JP2000271773A - Laser beam emitting optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam emitting optical system capable of forming beam converging spots of three or more with a laser beam from one optical fiber and changing an output ratio of these three beam converging spots. SOLUTION: A prism box, which forms at least three beam converging spots to a member 13 to be worked by dividing a laser beam from a recollimate lens into three, is arranged between the recollimate lens 11 and a machining lens 12, Inclined prisms 14A, 14B are accommodated in the prism box. The laser beam from the recollimate lens is divided into two laser beams passing through the two inclined prisms and a laser beam passing through between the two inclined prisms so as to respectively make incidence on a machining lens 12. Further, the laser beam divided into three is converged by the machining lens, three converging spots A, B, C are formed to the member 13 to be worked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a laser processing apparatus for performing processing such as welding by laser light,
The present invention relates to a laser emission optical system having a function of irradiating a workpiece with three or more focused spots.

[0002]

2. Description of the Related Art Various types of laser processing apparatuses for welding metal members and the like with laser light have been provided. This type of laser processing apparatus introduces laser light from a laser oscillator through an optical fiber into an optical system called an emission optical system, and irradiates a workpiece through the optical system. The exit optical system is usually used to collimate the laser light expanding from the end face of the optical fiber into a collimated lens, and collect the collimated light from the collimating lens to form a converged spot on the workpiece. Built-in processing lens.

By the way, in welding by laser light, a method has been proposed in which processing is performed not with one converging spot but on three converging spots. This is because, depending on the material to be welded, rapid heating or rapid cooling may cause defects such as cracks. Such a possibility increases in a low-temperature environment such as a cold region. For this reason, when welding a material that requires preheating and slow cooling, preheating is performed at the first condensing spot, main processing is performed at the next condensing spot, and slow cooling is performed at the last condensing spot. A method is needed.

There are the following emission optical systems for forming three converging spots.

(1) A method in which laser beams emitted from three optical fibers are respectively condensed on a workpiece through another recollimating lens and a processing lens.

(2) A method in which laser light emitted from three optical fibers is condensed on a work via one recollimating lens and a processing lens.

[0007]

However, in the method (1), three combinations of the recollimating lens and the processing lens are required, and the size of the output optical system is increased. Further, the method (2) also requires three optical fibers, which complicates the configuration around the emission optical system.

Accordingly, an object of the present invention is to provide a laser emitting optical system that can form three or more converging spots with laser light from one optical fiber and can change the output ratio of these three converging spots. To provide a system.

Another object of the present invention is to provide a laser emission optical system capable of changing the interval between three condensed spots.

[0010]

SUMMARY OF THE INVENTION The present invention has a built-in recollimating lens and a processing lens for converting a laser beam from an incident portion into parallel light, and emits a laser beam to a member to be processed by a condensing spot of the laser beam. In the optical system, the laser beam is divided into at least three beams between the incident section and the recollimating lens or between the recollimating lens and the processing lens, and at least three light beams are focused on the workpiece. An optical system for forming a spot is arranged.

The optical system has at least two inclined prisms spaced apart from each other in a pass band of the laser beam from the recollimating lens, and at least two laser beams passing through the at least two inclined prisms. By making light and laser light passing between the at least two inclined prisms incident on the processing lens, at least three condensed spots are formed in a straight line on the member to be processed.

By providing a moving mechanism for moving the at least two inclined prisms in a direction perpendicular to the optical axis of the laser beam, the energy ratio of the at least three condensed spots can be made variable.

[0013] Further, as the at least two inclined prisms, prisms having a gradient such that they become thinner from the inside to the outside and projecting toward the processing lens are used, and those having different inclination angles are used. The use can change the interval between the at least three light-converging spots.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing a preferred embodiment of the present invention with reference to FIG. 1, the principle of operation will be described. Laser light from a laser oscillator is introduced into the laser emission optical system through an optical fiber 10. The laser emission optical system is
A collimating lens 11 for collimating the laser light expanded from the emission end face of the optical fiber 10 into parallel light; and a collimating lens 11 for converging the parallel light from the collimating lens 11 to form a converged spot on the workpiece 13. A processing lens 12 is incorporated.

In addition to these lenses, two inclined prisms 14A and 14C are provided between the recollimating lens 11 and the processing lens 12 and in the passband of the laser beam from the recollimating lens 11 with an interval therebetween. Have been placed. Here, each of the two inclined prisms 14A and 14C has a gradient of an angle α that is inclined so as to become thinner from the inside to the outside, and is convex toward the processing lens 12 side. As a result, the laser light from the recollimating lens 11 is divided into two laser lights that have passed through the two tilt prisms 14A and 14C and the two tilt prisms 14A and 14C.
The laser beam that has passed between C is divided into three, and each can be made to enter the processing lens 12. And
The laser light divided into three is condensed by the processing lens 12 and the three condensed spots A, B,
C is formed on a straight line.

In this case, the converging spots A and C can change the optical path of the laser beam by the tilting prisms 14A and 14C having the tilting angle α, and are located at the distances a and b between the converging spots B. It can be focused. These distances a and b can be changed by changing the tilt angle α of the tilt prisms 14A and 14C. Of course, changing the tilt angle α means changing the tilt prism itself.

The condensing spot B is composed of the inclined prisms 14A, 1
The light is focused by the processing lens 12 without passing through 4C. The energy ratio of the condensed spots A, B, and C can be changed by individually moving the tilt prisms 14A and 14C in a direction perpendicular to the optical axis, so that the light amounts of the three laser beams can be changed. The ratio can be set arbitrarily.

On the other hand, a prism box accommodating the above-mentioned two inclined prisms can be provided between the exit end face of the optical fiber 10 and the collimating lens 11. In this case, the distances a and b can be adjusted by making the prism box movable in a direction parallel to the optical axis of the laser beam and adjusting the distance between the emission end face of the optical fiber 10 and the inclined prism.

An embodiment of the present invention will be described with reference to FIG. 2, the same parts as those in FIG. 1 are given the same numbers. As described with reference to FIG. 1, the present laser emission optical system is disposed in the case 20 in the order of the recollimating lens 11, the tilt prisms 14A and 14C, and the processing lens 12 from the top. Optical fiber 10 (FIG. 1)
Is fixed to the upper part 20 a of the case 20.
Here, the recollimating lens 11 is composed of two lenses 11A and 11B, and the processing lens 12 is also composed of two lenses 12A and 12B.

A moving mechanism for individually moving the tilt prisms 14A and 14C in a direction perpendicular to the optical axis will be described.
The tilt prisms 14A and 14C are detachably held by prism holders 21A and 21C, respectively. The prism holders 21 </ b> A and 21 </ b> C are arranged vertically inside the prism box 22. The prism holders 21A and 21C are respectively assembled to rack and pinion stages 23A and 23C, and are individually movable in directions perpendicular to the optical axis by adjustment knobs 24A and 24C, respectively.

It is possible to obtain four or more converging spots by increasing the number of inclined prisms arranged vertically. Further, the mechanism for moving the tilt prisms 14A and 14C in a direction perpendicular to the optical axis is not limited to that described with reference to FIG. 2, and other known mechanisms may be used. Further, the laser emission optical system according to the present invention is not limited to the one in which laser light is introduced via an optical fiber.

[0022]

As described above, according to the present invention, three or more converging spots can be formed by laser light from one optical fiber, and the output ratio of the three converging spots and And a laser emission optical system capable of changing the interval between the three converging spots. Accordingly, when welding a material that requires preheating and slow cooling, it is possible to perform welding while preventing defects such as cracks.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention.

FIG. 2 is a sectional view showing an embodiment of the present invention, and FIG. 2B is a view of the internal structure of the prism box of FIG.

[Explanation of symbols]

 Reference Signs List 10 optical fiber 11 recollimating lens 12 processing lens 13 workpiece 14A, 14C inclined prism 20 case 21A, 21C prism holder 22 prism box 23A, 23C rack and pinion stage 24A, 24C adjustment knob

Claims (4)

[Claims] 1. A laser emitting optical system which incorporates a recollimating lens for converting laser light from an incident portion into parallel light and a processing lens, and irradiates a converged spot of the laser light to a workpiece to be processed. An optical system that divides the laser beam into at least three and forms at least three condensed spots on the workpiece is disposed between the recollimating lens or between the recollimating lens and the processing lens. A laser emission optical system characterized in that: 2. The laser emission optical system according to claim 1, wherein the optical system includes at least two inclined prisms spaced from each other in a pass band of the laser beam from the recollimating lens, At least two of these
By causing at least two laser beams that have passed through two inclined prisms and a laser beam that has passed between the at least two inclined prisms to be incident on the processing lens, at least three condensed spots are aligned on the workpiece in a straight line. A laser emission optical system, wherein the laser emission optical system is formed. 3. The laser emission optical system according to claim 2, further comprising a moving mechanism for moving the at least two inclined prisms in a direction perpendicular to an optical axis of the laser light, so that the at least three light condensates. A laser emission optical system wherein the energy ratio of a spot is variable. 4. The laser emission optical system according to claim 2, wherein the at least two inclined prisms have a gradient that becomes thinner from the inside to the outside and are convex toward the processing lens. A laser emission optical system characterized in that the distance between the at least three condensed spots is changed by using prisms having different inclination angles.