JPH01298112A - Laser beam heat treatment method - Google Patents

Abstract

PURPOSE:To suitably control heating temp. on the rugged surface by forming heat concentrated part on the quenching work surface projected more than the other part at the time of quenching the metal surface having the rugged part by heating with laser beam irradiation and controlling output of the laser beam under heating condition of this projecting part. CONSTITUTION:A metallic block 12 is cut with the laser beam and at the time of heating and quenching the block forming drag line 13 having peculiar rugged shape on the cut face 14 at cutting further with the laser beam irradiation, the heat concentrated part 15 on a part of the cut face 14 projecting more than the other part is previously provided. The laser beam is condensed with a beam condensing part 11 and at the time of heating and quenching by irradiating on the rugged surface of the metallic block 12, heating condition at the projected heat concentrated part 15 is observed, and at the time of starting melting of the heat concentrated part 15, by restraining the output of the radiated laser beam, the cut face 14 is heated to the quenching temp. without melting to the other part thereof, and after executing suitable quenching, the projecting heat concentrated part 15 is removed with machining.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a laser heat treatment method for applying heat treatment to a processed surface of a workpiece by irradiating it with laser light.

(Prior art) For example, laser light from gas laser processing equipment has strong directivity and high energy density, and is therefore widely used for cutting or hardening of metal blocks as workpieces. . Moreover, due to the characteristics of the laser beam mentioned above, the metal block is locally heated by the high energy of the laser beam, so the residual thermal strain after laser processing is extremely small. Machining for removal can be minimized.

As an example of such a laser heat treatment method, as shown in FIG. 4, a metal block 1 is cut with a laser beam,
There is a method of hardening the cut surface 2 by irradiating the cut surface 2 with a laser beam focused by a focusing section 3 of a gas laser processing device.

(Problem to be Solved by the Invention) By the way, in the laser heat treatment method as described above, the cut surface 2 has an uneven drag line (surface roughness of RIIaX of several tens to several hundreds of μm) peculiar to cutting by laser light.
Therefore, when the laser beam is irradiated over the entire cut surface, the irradiation energy is concentrated on the convex part of the minute unevenness formed by the drag line, and as a result, the convex part is placed ahead of the concave part. As a result, the cut surface cannot be hardened sufficiently.

On the other hand, even if the surface to be processed has an uneven shape, if the uneven shape is constant, it is possible to identify the position of the convex part that starts to melt. By suppressing the light output, the temperature of the processed surface can be controlled. On the other hand, in a cut surface with a drag line, the uneven shape of the drag line is not uniform from cut surface to cut surface, so even if the convex part of the uneven shape starts to melt first, the melting start point is As a result, it was difficult to control the temperature of the processed surface.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a laser heat treatment method that can appropriately control the temperature of the processed surface of a workpiece even if the processed surface has an uneven shape.

[Structure of the Invention] (Means for Solving Problems) The present invention provides a laser heat treatment method for heat-treating a surface of a workpiece by irradiating a laser beam with a part of the surface to be processed. A heat concentrating part is formed in advance to protrude from the part, and the output of the laser beam is controlled based on the heating state of the heat concentrating part.

(Function) When a laser beam is irradiated onto the surface to be processed, the overall temperature of the surface increases. At this time, the heat concentrated area formed on the workpiece surface protrudes from other areas, so the energy from the laser beam is concentrated on this heat concentrated area, and this heat concentrated area is melted first. .

Therefore, for example, by suppressing the output of the laser beam when the heat-concentrating part starts to melt, the temperature of the other parts can be controlled to be below the melting temperature.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

First, in FIG. 2, the gas laser device includes a laser output section (not shown) that outputs a laser beam, a condensing section 11 that condenses the laser beam, a moving table that moves two-dimensionally, and a control that drives these. (none of which are shown), the laser beam output from the laser output section is focused by a condensing section 11 and irradiated to the processing point on the movable table in a condensed state. It has become.

Now, a method of processing A on a metal block 12, which is a workpiece that can be hardened, such as iron or alloy, using the gas laser device having the above configuration will be explained with reference to the process diagram shown in FIG. First, in the cutting process, the metal block 12 is fixed on a moving table (not shown) in a positioned state, and the cutting line 13 of the metal block 12 is aligned with a processing point. Then, when the moving table is moved so that the cutting line 13 of the metal block 12 moves along the processing point while the laser output section is driven at high power density, the metal block 12 is moved along the cutting line 13 by the laser beam.
It is cut along 3. Cut surface 1 by such processing
4, a drag line having an uneven shape is formed by cutting with a laser beam.

Now, as described above, the metal block 12 is cut along the cutting line 13.
When cutting along the metal block 2, by controlling the movement of the moving table, a heat concentration area 15 forming a protrusion is formed on the cut surface 14 of the metal block 2 as shown in FIG. That is, the heat concentration portion 15 is formed to cross the cut surface 4 having a drag line, and its apex position protrudes from the other cut surface 14.

Next, a hardening process for hardening the cut surface 14, which is the processed surface of the metal block 12 cut by the laser beam as described above, will be explained. That is, the metal block 12 is fixed on a moving table, and the processing point is aligned with the cut surface 14 of the metal block 12, as shown in FIG.

Then, when the laser output section is driven at a power density lower than that during the cutting process, the laser beam is irradiated onto the cut surface 14 of the metal block 12, and when the movable table is moved in the irradiated state, the temperature of the entire cut surface 14 increases. rises. Here, if the surface to be processed to which the laser beam is irradiated has an uneven shape, the energy of the laser beam is most concentrated on the convex portions of the uneven shape and the temperature thereof becomes high. In the case of this embodiment in which a drag line with an uneven shape is formed, the temperature rise in the convex portion of the drag line is more significant than in the concave portion, and therefore, the convex portion melts earlier than the concave portion. It becomes like this. However, in this embodiment, since the heat concentration part 15 is formed on the cut surface 14 of the metal block 12 and is more protruding than the convex part of the drag line,
The temperature of the heat concentration portion 15 rises prior to the temperature rise of the drag line. Therefore, by monitoring the heat concentration part 15 and when it starts to melt, by suppressing the output of the laser beam, it is possible to prevent other parts of the cut Ir1i 14 from melting. After the hardening with the laser beam is completed, the heat concentration portion 15 is removed by machining, thereby completing the hardening process.

In short, according to the above structure, when the cut surface 14 is hardened, the heat concentration part 1 formed on the cut surface 14 is
By monitoring the heating state of step 5, it is possible to prevent other parts of the cut surface 14 from melting, so when hardening an uneven work surface such as a drag line, Unlike conventional methods in which the convex portion may melt, the temperature of the cut surface 14 can be maintained below the melting temperature even if the surface of the cut surface 14 has an uneven shape like a drag line. can.

In the above embodiment, when the heat concentrating part 14 starts to melt, the output of the laser beam is suppressed. As shown in FIG. 3, the output of the laser beam may be feedback-controlled based on the detection result. In this case, since the position of the heat concentration part is limited, the detection point of the melting detection sensor can be easily aligned with the heat concentration part. Furthermore, since the heat concentration portion serves as an index of the temperature state of the cut surface, the temperature of the cut surface can be controlled by detecting the temperature of the heat concentration portion.

In addition, the present invention is not limited to what is described above and shown in the drawings. For example, the heat concentration portion may be formed intermittently, and the heat concentration portion may be formed not only by laser light but also by machining. Various modifications can be made without departing from the spirit of the invention, such as the heat concentration portion may be formed integrally with the cut surface.

[Effects of the Invention] As is clear from the above description, the present invention involves forming in advance a heat concentration area that is more prominent than other areas on a part of the processed surface of a workpiece, and then heating the heat concentration area. Since the output of the laser beam is controlled based on the state, by monitoring the heating state of the heat concentration area, the temperature of the workpiece surface can be appropriately controlled even if the workpiece surface has an uneven shape. It has excellent effects.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, FIG. 1 is an overall process diagram, FIG. 2 is a perspective view showing an example of the hardening process using laser light, and FIG. 3 is a diagram of the present invention. FIG. 2 is a diagram corresponding to FIG. 1 showing another embodiment of the invention. Moreover, FIG. 4 is a diagram corresponding to FIG. 2 showing a conventional example. In the figure, 12 is a metal block (workpiece), 14 is a cut surface (
15 is a heat concentration area. Figure 1 jp+2 Figure 3

Claims (1)

[Claims] 1. A laser heat treatment method that heat-treats the processed surface of a workpiece by irradiating laser light, in which a heat concentration part is formed in advance on a part of the processed surface that is more protruding than other parts, and A laser heat treatment method characterized by controlling the output of laser light based on the heating state of a heat concentration part.