Continuous firing device

Abstract

To provide a continuous burning apparatus capable of producing burned products with high quality while suppressing the consumption of energy.SOLUTION: A continuous burning apparatus 1 includes a conveyor 2 and a heating section 40. The conveyor 2 has an endless belt 21 and a motor 25. The motor 25 rotates the belt 21 so that a burning substance 91 placed in a belt conveyance area 21C positioned at an upper side in the belt 21 moves in a conveyance direction X. The heating section 40 is constituted of an upper side heating part 40U and a lower side heating part 40L. The upper side heating part 40U is arranged above the belt conveyance area 21C. The lower side heating part 40L is arranged below the belt 21 and at an inner peripheral side of the belt 21. The upper side heating part 40U and the lower side heating part 40L each have a flat heating plate 50 disposed facing the belt conveyance area 21C, and a sheathed heater 60 disposed on a heater surface 52 of the heating plate 50.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a continuous firing apparatus that continuously fires an object to be fired by heating the object to be fired while conveying it in a conveying direction.

Background Art

[0002] Conventionally, for example, in the production of baked confectionery, etc., the dough is baked by passing it through a high-temperature furnace. For example, Patent Document 1 describes a firing apparatus capable of obtaining a large quantity of fired products by conveying an object to be heated by a conveyor into a housing heated to a high temperature by burning gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the firing apparatus described in Patent Document 1 above is of a type that heats the inside of a housing by burning gas. In such a conventional firing apparatus, in order to suppress variations in the firing color of the object to be fired, etc., it is necessary to suppress extreme temperature variations in the space inside the housing. For this reason, for example, it is necessary to ensure a certain distance between the heat source and the object to be fired, and the space inside the housing tends to become large. Further, while ensuring a large space inside the housing, since it is necessary to heat the entire large space, there is a problem that the energy consumption increases.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a continuous firing apparatus capable of manufacturing a high-quality fired product while suppressing energy consumption.

Means for Solving the Problems

[0006] The continuous firing apparatus according to the present invention for solving the above problems is a continuous firing apparatus that continuously fires an object to be fired by heating the object to be fired while conveying it in the conveying direction, and includes an endless belt and a conveyor having a drive unit that rotates the belt in a direction in which the object to be fired placed in a belt conveying region, which is a region located above the belt, moves in the conveying direction, a upper heating unit disposed above the belt conveying region, and a heating unit having a lower heating unit disposed below the belt conveying region and on the inner peripheral side of the belt. The upper heating unit and the lower heating unit each include a flat heating plate provided to face the belt conveying region, and a heater provided on the back surface, which is the side opposite to the belt conveying region side of the heating plate. The heater is a linear heating element and has a plurality of width direction portions extending in the width direction of the belt and connection portions connecting the ends of two width direction portions. The plurality of width direction portions are arranged side by side in the conveyance direction, and the connection portions are located outside the region where the object to be fired is placed in the belt conveyance region in the width direction. A continuous firing apparatus characterized by the above.

[0007] In this continuous firing apparatus, the heat generated by the heater can be evenly distributed by the flat heating plate. That is, it is possible to suppress the occurrence of an extreme temperature difference in the heating plate. For this reason, the upper heating unit and the lower heating unit can each be brought closer to the object to be heated. That is, the upper heating unit can be disposed immediately above the object to be fired. Regarding the lower heating unit, it can be disposed immediately below the belt conveying region on the inner peripheral side of the belt. Thereby, the heating space formed between the heating plate of the upper heating unit and the heating plate of the lower heating unit can be narrowed. Therefore, the heating efficiency of the object to be fired can be increased. Further, since the heat generated by the heater is evenly distributed by the heating plate, it is possible to suppress the occurrence of a difference in the progress of firing of the object to be fired. Therefore, it is possible to manufacture a fired product of high quality while suppressing the energy consumption. In addition, in this continuous firing apparatus, the upper heating section and the lower heating section can uniformly heat the object to be fired in the width direction of the belt. Therefore, high-quality fired products can be stably manufactured.

[0008] Moreover, in the continuous firing apparatus described above, it is preferable that the belt is made of a sheet-like metal. In this continuous firing apparatus, by using a sheet-like metal as the belt, it is possible to suppress heat from escaping to the outside from the space between the upper heating unit and the belt. Thereby, the heating efficiency of the object to be fired can be further increased.

[0010] Further, in the continuous firing apparatus described above, it is preferable that the heating unit includes a plurality of heating regions with different heating temperatures of the object to be fired in the conveying direction. In this continuous firing apparatus, the heating temperature of the object to be fired at each time from the start to the end of firing can be appropriately changed. That is, for example, at the initial stage of firing, by heating at a high temperature, the amount of moisture removed from the object to be fired can be increased, and at the later stage of firing, by heating at a lower temperature than the initial stage, while suppressing burning of the object to be fired, the moisture content of the object to be fired can be finely adjusted. Therefore, high-quality fired products can be manufactured.

[0011] Further, in the continuous firing apparatus described above, in a heating region with the same heating temperature, there is a group of same-temperature heating plates composed of a plurality of heating plates provided in the conveying direction, and it is preferable that two adjacent heating plates in the group of same-temperature heating plates are in a contact state where they are in contact with each other at their ends, at least when the object to be fired is being heated. For example, in the conveying direction, if there is a position where the actual heating temperature is lower than the target temperature, the firing of the object to be fired at that position does not progress, and it becomes necessary to increase the overall length of the firing furnace. However, the larger the firing furnace, the more energy is required for firing. In contrast, in this continuous firing apparatus, in the upper heating part and the lower heating part in a heating region with the same heating temperature, when there are a plurality of heating plates, it is possible to suppress a decrease in the heating temperature even at the boundary between them. Thereby, while suppressing the energy consumption, high-quality fired products can be manufactured.

[0012] Further, in the continuous firing apparatus described above, a heating plate is provided in one heating region which is one of two adjacent heating regions and is located at the end on the side of the other heating region which is the other heating region, and a heating plate provided in the other heating region and located at the end on the side of the one heating region preferably assumes a non-contact state with a gap provided therebetween, at least when heating the object to be fired. In this continuous firing apparatus, it is possible to suppress the temperature of the heating plate from changing under the influence of the heating temperature of the other heating region. Therefore, the object to be fired can be heated at an accurate heating temperature predetermined for each heating region. Therefore, a fired product of high quality can be manufactured.

[0013] Further, in the continuous firing apparatus described above, it is preferable that a heat insulating material having a lower thermal conductivity than the heating plate is provided between the heating plate provided in one heating region which is one of two adjacent heating regions and located at the end on the side of the other heating region which is the other heating region, and the heating plate provided in the other heating region and located at the end on the side of the one heating region. In this continuous firing apparatus, it is possible to suppress the temperature of the heating plate from changing under the influence of the heating temperature of the other heating region. Therefore, the object to be fired can be heated at an accurate heating temperature predetermined for each heating region. Therefore, a fired product of high quality can be manufactured.

Advantages of the Invention

[0014] According to the present invention, there is provided a continuous firing apparatus capable of manufacturing a fired product of high quality while suppressing the energy consumption.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0016] A continuous firing apparatus which is an embodiment according to the present invention will be described in detail with reference to the drawings. First, the first embodiment which is one of the embodiments will be described. Thereafter, for other embodiments, the parts different from the first embodiment will be described.

[0017] <First Embodiment> FIG. 1 is a schematic view showing the whole of a continuous firing apparatus 1 according to this embodiment. As shown in FIG. 1, the continuous firing apparatus 1 includes a conveyor 2 and a firing furnace 3. The continuous firing apparatus 1 heats the object to be fired 91 while conveying it in the conveying direction X indicated by the arrow in FIG. 1. The object to be fired 91 is a solid containing moisture. The moisture of the object to be fired 91 is removed by heating with the continuous firing apparatus 1 and becomes a fired product 92. The continuous firing apparatus 1 can continuously manufacture the fired product 92 by continuously firing the object to be fired 91.

[0018] The fired product 92 is, for example, a small baked confectionery. Specific examples of the fired product 92 in this embodiment include Western confectioneries such as biscuits and cookies mainly made of wheat and containing fats and oils. The object to be fired 91 which is the firing target of the continuous firing apparatus 1 in this embodiment is in a state where the dough obtained by mixing the raw materials of the fired product 92 is formed into a predetermined size.

[0019] The conveyor 2 has a belt 21, a driving roller 22, and a driven roller 23. The belt 21 is an endless conveyor belt formed by connecting a metal sheet in a loop. Specifically, the belt 21 in this embodiment is a sheet-shaped stainless steel. By using the stainless steel sheet as the belt 21, it is possible to suppress solids and liquids that have fallen off the object to be fired 91 from falling off the belt 21, and to easily remove them. For example, it is possible to suppress oil that comes out of the object to be fired 91 during firing from dripping below the belt 21. In addition, the stainless steel sheet belt 21 can easily remove the oil adhering to the surface of the belt 21. Therefore, the continuous firing apparatus 1 can be maintained in a clean state.

[0020] The belt 21 is wound around the outer peripheral surfaces of the driving roller 22 and the driven roller 23. As a result, both left and right ends of the belt 21 in the left-right direction in FIG. 1 are supported by the driving roller 22 and the driven roller 23, respectively. The upper region of the belt 21 located between the driving roller 22 and the driven roller 23 is defined as a belt conveyance region 21C. Also, the outer peripheral surface in the belt conveyance region 21C is defined as an upper surface 21A, and the inner peripheral surface in the belt conveyance region 21C is defined as a lower surface 21B.

[0021] The driving roller 22 is connected to a motor 25 which is a driving source. When the motor 25 is driven, the driving roller 22 rotates in the direction indicated by the arrow in FIG. 1. The driving force of the driving roller 22 is transmitted to the driven roller 23 via the belt 21. The driven roller 23 rotates passively by the driving force being transmitted via the belt 21. In this way, when the driving roller 22 rotates, the belt 21 also rotates and moves.

[0022] When the belt 21 rotates, the belt conveyance area 21C moves in the conveyance direction X. The object to be fired 91 is supplied to a supply position 91A located on the upper surface 21A of the belt conveyance area 21C. The supply position 91A is a position on the upper surface 21A of the belt conveyance area 21C that is upstream of the firing furnace 3 in the conveyance direction X. The object to be fired 91 supplied to the supply position 91A then moves in the conveyance direction X by the movement of the belt conveyance area 21C while being placed on the belt conveyance area 21C. That is, when the belt 21 is rotationally driven, the object to be fired 91 passes through the firing furnace 3. The object to be fired 91 is fired by passing through the firing furnace 3 and becomes a fired product 92. The fired product 92 after passing through the firing furnace 3 is taken out from the continuous firing apparatus 1 at a take-out position 92A located on the upper surface 21A of the belt conveyance area 21C. The take-out position 92A is a position on the upper surface 21A of the belt conveyance area 21C that is downstream of the firing furnace 3 in the conveyance direction X.

[0023] The firing furnace 3 includes a firing space 35 partitioned from the outside by a plurality of outer walls 31. An inlet 32 is formed at a position corresponding to the belt conveyance area 21C in the outer wall 31 forming the upstream end of the firing furnace 3 in the conveyance direction X. An outlet 33 is formed at a position corresponding to the belt conveyance area 21C in the outer wall 31 forming the downstream end of the firing furnace 3 in the conveyance direction X. The inlet 32 is a through-hole for passing the belt 21 of the conveyor 2 and the object to be fired 91 from the outside of the firing space 35 into the firing space 35. The outlet 33 is a through-hole for passing the belt 21 of the conveyor 2 and the fired product 92 from inside the firing space 35 to the outside.

[0024] Inside the firing space 35, a plurality of partition walls 37 are provided. The plurality of partition walls 37 are arranged side by side in the conveying direction X, and divide the firing space 35 in the conveying direction X. In the firing furnace 3 according to the present embodiment, the firing space 35 is divided into seven heating regions 36 by six partition walls 37. In FIG. 1, the plurality of heating regions 36 are shown as heating regions 36A to 36G in order from the upstream side to the downstream side in the conveying direction X. Further, communication holes 38 are formed in the partition walls 37 at positions corresponding to the belt conveying region 21C. The communication hole 38 is a through hole for passing the object to be fired 91 from the upstream side to the downstream side of the adjacent heating regions 36.

[0025] Further, the firing furnace 3 includes a heating unit 40 for firing the object to be fired 91. The heating unit 40 includes an upper heating unit 40U disposed above the belt conveying region 21C and a lower heating unit 40L disposed below the belt conveying region 21C. The lower heating unit 40L is disposed on the inner peripheral side of the belt 21. The upper heating unit 40U and the lower heating unit 40L constitute a pair of heating units 40 provided to face each other with the belt conveying region 21C interposed therebetween.

[0026] The upper heating unit 40U and the lower heating unit 40L of the present embodiment heat the object to be fired 91 at different temperatures in the plurality of heating regions 36. That is, the upper heating unit 40U and the lower heating unit 40L heat the object to be fired 91 at different temperatures in the adjacent heating regions 36. The heating temperatures for each of the heating regions 36A to 36G by the upper heating unit 40U and the lower heating unit 40L are determined in advance based on the moisture content contained in the object to be fired 91 before heating, the degree of baking of the target fired product 92, and the like.

[0027] An exhaust duct 39 is provided at the upper part of the firing furnace 3. The exhaust duct 39 has an exhaust fan connected to the side opposite to the connection side with the firing furnace 3. Thereby, the exhaust duct 39 can discharge the air in the firing space 35 to the outside. The exhaust duct 39 is provided for each of the plurality of heating regions 36. When the object to be fired 91 is fired in the firing furnace 3, the moisture contained in the object to be fired 91 is removed from the object to be fired 91. The moisture removed from the object to be fired 91 will be contained in the air in the firing space 35. If the amount of moisture contained in the air in the firing space 35 becomes too large, the moisture cannot be appropriately removed from the object to be fired 91. In the firing furnace 3, by discharging the air containing moisture from the firing space 35 through the exhaust duct 39, the amount of moisture contained in the air in the firing space 35 can be kept low. Thereby, continuous firing can be appropriately performed.

[0028] FIG. 2 is a cross-sectional view of the continuous firing apparatus 1 at the A-A position shown in FIG. 1. That is, FIG. 2 is a cross-sectional view at the position of the heating region 36A of the continuous firing apparatus 1. However, the same configuration can be adopted for the heating regions 36B to 36G other than the heating region 36A.

[0029] As shown in FIG. 2, the firing furnace 3 is provided with a vertical adjustment unit 80 that can move the upper heating unit 40U up and down. The vertical adjustment unit 80 has a shaft portion 81 and a handle 82 provided on the shaft portion 81. The upper heating unit 40U is provided on the lower end side of the shaft portion 81. The upper end side of the shaft portion 81 penetrates the upper outer wall 31 and protrudes above the firing furnace 3. The handle 82 is provided above the shaft portion 81 and outside the firing furnace 3. The vertical adjustment unit 80 can move the upper heating unit 40U up and down by rotating the handle 82 in one or the other direction around the shaft portion 81. Thereby, the height of the upper heating unit 40U can be adjusted.

[0030] The height adjustment of the upper heating part 40U by the vertical adjustment part 80 is performed, for example, according to the thickness of the object to be fired 91. Specifically, the height adjustment of the upper heating part 40U by the vertical adjustment part 80 is performed, for example, after firing an object to be fired 91 with a certain thickness and before firing an object to be fired 91 with a different thickness. The vertical adjustment part 80 is provided for each of the plurality of heating regions 36 of the upper heating part 40U. Therefore, in the continuous firing apparatus 1, the height of the upper heating part 40U can be adjusted for each heating region 36.

[0031] The continuous firing apparatus 1 includes a control part 85. The control part 85 is for controlling each part in the continuous firing apparatus 1. Specifically, the control part 85 controls, for example, the driving of the motor 25 of the conveyor 2, the heating by the heating part 40, the exhaust from the exhaust duct 39, and the like.

[0032] Next, the configurations of the upper heating part 40U and the lower heating part 40L according to this embodiment will be described. FIG. 3 is an enlarged view of the upper heating part 40U and the lower heating part 40L. FIG. 3 shows the upper heating part 40U and the lower heating part 40L in the heating region 36 with the same heating temperature. As shown in FIG. 3, both the upper heating part 40U and the lower heating part 40L have a plurality of heaters 41 in one heating region 36 respectively.

[0033] The heater 41 has a heating plate 50 and a sheathed heater 60. The heating plate 50 is a flat plate member provided to face the belt conveyance region 21C. The heating plate 50 preferably has a uniform temperature when heating the object to be fired 91. This is because the object to be fired 91 can be heated uniformly. Also, the heating plate 50 preferably can reach the target temperature early after the start of heating. For this reason, it is preferable to use a metal with a low specific heat as the heating plate. Specifically, titanium or stainless steel can be used as the material of the heating plate 50. The heating plate 50 has a heating surface 51 on the belt conveyance region 21C side and a heater surface 52 which is the back surface of the heating surface 51.

[0034] The heating plate 50 faces the belt conveyance area 21C at the heating surface 51. A sheathed heater 60 is provided in contact with the heater surface 52 of the heating plate 50. The heater 41 of the upper heating unit 40U is provided with the heating surface 51 of the heating plate 50 facing downward. The heater 41 of the lower heating unit 40L is provided with the heating surface 51 of the heating plate 50 facing upward. That is, the heater 41 of the upper heating unit 40U and the heater 41 of the lower heating unit 40L are attached upside down. The sheathed heater 60 is a heating element that generates heat when electricity flows through it and heats the heating plate 50 by heat conduction.

[0035] FIG. 4 is a plan view of the upper heating unit 40U in the heating region 36 where the heating temperature is the same. Note that the heater 41 of the lower heating unit 40L has the same configuration as that of the upper heating unit 40U. As shown in FIG. 4, the heating plate 50 is wider than the belt width 21Y of the belt 21 in the width direction Y of the belt 21. A plurality of objects to be fired 91 are placed side by side in the conveyance direction X and the width direction Y in the belt conveyance area 21C. FIG. 4 shows the width 91Y of the area where the objects to be fired 91 are placed in the belt conveyance area 21C.

[0036] The sheathed heater 60 is linear and is provided in the conveyance direction X while being bent so as to meander in the width direction Y of the belt 21. The ends of the linear sheathed heater 60 are connected to the control unit 85. Thereby, the control unit 85 can control the heat generation of the sheathed heater 60. The control unit 85 can cause the sheathed heater 60 to generate heat at a predetermined temperature.

[0037] Further, the sheathed heater 60 has a plurality of linear portions 61 extending in the width direction Y. The plurality of linear portions 61 are provided side by side in the conveyance direction X. Equal intervals of gaps are provided between any two adjacent linear portions 61. Therefore, the sheathed heater 60 can uniformly heat the area of the heating plate 50 corresponding to the area where the objects to be fired 91 are placed in the conveyance direction X.

[0038] The sheathed heater 60 has a bent portion 62 at one end in the width direction Y of the straight portion 61. The bent portion 62 connects two adjacent straight portions 61 at their one ends. Also, in this embodiment, as shown in FIG. 4, the length in the width direction Y of the straight portion 61 is the same as the belt width 21Y. As a result, all of the bent portions 62 are located outside the region where the object to be fired 91 is placed in the width direction Y. Therefore, the sheathed heater 60 can uniformly heat the region corresponding to the region where the object to be fired 91 is placed in the heating plate 50 in the width direction Y.

[0039] That is, the sheathed heater 60 is set to a constant temperature when generating heat. When the sheathed heater 60 generates heat, the heating plate 50 in contact with the sheathed heater 60 is heated by heat transfer from the sheathed heater 60. The heating plate 50 is maintained at a uniform temperature as a whole by the heating from the sheathed heater 60. That is, in the heater 41, the heat of the sheathed heater 60 that has generated heat is evenly distributed by the heating plate 50. As a result, the heater 41 heats the object to be heated facing the heating surface 51 of the heating plate 50 by heat radiation. And the degree of heating by the heat radiation of the heating surface 51 is uniform without unevenness in both the conveyance direction X and the width direction Y.

[0040] The heater 41 of this embodiment can control the heating temperature for the entire wide heating surface 51 in both the conveyance direction X and the width direction Y in this way. For this reason, while using the sheathed heater 60 which is a linear heating element, a wide range of heating temperatures can be controlled by controlling the temperature of the sheathed heater 60. That is, the number of sheathed heaters 60 that require temperature control is small, and the wiring work with the control unit 85 is easy. Also, the number of sheathed heaters 60 that require temperature control is small, and it is suppressed that the control becomes complicated.

[0041] Further, as shown in FIGS. 3 and 4, the upper heating section 40U and the lower heating section 40L of this embodiment each have a plurality of heaters 41 in the conveyance direction X. That is, the upper heating section 40U has an upper same-temperature heating plate group 50SU composed of a plurality of heating plates 50 within the same heating region 36. Also, the lower heating section 40L has a lower same-temperature heating plate group 50SL composed of a plurality of heating plates 50 within the same heating region 36.

[0042] During firing, the control unit 85 controls the sheathed heaters 60 of the plurality of heaters 41 that constitute the upper heating section 40U in the heating region 36 where the heating temperature is the same to be at the same temperature. Then, during firing, the adjacent heating plates 50 of the upper same-temperature heating plate group 50SU are in a contact state where their ends in the conveyance direction X are in contact with each other. The same applies to the lower heating section 40L.

[0043] For this reason, in the heating region 36 where the heating temperatures of the upper heating section 40U and the lower heating section 40L are the same, the fired object 91 can be heated to the same extent at the boundary between two adjacent heaters 41 as at locations other than the boundary. That is, in the heating region 36 where the heating temperatures are the same, the upper heating section 40U and the lower heating section 40L can uniformly heat the object to be heated in the conveyance direction X despite having a plurality of heaters 41. Note that the adjacent heating plates 50 only need to be in a contact state during firing. That is, when the heating plate 50 expands as the temperature rises, a gap may be provided between the adjacent heating plates 50 at normal temperature when firing is not being performed.

[0044] The upper heating section 40U and the lower heating section 40L having such heaters 41 can appropriately heat the fired object 91 through the heating surface 51 of the heating plate 50 when the sheathed heater 60 generates heat.

[0045] As shown in FIG. 3, the heating surface 51 of the heater 41 of the upper heating unit 40U faces the upper surface 21A of the belt conveyance area 21C. The heating plate 50 is a flat plate provided facing the belt conveyance area 21C. That is, the heating surface 51 of the heating plate 50 has a shape along the belt conveyance area 21C, and the distance from the upper surface 21A of the belt conveyance area 21C is constant. Then, the heater 41 of the upper heating unit 40U heats the object to be fired 91 placed on the upper surface 21A of the belt conveyance area 21C by thermal radiation from above.

[0046] Therefore, the degree of heating of the object to be fired 91 by the heater 41 of the upper heating unit 40U is uniform in the width direction Y in each heating area 36. That is, the heater 41 of the upper heating unit 40U can heat any of the objects to be fired 91 placed side by side in the width direction Y to a certain degree. Also, the degree of heating of the object to be fired 91 by the heater 41 of the upper heating unit 40U is uniform in the conveyance direction X. That is, the heater 41 of the upper heating unit 40U can always heat the object to be fired 91 moving in the conveyance direction X to a certain degree in each heating area 36.

[0047] Also, the heating surface 51 of the heater 41 of the lower heating unit 40L faces the lower surface 21B of the belt conveyance area 21C. The heating plate 50 is a flat plate provided facing the belt conveyance area 21C. That is, the heating surface 51 of the heating plate 50 has a shape along the belt conveyance area 21C, and the distance from the lower surface 21B of the belt conveyance area 21C is constant. Then, the heater 41 of the lower heating unit 40L heats the belt conveyance area 21C by thermal radiation from below.

[0048] Therefore, the degree of heating of the belt conveyance area 21C by the heater 41 of the lower heating unit 40L is uniform in the width direction Y in each heating area 36. That is, the heater 41 of the lower heating unit 40L can heat the belt conveyance area 21C to a certain extent in the width direction Y. Also, the degree of heating of the belt conveyance area 21C by the heater 41 of the lower heating unit 40L is uniform in the conveyance direction X. That is, the heater 41 of the lower heating unit 40L can always heat the belt conveyance area 21C moving in the conveyance direction X to a certain extent in each heating area 36.

[0049] Further, the object to be fired 91 is placed on the upper surface 21A of the belt conveyance area 21C heated by the lower heating unit 40L. Thus, the belt conveyance area 21C heats the object to be fired 91 placed on the upper surface 21A by heat conduction. That is, the heater 41 of the lower heating unit 40L can heat all the objects to be fired 91 arranged side by side in the width direction Y through the belt conveyance area 21C to a certain extent in each heating area 36. Furthermore, the heater 41 of the lower heating unit 40L can always heat the object to be fired 91 moving in the conveyance direction X through the belt conveyance area 21C to a certain extent in each heating area 36.

[0050] Thus, in this embodiment, the upper heating unit 40U and the lower heating unit 40L can uniformly heat in the conveyance direction X and the width direction Y in each heating area 36. That is, in the continuous firing apparatus 1 of this embodiment, the object to be heated is not heated more strongly, for example, at a position directly below the heater than at the position of the gap between a plurality of heaters. Therefore, as shown in FIG. 3, the upper heating unit 40U can be arranged at a position close to the object to be fired 91. Also, the lower heating unit 40L can be arranged at a position close to the belt conveyance area 21C which is the object to be heated.

[0051] Here, generally, the heating efficiency by a heat source tends to decrease as the distance from the heat source to the object to be heated increases. In contrast, in the continuous firing apparatus 1 of the present embodiment, the upper heating unit 40U and the lower heating unit 40L can be arranged at positions close to the object to be fired 91 and the belt conveyance region 21C, which are the respective objects to be heated. For this reason, the upper heating unit 40U can efficiently heat the object to be fired 91. Also, the lower heating unit 40L can efficiently heat the belt conveyance region 21C. Thereby, the upper heating unit 40U and the lower heating unit 40L can appropriately heat the object to be fired 91 under desired conditions while suppressing the calorific value of the sheathed heater 60.

[0052] Also, in the continuous firing apparatus 1, the height of the heating space 42 formed in the gap between the heating plate 50 of the heater 41 of the upper heating unit 40U and the heating plate 50 of the heater 41 of the lower heating unit 40L is narrow. For this reason, the heat discharged from the heating space 42 can be reduced. Thus, the upper heating unit 40U and the lower heating unit 40L can heat the object to be fired 91 more efficiently.

[0053] Also, as described above, the upper heating unit 40U and the lower heating unit 40L can uniformly perform heating by the heating surface 51 in both the conveyance direction X and the width direction Y in each heating region 36. For this reason, a plurality of objects to be fired 91 can be closely arranged in any direction of the conveyance direction X and the width direction Y. Thus, the continuous firing apparatus 1 can manufacture a large amount of fired products 92 in a short time.

[0054] FIG. 5 is a view showing the upper heating unit 40U and the lower heating unit 40L at the boundary of the heating region 36. FIG. 5 shows the boundary between the heating region 36A and the heating region 36B as an example of the boundary between adjacent heating regions 36. The same applies to the boundaries between other adjacent heating regions 36. In the continuous firing apparatus 1, as described above, the heating temperatures of the objects to be fired 91 are different between adjacent heating regions 36. That is, the sheathed heaters 60 of the upper heating unit 40U in the heating region 36A and the sheathed heaters 60 of the upper heating unit 40U in the heating region 36B are controlled to different temperatures. The same applies to the lower heating unit 40L.

[0055] FIG. 5 shows a heater 41 that is located most downstream in the conveyance direction X among a plurality of heaters 41 that constitute the upper heater 40U and the lower heater 40L of the heating region 36A. Further, FIG. 5 shows a heater 41 that is located most upstream in the conveyance direction X among a plurality of heaters 41 that constitute the upper heater 40U and the lower heater 40L of the heating region 36B. That is, FIG. 5 shows a heater 41 provided in the heating region 36A and located at the end on the heating region 36B side, and a heater 41 provided in the heating region 36B and located at the end on the heating region 36A side.

[0056] And, as shown in FIG. 5, the heating plate 50 of the upper heating unit 40U of the heating region 36A and the heating plate 50 of the upper heating unit 40U of the heating region 36B are not in contact with each other, and a gap S is provided therebetween. The same applies to the lower heating unit 40L. Note that FIG. 5 shows the state during firing.

[0057] That is, in the continuous firing apparatus 1, the heating plates 50 of two adjacent heating regions 36 are each configured to be less affected by the temperature of the other during firing. For this reason, the upper heating unit 40U and the lower heating unit 40L can heat the object to be fired 91 at accurate temperatures predetermined for their respective heating regions 36. Thereby, the continuous firing apparatus 1 can manufacture fired products 92 of high quality.

[0058] <Example> Next, an example of this embodiment will be described. The inventors conducted an experiment of firing an object to be fired using each of the firing apparatuses of an example according to the present invention and a comparative example different from the present invention.

[0059] In the examples, the continuous firing apparatus 1 described in the above first embodiment was used to fire the object to be fired. As the object to be fired, a dough for biscuit having a water content of 2% and formed into a thickness of 4 mm was used. Also, in the examples, the heating temperature by the heating unit 40 was set such that the temperature became lower in the downstream heating region 36 in the transport direction X. Specifically, the heating region 36A was set to 195°C, the heating region 36B was set to 190°C, the heating region 36C was set to 185°C, the heating region 36D was set to 175°C, the heating region 36E was set to 165°C, the heating region 36F was set to 160°C, and the heating region 36G was set to 155°C. Further, as the heating plate 50, a titanium plate having a thickness of 1 mm was used. Then, the size of the gap between the heating plate 50 of the upper heating unit 40U and the heating plate 50 of the lower heating unit 40L was set to 13 mm, and adjustment was made so that the heating space 42 was formed as narrow as possible.

[0060] In the comparative example, while heating the inside of the firing furnace by combustion of gas, firing was performed by a device that conveys the object to be fired inside by a conveyor. As the heating source, a line burner was used. Also in the comparative example, the same object as in the examples was used as the object to be fired. Further, also in the comparative example, heating was performed so that the heating temperature became lower toward the downstream side in the transport direction, and the transition of the heating temperature was made to be approximately the same as that in the examples. That is, also in the comparative example, under the condition that the object to be fired was heated at approximately the same heating temperature as in the examples at each time from the start to the end of firing.

[0061] As a result of comparing the fired products obtained in each of the examples and the comparative example, it was confirmed that the quality such as taste, texture, and baking color was comparable. That is, it was confirmed that, according to the example of the present invention, a high-quality fired product comparable to the comparative example using the conventional method of heating the inside of the furnace by combustion of gas can be obtained. Also, in the example, the firing apparatus could be configured at a lower cost than in the comparative example. As a result, it was also confirmed that, in the example, the fired product can be manufactured at a lower cost than in the comparative example.

[0062] Furthermore, in the comparative example, it is necessary to raise the temperature of the entire space inside the firing furnace. For this reason, even if the outer wall of the firing furnace has a heat-insulating structure, the environmental temperature around the firing apparatus may rise, which may impose a burden on the operator. On the other hand, in the continuous firing apparatus 1 of the embodiment, only the heating space 42 between the heating plates 50 of the upper heating section 40U and the lower heating section 40L needs to be heated to a high temperature. That is, even inside the firing furnace 3, other than the heating space 42, it does not become so hot. For this reason, in the embodiment, the rise in the environmental temperature around the apparatus is suppressed. Thereby, in the embodiment, the working environment of the operator can be maintained in a comfortable environment.

[0063] As described in detail above, the continuous firing apparatus 1 according to the present embodiment can continuously fire the object to be fired 91 by heating it while conveying it in the conveying direction X. The continuous firing apparatus 1 includes a conveyor 2 and a heating unit 40. The conveyor 2 has an endless belt 21 and a motor 25 that rotates the belt 21. The motor 25 rotates the belt 21 so that the object to be fired 91 placed in the belt conveyance region 21C located above the belt 21 moves in the conveyance direction X. The heating unit 40 is composed of an upper heating unit 40U and a lower heating unit 40L. The upper heating unit 40U is disposed above the belt conveyance region 21C. The lower heating unit 40L is located below the belt 21 and is disposed on the inner peripheral side of the belt 21. And each of the upper heating unit 40U and the lower heating unit 40L has a flat heating plate 50 provided to face the belt conveyance region 21C, and a sheathed heater 60 provided on the heater surface 52 of the heating plate 50. With such a configuration, the upper heating unit 40U and the lower heating unit 40L can make the heat generated by the sheathed heater 60 uniform by the heating plate 50. That is, it is possible to suppress the occurrence of an extreme temperature difference in the heating plate 50. For this reason, both the upper heating unit 40U and the lower heating unit 40L can be brought closer to the object to be heated. Therefore, the object to be fired 91 can be efficiently fired in a narrow heating space 42. Further, since the heat generated from the sheathed heater 60 is made uniform by the heating plate 50, it is possible to suppress the occurrence of a difference in the progress of firing of the object to be fired 91. That is, it is possible to suppress underfiring and burning of the object to be fired 91. Therefore, the continuous firing apparatus 1 can manufacture a high-quality fired product 92 while suppressing the energy consumption.

[0064] In addition, in the conveyor 2, a stainless steel sheet is used as the belt 21. By using such a sheet-shaped metal belt 21, the deposits adhering to the belt 21 can be easily removed. Further, it is possible to suppress the oil and the like coming out of the object to be fired 91 during firing from dripping below the belt 21. That is, it is possible to suppress the adhesion of oil to the lower heating unit 40L. As a result, the fired product 92 can be manufactured with stable quality over a long period in a clean environment.

[0065] Note that as the belt 21, a mesh belt formed by, for example, weaving linear metal in a mesh pattern can also be used. When using a mesh belt as the belt 21, it is preferable to use one with a low aperture ratio. Specifically, the aperture ratio of the mesh belt used as the belt 21 is preferably 10% or less, more preferably 8% or less. Also, as the mesh belt, a herringbone type is preferable. This is because the herringbone type is generally formed by tightly weaving wire materials with a gap smaller than the wire diameter, resulting in a low aperture ratio. As such a mesh belt, specifically, for example, a T&H type mesh belt manufactured by HARIKAWA Wire Mesh Co., Ltd. with high tensile strength can be used. By using such a mesh belt as the belt 21, it is possible to suppress the falling of debris (solids) and oil (liquids) that have fallen off the object to be fired 91 from the belt 21. Also, the mesh belt tends to be less expensive than a sheet-like metal belt. Therefore, considering the cost of the continuous firing apparatus 1 and the texture formed on the fired product 92, a mesh belt can also be adopted as the belt 21. On the other hand, when using a sheet-like metal as the belt 21, oil on the belt 21 and foreign substances formed by abrasion of members such as the conveyor 2 including the belt 21 during conveyance are more likely to be appropriately removed from the belt 21 compared to when using a mesh belt. Also, by using a sheet-like metal as the belt 21, it is possible to suppress heat from escaping to the outside from the space in the gap between the belt conveyance region 21C and the upper heating unit 40U. That is, by using a sheet-like metal as the belt 21, the object to be fired 91 can be heated more efficiently compared to when using a mesh belt. Therefore, from these viewpoints, it is preferable to use a sheet-like metal as the belt 21.

[0066] Further, the sheathed heater 60 is a linear heating element and has a plurality of straight portions 61 extending in the width direction Y of the belt 21 and bent portions 62 connecting the ends of the two straight portions 61. The plurality of straight portions 61 are arranged side by side in the conveying direction X. And the bent portion 62 is located outside the region on which the object to be fired 91 is placed in the belt conveying region 21C in the width direction Y. Thereby, the upper heating portion 40U and the lower heating portion 40L can uniformly heat the object to be fired 91 in the width direction Y. Different from this embodiment, when the heating temperature is non-uniform in the width direction, the firing condition will be different for each fired product fired at different positions in the width direction. That is, there is a risk that the quality of the fired product will vary. In contrast, the continuous firing apparatus 1 according to this embodiment can stably manufacture a fired product 92 of high quality.

[0067] Further, the upper heating portion 40U and the lower heating portion 40L heat the object to be fired 91 at different heating temperatures for each of the plurality of heating regions 36 provided in the conveying direction X. Thereby, the heating temperature of the object to be fired 91 at each time from the start to the end of firing can be appropriately changed. That is, for example, at the initial stage of firing, by heating at a high temperature, a large amount of moisture removed from the object to be fired 91 can be increased. At the later stage of firing, by heating at a lower temperature than the initial stage, while suppressing burning of the object to be fired 91, the moisture content of the object to be fired 91 can be finely adjusted. Therefore, a fired product 92 of high quality can be manufactured.

[0068] In addition, in the upper heating section 40U, a plurality of heating plates 50 are provided in the heating region 36 having the same heating temperature in the conveying direction X, and an upper same-temperature heating plate group 50SU is formed. And, in the upper same-temperature heating plate group 50SU, two adjacent heating plates 50 are in a contact state where they are in contact with each other at their ends, at least when the object to be fired 91 is heated. Similarly, the lower heating section 40L also has a lower same-temperature heating plate group 50SL composed of a plurality of heating plates 50 in the heating region 36 having the same heating temperature. Further, two adjacent heating plates 50 in the lower same-temperature heating plate group 50SL are in a contact state where they are in contact with each other at their ends, at least when the object to be fired 91 is heated. Thereby, in the upper heating section 40U and the lower heating section 40L in the heating region 36 having the same heating temperature, even when there are a plurality of heating plates 50, it is possible to suppress a decrease in the heating temperature at the boundary. Different from this embodiment, when there is a conveying position where the actual heating temperature is lower than the target temperature in the conveying direction X, the firing of the object to be fired at that position does not proceed, and it becomes necessary to increase the overall length of the firing furnace or the like. However, the larger the firing furnace is, the more energy is required for firing. On the other hand, in the continuous firing apparatus 1 according to this embodiment, it is possible to manufacture a fired product 92 of high quality while suppressing the energy consumption.

[0069] In addition, in the continuous firing apparatus 1, for example, the heating plate 50 located at the end on the heating region 36B side within the heating region 36A and the heating plate 50 located at the end on the heating region 36A side within the heating region 36B are in a non-contact state where a gap S is provided between them. The same applies to other adjacent heating regions 36. That is, the heating plates 50 located in adjacent heating regions 36 are in a non-contact state, at least when the object to be fired 91 is heated. Thereby, it is possible to suppress the temperature of the heating plate 50 from changing due to the influence of the heating temperature of other heating regions 36. Therefore, the object to be fired 91 can be heated at an accurate heating temperature determined in advance for each heating region 36. Therefore, a fired product 92 of high quality can be manufactured.

[0070] <Second Embodiment> Next, a second embodiment different from the above-described first embodiment will be described. Also in this embodiment, the configuration of the continuous firing apparatus is generally the same as that of the above-described embodiment. In the continuous firing apparatus of this embodiment, the configuration at the ends of the plurality of heating plates is different from that of the above-described embodiment.

[0071] FIG. 6 is a view showing the upper heating section 140U and the lower heating section 140L of the continuous firing apparatus 10 according to this embodiment. FIG. 6 shows the configurations of the upper heating section 140U and the lower heating section 140L in the same heating region 36. As shown in FIG. 6, also for the upper heating section 140U and the lower heating section 140L of this embodiment, a plurality of heaters 41 are respectively provided in one heating region 36. The heater 41 of this embodiment also has the same sheathed heater 60 as in the above-described embodiment. Further, the upper heating section 140U constituted by a plurality of heaters 41 has an upper same-temperature heating plate group 150SU composed of a plurality of heating plates 150. Further, the lower heating section 140L constituted by a plurality of heaters 41 has a lower same-temperature heating plate group 150SL composed of a plurality of heating plates 150.

[0072] Also in this embodiment, similar to the above-described embodiment, the adjacent heating plates 150 of the upper same-temperature heating plate group 150SU are in a contact state where they contact each other at the ends in the conveyance direction X during firing. However, the heating plate 150 of this embodiment has a different end shape from the adjacent heating plates 150 of the upper same-temperature heating plate group 150SU.

[0073] Specifically, the side surfaces of the ends of the heating plates 150 where the adjacent heating plates 150 exist in the upper same-temperature heating plate group 150SU are inclined surfaces facing each other together with the side surfaces of the adjacent heating plates 150. The left side surface of the right heating plate 150 in FIG. 6 is an inclined surface that protrudes more to the left toward the upper side. The right side surface of the left heating plate 150 is an inclined surface that protrudes more to the right toward the lower side.

[0074] Therefore, when the length of the left end of the right heating plate 150 increases in the conveyance direction X due to thermal expansion, it becomes warped upward along the inclined surface at the right end of the left heating plate 150. When the length of the right end of the left heating plate 150 increases in the conveyance direction X due to thermal expansion, it becomes warped upward along the inclined surface at the left end of the right heating plate 150. As a result, it is possible to prevent two adjacent heating plates 150 in the upper same-temperature heating plate group 150SU from being damaged by compressive stress during thermal expansion. Therefore, two adjacent heating plates 150 in the upper same-temperature heating plate group 150SU can be brought into contact with each other while suppressing damage due to thermal expansion or the like during heating of the object to be fired 91.

[0075] Note that the end shape of the heating plate 150 is not limited to the shape shown in FIG. 6. That is, the end shape of the heating plate 150 may be any shape that can be deformed in a direction different from the conveyance direction X when it thermally expands in the conveyance direction X and comes into contact with an adjacent heating plate 150 in the upper same-temperature heating plate group 150SU. That is, the end of the heating plate 150 may be any shape that moves in a direction intersecting the conveyance direction X more than at normal temperature when it comes into contact with an adjacent heating plate 150 in the upper same-temperature heating plate group 150SU during heating of the object to be fired 91. The same applies to the lower same-temperature heating plate group 150SL.

[0076] FIG. 7 is a diagram showing the upper heating section 140U and the lower heating section 140L at the boundary of the heating region 36 of the continuous firing apparatus 10 according to the present embodiment. FIG. 7 shows the boundary between the heating region 36A and the heating region 36B as an example of the boundary between adjacent heating regions 36. The same applies to the boundaries between other adjacent heating regions 36. Also in the continuous firing apparatus 10, the heating temperature of the object to be fired 91 is different between adjacent heating regions 36. FIG. 7 shows a heater 41 provided in the heating region 36A and located at the end on the heating region 36B side, and a heater 41 provided in the heating region 36B and located at the end on the heating region 36A side.

[0077] As shown in FIG. 7, the heating plate 150 of the upper heating unit 140U in the heating region 36A and the heating plate 150 of the upper heating unit 140U in the heating region 36B are not in direct contact with each other, and a gap S is provided therebetween. And a heat insulating material 170 is sandwiched in the gap S. The heat insulating material 170 is fixed to, for example, either one of two adjacent heating plates 150.

[0078] The heat insulating material 170 is made of a material having a lower thermal conductivity than the heating plate 150. Specifically, for example, as the material of the heat insulating material 170, a material having a heat resistant temperature equal to or higher than the heat generation temperature of the sheathed heater 60 is preferable. Specifically, for example, as the heat insulating material 170, a phenolic resin-based foamed heat insulating material having a heat resistant temperature of 400° C. or higher, a ceramic-based fibrous heat insulating material such as alumina fiber or glass fiber can be used. The same applies to the lower heating unit 140L, and the heat insulating material 170 is sandwiched in the gap S between the heating plates 150 of the adjacent heating regions 36.

[0079] Thereby, the continuous firing apparatus 1 is configured such that the heating plates 150 of two adjacent heating regions 36 are less likely to be affected by the temperature of the other. For this reason, the upper heating unit 140U and the lower heating unit 140L can heat the object to be fired 91 at an accurate temperature predetermined for each heating region 36. Therefore, the continuous firing apparatus 1 can manufacture a fired product 92 of high quality.

[0080] As described in detail above, even in the continuous firing apparatus 10 according to this embodiment, the upper heating unit 140U and the lower heating unit 140L heat the object to be fired 91 at different heating temperatures for each of the plurality of heating regions 36 provided in the transport direction X. And, for example, between the heating plate 150 located at the end on the heating region 36B side within the heating region 36A and the heating plate 150 located at the end on the heating region 36A side within the heating region 36B, a heat insulating material 170 is sandwiched. The same applies to other adjacent heating regions 36. Thereby, it is possible to suppress the temperature of the heating plate 150 from changing under the influence of the heating temperature of other heating regions 36. Therefore, the object to be fired 91 can be heated at an accurate heating temperature determined in advance for each heating region 36. Therefore, a fired product 92 of high quality can be manufactured.

[0081] Furthermore, even in the continuous firing apparatus 10, a plurality of heating plates 150 are provided in the upper heating unit 140U in the transport direction X within the heating region 36 having the same heating temperature, and the upper same-temperature heating plate group 150SU is configured. And the end portion of the heating plate 150 is in a shape that moves in a direction intersecting the transport direction X more than at normal temperature by contacting the adjacent heating plate 150 in the upper same-temperature heating plate group 150SU when heating the object to be fired 91. It is possible to prevent, for example, two adjacent heating plates 150 in the upper same-temperature heating plate group 150SU from being damaged by compressive stress during thermal expansion. Therefore, two adjacent heating plates 150 in the upper same-temperature heating plate group 150SU can be brought into contact with each other while suppressing damage due to thermal expansion and the like during heating of the object to be fired 91. The same applies to the lower same-temperature heating plate group 150SL.

[0082] Also, in this way, in the continuous firing apparatus 10, the thermal expansion of the heating plate 150 in the conveyance direction X can be absorbed at the boundary between two adjacent heating plates 150 in the upper same-temperature heating plate group 150SU. Therefore, it is possible to suppress the narrowing of the gap S between the heating plates 150 existing at the boundary between two adjacent heating regions 36 due to the thermal expansion of the heating plate 150. The same applies to the lower same-temperature heating plate group 150SL. That is, it is possible to suppress the heating plate 150 that has thermally expanded from receiving a force in the direction in which the heat insulating material 170 is compressed. Therefore, it is also possible to suppress damage to the heat insulating material 170 due to the thermal expansion of the heating plate 150 and the like.

[0083] <Modification Example> In the above-described embodiments, parts of different embodiments can also be combined. For example, a part of the second embodiment can be combined with the continuous firing apparatus of the first embodiment. Specifically, in the second embodiment, a structure that can absorb the thermal expansion of the heating plate at the boundary between two adjacent heating plates in the same-temperature heating plate group was described. Such a structure may be applied to the continuous firing apparatus of the first embodiment. Also, in the second embodiment, a configuration in which a heat insulating material is provided in the gap between the heating plates located at the boundary between two adjacent heating regions was described. Such a structure may be applied to the continuous firing apparatus of the first embodiment.

[0084] Also, the above-described embodiments can be modified without changing the gist of the present invention. For example, in the above-described embodiments, biscuits and cookies were cited as examples of fired products for explanation. However, for example, it may be possible to manufacture other fired products. However, as a whole of the configuration described in the above embodiments, it is a configuration particularly suitable for the manufacture of Western confectionery mainly made of wheat and containing fats and oils.

[0085] In the above-described embodiment, the heating unit has been described as including seven heating regions with different firing temperatures of the object to be fired in the conveying direction. However, the number of heating regions with different heating temperatures is not limited to seven. For example, it is sufficient that the heating temperatures of two adjacent heating regions are different, and heating regions with the same heating temperature may be provided among a plurality of heating regions.

[0086] In the above-described embodiment, an example in which a sheathed heater is adopted as the heater for the upper heating unit and the lower heating unit has been described. However, for example, other types of heaters may be used. Also, for example, the path of the sheathed heater is not limited to the pattern shown in FIG. 4. For example, the portion described as the straight portion 61 may have a shape that extends in the width direction Y and meanders in the conveying direction X.

[0087] In the above-described embodiment, the continuous firing apparatus 1 for firing Western-style confectionery such as biscuits and cookies mainly made of wheat and containing fats and oils has been specifically described. However, a continuous firing apparatus having the same configuration as the continuous firing apparatus 1 can be used not only for the Western-style confectionery according to the above-described embodiment, but also for heat treatment of tea, roasting of sesame or coffee, roasting of nuts (for example, almonds, cashew nuts, peanuts, etc.). In such a case, the heating temperature and the like of the continuous firing apparatus may be determined according to the object to be fired.

Explanation of Reference Numerals

[0088] 1, 10 Continuous firing apparatus 2 Conveyor 21 Belt 21C Belt conveyance region 25 Motor 36 Heating region 40 Heating unit 40U, 140U Upper heating unit 40L, 140L Lower heating unit 50, 150 Heating plate 50SU, 150SU Upper same-temperature heating plate group 50SL and 150SL lower side same-temperature heating plate group 60 Sheathed heater 61 Straight part 62 Bent part 91 Object to be fired 92 Fired product 170 Heat insulator S Gap

Claims

1. A continuous firing apparatus for continuously firing a workpiece by heating the workpiece while conveying it in a conveying direction, comprising: a conveyor having an endless belt and a drive unit that rotates the belt in a direction in which the workpiece placed in a belt conveying region, which is a region located above the belt, moves in the conveying direction; a heating unit including an upper heating unit disposed above the belt conveying region and a lower heating unit disposed below the belt conveying region and on the inner peripheral side of the belt; each of the upper heating unit and the lower heating unit has a flat heating plate provided to face the belt conveying region and a heater provided on a back surface, which is the side opposite to the belt conveying region side of the heating plate; the heater is a linear heating element and has a plurality of width direction portions extending in the width direction of the belt and a connecting portion connecting ends of the two width direction portions; the plurality of width direction portions are arranged side by side in the conveying direction; the connecting portion is located outside a region on the belt conveying region where the workpiece is placed in the width direction, and the continuous firing apparatus is characterized by this.

2. The continuous firing apparatus according to Claim 1, characterized in that the belt is made of a sheet-like metal.

3. The continuous firing apparatus according to Claim 1 or Claim 2, characterized in that the heating unit includes a plurality of heating regions having different heating temperatures of the workpiece in the conveying direction.

4. In the continuous firing apparatus according to Claim 3, it has a same temperature heating plate group composed of a plurality of heating plates provided in the conveying direction within the heating region having the same heating temperature, and two adjacent heating plates in the same temperature heating plate group are in a contact state where they are in contact with each other at their ends, at least when the workpiece is being heated, and the continuous firing apparatus is characterized by this.

5. In the continuous firing apparatus according to Claim 3 or Claim 4, A continuous firing apparatus, comprising: a heating plate provided in one heating region, which is one of two adjacent heating regions, and located at an end on the side of the other heating region, which is the other heating region; and a heating plate provided in the other heating region and located at an end on the side of the one heating region, wherein the heating plates are in a non-contact state with a gap therebetween, at least during heating of an object to be fired. **Claim 6**: The continuous firing apparatus according to claim 3 or claim 4, wherein a heat insulating material having a lower thermal conductivity than that of the heating plate is provided between the heating plate provided in one heating region, which is one of two adjacent heating regions, and located at an end on the side of the other heating region, which is the other heating region, and the heating plate provided in the other heating region and located at an end on the side of the one heating region.

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