JPS60200082A - Atmosphere heat treatment furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a furnace for heat-treating objects to be heated, such as steel materials, in an atmospheric gas.

Atmospheric heat treatment furnaces generally maintain the atmosphere in the furnace at a non-oxidizing gas such as N8 or a reducing gas such as CO1 (hereinafter referred to as atmosphere gas) and annealing or expediently heat the object in a non-oxidizing state. Purge chambers are provided in the charging and extraction sections to prevent air from entering the furnace during hot charging and extraction.

Conventionally, the purge chamber was generally supplied with N,
Gas or other inert gas is supplied to replace the air in the purge chamber with the gas.

However, the composition of the replacement gas supplied from the gas tank is usually different from the atmospheric gas inside the furnace, so the composition of the atmosphere inside the furnace fluctuates each time the object to be heated is charged or extracted. There was a drawback that the quality of the product became unstable.1 For example, if N1 gas was used as a replacement gas and N2 was used in the furnace.
In a heat treatment furnace where a gas containing CO (e.g. endothermic gas) in addition to gas is supplied or enriched with hydrogen chloride gas and the carbon potential inside the furnace is controlled by the amount, the airtight door of the purge chamber is When the furnace was opened, N2 gas flowed into the furnace, temporarily making it impossible to maintain the carbon potential and damaging the quality of the product.

The present invention aims to solve the above-mentioned drawbacks, and is intended to provide an atmospheric heat treatment furnace in which a purge chamber is provided in the charging section and the extraction section of the material to be heated. Atmospheric gas is sucked from the furnace body and stored in a surge tank, and at the same time, the atmosphere gas from the surge tank is supplied to the purge chamber at the time of charging and extracting the heated object to replace the gas in the purge chamber. It was designed to be used for personal purposes.

Next, one embodiment of the present invention will be described with reference to the drawings.

In the figure, 1 is a furnace body, 2.3 is a purge chamber located in the charging section and extraction section, 4 is a charging table, 5 is an extraction table, W is an object to be heated, and purge chamber 2 is a purge chamber located in the charging section and extraction section. It is provided with an airtight N6 on the side facing the outside of the furnace that faces the input table 4, and an airtightness Hi-7 on the side opposite to the inside of the furnace.

On the other hand, the purge chamber 3 includes an airtight door 8 on the side opposite to the inside of the furnace, and an airtight door 9 on the outside of the furnace and inside facing the extraction table 6.

Reference numeral 10 denotes a heat insulating door provided at the entrance of the furnace body 1 to block radiant heat within the furnace. The airtight doors 6.7, 8, 9 and the heat insulating door 10 are each suspended from a pulley U-15 in order to be retracted upward so as not to interfere with the object W passing through.

Note that the joint between the purge chamber 2 and the furnace body 1 and the joint between the furnace body 1 and the purge chamber 3 are airtightly shielded from the outside.
Pulley recognition, 13 is in compartment 16, pulley 14 is in compartment 1
They are placed in 7. A fixed amount of N and gas are constantly supplied into the furnace body 1 through piping, and the flow rate control discrimination is adjusted based on the signal from the CO2 concentration sensor 19, so that the atmospheric gas inside the furnace body 1 becomes a predetermined CO2 gas. Endothermic gas is supplied through pipe m to maintain the concentration.

22 is a compressor that sucks atmospheric gas from inside the furnace body 1, and n is a surge tank that stores the sucked atmospheric gas. A flow rate control valve and a cooler 5 are connected in series to the primary side of the compressor 17. The flow rate control discrimination prevents excessive suction by controlling the amount of atmospheric gas suction based on a signal from a pressure sensor provided within the furnace body 1 and maintaining the atmospheric gas pressure within the furnace body 1 at a predetermined value. The cooler δ rapidly cools the atmospheric gas sucked from inside the furnace body 1, thereby preventing the generation of soot. Piping is provided from the surge tank section to each purge chamber 2.3! .

A solenoid valve 9 provided with a groove and provided in each of the pipes 1.28.
．． 30 is opened, so that the atmospheric gas stored in the surge tank can be appropriately supplied to the purge chamber 2.3. 31 is an air supply pipe that supplies the insufficient amount of atmospheric gas from a separate tank (not shown) via an electromagnetic valve clearer when the atmosphere gas in the surge tank Z is insufficient; 35 is a vacuum pump connected to the purge chamber 2.3 through a solenoid valve 37, respectively.

Therefore, when charging the object W on the charging table 4 into the furnace l, the object W to be heated is carried into the purge chamber 2 by opening the air door 6 with the airtight n7 closed. After the airtight valve 6 is closed, the solenoid valve 6 is opened and the vacuum pump 3 is operated to exhaust the air inside the purge chamber 2 to the outside and reduce the pressure inside the purge chamber 2 to a vacuum state. After that, the solenoid valve 4 is opened to supply the atmospheric gas stored in the surge tank to the purge chamber 2, and the purge chamber z
The atmosphere is replaced with the atmospheric gas. And airtight fffi7
When opening, the heated object W in the purge chamber 2 is moved into the furnace body 1. In addition, when extracting the heated object W that has passed through the furnace body 1 and has undergone the intended heat treatment onto the extraction table 5, the airtight door 8
With ゜9 closed, open the solenoid valve I and operate the vacuum pump A to discharge the air in the purge chamber 3 to the outside, then open the solenoid valve (capital) to purge the atmospheric gas from the surge tank. The gas is supplied to the chamber 3 to replace the inside of the purge chamber 3 with atmospheric gas, and then the airtight door 8 is opened to move the heated object W in the furnace body 1 into the purge chamber 3. After closing the airtight door 8, the airtight door 89 is opened to extract the object W to be heated onto the extraction table 5.

In this way, the atmospheric heat treatment furnace of the present invention stores the atmospheric gas sucked from the furnace body in the surge tank and uses it to replace the gas in the purge chamber. Since the composition of the atmospheric gas is changed, fluctuations in the composition of the atmospheric gas inside the furnace during charging and extraction can be suppressed as much as possible. Therefore, it has the effect of stabilizing the quality of processed products.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view of a W-enclosed heat treatment furnace showing an embodiment of the present invention. W: Heat target, 1: Furnace body, 2.3: Purge chamber, 22: Compressor, 23: Surge tank. U...Flow control valve, 26...Pressure sensor. Patent applicant: Daido Steel Co., Ltd.

Claims (1)

[Claims] In an atmospheric heat treatment furnace in which a purge chamber is provided in the charging section and the extraction section of the material to be heated, atmospheric gas is sucked from the furnace body to the extent that the atmospheric gas pressure in the furnace body maintains a predetermined value, and the gas is transferred to a surge tank. Atmosphere heat treatment characterized in that the atmospheric gas in the surge tank is supplied to the purge chamber at the time of charging the object to be heated and at the time of extraction, respectively, and is used for gas replacement in the purge chamber. Furnace.