Structure with a thermoplastic elastomer coating layer, moving body, and conveying device

Abstract

A structure with a thermoplastic elastomer coating layer, a moving body, and a conveying device are provided, which can mass-produce products at low cost. [Solution] The bearing (10) includes a first material layer (43) and a second material layer (44). The second material layer is made of a material softer than the first material layer. The first material layer (43) is formed on the outer peripheral surface (24) of the outer ring (21) by injection molding. The first material layer (43) is covered with the second material layer (44). The second material layer (44) has an outer peripheral surface layer (52), a first side surface layer (53), and a second side surface layer (54). The first outer peripheral surface (46) of the first material layer (43) is covered with the outer peripheral surface layer (52). Both side surfaces of the first material layer (43) are sandwiched between the first side surface layer (53) and the second side surface layer (54).

Description

Technical Field

[0001] The present invention relates to a structure with a thermoplastic elastomer coating layer, a moving body, and a conveying device.

Background Art

[0002] For example, as an application of a rolling bearing, it is known to convey a conveyed object such as a banknote or a ticket with the outer ring of the rolling bearing, or to roll the rolling bearing as a wheel of a moving body along a contacting object. In this case, in order to increase the frictional force between the outer peripheral surface of the outer ring and the conveyed object or the contacting object, or to reduce the noise when the outer ring rolls and contacts, the outer ring may be coated with urethane rubber. Urethane rubber is excellent in wear resistance and can be firmly adhered and fixed to the outer ring. The manufacturing process of attaching urethane rubber to the outer ring is as follows.

[0003] First, the outer peripheral surface of the outer ring of the rolling bearing is roughened by sandblasting, and an adhesive is applied to the roughened outer peripheral surface. Next, the rolling bearing is set in a mold, and a urethane raw material (liquid) is poured between the outer peripheral surface and the mold, and pressure is applied to the mold for molding. Then, it is held at a high temperature for a predetermined time (about half a day to one day depending on the hardness) in the mold. While curing the urethane rubber at a high temperature, the adhesive is heated to vulcanize and bond the urethane rubber to the outer peripheral surface. After vulcanization bonding, the outer peripheral surface of the urethane is polished to finish it to a predetermined dimension and accuracy. Thereby, the outer peripheral surface of the outer ring of the rolling bearing is coated with urethane rubber (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, conventional rolling bearings have the following problems. That is, it is necessary to cure the urethane rubber in the mold for a long time, it takes time to apply the adhesive to the outer peripheral surface of the outer ring, and after curing the urethane rubber, it is necessary to finish the outer peripheral surface of the urethane to a predetermined dimension and accuracy by polishing. Therefore, when mass-producing a rolling bearing with a urethane rubber coated on the outer peripheral surface, it is necessary to have a large number of facilities for coating the urethane rubber on the outer peripheral surface, which increases the equipment cost. In addition, a process of roughly processing the outer peripheral surface of the outer ring by sandblasting and a process of applying an adhesive to the roughly processed outer peripheral surface are required. For this reason, it is difficult to manufacture a rolling bearing coated with urethane rubber inexpensively and in large quantities.

[0006] The present invention has been made in consideration of such circumstances, and an object thereof is to provide a structure, a moving body, and a drive module with a thermoplastic elastomer coating layer that can manufacture a large number of products inexpensively.

Means for Solving the Problems

[0007] A structure with a thermoplastic elastomer coating layer according to an aspect of the present invention for solving the above problems includes a coating layer on the outer peripheral surface of a cylindrical member, and the coating layer has an outer peripheral surface layer formed by thermally fusing a thermoplastic elastomer. The coating layer includes a first material layer made of an amorphous plastic on the outer peripheral surface, and a second material layer made of a thermoplastic elastomer that contains potassium titanate fibers on the outer surface of the first material layer and forms the outer peripheral surface of the coating layer by thermally fusing. The second material layer is a softer material than the first material layer.

[0008] By thermally fusing the thermoplastic elastomer to form the outer peripheral surface, the outer peripheral surface layer can be firmly fixed by thermal fusion. Therefore, the sandblasting process and the coating process using an adhesive, which were conventionally required, can be made unnecessary. As a result, a structure with a thermoplastic elastomer coating layer can be manufactured inexpensively and in large quantities.

[0009] A structure with a thermoplastic elastomer coating layer according to one aspect of the present invention includes a coating layer formed on an outer surface having irregularities. The coating layer has an outer peripheral surface layer formed by heat-fusing a thermoplastic elastomer. The coating layer includes, on the outer surface, a first material layer made of an amorphous plastic, and a second material layer made of a thermoplastic elastomer as the outer peripheral surface layer that forms the outer peripheral surface of the coating layer by heat-fusing the thermoplastic elastomer to the outer surface of the first material layer. The second material layer is a material softer than the first material layer.

[0010] According to this configuration, by making the second material layer a material softer than the first material layer, a hard material can be used for the first material layer. A soft material refers to a material having a small flexural modulus and hardness (for example, Shore hardness A). A hard material refers to a material having a large flexural modulus and hardness (for example, Shore hardness A). When the first material layer is formed on a circular outer surface, the first material layer is formed in an annular shape. Therefore, due to the shrinkage when the first material layer is cooled and cured, the first material layer is firmly attached to the circular outer surface. Also, when the first material layer is formed on a flat outer surface having irregularities, the first material layer is locked to the irregularities of the flat outer surface. Therefore, the first material layer can be firmly fixed to a circularly formed outer surface or a flat outer surface having irregularities. Furthermore, by making the second material layer a material softer than the first material layer, the second material layer can be firmly fixed to the first material layer by heat fusion. In this way, by interposing a hard first material layer between the outer surface and the second material layer, the second material layer can be firmly fixed to a circular outer surface or an outer surface having irregularities via the first material layer.

[0011] Furthermore, the second material layer is firmly fixed by heat fusion to a circular outer surface or a flat outer surface having irregularities through the first material layer. Thus, the sandblasting process and the coating process using an adhesive, which were conventionally required, can be made unnecessary. As a result, a structure with a thermoplastic elastomer coating layer can be manufactured inexpensively and in large quantities.

[0012] Also, the second material layer is made of a material softer than the first material layer. Thereby, when conveying an object such as a banknote or a ticket with the outer ring of the bearing (i.e., the second material layer), or when rolling the bearing as a wheel of a moving body along a contact object, noise can be reduced by the second material layer.

[0013] In the above aspect, the outer peripheral surface is the outer peripheral surface of the outer ring provided in the bearing, and a coating layer may be formed on the outer peripheral surface of the outer ring. According to this configuration, the second material layer can be firmly fixed to the outer peripheral surface of the outer ring provided in the bearing through the first material layer. Thereby, it is possible to prevent the second material layer from falling off from the outer peripheral surface of the outer ring (i.e., the bearing).

[0014] In the above aspect, a groove portion extending in the circumferential direction may be provided on the outer peripheral surface of the outer ring. According to this configuration, by providing a groove portion on the outer peripheral surface, the first material layer can be filled in the groove portion. When the protrusion of the first material layer is filled in the groove portion on the outer peripheral surface, the groove portion on the outer peripheral surface and the protrusion of the first material layer can be engaged in an uneven shape. Therefore, when a force is applied to the first material layer, the first material layer can be prevented from coming off from the outer ring due to the unevenness between the outer peripheral surface and the first material layer. Thereby, it is possible to more reliably prevent the first material layer and the second material layer from falling off from the outer peripheral surface of the outer ring (i.e., the bearing).

[0015] In the above aspect, the second material layer may have an outer peripheral surface layer that covers the outer surface of the first material layer, and a pair of side surface layers that are connected to the outer peripheral surface layer and cover both side surfaces in the axial direction of the first material layer.

[0016] According to this configuration, a pair of side layers are formed on the second material layer, and both side surfaces of the first material layer are sandwiched by the pair of side layers. Therefore, when the second material layer cools and shrinks, both side surfaces of the first material layer can be clamped by the pair of side layers. As a result, the second material layer can be more firmly engaged with the first material layer, and it can be more reliably prevented that the second material layer drops off from the outer peripheral surface (i.e., the outer ring).

[0017] In the above aspect, the pair of side layers of the second material layer may be in contact with the outer peripheral surface of the outer ring. According to this configuration, by bringing the pair of side layers of the second material layer into contact with the outer peripheral surface of the outer ring, a larger height dimension of the pair of side layers can be ensured. Therefore, a larger contact area of the side layers with respect to the side surfaces of the first material layer can be ensured. As a result, when the second material layer cools and shrinks, both side surfaces of the first material layer can be clamped by the pair of side layers, and the second material layer can be more firmly engaged with the first material layer.

[0018] In the above aspect, the first material layer may be formed such that the width dimension gradually increases radially outward from the outer peripheral surface.

[0019] According to this configuration, by gradually increasing the width dimension of the first material layer radially outward, the second material layer can be more firmly fixed to the first material layer. As a result, it can be more reliably prevented that the second material layer drops off from the outer peripheral surface (i.e., the outer ring).

[0020] A coating layer is provided on the outer peripheral surface of an outer ring included in a cylindrical bearing. The outer ring is formed of an amorphous plastic. The coating layer includes an outer peripheral surface layer formed by thermally fusing a thermoplastic elastomer containing potassium titanate fibers to the outer peripheral surface of the outer ring. The outer peripheral surface layer is made of a material softer than the outer ring.

[0021] According to this configuration, by making the first material layer a thermoplastic elastomer of the same material as the second material layer, the first material layer and the second material layer can be thermally fused better. As a result, the second material layer can be fixed more firmly to the first material layer, and it is possible to more reliably prevent the second material layer from falling off from the outer peripheral surface (i.e., the outer ring).

[0022] According to this configuration, by forming the outer ring from an amorphous plastic (rigid plastic), a coating layer can be directly formed on the outer ring made of the amorphous plastic. Thereby, the first material layer can be removed, and the configuration can be simplified.

[0023] In the above aspect, a gate trace is provided on the outer surface of the second material layer, and when viewed in the axial direction, the outer shape of the gate trace is formed larger than the wall thickness dimension of the second material layer, and it may be arranged so as to overlap both the second material layer and the first material layer in the axial direction.

[0024] According to this configuration, the opening of the gate is formed large, and by arranging the gate so as to overlap both the first material layer and the second material layer, even when the wall thickness dimension of the second material layer is reduced, the second material layer can be molded well. Furthermore, the outer surface of the first material layer (specifically, the first side layer) can be filled with a thermoplastic elastomer under a large pressure. Thereby, the adhesion between the two layers of the first material layer and the second material layer can be enhanced.

[0025] In order to solve the above problems, a moving body according to an aspect of the present invention has a plurality of the above-described structures with a thermoplastic elastomer coating layer, the structure with a thermoplastic elastomer coating layer is a bearing, the inner rings of the plurality of bearings are fixed to a main body portion, the coating layers of the plurality of bearings are brought into contact with a contacting object, and the coating layer and the outer ring to which the coating layer is fixed function as a wheel that rolls with respect to the contacting object. In addition, in order to solve the above problems, a conveying device according to an aspect of the present invention has a pair of the above-described structures with a thermoplastic elastomer coating layer, the structures with a thermoplastic elastomer coating layer are bearings, the respective coating layers are arranged adjacent to each other, an inner ring of the bearing is attached to a support shaft, and by rotating the outer ring and the coating layer, a conveyed object sandwiched between the pair of coating layers is conveyed.

[0026] According to this configuration, by providing the above-described structures with a thermoplastic elastomer coating layer in a moving body or a conveying device, durability can be ensured and a low-cost moving body or conveying device can be obtained.

Effect of the Invention

[0027] According to an aspect of the present invention, by heat-fusing a thermoplastic elastomer to form an outer peripheral surface, the outer peripheral surface layer can be firmly fixed by heat fusion. Thereby, a structure with a thermoplastic elastomer coating layer can be manufactured inexpensively and in large quantities.

Brief Description of the Drawings

[0028]

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Mode for Carrying Out the Invention

[0029] Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the first to sixth embodiments, a structure with a thermoplastic elastomer coating layer will be described as bearings 10, 70, 90, 110, 130, 140. (First Embodiment) FIG. 1 is a cross-sectional view of a bearing 10 according to the first embodiment. As shown in FIG. 1, the bearing 10 is a rolling bearing including a ring body 12, a plurality of rolling elements 14, a retainer 16, and a coating layer 18. The ring body 12 includes an outer ring 21 and an inner ring 22. The outer ring 21 and the inner ring 22 are arranged coaxially with the axis O of the bearing 10. The inner ring 22 is arranged radially inside the outer ring 21. The plurality of rolling elements 14 are arranged annularly between the outer ring 21 and the inner ring 22 that constitute the ring body 12. The retainer 16 rotatably holds the plurality of rolling elements 14 in a state of being evenly arranged in the circumferential direction.

[0030] The outer ring 21 is made of a metal material such as stainless steel. The outer ring 21 is a cylindrical member and is formed, for example, by forging or machining. The outer ring 21 has an outer peripheral surface (i.e., the outer surface formed in a circular shape) 24, an inner peripheral surface 25, a central portion 26, and a pair of outer portions 27. The outer peripheral surface 24 is formed in an annular shape on the radially outer side of the outer ring 21. The inner peripheral surface 25 is formed in an annular shape on the radially inner side of the outer ring 21. The central portion 26 is formed at the center in the direction of the axis O. In the central portion 26, a portion 25a at the center in the direction of the axis O of the inner peripheral surface 25 is formed at a distance T1 from the outer peripheral surface 24 of the outer ring 21 in the radially inner direction. In a portion of the outer peripheral surface 24 corresponding to the central portion 26, a concave portion is formed as a groove portion 28 extending in the circumferential direction.

[0031] The groove portion 28 has a deepest portion 28a on the radially inner side of the outer peripheral surface 24. The deepest portion 28a is the deepest portion among the groove portions 28. The groove portion 28 is formed such that the groove width dimension L1 gradually decreases from the outer peripheral surface 24 side to the deepest portion 28a in the cross-sectional shape. As an example, the groove portion 28 has a cross-sectional shape formed as a curved surface at the center in the direction of the axis O of the outer ring 21 and is open to the radially outer side of the outer ring 21. The groove portion 28 is formed in a shape symmetric with respect to the center in the direction of the axis O of the outer ring 21.

[0032] The pair of outer portions 27 are formed symmetrically with respect to the center in the direction of the axis O of the outer ring 21 on the outer side in the direction of the axis O from the central portion 26. In the pair of outer portions 27, a portion on the outer side in the direction of the axis O of the inner peripheral surface 25 is formed at a distance T2 from the outer peripheral surface 24 of the outer ring 21 in the radially inner direction. The interval T1 of the central portion 26 is set to be larger than the interval T2 of the pair of outer portions 27. That is, the wall thickness dimension of the central portion 26 is larger than the wall thickness dimension of the pair of outer portions 27.

[0033] On a portion 25a of a central portion 26 of the inner peripheral surface 25, an outer ring rolling surface 29 is formed. The outer ring rolling surface 29 is formed with an arcuate side cross-section so as to follow the outer surface of the rolling element 14. The radius of curvature in the cross-section of the outer ring rolling surface 29 is formed to be substantially the same as or slightly larger than the radius of curvature of the outer surface of the rolling element 14. The outer ring rolling surface 29 is formed over the entire circumference of the inner peripheral surface 25 of the outer ring 21. The outer ring rolling surface 29 can contact the outer surfaces of a plurality of rolling elements 14. The outer ring rolling surface 29 is formed at the center in the direction of the axis O and is disposed at a position overlapping the groove portion 28 in the radial direction of the outer peripheral surface 24.

[0034] Incidentally, the groove portion 28 is formed at the center in the direction of the axis O and is disposed at a position overlapping the outer ring rolling surface 29 in the radial direction of the outer peripheral surface 24. On the other hand, the groove portion 28 has a curved cross-sectional shape. Therefore, the influence of the deformation of the outer ring 21 and the reduction in the rigidity of the outer ring 21 due to the groove portion 28 on the outer ring rolling surface 29 can be suppressed. Furthermore, by forming the cross-sectional shape of the groove portion 28 into a curved surface, the groove portion 28 does not have a flat portion on its bottom surface. Thereby, when machining the groove portion 28 with a cutting tool, the cutting resistance of the cutting tool can be suppressed to be small, and the machining of the groove portion 28 becomes easy. Furthermore, by suppressing the cutting resistance of the cutting tool to be small, the life of the cutting tool can be extended. In addition, the groove portion 28 is formed in a shape symmetric with respect to the center in the direction of the axis O of the outer ring 21. The groove portion 28 is formed well-balancedly at the center of the outer peripheral surface 24 of the outer ring 21. Thereby, the influence of the deformation of the outer ring 21 and the reduction in the rigidity of the outer ring 21 due to the groove portion 28 on the outer ring rolling surface 29 can be suppressed more favorably.

[0035] Here, the groove portion 28 is provided at the center in the direction of the axis O of the outer ring 21, and the outer ring rolling surface 29 is also provided at the center in the direction of the axis O of the outer ring 21. Thereby, the influence of deformation due to heat treatment such as quenching of the outer ring 21 can be suppressed to be small. In particular, the outer ring 21 is formed such that the wall thickness dimension of the central portion 26 is larger than the wall thickness dimensions of the pair of outer portions 27. The groove portion 28 is formed at a portion where the wall thickness dimension of the central portion 26 is large. Thereby, the wall thickness dimension for forming the groove portion 28 can be ensured. Furthermore, the groove portion 28 has a curved cross-sectional shape. On the other hand, the outer ring rolling surface 29 also has a curved cross-sectional shape. That is, the groove portion 28 is formed in the same shape as the outer ring rolling surface 29. Thereby, the influence of deformation due to heat treatment such as quenching of the outer ring 21 can be further reduced.

[0036] In the first embodiment, an example in which the groove portion 28 is formed with a curved cross-section has been described. However, the present invention is not limited to this, and as other examples, it may be formed in a shape such as a V-shaped cross-section or a U-shaped cross-section. Even when the groove portion 28 is formed in a V-shaped cross-section, a U-shaped cross-section, etc., the same effects as those of the first embodiment can be obtained.

[0037] The inner ring 22 is made of a metal material such as stainless steel. The inner ring 22 is a substantially cylindrical member having a predetermined thickness dimension in the axial direction of the axis O, and is formed by, for example, forging or machining. An inner ring rolling surface 33 is formed at an intermediate portion in the axial direction of the outer peripheral surface 32 of the inner ring 22. The inner ring rolling surface 33 has a side cross-section formed in an arc shape along the outer surface of the rolling element 14. The radius of curvature in the cross-section of the inner ring rolling surface 33 is formed to be substantially the same as or slightly larger than the radius of curvature of the outer surface of the rolling element 14. The inner ring rolling surface 33 is formed over the entire circumference of the outer peripheral surface 32 of the inner ring 22. The outer surfaces of a plurality of rolling elements 14 can abut against the inner ring rolling surface 33.

[0038] When the inner ring 22 is fixed to the support shaft 41, the coating layer 18 rotates together with the outer ring 21. The coated outer peripheral surface 52c of the coating layer 18 (second material layer 44) is, for example, a surface for conveying banknotes, tickets, etc., or rolling the contact object 5 (see FIG. 4).

[0039] The rolling elements 14 are formed into a spherical shape from a metallic material such as stainless steel or a ceramic material such as zirconia. A plurality of rolling elements 14 are arranged between the outer ring rolling surface 29 of the outer ring 21 and the inner ring rolling surface 33 of the inner ring 22, and roll along the outer ring rolling surface 29 and the inner ring rolling surface 33. The plurality of rolling elements 14 are circumferentially and evenly arranged in a ring shape by a retainer 16 so as to be freely rotatable. Grease for lubrication is enclosed in the bearing 10.

[0040] A coating layer 18 is formed on the outer peripheral surface 24 of the outer ring 21. The coating layer 18 includes a first material layer 43 and a second material layer 44. The second material layer 44 forms the outer peripheral surface layer of the coating layer 18. The first material layer 43 is insert-molded by injection molding at the center in the direction of the axis O of the outer peripheral surface 24 of the outer ring 21. The first material layer 43 has a first outer peripheral surface 46, a first inner peripheral surface 47, and a pair of side surfaces 48, 49. Hereinafter, one of the pair of side surfaces 48, 49 is referred to as the first side surface 48, and the other side surface is referred to as the second side surface 49.

[0041] The first inner peripheral surface 47 is welded to the outer peripheral surface 24 and the groove portion 28 of the outer ring 21 by insert molding. The first outer peripheral surface 46 is formed in an arc shape so as to have a predetermined thickness dimension with respect to the outer peripheral surface 24 of the outer ring 21. That is, the first outer peripheral surface 46 is formed linearly so as to be parallel to the axis O in the direction of the axis O of the bearing 10. The first side surface 48 is a surface that connects one end of the first outer peripheral surface 46 and one end of the first inner peripheral surface 47 and is formed so as to intersect the direction of the axis O of the bearing 10. The first side surface 48 is formed at an interval S1 from the first edge 24a of the outer peripheral surface 24 toward the center side of the outer peripheral surface 24 in the direction of the axis O. The second side surface 49 is formed at an interval S1 from the second edge 24b of the outer peripheral surface 24 toward the center side of the outer peripheral surface 24 in the direction of the axis O.

[0042] The first material layer 43 is formed of, for example, a rigid plastic. In particular, an amorphous plastic is preferable because it has excellent heat fusion properties with a thermoplastic elastomer. As the amorphous plastic, polycarbonate, ABS resin, or an alloy material of polycarbonate and ABS resin is preferable. Since the first material layer 43 is cooled and a force is applied so as to be in close contact with the center of the outer ring 21 toward the outer peripheral surface 24 (in the radial direction), the first material layer 43 is welded to the outer peripheral surface 24 and the groove portion 28 of the outer ring 21 by injection molding. The first material layer 43 is formed in an annular shape of a rigid plastic along the outer peripheral surface 24. Therefore, due to the shrinkage when the first material layer 43 is cooled and cured, the first material layer 43 is firmly attached to the outer peripheral surface 24. The groove portion 28 is filled with the first material layer 43. By filling the protrusion 43a of the first material layer 43 into the groove portion 28 of the outer peripheral surface 24, the groove portion 28 of the outer peripheral surface 24 and the protrusion 43a of the first material layer 43 can be engaged with each other in a concave-convex shape.

[0043] Here, when the first material layer 43 is insert-molded onto the outer peripheral surface 24 and the groove portion 28 of the outer ring 21, the bearing 10 is housed inside the mold, and at least the end faces 21a and 21b in the axial direction O of the outer ring 21 are in contact with and supported by the mold. In this way, since the end faces 21a and 21b are supported by the mold, the first material layer 43 is insert-molded onto the outer peripheral surface 24 and the groove portion 28 of the outer ring 21. Also, the first material layer 43 may be insert-molded with respect to the outer ring 21 alone.

[0044] In addition, by filling the protrusion 43a of the first material layer 43 into the groove portion 28, the filled protrusion 43a in the groove portion 28 serves as an anchor. Thereby, the first material layer 43 can be firmly fixed to the outer peripheral surface 24 and the groove portion 28 of the outer ring 21. In a state where the first material layer 43 is provided on the outer peripheral surface 24 of the outer ring 21, the first side portion 24c and the second side portion 24d, which are located on both sides in the axial direction O of the first material layer 43, of the outer peripheral surface 24 are exposed to the outside.

[0045] The first material layer 43 has a second material layer 44 formed on the first side portion 24c and the second side portion 24d of the outer peripheral surface 24. The second material layer 44 has an outer peripheral surface layer 52 and a pair of side surface layers 53, 54. Hereinafter, one of the pair of side surface layers 53, 54, the first side surface layer, is referred to as the first side surface layer 53, and the other side surface layer is referred to as the second side surface layer 54. The outer peripheral surface layer 52 is a layer that covers the first outer peripheral surface 46 of the first material layer 43. The first side surface layer 53 is a layer that is connected to one end portion 52a of the outer peripheral surface layer 52 and covers the first side surface 48 of the first material layer 43. The first side surface layer 53 is in contact with the first side portion 24c of the outer peripheral surface 24 of the outer ring 21. The second side surface layer 54 is a layer that is connected to the other end portion 52b of the outer peripheral surface layer 52 and covers the second side surface 49 of the first material layer 43. The second side surface layer 54 is in contact with the second side portion 24d of the outer peripheral surface 24 of the outer ring 21. That is, both side surfaces (the first side surface 48 and the second side surface 49) of the first material layer 43 are sandwiched by the first side surface layer 53 and the second side surface layer 54 of the second material layer 44.

[0046] The second material layer 44 is formed of a thermoplastic elastomer (TPE). The thermoplastic elastomer has excellent heat fusion properties with the amorphous plastic that is the material of the first material layer 43. As the thermoplastic elastomer, styrene-based (TPS), olefin-based (TPO), vinyl chloride-based (PPVC), urethane-based (TPU), and polyester-based (TPEE) are applicable. From the viewpoints of mechanical strength and wear resistance, urethane-based (TPU), polyester-based (TPEE), and styrene-based (TPS) are preferable. Further preferable thermoplastic elastomer includes polyester-based (TPEE). The urethane-based (TPU) is most excellent in wear resistance but has problems in moldability, has high hygroscopicity and requires sufficient drying. Further, annealing treatment is also required, which takes time in manufacturing and also has problems in molding accuracy. Also, the urethane-based is most excellent in mechanical strength and wear resistance among thermoplastic elastomers. For this reason, the urethane-based is used when the coating layer 18 requires characteristics of mechanical strength and wear resistance.

[0047] Polyester-based (TPEE) has the best wear resistance and mechanical strength among thermoplastic elastomers excluding urethane, and also has excellent heat fusion properties with hard plastics. In addition, polyester-based (TPEE) has low hygroscopicity and good moldability, making it optimal as the material for the coating layer 18.

[0048] Here, as the thermoplastic elastomer of the second material layer 44, polyester-based (TPEE) is preferred. Polyester-based has excellent wear resistance and mechanical strength, and also has excellent heat fusion properties with hard plastics (i.e., the first material layer 43). Heat fusion means, for example, that the thermoplastic elastomer of the second material layer 44 melts by heating and adheres to the hard plastic (the first material layer 43). Therefore, it exerts an effect during two-color molding. In addition, polyester-based (TPEE) has low hygroscopicity and good moldability, making it optimal as the material for the second material layer 44 of the bearing 10. From the viewpoint of suppressing noise, the Shore hardness A of the second material layer 44 is preferably 75 to 95. For example, setting the Shore hardness A to 92 is particularly preferable from the viewpoints of suppressing noise well and ensuring good mechanical strength and wear resistance of the second material layer 44. If the Shore hardness A is less than 75, it is conceivable that the mechanical strength and wear resistance of the second material layer 44 will become problematic.

[0049] The thermoplastic elastomer of the second material layer 44 is a softer material than the amorphous plastic (hard plastic) of the first material layer 43. That is, a hard amorphous plastic can be used for the first material layer 43. Therefore, the first material layer 43 is injection-molded in a molten state on the outer peripheral surface 24 of the outer ring 21, and after injection molding, the molten first material layer 43 cools and solidifies, causing the annular first material layer 43 to contract. Therefore, the first material layer 43 can be firmly fixed to the outer peripheral surface 24 of the outer ring 21. A soft material refers to a material with a small flexural modulus and hardness (e.g., Shore hardness A (durometer hardness A)). A hard material refers to a material having a large flexural modulus and hardness (e.g., Shore hardness A (durometer hardness A)).

[0050] Further, by providing a groove portion 28 on the outer peripheral surface 24 of the outer ring 21, the first material layer 43 can be filled in the groove portion 28. When the protrusion 43a of the first material layer 43 is filled in the groove portion 28 of the outer peripheral surface 24, the groove portion 28 of the outer peripheral surface 24 and the protrusion 43a of the first material layer 43 can be engaged in a concavo-convex shape. Therefore, when a force is applied to the first material layer 43, the first material layer 43 can be prevented from coming off the outer ring 21 due to the concavo-convexity between the outer peripheral surface 24 and the first material layer 43.

[0051] Here, the second material layer 44 is formed in an annular shape along the first material layer 43 and is a material softer than the first material layer 43. Therefore, the second material layer 44 can be firmly heat-sealed to the first material layer 43 by injection molding (two-color molding). Also, both side surfaces (the first side surface 48 and the second side surface 49) of the first material layer 43 are sandwiched by the first side surface layer 53 and the second side surface layer 54 of the second material layer 44. Therefore, when the second material layer 44 cools and shrinks after injection molding, the first side surface 48 and the second side surface 49 of the first material layer 43 can be sandwiched by the first side surface layer 53 and the second side surface layer 54 of the second material layer 44. Thereby, the second material layer 44 can be more firmly engaged with the first material layer 43.

[0052] Furthermore, the inner peripheral surface 53a of the first side surface layer 53 of the second material layer 44 is welded to the first side portion 24c of the outer peripheral surface 24 of the outer ring 21. The inner peripheral surface 54a of the second side surface layer 54 of the second material layer 44 is welded to the second side portion 24d of the outer peripheral surface 24 of the outer ring 21. That is, the height dimension H1 of the first side surface layer 53 and the second side surface layer 54 is ensured to be large. Therefore, a large contact area of the first side layer 53 with respect to the first side 48 is ensured. A large contact area of the second side layer 54 with respect to the second side 49 is ensured. As a result, when the second material layer 44 cools and contracts, the entire first side 48 and the entire second side 49 can be sandwiched between the first side layer 53 and the second side layer 54. As a result, the second material layer 44 can be more firmly engaged with the first material layer 43. Therefore, even when a force in the direction of the axis O or a force in the direction of peeling from the outer peripheral surface 24 of the outer ring 21 is applied to the second material layer 44, the second material layer 44 can be made difficult to peel from the outer peripheral surface 24 of the outer ring 21.

[0053] In this way, by interposing the hard first material layer 43 between the outer peripheral surface 24 of the outer ring 21 and the second material layer 44, the second material layer 44 can be firmly engaged with the outer peripheral surface 24 of the outer ring 21 via the first material layer 43. Thereby, it is possible to prevent the first material layer 43 and the second material layer 44 from falling off from the outer peripheral surface 24 of the outer ring 21.

[0054] Furthermore, by firmly engaging the second material layer 44 with the outer peripheral surface 24 of the outer ring 21 via the first material layer 43, the sandblasting process and the coating process using an adhesive, which were conventionally required, can be made unnecessary. Also, when the first material layer 43 and the second material layer 44 are injection molded by, for example, two-color molding, it is not necessary to cure the amorphous plastic of the first material layer 43 and the thermoplastic elastomer of the second material layer 44 in the mold for a long time like urethane rubber. That is, when the first material layer 43 and the second material layer 44 are injection molded, the process of curing in the mold for a long time like urethane rubber can be made unnecessary. Thereby, the bearing 10 having the coating layer 18 (the first material layer 43, the second material layer 44) formed on the outer peripheral surface 24 of the outer ring 21 can be manufactured inexpensively and in large quantities.

[0055] As described above, the first material layer 43 and the second material layer 44 of the coating layer 18 are formed, for example, by two-color molding. Specifically, the first material layer 43 is insert-molded on the outer peripheral surface 24 of the outer ring 21 by injection molding of an amorphous plastic. After the first material layer 43 is insert-molded, the second material layer 44 is insert-molded by injection molding of a thermoplastic elastomer. A mold is used to injection-mold the first material layer 43 and the second material layer 44. In particular, for the mold for injection-molding the second material layer 44, for example, the gate G1 is disposed at a position corresponding to the first side surface layer 53 of the second material layer 44. By filling the molten thermoplastic elastomer from the gate G1 into the inside (cavity) of the mold, the second material layer 44 is insert-molded on the first material layer 43 and the first side portion 24c and the second side portion 24d of the outer peripheral surface 24. By providing the gate G1 of the mold at a position corresponding to the first side surface layer 53, the filling position of the thermoplastic elastomer can be shifted from the coated outer peripheral surface 52c of the outer peripheral surface layer 52.

[0056] Also, the parting line PL of the mold is positioned, for example, on the outer surface 53b of the first side surface layer 53 in the direction of the axis O of the bearing 10. The outer surface 53b of the first side surface layer 53 is formed as a recess at one end 52d of the coated outer peripheral surface 52c with respect to the coated outer peripheral surface 52c of the outer peripheral surface layer 52. The parting line PL is disposed at a position shifted from the coated outer peripheral surface 52c of the outer peripheral surface layer 52. In this way, by shifting the gate G1 and the parting line PL from the coated outer peripheral surface 52c of the outer peripheral surface layer 52, burrs generated when filling the thermoplastic elastomer into the mold from the gate G1, burrs generated by the parting line PL, etc. can be prevented from occurring on the coated outer peripheral surface 52c of the outer peripheral surface layer 52. As a result, post-processing for removing burrs from the coated outer peripheral surface 52c of the outer peripheral surface layer 52 can be made unnecessary. Here, the interval between the outer surface 53b of the first side surface layer 53 and the inner peripheral surface 54a of the second side surface layer 54 is the width dimension of the coating layer 18. The width dimension of the coating layer 18 is set to be the same as the width dimension of the ring body 12.

[0057] Incidentally, when injection molding amorphous plastics or thermoplastic elastomers, the mold temperature can be kept low at 150°C or lower (preferably 100°C or lower). Further, when the molten amorphous plastic or thermoplastic elastomer is filled into the mold from gate G1, the amorphous plastic or thermoplastic elastomer instantaneously solidifies. Therefore, the high temperature of the molten amorphous plastic or thermoplastic elastomer can be prevented from reaching the grease encapsulated in the bearing 10. Accordingly, there is no risk of deteriorating the grease due to the high temperature of the molten amorphous plastic or thermoplastic elastomer.

[0058] Here, by welding the coating layer 18 (the first material layer 43, the second material layer 44) to the outer peripheral surface 24, it is not necessary to adhere the coating layer 18 to the outer peripheral surface 24 with an adhesive. By not interposing an adhesive between the coating layer 18 and the outer peripheral surface 24, the following effects can be obtained. That is, in the case of a small bearing, for example, when the coating layer is adhered to the outer peripheral surface with an adhesive, there is a possibility that the adhesive cannot be applied to the outer peripheral surface with a uniform thickness dimension due to uneven application of the adhesive. On the other hand, in the case of a small bearing, it is conceivable that the thickness dimension of the coating layer becomes smaller than 1.0 mm. In this state, when the adhesive is not applied to the outer peripheral surface with a uniform thickness dimension, it is conceivable that the hardness of the coating layer becomes non-uniform. For this reason, when conveying an object with a small bearing coated with the coating layer 18 or when rolling the coating layer along a contact object, there is a risk of generating noise or causing torque unevenness.

[0059] In contrast, by welding the coating layer 18 (the first material layer 43, the second material layer 44) to the outer peripheral surface 24, the adhesive can be made unnecessary. Thereby, even when the bearing 10 is small and the thickness dimension of the coating layer 18 is smaller than 1.0 mm, it becomes possible to keep the hardness of the coating layer 18 uniform over the entire circumference. Thereby, even when the bearing 10 is formed small, it is possible to suppress the generation of noise and the cause of torque unevenness when conveying an object with the bearing 10 or when rolling the bearing 10 along a contact object. In the first embodiment, an example in which the coating layer 18 (the first material layer 43 and the second material layer 44) is provided on the outer peripheral surface 24 only by welding will be described. However, depending on the use of the bearing 10, for example, an adhesive may be used in combination with welding to provide the coating layer 18 on the outer peripheral surface 24.

[0060] In the first embodiment, an example in which polycarbonate or the like is used as the hard plastic (amorphous plastic) for the first material layer 43 of the coating layer 18 has been described. However, for example, a thermoplastic elastomer may be used in the same manner as the second material layer 44. Therefore, the first material layer 43 and the second material layer 44 can be better heat-sealed together. As a result, the second material layer 44 can be more firmly fixed to the first material layer 43, and it is possible to more reliably prevent the second material layer 44 from falling off the outer peripheral surface 24 of the outer ring 21.

[0061] Here, for example, in order to ensure the wear amount of the second material layer 44, as shown in Table 1 and FIG. 2, it is also possible to contain potassium titanate fibers in the thermoplastic elastomer. Table 1 is a table showing the characteristics of the state in which the second material layer 44 of the present invention contains potassium titanate fibers. FIG. 2 is a graph showing the characteristics of the state in which the second material layer 44 contains potassium titanate fibers. In Table 1 and FIG. 2, a thermoplastic elastomer (polyester-based (TPEE)) that does not contain potassium titanate fibers is shown as the elastomer (single body). A thermoplastic elastomer containing 10 wt% of potassium titanate fibers is shown as the elastomer (10 wt%). Further, a thermoplastic elastomer containing 20 wt% of potassium titanate fibers is shown as the elastomer (20 wt%). A thermoplastic elastomer containing 30 wt% of potassium titanate fibers is shown as the elastomer (30 wt%).

[0062]

Table 1

[0063] In Table 1 and Figure 2, the properties of the elastomer (alone), elastomer (10 wt%), elastomer (20 wt%), and elastomer (30 wt%) are shown. By containing 10 wt%, 20 wt%, and 30 wt% of potassium titanate fibers in the thermoplastic elastomer, the tensile strength can be increased from 12 Mpa to 13 MPa, 18 MPa, and 23 MPa. Also, the flexural strength can be increased from 4 MPa to 7 MPa, 9 MPa, and 16 MPa. Furthermore, the flexural modulus can be increased from 0.05 GPa to 0.13 GPa, 0.21 GPa, and 0.44 GPa.

[0064] Also, the graph in Figure 2 shows the wear amount and durometer hardness A of the thermoplastic elastomer alone and the state in which the thermoplastic elastomer contains 10 wt%, 20 wt%, and 30 wt% of potassium titanate fibers. As shown in Figure 2 and Table 1, in the state where the thermoplastic elastomer contains 10 wt%, 20 wt%, and 30 wt% of potassium titanate fibers, the durometer hardness A of the thermoplastic elastomer can be ensured to be approximately the same as 94 to 96, 97, and 98. Furthermore, as shown in Figure 2 and Table 1, in the state where the thermoplastic elastomer contains 10 wt%, 20 wt%, and 30 wt% of potassium titanate fibers, the wear amount of the thermoplastic elastomer is 12.5×10 -3 cm 3 to 10.1×10 -3 cm 3 , 7.0×10 -3 cm 3 , 3.8×10 -3 cm 3 and can be decreased.

[0065] Here, the wear amount of the thermoplastic elastomer is measured by a reciprocating sliding test. The reciprocating sliding test conditions are to select a glass plate as the counter material and perform a reciprocating sliding test for 20 minutes at a load of 0.7 kg and a speed of 0.16 m / s. Note that the content of the potassium titanate fibers is appropriately selected according to the use of the bearing 10.

[0066] (Modified Example) Next, a modified example of the bearing 10 of the first embodiment will be described. FIG. 3 is a side view showing a modified example of the bearing according to the first embodiment. As shown in FIG. 3, as the bearing 10 of the first embodiment, an example in which the second material layer 44 is formed of a thermoplastic elastomer has been described. However, as another example, a plurality of teeth 57 for gears can be formed on the outer circumferential surface of the second material layer 44. Thereby, the bearing 10 can be used as a gear 55. The gear 55 can be used, for example, as a small planetary gear (planetary gear) inside a planetary gear mechanism. The gear 55 has a plurality of teeth 57 formed of a thermoplastic elastomer. Thereby, it is possible to reduce the driving noise generated when the gears 55 mesh with each other. In addition, as the second material layer 44 forming the plurality of teeth 57, it is also possible to use a thermoplastic elastomer having a durometer hardness A exceeding 95 in consideration of the wear resistance, mechanical strength, etc. of the gear 55.

[0067] Next, an example of the use of the bearing 10 of the first embodiment will be described with reference to FIG. 4. FIG. 4 is a side view showing a moving body 1 including the bearing 10 according to the first embodiment. As shown in FIG. 4, for example, the bearing 10 is attached to a moving body (drive module) 1 and used as a wheel. The moving body 1 includes a main body portion 2 and a plurality of bearings 10 attached to both sides of the main body portion 2. The plurality of bearings 10 are fixed by attaching the inner ring 22 to the support shaft 3. The support shaft 3 is attached to the main body portion 2. By fixing the inner ring 22 to the support shaft 3, the outer ring 21 and the coating layer 18 are rotatably supported by the support shaft 3. That is, the plurality of bearings 10 are used as wheels.

[0068] The moving body 1 is arranged in a state where the coating layer 18 (specifically, the second material layer 44) of the plurality of bearings 10 is in contact with the contact object 5. The second material layer 44 is formed of a thermoplastic elastomer. By rolling the outer ring 21 and the coating layer 18 of the bearing 10 along the contact object 5, the moving body 1 can be moved along the contact object 5. Since the covering layer 18 is formed on the outer ring 21, when the bearing 10 moves while rolling on the contact object 5, the covering layer 18 (particularly, the second material layer 44) can reduce the sound (noise). Also, since the covering layer 18 is firmly engaged with the outer peripheral surface 24 of the outer ring 21, it is possible to prevent the covering layer 18 from peeling off from the outer peripheral surface 24 of the outer ring 21. In this way, by providing the moving body 1 with a plurality of bearings 10, it is possible to ensure durability and obtain a low-cost moving body 1.

[0069] In FIG. 4, an example was described in which the covering layer 18 of the bearing 10 was rotated in a state of being in contact with the contact object 5 and the moving body 1 was moved along the contact object 5, but the present invention is not limited to this. As another example, the moving body 1 may be held in a fixed state, the covering layer 18 may be brought into contact with the contact object 5, and the contact object 5 may be moved by the rotation of the covering layer 18. In this case, when the drawer of a desk is used as the contact object 5, it corresponds to this case. Also in this state, the sound (noise) can be reduced by the covering layer 18. Also, as another example, the bearing 10 may be applied to a bicycle in which the traveling direction can turn. By applying the bearing 10 to the bicycle, the bearing 10 can be turned corresponding to the traveling direction of the moving body 1.

[0070] Furthermore, as an example of other applications, the bearing 10 is used in a conveying device (drive module) for banknotes, tickets, etc. That is, in the conveying device, the inner rings 22 of a pair of bearings 10 are attached to the support shaft 3, and the outer ring 21 and the covering layer 18 are rotatably supported by the support shaft. The pair of covering layers 18 are arranged adjacent to each other. In this state, when the outer ring 21 and the covering layer 18 rotate, banknotes, tickets, etc. are sandwiched between the pair of covering layers 18 and conveyed.

[0071] Since the covering layer 18 is formed on the outer ring 21, when conveying while sandwiching banknotes, tickets, etc. between the covering layers 18 of the bearing 10, the covering layer 18 can reduce the sound (noise). Also, since the covering layer 18 is firmly engaged with the outer peripheral surface 24 of the outer ring 21, it is possible to prevent the covering layer 18 from peeling off from the outer peripheral surface 24 of the outer ring 21. Thus, by providing the bearing 10 in the conveying device, it is possible to ensure durability and obtain a low-cost conveying device.

[0072] Next, the bearings of the second to sixth embodiments and the structures with the thermoplastic elastomer coating layer of the seventh to eighth embodiments will be described with reference to FIGS. 5 to 11. In the bearings of the second to sixth embodiments, the same or similar members as the bearing 10 of the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0073] (Second Embodiment) FIG. 5 is a cross-sectional view of a bearing 70 according to the second embodiment. As shown in FIG. 5, the bearing 70 is obtained by replacing the coating layer 18 of the first embodiment with a coating layer 72, and the other configurations are the same as those of the bearing 10 of the first embodiment. The coating layer 72 is obtained by replacing the first material layer 43 and the second material layer 44 of the first embodiment with a first material layer 73 and a second material layer 74.

[0074] The first material layer 73 has a first outer peripheral surface 76, a first inner peripheral surface 77, a first side surface 78, and a second side surface 79. The first outer peripheral surface 76 is formed in the same manner as the first outer peripheral surface 46 of the first material layer 43. The first inner peripheral surface 77 is formed in the same manner as the first inner peripheral surface 47 of the first material layer 43. The first inner peripheral surface 77 is formed smaller than the length dimension of the first outer peripheral surface 76.

[0075] The first side surface 78 extends in an inclined shape with an inclination angle θ1 from one end 77a of the first inner peripheral surface 77 to one end 76a of the first outer peripheral surface 76, outward from the center in the direction of the axis O of the outer ring 21. The second side surface 79 extends in an inclined shape with an inclination angle θ1 from the other end 77b of the first inner peripheral surface 77 to the other end 76b of the first outer peripheral surface 76, outward from the center in the direction of the axis O of the outer ring 21. The inclination angle θ1 of the first side surface 78 and the second side surface 79 is set to be less than 90 degrees. That is, the first material layer 73 is formed such that the width dimension W1 gradually increases radially outward from the outer peripheral surface 24 of the outer ring 21.

[0076] The second material layer 74 forms the outer peripheral surface layer of the coating layer 72. The second material layer 74 has an outer peripheral surface layer 82, a first side surface layer 83, and a second side surface layer 84. The outer peripheral surface layer 82 is formed in the same manner as the outer peripheral surface layer 52 of the second material layer 44. The first side surface layer 83 has a first inner side surface 83a formed in an inclined shape so as to contact the first side surface 78. The second side surface layer 84 has a second inner side surface 84a formed in an inclined shape so as to contact the first side surface 78. Therefore, when the second material layer 74 contracts due to cooling, the first side surface layer 83 (particularly, the first inner side surface 83a) can be preferably bitten into the first side surface 78. Also, the second side surface layer 84 (particularly, the second inner side surface 84a) can be preferably bitten into the second side surface 79.

[0077] According to the bearing 70 of the second embodiment, the second material layer 74 is more firmly fixed to the first material layer 73. As a result, it is possible to more reliably prevent the second material layer 74 from falling off from the first material layer 73 (that is, the outer peripheral surface 24 of the outer ring 21). Also, according to the bearing 70 of the second embodiment, similar to the bearing 10 of the first embodiment, a large number of bearings 70 having the coating layer 72 formed on the outer peripheral surface 24 of the outer ring 21 can be manufactured inexpensively.

[0078] (Third Embodiment) FIG. 6 is a cross-sectional view of a bearing 90 according to the third embodiment. As shown in FIG. 6, the bearing 90 is obtained by replacing the coating layer 18 of the first embodiment with a coating layer 92, and the other configuration is the same as that of the bearing 10 of the first embodiment. The coating layer 92 is obtained by replacing the first material layer 43 and the second material layer 44 of the first embodiment with a first material layer 93 and a second material layer 94.

[0079] The first material layer 93 has a first outer peripheral surface 96, a first inner peripheral surface 97, a first concave surface 98, and a second concave surface 99. The first outer peripheral surface 96 is formed in the same manner as the first outer peripheral surface 46 of the first material layer 43. The first inner peripheral surface 97 is similar to the first inner peripheral surface 47 of the first material layer 43 and is formed with the same width as the outer peripheral surface 24 of the outer ring 21. A large contact area is ensured between the first inner peripheral surface 97 and the outer peripheral surface 24 of the outer ring 21. Thus, the first material layer 43 is firmly fixed to the outer peripheral surface 24 of the outer ring 21 by cooling and shrinking after injection molding.

[0080] The first concave surface 98 is formed as a concave stepped portion by a first side surface 98a and a first circumferential surface 98b. The second concave surface 99 is formed as a concave stepped portion by a second side surface 99a and a second circumferential surface 99b. The height dimension of the first material layer 93 from the first inner peripheral surface 97 to the first outer peripheral surface 96 is H2. The height dimension H2 of the first material layer 93 is set to be larger than that of the first material layer 43 in the first embodiment.

[0081] The second material layer 94 is formed in the same manner as the second material layer 44 in the first embodiment. That is, the second material layer 94 forms an outer peripheral surface layer of the coating layer 92. The second material layer 94 has an outer peripheral surface layer 52, a first side surface layer 53, and a second side surface layer 54, similar to the second material layer 44. When the second material layer 94 cools and shrinks, the entire areas of the first side surface 98a and the second side surface 99a can be sandwiched between the first side surface layer 53 and the second side surface layer 54. Also, the inner peripheral surface 53a of the first side surface layer 53 is thermally fused to the first circumferential surface 98b. The inner peripheral surface 54a of the second side surface layer 54 is thermally fused to the second circumferential surface 99b. Thereby, the second material layer 94 can be firmly engaged with the first material layer 93.

[0082] In this way, the first material layer 93 is firmly fixed to the outer peripheral surface 24 of the outer ring 21 by cooling and shrinking after injection molding. Further, the second material layer 94 is firmly engaged with the first material layer 93. In particular, by thermally fusing the inner peripheral surface 53a of the first side surface layer 53 to the first circumferential surface 98b and the inner peripheral surface 54a of the second side surface layer 54 to the second circumferential surface 99b, the second material layer 94 is more firmly engaged with the first material layer 93. As a result, it is possible to make the second material layer 94 more difficult to separate from the first material layer 93.

[0083] According to the bearing 90 of the third embodiment, the second material layer 94 can be firmly engaged with the outer peripheral surface 24 of the outer ring 21 via the first material layer 93. As a result, it is possible to prevent the coating layer 92 from coming off the outer peripheral surface 24 (that is, the outer ring 21). Further, according to the bearing 90 of the third embodiment, similarly to the bearing 10 of the first embodiment, a large number of bearings 90 having the coating layer 92 formed on the outer peripheral surface 24 of the outer ring 21 can be manufactured inexpensively.

[0084] (Fourth Embodiment) FIG. 7 is a cross-sectional view of a bearing 110 according to the fourth embodiment. As shown in FIG. 7, the bearing 110 is obtained by replacing the coating layer 18 of the first embodiment with a coating layer 112, and other configurations are the same as those of the bearing 10 of the first embodiment. The coating layer 112 is obtained by replacing the first material layer 43 and the second material layer 44 of the first embodiment with a first material layer 113 and a second material layer 114.

[0085] The first material layer 113 has a first outer peripheral surface 116, a first inner peripheral surface 117, a first side surface 118, and a second side surface 119. The first outer peripheral surface 116 is the same as the first outer peripheral surface 46 of the first material layer 43 and is formed to have the same width as the outer peripheral surface 24 of the outer ring 21. The first inner peripheral surface 117 is the same as the first inner peripheral surface 47 of the first material layer 43 and is formed to have the same width as the outer peripheral surface 24 of the outer ring 21. The first inner peripheral surface 117 ensures a large contact area with the outer peripheral surface 24 of the outer ring 21. Therefore, the first material layer 113 is firmly fixed to the outer peripheral surface 24 of the outer ring 21 by cooling and shrinking after injection molding.

[0086] The second material layer 114 forms the outer peripheral surface layer of the coating layer 112. Similar to the second material layer 44 of the first embodiment, the second material layer 114 has an outer peripheral surface layer 122, a first side surface layer 123, and a second side surface layer 124. The outer peripheral surface layer 122 is formed in the same manner as the outer peripheral surface layer 52 of the first embodiment and protrudes outward in the direction of the axis O from both end edges (i.e., the first end edge 24a and the second end edge 24b) of the outer peripheral surface 24 of the outer ring 21. The first side surface layer 123 is in contact with the first side surface 118 of the first material layer 113. The second side surface layer 124 is in contact with the second side surface 119 of the first material layer 113.

[0087] When the second material layer 114 cools and contracts, the entire areas of the first side surface 118 and the second side surface 119 can be sandwiched between the first side surface layer 123 and the second side surface layer 124. Thereby, the second material layer 114 can be firmly engaged with the first material layer 113. In this way, the first material layer 113 is firmly fixed to the outer peripheral surface 24 of the outer ring 21 by cooling and contracting after injection molding. Also, the second material layer 114 is firmly engaged with the first material layer 113.

[0088] According to the bearing 110 of the fourth embodiment, the second material layer 114 can be firmly engaged with the outer peripheral surface 24 of the outer ring 21 via the first material layer 113. Thereby, it is possible to prevent the coating layer 112 from falling off from the outer peripheral surface 24 (i.e., the outer ring 21). Also, according to the bearing 110 of the fourth embodiment, similar to the bearing 10 of the first embodiment, a large number of bearings 110 having the coating layer 112 formed on the outer peripheral surface 24 of the outer ring 21 can be manufactured inexpensively.

[0089] (Fifth Embodiment) FIG. 8 is a cross-sectional view of a bearing 130 according to the fifth embodiment. As shown in FIG. 8, the bearing 130 has the coating layer 112 of the fourth embodiment replaced with a coating layer 132, and other configurations are the same as those of the bearing 110 of the fourth embodiment. The coating layer 132 has the second material layer 114 of the fourth embodiment replaced with a second material layer 134, and further includes a first material layer 113 similar to that of the fourth embodiment. Similar to the fourth embodiment, the first material layer 113 is firmly fixed to the outer peripheral surface 24 of the outer ring 21 by cooling and shrinking after injection molding.

[0090] The second material layer 134 forms the outer peripheral surface layer of the coating layer 132. The second material layer 134 is the same as the outer peripheral surface layer 122 of the fourth embodiment and is formed smaller than the length dimension of the outer peripheral surface layer 122. The second material layer 134 has a first layer side surface 136 and a second layer side surface 137. The first layer side surface 136 is flush with the first edge 24a of the outer peripheral surface 24 of the outer ring 21. The second layer side surface 137 is flush with the second edge 24b of the outer peripheral surface 24 of the outer ring 21. That is, the second material layer 134 is formed with the same width dimension W2 as the outer peripheral surface 24 of the outer ring 21 and the first material layer 113. The second material layer 134 is firmly engaged with the first outer peripheral surface 116 of the first material layer 113 by heat fusion.

[0091] In this way, the first material layer 113 is firmly fixed to the outer peripheral surface 24 of the outer ring 21 by cooling and shrinking after injection molding. Also, the second material layer 134 is firmly engaged with the first material layer 113. Thereby, according to the bearing 130 of the fifth embodiment, the second material layer 134 can be firmly engaged with the outer peripheral surface 24 of the outer ring 21 via the first material layer 113.

[0092] (Sixth Embodiment) FIG. 9 is a cross-sectional view of a bearing 140 according to the sixth embodiment. As shown in FIG. 9, the bearing 140 has the coating layer 18 of the first embodiment replaced with a coating layer 142, and the other configurations are the same as those of the bearing 10 of the first embodiment. The coating layer 142 has the second material layer 44 of the first embodiment replaced with a second material layer 144, and further includes a first material layer 43 similar to that of the first embodiment.

[0093] The second material layer 144 forms the outer peripheral surface layer of the coating layer 142. The second material layer 144 has an outer peripheral surface layer 146, a first side surface layer 53, and a second side surface layer 54. The outer peripheral surface layer 146 has the outer peripheral surface of the outer peripheral surface layer 52 of the first embodiment replaced with a curved coating outer peripheral surface 147, and the other parts are the same as those of the outer peripheral surface layer 52 of the first embodiment. The coating outer peripheral surface 147 has a first end 147a and a second end 147b. The coating outer peripheral surface 147 is formed in a curved shape such that the outer diameter gradually decreases from the first end 147a to the second end 147b. The coating outer peripheral surface 147 may be formed linearly such that the outer diameter gradually decreases.

[0094] The mold parting line PL is located at the first end 147a. That is, the coating outer peripheral surface 147 is formed in a curved shape such that the outer diameter gradually decreases from the parting line PL to the second end 147b. Therefore, after insert molding the coating layer 142 (the first material layer 43, the second material layer 144), by opening the movable mold of the mold in the arrow direction, it is possible to suppress the generation of burrs on the coating outer peripheral surface 147. Thereby, after insert molding the coating layer 142 (the first material layer 43, the second material layer 144) on the outer peripheral surface 24 of the outer ring 21, post-processing for removing burrs from the coating outer peripheral surface 147 can be made unnecessary.

[0095] According to the bearing 140 of the sixth embodiment, the outer diameter of the coated outer peripheral surface 147 is formed to gradually decrease. Therefore, when transporting banknotes, tickets, etc. with the coated outer peripheral surface 147, or when the coated outer peripheral surface 147 moves while rolling a contacting object, the contact area with respect to banknotes, tickets, contacting objects, etc. can be kept small. As a result, when transporting banknotes, tickets, etc. with the coated outer peripheral surface 147, or when the coated outer peripheral surface 147 moves while rolling a contacting object, an effect of reducing noise can be obtained.

[0096] Also, according to the bearing 140 of the sixth embodiment, the second material layer 144 can be firmly engaged with the outer peripheral surface 24 of the outer ring 21 via the first material layer 43. Thereby, it is possible to prevent the coating layer 142 from coming off from the outer peripheral surface 24 (that is, the outer ring 21). Also, according to the bearing 140 of the sixth embodiment, similarly to the bearing 10 of the first embodiment, a large number of bearings 140 in which the coating layer 142 is formed on the outer peripheral surface 24 of the outer ring 21 can be manufactured inexpensively.

[0097] In the first to sixth embodiments, an example in which the coating layers 18, 72, 92, 112, 132, 142 are formed on the bearings 10, 70, 90, 110, 130, 140 as a structure with a thermoplastic elastomer coating layer has been described, but it is not limited thereto. Coating layers 154, 164 may be formed on the cylindrical member 152 and the flat member 162 as in the seventh and eighth embodiments.

[0098] (Seventh Embodiment) FIG. 10 is a cross-sectional view of a structure 150 with a thermoplastic elastomer coating layer according to the seventh embodiment. As shown in FIG. 10, in the structure 150 with a thermoplastic elastomer coating layer, a coating layer 154 is formed on the outer peripheral surface (that is, the outer surface formed in a circular shape) 153 of the cylindrical member 152. The cylindrical member 152 is made of a metal material such as stainless steel, for example. The coating layer 154 includes a first material layer 155 formed on the outer peripheral surface 153 and a second material layer 156 formed on the first outer peripheral surface 155a of the first material layer 155.

[0099] The first material layer 155 is formed of the same amorphous plastic as the first material layer 43 (see FIG. 1) of the first embodiment. The second material layer 156 forms the outer peripheral surface layer of the coating layer 154. The second material layer 156 is formed of the same thermoplastic elastomer as the second material layer 44 (see FIG. 1) of the first embodiment. According to the structure 150 with a thermoplastic elastomer coating layer of the seventh embodiment, similar to the bearing 10 of the first embodiment, the first material layer 155 and the second material layer 156 can be firmly engaged with the outer peripheral surface 153 of the cylindrical member 152. Thereby, it is possible to prevent the coating layer 154 from falling off from the outer peripheral surface 153 of the cylindrical member 152. Further, according to the structure 150 with a thermoplastic elastomer coating layer of the seventh embodiment, similar to the bearing 10 of the first embodiment, a large number of structures 150 with a thermoplastic elastomer coating layer in which the coating layer 154 is formed on the outer peripheral surface 153 of the cylindrical member 152 can be manufactured inexpensively.

[0100] Similar to the bearing 10 of the first embodiment, the cylindrical member 152 may have a groove formed on the outer peripheral surface 153. The groove is formed in an annular shape in the circumferential direction of the outer peripheral surface 153. It is also possible to form a plurality of grooves at intervals in the axial direction of the outer peripheral surface 153.

[0101] In the seventh embodiment, an example in which the first material layer 155 and the second material layer 156 are formed as the coating layer 154 on the cylindrical member 152 has been described, but the present invention is not limited thereto. As another example, the first material layer 155 and the second material layer 156 may be formed as the coating layer 154 on a cylindrical member.

[0102] (Eighth Embodiment) FIG. 11 is a cross-sectional view of a structure 160 with a thermoplastic elastomer coating layer according to the eighth embodiment. As shown in FIG. 11, in the structure 160 with a thermoplastic elastomer coating layer, a coating layer 164 is formed on the outer surface 163 of the flat member 162. The flat member 162 is made of a metal material such as stainless steel, for example. The covering layer 164 includes a first material layer 165 formed on the outer surface 163 and a second material layer 166 formed on the outer surface 163 of the first material layer 165.

[0103] The flat member 162 has, for example, a protrusion 171 on the outer surface 163. The protrusion 171 has a leg portion 172 protruding in a direction intersecting the outer surface 163 and an extension portion 173 formed at the tip 172a of the leg portion 172. The protrusion 171 is formed in a T shape by the leg portion 172 and the extension portion 173. That is, the outer surface 163 of the flat member 162 is a flat outer surface having irregularities. The protrusion 171 is covered with the first material layer 165 formed on the outer surface 163 of the flat member 162. The first material layer 165 is formed of the same amorphous plastic as the first material layer 43 (see FIG. 1) of the first embodiment. The first material layer 165 is firmly locked to the outer surface 163 of the flat member 162 by being locked to the protrusion 171.

[0104] The second material layer 166 is formed on the outer surface 165a of the first material layer 165. The second material layer 166 forms the outer peripheral surface layer of the covering layer 164. The second material layer 166 is formed of the same thermoplastic elastomer as the second material layer 44 (see FIG. 1) of the first embodiment. The second material layer 166 has an outer peripheral surface layer 175, a first side surface layer 176, and a second side surface layer 177. Both side surfaces (the first side surface 165b and the second side surface 165c) of the first material layer 165 are sandwiched by the first side surface layer 176 and the second side surface layer 177 of the second material layer 166. Therefore, when the second material layer 166 cools and shrinks, the first side surface 165b and the second side surface 165c of the first material layer 165 can be sandwiched by the second material layer 166 (the first side surface layer 176 and the second side surface layer 177). Thereby, the second material layer 166 can be firmly engaged with the first material layer 165.

[0105] According to the structure 160 with a thermoplastic elastomer coating layer of the eighth embodiment, similar to the bearing 10 of the first embodiment, the first material layer 165 and the second material layer 166 can be firmly engaged with the outer surface 163 of the flat member 162. Thereby, it is possible to prevent the coating layer 164 from falling off the outer surface 163 of the flat member 162. Further, according to the structure 160 with a thermoplastic elastomer coating layer of the eighth embodiment, similar to the bearing 10 of the first embodiment, the structure 160 with a thermoplastic elastomer coating layer in which the coating layer 164 is formed on the outer surface 163 of the flat member 162 can be manufactured in large quantities and at low cost.

[0106] Here, modifications of the first to sixth embodiments will be described. That is, in the first to sixth embodiments, an example in which the outer ring 21 of the bearings 10, 70, 90, 110, 130, 140 is formed of a metal material has been described, but the present invention is not limited to this. As a bearing according to a modification of the first to sixth embodiments, for example, the outer ring 21 of the bearings 10, 70, 90, 110, 130, 140 may be formed of a hard plastic (amorphous plastic). By forming the outer ring 21 of an amorphous plastic, the second material layer (outer peripheral surface layer) 44, 74, 94, 114, 134, 144, 156, 166 can be directly formed on the outer ring 21 made of the amorphous plastic. Thereby, the first material layer 43, 73, 93, 113, 155, 165 can be removed, and the configuration can be simplified. Further, the outer ring 21 and the first material layer 43, 73, 93, 113, 155, 165 may be integrally formed of a hard plastic (amorphous plastic). Thereby, the same effects as those of the first to sixth embodiments can be obtained.

[0107] Next, modifications of the seventh to eighth embodiments will be described. That is, in the seventh to eighth embodiments, an example in which the cylindrical member 152 and the flat member 162 are formed of a metal material has been described, but the present invention is not limited to this. As a modification of the seventh to eighth embodiments, for example, the cylindrical member 152 and the flat member 162 may be formed of a hard plastic (amorphous plastic). By forming the cylindrical member 152 and the flat member 162 from an amorphous plastic, the second material layers 156 and 166 can be directly formed on the cylindrical member 152 and the flat member 162 made of the amorphous plastic. Thereby, the first material layers 155 and 165 can be removed, and the configuration can be simplified. Further, the cylindrical member 152, the flat member 162, and the first material layers 155 and 165 may be integrally formed of a rigid plastic (amorphous plastic). Thereby, the same effects as those of the seventh to eighty-sixth embodiments can be obtained.

[0108] (Modification example) FIG. 12 is a cross-sectional view of a bearing according to a modification example of the present invention. As shown in FIG. 12, it is also possible to mold the second material layer 44 of the bearing 10 from a thermoplastic elastomer filled from a gate G2 having a large gate diameter D1. The gate G2 has a gate diameter D1 that is larger than the wall thickness dimension T3 of the second material layer 44 and is opened. Further, the gate G2 is arranged so as to overlap both the first material layer 43 and the second material layer 44 in the axial direction. When the thermoplastic elastomer is filled from the gate G2 into the inside of the mold (cavity), the second material layer 44 is insert-molded on the first material layer 43 and the first side portion 24c and the second side portion 24d of the outer peripheral surface 24.

[0109] Since the gate diameter D1 of the gate G2 is formed large and the gate G2 is arranged so as to overlap both the first material layer 43 and the second material layer 44, even when the wall thickness dimension T3 of the second material layer 44 is small, the second material layer 44 can be favorably molded. Furthermore, the thermoplastic elastomer can be filled onto the outer surface 53b of the first material layer 43 (specifically, the first side surface layer 53) with a large pressure. Thereby, the adhesion between the two layers of the first material layer 43 and the second material layer 44 can be enhanced.

[0110] In the modification, an example in which the second material layer 44 of the bearing 10 is formed by the gate G2 having a large gate diameter D1 has been described, but the present invention is not limited thereto. As another example, the second material layers 74, 94, 114, 144 of the bearings 70, 90, 110, 140 may be formed by the gate G2 having a large gate diameter D1, for example.

[0111] Note that the technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. In the first to seventh embodiments, the use of the coating layers 18, 72, 92, 112, 132, 142, 154, 164 of the bearings 10, 70, 90, 110, 130, 140 for rotational sliding has been described, but the present invention is not limited thereto. As another example, it can also be applied as a member for fixing other members and the bearings 10, 70, 90, 110, 130, 140 (substituting for an O-ring) or as an insulating member for preventing electrolytic corrosion.

[0112] In the first to seventh embodiments, an example in which the coating layers 18, 72, 92, 112, 132, 142, 154, 164 are provided on the outer peripheral surface 24 of the outer ring 21 has been described, but the present invention is not limited thereto. As another example, a coating layer may be provided on the inner peripheral surface of the inner ring 22.

[0113] Furthermore, in the first to sixth embodiments, an example in which the first material layer and the second material layer are formed on the outer ring 21 of the bearings 10, 70, 90, 110, 130, 140 has been described, but the present invention is not limited thereto. As another example, for example, the first material layer, the second material layer, and the third material layer may be sequentially formed on the outer ring 21. In addition, the second material layer is made of a material softer than the first material layer. Also, the third material layer is made of a material harder than the second material layer. Thereby, it is possible to reduce the noise when driving the bearing, and furthermore, a bearing excellent in wear resistance and durability of the bearing can be realized.

[0114] In the first to seventh embodiments, an example in which the width dimensions of the coating layers 18, 72, 92, 112, 132, and 142 are set to be the same as the width dimension of the ring body 12 has been described. However, the present invention is not limited to this. As another example, for instance, the width dimensions of the coating layers 18, 72, 92, 112, 132, and 142 may be set to be smaller than that of the ring body 12. Hereinafter, the coating layers 18, 72, 92, 112, 132, and 142 will be abbreviated as "coating layer 18...". By reducing the width dimension of the coating layer 18..., the amount of material used to form the coating layer 18... can be reduced, and by reducing the contact area of the second material layer (i.e., the outer peripheral surface layer) of the coating layer 18..., noise reduction can be achieved.

[0115] In the first to seventh embodiments, grooves or indentations may be formed in the first outer peripheral surfaces 46, 76, 96, 116, 155a, and 165a of the first material layers 43, 73, 93, 113, 155, and 165. The grooves are formed, for example, so as to extend in the axial direction of the bearing. By forming grooves or indentations in the first outer peripheral surfaces 46, 76, 96, 116, 155a, and 165a, the bonding strength of the second material layer to the first outer peripheral surface of the first material layer can be increased.

Explanation of Reference Numerals

[0116] 10, 70, 90, 110, 130, 140... Bearing (Structure with Thermoplastic Elastomer Coating Layer) 18, 72, 92, 112, 132, 142, 154, 164... Coating Layer 21......... Outer Ring 24, 153... Outer Peripheral Surface (Circular Outer Surface) 28......... Groove 43, 73, 93, 113, 155, 165... First Material Layer 44, 74, 94, 114, 134, 144, 156, 166... Second Material Layer (Outer Peripheral Surface Layer) 46, 76, 96, 116, 155a... First Outer Peripheral Surface (Outer Surface of the First Material Layer) 52, 82, 122, 146, 175... Outer Peripheral Surface Layer 53, 54, 83, 84, 123, 124, 176, 177… the first and second side layers (a pair of side layers) 163...... outer surface 165a... outer surface of the first material layer (outer surface of the first material layer) 171...... protrusion

Claims

1. A structure having a coating layer on the outer peripheral surface of a cylindrical member, The coating layer has an outer peripheral surface layer formed by heat-sealing a thermoplastic elastomer, The coating layer, on the outer peripheral surface, has a first material layer made of an amorphous plastic, and a second material layer made of a thermoplastic elastomer, which is the outer peripheral surface layer forming the outer peripheral surface of the coating layer by heat-sealing the thermoplastic elastomer containing potassium titanate fibers on the outer surface of the first material layer, The second material layer is made of a material softer than the first material layer. A structure with a thermoplastic elastomer coating layer.

2. A structure having a coating layer formed on an outer surface having irregularities, The coating layer has an outer peripheral surface layer formed by heat-sealing a thermoplastic elastomer, The coating layer, on the outer surface, has a first material layer made of an amorphous plastic, and a second material layer made of a thermoplastic elastomer, which is the outer peripheral surface layer forming the outer peripheral surface of the coating layer by heat-sealing the thermoplastic elastomer containing potassium titanate fibers on the outer surface of the first material layer, The second material layer is made of a material softer than the first material layer. A structure with a thermoplastic elastomer coating layer.

3. The outer peripheral surface is the outer peripheral surface of an outer ring provided in a bearing, and a coating layer is formed on the outer peripheral surface of the outer ring. The structure with a thermoplastic elastomer coating layer according to Claim 1.

4. The outer peripheral surface of the outer ring is provided with a groove extending in the circumferential direction. The structure with a thermoplastic elastomer coating layer according to Claim 3.

5. The second material layer, is an outer peripheral surface layer covering the outer surface of the first material layer, A pair of side surface layers that are connected to the outer peripheral surface layer and cover both axial side surfaces of the first material layer. The structure with a thermoplastic elastomer coating layer according to claim 3 or claim 4, characterized by having the above.

6. The pair of side surface layers of the second material layer are in contact with the outer peripheral surface of the outer ring. The structure with a thermoplastic elastomer coating layer according to claim 5, characterized by the above.

7. The first material layer is formed such that the width dimension gradually increases radially outward from the outer peripheral surface. The structure with a thermoplastic elastomer coating layer according to claim 5 or claim 6, characterized by the above.

8. A coating layer is provided on the outer peripheral surface of the outer ring of a cylindrical bearing. The outer ring is formed of an amorphous plastic. The coating layer includes an outer peripheral surface layer formed by heat-fusing a thermoplastic elastomer containing potassium titanate fibers to the outer peripheral surface of the outer ring to form the outer peripheral surface of the coating layer. The outer peripheral surface layer is made of a material softer than the outer ring. The structure with a thermoplastic elastomer coating layer, characterized by the above.

9. A gate mark is provided on the outer surface of the second material layer. When viewed in the axial direction, the gate mark has an outer shape formed larger than the wall thickness dimension of the second material layer and is arranged to overlap both the second material layer and the first material layer in the axial direction. The structure with a thermoplastic elastomer coating layer according to any one of claims 1 to 7, characterized by the above.

10. Having a plurality of structures with a thermoplastic elastomer coating layer according to any one of claims 1 to 9, the structure with a thermoplastic elastomer coating layer being a bearing, fixing the inner rings of the plurality of bearings to a main body portion, bringing the coating layers of the plurality of bearings into contact with a contact object, and the coating layer and the outer ring of the bearing to which the coating layer is fixed functioning as a wheel that rolls with respect to the contact object. A moving body, characterized by the above.

11. Having a pair of the structures with a thermoplastic elastomer coating layer according to any one of claims 1 to 9, wherein the structure with a thermoplastic elastomer coating layer is a bearing, the coating layers are arranged adjacent to each other, the inner ring of the bearing is attached to a support shaft, and the outer ring of the bearing and the coating layer rotate to convey a conveyed object sandwiched between the pair of coating layers. A conveying device characterized by this.

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