JP7693629B2 - Structure with thermoplastic elastomer coating layer, moving body and conveying device - Google Patents

Description

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

For example, known applications of rolling bearings include transporting items such as banknotes and tickets with the outer ring of the rolling bearing, and using the rolling bearing as a wheel of a moving body to roll along a contact object. In this case, the outer peripheral surface of the outer ring may be coated with urethane rubber to increase the frictional force with the transported item or contact object, and to reduce the sound (noise) generated when the outer ring operates while rolling in contact.
Urethane rubber has excellent abrasion resistance, and can be firmly bonded to the outer ring. The manufacturing process for attaching urethane rubber to the outer ring is as follows:

First, the outer peripheral surface of the outer ring of the rolling bearing is roughly processed by sandblasting, and an adhesive is applied to the roughly processed outer peripheral surface. Next, the rolling bearing is set in a mold, and urethane raw material (liquid) is poured between the outer peripheral surface and the mold, and pressure is applied to the mold to form it. Next, it is held at high temperature in the mold for a specified time (approximately half a day to a day, depending on the hardness). The urethane rubber is hardened at high temperature, and the adhesive is exposed to high temperature to vulcanize and bond the urethane rubber to the outer peripheral surface. After vulcanization and bonding, the outer peripheral surface of the urethane is polished to the specified dimensions and precision. In this way, the outer peripheral surface of the rolling bearing outer ring is covered with urethane rubber (see, for example, Patent Document 1).

Japanese Utility Model Application Publication No. 6-87717

However, conventional rolling bearings have the following problems.
In other words, the urethane rubber must be allowed to harden within the mold over a long period of time, applying the adhesive to the outer peripheral surface of the outer ring takes time, and after the urethane rubber has hardened, the outer peripheral surface of the urethane must be polished to the specified dimensions and precision.
Therefore, when mass-producing rolling bearings whose outer circumferential surfaces are coated with urethane rubber, it is necessary to prepare a large amount of equipment for coating the outer circumferential surfaces with urethane rubber, which increases the equipment costs. In addition, it is necessary to roughen the outer circumferential surface of the outer ring by sandblasting and to apply an adhesive to the roughly-processed outer circumferential surface. For this reason, it is difficult to mass-produce rolling bearings coated with urethane rubber at low cost.

The present invention was made in consideration of these circumstances, and its purpose is to provide a structure, a moving body, and a drive module with a thermoplastic elastomer coating layer that can be mass-produced at low cost.

In order to solve the above problems, a structure with a thermoplastic elastomer coating layer according to one embodiment of the present invention has a coating layer on the outer peripheral surface of a cylindrical member, the coating layer has an outer peripheral surface layer formed by thermally fusing a thermoplastic elastomer, the coating layer has a first material layer made of amorphous plastic on the outer peripheral surface, 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 thermally fusing the thermoplastic elastomer containing potassium titanate fibers to the outer surface of the first material layer, and the second material layer is made of a material softer than the first material layer.

By forming the outer peripheral surface by heat fusing the thermoplastic elastomer, the outer peripheral surface layer can be firmly fixed by heat fusing. This makes it possible to eliminate the sandblasting process and adhesive coating process that were previously required. This allows structures with a thermoplastic elastomer coating layer to be mass-produced at low cost.

The structure with a thermoplastic elastomer coating layer according to one embodiment of the present invention comprises a coating layer formed on an outer surface having irregularities, the coating layer having an outer peripheral surface layer formed by thermally fusing a thermoplastic elastomer, the coating layer comprising a first material layer made of an amorphous plastic on the outer surface, 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 thermally fusing the thermoplastic elastomer to the outer surface of the first material layer, the second material layer being made of a material softer than the first material layer.

According to this configuration, by making the second material layer softer than the first material layer, a hard material can be used for the first material layer. A soft material refers to a material with a small flexural modulus and hardness (e.g., durometer hardness A). A hard material refers to a material with a large flexural modulus and hardness (e.g., durometer hardness A).
A layer of a first material is applied to the outer surface of the circle, thereby forming the layer of first material in an annular shape.
Thus, the first material layer is firmly attached to the circular outer surface by shrinkage when the first material layer cools and hardens. Also, by forming the first material layer on a flat outer surface having projections and recesses, the first material layer is locked to the projections and recesses of the flat outer surface. Thus, the first material layer can be firmly fixed to a circular outer surface or a flat outer surface having projections and recesses.
Furthermore, by making the second material layer from 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.

Furthermore, the second material layer is firmly fixed to the circular outer surface or the flat outer surface having irregularities by heat fusion via the first material layer. This makes it possible to eliminate the sandblasting process and adhesive coating process that were previously required. This allows structures with a thermoplastic elastomer coating layer to be mass-produced at low cost.

The second material layer is also made of a softer material than the first material layer. This allows the second material layer to reduce sound (noise) when the outer ring of the bearing (i.e., the second material layer) is used to transport items such as banknotes or tickets, or when the bearing is used as a wheel of a moving object and rolls along the object it comes into contact with.

In the above-described aspect, the outer peripheral surface may be an outer peripheral surface of an outer ring included in a 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 via the first material layer, thereby preventing the second material layer from falling off from the outer peripheral surface of the outer ring (i.e., the bearing).

In the above aspect, a groove portion extending in a circumferential direction may be provided on the outer peripheral surface of the outer ring.
According to this configuration, by providing grooves on the outer peripheral surface, the first material layer can be filled into the grooves. By filling the protrusions of the first material layer into the grooves on the outer peripheral surface, the grooves on the outer peripheral surface and the protrusions of the first material layer can be engaged in an uneven manner. Therefore, when a force is applied to the first material layer, the unevenness between the outer peripheral surface and the first material layer can prevent the first material layer from coming off the outer ring. This makes it possible to more reliably prevent the first material layer and the second material layer from falling off the outer peripheral surface of the outer ring (i.e., the bearing).

In the above embodiment, 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 layers that are connected to the outer peripheral surface layer and cover both axial side surfaces of the first material layer.

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 between the pair of side layers. As a result, the second material layer cools and contracts, so that both side surfaces of the first material layer can be sandwiched between the pair of side layers. This allows the second material layer to be more firmly engaged with the first material layer, and more reliably prevents the second material layer from falling off the outer peripheral surface (i.e., the outer ring).

In the above aspect, a pair of side layers of the second material layer may be in contact with an 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 large height dimension of the pair of side layers can be ensured. This makes it possible to ensure a large contact area of the side layers with the side surfaces of the first material layer. As a result, as the second material layer cools and contracts, both side surfaces of the first material layer can be sandwiched between the pair of side layers, allowing the second material layer to engage more firmly with the first material layer.

In the above aspect, the first material layer may be formed so that the width dimension gradually increases from the outer circumferential surface toward the radially outward direction.

With this configuration, the width dimension of the first material layer is gradually increased radially outward, so that the second material layer can be more firmly fixed to the first material layer. This makes it possible to more reliably prevent the second material layer from falling off the outer peripheral surface (i.e., the outer ring).

The cylindrical bearing has an outer ring with a coating layer on the outer peripheral surface thereof, the outer ring being formed from an amorphous plastic, the coating layer being characterized in that the outer peripheral surface of the coating layer is formed by heat-sealing a thermoplastic elastomer containing potassium titanate fibers to the outer peripheral surface of the outer ring, and the outer peripheral surface layer is made of a material that is softer than the outer ring.

According to this configuration, by making the first material layer from the same thermoplastic elastomer as the second material layer, the first material layer and the second material layer can be more effectively heat-sealed. This allows the second material layer to be more firmly fixed to the first material layer, and more reliably prevents the second material layer from falling off the outer peripheral surface (i.e., the outer ring).

With this configuration, by forming the outer ring from an amorphous plastic (hard plastic), the coating layer can be formed directly on the amorphous plastic outer ring. This makes it possible to eliminate the first material layer, simplifying the configuration.

In the above aspect, a gate mark may be provided on the outer surface of the second material layer, and the gate mark may be formed so that its outer shape is larger than the thickness dimension of the second material layer when viewed from the axial direction, and may be positioned so as to overlap both the second material layer and the first material layer in the axial direction.

According to this configuration, the gate opening is formed large and the gate is positioned so as to overlap both the first material layer and the second material layer, so that the second material layer can be well molded even when the thickness dimension of the second material layer is reduced.
Furthermore, the thermoplastic elastomer can be filled with a large pressure on the outer surface of the first material layer (specifically, the first side layer), thereby increasing the adhesion between the first material layer and the second material layer.

In order to solve the above problems, a moving body according to one embodiment of the present invention has a plurality of structures with thermoplastic elastomer coating layers as described above, the structures with thermoplastic elastomer coating layers are bearings, the inner rings of the plurality of bearings are fixed to a main body portion, the coating layers of the plurality of bearings are in contact with a contact object, and the coating layers and the outer rings to which the coating layers are fixed function as wheels that roll against the contact object.
In addition, in order to solve the above-mentioned problems, a conveying device according to one embodiment of the present invention has a pair of structures with the above-mentioned thermoplastic elastomer coating layers, and the structures with thermoplastic elastomer coating layers are bearings, 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 and the coating layer rotate to convey an object sandwiched between the pair of coating layers.

According to this configuration, by providing a moving body or a transport device with the above-mentioned thermoplastic elastomer coated layer-equipped structure, it is possible to ensure durability and to produce a low-cost moving body or transport device.

According to one aspect of the present invention, the outer peripheral surface is formed by heat fusing the thermoplastic elastomer, and the outer peripheral surface layer can be firmly fixed by heat fusing. This allows structures with a thermoplastic elastomer coating layer to be mass-produced at low cost.

1 is a cross-sectional view showing a bearing as a structure with a thermoplastic elastomer coating layer according to a first embodiment of the present invention. 6 is a graph showing characteristics of a state in which potassium titanate fibers are contained in the second material layer according to the first embodiment of the present invention. FIG. 4 is a side view showing a modified example of the bearing according to the first embodiment of the present invention. 1 is a side view showing a moving body including a bearing according to a first embodiment of the present invention; FIG. 4 is a cross-sectional view showing a moving body including a bearing as a structure with a thermoplastic elastomer coating layer according to a second embodiment of the present invention. FIG. 4 is a cross-sectional view showing a bearing as a structure with a thermoplastic elastomer coating layer according to a third embodiment of the present invention. FIG. 11 is a cross-sectional view showing a bearing as a structure with a thermoplastic elastomer coating layer according to a fourth embodiment of the present invention. FIG. 11 is a cross-sectional view showing a bearing as a structure with a thermoplastic elastomer coating layer according to a fifth embodiment of the present invention. FIG. 13 is a cross-sectional view showing a bearing as a structure with a thermoplastic elastomer coating layer according to a sixth embodiment of the present invention. FIG. 13 is a cross-sectional view showing a structure with a thermoplastic elastomer coating layer according to a seventh embodiment of the present invention. FIG. 13 is a cross-sectional view showing a structure with a thermoplastic elastomer coating layer according to an eighth embodiment of the present invention. FIG. 11 is a cross-sectional view showing a modified example according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first to sixth embodiments, the structures with thermoplastic elastomer coating layers are described as bearings 10, 70, 90, 110, 130, and 140.
First Embodiment
FIG. 1 is a cross-sectional view of a bearing 10 according to a first embodiment.
As shown in FIG. 1, the bearing 10 is a rolling bearing including a race 12, a plurality of rolling elements 14, a retainer 16 and a coating layer 18.
The raceway 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 multiple rolling elements 14 are arranged annularly between the outer ring 21 and the inner ring 22 that constitute the raceway 12. The retainer 16 holds the multiple rolling elements 14 in a state where they are evenly arranged in the circumferential direction so that they can roll freely.

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 circumferential surface (i.e., an outer surface formed in a circular shape) 24, an inner circumferential 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 in the center in the direction of the axis O. The central portion 26 is formed such that a central portion 25a of the inner peripheral surface 25 in the direction of the axis O is spaced a distance T1 radially inward from the outer peripheral surface 24 of the outer ring 21. A recess is formed in the portion of the outer peripheral surface 24 corresponding to the central portion 26 as a groove portion 28 extending in the circumferential direction.

Groove portion 28 has a deepest portion 28a radially inward from outer circumferential surface 24. Deepest portion 28a is the deepest portion of groove portion 28. Groove portion 28 is formed such that, in its cross-sectional shape, groove width dimension L1 gradually decreases from the outer circumferential surface 24 side to deepest portion 28a.
As an example, the groove portion 28 has a cross-sectional shape formed into a curved surface at the center of the outer ring 21 in the axial O direction, and opens to the radially outer side of the outer ring 21. The groove portion 28 is formed in a shape symmetrical with respect to the center of the outer ring 21 in the axial O direction.

The pair of outer parts 27 are formed symmetrically with respect to the center of the outer ring 21 in the axial O direction, outside the central part 26. The pair of outer parts 27 are formed such that the outer parts of the inner circumferential surface 25 on the outer side in the axial O direction are spaced apart by a distance T2 radially inward from the outer circumferential surface 24 of the outer ring 21. The distance T1 of the central part 26 is set larger than the distance T2 of the pair of outer parts 27. In other words, the thickness dimension of the central part 26 is larger than the thickness dimension of the pair of outer parts 27.

An outer ring rolling surface 29 is formed on a portion 25a of the central portion 26 of the inner circumferential surface 25. The outer ring rolling surface 29 is formed so that its side cross section is arc-shaped so as to conform to the outer surface of the rolling elements 14. The cross section of the outer ring rolling surface 29 is formed so that the radius of curvature is approximately the same as or slightly larger than the radius of curvature of the outer surface of the rolling elements 14. The outer ring rolling surface 29 is formed over the entire circumference of the inner circumferential surface 25 of the outer ring 21. The outer surfaces of a plurality of rolling elements 14 can abut against the outer ring rolling surface 29.
The outer ring rolling surface 29 is formed in the center in the direction of the axis O, and is disposed at a position overlapping with the groove portion 28 in the radial direction of the outer circumferential surface 24 .

Groove 28 is formed in the center in the direction of axis O, and is disposed at a position where it overlaps radially with outer ring rolling surface 29 and outer peripheral surface 24. Meanwhile, groove 28 has a curved cross-sectional shape. This makes it possible to suppress the influence of deformation of outer ring 21 and reduction in rigidity of outer ring 21 due to groove 28 on outer ring rolling surface 29.
Furthermore, by forming the cross-sectional shape of the groove 28 into a curved surface, there is no flat portion on the bottom surface of the groove 28. This makes it possible to reduce the cutting resistance of the cutting tool when machining the groove 28 with the cutting tool, making it easier to machine the groove 28. Furthermore, by reducing the cutting resistance of the cutting tool, the life of the cutting tool can be extended.
In addition, the grooves 28 are formed in a symmetrical shape with respect to the center in the direction of the axis O of the outer ring 21. The grooves 28 are formed in a well-balanced manner at the center of the outer peripheral surface 24 of the outer ring 21. This makes it possible to more effectively suppress the influence of deformation of the outer ring 21 and a decrease in rigidity of the outer ring 21 due to the grooves 28 on the outer ring rolling surface 29.

Here, the groove 28 is provided in the center of the outer ring 21 in the direction of the axis O, and the outer ring rolling surface 29 is also provided in the center of the outer ring 21 in the direction of the axis O. This makes it possible to minimize the influence of deformation of the outer ring 21 due to heat treatment such as quenching. In particular, the outer ring 21 is formed so that the thickness dimension of the central portion 26 is larger than the thickness dimension of the pair of outer portions 27. The groove 28 is formed in the portion of the central portion 26 where the thickness dimension is larger. This makes it possible to ensure the thickness dimension for forming the groove 28.
Furthermore, groove 28 has a curved cross-sectional shape. Meanwhile, outer ring rolling surface 29 also has a curved cross-sectional shape. That is, groove 28 is formed in the same shape as outer ring rolling surface 29. This makes it possible to further reduce the effects of deformation of outer ring 21 due to heat treatment such as quenching.

In the first embodiment, an example in which the groove portion 28 is formed on a curved cross section has been described, but this is not limiting, and as other examples, the groove portion 28 may be formed on a V-shaped cross section, a U-shaped cross section, or other shape. Even when the groove portion 28 is formed on a V-shaped cross section, a U-shaped cross section, or other shape, the same effect as in the first embodiment can be obtained.

The inner ring 22 is made of a metal material such as stainless steel, etc. The inner ring 22 is a substantially cylindrical member having a predetermined thickness dimension in the direction of the axis O, and is formed by, for example, forging or machining.
An inner ring rolling surface 33 is formed at a middle portion in the direction of the axis O of the outer circumferential surface 32 of the inner ring 22. The inner ring rolling surface 33 is formed so that its side cross section is arc-shaped so as to conform to the outer surface of the rolling elements 14. The inner ring rolling surface 33 is formed so that the radius of curvature in the cross section is substantially the same as or slightly larger than the radius of curvature of the outer surface of the rolling elements 14. The inner ring rolling surface 33 is formed over the entire circumference of the outer circumferential 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.

The inner ring 22 is fixed to the support shaft 41, so that the coating layer 18 rotates together with the outer ring 21. The coating outer peripheral surface 52c of the coating layer 18 (second material layer 44) is the surface that conveys, for example, banknotes, tickets, etc., and rolls over the contact object 5 (see Figure 4).

The rolling elements 14 are formed into a spherical shape from a metal 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 arranged evenly in an annular shape along the circumferential direction by the retainer 16 so as to be free to roll. Grease for lubrication is sealed in the bearing 10.

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 of the outer peripheral surface 24 of the outer ring 21 in the direction of the axis O. 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 first side surface of the pair of side surfaces 48, 49 will be referred to as the first side surface 48, and the other side surface will be referred to as the second side surface 49.

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

The first material layer 43 is formed of, for example, a hard plastic, and in particular, an amorphous plastic is preferred because it has excellent thermal adhesion with a thermoplastic elastomer. As the amorphous plastic, polycarbonate, ABS resin, or an alloy material of polycarbonate and ABS resin, etc. are preferred. The first material layer 43 is cooled and a force is applied to the outer peripheral surface 24 so that the first material layer 43 adheres to the outer peripheral surface 24 toward the center of the outer ring 21 (in the radial direction), so that 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 made of hard plastic and formed into an annular shape along the outer circumferential surface 24. Therefore, the first material layer 43 is firmly attached to the outer circumferential surface 24 by contraction when the first material layer 43 cools and hardens.
The first material layer 43 is filled in the grooves 28. By filling the protrusions 43a of the first material layer 43 in the grooves 28 of the outer circumferential surface 24, the grooves 28 of the outer circumferential surface 24 and the protrusions 43a of the first material layer 43 can be engaged in an uneven manner.

When the first material layer 43 is insert molded into the outer peripheral surface 24 and groove 28 of the outer ring 21, the bearing 10 is placed inside a mold, and at least the end faces 21a, 21b of the outer ring 21 in the direction of axis O are supported in contact with the mold. In this way, the end faces 21a, 21b are supported by the mold, and the first material layer 43 is insert molded into the outer peripheral surface 24 and groove 28 of the outer ring 21. The first material layer 43 may also be insert molded into the outer ring 21 alone.

In addition, by filling the grooves 28 with the protrusions 43a of the first material layer 43, the protrusions 43a filled in the grooves 28 act as anchors. This makes it possible to firmly fix the first material layer 43 to the outer peripheral surface 24 of the outer ring 21 and the grooves 28.
When the first material layer 43 is provided on the outer peripheral surface 24 of the outer ring 21, a first side portion 24c and a second side portion 24d of the outer peripheral surface 24 located on both sides of the first material layer 43 in the direction of the axis O are exposed to the outside.

A second material layer 44 is formed on the first material layer 43 and 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 layers 53, 54. Hereinafter, one of the pair of side layers 53, 54, the first side layer, is referred to as the first side layer 53, and the other side layer is referred to as the second side 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 connected to one end 52a of the outer peripheral surface layer 52 and is a layer that 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 connected to the other end 52b of the outer peripheral surface layer 52 and is a layer that 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 (first side surface 48 , second side surface 49 ) of the first material layer 43 are sandwiched between the first side surface layer 53 and the second side surface layer 54 of the second material layer 44 .

The second material layer 44 is made of a thermoplastic elastomer (TPE), which has excellent thermal adhesion to the amorphous plastic material of the first material layer 43.
As the thermoplastic elastomer, styrene-based (TPS), olefin-based (TPO), polyvinyl chloride-based (PPVC), urethane-based (TPU), and polyester-based (TPEE) are applicable. From the viewpoint of mechanical strength and abrasion resistance, urethane-based (TPU), polyester-based (TPEE), and styrene-based (TPS) are preferred. More preferred thermoplastic elastomers include polyester-based (TPEE).
The urethane-based material (TPU) has the best abrasion resistance, but has problems with moldability, is highly hygroscopic, and requires sufficient drying. In addition, annealing is required, which takes time to manufacture and also causes problems with molding accuracy. In addition, the urethane-based material has the best mechanical strength and abrasion resistance among thermoplastic elastomers. For this reason, the urethane-based material is used when the covering layer 18 requires mechanical strength and abrasion resistance.

Polyester-based materials (TPEE) have the best abrasion resistance and mechanical strength of all thermoplastic elastomers other than urethane, and also have excellent thermal adhesion to hard plastics. In addition, polyester-based materials (TPEE) have low moisture absorption and good moldability, making them an ideal material for the coating layer 18.

Here, polyester-based materials (TPEE) are preferable as the thermoplastic elastomer of the second material layer 44. Polyester-based materials have excellent abrasion resistance and mechanical strength, and also have excellent thermal fusion properties with hard plastics (i.e., the first material layer 43).
The heat fusion refers to, for example, the thermoplastic elastomer of the second material layer 44 melting by heating and adhering to the hard plastic (first material layer 43).
Therefore, this is effective when two-color molding is performed. Furthermore, polyester (TPEE) is an optimal material for the second material layer 44 of the bearing 10 because it has low moisture absorption and good moldability.
From the viewpoint of suppressing sound (noise), it is desirable for the durometer hardness A of the second material layer 44 to be 75 to 95. For example, a durometer hardness A of 92 is particularly preferable from the viewpoints of satisfactorily suppressing sound (noise) and satisfactorily ensuring the mechanical strength and abrasion resistance of the second material layer 44. If the durometer hardness A is less than 75, it is considered that the mechanical strength and abrasion resistance of the second material layer 44 will become problematic.

The thermoplastic elastomer of the second material layer 44 is a material softer 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. Thus, the first material layer 43 is injection molded in a molten state onto the outer peripheral surface 24 of the outer ring 21, and the molten first material layer 43 cools and solidifies after injection molding, causing the annular first material layer 43 to shrink. Thus, 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 that has a low flexural modulus and hardness (for example, durometer hardness A).
A hard material refers to a material that has a high flexural modulus and hardness (for example, durometer hardness A (durometer hardness A)).

In addition, by providing a groove 28 on the outer peripheral surface 24 of the outer ring 21, the first material layer 43 can be filled into the groove 28. By filling the protrusion 43a of the first material layer 43 into the groove 28 on the outer peripheral surface 24, the groove 28 on the outer peripheral surface 24 and the protrusion 43a of the first material layer 43 can be engaged in an uneven manner. Therefore, when a force is applied to the first material layer 43, the unevenness between the outer peripheral surface 24 and the first material layer 43 can prevent the first material layer 43 from coming off the outer ring 21.

Here, the second material layer 44 is formed in an annular shape along the first material layer 43, and is made of 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).
In addition, both side surfaces (first side surface 48, second side surface 49) of the first material layer 43 are sandwiched between 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 second side surface 49 of the first material layer 43 can be sandwiched between the first side surface layer 53 and the second side surface layer 54 of the second material layer 44. This allows the second material layer 44 to be engaged with the first material layer 43 more firmly.

Furthermore, the inner circumferential surface 53a of the first side 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 circumferential surface 54a of the second side 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, a large height dimension H1 of the first side layer 53 and the second side layer 54 is ensured.
Therefore, a large contact area of the first side layer 53 with the first side surface 48 is ensured. A large contact area of the second side layer 54 with the second side surface 49 is ensured. As a result, the second material layer 44 cools and contracts, so that the entire areas of the first side surface 48 and the second side surface 49 can be sandwiched between the first side surface layer 53 and the second side surface layer 54. As a result, the second material layer 44 can be engaged with the first material layer 43 more firmly. Therefore, even if a force in the direction of the axis O or a force in a direction in which the second material layer 44 is turned over from the outer peripheral surface 24 of the outer ring 21 is applied to the second material layer 44, the second material layer 44 is less likely to peel off from the outer peripheral surface 24 of the outer ring 21.

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. This makes it 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.

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 adhesive application process that were previously required can be eliminated.
Furthermore, when the first material layer 43 and the second material layer 44 are injection molded, for example, by two-color molding, it is not necessary to harden the amorphous plastic of the first material layer 43 and the thermoplastic elastomer of the second material layer 44 in a mold for a long period of time, as is the case with urethane rubber. In other words, when the first material layer 43 and the second material layer 44 are injection molded, it is possible to eliminate the need for a process of hardening the amorphous plastic of the first material layer 43 and the thermoplastic elastomer of the second material layer 44 in a mold for a long period of time, as is the case with urethane rubber.
This makes it possible to mass-produce the bearings 10 in which the coating layer 18 (first material layer 43, second material layer 44) is formed on the outer peripheral surface 24 of the outer ring 21 at low cost.

As described above, the first material layer 43 and the second material layer 44 of the covering layer 18 are formed, for example, by two-color molding. Specifically, the first material layer 43 is insert molded onto 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, the mold for injection molding the second material layer 44 has, for example, a gate G1 disposed at a position corresponding to the first side layer 53 of the second material layer 44. Molten thermoplastic elastomer is filled into the interior (cavity) of the mold from the gate G1, so that 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 layer 53, the filling location of the thermoplastic elastomer can be shifted from the coated outer peripheral surface 52c of the outer peripheral surface layer 52.

Further, the parting line PL of the mold is positioned on the outer surface 53b of the first side layer 53 in the direction of the axis O of the bearing 10, for example. The outer surface 53b of the first side layer 53 is formed in 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 positioned 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, it is possible to prevent burrs generated when the thermoplastic elastomer is filled into the mold from the gate G1, burrs generated by the parting line PL, and the like from being generated on the coated outer peripheral surface 52c of the outer peripheral surface layer 52. This makes it possible to eliminate the need for post-processing to remove burrs from the coated outer peripheral surface 52c of the outer peripheral surface layer 52.
Here, the distance between the outer surface 53b of the first side layer 53 and the inner peripheral surface 54a of the second side layer 54 is the width dimension of the covering layer 18. The width dimension of the covering layer 18 is set to be the same as the width dimension of the ring body 12.

Incidentally, the mold temperature during injection molding of amorphous plastic or thermoplastic elastomer is kept low at 150°C or less (preferably 100°C or less). In addition, when the molten amorphous plastic or thermoplastic elastomer is filled into the mold from gate G1, the amorphous plastic or thermoplastic elastomer instantly solidifies. This prevents the high temperature of the molten amorphous plastic or thermoplastic elastomer from reaching the grease sealed in the bearing 10. This means that there is no risk of the grease deteriorating due to the high temperature of the molten amorphous plastic or thermoplastic elastomer.

Here, by welding the coating layer 18 (the first material layer 43 and 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 using 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, if a coating layer is bonded to the outer peripheral surface with an adhesive, the adhesive may not be applied to a uniform thickness on the outer peripheral surface due to uneven application of the adhesive. On the other hand, in the case of a small bearing, the thickness of the coating layer may be less than 1.0 mm. In this state, if the adhesive is not applied to the outer peripheral surface in a uniform thickness, the hardness of the coating layer may become non-uniform.
For this reason, when a small bearing covered with a coating layer is used to transport an object or when the coating layer is caused to roll along a contact object, there is a risk that noise will be generated or that this will cause uneven torque.

In contrast, adhesive can be eliminated by welding the coating layer 18 (first material layer 43, second material layer 44) to the outer circumferential surface 24. This makes it possible to maintain the hardness of the coating layer 18 uniform over the entire circumference even when the bearing 10 is small and the thickness dimension of the coating layer 18 is smaller than 1.0 mm.
As a result, even if the bearing 10 is formed small, the generation of sound (noise) and causes of torque unevenness can be suppressed when the bearing 10 transports an object or when the bearing 10 rolls along a contacting object.
In the first embodiment, an example is described in which the coating layer 18 (first material layer 43, second material layer 44) is provided on the outer peripheral surface 24 only by welding. However, depending on the application of the bearing 10, the coating layer 18 may be provided on the outer peripheral surface 24 by, for example, using an adhesive in combination with welding.

In the first embodiment, an example has been described in which the first material layer 43 of the coating layer 18 is made of a hard plastic (amorphous plastic) such as polycarbonate, but a thermoplastic elastomer may also be used, for example, as with the second material layer 44.
This allows for more favorable thermal fusion bonding between the first material layer 43 and the second material layer 44. This allows the second material layer 44 to be more firmly fixed to the first material layer 43, and more reliably prevents the second material layer 44 from falling off the outer peripheral surface 24 of the outer ring 21.

Here, for example, in order to ensure the wear amount of the second material layer 44, it is possible to include potassium titanate fibers in the thermoplastic elastomer as shown in Table 1 and FIG.
Table 1 shows the characteristics of the second material layer 44 of the present invention when potassium titanate fibers are contained in the second material layer 44. Fig. 2 is a graph showing the characteristics of the second material layer 44 when potassium titanate fibers are contained in the second material layer 44.
In Table 1 and Figure 2, the thermoplastic elastomer (polyester-based (TPEE)) that does not contain potassium titanate fiber is shown as elastomer (single unit). The thermoplastic elastomer containing 10 wt% potassium titanate fiber is shown as elastomer (10 wt%). The thermoplastic elastomer containing 20 wt% potassium titanate fiber is shown as elastomer (20 wt%). The thermoplastic elastomer containing 30 wt% potassium titanate fiber is shown as elastomer (30 wt%).

Table 1 and FIG. 2 show the properties of elastomer (single substance), elastomer (10 wt%), elastomer (20 wt%), and elastomer (30 wt%).
By adding 10 wt%, 20 wt%, or 30 wt% potassium titanate fiber to the thermoplastic elastomer, the tensile strength can be increased from 12 MPa to 13 MPa, 18 MPa, or 23 MPa.
In addition, the bending strength can be increased from 4 MPa to 7 MPa, 9 MPa, and 16 MPa, and the bending modulus can be increased from 0.05 GPa to 0.13 GPa, 0.21 GPa, and 0.44 GPa.

The graph in Figure 2 shows the wear volume and durometer hardness A of the thermoplastic elastomer alone and the thermoplastic elastomer containing 10 wt%, 20 wt%, and 30 wt% potassium titanate fiber. As shown in Figure 2 and Table 1, when the thermoplastic elastomer contains 10 wt%, 20 wt%, and 30 wt% potassium titanate fiber, the durometer hardness A of the thermoplastic elastomer can be maintained at approximately the same values of 94 to 96, 97, and 98.
Furthermore, as shown in FIG. 2 and Table 1, when the thermoplastic elastomer contains 10 wt%, 20 wt%, and 30 wt% potassium titanate fiber, the wear volume of the thermoplastic elastomer can be reduced from 12.5× ^10-3 cm3 to ^10.1 × ^{10-3 cm3} , 7.0× ^{10-3 cm3} , and 3.8× ^10-3 cm3 ^.

Here, the wear amount of the thermoplastic elastomer is measured by a reciprocating sliding test, in which a glass plate is selected as the counter material, and the reciprocating sliding test is performed under conditions of a load of 0.7 kg, a speed of 0.16 m/s, and a time of 20 minutes.
The content of the potassium titanate fibers is appropriately selected depending on the application of the bearing 10.

(Modification)
Next, a modification 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, an example in which the second material layer 44 is formed from a thermoplastic elastomer has been described as the bearing 10 of the first embodiment, but as another example, a plurality of gear teeth 57 can be formed on the outer circumferential coating surface of the second material layer 44. This makes it possible to use the bearing 10 as a gear 55. The gear 55 can be used, for example, as a small planetary gear inside a planetary gear mechanism.
The gear 55 has a plurality of teeth 57 formed of a thermoplastic elastomer, which makes it possible to reduce the driving noise generated when the gears 55 mesh.
Also, for the second material layer 44 forming the plurality of teeth 57, a thermoplastic elastomer having a durometer A of more than 95 can be used, taking into consideration the wear resistance and mechanical strength of the gear 55.

Next, an example of an application of the bearing 10 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a side view showing a moving body 1 equipped with the bearing 10 according to the first embodiment.
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 2 and a plurality of bearings 10 attached to both sides of the main body 2. The plurality of bearings 10 are fixed by attaching an inner ring 22 to a support shaft 3.
The support shaft 3 is attached to the main body 2. The inner ring 22 is fixed to the support shaft 3, so that the outer ring 21 and the coating layer 18 are rotatably supported on the support shaft 3. In other words, the multiple bearings 10 are used as a wheel.

The movable body 1 is disposed with the covering layers 18 (specifically, the second material layers 44) of the multiple bearings 10 in contact with the contact object 5. The second material layers 44 are formed of a thermoplastic elastomer. The outer rings 21 and covering layers 18 of the bearings 10 roll on the contact object 5, thereby allowing the movable body 1 to move along the contact object 5.
Since the coating layer 18 is formed on the outer ring 21, the coating layer 18 (particularly the second material layer 44) can reduce sounds (noises) when the bearing 10 moves while rolling over the contact object 5. In addition, since the coating layer 18 is firmly engaged with the outer peripheral surface 24 of the outer ring 21, the coating layer 18 can be prevented from falling 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, durability can be ensured and the moving body 1 can be obtained at low cost.

4, an example has been described in which the coating layer 18 of the bearing 10 is rotated while being in contact with the contact object 5, and the movable body 1 is moved along the contact object 5, but this is not limiting. As another example, the movable body 1 may be held in a fixed state, and the coating 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 coating layer 18. In this case, it corresponds to the case where the drawer of a desk is the contact object 5. Even in this state, the coating layer 18 can reduce sound (noise).
As another example, the bearing 10 may be applied to a swivel wheel whose running direction is rotatable. By applying the bearing 10 to a swivel wheel, the bearing 10 can be rotated in accordance with the running direction of the moving body 1.

As another example of another application, the bearing 10 is used in a conveying device (drive module) for conveying banknotes, tickets, etc. That is, in the conveying device, the inner rings 22 of a pair of bearings 10 are attached to a support shaft 3, and the outer rings 21 and coating layers 18 are rotatably supported on the support shaft. The pair of coating layers 18 are arranged adjacent to each other. In this state, the outer rings 21 and coating layers 18 rotate, and banknotes, tickets, etc. are sandwiched between the pair of coating layers 18 and conveyed.

Since the coating layer 18 is formed on the outer ring 21, the coating layer 18 can reduce noise when bills, tickets, etc. are sandwiched and transported between the coating layers 18 of the bearing 10. In addition, since the coating layer 18 is firmly engaged with the outer peripheral surface 24 of the outer ring 21, it is possible to prevent the coating layer 18 from falling off from the outer peripheral surface 24 of the outer ring 21.
In this way, by providing the conveying device with the bearing 10, durability can be ensured and a low-cost conveying device can be obtained.

Next, the bearings of the second to sixth embodiments and the structures with thermoplastic elastomer coating layers of the seventh to eighth embodiments will be described with reference to Figures 5 to 11. Note that in the bearings of the second to sixth embodiments, the same or similar parts as those of the bearing 10 of the first embodiment are given the same reference numerals and detailed description will be omitted.

Second Embodiment
FIG. 5 is a cross-sectional view of a bearing 70 according to the second embodiment.
5, a bearing 70 has a coating layer 72 instead of the coating layer 18 of the first embodiment, and the other configuration is similar to that of the bearing 10 of the first embodiment. The coating layer 72 has a first material layer 73 and a second material layer 74 instead of the first material layer 43 and the second material layer 44 of the first embodiment.

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 similarly to the first outer peripheral surface 46 of the first material layer 43. The first inner peripheral surface 77 is formed similarly to 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.

The first side surface 78 extends from one end 77a of the first inner circumferential surface 77 to one end 76a of the first outer circumferential surface 76, inclining at an inclination angle θ1 from the center to the outside in the direction of the axis O of the outer ring 21. The second side surface 79 extends from the other end 77b of the first inner circumferential surface 77 to the other end 76b of the first outer circumferential surface 76, inclining at an inclination angle θ1 from the center to the outside 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. In other words, the first material layer 73 is formed so that the width dimension W1 gradually increases from the outer circumferential surface 24 of the outer ring 21 toward the radially outward side.

The second material layer 74 forms an outer peripheral surface layer of the covering 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 similarly to the outer peripheral surface layer 52 of the second material layer 44. The first side surface layer 83 has a first inner 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 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 layer 83 (particularly, the first inner side surface 83a) can be suitably inserted into the first side surface 78. Also, the second side layer 84 (particularly, the second inner side surface 84a) can be suitably inserted into the second side surface 79.

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 the first material layer 73 (i.e., the outer peripheral surface 24 of the outer ring 21).
Furthermore, according to the bearing 70 of the second embodiment, similar to the bearing 10 of the first embodiment, the bearing 70 in which the coating layer 72 is formed on the outer peripheral surface 24 of the outer ring 21 can be mass-produced at low cost.

Third Embodiment
FIG. 6 is a cross-sectional view of a bearing 90 according to a third embodiment.
6, a bearing 90 has a coating layer 92 instead of the coating layer 18 of the first embodiment, and the other configuration is similar to that of the bearing 10 of the first embodiment. The coating layer 92 has a first material layer 93 and a second material layer 94 instead of the first material layer 43 and the second material layer 44 of the first embodiment.

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 formed in the same manner as the first inner peripheral surface 47 of the first material layer 43, and has the same width as the outer peripheral surface 24 of the outer ring 21. The first inner peripheral surface 97 has a large contact area with the outer peripheral surface 24 of the outer ring 21. Therefore, 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.

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

The second material layer 94 is formed in the same manner as the second material layer 44 of the first embodiment. That is, the second material layer 94 forms the outer peripheral surface layer of the coating layer 92. The second material layer 94 has an outer peripheral surface layer 52, a first side layer 53, and a second side layer 54, similar to the second material layer 44. The second material layer 94 is cooled and contracted, so that the entire area of the first side surface 98a and the second side surface 99a can be sandwiched between the first side layer 53 and the second side layer 54. In addition, the inner peripheral surface 53a of the first side layer 53 is heat-sealed to the first peripheral surface 98b. The inner peripheral surface 54a of the second side layer 54 is heat-sealed to the second peripheral surface 99b.
This allows the second material layer 94 to be firmly engaged with the first material layer 93 .

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. In addition, the second material layer 94 is firmly engaged with the first material layer 93. In particular, the inner peripheral surface 53a of the first side layer 53 is heat-sealed to the first peripheral surface 98b, and the inner peripheral surface 54a of the second side layer 54 is heat-sealed to the second peripheral surface 99b, so that the second material layer 94 is even more firmly engaged with the first material layer 93. This makes it even more difficult for the second material layer 94 to fall off from the first material layer 93.

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. This makes it possible to prevent the coating layer 92 from falling off the outer peripheral surface 24 (i.e., the outer ring 21).
Furthermore, according to the bearing 90 of the third embodiment, similar to the bearing 10 of the first embodiment, the bearing 90 in which the coating layer 92 is formed on the outer peripheral surface 24 of the outer ring 21 can be mass-produced at low cost.

Fourth Embodiment
FIG. 7 is a cross-sectional view of a bearing 110 according to a fourth embodiment.
7, a bearing 110 has a coating layer 112 instead of the coating layer 18 of the first embodiment, and the other configuration is similar to that of the bearing 10 of the first embodiment. The coating layer 112 has a first material layer 113 and a second material layer 114 instead of the first material layer 43 and the second material layer 44 of the first embodiment.

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 similar to the first outer peripheral surface 46 of the first material layer 43, and is formed to the same width as the outer peripheral surface 24 of the outer ring 21. The first inner peripheral surface 117 is similar to the first inner peripheral surface 47 of the first material layer 43, and is formed to the same width as the outer peripheral surface 24 of the outer ring 21. The first inner peripheral surface 117 has a large area in contact 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.

The second material layer 114 forms an outer peripheral surface layer of the coating layer 112. 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, similar to the second material layer 44 of the first embodiment. The outer peripheral surface layer 122 is formed similar to 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 edge 24a and the second edge 24b) of the outer peripheral surface 24 of the outer ring 21.
The first side layer 123 is in contact with the first side 118 of the first material layer 113. The second side layer 124 is in contact with the second side 119 of the first material layer 113.

As 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. This allows the second material layer 114 to be firmly engaged with the first material layer 113.
In this manner, the first material layer 113 is firmly fixed to the outer circumferential surface 24 of the outer ring 21 by cooling and shrinking after injection molding. In addition, the second material layer 114 is firmly engaged with the first material layer 113.

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. This makes it possible to prevent the coating layer 112 from falling off the outer peripheral surface 24 (i.e., the outer ring 21).
Furthermore, according to the bearing 110 of the fourth embodiment, similar to the bearing 10 of the first embodiment, the bearing 110 in which the coating layer 112 is formed on the outer peripheral surface 24 of the outer ring 21 can be mass-produced at low cost.

Fifth Embodiment
FIG. 8 is a cross-sectional view of a bearing 130 according to a fifth embodiment.
8, the bearing 130 has a similar configuration to the bearing 110 of the fourth embodiment, except that the coating layer 112 of the fourth embodiment is replaced with a coating layer 132. The coating layer 132 has a second material layer 134 instead of the second material layer 114 of the fourth embodiment, and further includes a first material layer 113 similar to that of the fourth embodiment.
As in the fourth embodiment, the first material layer 113 is firmly fixed to the outer circumferential surface 24 of the outer ring 21 by cooling and shrinking after injection molding.

The second material layer 134 forms the outer peripheral surface layer of the coating layer 132. The second material layer 134 is similar to the outer peripheral surface layer 122 of the fourth embodiment, and is formed to be 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 formed flush with the first edge 24a of the outer peripheral surface 24 of the outer ring 21. The second layer side surface 137 is formed flush with the second edge 24b of the outer peripheral surface 24 of the outer ring 21. In other words, the second material layer 134 is formed to have the same width dimension W2 as the outer peripheral surface 24 of the outer ring 21 and the first material layer 113.
The second layer of material 134 is securely heat sealed to the first outer circumferential surface 116 of the first layer of material 113 .

In this manner, the first material layer 113 is firmly fixed to the outer circumferential surface 24 of the outer ring 21 by cooling and shrinking after injection molding. In addition, the second material layer 134 is firmly engaged with the first material layer 113.
As a result, 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 .

Sixth Embodiment
FIG. 9 is a cross-sectional view of a bearing 140 according to the sixth embodiment.
9, a bearing 140 has a similar configuration to the bearing 10 of the first embodiment, except that the coating layer 18 of the first embodiment is replaced with a coating layer 142. The coating layer 142 has a second material layer 144 instead of the second material layer 44 of the first embodiment, and further includes a first material layer 43 similar to that of the first embodiment.

The second material layer 144 forms an outer peripheral surface layer of the coating layer 142. The second material layer 144 has an outer peripheral surface layer 146, a first side layer 53, and a second side 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 other portions are similar to the outer peripheral surface layer 52 of the first embodiment.
The coated outer peripheral surface 147 has a first end 147a and a second end 147b. The coated outer peripheral surface 147 is formed in a curved shape so that the outer diameter gradually decreases from the first end 147a to the second end 147b. The coated outer peripheral surface 147 may also be formed in a straight shape so that the outer diameter gradually decreases.

The parting line PL of the mold is located at the first end 147a. That is, the coating outer peripheral surface 147 is curved so 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 and the second material layer 144), the movable part of the mold is opened in the direction of the arrow, thereby preventing burrs from being generated on the coating outer peripheral surface 147.
This makes it possible to eliminate the need for post-processing to remove burrs from the coated outer peripheral surface 147 after the coating layer 142 (first material layer 43 , second material layer 144 ) is insert molded onto the outer peripheral surface 24 of the outer ring 21 .

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 the coated outer peripheral surface 147 conveys banknotes, tickets, etc., or when the coated outer peripheral surface 147 moves while rolling over a contact object, the contact area with the banknotes, tickets, contact object, etc. can be kept small. This has the effect of reducing sound (noise) when the coated outer peripheral surface 147 conveys banknotes, tickets, etc., or when the coated outer peripheral surface 147 moves while rolling over a contact object.

Furthermore, 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. This makes it possible to prevent the coating layer 142 from falling off the outer peripheral surface 24 (i.e., the outer ring 21).
Furthermore, according to the bearing 140 of the sixth embodiment, similar to the bearing 10 of the first embodiment, the bearing 140 in which the coating layer 142 is formed on the outer peripheral surface 24 of the outer ring 21 can be mass-produced at low cost.

In the first to sixth embodiments, examples have been described in which the coating layers 18, 72, 92, 112, 132, and 142 are formed on the bearings 10, 70, 90, 110, 130, and 140 as structures with thermoplastic elastomer coating layers, but this is not limiting. As in the seventh and eighth embodiments, the coating layers 154 and 164 may be formed on the cylindrical member 152 and the flat member 162.

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

The first material layer 155 is made of the same amorphous plastic as the first material layer 43 (see FIG. 1) of the first embodiment. The second material layer 156 forms an outer peripheral surface layer of the covering layer 154. The second material layer 156 is made 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, similarly 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 circumferential surface 153 of the cylindrical member 152. This makes it possible to prevent the coating layer 154 from falling off from the outer circumferential surface 153 of the cylindrical member 152.
Furthermore, according to the seventh embodiment, the structure 150 with a thermoplastic elastomer coating layer, similar to the bearing 10 of the first embodiment, the structure 150 with a thermoplastic elastomer coating layer in which a coating layer 154 is formed on the outer peripheral surface 153 of a cylindrical member 152 can be mass-produced at low cost.

The cylindrical member 152 may have a groove formed on the outer circumferential surface 153, similar to the bearing 10 of the first embodiment. The groove is formed annularly in the circumferential direction of the outer circumferential surface 153. It is also possible to form multiple grooves at intervals in the axial direction of the outer circumferential surface 153.

In the seventh embodiment, an example was described in which a first material layer 155 and a second material layer 156 were formed as the coating layer 154 on the cylindrical member 152, but this is not limited to this. As another example, a first material layer 155 and a second material layer 156 may be formed as the coating layer 154 on the cylindrical member.

Eighth embodiment
FIG. 11 is a cross-sectional view of a structure 160 with a thermoplastic elastomer coating layer according to the eighth embodiment.
11, in a structure 160 with a thermoplastic elastomer coating layer, a coating layer 164 is formed on an outer surface 163 of a flat member 162. The flat member 162 is made of a metal material such as stainless steel.
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 .

The flat member 162 has, for example, a protrusion 171 on the outer surface 163. The protrusion 171 has a leg 172 protruding in a direction intersecting with the outer surface 163, and an extension 173 formed on a tip 172a of the leg 172. The protrusion 171 is formed in a T-shape by the leg 172 and the extension 173. In other words, the outer surface 163 of the flat member 162 is a flat outer surface having irregularities.
The protrusions 171 are covered with a first material layer 165 formed on the outer surface 163 of the flat member 162. The first material layer 165 is made of the same amorphous plastic as the first material layer 43 (see FIG. 1) of the first embodiment. The first material layer 165 is engaged with the protrusions 171, and is thereby firmly engaged with the outer surface 163 of the flat member 162.

A second material layer 166 is formed on an outer surface 165a of the first material layer 165. The second material layer 166 forms an 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 (first side surface 165b, second side surface 165c) of the first material layer 165 are sandwiched between the first side surface layer 176 and the second side surface layer 177 of the second material layer 166. Thus, as the second material layer 166 cools and contracts, the first side surface 165b and the second side surface 165c of the first material layer 165 can be sandwiched between the second material layer 166 (the first side surface layer 176, the second side surface layer 177). This allows the second material layer 166 to be firmly engaged with the first material layer 165.

According to the structure 160 with a thermoplastic elastomer coating layer of the eighth embodiment, similarly 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. This makes it possible to prevent the coating layer 164 from falling off from the outer surface 163 of the flat member 162.
Furthermore, according to the eighth embodiment, the structure 160 with a thermoplastic elastomer coating layer, similar to the bearing 10 of the first embodiment, the structure 160 with a thermoplastic elastomer coating layer in which a coating layer 164 is formed on the outer surface 163 of a flat member 162 can be mass-produced at low cost.

Here, modified examples of the first to sixth embodiments will be described. That is, in the first to sixth embodiments, examples have been described in which the outer ring 21 of the bearings 10, 70, 90, 110, 130, and 140 is made of a metal material, but this is not limiting. As a bearing modified example of the first to sixth embodiments, for example, the outer ring 21 of the bearings 10, 70, 90, 110, 130, and 140 may be made of hard plastic (amorphous plastic).
By forming the outer ring 21 from amorphous plastic, the second material layers (outer peripheral surface layers) 44, 74, 94, 114, 134, 144, 156, and 166 can be formed directly on the amorphous plastic outer ring 21. This makes it possible to eliminate the first material layers 43, 73, 93, 113, 155, and 165, simplifying the configuration.
Furthermore, the outer ring 21 and the first material layers 43, 73, 93, 113, 155, and 165 may be integrally formed from hard plastic (amorphous plastic), thereby obtaining the same effects as those of the first to sixth embodiments.

Modifications of the seventh to eighth embodiments will now be described. That is, in the seventh to eighth embodiments, examples have been described in which the cylindrical member 152 and the flat member 162 are made of a metal material, 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 made of hard plastic (amorphous plastic).
By forming the cylindrical member 152 and the flat member 162 from amorphous plastic, the second material layers 156, 166 can be formed directly on the amorphous plastic cylindrical member 152 and the flat member 162. This makes it possible to eliminate the first material layers 155, 165, and simplifies the configuration.
Also, the cylindrical member 152 and the flat member 162 may be integrally formed with the first material layers 155 and 165 from hard plastic (amorphous plastic), thereby obtaining the same effects as those of the seventh to eighty-sixth embodiments.

(Modification)
FIG. 12 is a cross-sectional view of a bearing according to a modified 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 with a thermoplastic elastomer that is filled from a gate G2 having a larger gate diameter D1.
The gate G2 is opened so that a gate diameter D1 is larger than a thickness dimension T3 of the second material layer 44. Furthermore, the gate G2 is disposed so as to overlap both the first material layer 43 and the second material layer 44 in the axial direction.
By filling the inside (cavity) of the mold with thermoplastic elastomer from gate G2, a second material layer 44 is insert molded onto the first material layer 43 and the first side portion 24c and second side portion 24d of the outer peripheral surface 24.

By forming the gate diameter D1 of the gate G2 large and positioning the gate G2 so as to overlap both the first material layer 43 and the second material layer 44, the second material layer 44 can be well molded even when the wall thickness dimension T3 of the second material layer 44 is made small.
Furthermore, the thermoplastic elastomer can be filled with a large pressure into the outer surface 53b of the first material layer 43 (specifically, the first side layer 53). This makes it possible to increase the adhesion between the first material layer 43 and the second material layer 44.

In the modified example, the second material layer 44 of the bearing 10 is molded using a gate G2 with a large gate diameter D1, but this is not limited to the above example. As another example, the second material layers 74, 94, 114, and 144 of the bearings 70, 90, 110, and 140 may be molded using a gate G2 with a large gate diameter D1.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
In the first to seventh embodiments, the coating layers 18, 72, 92, 112, 132, 142, 154, and 164 of the bearings 10, 70, 90, 110, 130, and 140 are used for rotational sliding, but the present invention is not limited to this. As another example, the coating layers 18, 72, 92, 112, 132, 142, 154, and 164 can be used as a member (substitute for an O-ring) for fixing the bearings 10, 70, 90, 110, 130, and 140 to other members, or as an insulating member for preventing electrolytic corrosion.

In addition, in the first to seventh embodiments, examples have been described in which the coating layers 18, 72, 92, 112, 132, 142, 154, and 164 are provided on the outer peripheral surface 24 of the outer ring 21, but this is not limited to this. As another example, a coating layer may be provided on the inner peripheral surface of the inner ring 22.

Furthermore, in the first to sixth embodiments, examples have been described in which a first material layer and a second material layer are formed on the outer ring 21 of the bearings 10, 70, 90, 110, 130, and 140, but the present invention is not limited to this. As another example, for example, a first material layer, a second material layer, and a third material layer may be formed in sequence 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.
This makes it possible to reduce noise when the bearing is driven, and also to realize a bearing with excellent wear resistance and durability.

In the first to seventh embodiments, the width of the coating layers 18, 72, 92, 112, 132, and 142 is set to be the same as the width of the ring 12, but this is not limiting. As another example, the width of the coating layers 18, 72, 92, 112, 132, and 142 may be set to be smaller than that of the ring 12. Hereinafter, the coating layers 18, 72, 92, 112, 132, and 142 will be abbreviated as "coating layers 18...".
By reducing the width dimension of the coating layers 18..., the amount of material used to form the coating layers 18... can be reduced, and by reducing the contact area of the second material layer (i.e., the outer surface layer) of the coating layers 18..., sound (noise) can be reduced.

In addition, in the first to seventh embodiments, a groove or a embossed portion may be formed on the first outer peripheral surface 46, 76, 96, 116, 155a, 165a of the first material layer 43, 73, 93, 113, 155, 165. The groove is formed, for example, to extend in the axial direction of the bearing. By forming a groove or a embossed portion on the first outer peripheral surface 46, 76, 96, 116, 155a, 165a, the bonding strength of the second material layer to the first outer peripheral surface of the first material layer can be increased.

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 (outer surface formed in a circular shape)
28 ... Groove portion 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 first material layer)
52, 82, 122, 146, 175...Outer surface layer 53, 54, 83, 84, 123, 124, 176, 177...First and second side layers (a pair of side layers)
163: Outer surface 165a: Outer surface of first material layer (outer surface of first material layer)
171...Protrusion

Claims (11)

A coating layer is provided on an outer peripheral surface of a cylindrical member,
the covering layer has an outer peripheral surface layer formed by heat-sealing a thermoplastic elastomer,
The coating layer is
a first material layer made of amorphous plastic on the outer peripheral surface;
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-sealing the thermoplastic elastomer containing potassium titanate fiber to the outer surface of the first material layer,
A structure with a thermoplastic elastomer coating layer, wherein the second material layer is made of a material softer than the first material layer. A coating layer is formed on an outer surface having projections and recesses,
the covering layer has an outer peripheral surface layer formed by heat-sealing a thermoplastic elastomer,
The coating layer is
a first material layer on the outer surface, the first material layer being made of an amorphous plastic;
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-sealing the thermoplastic elastomer containing potassium titanate fiber to the outer surface of the first material layer,
A structure with a thermoplastic elastomer coating layer, wherein the second material layer is made of a material softer than the first material layer. The structure with a thermoplastic elastomer coating layer described in claim 1, characterized in that the outer peripheral surface is the outer peripheral surface of an outer ring provided with 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 3, characterized in that the outer peripheral surface of the outer ring is provided with a groove extending in the circumferential direction. The second material layer is
an outer peripheral layer covering an outer surface of the first material layer;
A structure with a thermoplastic elastomer coating layer as described in claim 3 or claim 4, characterized in that it has a pair of side layers connected to the outer peripheral surface layer and covering both axial side surfaces of the first material layer. A structure with a thermoplastic elastomer coating layer as described in claim 5, characterized in that a pair of side 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 or 6, characterized in that the first material layer is formed so that the width dimension gradually increases from the outer circumferential surface toward the radially outward direction. A coating layer is provided on an outer peripheral surface of an outer ring of a cylindrical bearing,
The outer ring is formed of an amorphous plastic,
the covering layer includes an outer peripheral surface layer that forms the outer peripheral surface of the covering layer by heat-fusing a thermoplastic elastomer containing potassium titanate fibers to the outer peripheral surface of the outer ring,
A structure with a thermoplastic elastomer coating layer, wherein the outer peripheral surface layer is made of a material that is softer than the outer ring. a gate mark is provided on an outer surface of the second material layer;
The structure with a thermoplastic elastomer coating layer described in any one of claims 1 to 7, characterized in that the gate mark when viewed from the axial direction is formed so that its outer shape is larger than the thickness dimension of the second material layer and is arranged so as to overlap both the second material layer and the first material layer in the axial direction. A moving body having a plurality of structures with a thermoplastic elastomer coating layer according to any one of claims 1 to 9, the structures with a thermoplastic elastomer coating layer being bearings, the inner rings of the plurality of bearings being fixed to a main body, the coating layers of the plurality of bearings being in contact with a contact object, and the coating layers and the outer rings of the bearings to which the coating layers are fixed function as wheels that roll against the contact object. A conveying device comprising a pair of structures with thermoplastic elastomer coating layers according to any one of claims 1 to 9, the structures with thermoplastic elastomer coating layers being bearings, the coating layers being arranged adjacent to each other, the inner ring of the bearing being attached to a support shaft, and the outer ring of the bearing and the coating layers rotating to convey an object sandwiched between the pair of coating layers.

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