JP3584959B2 - Induction hardening apparatus and method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an induction hardening method in which high-frequency contour hardening is performed on the entire tooth width of the tooth portion of a helical gear in which tooth portions oblique to an axis are continuously formed in a circumferential direction on an outer peripheral surface. About the method .
[0002]
[Prior art]
For example, a high-frequency hardening device that performs high-frequency contour hardening on teeth that are irregularities formed on the peripheral surface of a helical gear is a ring-shaped device that is installed at a predetermined interval on the peripheral surface of the helical gear. And a cooling means for cooling the heated peripheral surface with a cooling liquid after the ultra short time heating by the high frequency heating coil is completed.
[0003]
In such a high-frequency contour quenching apparatus, as soon as heating of the work by the high-frequency heating coil is completed, the work is cooled by immersing the work in a coolant or spraying the coolant onto the work.
[0004]
[Problems to be solved by the invention]
However, the conventional method has the following problems. That is, as shown in FIGS. 5 and 6, the hardened layer W4 formed by induction hardening may not be formed on the end W2 of the side surface of the tooth portion W1 of the helical gear W. This is because, when a high-frequency current is applied to the high-frequency heating coil, the induced current generated on the surface of the helical gear W, which is a workpiece, is uniformly distributed along the tooth portion W1, which is an uneven surface of the end surface of the helical gear W. Due to not flowing to In the helical gear W, the teeth W1 which are the irregularities are inclined with respect to the axis W5, and the current density is high and the heating is performed in a short time. No induced current flows through the end W2 of the side surface on the side where the angle between the end surface of the helical gear W and the end surface is obtuse. For this reason, since the end portion W2 is not heated, a hardened layer is not formed even if the end portion W2 is cooled immediately after the end of the heating. If there is a portion where such a hardened layer is not formed, pitching or the like is likely to occur when the gear of the mating partner meshes with this portion. The lack of such a hardened layer is a problem specific to helical gears that are thin and have a sharper angle with respect to the axis W5 of the tooth portion W1.
[0005]
However, many conventional helical gears are thick and have a small angle with respect to the axis of the tooth portion, and there is no problem that a hardened layer is not formed at the end of the tooth portion. Further, even in the case of a thin helical gear, the end of the tooth portion is often used so as not to mesh with the counterpart tooth portion, so that this problem has not been given much importance.
[0006]
However, in recent years, the miniaturization of various machines has led to the demand for helical gears having thinner helical gears and helical gears having teeth with a sharp angle with respect to the axis, and that hardened layers have not been formed. It came to be regarded as important.
[0007]
The present invention has been made in view of the above circumstances, and even for a work having unevenness oblique to an axis like a helical gear, a hardened layer is formed even at the end of the tooth portion. It is an object of the present invention to provide an induction hardening method capable of forming a uniform hardened layer.
[0008]
[Means for Solving the Problems]
The high frequency quenching method according to the present invention is characterized in that the tooth portion of the helical gear, which is formed on the outer peripheral surface and is inclined with respect to the axis continuously in the circumferential direction, has a high frequency An induction quenching method for performing quenching, wherein when a temperature at which the helical gear melts is T (° C.) in a high-frequency heating coil that heats the tooth portion, the tip of the tooth portion of the helical gear and The main heating is performed after repeating the preheating two or more times at a bottom of 0.3 T to 0.4 T (° C.).
[0009]
In another high frequency quenching method according to the present invention, a high frequency heating coil for heating the tooth portion may heat the tip and bottom of the tooth portion of the helical gear to just below the A1 transformation point once or twice. A high-frequency contour quenching method for performing high-frequency contour quenching on the unevenness of the work in which the unevenness is formed obliquely with respect to the axis, which is characterized in that the main heating is performed after repeating the heat treatment for at least two times. When the temperature at which the work is melted is T (° C.) using a high-frequency heating coil for heating the workpiece, the preheating of the irregularities of the work is repeated twice or more preheating at 0.3 T to 0.4 T (° C.). Later, main heating is performed.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic configuration diagram of an induction hardening apparatus according to an embodiment of the present invention, and FIG. 2 is a lotus as a workpiece subjected to high-frequency contour hardening by the induction hardening apparatus according to the embodiment of the present invention. FIG. 3 is a schematic sectional view taken along line AA of FIG. 2. FIG. 4 is a schematic configuration diagram of an induction hardening apparatus according to another embodiment of the present invention.
[0013]
Induction hardening apparatus according to an embodiment of the present invention, the teeth W gear W helical a workpiece teeth W ₁ is unevenness is oblique with respect to the axial center W ₅ are formed ₁ a high-frequency hardening apparatus for performing the high-frequency contour hardening, cooling the high-frequency heating coil 100 for heating the teeth W ₁ of the gear W helical, the teeth W ₁ which has been heated by the cooling liquid L is cooled to And a storage tank 200 as a means.
[0014]
Gear W helical which is a work, as shown in FIG. 2, and has a toothed portion W ₁ which is oblique with respect to the axial center W _5. More precisely, the helical gear W refers to a cylindrical gear having a helical toothed line. Here, the tooth portion _{W 1} of the distal end of the tooth _{W 11,} between the teeth _{W 1} and the tooth portion _{W 1} and the tooth bottom _{W 12.}
[0015]
The high-frequency heating coil 100 is formed in a ring shape, connected to the heating conductor 110 opposed at a predetermined interval with respect to the tooth portion W ₁ of the gear W helical, and the heating conductor 110 and a high frequency power supply 400 And a power supply conductor 120 for performing the operation.
[0016]
The high-frequency heating coil 100 is formed of a conductive pipe made of copper or the like, and circulates a cooling liquid such as water inside to prevent overheating of itself.
[0017]
A high-frequency preheating coil 150 for preheating is installed above the high-frequency heating coil 100. The high frequency preheat coil 150 is a so-called multi-turn type heat conductor 151 becomes spiral, the heat conductor 151 opposed at a predetermined interval with respect to the tooth portion W ₁ of the gear W helical, the heating conductor And a power supply conductor 152 for connecting the high-frequency power supply 450 to the power supply conductor 151. Further, the high-frequency preheating coil 100 is formed of a conductive pipe made of copper or the like, and circulates a cooling liquid such as water inside to prevent overheating of itself.
[0018]
On the other hand, the storage tank 200 stores the cooling liquid L and is provided directly below the high-frequency heating coil 100.
[0019]
Further, the induction hardening device is provided with a work support portion 300 for supporting the helical gear W, a handling device (not shown) for attaching and detaching the helical gear W to and from the work support portion 300, and the like. I have. The work supporting unit 300 is configured to move the helical gear W, which is a work, to a preheating position inside the high-frequency preheating coil 150, a heating position inside the high-frequency heating coil 100 immediately below the helical gear W, and a cooling position of the storage tank 200 immediately below the high-frequency heating coil 100. And move between them. Note that a concentric ring 310 is set on both upper and lower surfaces of the helical gear W.
[0020]
Next, the operation of the induction hardening apparatus will be described.
First, the gear W helical is supported horizontally on the work supporting unit 300, the high frequency preheat coil 150 around the tooth portion W ₁ of the gear W helical is set. That is, the helical gear W is at the preheating position.
[0021]
High-frequency current is supplied from the high-frequency power supply 550 to the high-frequency preheating coil 150 to perform preheating.
This preheating, when the temperature of the gear W to dissolve the helical is a work with T (° C.), the tooth bottom is addendum W ₁₁ and the bottom portion is the tip of the tooth portion W ₁ of the gear W helical W Preheating is performed so that the temperature of the substrate ₁₂ becomes 0.3 to 0.4 T (° C.). This preheating may be one, two or more. When performing such preheating, it is the temperature of the tooth tip W ₁₁ and the tooth bottom W ₁₂ becomes uniform.
[0022]
When the preheating is completed, the work supporting unit 300 moves down to move the helical gear W to the heating position.
In the main heating performed at this heating position, a high-frequency current is supplied from the high-frequency power supply 400 to the high-frequency heating coil 100. Incidentally, since the temperature at which the steel is dissolved is about 1500 ° C., it is desirable to heat the tooth _{W 11} such as about 420 ° C. to 560 ° C. in preheating.
[0023]
The helical gear W that has been preheated and main-heated in this manner is lowered to the cooling position, and is immersed in the cooling liquid L in the storage tank 200 immediately below. By this immersion, induction hardening is performed on the helical gear W to form a hardened layer.
[0024]
By carrying out such preheating, hardening layer to be heated end W ₂ of the portion of the gear W also sufficiently helical is formed. Therefore, problems such as pitching hardly occur.
[0025]
Further, a cooling jacket 500 for injecting the cooling liquid L is provided below the high-frequency heating coil 100 without providing the storage tank 200, and the helical gear W is cooled by the cooling liquid L from the injection hole 510 of the cooling jacket 500. You may make it.
[0026]
In the embodiment described above, in the preheating was heated addendum _{W 11} etc. helical gear W to 0.3~0.4T (℃), just below _{the A 1} transformation point (e.g., about 700 ° C.) You may make it heat. Incidentally, the steel of _{A 1} transformation point is 727 (° C.).
[0027]
In the above-described embodiment, the helical gear W is used as the workpiece. However, it is needless to say that the present invention can be applied to a helical internal gear and a helical gear.
[0028]
【The invention's effect】
As described above, in the case of the induction hardening method according to claim 1 or 2 of the present invention, since the tip and the bottom of the tooth portion of the helical gear are sufficiently heated and then cooled, the high frequency Quenching can be performed reliably. That is, since induction hardening is performed on the entire tooth width of the tooth portion of the helical gear, problems such as pitching do not occur.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an induction hardening device according to an embodiment of the present invention.
FIG. 2 is a schematic perspective view of a helical gear as a workpiece on which high-frequency contour hardening has been performed by the high-frequency hardening apparatus according to the embodiment of the present invention.
FIG. 3 is a schematic sectional view taken along line AA of FIG. 2;
FIG. 4 is a schematic configuration diagram of an induction hardening device according to another embodiment of the present invention.
FIG. 5 is a schematic perspective view of a helical gear as a work on which high-frequency contour hardening has been performed by a conventional high-frequency hardening device.
FIG. 6 is a schematic sectional view taken along line BB of FIG. 5;
[Explanation of symbols]
100 High frequency heating coil L Coolant W Helical gear (work)
W ₁ tooth (unevenness)
W ₅ axis core

Claims (2)

An induction hardening method for performing high-frequency contour hardening over the entire tooth width of the tooth portion of a helical gear in which tooth portions oblique to an axis are continuously formed in a circumferential direction on an outer peripheral surface. When the temperature at which the helical gear melts is T (° C.) in a high-frequency heating coil that heats the tooth part, the tip and bottom of the tooth part of the helical gear are 0.3T to 0.4T ( C)), followed by main heating after repeating the preheating at least twice. An induction hardening method for performing high-frequency contour hardening over the entire tooth width of the tooth portion of a helical gear in which tooth portions oblique to an axis are continuously formed in a circumferential direction on an outer peripheral surface. The main heating is performed after repeating the preheating of heating the tips and bottoms of the teeth of the helical gear to just below the A1 transformation point twice or more with a high-frequency heating coil for heating the teeth. Induction hardening method.

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