KR20210011430A - Crushing roller manufacturing method and temperature raising device - Google Patents

Abstract

The manufacturing method of the crushing roller includes a journal housing rotatably supported with respect to the housing of a crusher, and a cured portion 26 provided on the outer circumferential surfaces of the annular base 25 and the base 25 and having a smaller coefficient of thermal expansion than the base 25. As a manufacturing method of a crushing roller having an annular roller portion 24 having ), the central axis C1 of the roller portion 24 is disposed in a direction orthogonal to the bottom surface, and the inner peripheral surface is external air. A heating process of heating the roller part 24 from the outer circumferential side in a state open to the journal housing and the roller part 24 in a heated state by the heating process, and the inner circumferential surface of the roller part 24 is the journal housing. An arrangement step of arranging so as to face or contact the outer peripheral surface of and a fitting step of cooling the roller portion 24 arranged in the arrangement step to fit the journal housing and the roller portion 24 are provided.

Description

Crushing roller manufacturing method and temperature raising device

The present invention relates to a method for manufacturing a crushing roller and a temperature increasing device.

A pulverizer that pulverizes solid fuels such as coal into fine powders smaller than a predetermined particle diameter, and is used for the purpose of supplying them to a combustion device, etc., and rotates around vertical vertical axes. A pulverizer is known that pulverizes an object to be pulverized placed on a pulverizing table to be pulverized by pressing a crushing roller rotatably supported in the pulverizer.

A crushing roller used in such a pulverizer has a journal housing rotatably mounted with respect to the housing of the pulverizer, and a roller portion formed of a metallic material that is actually pressed in contact with the pulverized object. In addition, the journal housing and the roller portion are fitted by shrink fitting, and when the roller portion is worn, the roller portion is removed to enable maintenance (for example, the pulverizing machine of Patent Document 1). (微粉炭機) roller).

Japanese Patent Publication No. 5259162

However, recently, as a crushing roller used in a pulverizer, a crushing roller having a roller part with a hardened part on its surface, and furthermore, a ceramic embedded casting roller in which ceramic is embedded in the surface of a roller part made of high chromium cast iron with excellent wear resistance. It may be used. Since the ceramic buried type casting roller can pulverize not only the ceramic part of the surface but also the high chromium cast iron as the base material, the allowable amount of wear is greatly increased, and the pulverization roller can have a long life.

However, the ceramic-embedded casting roller has a different coefficient of thermal expansion between the hardened part provided on the surface of the roller part (particularly, the ceramic embedded in the hardened part) and the base material made of high chromium cast iron. For this reason, when the roller part and the base material are assembled by shrink fitting as in the pulverized coal machine roller of Patent Document 1, the hardened part (especially the ceramic part) on the surface is different from the difference in the coefficient of thermal expansion when the roller part is heated by heating. Because there is a possibility of damaging ), assembly by fitting gaps was the mainstream. In order to perform this gap fitting, in addition to the dimension management of the fitting portion between the journal housing and the roller portion, mounting of the fixing member is required, which increases the cost of remodeling and the maintenance work. there was.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method of manufacturing a crushing roller and a temperature increasing device capable of making it difficult to damage the hardened part by making it difficult for cracks to propagate to the hardened part during shrink fit. do.

In order to solve the above problems, the method for manufacturing a crushing roller and the temperature raising device of the present invention employ the following means.

A method of manufacturing a crushing roller according to an aspect of the present invention is used in a pulverizer for pulverizing an object to be pulverized, a support portion rotatably supported with respect to a housing of the pulverizer, an annular base, and a base of the base. A method of manufacturing a crushing roller provided on an outer circumferential surface in a radial direction and having an annular roller portion having a hardened portion having a different thermal expansion coefficient from the base, wherein the central axis of the roller portion is in a direction orthogonal to the bottom surface, and the roller A heating step of heating the roller part from the outer circumferential side of the roller part in a state where the inner circumferential surface in the negative radial direction is open to the outside air, and the roller in a state in which the temperature is raised by the support part and the heating step And an arrangement step of arranging the part so that the inner circumferential surface of the roller part faces or contacts the outer circumferential surface of the support part, and a fitting step of cooling the roller part disposed in the arrangement step to fit the support part and the roller part.

In the above configuration, the roller part and the support part are fitted by so-called shrink fitting, which is fitted with the support part by cooling the heated roller part.

In the above configuration, in the heating step, the roller portion is heated from the outer peripheral surface side with the inner peripheral surface of the roller portion open to the outside air. For this reason, the outer circumferential surface side of the roller part heats up faster than the inner circumferential surface side, and becomes hotter than the inner circumferential surface side. Thereby, the base of the roller part thermally expands outward in the radial direction (that is, so that the outer shape becomes large). On the other hand, since the hardened portion has a different coefficient of thermal expansion than the base, the amount of thermal expansion is smaller than that of the base, or the amount of thermal expansion is greater than that of the base. Therefore, when the roller part thermally expands outward in the radial direction, a pressing force acts on the hardened part in the radial direction by being constrained by the base. For this reason, compressive stress in the radial direction is generated in the hardened portion. In this way, in the heating step of heating the roller part, since the stress generated in the hardened part can be mainly made into compressive stress, the tensile stress generated in the hardened part can be suppressed, and cracks can hardly propagate in the hardened part. . Therefore, it can be made difficult to damage the hardened part.

In addition, since the roller part and the support part can be fitted by shrink fitting in this way, even if it is a crushing roller having a hardened part on the outer circumferential surface, no special processing is performed on the roller part and the support part, and the roller part and the support part are fitted together. Can be manufactured. Therefore, compared with the method of performing special processing on the roller part and the support part, while reducing the cost, it is possible to shorten the time required for manufacturing.

Further, the roller portion is heated from the outer peripheral surface side in a state in which the central axis of the roller portion becomes a direction orthogonal to the bottom surface, and the inner peripheral surface is open to the outside air (in other words, the air is open). Thereby, the air in the space formed inside the inner circumferential surface of the annular roller part (hereinafter, referred to as "inner space") is heated by heating, and by the chimney effect, the air is discharged into the atmosphere as a rising airflow. Therefore, since the heated air does not stay in the inner space, the expansion of the temperature distribution on the inner circumferential surface of the roller portion can be suppressed and the occurrence of uneven stress in the entire roller portion can be suppressed. Therefore, it can be made difficult to damage the roller part. The damage to the roller portion includes, for example, the occurrence of partial microcracks, the propagation of internal cracks, and some dropouts.

Further, in the step of heating the roller part, since the inner circumferential surface of the roller part is opened to the outside air, the inner circumferential surface of the roller part can be accessed in the heating step. Thereby, in the heating process, the amount of heat extension of the inner diameter of the roller part can be measured with a vernier caliper, a laser distance measuring instrument, or the like. Accordingly, heating can be performed while checking the amount of thermal expansion of the inner diameter of the roller portion, and thus the desired amount of thermal expansion can be reliably achieved. In addition, since the amount of heat extension is continuously checked, the heating process can be finished when the desired amount of heat extension is reached, so that unnecessary time due to excessive heating or the like is prevented and the heating process can be shortened.

In addition, in the manufacturing method of a crushing roller according to an aspect of the present invention, the hardened portion may include at least a part of a member having a coefficient of thermal expansion smaller than that of the base.

In the above configuration, at least a portion of the hardened portion includes a member having a lower coefficient of thermal expansion than the base, for example, ceramics. When the hardened part expands radially outward, compressive stress in the radial direction is generated by the pressing force acting on the hardened part. Therefore, even if a member with a smaller amount of thermal expansion than the base is present, the compressive stress generated in the hardened part causes It is possible to make it difficult for cracks to propagate in a member having a small coefficient of thermal expansion, such as ceramics. Therefore, it can be made difficult to damage the hardened part.

In addition, the manufacturing method of the crushing roller according to an aspect of the present invention, in the heating step, while forming a lower space between the roller portion and the bottom surface, the inner side of the lower space and the inner peripheral surface of the roller portion You may heat the said roller part in the state which the inner space formed in to communicate with.

In the above configuration, the lower space and the inner space formed between the roller portion and the bottom surface are in communication. As a result, since air is introduced from the lower side of the inner space through the lower space, the chimney effect can be more effectively operated, and ascending airflow can be reliably generated in the inner space. Therefore, more suitably, it is possible to suppress the temperature distribution on the inner circumferential surface of the roller and suppress the occurrence of uneven stress in the entire roller portion.

In addition, in the heating step, in the manufacturing method of a crushing roller according to an aspect of the present invention, in the heating step, the outer peripheral surface in the radial direction of the roller portion is covered with a heater, and the outer peripheral surface in the radial direction of the heater is covered with a heat insulating material, You may heat the roller part by raising the temperature of the said heater.

In the above configuration, since the outer circumferential surface of the heater is covered with a heat insulating material, heat dissipation from the heater can be reduced, and the heat flux from the heater to the roller portion can be stabilized. Accordingly, distribution of the amount of heat transferred from the heater to the outer peripheral surface of the roller part can be suppressed and uniformized.

Further, since the inner circumferential surface of the roller portion is open to the atmosphere (that is, the low temperature side), the heat received from the outer circumferential side is likely to move toward the inner circumferential side. In this way, since the direction of the heat flux toward the inner circumferential side can be determined, the temperature increase on the inner circumferential side of the roller unit can be stabilized.

Further, in the manufacturing method of a crushing roller according to an aspect of the present invention, in the heating step, the roller portion may be heated while heating the heater from a room temperature state to a predetermined temperature increasing rate.

It takes a predetermined time for the heat inputted from the outer peripheral surface to be transferred to the inner peripheral surface. For this reason, when the roller part is heated from the outer circumferential surface with a heater, a temperature difference occurs between the outer circumferential surface and the inner circumferential surface. In the above configuration, the roller portion is heated while heating the heater at a predetermined temperature increasing rate from the room temperature state. Thereby, the outer peripheral surface and the inner peripheral surface of the roller part are also heated so as to follow the temperature increase of the heater. Therefore, compared with a method of heating while maintaining a constant temperature of the outer peripheral surface of the roller with a heater maintaining a constant temperature, the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller becomes smaller. Therefore, it is possible to reduce the stress generated in the hardened portion provided on the outer peripheral surface side of the roller portion. Therefore, it can be made difficult to damage the roller part.

Moreover, in the manufacturing method of the grinding roller which concerns on one aspect of this invention, the said predetermined temperature rising rate may be 1 degreeC/min or more, and 2 degrees C/min or less may be sufficient.

By slowing down the heating rate of the heater, the temperature difference between the inner and outer circumferential surfaces of the roller part can be sufficiently reduced, making it difficult to damage the roller part, but it takes time to obtain the amount of heat extension required to shrink and fit the roller part and the support part. For this reason, the heating process is prolonged for a long time and workability is deteriorated. On the other hand, if the heating rate of the heater is increased, the heating process can be shortened, but the temperature difference between the inner and outer circumferential surfaces of the roller cannot be sufficiently reduced, thereby increasing the possibility of damage to the roller.

In the above configuration, the heater is heated at a rate of 1°C/min or more and 2°C/min or less. In this way, by setting the temperature rise rate to 2°C/min or less, the temperature difference between the inner and outer circumferential surfaces of the roller portion can be sufficiently reduced, making it difficult to damage the roller portion, and heating by setting the temperature rising rate to 1°C/min or more It is possible to improve workability by preventing excessive lengthening of the process.

Moreover, in the manufacturing method of the crushing roller according to an aspect of the present invention, in the heating step, a metal foil may be provided between the roller portion and the heater.

In the above configuration, a metal foil is provided between the roller portion and the heater. Since the metal foil is easily deformed and has high thermal conductivity, the metal foil provided between the roller portion and the heater is deformed into a shape according to the gap between the roller portion and the heater, and is in close contact with the roller portion and the heater, and contact heat. Reduce resistance. In this way, by providing the metal foil between the roller portion and the heater, the gap formed between the roller portion and the heater can be filled with the metal foil.

Since the metal foil has good thermal conductivity, the thermal conductivity between the roller portion and the heater is improved by filling the gap formed between the roller portion and the heater with the metal foil. Thereby, the heat flux from the heater to the roller part can be increased. Accordingly, since the heat of the heater is easily transferred to the inner peripheral surface of the roller portion, the temperature increase in the inner peripheral surface is suitably performed. Therefore, it is possible to suppress the temperature distribution on the inner circumferential surface of the roller portion, and to suppress the occurrence of uneven stress in the entire roller portion. Therefore, it can be made difficult to damage the roller part.

Moreover, as a metal foil, an aluminum foil is mentioned, for example.

In addition, in the manufacturing method of the crushing roller according to an aspect of the present invention, the heating step is a first heating of heating the roller portion by heating the heater at a first heating rate until a predetermined time elapses from the start of heating. A step and a second heating step of heating the roller portion by heating the heater at a second heating rate faster than the first heating rate after the first heating step may be provided.

In the above configuration, heating of the roller portion is performed by heating the heater at the first temperature increasing rate from the start of heating to the elapse of a predetermined time. Thereby, it is possible to suppress an increase in the temperature difference between the outer circumferential surface and the inner circumferential surface of the roller unit, which occurs due to a rapid increase in temperature on the outer circumferential surface of the roller unit with the start of heating. Therefore, it is possible to reduce the stress generated in the hardened portion provided on the outer peripheral surface side of the roller portion. Therefore, it can be made difficult to damage the roller part.

In addition, in the manufacturing method of a crushing roller according to an aspect of the present invention, a plurality of the heaters are provided, and the plurality of heaters are arranged side by side in the circumferential direction so as to follow the outer peripheral surface of the roller part, respectively, The temperature increase rate may be controlled by another temperature increase rate control unit.

In the above configuration, a plurality of heaters covering the outer circumferential surface of the roller portion are arranged side by side, and the heating rate is controlled by different heating rate control units. Thereby, by appropriately controlling the heating rate of each heater individually, even if it is a large-sized roller part, it is possible to suppress the occurrence of temperature distribution on the outer peripheral surface of the roller part. By suppressing the occurrence of the temperature distribution on the outer circumferential surface, the heat input from the outer circumferential surface can be equalized, so that the temperature distribution on the inner circumferential surface of the roller portion can be suppressed.

Further, since a plurality of heaters covering the outer peripheral surface of the roller portion are arranged side by side, each heater is miniaturized. Thereby, since the temperature distribution in each heater can be reduced, the occurrence of the temperature distribution on the outer peripheral surface of the roller portion can be suppressed.

In addition, in the manufacturing method of the crushing roller according to one aspect of the present invention, in the heating step, a temperature increase rate storage step of storing a temperature increase rate of the heater, and a heat extension amount of the roller portion in the heating step are stored. A table creation step for creating a table in which the relationship between the temperature increase rate and the amount of heat extension is determined based on the heat extension amount memory step, the temperature increase rate memorized in the temperature increase rate memory step, and the heat extension amount memorized in the heat growth amount memory step. And, in the heating step, preheating is performed on the roller unit at a temporary heating rate, and determined based on the temporary heating rate and the amount of heat extension of the roller unit in the preliminary heating. You may heat the said roller part by a heating rate.

In the above configuration, by pre-heating in which the roller part is heated at a temporary heating rate at the site where the crusher is located, the appropriate heating rate of the roller part is determined and the heating can be performed within the range of the appropriate heating condition of the roller part. have.

In addition, the determined heating rate can be made under the condition that the temperature difference due to the rapid temperature gradient between the inner surface of the roller and the outer surface of the roller does not increase, so that the occurrence of stress in the hardened portion provided on the outer peripheral surface of the roller portion can be suppressed and partial damage can be suppressed. So, it is suitable.

A temperature raising device according to an aspect of the present invention is used in a crusher for pulverizing an object to be pulverized, and is provided on an annular base and an outer peripheral surface of the base in a radial direction, and has an annular-shaped base having a different thermal expansion coefficient than the base. A temperature increasing device for increasing a temperature of a roller unit, comprising: a heater provided to cover an outer circumferential surface of the roller unit in a radial direction; and a temperature increase rate control unit for controlling a temperature increase rate of the heater, wherein the temperature increase rate control unit is 1°C/min or more. In addition, the heater is controlled so that the heating rate is 2°C/min or less.

In addition, in the heating apparatus according to an aspect of the present invention, the heater is disposed in a state in which the central axis is in a direction orthogonal to the floor surface, and the inner peripheral surface in the radial direction of the roller part is open to outside air. It may be provided with respect to the formed roller portion.

By slowing down the heating rate of the heater, the temperature difference between the inner and outer circumferential surfaces of the roller part can be sufficiently reduced, making it difficult to damage the roller part, but it takes time to obtain the amount of heat extension required to shrink and fit the roller part and the support part. Therefore, the heating process becomes prolonged. On the other hand, if the heating rate of the heater is increased, the heating process can be shortened, but the temperature difference between the inner and outer circumferential surfaces of the roller cannot be sufficiently reduced, thereby increasing the possibility of damage to the roller.

In the above configuration, the heater is heated at a rate of 1°C/min or more and 2°C/min or less. In this way, by setting the temperature rise rate to 2°C/min or less, the temperature difference between the inner and outer circumferential surfaces of the roller portion can be sufficiently reduced, making it difficult to damage the roller portion, and heating by setting the temperature rising rate to 1°C/min or more Workability can be improved by suppressing excessive lengthening of the process.

Further, in the temperature raising device according to an aspect of the present invention, a plurality of heaters are provided, and a plurality of the temperature increase rate control units are provided, and the plurality of heaters are circumferentially along the outer peripheral surface of the radial direction of the roller part. The temperature increase rate may be controlled by the different temperature increase rate control units while being arranged side by side in the direction.

In the above configuration, a plurality of heaters covering the outer circumferential surface of the roller portion are arranged side by side, and the heating rate is controlled by different heating rate control units. Thereby, by individually appropriately controlling the heating rate of each heater, it is possible to suppress the occurrence of temperature distribution on the outer circumferential surface of the roller portion even if the roller portion becomes large. By suppressing the occurrence of the temperature distribution on the outer circumferential surface, the heat input from the outer circumferential surface can be equalized, so that the temperature distribution on the inner circumferential surface of the roller portion can be suppressed.

Further, since a plurality of heaters covering the outer peripheral surface of the roller portion are arranged side by side, each heater is miniaturized. Thereby, since the temperature distribution in each heater can be reduced, the occurrence of the temperature distribution on the outer peripheral surface of the roller portion can be suppressed.

According to the present invention, it is possible to make it difficult to damage the hardened part by making it difficult for cracks to propagate to the hardened part during shrink fit.

1 is a longitudinal sectional view showing a schematic configuration of a solid fuel pulverizing apparatus to which a crushing roller manufactured according to a method of manufacturing a crushing roller according to an embodiment of the present invention is applied.
2 is a perspective view of the crushing roller of FIG. 1.
3 is a longitudinal sectional view of the grinding roller of FIG. 1.
4 is a schematic longitudinal cross-sectional view of a crushing roller for explaining a heating step in the method for manufacturing a crushing roller according to the present embodiment.
5 is a schematic diagram schematically showing a temperature increasing device according to the present embodiment.
FIG. 6 is a graph showing changes with elapsed time of a temperature of a heater, a temperature of an inner surface of a roller, and a temperature difference between an inner surface of a roller and an outer surface of a roller part.
FIG. 7 is a graph showing the change of the temperature of the heater, the temperature of the inner surface of the roller, the temperature difference between the inner surface of the roller and the outer surface of the roller, and the elapsed time of the heat extension amount of the inner diameter when the heater is heated at a heating rate of 10°C/30 minutes.
FIG. 8 is a graph showing the change of the temperature of the heater, the temperature of the inner surface of the roller, the temperature difference between the inner surface of the roller and the outer surface of the roller, and the elapsed time of the heat extension amount of the inner diameter when the heater is heated at a heating rate of 50°C/30 minutes.
FIG. 9 is a graph showing the change of the temperature of the heater, the temperature of the inner surface of the roller, the temperature difference between the inner surface of the roller and the outer surface of the roller, and the elapsed time of the heat extension amount of the inner diameter when the heater is heated at a heating rate of 90°C/30 minutes.
10 is a graph showing the relationship between the heating rate of the heater and the time to reach the required amount of heat extension, and the relationship between the heating rate of the heater and the inner surface temperature of the roller.
11 is a graph showing a relationship between a heater temperature or a roller inner surface temperature.
12 is a graph showing the relationship between the elapsed time and the temperature difference between the heater temperature or the outer surface temperature of the roller and the inner surface temperature of the roller.
13 is a graph showing a change with elapsed time of a temperature of a heater, a temperature of an inner surface of a roller, and a temperature difference between an inner surface of the roller and an outer surface of the roller.

Hereinafter, an embodiment of a method for manufacturing a crushing roller and a temperature increasing device according to the present invention will be described with reference to the drawings.

The crushing roller 5 manufactured by the method of manufacturing the crushing roller according to the present embodiment can be used, for example, as the crushing roller 5 applied to the pulverizing machine 1 described below.

In addition, in this embodiment, the upper direction represents the direction of the vertical upper side, and the "upper", such as an upper part or the upper surface, represents a part of the vertical upper side. Likewise, "bottom" represents the vertical lower part. In addition, the outer circumferential surface and the inner circumferential surface represent the outer circumference and the inner circumference in the radial direction from the central axis of the annular roller part 24.

As shown in FIG. 1, the crusher 1 communicates with the cylindrical hollow housing 2 forming the outer shell and the lower side of the housing 2 to transfer gas for conveyance inside the housing 2. It is provided with an air supply duct 3 to supply. Inside the housing 2, a grinding table 4 is rotatably supported with respect to the housing 2 about a rotation axis along a vertical vertical direction, and an object to be pulverized on the grinding table 4 (in this embodiment, , As an example, a crushing roller 5 for pulverizing solid fuel such as coal) is accommodated.

The housing 2 has a cylindrical shape, and a cylindrical fuel supply pipe 7 is provided in the upper center so as to penetrate the ceiling surface portion 2b. The fuel supply pipe 7 supplies solid fuel such as coal into the housing 2 from a solid fuel supply device (not shown), and extends in a vertical vertical direction at the center position of the housing 2. Further, a rotary separator 8 is provided that rotates around the fuel supply pipe 7 in the housing 2 and exists in a direction orthogonal to the longitudinal direction of the fuel supply pipe 7. The rotary separator 8 classifies pulverized solid fuel (hereinafter, pulverized solid fuel is referred to as "pulverized fuel") based on a predetermined particle size. The ceiling surface portion 2b of the housing 2 is provided with an outlet port 9, which is an outlet port for conveying the finely divided fuel having a predetermined particle diameter or less classified by the rotary separator 8 to a wake device.

The grinding table 4 includes a rotation support 15 rotatably supported at an approximate center of the bottom 2c of the housing 2, and a substantially circular plate-shaped table portion fixed to an upper end of the rotation support 15 ( 16). The rotation support part 15 is rotationally driven by a drive device (not shown). The table portion 16 is disposed to face the lower end portion on the vertical lower side of the fuel supply pipe 7 and rotates together with the rotation support portion 15. In addition, the upper surface of the grinding table 4 extends in a horizontal direction, the central portion has an inclined shape in which the height increases in a vertical upward direction than the outer side, and the height decreases from the central portion toward the outer side, and the outer peripheral portion is curved upward again. .

The air supply duct 3 is provided so as to extend substantially parallel to the horizontal plane, and communicates with the side surface portion 2a of the housing 2. The air supply duct 3 supplies a conveying gas supplied from an air supply device (not shown) into the housing 2. The conveying gas supplied from the air supply duct 3 is sandwiched between the pulverizing table 4 and the pulverizing roller 5 on the pulverizing table 4, thereby allowing the pulverized fuel to flow through the rotary separator 8 Return.

A plurality of crushing rollers 5 (three as an example in this embodiment) are disposed vertically above the outer peripheral portion of the table portion 16 so as to face the table portion 16. In addition, in FIG. 1, only one of the plurality of crushing rollers 5 is shown in the relationship of illustration. The plurality of crushing rollers 5 are arranged side by side at equal intervals in the circumferential direction. For example, with an angular interval of 120° on the outer circumference, three crushing rollers 5 are evenly spaced in the circumferential direction. Detailed description of the crushing roller 5 will be described later.

Each crushing roller 5 is fixed to the housing 2 via a journal shaft 17, a journal head 18, and an eccentric shaft 19 (see Figs. 2 and 3). The journal shaft 17 extends inclined vertically downward from the side surface 2a of the housing 2 to the center side, and the crushing roller 5 is rotatably supported by a bearing (not shown) at the tip end. That is, the crushing roller 5 is rotatably supported in an inclined state positioned vertically above the crushing table 4 so that the upper side faces the center side of the housing 2 rather than the lower side.

The journal head 18 is supported by an eccentric shaft 19 along the horizontal direction in the middle portion so as to be able to swing in the vertical vertical direction by the side surface portion 2a of the housing 2. Further, the journal head 18 supports the base end of the journal shaft 17 on which the grinding roller 5 is rotatably attached to the distal end. That is, the crushing roller 5 can be separated from the upper surface of the crushing table 4 by swinging the journal head 18 in a vertical vertical direction with the eccentric shaft 19 as a point. Supported.

A pressing device 20 is provided at the upper end of the journal head 18 on the vertical upper side, and a stopper 21 is provided at the lower end of the journal head 18. The pressing device 20 is fixed to the housing 2 and applies a downward load for pulverizing the solid fuel supplied on the crushing table 4 to the crushing roller 5 through a journal head 18 or the like. . The stopper 21 is fixed to the housing 2 and regulates the amount that the pulverizing roller 5 can rotate vertically downward, so that the gap between the crushing roller 5 and the crushing table 4 is adjusted. Adjust.

Next, details of the crushing roller 5 will be described with reference to FIGS. 2 and 3.

The crushing roller 5 includes a journal housing (supporting portion) 23 rotatably supported at the tip end of the journal shaft 17, and an annular roller portion 24 fitted outside the journal housing 23. Are doing. The journal housing 23 is provided so as to cover the tip end of the journal shaft 17 and has an outer peripheral surface formed in a cylindrical shape.

In this embodiment, as shown in FIG. 3, the roller part 24 is a base 25 made of high chromium cast iron fitted to the journal housing 23, and a ceramic member provided on the outer peripheral surface of the base 25 It is provided with the hardened|cured part 26 containing in part. That is, the roller part 24 according to the present embodiment is a so-called ceramic-embedded high chromium cast iron roller. The base 25 is formed in a substantially annular shape. Further, the base 25 is fitted with the journal housing 23 so that the inner peripheral surface contacts the outer peripheral surface of the journal housing 23. The hardened portion 26 is fixed so as to be embedded over substantially the entire circumferential direction of the outer peripheral surface of the annular base 25. Further, since the hardened portion 26 is made of ceramic, the thermal expansion coefficient is smaller than that of the base 25 made of high chromium cast iron.

In addition, the outer diameter L1 of the roller part 24 is, for example, about 1m to about 2m in this embodiment, and the length L2 of the roller part 24 in the direction of the central axis is, for example, about 0.3m to about It is 0.7 m, and the length L3 of the roller part 24 in the radial direction is about 0.1 m to about 0.3 m, for example. That is, the inner diameter L4 of the roller part 24 is about 0.5 m to about 1.8 m (see Fig. 4).

Next, a method of fitting the journal housing 23 and the roller portion 24 in the method of manufacturing the crushing roller 5 will be described.

In this embodiment, the inner diameter of the inner circumferential surface of the roller part 24 is increased by thermal expansion by heating the roller part 24 from the outer peripheral surface side in the radial direction (heating step), and the roller part 24 in a state in which the inner diameter is increased by heating. ), the journal housing 23 is positioned within the space (hereinafter referred to as "inner space") formed on the inner circumferential surface of the (laying process), and then the roller part 24 is cooled to the inner diameter of the roller part 24 By making it small, the journal housing 23 and the roller part 24 are fitted (fitting process). That is, the journal housing 23 and the roller part 24 are fitted by so-called shrink fitting. In addition, in the arrangement process, the inner circumferential surface of the roller part 24 is arranged so as to face or contact the outer circumferential surface of the journal housing 23.

The heating process will be described in detail.

In the heating process, first, as shown in FIG. 4, the roller part 24 is arrange|positioned so that the central axis line C1 may become the direction orthogonal to a floor surface on the base on the floor surface formed of the heat insulating brick 27. In other words, the roller part 24 is arrange|positioned so that a circular surface may be horizontal with respect to a shelf surface. The base is 50mm to 200mm in height, and is provided so that a lower space may be formed between the roller part 24 and the ground. The insulating bricks 27 forming the foundation are arranged so that the lower space and the inner space of the roller part 24 communicate with each other. The arrow in FIG. 4 shows a situation in which the air in the inner space is heated by a temperature difference with the inner circumferential surface of the roller unit 24 to increase its temperature, and becomes a rising airflow due to the chimney effect and is discharged to the atmosphere.

The outer circumferential surface of the roller part 24 is substantially covered with a plurality of heaters 31 provided along the outer circumferential surface. When installing the heater 31 on the outer circumferential surface of the roller part 24, it is preferable that the heater 31 is in close contact with the outer circumferential surface of the roller part 24 as uniformly as possible. 24) is fixed to the outer circumferential surface of the outer circumferential surface by tightly binding a plurality of points in the vertical direction of the outer circumferential surface with wires or the like. The outer circumferential surface of the heater 31 is substantially entirely covered by the heat insulating material 29 provided along the outer circumferential surface.

The inner circumferential surface of the roller part 24 is not covered with the heater 31, the heat insulating material 29, etc., but is in a state open to the outside air (that is, a state opened to the atmosphere).

In the heating step, heating is performed by raising the temperature of the heater 31 at a predetermined temperature increasing rate from the room temperature state to the thus arranged room temperature roller portion 24.

Next, the temperature raising device 30 for heating the roller part 24 in the heating step will be described with reference to FIG. 5.

As shown in FIG. 5, the temperature raising device 30 includes a plurality of heaters 31 (three as an example in this embodiment) arranged side by side in the circumferential direction so as to follow the outer peripheral surface of the roller part 24, and each A plurality of (three as an example in this embodiment) power supply control unit (heating speed control unit) 32 that controls the amount of power supplied to the heater 31, and a power supply unit 33 that supplies electricity to each power supply control unit 32 Wow, a temperature measuring device 34 for measuring the temperature of the outer peripheral surface of the roller part 24 is provided.

Each heater 31 is a flexible planar heater 31 that can be in close contact with the outer circumferential surface of the roller part 24, such as an egg mat heater or a ribbon heater, for example. Each of the heaters 31 is disposed so as to cover a region where the outer peripheral surface of the roller portion 24 is divided into three equal parts in the circumferential direction. That is, the substantially entire outer circumferential surface of the roller part 24 is covered by the three heaters 31 of substantially the same type.

The temperature measuring device 34 is provided one at a time in the region where each heater 31 is provided among the outer circumferential surfaces of the roller part 24, and measures the temperature of the outer circumferential surface of the roller part 24 in the provided region. The temperature measuring device 34 transmits the measured temperature to the power supply control unit 32. The temperature measuring device 34 may be any one capable of measuring the temperature, and examples thereof include a thermocouple.

As described above, three power supply control units 32 are provided, and the three power supply control units 32 control the heating rate of the heater 31 by controlling the amount of power supplied to the different heaters 31, respectively. That is, the three power supply control units 32 and the three heaters 31 have a one-to-one correspondence. In addition, each power supply control unit 32 may adjust the amount of power supplied to each heater 31 so that the temperature measured by each temperature measurement device 34 becomes approximately the same based on the temperature measured by the temperature measurement device 34. do.

The power supply control unit 32 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a computer-readable storage medium, and the like. In addition, a series of processes for realizing various functions are stored in a storage medium or the like in the form of a program as an example, and the CPU reads this program into RAM or the like, and executes information processing/calculation processing, whereby various functions are performed. Come true. In addition, the program may be pre-installed in a ROM or other storage medium, provided in a form stored in a computer-readable storage medium, or transmitted through a communication means by wire or wireless. . Computer-readable storage media are magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

In addition, the number of the heater 31, the power supply control part 32, and the temperature measuring device 34 is not limited to the said example. A single number may be sufficient, and plural numbers other than three may be sufficient.

Next, the heating method of the roller part 24 performed by the temperature raising device 30 in a heating process is demonstrated.

In the heating step according to the present embodiment, the roller portion 24 is heated while heating the heater 31 of the temperature increasing device 30 at a predetermined temperature increasing rate. Specifically, the roller portion 24 is heated by heating the heater 31 at a heating rate of 1°C/min or more and 2°C/min or less. As described above, in the present embodiment, by heating the roller part 24 while heating the heater 31 at a predetermined temperature increasing rate, the temperature of the outer circumferential surface and the inner circumferential surface of the roller part 24 is increased due to the increase in the temperature of the heater 31. Is following.

On the other hand, as a method of heating the roller part 24 using the heater 31, a method of heating the roller part 24 with the heater 31 maintained at a constant temperature can also be considered. However, when the roller part 24 is heated with the heater 31 maintained at a constant temperature, the temperature of the outer circumferential surface of the roller part 24 is slightly lower than the temperature of the heater 31 and maintains an approximately constant temperature. It was found that the temperature difference between the inner circumferential surface and the outer circumferential surface of the portion 24 increases, and there is a possibility that damage or the like may occur in the roller portion 24. In addition, as a method of heating the roller unit 24 while heating the heater 31 at a predetermined temperature increasing rate, a method of heating the roller unit 24 with a heater 31 maintained at a constant temperature, It was found that the temperature difference between the inner circumferential surface and the outer circumferential surface of 24) can be reduced, so that the stress generated in the hardened portion 26 provided on the outer circumferential surface of the roller portion 24 can be reduced.

The decrease in the temperature difference between the inner and outer circumferential surfaces of the roller part 24 will be described in detail using the graph of FIG. 6. 6 shows the temperature of the heater 31, the temperature of the inner circumferential surface of the roller part 24 (hereinafter, also referred to as “roller inner surface”), and the inner surface of the roller and the outer circumferential surface of the roller part 24 (hereinafter also referred to as “roller outer surface”). ) Is a graph showing the change according to the elapsed time of the temperature difference, the horizontal axis represents the elapsed time (minutes), and the vertical axis represents the temperature difference ΔT (°C) or temperature (°C).

Further, a solid line 61 in FIG. 6 indicates the temperature of the heater 31 when the temperature of the heater 31 is kept constant at 200°C. Further, the solid line 62 represents the roller inner surface temperature when the temperature of the heater 31 is kept constant at 200°C, and the solid line 63 represents the temperature difference between the inner surface of the roller and the outer surface of the roller in this case. In addition, the broken line 64 in FIG. 6 shows the temperature of the heater 31 when the temperature of the heater 31 is raised at a heating rate of 50° C./30 minutes. In addition, the broken line 65 represents the inner surface temperature of the roller when the temperature of the heater 31 is raised at a heating rate of 50°C/30 minutes, and the broken line 66 represents the temperature difference between the inner surface of the roller and the outer surface of the roller in this case. .

In addition, the roller inner surface temperature T of FIG. 6 is computed by following formula (1).

(T-Ta)/(To-Ta)=Exp(-hA/(CM)×τ)...(1)

However, T: abnormal temperature inside the roller

To: Initial temperature of the inner surface of the roller (for example, this time at room temperature, 25℃)

Ta: heating side temperature (that is, this time the heater 31 temperature)

C: Specific heat of the roller (for example, 0.5~0.6kJ/kg℃)

h: Thermal conductivity inside the roller from the heater 31 (for example, 1 to 50 W/m ² K)

τ: time

M: mass of roller

A: roller area

ρ: density of the roller

t: heat conduction distance of roller

Here, since M=Aρt, the above formula (1) becomes the following formula (2).

(T-Ta)/(To-Ta)=Exp(-h/(Cρt)×τ)...(2)

Comparing the solid line 63 shown in FIG. 6 with the broken line 66, compared to the case in which the roller unit 24 is heated by maintaining a constant temperature of the heater 31 at all times, the roller unit is heated while raising the heater 31 In the case of heating (24), it can be seen that the temperature difference between the heater heating surface (that is, the outer surface of the roller) and the inner surface of the roller is smaller. For example, when the elapsed time is from 20 minutes to 40 minutes, the temperature difference between the heater heating surface (that is, the outer surface of the roller) and the inner surface of the roller is obtained by heating the roller part 24 by keeping the temperature of the heater 31 constant. Compared with the case, it can be seen from FIG. 6 that when the roller part 24 is heated while the heater 31 is heated, it can be suppressed to about 1/3 or less.

Next, a method of setting the heating rate of the heater 31 will be described.

In this embodiment, the roller part 24 is heated by raising the temperature of the heater 31 at a rate of 1°C/min or more and 2°C/min or less. This temperature increase rate is determined by appropriately selecting the temperature increase rate of the heater 31 from the result of the heating test of the roller unit 24, so that the temperature of the inner peripheral surface of the roller unit 24 is relatively low (for example, about 30°C to 50°C). ) Also is set based on finding that there is a heating condition of the roller in which the amount of heat extension of the inner diameter of the roller part 24 capable of shrink fitting is found. Below, the heating test of the roller part 24 is demonstrated using FIGS. 7-9.

In addition, in the present embodiment, in the contraction fitting between the roller portion 24 and the journal housing 23, the size of the roller portion 24 of the present embodiment is the inner diameter L4, for example, It is about 0.5 m to about 1.8 m, and the amount of required heat extension in the radial direction of the inner diameter of the roller part 24 is set to about 0.2 mm, for example.

7 to 9 are graphs showing measured values of changes with elapsed time of the temperature of the heater 31, the temperature of the inner surface of the roller, the temperature difference between the inner surface of the roller and the outer surface of the roller, and the amount of heat extension of the inner diameter, respectively, and the horizontal axis elapses. Represents time (minutes), and the vertical axis represents the heat extension amount (mm) and temperature difference or temperature (°C) of the inner diameter. In addition, the halftone portion represents the elapsed time period when the required heat extension amount reaches 0.2 mm. Each temperature and elapsed time illustrate the influence of the heater 31 on the heating rate, and illustrate an example of the present embodiment.

7 shows a case where the heater 31 is heated at a heating rate of 10°C/30 minutes, solid line 71 is the heater temperature, solid line 72 is the roller inner surface temperature, solid line 73 is the temperature difference between the inner surface of the roller and the outer surface of the roller, solid line 74 represents the measured value of the amount of heat extension of the inner diameter of the roller.

As shown in Fig. 7, when the heating rate of the heater 31 is relatively slow, in order to obtain the required amount of heat extension, it is necessary to heat the inner surface temperature of the roller from 40°C to about 45°C, and the time is also 115 minutes to 120 minutes. I need it. On the other hand, the temperature difference between the outer surface of the roller and the inner surface of the roller is as small as about 20°C to 25°C, and the entire roller part 24 can be heated relatively uniformly.

Fig. 8 shows a case where the heater 31 is heated at a heating rate of 50°C/30 minutes, broken line 81 is the heater temperature, broken line 82 is the roller inner surface temperature, broken line 83 is the temperature difference between the inner surface of the roller and the outer surface of the roller, broken line 84 represents the measured value of the heat extension amount of the inner diameter of the roller.

As shown in Fig. 8, when the heating rate of the heater 31 is relatively high, the inner surface temperature of the roller does not increase in temperature at the beginning of the heating, and the temperature increases after about 20 minutes (see broken line 82). This is because, as the heating proceeds, the outer peripheral surface of the roller portion 24 thermally expands, and the state of thermal contact between the heater 31 and the outer peripheral surface of the roller portion 24 improved.

The amount of heat extension of the inner diameter of the roller part 24 increases in proportion to the passage of time, including the time when the required amount of heat extension (0.2 mm) after about 30 to about 35 minutes has elapsed. On the other hand, as described above, the inner surface temperature of the roller hardly increases in temperature for about 20 minutes from the beginning of heating. Thereby, when the required amount of heat extension is reached, the roller inner surface temperature is about 30°C to 35°C. In this way, despite the relatively low temperature of the inner surface of the roller, the reason why the required amount of thermal expansion is reached is due to the fact that the inner surface of the roller is subjected to tensile stress due to thermal expansion (heat expansion) of the outer surface of the roller.

In this way, when the heater 31 is heated at a temperature increase rate of 50° C./30 minutes, the required heat extension amount is obtained while the inner surface temperature of the roller is relatively low. From this point of view, as described above, it can be seen that the inner surface of the roller is starting to generate a tensile force due to thermal expansion of the outer surface of the roller.

In addition, the temperature difference between the inner surface of the roller and the outer surface of the roller is about 50°C to 55°C when the required heat extension amount (0.2 mm) is reached. As a result, it is considered that the compressive stress to the hardened portion 26 provided on the outer peripheral surface of the roller is starting to increase.

9 shows a case in which the heater 31 is heated at a temperature increase rate of 90°C/30 minutes, dashed-dotted line 91 is the heater temperature, dashed-dotted line 92 is the inner surface temperature of the roller, and dashed-dotted line 93 is the relationship between the inner surface of the roller and the outer surface of the roller. The difference in temperature and the dashed-dotted line 94 indicate the measured value of the amount of heat extension of the inner diameter of the roller.

As shown in Fig. 9, when the temperature increase rate of the heater 31 is faster than the example in Fig. 8, the inner surface temperature of the roller does not increase in temperature at the beginning of heating, and the temperature rises rapidly after about 20 minutes. There is (refer to the dashed-dotted line 92), and since the required heat extension amount (0.2 mm) is reached at this time, control of the heating time is substantially difficult. The reason for the sudden increase in temperature is, as in the example of FIG. 8, as the heating proceeds, the outer circumferential surface of the roller part 24 thermally expands, and the state of thermal contact between the heater 31 and the outer circumferential surface of the roller part 24 This is because is improved. In addition, the amount of heat extension of the inner diameter of the roller part 24 reaches the required amount of heat extension (0.2 mm) after about 15 to about 20 minutes, and the inner surface temperature of the roller at this time changes substantially from the beginning of heating. There is no 25℃ to 30℃.

In this way, despite the fact that the inner surface temperature of the roller is almost unchanged, the reason that the required amount of heat extension is reached is due to the fact that the inner surface of the roller is strongly subjected to tensile stress due to thermal expansion (heat extension) of the outer surface of the roller. Therefore, with respect to the roller part 24 (particularly, the base 25), the stress exceeding the crack limit radial stress σo (in this embodiment, about 40 N/mm ² is assumed as an internal crack) Occurrence of is feared, and there is a concern that micro cracks may occur in the roller portion 24 (especially on the outer peripheral side of the base 25).

Moreover, while the temperature rise of the inner surface of the roller is only about 1°C to 5°C, the temperature difference between the inner surface of the roller and the outer surface of the roller is about 50°C to 55°C. As a result, it is considered that the compressive stress to the hardened portion 26 provided on the outer peripheral surface of the roller is starting to increase further.

In this way, when the heater 31 is heated at a heating rate of 90° C./30 minutes, the stress to the hardened portion 26 and the stress to the roller 24 (especially, the outer peripheral side of the base 25) increase. Thereby, the risk of partial damage to the roller part 24 increases.

Further, more power to be supplied to the heater 31 is required than in other cases (examples shown in Figs. 7 and 8), and a large power supply and equipment are required. In this embodiment, in order to raise the temperature of the heater 31 at a heating rate of 90° C./30 minutes, a large power supply of, for example, 200 V and 40 A is required, and the roller shrinking and fitting work in the field where the crusher 1 is located. In order to do this, the power supply capacity of this degree is at the upper limit. For this reason, it is difficult to further increase the high-speed temperature.

As described above, from Figs. 7 to 9, it is understood that if the heating rate of the heater 31 is increased, the required amount of heat extension can be obtained in a short time, but the risk of damage to the roller unit 24 increases.

In more detail, the relationship between the heating rate of the heater 31 and the risk of damage (in particular, the state of occurrence of tensile stress generated on the inner side of the roller due to thermal expansion (heat extension) on the outer side of the roller) will be described.

As described above, in this embodiment, since the roller part 24 is heated only from the outer circumferential side, when the amount of heat extension (0.2 mm) required for shrink fitting is reached, the "roller outer surface temperature> roller inner surface temperature" is As a result, the inner surface of the roller is subjected to tensile stress due to thermal expansion (heat extension) of the outer surface of the roller.

Table 1 below shows the inner surface temperature of the roller, the heater temperature, the arrival time when the required amount of thermal expansion is reached, the amount of thermal expansion caused by the inner surface temperature of the roller, and the inner surface of the roller due to thermal expansion (thermal expansion). The state of occurrence of the tensile stress is shown for each heating rate of the heater 31. In addition, in this embodiment, as described above, the crack limit radial stress ?o is set to about 40 N/mm ² . In addition, as for the amount of heat extension due to the inner surface temperature of the roller, the Young's modulus E of the material of the base 25 of the roller part 24 is 1.8 to 2.0 × 10 ⁵ N/mm ² , and the linear expansion coefficient is 11 × 10 ^-6 to It is calculated as 12×10 ^-6 .

From Table 1, in the case where the heating rate is from 30°C/30 minutes to 90°C/30 minutes, the amount of heat expansion due to the inner surface temperature of the rollers when reaching 0.2 mm of the required amount of heat expansion is 0.2 mm or less. Has been. That is, the value obtained by subtracting the amount of heat extension due to the temperature of the inner surface of the roller from 0.2 mm is pulled by the thermal expansion (heat extension) of the outer surface of the roller, so that the length of the inner surface of the roller is elongated.

Therefore, in the case where the heating rate is between 30°C/30 minutes and 90°C/30 minutes, the inner surface of the roller is stretched due to thermal expansion (heat extension) of the outer surface of the roller, and the inner surface of the roller is subjected to tensile stress. It can be seen that as the speed increases, the inner surface of the roller is stretched, thereby increasing the elongated length. That is, it can be seen that the higher the temperature increase rate, the greater the tensile stress applied to the inner surface of the roller increases.

In addition, the state of occurrence of tensile stress generated on the inner surface of the roller at each heating rate is as follows. In the case where the heating rate was 30°C/30 minutes and 50°C/30 minutes, the tensile stress generated in both did not reach the crack limit radial stress ?o. Further, even when the temperature increase rate is 60°C/30 minutes, the resulting tensile stress does not reach the crack limit radial stress ?o, and a tensile stress of about 80% of the crack limit radial stress ?o is generated. In addition, when the temperature increase rate is 90°C/30 minutes, the resulting tensile stress is a value slightly smaller than the crack limit radial stress ?o.

Considering the above results, when the heating rate is 90°C/30 minutes, there is a concern that the tensile stress generated on the inner surface of the roller will exceed the crack limit radial stress σo, and the risk of damage to the roller part 24 It is thought that is increasing. Therefore, it can be seen that it is preferable to set the upper limit of the heating rate of the heater 31 to about 60°C/30 minutes (that is, 2°C/min).

Next, a method of setting the lower limit of the heating rate of the heater 31 will be described.

As can be seen from Table 1, when the rate of temperature rise is slow, the time to reach the required amount of heat extension (0.2 mm) becomes longer.

The grinding roller 5 may be replaced for purposes such as maintenance of the grinding roller 5. In order to install the replacement crushing roller 5, a temporary arrangement step of temporarily disposing the replacement roller part, a heating step of heating the roller part 24, and the roller part 24 and the journal housing 23 are fitted. A fitting step to perform and an installation step of installing the crushing roller 5 in which the roller portion 24 and the journal housing 23 are fitted to the pulverizer 1 are required.

The time required in each step is, for example, as follows in the present embodiment. In addition, the required time in the following description is only an example, and the required time may be a different time.

It takes about 5 minutes for the temporary placement process, about 10 minutes for the fitting process, and about 25 minutes for the installation process. That is, in other processes except for the heating process, about 40 minutes in total is required. Therefore, when the time for the heating step is Ht, the time required to replace one crushing roller 5 is Ht+40 (minutes).

Next, a suitable time for replacing one crushing roller 5 is set as follows.

As in the present embodiment, in the case of replacing two units (6 crushing rollers 5) of the pulverizer 1 provided with three crushing rollers 5 in one day, the working time of one day is reduced to 10 hours. If it is, the working time for one crushing roller 5 is obtained in 100 minutes from the following equation (3).

(10×60)min/3pcs×2 units...(3)

Therefore, it can be seen from the following equation (4) that the time Ht required for the heating step is preferably 60 minutes or less.

Ht+40min≤100min...(4)

Considering the above results, it can be seen from Table 1 that it is preferable to set the lower limit of the heating rate of the heater 31 to about 30°C/30 minutes (that is, 1°C/min).

As described above, in this embodiment, from the viewpoint of workability, the lower limit of the heating rate of the heater 31 is 1°C/min, and from the viewpoint of the risk of damage to the crushing roller 5, the heater 31 is The upper limit of the temperature increase rate is 2°C/min.

This will be described with reference to FIG. 10. In FIG. 10, the relationship between the heating rate (°C/min) of the heater 31 and the time (minutes) to reach the required heat extension amount (0.2 mm) is shown by a broken line, and the heating rate (°C/min) of the heater 31 and The relationship with the roller inner surface temperature (°C) is shown by a solid line.

As indicated by the broken line in Fig. 10, when the heating rate of the heater 31 is 2° C./min or more, the inner surface temperature of the roller at the time of reaching the required amount of heat extension decreases and the risk of damage increases, which is not suitable. In addition, when the rate of temperature increase of the heater 31 is 1°C/min or less, the time required for the heating step becomes 60 minutes or more, which deteriorates workability, which is not suitable. Accordingly, 1°C/min to 2°C/min, which is the range indicated by the arrow of the halftone dot portion of FIG. In particular, from the viewpoints of both the risk of damage and workability, a temperature increase rate of 50° C./30 minutes as indicated by P in FIG. 10 is suitable.

In addition, a temperature increase rate faster than 3°C/min is not appropriate because it becomes a necessary amount of heat extension before the inner surface temperature of the roller increases, and it is difficult to control the amount of heat extension.

According to this embodiment, the following effects are exhibited.

In the present embodiment, in the heating step, the roller portion 24 is heated from the outer peripheral surface side in the radial direction with the inner peripheral surface open to the outside air. For this reason, the outer circumferential surface side of the base 25 increases the temperature faster than the inner circumferential surface side, and becomes higher temperature than the inner circumferential surface side. Thereby, the base 25 thermally expands outward in the radial direction (that is, so that the outer shape becomes large). On the other hand, the hardened portion 26 has a different coefficient of thermal expansion than the base 25, and the hardened portion 26 may contain a member having a small coefficient of thermal expansion, for example, ceramics, so that the amount of thermal expansion is smaller than that of the base 25. The amount of thermal expansion increases when the temperature of the hardened portion or the hardened portion 26 becomes higher than that of the base portion 25. Accordingly, when the roller portion 24 thermally expands outward in the radial direction, a pressing force acts on the hardened portion 26 in the radial direction by being constrained by the base portion 25. For this reason, compressive stress in the radial direction is generated in the hardened portion 26. In this way, in the heating process of heating the roller part 24, since the stress generated in the hardened part 26 can be mainly used as compressive stress, the tensile stress generated in the hardened part 26 is suppressed and hardened. It is possible to make it difficult for cracks to propagate in the portion 26. Therefore, it is possible to make it difficult to damage the hardened portion 26.

In addition, the roller part 24 and the journal housing 23 can be fitted by contraction fitting in this way. For this reason, it is not necessary to perform gap fitting, and even if it is the crushing roller 5 having the hardened portion 26 on the outer circumferential surface, the roller portion 24 and the journal housing 23 are fixed in addition to dimensional control of the fitting portion. The crushing roller 5 can be manufactured by fitting the roller portion 24 and the journal housing 23 by shrink fitting without performing any special processing such as mounting of the member. Therefore, compared with the method of performing special processing on the roller part 24 and the journal housing 23, while reducing the cost, it is possible to shorten the time required for manufacturing.

In addition, it is installed in a state in which the central axis C1 of the roller part 24 is in a direction orthogonal to the floor surface, and the inner circumferential surface is opened to the outside air (in other words, the roller is open to the atmosphere) from the outer circumferential side. The part 24 is heating. Thereby, the air in the annular inner space is heated by heating, and by the chimney effect, as indicated by the arrow in Fig. 4, the air is released into the atmosphere as a rising airflow. Therefore, since the heated air does not stay in the inner space, the temperature distribution on the inner circumferential surface of the roller part 24 can be suppressed to be small, and the occurrence of uneven stress in the entire roller part 24 can be suppressed. Therefore, it is possible to make it difficult to damage the roller part 24. The damage to the roller part 24 includes, for example, generation of partial microcracks, propagation of internal cracks, and partial dropout.

In this embodiment, the lower space and the inner space formed between the roller part 24 and the bottom surface are in communication. As a result, since air is introduced from the lower side of the inner space through the lower space, the chimney effect can be more effectively operated, and ascending airflow can be reliably generated in the inner space. Therefore, more suitably, it is possible to suppress the temperature distribution on the inner circumferential surface of the roller, and suppress the occurrence of uneven stress in the entire roller portion 24.

Further, in the step of heating the roller part 24, since the inner circumferential surface of the roller part 24 is opened to the outside air, it is possible to access the inner circumferential surface of the roller part 24 in the heating step. Thereby, in the heating process, the amount of heat extension of the inner diameter of the roller part 24 can be measured with a nonius caliper, a laser distance measuring instrument, or the like. Therefore, heating can be performed while checking the amount of heat extension of the inner diameter of the roller part 24, so that the desired amount of heat extension can be reliably achieved. Accordingly, since the amount of heat extension is continuously checked, the heating process can be finished at the point when the desired amount of heat extension is reached, so that unnecessary time due to excessive heating or the like can be prevented and the heating process can be optimized. In addition, when obtaining the desired amount of heat extension of the inner diameter of the roller part 24, the heating process is performed with the elapsed heating time by confirming the relationship with the elapsed heating time when the heater 31 is set at a predetermined heating rate. You can manage it.

In this embodiment, since the outer peripheral surface of the roller part 24 in the radial direction is covered with the heater 31 and the outer peripheral surface of the heater 31 in the radial direction is covered with the heat insulator 29, heat from the heater 31 By reducing the acid work, the heat flux from the heater 31 to the roller part 24 can be stabilized. Accordingly, the distribution of the amount of heat transferred from the heater 31 to the outer peripheral surface of the roller part 24 can be suppressed and uniformized.

Further, since the inner circumferential surface of the roller part 24 is open to the atmosphere (ie, the low temperature side), heat inputted from the outer circumferential side is likely to move toward the inner circumferential side. In this way, since the direction of the heat flux toward the inner circumferential side can be determined, the temperature increase on the inner circumferential side of the roller part 24 can be stabilized.

It takes a predetermined time for the heat inputted from the outer peripheral surface to be transferred to the inner peripheral surface. For this reason, when the roller part 24 is heated by the heater 31 from the outer peripheral surface, a temperature difference arises between the outer peripheral surface and the inner peripheral surface. In this embodiment, the roller part 24 is heated while raising the temperature of the heater 31 at a predetermined temperature rising rate from a room temperature state. Thereby, the outer peripheral surface and the inner peripheral surface of the roller part 24 are also heated so as to follow the temperature increase of the heater 31. Therefore, compared to the method of heating while maintaining the temperature of the outer circumferential surface of the roller part 24 with the heater 31 maintaining a constant temperature, the temperature difference between the inner circumferential surface and the outer circumferential surface of the roller part 24 becomes smaller. . Accordingly, the stress generated in the hardened portion 26 provided on the outer peripheral surface side of the roller portion 24 can be reduced. Therefore, it is possible to make it difficult to damage the roller part 24.

By slowing the heating rate of the heater 31, the temperature difference between the inner and outer circumferential surfaces of the roller part 24 can be sufficiently reduced, making it difficult to damage the roller part 24, but the roller part 24 and the journal housing Since it takes time to obtain the amount of heat extension necessary for shrink-fitting (23), the heating process is prolonged and workability is deteriorated. On the other hand, if the heating rate of the heater 31 is increased, the heating process can be shortened, but the temperature difference between the inner and outer circumferential surfaces of the roller part 24 cannot be sufficiently reduced, and damage to the roller part 24 may occur. It becomes higher.

In this embodiment, the heater 31 is heated at a heating rate of 1°C/min or more and 2°C/min or less. In this way, by setting the temperature rise rate to 2°C/min or less, the temperature difference between the inner and outer circumferential surfaces of the roller part 24 can be sufficiently reduced, making it difficult to damage the roller part 24, and increasing the temperature rise rate by 1 By setting it as C/min or more, workability can be improved by preventing excessive prolongation of a heating process.

In the present embodiment, the plurality of heaters 31 covering the outer peripheral surface of the roller part 24 are arranged side by side, and the heating rate is controlled by the different power supply control units 32, respectively. Thereby, by individually appropriately controlling the heating rate of each heater 31, it is possible to suppress the occurrence of temperature distribution on the outer peripheral surface of the roller part 24. By suppressing the occurrence of the temperature distribution on the outer circumferential surface, heat input from the outer circumferential surface can be equalized, so that the temperature distribution on the inner circumferential surface of the roller part 24 can be suppressed.

In addition, since the plurality of heaters 31 covering the outer circumferential surface of the roller part 24 are arranged side by side so as to increase the heat generation density, each heater 31 is miniaturized. Thereby, since the temperature distribution in each heater 31 can be reduced, the occurrence of the temperature distribution on the outer peripheral surface of the roller part 24 can be suppressed.

[Modified Example 1]

Modification Example 1 of the present embodiment will be described.

In this modified example, it differs from the above embodiment in that the roller part 24 is heated with a metal foil provided between the outer circumferential surface of the roller part 24 and the heater 31. Further, the metal foil is easily deformed and preferably has good thermal conductivity, and, for example, an aluminum foil is suitable. Moreover, other than that, copper foil etc. may be sufficient.

It has been found that the heat flux from the heater 31 to the roller part 24 changes significantly in the thermal contact state of the heater 31 to the outer circumferential surface of the roller part 24, and the temperature increase state of the inner surface of the roller changes.

In the heating process, the heater 31 and the roller part 24 are at least not rattled against the outer circumferential surface of the roller part 24, and a plurality of vertical positions of the outer circumferential surface are tightly tied with wires, etc. It is fixed (hereinafter referred to as "usually fixed state"). The heater 31 is preferably provided so as to be in close contact with the outer circumferential surface of the roller part 24 as uniformly as possible, but in reality, it cannot be said that the thermal adhesion state is sufficiently high at the start of heating, and from the heater 31 It is estimated that the heat transfer rate to the roller part 24 may be about 1/2 to 1/10 compared to the case where the heater 31 is thermally completely in close contact.

That is, the heater 31 is in close contact with the outer surface of the roller, and the heat transfer rate is improved, for example, five times, so that the temperature of the inner surface of the roller rises approximately 20% faster, and the temperature difference between the outer surface of the roller and the inner surface of the roller is reduced by approximately 20%. do.

This can be determined from FIGS. 11 and 12.

11 shows the relationship between the elapsed time (minutes) and the heater temperature (°C) or the roller inner surface temperature (°C). In addition, the solid line 111 in FIG. 11 represents the heater temperature when the temperature is raised at a heating rate of 10°C/30 minutes, the broken line 112 represents the heater temperature when the temperature is raised at a heating rate of 50°C/30 minutes, and the solid line 113 is usually fixed. In the condition, the inner surface temperature of the roller when the temperature is raised at a heating rate of 10°C/30 minutes is indicated, and the broken line 114 indicates the inner surface temperature of the roller when the temperature is raised at a heating rate of 50°C/30 minutes in a normal fixed state. Reference numeral 115 denotes the inner surface temperature of the roller when the heater 31 and the roller part 24 are heated at a heating rate of 50° C./30 minutes in a close contact state in which the thermal contact state is improved.

Comparing the dashed line 114 and the dashed-dotted line 115, even at the same elapsed time, when the heater 31 and the roller part 24 are in a close contact state in which the thermal contact state is improved, the inner surface temperature of the roller is higher than in the case of a normal fixed state. It can be seen that it is increasing (see arrow in Fig. 11).

12 shows the relationship between the elapsed time (minutes) and the heater temperature (°C) or the temperature difference ΔT (°C) between the roller outer surface temperature and the roller inner surface temperature. In addition, the broken line 121 in FIG. 12 represents the heater temperature when the temperature is raised at a heating rate of 50°C/30 minutes, and the broken line 122 is the outer surface temperature of the roller when the temperature is raised at a heating rate of 50°C/30 minutes in a normal fixed state. The difference between the temperature and the inner surface temperature of the roller is indicated by the two-dot chain line 123, when the heater 31 and the roller part 24 are in close contact with each other to improve their thermal contact, and the temperature rises at a heating rate of 50°C/30 minutes. It shows the temperature difference between the outer surface temperature and the roller inner surface temperature.

Comparing the broken line 122 and the two-dot chain line 123, even if the same elapsed time, when the heater 31 and the roller part 24 are in a close contact state in which the thermal contact state is improved, the outer surface temperature of the roller and It can be seen that the temperature difference with the inner surface temperature of the roller is decreasing (refer to the arrow in Fig. 12).

In this modification, the following effects are exhibited.

In this modification, a metal foil is provided between the roller part 24 and the heater 31. Since the metal foil is easily deformable, the metal foil provided between the roller portion 24 and the heater 31 is deformed into a shape corresponding to the gap between the roller portion 24 and the heater 31, and the roller portion 24 ) And the heater 31 in close contact. Thus, by providing the metal foil between the roller part 24 and the heater 31, the gap formed between the roller part 24 and the heater 31 can be filled with the metal foil.

Since the metal foil has good thermal conductivity, the thermal conductivity between the roller portion 24 and the heater 31 is improved by filling the gap formed between the roller portion 24 and the heater 31 with the metal foil. Thereby, the heat flux from the heater 31 to the roller part 24 can be increased. Accordingly, since the heat of the heater 31 is easily transmitted to the inner circumferential surface of the roller part 24, the temperature increase in the inner circumferential surface is suitably performed. Accordingly, it is possible to suppress the temperature distribution on the inner circumferential surface of the roller part 24 and to suppress the occurrence of uneven stress in the entire roller part 24. Therefore, it is possible to make it difficult to damage the roller part 24.

[Modified Example 2]

Next, Modification Example 2 of the present embodiment will be described.

In this modification, in response to the conditions of a plurality of predetermined heater heating rates and the structure of the plurality of roller units 24, measurement data collected in the heating process and fitting process of the roller unit 24 is accumulated in a database, A table of data is being built. In advance, data on the structure of the roller part 24 with respect to the heater heating rate, the temperature of each part of the roller part 24 due to heating, and the measured value of the heat extension amount of the inner diameter of the roller are accumulated, and a table using the database is created. have. That is, the control device (not shown) stores the temperature increase rate of the heater 31 and the amount of heat extension of the roller part 24 in the heating process (heating rate memory step, heat extension amount memory step), and the stored temperature rise Based on the speed and the amount of heat extension, a table is created (table creation process) in which the relationship between the temperature increase rate and the amount of heat extension is determined, and the table is stored.

Here, a preheating test in which the roller part 24 is subjected to a heating process at a temporary heating rate is performed on the site where the pulverizer 1 is located. Thereby, it is possible to select an appropriate rate of temperature increase for the roller heat treatment, and to perform heating within the range of an appropriate heating condition for the roller portion 24.

The preheating test means, for example, preheating the roller part 24 for about 10 minutes relative to the predetermined rate of temperature increase, and the amount of heat extension and the rate of temperature increase over time (for example, one to two This is a test in which correlation data with conditions) is collected, and the appropriate heating rate is determined and selected by comparing it with the accumulated database (table). Further, in the heating step, while preheating the roller part 24 at a temporary heating rate, the temporary heating rate and the amount of heat extension of the roller part 24 in the preheating are determined based on the table. You may heat the roller part 24 by a temperature increase rate.

In addition, the selected heating rate can be set as a condition in which the temperature difference does not increase due to a rapid temperature gradient between the inner surface of the roller and the outer surface of the roller, so that the occurrence of stress to the hardened portion 26 provided on the outer peripheral surface of the roller is suppressed, and partial damage is prevented Because it can be suppressed, it is suitable.

According to this modification, the following effects are exhibited.

In this modified example, an appropriate heating rate of the roller part 24 is selected in advance by a preheating test, and heating is performed within the range of the heating condition of the roller part 24. Stress generation to the hardened part 26 is suppressed and partial damage is suppressed, and the working time in a heating process can be shortened.

In addition, in this modified example, an example in which heating conditions are determined by a table based on a database has been described, but by accumulating data on the heating conditions, the appropriate range of heating conditions for the sizes of various rollers can be determined. , An AI system may be constructed, and heating conditions, such as an appropriate heating rate and a heating temperature as a reference, may be determined by the AI system.

[Modified Example 3]

Next, a modified example 3 of the present embodiment will be described.

In this modification, in the heating step, the temperature increase rate is changed within an appropriate range of 1°C/min to 2°C/min, which is different from the above embodiment.

In this modified example, as shown in FIG. 13, the roller part is heated by raising the heater 31 at a heating rate of 1° C./min (first heating rate) only for a predetermined time (tens of minutes in this embodiment) from the start of heating. The outer circumferential surface of (24) is heated (first heating step), and after a predetermined period of time has elapsed, the heater 31 is heated at a heating rate of 2°C/min (second heating rate). The outer circumferential surface is being heated (2nd heating process).

A change in the temperature difference between the inner surface of the roller and the outer surface of the roller when the temperature increase rate is changed will be described with reference to FIG. 13. 13 is a graph showing the change with the elapsed time of the temperature of the heater 31, the temperature of the inner surface of the roller, and the temperature difference ΔT between the inner surface of the roller and the outer surface of the roller, where the horizontal axis represents the elapsed time (minutes), and the vertical axis represents the temperature difference ( ΔT) or temperature (°C). In addition, the halftone portion represents the elapsed time period when the required heat extension amount reaches 0.2 mm.

In addition, the broken line 131 in FIG. 13 represents the heater temperature when the temperature is raised at a heating rate of 50°C/30 minutes. In addition, the solid line 132 represents the heater temperature when the temperature increase rate is changed. In addition, the broken line 133 represents the inner surface temperature of the roller when the temperature is raised at a heating rate of 50°C/30 minutes. In addition, the solid line 134 represents the inner surface temperature of the roller when the temperature increase rate is changed. In addition, the broken line 135 represents the temperature difference between the inner surface of the roller and the outer surface of the roller when the temperature is raised at a temperature increase rate of 50°C/30 minutes. In addition, the solid line 136 represents the temperature difference between the inner surface of the roller and the outer surface of the roller when the temperature increase rate is changed.

By comparing the broken line 133 and the solid line 134, it can be seen that there is almost no difference between the roller inner surface temperature when the temperature is raised at a temperature increase rate of 50°C/30 minutes and the roller inner surface temperature when the temperature increase rate is changed. In addition, by comparing the broken line 135 and the solid line 136, the case where the temperature increase rate is changed in a predetermined time from the start of heating is compared to the case of increasing the temperature at a temperature increase rate of 50°C/30 minutes, It can be seen that the temperature difference of is reduced. And, even when the required amount of heat extension is reached, the temperature increase rate of the case where the temperature increase rate is changed is about 5°C lower than that of the case where the temperature increase rate is increased at 50°C/30 minutes. I can.

In this way, by heating the heater 31 at a heating rate of 1° C./min only for a predetermined time from the start of heating (tens of minutes in this embodiment), the inner surface of the roller and the outer surface of the roller due to the occurrence of a sudden temperature gradient on the outer side of the roller It is possible to suppress an increase in the temperature difference between and. In addition, after that, the outer peripheral surface of the roller part 24 is heated by raising the temperature of the heater 31 at a heating rate of 2° C./min to obtain the required amount of heat extension (0.2 mm), thereby determining the temperature difference between the inner surface of the roller and the outer surface of the roller. By making it small, it is possible to suppress the generation of stress to the hardened portion 26 of the crushing roller 5. Therefore, it is possible to make it difficult to damage the roller part 24. In addition, since the inner surface temperature of the roller hardly changes when the heating rate is 50°C/30 minutes and when the heating rate is changed, the working time for the heating process increases even when the heating rate is changed. There is nothing to do.

According to this modification, the following effects are exhibited.

The increase in the temperature difference between the outer circumferential surface and the inner circumferential surface of the roller part 24, which occurs due to a sudden temperature increase on the outer circumferential surface of the roller part 24 with the start of heating, is suppressed, and is provided on the outer circumferential surface of the roller part 24 The stress generated in the hardened portion 26 can be reduced. Therefore, it is possible to make it difficult to damage the roller part 24.

In addition, the predetermined time for changing the temperature increase rate is not limited to the above description. The predetermined time is the temperature at which the required heat extension amount (0.2 mm) is obtained by adjusting the temperature of the outer circumference of the roller by the higher of the rate of temperature increase before the change and the rate of temperature increase after the change. About 1/3~1/2 of the time required to heat more than).

In addition, a predetermined time may be set in advance, and the heating rate may be set accordingly.

In addition, the present invention is not limited to the invention according to the above embodiment, and can be appropriately modified within a range not departing from the gist of the invention.

For example, each modified example may be combined respectively.

Further, for example, in the above embodiment, the roller portion 24 having an outer diameter L1 of about 1.5 m and an inner diameter L4 of about 1.1 m has been described, but the present invention is not limited thereto. If the inner diameter of the roller part 24 is between about 0.5 m to about 1.8 m, suitable heating can be performed.

1: grinder
2: housing
2a: side part
2b: ceiling surface
2c: bottom part
3: air supply duct
4: crushing table
5: crushing roller
7: fuel supply pipe
8: rotary separator
9: exit port
15: rotation support
16: table part
17: journal shaft
18: journal head
19: eccentric shaft
20: pressure device
21: stopper
23: journal housing (support)
24: roller part
25: donation
26: hardened part
27: insulation brick
29: insulation
30: heating device
31: heater
32: power supply control unit
33: power supply
34: temperature instrument

Claims (13)

A circle that is used in a pulverizer for pulverizing an object to be pulverized, and has a support part rotatably supported with respect to the housing of the pulverizer, an annular base and a hardened part provided on an outer circumferential surface of the base in the radial direction of the base As a manufacturing method of a crushing roller having an annular roller portion,
A heating step of heating the roller part from the outer circumferential side of the roller part in a state in which the central axis of the roller part is in a direction orthogonal to the bottom surface, and the inner circumferential surface in the radial direction of the roller part is open to the outside air, and ,
An arrangement step of arranging the support portion and the roller portion in a state of being heated by the heating step so that the inner peripheral surface of the roller portion faces or contacts an outer peripheral surface of the support portion;
A method of manufacturing a crushing roller including a fitting step of cooling the roller portion disposed in the arrangement step to fit the support portion and the roller portion. The method according to claim 1,
The method of manufacturing a crushing roller, wherein the hardened portion includes at least a part of a member having a coefficient of thermal expansion smaller than that of the base. The method according to claim 1 or 2,
In the heating process, while forming a lower space between the roller part and the bottom surface, heating the roller part in a state in which the lower space and the inner space formed inside the inner circumferential surface of the roller part communicate with each other. Method of manufacturing a crushing roller. The method according to any one of claims 1 to 3,
In the heating step, while covering the outer peripheral surface of the roller portion in the radial direction with a heater and covering the outer peripheral surface of the heater in the radial direction with a heat insulating material, a method of manufacturing a crushing roller for heating the roller portion by heating the heater . The method of claim 4,
In the heating step, a method of manufacturing a crushing roller in which the heater is heated from a room temperature state to a predetermined temperature increasing rate while heating the roller portion. The method of claim 5,
The predetermined temperature increase rate is 1°C/min or more and 2°C/min or less. The method according to any one of claims 4 to 6,
In the heating step, a method of manufacturing a crushing roller in which a metal foil is provided between the roller part and the heater. The method according to any one of claims 4 to 7,
The heating step includes: a first heating step of heating the roller portion by heating the heater at a first heating rate until a predetermined time elapses from the start of heating; and the first heating step after the first heating step. A method for manufacturing a crushing roller, comprising a second heating step of heating the roller portion by heating at a second heating rate faster than the speed. The method according to any one of claims 4 to 8,
A plurality of the heaters are provided,
A method for manufacturing a crushing roller in which a plurality of the heaters are arranged in a circumferential direction so as to follow the outer peripheral surface of the roller part, and the temperature increase rate is controlled by a different temperature increase rate control unit. The method according to any one of claims 5 to 9,
A temperature increase rate storage step of storing a temperature increase rate of the heater in the heating step,
A heat extension amount storage step of storing a heat extension amount of the roller portion in the heating step,
A table creation step of creating a table in which a relationship between a temperature increase rate and a heat extension amount is determined based on a temperature increase rate memorized in the temperature increase rate storage step and a heat extension amount memorized in the heat growth amount storage step,
In the heating step, while preheating the roller part at a temporary heating rate, the temporary heating rate and the amount of heat extension of the roller part in the pre-heating, and the temperature increasing rate determined based on the table A method of manufacturing a crushing roller in which the roller portion is heated by. A heating device used in a crusher for pulverizing an object to be pulverized, and is provided on an annular base and an outer circumferential surface of the base in a radial direction to increase temperature of an annular roller portion having a hardened portion having a different coefficient of thermal expansion than the base,
A heater provided to cover an outer peripheral surface of the roller part in the radial direction,
It has a temperature increase rate control unit for controlling the temperature increase rate of the heater,
The temperature increase rate control unit controls the heater so that the temperature increase rate is 1°C/min or more and 2°C/min or less. The method of claim 11,
The heater is disposed in a state in which the central axis is in a direction orthogonal to the bottom surface, and the inner peripheral surface in the radial direction of the roller part is open to outside air, and is provided with respect to the disposed roller part. The method according to claim 11 or 12,
A plurality of the heaters are provided,
A plurality of the heating rate control unit is provided,
The plurality of heaters are arranged side by side in the circumferential direction so as to follow the outer circumferential surface in the radial direction of the roller portion, and the heating rate is controlled by the different heating rate control units.

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