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 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. This patents application is a divisional application of European Patent application No. 96309411. 5. Fig.6 shows a conventional batch furnace. In Fig. 6, 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. 7 shows a conventional continuous furnace and parts of the furnace which are similar to the corresponding parts of the furnace shown in Fig. 6 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.8. 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. US-A-3 262 407 discloses a means of hermetically sealing a furnace opening by lowering a door such that a set of wedges are encountered by rollers, the resulting downwards and simultaneous horizontal movement sealing the door in the opening. 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. 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 of the appended claims. The heat treatment apparatus comprises a lifting door for opening and closing an opening of said heat treatment furnace, a guide pin projected from said lifting door, and a jam having an upper hook surface for receiving said guide pin thereon, said jam being pivotally supported so that when said lifting door is lowered, said lifting door is moved by said jam toward a seal surface of an opening of said heat treatment furnace. In accordance with the preferred aspect given by claim 2, the heat treatment apparatus further comprises a second lifting door for opening and closing an entrance or outlet of said heat treatment furnace, a guide pin projected from said second lifting door, and a guide groove for guiding said pin in the vertical direction, wherein a lower end portion of said groove is curved toward a seal surface of an opening of said heat treatment furnace. According to the preferred aspect given by claim 3, a seal packing is provided on a seal surface of an opening of said heat treatment furnace, and a cooling pipe is provided near said seal packing. 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 an intermediate door portion of a heat treatment apparatus in accordance with present invention. Fig. 2 is a front view of the intermediate door portion. Fig.3 is an enlarged side view of a guide means for the door. Fig. 4 is an enlarged side view of a guide means for an entrance door of the heat treatment apparatus. Fig.5 is a front view of a seal portion of an opening of the heat treatment apparatus. Fig.6 is a sectional side view of a conventional batch furnace. Fig.7 is a sectional side view of a conventional continuous furnace. Fig. 8 is a sectional side view of the other conventional continuous furnace. Figs. 1 to 3 show one of the doors 4, 24 and 26, for example, the intermediate door 4 in the heat treatment apparatus of the present invention. The guide pins 32 are projected in the horizontal direction from both sides of the door 4, planar jams 35 each having an upper hook surface 33 for receiving said guide pin 32 and a lower portion pivotally supported by a frame 34 are provided, and the intermediate door 4 is moved up and down through chains 36 by a lifting device 37, so that when the intermediate door 4 is lowered in order to close the outlet of the room 2, the guide pins 32 of the intermediate door 4 are engaged with the upper portions of the hook surfaces 33 of the jams 35 and guided along the hook surfaces 33 leftwards in Fig.3. After the guide pins 32 are reached to the bottom portions of the hook surfaces 33 of the Jams 35, the jams 35 are rotated In the counter-clockwise direction as shown by a double dot -and- dash line in Fig.3, so that the surface of the intermediate door 4 is pressed to the seal surface of the room 2. The intermediate door 4 does not contact with the seal surface of the room 2 in the course of lowering and lifting, and only when the intermediate door 4 is reached to the lowest position, the intermediate door 4 is In contact with the seal surface of the room 2, so that the seal surface is never damaged when the door is moved up and down. Fig.4 shows one of guide grooves 40a and corresponding guide surfaces 40b formed on a frame 38 for the entrance door 3 or the outlet door 5. The upper and lower guide pins 39a and 39b are projected in the horizontal direction from both sides of the door, and guided by guide grooves 40a and guide surface 40b, respectively. Each of said grooves 40a and guide surfaces 40b is curved at the lower portion thereof toward the seal surface of the room 1 or the room 2. The door does not contact with the seal surface of the heating room 1 or cooling room 2 in the course of lowering and lifting, and only when the door is reached to the lowest position, the door is brought into contact with the seal surface, so that the seal surface is never damaged when the door is moved up and down. Fig.5 shows seal packing 41 arranged on the seal surface of the heating room 1. The seal packing 41 is surrounded with an air pipe 42 into which a cooling air is introduced so as to cool the seal packing 41. In this manner the seal packing can be prevented from being deteriorated. 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, characterised in that the apparatus further comprises a lifting door (4,24,26) for opening and closing an opening of said heat treatment furnace, a guide pin (32) projected from said lifting door (4), and a jam (35) having an upper hook surface (33) for receiving said guide pin (32) thereon and a lower portion, said lower portion of said jam (35) being pivotally supported so that when said lifting door (4) is lowered said guide pin (32) engages with said upper hook surface (33) and is guided to said lower portion of said jam (35), the jam (33) then rotating about the pivotal support such that the lifting door (4) is moved by said jam (35) toward a seal surface of the opening of said heat treatment furnace. The heat treatment apparatus as claimed in claim 1, further comprising a second lifting door (3 or 5) for opening and closing an entrance or outlet of said heat treatment furnace, an upper guide pin (39a) and a lower guide pin (39b) projected from said second lifting door (3 or 5), and a guide groove (40a) and a guide surface (40b) for guiding said pins (39a and 39b) in the vertical direction, wherein respective lower end portions of said guide groove (40a) and guide surface (40b) are curved toward a seal surface of said entrance or outlet of said heat treatment furnace. The heat treatment apparatus as claimed in claim 1 or 2 further comprising a seal packing (41) provided on a seal surface of an opening of said heat treatment furnace, and a cooling pipe (42) is provided near said seal packing (41).

Inventors: SHIMURA HIROSHI, TANNO YOSHIYUKI, YAMAGUCHI SIGEMI, SHIMURA, HIROSHI, TANNO, YOSHIYUKI, YAMAGUCHI, SIGEMI, Shimura, Hiroshi, Dowa Mining Co., Ltd., Tanno, Yoshiyuki, Dowa Mining Co., Ltd., Yamaguchi, Sigemi, Dowa Mining Co., Ltd.
Applicants: DOWA MINING CO, DOWA MINING CO., LTD.
Application year: 1996
Main classification: C21D9
IPC codes: C21D9, F27B9