JPH03188212A - Laser beam heat treatment method - Google Patents

Abstract

PURPOSE:To execute uniform processing to steel plate surface by dividing laser beam into plural beams, guiding them to optical fibers and radiating plural beams while inclinedly lining up on the steel plate surface. CONSTITUTION:The laser beam 3 projected from a laser body 1 is divided into plural laser beams 3 through branching optical system 2 having semi-transparent mirror 12 and full transparent mirror 13 and each beam is guided to condensing optical system 5 through each optical fiber 4. This condensing optical system 5 is driven while holding the fixed positions (x and y) to the preceded beam and the heat treatment is executed to the steel material 8 while adjusting power density of the beam 3. Then, the steel material 8 is moved in the direction at the right angle to the scanning direction at the same time of scanning the beam 3. By this method, irregular treatment caused by rapid heating, rapid cooling and reheating to the steel material 8 is eliminated, and the uniform processing can be executed to the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of heat treating steel materials using a laser.

[Prior Art] In conventional laser heat treatment, a workpiece is processed by scanning a beam using two optical fibers.

Furthermore, when surface processing is performed, the workpiece is moved perpendicularly to the scanning direction at the same time as the beam is scanned.

[Problems to be solved by the invention] In conventional laser processing using optical fibers,
Heat treatment was performed by scanning a single beam.

In this case, the workpiece was rapidly heated and rapidly cooled, which is a characteristic of laser heat treatment. For this reason, it is difficult to set the surface temperature and maintain the set temperature by heating the steel material.

In addition, when surface-treating a workpiece by scanning with one beam, for example, taking hardening treatment, as shown in Figure 2, the next scan beam passes close to the part that has already been heat-treated. and heat treated. For this reason, if the surrounding areas that have already been heat-treated and become highly hard due to rapid heating and cooling are once again affected by heat, the hardness value will decrease, creating a difference in hardness from areas that are not affected by heat, resulting in uneven processing. There were drawbacks.

As a method of performing heat treatment by scanning multiple laser beams, there is a scratch processing device described in Japanese Patent Application Laid-open No. 13389/1989, but this method uses divided irradiation on several locations at the same time in order to process uniformly and at high speed. However, the above disadvantages cannot be prevented.

The present invention has been made in view of the above circumstances, and it is possible to set the processing temperature and maintain the set temperature by heating in a manner similar to -.
Another object of the present invention is to provide a method that allows heat treatment to be performed evenly.

[Means for Solving the Problems] The gist of the present invention to achieve this object is to provide a surface treatment method for a steel material in which a laser beam is scanned over the surface of the steel material using an optical fiber. A laser heat treatment method characterized by dividing the laser beam into two parts, guiding each laser beam to an optical fiber, and then irradiating a plurality of beams in parallel on the same scan on the surface of a steel material when focusing; A laser heat treatment method characterized by dividing the beam into a plurality of beams, guiding each beam to an optical fiber, and then irradiating the plurality of beams diagonally after the preceding beam when condensing the beam. A laser heat treatment method characterized by using a device to guide each beam to an optical fiber and then irradiating a plurality of beams in parallel on the same scan of a steel surface when condensing; This laser heat treatment method is characterized in that, after guiding each beam to an optical fiber using a device, when converging the beams, a plurality of beams are arranged and irradiated diagonally after the preceding beam.

[Action Co. The present invention will be explained in detail below.

FIG. 1-1 is a schematic diagram showing an example of the configuration of an apparatus for implementing the present invention.

As shown in FIG. 1, the present invention guides a laser beam 3 emitted from a laser main body 1 to an optical fiber 4 through a branching optical system 2 having a semi-transparent mirror 12 for splitting it into a plurality of laser beams. By changing the transmittance of these mirrors, the power of each laser beam can be varied. Thereafter, processing is performed while adjusting the power density of the beam by driving the condensing optical system 5 at the other end of the optical fiber.

An example of this drive device is independent for each condensing optical system, and has two boobies and a belt around the outer circumference.
It is driven by rotating the boot. As shown in Fig. 6, the driving method is to drive the focusing optical system 5 while maintaining a certain position (X and Y in Fig. 6) with respect to the preceding beam, and to move the scanning path at a certain interval. The multiple laser beams are adjusted so that they follow each other.

As a result, as the scan progresses, the position of the beam on the workpiece changes as shown in FIG. 7(e) to (h), and the temperature on the workpiece changes accordingly. a)～(
As shown in d), the path that the leading beam is scanning and the area where the leading beam has a thermal influence are arranged diagonally backwards for afterheating, and the area where the leading beam has a thermal influence is kept warm. . After that, the processing is finished as needed starting from the part where the thermal influence of the leading beam has disappeared. As a result, it is possible to maintain the temperature of the workpiece at the required temperature condition for the required time, and there is no rapid heating or cooling required when processing only with a laser beam, and Processing unevenness caused by heating can also be eliminated, making it possible to process the surface uniformly.

Note that the workpiece is moved in a direction perpendicular to the scanning direction simultaneously with the scanning of the beam.

Furthermore, in the above laser processing apparatus, instead of using the beam splitting optical system, it is also possible to perform similar heat treatment using a plurality of laser devices without using the splitting optical system as shown in FIGS. 1-2.

[Example 1 (Example 1) A heat-treated strengthened steel plate having a thickness of 1.4 mm whose components are shown in Table 1 was heat-treated. The laser used was a 400W YAG laser, and the laser beam was divided into three beams. The respective powers were 280W, 110W, and 110W from the beginning. A condenser lens with a focal length of 50 m+n was used.

Scan length is 300mm, width is 2mm, speed is 10
mm/sec, the delay of each beam is X=
10 mm, Y = Omm. At this time, the temperature at a point of the workpiece was a curve connecting the Δ points in FIG. 3, and the Vickers hardness was as shown in FIG. 4. As a result, it can be seen that the method according to the present invention is superior to the conventional method.

(Example 2) Heat treatment was performed on carbon steel S45 having a thickness of 3.2 mm. The lasers used were three 400W YAG lasers, each with a power of 4 (IOW, 400W, 400W) from the beginning. A condenser lens with a focal length of 50+nm was used. The scan length was 300mm. , width is 2 mm,
The speed is IOo+m/sec.

The delay of each beam is X = 50 mm in Fig. 6,
Y = 2m+n (scan path - main course plus 10mm delay). At this time, the distribution of Vickers hardness in the direction perpendicular to the scan became as shown by the curve connecting the X points in FIG. As a result, it can be seen that the processing unevenness has been improved compared to the hardness distribution of the conventional processing using a single scanning beam, which is shown by the curve connecting the 0 points in FIG.

[Effects of the Invention] As shown in the examples, according to the present invention, in heat input processing using a laser, the necessary temperature conditions, necessary time,
This makes it possible to maintain the workpiece. It has also become possible to improve processing unevenness in the direction perpendicular to the scan direction, which was a problem with heat treatment systems using a single scanning beam.

[Brief Description of the Drawings] Figures 1-1 and 1-2 are schematic diagrams showing an example of the configuration of an apparatus for carrying out the present invention, and Figure 2 is a conceptual diagram of scanning.
Figure 3 shows the temperature profile at a fixed point on the workpiece.
Figure 4 is a graph comparing each hardness, Figure 5 is a graph of the hardness value of the workpiece after quenching, Figure 6 is a conceptual diagram of the scan beam arrangement, and Figure 7 is a graph of the beam on the workpiece. It is a conceptual diagram of position and temperature distribution. DESCRIPTION OF SYMBOLS 1... Laser main body, 2... Branching optical system, 3... Laser beam, 4... Optical fiber 5... Condensing optical system, 6... Drive device, 7... Scanning path , 8・
・・Workpiece (steel material), 9-X-Y-Z table, 1
0--table controller, 11...scan delay, 12...semi-transmissive mirror, 13...total-reflective mirror

Claims (1)

[Claims] 1. In a method for surface treatment of a steel material, which is performed while scanning a laser beam on the surface of the steel material using an optical fiber,
A laser heat treatment method characterized by dividing a laser beam into multiple beams, guiding each laser beam to an optical fiber, condensing the beam, and irradiating the multiple beams in parallel on the same scan on the steel surface. 2. In a method of surface treatment of steel materials, which is performed by scanning a laser beam onto the surface of steel materials using an optical fiber,
A laser heat treatment method characterized by dividing a laser beam into a plurality of beams, guiding each laser beam to an optical fiber, condensing the light, and irradiating the plurality of beams in a line diagonally behind each preceding beam. 3. In a method of surface treatment of steel materials, which is performed by scanning a laser beam onto the surface of steel materials using an optical fiber,
A laser heat treatment method that uses a plurality of laser devices to guide each laser beam to an optical fiber, then converge the light, and irradiate the steel surface with the plurality of beams in a lined manner on the same scan. 4. In a method for surface treatment of steel materials, which is performed by scanning a laser beam onto the surface of steel materials using an optical fiber,
A laser heat treatment method characterized by using a plurality of laser devices to guide each laser beam to an optical fiber, converging the light, and irradiating the plurality of beams in a line diagonally behind each preceding beam.