JP2020051615A - Structure - Google Patents

Abstract

To provide a structure that can be manufactured in large quantities at low cost, in which a covering layer is sufficiently fixed to a metal member, and that has high reliability.SOLUTION: A bearing 10 is a structure comprising an outer ring 21 made of a metal member, and a covering layer 18 formed on the outer ring 21. The covering layer 18 comprises a first material layer 43 formed on the outer ring 21, and a second material layer 44 formed on the first material layer 43. The first material layer 43 includes an amorphous thermoplastic resin and a thermoplastic elastomer. The second material layer 44 includes a thermoplastic elastomer. The second material layer 44 is a softer material than the first material layer 43.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a structure.

For example, as applications of a rolling bearing, it is known that a conveyed object such as a bill or a ticket is conveyed by an outer ring of the rolling bearing, or that the rolling bearing can be rolled along a contact object as a wheel of a moving body. In this case, for example, on the outer peripheral surface of the outer ring made of a metal member, in order to increase the frictional force with a conveyed object or a contact object, or to reduce the sound (noise) when the outer ring operates while rolling and contacting, A coating layer may be formed using urethane rubber for the outer ring.
Urethane rubber has excellent abrasion resistance and can be firmly adhered and fixed to the outer ring. The manufacturing process for mounting urethane rubber on the outer ring is as follows.

  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, a urethane raw material (liquid) is poured between the outer peripheral surface and the mold, and the mold is formed by applying pressure to the mold. Next, the mold is held at a high temperature for a predetermined time (half day to about one day depending on the hardness). The urethane rubber is cured at a high temperature, and a high temperature is applied to the adhesive to cure and bond the urethane rubber to the outer peripheral surface. After vulcanization bonding, the outer peripheral surface of the urethane is finished to predetermined dimensions and accuracy by polishing. As a result, the outer peripheral surface of the outer ring of the rolling bearing is coated with urethane rubber (for example, see Patent Document 1).

JP-A-6-87717

However, the conventional rolling bearing has 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 the urethane rubber is cured, the outer peripheral surface of the urethane is polished to a predetermined size and accuracy. It is necessary to finish.
Therefore, when mass-producing a rolling bearing in which the outer peripheral surface is coated with urethane rubber, it is necessary to provide a large number of facilities for coating the outer peripheral surface with urethane rubber, which increases the equipment cost. Further, a step of roughly processing the outer peripheral surface of the outer ring by sandblasting and a step of applying an adhesive to the roughly processed outer peripheral surface are required. For this reason, it is difficult to manufacture inexpensively a large number of rolling bearings coated with urethane rubber.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a highly reliable structure that can be mass-produced inexpensively, has a coating layer that is sufficiently fixed to a metal member, and has high reliability. is there.

In order to solve the above problem, a structure according to one embodiment of the present invention is a structure including a metal member and a coating layer formed on the metal member, wherein the coating layer is formed of the metal. A first material layer formed on the member and a second material layer formed on the first material layer, wherein the first material layer is made of an amorphous thermoplastic resin and a thermoplastic resin. An elastomer, wherein the second material layer includes a thermoplastic elastomer, and the second material layer is a material softer than the first material layer.
According to this configuration, by including the amorphous thermoplastic resin in the first material layer, the heat-fusibility with the second material layer is increased, and the second material layer becomes the first material layer. Fully fixed. In addition, by including the thermoplastic elastomer in the first material layer, cracks and cracks are generated in a weld portion of the first material layer due to heat generated when the second material layer is formed on the first material layer. This can be suppressed. As a result, the pulling force of the first material layer hardly decreases, and the first material layer is sufficiently fixed to the metal member. In addition, the first material layer and the second material layer can be better heat-sealed. As a result, the second material layer can be more firmly fixed to the first material layer, and the second material layer can be more reliably prevented from falling off the metal member. Therefore, the covering layer is sufficiently fixed to the metal member, and a highly reliable structure can be obtained.
In addition, by including the thermoplastic elastomer in the second material layer, the second material layer can be firmly fixed to the first material layer by thermal fusion. Therefore, the sandblasting process and the application process using an adhesive, which have been conventionally required, can be eliminated. Thereby, the structure can be manufactured inexpensively and in large quantities.
Further, a harder material can be used for the first material layer by making the second material layer a material softer than the first material layer. The soft material refers to a material having a small flexural modulus and hardness (for example, durometer A (durometer hardness A)). A hard material refers to a material having a large flexural modulus and hardness (for example, durometer A (durometer hardness A)).
Further, by making the second material layer a material softer than the first material layer, the second material layer can be more firmly fixed to the first material layer by thermal fusion. In addition, for example, when the structure is a bearing, when a conveyed object such as a bill or a ticket is conveyed by the outer ring, or when the bearing is rolled along a contact object as a wheel of the moving body, the sound is generated by the second material layer. (Noise) can be reduced.

Further, it is preferable that the first material layer further includes an inorganic fiber.
According to this configuration, the second material layer is firmly fixed to the first material layer.

When the melting point of the thermoplastic elastomer contained in the second material layer is Tm and the glass transition temperature of the amorphous thermoplastic resin contained in the first material layer is Tg, the following formula (1) is obtained. It is preferable to satisfy the following.
Tm ≧ Tg-5 (1)
According to this configuration, the second material layer is firmly fixed to the first material layer.

Further, it is preferable that the thermoplastic elastomer contained in the first material layer and the thermoplastic elastomer contained in the second material layer are of the same type.
According to this configuration, the second material layer is firmly fixed to the first material layer.

Further, it is preferable that the amorphous thermoplastic resin is a polycarbonate resin.
According to this configuration, the pulling force of the first material layer is less likely to decrease, and the first material layer is firmly fixed to the metal member.

Further, the content of the thermoplastic elastomer contained in the first material layer is preferably 1 to 14% by mass based on the total mass of the first material layer.
According to this configuration, the occurrence of cracks and cracks in the weld portion of the first material layer can be further suppressed. As a result, the pulling force of the first material layer is less likely to decrease, and the first material layer is firmly fixed to the metal member. In addition, the shrinkage at the time of molding does not easily increase, and precise molding is facilitated.

  ADVANTAGE OF THE INVENTION According to this invention, it can manufacture in large quantities at low cost, a coating layer is fully fixed to a metal member, and a highly reliable structure can be provided.

It is a sectional view showing a bearing as a structure concerning a first embodiment of the present invention. It is a side view showing the modification of the bearing concerning a first embodiment of the present invention. It is a side view showing the mobile provided with the bearing concerning a first embodiment of the present invention. It is a sectional view showing a bearing as a structure concerning a second embodiment of the present invention. It is a sectional view showing a bearing as a structure concerning a third embodiment of the present invention. It is a sectional view showing the structure concerning a 4th embodiment of the present invention. (A) is sectional drawing explaining the measuring method of the extraction force of a 2nd material layer, (b) is sectional drawing explaining the measuring method of the extraction force of a 1st material layer. 5 is a graph showing characteristics in a state where a potassium titanate fiber is contained in a thermoplastic elastomer.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the first to third embodiments, the structure will be described as bearings 10, 130, and 140.

[First embodiment]
FIG. 1 is a 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 wheel 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 disposed radially inside the outer ring 21.
The plurality of rolling elements 14 are annularly arranged between the outer ring 21 and the inner ring 22 constituting the wheel body 12. The retainer 16 rotatably holds the plurality of rolling elements 14 in a state of being uniformly arranged in the circumferential direction.

The outer ring 21 is a metal member made of a metal material such as stainless steel and bearing steel. The outer ring 21 is a cylindrical member, and is formed by, for example, forging, cutting, grinding, or other mechanical processing. The outer ring 21 has an outer peripheral surface (that is, an 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 a ring shape outside the outer ring 21 in the radial direction. The inner peripheral surface 25 is formed in a ring shape radially inside the outer ring 21. The central portion 26 is formed at the center in the direction of the axis O. The central portion 26 is formed such that a portion 25 a of the inner peripheral surface 25 at the center in the direction of the axis O is spaced radially inward from the outer peripheral surface 24 of the outer race 21 at an interval T1. A concave portion is formed as a groove 28 extending in the circumferential direction in a portion of the outer peripheral surface 24 corresponding to the central portion 26.

The groove portion 28 has a deepest portion 28a radially inward of the outer peripheral surface 24. The deepest part 28a is the deepest part of the groove 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 28 has a curved cross section at the center of the outer ring 21 in the direction of the axis O, and is opened radially outward of the outer ring 21. The groove 28 is formed symmetrically with respect to the center of the outer ring 21 in the direction of the axis O.

  The pair of outer portions 27 are formed symmetrically with respect to the center of the outer ring 21 in the direction of the axis O outside the center portion 26 in the direction of the axis O. The pair of outer portions 27 are formed such that a portion of the inner peripheral surface 25 on the outer side in the axis O direction is spaced radially inward from the outer peripheral surface 24 of the outer ring 21 at an interval T2. The interval T1 between the central portions 26 is set larger than the interval T2 between the pair of outer portions 27. That is, the thickness of the central portion 26 is larger than the thickness of the pair of outer portions 27.

An outer race rolling surface 29 is formed in a portion 25 a of the central portion 26 of the inner peripheral surface 25. The outer ring rolling surface 29 has a circular arc-shaped cross section along the outer surface of the rolling element 14. The radius of curvature in the cross section of the outer race 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 race rolling surface 29 is formed over the entire circumference of the inner peripheral surface 25 of the outer race 21. The outer surface of the plurality of rolling elements 14 can abut on the outer ring rolling surface 29.
The outer race rolling surface 29 is formed at the center in the direction of the axis O, and is arranged at a position overlapping the groove 28 in the radial direction of the outer peripheral surface 24.

The groove 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 and the outer peripheral surface 24 in the radial direction. On the other hand, the groove 28 has a curved cross section. Therefore, it is possible to suppress the influence of the deformation of the outer ring 21 and the decrease in the rigidity of the outer ring 21 due to the groove 28 on the outer ring rolling surface 29.
Furthermore, since the cross-sectional shape of the groove 28 is formed as a curved surface, the flat surface is not provided on the bottom surface of the groove 28. Accordingly, when the groove 28 is machined with the cutting tool, the cutting resistance of the cutting tool can be reduced, and the machining of the groove 28 is facilitated. Further, by reducing the cutting resistance of the cutting tool, the life of the cutting tool can be extended.
In addition, the groove 28 is formed symmetrically with respect to the center of the outer ring 21 in the direction of the axis O. A groove 28 is formed in the center of the outer peripheral surface 24 of the outer ring 21 with good balance. Thereby, the influence of the deformation of the outer ring 21 and the decrease in the rigidity of the outer ring 21 due to the groove 28 on the outer ring rolling surface 29 can be more favorably suppressed.

Here, the groove 28 is provided at the center of the outer race 21 in the direction of the axis O, and the outer race rolling surface 29 is also provided at the center of the outer race 21 in the direction of the axis O. Thereby, the influence of deformation due to heat treatment such as quenching of the outer ring 21 can be reduced. In particular, the outer ring 21 is formed such that the thickness of the central portion 26 is larger than the thickness of the pair of outer portions 27. A groove 28 is formed in a portion of the central portion 26 where the thickness dimension is large. Thereby, the thickness dimension for forming the groove 28 can be secured.
Further, the groove 28 has a curved cross section. On the other hand, the outer race rolling surface 29 also has a curved cross section. That is, the groove 28 is formed in the same shape as the outer race rolling surface 29. Thereby, the influence of deformation due to heat treatment such as quenching of the outer ring 21 can be further reduced.

  Note that, in the first embodiment, an example in which the groove 28 is formed in a curved surface in a cross section has been described. However, the present invention is not limited to this, and the groove 28 may be formed in a shape such as a V-shaped cross section or a U-shaped cross section. . The same effect as in the first embodiment can be obtained also when the groove 28 is formed in a V-shaped cross section, a U-shaped cross section, or the like.

The inner ring 22 is a metal member made of a metal material such as stainless steel. The inner ring 22 is a substantially cylindrical member having a predetermined thickness in the direction of the axis O, and is formed by, for example, forging or machining.
An inner race rolling surface 33 is formed at an intermediate portion of the outer peripheral surface 32 of the inner race 22 in the direction of the axis O. The inner ring rolling surface 33 has an arc-shaped cross section 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 outer periphery 32 of the inner ring 22. The outer surface of the plurality of rolling elements 14 can contact the inner ring rolling surface 33.

  By fixing the inner ring 22 to the support shaft 41, the coating layer 18 rotates together with the outer ring 21. The coating outer peripheral surface 52c of the second material layer 44 constituting the coating layer 18 is, for example, a surface that conveys bills, tickets, or the like, or a surface that rolls the contact object 5 (see FIG. 3).

  The rolling element 14 is formed in a spherical shape using a metal material such as stainless steel or bearing 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 evenly arranged in a ring along the circumferential direction by the retainer 16 so as to freely roll. Grease for lubrication is sealed in the bearing 10.

  The 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 formed at the center of the outer peripheral surface 24 of the outer race 21 in the direction of the axis O. 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 and 49. Hereinafter, one of the pair of side surfaces 48, 49 will be referred to as a first side surface 48, and the other will be referred to as a second side surface 49.

The first inner peripheral surface 47 is fixed to the outer peripheral surface 24 of the outer race 21 and the groove 28 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 formed by connecting one end of the first outer peripheral surface 46 and one end of the first inner peripheral surface 47 so as to intersect the direction of the axis O of the bearing 10. The first side surface 48 is formed at a distance S1 from the first end edge 24a of the outer peripheral surface 24 toward the center of the outer peripheral surface 24 in the axis O direction. The second side surface 49 is formed at a distance S1 from the second edge 24b of the outer peripheral surface 24 toward the center of the outer peripheral surface 24 in the direction of the axis O.

The first material layer 43 includes an amorphous thermoplastic resin and a thermoplastic elastomer.
An amorphous thermoplastic resin has excellent heat-fusibility with a thermoplastic elastomer. When the first material layer 43 contains an amorphous thermoplastic resin, the heat-fusibility with the thermoplastic elastomer contained in the second material layer 44 described later is enhanced, and the first material layer 43 and the second And the second material layer 44 is sufficiently fixed to the first material layer 43.
Further, since the first material layer 43 contains a thermoplastic elastomer, cracks and cracks are generated in a weld portion of the first material layer due to heat generated when the second material layer is formed on the first material layer. This can be suppressed. As a result, the pulling force of the first material layer hardly decreases, and the first material layer 43 is sufficiently fixed to the outer ring 21. The first material layer 43 and the second material layer 44 can be better heat-sealed. Thereby, the second material layer 44 can be more firmly fixed to the first material layer 43, and the second material layer 44 can be more reliably prevented from falling off from the outer peripheral surface 24 of the outer race 21. Therefore, the coating layer 18 is sufficiently fixed to the outer ring 21, and the highly reliable bearing 10 can be obtained.

  The amorphous thermoplastic resin refers to a thermoplastic resin having a glass transition temperature and no melting point or heat of fusion (excluding a thermoplastic elastomer described below). Note that the amorphous thermoplastic resin does not show a definite melting point or a measurable heat of fusion, but includes those which show some crystallinity when cooled slowly. The glass transition temperature, melting point and heat of fusion of an amorphous thermoplastic resin can be measured using a differential scanning calorimeter (DSC), and the heat of fusion measured using a differential scanning calorimeter (DSC) is Those having less than 1 cal / g are defined as amorphous thermoplastic resins.

  The glass transition temperature of the amorphous thermoplastic resin is preferably 50 ° C. or higher, more preferably 70 ° C. or higher, even more preferably 130 ° C. or higher from the viewpoint of heat resistance. On the other hand, from the viewpoint of moldability, the glass transition temperature of the amorphous thermoplastic resin is preferably 250 ° C. or lower, more preferably 200 ° C. or lower, and even more preferably 170 ° C. or lower.

Examples of the amorphous thermoplastic resin include polycarbonate resin, acrylonitrile-butadiene-styrene (ABS) resin, polystyrene resin, polyphenylene ether resin, aromatic polysulfone resin, aromatic polyethersulfone resin, aromatic amorphous polyamide resin, and polystyrene. Ether imide resins and the like can be mentioned. Among these, polycarbonate resin is preferred from the viewpoint that the force of pulling out the first material layer 43 is less likely to decrease and the first material layer 43 is firmly fixed to the outer ring 21.
The type of the polycarbonate resin is not particularly limited, and a known resin can be used. The polycarbonate resin can be produced by a conventional method (for example, a phosgene method, a transesterification method, or the like). In addition, in this specification, a polycarbonate resin means a polymer having a basic structure having a structural unit represented by the following general formula (i).

In the formula (i), X ¹ is a divalent hydrocarbon group, and n is 1 or more. The divalent hydrocarbon group may have a hetero atom or a hetero bond introduced in the chain for the purpose of imparting various properties.

Polycarbonate resins are classified into aromatic polycarbonate resins (polycarbonate resins containing an aromatic dihydroxy compound as a polymer component) and aliphatic polycarbonate resins (polycarbonate resins containing an aliphatic dihydroxy compound as a polymer component). From the viewpoints of physical properties, electrical characteristics, and the like, aromatic polycarbonate resins are preferred.
One type of polycarbonate resin may be used, or two or more types may be used in combination in any combination and in any ratio. Further, the polycarbonate resin may be used as a resin obtained by mixing and alloying with another resin as long as the excellent properties of the present invention are not impaired. Examples of other resins used for alloying include acrylonitrile-styrene resin, ABS resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and the like.

The melt flow rate (hereinafter abbreviated as “MFR”) of the amorphous thermoplastic resin is, for example, 280 ° C. and a load of 2 from the viewpoint of moldability when a polycarbonate resin is used as the amorphous thermoplastic resin. The MFR value measured under conditions of 0.16 kg is preferably 0.1 g / 10 min or more, more preferably 15 g / 10 min or more, and even more preferably 30 g / 10 min or more. On the other hand, from the viewpoint of compatibility with the thermoplastic elastomer, the MFR value measured at 280 ° C. and a load of 2.16 kg is preferably 130 g / 10 min or less, more preferably 100 g / 10 min or less, and 80 g or less. / 10 min or less, more preferably 60 g / 10 min or less.
The MFR value of the amorphous thermoplastic resin is a value measured according to JIS K7210.

The thermoplastic elastomer is an elastomer having rubber-like elasticity at normal temperature (20 ° C.) and showing plasticity when heated. That is, the molecule has an amphoteric component of an elastic rubber component (soft segment) and a molecular constraint component (hard segment) for preventing plastic deformation.
Examples of the thermoplastic elastomer include a styrene-based thermoplastic elastomer (TPS), an olefin-based thermoplastic elastomer (TPO), a vinyl chloride-based thermoplastic elastomer (PPVC), and a urethane-based thermoplastic elastomer depending on the type of the soft segment and the hard segment. TPU) and polyester-based thermoplastic elastomer (TPEE). From the viewpoints of mechanical strength and wear resistance, TPU, TPEE, and TPS are preferable, and TPEE is more preferable.
TPU is the most excellent in abrasion resistance, but has a problem in moldability, and has high hygroscopicity and requires sufficient drying. Further, an annealing process is required, which takes time for the production and has a problem in molding accuracy. Further, TPU is the most excellent in mechanical strength and abrasion resistance among thermoplastic elastomers. For this reason, TPU is used when the coating layer 18 needs to have mechanical strength and abrasion resistance.
TPEE has the best abrasion resistance and mechanical strength among thermoplastic elastomers other than TPU, and also has excellent heat-fusibility with an amorphous thermoplastic resin. Further, TPEE is optimal as a material for the coating layer 18 because it has low hygroscopicity and good moldability.

  Thermoplastic elastomers have flexibility based on soft segments, and this flexibility can be expressed as durometer A (type A durometer hardness) measured according to JIS K6253. The durometer A is preferably 10 or more, more preferably 30 or more, still more preferably 45 or more, particularly preferably 55 or more, and preferably 95 or less, and 85 or less. It is more preferred that:

The MFR value of the thermoplastic elastomer is, for example, when TPEE is used as the thermoplastic elastomer, the MFR value measured at 280 ° C. and a load of 2.16 kg is 0.1 g / 10 min or more from the viewpoint of moldability. Is preferably 15 g / 10 min or more, and more preferably 30 g / 10 min or more. On the other hand, from the viewpoint of compatibility with the amorphous thermoplastic resin, the MFR value measured at 280 ° C. and a load of 2.16 kg is preferably 100 g / 10 min or less, more preferably 85 g / 10 min or less. More preferably, it is 60 g / 10 min or less.
The MFR value of the thermoplastic elastomer can be measured according to JIS K7210.

The thermoplastic elastomer is preferably one whose melting point is observed. The melting point of the thermoplastic elastomer is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, and even more preferably 120 ° C. or higher, from the viewpoint of improving heat resistance. On the other hand, from the viewpoint of moldability, the melting point of the thermoplastic elastomer is preferably 210 ° C. or lower, more preferably 180 ° C. or lower, and further preferably 160 ° C. or lower.
Here, in the case where the thermoplastic elastomer has two or more melting points due to the presence of two or more types of hard segments, from the viewpoint of sufficiently melting the thermoplastic elastomer to form the first material layer 43, The highest melting point is treated as the melting point of the thermoplastic elastomer.
The melting point of the thermoplastic elastomer is a value measured using DSC.

  The thermoplastic elastomer can be used in combination of two or more kinds as long as it satisfies the above structure, characteristics, and the like.

  The content of the thermoplastic elastomer contained in the first material layer 43 is 1 to the total mass of the first material layer 43 (that is, the total mass of all components contained in the first material layer 43). 14 mass% is preferable, and 2 to 12 mass% is more preferable. When the content of the thermoplastic elastomer is 1% by mass or more, generation of cracks and cracks in the weld portion of the first material layer 43 can be further suppressed. As a result, the pulling force of the first material layer 43 is less likely to decrease, and the first material layer 43 is firmly fixed to the outer ring 21. When the content of the thermoplastic elastomer is 14% by mass or less, the shrinkage during molding is hardly increased, and precise molding is facilitated.

  The mass ratio of the amorphous thermoplastic resin to the thermoplastic elastomer is preferably amorphous thermoplastic resin: thermoplastic elastomer = 70: 30 to 99: 1, and more preferably 85:15 to 95: 5. When the mass ratio between the amorphous thermoplastic resin and the thermoplastic elastomer is within the above range, the balance between the fixing force of the first material layer 43 to the outer ring 21 and the fixing force to the second material layer 44 is excellent.

It is preferable that the first material layer 43 further includes an inorganic fiber. Since the first material layer 43 further includes inorganic fibers, the second material layer 44 is firmly fixed by the first material layer 43. In addition, the amount of wear of the first material layer 43 can be reduced.
The inorganic fiber is preferably a powder composed of fibrous particles, and more preferably has an average fiber length of 1 to 300 μm and an average aspect ratio of 3 to 200. The average fiber length of the inorganic fibers is more preferably from 1 to 200 µm, further preferably from 3 to 100 µm, particularly preferably from 5 to 50 µm. The average aspect ratio of the inorganic fiber is more preferably from 3 to 100, still more preferably from 5 to 50, and particularly preferably from 8 to 40. By using the inorganic fibers having the average fiber length and the average aspect ratio in the above ranges, the second material layer 44 is firmly fixed to the first material layer 43.
The average fiber length and average fiber diameter of the inorganic fibers can be measured by observation with a scanning electron microscope (SEM), and the average aspect ratio (average fiber length / average fiber diameter) is calculated from the average fiber length and average fiber diameter. You can do it. For example, a plurality of inorganic fibers are photographed by a scanning electron microscope (SEM), and 300 inorganic fibers are arbitrarily selected from the observed image, the fiber length and the fiber diameter are measured, and all the fiber diameters are integrated. Then, the average fiber length can be obtained by dividing the number by the number, and the average fiber length can be obtained by integrating all the fiber diameters and dividing by the number.

  Specific examples of the inorganic fiber include glass fiber, carbon fiber, potassium titanate fiber, wollastonite fiber, aluminum borate fiber, magnesium borate fiber, zonotrite fiber, zinc oxide fiber, and basic magnesium sulfate fiber. . Among these, potassium titanate fiber and wollastonite fiber are preferable from the viewpoints of aggressiveness of a molding obtained to a partner material during sliding, abrasion of a molding machine, and mechanical properties.

As the potassium titanate fiber, conventionally known ones can be widely used, and examples thereof include potassium tetratitanate, potassium hexatitanate, and potassium octa titanate.
The size of potassium titanate is not particularly limited as long as it is within the range of the size of the above-mentioned inorganic fiber, but usually, the average fiber diameter is preferably 0.01 to 1 μm, more preferably 0.05 to 0.8 μm, 0.1 to 0.7 μm is more preferable. The average fiber length is preferably from 1 to 50 μm, more preferably from 3 to 30 μm, even more preferably from 10 to 20 μm. The average aspect ratio is preferably 10 or more, more preferably 10 to 100, and still more preferably 15 to 35.

Wollastonite fibers are inorganic fibers made of calcium metasilicate.
The size of wollastonite is not particularly limited as long as it is within the range of the above-mentioned inorganic fibers, but usually, the average fiber diameter is preferably 0.1 to 15 μm, more preferably 1 to 10 μm, and further preferably 2 to 7 μm. preferable. The average fiber length is preferably from 3 to 180 µm, more preferably from 10 to 100 µm, even more preferably from 20 to 40 µm. The average aspect ratio is preferably 3 or more, more preferably 3 to 30, and still more preferably 5 to 15.

One type of inorganic fiber may be used, or two or more types may be used in any combination and in any ratio.
The content of the inorganic fibers contained in the first material layer 43 may be appropriately determined according to the use of the bearing 10, for example, 1 to 50 mass with respect to the total mass of the first material layer 43. % Is preferable, 10 to 40% by mass is more preferable, and 20 to 35% by mass is further preferable.

The first material layer 43 is formed on the outer peripheral surface 24 and the groove 28 of the outer race 21 by injection molding. When the first material layer 43 is cooled, a force is applied so that the first material layer 43 comes into close contact with the outer peripheral surface 24 toward the center of the outer ring 21 (in the radial direction). It is fixed to the outer peripheral surface 24 and the groove 28.
The first material layer 43 is formed in a ring shape along the outer peripheral surface 24 with a material containing an amorphous thermoplastic resin and a thermoplastic elastomer. Therefore, the first material layer 43 is firmly attached to the outer peripheral surface 24 due to shrinkage when the first material layer 43 is cooled and hardened.
The first material layer 43 is filled in the groove 28. By filling the groove portions 28 of the outer peripheral surface 24 with the protrusions 43a of the first material layer 43, the groove portions 28 of the outer peripheral surface 24 and the protrusions 43a of the first material layer 43 are engaged in an uneven manner. Can be.

  Here, when insert-molding the first material layer 43 into the outer peripheral surface 24 and the groove portion 28 of the outer ring 21, the bearing 10 is housed in a molding die, and at least the end surface 21 a of the outer ring 21 in the axis O direction. , 21b are supported in contact with the mold. Thus, the first material layer 43 is insert-molded in the outer peripheral surface 24 and the groove 28 of the outer race 21 by supporting the end surfaces 21a and 21b with the molding die. Further, the first material layer 43 may be insert-molded on the outer ring 21 alone.

In addition, since the groove 28 is filled with the protrusion 43a of the first material layer 43, the protrusion 43a filled in the groove 28 functions as an anchor. Thereby, the outer ring 21 and the first material layer 43 are physically engaged, and the first material layer 43 can be more firmly fixed to the outer peripheral surface 24 and the groove 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 race 21, the first side portion 24 c and the second side portion 24 located on both side portions of the outer peripheral surface 24 in the direction of the axis O of the first material layer 43 are provided. The side part 24d is exposed to the outside.

The second material layer 44 is formed on the first material layer 43 and 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 and 54. Hereinafter, one of the pair of side layers 53 and 54 is referred to as a first side layer 53 and the other side layer is referred to as a 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 a layer that is connected to one end 52 a 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 52 b 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 race 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 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 includes a thermoplastic elastomer.
Since the second material layer 44 contains a thermoplastic elastomer, the heat-fusibility with the amorphous thermoplastic resin contained in the first material layer 43 is enhanced, and the first material layer 43 and the second material The layer 44 is thermally fused, and the second material layer 44 is sufficiently fixed to the first material layer 43.
Examples of the thermoplastic elastomer include the thermoplastic elastomers exemplified above in the description of the first material layer 43. Among them, TPU, TPEE and TPS are preferable. In particular, TPEE is optimal as the material of the second material layer 44 of the bearing 10 because it has low hygroscopicity and good moldability.

Here, in the present specification, the term “thermal fusion” means, for example, that the thermoplastic elastomer of the second material layer 44 is melted by heating and adheres to the first material layer 43 containing an amorphous thermoplastic resin. To do.
Thermal fusion is particularly effective during two-color molding.

From the viewpoint of suppressing sound (noise), the durometer A of the second material layer 44 is desirably 75 to 95. When the durometer A of the second material layer 44 is 75 or more, sound (noise) can be suppressed well, and the mechanical strength and wear resistance of the second material layer 44 can be secured well.
The durometer A is a value measured using a type A durometer based on JIS K6253.

The second material layer 44 is a material that is softer than the first material layer 43. 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. Therefore, the first material layer 43 in the molten state is injection-molded on the outer peripheral surface 24 of the outer ring 21 in a molten state, and the first material layer 43 in the molten state is cooled and solidified after the injection molding to form an annular first material layer. 43 contracts. Therefore, the first material layer 43 can be firmly fixed to the outer peripheral surface 24 of the outer race 21.
Here, in the present invention, the “soft material” means that at least one of the bending elastic modulus and the hardness (for example, durometer A (durometer hardness A)) of the second material layer 44 is the first material layer 43. Means less than.
The flexural modulus and hardness can be adjusted by the type and content of the thermoplastic elastomer or inorganic fiber.

In addition, from the viewpoint that the second material layer 44 is firmly fixed by the first material layer 43, the melting point of the thermoplastic elastomer included in the second material layer 44 is Tm, and the melting point of the thermoplastic elastomer included in the first material layer 43 is included. When the glass transition temperature of the amorphous thermoplastic resin is Tg, it is preferable that the following formula (1) is satisfied.
Tm ≧ Tg-5 (1)

  In addition, from the viewpoint that the second material layer 44 is firmly fixed by the first material layer 43, the thermoplastic elastomer contained in the first material layer 43 and the thermoplastic elastomer contained in the second material layer 44 are used. Are preferably the same type. For example, when the thermoplastic elastomer contained in the first material layer 43 is TPEE, it is preferable that the thermoplastic elastomer contained in the second material layer 44 is also TPEE.

In addition, the second material layer 44 may include an inorganic fiber, an amorphous thermoplastic resin, and other additives (other additives) as necessary.
Examples of the inorganic fibers include the inorganic fibers exemplified above in the description of the first material layer 43.
Examples of the amorphous thermoplastic resin include the amorphous thermoplastic resins exemplified above in the description of the first material layer 43.
Other additives include, for example, slidability improvers such as graphite, molybdenum disulfide, tungsten disulfide, boron nitride (BN), polytetrafluoroethylene (PTFE), polyethylene resin, silicone resin, etc .; Pigments such as titanium, and coloring agents such as dyes; mold release agents; thermal conductive agents; antistatic agents; nucleating agents; antioxidants (antioxidants); ultraviolet absorbers; One of these other additives may be used, or two or more of them may be used in any combination and in any ratio.

  According to the bearing 10 of the first embodiment described above, since the first material layer 43 contains the amorphous thermoplastic resin, the heat-fusibility with the second material layer 44 is improved, and the second material Layer 44 is fully fixed to first material layer 43. In addition, by including the thermoplastic elastomer in the first material layer 43, heat generated when the second material layer 44 is formed on the first material layer 43 causes a weld portion of the first material layer 43 to be formed. The generation of cracks and cracks can be suppressed. As a result, the pulling force of the first material layer 43 does not easily decrease, and the first material layer 43 is sufficiently fixed to the outer ring 21. In addition, the first material layer 43 and the second material layer 44 can be better heat-sealed. As a result, the second material layer 44 can be more firmly fixed to the first material layer 43, and the second material layer 44 can be more reliably prevented from falling off the outer race 21.

  Moreover, in the bearing 10 of the first embodiment, by providing the groove 28 on the outer peripheral surface 24 of the outer race 21, the groove 28 can be filled with the first material layer 43. By filling the groove portions 28 of the outer peripheral surface 24 with the protrusions 43a of the first material layer 43, the groove portions 28 of the outer peripheral surface 24 and the protrusions 43a of the first material layer 43 are engaged in an uneven manner. Can be. 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 unevenness of the outer peripheral surface 24 and the first material layer 43.

Here, the second material layer 44 is formed in a ring 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 thermally fused to the first material layer 43 by injection molding (for example, two-color molding).
Further, both side surfaces (the first side surface 48 and the 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, the second material layer 44 cools and contracts after the injection molding, so that the first side surface 48 and the second side surface 49 of the first material layer 43 are changed to the first side surface layer 53 of the second material layer 44. And the second side layer 54. Thereby, the second material layer 44 can be more firmly engaged with the first material layer 43.

Further, the inner peripheral surface 53 a of the first side surface layer 53 of the second material layer 44 is fixed to the first side portion 24 c of the outer peripheral surface 24 of the outer ring 21. The inner peripheral surface 54 a of the second side surface layer 54 of the second material layer 44 is fixed to the second side portion 24 d of the outer peripheral surface 24 of the outer ring 21. That is, a large height dimension H1 of the first side surface layer 53 and the second side surface layer 54 is ensured.
Therefore, a large contact area of the first side surface layer 53 with the first side surface 48 is ensured. A large contact area of the second side surface 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 area of the first side face 48 and the second side face 49 can be sandwiched between the first side face layer 53 and the second side face 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 a direction flipped from the outer peripheral surface 24 of the outer race 21 is applied to the second material layer 44, the second material layer 44 is less likely to be peeled off from the outer peripheral surface 24 of the outer race 21. it can.

  Thus, by interposing the first material layer 43 which is a material harder than the second material layer 44 between the outer peripheral surface 24 of the outer ring 21 and the second material layer 44, the second material The layer 44 can be more firmly engaged with the outer peripheral surface 24 of the outer race 21 via the first material layer 43. Thereby, the first material layer 43 and the second material layer 44 can be prevented from dropping from the outer peripheral surface 24 of the outer race 21.

Further, by firmly engaging the second material layer 44 with the outer peripheral surface 24 of the outer race 21 via the first material layer 43, a sand blasting process or an application process using an adhesive, which is conventionally required, is performed. Can be eliminated.
Further, when the first material layer 43 and the second material layer 44 are injection-molded by, for example, two-color molding, the amorphous thermoplastic resin and the thermoplastic elastomer contained in the first material layer 43 and the second It is not necessary to cure the thermoplastic elastomer contained in the second material layer 44 in a 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, a step of hardening in a mold for a long time like a urethane rubber can be omitted.
Thus, the bearing 10 in which the coating layer 18 (the first material layer 43 and the second material layer 44) is formed on the outer peripheral surface 24 of the outer ring 21 can be mass-produced at low cost.

As described above, the first material layer 43 and the second material layer 44 of the covering layer 18 are formed by, for example, 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 thermoplastic resin and a thermoplastic elastomer. 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 for injection molding the first material layer 43 and the second material layer 44. In particular, in 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 inside (cavity) of the mold from the gate G <b> 1 with the molten thermoplastic elastomer, the first material layer 43 and the first side portion 24 c and the second side portion 24 d of the outer peripheral surface 24 are added to the second side portion 24 d. The material layer 44 is insert molded.
By providing the mold gate G1 at a position corresponding to the first side surface layer 53, the filling location of the thermoplastic elastomer can be shifted from the coating outer peripheral surface 52c of the outer peripheral surface layer 52.

The parting line PL of the mold is positioned on the outer side surface 53b of the first side surface layer 53 in the direction of the axis O of the bearing 10, for example. The outer side surface 53b of the first side surface layer 53 is formed in a recess at one end 52d of the outer peripheral surface 52c with respect to the outer peripheral surface 52c of the outer peripheral surface layer 52. The parting line PL is arranged at a position shifted from the coating outer peripheral surface 52c of the outer peripheral surface layer 52.
As described above, by shifting the gate G1 and the parting line PL from the coating outer peripheral surface 52c of the outer peripheral surface layer 52, burrs generated when the thermoplastic elastomer is filled into the mold from the gate G1 and the parting line PL are reduced. It is possible to prevent burrs or the like from being generated on the coating outer peripheral surface 52c of the outer peripheral surface layer 52. This eliminates the need for post-processing for removing burrs from the coating 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 coating 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.

  By the way, the mold temperature at the time of injection molding an amorphous thermoplastic resin or a thermoplastic elastomer can be kept low at 150 ° C. or less (preferably 100 ° C. or less). Also, when the molten amorphous plastic or thermoplastic elastomer is filled into the mold from the gate G1, the amorphous plastic or thermoplastic elastomer is instantly solidified. Therefore, it is possible to prevent the heat of the molten amorphous plastic or thermoplastic elastomer from being transmitted to the grease sealed in the bearing 10. As a result, even at the high temperature of the molten amorphous plastic or thermoplastic elastomer, the grease is deteriorated even when a general-purpose grease (a soap-based thickening agent such as lithium soap) is used. There is no fear.

Here, by fixing the covering 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 covering 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, if the coating layer is adhered to the outer peripheral surface with an adhesive, the adhesive may not be applied to the outer peripheral surface to a uniform thickness 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 smaller than 1.0 mm. In this state, if the adhesive is not applied to the outer peripheral surface to have a uniform thickness, the hardness of the coating layer may be uneven.
For this reason, noise (noise) is generated and torque unevenness is caused when a conveyed object is conveyed by a small bearing covered with a coating layer or when the coating layer is rolled along a contact object. There is a possibility that.

On the other hand, by fixing the covering layer 18 (the first material layer 43 and the second material layer 44) to the outer peripheral surface 24, the adhesive can be made unnecessary. Thus, even when the bearing 10 is small and the thickness of the coating layer 18 is smaller than 1.0 mm, the hardness of the coating layer 18 can be kept uniform over the entire circumference.
Accordingly, even when the bearing 10 is formed in a small size, noise (noise) and uneven torque may be generated when the conveyed object is conveyed by the bearing 10 or when the bearing 10 is rolled along the contact object. Can be suppressed.

  In the first embodiment, an example will be described in which the coating layer 18 (the first material layer 43 and the second material layer 44) is provided only on the outer peripheral surface 24 by fixing. However, depending on the application of the bearing 10, for example, The coating layer 18 may be provided on the outer peripheral surface 24 by using an adhesive together to fix the coating layer 18 to the outer peripheral surface 24.

The method for forming the coating layer 18 is not limited to the above-described method (two-color molding). For example, the coating layer 18 may be formed as follows. First, the first material layer 43 is previously formed into a desired shape such as an annular shape. The first material layer 43 is attached to the outer peripheral surface 24 of the outer race 21 by being fitted thereto. After that, the second material layer 44 is insert-molded so as to cover the first outer peripheral surface 46, the first side surface 48, and the second side surface 49 of the first material layer 43.
Further, the coating layer 18 may be formed as follows. First, the first material layer 43 is previously formed into a desired shape such as an annular shape. The second material layer 44 is insert-molded so as to cover the first outer peripheral surface 46, the first side surface 48, and the second side surface 49 of the first material layer 43. The first material layer 43 on which the second material layer 44 is formed is attached to the outer peripheral surface 24 of the outer race 21 by being fitted thereto.

(Modification)
Next, a modified example of the bearing 10 of the first embodiment will be described.
FIG. 2 is a side view showing a modified example of the bearing according to the first embodiment.
As shown in FIG. 2, a plurality of gear teeth 57 can be formed on the outer peripheral surface of the coating of the second material layer 44. Thus, the bearing 10 can be used as the 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 gear 55 meshes.
The second material layer 44 forming the plurality of teeth 57 may be made of a thermoplastic elastomer having a durometer A of more than 95 in consideration of wear resistance, mechanical strength, and the like of the gear 55.

Next, an example of an application of the bearing 10 of the first embodiment will be described with reference to FIG. FIG. 3 is a side view showing the moving body 1 including the bearing 10 according to the first embodiment.
As shown in FIG. 3, for example, the bearing 10 is attached to the 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 the inner ring 22 being attached to the support shaft 41.
The support shaft 41 is attached to the main body 2. By fixing the inner race 22 to the support shaft 41, the outer race 21 and the coating layer 18 are rotatably supported by the support shaft 41. That is, the plurality of bearings 10 are used as wheels.

The moving body 1 is arranged in a state where the coating layers 18 (specifically, the second material layers 44) of the plurality of bearings 10 are in contact with the contact objects 5. The second material layer 44 is formed of a material containing a thermoplastic elastomer. The moving body 1 can be moved along the contact object 5 by the outer ring 21 of the bearing 10 and the coating layer 18 rolling on the contact object 5.
Since the coating layer 18 is formed on the outer ring 21, when the bearing 10 moves while rolling on the contact object 5, noise (noise) can be reduced by the coating layer 18 (particularly, the second material layer 44). it can. Further, 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.
As described above, by providing the moving body 1 with the plurality of bearings 10, the durability can be ensured and the low-cost moving body 1 can be obtained.

FIG. 3 illustrates an example in which the coating layer 18 of the bearing 10 is rotated while being in contact with the contact object 5 and the moving body 1 is moved along the contact object 5, but the present invention is not limited thereto. 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 rotating the covering layer 18. In this case, the case where the drawer is the contact object 5 in the drawer of the desk corresponds to this. Even in this state, sound (noise) can be reduced by the covering layer 18.
Further, as another example, the bearing 10 may be applied to a free wheel whose traveling direction turns. By applying the bearing 10 to a universal vehicle, the bearing 10 can be turned in accordance with the traveling direction of the moving body 1.

  Further, as an example of another application, the bearing 10 is used for a transport device (drive module) for bills and tickets. That is, in the transport device, the inner ring 22 of the pair of bearings 10 is attached to the support shaft 3, and the outer ring 21 and the coating layer 18 are rotatably supported by the support shaft. The pair of coating layers 18 are arranged adjacent to each other. In this state, as the outer ring 21 and the coating layer 18 rotate, bills, tickets, and the like are sandwiched between the pair of coating layers 18 and conveyed.

Since the coating layer 18 is formed on the outer ring 21, sound (noise) can be reduced by the coating layer 18 when a bill or a ticket is conveyed while being sandwiched between the coating layers 18 of the bearing 10. Further, 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.
As described above, by providing the transfer device with the bearing 10, it is possible to obtain a low-cost transfer device while ensuring durability.

  Next, the bearings of the second and third embodiments and the structure of the fourth embodiment will be described with reference to FIGS. In the bearings of the second embodiment and the third embodiment, the same or similar members as those of the bearing 10 of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[Second embodiment]
FIG. 4 is a cross-sectional view of the bearing 130 according to the second embodiment.
As shown in FIG. 4, a bearing 130 is the same as the bearing 10 of the first embodiment except that the coating layer 18 of the first embodiment is replaced with a coating layer 132.
The coating layer 132 is obtained by replacing the first material layer 43 of the first embodiment with the first material layer 113 and replacing the second material layer 44 with the second material layer 134.

  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 formed to be the same as the first outer peripheral surface 46 of the first material layer 43 and to have the same width as the outer peripheral surface 24 of the outer ring 21. The first inner peripheral surface 117 is formed similarly to 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 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 race 21 by cooling and contracting after the injection molding.

The second material layer 134 forms an outer peripheral layer of the coating layer 132. 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 24 a of the outer peripheral surface 24 of the outer ring 21. The second layer side surface 137 is formed flush with the second edge 24 b of the outer peripheral surface 24 of the outer race 21. That is, the second material layer 134 is formed to have the same width dimension W2 as the outer peripheral surface 24 of the outer race 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.

  According to the bearing 130 according to the second embodiment, similarly to the bearing 10 according to the first embodiment, since the first material layer 113 includes an amorphous thermoplastic resin, thermal fusion with the second material layer 134 is performed. The adhesion is enhanced, and the second material layer 134 is sufficiently fixed to the first material layer 113. In addition, by including the thermoplastic elastomer in the first material layer 113, the pulling force of the first material layer 113 is hardly reduced, and the first material layer 113 is sufficiently fixed to the outer ring 21. In addition, the second material layer 134 can be more firmly fixed to the first material layer 113, and the second material layer 134 can be more reliably prevented from falling off the outer race 21.

Moreover, the first material layer 113 is firmly fixed to the outer peripheral surface 24 of the outer ring 21 by cooling and contracting after the injection molding. Further, 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 race 21 via the first material layer 113.

[Third embodiment]
FIG. 5 is a cross-sectional view of the bearing 140 according to the third embodiment.
As shown in FIG. 5, a bearing 140 is obtained by replacing the ring 12 of the first embodiment with a ring 152, and replacing the coating layer 18 of the first embodiment with a coating layer 142. This is the same as the bearing 10 of the embodiment.
The ring body 152 is obtained by replacing the outer ring 21 of the first embodiment with an outer ring 154.
The coating layer 142 is obtained by replacing the first material layer 43 of the first embodiment with a first material layer 143 and replacing the second material layer 44 with a second material layer 144.

  The outer race 154 is the same as the outer race 21 of the first embodiment except that the outer race 154 does not have the groove 28 of the outer race 21 of the first embodiment.

  The first material layer 143 is formed on the outer peripheral surface 24 of the outer ring 154. The first material layer 143 is insert-molded on the outer peripheral surface 24 of the outer ring 154 by injection molding. The first material layer 143 has an outer peripheral surface layer 31 and a pair of side surface layers 31a and 31b. The outer peripheral surface layer 31 covers the outer peripheral surface 24 of the outer ring 154. The pair of side surface layers 31a and 31b are connected to both sides of the outer peripheral surface layer 31 in the direction of the axis O. The pair of side layers 31a and 31b cover the end surfaces 21a and 21b of the outer ring 154 over the entire circumference.

The material of the first material layer 143 is the same as the first material layer 43 of the first embodiment.
The first material layer 143 is formed in a ring shape along the outer peripheral surface 24 with a material containing an amorphous thermoplastic resin and a thermoplastic elastomer. Therefore, the first material layer 143 is firmly attached to the outer peripheral surface 24 due to shrinkage when the first material layer 143 is cooled and hardened.

  Here, the first material layer 143 is connected to both sides of the outer surface layer 31 of the first material layer 143 in the direction of the axis O in addition to the outer surface layer 31 covering the outer surface 24 of the outer ring 154, and It has a pair of side layers 31a and 31b that cover the end faces 21a and 21b. Thereby, the first material layer 143 is cooled and contracted, so that the end surfaces 21a and 21b of the outer ring 154 can be sandwiched and pinched by the pair of side surface layers 31a and 31b. Therefore, the outer ring 154 and the first material layer 143 are physically engaged, and the first material layer 143 is firmly fixed to the outer ring 154.

  When insert-molding the first material layer 143 on the outer peripheral surface 24 of the outer ring 154, the bearing 10 is housed inside the forming die, and the end surfaces 21a and 21b of the outer ring 154 are supported by contacting the forming die. In this way, the first material layer 143 is insert-molded on the outer peripheral surface 24 of the outer ring 154 by supporting the end surfaces 21a and 21b with the molding die. Further, the first material layer 143 may be insert-molded on the outer ring 154 alone.

The second material layer 144 is formed on the outer peripheral surface 34 (outer surface) of the first material layer 143. The second material layer 144 is an outer peripheral surface layer that forms the outer peripheral surface 35 of the coating layer 142.
The material of the second material layer 144 is the same as that of the second material layer 44 of the first embodiment.

  As described above, the bearing 140 of the third embodiment includes the coating layer 142 formed on the outer peripheral surface 24 of the outer ring 154 that is a metal member. The coating layer 142 is formed on the outer peripheral surface 24 of the outer ring 154 and includes a first material layer 143 containing an amorphous thermoplastic resin and a thermoplastic elastomer, and a thermoplastic resin on the outer peripheral surface 34 of the first material layer 143. A second material layer 144 as an outer peripheral surface layer that forms the outer peripheral surface 35 of the coating layer 142 by heat-sealing the elastomer. The second material layer 144 is a material that is softer than the first material layer 143. The first material layer 143 includes an outer peripheral surface layer 31 that covers the outer peripheral surface 24 of the outer ring 154, and an axis O of the outer peripheral layer 31. And a pair of side layers 31a, 31b connected to both sides in the direction to cover the end faces 21a, 21b of the outer race 154.

  According to the bearing 140 of the third embodiment, as in the case of the bearing 10 of the first embodiment, since the first material layer 143 contains an amorphous thermoplastic resin, the first material layer 143 is thermally fused with the second material layer 144. Thus, the second material layer 144 is sufficiently fixed to the first material layer 143. In addition, by including the thermoplastic elastomer in the first material layer 143, the pulling force of the first material layer 143 is hardly reduced, and the first material layer 143 is sufficiently fixed to the outer ring 154. In addition, the second material layer 144 can be more firmly fixed to the first material layer 143, and the second material layer 144 can be more reliably prevented from falling off the outer ring 154.

In addition, in the bearing 140 of the third embodiment, the second material layer 144 as the outer peripheral surface layer can be firmly fixed by the thermal fusion by forming the outer peripheral surface 35 by thermal fusion of the thermoplastic elastomer. Therefore, the sandblasting process and the application process using an adhesive, which have been conventionally required, can be eliminated. Thereby, the bearing 140 provided with the coating layer 142 made of the thermoplastic elastomer can be mass-produced at low cost.
Further, when the second material layer 144 is made of a material softer than the first material layer 143, a hard material can be used for the first material layer 143.
Further, since the first material layer 143 is formed on the outer peripheral surface 24 of the outer ring 154, the first material layer 143 is formed in an annular shape. Therefore, the first material layer 143 is firmly attached to the outer peripheral surface 24 of the outer race 154 due to shrinkage when the first material layer 143 is cooled and hardened.
In addition, by using the second material layer 144 as a material softer than the first material layer 143, the outer ring of the bearing 140 can be used to convey goods such as bills or tickets, or the bearing 140 can be used as a wheel of a moving body. When rolling along the contact object, the second material layer 144 can reduce sound (noise).

  Further, the first material layer 143 includes an outer peripheral surface layer 31 that covers the outer peripheral surface 24 of the outer ring 154 and a pair of side surfaces that are connected to both sides of the outer peripheral layer 31 in the direction of the axis O to cover the end surfaces 21a and 21b of the outer ring 154. Layers 31a and 31b. Since the pair of side layers 31a and 31b of the first material layer 143 cover the entire periphery of the end faces 21a and 21b of the outer ring 154, the first material layer 143 cools and contracts, thereby forming the outer ring 154. The end faces 21a, 21b can be sandwiched and pinched by the pair of side layers 31a, 31b over the entire circumference. Therefore, in the bearing 140 of the third embodiment, the first material layer 143 can be more firmly fixed to the outer ring 154, and the first material layer 143 can be prevented from falling off the outer ring 154.

[Fourth embodiment]
FIG. 6 is a cross-sectional view of a structure 160 according to the fourth embodiment.
As shown in FIG. 6, the structure 160 has a coating layer 164 formed on the outer surface 163 of the flat member 162. The flat member 162 is a metal member made of a metal material such as stainless steel.
The coating layer 164 includes a first material layer 165 formed on the outer surface 163 of the flat member 162, and a second material layer 166 formed on the outer surface 165a of the first material layer 165.

The flat member 162 has a protrusion 171 on the outer surface 163, for example. The protrusion 171 has a leg 172 protruding in a direction crossing the outer surface 163 and an extension 173 formed at a tip 172a of the leg 172. The protrusion 171 is formed in a T shape by the leg 172 and the extension 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 a first material layer 165 formed on the outer surface 163 of the flat member 162. The first material layer 165 is the same material as the first material layer 43 (see FIG. 1) of the first embodiment, and is specifically formed of a material containing an amorphous thermoplastic resin and a thermoplastic elastomer. ing. 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.

A second material layer 166 is formed on an outer surface 165a of the first material layer 165. The second material layer 166 forms the outer peripheral surface layer of the coating layer 164. The second material layer 166 is the same material as the second material layer 44 (see FIG. 1) of the first embodiment, and is specifically formed of a material containing a thermoplastic elastomer.
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. Therefore, the second material layer 166 cools and contracts, so that the first side surface 165b and the second side surface 165c of the first material layer 165 are changed to the second material layer 166 (the first side surface layer 176, the second side surface 176). Layer 177). Thereby, the second material layer 166 can be firmly engaged with the first material layer 165.

  According to the structure 160 of the fourth embodiment, similarly to the bearing 10 of the first embodiment, since the first material layer 165 contains an amorphous thermoplastic resin, thermal fusion with the second material layer 166 is possible. The adhesion is enhanced, and the second material layer 166 is sufficiently fixed to the first material layer 165. In addition, when the first material layer 165 contains a thermoplastic elastomer, the pulling force of the first material layer 165 is hardly reduced, and the first material layer 165 is sufficiently fixed to the flat member 162. In addition, the second material layer 166 can be more firmly fixed to the first material layer 165, and the second material layer 166 can be more reliably prevented from falling off the flat member 162.

Moreover, according to the structure 160 of the fourth embodiment, similarly to the bearing 10 of the first embodiment, the first material layer 165 and the second material layer 166 are firmly engaged with the outer surface 163 of the flat member 162. Can be done. This can prevent the coating layer 164 from falling off the outer surface 163 of the flat member 162.
According to the structure 160 of the fourth embodiment, similarly to the bearing 10 of the first embodiment, the structure 160 in which the coating layer 164 is formed on the outer surface 163 of the flat member 162 is manufactured in large quantities at low cost. can do.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
Various measurement and evaluation methods in Examples and Comparative Examples and materials used are as follows.

[Measurement / evaluation method]
<Measurement of MFR value>
According to JIS K 7210, the MFR value was measured under the conditions of a measurement temperature of 280 ° C. and a measurement load of 2.16 kg.

<Measurement of glass transition temperature, melting point and heat of fusion>
Using a differential scanning calorimeter (DSC), the measurement sample was heated to a temperature equal to or higher than the expected melting point at a heating rate of 10 ° C./min. Next, the measurement sample was cooled to 0 ° C. at a temperature lowering rate of 10 ° C./min, and left as it was for 1 minute. Thereafter, the melting peak when heating and raising the temperature again at a temperature raising rate of 10 ° C./min was measured and defined as the melting point. The heat of fusion and the glass transition temperature were measured simultaneously with the melting peak.

<Measurement of tensile strength and elongation at break>
Tensile strength and elongation at break were measured according to ISO 527-4.

<Measurement of molding shrinkage>
A dumbbell-shaped test piece used for a tensile property test described in JIS K 7161-2 was produced using a mold. The size (full length) of the test piece in the flow direction was measured using a micrometer. Similarly, the dimensions (full length) of the mold were measured, and the molding shrinkage in the flow direction was obtained from the following equation.
Molding shrinkage = {(mold size-test piece size) / mold size} x 100

<Measurement of pulling force>
A universal testing machine 200 shown in FIG. 7 was prepared. The universal testing machine 200 includes a hollow punching jig 210 and a pedestal 220.
As shown in FIG. 7A, the bearing 130 is set between the punching jig 210 and the pedestal 220, and the punching jig 210 is pushed in the axial direction of the bearing 130, and the first material layer 113 and the second The maximum load at the time when the fused surface with the material layer 134 was peeled off was determined, and this was defined as the pulling force of the second material layer 134.
Next, as shown in FIG. 7B, the bearing 131 from which the second material layer has been peeled is set between the punching jig 210 and the pedestal 220, and the punching jig 210 is pushed in the axial direction of the bearing 131. Then, the maximum load at the time when the fused surface between the outer ring and the first material layer 113 was peeled off was obtained, and this was defined as the pulling force of the first material layer 113.
The measurement was performed on the three bearings 130, and the average value and the standard deviation of the pulling forces of the first material layer 113 and the second material layer 134 were obtained.
In FIG. 7, only the first material layer 113 and the second material layer 134 among the components of the bearing 130 are illustrated, and the components other than the first material layer 113 and the second material layer 134 are Omitted.

<Appearance evaluation>
The appearance of the first material layer was visually observed to check for cracks.

<Measurement of flexural strength and flexural modulus>
The flexural strength and flexural modulus were measured according to JIS K7171.

<Measurement of Izod notch>
The Izod impact strength of a test piece (1/8 inch, with a notch) was measured according to ASTM D256.

<Measurement of durometer A>
The durometer A was measured using a type A durometer based on JIS K6253.

<Measurement of wear amount>
A test piece was placed on a moving table, and a glass plate was used as a contact partner, and a wear amount of the test piece was measured when a reciprocating sliding test was performed at a load of 0.7 kg and a speed of 0.16 m / s for 20 minutes. .

[material]
<Amorphous thermoplastic resin>
As the amorphous thermoplastic resin, an aromatic polycarbonate resin (MFR value: 44 g / 10 min, glass transition temperature: 147 ° C.) or an ABS resin (MFR value: 127 g / 10 min, glass transition temperature: 102 ° C.) was used.

<Thermoplastic elastomer>
As the thermoplastic elastomer, a polyester-based thermoplastic elastomer (MFR value: 44 g / 10 min, melting point: 142 ° C., durometer A: 58) was used.

<Inorganic fiber>
As the inorganic fibers, potassium titanate fibers (potassium hexatitanate, average fiber length: 15 μm, average fiber diameter: 0.5 μm) were used.

<Other additives>
As another additive, a silicone resin was used.

[Examples 1 to 5, Comparative Examples 1 to 3]
Based on the composition shown in Table 1, the first material layer and the second material layer of the coating layer were formed by two-color molding, and the bearing 130 shown in FIG. 4 was manufactured. Specifically, after the first material layer 113 is insert-molded on the outer peripheral surface 24 of the outer race 21 by injection molding at the molding temperature shown in Table 1, the second material layer 134 is insert-molded by injection molding. Thus, a bearing 130 was obtained.
A test piece was prepared with the same composition as the first material layer 113, and the tensile strength, elongation at break, flexural modulus, and molding shrinkage were measured. Similarly, a test piece having the same composition as the second material layer 134 was prepared, and the tensile strength, the elongation at break, the durometer A and the flexural modulus were measured. The molding temperature when producing each test piece was the molding temperature shown in Table 1. Table 1 shows the results.
Further, the pulling force of the first material layer 113 and the second material layer 134 was measured. Further, the appearance of the first material layer 113 was evaluated. Table 1 shows the results.
The mass ratio between the amorphous thermoplastic resin and the thermoplastic elastomer in the first material layer (amorphous thermoplastic resin: thermoplastic elastomer) was 97.1: 2.9 in Example 1, and In Example 2, it is 93.9: 6.1, in Example 3, it is 87.9: 12.1, in Example 4, it is 82.9: 17.1, and in Example 5, it is 97.1: 2. 0.9 and 100: 0 in Comparative Examples 1 to 3.
“PC” in Table 1 is an abbreviation for aromatic polycarbonate resin, and “ABS” is an abbreviation for ABS resin.

[Reference Example 6]
A test piece was prepared based on the composition of the first material layer shown in Table 1, and the molding shrinkage was measured. The molding temperature at the time of producing the test piece was 240 ° C. Table 1 shows the results.
The mass ratio between the amorphous thermoplastic resin and the thermoplastic elastomer in the first material layer (amorphous thermoplastic resin: thermoplastic elastomer) was 78.6: 21.4.

As is clear from Table 1, in the bearings obtained in Examples 1 to 5, the pulling force of the first material layer and the second material layer was large, and the coating layer was sufficiently fixed to the outer ring. In addition, in the case of Examples 1 to 5, the standard deviation of the pulling force of the first material layer was small, and the dispersion of the pulling force was small, indicating that the reliability was high. This is considered as follows.
That is, when measuring the pulling force of the first material layer, the weld portion is completely cracked in the radial direction (the space created by the crack) is expanded in the circumferential direction. One material layer comes off and comes off. The maximum force applied to the first material layer during this operation is measured as a pulling force. In particular, the first material layers of Comparative Examples 1 and 2 have cracks in the weld portion from the beginning, and this The size (depth) of cracks also varies among samples.
Therefore, in the case of Comparative Examples 1 and 2, only a small pulling force is obtained, and it is considered that a large variation occurs in the value of the pulling force. On the other hand, in the case of Examples 1 to 5, since no crack is generated in the weld portion, a large pulling force is obtained and the variation is small.

In addition, in the bearings obtained in Examples 1 to 5, no crack was recognized in the weld portion of the first material layer, though the molding temperature was higher than Comparative Examples 1 and 2. However, in the case of Examples 1 and 2, a slight weld line appeared.
Further, in Examples 1 to 5, the molding shrinkage of the first material layer was 0.44% or less. The molding shrinkage in the case of using 55% by mass of the aromatic polycarbonate resin, 15% by mass of the polyester-based thermoplastic elastomer, and 30% by mass of the potassium titanate fiber (Reference Example 6) was 0.48%. Was. From these results, it was shown that as the content of the thermoplastic elastomer decreases, the shrinkage ratio during molding hardly increases, and precise molding is facilitated.

On the other hand, in the bearings obtained in Comparative Examples 1 and 2, the pulling force of the first material layer and the second material layer was small, and particularly, the pulling force of the first material layer was large. In addition, cracks were observed in the weld portion of the first material layer.
The bearing obtained in Comparative Example 3 had a smaller pulling force of the first material layer than Examples 1 to 5.

[Experimental Examples 1-4]
Hereinafter, experimental examples will be described.
In Experimental Examples 1 to 4, in order to confirm that the effect of reducing and suppressing the abrasion loss of the first material layer and the second material layer can be obtained by blending the inorganic fiber with the thermoplastic elastomer, a polyester-based thermoplastic resin was used. The physical properties (tensile strength, flexural strength, flexural modulus, Izod notch and durometer A) and wear of the polyester-based thermoplastic elastomer were measured when the amount of potassium titanate fiber added to the elastomer was changed. . The results are shown in Table 2 and FIG.
In Table 2 and FIG. 8, the polyester-based thermoplastic elastomer containing no potassium titanate fiber is shown as “elastomer (single)”. Further, a polyester-based thermoplastic elastomer containing 10% by mass of potassium titanate fiber is referred to as “elastomer (10% by weight)”. A polyester-based thermoplastic elastomer containing 20% by mass of potassium titanate fiber is shown as “elastomer (20 wt%)”. A polyester-based thermoplastic elastomer containing 30% by mass of potassium titanate fiber is referred to as “elastomer (30 wt%)”.

As is clear from Table 2 and FIG. 8, the polyester thermoplastic elastomer contains potassium titanate fiber in an amount of 10% by mass, 20% by mass, and 30% by mass, so that the tensile strength is from 12 MPa to 13 MPa, 18 MPa, and 23 MPa. It was high. Further, the bending strength was increased from 4 MPa to 7 MPa, 9 MPa, and 16 MPa. Further, the flexural modulus was increased from 0.05 GPa to 0.13 GPa, 0.21 GPa, and 0.44 GPa.
Further, in a state where the polyester-based thermoplastic elastomer contains potassium titanate fiber at 10% by mass, 20% by mass, and 30% by mass, the durometer A of the polyester-based thermoplastic elastomer is substantially the same as 94 to 96, 97, 98. Was secured.
Further, in a state where the polyester-based thermoplastic elastomer contains potassium titanate fiber at 10% by mass, 20% by mass, and 30% by mass, the abrasion loss of the polyester-based thermoplastic elastomer is from 12.5 × 10 ⁻³ cm ³ to 10%. 0.1 × 10 ⁻³ cm ³ , 7.0 × 10 ⁻³ cm ³ , and 3.8 × 10 ⁻³ cm ³ .

10,130,140 Bearing (structure)
18, 132, 142, 164 Coating layer 21, 154 Outer ring (metal member)
43, 113, 143, 165 First material layer 44, 134, 144, 166 Second material layer 160 Structure 162 Flat member (metal member)

Claims (6)

A metal member, a structure comprising a coating layer formed on the metal member,
The coating layer includes a first material layer formed on the metal member, and a second material layer formed on the first material layer,
The first material layer includes an amorphous thermoplastic resin and a thermoplastic elastomer,
The second material layer includes a thermoplastic elastomer,
The structure, wherein the second material layer is a softer material than the first material layer.   The structure according to claim 1, wherein the first material layer further includes an inorganic fiber. When the melting point of the thermoplastic elastomer contained in the second material layer is Tm and the glass transition temperature of the amorphous thermoplastic resin contained in the first material layer is Tg, the following formula (1) is satisfied. The structure according to claim 1.
Tm ≧ Tg-5 (1)   The structure according to any one of claims 1 to 3, wherein the thermoplastic elastomer contained in the first material layer and the thermoplastic elastomer contained in the second material layer are of the same type.   The structure according to any one of claims 1 to 4, wherein the amorphous thermoplastic resin is a polycarbonate resin.   The content of the thermoplastic elastomer contained in the first material layer is 1 to 14% by mass based on the total mass of the first material layer, according to any one of claims 1 to 5. Structure.

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