JP2020071005A - heating furnace - Google Patents

Abstract

To suppress the variation of a thermal dose to a workpiece.SOLUTION: A heating furnace 100 comprises: a heating chamber 110; a closed type gas heater 160 arranged at the heating chamber 110; a first exhaust passage connected to the closed type gas heater 160; a preheating chamber 170 connected to the first exhaust passage; a pair of rotors 144a, 144b; and an endless carrier belt 142 stretched to the pair of rotors 144a, 144b, in which a part is located in the preheating chamber 170 and the other is located in the heating chamber 110. The carrier belt 142 is heated by the preheating chamber 170.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to heating furnaces.

  2. Description of the Related Art Conventionally, a heating furnace provided with a conveyor belt such as a belt has been widely used (eg, Patent Document 1). A part of the transport zone is located in the heating chamber. The transport zone transports the work into the heating chamber. The work is heated in the heating chamber while being transferred in the transfer zone. The heated work is carried out of the heating chamber by the carrying zone.

Japanese Patent No. 6096264

  As described above, in the heating furnace having the transfer zone, if the temperature of the transfer zone itself varies, the amount of heat applied to the work also varies.

  An object of the present disclosure is to provide a heating furnace capable of suppressing variations in the amount of heat applied to a work.

  In order to solve the above problems, a heating furnace according to an aspect of the present disclosure is connected to a heating chamber, a gas heater arranged in the heating chamber, a first exhaust passage connected to the gas heater, and a first exhaust passage. A preheating chamber, a pair of rotating bodies, and an endless transfer belt which is stretched between the pair of rotating bodies, a part of which is located in the preheating chamber and another part of which is located inside the heating chamber.

  A second exhaust passage may be provided, which is connected to the preheating chamber and discharges the exhaust gas supplied to the preheating chamber.

  A branch passage that branches from the first exhaust passage and communicates with the outside, and a connection portion of the first exhaust passage with the branch passage, or a control valve provided on the preheating chamber side of the connection portion, and the preheating chamber. And a flow rate control unit that controls the control valve based on the temperature.

  At least a part of the preheating chamber may be located between the heating chamber and a rotating body on the upstream side of the heating chamber in the workpiece conveyance direction, of the pair of rotating bodies.

  The workpiece may be sandwiched between the conveyor belt and the conveyor belt located on the vertically lower side, and the preheating chamber may surround at least a part of the vertically upper conveyor belt on the vertically upper conveyor belt.

  According to the present disclosure, it is possible to suppress variations in the amount of heat applied to a work.

FIG. 1 is a schematic sectional view of a heating furnace. 2 is a sectional view taken along the line II-II of FIG. FIG. 3 is a functional block diagram of the heating furnace. FIG. 4 is a diagram for explaining the first modification. FIG. 5 is a diagram for explaining the second modification. FIG. 6 is a diagram for explaining the third modification.

  Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding, and do not limit the present disclosure unless otherwise specified. In this specification and the drawings, elements having substantially the same functions and configurations are designated by the same reference numerals, and repeated description will be omitted. In addition, illustration of elements not directly related to the present disclosure is omitted.

  FIG. 1 is a schematic sectional view of the heating furnace 100. 2 is a sectional view taken along the line II-II of FIG. The heating furnace 100 is configured by a so-called continuous heating furnace that continuously heats the work W during the transportation process. As shown in FIGS. 1 and 2, the heating furnace 100 has a heating chamber 110. The inner space S is surrounded (formed) by the outer wall 120 of the heating chamber 110. The internal space S (outer wall 120) has, for example, a roughly rectangular parallelepiped shape. However, the shape of the internal space S is not limited to the rectangular parallelepiped shape, and may be another shape.

  The outer wall 120 has an upper outer wall 122, a lower outer wall 124, a left outer wall 126, a right outer wall 128, an upstream outer wall 130, and a downstream outer wall 132 (see both FIG. 1 and FIG. 2). The upper outer wall 122 is located vertically above the inner space S. The lower outer wall 124 is located vertically below the inner space S. The left outer wall 126 is located on the left side of the internal space S when facing the internal space S from the upstream side in the transport direction (hereinafter, simply referred to as the transport direction) of the work W indicated by the white arrow in FIG. 1. The right outer wall 128 is located on the right side of the internal space S when facing the internal space S from the upstream side in the transport direction. The upstream outer wall 130 is located upstream of the inner space S in the transport direction. The downstream outer wall 132 is located downstream of the inner space S in the transport direction.

  A carry-in port 130a is formed in the upstream outer wall 130. The carry-in port 130a penetrates the upstream outer wall 130 from the inner side (inner space S side) to the outer side. An outlet 132a is formed in the downstream outer wall 132. The carry-out port 132a penetrates the upstream outer wall 130 from the inner side (inner space S side) to the outer side. The transport belt 142 of the transport device 140 is inserted through the carry-in port 130a and the carry-out port 132a. A part of the transport band 142 is located inside the heating chamber 110.

  The transport device 140 includes a transport band 142, rotating bodies 144a, 144b, 144c, 144d, and a motor mechanism 146. The transport band 142 is configured by, for example, an endless belt (steel belt, mesh belt, caterpillar (registered trademark)). The rotating bodies 144a, 144b, 144c, 144d are composed of, for example, pulleys, gears, and rollers. Protrusions (grooves) that fit with each other are formed on the inner peripheral surface of the transport band 142 and the outer peripheral surfaces of the rotating bodies 144a, 144b, 144c, 144d. However, this protrusion (groove) is not an essential component.

  The rotating bodies 144a and 144b are arranged separately in the transport direction. The heating chamber 110 is arranged between the rotating bodies 144a and 144b. The rotating bodies 144c and 144d are arranged at a position lower than the rotating bodies 144a and 144b (heating chamber 110). The rotating bodies 144a, 144b, 144c, 144d are rotatably supported by bearings (not shown). The transport belt 142 is stretched around the rotating bodies 144a, 144b, 144c, 144d. Here, the case where four rotating bodies 144a, 144b, 144c, 144d are provided has been described. However, at least a pair of rotating bodies 144a and 144b may be provided.

  The motor mechanism 146 is composed of a gear, a motor, and the like. The motor mechanism 146 rotates the rotating body 144b around the central axis of the rotating body 144b. With the rotation of the rotating body 144b, the transport band 142 makes a transition (rotation). The rotating bodies 144a, 144c, and 144d rotate with the transition of the transport belt 142. In this way, the motor mechanism 146 rotates the transport belt 142 around the outer circumferences of the rotating bodies 144a, 144c, 144d.

  The feeding station 142a is located on the upstream side (hereinafter, simply referred to as “upstream”) of the transport zone 142 in the transport direction with respect to the heating chamber 110. The work W stored in a storage location (not shown) is transported to the loading location 142a by the transport unit 150 such as a robot arm. At the loading place 142 a, the transport unit 150 places the work W on the transport belt 142. The work W is carried into the heating chamber 110 through the carry-in port 130a together with the carrying zone 142.

  A hermetically sealed gas heater 160 is arranged in the heating chamber 110. For example, the hermetically sealed gas heater 160 is provided on the vertically upper side and the vertically lower side of the transport band 142. The carrier band 142 is sandwiched by the hermetically sealed gas heater 160 while being vertically separated from the hermetically sealed gas heater 160. A plurality of closed gas heaters 160 are arranged apart from each other in the transport direction. However, at least one closed gas heater 160 may be provided in the heating chamber 110.

  As shown in FIG. 2, a support hole 126a is formed in the left outer wall 126. The support hole 126a penetrates the left outer wall 126 in the rotation axis direction of the rotating body 144a (the width direction of the transport band 142. Hereinafter, simply referred to as the width direction). A support hole 128a is formed in the right outer wall 128. The support hole 128a penetrates the right outer wall 128 in the width direction.

  The closed gas heater 160 has, for example, a substantially rectangular parallelepiped shape, and both ends of the closed gas heater 160 are inserted into the support holes 126a and 128a. The hermetically sealed gas heater 160 is supported by the support holes 126a and 128a. However, the support holes 126a and 128a are not essential configurations. The closed gas heater 160 may be mounted in the heating chamber 110 by other means.

  Here, the hermetically sealed gas heater 160 is, for example, a radiant tube burner, or the hermetically sealed gas heater described in Japanese Patent Application Laid-Open No. 2017-058124. The fuel gas burns inside the closed gas heater 160. The radiation surface of the hermetically sealed gas heater 160 is heated as the fuel gas burns. The radiation surface of the hermetically sealed gas heater 160 faces the conveyor belt 142 (workpiece W). Radiant heat is transferred from the radiant surface to the work W. The exhaust gas after combustion is not exhausted into the heating chamber 110, but is exhausted from the hermetically sealed gas heater 160 to a first exhaust passage 180 (see FIG. 3) described later.

  Here, the case where the sealed gas heater 160 is provided in the heating chamber 110 has been described. In this case, since the exhaust gas is discharged to the first exhaust passage 180 without providing a blower (fan, blower) or the like, it is possible to reduce the cost required for the blower or the like. However, instead of the hermetically sealed gas heater 160, a gas heater for discharging exhaust gas into the heating chamber 110 may be provided. In this case, since the exhaust gas discharged from the gas heater is sent to the first exhaust passage 180, the above blower or the like is provided.

  By the way, for example, if the temperature in the factory changes depending on the season, the time zone, etc., the temperature of the portion exposed to the outside of the heating chamber 110 in the transport zone 142 is affected. Further, when the entire transfer zone 142 is located inside the heating chamber 110, the temperature of the transfer zone 142 itself also changes according to the temperature condition inside the heating chamber 110. Therefore, it is not easy to control the temperature of the transport zone 142, and the temperature of the transport zone 142 may vary. If the temperature of the carrier band 142 varies, the amount of heat input to the carrier band 142 also varies. As a result, the amount of heat applied to the work W varies.

  In particular, when the work W is a coated product or food, the water and organic solvent of the work W mainly evaporate near the boiling point. In the heating furnace 100, the arrangement of the hermetically sealed gas heater 160 and the like are designed such that the temperature at which evaporation occurs at a predetermined position in the transport direction. If the amount of heat applied to the work W varies, the temperature rise transition of the work W becomes unstable, and the position at which evaporation occurs is not stable, which affects the quality. Further, particularly for foods having a relatively small heat capacity such as food, the carrier band 142 made of steel or the like has a larger heat capacity, and the temperature change of the carrier band 142 greatly affects the quality such as baking of the work W.

  Therefore, the heating furnace 100 is provided with a preheating chamber 170. Two through holes 172a and 172b are formed in the outer wall 172 of the preheating chamber 170. The through holes 172a and 172b penetrate the outer wall 172. The through hole 172a is formed in a portion of the outer wall 172 that faces the carry-in port 130a. The through hole 172b is formed in the outer wall 172 at a portion between the rotating bodies 144c and 144d. The transport band 142 is inserted through the through holes 172a and 172b.

  The preheating chamber 170 is provided outside the heating chamber 110. In the preheating chamber 170, the rotating bodies 144a, 144c and a part of the transport band 142 are located. A part of the preheating chamber 170 is located between the heating chamber 110 and the rotating body 144 a of the rotating bodies 144 a and 144 b on the upstream side of the heating chamber 110 in the transport direction. A part of the carrier band 142 between the rotating body 144a and the carry-in port 130a is located in the preheating chamber 170.

  FIG. 3 is a functional block diagram of the heating furnace 100. In FIG. 3, solid arrows indicate the flow of exhaust gas. In FIG. 3, dashed arrows indicate flows of data and control signals. As shown in FIG. 3, the heating furnace 100 includes a first exhaust passage 180, a branch passage 182, a control valve 184, a second exhaust passage 186, a temperature sensor 188, and a flow rate control unit 190.

  One end of the first exhaust passage 180 is connected to (communicates with) the closed gas heater 160. The other end of the first exhaust passage 180 is connected to the preheating chamber 170. The other end of the first exhaust passage 180 opens into the preheating chamber 170. In FIG. 1 and FIGS. 4, 5, and 6 described later, the first exhaust passage 180 is indicated by a dashed line. All or some of the closed gas heaters 160 are connected to the first exhaust passage 180. 1, FIG. 4, FIG. 5, and FIG. 6 illustrate a configuration in which the first exhaust passage 180 and a part of the hermetically sealed gas heater 160 are connected.

  One end of the branch passage 182 is connected to the connecting portion 180a in the first exhaust passage 180. The other end of the branch passage 182 opens outside the heating furnace 100. That is, the branch path 182 branches from the connecting portion 180a and communicates with the outside (outdoor) of the heating furnace 100.

  The control valve 184 is formed of, for example, a three-way valve, and is provided at the connecting portion 180a of the first exhaust passage 180. However, the control valve 184 may be provided in the first exhaust passage 180 closer to the preheating chamber 170 than the connecting portion 180a. In this case, the control valve 184 is, for example, a throttle valve. In any case, the opening degree of the control valve 184 is adjusted by the actuator 184a. The control valve 184 controls the flow rate of exhaust gas flowing from the first exhaust passage 180 to the preheating chamber 170. Part of the exhaust gas flows into the preheating chamber 170, and the rest is discharged to the outside of the heating furnace 100.

  The second exhaust passage 186 is connected to the preheating chamber 170. The exhaust gas supplied to the preheating chamber 170 is discharged to the outside of the heating furnace 100 through the second exhaust passage 186.

  The temperature sensor 188 is provided in the preheating chamber 170. The temperature sensor 188 may be provided, for example, on the inner wall surface of the preheating chamber 170, or may be provided on the rotating body 144a. The temperature sensor 188 detects the temperature of the preheating chamber 170 (air temperature, inner wall surface temperature, or temperature of the rotating body 144a). The temperature sensor 188 outputs temperature data indicating the detected temperature to the flow rate controller 190.

  The flow rate control unit 190 controls the opening degree of the control valve 184 based on the temperature data output from the temperature sensor 188. The flow rate control unit 190 controls the opening degree of the control valve 184 so that the temperature of the preheating chamber 170 becomes the target temperature. The target temperature is preset by the operator, for example. The flow rate control unit 190 performs feedback control using, for example, temperature data as an input and the opening degree of the control valve 184 as an output.

  In this way, the temperature of the preheating chamber 170 is maintained (maintained) at the set temperature by the exhaust gas of the closed gas heater 160. A part of the carrier zone 142 enters the heating chamber 110 after being kept at a predetermined temperature in the preheating chamber 170. Variations in the amount of heat input to the transport zone 142 can be suppressed. In this way, variations in the amount of heat applied to the work W are suppressed. The preheating chamber 170 is heated by the exhaust gas that has not been conventionally used, so that energy consumption is reduced.

  Further, the preheating chamber 170 is provided with a cooling unit 192. Inside the cooling unit 192, a cooling system such as a refrigerant pipe (not shown) is provided. The cooling pipe extends to the outside of the preheating chamber 170, and a refrigerant (for example, cooling water) cooled by an external device (not shown) circulates inside the cooling pipe. The flow rate control unit 190 controls a valve (not shown) to control the flow rate of the refrigerant flowing through the cooling pipe. By providing the cooling unit 192, the preheating chamber 170 can be cooled, and the preheating chamber 170 can function as a precooling chamber. However, the cooling unit 192 is not an essential component.

  FIG. 4 is a diagram for explaining the first modification. As shown in FIG. 4, in the first modification, the shape of the preheating chamber 270 is different from that of the preheating chamber 170 of the above-described embodiment. The preheating chamber 270 has an extending portion 270A. The extending portion 270A extends vertically below the heating chamber 110 in parallel with the transport direction. The length surrounding the transport band 142 between the rotating body 144a and the heating chamber 110 is shorter than that in the above-described embodiment. The extension portion 270A enables the preheating of the transport belt 142 to the same extent as in the above-described embodiment because the surrounding area of the transport belt 142 can be secured. Therefore, the length of the heating furnace 100 in the carrying direction can be shortened.

  FIG. 5 is a diagram for explaining the second modification. As shown in FIG. 5, in the second modification, through holes 130b and 132b are formed in the heating chamber 110 in addition to the carry-in port 130a and the carry-out port 132a.

  The through hole 130b is formed vertically below the carry-in port 130a in the upstream outer wall 130. The through hole 132b is formed vertically below the carry-out port 132a in the downstream outer wall 132. The transport band 142 is also inserted through the through holes 130b and 132b. The transport band 142 has a portion 142c located in the heating chamber 110 even on the vertical side of the portion 142b that transports the work W.

  The preheating chamber 370 is housed in the heating chamber 110. In the preheating chamber 370, a part of a portion 142c on the vertically lower side of the transport band 142 is located. The preheating chamber 370 is arranged, for example, on the upstream outer wall 130 side. The preheating chamber 370 is adjacent to the upstream outer wall 130 and the lower outer wall 124, for example. However, the preheating chamber 370 may be arranged at another position in the heating chamber 110 as long as it surrounds the vertically downward portion 142c of the transport band 142.

  FIG. 6 is a diagram for explaining the third modification. As shown in FIG. 6, in the third modified example, the transport device 440 is also provided vertically above the transport device 140 (workpiece W). The transport device 440 includes a transport belt 442, rotating bodies 444a, 444b, 444c, 444d, and a motor mechanism 446. Here, the difference between the transport belt 442, the rotating bodies 444a, 444b, 444c, 444d, and the motor mechanism 446 from the transport belt 142, the rotating bodies 144a, 144b, 144c, 144d, and the motor mechanism 146 will be described.

  The rotating bodies 444a and 444b are arranged in the heating chamber 110 vertically above the transport belt 142. The rotating bodies 144c and 144d are arranged vertically above the heating chamber 110. The transport belt 442 contacts the work W on the transport belt 142 from the vertically upper side. The work W is transported in the heating chamber 110 while being sandwiched between the transport band 142 and the transport band 442.

  The preheating chamber 470A is located vertically below the heating chamber 110. The preheating chamber 470A contacts the lower outer wall 124. The preheating chamber 470A is located between the rotating body 144c and the rotating body 144d. A part of the transport band 142 between the rotating body 144c and the rotating body 144d is located in the preheating chamber 470A.

  The preheating chamber 470B is located vertically above the heating chamber 110. The preheating chamber 470B contacts the upper outer wall 122. The rotating bodies 444c and 444d are arranged in the preheating chamber 470B. The entire portion of the transport band 442 between the rotating body 444c and the rotating body 444d is located in the preheating chamber 470B. A part of the transport band 442 between the rotating body 444b and the rotating body 444d is located in the preheating chamber 470B. A part of the carrier band 442 between the rotating body 444a and the rotating body 444c is located in the preheating chamber 470B. However, the preheating chamber 470B may surround at least a part of the transport band 442 on the vertically upper side.

  Since the preheating chamber 470B is provided on the vertically upper side of the heating chamber 110, heat radiation from the heating chamber 110 to the vertically upper side is suppressed. By suppressing the heat dissipation, the heat loss of the heating chamber 110 is suppressed.

  In the modified example described above, as in the above-described embodiment, the temperature of the preheating chambers 270, 370, 470A, and 470B is maintained at the set temperature by the exhaust gas of the hermetically sealed gas heater 160. Variations in the amount of heat input to the transport zones 142, 442 are suppressed, and variations in the amount of heat applied to the work W are suppressed. The preheating chambers 270, 370, 470A, 470B are heated by the exhaust gas that has not been conventionally used, so that energy consumption is reduced.

  Although one embodiment of the present disclosure has been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the embodiment. It is obvious to those skilled in the art that various changes or modifications can be conceived within the scope of the claims, and it should be understood that these also belong to the technical scope of the present disclosure. To be done.

  For example, in the above-described embodiment and modification, the case where the heating furnace 100 is a continuous heating furnace has been described. However, the heating furnace 100 may be a multi-chamber type furnace having a plurality of chambers having different temperatures or a batch furnace having a single chamber. In the multi-chamber furnace or the batch furnace, the work W may be heated or cooled while being stationary. In any case, the work W may be transferred into and out of the heating chamber 110 by the transfer bands 142 and 442.

  Further, in the above-described embodiment and modified examples, the case where the second exhaust passage 186 is provided has been described. In this case, outflow of exhaust gas into the factory is avoided. However, the second exhaust passage 186 is not an essential component.

  Further, in the above-described embodiment and modification, the case where the branch passage 182, the control valve 184, and the flow rate control unit 190 are provided has been described. In this case, it is possible to control the temperature of the preheating chambers 170, 270, 370, 470A, 470B. However, the branch passage 182, the control valve 184, and the flow rate control unit 190 are not essential components.

  Further, in the above-described embodiment and the first modification, the case where at least a part of the preheating chambers 170 and 270 is located between the rotating body 144a and the heating chamber 110 has been described. In this case, the transport belt 142 can be preheated before entering the heating chamber 110. However, the preheating chambers 170 and 270 do not have to be located between the rotating body 144 a and the heating chamber 110.

  Further, in the above-described third modified example, the case where both the preheating chambers 470A and 470B are provided has been described. However, the preheating chamber 470A is not an essential component. At least the preheating chamber 470B may be provided.

  Further, in the above-described embodiment and modified example, as shown in FIGS. 1, 4, 5, and 6, the other end of the first exhaust passage 180 is one of the preheating chambers 170, 270, 370, 470A, and 470B. , The work W is opened on the downstream side in the transport direction. In this case, it becomes possible to preheat the transport zone 142 immediately before leaving the preheating chambers 170, 270, 370, 470A, 470B. At this time, in order to efficiently preheat the carrier band 142, the exhaust gas may be directly blown to the carrier band 142. However, the arrangement of the first exhaust passage 180 is not limited to this. The first exhaust passage 180 may have any arrangement as long as it is connected to the closed gas heater 160 and the preheating chambers 170, 270, 370, 470A, 470B.

  The present disclosure can be applied to a heating furnace.

100 heating furnace 110 heating chamber 142 conveyance zone 144a rotating body 144b rotating body 144c rotating body 144d rotating body 160 hermetically sealed gas heater (gas heater)
170 preheating chamber 180 first exhaust passage 180a connecting portion 182 branch passage 184 control valve 186 second exhaust passage 190 flow rate control unit 270 preheating chamber 370 preheating chamber 442 transfer zone 444a rotating body 444b rotating body 444c rotating body 444d rotating body 470A preheating chamber 470B Preheating chamber W work

Claims (5)

A heating chamber,
A gas heater arranged in the heating chamber,
A first exhaust passage connected to the gas heater;
A preheating chamber connected to the first exhaust passage,
A pair of rotating bodies,
An endless conveyor belt which is stretched around the pair of rotating bodies, a part of which is located in the preheating chamber, and another part of which is located in the heating chamber,
Heating furnace equipped with. The heating furnace according to claim 1, further comprising a second exhaust passage that is connected to the preheating chamber and discharges the exhaust gas supplied to the preheating chamber. A branch path that branches from the first exhaust path and communicates with the outside,
Of the first exhaust passage, a connecting portion with the branch passage, or a control valve provided on the preheating chamber side with respect to the connecting portion,
A flow rate control unit for controlling the control valve based on the temperature of the preheating chamber,
The heating furnace according to claim 1 or 2, further comprising:   At least a part of the preheating chamber is located between the heating chamber and a rotating body on the upstream side of the heating chamber in the workpiece transport direction among the pair of rotating bodies. A heating furnace according to item 1. The conveyor belt sandwiches the work between the conveyor belt and the conveyor belt located vertically below,
The heating furnace according to any one of claims 1 to 4, wherein the preheating chamber surrounds at least part of the vertically upper side of the vertically upper transfer zone.

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