JPS58133314A - Heat treating method - Google Patents

Abstract

PURPOSE:To conserve heat energy required in the next heat treating process, by a method wherein a heat radiation part and a preheating part in a heat exchange chamber are formed in adjacent relation to each other and, after a high tmp. forged product is cooled in the heat radiation part, it is taken out of the chamber to be cooled to a room temp. to be subsequently preheated in the preheating part by the gas of the heat radiation part. CONSTITUTION:A high temp. forged product (a) directly after hot forging is charged into the heat radiation part 3 of a heat exchange chamber 1 from a charging door 5 to be cooled by flowing air from a recirculation fan 10 and the air cooled forged product (b) is succeedingly cooled by taking the same out of the chamber 1 from a discharge door 6 to obtain a forged product C with a temp. of Ar1 transformation point or less. In the next step, this forged product C is charged into a preheating part 4 from a charging door 7 and heated by the gas from the heat radiation part 3 to obtain a forged product (d). The forged product (d) is further conveyed into a heat treating chamber 2 to be heated by a heat source such as a burner and, after predetermined heat treatment, it is discharged from a discharge door 8 as a forged product (e).

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to save energy in heat treatment by using the sensible heat of a forged product immediately after hot forging for preheating in the next step of heat treatment.

Generally, hot forging involves a process in which the workpiece is heated to 1000@C or higher and then cooled in the atmosphere, so a large amount of thermal energy is wasted into the atmosphere.

In addition, heat treatments such as annealing, normalizing, and quenching, which are performed for the purpose of changing the structure of the steel, removing internal stress, and hardening, are normally carried out to change the temperature of steel from room temperature to a temperature that reaches the austenite region (mu03
Since it is heated to a temperature above the transformation point ($730-710@C), a large amount of ripening energy is required. However, in order to save energy during such heat treatment, the applicant has already developed a continuous M heat treatment apparatus that uses the thermal energy obtained in the cooling process of heat treatment to preheat the steel to be newly heat treated. Special public Akira! ≦−II≦l
Publication J, Tokukosho! It is disclosed in Publication No. 6-aIIttt. However, since it is difficult to obtain a high temperature with the thermal energy obtained in the cooling process of heat treatment, it may not be possible to reach a high temperature as the preheating temperature of the steel.

The present invention solves the above-mentioned drawbacks by utilizing the sensible heat of the forged product by hot forging for preheating the heat treatment process.

An embodiment of the present invention will be described below with reference to FIG.

Figure II1 is a horizontal sectional plan view of this furnace body, where 1 is the heat exchange chamber and 2 is the heat treatment chamber. Inside the heat exchanger 11!1, a heat radiation section 3 and a preheating section 4 are formed adjacent to each other.

5.6 indicates the charging door and extraction door of the heat dissipation section 3, 7 indicates the charging door to the preheating section 4, and the heat treatment chamber! is formed in a straight line with the preheating section 4. 8 is an extraction door for heat treatment w12. In addition, at the bottom of each of these chambers, there are glue rollers and bushings for transporting the forged products to be heated.

Appropriate conveyance means (not shown) such as a belt conveyor is provided. Further, a heat source such as a burner is provided on the inner wall of the heat treatment chamber 2. As shown in FIG. 2, the heat dissipation section 3 and the preheating section 4 are separated by a partition wall I that is in communication with the ceiling and bottom, and a circulation fan stirrup installed on the ceiling of the heat dissipation section 3 By rotating the gas (air) in the heat dissipation section 3,
and the gas in the preheating section 4 circulate as shown in the arrow.

However, in the present invention, immediately after hot forging, high temperature (de00-
/CoOO@C11) forgings island from the charging door S to the heat dissipation part 3
After the forged product C is air-cooled by blowing circulating air at a rate of 1 lO, it is taken out from the extraction door 6 to the outside of the heat exchange chamber, and the forged product C is continuously air-cooled until it reaches a temperature below the Mrl transformation point, that is, from 300°C to 300°C.
? Let it be 00@C. The temperature curve is shown in FIG. l
l! The forged product d is preheated by giving and receiving I-ri. The forged product d is further carried into the W-heat treatment chamber ez, where it is heated by a heat source such as a burner to a point Ao, f or above (lOO~deoo''C) K, and after a predetermined heat treatment is completed, it is extracted from the extraction door 8.

As explained in the *m examples above, the method for heat treatment of a hot forged product according to the present invention cools a high-temperature forged product immediately after hot forging by passing it through a heat radiating section of a heat exchange chamber, and then cools the forged product. Air cooling outside the heat exchange chamber to below the Mr1 transformation point,
After that, the forged product is passed through the preheating section of the heat exchange chamber, and the gas in the heat radiating section is circulated through the preheating section, so that the sensible heat of the forged product immediately after hot forging is used for preheating the next step heat treatment. Therefore, it is possible to preheat the forged product to a high temperature by effectively utilizing the ripening energy that was wasted in the past, resulting in a remarkable young fruit that can significantly reduce the thermal energy required for heat treatment.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a horizontal cross-sectional plan view of a furnace body, and FIG. 2 is a cross-sectional view taken along the line X--X. FIG. 3 is a diagram showing the temperature curve of the forged product. 1...Heat exchange chamber, 鵞...Heat treatment chamber, 3...
Heat dissipation part, 4... Preheating part, a-6... Forged product. Patent applicant: Daido Steel Co., Ltd.-6 (

Claims (1)

[Claims] A heat radiating part and a preheating part are formed adjacent to each other in a heat exchange chamber, a high-temperature forged product immediately after hot forging is passed through the heat radiating part to be cooled, and the forged product is then air-cooled outside the heat exchange chamber. Mr 1111
! The forged product is cooled down to a temperature below 100°C, and then the forged product is passed through the preheating section, and the gas from the heat dissipation section is circulated through the preheating section to remove the sensible heat of the forged product immediately after hot forging into the next heat. A method for heat treating a hot forged product, characterized in that the method is used for preheating a processing ring.