JPS5891117A - Heat treating method - Google Patents

Abstract

PURPOSE:To carry out excellent quenching free of thermal strain up to desired depth without reference to the size and shape of a metallic member by irradiating the metallic member where quenching is to be performed with a laser beam repeatedly. CONSTITUTION:A shaft 2 to be quenched is held in a chuck 1 and the shaft 2 is painted in black at a position 3 where quenching is to be performed. This position 3 is irradiated with a laser beam 4 from a large-output carbon dioxide gas laser device which is reduced to an adequate spot through a convergent lens 5, and the chuck 1 is rotated. At this time, the turning speed of the shaft 2 and the power and irradiation time of the laser beam 4 are adjusted to form a locally quenched layer to desired depth.

Description

DETAILED DESCRIPTION OF THE INVENTION 1) Technical Field of the Invention The present invention relates to a heat treatment method suitable for locally consolidating a metal member.

2) Background of the Invention In general, metal members used as movable parts of mechanical devices, such as electric motors, rotate 1! The shaft used for L@ is often heat-treated to obtain the desired function depending on the purpose. For example, in a motor used for an agricultural water pump, a rubber rolling is used to tighten the shaft tube at the bearing part of the shaft to prevent water from entering the motor from the outside. The strength of this shaft is calculated based on the required torque and belt tension, and the material, diameter, etc. are determined, but due to the mechanical structure of the motor, this shaft usually has a stepped portion. Quenching treatment is recommended for the purpose of improving the fatigue strength of this stepped portion or the former rolling abrasion resistance.

3) Prior Art When locally hardening a metal member such as a shaft, conventionally a high frequency induction heater has not been used. According to this method, good local quenching treatment with less thermal strain can be achieved.

4) Problems with the conventional technology However, in the conventional method described above, an induction coil must be prepared according to the size and shape of the metal member to be heat treated, which is expensive, and the induction coil cannot be attached to the metal member. There are 6 problems such as complicated work to set up.

5) Purpose of the Invention The present invention provides the ability to
It is an object of the present invention to provide a heat treatment method capable of performing partial hardening treatment and also capable of performing good hardening treatment without thermal distortion.

6) Structure of the Invention In order to achieve this object, the present invention is characterized in that the hardening process is performed using a laser beam, and at the same time, the hardened area is irradiated with a Rede beam multiple times. do.

7) Examples of the invention Hereinafter, the present invention will be explained with reference to the embodiments shown in the drawings.

In the figure, reference numeral 1 denotes a chuck 1 which is rotated by a motor (not shown) and holds a shaft 2 to be hardened in the chuck 1. A hardened part 3 of the shaft 2 is coated with black obstetrics in advance by spraying, etc., and a radar beam 4 of a carbon dioxide gas high-output radar device is applied to the hardened part 3 through a focusing lens 5 through an appropriate slit. While squeezing and cleaning, rotate the chuck l. As a result, the hardened portion 3 is heated by the Lede beam 4, and the shaft 2 is locally hardened.

By the way, at this time, it is necessary to insert the hardened part 3 of the shaft 2 to the desired depth, but for this purpose, by raising the rotor (7'cjl) and slowing down the rotational speed of the shaft 20, the hardened part 3 can be heated. If the heat input per unit time is within the range of 1A, the heat balance of the shaft 2 is asymmetrical and thermal distortion occurs. You will have to do so.

Therefore, in this embodiment, by adjusting the rotational speed of the shaft 2, the neuer of the Rede beam 40, and the irradiation time, By adjusting the number and repeatedly heating the hardened portion 3, a hardened layer with a desired depth is formed.

In other words, the irradiation spot diameter of the Radhe beam 4 is d.

Assuming that the circumferential length of the shaft 2 is t, when the circumferential speed of the shaft 2 during radar irradiation is high and the time t required for one rotation is short, the heat conduction from the surface of the quenched portion 30 to the shaft 2R portion is rlj a * It can be approximated to one-dimensional heat conduction of a planar heat source with length t. Therefore, if the thermal diffusion coefficient of the shaft 2 is C, the specific heat is C1, the density is p, the time required for one rotation of the shaft 2 is t, and the heat input density from the loop beam 4 to the shaft 2 is q. The temperature rise Tn after nt seconds within the distance x from the surface due to the heat input during the first rotation is expressed as follows. The temperature TX after me seconds due to the heat input of 11 revolutions can be calculated as follows.

Therefore, for quenching, at 10 rotations per second for 5 seconds, the circumference is 56
1! If the shaft 2 is heated to 900°C and has a width α5 cxs -0.13° and is round, then c = 0.15-/path・°C, p curvature 7.7 tt/cd, 'evening 0. Q 7 c
d/Ki, the required heat input density is -108 watts/
− is calculated. Approximately 2700 radar beams are required for this.
It will be 1F11tt, but considering heat dissipation into the atmosphere and reflection on the hardened surface, it will be adjusted to 4W, which is somewhat larger.

In this way, the rotational speed of the shaft 201, the power and irradiation time of the Redebeam 4! #If the hardening process is performed with sufficient heat, the heat incident on the hardened part 3 every rotation will be:
While instantaneously increasing the surface temperature, the heat transfers to the inside of the shaft 2 by heat conduction, raising the internal temperature.

By repeating this thermal operation, the temperature can be raised with a gentle temperature gradient toward the deeper part of the shaft 2. That is, since the heat input is substantially uniform over time as the shaft 2 rotates, it is possible to suppress the occurrence of thermal distortion due to the Radhe heat input.

Since the heat input per unit area per Radar irradiation is small, it is possible to raise the temperature to the deep part by multiple Radar irradiations without overheating the surface.

Therefore, only the surface layer does not cause an extreme temperature rise, and the heat-balanced Rede hardening is performed on the axis of the shaft 2.
You will be able to go deeper.

8) Modifications of the invention In the above embodiments, the case where the shaft 2 is locally hardened is explained, but the present invention is not limited to this, but can be widely applied to gold J4 members that require local hardening. Needless to say.

9) Effects of the Invention As described above, according to the present invention, the hardening process is performed using a Lede beam, so it is non-contact, easy to control, and easy to reach complicated narrow parts with light. At the same time, it is possible to obtain a heat treatment method that can successfully harden to a desired depth without requiring a step of correcting the hardened edge due to @strain.

[Brief explanation of the drawing]

The figure is an explanatory diagram of a heat treatment method according to an embodiment of the present invention. l...Char, Ri, 2...Shaft, 3...Hardened portion, 4...Lede beam, 5...Focusing lens.

Claims (1)

[Scope of Claims] (1) By repeatedly irradiating the part of the metal member to be hardened with the Radhe beam several times and gradually raising the temperature toward part #, the local part is heated to a desired depth. A heat treatment method characterized by performing hardening. (2. The heat treatment according to claim 1, wherein the irradiation energy density of the Lede beam, the number of dove shots per unit time, and the total number of irradiations are adjusted according to the hardening depth of the metal material. (3) In claim 1, the shaft is held in a rotatable chuck by the front Mi2 gold knitting material member,
The shaft is locally hardened to a desired depth by applying a black paint to the area to be hardened, irradiating it with a Radbeam of a predetermined energy, and rotating the shaft a predetermined number of times at a predetermined speed. heat treatment method.