Treatment process for isothermal normalizing with exhaust heat of forgeable piece smithing

A technology of isothermal normalizing and treatment process, applied in the field of heat treatment of forgings, can solve the problems of increasing surface oxidation of forgings, increasing forging costs, not suitable for the production requirements of precision forgings, etc., to achieve stable product quality, balanced production, and reduced surface oxidation conditions Effect

Inactive Publication Date: 2009-05-13
JIANGSU AIRSHIP GEAR
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  • Description
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AI Technical Summary

Problems solved by technology

The disadvantage is that after the forgings are naturally cooled, they are reheated together and kept warm. The secondary heating of the forgings not only increases the forging cost, but also increases the surface oxidation of the forgings.
The isothermal normalizing process of the prior art is not suitable for the production requirements of precision forgings

Method used

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  • Treatment process for isothermal normalizing with exhaust heat of forgeable piece smithing

Examples

Experimental program
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Effect test

Embodiment 1

[0018] The isothermal normalizing treatment process is carried out by using the waste heat of forging forging, which is the process of carrying out normalizing treatment after the final forging of forgings. The forging in this embodiment is a car differential gear forged by precision hot die forging. The final forged forgings are sequentially sent to the heating furnace through the conveyor belt, and methanol is dripped into the heating furnace. The temperature of the heating furnace is controlled at 940±10°C. Under this temperature condition, the dripped methanol becomes gaseous methanol and fills the heating furnace. After the forging is kept warm for 160±20min, the forging is sent to the air-cooled room by the conveyor belt, and the forging is air-cooled to 610±10°C with nitrogen. After the forging is air-cooled, it is sent to the isothermal furnace filled with nitrogen by the conveyor belt. Keep warm for 170±10min at a furnace temperature of ±10°C, and then take it out of ...

Embodiment 2

[0020] The forging in this embodiment is the connecting gear of the automobile gearbox, and its material is the same as that in Embodiment 1, except that its structural size and volume are relatively smaller. The steps of the isothermal normalizing process using the residual heat of forging are the same as those in Example 1, but the values ​​of some process parameters are different. For example, the forgings enter the heating furnace at 860±10°C and are kept warm for 30±10min under the protection of methanol gas, and then sent to the air-cooled room by the conveyor belt, and the forgings are air-cooled to 710±10°C with nitrogen, and the forgings are air-cooled. The conveyor belt is sent into an isothermal furnace filled with nitrogen, and the forgings are kept at a furnace temperature of 710±10°C for 50±5min, and then cooled naturally after being released from the furnace. The technical effect of this embodiment is the same as that of Embodiment 1, and it can fully guarantee ...

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Abstract

The invention discloses a process for carrying out isothermal normalizing treatment through utilizing the residual forging heat of a forging piece. The process is carried out under the condition that the temperature of the residual heat of the forging pieces in final forging is between 950 and 1,050 DEG C. The forging pieces are transported to a heating furnace in sequence through a conveyor belt; the temperature of the heating furnace is controlled between 870 and 950 DEG C; in the atmosphere of the heating furnace filled with antioxidation gas, the forging pieces are kept at the temperature for 20 to 180 minutes; the forging pieces are transported to an air-cooled chamber in sequence through the conveyor belt; the forging pieces are subjected to air cooling to a temperature of between 600 and 720 DEG C through nitrogen gas; and the forging pieces are transported to an isothermal furnace filled with nitrogen gas in sequence through the conveyer belt, are kept at the furnace temperature of between 500 and 720 DEG C for 45 to 180 minutes, is discharged and is naturally cooled. The process needs no secondary heating, is assisted with the antioxidation gas to protect the surface of the forging pieces from producing an oxidation layer and feasibly protects the surface quality of the forging pieces in the normalizing treatment stage. The process is in particular suitable for the forging production of a precise hot mold.

Description

technical field [0001] The invention relates to a heat treatment process for a forging, in particular to a heat treatment process for isothermal normalizing by utilizing the residual heat of forging. Background technique [0002] Surface hardened steel hot die forgings are easy to form a surface hardened layer when they are freely cooled. The hardened layer on the surface of the forging is not conducive to subsequent machining. Necessary heat treatment is required before machining to eliminate the surface hardened layer. Isothermal normalizing treatment is to eliminate the surface hardened layer. One of the most effective process methods for layering. In the prior art, the forgings are placed in a normalizing furnace for isothermal normalizing treatment. The normalizing process is simple, the normalizing temperature and the holding time are easy to control uniformly, the normalizing quality is stable, and it can meet the requirements of subsequent machining. The disadvantag...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/28
Inventor 王欣林陆小兵
Owner JIANGSU AIRSHIP GEAR
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