JP2003014376A - Roller hearth type vacuum furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep hermetic sealing, improve air cooling efficiency, and reinforce the strength of a sealing chamber by air cooling a conveyor roller in a roller hearth type vacuum furnace 3. SOLUTION: A furnace comprises a processing chamber 3 wherein a furnace structure 1 is formed with a heat insulating member 2 which structure includes at opposite ends thereof a gateway for conveyance a workpiece 10, and a metal furnace body 4 provided outside the furnace. Conveyance rollers 5 are provided in parallel in the direction of the gateway after passage through the processing chamber and the furnace body, and a sealing chamber 8 is provided so as to surround a protrusion section 7 of a conveyance roller protruded from an outer wall 6 of the furnace body with a bearing 9 provided in the sealing chamber for supporting the protruded portion 7, inside and outside which sealing chamber air cooling fins are provided. A shielding plate 13 is provided between the bearing and the outer wall while being separated from the outer wall, whereby the sealing is mounted through a flange having the air cooling fins. Further, a detection window 16 is mounted on the sealing chamber 8 to which mounting purge gas is supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller hearth type vacuum furnace that heats (heats, keeps, lowers, etc.) an object to be heat-treated in a vacuum state.

[0002]

2. Description of the Related Art Conventionally, a furnace body having inlets and outlets for loading and unloading an object to be processed is provided at both ends, and the furnace body is a processing chamber formed of a heat insulating material, and a metal provided outside the processing chamber. In the roller hearth type vacuum furnace consisting of a furnace main body made of, and a plurality of transfer rollers for transferring the object to be processed in the entrance / exit direction are arranged side by side in the entrance / exit direction through the processing chamber and the furnace main body,
The heat inside the furnace is transmitted through the transfer roller, or a bearing that axially supports the transfer roller by radiant heat from the outer wall of the furnace body, a sprocket that is connected to the shaft and transmits power from the drive unit,
The chain etc. is heated. Therefore, it is necessary to cool the transport roller. Further, in order to maintain the vacuum, it is necessary to hermetically seal the end portion of the transport roller.

Therefore, in Japanese Unexamined Patent Publication (Kokai) No. 2-89987, as shown in FIG. 3, in a furnace body 1 having an inlet for charging an object to be treated and an outlet for taking out an object to be treated, In a roller hearth type vacuum furnace in which a heating chamber 3 surrounded by a heat insulating wall 2 and having a heating device 40 therein is provided, and a transfer roller 65 for transferring an object to be processed is arranged in parallel from an inlet to an outlet, a transfer passing through the heating chamber 3 Each end of the shaft portion 66a, 66b protruding from the heat insulating wall 2 of the roller 65 and the furnace body 4 is rotatably supported by a bearing 67 arranged in an airtight casing 68 for ensuring vacuum, and heat insulating is performed. Between the wall 2 and the bearing 67, the shaft portion is fitted in a water-cooled jacket 69 having an inner cylindrical surface with a clearance, and this water-cooled jacket is fixed to the furnace body 4 so that cooling water can be supplied and drained.

The transport roller 65 is made of heat-resistant metal and is rotationally driven by a known drive mechanism. 53 is a shaft portion 66
Multiple sprockets attached to b (for example, 5)
The airtight casing 68 is provided so as to surround the ends 66a and 66b of the plurality of transport rollers along the direction of the entrance and exit. Also, 55 is one for each of the plurality of conveying rollers 65.
A drive shaft (idle roller) provided one by one protrudes to the outside of the airtight casing 68 via the sealing device 20 and is rotationally driven by a known drive mechanism, so that the plurality of transport rollers 65 are driven by the chain 17. It is driven by a chain. In the case of Japanese Patent Laid-Open No. 3-50491, one end of the carrying roller is further projected from the airtight chamber 68 through a seal to supply water into the carrying roller from the outside.

[0005]

However, since these are water-cooled types, there are problems of water leakage and a complicated structure. Therefore, in JP-A-3-96347 and JP-A-5-214432, heat radiation fins are provided between the outer wall of the furnace and the bearings for air cooling. However, heat radiation in a closed chamber provided on the outer wall of the vacuum furnace is performed. Has not been suggested or disclosed. In addition, the actual Kaihei 4-11074
In Japanese Patent No. 0, the cooling gas is supplied to the closed chamber to cool the bearing portion transport roll. However, the use of cooling gas is limited to cooling only.

In view of the above-mentioned problems, an object of the present invention is to provide a roller hearth type vacuum furnace which does not leak water and which has a simple structure and which cools a conveying roller by air cooling and maintains airtightness. Furthermore, it improves the air cooling efficiency,
To strengthen the strength of the airtight chamber.

[0007]

According to the present invention, there is provided a furnace body having inlets and outlets for loading and unloading an object to be processed, the furnace body comprising a processing chamber formed of a heat insulating material, Consisting of a metal furnace body provided outside the processing chamber,
In a roller hearth type vacuum furnace in which a plurality of transfer rollers for transferring the object to be processed are arranged side by side in the direction of the entrance through the processing chamber and the furnace main body, the transfer protruding from the outer wall of the furnace main body A metal airtight chamber formed on the outer wall so as to surround the projecting portion of the roller, and a bearing that axially supports the projecting portion of the carrying roller is provided in the airtight chamber for air cooling outside the airtight chamber. The above problems have been solved by providing a roller hearth type vacuum furnace characterized in that the fins are formed.

Since the airtight chamber is provided on the outer wall of the furnace main body and the bearings and the like are provided in the airtight chamber, the space volume in the airtight chamber is relatively large, and the cooling effect is exhibited only by providing the cooling fins outside the airtight chamber. can do. In order to improve the cooling efficiency, the fins may be further formed inside the airtight chamber (claim 2).

Further, between the bearing and the outer wall, a shield plate is provided which is separated from the outer wall and is joined to at least the upper side face and the lower side face of the airtight chamber, and the bearing is flange-attached to the shield plate. (Claim 3) The shield plate is separated from the outer wall, and is joined to the upper and lower side surfaces connected to the cooling fins of the airtight chamber, so that the radiant heat from the transport rollers and the furnace is effectively transmitted to the cooling fins. Further, since the shielding plate can be firmly joined to the airtight chamber, the bearing can be flange-mounted, so that the bearing strength is increased and the centering is easy.

It is more effective to provide air-cooling fins on the shielding plate as in the prior art (claim 4). Further, as in the conventional case, the airtight chamber can be integrated by being provided along the plurality of conveying rollers along the entrance / exit direction, and the structure is simpler (claim 5). Further, a detection window having a tubular body, one end of which is opened to the airtight chamber and a glass for a detection window provided at the other end is attached to the airtight chamber, and the tubular body portion By making it possible to supply the purging gas, the gas and the like can be effectively used for cleaning the detection window and cooling the airtight chamber (claim 5).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As an example of an embodiment of the present invention, a tray comprising a charging chamber, a temperature raising chamber, a carburizing diffusion chamber, a temperature lowering / holding chamber, a quenching chamber and an extraction chamber, and carrying iron alloy parts is transported. A case where the present invention is applied to a continuous vacuum carburizing furnace which is an example of a roller hearth type vacuum furnace for carrying out carburizing and quenching of iron alloy parts while being conveyed by rollers will be described with reference to the drawings. In each drawing, FIG. 1 is a conceptual view of a vertical cross section of a continuous vacuum carburizing furnace, and FIG. 2A is a cross sectional view of the temperature raising chamber of FIG.
(B) is a partial expanded sectional view of an airtight chamber. It should be noted that the same parts as those in the above-mentioned conventional example shown in FIG. In FIG. 1, the continuous vacuum carburizing furnace 21 includes a charging chamber 22, a temperature raising chamber 23, a carburizing diffusion chamber 24, a temperature lowering / holding chamber 25, a quenching chamber 26, and an extraction chamber 27, which are arranged in this order from the left. Vacuum seal door 28-32
It is divided by. Transfer rollers 5, 33 to 36 for transferring the iron alloy component 10 as the object to be processed by trays or baskets are provided between the chambers and between the chambers, and the trays and the like are movable from left to right when viewed in the drawing. ing. Further, since the vacuum seal doors 28 to 32 move up and down between the chambers, the transport roller 36 between the chambers is moved up and down by the cylinder 37 so that the transport rollers do not get in the way when the doors are closed. .

The loading chamber 22 is a chamber for preparing the loading of the next tray or the like into the temperature raising chamber after the completion of the treatment in the next temperature raising chamber 23. It is easy to carry in, and it is easy to load into the temperature raising chamber. Temperature raising chamber 23, carburizing diffusion chamber 24, temperature lowering / holding chamber 25
Is a furnace body 1 having inlets and outlets 11 for loading and unloading the object to be treated 10 provided at both ends, and a processing chamber 3 surrounded by a heat insulating material 2 is provided inside a furnace body 4 made of metal. . The temperature raising chamber 23 shown in FIGS. 1 and 2 is for raising the temperature of the object to be processed 10 in a vacuum, and a heating / exhausting port (not shown) in the processing chamber 3 and a heating device for heating vertically and horizontally. 40 (for example, a radiation tube (tube burner)) and the like are provided. The carburizing diffusion chamber 24 includes a carburizing gas supply / exhaust port (not shown) for performing the vacuum carburizing treatment and the diffusion treatment of the workpiece 10 in the processing chamber 3 and an electric heater for vacuum mainly for keeping the temperature above and below. A heating device 40 is provided. Since the temperature lowering / holding chamber 25 is a post-treatment of the object 10 to be carburized in the processing chamber 3, a supply / exhaust port (not shown) for supplying / discharging nitrogen gas for oxidation prevention, a temperature lowering / holding For cooling fan 43,
A heating device 40 such as an electric heater is provided. A cooling oil tank 45 is provided below the quenching chamber 26, and an object to be processed 10 is immersed in the oil tank by an elevator 46 to enable oil quenching. The extraction chamber 27 is provided with a lifter 47 so that the tray can be easily carried out.

The transport roller 5 is moved from the charging chamber 22 to the extraction chamber 27.
Although the heating chamber 23, the carburizing diffusion chamber 24, and the temperature lowering / holding chamber 25, which are heated and change from atmospheric pressure to a vacuum state, are exposed to high temperatures. Therefore, in the present invention, the temperature raising chamber shown in FIG. 2 will be described as an example. A plurality of transport rollers 5 for transporting trays and the like in the entrance / exit direction penetrate the processing chamber 3 and the furnace body 4 and are arranged in parallel in the entrance / exit direction. A metal airtight chamber 8 is provided on the outer wall of the furnace body along the direction of the entrance and exit so as to surround the projecting portions 7a, 7b of the plurality of transport rollers projecting from the outer wall 6 of the furnace body 4, and the outer side 8a of the airtight chamber and Fins 12 for air cooling are formed on the inner side 8b. Inside the airtight chamber 8, heat-resistant bearings 9 that pivotally support the projecting portions 7a and 7b of the transport roller 5 are provided. A shield plate 13 is provided between the heat-resistant bearing 9 and the outer wall 6 and is joined to the upper side surface 8c and the lower side surface 8d of the airtight chamber 8 and is separated from the outer wall. It is installed. The shield plate 1
It is advisable to provide air-cooling fins 15 for the shielding plate on the flange 14 that is integral with 3 to promote cooling of the shielding plate. Both airtight chamber ends 8
e has a tubular body 16a, and one end 16b of the tubular body
Is opened in the airtight chamber 8, and the detection window 16 provided with the detection window glass 16d is attached to the other end 16c. The light emitting portion and the light receiving portion of the photoelectric switch are arranged on a straight line outside the detection windows 16 on both sides. I do. A supply port 16e for supplying a purging gas is provided in the cylindrical main body 16a.

On the outer circumference of the carrying roller 5, there are provided a contact portion 5a with which the tray or the like comes into contact and a collar 5b for holding the lateral position of the tray or the like. Through holes 54 are formed on both sides of the heat insulating material 2 and the furnace main body 4 so as to fit the conveying rollers 5 in a gap. As shown in FIG. 2A, the right end 7 a is fitted into the heat resistant bearing 9, and the heat resistant bearing is attached to the shield plate 13 by the flange portion 14. The left end 7b penetrates through the shield plate 13 and is supported by the bearing 9, and is further provided with a sprocket 53.
The chain 17 is wound around the sprocket 53 so that it can be interlocked with the sprockets of other conveying rollers. The chain wrapped around multiple transport rollers further seals the airtight chamber 2
It is wound around an idle gear 55 penetrating with 0, and the idle gear 55 is connected to a reduction gear and a drive motor (not shown), and the drive motor allows a plurality of transport rollers to rotate.

According to this apparatus, the heat from the furnace 3 is the radiant heat from the furnace body 4 and the conductive heat from the conveying roller 5, but the heat from the furnace body 4 is shielded by the shield plate 13 and quickly. It is transmitted to the side surfaces 8c and 8d of the airtight chamber 8 and is radiated by the outer air-cooling fins 12. Further, the conduction heat is transmitted through the bearing 9 and is radiated from the shield plate 13, or is radiated from the fins 15 of the flange 14 and is transmitted from the fins in the airtight chamber 8 to the side surface of the airtight chamber 8 and is radiated by the outer air cooling fins 12.
Furthermore, the nitrogen gas supplied to prevent the detection window from becoming dirty is discharged into the furnace through the airtight chamber, so that the temperature in the airtight chamber is lowered. In addition, in this device, the furnace temperature is about 1000 ° C.
In this state, the temperature of the bearing was 175 ° C. This temperature was a temperature that a heat-resistant bearing (heat-resistant temperature of 400 ° C.) could sufficiently withstand. However, the air-cooling fins 15 of the shielding plate were not provided in the measurement.

In the above example, the case of the temperature raising chamber 23 is described, but it is also applicable to the carburizing diffusion chamber 24 and the temperature lowering / holding chamber 25 as appropriate. Although the shaft end of the conveying roller is enclosed in the airtight chamber, it may be protruded from the airtight chamber via a seal as disclosed in Japanese Patent Laid-Open No. 3-50491. Needless to say, the above-mentioned various heat countermeasures are appropriately selected according to the desired temperature. Further, a plurality of carburizing diffusion chambers may be provided. Further, the carburizing chamber and the diffusion chamber may be separately provided. Further, it is needless to say that the invention is not limited to the continuous vacuum carburizing furnace and can be appropriately applied without departing from the spirit of the invention.

[0017]

As described above, according to the present invention,
Fins for air cooling and shielding plates were installed inside and outside the sealed chamber, and the effective use of gas charge was used to prevent the temperature inside the sealed chamber from rising, so there is no risk of water leaks such as water cooling or rust. There is no simple structure to provide a cooling device. In addition, since the bearing is a flange type bearing with a shielding plate, the shaft bearing strength is strong, the distance between the shafts can be shortened, and a large number of transport rollers can be installed side by side, making it possible to transport heavy trays or small trays. It was

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional conceptual diagram of a continuous vacuum carburizing furnace which is an example of an embodiment of the present invention.

2A is a sectional view taken along line AA of the temperature raising chamber of FIG. 1, and FIG. 2B is a partially enlarged sectional view of a hermetic chamber of a continuous vacuum carburizing furnace which is an example of an embodiment of the present invention.

FIG. 3 is a cross-sectional explanatory view of a conventional roller hearth type vacuum furnace.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 furnace body, 2 heat insulating material, 3 processing chamber (heating chamber), 4 furnace body, 5 transfer rollers, 6 outer wall of furnace body, 7a, 7
b roller protrusion, 8 airtight chamber, 8a outer side of airtight chamber, 8b inner side of airtight chamber, 8c upper surface of airtight chamber, 8d
Lower side of airtight chamber, 9 bearings, 10 objects to be treated, 11
Doorway, 12 Air cooling fins, 13 Shield, 14
Flange, 15 fins for air-cooling shield plate, 16 detection window, 16a tubular body, 16b one end of tubular body, 1
6c Other end of cylindrical body, 16d Glass for bay window, 16e
Purging gas supply port, 21 continuous vacuum carburizing furnace (roller hearth type vacuum furnace)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeru Murakami             1-1 1-1 Fujikoshi Honmachi, Toyama City, Toyama Prefecture             Ceremony company Fujikoshinai (72) Inventor Sueo Takashima             1-1 1-1 Fujikoshi Honmachi, Toyama City, Toyama Prefecture             Ceremony company Fujikoshinai (72) Inventor Yoshiyuki Iwakami             1-1 1-1 Fujikoshi Honmachi, Toyama City, Toyama Prefecture             Ceremony company Fujikoshinai (72) Inventor Koichi Fukuda             Toyota Motor Corporation, 1 Toyota Town, Toyota City, Aichi Prefecture             Within the corporation (72) Inventor Akio Tamura             Toyota Motor Corporation, 1 Toyota Town, Toyota City, Aichi Prefecture             Within the corporation F-term (reference) 4K050 AA02 CC02 CG05 EA04

Claims (6)

[Claims] 1. A furnace body having inlets and outlets for loading and unloading an object to be processed provided at both ends, the furnace body being a processing chamber formed of a heat insulating material, and a metal provided outside the processing chamber. In a roller hearth type vacuum furnace comprising a furnace body made of, and a plurality of transport rollers for transporting the object to be processed in the inlet / outlet direction, which are arranged in parallel in the inlet / outlet direction through the processing chamber and the furnace body, A metal airtight chamber formed on the outer wall so as to surround the projecting portion of the transfer roller projecting from the outer wall of the furnace body is provided, and a bearing for axially supporting the projecting portion is provided in the airtight chamber. A roller hearth type vacuum furnace characterized in that fins for air cooling are formed on the outside. 2. The roller hearth type vacuum furnace according to claim 1, wherein the fins are further formed inside the airtight chamber. 3. A shield plate is provided between the bearing and the outer wall, the shield plate being separated from the outer wall and joined to at least the upper side face and the lower side face of the airtight chamber, and the bearing is flange-attached to the shield plate. Claim 1 or 2 characterized in that
Roller hearth type vacuum furnace described. 4. The roller hearth type vacuum furnace according to claim 3, wherein the shielding plate is provided with air cooling fins. 5. The roller hearth type vacuum furnace according to claim 1, wherein the airtight chamber is provided along a plurality of conveying rollers along an entrance / exit direction. 6. A detection window having a tubular body, one end of which is opened to the airtight chamber, and a detection window glass provided at the other end is attached to the airtight chamber. 6. The roller hearth type vacuum furnace according to claim 5, wherein the purging gas can be supplied to the main body.