JPS6315970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat treatment apparatus for hardening the peaks of tooth profiles of gears, sprockets, racks, etc., one tooth at a time, using induction heating means, and particularly for hardening during rapid cooling hardening. This invention relates to improvements in cooling devices.

Conventionally, when hardening the peaks of the tooth profile, Fig. 1a
As shown in and b, the inner surface of the rectangular loop-shaped tubular conductor 1' constituting the induction heating coil C' is
A high-frequency current is applied to the conductor 1' through the lead portion 10 by turning on a high-frequency power source (not shown), extending over the abdomen of the tooth profile to be heat-treated and leaving a predetermined gap therebetween. The surface layer of the top and abdomen of the tooth profile is heated by the magnetic field lines generated from A cooling fluid is injected from the fluid injection pipe 5' to the top part to rapidly cool and harden the heated surface, thereby obtaining a hardened layer having a pattern as shown by diagonal lines in FIG. 1b. Note that the conductor 1' self-heats when high-frequency current is applied, so in order to suppress this, the cooling fluid supply pipe 2a and the discharge pipe 2
b allows the cooling fluid to constantly flow through the hollow portion of the conductor 1'.

However, in this method, during hardening, the cooling fluid is injected toward the tooth top part _GT from the injection hole 51 of the hardening injection pipe 5' disposed above the tooth top part _GT . After directly hitting the top surface G _T of the tooth, it flows to the flank of the tooth. Therefore, the tooth top surface and the vicinity of the ridge line G _E , which is the boundary between the tooth top surface and the tooth flank, are effectively rapidly cooled, but the tooth flank is cooled by the fluid that has risen in temperature during the cooling process of the above-mentioned portion. Therefore, the cooling effect is weaker than that of the tooth top G _T and ridge line G _E , and the cooling effect decreases rapidly from the upper G _SU to the lower G _SD of the tooth flank, resulting in slow hardening. As a result, it is not possible to obtain a hardened layer of uniform hardness and depth over the entire crest, which is particularly desired for tooth profiles. In order to avoid this, it is possible to increase the amount of cooling fluid jetted from the hardening fluid jet pipe 5' to improve the hardening hardness of the tooth flank, especially the lower part, but this would require the tooth top G _T and ridge line G _E This will cause hardness, especially at the ridgeline, and damage during use.

After heating the peak of the tooth profile to a predetermined temperature and removing the induction heating coil C' from the tooth profile, a cooling device having injection holes that can directly cool the tooth top G _T and the tooth flank G _S is placed. It is thought that the above-mentioned defects can be avoided by cooling, but except in special cases, the thickness of the hardened layer required for surface hardening of the tooth profile is about 1 to 3 mm, so the induction heating coil is removed. While the cooling device is attached, the heat from the surface layer diffuses toward the core by thermal conduction, resulting in poor hardening. In order to avoid this, if the surface layer is heated above a predetermined temperature, the hardening depth will become thicker than necessary.

The present invention has been made in order to solve the above-mentioned problems that exist in conventional tooth profile heat treatment.

The present invention will be explained according to the embodiment shown in FIG. C is an induction heating coil, and like the induction heating coil C' shown in FIG. In the conductor 1, the inner sides of the opposing longitudinal sides extend over the tooth flanks of the tooth profile,
It is configured to face it with a predetermined gap therebetween. However, the hollow part of the conductor 1 of the induction heating coil C is different from that shown in FIG. 1, and is partitioned into upper and lower parts by a partition plate 11 watertightly provided in the middle part along the longitudinal direction. The one located above is called an upper passage 1a, and the one located below is called a lower passage 1b. The lower passage 1b is an induction heating coil C
A cooling fluid supply pipe 2a connected to a self-cooling fluid supply source _P1 is connected to one end of the self-cooling passage, and a cooling fluid discharge pipe 2b is connected to the other end thereof. The upper passage 1a is a quenching fluid passage, and a plurality of through holes are formed in the side wall of the quenching fluid passage 1a facing the tooth profile to be quenched, slanting downward with respect to the tooth profile, and forming injection holes 12. ing. A pipe 3a connected to a hardening fluid supply source _P2 is connected to one end of the hardening fluid passage 1a,
The other end is a watertight closed surface. Reference numeral 5 denotes a hardening fluid injection tube similar to that shown in FIG. 1b, and a plurality of cooling fluid injection holes 51 are formed in the lower wall facing the tooth top G _T. The hardening fluid injection pipe 5 is connected to a hardening fluid supply source _P2 via a pipe 3b. Pipes 3a and 3b are connected in parallel to a quenching fluid supply source _P2 ,
The pipe 3a has a valve 4a, and the pipe 3b has a valve 4b.
is inserted. Therefore, the amount of fluid supplied to the hardening fluid passage 1a and the hardening fluid injection pipe 5 can be increased or decreased by adjusting the valves 4a and 4b. The hardening fluid supply source _P2 can be driven intermittently so as to inject the hardening cooling fluid from the injection holes 12 and 51 every time the tooth profile _G1 to be hardened is heated to the hardening temperature. Reference numeral 6 denotes a shield plate made of a ferromagnetic material, which is attached to the outside of the longitudinally parallel portion of the conductor 1 of the induction heating coil. The shield plate 6 is for guiding the magnetic lines of force generated from the conductor 1 into itself, and preventing the lines of magnetic force from being diffused to the adjacent tooth profiles G ₂ and G ₂ ', thereby preventing the tooth profiles from being heated by induction.

In such a configuration, the tooth profile can be improved by the present invention.
The case of hardening the mountain part of _G1 will be described.

The induction heating coil C is mounted from above the tooth profile G ₁ so that the inside in the longitudinal direction of the conductor 1 spans the opposing flanks of the tooth profile G ₁ and maintains a predetermined gap therebetween. Next, after driving the self-cooling fluid supply source _P1 to cause the cooling fluid to flow into the self-cooling fluid passage 1b, a high frequency power source (not shown) is turned on. As a result, the conductor 1 is energized, and the lines of magnetic force generated from the conductor 1 cause the tooth flank G _S and tooth crest of the tooth profile G ₁ to be
The surface layer of _GT is heated. When the heated part is heated to the predetermined quenching temperature, the high-frequency power source is cut off to stop the current supply to the conductor 1, and at the same time, the quenching fluid supply source is turned off.
Drive _P2 . Thereby valves 4a and 4
The cooling fluid at a flow rate regulated by b flows through pipe 3.
a and 3b to the hardening fluid passage 1a and the hardening jet pipe 5, and the jet fluid from the jet hole 12 is directly diagonally directed from the upper G _SU to the lower G _SD of the tooth flank G _S. For example, the angle θ≦90° formed by the jet fluid with respect to the flank surface of the tooth, and the jet hole 5
The jet fluid from 1 is jetted directly to the tooth top G _T ,
The cooling capacity according to each flow rate
G _S should be applied uniformly from the top to the bottom, and at the top of the tooth.
_GT is cooled as prescribed. When the cooling is completed, the hardening of the tooth profile _G1 is completed by stopping the driving of the hardening fluid supply source _P2 .

Next, the induction heating coil C is displaced upward from the tooth profile G ₁ and placed over the adjacent tooth profile G ₂ or G ₂ ′, and the tooth profile G ₂ or G ₂ ′ is hardened by the same operation as described above. The tooth profile is then hardened successively.
In the above-mentioned hardening process, the lines of magnetic force generated from the conductor 1 in the direction of the adjacent tooth profile are guided to the shield plate 6 provided on the outside of the parallel part of the conductor ₁ in the longitudinal direction. tooth profile
The temperature rise due to leakage magnetic flux of G ₂ and G ₂ ′ can be suppressed to about 100℃ or less, and after heating G ₁ , G ₂ is heated immediately.
Or even if G ₂ ′ heating is performed, quenching is possible without being affected by the heat during G ₁ heating, and
Even if a tooth profile adjacent to a hardened tooth profile is hardened, there is no risk that the hardened tooth profile will be tempered.

According to the present invention, after the surface layer of the tooth flank and the tooth top of the tooth profile is heated to a predetermined hardening temperature, the tooth flank and the tooth top are cooled by cooling fluid jets that directly hit the tooth flank and the tooth top. The flow rate of the cooling fluid to each can be adjusted, and the cooling capacity for each can be made different.1.The tooth flank can be cooled reliably and the so-called soft quenching that occurs in the past can be avoided. 2. Also, in the conventional method, when a large amount of cooling fluid is injected into the tooth crest in order to sufficiently harden the tooth flank, there is also the drawback that the tooth crest becomes harder than necessary. do not have.

3. Also, by making the amount of cooling fluid injected to the top of the tooth smaller than that to the flank of the tooth, the edge effect prevents a large amount of injection from being applied to the ridgeline area, which would otherwise become overheated. This prevents the formation of unnecessarily high hardness and deep hardened layers, thereby avoiding quench cracking at the ridge line and breakage accidents during use, which are conventional.

4. In addition to being able to obtain a hardened layer with uniform hardness and depth over the tooth flank and the tooth top, 5. It is possible to freely form a hardened layer with a different desired hardness and depth on the tooth flank and the tooth crown. Its technical effects are remarkable.

[Brief explanation of the drawing]

FIG. 1a is a perspective view for explaining a conventional tooth profile hardening method, FIG. 1b is a sectional view taken along line A--A in FIG. 1a, and FIG. 2 is a sectional view showing an embodiment of the present invention. 1...Conductor, 1a...Quenching cooling fluid passage,
1b...Fluid passage for self-cooling, 5...Fluid injection pipe for quenching, 12, 51...Cooling fluid injection hole, C...
...Induction heating coil, G, G ₁ , G ₂ , G ₂ '...Tooth profile,
G _S ...Tooth flank, G _SU ...Upper part of tooth flank, G _T ...Tooth top,
P ₁ , 2a... Self-cooling fluid supply mechanism, P ₂ , 3
a, 3b, 4a, 4b...Quenching fluid supply mechanism.

Claims (1)

[Scope of Claims] 1. A hollow part of a rectangular loop-shaped hollow conductor formed such that its longitudinally opposing inner surfaces face tooth flanks on both sides of a tooth profile at a predetermined distance, 2. The lower part is divided into a fluid passage for self-cooling the conductor, and the upper part is a fluid passage for quenching.The inside wall in the longitudinal direction of the quenching fluid passage is equipped with an induction heating coil with a plurality of cooling fluid injection holes formed therein, and an induction heating coil with a plurality of cooling fluid injection holes formed on the top of the tooth. a quenching fluid injection pipe having a plurality of cooling fluid injection holes on opposing walls; a fluid supply mechanism for supplying cooling fluid to the self-cooling fluid passage of the induction heating coil; a quenching fluid passage of the induction heating coil; A tooth profile heat treatment device comprising a fluid supply mechanism that simultaneously supplies a quenching fluid to a quenching fluid injection pipe. 2 The hollow part of a rectangular loop-shaped hollow conductor is formed such that the inner surfaces facing each other in the longitudinal direction face the flanks of the teeth on both sides of the tooth profile at a predetermined distance. A self-cooling fluid passage, the upper part of which is a hardening fluid passage, an induction heating coil with a plurality of cooling fluid injection holes formed on the longitudinal inner wall of the said quenching fluid passage, and a plurality of induction heating coils formed on the wall facing the tooth top. A quenching fluid injection tube having a cooling fluid injection hole, a fluid supply mechanism for supplying cooling fluid to the self-cooling fluid passage of the induction heating coil, and a quenching fluid passage and quenching fluid injection tube of the induction heating coil. A tooth profile heat treatment apparatus, comprising a fluid supply mechanism that simultaneously supplies a hardening fluid, and a variable mechanism that varies the supply of cooling fluid to the hardening fluid injection pipe and the hardening fluid passage of the induction heating coil.