JPH0557329B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method and apparatus for heat treating steel materials using a laser. [Prior Art] In conventional laser heat treatment using a polygon mirror, a workpiece is processed by scanning a beam using a single polygon mirror. Furthermore, when surface treatment is performed, the workpiece is simultaneously scanned by the beam and moved perpendicularly to the scanning direction. [Problems to be Solved by the Invention] In conventional laser processing using a polygon mirror, heat treatment was performed by scanning one beam. In this case, the workpiece was subjected to rapid heating and rapid cooling, which are characteristics of laser heat treatment. For this reason, it is difficult to set the surface temperature and maintain the set temperature by uniformly heating the steel material. In addition, when surface treatment is performed on a workpiece by scanning with one beam, for example, in case of hardening treatment, the next scan beam passes close to the part that has already been heat treated, as shown in Figure 2. and heat treated. As a result, the surrounding areas, which have already been heat-treated to a high degree of hardness through rapid heating and cooling, are once again affected by heat and the hardness value decreases, resulting in a difference in hardness from areas that are not affected by heat, resulting in uneven processing. It was hot. As a laser beam processing method using a polygon mirror, there is a scratch processing device described in JP-A-62-13389, but this is designed to irradiate several locations at the same time in order to achieve uniform and high-speed processing. However, the above drawbacks cannot be prevented. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an apparatus and method that can set a processing temperature and maintain the set temperature by uniform heating, and that can perform heat treatment without unevenness. purpose. [Means for Solving the Problems] The gist of the present invention is to provide an optical system for dividing a laser beam into a plurality of beams in a laser processing apparatus for steel materials, which includes a laser body and a polygon mirror for reflecting and scanning the laser beam. a plurality of bending mirrors that respectively adjust and reflect the directions of the plurality of beams split from the branching optical system; A laser heat treatment apparatus characterized by comprising a polygon mirror that rotates coaxially with angles shifted from each other, and a movement mechanism that moves the workpiece in a direction perpendicular to the scan direction of a laser beam; In a steel processing method that involves scanning a beam over the steel surface, the laser beam is divided into multiple beams, the reflection angle of each beam is adjusted using a bending mirror, and the beam is scanned onto the mirror surface of each stage of a multi-stage polygon mirror. A laser heat treatment method characterized by reflecting and irradiating a steel surface with multiple beams, and a steel processing method in which the laser beam is scanned over the steel surface using a polygon mirror. A laser that divides the beam into two parts, adjusts the reflection angle of each beam with a bending mirror, reflects it on each stage mirror surface of a multi-stage polygon mirror, and distributes and irradiates multiple beams onto the same scan on the steel surface. In the heat treatment method and the steel processing method, which uses a polygon mirror to scan a laser beam over the surface of the steel material, the laser beam is divided into multiple beams, and the reflection angle of each beam is adjusted using a bending mirror. The laser heat treatment method is characterized in that the laser heat treatment method is characterized in that the laser beams are reflected on the mirror surfaces of each stage of a multi-stage polygon mirror and are distributed and irradiated with a plurality of beams at an angle with respect to the scan direction. [Function] The present invention will be explained in detail below. FIG. 1 is a schematic diagram showing the configuration of the apparatus of the present invention. As shown in FIG. 1, the present invention includes a branching optical system 2 that splits a laser beam 3 emitted from a laser main body 1 into a plurality of laser beams, and a plurality of bending mirrors 14 that adjust the method of each laser beam. The angle adjuster 4, a lens 5 that focuses a plurality of laser beams, and a plurality of coaxial polygons that reflect the laser beams from the focusing lens 5 and irradiate the surface of the workpiece 9 with the laser beams. A mirror 6, a rotation drive mechanism that rotates the plurality of bending mirrors, and a movement mechanism that moves the workpiece in an angular direction relative to the direction in which the laser beam is scanned by rotation of the polygon mirror. be done. The rotational drive mechanism for the polygon mirror 6 is a motor 7 equipped with a controller 8 capable of controlling the rotation speed, and the movement mechanism for the workpiece is an X-Y-Z table 10 with a controller 11, for example. Can be mentioned. Note that 12 indicates the scan delay, and 13 indicates the scan path. In this device, a laser beam 3 emitted from a laser main body 1 is divided into a plurality of laser beams using a branching optical system 2, and the angle of each laser beam is incident on a target polygon mirror and reflected.
The bending mirror 14 is adjusted by the angle adjuster 4 so that the target part of the workpiece can be irradiated, and the beam is guided to a plurality of polygon mirrors 6 through the condenser lens 5. Here, the angle around the axial direction of the polygon mirror has a difference (lag angle) θ as shown in Figure 7.
Add. As a result, the reflected light from the polygon mirror becomes a plurality of laser beams that follow the same scan path while maintaining a certain delay and is irradiated onto the workpiece. As a result, the beam on the workpiece becomes h in order from e to h in FIG. 8, and the temperature on the workpiece becomes a to d. At this time, the number of beams,
By changing the power and delay of each beam, the workpiece is heated in sequence, and by controlling the set angle and rotation speed of the polygon mirror, it is possible to maintain the required temperature range for the required time. can. Therefore, there is no rapid heating and rapid cooling unlike when processing with only one laser beam, and the cooling rate after heat treatment of the steel surface can be arbitrarily controlled. Note that the workpiece is moved simultaneously with the scanning of the beam in a direction perpendicular to the scanning direction. In addition, using this device, each beam is distributed to the path where the leading beam is scanning and the area where the leading beam has a thermal effect, with an angle in the scanning direction due to afterheating, and the leading beam is Insulates areas that are affected by heat. 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 match the temperature of the workpiece to the temperature conditions for processing, and it is also possible to eliminate processing unevenness due to reheating. [Examples] Example 1 A heat-treated strengthened steel plate having a thickness of 1.4 mm and having the components shown in Table 1 was heat-treated. At this time, three polygon mirrors were used. The polygon mirror used was a hexagonal column made of steel, 80 mmφ, and each piece had a mirror surface of 20 mm. The rotation speed of the polygon mirror is 0.5 rpm,
The angular difference θ was set to 9.2 degrees. The laser used was a 2kW carbon dioxide laser, and the beam was split into three by a beam splitter. The power of each was set to 1.5kW, 0.25kW, and 0.25kW from the beginning. A condensing lens with a focal length of 1000 mm was used. The scan length is 300mm, the width is 2mm, and the speed is 30mm.
mm/sec, and the delay of each beam was 100 mm.
At this time, the temperature at one point of the workpiece was a curve connecting the points Δ in FIG. 5, and the Vickers hardness was as shown in FIG. 6. As a result, it can be seen that the method according to the present invention is superior to the conventional method.

[Table] Example 2 A 3.2 mm thick carbon steel S45C was subjected to surface treatment using three polygon mirrors and a 2 kW carbon dioxide laser. Polygon mirror is made of copper, hexagonal column, 80mm
A piece with a mirror surface of 20 mm in diameter was used. The rotation speed of the polygon mirror is 0.5 rpm, and the angle difference is 4.2
It was a degree. The beam splitter divides the beam into three parts, each with a power of 1kW, 0.5kW,
It was set to 0.5kW. The lens used had a focal length of 1000mm. The scan length is 300mm, the width is 2mm,
Speed is 30mm/sec, each beam delay is 350mm
(one scan path and 50mm delay), and 12mm/sec in the direction perpendicular to the scan direction. At this time, the distribution of the Vickers hardness in the direction perpendicular to the scan was as shown 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 one polygon mirror shown 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 are met.
It became possible to maintain the workpiece for the required time. Another problem was the heat treatment system using one polygon mirror. It has also become possible to improve processing unevenness in the direction perpendicular to the scan direction.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the configuration of the present invention, FIG. 2 is a conceptual diagram of scan, and FIG. 3 is a graph of the hardness value of a workpiece after quenching by a heat treatment apparatus using a conventional polygon mirror. Fig. 4 is a graph of the hardness value of the workpiece after quenching by the apparatus of the present invention;
The figure shows the temperature profile at a fixed point on the workpiece, Figure 6 is a graph of the hardness after processing, Figure 7 is a conceptual diagram of the polygon mirror settings, and Figure 8 shows the beam position and temperature distribution on the workpiece. It is a conceptual diagram. 1... Laser main body, 2... Branching optical system, 3...
Laser beam, 4... Angle adjuster, 5... Lens, 6... Polygon mirror, 7... Motor, 8...
...Controller, 9...Workpiece, 10...X-
Y-Z table, 11...controller, 12...
...Sukyan's delay, 13...Sukyan's route, 1
4...Bending mirror.

Claims (1)

[Scope of Claims] 1. A laser processing device for steel materials comprising a laser main body and a polygon mirror for reflecting and scanning the laser beam, including an optical system that splits the laser beam into a plurality of beams, and an optical system that splits the laser beam from the branching optical system. multiple bending mirrors that adjust and reflect the directions of the multiple laser beams, a lens that focuses the divided laser beams, and a stack of stages corresponding to the number of divided and reflected beams. a polygon mirror that rotates coaxially, and the angles of the reflective surfaces of the polygon mirrors are shifted from each other;
A laser heat treatment apparatus using a polygon mirror, characterized by comprising a moving mechanism for moving the workpiece in a direction perpendicular to the scan direction of a laser beam. 2. In a steel processing method that uses a polygon mirror to scan a laser beam onto the steel surface, the laser beam is divided into multiple beams, the reflection angle of each beam is adjusted using a bending mirror, and a multi-stage polygon mirror is created. It is reflected on the mirror surface of each stage of
A laser heat treatment method using a polygon mirror, which is characterized by irradiating the steel surface with multiple beams. 3 In a steel processing method that uses a polygon mirror to scan a laser beam onto the steel surface, the laser beam is divided into multiple beams, the reflection angle of each beam is adjusted using a bending mirror, and a multi-stage polygon mirror is created. It is reflected on the mirror surface of each stage of
A laser heat treatment method using a polygon mirror, which is characterized by distributing and irradiating multiple beams onto the same scan on the surface of a steel material. 4 In a steel processing method that uses a polygon mirror to scan a laser beam over the steel surface, the laser beam is divided into multiple beams, the reflection angle of each beam is adjusted using a bending mirror, and a multi-stage polygon mirror is created. It is reflected on the mirror surface of each stage of
A laser heat treatment method using a polygon mirror, which is characterized by irradiating multiple beams at different angles to the scan direction.