JPH03243292A - Laser welding machine - Google Patents

Abstract

PURPOSE:To make improvement in the ease of the laser welding procedure in a narrow joint part by using an eccentric condenser lens having a polarizing angle on the rear with the laser welding machine which deviates a focus by the condenser lens. CONSTITUTION:The focus of a laser beam 1 emitted from a laser oscillator is deviated by using the eccentric condenser lens 5 having the polarizing angle on the rear as the condenser lens of the laser welding machine which welds a work by transmitting the above-mentioned transmission beam with a transmission path to a condensing part and deviating the focus by the condenser lens. A driving mechanism for rotationally driving the eccentric condenser lens 5 is provided for this purpose to irradiate the work with the laser beam. The laser welding machine which allow the easy holding of the condenser lens and can securely join the work even in the narrow joint part is obtd. in this way.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a laser welder.

(Prior art) Conventionally, multiple stacked steel plates, etc. can be quickly and
A resistance welder is used to ensure a good joint.

However, with this resistance welding machine, the tip of the electrode wears out as the number of times we weld increases, and the area where pressure and current are applied increases, so the electrode tip must be reshaped regularly.

In addition, the welding part of the steel plates to be joined requires a certain amount of overlap determined by the plate thickness, and as the plate thickness increases, the welding current is welded first and then flows to the adjacent welded part.
Again, a distance of more than one room is required.

Therefore, a laser welding machine shown in FIG. 5 is available as a welding method that compensates for these drawbacks.

That is, in the laser welding machine shown in the figure, the optical axis of the laser beam 1 transmitted from the not-shown laser propagation path into the processing head 13 of the not-shown laser propagation path and α. A condensing lens 12 decentered by 1 is housed so as to be rotatable in the direction of arrow β1 via a holder and a rotational drive mechanism (not shown). By focusing the light at point 12, an annular welded portion is obtained at the focusing point as indicated by arrow β2.

As a result, with this laser welding machine, even if the overlapping margin of stacked steel plates is narrow, they can be joined as long as the width of the diameter of the annular weld is approximately the same as described above, and the spacing between the annular welds is also required. It can be set arbitrarily according to the specifications.

(Problem to be Solved by the Invention) However, in the laser welding machine configured in this way, as shown in FIG. In order to obtain a focusing distance of 12 oscillates, making the cooling structure difficult and difficult to put into practical use.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser welding machine that can easily and powerfully weld even narrow joints.

[Structure of the invention]

(Means and Effects for Solving the Problems) The present invention provides a laser welding machine that transmits a laser beam emitted from a laser oscillator to a condensing section, decenters it with a condensing lens, and welds a workpiece. By using an eccentric condensing lens with a polarization angle on the back surface and installing a drive mechanism to rotate this eccentric condensing lens, the workpiece is irradiated with the focused laser light, making it easy to hold the condensing part. This is a laser welding machine that can powerfully join workpieces.

(Example) Hereinafter, an example of the laser welding machine of the present invention will be described with reference to the drawings.

First, the inventors considered a combination of lenses shown in FIG. 2(a) as a condensing optical system for the laser welding machine of the present invention.

This laser welding machine receives a laser beam 1 transmitted through a transmission path (not shown) with a prism 11 having a polarization angle α1, and directs the transmitted light to a condensing spherical surface that has the same diameter as the prism 11 and is provided concentrically adjacent to the prism 11. By rotating the prism 11 alone or the prism 11 and the condensing spherical lens 12, the workpiece is heated annularly and melted and bonded by concentrating the transmitted laser beam l and the eccentric condensing part by the lens 12. It is something to do.

Here, the radius of rotation R of the focal point is expressed by the following equation.

R= f (n −1) tanα ・・・・・・
(1) However, f: Focusing distance of the focusing spherical lens 12 n: Refractive index of the focusing lens 12 In this optical system, the prism 11 and the focusing lens are coaxial with the laser beam 1. By providing the lens 12, the prism 11 and the condensing lens 12 can be rotated without swinging, which facilitates the cooling configuration of the optical system components, making it possible to put it into practical use.

However, this optical system has two optical components, so
The holding mechanism is complicated and the accuracy may vary.

In order to solve these problems, the inventors further put into practical use a condensing optical system shown in FIG. 2(b).

In the same figure, the polarized light condensing lens 5 is a lens 5 having a polarization angle α on the back surface of the condensing lens 12 shown in FIG. 5, and is provided coaxially with the transmitted laser beam l.
As shown in the figure, the focal point is also eccentric.

FIG. 1 is a longitudinal sectional view of the head portion of a laser welding machine incorporating this polarized light condensing lens 5.

In the figure, at the lower end of an end pipe 4 attached to the end of a transmission line of a laser welding machine (not shown).

A substantially cylindrical outer tube 4a is attached concentrically to the end pipe 4, a nozzle 8 is screwed to the lower end of the outer tube 4a, and a pneumatic joint 7 is screwed to the upper right side of the nozzle 8. A shield gas supply pipe (not shown) is connected to the nozzle 8, and a cylindrical capacitive distance sensor 10 is inserted into the lower end of the nozzle 8.

In addition, an inner tube 4b having a bearing 9 rigged on the outer periphery of the lower end is inserted into the outer tube 4a coaxially with the outer tube 4a from below, and a nut 4b screwed onto the outer periphery of the inner tube 4b. The bearing 9 is fixed to the outer tube 4a and the inner tube 4b with a nut 9a screwed inside the lower end of the tube 4a, so that it is rotatably supported by the outer tube 4a, and a spur gear 3B is attached to the outer circumference of the upper end of the inner tube 4b. is tightened with a nut 3B□ on the outside of the upper end inserted through a key (not shown).

Further, a DC motor 2 is vertically provided on the right side of the end pipe 4, and a pinion 3A meshing with a spur gear 3B is inserted into the output shaft of the DC motor 2 via a key (not shown) and fixed with a nut. , are protected by a cover 40 attached from the outside to the right side of the end pipe 4 and the right side of the outer tube 4a.

Furthermore, an aluminum cylindrical cooling tube 6 is screwed onto the lower end of the inner tube 4b from below, and inside the threaded portion of the cooling tube 6 is a polarized light condenser shown in FIG. 2(b). The optical lens 5 is inserted from above and fixed from above with an O-ring 5a and a nut 5b, and the outer periphery below the middle part of the cooling tube 6 is provided as shown in FIG. cooling fins 6 in a gear shape.
a is formed.

Next, the operation of the laser welding machine configured in this way will be explained.

The laser beam l transmitted from a laser oscillator (not shown) and condensed by the polarization condensing lens 5 is eccentrically focused from the optical axis 1a of the laser beam at the focal position. If the focal length of lens 5 is 5 inches and the polarization angle is 0.64°, then 2m+++ is obtained from equation (1).
bawl.

Now, when the DC motor 2 is driven, the inner tube 4B rotates via the pinion 3A and the spur gear 3B, and the polarized light condensing lens 5 rotates together with the cooling cylinder 6, so that the locus of the focal point becomes 4 mm in diameter.
mm, and the shielding gas discharged from the pneumatic joint 7 into the nozzle 8 at this time was blown onto the cooling fins 6a of the rotating cooling cylinder 6 and heated by heat transfer from the polarizing condenser lens 5. The heat of the cooling tube 6 is absorbed and the nozzle 8
It flows below, flows through the capacitance distance sensor 10, and is supplied to the irradiation part of the workpiece.

Here, there are roughly two methods for welding the workpieces to be joined.

One method is to form an annular surface bead 14 on the workpiece surface as shown in FIG. 3(b) and a melt penetration 15 as shown in the cross-sectional view of FIG. 3(c). As shown in a), the laser beam irradiation is interrupted, the laser transmission line (not shown) is driven, the nozzle 8 is moved a predetermined distance in the direction of the welding line of the workpiece, and the laser beam is irradiated again as shown in the figure ('a). The same figure (b) is obtained by irradiating the workpiece.

This is a method in which a surface beat 14 and a melt penetration 15 shown in (c) are obtained, and this process is repeated thereafter.

The inventors set the circumferential speed of the focal point to 1 m/m with the polarizing lens 5 described above.
3 (b), (C
), a welded part with a surface beat 14 and a weld penetration 15 was obtained, and as a result, a workpiece with little welding distortion was obtained.

In addition, the inventors have proposed another welding method in which the eccentric focusing lens 5 is replaced and the eccentric distance of the focal point is 0.5 mm, and the laser beam is continuously applied to the workpiece as shown in FIG. 4(a). At the same time, a laser transmission line (not shown) is continuously moved in the direction of the welding line of the workpiece to weld the two stacked mild steel plates to form a surface bead 16 with a width of 1 mm as shown in Figure (b). A melt penetration 17 was obtained as shown in the cross-sectional view of FIG.

In this case, the amount of heat input increases, so there is a disadvantage that distortion occurs in the workpieces, but even if there is a slight gap between the stacked plate-like workpieces or the overlapping margin is narrow, it can be strongly joined. , it also has the advantage of being applicable to the butt part of the workpiece.

In the above embodiment, the cooling fins 6a on the outer periphery of the cooling cylinder 6 are shaped like a gear, but they may also be shaped like a male thread of a ball screw. In this case, there are advantages that manufacturing is easy, the cooling effect is constant regardless of the rotation speed, and the noise caused by the blowing of assist gas is reduced.

〔Effect of the invention〕

As described above, according to the present invention, in a laser welding machine that transmits a laser beam emitted from a laser oscillator to a condensing part through a transmission path, and welds a workpiece by decentering the focal point with a condensing lens, the back surface of the condensing lens is used. A polarized condensing lens with a polarization angle is used to decenter the focal point, and a drive mechanism is installed to rotate this decentered condensing lens to irradiate the workpiece.The condensing lens can be easily held and can be used even in narrow joints. A laser welding machine capable of powerfully joining workpieces can be obtained.

[Brief explanation of drawings]

The second construction drawing is a diagram showing an embodiment of the laser welding machine of the present invention.
Figure (a) is a vertical cross-sectional view of the main part, Figure (b) is a cross-sectional view taken along line A-A in Figure (a), Figures 2 (a), (b), Figure 3 (a),
(b), (c) and Fig. 4 (a), (b), (c) are diagrams showing the operation of the laser welding machine of the present invention, and Fig. 5 is a diagram showing the main parts of a conventional laser welding machine. It is. 1. Laser light 2. DC motor 3. Polarized condensing lens 6. Cooling tube (8733) Agent Patent attorney Yoshiaki Inomata (and 1 other person) (a) (b) Figure (a) (b) (c) The first round A-A bait surface (b)

Claims (1)

[Claims] In a laser welding machine that transmits a laser beam emitted from a laser oscillator to a condenser and decenters it with a condenser lens to weld a workpiece, the condenser lens is an eccentric condenser lens with a polarization angle on the back or front surface. . A laser welding machine, characterized in that the condensing section is provided with a drive mechanism for rotationally driving the eccentric condensing lens.