JP5429534B2 - Pusher type continuous firing furnace - Google Patents

Description

  The present invention relates to a pusher-type continuous firing furnace, and more specifically, a pusher-type continuous firing in which the firing atmosphere can be switched in a short time during firing, enabling high-precision gas atmosphere control and reducing gas consumption. Related to the furnace.

  The pusher furnace is a furnace for continuously firing processed products (sintered products) such as ceramic electronic components, and as shown in FIG. 1, silicon carbide for heating the processed products placed on the base plate. It consists of a furnace body 1 provided with a heating element 7 such as a heating element, and the processed product placed on the base plate is conveyed from the processed product inlet 3 to the right of the furnace main body 1 by the pusher 2 and taken out from the processed product outlet 4. It is configured. 5 is an inlet for the atmospheric gas in the furnace, and 6 is an outlet for the atmospheric gas in the furnace.

  In a general pusher furnace, a gas for forming a predetermined furnace atmosphere is introduced into the furnace and the processed product is fired. In recent years, some ceramic parts have achieved desired characteristics. Therefore, it is necessary to change the firing atmosphere at each temperature stage during firing.

  In response to such a requirement, for example, the furnace main body is divided into a plurality of zones along the conveyance direction of the processed product, a partition having a gas curtain structure is provided between each zone, and the gas curtain exists before and after the partition. A continuous atmosphere furnace that separates the atmosphere has been proposed. In this proposal, the gas curtain gas, the supply of the atmosphere gas supplied into the furnace, and the discharge of the exhausted gas are balanced. Therefore, good results are not necessarily obtained, gas diffusion to other zones and gas introduction cannot be completely prevented, and high-precision gas atmosphere adjustment cannot be performed.

  In addition, each processed product is housed in a fired sheath whose interior atmosphere can be adjusted independently, the fired sheath is placed on a belt, and the belt is moved to transport the fired sheath to a position corresponding to a predetermined heating means. The atmosphere gas supply nozzle and the atmosphere gas discharge nozzle are connected to the firing sheath at the predetermined position, and the atmosphere in the firing sheath is controlled to a predetermined atmosphere and heated to a predetermined temperature by the heating means. Then, the atmosphere gas supply nozzle and the atmosphere gas discharge nozzle are removed from the firing sheath, the belt is moved, and the firing sheath is transported to a position corresponding to the next heating means. The operation of connecting the supply nozzle and the atmosphere gas discharge nozzle to the firing sheath, controlling the atmosphere in the firing sheath to a predetermined atmosphere, and heating the processing product to a predetermined temperature by a heating means is performed. Ri returns, baking apparatus has been proposed which is to perform firing of the ceramic component by changing the temperature and atmospheric conditions in stages.

  However, this firing apparatus is a tact feed method in which the firing sheath in the furnace is sequentially fed to a predetermined position, and the atmosphere gas is not supplied until it is completely sent to the next position. Since the supply nozzle and the gas discharge nozzle are attached to and removed from the firing sheath, there is a problem in maintaining airtightness, and the firing sheath is intermittently conveyed, and there is a problem in terms of processing efficiency.

JP-A-11-281259 JP-A-8-26835

  The present invention has been made to solve the above-described conventional problems in the pusher furnace, and its purpose is to switch the firing atmosphere in a short time during continuous firing of the processed product, and to provide a highly accurate gas atmosphere. It is an object of the present invention to provide a pusher-type continuous firing furnace that can be controlled, has reduced gas consumption, and is excellent in processing efficiency.

In order to achieve the above object, a pusher type continuous firing furnace according to claim 1 is configured such that a base plate on which a treated product is placed is conveyed by a pusher in a furnace body for firing the treated product. The furnace body is provided with a floor surface on which the base plate can slide, and each base plate is covered with a sheath to form an independent fired sheath, and the position of each fired sheath in the furnace body is at that position. A gas introduction pipe for introducing a gas for adjusting the atmosphere inside a certain fired sheath and a gas exhaust pipe for discharging the gas are arranged, and the floor surface at the position of each fired sheath in the furnace body is penetrated respectively. A hole is provided, the gas introduction pipe and the gas discharge pipe are connected to the through hole, and a through hole is also provided in each base plate, so that the firing sheath conveyed by the pusher should change the firing atmosphere. Reached the transport zone Until leaving the conveying zone, when the through hole of the through hole and the floor of the base plate of the firing sheath matches, gas through the through-hole is introduced into the sintering sheath from the gas inlet tube in calcination sheath Is adjusted to the set atmosphere in the transport zone, and until the firing sheath reaches the next transport zone in the furnace body where the firing atmosphere should be changed again and exits the transport zone, the through hole of the base plate of the fired sheath When the gas is introduced into the fired sheath through the through-hole and the interior of the fired sheath is adjusted to the set atmosphere in the transport zone, The through-holes in the plate are vertically long and extend in the transport direction of the base plate, and are provided in two positions respectively in the front and rear in the transport direction approximately symmetrically across the center line, and the through-holes in the floor surface are positioned at the positions of the fired sheaths. In the same way as the through hole of the base plate, In general, it is provided at a position where the through-holes of the baked sheath base plate that is continuously transported by the pusher can always coincide with the through-holes of the floor surface during transportation, two places in front and back in the transport direction of the base plate. Thus, during conveyance of the fired sheath, gas is introduced into and discharged from the fired sheath through the through holes at all times .

  According to the present invention, each base plate is covered with a sheath to constitute an independent fired sheath, and since the atmospheric gas is constantly flowing from the gas introduction pipe, the fired sheath is continuously conveyed by the pusher. The gas is introduced through the through-hole when the through-hole of the calcined sheath plate matches the through-hole of the floor surface until it reaches the transfer zone in the furnace body where the firing atmosphere should be changed and exits the transfer zone. From the tube into the fired sheath, the fired sheath is adjusted to the set atmosphere in the transport zone, until the fired sheath reaches the next transport zone in the furnace body where the firing atmosphere should be changed, and exits the transport zone When the through hole of the base plate of the fired sheath matches the through hole of the floor surface, the atmosphere set in the transport zone is introduced into the fired sheath from the gas introduction pipe through the through hole. Configured to be adjusted to Since that, to be able to switch the gas atmosphere in the firing sheath in a short time (several minutes), it is possible to atmosphere control with high precision, it can be fired the treated product in a stable atmosphere. In addition, gas consumption can be reduced.

  In particular, by making the through hole of the base plate into a vertically long shape extending in the transport direction of the base plate, even if the fired sheath is continuously transported by the pusher, the time for matching with the through hole on the floor surface becomes longer, and the fired sheath Since the atmosphere can be sufficiently switched, the processing efficiency is excellent.

  When cooling the treated product after firing, a large amount of cooling gas (inexpensive air or nitrogen gas) can be introduced into the firing sheath from the gas introduction pipe without affecting the atmosphere and temperature before and after, so the cooling rate And cooling time can be shortened.

It is the schematic which shows the structure of the pusher type continuous baking furnace of this invention. Similarly, it is a schematic cross-sectional view. It is a figure which shows the plane and side surface of a baseplate. It is a sectional side view of a sheath. It is a schematic cross-sectional view showing a calcined sheath, a gas introduction pipe, and a gas discharge pipe in a calcining furnace. It is explanatory drawing which shows the positional relationship of the through-hole of a baseplate and the through-hole of a floor surface.

  Hereinafter, specific embodiments of the pusher-type continuous firing furnace of the present invention will be described with reference to the drawings.

  As in the conventional pusher furnace, the pusher type continuous firing furnace according to the present invention is provided with a heating element 7 such as a silicon carbide heating element for heating a processed product placed on a base plate as shown in FIG. The processed product placed on the base plate is conveyed from the processed product inlet 3 to the right of the furnace main body 1 by the pusher 2 and taken out from the processed product outlet 4. An input port 5 and a discharge port 6 for atmospheric gas in the furnace are provided.

  In the conventional pusher furnace according to the present invention, as shown in more detail in FIGS. 3 to 5, each base plate 13 is covered with a sheath 14 to form independent firing sheaths 12. At the position of the sheath 12, a gas introduction pipe 10 for introducing a gas for adjusting the atmosphere inside the fired sheath at that position and a gas discharge pipe 11 for discharging the gas are arranged. Accordingly, as shown in FIGS. 1 and 2, the furnace body 1 is provided with a large number of gas introduction pipes 10 and gas discharge pipes 11 independently for each position of the fired sheath. The hearth of the furnace body 1 is preferably a floor 15 on which the base plate 13 of the fired sheath 12 can easily slide, and a rail made of a refractory material is laid so that the base plate 13 can easily slide and be transported. Is more preferable.

  Through holes 19 and 20 are provided in the floor surface 15 of each fired sheath in the furnace body, respectively, and the gas introduction pipe 10 and the gas discharge pipe 11 are connected to the through holes 19 and 20, respectively. The introduction pipe 10 is connected, and the gas discharge pipe 11 is connected to the through hole 20. Each base plate 13 is also provided with through holes 17 and 18. As shown in FIG. 5, the gas introduced from the gas introduction port 8 flows through the gas introduction pipe 10, and the through holes 19 in the floor 15. Then, it is introduced into the fired sheath 12 through the through hole 17 of the base plate 13 of the fired sheath 12 to adjust the atmosphere in the fired sheath 12, and the through hole 18 of the base plate 13 of the fired sheath 12 penetrates the floor surface 15. The gas flows into the gas discharge pipe 11 through the hole 20 and is discharged from the gas discharge port 9.

  The gas introduced into the fired sheath through the gas introduction pipe 10 is adjusted for forming an atmosphere at that position, and each processed product 16 such as a ceramic electronic component is in the fired sheath 12 in the adjusted atmosphere. Heated to the set temperature at the position. The gas introduction pipe 10 has a structure in which gas always flows, and is configured such that the gas is immediately introduced into the calcined sheath 12 when the through hole 17 and the through hole 19 coincide with each other.

  In FIG. 5, reference numeral 21 denotes a rectifying plate placed on the through hole side into which gas is introduced, and is preferably made of ceramic with slits cut so that the gas flows only at the position of the processed product 16. Since the gas flows directly into the processed product 16 by disposing the rectifying plate 21, the volatile gas generated from the processed product 16 is quickly removed, and the processed product can be baked in a uniform atmosphere. Become.

  As the base plate 13 and the sheath 14, it is preferable to use a ceramic material such as alumina or silicon carbide having an apparent porosity of 20% or less. By selecting the material, the gas atmosphere in the fired sheath 12 is maintained at a set atmosphere. can do. If the apparent porosity exceeds 20%, the surrounding atmosphere gas tends to flow into the fired sheath and there may be a problem in maintaining the set gas atmosphere. The fired sheath has a structure in which the gap between the base plate 13 and the sheath 14 is closed by the gravity of the sheath 14, and for this purpose, the contact surface between the base plate 13 and the sheath 14 is polished so that no gap is generated. Is desirable. It is also desirable to polish the contact surface between the floor surface (or rail) 15 on which the base plate 13 slides and the base plate 13.

  The firing of a processed product such as a ceramic electronic component by the pusher-type continuous firing furnace of the present invention having the above-described configuration will be described. For example, as shown in FIG. In the case of changing the firing atmosphere, the through hole 17 of the base plate of the fired sheath and the floor until the firing sheath transported by the pusher reaches the transport zone b where the firing atmosphere should be changed from the transport zone a and exits the transport zone b. When the through-hole 19 of the surface 15 coincides, it is introduced into the fired sheath 12 from the gas introduction pipe 10 through the through-holes 17 and 19 and adjusted to the atmosphere set in the transport zone b. In the adjusted atmosphere, it is heated to the temperature set in the transport zone b and baked.

  The fired sheath 12 that has passed through the transport zone b is transported by the pusher and reaches the next transport zone c until it exits the transport zone c, and the through hole 17 of the base plate of the fired sheath and the through hole 19 of the floor 15 Are matched, the gas is introduced into the fired sheath 12 from the gas introduction pipe 10 through the through holes 17 and 19 and adjusted to the atmosphere set in the transport zone c, and the processed product 16 is adjusted in the adjusted atmosphere. It is heated to the temperature set in the transport zone c and baked.

  When more transfer zones are set in the furnace body, the above steps are repeated, and the process is performed and fired under the gas atmosphere and temperature conditions set in each transfer zone. In the furnace main body 1, as shown in FIG. 3, the through holes 17 and 18 of the base plate 13 can be switched even if the fired sheath 12 is continuously conveyed by the pusher in order to switch the atmosphere in the fired sheath. Is preferably a vertically long shape extending in the conveying direction of the base plate. With this configuration, the through hole 17 of the base plate and the floor surface 15 pass through while the fired sheath passes through the transport zone when pushed by the pusher. Since the time for matching with the hole 19 becomes longer and the time during which the atmosphere is adjusted by introducing the gas into the fired sheath during the passage can be made longer, the atmosphere can be sufficiently switched during the passage. .

  Even if the vertically long through-holes 17 of the base plate 13 shown in FIG. 3 are arbitrarily arranged in the transport direction of the base plate, the time for the through-holes 17 of the base plate and the through-holes 19 of the floor surface 15 to coincide is increased. can do. Further, in FIG. 3, a plurality of through holes may be arranged in the conveying direction of the base plate instead of the vertically long through holes 17. However, as shown in FIG. 17 and 18 are formed in a vertically long shape extending in the transport direction of the base plate 13, approximately symmetrically across the center line XY, and two places each in the front and rear in the transport direction, for a total of four locations (17 a, 17 b, 18 a, 18 b) The length of the base plate is L, the length of the through holes 17 and 18 is 1 / 4L, the interval between the through holes 17a and 17b, and the distance between 18a and 18b is 1 / 4L. To 1/8 L from the through hole 17.

  The corresponding through-holes 19 and 20 in the floor surface 15 are substantially symmetrical with respect to the through-holes 17 and 18 of the base plate 13 in the same manner as the through-holes 17 and 18 of the base plate 13 with the center line XY sandwiched in the front-rear direction in the transport direction of the base plate. A total of four places (19a, 19b, 20a, 20b) are provided for each two places, and the positional relationship with the through holes 17a, 17b, 18a, 18b of the base plate is as shown in FIG. In FIG. 6, A is a conveyance direction of the base plate 13 of a baking sheath.

  According to the above embodiment, the fired sheath continuously transported by the pusher reaches a predetermined transport zone (positions n and n + 1 shown in FIG. 6 and thereafter n + n) and then exits this transport zone. Between the through holes provided on the floor, a set of gas introduction holes and gas discharge holes, that is, a set of through holes 19a and 20a, a set of 19b and 20b, and a base plate are provided. Among the through holes, the set of the gas introduction hole and the gas discharge hole, that is, the set of the through holes 17a and 18a and the set of 17b and 18b always coincide with each other. The gas is introduced into and discharged from the fired sheath through the through hole, and the atmosphere in the fired sheath is adjusted in a short time.

  In the pusher-type continuous firing furnace of the present invention, as described above, the atmospheres of the three transport zones a, b, and c in the furnace body are set to 1 (oxygen 3% + nitrogen 97%) and 2 (oxygen 0), respectively. .5% + nitrogen 99.5%), setting 3 (oxygen 0.15% + nitrogen 99.85%) when firing, change the atmosphere only in a predetermined zone, gas diffusion to other zones and gas In order to prevent the introduction, the method using a partition wall or a curtain cannot achieve a set atmosphere even after 10 minutes, for example, but in the present invention, it is covered with a sheath 14 and independent. Since the gas can be directly introduced into the treated product in the fired sheath 12 and only the atmosphere in the fired sheath needs to be replaced, for example, the atmosphere can be switched reliably in a short time of about 2 minutes, and the gas consumption is also Can be reduced Kill.

DESCRIPTION OF SYMBOLS 1 Body body of a pusher type continuous firing furnace 2 Pusher 3 Processed product inlet 4 Processed product outlet 5 Atmospheric gas inlet 6 Atmospheric gas outlet 7 Heating element 8 Gas inlet 9 Gas outlet 10 Gas inlet pipe 11 Gas outlet pipe 12 fired sheath 13 base plate 14 sheath 15 floor surface 16 processed product 17 base plate gas introduction side through hole 18 base plate gas discharge side through hole 19 floor surface gas introduction side through hole 20 floor surface gas introduction side through hole 21 Rectifier plate

Claims (1)

Into the furnace body for firing the treated product, with a pusher furnace which is configured to stand carrying the treated product plate is transported by the pusher, the furnace body is provided with the floor on which the base plate can slide, each platform The plates are covered with sheaths to form independent firing sheaths, and each firing sheath in the furnace body has a gas introduction pipe for introducing a gas for adjusting the atmosphere in the firing sheath at that position. Gas exhaust pipes for exhausting gas are respectively disposed, and through holes are provided in the floor surface of each firing sheath in the furnace body, and the gas introduction pipe and the gas exhaust pipe are connected to the through holes. Each base plate is also provided with a through-hole, and the firing sheath transported by the pusher reaches the transportation zone in the furnace body where the firing atmosphere should be changed, and until it exits the transportation zone, the firing sheath base Through hole in board and through hole in floor Furnace body but if they match, should be changed gas is within firing sheath is introduced into the sintering sheath from the gas inlet pipe is adjusted to set the atmosphere in the conveying zone, the firing atmosphere calcination sheath again through the through hole When the through hole on the base plate of the calcined sheath and the through hole on the floor surface coincide with each other until the next transport zone is reached and exit the transport zone, the gas is fired from the gas introduction pipe through the through hole. In the case where the baked sheath is introduced into the sheath and the inside of the sheath is adjusted to the set atmosphere in the transport zone, the through hole of the base plate is a vertically long shape extending in the transport direction of the base plate and is substantially symmetrical across the center line. Two through-holes are provided in the front and rear in the transport direction, and the through-holes in the floor surface are front and rear in the transport direction of the base plate substantially symmetrically across the center line, similar to the through-holes in the base plate, at the positions of the respective fired sheaths. 2 places in each, connected by pusher The through hole of the base plate of the fired sheath that is transported in a continuous manner is provided at a position where it can always coincide with the through hole of the floor surface during transport. A pusher-type continuous firing furnace characterized in that gas is introduced into and discharged from the furnace.

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