JPS6272432A - Deflection removing method for heat treating item - Google Patents

Abstract

PURPOSE:To increase the productivity and the quality of a product by irradiat ing laser beam at least on one part of heat treating item and by removing the thermal deflection generated in heat treatment. CONSTITUTION:The laser beam generating device 2 with the prescribed output and having an output variable capacity is arranged for the heat treating item 1 of a crank shaft,etc. A laser beam 3 is first irradiated at the adequate feeding speed and in adequate width on the shoulder part 1a at both sides of the journal J4 which is located at the center part of a crank shaft 1. Then, the laser beam 3 is irradiated similarly on the shoulder part 1a of the adjacent journals J8, J5 as well. In succession, the irradiation is performed on the one side of the journals J2, J6, as well. In this way, the thermal deflection can be removed in short time and the heat treatment grinding, etc. are disused. Consequently the product quality as well as the productivity are increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for removing thermal strain generated in a heat-treated crankshaft or the like and removing strain from a heat-treated product using laser light.

Conventional technology Crankshafts used in conventional engines are subjected to heat treatment such as fillet quenching to improve fatigue resistance, but because of the large thermal strain that occurs, conventionally various countermeasures are taken at the heat treatment stage. This aims to reduce the generated distortion.

In addition, for items with large distortions after heat treatment, we perform low-temperature tempering using a press, etc., and for crankshafts that require high quality, we take the distortion into consideration in advance and reduce the amount of polishing. A method is adopted in which the material is provided, heat treated, and then the polishing allowance is polished to finish it to a predetermined size.

Problems that the invention attempts to solve However, the former method of removing distortion using a machine such as a press has the disadvantage that it requires a large number of man-hours to remove distortion, resulting in poor productivity.

Further, the latter method in which a polishing allowance is provided in advance has problems such as poor material yield and a large number of man-hours required for polishing after heat treatment, resulting in poor productivity similar to the aforementioned method.

This invention was made for the purpose of improving the above-mentioned problems.

Means and effects for solving the problem: Irradiating at least a part of the heat-treated product with laser light
5. A heat treatment strain removal method that can efficiently remove thermal strain generated during heat treatment in a short time.

EXAMPLE An example of the method of this invention will be described in detail with reference to the drawings.
In the figure, 1 is a fillet-hardened crankshaft for a 6-cylinder engine, and the diameter of the 6 bottles Px NPa is 5.
4φ, the diameter of the seven journals J1 to J is 85φ, and the total length is 97411I11.

Journal Jx ”” Each pin P centered on Jt, ~
The arrangement of P6 was as shown in FIG. 2, and the following distortion occurred with respect to the center of the journals J1 to J7 after heat treatment.

Next, to explain the method for removing the distortion, a laser generator 2 with an output of 5 kW and a beam width of 2 m is used to remove the distortion. As shown in FIG. 2, the laser beam 3 was irradiated for 6 seconds at a feed rate of vo, s cm/sec. Furthermore, the third
The figure shows the irradiated area, and FIG. 4 shows the laser irradiated area of the shoulder portion 1a. Also, the irradiation range is 2 inches wide and about 30 inches long.
■It is a dove.

When the strain of the journals J1 to J7 after the laser irradiation was measured, the measurement results shown in column 2 of Table 1 below were obtained, confirming the effect of strain removal by the laser irradiation.

Next, the shoulder portion 1a located on the right side of journal J3 and the left side of journal J6 was irradiated in the same manner (see Figure 5), and then the strain of each journal J1 to J"r was measured. Table 1 The results shown in column (■) were obtained.

Furthermore, laser irradiation is applied to journal J2 as shown in Figure 6.
When the right side of the journal J6 and the left shoulder portion 1aK of the journal J6 were also measured, the measurement results as shown in column (■) of Table 1 were obtained.

As a result, we were able to confirm that the greater the number of laser irradiated locations, the greater the distortion removal effect.

(m) Note that the output of the laser generator 2 can be varied in the range of 0.5 to 5 KW depending on the size of the crankshaft, etc., and the laser beam size can also be varied in the range of 2 to 10 φ.

Further, in the above embodiment, the number of laser irradiation points was set to six at most, but as shown in FIG. 7, the number of laser irradiation points may be eight or more, and it goes without saying that the present invention can also be applied to strain relief of heat-treated products other than one crankshaft.

Effects of the Invention As described in detail above, this invention removes thermal strain caused by heat treatment by laser irradiation, so it is possible to use a conventional method of removing strain using a machine such as a press. Compared to the method of setting a polishing allowance in advance and performing heat treatment, and then polishing the polishing allowance after heat treatment, distortion can be removed in a shorter time and with fewer man-hours, so it is possible to achieve the same productivity and reduce the number of heat-treated products. This will also improve the quality of the products.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1(0) is a front view of the crankshaft, FIG. 1(0) is a side view of the crankshaft, FIG. The enlarged views of the irradiated area and FIGS. 4 to 7 are explanatory diagrams showing the laser irradiated area.

Claims (1)

[Claims] A method for removing distortion from a heat-treated product, comprising irradiating at least a portion of the heat-treated product with a laser beam to remove thermal distortion generated during heat treatment.