JPS58136712A - Hardening method - Google Patents

Abstract

PURPOSE:To prevent the infiltration of quenching media into a cover and to prevent the increase in the hardness of the nonhardened areas of hardened parts by covering said nonhardened parts with the cover after heating the hardened parts to prescribed temp. then pressurizing the air in the cover and injecting cooling liquid to the hardened areas. CONSTITUTION:Hardened parts and a lower cover 4 are combined and after both are heated to a hardening temp., both are removed from a heating furnace and are set; thereafter, an upper cover 3 is put thereon. The hardened parts are rotated slowly by using an electric motor 6 and a speed reducer 7, and a gas is introduced through an air introducing pipe 5 to maintain the internal space enclosed with the covers 3, 4 to pressure higher than atmospheric pressure, then quenching media 9 are injected from an injector 1 for quenching media, whereby local hardening is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hardening method, and particularly to a hardening method for preventing hardness from increasing due to penetration of a hardening liquid into unhardened parts.

For parts that are to be locally hardened after heating the whole, as shown in Figs. Then, a quenching liquid (water, oil, etc.) 9 was injected to obtain a locally hardened portion 2. However, in that case, it is very difficult to prevent the quenching liquid from entering the non-hardened portion 2a, and due to the quenching liquid entering, the hardness of the non-hardened portion 2a decreases according to the curve 11 in FIG.
As shown in Fig. 2, it becomes high, causing problems in later processes such as machining.

In order to eliminate the above-mentioned drawbacks, the present invention provides a quenching method that prevents the quenching liquid from entering into the nanobar.

That is, the present invention provides a quenching method characterized in that after heating a quenched part to a predetermined temperature, the non-hardened part of the part is covered with a cover, and the inside of the cover is pressurized to inject a cooling liquid onto the part. It is related to.

FIG. 1 is a front view showing an embodiment of the method of the present invention, and FIG.
The figure is a sectional view taken along the line AA.

In Figures 1 and 2, 1 is a quenching fluid injection device, 2 is a hardened part of the quenched part, 2a is a non-hardened part of the part, 6 is an upper cover, 4 is a lower cover, 5 is an air introduction pipe, 6 is an electric motor, 7
is a speed reducer, 8 is a rotating shaft, and 9 is a quenching fluid (water, oil, etc.).

In Figures 1 and 2, first, the hardened parts and the cover 4
After combining and heating to the quenching temperature, it is taken out from the heating furnace (not shown) and set as shown in this figure, and then the upper cover 6 is covered. After that, the hardened parts are slowly rotated using the electric motor 6 and the speed reducer 7, and gas (air, non-oxidizing gas such as nitrogen, etc.) is introduced from the air introduction pipe 5, and the hardened parts are partially rotated. After maintaining the internal space surrounded by the cover 6 and the lower cover 4 at atmospheric pressure or higher, the quenching fluid injection device 1
A quenching liquid 9 is injected from the hole to perform local quenching.

By the way, if only the upper cover 6 and the lower cover 4 are attached, the quenching liquid 9 will enter through the gap between the quenched parts and the covers 3 and 4, and the quenching liquid 9 will splash on the non-hardened part 2a, causing damage to that part. The hardness increases, which has a significant negative impact on quality and post-process machining. Therefore, in the present invention, by maintaining the pressure in the inner part of the cover 6.4 above atmospheric pressure,
This reliably prevents the quenching fluid 9 from entering through the gap between the quenched parts and the cover 6.4.

Next, the effects of the method of the present invention will be explained by giving specific examples.

A hardened part having the shape shown in FIGS. 1 and 2 and the dimensions shown in FIG. 6(A) is hardened and tempered (
The cross-sectional hardness distribution was measured. The results were as shown in Figure 6 (J3).

In Figure 6) and (B), 10 is the cross-sectional hardness of the hardened part 2, 11 is the cross-sectional hardness from the hardened part 2 to the unhardened part 231 soil, and for reference, li+:'tc: l- ,
/c shows the cross-sectional hardness 12 from the hardened part 2 to the non-hardened part 2a in the case of quenching 1 and tempering (200"C) treatment 1 to 1 in the conventional method.

As is clear from Figure (B), when quenching and tempering are performed without applying pressure to the inner part of the cover as in the conventional method, only the hardened part 2 is hardened, as shown in cross-sectional hardness distribution 10.12. Without,
Although the hardness of the non-hardened portion 2a also increases, by introducing air from the air introduction pipe 5 and pressurizing the inner part of the cover as in the method of the present invention, intrusion of the quenching liquid can be prevented 1)-1, and as a result, As shown in the cross-sectional hardness distribution 11, the hardness of the non-hardened portion 2a can be lowered.

As explained above, in the method of the present invention, by increasing the pressure inside the horn bar higher than atmospheric pressure, it is possible to prevent the quenching liquid from entering the cover and prevent the hardness of the unhardened portion from increasing. I can do it.

4 and 5 are diagrams showing other embodiments of the method of the present invention, and FIG. 4 is an example of a case where the outer surface of a traveling guide roller of a construction machine is subjected to surface hardening treatment, and FIG. The figure is an example of a case where bottles and shafts are locally hardened. The symbols in FIG. 4.5 have the same meanings as those in FIGS. 1 to 3.

[Brief explanation of the drawing]

FIG. 1 is a front view for explaining one embodiment of the method of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, FIG. 3 (A),
σ3) shows the dimensions and shape of a part to be hardened and tempered [Fig. 6 (A)] and the cross-sectional hardness distribution of the part after the treatment [Fig. 6 0] to explain the effects of the method of the present invention. Figure 4, illustrating
FIG. 5 is a diagram showing another embodiment of the method of the present invention. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] A quenching method comprising heating a quenched part to a predetermined temperature, then covering the non-hardened part of the part with a cover, pressurizing the inside of the cover, and injecting a cooling liquid onto the part.