Continuous Heating Furnace

Abstract

To reduce erroneous detection of an article to be conveyed.SOLUTION: A continuous heating furnace 1 includes a tunnel-shaped furnace body 10 surrounding a space 10i along a predetermined conveyance direction, a plurality of conveyance rollers 20 respectively crossing the tunnel-shaped furnace body 10 and arranged along the conveyance direction, and a conveyance article detection device 90 for detecting that an article to be conveyed on the plurality of conveyance rollers 20 has passed a predetermined position in the furnace body 10. At least one conveyance roller 20 arranged in a predetermined region C including a predetermined position B is individually position-adjustable.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a continuous furnace. [Background technology]

[0002] JP 2022-94174 A discloses a roller hearth type heat treatment furnace including a heating chamber for heating the workpiece, a roller arranged in the heating chamber for supporting and transporting the workpiece, a roller driving means for driving the roller, a detection device for detecting the workpiece or a tray on which the workpiece is placed, and a control unit. The control unit is configured to be capable of performing an oscillation operation for rotating the roller in a stopped state by a predetermined angle in a forward or reverse direction, and a position correction operation for rotating the roller to correct the position of the workpiece based on a signal from the detection device. The control unit performs the position correction operation at intervals longer than the intervals at which the oscillation operation is repeatedly performed. In such a roller hearth type heat treatment furnace, it is said that thermal deformation of the roller at high temperatures can be suppressed. In addition, in such a roller hearth type heat treatment furnace, it is said that adhesion of evaporated matter to the detection device can be reduced, and deterioration of the function of detecting the heat-treated workpiece can be suppressed.

[0003] Japanese Patent Laid-Open Publication No. 10-220966 discloses a tunnel-shaped baking device having multiple rollers arranged parallel to each other and each driven to rotate around its axis. In the baking device, multiple substrates are subjected to heat treatment while being transported in one direction by multiple rollers. The baking device includes a substrate position detection device that detects the position of the substrate in a part of the substrate transport direction. The substrate detection device is positioned so as to detect a predetermined substrate detection point set between the rollers in a non-contact manner from a direction inclined at a predetermined angle with respect to the upper surface of the substrate. In such a baking device, it is said that failure to detect the substrate position is suppressed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-94174 [Patent Document 2] Japanese Patent Application Publication No. 10-220966 Summary of the Invention [Problem to be solved by the invention]

[0005] The present inventors wish to reduce erroneous detection of conveyed objects in a continuous heating furnace equipped with a conveyed object detection device that detects conveyed objects. [Means for solving the problem]

[0006] The continuous heating furnace disclosed herein includes a tunnel-shaped furnace body that encloses a space along a predetermined conveying direction, a plurality of conveying rollers that cross the tunnel-shaped furnace body and are arranged along the conveying direction, and a conveyed object detection device that detects that an object conveyed on the plurality of conveying rollers has passed a predetermined position in the furnace body. At least one of the conveying rollers arranged in a predetermined area including the predetermined position is configured to be individually position adjustable. With such a continuous heating furnace, erroneous detection of the conveyed object is reduced. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of a continuous heating furnace 1. [Diagram 2] FIG. 2 is a cross-sectional view of the continuous heating furnace 1. [Diagram 3] FIG. 3 is a schematic diagram showing a support structure for the plurality of transport rollers 20. As shown in FIG. [Figure 4] FIG. 4 is a schematic diagram of the roller support 30. As shown in FIG. [Diagram 5] FIG. 5 is a schematic diagram of the roller support 40. As shown in FIG. [Figure 6] FIG. 6 is a schematic diagram of the roller support 30. As shown in FIG. [Figure 7] FIG. 7 is a schematic diagram showing the height adjustment member 37. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, one of the embodiments of the present disclosure will be described in detail with reference to the drawings. In the following drawings, the same reference numerals are used to denote members and parts that perform the same function. Furthermore, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships. The directions of up, down, left, right, front, and rear are respectively indicated by arrows U, D, L, R, F, and Rr in the drawings. Here, the directions of up, down, left, right, front, and rear are merely defined for the convenience of explanation, and do not limit the present invention unless otherwise specified.

[0009] 1 and 2 are cross-sectional views of a continuous heating furnace 1. In Fig. 1, a longitudinal section of the continuous heating furnace 1 along the conveying direction is shown typically. In Fig. 2, a cross-sectional view taken along line II-II in Fig. 1 is shown typically. In Fig. 2, a transverse section of the continuous heating furnace 1 intersecting the conveying direction is shown typically.

[0010] <Continuous heating furnace 1> As shown in FIG. 1 and FIG. 2, the continuous heating furnace 1 includes a furnace body 10, a plurality of conveying rollers 20, a plurality of roller supports 30, 40, and a conveyed object detection device 90. The continuous heating furnace 1 includes a pair of support tables 35, 45. In the continuous heating furnace 1, the conveyed object is conveyed on the plurality of conveying rollers 20. In this embodiment, the conveyed object is a workpiece (hereinafter also referred to as workpiece A) placed on a heating container. The continuous heating furnace 1 is a heating furnace that continuously heats the workpiece A while conveying it along the conveying direction. In this embodiment, the continuous heating furnace 1 is a so-called roller hearth kiln that heats the workpiece while conveying it in the conveying direction (from the rear Rr to the front F) by the rotation of the conveying rollers. The arrow in the figure indicates the conveying direction in which the workpiece A is conveyed.

[0011] <Furnace body 10> The furnace body 10 encloses a space 10i in which the workpiece A is transported along the transport direction. The furnace body 10 is formed in a tunnel shape. As shown in FIG. 2, the furnace body 10 has a pair of side walls 50, 60, a bottom wall 70, and a ceiling wall 80. A transport roller 20 and a heater 12 are provided in the space 10i of the furnace body 10. The workpiece A is heat-treated by the heater 12 while being transported in the space 10i by the transport roller 20.

[0012] The heater 12 is a device for heat-treating the workpiece A transported on the transport rollers 20. In this embodiment, a burner-type heating device is used as the heater 12. The heater 12 is a device for burning fuel gas introduced from a pipe 13. The combustion of the fuel gas increases the temperature inside the furnace, and the workpiece A is heated. The heater 12 is provided on the side walls 50, 60. The heater 12 is provided on the side walls 50, 60 at predetermined heights above and below the transport rollers 20. The heater 12 is provided in a recess in the inner wall surface of the side walls 50, 60.

[0013] The heater 12 is not limited to the heater 12 described above as long as it can heat the workpiece A. The type, shape, arrangement, etc. of the heater 12 are not particularly limited and can be selected according to the heating conditions, etc. As the heater, for example, a cylindrical ceramic heater, a metal sheath heater, a plate-shaped panel heater, etc. may be used. The number, output, etc. of the heaters 12 can be appropriately set according to the processing conditions of the workpiece A. By changing the number, output, etc. of the heaters 12, it is possible to process the workpiece A under different processing conditions along the conveying direction.

[0014] Although not shown in the figure, a temperature sensor is provided in the space 10i. A thermocouple, an infrared thermometer, or the like can be used as the temperature sensor. The temperature sensor measures the temperature of the space 10i heated by the heater 12. The output of the heater 12 can be controlled according to the temperature of the space 10i measured by the temperature sensor. This allows the space 10i to be maintained at a preset temperature.

[0015] The furnace body 10 is made of a material that insulates the space 10i from heat and has fire resistance. In this embodiment, the furnace body 10 is made of firebricks. The firebricks are ceramic bricks, and may be made of alumina, mullite, or cordierite. The stacked firebricks are bonded together with an adhesive or mortar. The adhesive or mortar may be made of a highly heat-resistant ceramic material such as alumina, magnesia, or zirconia. The firebricks may be fixed together with an adhesive or mortar. In this embodiment, the firebricks used in the area where the conveying roller 20 is inserted have through holes 50a and 60a. A single firebrick may have a plurality of through holes 50a and 60a.

[0016] The refractory bricks may be stacked so that the boundaries between the refractory bricks stacked on top of each other are not continuous to form the furnace body 10. By not having continuous boundaries between the refractory bricks, the heat insulation properties can be good. Also, a stable layered structure of the furnace body 10 can be realized. The furnace body 10 may be appropriately made of a ceramic plate-shaped heat insulating material.

[0017] <Bottom wall 70> The bottom wall 70 is made of substantially rectangular parallelepiped refractory bricks stacked in multiple stages. The bottom wall 70 supports the side walls 50, 60. The refractory bricks constituting the side walls 50, 60 are stacked upward from both ends of the bottom wall 70 in the width direction of the furnace body 10.

[0018] <Side wall 50,60> The side walls 50, 60 extend upward from the bottom wall 70. The inner wall surfaces of the side walls 50, 60 are formed substantially vertically. A plurality of through holes 50a, 60a are formed in the pair of side walls 50, 60. The through holes 50a, 60a are holes through which the conveying roller 20 is inserted, and penetrate the side walls 50, 60, respectively. The plurality of through holes 50a, 60a are formed at a predetermined height of the side walls 50, 60 at a substantially constant pitch along the conveying direction. The through holes 50a, 60a are not limited to those formed in the firebrick. The through holes 50a, 60a may be formed, for example, by side walls above and below the portion through which the conveying roller 20 is inserted, and a partition member disposed between the side walls.

[0019] An inclined surface 50b, 60b is formed on the upper portion of the side wall 50, 60. The inclined surface 50b, 60b is a surface that is inclined from the upper portion of the side wall 50, 60 toward the inner wall surface. The inclined surface 50b, 60b is inclined so as to become lower toward the space 10i. The inclined surface 50b, 60b supports the ceiling wall 80. The inclined surface 50b, 60b forms a boundary between the side wall 50, 60 and the ceiling wall 80.

[0020] <Ceiling Wall 80> In this embodiment, the ceiling wall 80 is curved in the width direction of the furnace body 10. The ceiling wall 80 is made of firebricks. The ceiling wall 80 is formed in multiple layers. The configuration of the ceiling wall 80 is not particularly limited. The ceiling wall 80 may be formed substantially horizontally or inclined. The ceiling wall 80 at the upper part of the furnace body 10 is covered with multiple layers of blankets 15. The furnace body 10 may be provided with an exhaust path (not shown). Although not particularly limited, the exhaust path may be provided in the ceiling wall 80 of the furnace body 10.

[0021] The outside of the furnace body 10 may be covered by an outer frame 16. The outer frame 16 may be made of a metal having excellent rigidity and heat resistance. For example, stainless steel or the like may be used for the outer frame 16.

[0022] <Multiple conveying rollers 20> The multiple transport rollers 20 each cross the tunnel-shaped furnace body 10. The multiple transport rollers 20 are lined up along the transport direction. The multiple transport rollers 20 are each a hollow shaft member. In other words, the transport rollers 20 are cylindrical rollers. In this embodiment, a ceramic roller is used as the transport roller 20. The transport roller 20 is not limited to being made of ceramic, and may be made of metal. The transport rollers 20 are aligned at the same height so as to support the workpiece A, and are lined up in the space 10i at a predetermined pitch (see FIG. 1).

[0023] As shown in Fig. 2, the multiple transport rollers 20 are inserted into the through holes 50a, 60a of the pair of side walls 50, 60, respectively. In this embodiment, one end of one transport roller 20 is inserted into each of the multiple through holes 50a, 60a (see Fig. 2). The ends of the multiple transport rollers 20 protrude from the through holes 50a, 60a to the outside of the furnace body 10. The through holes 50a, 60a are blocked by the blanket 17 from the outside of the side walls 50, 60. This can reduce the escape of heat from the space 10i through the through holes 50a, 60a through which the transport rollers 20 are inserted.

[0024] FIG. 3 is a schematic diagram showing a support structure for a plurality of conveying rollers 20. FIG. 3 shows a schematic diagram of a plurality of conveying rollers 20 seen from above, a plurality of roller supports 30, 40 supporting the plurality of conveying rollers 20, and a conveyed object detection device 90. FIG. 4 is a schematic diagram of the roller support 30. FIG. 4 shows a schematic diagram of a support structure on the driving side of the conveying roller 20. FIG. 5 is a schematic diagram of the roller support 40. FIG. 5 shows a schematic diagram of a support structure on the driven side of the conveying roller 20. FIG. 6 is a schematic diagram of the roller support 30. FIG. 6 shows a schematic diagram of the roller support 30 seen from above. In FIG. 6, the conveyed object detection device 90 is omitted.

[0025] 3, the multiple conveying rollers 20 are supported by roller supports 30, 40, respectively. Here, one end of one conveying roller 20 is supported by the roller support 30, and the other end is supported by the roller support 40. The multiple roller supports 30, 40 are supported by support stands 35, 45 outside the furnace body 10.

[0026] The roller supports 30, 40 and the support bases 35, 45 are provided with an attachment structure that enables the position of the roller supports 30, 40 to be adjusted along the conveyance direction relative to the support bases 35, 45. The structures of the support bases 35, 45 and the roller supports 30, 40 will be described below.

[0027] <Support stand 35,45> The support bases 35 and 45 are rail-shaped members extending along the conveying direction. The support bases 35 and 45 are provided outside the furnace body 10. The support base 35 is disposed at a required distance from the side wall 50 of the furnace body 10. The support base 45 is disposed at a required distance from the side wall 60 of the furnace body 10.

[0028] As shown in Fig. 4, the support base 35 is supported by support columns 36. Although not shown, a plurality of support columns 36 are provided along the conveying direction, and each support base 35 is supported by a plurality of support columns 36. The support base 35 is attached to the support columns 36 by fixing brackets (not shown). A sprocket 34b is attached to the support base 35. A member that forms a loop path for the roller chain 34a, such as a chain guide, may be attached to the support base 35.

[0029] 5, the support table 45 is supported by support columns 46. Although not shown in the figure, a plurality of support columns 46 are provided along the conveyance direction, and each support table 45 is supported by a plurality of support columns 46. The support table 45 is attached to the support columns 46 by fixing brackets (not shown).

[0030] 4 and 5, the support bases 35, 45 have a pair of legs 35a, 45a and support portions 35b, 45b. The legs 35a, 45a extend upward from the posts 36, 46. The support portions 35b, 45b connect the upper ends of the pair of legs 35a, 45a, respectively.

[0031] The support portion 35b, 45b is a flat plate-shaped portion that supports the roller support 30, 40. The upper surface of the support portion 35b, 45b is provided with a protrusion 35b1, 45b1. The protrusion 35b1, 45b1 may be formed continuously or intermittently along the conveying direction. The protrusion 35b1, 45b1 is provided at a substantially central portion in the width direction of the support portion 35b, 45b. The protrusion 35b1, 45b1 may be, for example, a protrusion intermittently provided along the conveying direction, or may be a protrusion extending along the conveying direction. The support portion 35b, 45b may be provided with the protrusions 35b1, 45b1 arranged in a plurality of rows.

[0032] The support parts 35b, 45b are each formed with two rows of holes 35b2, 45b2. The holes 35b2, 45b2 are elongated holes (see FIG. 6) extending along the conveying direction. The two rows of holes 35b2, 45b2 are provided at positions sandwiching the protruding parts 35b1, 45b1 along the width direction of the support parts 35b, 45b, respectively. The dimensions of the holes 35b2, 45b2 in the width direction of the support parts 35b, 45b are set to dimensions that allow the mounting members 35b3, 45b3 to be inserted therethrough. The dimensions of the holes 35b2, 45b2 are not particularly limited. The length of the holes 35b2, 45b2 along the conveying direction may be a length that fits within the width of the roller supports 30, 40, or may be a length that spans a plurality of roller supports 30, 40. The holes 35b2, 45b2 may be formed intermittently in the support portions 35b, 45b, or may be formed continuously.

[0033] The roller supports 30, 40 are placed on the upper surfaces of the support bases 35, 45 (upper surfaces of the support portions 35b, 45b in this embodiment). This makes it difficult for the roller supports 30, 40 to fall off the support bases 35, 45. The roller supports 30, 40 may be placed directly on the upper surfaces of the support bases 35, 45, or may be placed on the upper surfaces of the support bases 35, 45 via height adjustment members 37 (see FIG. 7).

[0034] 7 is a schematic diagram showing a height adjustment member 37. FIG. 7 shows a schematic diagram of the height adjustment member 37 interposed between the support base 35 and the roller support 30. In the embodiment shown in FIG. 7, the roller support 30 is placed on the upper surface of the support base 35 via the height adjustment member 37. The height adjustment member 37 is a member that adjusts the height of the transport roller 20 by being interposed between the roller support 30 and the support base 35. The height adjustment member 37 may be provided between some of the multiple transport rollers 20 and the support base 35.

[0035] The height adjustment member 37 may be, for example, a plate-shaped member. The height adjustment member 37 may be a plate-shaped member extending along the conveying direction. The height of the roller support 30 is adjusted by adjusting the number and thickness of the height adjustment members 37 arranged between the roller support 30 and the support base 35. The shape of the height adjustment member 37 is not particularly limited. The height adjustment member may have approximately the same width as the roller support 30 or the support base 35. In this case, the height adjustment member 37 may be formed with a hole 37a corresponding to the convex portion 35b1 of the support base 35, and a hole 37b corresponding to the hole 35b2 and the mounting member 35b3. The shapes of the holes 37a and 37b are not particularly limited as long as the convex portion 35b1 and the mounting member 35b3 can be inserted therethrough, respectively. The height adjustment member 37 is not limited to such a form. The height of the roller support 30 may be adjusted by a plurality of height adjustment members arranged at positions that do not interfere with the convex portion 35b1 and the mounting member 35b3 of the support base 35. Furthermore, the height of the roller support 40 may be adjusted by disposing the height adjustment member 37 described above between the support base 45 and the roller support 40.

[0036] <Multiple Roller Supports 30, 40> As shown in Fig. 3, the multiple roller supports 30, 40 each support one end of one of the multiple transport rollers 20. Both ends of the multiple transport rollers 20 adjacent to each other in the transport direction are supported by the roller supports 30, 40, respectively. The roller support 30 supports the end 21 of the transport roller 20 protruding from the through hole 50a of the side wall 50. The roller support 40 supports the end 22 of the transport roller 20 protruding from the through hole 60a of the side wall 60.

[0037] The roller supports 30, 40 are arranged intermittently outside the furnace body 10 along the direction in which the transport rollers 20 are arranged (the transport direction). In other words, on both sides of the width of the furnace body 10, the roller supports 30, 40 supporting the transport rollers 20 are arranged with gaps in between along the transport direction. The roller supports 30, 40 are attached to support stands 35, 45.

[0038] <Roller support 30> 4, each of the roller supports 30 includes a housing 31, a bearing 32, and a shaft 33. One end (end 21) of each of the conveying rollers 20 is supported with one end of the shaft 33 of the roller support 30 inserted therein.

[0039] <Case 31> The housing 31 is a member that supports the shaft 33 via the bearing 32. The housing 31 is made of metal, and can be formed from, for example, stainless steel, aluminum, aluminum alloy, carbon steel, or the like. In this embodiment, the housing 31 has a rectangular prism shape. The housing 31 is placed on the support base 35 so that the length along the width direction of the furnace body 10 is longer than the length in other directions. In other words, the housing 31 is placed on the support base 35 with the surface with the narrowest area facing the furnace body 10. The shape of the housing 31 is not particularly limited, and may be a prism shape other than a rectangular prism, or may have a shape including a curved surface. The housing 31 may be a box-shaped one composed of a plurality of plates, or may be a U-shaped or L-shaped one. From the viewpoint of ease of processing and strength, it is preferable that the housing has a rectangular prism shape.

[0040] The housing 31 is placed on the support base 35. In this embodiment, the housing 31 of the roller support 30 has a portion corresponding to the convex portion 35b1 on the upper surface of the support portion 35b. A recess 31b is formed on the lower surface of the housing 31 into which the convex portion 35b1 of the support base 35 fits. As shown in FIG. 6, the recess 31b is a groove extending along the conveying direction. The dimensions of the recess 31b of the housing 31 correspond to the dimensions of the convex portion 35b1 of the support base 35. In the width direction of the support base 35 (the width direction of the furnace body 10), the recess 31b of the housing 31 is set to a dimension into which the convex portion 35b1 of the support base 35 fits. In this embodiment, in the width direction of the support base 35, the recess 31b of the housing 31 is set to a dimension slightly larger than the convex portion 35b1 of the support base 35. By providing the recess 31b in the housing 31, when the recess 31b of the housing 31 fits into the protrusion 35b1 of the support base 35, the roller support 30 is prevented from shifting in the width direction relative to the support base 35. Note that the housing 31 and the support base 35 do not necessarily have to be provided with corresponding recesses 31b and protrusions 35b1. A protrusion may be provided on the housing, and a recess corresponding to the protrusion may be provided on the support plate.

[0041] The housing 31 of the roller support 30 is formed with a mounting hole 31a to which the mounting member 35b3 is attached. The roller support 30 is attached to the support base 35 by the mounting member 35b3 in a state in which the recess 31b of the housing 31 is fitted into the protrusion 35b1 of the support base 35. The roller support 30 is detachably attached to the support base 35 by the mounting member 35b3 inserted into the hole 35b2. For example, a bolt or the like can be used as the mounting member 35b3. The hole 35b2 to which the mounting member 35b3 is attached is an elongated hole along the conveying direction. Therefore, even when the roller support 30 is moved along the conveying direction, the mounting member 35b3 attached to the mounting hole 31a of the roller support 30 moves along the hole 35b2. After the roller support 30 is moved along the conveying direction with the mounting member 35b3 loosened or removed, the roller support 30 can be fixed by the mounting member 35b3. This makes it possible to adjust the position of the roller support 30. The position adjustment of the roller support 30 can be performed at any desired timing, such as when the continuous heating furnace 1 is installed, when maintenance is performed after operation, or during operation.

[0042] As shown in FIG. 4, the housing 31 is formed with a through hole 31c through which the shaft 33 is inserted. The through hole 31c is a hole that opens in a substantially cylindrical shape in the center of the housing 31. The through hole 31c penetrates the center of the housing 31 along the length direction of the housing 31 (the width direction of the furnace body 10). In addition, a pair of recesses 31d are formed at both ends in the length direction of the housing 31. The recesses 31d are portions whose inner diameter is wider than that of the through hole 31c. The recesses 31d are formed in a substantially disk shape. A bearing 32 is attached to the recesses 31d.

[0043] <Bearing 32> The bearing 32 is a member that rotatably supports the shaft 33. The bearing 32 is attached to the housing 31. The bearing 32 is fitted into a pair of recesses 31d formed in the housing 31. At both ends of the housing 31, the bearing 32 partially protrudes from the recess 31d. A groove is provided in the portion of the bearing 32 that protrudes from the recess 31d. The bearing 32 is attached to the housing 31 by attaching a holding member 32a to the groove in a state where the bearing 32 is fitted into the recess 31d of the housing 31. Although not particularly limited, the holding member 32a may be a fastener such as an annular or pin-shaped member. The shaft 33 is inserted through the bearing 32 and the through hole 31c of the housing 31. A spacer may be provided between the inner peripheral surface of the housing 31 and the shaft 33.

[0044] <Shaft 33> The shaft 33 is rotatably supported by the bearing 32. At least one end of the shaft 33 protrudes from the housing 31. In this embodiment, the shaft 33 is inserted into the through hole 31c of the housing 31. The housing 31 surrounds the periphery of the shaft 33. This makes it difficult for dust, dirt, etc. to get between the shaft 33 and the housing 31, and prevents the shaft 33 from rotating due to the inclusion of foreign matter. Both ends of the shaft 33 protrude from the housing 31. The shaft 33 includes a base end 33a, a spring seat portion 33b, an insertion portion 33c, and a support portion 33d. The base end 33a is a portion attached to the bearing 32. The outer diameter of the base end 33a is approximately the same as the inner diameter of the bearing 32. The length of the base end 33a is longer than the length of the housing 31. Therefore, one end of the base end 33a protrudes outward from the housing 31. A sprocket 34 is attached to one end of the base end 33a protruding from the housing 31. A spring seat 33b is connected to the other end of the base end 33a.

[0045] The spring seat 33b is provided on a portion of the shaft 33 that protrudes from the housing 31. The spring seat 33b is disposed inside the housing 31 (toward the side wall 50 of the furnace body 10). The spring seat 33b is a substantially disk-shaped portion having an outer diameter larger than that of the base end 33a. The spring seat 33b is a portion against which one end of the coil spring 25 abuts. An insertion portion 33c extends from the spring seat 33b.

[0046] The insertion portion 33c is a portion through which the coil spring 25 is inserted. The insertion portion 33c extends from the spring seat portion 33b toward the side wall 50 of the furnace body 10. The outer diameter of the insertion portion 33c is smaller than the outer diameter of the spring seat portion 33b. The outer diameter of the insertion portion 33c is smaller than the inner diameter of the coil spring 25 through which it is inserted. In this embodiment, the outer diameter of the insertion portion 33c at the base end side (the spring seat portion 33b side) is approximately the same as the inner diameter of the coil spring 25. This makes it easier for the coil spring 25 to be fixed to the shaft 33, and makes it difficult for the position of the coil spring 25 to shift. A step is formed in the insertion portion 33c so that it becomes thinner toward the tip side. A support portion 33d is provided at the tip of the insertion portion 33c.

[0047] The support portion 33d is a portion that supports the conveying roller 20. The support portion 33d is inserted into the hollow conveying roller 20. A part of the tip of the insertion portion 33c can also be inserted into the conveying roller 20. The support portion 33d inserted into the conveying roller 20 supports the conveying roller 20 from the inside. The outer diameter of the support portion 33d is slightly smaller than the inner diameter of the conveying roller 20. This makes it difficult for a large load to be applied to these members even if the conveying roller 20 and the shaft 33 thermally expand as the continuous heating furnace 1 operates.

[0048] The conveying roller 20 is supported by the shaft 33 via a coil spring 25. The coil spring 25 is disposed between the conveying roller 20 and the spring seat 33b of the shaft 33. Here, a coil spring 25 having a natural length longer than the gap between the conveying roller 20 and the spring seat 33b of the shaft 33 is used. Therefore, both ends of the coil spring 25 abut against the end 21 of the conveying roller 20 and the spring seat 33b of the shaft 33, respectively. The elastic force of the compressed coil spring 25 acts on the end 21 of the conveying roller 20 and the end 21 of the spring seat 33b. As a result, the conveying roller 20 rotates in conjunction with the rotation of the shaft 33.

[0049] As described above, the sprocket 34 is attached to the end (the end of the base end 33a) of the shaft 33 opposite the conveying roller 20 across the housing 31. The roller chain 34a is wound around the sprocket 34. Although detailed illustration is omitted, the roller chain 34a is formed in a ring shape. As shown in FIG. 3, the roller chain 34a is wound around the sprockets 34 attached to the shafts 33 of the multiple roller supports 30. A chain guide (not shown) is provided below the multiple sprockets 34. The roller chain 34a may be wound around a sprocket 34b that sets a loop path for the roller chain 34a, in addition to the sprocket 34. The roller chain 34a is connected to a drive device (not shown) with a required tension applied to it. For example, a motor or the like can be used as the drive device. The drive device may be connected to the roller chain 34a via a reducer, a clutch, a coupling, or the like. The roller chain 34a rotates by the power of the drive device. The sprockets 34 attached to the shafts 33 of the roller supports 30 rotate in conjunction with the roller chains 34a, causing the shafts 33 to rotate. The elastic force of the compressed coil springs 25 acts on the spring seat portions 33b of the shafts 33 and the ends 21 of the transport rollers 20. Therefore, the rotation of the shafts 33 is transmitted to the transport rollers 20 via the coil springs 25, and the transport rollers 20 rotate in conjunction with the shafts. This causes the multiple transport rollers 20 to rotate at approximately the same timing and speed. In this way, the multiple transport rollers 20 are driven from the end 21 side on the side wall 50 side.

[0050] Ends 22 of the plurality of conveying rollers 20 on the side wall 60 side are supported by the roller support 40. The ends 22 of the plurality of conveying rollers 20 are supported by the roller support 40 so as to rotate following the rotation of the ends 21 on the side wall 50 side.

[0051] <Roller support 40> 5, like the roller support 30, the roller support 40 includes a housing 41, a bearing 42, and a shaft 43. One end (end 22) of the multiple conveying rollers 20 is supported with one end of the shaft 43 of the roller support 40 inserted therein. The roller support 40 can be configured in the same manner as the roller support 30, and therefore a detailed description thereof will be omitted.

[0052] The housing 41 has a mounting hole 41a to which the mounting member 45b3 is attached. The housing 41 has a through hole 41c. A pair of recesses 41d are formed at both ends of the housing 41 in the longitudinal direction. A bearing 42 is attached to the recess 41d. The bearing 42 is attached to the housing 41 by a holding member 42a. The shaft 43 is rotatably supported by the bearing 42. In this embodiment, both ends of the shaft 43 protrude from the housing 41. The shaft 43 includes a base end 43a, a spring seat portion 43b, an insertion portion 43c, and a support portion 43d. A compressed coil spring 25 is disposed between the spring seat portion 43b and the end 22 of the conveying roller 20. This allows the shaft 43 and the conveying roller 20 to rotate in conjunction with each other.

[0053] The shaft 43 of the roller support 40 does not have a sprocket 34 for transmitting the power of a driving device, unlike the sprocket 34 attached to the shaft 33 of the roller support 30 (see FIGS. 4 and 5). Therefore, the shaft 43 rotates in response to the rotation of the shaft 33 and the conveying roller 20.

[0054] As shown in FIG. 2, a transported object detection device 90 for detecting the object A transported on the multiple transport rollers 20 is provided outside the furnace body 10.

[0055] <Transported object detection device 90> The transported object detection device 90 includes a sensor 91 and a control device 98. The sensor 91 is configured to detect that the transported object (in this embodiment, object to be treated A) has passed a predetermined position B (see FIG. 1) inside the furnace body 10. In this embodiment, the sensor 91 is realized by a photoelectric switch. The sensor 91 includes a light projector 92 and a light receiver 93. The light projector 92 irradiates, for example, an infrared laser. The light receiver 93 receives the infrared laser irradiated from the light projector 92.

[0056] The light projector 92 and the light receiver 93 are attached to the outside of the furnace body 10. The light projector 92 and the light receiver 93 may be attached to a support member such as a metal fitting (not shown) outside the furnace body 10. The light projector 92 is provided at a position higher than the conveying rollers 20 on the outside of the side wall 60. The light receiver 93 is provided at a position lower than the conveying rollers 20 on the outside of the side wall 50. The light projector 92 and the light receiver 93 are disposed at the same position in the conveying direction and at different heights in the height direction (see FIGS. 2 and 3). The light projector 92 and the light receiver 93 are disposed so that their irradiating surface and receiving surface face each other.

[0057] In the space 10i, an optical axis P is set by a light projector 92 and a light receiver 93. In Figs. 2 and 3, the optical axis P is indicated by a two-dot chain line. The optical axis P is set at a position where the workpiece A passing through approximately the center in the width direction of the furnace body 10 can be detected. In this embodiment, the optical axis P is inclined at a predetermined angle with respect to the axial direction of the conveying rollers 20. The optical axis P is set approximately perpendicular to the conveying direction (see Fig. 3). The optical axis P passes between two adjacent conveying rollers 20 (see Figs. 1 and 3). In other words, position B is set at a position between two adjacent conveying rollers 20.

[0058] The side walls 50, 60 are provided with through holes 50c, 60c that penetrate along an optical axis P set by the light projector 92 and the light receiver 93. The through holes 50c, 60c penetrate the side walls 50, 60 at an angle. In other words, the through holes 50c, 60c incline the side walls 50, 60 at a predetermined angle with respect to the axial direction of the conveying roller 20. The through hole 60c is formed at a position higher than the conveying roller 20. The through hole 50c is formed at a position lower than the conveying roller 20.

[0059] A tube 94 is inserted into each of the through holes 50c, 60c. The tube 94 penetrates the side walls 50, 60, respectively. The tube 94 has a substantially cylindrical shape corresponding to the through holes 50c, 60c. The outer diameter of the tube 94 is substantially the same as the inner diameter of the through holes 50c, 60c. The tube 94 may be made of, for example, stainless steel or the like. Outside the furnace body 10 on the side wall 60 side, a light projector 92 is connected to the end of the tube 94 via a connecting member (not shown). Outside the furnace body 10 on the side wall 50 side, a light receiver 93 is connected to the end of the tube 94 via a connecting member.

[0060] The connection member may have, for example, a socket and a sight hole. A heat-resistant glass protective plate that protects the sensor 91 (in this embodiment, the light projector 92 and the light receiver 93) from heat, light, and the like can be attached to the sight hole. The protective plate can be attached to the sight hole via a rubber packing.

[0061] In this embodiment, the sensor 91 is configured to detect the transported object when the infrared laser emitted from the projector 92 is blocked and the infrared laser is not detected by the receiver 93. The control device 98 is communicatively connected to the sensor 91. When the sensor 91 detects that the transported object is passing through position B, various processes can be executed by the control device 98. An example of the processes executed by the control device 98 will be described below.

[0062] The control device 98 may be connected to, for example, a drive device connected to the roller chain 34a so as to be able to communicate with it. The control device 98 may control the power of the drive device when the workpiece A passes through position B. The rotation speed of the conveying roller 20 is controlled by controlling the driving force of the drive device, and the conveying speed of the workpiece A can be controlled. The control device 98 may control the drive device to increase the conveying speed of the workpiece A when the workpiece A passes through position B, or may control the drive device to decrease the conveying speed of the workpiece A. The control device 98 is not limited to controlling to change the conveying speed, and may control the drive device to stop the conveying of the workpiece A for a certain period of time. The control device 98 may control the drive device to convey the workpiece A in the opposite direction to the conveying direction. The control of the drive device by the control device 98 may be appropriately set according to the processing conditions of the workpiece A, etc. In this way, the workpiece A may be detected by the sensor 91, and the conveying of the workpiece A may be controlled by the control device 98.

[0063] The control device 98 may be configured to confirm that the workpiece A is being transported normally. For example, the control device 98 may record the time when the workpiece A is scheduled to pass through position B. When a plurality of workpieces A are transported intermittently, the time when each of the plurality of workpieces A is scheduled to pass through position B may be recorded. The control device 98 may be configured to notify that a malfunction has occurred in the transport when the time when the workpiece A passed through position B is different from the recorded time. The method of notification is not particularly limited, and may be notified by a notification lamp provided on the outside of the furnace body 10, may be notified by an alarm sound, may be notified by displaying on a display showing the operating status of the continuous heating furnace 1, or may be notified to a predetermined notification destination. The predetermined notification destination is not particularly limited, and may be, for example, a display showing the operating status of the continuous heating furnace 1, or may be a terminal used for managing the continuous heating furnace 1. In this way, a malfunction in the transport of the workpiece A may be notified by the sensor 91 and the control device 98.

[0064] According to the inventor's knowledge, when the temperature inside the continuous heating furnace rises during operation, the temperature of the conveying roller rises and the conveying roller expands. In addition, the weight of the conveyed object may apply a load to the conveying roller. For this reason, there is a concern that the conveying roller may change in dimension or become deformed during operation of the continuous heating furnace. If the conveying roller is deformed in a continuous heating furnace provided with a conveyed object detection device, the conveyed object detection device may detect the conveying roller. For example, in a conveyed object detection device using a light projector and a light receiver as sensors, if the optical axis set by the light projector and the light receiver is blocked by a deformed conveying roller, the conveyed object may be erroneously detected as having passed a predetermined position. If the conveyed object is erroneously detected, problems such as the conveying of the conveyed object not being appropriately controlled or a conveying error being erroneously notified may occur.

[0065] In the above-described embodiment, the continuous heating furnace 1 includes a tunnel-shaped furnace body 10 surrounding a space 10i along a predetermined conveying direction, a plurality of conveying rollers 20 arranged along the conveying direction, each of which crosses the tunnel-shaped furnace body 10, and a conveyed object detection device 90 for detecting that a conveyed object conveyed on the plurality of conveying rollers 20 has passed a predetermined position B in the furnace body 10. The conveying rollers 20 are configured to be individually position adjustable. When the conveying object detection device 90 erroneously detects a conveying roller 20 that has been deformed or the like at the predetermined position B, the position of only the conveying roller 20 that has been erroneously detected can be adjusted. As a result, erroneous detection can be reduced. In addition, since only the conveying roller 20 that has been erroneously detected by the conveying object detection device 90 can be adjusted in position among the plurality of conveying rollers 20, it is not necessary to move the positions of the other conveying rollers 20. As a result, the position of only the conveying roller 20 that has been erroneously detected can be adjusted so that the other conveying rollers 20 do not interfere with equipment such as the furnace body 10. In addition, the transported object detection device 90 is usually fixed in position relative to the furnace body 10, and it is difficult to eliminate erroneous detection of the transported object by adjusting the position of the transported object detection device 90. Here, the transport roller 20 is configured to be position adjustable, so that erroneous detection can be easily reduced.

[0066] It is not necessary that all of the conveying rollers 20 are individually adjusted in position. Among the conveying rollers 20, the conveying rollers 20 in the vicinity of the position where the workpiece A is detected by the conveyed object detection device 90 may be supported by the roller supports 30, 40. For example, as shown in FIG. 1, the conveying rollers 20 arranged in a predetermined area C including a predetermined position B detected by the conveyed object detection device 90 may be configured to be position adjustable. In this embodiment, the position B is set to a position between two adjacent conveying rollers 20 among the conveying rollers 20. If these conveying rollers 20 are deformed, the deformed portion may enter the position B, causing the conveyed object detection device 90 to make a false detection. For this reason, the area C is set to include two adjacent conveying rollers 20 sandwiching the position B. By adjusting the positions of these conveying rollers 20, the false detection may be eliminated. Not limited to this, the area C may be determined by the position, configuration, etc. of the conveyed object detection device 90. The area C may include one transport roller 20, may include two transport rollers 20, or may include three or more transport rollers 20. For example, when the transported article detection device 90 is provided such that the optical axis P passes above one transport roller 20 substantially parallel to the transport roller 20, the area C may be set to include only one transport roller 20 directly below the optical axis P. When the transported article detection device 90 is provided such that the optical axis P passes above multiple (e.g., three or more) transport rollers 20, the area C may be set to include multiple transport rollers 20 directly below the optical axis P.

[0067] In the above-described embodiment, the ends 21, 22 of the conveying roller 20 arranged in the predetermined area C are supported by the roller supports 30, 40 configured to be position adjustable. The position of the conveying roller 20 can be adjusted by adjusting the positions of the roller supports 30, 40 outside the furnace body 10. Therefore, the position of the conveying roller 20 can be adjusted even during operation of the continuous heating furnace 1, making it easy to eliminate erroneous detection.

[0068] According to the inventor's knowledge, erroneous detection of the conveying roller may also occur when the conveying roller is deteriorated due to long-term use of the continuous heating furnace. The temperature of the conveying roller rises and falls with temperature changes due to operation and stop of the continuous heating furnace. The conveying roller repeatedly expands and contracts with the rise and fall of temperature. The dimensions of the conveying roller may change or be deformed due to long-term use of the continuous heating furnace. For this reason, the conveying roller needs to be inspected and replaced periodically, such as during maintenance of the continuous heating furnace. In addition, not only the conveying roller, but also each equipment such as the furnace body of the continuous heating furnace may change in dimensions or be deformed due to long-term use. In such a case, even if the deteriorated conveying roller is replaced, the conveying roller and the furnace body may interfere with each other due to deformation of the furnace body. The conveying roller may be deformed due to interference between the furnace body and the conveying roller. In such a case, erroneous detection of the conveying roller by the conveyed object detection device may also occur. In the above-mentioned embodiment, the conveying roller 20 is supported by the roller supports 30 and 40 so that the position can be adjusted individually. This makes it easy to individually adjust the positional relationship between the furnace body 10 and the transport roller 20. Therefore, erroneous detection of the transport roller 20 caused by interference between the furnace body 10 and the transport roller 20 can be easily eliminated.

[0069] In the above-described embodiment, the continuous heating furnace 1 includes a pair of support bases 35, 45. The pair of support bases 35, 45 each extend along the conveying direction and are provided outside the furnace body 10 in the width direction of the furnace body 10 (see Figs. 3 and 6). The roller supports 30, 40 are each attached to the pair of support bases 35, 45 (see Figs. 4 and 5). The roller supports 30, 40 and the support bases 35, 45 are provided with an attachment structure that allows the position of the roller supports 30, 40 to be adjusted along the conveying direction relative to the support bases 35, 45. With this configuration, the position of the conveying roller 20 can be adjusted outside the furnace body 10, improving the workability of the position adjustment.

[0070] In the above-described embodiment, the support base 35, 45 has the convex portion 35b1, 45b1 at the portion where the roller support 30, 40 is attached. The housing 31, 41 of the roller support 30, 40 has the concave portion 31b, 41b into which the convex portion 35b1, 45b1 fits. By fitting the convex portion 35b1, 45b1 of the support base 35, 45 into the concave portion 31b, 41b of the roller support 30, 40, the roller support 30, 40 is less likely to shift in the width direction when the position of the roller support 30, 40 is adjusted. This can improve the workability when adjusting the position of the roller support 30, 40.

[0071] In the above-described embodiment, the recesses 31b, 41b are grooves extending along the transport direction. This allows the roller supports 30, 40 to slide along the transport direction with the protrusions 35b1, 45b1 inserted in the groove-shaped recesses 31b, 41b. The protrusions 35b1, 45b1 are guided by the groove-shaped recesses 31b, 41b, making it difficult for the roller supports 30, 40 to shift in position in the width direction, and making it easy to adjust the position of the roller supports 30, 40 along the transport direction.

[0072] The roller supports 30, 40 may be attached to the support bases 35, 45 in a state in which they are placed on the upper surfaces of the support bases 35, 45 via the height adjustment members 37. By using the height adjustment members 37, not only the position and angle along the conveying direction but also the height of the conveying rollers 20 can be adjusted. This can improve the degree of freedom in adjusting the position, angle, etc. of the conveying rollers 20.

[0073] In the above-described embodiment, the transported object detection device 90 is realized by a photoelectric switch. The optical axis P is inclined at a predetermined angle with respect to the axial direction of the transport roller 20, and is set at a position where the object A passing through approximately the center in the width direction of the furnace body 10 can be detected. The optical axis P is set to pass between two adjacent transport rollers 20. However, the transported object detection device 90 is not limited to this form. The arrangement, form, etc. of the transported object detection device 90 can be appropriately selected depending on the shape, etc. of the transported object.

[0074] The positions at which the light projector 92 and the light receiver 93 as the sensor 91 are provided are not limited to the above-mentioned embodiment. The light projector 92 and the light receiver 93 may be provided outside the ceiling wall 80 and the bottom wall 70 of the furnace body 10 so that the optical axis P is set along the height direction. The light projector 92 and the light receiver 93 may be provided at the same height so that the optical axis P is set along the width direction of the furnace body at a position higher than the upper end of the conveying roller 20. The optical axis P may be set above the conveying roller 20 or above the gap between two adjacent conveying rollers 20. The light projector 92 and the light receiver 93 may be provided at different positions in the conveying direction so that the optical axis P is inclined with respect to the width direction of the furnace body 10.

[0075] The sensor 91 is not limited to a configuration in which the sensor 91 detects the transported object when the optical axis P set by the light projector 92 and the light receiver 93 is interrupted. The sensor 91 may be configured to detect the transported object when, for example, an infrared laser irradiated from the light projector 92 is reflected by the transported object and detected by the light receiver 93. In this case, the positions of the light projector 92 and the light receiver 93 are appropriately set.

[0076] Although a detailed description has been given above with reference to specific embodiments, these are merely examples and do not limit the scope of the claims. Thus, the technology described in the claims includes various modifications and alterations of the above-described embodiments.

[0077] This specification includes the following items 1 to 10. The following items 1 to 10 are not limited to the above-mentioned embodiment.

[0078] Section 1: A tunnel-shaped furnace body that encloses a space along a predetermined conveying direction; A plurality of conveying rollers arranged along the conveying direction and crossing the tunnel-shaped furnace body, a transported object detection device that detects that the transported object transported on the plurality of transport rollers has passed a predetermined position in the furnace body; Equipped with At least one conveying roller arranged in a predetermined area including the predetermined position is configured to be individually position adjustable. Continuous heating furnace.

[0079] Section 2: Item 1. The continuous heating furnace according to item 1, wherein an end of at least one of the conveying rollers arranged in the predetermined region is supported by a plurality of roller supports configured to be adjustable in position.

[0080] Section 3: Further comprising a pair of support bases; The pair of support tables each extend along the conveying direction and are provided outside the furnace body in the width direction of the furnace body, The roller supports are each attached to one of the pair of support bases, Item 3. The continuous heating furnace according to item 2, wherein the roller support and the support base are provided with an attachment structure that allows the position of the roller support to be adjusted along the conveying direction relative to the support base.

[0081] Section 4: Each of the plurality of conveying rollers is a hollow shaft member, The plurality of roller supports include Housing and A bearing attached to the housing; a shaft that is rotatably supported by the bearing and has at least one end protruding from the housing; Each of them has Item 4. The continuous heating furnace according to item 3, wherein both ends of at least one of the plurality of conveying rollers are supported in a state in which one end of the shaft of the roller support is inserted therein.

[0082] Section 5: the support base has a protrusion at a location where the roller support is attached, 5. The continuous heating furnace according to item 4, wherein the housing of the roller support has a recess formed therein into which the protrusion fits.

[0083] Item 6: Item 6. The continuous heating furnace according to item 5, wherein the recess is a groove extending along the conveying direction.

[0084] Section 7: 7. The continuous heating furnace according to any one of items 3 to 6, wherein the roller support is attached to the support table in a state in which the roller support is placed on an upper surface of the support table.

[0085] Section 8: Item 8. The continuous heating furnace according to item 7, wherein the roller support is attached to the support table in a state in which the roller support is placed on the upper surface of the support table via a height adjustment member.

[0086] Section 9: Item 9. The continuous heating furnace according to item 8, wherein the height adjustment member is plate-shaped.

[0087] Section 10: The support base has a hole formed along the conveying direction, The housing of the roller support has a mounting hole formed therein, 10. The continuous heating furnace according to any one of items 4 to 9, wherein the roller support is attached to the support base by an attachment member inserted into the hole and the attachment hole. [Explanation of symbols]

[0088] A. Material to be processed 1 Continuous heating furnace 10 Furnace body 10i space 12 Heater 20 Conveyor roller 21,22 End 25 Coil spring 30,40 Roller support 31,41 Case 31a, 41a Mounting holes 31b, 41b Recess 31c,41c through hole 31d,41d recess 32,42 Bearings 33,43 Shaft 33a,43a Base end 33b,43b Seat part 33c, 43c Insertion part 33d,43d Support part 34 Sprocket 34a roller chain 35,45 Support stand 35a,45a Legs 35b,45b Support part 35b1,45b1 convex part 35b2,45b2 hole 35b3, 45b3 mounting parts 36,46 pillars 37 Height adjustment member 50,60 side wall 50a, 60a Through holes 90 Transported goods detection device 91 Sensors 92 Floodlight 93 Receiver 98 Control Device

Claims

1. A tunnel-shaped furnace body that encloses a space along a predetermined conveying direction; A plurality of conveying rollers arranged along the conveying direction and crossing the tunnel-shaped furnace body, A plurality of roller supports each independently supporting an end portion of the plurality of conveying rollers; A pair of supports; a transported object detection device that detects that the transported object transported on the plurality of transport rollers has passed a predetermined position in the furnace body; Equipped with Each of the plurality of conveying rollers is a hollow shaft member, The plurality of roller supports include Housing and A bearing attached to the housing; a shaft that is rotatably supported by the bearing and has at least one end protruding from the housing; Each of them has both ends of at least one of the plurality of conveying rollers are supported in a state in which one end of the shaft of the roller support is inserted, The pair of support tables each extend along the conveying direction and are provided outside the furnace body in the width direction of the furnace body, The support table has a hole formed therein that penetrates an upper surface thereof and is aligned along the conveying direction, A mounting hole is formed in the lower surface of the housing of the roller support, the plurality of roller supports are attached to the housing by the mounting members inserted through the holes and the mounting holes in a state in which the lower surface of the housing is placed on the upper surface of one of the pair of support bases, In a predetermined region including the predetermined position, the roller support and the support base are provided with an attachment structure capable of adjusting the position of the roller support relative to the support base along the conveying direction, and at least one conveying roller arranged in the predetermined region is configured to be individually position adjustable. Continuous heating furnace.

2. 2. The continuous heating furnace according to claim 1, wherein an end portion of at least one of the conveying rollers arranged in the predetermined region is supported by a plurality of roller supports configured to be positionably adjustable.

3. the support base has a convex portion on the upper surface to which the roller support is attached, 3. The continuous heating furnace according to claim 1, wherein the lower surface of the housing of the roller support body is formed with a recess into which the protrusion fits.

4. The continuous heating furnace according to claim 3 , wherein the recess is a groove extending along the conveying direction.

5. 3. The continuous heating furnace according to claim 1, wherein the roller support is attached to the support table in a state in which the roller support is placed on the upper surface of the support table via a height adjustment member.

6. 6. The continuous heating furnace according to claim 5, wherein the height adjustment member is plate-shaped.

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