysis unit 51 input to the nozzle vertical movement servo control unit 65,
As a result, the assist gas nozzle mount 39, in other words, the pivot 41 is automatically moved up and down, and the NC program analysis unit 51 input to the nozzle tilt servo control unit 65.
The nozzle tilt servo motor 49 is driven by the nozzle tilt command signal from
It is automatically tilted about 1.

Thus, the assist gas nozzle 37 supplies the assist gas to the laser welding portion P from the front in the traveling direction of the laser processing head 19 with a flat jet stream having a band shape from the slit-shaped nozzle 39, and the material of the workpiece W at this time. , Board thickness,
Injection is performed at an optimum injection angle θ according to welding conditions such as a welding surface shape such as unevenness, laser intensity, and welding speed.

In this case, the optimum injection angle of the assist gas is
The larger the plate thickness of the object to be welded or the higher the welding speed, the smaller the melting point of the object to be welded or the stronger the laser intensity.

In one laser welding, the workpiece W has irregularities, or changes in laser intensity and welding speed.
If there is a variation, the assist gas nozzle 37 may be moved up and down and tilted according to the change of the optimum injection angle of the assist gas, whereby the injection angle θ of the assist gas may be always maintained at the optimum injection angle. . That is, in one laser welding, the assist gas nozzle 37 may move up and down and tilt so that the injection angle θ of the assist gas maintains the optimum injection angle.

In the above-described embodiment, planar laser welding is assumed by moving the laser processing head 19 in the X-coordinate axis direction and the Y-coordinate axis direction. The above-described three-dimensional laser welding by combining the movement of the processing head 19 in each of the X, Y, and Z coordinate axes with the B-axis rotation and the C-axis movement of the laser processing head 19 is also described. This is applied in the same manner as in the embodiment, and in this case, the same operation and effect as those in the above-described embodiment can be obtained.

The assist gas injection control device according to the present invention is not limited to the laser welding device of the three optical axis moving type, but can be applied to other types of laser welding devices and laser welding devices by robots.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to these embodiments, and various embodiments can be made within the scope of the present invention. Some will be apparent to those skilled in the art.

[0031]

As will be understood from the above description, according to the present invention, the assist gas nozzle mount 39 provided on the front side in the traveling direction of the laser processing head 19 for performing laser welding on the workpiece W is provided with a vertical actuator. 37
The assist gas nozzle 43 attached to the assist gas nozzle mount 39 so as to be vertically rotatable is automatically rotated vertically by a servo motor 49. And
The injection angle of the assist gas can be changed without changing the injection position of the assist gas from the assist gas nozzle 43 to the laser welding portion P of the workpiece W.

Therefore, according to the present invention, the assist gas can be supplied without changing the injection position with respect to the laser welded portion in accordance with the welding conditions such as the material, plate thickness, welding surface shape, laser intensity, welding speed, etc. of the workpiece. Can be changed, and appropriate and high-quality laser welding can always be performed according to various laser welding conditions.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an essential part of an embodiment of an assist gas injection control device of a laser welding device according to the present invention.

FIG. 2 is a side view showing an essential part of an embodiment of an assist gas injection control device of the laser welding device according to the present invention.

FIG. 3 is a block diagram showing one embodiment of a control system configuration of an assist gas injection control device according to the present invention and an NC device of a laser welding device related thereto.

FIG. 4 is a schematic perspective view showing one example of a laser welding apparatus to which the assist gas injection control device according to the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Work table 5 X-axis movable frame 9 Y-axis carriage 11 Laser processing head mounting member 19 Laser processing head 29 Laser beam irradiation hole 37 Vertical movement actuator 39 Assist gas nozzle mount 41 Axis 43 Assist gas nozzle 45 Slit nozzle 49 Servo motor for nozzle tilting 51 NC program analysis unit 65 Nozzle vertical movement servo control unit 67 Nozzle tilting servo control unit

Claims (1)

(57) [Claims] An assist gas nozzle mount (39) is provided movably up and down in front of a laser processing head (19) for performing laser welding on an object to be welded (W), and the assist gas nozzle mount (39) is automatically moved. And an assist gas nozzle (43) for injecting assist gas to a laser welded portion (P) of the workpiece (W) is provided with the assist gas nozzle mount (37). And a servomotor (49) for automatically rotating the assist gas nozzle (43) in the vertical direction, and a laser for the workpiece (W). The injection angle of the assist gas from the assist gas nozzle (43) can be changed without changing the injection position with respect to the welding portion (P). A laser welding apparatus characterized in that: