JPS603935A - Continuous rolling and surface hardening method of steel parts - Google Patents

Abstract

PURPOSE:To perform continuous rolling and surface hardening in the same stage by conducting high frequency electric current to a work to worm the work and rolling the work then increasing the current to heat the work up to the hardening temp. stopping the current conduction and hardening the work. CONSTITUTION:High frequency current is fed from a circuit 3 to both centers 2 and is conducted to a spindle 1 supported freely rotatably by both centers 2 to maintain the surface temp. thereof at about 550 deg.C. The spindle is then serrated by a die 4 and after the die 4 is retreated, the high frequency current to the spindle 1 is enhanced to increase the surface temp. thereof up to the hardening temp. of about 850 deg.C. The current conduction is interrupted at the point of the time when the hardening temp. is attained then a coolant is ejected from ejecting nozzles 5 to cool quickly the serrated part, thereby hardening the surface of said part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method in which surface hardening of a steel part is carried out in the same step following rolling.

Various types of spindles and shirts used as automatic 11 parts are used by applying rolling processing such as serrations to the surface of A, and then hardening the surface of that part. There are various types.

By the way, looking at the processing method for the above parts, the rolling side■
Conventionally, it has been common practice to perform cold hardening, followed by quenching and tempering in a separate process, and then surface hardening by high-frequency induction heating quenching in a separate process. The reason for separating the processes in this way is that in high-frequency induction heating quenching, the induction coil surrounds the part, making it impossible to perform rolling in the same process. ■ This was because it required a means to move the parts from the part, making the processing process extremely complicated. Therefore, the conventional processing method requires a large number of steps (it is disadvantageous in terms of time, and also requires the selection of materials that are easily plastically deformed due to the need for cold rolling); The PrI used for rolling processing has become larger, resulting in disadvantages such as an increase in stage preparation costs and installation space.

The present invention has been made to solve the above-mentioned conventional disadvantages, and focuses on the point that when a high frequency current is directly supplied to a steel part, the temperature of the surface of the material 11 can be changed continuously by controlling the current 11. By performing the rolling process at a warm temperature, we are able to increase the degree of freedom in material selection, while also making the processing equipment more compact and space-saving.

The purpose is to simplify the process with vtV.

For this purpose, the present invention applies a high-frequency current to the workpiece to apply warm rolling to the workpiece while maintaining a surface temperature of 2'a. It is characterized in that the surface temperature is raised to a quenching temperature by increasing the temperature, and then the energization is stopped to perform quenching.

As a related prior art, an induction hardening method in which main heating is performed following preheating by controlling the high frequency current M is found in Japanese Patent Publication No. 56-47927.

Hereinafter, the method according to the present invention will be explained with reference to the drawings and a description of the implementation apparatus.

In Fig. 1, reference numeral 1 indicates a spindle which is a workpiece, and is made of steel such as SCVRM, and is machined into a predetermined external shape so as not to be serrated by rolling. Supported. This center 2 also serves as an electrode of a high frequency current circuit 3, and is designed to directly feed high frequency current to the spindle 1 supported therebetween. Note that the above-mentioned current can be continuously changed by a controller (not shown). Reference numeral 4.4 in the figure is a pair of upper and lower serration rolling dies, which press against the circumferential surface of the spindle 1 and move in opposite directions perpendicular to the axial direction of the spindle 1. The predetermined serrations can be rolled. Furthermore, reference numeral 5 denotes a cooling water jet nozzle, which faces the circumferential surface of the portion of the spindle 1 to be serrated, and is arranged in a position that does not interfere with the upper and lower dies 4, 4.

First, a high frequency current is supplied to both centers 2.2 to energize the spindle 1. As a result, the moisture marks on the outer circumferential surface of the spindle 1 rise and 'Ctj <', so when the temperature reaches a temperature suitable for rolling between serrations, the supplied current is slightly reduced to maintain that temperature. As shown in Fig. 2, at the initial stage of energization, the energizing current is relatively large in order to preheat the spindle 1, and when the surface temperature of the spindle 1 reaches approximately 550°C, the current is reduced. It is kept at that temperature. In this case, since the relationship between temperature and current is influenced by the material and size of the spindle 1, which is the workpiece, the current is determined experimentally as appropriate depending on the workpiece.

In this manner, while the surface temperature of the spindle 1 is maintained at approximately 550° C., serrations are formed on the circumferential surface of the spindle 1 using a pair of upper and lower dies 4.4. Then, as shown in Figure 13, after retracting the dice 4.4 to the left and right of the spindle 1,
The high frequency current applied to the spindle 1 is increased to raise the surface 111Jj of the spindle 1 to a hardening temperature of approximately 850°C. When the predetermined quenching temperature is reached, 'C^
A frequency current is applied, and at the same time, a coolant such as water is ejected from the ejection nozzle 5.5 to perform rapid cooling, thereby completing the surface hardening of the plate portion 1a.

As explained above, how can the method of the present invention be applied to the workpiece? :
This method directly applies a 5-frequency current to obtain a surface temperature of 4q suitable for warm rolling, and while maintaining that temperature, a rolling die is pressed against the outer periphery of the workpiece to perform warm rolling. Since there are things that can be used for rolling, there is more freedom in selecting materials for workpieces, and there is also more flexibility in selecting materials for the workpiece. ! i! The driving force of the dies, etc. is reduced, and as a result, the device can be made smaller and save space.

In addition, since the surface of the workpiece is brought to a predetermined hardening temperature by increasing the high-frequency current applied to the workpiece, surface hardening must be performed in the same process following warm rolling. This makes it possible to significantly simplify the process compared to those that require the steps of cold rolling, quenching and tempering, and surface hardening.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view showing an embodiment of the method of the present invention;
The figure is a graph showing the relationship between changes in high-frequency current and the surface of the workpiece. FIG. 3 is a schematic plan view of the embodiment in a state of surface hardening. DESCRIPTION OF SYMBOLS 1...Spindle, 2...Center, 3...High frequency current circuit, 4...Dice, 5...Ejection nozzle. Patent Applicant Tomi: Meroeju Co., Ltd. Agent Patent Attorney Makoto Kobashi Ukiyo Patent Attorney Susumu Murai

Claims (1)

[Claims] A high-frequency current is internally applied to the workpiece, and rolling processing is performed on that part while maintaining a 1 m thickness suitable for the warm rolling side -L, and then the above current is increased. For rolling steel parts, characterized in that the surface hot stone is affected by the quenching hot stone by heating, and then the current is stopped and quenching is carried out.
J'3 J: Method for continuous surface hardening.