JP3948038B2 - Furnace core tube type heat treatment furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a batch-type furnace core tube heat treatment furnace suitable for main firing ceramic products.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a furnace core tube heat treatment furnace for firing ceramics has a structure shown in FIGS. In this heat treatment furnace, a furnace chamber 2 is formed inside a furnace body 1 made of a refractory material, and a furnace core tube 3 made of a refractory material is installed so as to penetrate the furnace chamber 2 in the horizontal direction. In the furnace core tube 3, a jig W such as a basket containing a workpiece is put. As the heater 4 for heating the workpiece, a rod-shaped or module type heater is used, and is disposed around the core tube 3. The workpiece in the jig W put into the furnace core tube 3 is fired by heating from the outside of the furnace core tube 3. Note that a sensor 5 such as a thermocouple for detecting the temperature in the furnace chamber 2 is attached to the furnace body 1.
[0003]
[Problems to be solved by the invention]
In the conventional heat treatment furnace as described above, since the object to be processed is fired in a fixed state, there is a drawback that the temperature variation in the object to be processed is large. Further, in the heat treatment furnace of the atmosphere firing method by closing the end of the furnace core tube 3, the supply of the atmosphere gas is a fixed point supply to the object to be processed. It was the cause.
[0004]
Therefore, an object of the present invention is to provide a furnace core tube type heat treatment furnace that can solve the above-mentioned problems.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a furnace tube type heat treatment furnace of the present invention is composed of a refractory, a furnace body in which a furnace chamber is formed, a vertical body disposed in the furnace chamber in the vertical direction and closed at the upper end. Type furnace core tube, a heater that is disposed in the furnace chamber and on the outer periphery of the furnace core tube, a stage that supports the furnace core tube, a stage that supports the object to be processed, and a stage that is moved up and down to move the object to be processed A lifting device that is inserted into the furnace core tube from below and a rotary drive device that rotationally drives the stage in a certain direction . The furnace body is divided into a plurality of parts in the horizontal direction, and each divided furnace body part is horizontally arranged. An opening / closing drive device for opening and closing is provided, and the heaters are individually attached to the furnace body portions .
[0006]
Heat of the heater is transmitted to the object to be processed disposed inside through the furnace core tube. The object to be processed is placed on the stage, and the stage is rotationally driven in a certain direction by the rotation driving device, so that it is exposed to uniform heating and a uniform atmosphere, and uniform heat treatment is possible. When the heat treatment is completed, the stage can be lowered, and the workpiece can be easily taken out by pulling it out below the furnace core tube.
[0007]
Immediately after the heat treatment, if the stage is lowered and the object to be processed is pulled out below the furnace core tube, the object to be processed is rapidly cooled, causing various problems. Therefore, although it waits for cooling in a furnace core tube, the inside of a furnace core tube is hard to be cooled, and the baking time until taking out a to-be-processed object was long. Therefore, it is desirable to provide an opening / closing drive device that divides the furnace body into a plurality of parts in the horizontal direction and opens and closes the divided furnace body parts in the horizontal direction. In this case, since the core tube can be cooled in a short time by opening the furnace body, the heat treatment time can be shortened. In addition, it is desirable to attach a heater to each divided furnace body part. Thereby, when the furnace body is opened, the heater is opened integrally with the furnace body, so that the cooling effect of the furnace core tube is improved and interference between the heater and the furnace body can be prevented.
[0008]
It is desirable to dispose a frame that supports the upper and lower ends of the furnace core tube outside the furnace body, and to attach an opening / closing drive device that opens and closes each furnace body part in the horizontal direction. As an open / close drive device, a guide rail fixed to the frame and slidably guiding each furnace body part, a ball screw shaft that is rotatably attached to the frame and has a reverse screw formed at the middle part, and each furnace It is desirable to include a nut provided on the body portion and screwed into each screw portion of the ball screw shaft and a driving actuator for driving the ball screw shaft. In this case, when the ball screw shaft is driven, each furnace body part opens and moves in the opposite direction with the furnace core tube in between, so that the opening speed is increased and the distance between each furnace body part and the furnace core tube is increased. It becomes equal and uniform cooling is obtained.
[0009]
It is desirable to attach a plurality of heaters to the furnace body in the vertical direction, and to fix a heat-resistant partition wall member inserted in the vertical gap of each heater on the inner wall of the furnace body. In this case, interference between the heaters arranged in the vertical direction can be prevented by the partition member, and heating can be performed independently.
[0010]
When a frame that supports the upper and lower ends of the furnace core tube is arranged outside the furnace body, a top plate that closes the upper end of the furnace core tube can be displaced vertically via spring means at the upper end of the frame. It is desirable to install. As a result, the furnace core tube can always be closed and the vertical extension of the furnace core tube can be absorbed by the spring means.
[0011]
It is desirable to attach a gas supply pipe for supplying atmospheric gas into the furnace core pipe and a gas discharge pipe for discharging the gas in the furnace core pipe to the top plate. As a result, even if the core tube expands and contracts in the vertical direction, gas supply and exhaust into the core tube can be reliably performed.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
3 to 8 show an example of a batch heat treatment furnace according to the present invention.
This heat treatment furnace is provided with a square furnace body 10 at the top, and the furnace body 10 is made of a refractory material such as ceramic fiber. 4 and 5, the furnace body 10 is divided into two left and right furnace body parts 10 a and 10 b, and each furnace body part 10 a and 10 b is driven to open and close by an opening / closing drive device 40 described later. A furnace chamber 11 is formed inside the furnace body 10, and a vertical furnace core tube 12 made of a refractory is disposed so as to penetrate the furnace chamber 11 vertically. A plurality of bar heaters 13 (see FIG. 4) are horizontally passed through and fixed to the furnace body portions 10a and 10b so that the furnace core tube 12 can be heated from the periphery. A temperature sensor 14 such as a thermocouple is fixed to one furnace body portion 10 a or 10 b, and the tip of the sensor 14 is inserted into the furnace chamber 11.
[0013]
A frame 15 that supports the upper and lower ends of the furnace core tube 12 is disposed outside the furnace body 10. The lower end portion of the furnace core tube 12 is sealed by being placed on a hearth plate 16 constituting the bottom plate of the frame 15 through a heat resistant sealing material 17 such as a silicon plate as shown in FIG. . Further, a heat insulating material 18 is fitted to the upper end portion of the furnace core tube 12, and an atmosphere gas supply pipe 19 and an exhaust pipe 20 are inserted so as to penetrate the heat insulating material 18 vertically. The upper ends of the gas supply pipe 19 and the gas exhaust pipe 20 are fixed to a top plate 21 made of a heat-resistant metal. The top plate 21 is inserted through a shaft 22 projecting from the upper end surface of the frame 15 as shown in FIG. 7 so as to be movable up and down, and a spring 23 is disposed between the head of the shaft 22 and the top plate 21. Thus, the top plate 21 is in pressure contact with the upper end of the furnace core tube 12. Between the top plate 21 and the upper end of the furnace core tube 12, a heat-resistant sealing material 24 made of a silicon O-ring or a plate is interposed. As described above, since the furnace core tube 12 and the top plate 21 are in pressure contact with each other via the spring 23, a seal corresponding to the elongation of the furnace core tube 12 due to heating becomes possible. Atmospheric gas leakage can be reliably prevented.
[0014]
As shown in FIG. 3, an elevating lifter (elevating device) 30 is provided below the frame 15. The lifter 30 is provided on the structure 31 that supports the frame 15, the support 32 that is slidably guided by the structure 31, the stage 33 on which the workpiece W is placed, and the stage 33. An elevating drive source 34 such as a hydraulic cylinder that elevates and lowers through the support 32 is provided. By driving the raising / lowering drive source 34, the stage 33 is raised, and the workpiece W is introduced into the furnace core tube 12 from below as indicated by a two-dot chain line in FIG. Actually, the workpiece W is heat-treated in a state of being housed in a jig such as a basket. The stage 33 includes a rotating table 33a on which the workpiece W is placed and a stationary table 33b that does not rotate. The rotating table 33a is rotationally driven in one direction by a rotation driving device 35 at a constant speed. The rotation drive device 35 of this embodiment includes a pulley or sprocket 36 connected to a turntable 33a, a motor 37 fixed inside the support 32, a pulley or sprocket 38 connected to the rotating shaft of the motor 37, and the pulley Alternatively, it is composed of a belt or chain 39 wound around the sprockets 36 and 38.
[0015]
As shown in FIG. 8, the opening / closing drive device 40 includes a pair of fixed guide shafts (guide rails) 41 and 42 that are stretched across the frame 15 in the horizontal direction, and a pair of ball screw shafts 43 and 44. . Mounting plates 45 and 46 are fixed to the lower portions of the furnace body portions 10a and 10b, respectively, and a plurality of sliders 47 and 48 slidable with respect to the guide shafts 41 and 42 are fixed to the mounting plates 45 and 46, respectively. ing. Therefore, each furnace body part 10a, 10b can be horizontally moved smoothly. Further, nuts 49 and 50 that are screwed onto the ball screw shafts 43 and 44 are fixed to the mounting plates 45 and 46. The ball screw shafts 43 and 44 are reverse screws with the central portion as a boundary, and the nuts 49 and 50 of the furnace body portions 10a and 10b are screwed into the screw portions. Therefore, when the ball screw shafts 43 and 44 are rotated in one direction, the furnace body portions 10a and 10b move in the closing direction, and when rotated in the opposite direction, the furnace body portions 10a and 10b move in the opening direction. The two ball screw shafts 43 and 44 are coupled to rotate synchronously via sprockets 51 and 52 and a chain 53. Another sprocket 54 is fixed to one ball screw shaft 43, and this sprocket 54 is connected to a motor 57, which is a driving actuator, via a chain 55 and a sprocket 56. The motor 57 is fixed to the frame 15. When the motor 57 is driven, the two ball screw shafts 43 and 44 rotate in the same direction and at the same speed, so that the furnace body portions 10a and 10b can be opened and closed.
[0016]
As described above, the opening / closing drive device 40 is not limited to the one using the ball screw shafts 43 and 44 having a reverse screw configuration with the central portion as a boundary, and may use the ball screw shafts 43 and 44 having uniform screws. In this case, since one furnace body part is fixed and only the other furnace body part opens and closes, the opening and closing speed of the furnace body part is slow, and the furnace core tube in the open state and the left and right furnace body parts The distance becomes uneven. On the other hand, when the ball screw shafts 43 and 44 having the reverse screw configuration as in the embodiment are used, when the ball screw shafts 43 and 44 are driven, the furnace body portions 10a and 10b sandwich the furnace core tube 12 therebetween. Since the opening movement is performed by the same distance, the distances between the furnace body portions 10a and 10b and the furnace core tube 12 become equal, uniform cooling performance is obtained, and the opening speed is increased.
[0017]
Next, the operation of the heat treatment furnace having the above configuration will be described.
At the start of heat treatment, first, the stage 33 is lowered by the lifter 30 and the workpiece W is placed on the rotating table 33a of the stage 33, and then the stage 33 is lifted to bring the workpiece W into the furnace core tube 12. (Indicated by a two-dot chain line in FIG. 3). At this time, it is desirable that the fixing base 33b of the stage 33 is brought into close contact with the lower end portion of the furnace core tube 12 or the hearth plate 16 and the lower end side of the furnace core tube 12 is sealed. Next, the rotary table 33a of the stage 33 is rotated in a certain direction by the motor 37, the heater 13 is energized to heat the furnace core tube 12 to a predetermined temperature, and the atmospheric gas is supplied from the gas supply pipe 19 to the furnace core tube 12. Supply and heat-treat the workpiece W. The exhaust gas generated during the heat treatment is discharged from the gas exhaust pipe 20. Of course, the heat treatment is performed with the furnace body 10 closed.
[0018]
As described above, since the workpiece W is heat-treated while being rotationally driven by the stage 33, the workpiece W is uniformly heated even if there is some temperature variation in the circumferential direction of the furnace core tube 12, and the furnace W Since the atmospheric gas supplied into the core tube 12 is evenly touched, the heat treatment conditions are made uniform and heat treatment with little variation can be performed.
[0019]
When the heat treatment is completed, the energization to the heater 13 is stopped and the supply of the atmospheric gas is also stopped. And the motor 57 of the opening / closing drive apparatus 40 is driven, and the furnace body parts 10a and 10b are opened right and left. As a result, the furnace chamber 11 is opened to the outside air, the radiant heat from the furnace body 10 and the heater 13 to the furnace core tube 12 is reduced, and the furnace core tube 12 is rapidly cooled. In addition, since the to-be-processed object W in the furnace core tube 12 is sealed inside the furnace core tube 12, the temperature gradually decreases and the quality of the to-be-processed object W is not deteriorated.
[0020]
When the internal temperature of the furnace core tube 12 falls below a predetermined temperature, the stage 33 is lowered by the lifter 30 and the workpiece W is taken out below the furnace core tube 12. Thereafter, the workpiece W is taken out from the stage 33 and conveyed to the next step, while the untreated workpiece W is placed on the stage 33 and subjected to the next heat treatment.
[0021]
In the case of using an integrally structured furnace body as in the conventional case, it is necessary to wait for the furnace body to naturally cool after the heat treatment is completed. On the other hand, if the opening of the furnace bodies 10a and 10b as described above and the removal of the object to be processed by the lowering of the stage 33 are used in combination, the firing time can be shortened to about 2 hours. As a result, the heat treatment cycle could be shortened and the production efficiency could be greatly improved.
[0022]
FIG. 9 shows a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
In this embodiment, a plurality of heaters 13 are attached to the furnace body 10 in the vertical direction, and a heat-resistant partition wall member 60 inserted into the vertical gap of each heater 13 is fixed to the inner wall of the furnace body 10. is there. Each heater 13 is independently energized and controlled by an individual control circuit. In this embodiment, among the heaters 13 provided vertically in four stages, the partition wall member 60 is provided between the first stage and the second stage from the top, and between the third stage and the fourth stage. A partition wall member 60 may be provided between all the stage heaters 13.
[0023]
By fixing the partition wall member 60 to the furnace body 10 in this way, interference between the heaters 13 in the vertical direction in the furnace can be suppressed, and each part of the furnace core tube 12 can be heated independently.
[0024]
The present invention is not limited to the above embodiments.
For example, the furnace body is not limited to the one divided into left and right parts, but may be another divided structure such as four parts, or may be an integrated structure.
As shown in FIG. 4, the heater is not limited to a rod heater disposed in the horizontal direction of the furnace body, but may be a plurality of rod heaters disposed in the longitudinal direction of the furnace body. Any shape such as a U-shape may be used.
The guide shaft and the ball screw shaft are used as the opening and closing drive device for opening and closing the left and right furnace body portions, but the opening and closing drive device may be driven by a known drive device such as a cylinder. However, when a ball screw mechanism is used, there is little vibration during the opening and closing operation, and a smooth operation is possible.
[0025]
【The invention's effect】
As is clear from the above description, according to the present invention, the workpiece is placed on the stage, and the stage is heat-treated while being rotationally driven in a fixed direction by the rotation driving device. Even if there is some variation in temperature and variation in atmospheric gas, the temperature and atmosphere for the object to be processed are made uniform, and heat treatment under uniform conditions becomes possible.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an example of a conventional furnace core tube heat treatment furnace.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is a longitudinal sectional view of an example of a furnace tube type heat treatment furnace according to the present invention.
4 is a cross-sectional view taken along line BB in FIG.
FIG. 5 is a longitudinal sectional view showing the opening / closing operation of the furnace body.
FIG. 6 is an enlarged cross-sectional view showing the structure of the lower end portion of the furnace core tube.
FIG. 7 is a cross-sectional view showing the structure of the upper end portion of the furnace core tube.
FIG. 8 is a perspective view of the upper part of the heat treatment furnace according to the present invention.
FIG. 9 is a sectional view of another embodiment of the heat treatment furnace according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Furnace 10a, 10b Furnace part 11 Furnace chamber 12 Furnace core pipe 13 Heater 15 Frame 19 Gas supply pipe 20 Gas exhaust pipe 21 Top plate 30 Lifting lifter (lifting device)
33 Stage 35 Rotation drive device 40 Opening / closing drive device 41, 42 Guide shaft 43, 44 Ball screw shaft 49, 50 Nut 57 Motor (drive actuator)
W Workpiece

Claims (5)

A furnace body made of a refractory and having a furnace chamber formed therein, a vertical furnace core tube vertically arranged in the furnace chamber and closed at the upper end, and disposed in the furnace chamber and on the outer periphery of the furnace core tube A heater that heats the furnace core tube, a stage that supports the object to be processed, an elevating device that moves the stage up and down, and throws the object to be processed into the furnace core tube from below, and the stage is rotationally driven in a certain direction. A rotational drive device,
The furnace body is divided into a plurality of parts in the horizontal direction, an opening / closing drive device is provided for opening and closing each divided furnace body part in the horizontal direction, and the heaters are individually attached to the furnace body parts. Furnace core tube type heat treatment furnace characterized by A frame that supports the upper and lower ends of the furnace core tube is disposed outside the furnace body, and the open / close drive device is fixed to the frame and guides each furnace body part slidably, A ball screw shaft that is rotatably attached to the frame and has a reverse screw formed at the middle part, a nut that is provided in each furnace body part and that engages with each screw part of the ball screw shaft, and drives the ball screw shaft The furnace core tube heat treatment furnace according to claim 1 , further comprising a driving actuator for performing the operation. A plurality of heaters are attached to the furnace body in the vertical direction, and a heat-resistant partition member inserted in the vertical gap of each heater is fixed to the inner wall of the furnace body. The furnace core tube type heat treatment furnace according to claim 1 or 2 . A frame that supports the upper and lower ends of the furnace core tube is disposed outside the furnace body, and a top plate that closes the upper end of the furnace core tube is vertically attached to the upper end portion of the frame via spring means. The furnace core tube heat treatment furnace according to any one of claims 1 to 3 , wherein the furnace core pipe heat treatment furnace is mounted so as to be displaceable. The furnace core according to claim 4 , wherein a gas supply pipe for supplying atmospheric gas into the furnace core pipe and a gas discharge pipe for discharging gas in the furnace core pipe are attached to the top plate. Tube heat treatment furnace.

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