JP2002356713A - Induction hardening method, and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction hardening method in which the sufficient surface hardness of the surface to be treated of parts is obtained and the distor tion of the induction-hardened parts is reduced and an induction hardening apparatus. SOLUTION: The parts (for example, a transmission parts 1) is immersed in the quenching solution 11, and a coil head part 13a of an induction heating coil 13 is immersed in the quenching solution 11. The coil head part 13a is disposed close to the surface to be treated (for example, an inside diameter part of a small hole 5) of the parts 1, and the high frequency power of the frequency in the super-high frequency band is supplied to the induction heating coil for a short time to perform the induction heating of the surface, and at the same time, hardened and quenched with the quenching solution 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction hardening method and apparatus for induction hardening a surface to be processed of a component.

[0002]

2. Description of the Related Art FIG. 4 shows a transmission component 1 of an automobile. This transmission part 1
As shown in FIG. 5, three members (specifically, an upper part 2, a middle part 3, and a lower part 4) are welded to make one part for weight reduction. In addition, in FIG. 5, W is a welded part. Although carbon steel is used as the material of the lower part 4, mild steel that can be subjected to plastic working is used as the material of the upper part 2 and the middle part 3 in order to reduce costs.

In the transmission component 1 described above, a plurality of small holes 5 formed in the upper part 2 and a plurality of small holes 6 formed in the lower part 4 are aligned with each other. It is designed to be used with a shaft (not shown) inserted and arranged vertically.

The upper part 2 is made of mild steel to which plastic working can be applied, as described above, and has a material hardness lower than that of carbon steel. Therefore, it is necessary to improve the wear resistance of the small hole 5 in order to prevent the small hole 5 of the upper part 2 which is the shaft fitting portion from being worn. Therefore, as a means for improving the wear resistance of the small holes 5, it is conceivable to perform induction hardening. Specifically, a high-frequency induction heating coil (not shown) is arranged in the small hole 5 of the upper part 2 to perform high-frequency induction heating to a required temperature, and immediately thereafter, a cooling liquid (quenching water or the like) is injected into the heated portion. And quenching,
It is conceivable to obtain a required surface hardness (quenching quality) by forming a quench hardened layer of a required depth in the inner diameter part (peripheral part) of the small hole 5.

[0005]

However, in the induction hardening method of the small holes 5 which has been conventionally performed, although the wear resistance can be secured by induction hardening the small holes 5, the small holes 5 can be hardened. There is a problem that a large distortion is generated in the inner diameter shape of the hole 5. That is, when so-called stationary heating is performed in a state where the component (work) and the high-frequency induction heating coil are not relatively rotated, the shape of the high-frequency induction heating coil is greatly affected. Causes distortion. When such distortion occurs, the small hole 5 of the upper part 2 and the small hole 6 of the lower part 4 are displaced from each other, and the shaft passing accuracy (position accuracy) is deteriorated.
A disadvantage arises in that the shaft cannot be inserted through these small holes 5 and 6.

[0006] The quenching distortion of the small holes 5 is caused by deformation of the small holes 5 due to narrowing of the inner diameter due to volume expansion accompanying martensitic transformation by quenching. In other words, as the depth of the quenched hardened layer formed on the inner diameter portion (inner peripheral surface) of the small hole 5 by quenching increases, the volume expansion increases, and the amount of change in the inner diameter portion of the small hole 5 increases. , And tends to be easily distorted. By reducing the depth of the quench hardened layer, it is possible to reduce the quenching distortion of the inner diameter of the small hole 5, but at a frequency in the kHz band used for high-frequency induction heating for quenching, When the quench hardened layer depth is set to 0.5 mm or less,
The surface of the inner diameter of the small hole 5 which is the portion to be heated becomes lower than the appropriate heating temperature, and as a result, the surface hardness (hardening hardness) of the inner diameter of the small hole 5 becomes low. Incidentally, mild steel to which plastic working can be applied cannot secure a surface hardness of about Hv400. As a method of reducing the quenching distortion of the inner diameter portion of the small hole 5, there is a short-time heating method in which high-frequency induction heating is performed in a short time in order to minimize the influence of heat. When the heating time is set to 0.5 sec or less, only a quench hardened layer depth of 0.5 mm or less can be obtained, so that stable quenching quality cannot be ensured.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to achieve a sufficient surface hardness of a surface to be processed of a part and to obtain a part after induction hardening. It is an object of the present invention to provide an induction hardening method and an apparatus that can suppress distortion.

[0008]

In order to achieve the above-mentioned object, the present invention provides an induction hardening method for induction hardening a surface to be processed of a component. Under a state in which the coil head of the induction heating coil is immersed in the cooling liquid, the coil head is arranged close to the surface to be processed, and the high-frequency power of the frequency of the super-high frequency band is applied for a short time. The surface to be processed is subjected to high-frequency induction heating by supplying it to the high-frequency induction heating coil, and at the same time, quenched and cooled with the cooling liquid. In the present invention, the frequency of the ultrahigh frequency band is 1 MHz to
It is set to 4 MHz. Further, in the present invention, the time for supplying the high-frequency power of the frequency in the ultrahigh-frequency band to the high-frequency induction heating coil, that is, the heating time for the component is set to 0.4 sec or less. In the present invention, the carbon content of the component is 0.05% to 0.5%.
5%. Further, according to the present invention, in the induction hardening device for induction hardening the inner diameter portion of the small hole formed in the component, (A) a coolant is filled, and
(B) a high-frequency induction heating coil having a coil head inserted and arranged in the small hole; , (C) a high frequency power supply having a power frequency of an ultra-high frequency band of 1 to 4 MHz, wherein the component is immersed in a cooling liquid of the cooling liquid tank, and the component is immersed in a small hole of the component. Under the condition that the coil head of the high frequency induction heating coil is inserted and arranged, 1 to 4 MHz from the high frequency power supply.
By supplying the high-frequency power to the high-frequency induction heating coil, the inside diameter of the small hole of the component is quenched.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIGS. 1 to 3, the same parts as those in FIGS. 4 and 5 are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 shows an induction hardening apparatus 1 used for performing an induction hardening method according to an embodiment of the present invention.
0, the present device 10 is for induction hardening the inner diameter portion (inner peripheral surface) of the small hole 5 of the upper part 2 constituting the upper part of the transmission part 1. As shown in FIG. 1, the induction hardening apparatus 10 of the present embodiment has a cooling liquid tank 12 in which a cooling liquid 11 is filled (reserved), and a high-frequency hardening apparatus having a coil head 13 a inserted through the small hole 5. Induction heating coil 13 and high-frequency induction heating coil 13
, A high-frequency power supply 15 for supplying high-frequency power (high-frequency current) to the high-frequency induction heating coil 13 via the transformer 14, and a control panel 16 for adjusting and controlling the high-frequency power supply 15, respectively. Have.

The above-mentioned cooling liquid tank 12 is filled with a cooling liquid 11 such as cooling water, and a work 12 for holding the transmission component 1 as a work to be quenched on the bottom 12a. A receiving jig 17 is provided. Thus, the entire transmission component 1 is immersed in the coolant 11 in the coolant tank 12 while being held by the work receiving jig 17.
In this case, the upper part 2 constituting the upper part of the transmission part 1 is set so as to be arranged at a relatively shallow position near the liquid surface 11a of the coolant 11.

The above-described high-frequency induction heating coil 13
Is a water-cooled type which is cooled by coil cooling water, and as shown in FIGS. 1 and 2, a pair of leads 20a and 20b connected to the transformer 14, and these leads 20a and 20b It comprises an insulating plate 21 interposed therebetween and a coil head 13a having a substantially cylindrical cross section connected between the pair of lead portions 20a and 20b. The outer diameter of the coil head 13a is set slightly smaller than the inner diameter of the small hole 5 of the transmission component 1. Therefore, the coil head 13a is inserted into the small hole 5 with a small gap. It is set to be placed. Further, in the present embodiment, in order to improve the coupling efficiency of high-frequency oscillation, a dust core 22 made of a magnetic material is inserted and disposed in the hollow portion of the inner diameter of the coil head 13a.

The high-frequency power supply 15 has a frequency of 1 MHz.
A high frequency oscillator capable of oscillating a power frequency in an ultrahigh frequency band in the range of 4 MHz to 4 MHz. The control panel 16 converts high frequency power (high frequency voltage) in the range of 1 MHz to 4 MHz from the high frequency power It is configured to be supplied to the high-frequency induction heating coil 13 via the heater 14 sequentially. Furthermore, the control panel 16 can appropriately adjust the energizing time of the high-frequency induction heating coil 13 and, consequently, the high-frequency induction heating time within a range of 0.1 sec to 0.5 sec. The induction heating time is set within 0.4 sec (that is, in the range of 0.1 sec to 0.4 sec).

The high-frequency induction heating apparatus 10 having such a configuration
An example of a procedure and an operation when induction hardening the inner diameter portion of the small hole 5 of the transmission component 1 by using the following will be described as follows.

First, the cooling liquid tank 12 is filled with a cooling liquid such as cooling water, and the transmission component 1 to be quenched is filled.
Is fitted to a work receiving jig 17 in the cooling liquid 12 and held in the cooling liquid tank 12. Along with this, the entire transmission component 1 is immersed in the coolant 11 and the small holes 5 of the upper component 2 which is the part to be quenched are filled with the liquid surface 11 a of the coolant 11.
Is located in the vicinity of. Next, only the coil head 13a of the high-frequency induction heating coil 13 is put into the cooling liquid 11 and inserted into the small hole 5, and a slight gap is formed between the outer peripheral surface of the coil head 13a and the inner peripheral surface of the small hole 5. Are placed with a proper gap. Thereafter, the high-frequency power supply 15 is connected to the output cable 23.
And a high-frequency induction heating coil 1 through a transformer 14 in sequence.
3 is supplied with a high frequency power of 1 MHz to 4 MHz in an ultra high frequency band for a period of 0.1 sec to 0.4 sec. Thereby, the inner diameter portion of the small hole 5 facing the high-frequency induction heating coil 13 is subjected to high-frequency induction heating, and at the same time,
The quenching and cooling by the cooling liquid 11 is performed to form a quenched and hardened layer at the inner diameter of the small hole 5.

FIG. 3 shows a high-frequency power source 1 during high-frequency induction heating.
5 shows an example of a waveform of an output voltage (high-frequency oscillation output waveform) output to the high-frequency induction heating coil 13 from FIG. In this case, the rise time of the output voltage is 35 msec.
By doing so, high-frequency oscillation at a constant voltage of 85% or more becomes possible for a heating time of about 0.2 sec, and the quenching quality is stabilized.

According to the induction hardening apparatus 10 and the induction hardening method using the apparatus 10 as described above, heating is performed for a short time at the frequency of the ultrahigh frequency band. The surface hardness of the portion is sufficiently ensured, and the depth of the quench hardened layer is set to be shallower than in the conventional case. As a result, quenching distortion at the inner diameter of the small hole 5 can be reduced.

Hereinafter, specific embodiments of the present invention will be described. Example (1) Work (hardened body): Transmission parts (a) Material: SAPH (b) Small hole diameter: 12.0 mm (c) Plate thickness: 4.5 mm (2) High frequency induction heating conditions (a) ) High frequency input power: 16 KW (b) Frequency: 2.5 MHz (ultra high frequency band) (c) Heating time: 0.4 sec

The surface hardness when the inner diameter of the small hole 5 of the upper part 2 is quenched under the above quenching conditions is Hv (Vickers hardness) 500, and the depth of the hardened layer is from 0.3 mm to 0 mm. .
4 mm. In contrast, the conventional 200 kHz
At a frequency of about z, the surface hardness is Hv380,
The depth of the hardened layer was 1.0 mm to 1.2 mm.

According to the embodiment of the present invention as described above, the martensitic transformation amount decreases as the depth of the quenched hardened layer decreases by about 0.7 mm at a predetermined surface hardness (Hv 400 or more). did.

Further, in the embodiment of the present invention, the heating time is 0.4 sec, which is about 2.0 sec in the prior art, so that the heating time is about 1.6 sec in comparison with the conventional case.
c was shortened. As a result, the quench hardened layer depth decreases,
By shortening the heating time, distortion after quenching is reduced,
It was confirmed that the degree of the distortion was not at a level that would hinder the work of inserting the shaft into the small holes 5 and 6 at the time of assembling the transmission component 1. It was confirmed that good results were obtained when the heating time was set to 0.4 sec or less.

The material of the part to be quenched can suppress distortion after quenching to a practically usable level when the carbon content is 0.05% to 0.55%. Confirmed by experiment.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment.
Various modifications and changes are possible based on the technical concept of the present invention. For example, in the above-described embodiment, the small holes 5 of the transmission component 1 are induction hardened. However, when the inner diameter portions of the small holes formed in various components other than the transmission component 1 are induction hardened, The present invention can also be applied to the present invention. In addition, the present invention can be applied to the small holes 5 that are the quenching target portions, not limited to the circular holes, but may be various shapes such as an elliptical shape, a semicircular shape, and a rectangular shape.

[0024]

As described above, according to the induction hardening method and apparatus of the present invention, a component to be hardened is immersed in a coolant, and the coil head of the high-frequency induction heating coil is placed in the coolant. The coil head is placed in close proximity to the surface to be processed of the part under the condition of being immersed in the part, and the high frequency power of the frequency of the super-high frequency band is supplied to the high frequency induction heating coil for a short time so that the surface to be processed is At the same time as high-frequency induction heating, because the quenching and cooling with the cooling liquid,
The quenching distortion of the components caused by the quenching process can be suppressed to a small level while sufficiently securing the surface hardness of the surface to be processed. Therefore, in the case where the inner diameter of a small hole of a transmission part or the like formed by assembling a plurality of parts is induction hardened, the shaft cannot be inserted when the shaft is inserted into the small hole in a later process. In addition, the strength (surface hardness) of the small holes can be sufficiently secured, and high wear resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an induction hardening apparatus used for performing an induction hardening method according to the present invention.

FIG. 2 is a perspective view of a high frequency induction heating coil used in the high frequency hardening apparatus shown in FIG.

FIG. 3 is a diagram illustrating a waveform of an output voltage output from a high-frequency power supply to a high-frequency induction heating coil.

FIG. 4 is a perspective view showing a transmission part of a motor vehicle to be quenched.

FIG. 5 is an exploded perspective view of the transmission component described above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmission part 2 Upper part 5 Small hole 10 Induction hardening device 11 Coolant 11a Liquid level 12 Coolant tank 13 High frequency induction heating coil 13a Coil head 14 Transformer 15 High frequency power supply 16 Control panel 17 Work receiving jig

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koji Obayashi 10 Takane, Fujii-machi, Anjo, Aichi Prefecture Inside Aisin AW Co., Ltd. (72) Inventor Takanori Wakasugi 38 Ikenoue-cho, Takefu-shi, Fukui Prefecture Aisin AW Industry Co., Ltd. (72) Inventor Hideaki Katanuma 3-3-1 Marunouchi, Chiyoda-ku, Tokyo Denki Kogyo Co., Ltd. (72) Kiyoaki Kito 3-3-1 Marunouchi, Chiyoda-ku, Tokyo Denki Kogyo F term in the company (reference) 3K059 AA09 AA10 AB09 AB28 AC12 AC35 AD03 AD05 AD34 CD64 CD72

Claims (5)

[Claims] 1. An induction hardening method for induction hardening a surface to be processed of a component, wherein the component is immersed in a coolant and a coil head of a high frequency induction heating coil is immersed in the coolant. Under the following, the coil head is arranged close to the surface to be processed, and the surface to be processed is subjected to high-frequency induction heating by supplying high-frequency power having a frequency in an ultrahigh frequency band to the high-frequency induction heating coil for a short time. And quenching and cooling with the cooling liquid. 2. The frequency of the ultrahigh frequency band is 1 MHz to 4 MHz.
The induction hardening method according to claim 1, wherein the induction hardening method is set to MHz. 3. The heating device according to claim 1, wherein a time for supplying high-frequency power having a frequency in the ultrahigh-frequency band to the high-frequency induction heating coil, that is, a heating time for the component, is set to 0.4 sec or less. Induction hardening method. 4. The carbon content of said part is 0.05% to 0.55.
%. The induction hardening method according to claim 1, wherein 5. An induction hardening device for induction hardening an inner diameter portion of a small hole formed in a component, wherein (A) a coolant is filled and the component to be hardened is cooled. A cooling liquid tank housed and arranged in a state of being immersed in the liquid,
(B) a high-frequency induction heating coil having a coil head inserted and arranged in the small hole, and (C) 1 MHz to 4 MH
a high-frequency power source having a power frequency of a super-high frequency band of z, and immersing the component in a cooling liquid of the cooling liquid tank, and coiling the high-frequency induction heating coil in a small hole of the component. By supplying high-frequency power from the high-frequency power supply to the high-frequency induction heating coil under a state where the head is inserted and arranged, the internal diameter of the small hole of the component is quenched. Induction hardening equipment.