JP5979613B2 - Rotating body - Google Patents

Description

  The present invention relates to a rotating body made of ceramics, and more particularly to a high temperature resistant rotating body suitably used for conveying and supporting a steel plate in a steel plate rolling line.

  Many steel furnaces, soaking furnaces, and heat treatment furnaces are provided at steelworks to maintain steel plates, billets, and other materials at high temperatures and for heat treatment. In these furnaces, the material is mainly transported on a transport roll. In recent years, studies have been made to use transport rolls made of ceramics for the purpose of achieving high-temperature treatment, uniformity during heating or soaking, energy saving, and improvement of wear resistance. Conventionally known rolls made of this ceramic have the following structure.

  Patent Document 1 discloses a roll that is used at a high temperature in which a ceramic sleeve is mounted on a metal roll shaft, and water is circulated in the roll shaft so that the roll shaft is water-cooled. A heat insulating material is disposed between the sleeves, and at least one of both ends of the sleeve is elastically pressed in the axial direction by a pressing material having the roll shaft as a seat, and substantially only by this pressing force. A high temperature resistant roll is disclosed which supports a load acting on the sleeve in a direction perpendicular to its outer surface. According to the roll of patent document 1, it is supposed that the high temperature resistant roll which is rich in durability, such as being able to prevent damage to the sleeve.

  In Patent Document 2, a metal fitting with a center hole is fitted or bonded to both ends of a solid ceramic mother body, a through hole for air venting is provided on the metal fitting, and one hole is fitted between the metal fitting and the ceramic mother body. There is disclosed a ceramic work roll used for rolling metal, which is provided in contact with the joint and provided with the other hole opened to the atmosphere. According to the ceramic work roll of Patent Document 2, the through hole functions so that excess air does not remain inside the fitting portion, and can be securely fitted or adhered by shrinkage fitting, and the center can be worn or worn. Alternatively, since the deterioration of the center axis accuracy due to the influence of the position of the through hole is suppressed, a ceramic work roll having improved roundness, cylindricity and the like is obtained.

  Patent Document 3 discloses a roll for a hot metal plating bath comprising a hollow body portion that comes into contact with a steel plate and a shaft portion joined to the body portion, wherein the body portion and the shaft portion are each formed of ceramics. The inner surface of the body portion is composed of a large-diameter region at both ends and a small-diameter region at the center, and the shaft portion has a small-diameter portion, a flange portion, and a large-diameter portion, and the large-diameter region of the trunk portion includes the A large-diameter portion of the shaft portion is joined, and a plurality of longitudinal grooves that pass through the large-diameter portion and the flange portion are formed in the shaft portion, and the shaft portion is at both ends of the body portion. A molten metal plating bath roll is disclosed in which the groove portion forms a hole communicating with the inside of the roll in a state where the groove portion is joined to the portion. According to the roll for a molten metal plating bath of Patent Document 3, since there are a plurality of holes communicating with the inside of the roll between the body portion and the shaft portion of the roll, when the roll is immersed in the molten metal plating bath, By quickly entering the roll and reducing the temperature difference between the inside and outside of the roll, the thermal shock is further suppressed, and when the roll is taken out from the molten metal plating bath, the molten metal can be quickly discharged from the roll. It is said that a large amount of molten metal can be prevented from solidifying. Moreover, even if it is immersed in the molten metal plating bath for a long time, the shaft portion is not detached from the body portion, and continuous molten metal plating can be performed for a long time.

Japanese Unexamined Patent Publication No. 64-55325 JP 2002-126807 A JP 2006-193814 A

  When the roll made of ceramics described in the above-mentioned patent document is applied in a high-temperature environment, for example, to transport or support a steel plate, there are the following problems.

  In the high temperature resistant roll described in Patent Document 1, a heat insulating material substantially made of ceramic fibers is interposed between a ceramic sleeve and a metal roll shaft. For this reason, the heat insulating material is deformed during use, the axis of the ceramic sleeve and the metal roll shaft are displaced, and vibration due to the vibration of the ceramic sleeve is generated, which is used as a rotating body for conveyance. In such a case, there is a problem that waviness and scratches are generated on the steel sheet to be conveyed. Also, since the metal roll shaft is long, bending of the roll shaft occurs due to repeated use, which also causes vibration due to the vibration of the ceramic sleeve, and undulations and scratches are generated on the conveyed steel sheet. Had the problem of occurring.

  The ceramic roll described in Patent Document 2 is substantially made of solid ceramics, and since the thickness of the roll body is increased, when used as a rotating body for conveyance, a heated steel plate and In some cases, the surface of the ceramic peels off due to a thermal shock at the time of contact, and the roll itself is damaged.

  The roll of Patent Document 3 is formed of a substantially hollow barrel portion and a hollow shaft portion, and the diameter of the hollow shaft portion is smaller than that of the hollow barrel portion, so that it was used as a rotating body for conveyance. In this case, the problem of thermal shock that occurs in the roll of Patent Document 2 can be solved by using a hollow cave. However, since the shaft portion is hollow, the strength is insufficient, and the shaft portion is damaged early.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a rotating body having durability while preventing problems such as breakage and vibration in a high temperature environment.

The present invention has the following configuration to solve the above problems.
The rotating body of the present invention is a rotating body having a hollow body made of ceramics and a solid shaft part made of ceramics fitted to the inner surfaces of both ends of the body part. The portions each have a fitting surface to be fitted in a close contact state, and an air hole extending along the rotation axis direction of the rotating body is formed in the fitting interface between the body portion and the shaft portion. And

  In the rotating body of the present invention, it is preferable that a cross-sectional area of the air hole in a cross section perpendicular to the rotation axis is 0.001 to 5% of a cross-sectional area of the shaft portion.

  In the rotating body of the present invention, it is preferable that a flat surface is formed on a part of the fitting surface of the shaft portion.

  In the rotating body of the present invention, the relationship between the fitting length L along the rotation axis direction of the fitting surface and the diameter D of the fitting surface of the shaft portion is preferably L / D = 0.5-2. .

  In the rotating body of the present invention, the shaft portion includes a bearing portion to be connected to a bearing, a flange portion connected to the bearing portion, a large diameter portion larger in diameter than the bearing portion connected to the flange portion, and the large diameter portion. It is preferable that it consists of a fitting part which has a fitting surface.

  In the rotating body of the present invention, it is preferable that each of the body portions is composed of a body member made of a plurality of ceramics, and the body members are fitted to each other.

  In the rotating body of the present invention, each of the body members has a fitting surface to be fitted in a close contact state, and is replaced with an air hole formed at a fitting interface between the body portion and the shaft portion. An air hole extending in the rotation axis direction of the rotating body may be formed in the fitting interface.

  In the rotating body of the present invention, it is preferable that the shaft portion has a bearing portion to be connected to a bearing, and a flat surface extending in the rotation axis direction is formed at an end portion of the bearing portion.

  In the rotating body according to the present invention, the body portion and the shaft portion are both made of silicon nitride ceramics, have a four-point bending strength of 500 MPa or more, a Vickers hardness of 1300 or more, a relative density of 95% or more, and a Young's modulus of 250 to 350 GPa. Preferably there is. In the rotating body made of the silicon nitride ceramic of the present invention, it is preferable that the thermal conductivity of the silicon nitride ceramic is 50 W / mK or more and the number of grain boundaries per 10 μm is 10 or less.

  The rotating body of the present invention can solve the above-described problems, prevent problems such as breakage and vibration in a high temperature environment, and provide a rotating body having durability. For this reason, it becomes possible to convey a steel plate stably over a long period of time.

FIG. 1A is a front view of a part of a rotary body according to an embodiment of the present invention, and FIG. 1B is a view of the rotary body in FIG. FIG. 2 (a) is a front view partially showing a cross section of a rotating body according to another embodiment of the present invention, and FIG. 2 (b) is a view as seen from an arrow B of the rotating body of FIG. 2 (a). is there. It is sectional drawing of a cross section perpendicular | vertical with respect to a rotating shaft in the fitting part of the rotary body by other one Embodiment of this invention. FIG. 4 (a) is a front view showing a part of a rotating body according to another embodiment of the present invention, and FIG. 4 (b) is a view taken along the arrow C of the rotating body in FIG. 4 (a). FIG. 4C is a plan view of the rotating body of FIG. 4A, and FIG. 4D is a view taken along the arrow D of the rotating body of FIG. It is a front view which shows the rotary body by other one Embodiment of this invention. It is a front view which shows the rotary body by other one Embodiment of this invention. 6 is a view illustrating a rotating body arranged in a heating furnace according to another embodiment of the present invention. FIG. 8A is a front view showing a body part constituting the rotating body of FIG. 5, and FIG. 8B is a front view showing a shaft part constituting the rotating body of FIG.

  Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to the following embodiments, and is based on ordinary knowledge of a person skilled in the art without departing from the spirit of the present invention. It should be understood that modifications and improvements as appropriate to the following embodiments also fall within the scope of the present invention.

[First embodiment]
The rotating body which is 1st Embodiment concerning this invention is demonstrated with reference to Fig.1 (a) which is the front view, and FIG.1 (b) which is A arrow view of Fig.1 (a). A rotating body 100 shown in FIG. 1 includes a hollow cylindrical barrel portion 1 made of ceramics and a pair of solid cylindrical shaft portions 2 made of ceramics fitted to inner surfaces of both end portions of the barrel portion. And the trunk | drum 1 and the axial part 2 have the fitting surfaces 3 and 4 which should be fitted by the contact | adherence state, respectively, and the fitting interface 5 of the left side axial part 2 has the rotating shaft 9 of the rotary body 100. Air holes 6 extending in the direction are formed. The rotating body 100 of the present invention has a ceramic integrated structure in which a hollow body portion 1 made of ceramics and a solid shaft portion 2 disposed on inner surfaces of both end portions of the body portion are fitted. Therefore, the thermal expansion in the heating furnace is substantially the same for both the body 1 and the shaft 2, and it is possible to prevent the occurrence of vibration due to the swinging of the body 1 caused by the looseness of the body 1. For this reason, it has the effect that it becomes difficult to generate | occur | produce a wave | undulation and a crack in the product (heated steel plate) conveyed by the rotary body 100. In addition, the body portion 1 that is in contact with a heated steel plate or the like is formed in a hollow shape, and since the wall thickness is thin, the thermal shock stress generated in the body portion 1 is suppressed, and the body portion 1 is prevented from being damaged. it can.

  Furthermore, in the rotating body 100 of this aspect, since the shaft portion 2 is formed solid, the strength thereof can be increased as compared with the hollow shaft portion. Here, since the overheated steel sheet or the like is not in direct contact with the shaft portion 2, damage due to thermal shock is unlikely to occur in the shaft portion 2, but it is hollow due to an excessive load acting during use or an impact caused by handling. The shaft may be damaged. Even in such a case, it is possible to increase the strength of the shaft portion 2 and prevent the shaft portion 2 from being damaged by providing a solid shape capable of securing a cross-sectional area. The configuration in which the shaft portion 2 is solid is particularly effective in a rotating body having the shaft portion 2 having a small diameter and a diameter of 50 mm or less.

  Here, the hollow body portion 1 is fitted so that the fitting surface of the solid shaft portion 2 is in close contact with the fitting surface 3, so that the hollow portion 8 sealed in the body portion 1 is sealed. Is formed. When the rotating body 100 is disposed in a high temperature environment such as in a heating furnace, the air pressure in the hollow portion 8 of the trunk portion 1 increases, so that a tensile stress is generated on the surface of the trunk portion 1 and the heated steel plate becomes a barrel. Due to the thermal shock that occurs when the part 1 is touched, the body part 1 is easily damaged. In order to prevent this increase in air pressure, an air hole 6 extending in the direction of the rotating shaft 9 of the rotating body 100 is formed in the fitting interface 5. Specifically, the air hole 6 has one end opened to the hollow portion 8 and the other end opened to the outside, and the hollow portion 8 and the atmosphere are connected via the air hole 6. Yes. Thereby, even when the rotating body 100 is inserted and used in a high-temperature environment such as a heating furnace, the heated and expanded air in the hollow portion 8 is smoothly discharged from the air holes 6. It becomes possible to prevent an increase in pressure. The air hole 6 that exhibits the above-described action may be formed in the fitting interface 5 between the body portion 1 and at least one shaft portion 2.

  As will be described later, the air hole 6 may be formed by forming a concave groove in the outer peripheral surface of the shaft portion 2 along the direction of the rotation shaft 9, but considering damage from the groove corner and processing costs, As shown in FIG. 1 (b), a flat surface 7 is formed on a part of the fitting surface 4 of the shaft portion 2, and the cross section formed by the flat surface 7 and the fitting surface 3 of the body portion 1 is approximately. It is preferable that the air hole 6 is constituted by a semicircular passage. In FIG. 1A, the flat surface 7 is formed in a part of the shaft portion 2 so that the air hole 6 is interposed between the outside and the hollow portion 8 along the direction of the rotation shaft 9. However, it may be formed over the entire length of the shaft portion 2.

  In this way, the barrel portion 1 and the shaft portion 2 are damaged by making the barrel portion 1 hollow and the shaft portion 2 solid, and providing the air holes 6 in the fitting interfaces 5 between the fitting surfaces 3 and 4. In addition, it is possible to provide a highly durable rotating body that can prevent vibrations caused by the swinging of the body 1 and the body 1.

  The body portion 1 and the shaft portion 2 need to be fitted in a state of being closely attached to the fitting surfaces 3 and 4. For the fitting between the body portion 1 and the shaft portion 2, various joining methods such as shrink fitting, diffusion bonding, or brazing can be used, but shrink fitting is preferable from the viewpoint of ease of manufacture. In the case of shrink fitting, it is preferable that the shrinkage rate of the trunk portion 1 and the shaft portion 2 is in the range of 0.01 / 1000 to 0.5 / 1000, respectively. When the shrinkage-fit rate is less than 0.01 / 1000, the tightening force of the body portion 1 to the shaft portion 2 is insufficient, and the shaft portion 2 may come off from the body portion 1 or slip. Further, if the shrinkage fitting ratio exceeds 0.5 / 1000, the tightening force due to shrinkage fitting becomes too large, and there is a possibility that the body 1 or the shaft 2 is damaged. A more preferable shrink fitting rate is 0.2 / 1000 to 0.3 / 1000. Moreover, in order to prevent the vibration by a whirling, the concentricity of the trunk | drum 1 and the axial part 2 has preferable 0.2 mm or less.

  The thickness of the hollow body 1 is preferably 5 to 30 mm. If it is less than 5 mm, it is likely to break due to the load from the steel plate when transporting the steel plate, and if it is 30 mm or more, the body portion 1 is likely to be damaged by the thermal shock caused by the heated steel plate. This is because there are cases.

[Second Embodiment]
A rotating body 200 of the second embodiment different from the rotating body 100 of the first embodiment will be described with reference to FIG. Here, Fig.2 (a) is a front view of the rotary body 200, FIG.2 (b) is a B arrow directional view of Fig.2 (a). 2, the same components as those of the rotating body 100 of the first embodiment are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof is omitted (the following third to fifth embodiments and modifications). The same applies to the example).

  The rotator 200 of the second embodiment shown in FIG. 2 has a trunk portion 1a and a shaft portion 2a as in the rotator 100 of the first embodiment, but has a recess formed on the fitting surface 3 of the trunk portion 1a. It differs from the rotating body 100 in that the air hole 10 is formed in the fitting interface 3 by the groove 11. That is, as shown in FIG. 2A, the concave groove 11 extending inward from the end surface of the body portion 1 a has a length from the end surface of the body portion 1 of the body portion 1 and the shaft portion 2. It is formed to be longer than the fitting length of the fitting interface 3. The air hole 10 defined by the groove 11 and the fitting surface 4 of the shaft portion 2 is formed by closely contacting the body portion 1 and the shaft portion 2 at the respective fitting surfaces 3 and 4. One end opens to the hollow portion 8 and the other end opens to the outside. The second embodiment of the rotating body 200 having such air holes 8 can also provide the same functions and effects as the first embodiment of the rotating body 100. However, the shaft portion 2 has a small diameter, a flat portion and a concave portion. Forming the groove is effective when the cross-sectional area decreases and the strength of the shaft portion 2 decreases. In addition, when the concave groove 11 is formed in the fitting surface 3 of the trunk portion 1 as in this aspect, in order to prevent breakage from the corner portion of the concave groove, as shown in the figure, it is orthogonal to the rotating shaft 9. It is preferable to form a substantially semicircular or substantially U-shaped groove 11 having no corners in cross-sectional view.

  A modification example having the same operation and effect as the air holes 6 and 10 of the rotating bodies 100 and 200 of the first aspect and the second aspect will be described with reference to FIG. FIGS. 3A and 3B are examples in which the air hole 6 is configured by the concave groove formed in the fitting surface 4 of the shaft portions 2b and 2c mentioned above, and a cross-sectional view orthogonal to the rotation shaft 9 is shown. 3A is an example of a substantially rectangular groove 12, and FIG. 3B is an example of a substantially semicircular groove 13. FIG. FIG. 3C shows an example in which the air hole 10 is formed by a substantially rectangular groove 14 formed on the fitting surface of the body 1b. In this case, the corner of the groove 14 is formed in the corner. It is preferable to form a curved surface (R surface) in order to prevent breakage. FIG. 3D shows a state in which the groove portions 15 and 16 having substantially the same groove width are formed on the fitting surfaces 3 and 4 of the body portion 1c and the shaft portion 2d, and the grooves 15 and 16 are aligned so as to face each other. This is an example in which the air hole 17 is formed by fitting the shaft portion 2 to the body portion 1. In this manner, by forming the concave grooves 15 and 16 in the body portion 1c and the shaft portion 2d, air holes 17 that can discharge air at an appropriate flow rate while ensuring the strength of the body portion 1 and the shaft portion 2 are formed. Can be configured. It should be noted that the above-described flat surface may be formed in the shaft portion 2d in place of the concave groove 16. Furthermore, FIG.3 (e) is the example which comprised the two air holes 6 by the two flat surfaces 7 and 7 formed so that it might oppose the fitting surface of the axial part 2e.

  In the rotating body, the cross-sectional area of the air hole 6 or 10 in a cross section perpendicular to the rotating shaft 9 is preferably 0.001 to 5% of the cross-sectional area of the shaft portion 2. If the cross-sectional area of the air hole 6 or 10 is less than 0.001, the effect of the air hole may not be obtained, and when the rotary body is inserted into a heating furnace and used, This is because the pressure rises and tensile stress due to the internal pressure acts on the surface of the body part, and the heated steel sheet may be easily damaged by thermal shock when it touches the body part. Further, if the cross-sectional area of the air hole 6 or 10 exceeds 5%, the strength of either or both of the body part and the shaft part is lowered, and they may be damaged. This is because imbalance occurs and vibration of the rotating body may occur. The cross-sectional area of the air hole is more preferably 0.03 to 2%, and further preferably 0.05 to 0.5% of the cross-sectional area of the shaft portion.

  In the above rotating body, the relationship between the fitting length (L) along the rotation axis direction of the fitting surface and the diameter (D) on the fitting surface of the shaft portion is L / D = 0.5-2. preferable. This is because when L / D is less than 0.5, the adhesion between the body portion and the shaft portion at the fitting interface is insufficient, and the shaft portion comes off or slips. On the other hand, when L / D exceeds 2, the bending moment applied to the fitting surface of the body portion and the shaft portion becomes large and is easily damaged. A more preferable range of L / D is 0.8 to 1.3.

[Third embodiment]
A rotating body 300 according to a third embodiment different from the rotating body 100 according to the first embodiment will be described with reference to FIG. Here, FIG. 4A is a front view of the rotator 300, FIG. 4B is a view taken along the arrow C in FIG. 4A, and FIG. 4C is FIG. ), And FIG. 4D is a view as seen from the direction of arrow D in FIG.

  The rotating body 300 of the third embodiment shown in FIG. 4 has the body portion 1, the shaft portion 2 f, and the air holes 6 similar to the rotating body 100 of the first mode, like the rotating body 100 of the first embodiment. The shaft portion 2f is connected to the bearing portion 2g to be connected to the bearing, the flange portion 2h connected to the bearing portion 2g, the large diameter portion 2i larger than the bearing portion 2g connected to the flange portion 2h, and the large diameter portion 2i. It is different in that it is formed from a fitting portion 2j that is continuous and has a fitting surface 3 and has an air hole 19 formed in the vertical direction. Here, the outer diameter of the large-diameter portion 2i is larger than that of the fitting portion 2i, and the end surface on the body portion 1 side is disposed in close contact with the end surface of the opposite body portion 1. Therefore, during use, for example, when an excessive torque is applied and the shaft portion 2 f slips, the shaft portion 2 f moves relatively in the direction of the rotating shaft 9 at the fitting interface 5, and the shaft portion 2 f becomes the body portion 1. Can be prevented from falling out. Further, since the small-diameter bearing portion 2g and the large-diameter large-diameter portion 2i are smoothly connected by a tapered cone-shaped flange portion 2h having an inclined surface, there are few suddenly changing portions of the thickness, and thermal shock resistance is reduced. Can be increased.

  The fitting portion 2j of the left shaft portion 2f has a flat surface 7 on the fitting surface 4 in the same manner as the rotating body 100 of the first aspect, and the fitting portion 2j is fitted to the trunk portion 1. Thus, an air hole 6 extending in the horizontal direction is formed in the fitting interface 5 between the fitting surfaces 3 and 4. The end surface of the large-diameter portion 2i is formed with a groove having a substantially semicircular cross section extending in the radial direction of the rotating body so as to be continuous with the flat surface 7, and the end surface of the large-diameter portion 2i and the end surface of the body portion 1 are formed. The air holes 19 are formed. Since the air holes 6 and the air holes 19 are connected to each other at the end portions, when the rotating body 300 is heated, the air pressurized in the hollow portion 8 of the trunk portion 1 is air holes 6. And 19 and then discharged to the outside. The cross-sectional area in the vertical vertical section of the rotating body 300 of the concave groove constituting the air hole 19 is the cross-sectional area in the cross section perpendicular to the rotation axis of the air hole 6 from the viewpoint of releasing pressurized air. It is preferable that it is equal or larger.

  Furthermore, as shown in FIG. 4D, a flat surface 20 extending in the direction of the rotation axis is formed at the end of the bearing 2g to be connected to the bearing. The flat surface 20 is formed for the purpose of inserting a key between the bearing portion 2a and the bearing (not shown) in order to transmit the rotational force from the rotary motor (not shown) to the rotating body 300. is there. By using the flat surface 20, the bearing portion 2g is hardly damaged.

[Fourth embodiment]
Regarding the rotating body 400 of the fourth embodiment, referring to FIG. 5 which is a front view thereof, FIG. 7 which shows the rotating body 400 incorporated in a heating furnace, and FIG. 8 which is a front view of each component of the rotating body 400. explain. The rotating body 400 of the fourth embodiment shown in FIG. 5 has the same shaft portion 2f and air holes 6 and 19 as the rotating body 300 of the third embodiment, but the body portion 1d has a plurality of body members 1e and 1f. 1 and 1g, and the trunk members 1e to 1g are different from each other. That is, as shown in FIG. 8, the cylindrical body member 1f constituting the central part of the body 1d has circular recesses at both ends, and the inner peripheral surface of the circular recess serves as the fitting surface 1i. Further, the pair of body members 1e and 1g fitted to both ends of the body member 1f have a circular convex part that can be fitted into the concave part of the body member 1f at one end, and the outer peripheral surface of the circular convex part is It becomes a fitting surface 1j * 1k. The body member body members 1e and 1g have the circular protrusions fitted and fixed to the circular recesses of the body member 1f to form the body part 1d. The configuration of the shaft portion 2f is the same as that of the rotating body 300 of the third aspect, and the fitting portion 2j of the shaft portion 2f is fitted in the circular recesses 1L and 1m formed at the other end of the body members 1e and 1g. The air hole 6 and the air hole 19 are formed by the fitting.

  As described above, the body members 1e to 1f of the rotating body 400 need to be fitted in close contact with each other on the fitting surface. For this fitting, various joining methods such as shrink fitting, diffusion joining, or brazing can be used, but shrink fitting is preferable from the viewpoint of ease of manufacture. In the case of shrink fitting, similarly to the case of shrink fitting between the shaft part and the body part, it is preferable that the shrinkage rate between the body members is in the range of 0.01 / 1000 to 0.5 / 1000, respectively. If the shrinkage fit is less than 0.01 / 10000, the tightening force between the body members is insufficient, and the shaft member may come off or slip. On the other hand, if the shrinkage-fit rate exceeds 0.5 / 1000, the tightening force due to shrink-fit becomes too large, and the body member may be damaged. A more preferable shrink fitting rate is 0.2 / 1000 to 0.3 / 1000. In addition, for the purpose of reducing vibration due to swinging, the concentricity of the body members 1e to 1f is preferably 0.1 mm or less.

  As shown in FIG. 7 for explaining the state in which the rotating body 400 is disposed in the heating furnace 50, through-holes through which the body 1 of the rotating body 400 can be inserted are formed in the furnace walls 51, 51 on both sides of the heating furnace 50. Has been. The rotating body 400 is horizontally disposed through the through hole so that the shaft portion 2f is exposed from the through hole, and the bearing portion of the shaft portion 2f is freely rotatable by bearings 52 and 52 disposed outside the furnace. It is supported by. Here, the barrel member 1f constituting the central portion of the trunk portion 1a is disposed in a heating chamber 53 that conveys the steel plate (conveyed material) while heating, and the steel plate 54 heated in the heating chamber 53 is: It is conveyed while being supported by the body member 1f. Since only the trunk member 1f is in contact with the conveying material 54, when the trunk member 1f is worn due to long-term use, only the trunk member 1f can be removed and replaced, and the running cost of the rotating body 400 can be reduced. Can be planned.

[Fifth Embodiment]
A rotating body 500 according to a fifth embodiment will be described with reference to FIG. The rotator 500 of the fifth embodiment shown in FIG. 5 has three body members as in the rotator 400 of the fourth embodiment, but air holes 56 and 59 are formed between the body member 1f and the body member 1h. Is different. That is, as shown in FIG. 6, a flat surface 57 similar to that formed on the fitting portion 2j of the shaft portion 2f in the fourth aspect is formed on the fitting surface 1K of the body member 1h. A concave groove (not shown) having a substantially semicircular cross section extending from the right end of the flat surface 57 in the radial direction of the rotator 500 is formed, and the end surface of the body member 1f and the end surface of the body member 1h are brought into close contact with each other. Thus, air holes 56 and 59 communicating with the hollow portion 8 and the outside are formed.

  An air hole 56 extending in the rotation axis direction of the rotating body and an air hole 59 connected to the air hole 56 and leading to the outside are formed at the fitting interface between the body member 1f and the body member 1h or 1e. An air hole 6 extending in the direction of the rotation axis of the rotating body and an air hole 19 connected to the air hole 6 and leading to the outside may be formed on the fitting surface between 1e or 1h and the shaft portion 2K.

  In the rotating bodies 100 to 500 described above, the body portions 1 to 1d and the shaft portions 2 to 2j are hard, high-strength ceramics having wear resistance that can be used as a transfer roller, such as silicon nitride, alumina, Any ceramic containing at least one kind such as silicon carbide and zirconia can be used, but it is formed from silicon nitride ceramics, has a four-point bending strength of 500 MPa or more, a Vickers hardness of 1300 or more, a relative density of 95% or more, Young The rate is preferably 250 to 350 GPa.

Silicon nitride ceramics are composed of silicon nitride crystals or hard particles of sialon crystals in which Al and O are dissolved in silicon nitride as the main crystal, and the space between them is composed of a grain boundary phase formed from a sintering aid. Since it has heat resistance and high strength and high hardness can be obtained, it is preferable when used as a rotating body for transporting a heated steel plate or the like. In particular, when the four-point bending strength is 500 MPa or more, it is difficult to break due to mechanical stress when the steel sheet is conveyed, and when the Vickers hardness is 1300 or more, the wear of the body portion 1 due to the steel sheet is reduced and lengthened. This is because a rotating body with a long life can be obtained. A relative density of 95% or more is preferable because a four-point bending strength of 500 MPa or more and a Vickers hardness of 1300 or more can be obtained. When the Young's modulus is 250 to 350 GPa, in the case of the long rotating body 400 shown in FIG. 5, the body member 1 f is not easily bent, the steel plate can be smoothly conveyed, and the quality of the steel plate is not adversely affected. Therefore, it is preferable. As the sintering aid, Al ₂ O ₃ , MgO, rare earth element oxide and the like are preferable. Among them, silicon nitride is the main crystal, 1 to 7 mass% of MgO and 1 rare earth element oxide are used as the sintering aid. The silicon nitride ceramic used in an amount of ˜7% by mass is preferable from the viewpoint of achieving both high strength and thermal shock resistance. As the rare earth element, any element of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu can be preferably used. Among these, Y, Ce, Sm, Dy, Er, Yb, and Lu, especially Y and Er are preferable in terms of characteristics and cost. Among them, Y is particularly preferable.

  In addition, in this silicon nitride ceramic, at least one of Periodic Table Group 4, Group 5 and Group 6 metals such as Ti, V, Nb, Zr, W, Mo, and Hf is 0.02 to 2 mass in terms of oxide. % Is preferable because it has an effect of improving strength and toughness.

  In the rotating body made of the above silicon nitride ceramics, it is preferable that the thermal conductivity of the silicon nitride ceramics is 50 W / mK or more and the number of grain boundaries per 10 μm is 10 or less. It is preferable for the conductivity to be 50 W / mK or more because the barrel 1 is more difficult to break due to thermal shock when the heated steel plate contacts the barrel 1. Further, it is preferable that the number of grain boundaries per 10 μm is 10 or less because the thermal conductivity is 50 W / mK or more and the four-point bending strength is 500 MPa or more. The number of grain boundaries per 10 μm is more preferably 2-8, and even more preferably 2-5.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.
Example 1
An average particle size of 0.8 μm, an oxygen content of 0.9%, an α conversion of 97% of silicon nitride powder of 93% by mass, as a sintering aid, 2.0% by mass of magnesium oxide powder having an average particle size of 0.2 μm Then, 5.0% by mass of yttrium oxide powder having an average particle size of 2.0 μm was added, an appropriate amount of a dispersant and a binder were added, and the mixture was pulverized and mixed in alcohol. Next, after spray drying, granulated through a sieve, filled into a rubber mold, and subjected to cold isostatic pressing (CIP) by hydrostatic pressure, which corresponds to the barrel members 1e, 1f, 1g and the shaft portion 2 shown in FIG. A molded body having a predetermined shape was prepared. The molded body is fired in a nitrogen gas atmosphere at 1800 ° C. and 10 atm for 5 hours to obtain a sintered body made of silicon nitride ceramics, and then ground into a predetermined shape, respectively, as shown in FIG. Rotating body 400 and a sintered body for measuring material characteristics were prepared. Here, the rotating body 400 had an overall length of 3060 mm, an overall length of the body 1d of 2260 mm, and an outer diameter of 120 mm.

  Here, the body member 1f has a total length of 1500 mm, an outer diameter of 120 mm, and an inner diameter of 80 mm, and a circular recess having an inner diameter of 90 mm and a length of 110 mm for forming the fitting surface 1i is formed at both ends thereof. The body members 1e and 1g have a total length of 480 mm, an outer diameter of 120 mm, and an inner diameter of 50 mm, and an outer shape of 90 mm and a length of 100 mm for forming fitting surfaces 1j and 1K that can be fitted to the body member 1f at one end. A circular concave portion having an inner diameter of 90 mm and a length of 110 mm for forming fitting surfaces 1L and 1m that can be fitted to the shaft portion 2f was formed at the other end portion.

  On the other hand, the pair of shaft portions 2f has a total length of 500 mm, the outer diameter of the fitting portion 2j is 90 mm, the length is 100 mm, the outer diameter of the large diameter portion 2i is 115 mm, the outer diameter of the bearing portion 2g is 50 mm, and the length is 150 mm. A flat portion 7 having a width of 20 mm and a length of 100 mm extending in the rotation axis direction of the rotating body is formed in the fitting portion 2j of one of the shaft portions 2f, and the large diameter portion 2i is continuous with the flat surface 7. Then, a concave groove having a locality radius of 3.1 mm extending in the radial direction of the rotating body was formed.

  The shrinkage rate of 0.3 / 1000 is adjusted so that the concentricity of the body members 1e to 1g and the fitting parts 1i of the body member 1f and the fitting parts 1j and 1k of the body members 1e and 1g are 0.1 mm. It was integrated with shrink fitting. Then, the other fitting portions 1L and 1m of the body members 1e and 1g and the fitting portion 23 of the shaft portion 2 are shrink-fitted and integrated at a shrinkage fitting rate of 0.3 / 1000 so that the concentricity is 0.1 mm. The rotation 400 of the fourth embodiment shown in FIG. 5 was produced. In this rotator 400, the cross-sectional area of the air hole 6 in the cross section perpendicular to the rotation axis is 0.24% of the cross-sectional area of the shaft portion, and the air hole 19 in the vertical cross-section in the radial direction of the rotator 400 The cross-sectional area is substantially the same as the air hole 6. Further, the relationship between the fitting length L (100 mm) along the rotation axis direction of the fitting surface of the body portion 1d and the shaft portion 2f and the diameter D (90 mm) of the fitting portion 2j of the shaft portion 2f is L / D = 1. .11.

At the same time, a test piece was prepared from the sintered body for measuring material properties, and the following material properties were measured. The 4-point bending strength was measured by the method specified in JIS R1601, and the average value was 900 MPa. The Vickers hardness was measured by the method defined in JIS R1610, and the average value was 1500. The relative density was 99%, as measured by the method prescribed in JIS R1634, by measuring the sintered body density and calculating it as a ratio to the theoretical density of silicon nitride (3.27 g / cm ³ ). The Young's modulus was measured using the static elastic modulus measuring method defined in JIS R1602, and the average value was 305 GPa. The thermal conductivity was measured by the laser flash method specified in JIS R1611, and the average value was 66 W / mK. In addition, the number of grain boundaries per 10 μm is measured on an arbitrary straight line having a total length of 500 μm by SEM after etching any polished surface of silicon nitride ceramics so that the grain boundaries can be identified. The number of grain boundaries was measured and calculated as the number of grain boundaries per 10 μm of linear length, and the number of grain boundaries was 5 per 10 μm.

(Examples 2 to 5)
For the rotating body of the first embodiment, the width of the flat surface 7 formed on the fitting surface 3 of the shaft portion 2f and the radius of curvature of the concave groove formed in the large diameter portion 2i connected thereto are changed, so that the rotating shaft Example 1 except that the air hole 6 is formed by changing the cross-sectional area of the air hole 6 in a cross section perpendicular to the air hole 6 as shown in Table 1 and the cross-sectional area of the air hole 19 is substantially the same as the air hole 6. In the same manner as in Example 1, rotating bodies of Examples 2 to 5 were produced.

(Comparative Example 1)
A rotating body of Comparative Example 1 was produced in the same manner as in Example 1 except that the air holes 19.6 were not formed on the rotating body of Example 1.

(Comparative Example 2)
Using the same ceramics as in Example 1, a solid and integral rotating body having a length of 3060 mm and an outer diameter of 120 mm having the same dimensions as the rotating body 400 was produced.

(Comparative Example 3)
Using the same ceramics as in Example 1, a sleeve made of ceramics having an outer diameter of 120 mm, an inner diameter of 80 mm, and a total length of 1500 mm was produced. A metal shaft having a total length of 3060 mm, an outer diameter of 60 mm, and a flow path for circulating cooling water inside is manufactured by SUS310, inserted into the sleeve, and a heat insulating material made of ceramic fiber between the sleeve and the metal shaft And a rotating body made of ceramics and metal, in which one end face in the axial direction of the sleeve was pressed and fixed with a spring.

  The rotating bodies of Examples 1 to 5 and Comparative Examples 1 to 3 were installed in a heating furnace having a furnace inner width of 1400 mm and a furnace temperature of 1,100 ° C. A steel plate having a plate thickness of 4.5 mm and a plate width of 1300 mm was passed through this heating furnace. The results are shown in Table 1. In each of the rotating bodies of Examples 1 to 5, the steel plates were smoothly transported, and the swells and scratches of the steel plates did not occur, and the service life of 6 months or more could be confirmed. It should be noted that minute peeling to the extent that does not affect the quality of the steel sheet occurred on a part of the surface of the body member 1f of the rotating body of Example 4. Moreover, although the very small vibration had generate | occur | produced in the rotary body of Example 5, there was no influence on the quality of a steel plate. On the other hand, since the air hole was not formed in the rotating body of Comparative Example 1, a breakage of the body of the rotating body occurred immediately after the start of conveyance, and the rotating body could not be used. Moreover, since the trunk | drum was solid, the rotating body of the comparative example 2 generate | occur | produced a crack when it arrange | positioned in a heating furnace, and could not be used. Further, the rotating body of Comparative Example 3 was discontinued from use because it caused vibration due to swirling after about 1 hour of use, and the product was swelled.

1 (1a-1d): trunk | drum 1e, 1f, 1g: trunk | drum member 2 (2a-2f, 2k): axial part 2j: fitting part
2i: Large diameter portion 2h: Flange portion 2g: Bearing portion 3 (4): Fitting surface 5: Fitting interface 6 (10, 17, 19): Air hole 7: Flat surface 8: Hollow portion 9: Rotating shaft

Claims (11)

  A rotating body having a hollow body portion made of ceramics and a solid shaft portion made of ceramics fitted to inner surfaces of both end portions of the body portion, wherein the body portion and the shaft portion are fitted in close contact with each other. Each has a fitting surface to be mated, and an air hole extending in the direction of the rotation axis of the rotating body is formed at the fitting interface between the body part and the shaft part, and the air hole is connected to the atmosphere. A rotating body that is used for transporting and supporting high-temperature materials in the atmosphere.   The rotating body according to claim 1, wherein the rotating body is used outside the furnace.   The rotating body according to claim 1 or 2, wherein a cross-sectional area of the air hole in a cross section perpendicular to the rotation axis is 0.001 to 5% of a cross-sectional area of the shaft portion.   The rotating body according to any one of claims 1 to 3, wherein a flat surface is formed on a part of the fitting surface of the shaft portion.   The rotating body according to any one of claims 1 to 4, wherein a relationship between a fitting length L along the rotation axis direction of the fitting surface and a diameter D of the shaft portion is L / D = 0.5-2.   The shaft portion includes a bearing portion to be connected to a bearing, a flange portion connected to the bearing portion, a large diameter portion larger in diameter than the bearing portion connected to the flange portion, and the fitting surface. The rotating body according to any one of claims 1 to 5, comprising a fitting portion including   The rotating body according to any one of claims 1 to 6, wherein each of the body portions includes a body member made of a plurality of ceramics, and the body members are fitted to each other.   The barrel member has a fitting surface to be fitted in close contact with each other, and instead of an air hole formed in the fitting interface between the barrel portion and the shaft portion, a rotating body is provided at the fitting interface of the barrel member. The rotating body according to claim 7, wherein an air hole extending in the direction of the rotation axis is formed.   The rotation according to any one of claims 1 to 8, wherein the shaft portion has a bearing portion to be connected to the bearing, and a flat surface extending in a rotation axis direction is formed at an end portion of the bearing portion. body.   The body portion and the shaft portion are both formed of silicon nitride ceramics, and have a four-point bending strength of 500 MPa or more, a Vickers hardness of 1300 or more, a relative density of 95% or more, and a Young's modulus of 250 to 350 GPa. The rotating body according to any one of the above. The rotating body according to claim 10, wherein the silicon nitride ceramic has a thermal conductivity of 50 W / mK or more and 10 or less grain boundaries per 10 μm.

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