Heat treatment apparatus

Abstract: A heat treatment apparatus having a heat treatment furnace into which a hydrocarbon gas and an oxidization gas are introduced, wherein an outlet opening of a valve (30) through which a pusher (27) for pushing a work to be heat treated in the heat treatment furnace is movable is hermetically connected to a pusher insertion port formed on a wall (28) of the heat treatment furnace, and a seal box (31) is connected hermetically to an inlet opening of the valve (30), the pusher (27) being movable hermetically through the seal box (31). An elevator door (4) for opening and closing the heat treatment furnace has a guide pin (32) projected therefrom, and a jam (35) having an upper hook surface (33) for receiving the guide pin (32) thereon, the jam (35) being pivotally supported so that when the elevator door (4) is lowered, the elevator door (4) is moved by the jam (35) toward a seal surface of the opening of the heat treatment furnace. A guide groove (40) for guiding a pin (39) of an elevator door (4) in the vertical direction is curved at the lower portion thereof toward a seal surface of the opening of the heat treatment furnace. A seal packing (41) is provided on a seal surface of an opening of the heat treatment furnace, and a cooling pipe (42) is provided near the seal packing (41).

Description: This invention relates to a heat treatment apparatus, and more particularly relates to a heat treatment apparatus having a heat treatment furnace into which a hydrocarbon gas and an oxidization gas are introduced in order to heat treating metals. Fig. 2 shows a conventional batch furnace. In Fig. 2, a reference numeral 1 denotes a heating room, 2 denotes a cooling room, 3 an entrance door for said heating room 1, 3a an opening and closing port formed on said entrance door 3, 4 an intermediate door, 4a an outlet formed on said intermediate door 4, 5 an outlet door for said cooling room 2, 6 a cooling oil tank, 7 an excess air exhausting device, 8 a curtain flame to be ignited when the outlet door 5 is opened, 9 and 10 gas supply pipes, 11 and 12 valves provided in said gas supply pipes 9 and 10, respectively, and 19 an agitating fan. Fig. 3 shows a conventional continuous furnace and parts of the furnace which are similar to the corresponding parts of the furnace shown in Fig. 2. have been given corresponding reference numerals and need not be further described. A reference numeral 15 denotes a work-piece receiving room, 16 a door for the work-piece receiving room 15, 17 a CO 2 supply pipe, 18 is valve provided in said CO 2 supply pipe 17, and 20 a gas material supply pipe. In conventional cementation methods, a converted gas obtained from the conversion furnace is used as a carrier gas. Recently, in order to enhance the quality, and to reduce the treatment time and running cost, such a method that the conversion furnace is not used, but a hydrocarbon gas and an oxidizing gas are introduced directly into the furnace to carry out the metamorphism and the cementation in the furnace has been proposed. Further, such a cementation method that the carbon potential in the furnace atmosphere is increased and decreased repeatedly to reduce the treatment time is described in Japanese Patent Laid Open Nos. 128577/1980 and 49621/1994, Japanese Patent Publication Nos. 38870/ 1989, 51904/1994 and 21866/ 1987, for example. Fig. 4 shows a heat treatment furnace in said Japanese Patent Publication No. 21866/1987, wherein the entrance door 3 is opened at first, and then a work-piece is inserted into a vestibule 22 by a pusher 21. When the pusher 21 is returned, the entrance door 3 is closed and at the same time a door 24 is opened and then the work-piece is moved into the heating room 1 by a pusher 23. Next, the door 24 is closed and after the heating treatment is completed a door 26 is opened and the work-piece is moved by a pusher 25 into the cooling room 2. Then, the door 26 is closed and the temperature in the cooling room 2 is reduced, and at the same time the intermediate door 4 is opened and the work-piece is moved by a pusher 27 into the cooling oil tank 6. Then, the intermediate door 4 is closed to carry out the quenching. Next, the outlet door 5 is opened, and the work-piece is discharged to the outside, and then the outlet door 5 is closed. However, the conventional heat treatment apparatus for metals using an endothermic gas has such a defect that it is difficult to form a hermetical seal of the apparatus. US Patent Number 2,208,373 discloses a pusher rod assembly and housing therefor. An object of the present invention is to obviate the above defect of the conventional heat treatment apparatus. The invention provides a heat treatment apparatus according to claim 1 of the appended claims. Accordingly, the heat treatment apparatus comprises a valve having an outlet opening and an inlet opening through which a pusher for pushing a work-piece to be heat treated in said heat treatment furnace is movable, said outlet opening of the valve being hermetically connected to a pusher inserting port formed on a wall of said heat treatment furnace, and a seal box hermetically connected to said inlet opening of the valve, said pusher being movable hermetically through said seal box. According to preferred aspects of the invention, said valve is closed when said pusher is withdrawn therefrom, and is opened when said pusher is inserted thereinto. The foregoing and other objects, features, and advantages of the present invention will become apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings. Fig. 1 is a sectional side view of a hermetical seal of a pusher portion of a heat treatment apparatus in accordance with the present invention. Fig. 2 is a sectional side view of a conventional batch furnace. Fig. 3 is a sectional side view of a conventional continuous furnace. Fig. 4 is a sectional side view of the other conventional continuous furnace. Fig. 1 shows an improved hermetical seal for one 27 of the pushers 23, 25 and 27 shown in Fig. 4 In Fig. 1, a ball valve 30 and a seal box 31 are arranged in this order adjacent to the outer surface of a furnace wall 28 of the room 1 or 2 corresponding to a pusher insertion port 29 formed on the furnace wall 28. The pusher 27, for example, can be moved passing through said seal box 31, ball valve 30 and pusher insertion port 29 and inserted into the cooling room 2, for example. In this embodiment of the present invention, a work-piece to be heat treated is inserted into the room 2 by the pusher 27 in the state that the ball valve 30 is opened, then the pusher 27 is withdrawn from the room 2 through the ball valve 30 into the seal box 31, and then the ball valve 30 is closed. As stated above, according to the present invention, the work-piece can be inserted into the room 2 without breaking the hermetical seal of the room 2. While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims: A heat treatment apparatus having a heat treatment furnace into which a hydrocarbon gas and an oxidization gas are introduced, a pusher (27) for pushing a work-piece to be heat treated in said heat treatment furnace and a seal box (31), characterized in that said apparatus further comprises a valve (30) having an outlet opening and an inlet opening through which the pusher (27) is movable, said outlet opening of the valve (30) being hermetically connected to a pusher inserting port (29) formed on a wall (28) of said heat treatment furnace, and the seal box (31) being hermetically connected to said inlet opening of the valve (30), said pusher (27) being movable hermetically through said seal box (31). The heat treatment apparatus as claimed in claim 1, wherein said valve (30) is closed when said pusher (27) is withdrawn therefrom, and is opened when said pusher (27) is inserted thereinto.

Inventors: SHIMURA HIROSHI, TANNO YOSHIYUKI, YAMAGUCHI SIGEMI, SHIMURA, HIROSHI, TANNO, YOSHIYUKI, YAMAGUCHI, SIGEMI
Applicants: DOWA MINING CO, DOWA MINING CO., LTD.
Application year: 1996
Main classification: C21D9
IPC codes: F27B9, C23C8, F27D1, C21D1, F27D3, F27D23, C21D9