Heat treatment furnace

Abstract

The present invention provides a heat treatment furnace that can avoid the thermal impact of high-temperature exhaust gas on a duct cleaning device positioned above the exhaust duct. [Solution] The system comprises an exhaust duct (11) that protrudes from the top of the furnace body (10) and communicates with a heat treatment space (15), and has a first through hole (11A) in the center of its upper end; a plurality of cylindrical members (41, 42) arranged coaxially on the upper end of the exhaust duct, each having a ceiling portion (41B, 42B) with a second through hole (41C, 42C) formed in the center; and a duct cleaning device (30) positioned above the plurality of cylindrical members to remove dust adhering to the inside of the exhaust duct. The duct cleaning device has a rod-shaped support portion (32) inserted through the first and second through holes, with its lower end connected to the upper end of a scraper (31); and a drive unit (33) to which the upper end of the support portion is connected, causing the scraper and the support portion to reciprocate vertically.

Description

【Technical Field】 【0001】 The present disclosure relates to a heat treatment furnace. 【Background Art】 【0002】 The ash melting furnace described in Patent Document 1 has an inclined duct portion that communicates with a gas discharge port and inclines obliquely upward, and a horizontal duct portion that extends horizontally from above the inclined duct portion and is connected to a combustion chamber. Further, a duct cleaning device for removing dust adhering in the horizontal duct portion is provided. The duct cleaning device is configured to rotate a scraping blade from the upstream side of the horizontal duct and reciprocate in the horizontal direction to remove dust in the horizontal duct and convey it to the combustion chamber. Since such a duct cleaning device is arranged at a position outside the horizontal direction parallel to the horizontal duct, it is possible to avoid the thermal influence of high-temperature exhaust gas. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2002-168433 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 However, in a heat treatment furnace such as a firing furnace, an exhaust duct that discharges exhaust gas generated from the workpiece to the outside protrudes vertically upward from the upper part of the furnace body. Therefore, when a duct cleaning device is arranged above the exhaust duct, there is a problem that it is difficult for the duct cleaning device to avoid the thermal influence of high-temperature exhaust gas at the upper end of the exhaust duct. 【0005】 One aspect of the present disclosure aims to provide a heat treatment furnace capable of avoiding the thermal influence of high-temperature exhaust gas on a duct cleaning device arranged above an exhaust duct. 【Means for Solving the Problems】 【0006】 To solve the above problems, a heat treatment furnace according to one aspect of the present disclosure comprises: a furnace body having a heat treatment space inside for heating and treating a workpiece; an exhaust duct protruding vertically from the upper part of the furnace body and communicating with the heat treatment space, and having a first through-hole in the center of its upper end; a plurality of cylindrical members arranged at the upper end of the exhaust duct, overlapping the exhaust duct coaxially, and having a ceiling portion at its upper end with a second through-hole formed along its axis; and a duct cleaning device arranged above the plurality of cylindrical members, which removes dust adhering to the inside of the exhaust duct and drops it into the heat treatment space, wherein the duct cleaning device comprises: a scraper for removing the dust; a rod-shaped support portion inserted through the first and second through-holes and having its lower end connected to the upper end of the scraper; the upper end of the support portion protruding upward outward from the second through-hole, and a drive unit to which the upper end of the support portion is connected, causing the scraper and the support portion to reciprocate in the vertical direction. [Effects of the Invention] 【0007】 According to one aspect of this disclosure, it is possible to avoid thermal effects from high-temperature exhaust gas on a duct cleaning device located above the exhaust duct. [Brief explanation of the drawing] 【0008】 [Figure 1] This is a front view of a heat treatment furnace according to this embodiment. [Figure 2] This is a plan view of the heat treatment furnace according to this embodiment. [Figure 3] This is an enlarged view of section A1 in Figure 1. [Figure 4] This diagram illustrates the position of the scraper under normal circumstances. [Figure 5] This diagram illustrates the lowest position of the scraper during cleaning. [Modes for carrying out the invention] 【0009】 [Outline configuration of a heat treatment furnace] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to Figures 1 to 5. In each figure, arrows indicate the top, bottom, left, right, front, and rear directions of the heat treatment furnace 1. In the following description, descriptions of direction will be based on these directions. 【0010】 The schematic configuration of the heat treatment furnace 1 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a front view of the heat treatment furnace 1 according to this embodiment. Figure 2 is a plan view of the heat treatment furnace 1 according to this embodiment. The heat treatment furnace 1 is a furnace for firing workpieces 5, such as positive electrode material and negative electrode material for lithium-ion batteries, ceramic products, etc. 【0011】 [Furnace body 10] As shown in Figures 1 and 2, the heat treatment furnace 1 comprises a furnace body 10 mounted on a frame 3, a door 20 that closes the opening of the furnace body 10, an exhaust duct 11 that protrudes vertically upward from the top of the furnace body 10, and a duct cleaning device 30 positioned above the exhaust duct 11. The heat treatment furnace 1 is configured so that an operator can open and close the door 20 while standing to move the workpiece 5 into and out of the furnace body 10. The furnace body 10 is a roughly rectangular parallelepiped with an open front, and is made of a metal plate (such as a stainless steel plate) of a predetermined thickness. The inner bottom, top, left and right, and rear side walls are covered with an insulating material 12. 【0012】 [Door 20] Furthermore, the door 20 is rectangular in front view and includes a door frame 21 made of a metal plate (such as a stainless steel plate) of a predetermined thickness. The door frame 21 almost completely covers the entire front surface of the furnace body 10, and its right edge is rotatably attached to the front edge of the right side of the furnace body 10 via a plurality of hinges 22, for example, three hinges 22. The inner surface of the door frame 21 is covered by an insulating material 12 that is fitted into the opening of the furnace body 10. 【0013】 The insulating material 12 covering the inner surface of the door frame 21 is configured to be close to or in contact with the front end of the insulating material 12 inside the opposing furnace body 10 when the door 20 is closed. The door 20 is not an essential component, and its presence or absence may be determined depending on the type of furnace to which this disclosure applies. For example, in the case of a roller hearth kiln (continuous furnace), the door 20 is not necessary and may not be provided. In the case of a batch furnace or the like having a box-shaped furnace body that can be sealed, the door 20 may be provided. 【0014】 The insulation material 12 is composed of, for example, stacked ceramic fiber boards that have been molded into a predetermined shape. The ceramic fiber boards are formed into plates by adding inorganic fillers and inorganic-organic binders to so-called bulk fibers, for example. The thickness and number of ceramic fiber boards are appropriately set according to the heating temperature of the workpiece 5. 【0015】 Furthermore, a support platform 13 is stretched between the left and right side walls inside the furnace body 10 on which the object to be processed 5, contained in a sagger or the like, is placed. The support platform 13 is made up of multiple rollers arranged in the front-to-back direction, allowing the object to be processed 5 to be easily moved in the front-to-back direction. Above and below the support platform 13, multiple heaters 14 are stretched between the left and right side walls, each arranged in the front-to-back direction. The heaters 14 are made up of cylindrical ceramic heaters or the like, and the number of heaters 14 arranged in the front-to-back direction is appropriately set according to the heating temperature of the object to be processed 5. As a result, when the door 20 is closed, a heat treatment space 15 is formed inside the furnace body 10 where the object to be processed 5 is heated by each heater 14. The exhaust duct 11 is also connected to the heat treatment space 15. 【0016】 [Exhaust duct 11] As shown in FIGS. 1 and 2, the substantially cylindrical exhaust duct 11 is made of metal (such as stainless steel) having a predetermined thickness, and the lower end portion thereof is detachably attached to a substantially central position on the upper end surface of the furnace body 10 by means of bolts or the like. On the outer peripheral surface at a substantially central position in the vertical direction of the exhaust duct 11, a pair of circular through holes in the front view are formed facing each other in the left - right direction, and one end of each of the pair of cross pipes 17 is attached to the pair of through holes by welding or the like. The pair of cross pipes 17 are arranged so as to be orthogonal to the axial direction of the exhaust duct 11, air is supplied from the outside to one of the cross pipes 17, and the exhaust gas in the exhaust duct 11 is configured to flow out from the other cross pipe 17 together with the air. 【0017】 The configuration of the lower end portion of the exhaust duct 11 will be described based on FIGS. 1, 4, and 5. FIG. 4 is a diagram for explaining the position of the scraper 31 in the normal state. FIG. 5 is a diagram for explaining the lowermost position of the scraper 31 during cleaning. 【0018】 As shown in FIGS. 1, 4, and 5, a columnar ceramic inner cover member 18 is fitted into the lower inner peripheral portion from the lower ends of the pair of cross pipes 17 of the exhaust duct 11. The inner cover member 18 penetrates along the axis, and a third through hole 18A through which the scraper 31 of the duct cleaning device 30 is inserted is formed. The lower end portion of the third through hole 18A penetrates through the upper portion of the furnace body 10 and is coaxially connected to the upper end portion of an exhaust passage 10A that communicates with the heat treatment space 15. The cross - section of the exhaust passage 10A is set to be slightly larger than the cross - section of the third through hole 18A of the columnar inner cover member 18. 【0019】 The upper end portion of the exhaust duct 11 is closed, and a first through hole 11A through which the substantially cylindrical rod - shaped support portion 32 of the duct cleaning device 30 and the shaft portion 31A of the scraper 31 are inserted is formed at the central portion of the upper end portion. The exhaust duct 11 is provided with a flange 11B in the shape of a ring in the plan view that extends radially outward from the outer peripheral surface of the upper end portion. On the upper end surface of the exhaust duct 11, a substantially cylindrical first cylindrical member 41 and a substantially cylindrical second cylindrical member 42 are arranged coaxially with each other, overlapping in the vertical direction. 【0020】 [First cylindrical member 41] The first cylindrical member 41 and the second cylindrical member 42 will be described based on FIG. 3. FIG. 3 is an enlarged view of part A1 in FIG. 1. As shown in FIG. 3, the substantially cylindrical first cylindrical member 41 is made of metal (such as stainless steel) having a predetermined thickness, and a flange 41A in the shape of a ring in plan view extending a predetermined length radially outward from the outer peripheral surface of the lower end portion is provided. The flange 41A is formed to have substantially the same outer diameter as the outer diameter of the flange 11B provided at the upper end portion of the exhaust duct 11, is coaxially disposed above the flange 11B, and is attached to the flange 11B by a plurality of bolts 45 and nuts 46. Therefore, the inside of the first cylindrical member 41 communicates with the inside of the exhaust duct 11 through the first through hole 11A formed at the upper end portion of the exhaust duct 11. 【0021】 The upper end portion of the first cylindrical member 41 is closed by a ceiling portion 41B having a predetermined thickness, and a second through hole 41C through which the substantially cylindrical column portion 32 of the duct cleaning device 30 is inserted is formed at the central portion of the ceiling portion 41B. Further, the first cylindrical member 41 is provided with a flange 41D in the shape of a ring in plan view extending a predetermined length radially outward with a predetermined thickness in the vertical direction from the outer peripheral surface of the upper end portion. Further, a seal member 48 for sealing the column portion 32 inserted into the second through hole 41C formed in the ceiling portion 41B is attached to the upper end surface of the first cylindrical member 41 with respect to the second through hole 41C. 【0022】 [Seal member 48] As shown in FIG. 3, the seal member 48 has a disk-shaped disk portion 48A having an outer diameter smaller than the inner diameter of the second cylindrical member 42. The disk portion 48A is attached coaxially with the first cylindrical member 41 to the upper end surface of the first cylindrical member 41 by a plurality of bolts 49. The seal member 48 attached to the upper end surface of the first cylindrical member 41 has a columnar protruding portion 48B protruding upward a predetermined height coaxially with the first cylindrical member 41 from the upper end surface of the disk portion 48A. The protruding portion 48B is provided with a recess 48C having a circular cross-section recessing coaxially with the first cylindrical member 41 from the upper end surface toward the disk portion 48A. 【0023】 Three layers of heat-resistant packing 51 are arranged in the recess 48C in a vertical direction. A through hole 48D is provided in the center of the bottom of the recess 48C through which the support column 32 is inserted. The heat-resistant packing 51 seals the support column 32, which is inserted through the second through hole 41C and the through hole 48D, to the second through hole 41C and the through hole 48D. Note that the heat-resistant packing 51 is not limited to three layers, but may be arranged in one, two, or four or more layers. The heat-resistant packing 51 can be any heat-resistant sealing material, but for example, a heat-resistant gland packing is preferred. 【0024】 The recess 48C of the protruding portion 48B is provided with a disc-shaped pressing portion 48E that presses down the three stacked heat-resistant packings 51 against the bottom (downward) of the recess 48C. The pressing portion 48E is formed to have approximately the same outer diameter as the outer diameter of the protruding portion 48B. The pressing portion 48E is attached to the upper end surface of the protruding portion 48B by a plurality of bolts 53. A through hole 48F is provided in the center of the pressing portion 48E through which the support column 32 is inserted. 【0025】 [Second cylindrical member 42] As shown in Figure 3, the second cylindrical member 42 is made of metal (such as stainless steel) with a predetermined thickness and is formed in a substantially cylindrical shape with an outer diameter smaller than the outer diameter of the first cylindrical member 41. The second cylindrical member 42 is provided with a ring-shaped flange 42A in plan view, which extends radially outward for a predetermined length from the outer circumferential surface of the lower end. The flange 42A is formed to have approximately the same outer diameter as the flange 41D provided at the upper end of the first cylindrical member 41, is positioned coaxially above the flange 41D, and is attached to the flange 41D by a plurality of bolts 55. Therefore, the inside of the second cylindrical member 42 is prevented from receiving exhaust gas from the first cylindrical member 41 by the sealing member 48 provided at the upper end of the first cylindrical member 41. 【0026】 The upper end of the second cylindrical member 42 is closed by a ceiling portion 42B of a predetermined thickness, and a second through-hole 42C is formed in the center of the ceiling portion 42B through which the support column 32 of the duct cleaning device 30 is inserted. Furthermore, a sealing member 58 is attached to the upper end surface of the second cylindrical member 42 to seal the support column 32, which is inserted through the second through-hole 42C formed in the ceiling portion 42B, against the second through-hole 42C. 【0027】 [Sealing member 58] As shown in Figure 3, the sealing member 58 has a disc-shaped disc portion 58A having an outer diameter smaller than the outer diameter of the second cylindrical member 42. The disc portion 48A is attached coaxially to the upper end surface of the second cylindrical member 42 by a plurality of bolts 59. The sealing member 58 attached to the upper end surface of the second cylindrical member 42 has a cylindrical projection 58B that protrudes upward to a predetermined height coaxially with the second cylindrical member 42 from the upper end surface of the disc portion 58A. The projection 58B is provided with a circular cross-section recess 58C that is recessed coaxially with the second cylindrical member 42 from the upper end surface toward the disc portion 58A. 【0028】 Two layers of heat-resistant packing 61 are housed in the recess 58C, stacked vertically. A through-hole 58D is provided in the center of the bottom of the recess 58C through which the support column 32 is inserted. The heat-resistant packing 61 seals the support column 32, which is inserted through the second through-hole 42C and the through-hole 58D, against the second through-hole 42C and the through-hole 58D. Note that the heat-resistant packing 61 is not limited to being stacked in two layers; it may be arranged in one layer or three or more layers. The heat-resistant packing 61 can be any heat-resistant sealing material, but for example, a heat-resistant gland packing is preferred. 【0029】 The recess 58C of the protruding portion 58B is provided with a disc-shaped pressing portion 58E that presses down the two stacked heat-resistant packings 61 against the bottom (downward) of the recess 58C. The pressing portion 58E is formed to have approximately the same outer diameter as the outer diameter of the protruding portion 58B. The pressing portion 58E is attached to the upper end surface of the protruding portion 58B by a plurality of bolts 63. A through hole 58F is provided in the center of the pressing portion 58E through which the support column 32 is inserted. 【0030】 [Duct cleaning device 30] Next, the general configuration of the duct cleaning device 30 will be described based on Figures 1, 2, 4, and 5. As shown in Figures 1 and 2, the duct cleaning device 30 includes an air cylinder 33 which functions as an example of a drive unit, a support column 32, a scraper 31, and the like. The air cylinder 33 is positioned on a frame 65 provided on the upper part of the furnace body 10 and above the second cylindrical member 42. 【0031】 [Stand 65] As shown in Figures 1 and 2, the frame 65 has four support frames 65A, the lower ends of which are fixed to the four corners of the upper end surface of the furnace body 10, and which extend vertically upward to a predetermined height. Each support frame 65A extends upward to a predetermined height higher than the upper end of the second cylindrical member 42. The upper end of each support frame 65A is attached to the lower end of each corner of the square frame 65B by welding, bolting, or the like. Therefore, the square frame 65B is positioned substantially horizontally with respect to the second cylindrical member 42, the first cylindrical member 41, and the exhaust duct 11. 【0032】 As shown in Figure 2, a pair of beam frames 65C are provided across the front-to-back direction of the rectangular frame 65B, with opposing frames in the front-to-back direction. When viewed from above, these beam frames 65C are positioned so as to sandwich the exhaust duct 11 from the left and right outer sides. As shown in Figures 1 and 2, a base plate 67 is positioned at a predetermined height above the center of the front-to-back center between the pair of beam frames 65C, with an air cylinder 33 attached to the center of its upper surface. 【0033】 [Base Plate 67] The base plate 67 is formed in a rectangular shape that is elongated horizontally when viewed from above, and is supported approximately horizontally by four plate support parts 67A that extend downward from the four corners and whose lower ends are fixed to a pair of beam frames 65C. In addition, four slide bushings 68 are provided on the base plate 67, passing through vertically at the four corners of a square shape with the width of the base plate 67 in the front-to-back direction as one side, with the air cylinder 33 at the center of this square. 【0034】 As shown in Figures 4 and 5, a slide shaft 69, which is a predetermined length longer than the piston rod 33A of the air cylinder 33, is fitted into each slide bush 68 so as to be movable in the vertical direction. The lower end of each slide shaft 69 is attached to the four corners of a connecting plate 71 that is square in plan view. Therefore, the connecting plate 71 is positioned parallel to the base plate 67. A floating joint 72 is provided in the center of the upper surface of the connecting plate 71. The connecting plate 71 is connected to the tip of the piston rod 33A via the floating joint 72. The upper end of the support column 32 is connected vertically to the center of the lower surface of the connecting plate 71. 【0035】 [Scraper 31] The upper end of the shaft portion 31A of the scraper 31 is connected to the lower end of the support portion 32. A disc-shaped scraping portion 31B is provided at the lower end of the shaft portion 31A of the scraper 31, approximately perpendicular to the shaft portion 31A. The outer diameter of the disc-shaped scraping portion 31B is slightly shorter than the inner diameter of the third through hole 18A of the inner cover member 18, for example, about 5 mm to 10 mm shorter. Note that the scraping portion 31B is not limited to a disc shape, but may also be an elliptical plate shape, a square plate shape, a hexagonal plate shape, etc., which are slightly smaller than the third through hole 18A. 【0036】 As shown in Figure 4, the length of the shaft portion 31A of the scraper 31 is set to be slightly shorter than the distance from the upper end of the cross pipe 17 to a position slightly above the lower end of the first cylindrical member 41 when the piston rod 33A of the air cylinder 33 is retracted. As a result, when the piston rod 33A of the air cylinder 33 is retracted, the scraping portion 31B of the scraper 31 can be positioned above the upper end of the cross pipe 17. Also, when the piston rod 33A of the air cylinder 33 is retracted, the support portion 32 is pulled upward while being inserted through the respective seal members 48 and 58. Normally, the piston rod 33A of the air cylinder 33 is retracted. 【0037】 [Strut part 32] As shown in Figure 5, the length of the support column 32 is set to a distance from a position slightly below the midpoint between the upper end of the cross pipe 17 and the upper end of the exhaust duct 11 to a position a predetermined height above and outside the sealing member 58 of the second cylindrical member 42. Therefore, when the piston rod 33A of the air cylinder 33 is pushed out, the support column 32 is inserted through the respective sealing members 48 and 58 and protrudes upward from the sealing member 58. Also, when the piston rod 33A of the air cylinder 33 is pushed out, the scraping portion 31B of the scraper 31 protrudes slightly downward from the lower end of the third through-hole 18A of the inner cover member 18 located at the lower end of the exhaust duct 11 and is located at the upper end of the exhaust passage 10A of the furnace body 10. 【0038】 [Operation of the duct cleaning device 30] As shown in Figures 4 and 5, the duct cleaning device 30 can move the support column 32 and the scraper 31 back and forth vertically by repeatedly pushing out and retracting the piston rod 33A of the air cylinder 33. As a result, dust adhering to the inner circumference of the third through hole 18A of the inner cover member 18 located at the lower end of the exhaust duct 11 can be removed by the scraping portion 31B of the scraper 31 and dropped into the heat treatment space 15 via the exhaust passage 10A. 【0039】 As described in detail above, in the heat treatment furnace 1 according to this embodiment, the air cylinder 33 of the duct cleaning device 30 is positioned between the air cylinder 33 and the upper end of the exhaust duct 11, with a first cylindrical member 41 and a second cylindrical member 42 in between. This makes it possible to avoid the thermal effects of high-temperature exhaust gas on the duct cleaning device 30, including the air cylinder 33, which is positioned above the exhaust duct 11. As a result, a heat treatment furnace 1 can be realized in which the duct cleaning device 30 is positioned above the exhaust duct 11. 【0040】 Furthermore, the outer diameter of the upper second cylindrical member 42 is set to be smaller than the outer diameter of the lower first cylindrical member 41. This gradually reduces the amount of heat transferred upward by the high-temperature exhaust gas, further preventing the thermal impact of the high-temperature exhaust gas on the duct cleaning device 30. 【0041】 Furthermore, the support column 32 of the duct cleaning device 30 is sealed to the second through-holes 41C and 42C via the sealing member 48 of the first cylindrical member 41 and the sealing member 58 of the second cylindrical member 42, thereby improving the airtightness of the exhaust duct 11. As a result, exhaust gas flowing into the exhaust duct 11 can be prevented from leaking to the outside through the second through-hole 42C of the second cylindrical member 42. In addition, the long support column 32 can be supported by the sealing members 48 and 58 to suppress axial wobble. 【0042】 Furthermore, because air flows above the inner cover member 18, solidified exhaust gas dust is generated on the inner surface of the third through-hole 18A. Therefore, the scraper 31 can effectively remove the dust generated in the third through-hole 18A of the exhaust duct 11 and allow it to fall into the heat treatment space 15. In addition, the air flowing into the exhaust duct 11 via the cross piping 17 cools the high-temperature exhaust gas inside the exhaust duct 11, further preventing the heat impact of the high-temperature exhaust gas on the duct cleaning device 30 located above the exhaust duct 11. 【0043】 Furthermore, under normal circumstances, the scraper 31 is positioned above the cross pipe 17, allowing air to flow smoothly through one of the cross pipes 17, thereby enabling the exhaust gas in the exhaust duct 11 to flow out into the other cross pipe 17. 【0044】 Furthermore, since the air cylinder 33 of the duct cleaning device 30 is positioned on a frame 65 located on the upper part of the furnace body 10, the installation space of the heat treatment furnace 1 can be reduced. Also, since the scraper 31 of the duct cleaning device 30 is positioned on a frame 65 located on the upper part of the furnace body 10, for example, when cleaning the cross pipe 17, even if the cross pipe 17 is removed from the exhaust duct 11, the scraper 31 and the exhaust duct 11 can remain positioned coaxially on the frame 65. Therefore, cleaning and dismantling work can be performed without shifting the axis of the scraper 31 and the center of the exhaust duct 11. 【0045】 [Differentiation] Modified examples of the above embodiments will now be described. For the sake of convenience, in the following description, components having the same function as those described in the above embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated. 【0046】 [Example 1] For example, one or more cylindrical members with an outer diameter smaller than the outer diameter of the second cylindrical member 42 may be arranged vertically on top of the second cylindrical member 42. Furthermore, a second through-hole is provided in the ceiling of each cylindrical member arranged above the second cylindrical member 42, through which the support column 32 can be inserted. A sealing member 58 may also be placed on the upper end surface of each cylindrical member arranged above the second cylindrical member 42. This prevents the duct cleaning device 30, which is positioned above the exhaust duct 11, from being affected by the heat from the high-temperature exhaust gas. As a result, a heat treatment furnace with the duct cleaning device 30 positioned above the exhaust duct 11 can be realized. 【0047】 [summary] The heat treatment furnace of the first embodiment comprises a furnace body having a heat treatment space inside for heating and treating an object to be treated; an exhaust duct that protrudes vertically from the top of the furnace body and communicates with the heat treatment space, and has a first through-hole in the center of its upper end; a plurality of cylindrical members arranged at the upper end of the exhaust duct, overlapping the exhaust duct coaxially, and having a ceiling portion at its upper end with a second through-hole formed along its axis; and a duct cleaning device arranged above the plurality of cylindrical members, which removes dust adhering to the inside of the exhaust duct and drops it into the heat treatment space. The duct cleaning device comprises a scraper for removing the dust; a rod-shaped support portion whose lower end is connected to the upper end of the scraper while being inserted through the first and second through-holes; the upper end of the support portion protrudes upward outward from the second through-hole, and the upper end of the support portion is connected to a drive unit that reciprocates the scraper and the support portion in the vertical direction. 【0048】 The second embodiment is a heat treatment furnace according to the first embodiment, wherein the plurality of cylindrical members are sequentially set such that the outer diameter of the cylindrical member positioned on the upper side is smaller than the outer diameter of the cylindrical member positioned on the lower side. 【0049】 A third embodiment is a heat treatment furnace according to the first or second embodiment, wherein the plurality of cylindrical members have a sealing member positioned at the upper end of the second through hole, and the support portion is sealed to the second through hole via the sealing member. 【0050】 The fourth embodiment is a heat treatment furnace according to any one embodiment of the first to third embodiments, wherein the exhaust duct comprises a pair of cross pipes mounted opposite to each other in a direction perpendicular to the axial direction of the exhaust duct, allowing air to flow into the exhaust duct and exhaust gas to flow out together with the air, and an inner cover member mounted on the inner circumferential surface of the exhaust duct whose outer circumferential surface is lower than the pair of cross pipes, and having a third through-hole formed in the center through which the scraper can be inserted. 【0051】 The fifth embodiment is a heat treatment furnace according to the fourth embodiment, wherein the drive unit normally positions the scraper above the pair of cross pipes, and when cleaning the exhaust duct, moves the scraper back and forth in the vertical direction. 【0052】 The sixth embodiment is a heat treatment furnace according to any one embodiment of the first to fifth embodiments, wherein the drive unit is arranged on a frame provided on the upper part of the furnace body. 【0053】 [Additional Notes] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure. [Explanation of Symbols] 【0054】 1: Heat treatment furnace 5: Items to be processed 10:Furnace body 11: Exhaust duct 11A: 1st through hole 15: Heat treatment space 17: Cross-piping 18: Inner cover component 18A: 3rd through hole 30: Duct cleaning device 31: Scraper 32: Strut part 33: Air Cylinder 41: First cylindrical member 41B, 42B: Ceiling part 41C, 42C: 2nd through hole 42: Second cylindrical member 48, 58: Sealing members 3. 65: Stand

Claims

[Claim 1] A furnace body having a heat treatment space inside for heating the object to be processed, An exhaust duct that protrudes vertically from the upper part of the furnace body, communicates with the heat treatment space, and has a first through-hole in the center of its upper end, At the upper end of the exhaust duct are a plurality of cylindrical members arranged coaxially with the exhaust duct and having a ceiling portion at its upper end in which a second through-hole is formed along the axis, A duct cleaning device is positioned above the plurality of cylindrical members and removes dust adhering to the inside of the exhaust duct and drops it into the heat treatment space. Equipped with, The duct cleaning device is, A scraper for removing the aforementioned dust, A rod-shaped support portion, inserted through the first through hole and the second through hole, with its lower end connected to the upper end of the scraper, The upper end of the support column protrudes upward and outward from the second through hole, and the upper end of the support column is connected to a drive unit that reciprocates the scraper and the support column in the vertical direction. It has, The aforementioned exhaust duct is A pair of cross pipes are installed opposite each other in a direction perpendicular to the axial direction of the exhaust duct, allowing air to flow into the exhaust duct and exhaust gas to flow out together with the air, An inner cover member is attached to the inner circumferential surface of the exhaust duct, whose outer circumferential surface is lower than the pair of cross pipes, and which has a third through-hole formed in its center through which the scraper can be inserted. A heat treatment furnace having [Claim 2] The plurality of cylindrical members are sequentially set such that the outer diameter of the cylindrical member positioned on the upper side is smaller than the outer diameter of the cylindrical member positioned on the lower side. The heat treatment furnace according to claim 1. [Claim 3] The plurality of cylindrical members each have a sealing member positioned at the upper end of the second through hole, The support column is sealed to the second through-hole via the sealing member. The heat treatment furnace according to claim 1. [Claim 4] The aforementioned drive unit is Under normal circumstances, the scraper is positioned above the pair of cross pipes. When cleaning the exhaust duct, the scraper is moved back and forth in the vertical direction. The heat treatment furnace according to claim 1. [Claim 5] The drive unit is positioned on a frame provided on the upper part of the furnace body. The heat treatment furnace according to claim 1.

Images