JPS61202787A - Laser beam machining - Google Patents

Abstract

PURPOSE:To improve the stabilized work for long term and the operation rate of the devices by protecting the optical fiber from the mutual laser beam by locating the laser optical axis of laser optical system provided at both sides of the member to be worked so as to intersect at the prescribed angle. CONSTITUTION:A joining face 4c is welded by providing laser optical systems on both sides of the member 4a, 4b to be worked and by condensing on the joining face 4c of the members 4a, 4b a laser beam 1 by each condensing lens 3 through an optical fiber 2. Each optical system locates the optical axes 6, 6 of the laser beam 1 so as to intersect at the prescribed angle without locating in a straight line, making the transmitting laser beam 5 not incident onto the lens 3 of other part even if the laser beam 1 of one part transmits the key hole, etc. to cause in the gap of the joining face 4c or at melting time. With such method the optical fiber 2 of each laser optical system can be protected from the transmitting laser beam 5 of the counter part.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a laser processing method using an optical fiber,
In particular, it relates to a method for processing a workpiece from both sides thereof.

[Technical background of the invention and its problems] When welding, for example, a plurality of workpieces using a laser guided by an optical fiber, as shown in FIG. Workpiece 4 with condensing lens 3
The light is focused on the joint surface 4c of the parts a and 4b, and this focal point is
c to weld the workpieces 4a and 4b together. However, if the welding strength between the workpieces 4a and 4b cannot be obtained by welding in only one direction due to the energy of the laser beam 1, etc., the laser optical system or the workpiece may be turned over and welded again or in the same direction. As shown in FIG. 3, a method has been used in which a laser optical system is positioned opposite to each other on both sides of workpieces 4a and 4b, and the workpieces 4a and 4b are laser welded from both sides.

However, in the former method, there are inconveniences such as turning over the workpieces 4a, 4b or the laser optical system or scanning the welding surface twice to perform welding, and the latter method in which the laser optical systems are opposed to each other. Then, the gap between the joint surfaces 4C of the workpieces 4a and 4b or the workpiece 4a
, 4b may be transmitted through a keyhole or the like generated when melting. In this case, if the optical axes and positional relationships of the opposing laser optical systems match, there is no problem because the transmitted laser beams will be focused on the optical fiber 2.2 by the respective condensing lenses 3.3. However, if there is even a slight deviation in the optical axis, the light may be focused on the side of the optical fiber 2.2 or, although not shown, since the optical fiber is fixed with a metal fitting through an adhesive, the light may be concentrated on the side of the optical fiber 2. If the laser beam is focused, there is a problem that the optical fiber 2.2a may be burned out by the laser beam.

[Objective of the Invention 1 The present invention has been made with attention to the above-mentioned problem, and its purpose is to easily protect the optical fibers of the laser optical system provided on both sides of the workpiece from each other's laser beams. The object of the present invention is to provide a laser processing method that can perform the following steps.

[Summary of the Invention] The present invention involves positioning laser optical systems each having a condenser lens and an optical fiber on both sides of a workpiece, and concentrating laser light from each laser optical system onto a joint of the workpiece. When welding, the optical axes of each laser optical system are not located in a straight line, but are positioned so that they intersect at a predetermined angle, so that the laser beam from one laser optical system is directed to the other. Even if the light enters the condensing lens of the laser optical system, the converging point can be focused at a position that is significantly shifted from the optical fiber of the laser optical system, or it can be made so that it does not enter the condensing lens, and the light can be separated from each other. The optical fiber of the laser optical system can be protected.

[Embodiments of the invention] Hereinafter, the present invention will be explained based on an embodiment shown in the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention. Laser optical systems are provided on both sides of the workpieces 4a and 4b, and each laser optical system emits laser light 1 from an oscillator (not shown) through an optical fiber 2. Each of the laser beams 1 is focused by a condenser lens 3 on the joint surface 4C of the workpieces 4a and 4b, and thereby the workpiece 4
The joint surface 4C of a and 4b absorbs the laser beam and melts. Here, each laser optical system is positioned such that the optical axis 6.6 of the laser beam 1 from the optical fiber 2 to the bonding surface 4C is not located in a straight line but intersects at an angle θ. Therefore, even if the laser beam 1 of one laser optical system passes through a gap in the joint surface 4C or a keyhole generated during melting, the transmitted laser beam 5 does not enter the condenser lens 3 of the other side. Furthermore, even if the laser beams were to be incident, since the optical axes 6 and 6 are shifted from each other by θ, the incident laser beam 5 is focused by the condenser lens 3' at a position that is far more shifted than the optical fiber 2. This also applies to the laser beam of the other laser optical system, so that the optical fiber 2.2 of each laser optical system will not be burned out by the laser beam 6 transmitted by the other laser optical system.

[Effects of the Invention] As explained above, the laser processing method according to the present invention does not cause burnout of the optical fiber, so stable processing can be performed for a long period of time, and work efficiency and device operating rate can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the method of the present invention, and FIGS. 2 and 3 are perspective views showing conventional laser processing methods, respectively. DESCRIPTION OF SYMBOLS 1... Laser light, 2... Optical fiber, 3... Condensing lens, 4a, 4b... Workpiece member, 4c... Joint surface, 5... Transmitted laser light, 6... ··optical axis.

Claims (1)

[Claims] Laser optical systems each having an optical fiber and a condensing lens are installed on both sides of the workpiece, and the laser beam guided by the optical fiber of each laser optical system is focused by the condenser lens to process the workpiece from both sides. A laser processing method, characterized in that each laser optical system is positioned such that the optical axes of its laser beams intersect at a predetermined angle.