Rotary kiln

Abstract

To swiftly execute heat treatment to the whole of an object to be treated.SOLUTION: A rotary kiln 1 comprises: a cylindrical part 2 rotatable around its own axis D and having a heat treatment chamber 203 for executing heat treatment to a powdery object W to be treated; and a rugged friction amplification part 4 arranged around at least a part of an inner circumferential face 201a of the cylindrical part 2, and amplifying friction force against the object W to be treated.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a rotary kiln that applies heat treatment to an object to be treated. [Background technology]

[0002] A rotary kiln has a cylindrical section that can rotate around its own axis. A heat treatment chamber is defined inside the cylindrical section. It is assumed that the inner surface of the cylindrical section is smooth and has no irregularities. In this case, the workpiece slides against the inner surface of the rotating cylindrical section while appearing to be stationary at a predetermined position. Alternatively, the workpiece slides against the inner surface of the rotating cylindrical section while apparently oscillating within a certain range along the inner surface.

[0003] However, in this case, the contact surface (heat transfer surface) of the workpiece with the inner circumferential surface of the cylindrical portion is difficult to renew. As a result, only the area near the contact surface is likely to be heated locally. The heated area near the contact surface acts as a heat insulator, inhibiting heat diffusion throughout the workpiece. This makes it difficult to quickly heat-treat the entire workpiece.

[0004] In this regard, lifters are arranged on the inner peripheral surface of the cylindrical part of the rotary kiln in Patent Document 1. According to the rotary kiln in this document, the lifters can agitate the material to be treated as the cylindrical part rotates. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-210067 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the rotary kiln of the same document, as the cylindrical portion rotates, the material to be treated repeats the following actions (a) to (d): (a) It accumulates on the lower part of the inner circumferential surface. (b) It is scooped up by the rotating lifter. (c) It rises while accumulated on the lifter. (d) It descends (flows down, falls, etc.) from the lifter to the lower part of the inner circumferential surface. In this way, as the cylindrical portion rotates, the material to be treated moves, alternately resting on the inner circumferential surface and the lifter.

[0007] Here, the workpiece does not always move continuously. The workpiece moves when transferring from the inner circumferential surface to the lifter (step (b)) and from the lifter to the inner circumferential surface (step (d)). However, the workpiece remains stationary when depositing on the inner circumferential surface (step (a)) and when depositing on the lifter (step (c)). Thus, in the rotary kiln of the same document, the workpiece moves intermittently only during steps (b) and (d). That is, the workpiece is agitated. In the stationary state of steps (a) and (c), the workpiece is not agitated. In the rotary kiln of the same document, heat can be diffused intermittently only during steps (b) and (d). This makes it difficult to rapidly apply heat treatment to the entire workpiece. Therefore, the rotary kiln of the present disclosure aims to rapidly apply heat treatment to the entire workpiece. [Means for solving the problem]

[0008] (1) In order to solve the above problem, the rotary kiln of the present disclosure is characterized by comprising a cylindrical section that is rotatable about its own axis and has a heat treatment chamber for applying heat treatment to a powdered workpiece, and a friction amplification section that is arranged around the entire inner surface of the cylindrical section and has a concave-convex shape and amplifies the friction force against the workpiece.

[0009] Compared to a rotary kiln in which the inner peripheral surface of the cylindrical portion is a smooth surface without any irregularities, this configuration has a friction amplification portion disposed around at least a portion of the inner peripheral surface of the cylindrical portion. This makes it easier for the material to follow the rotating inner peripheral surface. Therefore, the material can rise to a high position by following the inner peripheral surface. This promotes the rolling of the material when it descends (flows down, falls, etc.) under its own weight.

[0010] By promoting the rolling of the workpiece, the contact surface (heat transfer surface) of the workpiece with the inner circumferential surface of the cylindrical portion is more easily renewed, which facilitates heat diffusion throughout the workpiece, thereby enabling rapid heat treatment of the entire workpiece.

[0011] In rotary kilns with lifters located on the inner circumferential surface of the cylindrical portion, the material is raised by lifting it with the lifter. In contrast, in the present configuration, the material is raised by the frictional force between the material and the friction amplifier (the inner circumferential surface of the cylindrical portion). Thus, the mechanism for raising the material is essentially different between a rotary kiln with a lifter and this configuration.

[0012] As mentioned above, in the case of a rotary kiln with a lifter, the material to be treated does not move continuously, but moves intermittently only when transferring from the inner circumferential surface to the lifter and when transferring from the lifter to the inner circumferential surface.

[0013] In contrast, in the present configuration, the position (height and angle) of any part of the inner circumferential surface changes continuously as the cylindrical part rotates. Therefore, the position of the workpiece deposited on that part also changes continuously. Therefore, the workpiece continuously rises and falls depending on the position of the workpiece, the dynamic angle of repose, and the internal frictional resistance (resistance caused by friction and meshing between particles that make up the powder).

[0014] In this way, with this configuration, the workpiece can be continuously moved relative to the rotary kiln with lifters. This allows heat to be continuously diffused throughout the workpiece. This allows the entire workpiece to be quickly heat-treated. Furthermore, the thermal history of the workpiece is less likely to vary throughout the workpiece. This makes it easier to homogenize the quality of the workpiece after heat treatment.

[0015] (2) In the configuration of (1) above, it is preferable to use an externally heated rotary kiln that includes a pressure reducing section for reducing the pressure in the heat treatment chamber. This rotary kiln is an externally heated rotary kiln. Therefore, the heat treatment chamber can be heated from outside the heat treatment chamber.

[0016] Furthermore, with this configuration, the heat treatment chamber can be heated in a reduced pressure environment. In a reduced pressure environment, the amount of gas in the heat treatment chamber decreases. This makes it difficult to perform heat treatment using convective heat transfer. In this regard, with this configuration, a friction amplification portion is disposed around at least a portion of the entire inner circumferential surface of the cylindrical portion. This facilitates rolling of the workpiece during heat treatment. Therefore, heat conduction (heat conduction due to contact between the inner circumferential surface of the wall of the cylindrical portion and the workpiece) can be promoted. Thus, with this configuration, the entire workpiece can be quickly heat-treated, even in a reduced pressure environment where convective heat transfer is difficult to utilize.

[0017] (2-1) In any of the above configurations, the heat treatment performed on the object in the heat treatment chamber is preferably drying. With this configuration, the entire object can be quickly dried.

[0018] (3) In any of the above configurations, it is preferable that the powder-like workpiece is an aggregate of a large number of particles, and that the friction amplification portion has a recess through which at least some of the large number of particles can enter and exit.

[0019] At least some of the particles constituting the workpiece can enter and exit the recess of the friction amplification part from the heat treatment chamber side (the radially inner side of the cylindrical part), so the workpiece can be raised to a position where the particles that have entered the recess will fall out of the recess under their own weight.

[0020] (4) In any of the above configurations, it is preferable that the friction amplifier be detachable from the inner peripheral surface. Consider a case where heat treatment is performed on multiple different types of workpieces in a shared rotary kiln. If the friction amplifier is integrated with the inner peripheral surface, it would be necessary to clean the friction amplifier when switching between workpieces. The friction amplifier is integrated with the inner peripheral surface. This makes cleaning the friction amplifier complicated. Furthermore, depending on the degree of cleaning, the workpiece before switching may remain in the friction amplifier. In this case, there is a risk of contamination.

[0021] In contrast, with this configuration, when switching between workpieces, the friction amplifier can be removed from the inner circumferential surface and cleaned from the outside of the cylindrical section. This simplifies cleaning of the friction amplifier. Furthermore, the friction amplifier can be replaced depending on the workpiece switching. This makes it possible to prevent contamination from occurring. For example, it is possible to prevent defects in workpieces of a particular lot from spreading to workpieces of other lots.

[0022] Furthermore, the friction amplifying unit can be removed from the inner circumferential surface for cleaning, which increases the flexibility of cleaning work. This allows the friction amplifying unit to be thoroughly cleaned. Therefore, even when a common friction amplifying unit is used for multiple different types of workpieces, contamination can be prevented.

[0023] (5) In any of the above configurations, the friction amplifying unit is preferably a mesh member. With this configuration, the mesh of the mesh member can be used to amplify the frictional force on the workpiece. Furthermore, if an existing mesh member is used as the friction amplifying unit (of course, a mesh member specifically designed for this configuration can be used instead of an existing one), the procurement cost of the friction amplifying unit can be reduced. [Effects of the Invention]

[0024] The rotary kiln of the present disclosure allows for rapid heat treatment of the entire workpiece. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a cross-sectional view of a rotary kiln according to one embodiment of the present disclosure taken along the front-rear direction. [Figure 2] FIG. 2 is a cross-sectional view taken along the line II-II in FIG. [Figure 3] FIG. 3 is an enlarged view of the area within the frame III in FIG. [Figure 4] FIG. 4 is a development view of the inner circumferential surface of the cylindrical portion in section IV of FIG. [Figure 5] FIG. 5 is an enlarged view of the area within circle V in FIG. [Figure 6] FIG. 6 is a radial cross-sectional view of a rotary kiln with a lifter. [Figure 7] FIG. 7 is a graph showing the change in temperature of the workpiece. DETAILED DESCRIPTION OF THE INVENTION

[0026] An embodiment of the rotary kiln of the present disclosure will now be described. FIG. 1 shows a cross-sectional view of the rotary kiln in the front-to-rear direction of this embodiment. FIG. 2 shows a cross-sectional view taken along the line II-II in FIG. 1. FIG. 3 shows an enlarged view of the area within frame III in FIG. 1. FIG. 4 shows a developed view of the inner circumferential surface of the cylindrical section in section IV in FIG. 2. FIG. 5 shows an enlarged view of the area within circle V in FIG. 2. For ease of explanation, the mesh member 4 is shown in a simplified schematic form in FIGS. 1 and 3. In addition, in FIG. 5, large-diameter particles w1 at the beginning of heat treatment are shown by dotted lines, and small-diameter particles w2 at the end of heat treatment are shown by solid lines.

[0027] [Configuration of a rotary kiln] First, the configuration of the rotary kiln of this embodiment will be described. As shown in Figure 1, the rotary kiln 1 of this embodiment includes a cylindrical section 2, a pressure reducing section 3, a mesh member 4, a sliding section 5, a material supply section 60, a material carry-in section 61, a heat medium supply section 62, and a stand 9.

[0028] The rotary kiln 1 of this embodiment is an externally heated rotary kiln. As shown in Fig. 1, the rotary kiln 1 of this embodiment heats the heat treatment chamber 203, i.e., the workpiece W, from outside the heat treatment chamber 203 by a heat medium (hot water in this embodiment) flowing through a heat medium flow path 202 (described later).

[0029] (Frame 9) 1 and 2, the base 9 supports the cylindrical portion 2, which will be described later. The base 9 includes a support floor 91, a carry-in portion support portion 93, and a cylindrical portion support portion 94.

[0030] As shown in Fig. 1, the loading section support part 93 is disposed on the upper surface of the support floor 91. The loading section support part 93 is provided with two bearings 930, one in the front and one in the rear. The cylindrical section support part 94 is disposed on the upper surface of the support floor 91. The cylindrical section support part 94 is provided with two roller devices 940, one in the front and one in the rear.

[0031] As shown in Figures 1 and 2, the rear roller device 940 has two roller units 940a, one on the left and one on the right. The right roller unit 940a has two bearings 940b, one on the front and one on the back, and a roller 940c. The roller 940c is disposed between the two bearings 940b. The roller 940c can rotate around its own axis by means of the two bearings 940b.

[0032] 2, in the rear roller device 940, the configuration of the left roller unit 940a is the same as the configuration of the right roller unit 940a described above. As shown in FIG. 1, the configuration of the front roller device 940 is the same as the configuration of the rear roller device 940.

[0033] (Cylindrical part 2) As shown in Figures 1 and 2, the cylindrical portion 2 includes a cylindrical wall 20, a cover wall 21, a cylindrical portion side flange 22, and two front and rear tires 23. The cylindrical wall 20 is cylindrical and extends in the front-to-rear direction (axial direction (extension direction of axis D of the cylindrical portion 2), a direction parallel to the support floor 91). The cylindrical wall 20 includes an outer peripheral wall 200 and an inner peripheral wall 201. The inner peripheral wall 201 is disposed radially inward of the outer peripheral wall 200 (radial direction centered on axis D). An inner peripheral surface 201a of the inner peripheral wall 201 is a smooth surface without any irregularities.

[0034] 2, a heat treatment chamber 203 for subjecting workpieces W to heat treatment is defined radially inward of the inner circumferential surface 201a of the inner circumferential wall 201 (more specifically, radially inward of the inner circumferential surface 201a and a mesh member 4 described later). The workpieces W are batch-processed in the heat treatment chamber 203. A heat medium flow path 202 for heating the heat treatment chamber 203 is defined between the outer circumferential wall 200 and the inner circumferential wall 201 (inside the cylindrical wall 20).

[0035] 1, the cover wall 21 is disk-shaped and detachably disposed at the front end (one axial end) of the cylindrical wall 20. The cover wall 21 covers the front end opening of the cylindrical wall 20. The cover wall 21 can open and close the front end opening of the cylindrical wall 20.

[0036] As shown in Fig. 1, the cylindrical portion side flange 22 is disk-shaped and is disposed at the rear end (the other axial end) of the cylindrical wall 20. The cylindrical portion side flange 22 is fixed to the rear end opening of the cylindrical wall 20. As shown in Fig. 3, a through hole 220 is formed in the radial center of the cylindrical portion side flange 22.

[0037] As shown in Fig. 1, the two front and rear tires 23 protrude radially outward from the outer circumferential surface of the outer circumferential wall 200. As shown in Fig. 2, the rear tire 23 is rotatably mounted on two left and right roller portions 940a (specifically, rollers 940c) of the rear roller device 940. Similarly, the front tire 23 is rotatably mounted on two left and right roller portions 940a (specifically, rollers 940c) of the front roller device 940. The two front and rear tires 23, i.e., the tubular portion 2, are rotatable around their own axis D.

[0038] (Decompression section 3) 1, the pressure reducing unit 3 is disposed on the upper surface of the support bed 91. The pressure reducing unit 3 is a vacuum pump. The pressure reducing unit 3 is capable of reducing the pressure in the heat treatment chamber 203. An exhaust path E is formed between the heat treatment chamber 203 and the pressure reducing unit 3.

[0039] (Sliding part 5) 1 and 3, the sliding part 5 is connected to the rear end of the cylindrical part 2 (heat treatment chamber 203). The sliding part 5 includes a first rotary joint 50 and a second rotary joint 51.

[0040] (First rotary joint 50) 1 and 3, the first rotary joint 50 airtightly connects the heat treatment chamber 203 on the rotating side (the side that rotates with the rotation of the cylindrical portion 2) to the heat medium supply unit 62 and the pressure reduction unit 3 on the fixed side (the side that does not rotate even when the cylindrical portion 2 rotates). The first rotary joint 50 includes a first rotating side inner member 500, a first fixed side outer member 501, two front and rear bearings 502, and two front and rear seal rings 503.

[0041] The first rotating side inner member 500 is fixed to the rear surface (the hole edge portion of the through hole 220) of the cylindrical portion side flange 22 of the cylindrical portion 2. The first rotating side inner member 500 is cylindrical and extends in the front-rear direction.

[0042] The first fixed-side outer member 501 is disposed radially outward of the first rotating-side inner member 500. The first fixed-side outer member 501 is cylindrical and extends in the front-to-rear direction. Two annular bearing accommodating grooves 501a, one at the front and one at the rear, and two annular seal ring accommodating grooves 501b, one at the front and one at the rear, are recessed in the inner circumferential surface of the first fixed-side outer member 501. The two annular bearing accommodating grooves 501a are disposed at both ends of the first fixed-side outer member 501 in the front-to-rear direction. An annular bearing 502 is accommodated in the bearing accommodating groove 501a. The bearing 502 rotatably supports the first rotating-side inner member 500 relative to the first fixed-side outer member 501.

[0043] The two front and rear seal ring accommodating grooves 501b are arranged midway between the two front and rear bearing accommodating grooves 501a in the front-rear direction. An annular seal ring 503 is accommodated in the seal ring accommodating groove 501b. The seal ring 503 is fixed to the first fixed-side outer member 501 and is in sliding contact with the first rotating-side inner member 500. The seal ring 503 seals the gap between the first fixed-side outer member 501 and the first rotating-side inner member 500.

[0044] (Second rotary joint 51) 1 and 3, the second rotary joint 51 airtightly connects the heat medium flow path 202 on the rotating side and the heat medium supply unit 62 on the fixed side. The second rotary joint 51 includes a second fixed-side inner member 510, a second rotating-side outer member 511, two front and rear bearings 512, three front and rear seal rings 513, and a joint-side flange 514.

[0045] The second fixed side inner member 510 is annularly mounted on the outer peripheral surface of the first fixed side outer member 501. The second fixed side inner member 510 is cylindrical and extends in the front-to-rear direction. The first fixed side outer member 501, i.e., the first rotary joint 50, is disposed radially inward of the second fixed side inner member 510, i.e., the second rotary joint 51. The first rotary joint 50 and the second rotary joint 51 can be easily separated by sliding the second rotary joint 51 rearward relative to the first rotary joint 50. In other words, the first rotary joint 50 and the second rotary joint 51 can be maintained (repaired, replaced, etc.) independently of each other.

[0046] The outer peripheral surface of the second fixed-side inner member 510 is recessed with an annular heat medium supply groove 510a, an annular heat medium discharge groove 510b, and three annular seal ring accommodating grooves 510c in the front and rear. These grooves are arranged alternately in the front-rear direction. Two seal ring accommodating grooves 510c are arranged on both front-rear sides of the heat medium supply groove 510a. Similarly, two seal ring accommodating grooves 510c are arranged on both front-rear sides of the heat medium discharge groove 510b.

[0047] An annular seal ring 513 is accommodated in the seal ring accommodating groove 510c. The seal ring 513 is fixed to the second fixed side inner member 510 and is in sliding contact with the second rotation side outer member 511. The seal ring 513 seals the gap between the second fixed side inner member 510 and the second rotation side outer member 511.

[0048] An inner-side heat medium supply hole 510d and an inner-side heat medium discharge hole 510e are formed inside the cylindrical wall of the second fixed-side inner member 510. The inner-side heat medium supply hole 510d connects the rear end surface of the second fixed-side inner member 510 to the bottom surface of the heat medium supply groove 510a. The inner-side heat medium discharge hole 510e connects the rear end surface of the second fixed-side inner member 510 to the bottom surface of the heat medium discharge groove 510b. The inner-side heat medium supply hole 510d and the inner-side heat medium discharge hole 510e are arranged radially opposite each other with a central angle of 180° (their centers are on axis D shown in FIG. 2 ; the same applies below).

[0049] The second rotation-side outer member 511 is disposed radially outside the second fixed-side inner member 510. The second rotation-side outer member 511 is cylindrical and extends in the front-rear direction. Two annular bearing accommodating grooves 511a, one in front and one in rear, are recessed into the inner circumferential surface of the second rotation-side outer member 511. The two annular bearing accommodating grooves 511a, one in front and one in rear, are disposed at both ends of the second rotation-side outer member 511 in the front-rear direction (outside the three seal ring accommodating grooves 510c in the front-rear direction). An annular bearing 512 is accommodated in the bearing accommodating groove 511a. The bearing 512 rotatably supports the second rotation-side outer member 511 with respect to the second fixed-side inner member 510.

[0050] An outer-side heat medium supply hole 511d and an outer-side heat medium discharge hole 511e are formed inside the cylindrical wall of the second rotating-side outer member 511. The outer-side heat medium supply hole 511d penetrates the cylindrical wall in the radial direction. The radially inner end of the outer-side heat medium supply hole 511d is connected to the heat medium supply groove 510a. The outer-side heat medium discharge hole 511e penetrates the cylindrical wall in the radial direction. The radially inner end of the outer-side heat medium discharge hole 511e is connected to the heat medium discharge groove 510b. The outer-side heat medium supply hole 511d and the outer-side heat medium discharge hole 511e are arranged with a central angle of 180° offset from each other (diametrically opposed).

[0051] The joint-side flange 514 shown in Fig. 3 has an annular plate shape when viewed in the front-rear direction (axial direction). The joint-side flange 514 is fixed to the front end surface of the second rotating-side outer member 511. The joint-side flange 514 and the cylindrical portion-side flange 22 are connected by a plurality of connecting members (bolts with spacers) 99.

[0052] (Net member 4) As shown in Figures 2, 4, and 5, the mesh member 4 is disposed all around the inner circumferential surface 201a (heat transfer surface exposed to the heat treatment chamber 203) of the inner circumferential wall 201 of the cylindrical wall 20. That is, the mesh member 4 is disposed all over the inner circumferential surface 201a. The mesh member 4 has an overall cylindrical shape. The mesh member 4 is detachable from the inner circumferential surface 201a.

[0053] The mesh member 4 is a woven wire mesh. The mesh member 4 has a plurality of vertical wires 40 and a plurality of horizontal wires 41. The vertical wires 40 and the horizontal wires 41 intersect with each other in a lattice pattern. The vertical wires 40 extend in the front-to-rear direction (axial direction) while curving in a wavy line in the radial direction. The vertical wires 40 are arranged side by side at predetermined intervals in the circumferential direction (the circumferential direction centered on the axis D of the tubular portion 2). The horizontal wires 41 extend in the circumferential direction while curving in a wavy line in the radial direction. The horizontal wires 41 are arranged side by side at predetermined intervals in the front-to-rear direction.

[0054] The mesh 42 is defined by any pair of adjacent vertical lines 40 and any pair of adjacent horizontal lines 41. The mesh 42 is included in the concept of "recess" in the present disclosure. The multiple meshes 42 are arranged over the entire inner circumferential surface 201a of the inner circumferential wall 201 of the cylindrical wall 20. The mesh 42 penetrates the mesh member 4 in the radial direction.

[0055] The plurality of meshes 42 (i.e., recesses) are arranged over the entire inner circumferential surface 201a. As described above, the vertical lines 40 and horizontal lines 41 are each curved in a wavy line shape. Therefore, the inner and outer circumferential surfaces of the cylindrical mesh member 4 each have an uneven shape. In contrast, the inner circumferential surface 201a of the tubular portion 2 is a smooth surface without any unevenness. Therefore, the frictional force of the mesh member 4 against the workpiece W is amplified relative to the inner circumferential surface 201a.

[0056] (Material supply unit 60) 1, the workpiece supply section (hopper) 60 is disposed on the upper surface of the support floor 91 via legs 600. The workpiece supply section 60 is disposed on the front side of the cylindrical section 2. Workpieces W to be heat-treated are stored in the workpiece supply section 60.

[0057] (Workpiece loading section 61) As shown in FIG. 1 , the workpiece carry-in section (screw feeder) 61 is disposed at the front side of the cylindrical section 2. The workpiece carry-in section 61 is connected to the lower side of the workpiece supply section 60 via a supply pipe 98. The rotation shaft of the workpiece carry-in section 61 is rotatably supported by two bearings 930 of the carry-in section support section 93. The rear portion of the workpiece carry-in section 61 penetrates the cover wall 21 and is inserted into the heat treatment chamber 203. The workpiece carry-in section 61 transports the workpiece W that flows down from the workpiece supply section 60 to the heat treatment chamber 203.

[0058] (heat medium supply section 62) As shown in FIG. 1, the heat medium supply unit 62 is disposed on the upper surface of the support bed 91. The heat medium supply unit 62 supplies the heat medium (hot medium) to the heat medium flow path 202 via the second rotary joint 51 shown in FIG. 3. The heat medium supply unit 62 includes a temperature adjustment unit (not shown, such as a heat exchanger) and a liquid transfer unit (not shown, such as a pump). The temperature adjustment unit can adjust the temperature of the heat medium to a predetermined temperature. The liquid transfer unit can pump the heat medium.

[0059] As shown in FIGS. 1 and 3, a heat medium path F is formed between the heat medium supply unit 62 and the heat medium passage 202, and follows the path (circulation path) of "heat medium supply unit 62 → second rotary joint 51 (more specifically, inner-side heat medium supply hole 510d → heat medium supply groove 510a → outer-side heat medium supply hole 511d) → heat medium passage 202 → second rotary joint 51 (more specifically, outer-side heat medium discharge hole 511e → heat medium discharge groove 510b → inner-side heat medium discharge hole 510e) → heat medium supply unit 62 again."

[0060] [Heat treatment method] Next, a heat treatment method using the rotary kiln of this embodiment will be described. The heat treatment method includes a supply step, a depressurization step, a heat treatment step, a pressure recovery step, and a discharge step. In the supply step, the workpiece carry-in section 61 shown in FIG. 1 is driven to transport the workpiece W before heat treatment (before drying) from the workpiece supply section 60 to the heat treatment chamber 203. The workpiece W is an aggregate of numerous granular particles w1. A fixed amount of the workpiece W is supplied to the heat treatment chamber 203. Next, a supply valve (not shown) arranged in the supply piping 98 is closed to block communication between the workpiece supply section 60 and the heat treatment chamber 203.

[0061] 1 and 3 is driven to rotate the cylindrical portion 2 around its axis D (see FIG. 2). Next, a pressure reducing valve (not shown) disposed in the exhaust path E is opened to drive the pressure reducing portion 3, and the pressure in the heat treatment chamber 203 is reduced to a predetermined pressure via the exhaust path E.

[0062] In the heat treatment step, the heat medium in the heat medium path F is heated by the temperature adjustment unit of the heat medium supply unit 62. The heated heat medium heats the heat treatment chamber 203, i.e., the workpiece W, in a predetermined temperature pattern via the heat medium flow path 202 and the inner peripheral wall 201. That is, the predetermined heat treatment is performed on the workpiece W while the heat treatment chamber 203 is rotated and depressurized. Specifically, the workpiece W is dried.

[0063] In the pressure recovery process, the rotation of the cylindrical portion 2 is stopped, and dry air (or inert gas) is introduced into the heat treatment chamber 203 via a gas supply pipe (not shown). That is, the pressure in the heat treatment chamber 203 is returned to atmospheric pressure. In the discharge process, the cover wall 21 is removed from the cylindrical portion 2, and the heat-treated workpiece W is removed from the heat treatment chamber 203. As in the discharge process, the mesh member 4 can be attached to and detached from the inner circumferential surface 201a by removing the cover wall 21 from the cylindrical portion 2.

[0064] [Action and effect] Next, the effects of the rotary kiln of this embodiment will be described. As shown in FIGS. 2, 4, and 5, the mesh member 4 is disposed all around the inner peripheral surface 201a (heat transfer surface exposed to the heat treatment chamber 203) of the inner peripheral wall 201 of the cylindrical wall 20. The inner peripheral surface 201a is a smooth surface without any irregularities. Therefore, compared to when the mesh member 4 is not disposed on the inner peripheral surface 201a, the workpiece W can more easily follow the rotating inner peripheral surface 201a (mesh member 4) during the heat treatment process. Therefore, the workpiece W can rise to a high position while following the inner peripheral surface 201a. This facilitates the rolling of the workpiece W when it descends (flows down, falls, etc.) due to its own weight.

[0065] When the rolling of the workpiece W is promoted, the contact surface (heat transfer surface) of the workpiece W with the inner circumferential surface 201a is more likely to be renewed. Therefore, heat is more likely to be diffused throughout the workpiece W. Therefore, heat treatment can be performed quickly throughout the workpiece W. In other words, the entire workpiece W can be dried quickly. Furthermore, when the rolling of the workpiece W is promoted, the vapor diffusion surface (surface exposed to the heat treatment chamber 203) of the workpiece W is more likely to be renewed. Therefore, the entire workpiece W can be dried quickly.

[0066] FIG. 6 shows a radial cross-sectional view of a rotary kiln with lifters. The same reference numerals are used to denote corresponding parts to those in FIG. 2. As shown in FIG. 6, in the case of a rotary kiln 100 having a pair of lifters 101 on the inner peripheral surface 201a, the workpiece W is elevated by being lifted by the lifters 101. In contrast, in the case of the rotary kiln 1 of this embodiment, as shown in FIGS. 2, 4, and 5, the workpiece W is elevated by the frictional force between the workpiece W and the mesh member 4 (inner peripheral surface 201a). Thus, the rotary kiln 100 with lifters 101 and the rotary kiln 1 of this embodiment essentially differ in the mechanism for elevating the workpiece W.

[0067] Furthermore, in the case of the rotary kiln 100 with the lifter 101, the workpiece W does not move continuously. The workpiece W moves intermittently only when transferring from the inner circumferential surface 201a to the lifter 101 and when transferring from the lifter 101 to the inner circumferential surface 201a.

[0068] In contrast, in the rotary kiln 1 of this embodiment, the position (height and angle) of any given portion of the inner circumferential surface 201a changes continuously as the cylindrical portion 2 rotates. Therefore, the position of the workpiece W deposited in that given portion also changes continuously. Therefore, the workpiece W continuously rises and falls depending on the position of the workpiece W, the dynamic angle of repose, and internal friction resistance (resistance due to friction and meshing between particles w1 and w2 that make up the powder, as shown in FIG. 5).

[0069] As described above, the rotary kiln 1 of this embodiment allows the workpiece W to be continuously moved relative to the rotary kiln 100 equipped with the lifter 101. This allows heat to be continuously diffused throughout the workpiece W. This allows the entire workpiece W to be quickly heat-treated. Furthermore, the thermal history of the entire workpiece W is less likely to vary. This makes it easier to homogenize the quality of the workpiece W after heat treatment.

[0070] As shown in Fig. 1, the rotary kiln 1 of this embodiment includes a heat medium flow path (heat source) 202 isolated from a heat treatment chamber 203. In other words, the rotary kiln 1 is an externally heated rotary kiln. Therefore, the heat treatment chamber 203 can be indirectly heated from outside the heat treatment chamber 203 via the inner peripheral wall 201.

[0071] As shown in FIG. 1 , the rotary kiln 1 of this embodiment includes a pressure reduction section 3 capable of reducing the pressure in the heat treatment chamber 203. Therefore, the heat treatment chamber 203, i.e., the workpiece W, can be heated in a reduced-pressure environment. In a reduced-pressure environment, the amount of air (gas) in the heat treatment chamber 203 decreases, making heat treatment using convective heat transfer difficult. In contrast, the rotary kiln 1 of this embodiment has a mesh member 4 arranged around the entire inner circumferential surface 201a. This facilitates rolling of the workpiece W during the heat treatment process. This promotes heat conduction (heat conduction due to contact between the inner circumferential surface 201a of the inner circumferential wall (wall portion) 201 of the cylindrical portion 2 and the workpiece W). Thus, the rotary kiln 1 of this embodiment can quickly heat-treat the entire workpiece W, even in a reduced-pressure environment where convective heat transfer is difficult to utilize. Furthermore, the heat treatment performed in the heat treatment process is drying. The rotary kiln 1 of this embodiment can quickly dry the entire workpiece W.

[0072] As shown in FIG. 5, the workpiece W is in the form of a powder. At the beginning of heat treatment, the workpiece W is a wet powder, consisting of a large number of large-diameter particles w1. The large-diameter particles w1 are composed of a plurality of small-diameter particles. The particles are bonded to each other by a liquid bridging force acting between the particles. The particles w1 can enter and exit the mesh 42 of the mesh member 4 from the radially inner side (the heat treatment chamber 203 side). Therefore, the workpiece W can be raised to a position where the particles w1 that have entered the mesh 42 will fall out of the mesh 42 due to their own weight. This promotes the rolling of the workpiece W. Furthermore, when the particles fall out of the mesh 42, they climb over the vertical lines 40 below them and fall out radially inward. At this time, the particles w1 tend to roll. This also promotes the rolling of the workpiece W.

[0073] As the workpiece W dries, the liquid bridging force between the multiple particles constituting the particles w1 weakens. Furthermore, as the workpiece W rolls, the particles w1 are crushed. Therefore, as shown schematically in FIG. 5, at the end of the heat treatment, particles w2 smaller in diameter than the particles w1 appear in the workpiece W. Here, the vertical lines 40 and the horizontal lines 41 each extend in a wavy line shape. Therefore, gaps C are secured between the vertical lines 40 and the inner circumferential surface 201a and between the horizontal lines 41 and the inner circumferential surface 201a. Large-diameter particles w1 cannot pass through the gaps C, whereas small-diameter particles w2 can. Therefore, as the inner circumferential surface 201a rotates, the particles w2 are not caught in the mesh 42 (specifically, the vertical lines 40). Therefore, the upper limit position (the position where the height becomes highest as the inner circumferential surface 201a rotates (the position where the particle starts to descend)) of the particle w2 is lower than that of the particle w1. Therefore, only the particle w1, whose drying has not yet progressed, can be raised to a higher position than the particle w2, whose drying has almost completed.

[0074] The mesh member 4 shown in FIG. 1 is detachable in the front-to-rear direction relative to the inner peripheral surface 201a. Assume that heat treatment of multiple different types of workpieces W is performed in a shared rotary kiln 1. If the mesh member 4 were integrated with the inner peripheral surface 201a, it would be necessary to clean the mesh member 4 when switching between workpieces W. The mesh member 4 is integrated with the inner peripheral surface 201a. This makes cleaning the mesh member 4 complicated. Furthermore, depending on the degree of cleaning, the workpieces W before switching may remain on the mesh member 4. In this case, contamination may occur.

[0075] In contrast, with the rotary kiln 1 of this embodiment, when switching between workpieces W, the mesh member 4 can be removed from the inner circumferential surface 201a and cleaned outside the cylindrical portion 2. This simplifies the cleaning of the mesh member 4. Furthermore, the mesh member 4 can be replaced depending on the workpiece W being switched. This makes it possible to prevent contamination from occurring. For example, it is possible to prevent defects in a particular lot of workpieces W from spreading to other lots of workpieces W.

[0076] Furthermore, the mesh member 4 can be removed from the inner circumferential surface 201a for cleaning, which increases the flexibility of cleaning work. This allows the mesh member 4 to be thoroughly cleaned. Therefore, even when a common mesh member 4 is used for a plurality of different types of workpieces W, the occurrence of contamination can be suppressed.

[0077] Furthermore, the mesh member 4 is a wire mesh. Therefore, the mesh 42 can be used to amplify the frictional force against the workpiece W. Furthermore, the mesh member 4 is an existing woven wire mesh. Therefore, the procurement cost of the mesh member 4 can be reduced.

[0078] The vertical wires 40 of the mesh member 4 extend in the front-to-rear direction (axial direction). Therefore, even if the workpieces W are widely distributed in the front-to-rear direction, the workpieces W can be lifted. Furthermore, the vertical wires 40 extend in a direction perpendicular to the circumferential direction. Therefore, the workpieces W are more likely to get caught on the vertical wires 40 when being lifted, compared to when the vertical wires 40 extend in a direction intersecting the circumferential direction other than perpendicular. Therefore, the workpieces W can be lifted easily.

[0079] The opening area and opening ratio of the plurality of meshes 42 are constant over the entire surface of the inner circumferential surface 201a. Therefore, the amount of workpiece W accommodated in the meshes 42 is unlikely to vary over the entire surface of the inner circumferential surface 201a. Therefore, the thermal history is unlikely to vary over the entire workpiece W. Therefore, it is easy to homogenize the quality of the workpiece W after heat treatment.

[0080] 3 connects the heat treatment chamber 203, which is the target of pressure reduction, to the exhaust path E and the pressure reduction unit 3. Therefore, the first rotary joint 50 is required to have high airtightness. On the other hand, the second rotary joint 51 connects the heat medium flow path 202 to the heat medium supply unit 62. Therefore, the second rotary joint 51 is not required to have as high airtightness as the first rotary joint 50.

[0081] Let us assume that the two joints (first rotary joint 50, second rotary joint 51) are an inseparable unit. In this case, even if a malfunction occurs in only one of the joints, both joints must be replaced at the same time. This results in high maintenance costs. In particular, if a malfunction occurs in only the second rotary joint 51, which has low airtightness, not only the second rotary joint 51 but also the first rotary joint 50, which has high airtightness, must be replaced, which results in high maintenance costs.

[0082] In this regard, as shown in Fig. 3, in the rotary kiln 1 of this embodiment, the first rotary joint 50 and the second rotary joint 51 can be easily separated by sliding the second rotary joint 51 rearward relative to the first rotary joint 50. In other words, the first rotary joint 50 and the second rotary joint 51 can be maintained (repaired, replaced, etc.) independently. Therefore, of the two joints (first rotary joint 50, second rotary joint 51), only the joint in which a malfunction has occurred can be replaced.

[0083] As shown in Fig. 3, the two joints are stacked in the radial direction. That is, the two joints are arranged at the same position in the front-rear direction (axial direction). Therefore, the length of the sliding portion 5 in the front-rear direction can be shortened compared to a configuration in which the two joints are arranged offset in the front-rear direction.

[0084] [others] The rotary kiln according to the present disclosure has been described above. However, the present disclosure is not limited to the above embodiment. Various modifications and improvements can be made by those skilled in the art.

[0085] The rotary kiln 1 may be a batch type in which the workpieces W are heat-treated in fixed amounts, or a continuous type in which the workpieces W are continuously heat-treated while being transported. The type of heat medium flowing through the heat medium flow path 202 is not particularly limited. It may be hot water, oil, or the like. The rotary kiln 1 may be an internally heated type having a heat source inside the heat treatment chamber 203, or an externally heated type having a heat source outside the heat treatment chamber 203. The type of heat source is not particularly limited. In the case of an internally heated type, it may be a gas burner, or the like. In the case of an externally heated type, it may be an electric heater, microwave, IH (electromagnetic induction heating), or the like. The heat source may rotate integrally with the cylindrical portion 2. The heat source may be fixed to the frame 9 independently of the cylindrical portion 2.

[0086] There are no particular limitations on the shape of the vertical cross section (cross section perpendicular to the axis) of the inner circumferential surface 201a of the cylindrical portion 2. It may be a perfect circle or a polygonal shape (triangle, square, pentagon, hexagon, octagon, etc.).

[0087] The shape of the mesh member 4 (for example, the type, material, and arrangement of the mesh member 4, the material, wire diameter, and extension direction of the vertical wires 40, the material, wire diameter, and extension direction of the horizontal wires 41, the shape, size, opening rate, and pitch of the mesh 42, etc.) is not particularly limited. The type of mesh member 4 may be, for example, tortoiseshell wire mesh, woven wire mesh, diamond-shaped wire mesh, crimped wire mesh, welded wire mesh, expanded metal, punched metal, etc.

[0088] The direction in which the vertical lines 40 extend may be, for example, the front-rear direction or the circumferential direction. They may also extend in a direction intersecting (diagonal) with respect to the front-rear and circumferential directions. The same applies to the horizontal lines 41. The size of the mesh 42 may be 1 mm or more and 10 mm or less in width in the front-rear and circumferential directions. The pitch in the front-rear and circumferential directions may be uniform or non-uniform. The included angle (intersection angle) between the vertical lines 40 and the horizontal lines 41 when viewed from the radial direction (see FIG. 4) is not particularly limited. For example, it may be 30°, 45°, 60°, 90°, 120°, 135°, 150°, etc.

[0089] Regarding the arrangement of the mesh member 4, the mesh member 4 may be arranged over the entire length of the inner circumferential surface 201a in the front-rear direction (axial direction), or may be arranged in a portion of the inner circumferential surface 201a in the front-rear direction. When the mesh member 4 is arranged in a portion of the inner circumferential surface 201a in the front-rear direction, the mesh member 4 may be arranged locally in a single portion, or may be arranged dispersedly in multiple portions. When the mesh member 4 is arranged dispersedly in multiple portions, the shape, etc. of the mesh member 4 may be the same or different between the multiple portions.

[0090] The mesh member 4 may be disposed over the entire circumferential length of the inner circumferential surface 201a, or may be disposed only partially in the circumferential direction. When the mesh member 4 is disposed only partially in the circumferential direction of the inner circumferential surface 201a, the mesh member 4 may be disposed locally in a single portion, or may be disposed dispersedly in multiple portions. When the mesh member 4 is disposed dispersedly in multiple portions, the shape of the mesh 42 may be the same or different between the multiple portions.

[0091] A plurality of mesh members 4 may be stacked in the radial direction. For example, the plurality of mesh members 4 may be stacked so that the opening area of ​​the mesh 42 gradually decreases from the radially inner side (toward the heat treatment chamber 203) toward the radially outer side (toward the inner circumferential surface 201a). The rotational speed (movement speed) of the workpiece W accompanying the rotation of the mesh member 4 is not particularly limited. For example, it may be 0.5 rpm or more and 10 rpm or less.

[0092] Before or at the beginning of heat treatment, the workpiece W may be a wet powder or a dry powder. In other words, the moisture content of the workpiece W is not particularly limited. The shape, etc., of the particles w1 constituting the workpiece W is not particularly limited. The particles w1 may be granules (wet granules, frozen granules, etc.). The particles w1 may be circular (spherical), elliptical, polygonal, irregular, etc. Furthermore, the shapes, etc., of multiple particles w1 may be the same or different. The same applies to particles w2. There is no particular limitation on the shape, etc., between particles w1 at the beginning of heat treatment and particles w2 at the end of heat treatment. Compared to particles w1, particles w2 may have a smaller diameter (e.g., reduced by crushing), the same diameter, or a larger diameter (e.g., increased by granulation). The presence or size of the gap C shown in Figure 5 is not particularly limited. If gap C is present, gap C may be set to a size that prevents both particles w1 and w2 from passing through. Alternatively, the gap C may be set to a size that allows both particles w1 and w2 to pass through. If particle w2 has a smaller diameter than particle w1, the gap C may be set to a size that prevents particle w1 from passing through but allows particle w2 to pass through.

[0093] The cylindrical portion 2 may be supported so as to be tiltable relative to the stand 9 in the direction in which the axis D is tilted. In this way, the workpiece W can be easily moved in the axial direction (the direction in which the axis D extends) in the heat treatment step. Also, the workpiece W can be easily moved to the front side (the carrying-out side) in the discharge step.

[0094] The ultimate pressure of the heat treatment chamber 203 during the decompression step is not particularly limited. It may be 20,000 Pa or lower, or the boiling point of 60°C or lower. Under these conditions, it is difficult to utilize convective heat transfer. Even under such an environment, the rotary kiln 1 can promote heat conduction (heat conduction due to contact between the inner circumferential surface 201a of the inner circumferential wall (wall portion) 201 of the cylindrical portion 2 and the workpiece W).

[0095] The atmosphere in the heat treatment chamber 203 during the heat treatment step is not particularly limited, and may be a vacuum or a predetermined gas (e.g., air, inert gas, neutral gas, oxidizing gas, reducing gas, nitriding gas, carburizing gas, decarburizing gas, etc.). [Example]

[0096] Hereinafter, an experiment conducted using the rotary kiln of the present disclosure will be described with reference to FIGS.

[0097] [Configuration of a rotary kiln] First, the configurations of the rotary kilns used in the experiments (Examples 1 and 2, Comparative Example 1) will be described. Example 1 is a rotary kiln with a configuration similar to that of the rotary kiln 1 shown in Figures 1 to 5 (however, as will be described later, the shape of the tubular portion 2 (inner diameter and front-rear (axial) length)) is different). On the inner peripheral surface 201a of Example 1, a woven wire mesh member 4 (EA962BC-11, manufactured by ESCO Corporation) shown in Figures 4 and 5 is arranged. The material of the mesh member 4 is SUS304. The number of meshes is 4. The wire diameters (diameters) of the vertical wires 40 and horizontal wires 41 are each 1.1 mm. The front-rear width and circumferential width of the mesh 42 are each 5.3 mm. The opening ratio is 68%.

[0098] In Example 2, the rotary kiln 1 of Example 1 is modified such that a punched metal mesh member (EA952B-104, manufactured by ESCO Corporation) is disposed on the inner peripheral surface 201a of the cylindrical portion 2 instead of the woven wire mesh member 4 shown in Figures 4 and 5. The mesh member is made of SUS304. The hole diameter is 5 mm. The pitch is 8 mm. The opening ratio is 35%.

[0099] Comparative Example 1 is the rotary kiln 100 shown in Figure 6. A pair of lifters 101 are arranged on the inner peripheral surface 201a of Comparative Example 1, offset by a central angle of 180° (diametrically opposed). The inclination angle θ of the lifters 101 with respect to the inner peripheral surface 201a is 30°. The protrusion amount L of the lifters 101 from the inner peripheral surface 201a is 20 mm.

[0100] [Heat treatment conditions] The following heat treatment conditions and specifications were common to all rotary kilns. In contrast to the long-axis cylindrical rotary kiln 1 shown in FIG. 1, the rotary kiln used in the experiment had a short-axis cylindrical shape. Specifically, the inner diameter (diameter) of the inner circumferential surface 201a of the cylindrical portion 2 was 100 mm. The length of the inner circumferential surface 201a of the cylindrical portion 2 in the front-to-rear direction was 100 mm. The rotation speed of the inner circumferential surface 201a was 2 rpm. The heat medium flowing through the heat medium flow path 202 was hot water at a temperature of 60°C. In other words, the heating method was hot water heating. The flow rate of the hot water was 1 liter / min. The pressure in the heat treatment chamber 203 was 3000 Pa.

[0101] The material W to be treated is a mixture of the raw materials acetaminophen, lactose, cornstarch, crystalline cellulose, and hydroxypropyl cellulose in a mass ratio of 10:43:18.5:25:3.5 (acetaminophen:lactose:cornstarch:crystalline cellulose:hydroxypropyl cellulose), which is then hydrated with 30% water (the sum of the mass of the mixture and the mass of water is 100%) and granulated. The average particle size of particles w1 at the initial stage of heat treatment (median diameter of particle size distribution measured by laser diffraction or the like) is approximately 200 μm. The amount of material W to be treated placed in the heat treatment chamber 203 is 50 g.

[0102] [Experimental method and results] The experiment was conducted by drying the workpiece W using each rotary kiln under the above-mentioned experimental conditions. Figure 7 shows a graph of the temperature change of the workpiece W. The horizontal axis represents time, and the vertical axis represents the temperature of the workpiece W. The dashed dotted line also represents the boiling point at 3000 Pa (pressure in the heat treatment chamber 203).

[0103] As shown in Fig. 7, the temperature at which the temperature of the workpiece W begins to rise from the boiling point is, in ascending order, Example 1, Example 2, and Comparative Example 1. From this, it can be seen that the drying time of the workpiece W is, in descending order, Example 1, Example 2, and Comparative Example 1. In other words, it can be seen that the drying time (heat treatment time) of the workpiece W is shorter in the rotary kiln 1 equipped with the mesh member 4 (Example 1 and Example 2) than in the rotary kiln 100 equipped with the lifter 101 (Comparative Example 1). [Explanation of symbols]

[0104] 1: rotary kiln, 2: cylindrical portion, 20: cylindrical wall, 200: outer peripheral wall, 201: inner peripheral wall, 201a: inner peripheral surface, 202: heat transfer medium flow path, 203: heat treatment chamber, 21: cover wall, 22: cylindrical portion side flange, 220: through hole, 23: tire, 3: pressure reducing portion, 4: mesh member, 40: vertical line, 41: horizontal line, 42: mesh (recess), 5: sliding portion, 50: first rotary joint, 500: first rotating side inner member, 501: first fixed side outer member, 501a: bearing accommodating groove, 501b: seal ring accommodating groove, 502: bearing, 503: seal ring, 51: second rotary joint, 510: second fixed side inner member, 510a: heat transfer medium supply groove, 510b: heat transfer medium discharge groove, 510c: Seal ring accommodating groove, 510d: inner side heat medium supply hole, 510e: inner side heat medium discharge hole, 511: second rotating side outer member, 511a: bearing accommodating groove, 511d: outer side heat medium supply hole, 511e: outer side heat medium discharge hole, 512: bearing, 513: seal ring, 514: joint side flange, 60: workpiece supply section, 600: leg, 61: workpiece carry-in section, 62: heat medium supply section, 9: stand, 91: support bed, 93: carry-in section support section, 930: bearing, 94: cylindrical section support section, 940: roller device, 940a: roller section, 940b: bearing, 940c: roller, 98: supply piping, 100: rotary kiln, 101: lifter C: Gap, D: Shaft, E: Exhaust path, F: Heat transfer medium path, L: Protrusion, W: Object to be treated, w1: Particle, w2: Particle, θ: Inclination angle

Claims

1. a cylindrical portion that is rotatable about its own axis and has a heat treatment chamber for performing heat treatment on a powder-like treatment object; a friction amplifying portion having a concave-convex shape, the friction amplifying portion being disposed on at least a portion of the inner circumferential surface of the cylindrical portion and amplifying the frictional force against the object to be treated; A rotary kiln equipped with:

2. 2. The rotary kiln according to claim 1, which is an externally heated type and includes a pressure reducing section for reducing the pressure in the heat treatment chamber.

3. The powder-like material to be processed is an aggregate of a large number of particles, The rotary kiln according to claim 1 , wherein the friction amplification portion has a recess through which at least some of the particles can enter and exit.

4. The rotary kiln according to claim 1 , wherein the friction amplification portion is detachable from the inner circumferential surface.

5. The rotary kiln according to claim 4, wherein the friction amplifying portion is a mesh member.

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