JP4477842B2 - High frequency induction heating method - Google Patents

Description

  The present invention relates to a high-frequency induction heating method in the case where the number of induction hardening processes is different during one-shot heat treatment (one high-frequency induction heat treatment).

  FIG. 4 shows a generally used steering rack bar 1 (hereinafter simply referred to as rack bar 1). The rack bar 1 has inclined teeth 2 having an angle θ with respect to the axis P on one side surface, and a surface opposite to the tooth surface 3 of the inclined teeth 2 is a back surface (semi-cylindrical surface) 4. Yes. As shown in FIG. 4, the rack bar 1 has a shaft portion 5 having a circular cross section that continuously extends from the entire circumferential surface including the tooth surface 3 and the back surface 4. Conventionally, when quenching such a rack bar 1, the rack bar 1 is continuously hardened by high-frequency induction heating by a moving heating method using a high-frequency induction heating device 6 as shown in FIG. 5. It is made to process (for example, refer patent document 1).

On the other hand, for the purpose of increasing the production efficiency, from the method of centering and quenching one workpiece (object to be heated), two workpieces are centered (hereinafter referred to as “two axes”) and two high frequency inductions are performed simultaneously. The method is improved to a method of heating (hereinafter referred to as biaxial heating) and quenching (hereinafter referred to as biaxial quenching). In the case of this biaxial heating, in order to reduce the equipment cost, a power supply system is generally constituted by one oscillator, one transformer, and one high-frequency coil. The high-frequency induction heating coil for biaxial heating has two inductance portions (coil constituent portions), which are connected in series (connected in series). In the biaxial quenching, a work such as the rack bar 1 is inserted into two inductance portions of the high frequency induction heating coil, respectively, the two works are simultaneously subjected to high frequency induction heating, and then cooled, and then the required parts of the rack bar 1 are cooled. This is done by forming a hardened and hardened layer.
JP 54-107812 A

  In the case of induction hardening, the slight difference in workpiece material, pretreatment, cutting conditions and induction induction heating affects the heat treatment quality after hardening, hardness, depth of hardened layer, and distortion. Are managed for each production lot. In the case of quenching production, in order to reduce the variation in heat treatment quality, the quenching conditions are determined for each lot, the first product is quenched, the heat treatment quality of the first product is inspected and confirmed, and then the production process is performed. Has been. In the case of biaxial quenching, in general, two workpieces are transported by lift & carry or transformer, and two workpieces are centered at the induction hardening station, and then moved and heated simultaneously by one high frequency induction heating coil ( Biaxial heating) is performed and quenching is performed. Therefore, in biaxial heating, since two workpieces are processed, the number of processing (the number of workpieces to be processed) needs to be an even number. However, when the number of workpieces is an odd number, the last one cannot be hardened and one remainder is generated in the production process. At present, when the number of processing is an odd number, one workpiece cannot be processed in lot units, and the production efficiency is hindered.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a high-frequency induction heating that does not cause the remainder of a work to be generated in lot units in a high-frequency induction heating process during a quenching process or the like. It is to provide a method.

In order to achieve the above-described object, in the present invention, one high frequency induction heating coil having two or more inductance parts connected in series is arranged on the outer periphery of a work to be heated, and the work is subjected to high frequency induction heating. In the high frequency induction heating apparatus configured as described above, a control device in which high frequency induction heating conditions corresponding to the number of the workpieces disposed inside the two or more inductance portions are set in advance is provided, and the high frequency induction heating of the workpiece is performed. In this case, a heating condition corresponding to the number of the workpieces arranged inside the inductance portion of the high-frequency induction heating coil is selected by the control device , the setting condition of the high-frequency induction heating coil is changed, and the high-frequency induction heating is performed on the workpiece. Like to do.
Also, in the present invention, the high-frequency frequency of the power supplied to the high-frequency induction heating coil, so that is 1～800KHz.

The present invention, on the outer circumference of the to be heated workpiece, the apparatus for high-frequency induction heating by placing one of the high-frequency induction heating coil having an inductance portion of the two or more portions which are connected in series, the high-frequency induction heating coil of the inductance section In order to enable high-frequency induction heating with a predetermined heat treatment quality even if the number of workpieces arranged on the inside changes, a control device in which heating conditions corresponding to the number of workpieces are set in advance is provided. By setting the heating conditions corresponding to the number of workpieces (that is, by changing the setting conditions of the high-frequency induction heating coil corresponding to the number of workpieces), it is possible to prevent surplus workpieces in the heat treatment for each lot. . Therefore, according to the present invention, by adopting a high-frequency induction heating device that can change the heating conditions (production conditions) corresponding to the number of workpieces, the number of heating processes in one-shot heat treatment can be changed, Heat treatment can be performed without producing surplus in lot production.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a biaxial moving quenching apparatus 11 for a rack bar 1 provided with a high frequency induction heating apparatus 10 according to the present invention. As shown in FIG. 1, the high frequency induction heating apparatus 10 includes two centering mechanisms 12a and 12b for centering two works (for example, rack bars and the like) W ₁ and W ₂ and one high frequency for biaxial heating. An induction heating coil 13 and a work rotation motor 14 are provided.

  As shown in FIG. 2, the above-described high frequency induction heating coil 13 has inductance portions 13a and 13b at two separate locations, and these inductance portions 13a and 13b are connected in series (series connection) to each other. . The high-frequency induction heating coil 13 is connected to a high-frequency oscillator (high-frequency power source) 15 through a single transformer (not shown). Further, the high-frequency induction heating device 10 is provided with a control device 16 in which high-frequency induction heating conditions are set in advance corresponding to the number of workpieces arranged inside the two inductance portions 13a and 13b. The heating device is configured so that a heating condition corresponding to the number of workpieces arranged inside the inductance portions 13a and 13b of the high-frequency induction heating coil 13 is selected by the control device 16 during heating, and the workpiece is heated by high-frequency induction.

FIG. 2 shows the relationship between the two workpieces (for example, the rack bar 1 and the like) W ₁ and W ₂ centered on the high-frequency induction heating coil 13 for biaxial heating and the quenching conditions. In the case of biaxial heating, the two workpieces W ₁ and W ₂ are respectively arranged inside the two inductance portions 13a and 13b of the high-frequency induction heating coil 13 (that is, the heating conductor portion that is a coil constituent portion) and controlled. The moving heating is performed under the heating condition A preset in the apparatus 16. In the case of uniaxial heating, one work W ₁ is arranged inside one inductance portion 13 a of the high-frequency induction heating coil 13, and moving heating is performed under the heating condition B set in advance in the control device 16. It has come to be. That is, when the work is subjected to high frequency induction heating, the control device 16 selects a heating condition according to the number of works arranged inside the inductance portions 13a and 13b of the high frequency induction heating coil 13, and the entire high frequency induction heating coil 13 is set. The conditions are changed and the workpiece is heated by high frequency induction.

  Therefore, according to the high frequency induction heating apparatus 10 of the present embodiment, the preset quenching condition A or B is selected according to the number of workpieces to be centered, and the high frequency induction heating is performed. There are no restrictions depending on whether the number is even or odd.

  The heat treatment quality (quenching quality) when the uniaxial and biaxial heating was performed by the above-described high frequency induction heating apparatus 10 was as shown in FIG. As can be seen from FIG. 3, the hardened layer pattern S is connected to the entire circumference of the rack portion and the shaft portion of the rack bar, which is a workpiece, and it was confirmed that a predetermined surface hardness was ensured.

Below, the specific Example at the time of carrying out the high frequency induction heating of the workpiece | work using the high frequency induction heating apparatus which concerns on this invention is shown.
Example (1) Workpiece: Rack bar (a) Material: S45C
(B) Dimensions (i) Shaft diameter: φ32mm
Rack outline: φ32mm
Length: 790mm
(Ii) Teeth right angle module: 2.1
Tooth height: 3.5mm
Tooth right angle bitch: 6.7mm
(2) High frequency induction heating conditions [I] Biaxial heating (i) Shaft: Frequency = 20 kHz
Output = 124kW
Feed rate = 26mm / sec
(Ii) Tooth part: Frequency = 20 kHz
Output = 79kW
Feed rate = 14mm / sec
[2] Uniaxial heating (i) Shaft: Frequency = 20 kHz
Output = 82kW
Feed rate = 24mm / sec
(Ii) Tooth part: Frequency = 20 kHz
Output = 67kW
Feed rate = 13mm / sec

  The surface hardness of the tooth portion when the rack bar is subjected to high-frequency induction heating under the above heating conditions and subjected to quenching treatment is Hv 670 to 700 in the case of biaxial heating and in the case of uniaxial heating. In the case of biaxial heating, the thickness was 3.3 to 3.5 mm in both cases of uniaxial heating. The surface hardness of the shaft portion of the rack bar is Hv 680 to 710 in the case of biaxial heating and in the case of uniaxial heating, and the hardened layer depth is 0.3 to 1 in both biaxial heating and uniaxial heating. .6 mm. It was confirmed that both the biaxial and uniaxial heating satisfied the surface hardness and hardened layer depth, which are heat treatment specifications. Conventionally, when a high-frequency induction heating coil for biaxial heating is used, the quenching process is performed only for biaxial heating. It was verified that quenching quality was obtained. Since the high-frequency induction heating coil for biaxial heating can satisfy the heat treatment quality of biaxial heating and uniaxial heating, the number of production processes does not necessarily have to be an even number, and the total number of processes is an odd number. However, no surplus (surplus work) is generated during production.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and changes can be made based on the technical idea of the present invention. For example, in the above-described embodiment, the high-frequency induction heating coil 13 is for biaxial heating, but is not limited to biaxial, and may be a high-frequency induction heating coil for n-axis heating (n is an integer of 3 or more). Further, the number of workpieces inserted into the high-frequency induction heating coil for n-axis heating is not limited to one or two, and n cases may be divided. This apparatus can be used by setting the heating condition corresponding to the n number of cases in the control apparatus 16. In addition, the high frequency induction heating apparatus of this invention is not limited to a moving heating, It can be used also for one-shot heating. Furthermore, the heat treatment is not limited to quenching, and the apparatus can be used for tempering or quenching and tempering.

It is a front view which shows the induction hardening apparatus which has a high frequency induction heating apparatus which concerns on one Embodiment of this invention. It is a figure which shows schematically the high frequency induction heating coil used for the high frequency induction heating apparatus of FIG. 1, Comprising: FIG. 2 (a) is explanatory drawing which shows the state of biaxial heating, FIG.2 (b) is 1 axis | shaft. It is explanatory drawing which shows the state of a heating. FIG. 3 is a cross-sectional view showing a hardened layer pattern obtained when the rack bar is subjected to high-frequency induction heating with the high-frequency induction heating apparatus of FIG. 1 and quenched, and FIG. 3A is a plan view including the rack bar axis line. 3B is an enlarged sectional view taken along the line XX in FIG. 3A, and FIG. 3C is an enlarged sectional view taken along the line YY in FIG. 3A. It is a side view of a rack bar for steering. It is a perspective view which shows the high frequency induction heating apparatus of the conventional rack bar.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rack bar 10 High frequency induction heating apparatus 11 High frequency hardening apparatus 13 High frequency induction heating coil 13a, 13b Inductance part 15 High frequency oscillator (high frequency power supply)
16 control device W _1, W ₂ work

Claims (2)

In the high frequency induction heating apparatus in which one high frequency induction heating coil having two or more inductance portions connected in series is arranged on the outer periphery of the work to be heated to heat the work by high frequency induction, the two places A control device in which high-frequency induction heating conditions corresponding to the number of the workpieces arranged inside the inductance portion are set in advance is provided, and the high-frequency induction heating coil is arranged inside the inductance portion of the high-frequency induction heating coil. A high-frequency induction heating apparatus characterized in that a heating condition corresponding to the number of workpieces to be selected is selected by the control device , the setting conditions of the high-frequency induction heating coil are changed, and the work is subjected to high-frequency induction heating. . The high frequency induction heating apparatus according to claim 1, wherein a high frequency of a power source supplied to the high frequency induction heating coil is 1 to 800 kHz.

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