The present invention relates to a housing for heating and a use method of the housing for heating, a heating jig and a use method of the jig, and an operation method of a heating device.
A heating step is used in manufacturing various products. For example, there is broadly used a method of disposing a plate, a shelf assembly or the like on which a plurality of articles to be heated are mounted in a furnace to simultaneously heat the plurality of articles to be heated (e.g., Patent Document 1).
However, when the plurality of articles to be heated, which are mounted on the plate or the shelf assembly, are simultaneously heated, the plate or the shelf assembly absorbs heat, whereby fluctuations are generated in an ambient temperature around the articles to be heated. In consequence, fluctuations are generated in the amount of heat received by the articles to be heated.
In view of the above problem, an object of the present invention is to provide a housing for heating which enables simultaneous heating of a plurality of articles to be heated and decreases a difference in the amount of heat received by the articles to be heated during the heating, a use method of the housing for heating, a heating jig and a use method of the jig, and an operation method of a heating device.
The present invention has been completed to achieve the above object. Specifically, there are provided a housing for heating and a use method of the housing for heating, a heating jig and a use method of the jig, and an operation method of a heating device as follows.
[1] A housing for heating comprising: a plurality of mounting parts each including a mounting face on which articles to be heated are mounted, which is a part of the surface of the mounting part; and a fixing part to which the plurality of mounting parts are detachably fixed so that the plurality of mounting parts are stacked while a space is left between the mounting face of one of the mounting parts and the mounting part disposed adjacent to the one mounting part, wherein the plurality of mounting parts include the mounting part provided with the mounting face having a thermal emissivity which is different from that of the mounting face of the other mounting part.
[2] The housing for heating according to the above [1], wherein the mounting part has a plate shape, and includes the mounting face on one of two front and back surfaces of the plate shape, and the plurality of mounting parts are stacked while a space is left between the mounting face of the one mounting part and the surface of the mounting part stacked above the one mounting part on a side opposite to the mounting face of the mounting part.
[3] The housing for heating according to the above [2], wherein the mounting face of the mounting part having the plate shape has a thermal emissivity which is equal to that of the surface of the mounting part opposite to the mounting face thereof.
[4] The housing for heating according to any one of the above [1] to [3], further comprising a plurality of units each including the mounting part and the fixing part combined with the mounting part, wherein the fixing part of one of the units is detachably connected to the other unit so that the plurality of units are stacked while a space is left between the mounting face of the one unit and the unit disposed adjacent to the one unit.
[5] A use method of the housing for heating according to any one of the above [1] to [4], comprising the steps of: in case of mounting the articles to be heated on the mounting faces of the mounting parts to house the articles to be heated in the housing for heating and heating the articles to be heated together with the housing for heating by heating means, stacking the plurality of mounting parts so that the ascending order of the size of the thermal emissivity of the mounting face of each of the mounting parts corresponds to the descending order of the rise/fall of an ambient temperature in a facing space of the mounting face, to use the mounting parts.
[6] A use method of the housing for heating according to any one of the above [1] to [4], comprising the steps of: mounting the articles to be heated on the mounting faces of the plurality of mounting parts to house the articles to be heated in the housing for heating while stacking the mounting parts so that the thermal emissivity of the mounting face of each of the mounting parts is not less than the thermal emissivity of the mounting face of the mounting part stacked above each of the mounting parts; storing the housing for heating in a storage chamber surrounded by a wall part; and raising an ambient temperature in the storage chamber to heat the articles to be heated together with the housing for heating.
[7] An operation method of a heating device comprising the housing for heating according to any one of the above [1] to [4], a storage section which stores the housing for heating in a storage chamber surrounded by a wall part having an inner wall surface made of a material having a thermal emissivity of 0.7 or more at a wavelength of 1.6 to 2.6 μm, ambient temperature measuring means for measuring an ambient temperature in the storage chamber, temperature distribution measurement means for measuring a temperature distribution in the article to be heated, and heating means for heating the inside of the storage chamber while controlling a temperature rise speed of the ambient temperature based on the ambient temperature measured by the ambient temperature measuring means and the temperature distribution measured by the temperature distribution measuring means, the method comprising the steps of: storing, in the storage chamber of the storage section, the housing for heating in which the articles to be heated are mounted; and heating the inside of the storage chamber by the heating means while controlling the temperature rise speed of the ambient temperature so that the temperature distribution in the article to be heated measured by the temperature distribution measuring means is from 0.9 to 1.0 time a maximum allowable value, when the ambient temperature measuring means measures the ambient temperature having the maximum allowable value of the temperature distribution in the article to be heated, which is determined so that any defect is not generated in the articles to be heated.
[8] The operation method of the heating device according to the above [7], further comprising the steps of: raising the ambient temperature so that the temperature reaches 750° C. or higher.
[9] The operation method of the heating device according to the above [7] or [8], wherein the inner wall surface is made of a material including at least two main components selected from the group consisting of silicon carbide (SiC), titanium oxide (TiO2 or TiO) and silica (SiO2).
[10] The operation method of the heating device according to the above [7] or [8], wherein the wall part includes an inner wall member constituting the inner wall surface, and a supporter with which the inner wall member is lined, and the inner wall member has a thickness of 0.1 to 3.0 mm and is made of a material containing at least two main components selected from the group consisting of silicon carbide (SiC), titanium oxide (TiO2 or TiO) and silica (SiO2).
[11] A heating jig comprising a mounting part having a plate shape and including one of two front and back surfaces as a mounting face on which articles to be heated are mounted, wherein the thermal emissivity of the center of the mounting face is larger than that of an edge side portion of the mounting face.
[12] The heating jig according to the above [11], wherein the mounting part includes a plurality of members having a plate shape, and the mounting face is formed by aligning and contacting with, substantially on the same plane, one of the two front and back surfaces of each of the plurality of members having the plate shape.
[13] A use method of the heating jig according to any one of the above [11] or [12], comprising the steps of: storing the heating jig having the mounting face on which the articles to be heated are mounted in a storage chamber surrounded by a wall part; and heating the heating jig together with the articles to be heated by radiant-heat transfer from the wall part.
[14] An operation method of a heating device comprising the heating jig according to the above [11] or [12], a storage section which contains the heating jig in a storage chamber surrounded by a wall part having an inner wall surface made of a material having a thermal emissivity of 0.7 or more at a wavelength of 1.6 to 2.6 μm, ambient temperature measuring means for measuring an ambient temperature in the storage chamber, temperature distribution measurement means for measuring a temperature distribution in the article to be heated, and heating means for heating the inside of the storage chamber while controlling a temperature rise speed of the ambient temperature based on the ambient temperature measured by the ambient temperature measuring means and the temperature distribution measured by the temperature distribution measuring means, the method comprising the steps of: storing, in the storage chamber of the storage section, the heating jig on which the articles to be heated are mounted; and heating the inside of the storage chamber by the heating means while controlling the temperature rise speed of the ambient temperature so that the temperature distribution in the article to be heated measured by the temperature distribution measuring means is from 0.9 to 1.0 time a maximum allowable value, when the ambient temperature measuring means measures the ambient temperature having the maximum allowable value of the temperature distribution in the article to be heated, which is determined so that any defect is not generated in the articles to be heated.
[15] The operation method of the heating device according to the above [14], further comprising the steps of: raising the ambient temperature so that the temperature reaches 750° C. or higher.
[16] The operation method of the heating device according to the above [14] or [15], wherein the inner wall surface is made of a material including at least two main components selected from the group consisting of silicon carbide (SiC), titanium oxide (TiO2 or TiO) and silica (SiO2).
[17] The operation method of the heating device according to the above [14] or [15], wherein the wall part includes an inner wall member constituting the inner wall surface, and a supporter with which the inner wall member is lined, and the inner wall member has a thickness of 0.1 to 3.0 mm and is made of a material containing at least two main components selected from the group consisting of silicon carbide (SiC), titanium oxide (TiO2 or TiO) and silica (SiO2).
The housing for heating of the present invention enables simultaneous heating of a plurality of articles to be heated, and can decrease a difference in the amount of heat received by the articles to be heated during the heating. The use method of the housing for heating of the present invention can simultaneously heat the plurality of articles to be heated and decrease the difference in the amount of the heat received by the articles to be heated during the heating.
The heating jig of the present invention enables the simultaneous heating of the plurality of articles to be heated, and can decrease the difference in the amount of the heat received by the articles to be heated during the heating. The use method of the heating jig of the present invention can simultaneously heat the plurality of articles to be heated and decrease the difference in the amount of the heat received by the articles to be heated during the heating.
The operation method of the heating device of the present invention heats the articles to be heated in the storage chamber surrounded by the inner wall surface made of the material having a high thermal emissivity, to decrease the difference in the amount of the heat received by the articles to be heated, thereby easily obtaining a uniform temperature in the articles to be heated. Furthermore, the operation method of the heating device of the present invention can increase the temperature rise speed of the ambient temperature in the storage chamber as much as possible. When the temperature rise speed is increased in this manner, the efficiency of energy required for temperature rise can be improved, and generation of a defective article to be heated can be minimized.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and alteration, modification or improvement can be added to the embodiments without departing from the scope of the present invention.
1. Housing for Heating
A housing for heating of the present invention comprises a plurality of mounting parts each having a mounting face on which articles to be heated are mounted, which is a part of the surface of the mounting part; and a fixing part to which the plurality of mounting parts are detachably fixed so that the plurality of mounting parts are stacked while a space is left between the mounting face of one of the mounting parts and the mounting part disposed adjacent to the one mounting part, characterized in that the plurality of mounting parts include the mounting part provided with the mounting face having a thermal emissivity which is different from that of the mounting face of the other mounting part.
In the housing for heating of the present invention, it is possible to mount the articles to be heated on the mounting faces of the plurality of mounting parts. Therefore, the housing for heating of the present invention can house a plurality of articles to be heated. Moreover, the housing for heating of the present invention can contain the plurality of articles to be heated to simultaneously heat the articles, and can, accordingly, improve productivity.
In the housing for heating of the present invention, an ambient temperature in a space where the articles to be heated are housed varies with each space sometimes. In such a case, when the articles to be heated are housed in the space having a high ambient temperature, the articles to be heated receive a large amount of heat from an ambient gas. When the articles to be heated are housed in the space having a low ambient temperature, the articles to be heated receive a small amount of heat from the ambient gas.
To cope with the above situation, in the housing for heating of the present invention, the order of the mounting parts may be determined so as to increase the thermal emissivity of the mounting face facing the space where the ambient temperature lowers during the heating and decrease the thermal emissivity of the mounting face facing the space where the ambient temperature rises (described later in detail). When the order of the mounting parts is determined in this manner, it is possible to transfer a large amount of heat to the article to be heated which receives less heat from the ambient gas, by radiant heat transfer from the mounting face. Moreover, it is possible to only transfer a small amount of heat to the article to be heated which receives more heat from the ambient gas, by the radiant heat transfer from the mounting face. Therefore, in a case where a plurality of articles to be heated are housed and heated in the housing for heating of the present invention, a difference in the amount of the heat received by the articles to be heated can be decreased.
In the housing for heating of the present invention, the mounting part has a plate shape, and includes the mounting face on one of two front and back surfaces of the plate shape, and the plurality of mounting parts are stacked while a space is left between the mounting face of the one mounting part and the surface of the mounting part stacked above the one mounting part on a side opposite to the mounting face of the mounting part.
In this embodiment, the two front and back surfaces of the mounting part having the plate shape face the spaces where the articles to be heated are housed, and hence the mounting part easily receives the heat from the ambient gas in the spaces where the articles to be heated are housed. Therefore, the mounting part can efficiently transfer the heat absorbed from the ambient gas to the articles to be heated by the radiant heat transfer. Furthermore, the mounting part having the plate shape is preferably made thin. In this case, the heat capacity of the mounting part lowers, and hence the temperature of the mounting part rapidly rises. In consequence, it is possible to more efficiently transfer the radiant heat from the mounting part to the articles to be heated.
Furthermore, in the embodiment including the mounting part having the above plate shape, the mounting face of the mounting part has a thermal emissivity which is equal to that of the surface of the mounting part opposite to the mounting face thereof.
In this embodiment, when the mounting part is provided with the mounting face having a high thermal emissivity, the opposite surface of the mounting part also has a high thermal emissivity. The high thermal emissivity means a high thermal absorptivity. Therefore, when the thermal emissivity of the mounting face is high, the mounting face and the opposite surface absorb much heat, whereby the mounting part can accumulate a large amount of heat. In consequence, the mounting part can transfer a large amount of heat to the articles to be heated by the radiant heat transfer. When the thermal emissivity of the mounting face is low, the mounting face and the opposite surface only absorb a small amount of heat, and hence the amount of the heat accumulated in the mounting part also decreases. In consequence, the mounting part only transfers a small amount of heat to the articles to be heated. Therefore, in this embodiment, a difference between the high thermal emissivity and the low thermal emissivity of the mounting face can more clearly be reflected in the difference in the amount of the heat transferred from the mounting part to the articles to be heated.
The housing for heating of the present invention preferably comprises a plurality of units each including the mounting part and the fixing part combined with the mounting part, and the fixing part of one of the units is detachably connected to the other unit so that the plurality of units are stacked while a space is left between the mounting face of the one unit and the unit disposed adjacent to the one unit.
In this embodiment, the attaching/detaching of the unit constituting the housing for heating and the changing of arrangement of the units can easily be performed. Therefore, in this embodiment, when heating conditions in an electric furnace are changed, it is possible to easily cope with the change of the conditions by changing the arrangement of the units or the like. Moreover, when the housing for heating is stored and heated in the electric furnace, the articles to be heated can beforehand be mounted on the mounting faces outside the electric furnace, moved, as they are, into the electric furnace, and rapidly heated.
Hereinafter, a specific example of the embodiment of the housing for heating of the present invention will be described to explain contents of the housing for heating of the present invention in detail.
The embodiment will be described with reference to
In the shelf assembly 21 shown in
Moreover, the shelves 23a and 23b may be stacked with a posture where the supporters 29 are disposed on the upside and the shelf plates 25a and 25b are disposed on the downside (not shown). For example, on the supporters 29 of the shelf 23a, the shelf plate 25b of another shelf 23b may be stacked. In this case, the shelf assembly 21 shown in
The radiant heat transfer is a phenomenon where heat is transferred from a high-temperature body to a low-temperature body by radiation and absorption. The thermal emissivity varies depending on the type of a substance, the temperature of the substance, or a wavelength. Therefore, the amount of the heat transferred by the radiant heat transfer, so-called the radiant heat transfer amount is determined by a complicated phenomenon where a plurality of factors are entwined.
Considering from a relation between the radiant heat amount from a black body having a thermal emissivity of 1 and a wavelength peak, the wavelength at which the radiant heat amount at 1000° C. reaches a peak is, for example, 2.3 μm. Similarly, the wavelength at which the radiant heat amount at 1250° C. reaches the peak is 1.9 μm, and the wavelength at which the amount at 1500° C. reaches the peak is 1.6 μm (not shown). Therefore, it can be understood from analysis of Planck's law that in a temperature range of the black body exceeding 1000° C., the thermal emissivity at a wavelength of 2.3 μm or less noticeably influences the radiant heat transfer, but it is well known that the black body is merely ideal.
An alumina refractory material is used in a structure material of a firing furnace (a refractory material for use in a furnace wall or the like) or a base material of the shelf assembly in which the articles to be heated are housed. Moreover, it is known that the thermal emissivity of the alumina refractory material is 0.65 (e.g., refer to “Journal of Chemical Engineering of Japan” (issued by Maruzen Co., Ltd.)). Heretofore, when the articles to be heated are heated by using the structure material of the firing furnace or the shelf assembly made of the alumina refractory material, the thermal emissivity of the alumina refractory material is 0.65. Therefore, it is not necessary to control the thermal emissivity by use of a material other than the alumina refractory material. It has been considered that a temperature distribution is inevitably generated in the shelf assembly or the like.
However, from the measurement results of the emissivities of the alumina refractory material, SiC containing SiO2 and titanium oxide containing SiO2 in a wavelength range around 2 μm, as shown in
Therefore, the present inventors have focused on the thermal emissivity of the housing for heating in which the articles to be heated are disposed (e.g., the shelf assembly for heating) being regulated when heating the articles to be heated, and have intended to further decrease the width of the temperature distribution generated in the shelf assembly or the like.
For example, the thermal emissivity of the alumina material is different from that of the mixture of titanium oxide and SiO2. Therefore, the shelf assembly 21 shown in
Alternatively, the shelf plate 25b may be prepared by coating the surface of the shelf plate 25a with a coat layer made of the mixture of titanium oxide and SiO2. In this case, the mixture of titanium oxide and SiO2 is easily adsorbed by the alumina material, and hence the coat layer made of the mixture of titanium oxide and SiO2 does not easily peel from the surface of the shelf plate 25a made of the alumina material. Moreover, when the shelf plate 25b is prepared from the shelf plate 25a as described above, a weight or a heat capacity only slightly increases as much as the coating layer.
A use method can be applied to the above housing for heating (hereinafter referred to as “the use method of the housing for heating of the present invention”) as follows.
2. Use Method of Housing for Heating
A first embodiment of the use method of the housing for heating of the present invention uses the above housing for heating, and is characterized by, in case of mounting the articles to be heated on the mounting faces of the mounting parts to house the articles to be heated in the housing for heating and heating the articles to be heated together with the housing for heating by heating means, stacking the plurality of mounting parts so that the ascending order of the size of a thermal emissivity of the mounting face of each of the mounting parts corresponds to the descending order of the rise/fall of an ambient temperature in a facing space of the mounting face, to use the mounting parts.
In this first embodiment, when the articles to be heated receive a small amount of heat from the ambient gas, the articles receive a large amount of heat by radiant heat transfer from the mounting face. Moreover, when the articles to be heated receive a large amount of heat from the ambient gas, the articles receive a small amount of heat by the radiant heat transfer from the mounting face. Therefore, in the first embodiment of the use method of the housing for heating of the present invention, a difference in the total amount of the heat received by the articles to be heated from the ambient gas and the mounting face decreases among the articles to be heated. Therefore, it is possible to suppress uneven heating in all the articles to be simultaneously heated.
Furthermore, in this first embodiment, since the uneven heating can be suppressed, any heat does not have to be transferred to the articles to be heated over time so that the width of the temperature distribution in the article to be heated is not enlarged (e.g., in case of the heating by use of the furnace, the temperature rise speed of an in-furnace ambient temperature does not have to be minimized). In consequence, productivity improves, and a degree of freedom in a temperature profile during the heating enlarges (e.g., in the case of the heating by use of the furnace, the set range of the rise/fall of the temperature rise speed of the in-furnace ambient temperature enlarges).
A second embodiment of the use method of the housing for heating of the present invention uses the above housing for heating, and is characterized by mounting the articles to be heated on the mounting faces of the plurality of mounting parts to house the articles to be heated in the housing for heating while stacking the mounting parts so that the thermal emissivity of the mounting face of each of the mounting parts is not less than the thermal emissivity of the mounting face of the mounting part stacked above each of the mounting parts; storing the housing for heating in a storage chamber surrounded by a wall part; and raising an ambient temperature in the storage chamber to heat the articles to be heated together with the housing for heating.
When the temperature of the ambient gas in the storage chamber rises, the gas flows upwards. Therefore, the articles to be heated on the upper mounting part receive a large amount of heat from the ambient gas. In the second embodiment, the thermal emissivity of each mounting face is equal to or larger than that of the lower mounting face, so that variability of the amount of the heat received from the ambient gas can be eliminated. That is, when the articles to be heated receive a small amount of heat from the ambient gas, the articles receive a large amount of heat by the radiant heat transfer from the mounting face. When the articles receive a large amount of heat from the ambient gas, the articles receive a small amount of heat by the radiant heat transfer from the mounting face.
Therefore, in the second embodiment of the use method of the housing for heating of the present invention, a difference in the total amount of the heat received by the articles to be heated from the ambient gas and the mounting face decreases among the articles to be heated. In consequence, it is possible to suppress the heating unevenness in all the articles to be simultaneously heated.
Also in this second embodiment, since the uneven heating can be suppressed, any heat does not have to be transferred to the articles to be heated over time so that the width of the temperature distribution in the article to be heated is not enlarged (e.g., the temperature rise speed of an ambient temperature in the storage chamber does not have to be minimized). In consequence, productivity improves, and a degree of freedom in a temperature profile (e.g., a heat curve of the ambient temperature in the storage chamber) during the heating enlarges.
Hereinafter, a specific example of the embodiment of the use method of the housing for heating of the present invention will be described to explain contents of the use method of the housing for heating of the present invention in more detail.
In the shelf assembly 21 shown in
3. Heating Jig and Use Method of Heating Jig
A heating jig of the present invention includes a mounting part having a plate shape, and one of two front and back surfaces as a mounting face on which articles to be heated are mounted, and is characterized in that the thermal emissivity of the center portion of the mounting face is larger than that of an edge side portion of the mounting face.
The heating jig of the present invention is preferably used during heating in a configuration where the temperature of the edge side portion of the mounting part rises earlier than the temperature of the center portion of the mounting part (described later in detail). The heating jig is preferable, for example, in a case where a heat source is disposed so that the temperature of the edge side portion of the mounting part rises earlier than that of the center portion of the mounting part. In such a case, the article mounted on the edge side portion of the mounting face receives a larger amount of heat from the heat source as compared with the article mounted on the center portion of the mounting part. Moreover, in the heating jig of the present invention, the thermal emissivity of the center portion of the mounting face is larger than that of the edge side portion of the mounting face, whereby the center portion of the mounting face absorbs a larger amount of heat than the edge side portion of the mounting face. In consequence, the article mounted on the center portion of the mounting face receives a larger amount of heat by the radiant heat transfer from the mounting face, as compared with the article mounted on the edge side portion of the mounting face. Therefore, a difference in the total amount of the heat received by the article to be heated from the heat source and the mounting face becomes small between the article mounted on the center portion of the mounting face and the article mounted on the edge side portion of the mounting face.
In the heating jig of the present invention, the mounting part includes a plurality of members having a plate shape, and the mounting face is formed by arranging and combining, substantially on the same plane, one of the two front and back surfaces of each of the plurality of members having the plate shape. In this embodiment, the area of the mounting face can be enlarged, and hence more articles to be heated can simultaneously be heated. Moreover, the articles to be heated are beforehand mounted on the surfaces which are the mounting faces of the members having the plate shape, these members having the plate shape are separately moved into the furnace, and the members having the plate shape may be assembled to form the heating jig in the furnace. In this case, it is possible to cope with even a situation where there is not any operation space having a sufficient breadth outside the furnace.
In the heating jig of the present invention, an embodiment may be applied in which the center portion of one of the two front and back surfaces of each member having the plate shape and made of a first material is coated with a member made of a second material having a larger thermal emissivity than the first material, to set the thermal emissivity of the center portion of the mounting face to be larger than that of the edge side portion of the mounting face. When the center portion of the surface is coated with the second material, a membrane made of the second material may be formed by using a spray or the like. Examples of an advantage of such a case include an advantage that the case can easily be applied when the surface of the member having the plate shape has a complicated shape, and an advantage that a weight or a heat capacity only slightly increases as much as the film. For example, in an embodiment in which an alumina material is used as the first material and the mixture of titanium oxide and SiO2 is used as the second material, the mixture of titanium oxide and SiO2 is easily adsorbed by the alumina material, and hence the film made of the mixture of titanium oxide and SiO2 does not easily peel from the alumina material. Moreover, when this embodiment is applied in the furnace and first heat history is received, the adsorbed mixture itself causes sticking and sintering by generation of a vitreous material owing to an influence of a micro amount of inevitable impurities included in the mixture itself and the alumina material between the adsorbed mixture and the alumina material. In consequence, peeling between the adsorbed mixture and the alumina material does not easily occur.
The use method of the heating jig of the present invention uses the above heating jig, and is characterized by heating the heating jig having the mounting face on which the articles to be heated are stored in a storage chamber surrounded by a wall part; and heating the heating jig together with the articles to be heated by radiant heat transfer from the wall part. In the use method of the heating jig of the present invention, the article mounted on the edge side portion of the mounting face receives a larger amount of heat by radiant heat from the wall part, as compared with the article mounted on the center portion of the mounting part. However, since the article mounted on the center portion of the mounting face receives a large amount of heat by the radiant heat transfer from the mounting face as compared with the article mounted on the edge side portion of the mounting face as described above, a difference in the total amount of the heat received by the article to be heated from the wall part and the mounting face becomes small between the article mounted on the center portion of the mounting face and the article mounted on the edge side portion of the mounting face.
Hereinafter, a specific example of the embodiment of the heating jig of the present invention will be described to explain contents of the heating jig and the use method of the heating jig of the present invention in detail.
4. Operation Method of Heating Device
In a heating step, when a temperature difference is generated in the articles to be heated, a heat stress is generated in the articles to be heated. When this heat stress exceeds a material strength, thermal shock cracks and the like are generated. To cope with this problem, in a conventional heating step, an ambient temperature in a space where the articles to be heated are disposed is moderately raised so that a temperature difference in the articles to be heated is not enlarged. In this case, defects such as the thermal shock cracks are not easily generated in the articles to be heated (e.g., refer to JP-A-2003-212672 and JP-A-2004-059357). However, in a method of moderately raising the ambient temperature in the space where the articles to be heated are disposed, a problem occurs that time required for the temperature rise lengthens and much energy is consumed for the temperature rise. To solve this problem, the present inventors set up a purpose of providing an operation method of a heating device having a low generation frequency of damages by the heating of the articles to be heated and having a high energy efficiency. The present inventors have contrived the operation of the heating device as follows.
The operation method of the present heating device (hereinafter referred to as “the present operation method”) is characterized by using the heating device comprising a storage section which contains articles to be heated in a storage chamber surrounded by a wall part having an inner wall surface made of a material having a thermal emissivity of 0.7 or more at a wavelength of 1.6 to 2.6 μm, ambient temperature measuring means for measuring an ambient temperature in the storage chamber, temperature distribution measurement means for measuring a temperature distribution in the article to be heated, and heating means for heating the inside of the storage chamber while controlling a temperature rise speed of the ambient temperature based on the ambient temperature measured by the ambient temperature measuring means and the temperature distribution measured by the temperature distribution measuring means.
Furthermore, the present operation method is characterized by storing the articles to be heated in the storage chamber of the storage section; and heating the inside of the storage chamber by the heating means while controlling the temperature rise speed of the ambient temperature so that the temperature distribution in the article to be heated measured by the temperature distribution measuring means is from 0.9 to 1.0 time a maximum allowable value, when the ambient temperature measuring means measures the ambient temperature having the maximum allowable value of the temperature distribution in the article to be heated, which is determined so that any defect is not generated in the articles to be heated.
In the operation method of the present heating device, the articles to be heated are heated in the storage chamber surrounded by the inner wall surface made of a material having a high thermal emissivity to easily obtain a uniform temperature in the articles to be heated. The temperature rise speed of the ambient temperature in the storage chamber is raised as much as possible. Therefore, the energy efficiency required for the temperature rise can be increased, and the generation of a defective article to be heated can be minimized.
Since the inner wall surface of the wall part surrounding the storage chamber is made of the material having a thermal emissivity of 0.7 or more at a wavelength of 1.6 to 2.6 μm, the articles disposed in the storage chamber can receive much more heat by the radiant heat transfer from the wall part around the articles. Therefore, the articles to be heated can be heated while the width of the temperature distribution is set to be smaller.
A radiant heat transfer amount from a wall part of a flat plate (temperature T1 and thermal emissivity e1) to a flat plate to be heated (temperature T2 and thermal emissivity e2) shown in
As understandable from the above finding described with reference to
There is not any special restriction on the specific constitution of the ambient temperature measuring means as long as the means can measure the ambient temperature in the storage chamber in real time.
The temperature distribution measuring means measures the temperature distribution in the article to be heated in real time. The temperature distribution in the article mentioned in the present description is measured so that defects such as damages or surface color unevenness due to heat stress are not generated, and the temperature distribution does not necessarily mean a difference between the maximum temperature and the minimum temperature in the articles to be heated. The temperature distribution measuring means does not necessarily have to measure the temperatures of all portions in the articles to be heated. For example, when the difference in the surface temperature between two specific places A and B in the article to be heated is measured, the generation of the damages on the article to be heated can be prevented. In this case, the temperature distribution measuring means measures the surface temperature difference between the specific place A and the specific place B in the article to be heated. Even when there is a place having a temperature higher or lower than the temperature of the place A or B in the article to be heated, the surface temperature difference between the place A and the place B may be regarded as the temperature distribution.
In the articles to be heated, the maximum allowable value of the temperature distribution in the article to be heated is determined so that defects such as the damages or the surface color unevenness due to the heat stress are not generated in the articles to be heated. The maximum allowable value is determined in accordance with the ambient temperature in the storage chamber. For example, in the operation method of the heating device for raising the ambient temperature in the storage chamber from 20° C. to 1200° C., when the temperature distribution in the article to be heated at the ambient temperature of 1000 to 1200° C. exceeds 1% of the ambient temperature (e.g., 10° C. at 1000° C. or 12° C. at 1200° C.), a defective article to be heated is generated. In this case, the maximum allowable value of the temperature distribution in the article to be heated is set to 10° C. at the ambient temperature of 1000° C. or 12° C. at the ambient temperature of 1200° C. It is to be noted that the maximum allowable value of the temperature distribution in the article to be heated varies in accordance with the size, shape, material or the like of the articles to be heated. For example, the maximum allowable value of the temperature distribution in the article to be heated can be determined based on preliminary experiments or empirical findings.
When the temperature rise speed of the ambient temperature in the storage chamber is higher, the width of the temperature distribution in the article to be heated further easily enlarges. In the present operation method, since the heating means controls the temperature rise speed of the ambient temperature in the articles to be heated so that the temperature distribution in the article to be heated is from 0.9 to 1.0 time the above maximum allowable value, the temperature rise speed of the ambient temperature in the storage chamber does not lower excessively. Furthermore, this temperature rise speed is raised to such an extent that the width of the temperature distribution in the article to be heated is not enlarged excessively. Therefore, the articles to be heated can rapidly be heated so that any defect is not generated in the articles to be heated. Especially in the present operation method, the articles to be heated in the storage chamber can receive a large amount of heat owing to radiant heat transfer from the wall part, and hence the width of the temperature distribution in the article to be heated tends to become small. In such a situation where the width of the temperature distribution becomes small, the temperature rise speed of the ambient temperature in the storage chamber has to be raised so that the temperature distribution in the article to be heated is from 0.9 to 1.0 time the above maximum allowable value. Therefore, in the present operation method, since the temperature rise speed of the ambient temperature is increased, time required for raising the ambient temperature to a desirable temperature can be shortened, so that energy required for raising the ambient temperature can be decreased.
In the present operation method, the material of the inner wall surface is regulated so that the thermal emissivity of the material is 0.7 or more at a wavelength of 1.6 to 2.6 μm. When it is considered that the wavelength of 1.6 to 2.6 μm is dominant in heat radiation at 750 to 1500° C., the ambient temperature in the storage chamber is preferably raised to be 750° C. or higher in the present operation method. When the temperature of the inner wall surface is from 750 to 1500° C., much heat is transferred from the wall part to the articles to be heated by radiant heat transfer, and the temperature distribution in the article to be heated further easily becomes uniform. Therefore, the temperature rise speed of the ambient temperature in the storage chamber has to be further increased so that the temperature distribution in the article to be heated is from 0.9 to 1.0 time the maximum allowable value, when the ambient temperature in the storage chamber is from 750 to 1500° C. Therefore, time required for temperature rise in an ambient temperature range from 750 to 1500° C. is further shortened.
In the present operation method, the inner wall surface of the wall part of the storage section is preferably made of a material including at least two components selected from the group consisting of silicon carbide (SiC), titanium oxide (TiO2, TiO or the like), and silica (SiO2) (cristobalite, tridymite, silica or the like). Since the emissivity of this material at a wavelength of 1.6 to 2.6 μm is 0.7 or more at both ordinary temperature (25° C.) and high temperature, the above material can be selected to increase the efficiency of radiant heat transfer. In consequence, when the temperature distribution enlarges in the articles to be heated, the efficiency of the heat transfer to a low temperature portion of the article to be heated is kept to be high as compared with the heat transfer to a high temperature portion of the article to be heated. In consequence, the width of the temperature distribution in the article to be heated can be reduced.
The wall part of the heating device includes an inner wall member forming the inner wall surface, and a supporter with which the inner wall member is lined, and the inner wall member has a thickness of 0.1 to 3.0 mm and is made of a material containing at least two components selected from the group consisting of silicon carbide (SiC), titanium oxide (TiO2 or TiO) and silica (SiO2) (cristobalite, tridymite, or silica glass). The above inner wall member can transfer much heat to the articles to be heated by the radiant heat transfer, when the temperature of the inner wall member is from 750 to 1500° C. Moreover, since the inner wall member has a thickness of 3.0 mm or less, a heat capacity lowers, and it is possible to decrease the absolute value of the heat amount necessary for transferring the heat to the articles to be heated by the radiant heat transfer.
In the present operation method, when the width of the temperature distribution in the article to be heated does not easily enlarge, the temperature rise speed of the ambient temperature in the storage chamber can further be increased. In consequence, the efficiency of the energy can further be improved. When the plurality of articles to be heated are simultaneously heated by using the above housing for heating and heating jig of the present invention, the difference in the amount of the heat received by the articles to be heated can be decreased. Moreover, the width of the temperature distribution in each article to be heated does not easily enlarge. Therefore, in the present operation method, the above housing for heating and heating jig of the present invention are preferably used. In the present operation method, when the housing for heating and heating jig of the present invention are used, the temperature rise speed of the ambient temperature in the storage chamber can further be increased. In consequence, the generation frequency of damages due to the heating of the articles to be heated can further be decreased, and the efficiency of the energy can further be improved.
Hereinafter, the present invention will be described with respect to examples in more detail, but the present invention is not limited to these examples.
(1) Shelf Assembly
(2) Electric Furnace
The electric furnace 11 had an effective inner dimension of width 500×depth 500×height 500 mm, and heaters 13 were installed on wall surfaces 18 of all furnace walls 14 on all four surfaces constituting side surfaces (
(3) Heating Test:
Shelf assemblies 21 of Example 1 and Comparative Example 1 described hereinafter were arranged in the furnace inner space 12 of the electric furnace 11 as shown in
Shelves 23a which were not provided any coat layer were stacked as six upper stages, and shelves 23b provided with coat layers were stacked as seven lower stages, to assemble a shelf assembly 21 having 13 stages in total. The shelf assembly 21 was disposed on the right side in the furnace inner space 12 as one faced a door of the electric furnace 11 (on the right side in
Shelves 23a which were not provided with any coat layer were stacked in 13 stages to assemble a shelf assembly 21. The shelf assembly 21 was disposed on the left side of a furnace inner space 12 as one faces a door of an electric furnace 11 (on the left side in
In the electric furnace 11, the shelf assemblies 21 of Example 1 and Comparative Example 1 were disposed, and an ambient temperature in the furnace inner space 12 was raised as shown by a heating curve in
From a positional relation between the furnace walls 14 and the heaters 13, column I of Example 1 exhibits a contrast to column III of Comparative Example 1, and column II of Example 1 exhibits a contrast to column IV of Comparative Example 1. Hereinafter, results of comparison of the columns in contrast to each other will be described.
Here, the results in 6.5 hours after the start of the heating shown in
In 6.5 hours after the start of the heating shown in
Next, the results in 7.5 hours after the start of the heating shown in
In 7.5 hours after the start of the heating shown in
Finally, results in 8.9 hours after the start of the heating shown in
Shelf assemblies 21 of Comparative Examples 2 and 3 described hereinafter were arranged in a furnace inner space 12 of an electric furnace 11 as shown in
Shelves 23b provided with coat layers were stacked in 13 stages to assemble a shelf assembly 21. The shelf assembly 21 was disposed on the right side in a furnace inner space 12 as one faced a door of an electric furnace 11 (on the right side in
Shelves 23a which were not provided with any coat layer were stacked in 13 stages to assemble a shelf assembly 21. The shelf assembly 21 was disposed on the left side in a furnace inner space 12 as one faced a door of an electric furnace 11 (on the left side in
In the electric furnace 11, the shelf assemblies 21 of Comparative Examples 2 and 3 were disposed, and an ambient temperature in the furnace inner space 12 was raised as shown by a heat curve shown in
In either of 6.5 hours and 7.5 hours after the start of the heating, the temperature of the shelf assembly was higher in Comparative Example 2 owing to a large thermal emissivity of the shelves as compared with Comparative Example 3. However, a temperature distribution in the shelf assembly was substantially the same in Comparative Examples 2 and 3, and unlike Example 1, an effect of obtaining a small temperature distribution was not observed. Therefore, it has been found that even when the thermal emissivities of all the shelves are uniformly set to be large, the effect of obtaining the small temperature distribution in the shelf assembly is not produced.
Next, investigations of the above-mentioned operation method of the heating device will be described. Reference Example 1 described hereinafter belongs to the technical range of the operation method of the heating device (the present operation method). On the other hand, Reference Examples 2 and 3 do not belong to the technical range of the present operation method.
In the furnace inner space 102, two shelf assemblies 113 each obtained by stacking alumina shelf plates 111 in 20 stages via supporters were arranged in the furnace inner space 102 (
Temperature rise conditions were set so that the ambient temperature in the furnace inner space 102 was raised from ordinary temperature (25° C.) to 1400° C. After the ambient temperature in the furnace inner space 102 reached 1400° C., the ambient temperature of 1400° C. was kept as it was. A temperature distribution in the shelf assembly 113 (each assembly) was measured by the six thermocouples 107 described above. A temperature rise program of the ambient temperature in the furnace was set so that the temperature distribution in the shelf assembly 113 was 12° C. when the ambient temperature in the furnace inner space 102 was 1400° C. Therefore, when the maximum allowable value of the temperature distribution in the shelf assembly 113 at the ambient temperature of 1400° C. in the furnace inner space 102 was 12° C., the temperature rise was controlled so that the temperature distribution at the in-furnace ambient temperature of 1400° C. was 1.0 time the maximum allowable value.
Table 1 shows an integral power consumption (kWh) required for temperature rise until the in-furnace ambient temperature reached 1400° C. from ordinary temperature (25° C.), time (h) required until the in-furnace ambient temperature reached 1400° C. from ordinary temperature (25° C.), the temperature distribution (° C.) in the shelf assembly 113 when the ambient temperature reached 1400° C., and a power (kW) required for holding the ambient temperature of 1400° C. after the in-furnace ambient temperature reached 1400° C. in Reference Example 1.
An operation method was performed in the same manner as in Reference Example 1 except that a plastered wall 110 was not disposed on furnace walls 104 of an electric furnace 101. It is to be noted that refer to
An operation method was performed in the same manner as in Reference Example 1 except that a temperature rise program of an ambient temperature in a furnace inner space 102 was set so that a temperature distribution in a shelf assembly 113 at an ambient temperature of 1400° C. in the furnace inner space 102 was 6° C. When the maximum allowable value of the temperature distribution in the shelf assembly 113 at the ambient temperature of 1400° C. in the furnace inner space 102 was 12° C., the temperature rise was controlled so that the temperature distribution at the in-furnace ambient temperature of 1400° C. was 0.5 time the maximum allowable value. Results of Reference Example 3 are shown in Table 1.
In Reference Example 1, as compared with Reference Example 2, the integral power consumption required for the temperature rise until the in-furnace ambient temperature reached 1400° C. from ordinary temperature (25° C.) was decreased by about 11% (12.5 kWh), and time required until the in-furnace ambient temperature reached 1400° C. from ordinary temperature (25° C.) was reduced by 20% (1.5 h). Reference Examples 2 and 3 had an equal integral power consumption required for the temperature rise until the in-furnace ambient temperature reached 1400° C. from ordinary temperature (25° C.), and equal time required until the in-furnace ambient temperature reached 1400° C. from ordinary temperature (25° C.).
The present invention can be utilized as a housing for heating and a use method of the structure, a heating jig and a use method of the heating jig, and an operation method of a heating device.
Number | Date | Country | Kind |
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2010-037876 | Feb 2010 | JP | national |
2010-063412 | Mar 2010 | JP | national |
This application is a division of U.S. application Ser. No. 13/030,471, having a filing date of Feb. 18, 2011, the entirety of which is incorporated herein by reference.
Number | Date | Country | |
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Parent | 13030471 | Feb 2011 | US |
Child | 14160617 | US |