JP2623259B2 - Induction tempering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Prior Art) For example, in a cylindrical body W with a shaft as shown in FIG. 4, a predetermined portion of the inner wall of a large cylindrical portion Wp serves as a sliding portion, so that it is provided with wear resistance. Further, for example, the area of the shaft portion Ws indicated by double oblique lines is surface quenched in order to improve the mechanical properties. However, as is well known, the quenched member is subjected to a tempering treatment because the member lacks toughness as it is.

Conventionally, when tempering a member having such a complicated shape is to be performed by, for example, high-frequency induction heating, the heating temperature of each member is 290 ° C. at the center of the shaft portion Ws, 240 ° C. at the end, and the cylindrical portion Wp.
Induction tempering was considered unsuitable for a cylindrical body W with a shaft, and the maximum and minimum were as high as 220 ° C., and the maximum and minimum reached 70 ° C., resulting in an extremely large temperature difference.

(Problems existing in the prior art) Tempering by heating in an electric furnace can process a plurality of shafted cylinders W at one time, but it takes time, and it is time-consuming to align and pack in a basket for insertion into an electric furnace. In addition to this, the production of the line is interrupted due to the tempering process, and the electric furnace is heated as described above because the entire cylindrical body W with the shaft is put into the furnace and tempered under exactly the same temperature conditions. To the extent that the hardness of the cylindrical body part Wp does not decrease too much for the purpose of wear resistance, and the shaft part Ws has a lower hardness than the large part of the cylindrical part Wp for the purpose of improving mechanical properties. However, tempering with an appropriate difference in the heating temperature was impossible.

(Object of the Invention) The present invention has been made in order to solve the above-mentioned weak points of the conventional electric furnace tempering when tempering a cylindrical body with a shaft, and the heating temperature difference in the shaft portion is substantially uniform. It is an object of the present invention to provide a high-frequency tempering method capable of performing a tempering process at a heating temperature at which an appropriate temperature difference is applied to a shaft portion.

(Structure of the Invention) The structure of the present invention is such that, when tempering a cylindrical body with a shaft by high-frequency induction heating, the winding diameter is larger than the outer diameter of the cylindrical part of the cylindrical body with a shaft, and the winding length is sufficiently longer than the entire length. Using a multi-turn heating coil connected to a long high-frequency power source, a magnetic body having a predetermined length and an end surface having substantially the same diameter as the end surface is provided on the shaft end surface of the shafted cylinder placed in the coil. Also, a magnetic body made of a solid bar having substantially the same outer diameter as the end face or a cylindrical material having substantially the same outer diameter and a predetermined inner diameter is pressed and abutted on the end face of the cylindrical body. An induction tempering method characterized by heating.

According to the present invention, the magnetic body pressed and abutted on both end surfaces of the cylindrical body with the shaft prevents the magnetic flux transmitted through the shaft portion from diffusing from the vicinity of the end surface in the shaft portion, thereby substantially forming the shaft portion. The cylinder is heated to a uniform tempering temperature, and the magnetic flux transmitted through the cylinder is converged and controlled in the cylinder, so that the cylinder can be heated to a desired appropriate tempering temperature.

[Example 1] ○ Experimental method: Specimens A and B which are cylindrical bodies W having the same shape and having a shaft diameter of 30 mmφ are used, and the shaft Ws end face of the specimen A is shown in FIG. As shown, carbon steel with a shaft diameter of 30 mmφ (S4
Bar Ia consisting of 5C material) and the specimen B
As shown in Fig. (B), a bar I made of the same material and having a shaft diameter of 40mmφ
b, in a state of being pressed and abutted against the end face of the shaft Ws, respectively, is fixed in a multi-turn coil HC connected to a high-frequency power supply of 3 KHz and an output of 40 KW, and is energized for 15 seconds. A plurality of different member temperature measuring reagents applied to the peripheral surface and the peripheral surface in the vicinity of the end portion (reagents that change color from a normal color at different temperatures when the members are heated. The heating temperature was measured by applying the coating in parallel to the portion and measuring the temperature increase of the portion.

○ Experimental results; As shown in FIGS. 1 (a) and (b),
In the specimen A, the center of the shaft Ws was 235 ° C, and the vicinity of the end was 227 ° C.
° C, and in the specimen B, the center of the shaft Ws was 225
It was confirmed that the temperature rose to 240 ° C in the vicinity of the end and 240 ° C.

From the results of the above [Experimental example 1], the specimen A according to a part of the present invention had a heating temperature difference of 8 ° C., and the shaft portion shown in FIG. In addition to the temperature difference of 50 ° C in Ws, the heating temperature
It was proved that substantially uniform heating in the shaft portion Ws was achieved, with only half the temperature compared to ° C.

[Experimental example. 2] ○ Experimental method: The same cylindrical cylinders C, D and E as those used in [Experimental example 1] above were used as test specimens. Magnetic body I a having substantially the same end face
Press and abut, and the inner and outer diameters are approximately 70mmφ and
To the end face of the deformed cylindrical body Wp of 90 mmφ (not a perfect cylinder, the thickness is also uneven in the circumferential direction),
2A. As shown in FIG. 2A, a cylindrical magnetic body Ic having inner and outer diameters of 70 mmφ and 90 mmφ, respectively, which is considered to have substantially the same shape as the end face of the specimen C, and a specimen D shown in FIG. As described above, the outer diameter is regarded as substantially the same as the end face of the specimen D, but the inner diameter is 55 mmφ.
And a thick cylindrical magnetic body Id, and the specimen E is a magnetic body I made of a solid rod having an outer diameter of 90 mmφ as shown in FIG. 2 (c).
e (Each S45C material) is pressed and contacted, [Experimental example.
Heating was performed under the same conditions as in [1], and the heating temperature at the center of each of the cylindrical body Wp and the shaft Ws of each of the specimens C to E was measured using a temperature measuring reagent.

○ Experimental results: As shown in FIGS. 2 (a) to 2 (c), in the specimen C, the temperature of the cylinder Wp was increased to 204 ° C. and the temperature of the shaft Ws to 230 ° C., and the temperature difference was 26 ° C. In sample D, the temperature of the cylinder Wp rises to 195 ° C and the temperature of the shaft Ws rises to 227 ° C. The temperature difference is 32 ° C. In sample E, the temperature of the cylinder Wp rises to 175 ° C and the temperature of the shaft Ws rises to 225 ° C. As a result, it was confirmed that the temperature difference was 50 ° C.

From the results of the above [Experimental Example 1] and [Experimental Example 2], the present invention relates to the induction tempering of a shaft barrel W with a shaft.
(1) The pressing and contacting of the magnetic body Ia having substantially the same end face as the end face is effective for equalizing the temperature of the shaft portion Ws. (2) The heating temperature of the cylindrical body portion Wp is pressed and contacted to the end face. Because the heating temperature of the cylindrical body Wp is not greatly different from the heating temperature of the shaft Ws without using the magnetic body I of the conventional method, it depends on the shape of the magnetic body I. In addition, it has been proved that the temperature can be controlled, and an appropriate tempering temperature can be easily obtained by setting the shape of the magnetic body I to a predetermined value.

In addition, each of the above [Experimental Example.1] and [Experimental Example.2] is a case where the target heating temperature of the shaft portion Ws is set to 230 ° C.
Needless to say, if the used power source / target heating temperature of the shaft portion Ws, the mass relationship between the shaft portion Ws and the cylindrical portion Wp, etc. are different, the cylindrical portion Wp shows a heating temperature slightly different from that of the above embodiment. .

Therefore, in practicing the present invention, it is necessary to appropriately design the magnetic body I in accordance with the conditions of the possessed equipment and the required heating temperature. As long as the tempering of the cylindrical body W with a shaft to be performed is considered to be an application of the present invention.

In the above [Experimental Example 1] and [Experimental Example 2], the magnetic body = impeder I as a jig is pressed and brought into contact with the end face of each of the shafted cylinders W which are fixedly heated in the multi-turn coil HC. However, as shown in FIG. 3, for example, a tubular body W with a shaft that presses and abuts opposite end surfaces on each other is continuously passed through an axial feed into a multi-turn coil HC set to a predetermined length. You may make it do. However, this method can be adopted only when the heating temperature of the cylindrical portion Wp is maintained at an appropriate required temperature difference from the heating temperature of the shaft portion Ws.

(Effects of the Invention) By implementing the present invention, (1) it is possible to apply a high frequency tempering to a shafted cylinder instead of an electric furnace tempering, so that interruption of line production is avoided, and the design is made in advance. Intermittent heating by a heating device equipped with a magnetic material or tempering by continuously feeding a cylindrical body with a shaft or tempering built into a production line as continuous heating can be realized, thus enabling full automation of line production and improving productivity. Is achieved, and tempering by uniform heating of the shaft portion and controlled appropriate heating of the cylindrical portion is achieved, and the effect brought about is extremely remarkable.

[Brief description of the drawings]

1 (a) and 1 (b) are front sectional views showing experimental methods and experimental results in [Experimental Example 1], respectively, and FIGS. 2 (a) to 2 (c) are experiments in [Experimental Example 2], respectively. FIG. 3 is a partial cross-sectional front view showing an application example of the present invention, and FIG. 4 is a cross-sectional front view showing a state in which a cylindrical body with a shaft is tempered and heated by a known method. It is.

Claims (3)

(57) [Claims] 1. A high-frequency power supply having a winding diameter larger than an outer diameter of a cylindrical portion of the shaft-equipped cylindrical body and a winding length sufficiently longer than the entire length when the shaft-equipped cylindrical body is tempered by high-frequency induction heating. A magnetic body having a diameter approximately equal to the end surface and a predetermined length is provided on the shaft end surface of the cylindrical body with the shaft placed in the coil using a multi-turn heating coil connected to the coil, and the cylindrical body end surface. In this method, a solid bar having substantially the same outer diameter as the end face or a cylindrical material having substantially the same outer diameter and a predetermined inner diameter is heated while being pressed and abutted. Induction tempering method characterized by the above-mentioned. 2. The high-frequency tempering method according to claim 1, wherein the magnetic material is an impedance as a jig. 3. The high frequency tempering method according to claim 1, wherein the magnetic body is a cylindrical body with a shaft whose opposite end faces are pressed and brought into contact with each other.