JP3103905B2 - Furnace pressure adjustment method of batch type atmosphere furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a batch type atmosphere furnace which is effective for carrying out an atmosphere heat treatment method for supplying a raw material gas such as a hydrocarbon gas and an oxidizing gas directly into an atmosphere furnace without using a so-called shift furnace. The method of adjusting the furnace pressure of the above, the positive and negative pressure in the furnace at the time of closing the entrance door after charging the workpiece into the heating chamber and at the time of quenching of the workpiece quickly eliminates the It is characterized by preventing the occurrence of defective products due to oxidation of the atmosphere and disturbance of the atmosphere.

[0002]

2. Description of the Related Art Conventionally, in an atmosphere furnace used for gas carburizing of steel or the like, oxidation of an article to be treated due to invasion of outside air, generation of a defective article due to turbulence of the atmosphere, explosion, etc. are prevented, and a uniform hardened layer is formed. For this purpose, the furnace atmosphere should be 5 to 1 per hour.
A large amount of carrier gas, such as endothermic gas, which has been transformed in a transformation furnace so that it can be replaced about 0 times, is supplied. Had been exhausted from the exhaust.

[0003] However, an atmosphere heat treatment method in which a raw material gas such as a hydrocarbon gas is directly supplied into an atmosphere furnace without using a shift furnace (Japanese Patent Publication No. 1-387070, Japanese Patent Application Laid-Open No. SHO 59-5959).
In Japanese Patent Application Laid-Open No. -225711, the amount of gas supplied into the atmosphere furnace is extremely small, so that when the entrance door is closed or quenching, the inside of the furnace becomes a negative pressure and the outside air is sucked in from the exhaust, and compared with the heating chamber. Explosion hazard due to low temperature, or when the atmosphere in the heating chamber is disturbed due to the atmosphere in the oil tank going around to the heating chamber and the required processing effect cannot be obtained due to oxidation of the surface of the workpiece was there. Therefore, the present inventors have provided a furnace pressure adjusting device for an atmospheric furnace with an improved exhaust structure (see Japanese Utility Model Publication No. 1-17666).

[0004]

SUMMARY OF THE INVENTION In an atmosphere heat treatment method in which a raw material gas such as a hydrocarbon gas and an oxidizing gas are supplied directly into the atmosphere furnace, an article to be processed is charged into a heating chamber and an entrance door is closed. When the curtain burner is turned off, the inside of the furnace becomes a negative pressure, and the outside air is sucked from the exhaust. Further, when the curtain burner is not used, the inside of the furnace becomes positive pressure when the entrance door is closed after the article to be processed is charged.

[0005] Further, when the article to be treated is quenched, the pressure in the furnace becomes negative, and the outside air is sucked into the oil tank from the exhaust. And the outside air sucked into the oil tank oxidizes the article to be processed, and further circulates from the intermediate door portion to the heating chamber by convection to disturb the atmosphere of the heating chamber,
Oxidation and other required treatment effects may not be obtained in some cases. These problems have been largely solved by the use of the exhaust having the improved structure, but the present invention aims to solve the problem by physically preventing the inhalation of the outside air in addition to the mechanical solution. is there.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to directly feed a raw material such as hydrocarbon gas into an atmosphere furnace.
Gas atmosphere and oxidizing gas supply atmosphere heat treatment method
Then, when closing the entrance door after charging the workpiece into the heating chamber and quenching the workpiece, open the lid of the hole for the pusher fork of the entrance door, and at the same time, feed the raw material gas inlet into the heating chamber.
Introducing a raw material gas from preparative, then it is to sure to allow dissolution of furnace negative pressure which closes the pusher fork hole and to obtain a conditioning effect of resulting in the furnace atmosphere.

[0007]

According to the present invention, the article to be treated 15 in which the pressure inside the furnace is positive and negative
The lid 12 of the pusher fork hole 11 of the entrance door 4 is opened when the entrance door 4 is closed and the workpiece 15 is quenched after the charging, and the raw material gas inlet is simultaneously placed in the heating chamber 1.
Source gas is introduced from port 13 . Then , the pusher fork hole is closed in anticipation of the elimination of the positive and negative pressures in the furnace , so that the suction of the outside air from the exhaust 7 is prevented, and the outside air introduced into the heating chamber 1 is discharged into the heating chamber 1. Because of the high temperature, there is no danger of explosion due to combustion, and therefore the oxidation of the article to be treated 15 and the oil tank 2
The required processing effect can be obtained without disturbing the atmosphere in the heating chamber 1 inside the heating chamber 1.

[0008]

An embodiment of the present invention will be described below. FIG. 1 shows an example of an apparatus for implementing the present invention. In the figure, 1 is a heating chamber, 2 is an oil tank having quenching oil 3, 4 is an entrance door, 5 is an intermediate door, 6 is an exit door, 7 is the improved exhaust, 8 is a pusher, 9 is an exit conveyor, 10
Is a stirring fan, 11 is a hole for a pusher fork, 12 is a lid of the hole for a pusher fork 11, 13 is a raw material gas inlet, 14 is a curtain burner, and 15 is an article to be processed.

At the time of heat treatment of the article 15 to be treated, the entrance door 4 is first opened and the article 15 to be treated on the pusher 8 is loaded into the heating chamber 1. When the curtain burner 14 is used at the time of loading the article 15 to be treated, the inside of the furnace has a negative pressure,
When the curtain burner 14 is not used, the inside of the furnace has a positive pressure. Therefore, in the present invention, when the entrance door 4 is closed, the pusher 8 is raised to push up the lid 12 of the pusher fork hole 11 provided on the entrance door 4 to open it. As a result, the positive and negative pressures in the furnace are quickly restored, and the intake of outside air from the exhaust 7 is prevented,
Therefore, the oxidation of the article to be treated 15 is prevented, and the atmosphere in the oil chamber 2 is prevented from sneaking into the heating chamber 1, the disturbance in the atmosphere in the heating chamber 1 is prevented, and a required processing effect can be obtained. Things.

The lid 12 of the pusher fork hole 11 is opened not only when the article 15 is loaded, but also when the article 15 to be quenched becomes negative pressure in the furnace, or when the positive and negative pressures are applied to the furnace. Is carried out as appropriate in the event that Further, the lid 12 of the pusher fork hole 11 is immediately closed in anticipation of the cancellation of the positive and negative pressures. Further, if the raw material gas is introduced from the raw material gas inlet 13 at the same time when the lid 12 of the pusher fork hole 11 is opened, the negative pressure can be eliminated more quickly.

In the figure, reference numeral 16 denotes an opening / closing valve for communicating the inside and outside of the furnace. The opening / closing valve 16 measures the internal pressure of the furnace in advance in accordance with the actual processing cycle, and then controls the opening / closing by a timer or the like to be used for furnace pressure adjustment. Further, the opening and closing may be controlled in conjunction with the introduction of the raw material gas.

[0012]

According to the present invention, carbonization is directly performed in an atmosphere furnace.
Atmospheric heat to supply source gas such as hydrogen gas and oxidizing gas
In the processing method, since the positive and negative pressure in our Keru furnace in the atmosphere heat treatment is rapidly eliminated, without external air is sucked into the furnace, workpieces of oxidation by outside air intrusion, disturbance of the atmosphere of the heating chamber Is prevented, and as a result, the atmosphere in the furnace is adjusted, and the required processing effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an apparatus for performing the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating chamber 4 Entrance door 11 Hole for pusher fork 12 Cover for hole for pusher fork 13 Raw material gas inlet 15 Processed product

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiko Watanabe 2-6-26 Minowa-cho, Kohoku-ku, Yokohama-shi, Kanagawa Inside Dowa Mining Co., Ltd. Yokohama Plant (72) Inventor Kenichi Kitamoto Minowa-cho, Kohoku-ku, Yokohama, Kanagawa 2-6-6 No. 26 Dowa Mining Co., Ltd. Yokohama Plant (56) References JP-A-60-162179 (JP, A) JP-A 64-25700 (JP, U) JP-A 50-36806 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C21D 1 / 74,1 / 76 C23C 8/20 F27D 7/06

Claims (2)

(57) [Claims] 1. A raw material such as a hydrocarbon gas directly in an atmosphere furnace.
Gas atmosphere and oxidizing gas supply atmosphere heat treatment method
Open the lid of the pusher fork hole of the entrance door when closing the entrance door after loading the workpiece into the heating chamber and when quenching the workpiece, and then close it in order to eliminate the positive and negative pressure in the furnace. Furnace pressure adjusting method of a batch type atmosphere furnace characterized by the above-mentioned. 2. A raw material such as a hydrocarbon gas directly in an atmosphere furnace.
Gas atmosphere and oxidizing gas supply atmosphere heat treatment method
Te, open the lid of the pusher fork hole entrance door during quenching of closing time and the processing products of the inlet door after charging into the heating chamber to be treated products, raw <br/> from the source gas inlet to the heating chamber at the same time A method of adjusting the pressure in a batch-type atmosphere furnace, which comprises introducing a feed gas and then closing the pusher fork hole in anticipation of eliminating the positive and negative pressures in the furnace.