CN112292209B - Method for manufacturing grinding roller and temperature rising device - Google Patents

Abstract

A method of manufacturing a mill roller, the mill roller comprising: a journal housing rotatably supported by the housing of the pulverizer; and an annular roller portion (24) having an annular base portion (25) and a solidified portion (26) provided on the outer peripheral surface of the base portion (25) and having a thermal expansion coefficient smaller than that of the base portion (25), the method for manufacturing the pulverization roller comprising: a heating step of heating the roller section (24) from the outer peripheral surface side in a state where the roller section (24) is disposed such that the central axis (C1) thereof is oriented perpendicular to the ground surface and the inner peripheral surface is open to the outside air; a placement step of placing the journal housing and the roller section (24) in a state of being heated in the heating step such that the inner circumferential surface of the roller section (24) faces or contacts the outer circumferential surface of the journal housing; and a fitting step of cooling the roller portion (24) disposed in the disposing step to fit the journal housing and the roller portion (24).

Description

Method for manufacturing grinding roller and temperature rising device

Technical Field

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

Background

As a pulverizer for pulverizing a pulverized material used for the purpose of pulverizing a solid fuel such as coal into a fine powder having a particle size smaller than a predetermined particle size and supplying the pulverized material to a combustion apparatus, there is known a pulverizer in which a pulverized material placed on a pulverizing table rotating about a vertical upper and lower axis is pressed by a pulverizing roller rotatably supported inside the pulverizer to be pulverized.

The mill roller used in this type of mill has a journal housing rotatably attached to a housing of the mill and a roller portion made of a metal material that is in contact with and presses against the material to be milled. The journal housing and the roller portion are fitted together by shrink-fitting, and when the roller portion is worn, the roller portion can be removed and maintained (for example, a pulverized coal machine roller of patent document 1).

Prior art documents

Patent document

Patent document 1: japanese patent No. 5259162

Disclosure of Invention

Technical problem to be solved by the invention

Recently, as a crushing roller used in a crusher, there are used a crushing roller having a roller portion having a solidified portion on a surface thereof, and further, a ceramic insert casting roller in which a ceramic is embedded in a surface of a roller portion made of high chromium cast iron having excellent wear resistance. Since the ceramic insert casting roll can crush the material to be crushed not only by the ceramic portion of the surface but also by the high chromium cast iron which is the base material, the wear amount can be allowed to be significantly increased, and the life of the crushing roll can be extended.

However, in the ceramic insert casting roll, the cured portion (particularly, the ceramic inserted into the cured portion) provided on the roll portion surface has a different thermal expansion coefficient from the base material made of high-chromium cast iron. Therefore, when the roller portion and the base material are assembled by the hot press-fitting like the pulverized coal machine roller of patent document 1, the solidified portion (particularly, the ceramic portion) on the surface may be damaged due to the difference in the thermal expansion coefficient when the temperature is raised by heating the roller portion, and therefore the assembly by the clearance fitting is the mainstream. In order to perform the clearance fit, in addition to the dimensional control of the fitting portion between the journal housing and the roller portion, the fitting process of the fixing member is required, which causes an increase in the modification cost and the maintenance workload.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a pulverizing roller and a temperature increasing device that can prevent cracks from easily propagating to a solidified portion and thereby prevent the solidified portion from being damaged when hot press fitting is performed.

Means for solving the technical problem

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

In a method for manufacturing a mill roller according to an aspect of the present invention, the mill roller includes: a support portion for supporting a crusher for crushing a material to be crushed in a rotatable manner in a housing of the crusher; and an annular roller portion having an annular base portion and a solidified portion provided on an outer peripheral surface of the base portion in a radial direction and having a thermal expansion coefficient different from that of the base portion, the method for manufacturing the pulverization roller including: a heating step of heating the roller portion from the outer circumferential surface side in the radial direction of the roller portion in a state where the central axis of the roller portion is in a direction orthogonal to the ground and the inner circumferential surface in the radial direction of the roller portion is open to the outside air; a placement step of placing the support portion and the roller portion in a state in which the temperature is increased in the heating step such that the inner peripheral surface of the roller portion faces or contacts the outer peripheral surface of the support portion; and a fitting step of cooling the roller portion disposed in the disposing step to fit the support portion and the roller portion.

In the above configuration, the roller portion and the support portion are fitted by so-called shrink fit in which the heated roller portion is cooled and fitted to the support portion.

In the above configuration, in the heating step, the roller portion is heated from the outer peripheral surface side in a state where the inner peripheral surface of the roller portion is open to the outside air. Therefore, the outer peripheral surface side of the roller portion is heated more quickly than the inner peripheral surface side, and becomes a higher temperature than the inner peripheral surface side. Thereby, the base of the roller portion thermally expands outward in the radial direction (i.e., outward in a manner that the outer strain is large). On the other hand, since the cured portion has a different thermal expansion coefficient from the base portion, the amount of thermal expansion is smaller or larger than that of the base portion. Therefore, when the roller portion thermally expands outward in the radial direction, the pressing force acts on the solidified portion in the radial direction due to the restriction to the base portion. Therefore, a compressive stress in the radial direction is generated in the cured portion. In this way, in the heating step of heating the roll portion, the stress generated in the cured portion can be regarded mainly as compressive stress, and therefore the tensile stress generated in the cured portion can be suppressed, and cracks can be made less likely to propagate to the cured portion. Therefore, the cured portion can be made less susceptible to damage.

In addition, since the roller portion and the support portion can be fitted together by the hot press fitting, even in a mill roller having a solidified portion on the outer peripheral surface, the roller portion and the support portion can be fitted together without performing special processing on the roller portion and the support portion, thereby manufacturing the mill roller. Therefore, the cost can be reduced and the time required for manufacturing can be shortened as compared with a method in which the roller portion and the support portion are subjected to special processing.

The roller portion is heated from the outer peripheral surface side in a state where the central axis of the roller portion is oriented in a direction perpendicular to the ground and the inner peripheral surface is open to the outside air (in other words, in a state where the atmosphere is open). As a result, the air in the space formed inside the inner peripheral surface of the annular roller portion (hereinafter referred to as "inside space") is heated to increase the temperature, and is released into the atmosphere as an updraft by the chimney effect. Therefore, the air heated in the inner space does not stagnate, and therefore, the spread of the temperature distribution in the inner peripheral surface of the roller portion can be suppressed, and the occurrence of uneven stress in the entire roller portion can be suppressed. Therefore, the roller portion can be made less susceptible to damage. Examples of the damage of the roller portion include the occurrence of local micro cracks, the propagation of internal cracks, and partial falling.

In the step of heating the roller portion, the inner peripheral surface of the roller portion is in an open state to the outside air, and therefore, the inner peripheral surface of the roller portion can be contacted in the heating step. In this way, in the heating step, the thermal elongation of the inner diameter of the roll portion can be measured by a vernier caliper, a laser distance meter, or the like. Therefore, the heating can be performed while checking the thermal elongation of the inner diameter of the roller portion, and thus a desired thermal elongation can be reliably set. Further, since the thermal elongation is continuously checked, the heating step can be ended at a timing at which the thermal elongation is desired, and thus the heating step can be shortened by preventing unnecessary time from occurring due to overheating or the like.

In the method of manufacturing a pulverizing roller according to one aspect of the present invention, at least a part of the solidified portion may include a member having a thermal expansion coefficient smaller than that of the base portion.

In the above structure, at least a part of the cured portion includes a member having a thermal expansion coefficient smaller than that of the base portion, such as ceramic. When the cured portion expands outward in the radial direction, a pressing force acts on the cured portion and a compressive stress in the radial direction is generated, so that even if there is a member having a smaller thermal expansion amount than the base portion, a crack can be made less likely to propagate to a member having a small thermal expansion coefficient, such as ceramic, in the cured portion by the compressive stress generated in the cured portion. Therefore, the cured portion can be made less susceptible to damage.

In the method of manufacturing a mill roller according to one aspect of the present invention, in the heating step, a lower space may be formed between the roller portion and the floor surface, and the roller portion may be heated in a state where the lower space communicates with an inner space formed inside the inner circumferential surface of the roller portion.

In the above structure, the lower space formed between the roller portion and the ground communicates with the inside space. As a result, air flows in from below the inner space through the lower space, and thus the chimney effect is more effectively exhibited, and an updraft can be reliably generated in the inner space. Therefore, the temperature distribution of the inner circumferential surface of the roller can be more appropriately suppressed, and the generation of uneven stress in the entire roller portion can be suppressed.

In the method of manufacturing a pulverizing roller according to one aspect of the present invention, in the heating step, the roller portion may be heated by raising the temperature of the heater while the outer peripheral surface of the roller portion in the radial direction is covered with the heater and the outer peripheral surface of the heater in the radial direction is covered with an insulating material.

In the above configuration, since the outer peripheral surface of the heater is covered with the heat insulating material, heat dissipation from the heater is reduced, and the heat flux from the heater toward the roller portion can be stabilized. Therefore, the distribution of the heat transfer amount from the heater to the outer peripheral surface of the roller portion can be suppressed to be uniform.

Further, since the inner peripheral surface of the roller portion is in an open state (i.e., on the low temperature side), the heat input from the outer peripheral surface side is likely to move toward the inner peripheral surface side. In this way, the direction of the heat flux toward the inner peripheral surface side can be specified, and therefore, the temperature rise on the inner peripheral surface side of the roller portion can be stabilized.

In the method of manufacturing a pulverizing roller according to one aspect of the present invention, in the heating step, the heater may be configured to heat the roller portion while increasing the temperature from a room temperature state at a predetermined temperature increase rate.

It takes a predetermined time for the heat input from the outer peripheral surface to be transferred to the inner peripheral surface. Therefore, when the roller portion is heated from the outer circumferential surface by the heater, a temperature difference is generated between the outer circumferential surface and the inner circumferential surface. In the above configuration, the roller portion is heated while raising the temperature of the heater from a room temperature state at a predetermined temperature raising rate. Thereby, the outer circumferential surface and the inner circumferential surface of the roller portion are also heated to follow the heating of the heater. Therefore, the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller portion is smaller than in the method of heating the roller portion while keeping the temperature of the outer peripheral surface of the roller portion constant by a heater for keeping the temperature constant. Therefore, the stress generated in the cured portion provided on the outer peripheral surface side of the roller portion can be reduced. Therefore, the roller portion can be made less susceptible to damage.

In the method for manufacturing a pulverizing roller according to one aspect of the present invention, the predetermined temperature increase rate may be 1 ℃/min or more and 2 ℃/min or less.

If the temperature increase rate of the heater is slowed, the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller portion can be sufficiently reduced, and the roller portion can be made less likely to be damaged, but it takes time to obtain the thermal elongation necessary for the thermal press-fitting of the roller portion and the support portion, which causes a heating process to be lengthened, and thus the workability to be degraded. On the other hand, if the temperature increase rate of the heater is increased, the heating process can be shortened, but the temperature difference between the inner circumferential surface and the outer circumferential surface of the roller portion cannot be sufficiently reduced, and the possibility of damage occurring to the roller portion increases.

In the above configuration, the heater is heated at a heating rate of 1 ℃/min to 2 ℃/min. In this way, the temperature difference between the inner circumferential surface and the outer circumferential surface of the roller portion can be sufficiently reduced by setting the temperature rise rate to 2 ℃/min or less, and the roller portion is less likely to be damaged, and the temperature rise rate to 1 ℃/min or more can prevent an excessively long time of the heating step and improve the workability.

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

In the above configuration, the 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 corresponding to a gap between the roller portion and the heater, and is brought into close contact with the roller portion and the heater to reduce contact thermal 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 gap formed between the roller portion and the heater is filled with the metal foil, thereby improving the thermal conductivity between the roller portion and the heater. This can increase the heat flux from the heater to the roller portion. Therefore, the heat of the heater is easily transmitted to the inner circumferential surface of the roller portion, and therefore the temperature of the inner circumferential surface can be appropriately increased. Therefore, the temperature distribution of the inner peripheral surface of the roller portion can be suppressed, and the generation of uneven stress in the entire roller portion can be suppressed. Therefore, the roller portion can be made less susceptible to damage.

Examples of the metal foil include aluminum foil.

In the method of manufacturing a pulverizing roller according to one aspect of the present invention, the heating step may include: a 1 st heating step of heating the roller portion by raising the temperature of the heater at a 1 st temperature raising rate until a predetermined time elapses from a heating start time; and a 2 nd heating step of heating the roller portion by raising the temperature of the heater at a 2 nd temperature raising rate faster than the 1 st temperature raising rate after the 1 st heating step.

In the above configuration, the heating of the roller portion is performed by raising the temperature of the heater at the 1 st temperature raising rate until a predetermined time elapses from the heating start time. This can suppress an increase in the temperature difference between the outer peripheral surface and the inner peripheral surface of the roller portion caused by a rapid temperature increase in the outer peripheral surface of the roller portion with the start of heating. Therefore, the stress generated in the cured portion provided on the outer peripheral surface side of the roller portion can be reduced. Therefore, the roller portion can be made less susceptible to damage.

In the method of manufacturing a pulverizing roller according to one aspect of the present invention, a plurality of the heaters may be provided, and the plurality of the heaters may be arranged in a circumferential direction so as to be arranged along the outer circumferential surface of the roller portion, and the temperature increase rates may be controlled by different temperature increase rate control portions.

In the above configuration, the plurality of heaters covering the outer peripheral surface of the roller portion are arranged in an array, and the temperature increase rates are controlled by different temperature increase rate control portions, respectively. Thus, by appropriately controlling the temperature increase rate of each heater individually, even in a large-sized roller portion, the occurrence of the temperature distribution on the outer peripheral surface of the roller portion can be suppressed. Since the heat input from the outer peripheral surface can be made uniform by suppressing the occurrence of the temperature distribution of the outer peripheral surface, the temperature distribution of the inner peripheral surface of the roller portion can be suppressed.

Further, since the plurality of heaters covering the outer peripheral surface of the roller portion are arranged in line, the heaters can be downsized. This can reduce the temperature distribution in each heater, and thus can suppress the occurrence of the temperature distribution on the outer peripheral surface of the roller portion.

A method of manufacturing a mill roller according to an aspect of the present invention includes: a temperature increase rate storage step of storing the temperature increase rate of the heater in the heating step; a thermal elongation storage step of storing the thermal elongation of the roller portion in the heating step; and a table creating step of creating a table defining a relationship between the temperature increase rate and the thermal elongation amount on the basis of the temperature increase rate stored in the temperature increase rate storage step and the thermal elongation amount stored in the thermal elongation amount storage step, wherein in the heating step, the roller portion is preliminarily heated at a temporary temperature increase rate, and the roller portion is heated on the basis of the temporary temperature increase rate, the thermal elongation amount of the roller portion during the preliminary heating, and the temperature increase rate determined by the table.

In the above configuration, by performing preliminary heating for heating the roller portion at the temporary temperature increase rate in a site where the pulverizer is present, the appropriate temperature increase rate of the heating process of the roller portion can be determined and heating can be performed within the range of the appropriate heating condition of the roller portion.

The determined temperature increase rate is preferably set to a condition that the temperature difference between the roll inner surface and the roll outer surface due to a rapid temperature gradient does not increase, because stress generated in a cured portion provided on the outer peripheral surface of the roll portion can be suppressed to suppress local damage.

A temperature raising device according to an aspect of the present invention is a temperature raising device for a pulverizer configured to pulverize an object to be pulverized, the temperature raising device being configured to raise a temperature of an annular roller portion having an annular base portion and a cured portion provided on an outer circumferential surface of the base portion in a radial direction and having a thermal expansion coefficient different from that of the base portion, the temperature raising device including: a heater provided so as to cover an outer circumferential surface of the roller portion in a radial direction; and a temperature rise rate control unit that controls a temperature rise rate of the heater, wherein the temperature rise rate control unit controls the heater so that the temperature rise rate is 1 ℃/min or more and 2 ℃/min or less.

In the temperature raising device according to the aspect of the present invention, the heater may be disposed in a state in which a central axis thereof is perpendicular to a ground surface, and the heater may be provided in the roller portion disposed in a state in which an inner circumferential surface of the roller portion in a radial direction is open to outside air.

If the temperature increase rate of the heater is slowed, the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller portion can be sufficiently reduced, and the roller portion can be made less likely to be damaged, but it takes time to obtain the thermal elongation necessary for the thermal press-fitting of the roller portion and the support portion, which leads to a long heating process. On the other hand, if the temperature increase rate of the heater is increased, the heating process can be shortened, but the temperature difference between the inner circumferential surface and the outer circumferential surface of the roller portion cannot be sufficiently reduced, and the possibility of damage occurring to the roller portion increases.

In the above configuration, the heater is heated at a heating rate of 1 ℃/min to 2 ℃/min. In this way, the temperature difference between the inner circumferential surface and the outer circumferential surface of the roller portion can be sufficiently reduced by setting the temperature rise rate to 2 ℃/min or less, so that the roller portion is less likely to be damaged, and the temperature rise rate to 1 ℃/min or more can suppress an excessive increase in time of the heating step, thereby improving the workability.

In the temperature raising device according to the aspect of the present invention, a plurality of the heaters may be provided, a plurality of the temperature raising rate control units may be provided, and the plurality of the heaters may be arranged in a circumferential direction so as to be along an outer circumferential surface of the roller portion in the radial direction, and the temperature raising rates may be controlled by the different temperature raising rate control units.

In the above configuration, the plurality of heaters covering the outer peripheral surface of the roller portion are arranged in an array, and the temperature increase rates are controlled by different temperature increase rate control portions, respectively. Thus, by appropriately controlling the temperature increase rate of each heater individually, even if the roller portion is large in size, the occurrence of the temperature distribution on the outer peripheral surface of the roller portion can be suppressed. Since the heat input from the outer peripheral surface can be made uniform by suppressing the occurrence of the temperature distribution of the outer peripheral surface, the temperature distribution of the inner peripheral surface of the roller portion can be suppressed.

Further, since the plurality of heaters covering the outer peripheral surface of the roller portion are arranged in line, the heaters can be downsized. This can reduce the temperature distribution in each heater, and thus can suppress the occurrence of the temperature distribution on the outer peripheral surface of the roller portion.

Effects of the invention

According to the present invention, when the shrink fit is performed, cracks are less likely to propagate to the cured portion, and the cured portion can be less likely to be damaged.

Drawings

Fig. 1 is a vertical sectional view showing a schematic configuration of a solid fuel pulverizer to which a pulverizing roller manufactured by a method for manufacturing a pulverizing roller according to an embodiment of the present invention is applied.

Fig. 2 is a perspective view of the pulverizing roller of fig. 1.

Fig. 3 is a longitudinal sectional view of the pulverizing roller of fig. 1.

Fig. 4 is a schematic vertical sectional view of the crushing roller for explaining the heating step of the method of manufacturing the crushing roller according to the present embodiment.

Fig. 5 is a schematic diagram showing a temperature raising device according to the present embodiment.

Fig. 6 is a graph showing changes over time between the temperature of the heater, the temperature of the roll inner surface, and the temperature difference between the roll inner surface and the roll outer surface.

Fig. 7 is a graph showing the change over time of the heater temperature, the roll inner surface-roll outer surface temperature difference, and the inner diameter thermal elongation when the heater is heated at a heating rate of 10 ℃/30 minutes.

Fig. 8 is a graph showing the change over time of the heater temperature, the roll inner surface-roll outer surface temperature difference, and the inner diameter thermal elongation when the heater is heated at a heating rate of 50 ℃/30 minutes.

Fig. 9 is a graph showing the change over time of the heater temperature, the roll inner surface-roll outer surface temperature difference, and the inner diameter thermal elongation when the heater is heated at a heating rate of 90 ℃/30 minutes.

Fig. 10 is a graph showing the relationship between the temperature increase rate of the heater and the required thermal elongation arrival time, and the relationship between the temperature increase rate of the heater and the roll inner surface temperature.

Fig. 11 is a graph showing a relationship with a heater temperature or a roller inner surface temperature.

Fig. 12 is a graph showing the relationship between elapsed time and the temperature difference between the heater temperature or the roll outer surface temperature and the roll inner surface temperature.

Fig. 13 is a graph showing the change with time between the temperature of the heater, the temperature of the roll inner surface, and the temperature difference between the roll inner surface and the roll outer surface.

Detailed Description

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

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

In the present embodiment, the upward direction represents the direction of the vertically upper side, and the "upward" of the upper portion, the upper surface, or the like represents the portion of the vertically upper side. Similarly, "lower" indicates a vertically lower portion. The outer and inner peripheral surfaces indicate the outer and inner peripheries of the annular roller portion 24 in the radial direction from the center axis.

As shown in fig. 1, the pulverizer 1 includes a cylindrical hollow casing 2 having an outer shell, and an air supply duct 3 communicating with a lower side surface of the casing 2 and supplying a carrier gas into the casing 2. A mill table 4 supported rotatably about a rotation axis in the vertical up-down direction on the casing 2 and a mill roller 5 for milling a material to be milled (in the present embodiment, a solid fuel such as coal, for example) on the mill table 4 are accommodated in the casing 2.

The casing 2 has a cylindrical shape, and a cylindrical fuel supply pipe 7 is provided at the upper center so as to penetrate the top surface portion 2 b. The fuel supply pipe 7 supplies solid fuel such as coal into the casing 2 from a solid fuel supply device not shown, and extends vertically at a center position of the casing 2. A rotary separator 8 is provided that rotates around the fuel supply pipe 7 in the casing 2 and is present in a direction orthogonal to the longitudinal direction of the fuel supply pipe 7. The rotary classifier 8 classifies the pulverized solid fuel (hereinafter, the pulverized solid fuel is referred to as "fine powder fuel") according to a predetermined particle diameter. The top surface 2b of the casing 2 is provided with an outlet port 9 as a carrying-out port for conveying the fine fuel having a predetermined particle size or less classified by the rotary classifier 8 to downstream equipment.

The mill table 4 includes a rotation support portion 15 rotatably supported at substantially the center of the bottom surface portion 2c of the casing 2, and a table portion 16 of a substantially circular plate shape fixed to the upper end of the rotation support portion 15. The rotation support portion 15 is rotationally driven by a driving device not shown. The table portion 16 is disposed to face the lower end portion of the fuel supply pipe 7 on the lower vertical side, and rotates together with the rotation support portion 15. The upper surface of the mill table 4 extends in the horizontal direction, the height of the central portion is higher than that of the outer portion in the vertical upward direction, and the mill table has an inclined shape in which the height gradually decreases from the central portion toward the outer portion, and the outer peripheral portion is bent upward again.

The air supply duct 3 is provided to extend substantially parallel to a horizontal plane and communicates with the side surface portion 2a of the housing 2. The air supply duct 3 supplies a transport gas supplied from an air supply device not shown into the casing 2. The transportation gas supplied from the air supply conduit 3 transports the fine powder fuel, which is sandwiched between the pulverization table 4 and the pulverization roller 5 on the pulverization table 4 and pulverized, to the rotary classifier 8 by air flow.

A plurality of mill rollers 5 (3 in the present embodiment, for example) are disposed above and in the vertical direction of the outer peripheral portion of the table portion 16 so as to face the table portion 16. In fig. 1, only 1 of the plurality of pulverizing rollers 5 is shown for the sake of illustration. The plurality of pulverizing rollers 5 are arranged at equal intervals in the circumferential direction. For example, 3 pulverizing rollers 5 are arranged at regular intervals in the circumferential direction at angular intervals of 120 ° on the outer circumferential portion. The pulverizing roller 5 will be described in detail later.

Each mill roller 5 is fixed to the casing 2 via a journal bracket 17, a journal head 18, and an eccentric shaft 19 (see also fig. 2 and 3). The journal bracket 17 extends so as to be inclined vertically downward from the side surface portion 2a of the casing 2 toward the center portion, and the mill roller 5 is rotatably supported at the tip end portion via a bearing (not shown). That is, the mill roller 5 is supported above the mill table 4 in the vertical direction so as to be rotatable in a state in which the upper side is positioned closer to the center portion side of the casing 2 than the lower side.

The middle portion of the journal head 18 is supported by the side surface portion 2a of the housing 2 so as to be vertically swingable via an eccentric shaft 19 extending in the horizontal direction. The journal head 18 is supported by the base end of a journal frame 17 to which the grinding roller 5 is rotatably attached at the tip. That is, the mill roller 5 is supported so as to be vertically swingable about the eccentric shaft 19 by the journal head 18 and be capable of being separated from and brought into contact with the upper surface of the mill table 4.

A pressing device 20 is provided at an upper end portion located vertically above the journal head 18, and a stopper 21 is provided at a lower end portion of the journal head 18. The pressing device 20 is fixed to the casing 2, and applies a downward load to the mill roller 5 via the journal head 18 or the like, the load being for milling the solid fuel supplied to the mill table 4. The stopper 21 is fixed to the housing 2, and regulates the gap between the mill roller 5 and the mill table 4 while limiting the amount of rotation of the mill roller 5 in the vertical direction.

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

The mill roller 5 includes a journal housing (support portion) 23 rotatably supported by the distal end portion of the journal bracket 17, and an annular roller portion 24 externally fitted to the journal housing 23. The journal housing 23 is provided to cover the front end of the journal holder 17, and has a cylindrical outer peripheral surface.

In the present embodiment, as shown in fig. 3, the roller portion 24 includes a base portion 25 made of high-chromium cast iron fitted to the journal housing 23, and a solidified portion 26 partially including a ceramic member provided on the outer peripheral surface of the base portion 25. That is, the roll portion 24 according to the present embodiment is a so-called ceramic embedded high-chromium cast iron roll. The base portion 25 is formed in a substantially circular ring shape. The base 25 is fitted to the journal housing 23 so that the inner peripheral surface thereof contacts the outer peripheral surface of the journal housing 23. The cured portion 26 is fixed so as to be fitted over substantially the entire circumferential region of the outer circumferential surface of the annular base portion 25. Since the solidified portion 26 is made of ceramic, the thermal expansion coefficient is smaller than that of the base portion 25 made of high-chromium cast iron.

In the present embodiment, the outer diameter L1 of the roller portion 24 is, for example, about 1m to about 2m, the length L2 of the roller portion 24 in the center axis direction is, for example, about 0.3m to about 0.7m, and the length L3 of the roller portion 24 in the radial direction is, for example, about 0.1m to about 0.3 m. That is, the inner diameter L4 of the roller portion 24 is about 0.5m to about 1.8m (see fig. 4).

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

In the present embodiment, the roller portion 24 is heated from the outer peripheral surface side in the radial direction, and the inner diameter of the inner peripheral surface of the roller portion 24 is increased by thermal expansion (heating step), so that the journal housing 23 is positioned in a space (hereinafter referred to as "inner space") formed inside the inner peripheral surface of the roller portion 24 in an inner diameter expanded state by heating (arrangement step), and then the roller portion 24 is cooled to reduce the inner diameter of the roller portion 24, and the journal housing 23 and the roller portion 24 are fitted (fitting step). That is, the journal housing 23 and the roller portion 24 are fitted to each other by so-called shrink fitting. In the disposing step, the inner circumferential surface of the roller portion 24 is disposed so as to face or contact the outer circumferential surface of the journal housing 23.

The heating step will be described in detail.

In the heating step, first, as shown in fig. 4, the roller portion 24 is disposed on the base formed of the heat insulating bricks 27 on the floor surface such that the center axis C1 is perpendicular to the floor surface. In other words, the roller portion 24 is disposed so that the circular surface is horizontal to the ground. The height of the base is 50mm to 200mm, and the base is provided so as to form a lower space between the roller portion 24 and the ground. The heat insulating bricks 27 forming the base are disposed so that the lower space communicates with the inner space of the roller portion 24. The arrows in fig. 4 show a state in which the air in the inner space is heated by the temperature difference with the inner circumferential surface of the roller portion 24 to increase in temperature, and is released into the atmosphere as an updraft by the chimney effect.

Substantially the entire area of the outer peripheral surface of the roller portion 24 is covered with a plurality of heaters 31 provided along the outer peripheral surface. When the heater 31 is provided on the outer peripheral surface of the roller portion 24, it is preferable that the heater 31 is as uniformly adhered to the outer peripheral surface of the roller portion 24 as possible, but in practice, the heater 31 is fixed by tying a plurality of portions or the like in the vertical direction of the outer peripheral surface with a wire rope or the like so that at least the heater 31 does not become loose with respect to the outer peripheral surface of the roller portion 24. Substantially the entire outer peripheral surface of the heater 31 is covered with the heat insulating material 29 provided along the outer peripheral surface.

The inner circumferential surface of the roller portion 24 is not covered with the heater 31, the heat insulator 29, or the like, and is in a state of being open to the outside air (i.e., a state of being open to the atmosphere).

In the heating step, the heater 31 is heated at a predetermined temperature increase rate to heat the roller portion 24 in the room temperature state thus arranged from the room temperature state.

Next, a temperature increasing device 30 that heats the roller portion 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 (3 in the present embodiment) heaters 31 arranged in a circumferential direction so as to be arranged along the outer peripheral surface of the roller portion 24, a plurality of (3 in the present embodiment) power supply control portions (temperature raising rate control portions) 32 that control the amount of power supplied to the respective heaters 31, a power supply portion 33 that supplies power to the respective power supply control portions 32, and a temperature measuring instrument 34 that measures the temperature of the outer peripheral surface of the roller portion 24.

Each heater 31 is a flexible planar heater 31 that can be brought into close contact with the outer peripheral surface of the roller portion 24, such as a mat heater or a band heater. Each heater 31 is disposed so as to cover a region equally dividing the outer peripheral surface of the roller portion 24 into 3 portions in the axial direction. That is, substantially the entire area of the outer peripheral surface of the roller portion 24 is covered with 3 heaters 31 having substantially the same shape.

The temperature measuring instrument 34 is provided in 1 each of the regions where each heater 31 is provided in the outer peripheral surface of the roller portion 24, and measures the temperature of the outer peripheral surface of the roller portion 24 in the provided region. The temperature measuring instrument 34 transmits the measured temperature to the power supply control unit 32. The temperature measuring instrument 34 may be any temperature measuring instrument capable of measuring temperature, and examples thereof include a thermocouple.

As described above, the power supply control unit 32 is provided with 3 units, and the 3 units of power supply control unit 32 control the temperature increase rate of the heater 31 by controlling the amount of power supplied to the different heaters 31. That is, 3 power supply control units 32 correspond to 3 heaters 31 one-to-one. Further, each of the power supply control units 32 may adjust the amount of power supplied to each of the heaters 31 so that the temperature measured by each of the temperature measuring instruments 34 is substantially the same, based on the temperature measured by the temperature measuring instrument 34.

The power supply control Unit 32 is configured by, 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. Further, as an example, a series of processes for realizing various functions are stored in a storage medium or the like in the form of a program, and the program is read out to a RAM or the like by a CPU to execute processing and arithmetic processing of information, thereby realizing various functions. The program may be installed in advance in a ROM or other storage medium, provided in a state of being stored in a computer-readable storage medium, transmitted via a wired or wireless communication means, or the like. The computer-readable storage medium is a magnetic disk, an optical magnetic disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

The number of heaters 31, power supply control unit 32, and temperature measuring instruments 34 is not limited to the above example. The number of the substrates may be single or plural other than 3.

Next, a method of heating the roller portion 24 by the temperature increasing device 30 in the heating step will be described.

In the heating step according to the present embodiment, the roller portion 24 is heated while the temperature of the heater 31 of the temperature increasing device 30 is increased at a predetermined temperature increasing rate. Specifically, the temperature of the heater 31 is increased at a temperature increase rate of 1 ℃/min to 2 ℃/min, thereby heating the roller section 24. In this way, in the present embodiment, the temperature of the outer peripheral surface and the temperature of the inner peripheral surface of the roller portion 24 are made to follow the increase in the temperature of the heater 31 by heating the roller portion 24 while raising the temperature of the heater 31 at a predetermined temperature raising rate.

On the other hand, as a method of heating the roller portion 24 using the heater 31, a method of heating the roller portion 24 using the heater 31 which is kept at a constant temperature may be considered. However, it has been found that when the roller portion 24 is heated by the heater 31 which is kept at a constant temperature, the temperature of the outer peripheral surface of the roller portion 24 is kept at a substantially constant temperature at a temperature slightly lower than the temperature of the heater 31, but the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller portion 24 increases, and there is a possibility that damage or the like occurs in the roller portion 24. Further, it has been found that, in the method of heating the roller portion 24 while raising the temperature of the heater 31 at a predetermined temperature raising rate, the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller portion 24 can be reduced and the stress generated in the cured portion 26 provided on the outer peripheral surface of the roller portion 24 can be reduced as compared with the method of heating the roller portion 24 with the heater 31 kept at a constant temperature.

The case where the temperature difference between the inner circumferential surface and the outer circumferential surface of the roller portion 24 is small will be described in detail with reference to the graph of fig. 6. Fig. 6 is a graph showing changes with time between the temperature of the heater 31, the temperature of the inner peripheral surface of the roller portion 24 (hereinafter also referred to as "roller inner surface"), and the temperature difference between the roller inner surface and the outer peripheral surface of the roller portion 24 (hereinafter also referred to as "roller outer surface"), in which the horizontal axis shows elapsed time (minutes) and the vertical axis shows the temperature difference Δ T (c) or temperature (c).

The 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 ℃. Also, a solid line 62 indicates the roll inner surface temperature at 200 ℃ at which the temperature of the heater 31 is kept constant, and a solid line 63 indicates the temperature difference between the roll inner surface and the roll outer surface at that time. The broken line 64 in fig. 6 indicates the temperature of the heater 31 when the temperature of the heater 31 is increased at a rate of 50 ℃/30 minutes. The dotted line 65 indicates the roll inner surface temperature when the temperature of the heater 31 is raised at a rate of 50 ℃/30 minutes, and the dotted line 66 indicates the temperature difference between the roll inner surface and the roll outer surface at that time.

The roll inner surface temperature T in fig. 6 is calculated by the following formula (1).

(T-Ta)/(To-Ta)＝Exp(-hA/(CM)×τ)......(1)

Wherein, T: unsteady temperature of the inner surface of the roll

To: initial temperature of the inner surface of the roll (e.g., this time 25 ℃ at room temperature)

Ta: heating side temperature (i.e. this time the heater 31 temperature)

C: specific Heat of roller (for example, 0.5 to 0.6kJ/kg ℃ C.)

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

τ: time of day

M: mass of the roll

A: area of the roller

ρ: density of the roll

t: heat transfer distance of roller

Here, since M is a ρ t, the above formula (1) is the following formula (2).

(T-Ta)/(To-Ta)＝Exp(-h/(Cρt)×τ)......(2)

Comparing the solid line 63 and the broken line 66 shown in fig. 6, it is understood that the temperature difference between the heater heating surface (i.e., the roll outer surface) and the roll inner surface is smaller when the roll portion 24 is heated while raising the temperature of the heater 31, as compared to when the roll portion 24 is heated while keeping the temperature of the heater 31 constant at all times. For example, as is clear from fig. 6, when the elapsed time is 20 minutes to 40 minutes, the temperature difference between the heater heating surface (i.e., the roll outer surface) and the roll inner surface can be suppressed to about 1/3 or less when the roll portion 24 is heated while raising the temperature of the heater 31, compared to when the roll portion 24 is heated while keeping the temperature of the heater 31 constant.

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

In the present embodiment, the temperature of the heater 31 is raised at a temperature raising rate of 1 ℃/min or more and 2 ℃/min or less, thereby heating the roller portion 24. The temperature increase rate is set according to the result of the heating test of the roller portion 24, and by appropriately selecting the temperature increase rate of the heater 31, it is possible to obtain a heating condition for the roller with a thermal elongation of the inner diameter of the roller portion 24 that can be press-fitted even if the temperature of the inner peripheral surface of the roller portion 24 is relatively low (for example, about 30 to 50 ℃). The heating test of the roller portion 24 will be described below with reference to fig. 7 to 9.

In the present embodiment, when the roll portion 24 and the journal housing 23 are shrink-fitted, the roll portion 24 of the embodiment has an inner diameter L4 of, for example, about 0.5m to about 1.8m, and the required thermal elongation in the radial direction of the inner diameter of the roll portion 24 is set to, for example, about 0.2 mm.

Fig. 7 to 9 are graphs showing measured values of the temperature of the heater 31, the temperature of the roll inner surface, the temperature difference between the roll inner surface and the roll outer surface, and the thermal elongation of the inner diameter as time elapses, respectively, with the horizontal axis showing elapsed time (minutes) and the vertical axis showing the thermal elongation (mm) of the inner diameter and the temperature difference or temperature (deg.c). And, the hatched portion represents the elapsed time period when the desired thermal elongation, i.e., 0.2mm, is reached. The respective temperatures and elapsed times show the influence on the temperature increase rate of the heater 31, and an example of the present embodiment is shown.

Fig. 7 shows the case where the heater 31 is warmed up at a warming-up rate of 10 ℃/30 minutes, with a solid line 71 representing the heater temperature, a solid line 72 representing the roll inner surface temperature, a solid line 73 representing the temperature difference between the roll inner surface and the roll outer surface, and a solid line 74 representing the measured value of the thermal elongation of the roll inner diameter.

As shown in fig. 7, when the temperature rising speed of the heater 31 is relatively slow, the roll inner surface temperature needs to be heated to about 40 to 45 ℃ and the time also needs to be about 115 to 120 minutes in order to obtain the required thermal elongation. On the other hand, the temperature difference between the outer surface of the roll and the inner surface of the roll is relatively small, about 20 ℃ to 25 ℃, so that the temperature of the entire roll portion 24 can be relatively uniformly raised.

Fig. 8 shows the case where the heater 31 is heated at a heating rate of 50 c/30 minutes, the broken line 81 indicates the heater temperature, the broken line 82 indicates the roll inner surface temperature, the broken line 83 indicates the temperature difference between the roll inner surface and the roll outer surface, and the broken line 84 indicates the measured value of the thermal elongation of the roll inner diameter.

As shown in fig. 8, when the temperature rising speed of the heater 31 is relatively fast, the temperature of the roller inner surface starts almost without temperature rise at the beginning of heating, and the temperature rise starts after about 20 minutes has elapsed (refer to a broken line 82). This is because the outer peripheral surface of the roller portion 24 thermally expands as heating is performed, and the thermal contact state between the heater 31 and the outer peripheral surface of the roller portion 24 is improved.

The thermal elongation of the inner diameter of the roller portion 24, including when the desired thermal elongation (0.2mm) after about 30 minutes to about 35 minutes has elapsed, is increased in a manner proportional to the passage of time. In contrast, as described above, the temperature of the inner surface of the roller hardly rises during the period from the start of heating to about 20 minutes. Thus, when the desired amount of thermal elongation is reached, the roll inner surface temperature is about 30 ℃ to 35 ℃. As such, the desired amount of thermal elongation is achieved because the roll inner surface is subjected to tensile stress caused by thermal expansion (thermal elongation) of the roll outer surface, despite the relatively low temperature of the roll inner surface.

When the heater 31 is heated at a heating rate of 50 ℃/30 minutes in this manner, the required thermal elongation is achieved in a state where the roll inner surface temperature is relatively low. From this, it was found that, as described above, a tensile force caused by thermal elongation of the outer surface of the roll started to be generated on the inner surface of the roll.

And, when the desired thermal elongation (0.2mm) is reached, a temperature difference of about 50 ℃ to 55 ℃ is produced between the roll inner surface and the roll outer surface. Thus, it is considered that the compressive stress to the solidified portion 26 provided on the outer circumferential surface of the roller starts to increase.

Fig. 9 shows a case where the heater 31 is heated at a heating rate of 90 ℃/30 minutes, the one-dot chain line 91 indicates the heater temperature, the one-dot chain line 92 indicates the roll inner surface temperature, the one-dot chain line 93 indicates the temperature difference between the roll inner surface and the roll outer surface, and the one-dot chain line 94 indicates the measured value of the thermal elongation of the roll inner diameter.

As shown in fig. 9, when the temperature rising speed of the heater 31 is much faster than the example of fig. 8, the temperature of the roll inner surface rises almost without temperature rise at the beginning of heating, and after about 20 minutes, the temperature rises sharply (refer to the one-dot chain line 92), at which time the desired thermal elongation (0.2mm) has been reached, and thus it becomes substantially difficult to control the temperature rising time. As in the example of fig. 8, the reason why the temperature sharply rises is that the outer peripheral surface of the roller portion 24 thermally expands as heating progresses, and the thermal contact state between the heater 31 and the outer peripheral surface of the roller portion 24 increases. The thermal elongation of the inner diameter of the roller portion 24 reaches the required thermal elongation (0.2mm) after about 15 to about 20 minutes, and the temperature of the roller inner surface at this time is about 25 to 30 ℃ which is almost unchanged from the start of heating.

Thus, although the temperature of the roll inner surface is hardly changed, the desired amount of thermal elongation is achieved because the roll inner surface is strongly subjected to tensile stress caused by thermal expansion (thermal elongation) of the roll outer surface. Therefore, stress σ o in the radial direction exceeding the crack limit may occur in the roller portion 24 (particularly in the base portion 25) (in the present embodiment, it is assumed that about 40N/mm is present as an internal crack²) There is a possibility that minute cracks may be generated in the roller portion 24 (particularly, on the outer peripheral side of the base portion 25).

The temperature rise of the inner surface of the roll stays at about 1 to 5 ℃, whereas the temperature difference between the inner surface of the roll and the outer surface of the roll is about 50 to 55 ℃. Thus, it is considered that the compressive stress to the solidified portion 26 provided on the outer circumferential surface of the roller starts to increase further.

When the temperature of the heater 31 is raised at the temperature raising rate of 90 ℃/30 minutes in this manner, the risk of local damage to the roller portion 24 is increased due to an increase in stress to the solidified portion 26 and an increase in stress to the roller portion 24 (particularly, the outer peripheral side of the base portion 25).

Further, compared to the other cases (examples shown in fig. 7 and 8), more electric power is required to be supplied to the heater 31, and a large-sized power supply and equipment are required. In the present embodiment, when the temperature of the heater 31 is to be raised at a rate of 90 ℃/30 minutes, a large power supply of, for example, 200V or 40A is required, and when the thermal press-fitting operation of the rolls is to be performed on site where the crusher 1 is present, the power supply capacity corresponding thereto is at the upper limit. Therefore, a high-speed temperature rise above this is not realistic.

As described above, as is clear from fig. 7 to 9, if the temperature increase rate of the heater 31 is increased, the necessary thermal elongation is obtained in a short time, but the risk of damaging the roller portion 24 increases.

The relationship between the temperature increase rate of the heater 31 and the risk of damage (particularly, the state of generation of tensile stress generated on the inner surface side of the roller due to thermal expansion (thermal elongation) on the outer surface side of the roller) will be described in more detail.

As described above, in the present embodiment, since the heating of the roller portion 24 is performed only from the outer peripheral surface side, when the thermal elongation (0.2mm) necessary for the thermal compression fitting is reached, "the roller outer surface temperature > the roller inner surface temperature" is reached, and the roller inner surface is in a state of being subjected to the tensile stress due to the thermal expansion (thermal elongation) of the roller outer surface.

Table 1 below shows the state of occurrence of tensile stress in the roll inner surface due to thermal expansion (thermal elongation) of the roll outer surface, the temperature of the roll inner surface, the heater temperature, the reaching time, the thermal elongation caused by the roll inner surface temperature, and the thermal elongation when the required thermal elongation is reached, in accordance with the temperature increase rate of the heater 31. In the present embodiment, as described above, the crack critical radial direction stress σ o is set to about 40N/mm². The Young's modulus E of the material of the base 25 of the roller portion 24 is set to 1.8 to 2.0 x 10⁵N/mm²Setting the linear expansion coefficient to 11X 10^－6～12×10^－6And the amount of thermal elongation caused by the roll inner surface temperature is calculated.

[ Table 1]

As is apparent from Table 1, when the temperature raising rate was 30 ℃/30 minutes to 90 ℃/30 minutes, the thermal elongation at the roll inner surface temperature reached 0.2mm, which is the desired thermal elongation, was 0.2mm or less. That is, a value obtained by subtracting the amount of thermal elongation caused by the roll inner surface temperature from 0.2mm is a length of the roll inner surface elongation due to the elongation caused by the thermal expansion (thermal elongation) of the roll outer surface.

Therefore, it is understood that, when the temperature increase rate is 30 ℃/30 minutes to 90 ℃/30 minutes, the roll inner surface is stretched by thermal expansion (thermal elongation) of the roll outer surface and the roll inner surface is in a state of being subjected to tensile stress, but the higher the temperature increase rate is, the longer the length of the roll inner surface stretched by the stretching becomes. That is, it is found that the higher the temperature increase rate is, the higher the tensile stress applied to the inner surface of the roll becomes.

The tensile stress generated in the inner surface of the roller at each temperature increase rate is generated as follows. When the temperature rising speed is 30 ℃/30 minutes and 50 ℃/30 minutes, the generated tensile stress does not reach the crack limiting radial direction stress sigma o. And when the temperature rise speed is 60 ℃/30 minutes, the generated tensile stress does not reach the crack ultimate radial stress σ o, and the tensile stress of about 80% of the crack ultimate radial stress σ o is generated. And when the temperature rise rate is 90 ℃/30 minutes, the generated tensile stress becomes a value slightly smaller than the crack limit radial direction stress σ o.

In view of the above results, when the temperature rising rate is 90 ℃/30 minutes, it may result in that the tensile stress generated in the roll inner surface exceeds the crack limit radial direction stress σ o, and thus the risk of damaging the roll portion 24 is considered to increase. Therefore, it is found that the upper limit of the temperature increase rate of the heater 31 is preferably set to about 60 ℃/30 minutes (i.e., 2 ℃/min).

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

As is clear from Table 1, when the temperature increase rate is lowered, the time required for the thermal elongation to reach the required thermal elongation (0.2mm) becomes longer.

The mill roller 5 may be replaced for the purpose of maintenance of the mill roller 5 and the like. In order to install the replacement mill roller 5, it is necessary to temporarily install a replacement roller portion, a heating step of heating the roller portion 24, a fitting step of fitting the roller portion 24 to the journal housing 23, and an installation step of installing the mill roller 5 in which the roller portion 24 is fitted to the journal housing 23 in the mill 1.

In the present embodiment, the time required for each step is, for example, as follows. The required time in the following description is merely an example, and the required time may be other times.

The temporary setting step requires about 5 minutes, the fitting step requires about 10 minutes, and the setting step requires about 25 minutes. That is, it takes about 40 minutes in total in the steps other than the heating step. Therefore, if the time of the heating step is Ht, the time required to replace 1 pulverizing roller 5 is Ht +40 (minutes).

Next, a time suitable for replacing 1 pulverizing roller 5 is set as follows.

When replacing the mill 1 provided with 3 mill rollers 5 for 2 mills (6 mill rollers 5) in a day as in the present embodiment, the operating time for 1 mill roller 5 of 100 minutes is obtained from the following equation (3) when the operating time for one day is 10 hours.

(10 × 60) minutes per 3 × 2 stands

Therefore, as is apparent from the following formula (4), the time Ht required in the heating step is preferably 60 minutes or less.

(4) Ht +40 min is less than or equal to 100 min

In view of the above results, it is understood from Table 1 that the lower limit of the temperature increase rate of the heater 31 is preferably set to about 30 ℃/30 minutes (i.e., 1 ℃/min).

As described above, in the present embodiment, the lower limit of the temperature increase rate of the heater 31 is set to 1 ℃/min from the viewpoint of operability, and the upper limit of the temperature increase rate of the heater 31 is set to 2 ℃/min from the viewpoint of the risk of damaging the pulverizing roller 5.

This will be described with reference to fig. 10. In FIG. 10, the relationship between the temperature increase rate (. degree.C./min) of the heater 31 and the time (minutes) for the desired thermal elongation (0.2mm) to reach is shown by a broken line, and the relationship between the temperature increase rate (. degree.C./min) of the heater 31 and the roll inner surface temperature (. degree.C.) is shown by a solid line.

As shown by the broken line in fig. 10, when the temperature increase rate of the heater 31 is 2 ℃/min or more, the roll inner surface temperature at the time of reaching the required thermal elongation becomes low, and the risk of damage increases, which is not preferable. Further, when the temperature increase rate of the heater 31 is 1 ℃/min or less, the time required for the heating step is 60 minutes or more, which is not preferable because the workability is deteriorated. Therefore, the range shown by the arrow in the shaded portion of FIG. 10, i.e., 1 ℃/min to 2 ℃/min, becomes a preferable range. Particularly, from the viewpoint of both the risk of damage and the ease of handling, a temperature rise rate of 50 ℃/30 minutes as indicated by P in fig. 10 is preferable.

Further, at a temperature rise rate of more than 3 ℃/min, the amount of thermal elongation becomes necessary before the temperature of the roll inner surface rises, and therefore, it is difficult to control the amount of thermal elongation, which is not preferable.

According to the present embodiment, the following operational 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 opened to the outside air. Therefore, the outer peripheral surface side of the base portion 25 is heated more quickly than the inner peripheral surface side, and becomes a higher temperature than the inner peripheral surface side. Thereby, the base portion 25 thermally expands outward in the radial direction (i.e., so that the external strain is large). On the other hand, since the cured portion 26 has a thermal expansion coefficient different from that of the base portion 25 and a member having a small thermal expansion coefficient, for example, ceramic may be included in the cured portion 26, the thermal expansion amount is smaller than that of the base portion 25 or the thermal expansion amount is larger because the cured portion 26 has a higher temperature than that of the base portion 25. Therefore, when the roller portion 24 thermally expands outward in the radial direction, the solidified portion 26 is restrained by the base portion 25 and a pressing force acts in the radial direction. Therefore, a compressive stress in the radial direction is generated in the cured portion 26. In this way, in the heating step of heating the roll portion 24, the stress generated in the cured portion 26 can be regarded mainly as compressive stress, and therefore, the tensile stress generated in the cured portion 26 is suppressed, and cracks can be made less likely to propagate to the cured portion 26. Therefore, the cured portion 26 can be made less likely to be damaged.

In this way, the roller portion 24 and the journal housing 23 can be fitted together by shrink fitting. Therefore, even in the mill roller 5 having the hardened portion 26 on the outer peripheral surface without performing the clearance fit, the mill roller 5 can be manufactured by fitting the roller portion 24 and the journal housing 23 by the hot press fit without performing special processing such as mounting processing of a fixing member other than dimensional control of the fitting portion on the roller portion 24 and the journal housing 23. Therefore, the cost can be reduced and the time required for manufacturing can be shortened as compared with a method of performing special processing on the roller section 24 and the journal housing 23.

The roller portion 24 is heated from the outer peripheral surface side in a state where the central axis C1 of the roller portion 24 is oriented in a direction perpendicular to the ground and the inner peripheral surface is open to the outside air (in other words, in a state where the atmosphere is open). As a result, the air in the annular inner space is heated to increase in temperature, and is released into the atmosphere as an updraft by the chimney effect as shown by the arrows in fig. 4. Therefore, since the air whose temperature is raised in the inner space does not stagnate, the temperature distribution of the inner peripheral surface of the roller portion 24 is suppressed to be small, and the occurrence of uneven stress in the entire roller portion 24 can be suppressed. Therefore, the roller portion 24 can be made less likely to be damaged. Examples of the damage of the roller portion 24 include the occurrence of local micro cracks, the propagation of internal cracks, and partial falling.

In the present embodiment, the lower space formed between the roller portion 24 and the ground communicates with the inside space. As a result, air flows in from below the inner space through the lower space, and thus the chimney effect is more effectively exhibited, and an updraft can be reliably generated in the inner space. Therefore, the temperature distribution of the inner circumferential surface of the roller is more appropriately suppressed, and the generation of uneven stress in the entire roller portion 24 can be suppressed.

In the step of heating the roller portion 24, the inner peripheral surface of the roller portion 24 is open to the outside air, and therefore, in the heating step, the inner peripheral surface of the roller portion 24 can be brought into contact therewith. In this way, in the heating step, the thermal elongation of the inner diameter of the roller portion 24 can be measured by a vernier caliper, a laser distance meter, or the like. Therefore, the heating can be performed while checking the thermal elongation of the inner diameter of the roller portion 24, and thus a desired thermal elongation can be reliably set. Therefore, since the thermal elongation is continuously checked, the heating process can be terminated at a timing at which the thermal elongation is desired, and thus occurrence of unnecessary time due to overheating or the like can be prevented, and the heating process can be rationalized. When a desired thermal elongation of the inner diameter of the roller portion 24 is obtained, the heating process may be managed by the heating elapsed time by confirming the relationship between the heating elapsed time and the time when the heater 31 is set to the predetermined temperature increase rate through experiments in advance.

In the present embodiment, since the outer peripheral surface of the roller portion 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 insulating material 29, the heat dissipation from the heater 31 is reduced, and the heat flux from the heater 31 toward the roller portion 24 can be stabilized. Therefore, the distribution of the heat transfer amount from the heater 31 to the outer peripheral surface of the roller portion 24 can be suppressed to be uniform.

Further, since the inner peripheral surface of the roller portion 24 is in an open state (i.e., on the low temperature side), the heat input from the outer peripheral surface side is likely to move toward the inner peripheral surface side. In this way, the direction of the heat flux toward the inner peripheral surface side can be specified, and therefore, the temperature rise on the inner peripheral surface side of the roller portion 24 can be stabilized.

It takes a predetermined time for the heat input from the outer peripheral surface to be transferred to the inner peripheral surface. Therefore, when the roller portion 24 is heated from the outer peripheral surface by the heater 31, a temperature difference is generated between the outer peripheral surface and the inner peripheral surface. In the present embodiment, the roller portion 24 is heated while raising the temperature of the heater 31 from a room temperature state at a predetermined temperature raising rate. Thereby, the outer circumferential surface and the inner circumferential surface of the roller portion 24 are also heated so as to follow the temperature rise of the heater 31. Therefore, the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller portion 24 is smaller than that in the method of heating while keeping the temperature of the outer peripheral surface of the roller portion 24 constant by the heater 31 for keeping the temperature constant. Therefore, the stress generated in the cured portion 26 provided on the outer peripheral surface side of the roller portion 24 can be reduced. Therefore, the roller portion 24 can be made less likely to be damaged.

If the temperature increase rate of the heater 31 is slowed, the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller portion 24 can be sufficiently reduced, and the roller portion 24 can be made less likely to be damaged, but it takes time to obtain the thermal elongation necessary for the thermal compression-fitting of the roller portion 24 and the journal housing 23, which results in an increase in the heating process and a reduction in the workability. On the other hand, if the temperature increase rate of the heater 31 is increased, the heating process can be shortened, but the temperature difference between the inner circumferential surface and the outer circumferential surface of the roller portion 24 cannot be sufficiently reduced, and the possibility of damage occurring to the roller portion 24 increases.

In the present embodiment, the temperature of the heater 31 is raised at a temperature raising rate of 1 ℃/min to 2 ℃/min. By setting the temperature increase rate to 2 ℃/min or less in this way, the temperature difference between the inner peripheral surface and the outer peripheral surface of the roller portion 24 can be sufficiently reduced, whereby the roller portion 24 can be made less susceptible to damage, and by setting the temperature increase rate to 1 ℃/min or more, excessive lengthening of the heating step can be prevented, and the workability can be improved.

In the present embodiment, a plurality of heaters 31 covering the outer peripheral surface of the roller portion 24 are arranged in a row, and the temperature increase rate is controlled by different power supply control portions 32. Accordingly, by appropriately controlling the temperature increase rate of each heater 31 individually, the occurrence of the temperature distribution on the outer peripheral surface of the roller portion 24 can be suppressed. Since the heat input from the outer peripheral surface can be made uniform by suppressing the occurrence of the temperature distribution of the outer peripheral surface, the temperature distribution of the inner peripheral surface of the roller portion 24 can be suppressed.

Further, since the plurality of heaters 31 covering the outer peripheral surface of the roller portion 24 are arranged in a row so as to increase the heat generation density, the heaters 31 can be downsized. This can reduce the temperature distribution in each heater 31, and thus can suppress the occurrence of the temperature distribution on the outer peripheral surface of the roller portion 24.

[ modification 1]

Modification 1 of the present embodiment will be described.

In the present modification, the heating of the roller portion 24 is performed in a state where the metal foil is provided between the outer peripheral surface of the roller portion 24 and the heater 31, which is different from the above embodiment. The metal foil is preferably a metal foil that is easily deformed and has good thermal conductivity, and is preferably an aluminum foil, for example. Further, copper foil or the like may be used.

It was confirmed that in the state of thermal close contact of the heater 31 to the outer peripheral surface of the roller portion 24, the heat flux from the heater 31 to the roller portion 24 largely changed and the temperature increasing state of the roller inner surface changed.

In the heating step, at least the heater 31 is fixed to the outer peripheral surface of the roller portion 24 by tightening a plurality of portions of the outer peripheral surface in the vertical direction with a wire rope or the like without loosening the outer peripheral surface of the roller portion 24 (hereinafter, referred to as "normal fixed state"). The heater 31 is preferably provided to be in close contact with the outer peripheral surface of the roller portion 24 uniformly, but it is estimated that the thermal contact state is not always sufficient at the time of starting heating, and the thermal conductivity from the heater 31 to the roller portion 24 is about 1/2 to 1/10 compared with the case where the heater 31 is completely in thermal contact.

That is, the heater 31 closely contacts the roll outer surface and the thermal conductivity is increased by, for example, 5 times, whereby the temperature rise of the roll inner surface is accelerated by about 20% and the temperature difference between the roll outer surface and the roll inner surface is reduced by about 20%.

This can be judged from fig. 11 and 12.

Fig. 11 shows the relationship between elapsed time (minutes) and heater temperature (deg.c) or roll inner surface temperature (deg.c). In fig. 11, a solid line 111 indicates the heater temperature at the time of temperature increase at a temperature increase rate of 10 ℃/30 minutes, a broken line 112 indicates the heater temperature at the time of temperature increase at a temperature increase rate of 50 ℃/30 minutes, a solid line 113 indicates the roll inner surface temperature at the time of temperature increase at a temperature increase rate of 10 ℃/30 minutes in a normally fixed state, a broken line 114 indicates the roll inner surface temperature at the time of temperature increase at a temperature increase rate of 50 ℃/30 minutes in a normally fixed state, and a two-dot chain line 115 indicates the roll inner surface temperature at the time of temperature increase at a temperature increase rate of 50 ℃/30 minutes in a close contact state in which the heater 31 and the roll portion 24 are brought into close contact with each other with heat.

Comparing the broken line 114 with the two-dot chain line 115, it is understood that even with the same elapsed time, when the heater 31 and the roller portion 24 are in a close contact state in which the thermal close contact state is improved, the roller inner surface temperature becomes higher than that in the case of the normal fixed state (see the arrow in fig. 11).

Fig. 12 shows the relationship between elapsed time (minutes) and heater temperature (deg.c) or the temperature difference Δ T (deg.c) between the roll outer surface temperature and the roll inner surface temperature. In fig. 12, a broken line 121 indicates a heater temperature when the temperature is raised at a temperature raising rate of 50 ℃/30 minutes, a broken line 122 indicates a temperature difference between a roll outer surface temperature and a roll inner surface temperature when the temperature is raised at a temperature raising rate of 50 ℃/30 minutes in a normally fixed state, and a two-dot chain line 123 indicates a temperature difference between a roll outer surface temperature and a roll inner surface temperature when the temperature is raised at a temperature raising rate of 50 ℃/30 minutes in a close contact state in which the heater 31 and the roll portion 24 are brought into high thermal contact with each other.

Comparing the broken line 122 with the two-dot chain line 123, it is understood that even with the same elapsed time, when the heater 31 and the roller portion 24 are in close contact with each other with the heat contact state improved, the temperature difference between the roller outer surface temperature and the roller inner surface temperature becomes smaller than that in the case of the normal fixed state (see the arrow in fig. 12).

In this modification, the following operational effects are exhibited.

In the present modification, a metal foil is provided between the roller portion 24 and the heater 31. Since the metal foil is easily deformed, 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 is in close contact with the roller portion 24 and the heater 31. By providing the metal foil between the roller portion 24 and the heater 31 in this manner, the gap formed between the roller portion 24 and the heater 31 can be filled with the metal foil.

Since the metal foil has good thermal conductivity, the gap formed between the roller portion 24 and the heater 31 is filled with the metal foil, thereby increasing the thermal conductivity between the roller portion 24 and the heater 31. This can increase the heat flux from the heater 31 to the roller portion 24. Therefore, the heat of the heater 31 is easily transmitted to the inner circumferential surface of the roller portion 24, and therefore the temperature of the inner circumferential surface can be appropriately increased. Therefore, the temperature distribution of the inner peripheral surface of the roller portion 24 is suppressed, and the generation of uneven stress in the entire roller portion 24 can be suppressed. Therefore, the roller portion 24 can be made less likely to be damaged.

[ modification 2]

Next, modification 2 of the present embodiment will be described.

In the present modification, the measurement data collected in the heating step and the fitting step of the roller portion 24 is accumulated in the database in accordance with the conditions of the plurality of predetermined heater temperature increase rates and the configuration of the plurality of roller portions 24, and a data table is constructed. Data on the structure of the roller section 24 with respect to the rate of temperature rise of the heater, the temperature of each part of the roller section 24 by heating, and the measured value of the thermal elongation of the inner diameter of the roller are accumulated in advance to create a table based on a database. That is, the control device (not shown) stores the temperature increase rate of the heater 31 and the thermal elongation of the roller section 24 in the heating step (temperature increase rate storage step, thermal elongation storage step), creates a table defining the relationship between the temperature increase rate and the thermal elongation based on the stored temperature increase rate and thermal elongation (table creation step), and stores the table.

Here, a preliminary heating test in which the roller portion 24 is subjected to the heating step at the temporary temperature increase rate in the field where the pulverizer 1 is present is performed. This makes it possible to select an appropriate temperature increase rate for the heating process of the roller and perform heating within an appropriate range of the heating condition of the roller section 24.

The preliminary heating test is a test in which, for example, the roller portion 24 is preliminarily heated for about 10 minutes at a predetermined temperature increase rate, the data on the correlation between the thermal elongation and the temperature increase rate (for example, 1 to 2 conditions) with the passage of time is extracted, and the appropriate temperature increase rate is determined and selected by comparing the data with a stored database (table). In the heating step, the roller section 24 may be preliminarily heated at the temporary temperature increase rate, and the roller section 24 may be heated at the temperature increase rate determined from the temporary temperature increase rate, the thermal elongation of the roller section 24 during preliminary heating, and the table.

The selected temperature increase rate is preferably because stress generated in the hardened portion 26 provided on the outer circumferential surface of the roll can be suppressed and local damage can be suppressed because it can be considered as a condition that the temperature difference between the roll inner surface and the roll outer surface due to a sharp temperature gradient does not increase.

According to this modification, the following operational effects are exhibited.

In the present modification, an appropriate temperature increase rate of the heating process of the roller portion 24 is selected in advance by the preliminary heating test, and heating is performed within a range of an appropriate heating condition of the roller portion 24, so that stress generated in the cured portion 26 provided on the outer peripheral surface of the roller is suppressed, local damage is suppressed, and the operating time in the heating step can be shortened.

In the present modification, although the example in which the heating conditions are specified based on the table based on the database has been described, the AI system may be constructed so that the appropriate range of the heating conditions for the sizes of the various rolls can be determined as the data of the heating conditions are accumulated, and the heating conditions such as the appropriate temperature increase rate and the standard heating temperature may be specified by the AI system.

[ modification 3]

Next, modification 3 of the present embodiment will be described.

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

In the present modification, as shown in fig. 13, the heater 31 is heated at a heating rate of 1 ℃/min (1 st heating rate) for a predetermined time (ten minutes in the present embodiment) from the start of heating to heat the outer peripheral surface of the roller section 24 (1 st heating step), and after the predetermined time has elapsed, the heater 31 is heated at a heating rate of 2 ℃/min (2 nd heating rate) to heat the outer peripheral surface of the roller section 24 (2 nd heating step).

The change in the temperature difference between the inner surface of the roll and the outer surface of the roll when the temperature increase rate is changed will be described with reference to fig. 13. Fig. 13 is a graph showing changes with time of the temperature of the heater 31, the temperature of the roll inner surface, and the temperature difference Δ T between the roll inner surface and the roll outer surface, in which the horizontal axis shows elapsed time (minutes) and the vertical axis shows the temperature difference (Δ T) or temperature (deg.c). And, the hatched portion represents the elapsed time period when the desired thermal elongation, i.e., 0.2mm, is reached.

The broken line 131 in fig. 13 indicates the heater temperature when the temperature is raised at a rate of 50 ℃/30 minutes. Also, a solid line 132 indicates the heater temperature when the temperature increase rate is changed. The dotted line 133 indicates the roll inner surface temperature when the temperature is raised at a rate of 50 ℃ for 30 minutes. Also, a solid line 134 indicates the roll inner surface temperature when the temperature increase rate is changed. The dotted line 135 indicates the temperature difference between the inner surface and the outer surface of the roll when the temperature is raised at a temperature raising rate of 50 ℃ for 30 minutes. Also, the solid line 136 represents the temperature difference between the roll inner surface and the roll outer surface when the temperature increase rate is changed.

Comparing the broken line 133 with the solid line 134, it is understood that the roll inner surface temperature when the temperature rise rate is 50 ℃/30 minutes is almost the same as the roll inner surface temperature when the temperature rise rate is changed. Further, by comparing the broken line 135 with the solid line 136, it is understood that the temperature difference between the roll inner surface and the roll outer surface is reduced when the temperature increase rate is changed within a predetermined time period from the start time of heating, as compared with the case where the temperature is increased at the temperature increase rate of 50 ℃/30 minutes. Further, when the desired thermal elongation is reached, the temperature difference between the roll inner surface and the roll outer surface is reduced by about 5 ℃ more in the case of changing the temperature increase rate than in the case of increasing the temperature at a temperature increase rate of 50 ℃/30 minutes.

As described above, by raising the temperature of the heater 31 at the rate of temperature rise of 1 ℃/min only for a predetermined time (ten minutes in the present embodiment) from the start time of heating, it is possible to suppress an increase in the temperature difference between the roll inner surface and the roll outer surface due to the occurrence of a sharp temperature gradient on the roll outer surface side. Then, the heater 31 is heated at a heating rate of 2 ℃/min to heat the outer peripheral surface of the roller section 24, thereby obtaining a desired thermal elongation (0.2mm), and thereby reducing the temperature difference between the roller inner surface and the roller outer surface, and suppressing the generation of stress in the solidification section 26 by the pulverization roller 5. Therefore, the roller portion 24 can be made less likely to be damaged. Further, since the inner surface temperature of the roll hardly changes when the temperature increase rate is 50 ℃/30 minutes or when the temperature increase rate is changed, the operation time of the heating step does not increase even when the temperature increase rate is changed.

According to this modification, the following operational effects are exhibited.

It is possible to suppress an increase in the temperature difference between the outer peripheral surface and the inner peripheral surface of the roller portion 24 due to a rapid temperature increase in the outer peripheral surface of the roller portion 24 accompanying the start of heating, and to reduce the stress generated in the cured portion 26 provided on the outer peripheral surface of the roller portion 24. Therefore, the roller portion 24 can be made less likely to be damaged.

The predetermined time for changing the temperature increase rate is not limited to the above description. The predetermined time may be about 1/3 to 1/2, which is a time required to heat the temperature of the outer peripheral surface of the roller to a temperature (for example, about 30 to 50 ℃) at which a desired thermal elongation (0.2mm) can be obtained or more at a higher temperature rise rate than the temperature rise rate before the change and the temperature rise rate after the change.

Further, a predetermined time may be set in advance, and the temperature increase rate may be set in accordance with the predetermined time.

The present invention is not limited to the invention according to the above-described embodiment, and can be modified as appropriate without departing from the scope of the invention.

For example, the modifications may be combined.

For example, in the above embodiment, the roller portion 24 having the outer diameter L1 of about 1.5m and the inner diameter L4 of about 1.1m was described, but the present invention is not limited thereto. The roller portion 24 having an inner diameter of about 0.5m to about 1.8m can be appropriately heated.

Description of the symbols

1-pulverizer, 2-housing, 2 a-side, 2 b-top, 2 c-bottom, 3-air supply conduit, 4-pulverizing table, 5-pulverizing roller, 7-fuel supply pipe, 8-rotary classifier, 9-outlet port, 15-rotary support, 16-table, 17-journal, 18-journal head, 19-eccentric shaft, 20-pressing device, 21-stopper, 23-journal housing (support), 24-roller, 25-base, 26-solidification, 27-insulating brick, 29-insulating material, 30-temperature raising device, 31-heater, 32-power supply control, 33-power supply, 34-temperature measuring instrument.

Claims (13)

1. A method for manufacturing a crushing roller, wherein,

the pulverization roller is provided with: a support portion for supporting a crusher for crushing a material to be crushed in a rotatable manner in a housing of the crusher; and an annular roller portion having an annular base portion and a solidified portion provided on an outer peripheral surface of the base portion in a radial direction and having a thermal expansion coefficient different from that of the base portion, the method for manufacturing the pulverization roller including:

a heating step of heating the roller portion from the outer circumferential surface side in the radial direction of the roller portion in a state where the central axis of the roller portion is in a direction orthogonal to the ground and the inner circumferential surface in the radial direction of the roller portion is open to the outside air;

a placement step of placing the support portion and the roller portion in a state in which the temperature is increased in the heating step such that the inner peripheral surface of the roller portion faces or contacts the outer peripheral surface of the support portion; and

and a fitting step of cooling the roller portion disposed in the disposing step to fit the support portion and the roller portion.

2. The method of manufacturing a pulverizing roller as defined in claim 1,

at least a portion of the cured portion includes a member having a coefficient of thermal expansion less than that of the base portion.

3. The method of manufacturing a pulverizing roller according to claim 1 or 2, wherein,

in the heating step, a lower space is formed between the roller portion and the floor surface, and the roller portion is heated in a state where the lower space communicates with an inner space formed inside the inner circumferential surface of the roller portion.

4. The method of manufacturing a pulverizing roller according to any one of claims 1 to 3,

in the heating step, the roller portion is heated by raising the temperature of the heater in a state where the outer peripheral surface of the roller portion in the radial direction is covered with the heater and the outer peripheral surface of the heater in the radial direction is covered with the insulating material.

5. The method of manufacturing a pulverizing roller as defined in claim 4,

in the heating step, the roller portion is heated while the heater is heated at a predetermined temperature increase rate from a room temperature state.

6. The method of manufacturing a pulverizing roller as defined in claim 5,

the predetermined temperature rise rate is 1 ℃/min to 2 ℃/min.

7. The method of manufacturing a pulverizing roller according to any one of claims 4 to 6,

in the heating step, a metal foil is provided between the roller portion and the heater.

8. The method of manufacturing a pulverizing roller according to any one of claims 4 to 7,

the heating step includes: a 1 st heating step of heating the roller portion by raising the temperature of the heater at a 1 st temperature raising rate until a predetermined time elapses from a heating start time; and a 2 nd heating step of heating the roller portion by raising the temperature of the heater at a 2 nd temperature raising rate faster than the 1 st temperature raising rate after the 1 st heating step.

9. The method of manufacturing a pulverizing roller according to any one of claims 4 to 8,

a plurality of the heaters are provided and,

the plurality of heaters are arranged in a circumferential direction so as to be arranged along the outer circumferential surface of the roller portion, and the temperature increase rates are controlled by different temperature increase rate control portions, respectively.

10. The method of manufacturing the pulverizing roller as claimed in any one of claims 5 to 9, comprising:

a temperature increase rate storage step of storing the temperature increase rate of the heater in the heating step;

a thermal elongation storage step of storing the thermal elongation of the roller portion in the heating step; and

a table creating step of creating a table defining a relationship between the temperature increase rate and the thermal elongation based on the temperature increase rate stored in the temperature increase rate storage step and the thermal elongation stored in the thermal elongation storage step,

in the heating step, the roller portion is preliminarily heated at a temporary temperature increase rate, and the roller portion is heated at a temperature increase rate determined from the temporary temperature increase rate, the thermal elongation of the roller portion in the preliminary heating, and the table.

11. A temperature raising device for use in a crusher for crushing an object to be crushed, the temperature raising device raising a temperature of an annular roller portion having an annular base portion and a curing portion provided on an outer peripheral surface of the base portion in a radial direction and having a thermal expansion coefficient different from that of the base portion, the temperature raising device comprising:

a heater provided so as to cover an outer circumferential surface of the roller portion in a radial direction; and

a temperature rise rate control unit for controlling the temperature rise rate of the heater,

the temperature rise rate control unit controls the heater so that the temperature rise rate is 1 ℃/min or more and 2 ℃/min or less.

12. The temperature increasing apparatus according to claim 11,

the heater is disposed in a state in which a central axis thereof is perpendicular to the ground, and is provided to the roller portion disposed in a state in which an inner circumferential surface of the roller portion in a radial direction is open to the outside air.

13. The temperature increasing apparatus according to claim 11 or 12,

a plurality of the heaters are provided and,

a plurality of the temperature increase rate control units are provided,

the plurality of heaters are arranged in a circumferential direction so as to be aligned along the outer circumferential surface of the roller portion in the radial direction, and the temperature increase rates are controlled by the different temperature increase rate control portions, respectively.

Images