JPH08134532A - Heat treatment furnace - Google Patents

Abstract

PURPOSE: To prevent the lowering of the number of revolution of a cooling fan at the time of cooling by arranging a coolant introducing part at the position where the blowing coolant steam directly abuts on the blades of the cooling fan. CONSTITUTION: The cooling gas is introduced into a furnace to cool a treating material 5. Pressure in the furnace is increased by introducing the cooling gas and the overload is applied to the cooling fan 8. Cooling gas introducing passages 9b, 9c are arranged proximately to the blade part of the cooling fan 8. The blowing pressure of the cooling gas is worked in the direction accelerating the revolution of the blade part of the cooling fan 8 to cancel the sudden increase of the load on the cooling fan 8 caused by the increase of the pressure in the furnace. The number of revolution of the cooling fan 8 is not lowered, and the cooling gas in the furnace is sufficiently circulated and the treating material 5 can rapidly be cooled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment furnace having a cooling function for rapidly cooling a heat-treated product.

[0002]

2. Description of the Related Art In a heat treatment furnace, a furnace body is made of a heat insulating material, and a heater provided in the furnace heats a heat treatment space to heat a processed material. Also,
After the heat treatment, a forced cooling means is provided in order to rapidly cool the processed material and perform processing such as quenching. The forced cooling means normally introduces a refrigerant such as nitrogen gas into the furnace, and circulates the refrigerant by a cooling fan (motor drive) arranged in the furnace to uniformly cool the processed material. It is configured.

[0003]

Generally, this kind of heat treatment operation is performed while keeping the furnace body airtight.
The inside of the furnace is often evacuated to a reduced pressure. Therefore, when the cooling gas is introduced after the treatment, the pressure in the furnace rises sharply, the drive motor of the cooling fan is overloaded, and the rotation speed decreases, resulting in poor circulation of the cooling gas. There was a problem that the rapid cooling performance of the processed material deteriorates.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a heat treatment furnace excellent in quenching performance after heat treatment.

[0005]

In order to solve the above-mentioned problems, in the heat treatment furnace according to the present invention, the position where the cooling gas flow introduced into the furnace directly exerts a force on the blade of the cooling fan. The cooling gas introduction port is arranged at.

[0006]

According to the above construction, since the rotation of the cooling fan is promoted by the jetting force of the cooling gas, there is no fear that the drive motor of the cooling fan will be overloaded due to the rise in the pressure in the furnace. As a result, the rotation speed of the cooling fan is maintained in a steady state regardless of the rise in the furnace pressure.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of a conventional heat treatment furnace. A heat treatment space 3 closed by heat insulating walls 2, 2a and 2b is provided in a housing 1 of the heat treatment furnace. A heater 4 is provided inside the heat treatment space 3 and heats the object to be treated 5. During the heat treatment, the entire inside of the housing 1 including the heat treatment space 3 is exhausted by a normal method not shown. After the heating process is completed, the heater 4 is turned off,
The heat insulating walls 2a and 2b are separated from the heat insulating wall 2 by a driving means (not shown) such as an actuator, and the heat treatment space 3 is released. Cooling fan drive motor 7 allows cooling fan 8
Is rotated, the valve 9a of the cooling gas introduction passage 9 is opened, and the cooling gas (nitrogen gas or the like) is forcedly circulated in the housing 1 and the heat treatment space 3 to cool the processed material 5. At the same time, the heat exchanger 10 provides cooling. After cooling is completed, a door 1a and a heat insulating wall 2a are provided at one end of the housing 1 for transporting the processed material.
Is opened and the processed product 5 is taken out of the furnace.

In such a structure, as the cooling gas fills the inside of the furnace, the inside of the furnace is under high pressure (about 5 Kgf / cm ² (G)).
Therefore, the motor of the cooling fan, which rotates at a high speed of about 1800 (revolutions / minute), is overloaded and the number of revolutions drops by about 20%. As a result, the circulation of the cooling gas in the furnace is deteriorated during the introduction of the cooling gas, the cooling rate of the processed material is decreased, and the quenching may be defective, or the quality may be deteriorated.

FIG. 2 shows the structure of an embodiment of a heat treatment furnace according to the present invention. The figure shows a state during the cooling process, in which the heat insulating walls 2a and 2b are separated from the heat insulating wall 2 and the heat treatment space 3 is opened. The cooling gas introduced into the furnace from the cooling gas introduction passage 9 through the valve 9a is forcibly circulated by the cooling fan 8 to cool the processed material 5. When the cooling gas is introduced, the motor of the cooling fan is overloaded due to the pressure increase in the furnace, as in FIG.

By the way, in the heat treatment furnace according to the present invention, the cooling gas inlets 9b and 9c are arranged close to the blades of the cooling fan 8 so that the energy of the blowing of the cooling gas directly acts on the blades of the cooling fan. There is. According to FIG. 2, after the cooling gas has passed through the cooling gas introduction passage 9 and the valve 9a,
It is branched into the same pressure and blown out into the furnace through cooling gas inlets 9b and 9c arranged near the blades of the cooling fan 8.
At this time, the blowing pressure of the cooling gas directly acts on the blade portion of the cooling fan 8, and as a result, the cooling fan 8
A force acts in a direction to accelerate the rotation of the blades of the cooling fan, a sudden increase in the load of the cooling fan drive motor due to a pressure increase in the furnace can be prevented, and a high speed rotation can be maintained. Further, the circulation of the cooling gas is not delayed even during the introduction of the cooling gas, and the processed material 5 is rapidly cooled well.

In the above-mentioned embodiment, the cooling gas inlet is 9
Although the gas is branched into b and 9c, this is to make the ejection pressure of the gas applied to the cooling fan 8 uniform, and is to consider the rotational balance of the cooling fan 8. The present invention is not limited to this, and the number of branches is not limited.

There is no particular limitation on the type of the cooling fan. In the case of the axial flow fan, the cooling gas inlet may be arranged at a position where the jet pressure is applied in the forward rotation direction as shown in FIG. In the case of a fan, it may be arranged so as to blow out from the phase direction as shown in FIG.

Nitrogen gas was used as the refrigerant in this embodiment, but it is not particularly limited as long as it has a cooling effect.

[0015]

In the heat treatment furnace according to the present invention, even if the cooling fan drive motor is overloaded due to an increase in the pressure inside the furnace, the jet power of the cooling gas flow acts on the fan blades in the direction of promoting the rotation. As a result, the rotation speed of the cooling fan is maintained, the circulation of the cooling gas in the furnace is not delayed, and the processed material can be rapidly cooled. In particular, it is effective in the quenching treatment that requires rapid cooling after the heat treatment, and has an effect that the quality of the final product can be reliably improved as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a conventional heat treatment furnace.

FIG. 2 is a diagram showing an example of a heat treatment furnace according to the present invention.

FIG. 3 is a diagram showing another embodiment of the arrangement of the cooling gas inlet of the heat treatment furnace according to the present invention.

[Explanation of symbols]

 1. Casing 1a ... Door for carrying in processed material 2, 2a, 2b ... Insulation wall 3 ... Heat treatment space 4 Heater 5 Processed object 7 Cooling fan drive motor 8・ ・ ・ Cooling fan 9 ・ ・ ・ ・ ・ ・ ・ ・ Cooling gas introduction path 9a ・ ・ ・ ・ ・ ・ Valves 9b, 9c ・ ・ ・ ・ Cooling gas introduction port 10 ・ ・ ・ ・ ・····Heat exchanger

Claims (1)

[Claims] 1. A furnace main body surrounded by a heat insulating material, a heating means for heating the inside of the furnace main body, a refrigerant inlet for cooling the inside of the furnace main body, and a refrigerant circulating in the furnace main body. In the heat treatment furnace, the heat treatment furnace is provided at a position where the refrigerant flow blown from the refrigerant introduction port directly contacts the cooling fan blade.