Firing furnace

Abstract

To easily acquire a temperature rising rate suitable for firing a molding member in a firing furnace.SOLUTION: A firing furnace 1 comprises a vibration detection sensor 40 arranged at a furnace 10 and detecting vibration in the furnace body 10, and a thermocouple 31 for a rack and a thermocouple 32 for a molding member as temperature sensors for measuring temperatures in the furnace body 10. In this way, a control unit 7 can satisfactorily and easily acquire information on the generation of cracking in a molding member 100 during firing in the furnace body 10 at a certain temperature rising rate and the temperature in the furnace body 10 upon generation of the cracking in the molding member 100. Thus, a relationship between the temperature rising rate and the temperature at which the molding member 100 cracks can be easily obtained. Therefore, the temperature rising rate suitable for firing the molding member 100 in the firing furnace 1 can be easily acquired.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a firing furnace. [Background technology]

[0002] As disclosed in Patent Documents 1 to 3, a grinding wheel is manufactured by mixing abrasive grains and a binder to form a molded member, and firing the molded member in a firing furnace. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 63-007269 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-021267 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-183627 Summary of the Invention [Problem to be solved by the invention]

[0004] When firing a molded member to obtain a fired product, the molded member is placed in a furnace, the temperature inside the furnace is raised to the firing temperature (for example, 1400° C.), and this temperature is maintained for a predetermined time.

[0005] However, the molded member may crack when the temperature inside the furnace is raised to the firing temperature, and it takes time and effort to determine the appropriate temperature rise rate (for example, the fastest possible temperature rise rate that does not cause cracks).

[0006] Therefore, an object of the present invention is to easily obtain an appropriate temperature rise rate for firing a molded member in a firing furnace. [Means for solving the problem]

[0007] The firing furnace (main firing furnace) of the present invention is a firing furnace that fires molded members to produce fired products, and is equipped with a furnace body in which the molded members are placed and fired, a heater that heats the inside of the furnace body, a vibration detection sensor that is placed in the furnace body and detects vibrations within the furnace body, and a temperature sensor that measures the temperature within the furnace body.

[0008] This firing furnace may further include a memory unit for storing the temperature measured by the temperature sensor when the magnitude of the vibration detected by the vibration detection sensor is equal to or greater than a preset threshold value while the temperature inside the furnace body is being raised at a certain heating rate, and a control unit for slowing down the heating rate at which the temperature inside the furnace body is raised toward the firing temperature when the temperature inside the furnace body becomes a predetermined temperature lower than the temperature stored in the memory unit.

[0009] Furthermore, the firing furnace may further include a memory unit for storing the temperature measured by the temperature sensor when the magnitude of the vibration detected by the vibration detection sensor is equal to or greater than a preset threshold value while the temperature inside the furnace body is being increased at a certain rate, and a control unit for slowing the rate of increase in temperature up to the temperature stored in the memory unit compared to the rate of increase in temperature when the temperature was stored in the memory unit. [Effects of the Invention]

[0010] The firing furnace is equipped with a vibration detection sensor that detects vibrations within the furnace body and a temperature sensor that measures the temperature within the furnace body. This makes it possible to easily and reliably detect when a crack occurs in a formed member being fired in the furnace body at a certain temperature rise rate, and the temperature within the furnace body when the crack occurs in the formed member. Therefore, in the firing furnace, the relationship between the temperature rise rate and the temperature at which the formed member cracks can be easily obtained. Therefore, an appropriate temperature rise rate for firing a formed member in the firing furnace can be easily obtained. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view showing the configuration of a firing furnace. [Figure 2]FIG. 2 is a perspective view showing the configuration of an insulating block and a baking rack. [Figure 3] 10 is a graph showing temperature changes inside the furnace body in the first firing step. [Figure 4] 10 is a graph showing temperature changes inside the furnace body during the second firing step. [Figure 5] 10 is a graph showing a change in temperature inside the furnace body in the third firing step. [Figure 6] 10 is a graph showing temperature changes inside a furnace body during firing of a molded member. [Figure 7] 10 is a graph showing another temperature change inside the furnace body during firing of a molded member. DETAILED DESCRIPTION OF THE INVENTION

[0012] 1, a firing furnace 1 according to this embodiment produces a fired product by firing a molded member 100. The fired product obtained by firing the molded member 100 is, for example, a grinding wheel provided in a grinding device that grinds workpieces such as semiconductor wafers.

[0013] The firing furnace 1 has a furnace body 10 in which a molded member 100 is placed and fired. The furnace body 10 is equipped with an insulating block 11 and an insulating block lid 12. As shown in Figures 1 and 2, the insulating block 11 has a substantially rectangular parallelepiped shape (approximately box-like), and a firing space 13 in which the molded member 100 is placed is formed inside. The top surface of the insulating block 11 is open so that the firing space 13 is exposed.

[0014] As shown in FIG. 1, the heat insulating block lid 12 is a generally plate-shaped member that is configured to be able to close the upper surface of the heat insulating block 11 that is open, thereby sealing the baking space 13 .

[0015] The baking space 13 is opened as shown in Fig. 2 by removing the insulating block lid 12 from the insulating block 11. Inside the baking space 13, a plurality of baking racks 20 for holding the molded members 100 can be stacked.

[0016] 1 and 2, the firing rack 20 includes a bottom plate 21 on which the formed member 100 is placed, a top plate 22, and a plurality of (for example, four) support columns 23 that connect the bottom plate 21 and the top plate 22. The support columns 23 have a length that allows the formed member 100 to be placed between the bottom plate 21 and the top plate 22.

[0017] Within the baking space 13, multiple baking racks 20 can be stacked on top of each other by placing the bottom plate 21 of one baking rack 20 on the top plate 22 of another baking rack 20 (in Figure 1, three baking racks 20 are stacked).

[0018] A linear heater 15 is disposed on the inner wall of the insulating block 11 so as to surround the firing space 13. The heater 15 heats the interior of the furnace body 10. That is, the heater 15 is configured to generate heat when connected to a power source (not shown) to raise the temperature inside the firing space 13. In this embodiment, the heater 15 is disposed on substantially the entire surface of the inner wall of the insulating block 11. The heater 15 may include a single heating wire arranged in a spiral shape on the inner wall of the insulating block 11, or may include multiple heating wires.

[0019] 1, a rack thermocouple 31 for measuring the temperature of the bottom plate 21 is attached to the bottom plate 21 of each firing rack 20. In addition, a forming member thermocouple 32 for measuring the temperature of the forming member 100 is attached to the forming member 100 placed on the bottom plate 21. The rack thermocouple 31 and the forming member thermocouple 32 are examples of temperature sensors that measure the temperature inside the furnace body 10.

[0020] The rack thermocouple 31 extends upward from the bottom plate 21, passes through the insulating block lid 12 of the furnace body 10, and is connected to a first measuring instrument 301 outside the furnace body 10. The first measuring instrument 301 can measure the temperature of the bottom plate 21 by measuring the voltage generated in the rack thermocouple 31.

[0021] The thermocouple 32 for the formed member extends upward from the formed member 100, passes through the insulating block lid 12 of the furnace body 10, and is connected to a second measuring instrument 302 outside the furnace body 10. The second measuring instrument 302 can measure the temperature of the formed member 100 by measuring the voltage generated in the thermocouple 32 for the formed member.

[0022] 1 and 2, a vibration detection sensor 40 is disposed in the furnace body 10. In this embodiment, the vibration detection sensor 40 is disposed on the outer wall of the insulating block 11 in the furnace body 10. The vibration detection sensor 40 includes an AE sensor (Acoustic Emission sensor) or a microphone, and detects vibrations within the furnace body 10. For example, if a formed member 100 held on a firing rack 20 in the firing space 13 of the furnace body 10 cracks during firing, the vibration detection sensor 40 can detect vibrations associated with the crack. In this embodiment, the vibration detection sensor 40 can detect the occurrence of vibration in the furnace body 10 as well as the magnitude of the vibration occurring in the furnace body 10.

[0023] 1, the firing furnace 1 includes a control unit 7 that controls each component of the firing furnace 1, and a storage unit 8. The control unit 7 includes a CPU that performs calculations according to a program, and a storage medium such as a memory. The control unit 7 controls each component of the firing furnace 1 to fire the formed member 100. The storage unit 8 is used to store various data used for control by the control unit 7.

[0024] When the formed member 100 is fired in the firing furnace 1, the temperature inside the furnace body 10 is raised based on a temperature rise rate set by the control unit 7. The setting of the temperature rise rate in this embodiment will be described below. In this embodiment, in order to set the temperature rise rate, a plurality of firing steps (firing experiments) are carried out. In the example shown below, three firing steps (first to third firing steps) are carried out.

[0025] [First firing process] In the first firing step, first, an operator places the firing rack 20 holding the formed members 100 in the firing space 13 of the furnace body 10. Next, the operator closes the upper surface of the insulating block 11 with the insulating block lid 12 to seal the firing space 13.

[0026] Next, the control unit 7 controls the power supplied to the heater 15 to raise the temperature in the firing space 13 where the firing rack 20 holding the formed members 100 is placed (i.e., the temperature in the furnace body 10). Specifically, as shown in Fig. 3, the control unit 7 raises the temperature in the furnace body 10 from room temperature T0 to a predetermined firing temperature TB at a first temperature rise rate HR1. At this time, the control unit 7 acquires, for example, the temperature of the firing rack 20 measured by the rack thermocouple 31 and the first measuring instrument 301 shown in Fig. 1 as the temperature in the furnace body 10.

[0027] After the temperature inside the furnace body 10 reaches a predetermined firing temperature TB, the control unit 7 maintains the temperature inside the furnace body 10 at this firing temperature TB for a predetermined time. Thereafter, the control unit 7 lowers the temperature inside the furnace body 10 to room temperature T0 at a predetermined temperature lowering rate CR.

[0028] The first temperature rise rate HR1 is a relatively fast temperature rise rate for the formed member 100. Therefore, when the temperature is raised at the first temperature rise rate HR1, the formed member 100 cracks before the temperature inside the furnace body 10 reaches the firing temperature TB. In this embodiment, as shown in FIG. 3, the time when the formed member 100 cracks is defined as time t1. At this time t1, a relatively large vibration occurs inside the furnace body 10 due to the cracking of the formed member 100.

[0029] In this case, the control unit 7 detects that the formed member 100 has cracked by detecting vibrations in the furnace body 10 using the vibration detection sensor 40. Specifically, the control unit 7 determines that the formed member 100 has cracked when the magnitude of the vibrations detected by the vibration detection sensor 40 is equal to or greater than a preset threshold value.

[0030] Then, the control unit 7 acquires a first temperature T1, which is the temperature inside the furnace body 10 when the formed member 100 cracks (at time t1), and stores this first temperature T1 in association with the first temperature rise rate HR1 in the memory unit 8. In this way, the memory unit 8 is used to store the temperature inside the furnace body 10 measured by the rack thermocouple 31, which is a temperature sensor, when the magnitude of the vibration detected by the vibration detection sensor 40 is equal to or greater than a preset threshold value while the temperature inside the furnace body 10 is being raised at a certain temperature rise rate.

[0031] [Second firing process] Next, the second firing step is carried out. In this step, first, an operator replaces the formed member 100 in the firing space 13 of the furnace body 10. Specifically, the operator removes the firing rack 20 holding the fired product made of the broken formed member 100 from the firing space 13 of the furnace body 10, places the firing rack 20 holding a new formed member 100 in the firing space 13, and seals the firing space 13.

[0032] Next, as shown in FIG. 4, the control unit 7 raises the temperature inside the furnace body 10 to a first temperature T1 at a first temperature rise rate HR1, and then raises the temperature from the first temperature T1 to a predetermined firing temperature TB at a second temperature rise rate HR2 that is slower than the first temperature rise rate HR1, and after a predetermined time, lowers the temperature to room temperature T0 at a predetermined temperature drop rate CR. The second temperature increase rate HR2 is also a relatively fast temperature increase rate for the formed member 100. Therefore, after the formed member 100 cracks at the first temperature T1, the formed member 100 will crack even when heated at the second temperature increase rate HR2 before the temperature inside the furnace body 10 reaches the firing temperature TB. In this embodiment, as shown in FIG. 4, the time when the formed member 100 cracks during heating at the second temperature increase rate HR2 is defined as time t2.

[0033] As in the first firing step, the control unit 7 detects that the formed member 100 has cracked by detecting vibrations in the furnace body 10 using the vibration detection sensor 40. Then, the control unit 7 acquires a second temperature T2, which is the temperature in the furnace body 10 when the formed member 100 cracked (time t2) during heating at the second heating rate HR2, and stores this second temperature T2 in the memory unit 8 in association with the second heating rate HR2. Since the second temperature increase rate HR2 is slower than the first temperature increase rate HR1, as shown in Fig. 4, the second temperature T2 at which the molded member 100 cracks during heating at the second temperature increase rate HR2 is higher than the first temperature T1 shown in Fig. 3. In addition, the time t2 at which the molded member 100 cracks is also later than the time t1 shown in Fig. 3.

[0034] [Third firing process] Next, the third firing step is carried out. In this step, first, an operator replaces the formed member 100 in the firing space 13 of the furnace body 10 in the same manner as in the second firing step. Next, as shown in FIG. 5, the control unit 7 raises the temperature inside the furnace body 10 to a first temperature T1 at a first temperature rise rate HR1, then raises the temperature from the first temperature T1 to a second temperature T2 at a second temperature rise rate HR2, and further raises the temperature from the second temperature T2 to a predetermined firing temperature TB at a third temperature rise rate HR3 that is slower than the second temperature rise rate HR2, and after a predetermined time, lowers the temperature to room temperature T0 at a predetermined temperature drop rate CR. The third temperature increase rate HR3 is a relatively slow temperature increase rate for the formed member 100. Therefore, after the formed member 100 cracks at the first temperature T1 and the second temperature T2, the formed member 100 will not crack when heated at the third temperature increase rate HR3 before the temperature inside the furnace body 10 reaches the firing temperature TB.

[0035] After the third firing step, the control unit 7 sets the temperature rise rate for firing the molded member 100. That is, the control unit 7 sets the temperature rise rate using the first temperature rise rate HR1, the second temperature rise rate HR2, and the third temperature rise rate HR3, as well as the first temperature T1 and the second temperature T2 stored in the memory unit 8 in the first and second firing steps.

[0036] In this embodiment, the control unit 7 sets a temperature rise rate HR as shown in Fig. 6, and raises the temperature inside the furnace body 10 based on this temperature rise rate HR. This temperature rise rate HR is a combination of the above-mentioned first temperature rise rate HR1, second temperature rise rate HR2, and third temperature rise rate HR3.

[0037] In the temperature increase based on this temperature increase rate HR, the control unit 7 first increases the temperature inside the furnace body 10 from room temperature T0 to a temperature (temperature T1-ΔT) that is lower than the first temperature T1 by a predetermined temperature ΔT at a first temperature increase rate HR1. This predetermined temperature ΔT is a set temperature that is preset in the control unit 7.

[0038] Next, the control unit 7 raises the temperature inside the furnace body 10 from temperature T1-ΔT to a temperature (temperature T2-ΔT) that is lower than the second temperature T2 by a predetermined temperature ΔT at a second temperature rise rate HR2 that is slower than the first temperature rise rate HR1. As a result, the temperature rise rate HR when the temperature inside the furnace body 10 reaches the first temperature T1 is the second temperature rise rate HR2 that is slower than the first temperature rise rate HR1. This makes it possible to suppress cracking of the molded member 100 at the first temperature T1 shown in FIG. 3. The predetermined temperature ΔT subtracted from the second temperature T2 may be the same as or different from the predetermined temperature ΔT subtracted from the first temperature T1.

[0039] Next, the control unit 7 increases the temperature inside the furnace body 10 from temperature T2-ΔT to the firing temperature TB at a third temperature increase rate HR3 that is slower than the second temperature increase rate HR2. As a result, the temperature increase rate HR when the temperature inside the furnace body 10 reaches the second temperature T2 is the third temperature increase rate HR3 that is slower than the second temperature increase rate HR2. This makes it possible to suppress cracking of the molded member 100 at the second temperature T2 shown in FIG. 4.

[0040] After the temperature inside the furnace body 10 reaches a predetermined firing temperature TB, the control unit 7 maintains the temperature inside the furnace body 10 at this firing temperature TB for a predetermined time. Thereafter, the control unit 7 lowers the temperature inside the furnace body 10 to room temperature T0 at a predetermined temperature lowering rate CR. This causes the molded member 100 to be fired, producing a fired product.

[0041] As described above, in this embodiment, the firing furnace 1 is equipped with a vibration detection sensor 40 that detects vibrations within the furnace body 10, and the rack thermocouple 31 and the formed member thermocouple 32 that serve as temperature sensors that measure the temperature within the furnace body 10. This allows the control unit 7 to easily and reliably detect the occurrence of a crack in the formed member 100 being fired within the furnace body 10 at a certain temperature rise rate, and the temperature within the furnace body 10 when the crack occurred in the formed member 100.

[0042] Therefore, in this embodiment, it is possible to easily obtain the relationship between the temperature rise rate and the temperature at which the formed member 100 cracks. Therefore, it is possible to easily obtain an appropriate temperature rise rate (for example, the above-mentioned temperature rise rate HR) for firing the formed member 100 in the firing furnace 1.

[0043] Furthermore, in this embodiment, when the temperature inside the furnace body 10 becomes lower by a predetermined temperature ΔT than the first temperature T1 and the second temperature T2, which are temperatures stored in the memory unit 8, the control unit 7 slows down the temperature increase rate HR, which is the rate at which the temperature inside the furnace body 10 is increased toward the firing temperature TB. This makes it possible to suppress cracking of the molded member 100 at the first temperature T1 and the second temperature T2.

[0044] Specifically, when the temperature inside the furnace body 10 reaches temperature T1-ΔT, the control unit 7 changes the temperature rise rate from the first temperature rise rate HR1 to the second temperature rise rate HR2. Therefore, the temperature rise rate HR when the temperature inside the furnace body 10 reaches the first temperature T1 becomes the second temperature rise rate HR2, which is slower than the first temperature rise rate HR1, and therefore cracking of the formed member 100 at the first temperature T1 shown in FIG. 3 can be suppressed.

[0045] Furthermore, when the temperature inside the furnace body 10 reaches temperature T2-ΔT, the control unit 7 changes the temperature rise rate from the second temperature rise rate HR2 to the third temperature rise rate HR3. Therefore, the temperature rise rate HR when the temperature inside the furnace body 10 reaches the second temperature T2 is the third temperature rise rate HR3, which is slower than the second temperature rise rate HR2, and therefore cracking of the formed member 100 at the second temperature T2 shown in FIG. 4 can be suppressed. Therefore, in this embodiment, the temperature inside the furnace body 10 can be raised to the firing temperature TB while suppressing cracking of the formed member 100.

[0046] In this embodiment, the temperature rise rate HR (see FIG. 6) is set by combining a third temperature rise rate HR3 (see FIG. 5) that does not cause cracks in the formed member 100 with faster first temperature rise rates HR1 (see FIG. 3) and second temperature rise rates HR2 (see FIG. 4). Therefore, the temperature in the furnace body 10 can be raised to the firing temperature TB in a shorter time than when the temperature in the furnace body 10 is raised from room temperature T0 to the firing temperature TB at the third temperature rise rate HR3. Therefore, it is possible to fire the formed member 100 in a shorter time while suppressing cracks in the formed member 100.

[0047] In this embodiment, three firing steps (first to third firing steps) are performed to set the temperature rise rate. In this regard, the number of firing steps (firing experiments) for setting the temperature rise rate may be two, four or more. These firing steps for setting the temperature rise rate preferably include a firing step at a temperature rise rate at which cracks occur in the molded member 100 before the temperature in the furnace body 10 reaches the firing temperature TB, and a firing step at a temperature rise rate at which cracks do not occur in the molded member 100 before the temperature in the furnace body 10 reaches the firing temperature TB.

[0048] Then, when firing the formed member 100, the control unit 7 starts raising the temperature at a temperature rise rate that will cause cracks in the formed member 100. Thereafter, the control unit 7 slows the temperature rise rate when the temperature reaches a predetermined temperature lower than the temperature at which cracks will occur at this temperature rise rate. By repeating this process, the control unit 7 eventually raises the temperature inside the furnace body 10 to the firing temperature TB at a temperature rise rate that will not cause cracks. This makes it possible to produce a fired product in a short time while suppressing cracks in the formed member 100. In addition to the grinding wheel, the fired product may be a porous member of a chuck table, a dense frame body in which the porous member is arranged, or a dense support table that supports the chuck table.

[0049] In this embodiment, the firing furnace 1 is equipped with a rack thermocouple 31 and a formed member thermocouple 32 as temperature sensors for measuring the temperature inside the furnace body 10. In this regard, the firing furnace 1 may be equipped with other temperature measuring devices such as a high-temperature radiation thermometer as temperature sensors.

[0050] In this embodiment, the control unit 7 acquires the temperature of the firing rack 20 measured by the rack thermocouple 31 and the first measuring instrument 301 as the temperature inside the furnace body 10. In this regard, the control unit 7 may acquire the temperature of the forming member 100 measured by the forming member thermocouple 32 and the second measuring instrument 302 as the temperature inside the furnace body 10. In this case, the memory unit 8 is used to store the temperature measured by the forming member thermocouple 32 when the magnitude of the vibration detected by the vibration detection sensor 40 is equal to or greater than a preset threshold value.

[0051] Furthermore, in this embodiment, when the temperature inside the furnace body 10 is being increased at a certain rate, and the magnitude of the vibration detected by the vibration detection sensor 40 is equal to or greater than a preset threshold, the control unit 7 associates the temperature (T1, T2) inside the furnace body 10 measured by the rack thermocouple 31 or the formed part thermocouple 32 with the temperature increase rate (HR1, HR2) and stores them in the memory unit 8. The control unit 7 may then set the temperature increase rate at which the temperature inside the furnace body 10 reaches the temperature (T1, T2) stored in the memory unit 8 to be slower than the temperature increase rate (HR1, HR2) stored in the memory unit 8 and associated with this temperature (T1, T2). For example, the control unit 7 may set a temperature increase rate HR as shown in FIG. 7, and increase the temperature inside the furnace body 10 based on this temperature increase rate HR.

[0052] This temperature increase rate HR is a combination of a first temperature increase rate HR1' that is slower (has a gentler temperature gradient) than the above-mentioned first temperature increase rate HR1, a second temperature increase rate HR2' that is slower than the second temperature increase rate HR2, and a third temperature increase rate HR.

[0053] In the temperature increase based on this temperature increase rate HR, the control unit 7 first increases the temperature inside the furnace body 10 from room temperature T0 to a first temperature T1 at a first temperature increase rate HR1'. Because the first temperature increase rate HR1' is slower than the first temperature increase rate HR1, cracking of the formed member 100 at the first temperature T1 shown in Figure 3 can be suppressed. Note that the first temperature increase rate HR1' is, for example, slower than the first temperature increase rate HR1 and faster than the second temperature increase rate HR2.

[0054] Next, the control unit 7 increases the temperature inside the furnace body 10 from the first temperature T1 to the second temperature T2 at a second temperature increase rate HR2'. Because the second temperature increase rate HR2' is slower than the second temperature increase rate HR2, cracking of the formed member 100 at the second temperature T2 shown in Figure 4 can be suppressed. Note that the second temperature increase rate HR2' is, for example, slower than the second temperature increase rate HR2 and faster than the third temperature increase rate HR3.

[0055] Next, the control unit 7 increases the temperature inside the furnace body 10 from the second temperature T2 to the firing temperature TB at a third temperature increase rate HR3 that is slower than the second temperature increase rate HR2. After the temperature inside the furnace body 10 reaches a predetermined firing temperature TB, the control unit 7 maintains the temperature inside the furnace body 10 at this firing temperature TB for a predetermined time. Thereafter, the control unit 7 lowers the temperature inside the furnace body 10 to room temperature T0 at a predetermined temperature lowering rate CR. This causes the molded member 100 to be fired, producing a fired product.

[0056] As described above, in this embodiment, the control unit 7 sets the temperature rise rate when the temperature inside the furnace body 10 reaches the first temperature T1 and the second temperature T2 stored in the memory unit 8 to be slower than the first temperature rise rate HR1 and the second temperature rise rate HR2 (the temperature rise rates at which the formed member 100 cracks at each temperature) stored in the memory unit 8 in association with the respective temperatures. That is, the control unit 7 sets the temperature rise rate up to the first temperature T1 and the second temperature T2, which are the temperatures stored in the memory unit 8, to be slower than the first temperature rise rate HR1 and the second temperature rise rate HR2, which are the temperature rise rates when the first temperature T1 and the second temperature T2 are stored in the memory unit 8. Therefore, cracking of the formed member 100 at the first temperature T1 and the second temperature T2 can be suppressed.

[0057] When storing in the memory unit 8 the temperature measured by the temperature sensor when the magnitude of the vibration detected by the vibration detection sensor 40 is equal to or greater than a preset threshold, the control unit 7 does not need to associate the temperature with the heating rate. In other words, the memory unit 8 only needs to be used to store the temperature measured by the temperature sensor, i.e., the rack thermocouple 31 or the molded part thermocouple 32, when the temperature inside the furnace body 10 is being heated at a certain heating rate and the magnitude of the vibration detected by the vibration detection sensor 40 is equal to or greater than a preset threshold. [Explanation of symbols]

[0058] 1: firing furnace, 7: control unit, 8: memory unit, 10: furnace body, 11: heat insulating block, 12: Heat insulating block lid, 13: Firing space, 15: Heater, 20: Firing rack, 21: bottom plate, 22: top plate, 23: support column, 31: rack thermocouple, 32: Thermocouple for molding member, 40: Vibration detection sensor, 100: Molding member, 301: First measuring instrument, 302: Second measuring instrument, CR: Temperature drop rate, HR: Temperature rise rate, HR1, HR1': first temperature rise rate, HR2, HR2': second temperature rise rate, HR3: Third heating rate, T0: room temperature, T1: first temperature, T2: second temperature, TB: baking temperature, ΔT: predetermined temperature

Claims

1. A firing furnace for firing a molded member to produce a fired product, a furnace body for placing the molded member and firing it; a heater for heating the inside of the furnace body; a vibration detection sensor disposed in the furnace body and detecting vibrations within the furnace body; a temperature sensor for measuring the temperature inside the furnace body; A firing furnace equipped with:

2. a memory unit for storing the temperature measured by the temperature sensor when the magnitude of the vibration detected by the vibration detection sensor is equal to or greater than a preset threshold value while the temperature inside the furnace body is being increased at a certain temperature increase rate; and a control unit that slows down the rate at which the temperature of the furnace body is raised toward the firing temperature when the temperature of the furnace body becomes a predetermined temperature lower than the temperature stored in the memory unit. The firing furnace according to claim 1.

3. a storage unit for storing the temperature measured by the temperature sensor when the magnitude of vibration detected by the vibration detection sensor is equal to or greater than a preset threshold value while the temperature inside the furnace body is being increased at a certain temperature increase rate; and a control unit that makes the rate of temperature rise to the temperature stored in the storage unit slower than the rate of temperature rise when the temperature was stored in the storage unit. The firing furnace according to claim 1.

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