Environmentally friendly machine component

Abstract

To use a PA4T, an environmentally friendly biomass plastic, which is made from a semi-aromatic polyamide derived from plant-derived tall oil, for components of industrial machinery such as a synthetic resin holder for a rolling bearing, a resin pulley, and a linear motion device.SOLUTION: The present invention is an environmentally friendly machine component used as a component of industrial machinery, the machine component made of a polyamide resin composition in which a reinforcing material is contained in polyamide 4T produced from a biomass-derived raw material. The industrial machinery is a rolling bearing consisting of an inner ring 2, an outer ring 3, a holder 4, and rolling bodies 5. The holder 4, a component of the rolling bearing, is an environmentally friendly mechanical component, where the content of the reinforcing material is 0 to 40 wt.%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This relates to environmentally friendly machine parts for industrial machinery that can be used in a variety of environments. [Background technology]

[0002] Rolling bearings for industrial machinery, belt guide pulleys, and parts used in linear motion devices are used in environments where they are subject to a variety of influences. For example, in the synthetic resin cages that make up rolling bearings, polyamide 4T (hereinafter simply referred to as PA4T), a polyamide resin with a high elastic modulus, is used to prevent deformation of the cage due to centrifugal force generated during rotation, which can cause damage to the bearing (see Patent Document 1).

[0003] Furthermore, in resin pulleys, which are formed by integrally molding resin onto the outer periphery of rolling bearings, which are pulleys used to guide belts that drive automotive accessories, mechanical properties that correspond to the belt tension, the shape precision of the guide part that guides the belt, heat resistance when used under continuous load, excellent resistance to calcium chloride to prevent deterioration due to the scattering of snow-melting agents and the like while the automobile is running, and low water absorption and little dimensional change to maintain adhesion to the bearing are required, so a resin composition is used in which glass fiber is blended into PA4T, which is a base resin made of a diamine component whose main component is 1,4-butanediamine (see Patent Document 2).

[0004] Furthermore, in linear motion devices aimed at reducing noise, separators with arc-shaped recesses in which the balls are housed are installed between the balls to eliminate the sound of balls colliding with each other during operation. Materials used for these separators include unreinforced 66 nylon and polyester-based thermoplastic elastomers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-175032 [Patent Document 2] Japanese Patent Application Publication No. 2020-056419 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the PA4T used in the synthetic resin cages and resin pulleys of these rolling bearings is entirely derived from petroleum, including its main raw material, 1,4-butanediamine, and is not environmentally friendly. Furthermore, while there was a demand for high-speed linear motion devices to improve productivity, the separator, which is made of nylon 66 resin, has a low melting point. When the linear motion device operates at high speed and the internal temperature rises, the separator softens and may deform.

[0007] The present invention has been made in light of these circumstances, and aims to change the main raw material, 1,4-butanediamine, in the synthetic resin cages and resin pulleys of rolling bearings for industrial machinery to PA4T, an environmentally friendly biomass plastic made from a semi-aromatic polyamide derived from plant-derived tall oil, and to use separators in linear motion devices for industrial machinery that are highly reliable, environmentally friendly, and environmentally friendly machine parts that achieve the high-speed deformation prevention required of separators. [Means for solving the problem]

[0008] The first invention is an environmentally friendly mechanical part used as a component of industrial machinery, characterized in that it is formed from a polyamide resin composition containing polyamide 4T produced from biomass-derived raw materials and a reinforcing material. A second invention is the industrial machine according to the first invention, wherein the industrial machine is a rolling bearing comprising at least an inner ring, an outer ring, rolling elements, and a cage, The cage, which is a component of the rolling bearing, is an environmentally friendly machine part, and is characterized in that it contains 0 to 40% by weight of the reinforcing material. A third invention is the industrial machine according to the first invention, wherein the industrial machine is a rolling bearing comprising an inner ring, an outer ring, and rolling elements, The pulley, which is made up of a resin part integrally attached to the outer peripheral surface of the outer ring of the rolling bearing, is an environmentally friendly machine part, characterized in that it contains 20 to 55 wt % of the reinforcing material. A fourth invention is the industrial machine according to the first invention, wherein: A linear motion device comprising: a linear motion body fitted onto a shaft and moving linearly along the shaft; a number of balls held by a ball groove formed on the outer surface of the shaft and a ball groove formed on the inner surface of the linear motion body, the balls rolling between the linear motion body and the shaft; and a circulation passage formed on the linear motion body for circulating the balls from one end side to the other end side of the ball groove, The circulation passage of the linear motion device is an environmentally friendly machine part, and is characterized in that the reinforcing material is contained in an amount of 10 to 40% by weight. A fifth aspect of the present invention is the industrial machine according to the first aspect of the present invention, A linear motion device comprising: a linear motion body fitted onto a shaft and moving linearly along the shaft; a number of balls held by a ball groove formed on the outer surface of the shaft and a ball groove formed on the inner surface of the linear motion body, and rolling between the linear motion body and the shaft; separators interposed between the balls; and a circulation passage formed in the linear motion body for circulating the balls from one end side to the other end side of the ball groove, At least one of the separator and the circulation passage of the linear motion device is an environmentally friendly mechanical component, and is characterized in that the reinforcing material is contained in an amount of 10 to 40% by weight. [Effects of the Invention]

[0009] Because the environmentally friendly PA4T of the present invention is a biomass plastic, it can be used to make bearing devices more environmentally friendly than conventional PA4T made only from petroleum-derived components and having a bio-content of 0%. This biomass PA4T has the same chemical composition as conventional PA4T made only from petroleum-derived components, so there is no difference in its mechanical properties, heat resistance, and other characteristics.

[0010] Furthermore, by using PA4T made from 1,4-butanediamine derived from plant-derived tall oil as the resin material for the resin part of a resin pulley consisting of a resin part formed integrally with a rolling bearing around the bearing, an environmentally friendly pulley can be provided. The biomass PA4T of the present invention has the same chemical composition as conventional PA4T produced only from petroleum-derived components, and therefore has excellent mechanical properties, heat resistance, calcium chloride resistance, and dimensional stability.

[0011] Furthermore, by using PA4T, a semi-aromatic polyamide with excellent heat resistance, as the resin material for the circulation passages of a linear motion device or the separator cage, a linear motion device can be provided that is both highly reliable and low-cost, making it suitable for use in a variety of environments. In this way, by using PA4T as the resin material for the resin parts of a resin pulley, an environmentally friendly linear motion device can be achieved. Furthermore, PA4T, a semi-aromatic polyamide with excellent heat resistance, can also be used for the circulation passages formed in the linear motion body that circulate balls from one end of the ball groove to the other. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1( a ) is a schematic perspective view showing, with a portion cut away, a rolling bearing that is one embodiment using an environmentally friendly mechanical component of the present invention, and FIG. 1( b ) is a schematic perspective view showing one embodiment of a cage that is an environmentally friendly mechanical component. [Figure 2] 1A is a front view showing one embodiment of a resin pulley for a belt tensioner according to the present invention, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. [Figure 3] (a) is a partially cutaway perspective view showing a ball screw device, which is another example of a linear motion device, (b) is a longitudinal sectional view of the ball screw device, (c) is a plan view showing the inside of a ball circulation path of the linear motion device, and (d) is a sectional view showing separators interposed between balls in the ball circulation path of the linear motion device. DETAILED DESCRIPTION OF THE INVENTION

[0013] The embodiments for carrying out the invention will explain three embodiments in which environmentally friendly machine parts formed from a polyamide resin composition containing a reinforcing material in polyamide 4T produced from biomass-derived raw materials are used as components of industrial machinery. In the first embodiment, the industrial machine is a rolling bearing comprising at least an inner ring, an outer ring, rolling elements, and a cage, and the cage, which is a component of the rolling bearing, is an environmentally friendly machine part. In the second embodiment, the industrial machine is a rolling bearing, and the environmentally friendly machine part is a resin pulley made of a resin part formed integrally with the rolling bearing around the rolling bearing. The third embodiment is a linear motion device having an industrial machine, a linear motion body fitted onto a shaft and moving linearly along the shaft, a number of balls held by ball grooves formed on the outer surface of the shaft and ball grooves formed on the inner surface of the linear motion body and rolling between the linear motion body and the shaft, and a circulation passage formed in the linear motion body for circulating the balls from one end to the other end of the ball groove, or a linear motion device further having separators interposed between each ball, wherein at least one of the circulation passage of the linear motion device or the separator and the circulation passage is an environmentally friendly mechanical part. Each embodiment will be described below in order. Note that these embodiments are merely one embodiment of the present invention and should not be construed as being limiting in any way, and appropriate design modifications can be made within the scope of the present invention.

[0014] [First embodiment of environmentally friendly mechanical component] As a first embodiment of the environmentally friendly mechanical component, this type of rolling bearing is a rolling bearing for industrial machinery that uses the environmentally friendly mechanical component. As shown in FIG. 1(a), for example, the rolling bearing is assumed to be a deep groove ball bearing 1, and is composed of an inner ring 2 having a rolling surface 2a on its circumferential surface, an outer ring 3 having a rolling surface 3a on its inner circumferential surface, a plurality of rolling elements (balls) 4 interposed between the two rolling surfaces 2a, 3a, a synthetic resin cage 5 that holds the plurality of rolling elements 4, a sealing member 9 that is disposed between the inner ring 2 and the outer ring 3 and seals the interior space of the bearing, and a lubricant (not shown) that is sealed in the interior space of the bearing, and the cage 5 is a rolling element guide.

[0015] 1(b), in this embodiment, a synthetic resin crown-type cage is used as the cage 5. This crown-type cage 5 has a main portion 6 formed in the shape of a short cylinder, and a pair of claw portions 7, 7 protruding from one side of the main portion 6 in the axial direction of the cylinder, with a plurality of pairs of claw portions 7, 7 provided at predetermined intervals around the circumferential direction of the main portion 6, and pockets 8 that rotatably hold the rolling elements 4 are formed between each pair of claw portions 7, 7. The crown type cage of this embodiment is one embodiment, and other general crown type cages can be adopted within the scope of the present invention. Also, although this embodiment will be described using a crown type cage, the cage is not limited to this, and other types of cages made of synthetic resin can be designed and modified within the scope of the present invention.

[0016] The environmentally friendly mechanical component used in the synthetic resin cage of the rolling bearing of the present invention is formed from a polyamide resin composition containing polyamide 4T produced from biomass-derived raw materials and a reinforcing material. That is, a synthetic resin cage using an environmentally friendly mechanical component formed from a polyamide resin composition consisting of PA4T and a reinforcing fiber material (content 0 to 40 wt%) uses the environmentally friendly biomass plastic PA4T, making it possible to produce a rolling bearing that is more environmentally friendly than conventional PA4T made only from petroleum-derived components and having a bio-content of 0%. Furthermore, because this biomass PA4T has the same chemical composition as conventional PA4T produced only from petroleum-derived components, there is no difference in its mechanical properties, heat resistance, etc.

[0017] The base resin used to form the cage can be PA4T, a polycondensate of petroleum-derived terephthalic acid and 1,4-butanediamine derived from plant-derived tall oil. Because PA4T is a polycondensate of terephthalic acid and 1,4-butanediamine in a 1:1 molar ratio, the bio-content (bio ratio) can be increased to approximately 40%.

[0018] The molecular weight of the polyamide resin should be within a range that allows injection molding when containing a reinforcing material such as glass fiber, specifically, a number-average molecular weight of 13,000 to 28,000, and more preferably, considering fatigue resistance and moldability, a number-average molecular weight of 18,000 to 26,000. If the number-average molecular weight is less than 13,000, the molecular weight is too low, resulting in poor fatigue resistance and low practicality. On the other hand, if the number-average molecular weight exceeds 28,000, the melt viscosity becomes too high when a practical content of a reinforcing material such as glass fiber is added in a range of 15 to 35 wt %, making it difficult to precisely manufacture a cage by injection molding, which is not preferable.

[0019] The base resin alone exhibits a certain level of durability, and works advantageously against wear on the mating components (rolling elements and outer rings) with which the cage may come into contact, allowing it to function satisfactorily as a cage. Because cages for wheel rolling bearings are significantly deformed during manufacturing before being incorporated into the bearing, and because the temperature environment of the wheel is subject to severe changes, the materials used must be flexible, so unreinforced materials that do not contain reinforcing materials are usually used.

[0020] However, if the cage is used under more severe conditions, it is expected that the cage may be damaged, deformed, or worn, so it is preferable to compound a reinforcing material to further improve reliability.

[0021] Preferred reinforcing materials include glass fiber, carbon fiber, aramid fiber, potassium titanate whisker, aluminum borate whisker, etc., and those surface-treated with a silane coupling agent or the like are more preferred in consideration of adhesion to the above-mentioned polyamide resins. Furthermore, a combination of multiple types of these reinforcing materials can be used. Considering impact strength, it is preferable to blend fibrous materials such as glass fiber or carbon fiber, and considering damage to the mating material, it is preferable to blend whisker-like materials in combination with fibrous materials. When mixed, the mixing ratio varies depending on the type of fibrous material and whisker-like material, and is selected appropriately in consideration of impact strength, damage to the mating material, etc.

[0022] As the glass fiber, in addition to those with a general average fiber diameter of 10 to 13 μm, those with an average fiber diameter of 5 to 7 μm or those with an irregular cross section are more suitable, as they can achieve high strength and improved wear resistance with a small content.

[0023] Furthermore, if strength is a priority, PAN-based carbon fibers are suitable, but pitch-based fibers are also usable because of their cost advantage. The average fiber diameter is preferably 5 to 15 μm. Carbon fibers have high strength and elastic modulus, making it possible to achieve higher strength and elastic modulus in the cage compared to glass fibers.

[0024] As the aramid fiber, it is possible to suitably use para-aramid fiber, which has excellent reinforcing properties. The average fiber diameter is preferably 5 to 15 μm. Unlike glass fiber and carbon fiber, aramid fiber does not damage steel materials and does not deteriorate the surface condition of the mating member with which the cage comes into contact, making it even more suitable when emphasis is placed on the acoustic characteristics of the bearing.

[0025] These reinforcing materials are preferably blended in a proportion of 10 to 40% by weight, particularly 15 to 30% by weight, based on the total weight. If the blending amount of the reinforcing material is less than 10% by weight, the improvement in mechanical strength is small, which is not preferred. If the blending amount of the reinforcing material exceeds 40% by weight, the moldability decreases and, depending on the type of reinforcing material, the likelihood of damaging the mating material increases, which is not preferred.

[0026] Furthermore, it is preferable to add an iodide-based heat stabilizer or an amine-based antioxidant, either alone or in combination, to the resin as an additive to prevent deterioration due to heat during molding and use.

[0027] The following explains grease, which keeps rolling bearings well lubricated. The inflow of grease ensures smooth rolling of the balls. The grease used in the present invention is mainly composed of a thickener and a base oil, and the base oil is mainly composed of poly-α-olefin oil in consideration of wettability with the PA4T used in the present invention, and the thickener is a urea compound consisting of amine and isocyanate, Li soap, Li complex soap, Ba soap, Ba complex soap, etc.

[0028] Among these thickeners, urea compounds having urea bonds similar in structure to polyamides are particularly preferred because of their excellent adsorption to polyamide resins. The base oil may be a mixture of diester oil or aromatic ester oil to improve the lubricity of the poly-α-olefin oil. The amount of such oil mixed is 30% by weight or less of the total base oil.

[0029] Other additives can also be added to this grease, such as amine or phenolic antioxidants, rust inhibitors such as Ca sulfonate, extreme pressure additives such as MoDTC, Montan acid ester wax, partially saponified Montan acid ester wax, polyethylene wax, and oiliness improvers such as oleic acid.

[0030] Furthermore, if the seal is also made of the same resin material or biomass rubber as that used for the cage, the rolling bearing will be even more environmentally friendly, which is preferable.

[0031] As explained above, the environmentally friendly mechanical part PA4T is a biomass plastic, making it possible to create a bearing device that is more environmentally friendly than conventional PA4T, which is made only from petroleum-derived components and has a bio-content of 0%.

[0032] [Cage material properties] The following describes further the properties of the cage material by way of examples of embodiments and comparative examples, but the present invention is not limited thereto. As shown in the cage material properties in Table 1, the cage of the rolling bearing (first embodiment shown in FIG. 1) can be injection molded by blending a reinforcing material (glass fiber GF) into a base resin.

[0033] [Table 1]

[0034] In Example 1 of the embodiment, Envalior's ForTii Eco E11 was used as the resin composition, and in Example 1 of the comparative embodiment, Envalior's ForTii Ace MX51 was used as the resin composition.

[0035] As a result, Example 1 of the embodiment uses biomass raw materials and is therefore more environmentally friendly than Comparative Example 1, which is made solely of petroleum-derived components. Furthermore, as shown in Table 1, Example 1 of the embodiment has approximately the same tensile modulus (rigidity) as Comparative Example 1, and therefore can be used without breakage even under the high-speed rotation conditions that have traditionally been used with PA4T.

[0036] [Second embodiment of environmentally friendly mechanical component] The following second embodiment relates to a pulley that is an environmentally friendly mechanical part, and more specifically, is used as a tensioner for drive belts for auxiliary equipment mounted on automobiles, or for other belts, or as an idler pulley.

[0037] 2(a) and 2(b) is composed of a rolling bearing 10 having an inner ring 10a, an outer ring 10b, and rolling elements 10c disposed for free roll between the inner ring 10a and the outer ring 10b, and a resin part 11 formed integrally with the rolling bearing 10 around the rolling bearing 10. The resin part 11 has an inner cylindrical part 12 fixed to the outer ring of the rolling bearing 10, an outer cylindrical part 14 having a belt guide surface 13, and a disk part 15 formed between the outer cylindrical part 14 and the inner cylindrical part 12, and furthermore a number of ribs 16 formed radially on the disk part 15. In addition, a number of gates 17 are formed in the inner cylindrical part 12 at equal intervals at a predetermined circle, and molten resin is poured into these gates 17 to manufacture a resin pulley by injection molding. As shown in FIG. 2(b), the rolling bearing 10 is a deep groove ball bearing with a contact rubber seal 19 having a recessed groove 18 on the outer periphery of the outer ring to prevent the resin part 10 from coming off.

[0038] The PA4T used in conventional resin pulleys is made entirely from petroleum-derived main raw materials, and is not environmentally friendly. In light of this situation, the present invention uses a resin pulley made from PA4T, a biomass plastic, as an environmentally friendly machine part, instead of plant-derived tall oil, which is made from 1,4-butanediamine, the main raw material of PA4T.

[0039] As a result, environmentally friendly resin pulleys can be provided by using PA4T, which is made from 1,4-butanediamine derived from plant-derived tall oil, as the resin material for the resin part of a resin pulley.This biomass PA4T has the same chemical composition as conventional PA4T made only from petroleum-derived components, and therefore has excellent mechanical properties, heat resistance, calcium chloride resistance, and dimensional stability.

[0040] The resin pulley consists of a rolling bearing and a resin part formed integrally with the rolling bearing around the bearing. The base resin of the resin part is made of PA4T (melting point 300-340°C), a semi-aromatic polyamide made from biomass materials. By making the base resin highly heat-resistant and low water-absorbent, the heat resistance and calcium chloride resistance required of a resin pulley can be fully satisfied. In addition, by using 1,4-butanediamine derived from plant-derived tall oil as one of the raw materials, the bio-content can be increased to approximately 40%, making it an environmentally friendly material.

[0041] Such a resin pulley is composed of a resin part formed integrally with the bearing, and the resin part is formed by injection molding a polyamide resin composition containing 80 to 45 weight % of PA4T, which is made from 1,4-butanediamine derived from tall oil, and 20 to 55 weight % of a reinforcing material.

[0042] Additionally, PA4T, a polycondensate of petroleum-derived terephthalic acid and 1,4-butanediamine derived from plant-derived tall oil, can be used as the base resin forming the resin portion of the resin pulley. PA4T is a polycondensate of terephthalic acid and 1,4-butanediamine in a 1:1 molar ratio, allowing for a bio-content (bio ratio) of approximately 40%. 1,4-butanediamine may also be replaced with another copolymer component to form a copolymerized polyamide.

[0043] The molecular weight of the polyamide resin is within a range that allows injection molding, specifically, a number average molecular weight of 13,000 to 28,000, and more preferably, a number average molecular weight of 18,000 to 26,000, taking into consideration fatigue resistance and moldability. If the number average molecular weight is less than 13,000, the molecular weight is too low, resulting in poor fatigue resistance and low practicality. On the other hand, if the number average molecular weight exceeds 28,000, the melt viscosity becomes too high, making it difficult to precisely manufacture a resin pulley by injection molding, which is undesirable. To ensure sufficient strength for a resin pulley, a reinforcing material is blended to prevent breakage, deformation, and wear of the resin portion and to further improve reliability.

[0044] As the reinforcing material, glass fiber, carbon fiber, aramid fiber, potassium titanate whisker, aluminum borate whisker, etc. are preferred, and those surface-treated with a silane coupling agent or the like are more preferred in consideration of adhesion to the above-mentioned polyamide resin.

[0045] Furthermore, a combination of multiple types of these reinforcing materials can be used. In consideration of impact strength, it is preferable to blend fibrous materials such as glass fibers and carbon fibers, and in consideration of the surface smoothness of the resin pulley, it is preferable to blend whisker-like materials in combination with fibrous materials. When mixed, the mixing ratio varies depending on the types of fibrous materials and whisker-like materials and is appropriately selected in consideration of impact strength, surface smoothness, etc.

[0046] In addition, glass fibers with a general average fiber diameter of 10 to 13 μm are preferred, as well as those with an average fiber diameter of 5 to 7 μm, which can improve strength and abrasion resistance with a small content, or those with an irregular cross section. Furthermore, if strength is a priority, PAN-based carbon fibers are suitable, but pitch-based fibers are also usable because of their cost advantage. The average fiber diameter is preferably 5 to 15 μm. Carbon fibers have high strength and elastic modulus, making it possible to achieve higher strength and elastic modulus in the cage compared to glass fibers.

[0047] As the aramid fiber, para-aramid fiber, which has excellent reinforcing properties, can be preferably used. The average fiber diameter is preferably 5 to 15 μm. Unlike glass fiber and carbon fiber, aramid fiber does not damage steel materials and does not deteriorate the surface condition of the mating member with which the cage comes into contact. Therefore, when the acoustic characteristics of the linear motion device are important, aramid fiber is even more preferable.

[0048] When these reinforcing materials are contained, it is preferable to blend them in a proportion of 20 to 55% by weight, particularly 25 to 40% by weight, based on the total weight. If the blending amount of the reinforcing material is less than 20% by weight, the improvement in mechanical strength is small, which is not preferable. If the blending amount of the reinforcing material exceeds 55% by weight, the moldability decreases and, depending on the type of reinforcing material, the surface smoothness also decreases, which is not preferable.

[0049] Furthermore, it is preferable to add an iodide-based heat stabilizer or an amine-based antioxidant, either alone or in combination, to the resin as an additive to prevent deterioration due to heat during molding and use.

[0050] As explained above, environmentally friendly resin pulleys can be provided by using PA4T, which is made from 1,4-butanediamine derived from plant-derived tall oil, as the resin material for the resin portion of a resin pulley. Because the biomass PA4T of this application has the same chemical composition as conventional PA4T produced solely from petroleum-derived components, it has excellent mechanical properties, heat resistance, calcium chloride resistance, and dimensional stability.

[0051] [Examples of embodiments and comparative examples of physical properties of resin material for resin pulley] The present invention will be further explained below by way of examples of the embodiment and comparative examples, but the present invention is not limited thereto in any way. Table 2 shows the physical properties of the resin material for the resin pulley. The structure of the resin pulley is shown in FIG. 2 (second embodiment). [Making a resin pulley] Resin pulleys can be manufactured integrally by injection molding using the base resins shown in Table 2 and reinforcing agents.

[0052] [Table 2]

[0053] In Example 2 of the embodiment, Envalior's ForTii Eco E11 was used as the resin composition. In Example 2 of the comparative embodiment, Envalior's ForTii K11 was used as the resin composition. In Example 3 of the comparative embodiment, Envalior's ForTii Ace MX51 was used as the resin composition.

[0054] The resin used in Example 2 of the present invention is an environmentally friendly resin from Envalior, which uses some biomass materials. Example 2 of the comparative embodiment is PA4T resin, which has been used as a material for resin pulleys. Example 2 of the present invention has the same melting point and water absorption as the comparative embodiment, and therefore has the same level of heat resistance, dimensional stability, and calcium chloride resistance as conventional resin materials.

[0055] [Third embodiment of environmentally friendly mechanical component] Next, a third embodiment of the present invention relates to a linear motion device such as a linear guide device or a ball screw used in industrial machinery. For example, as shown in Fig. 3(a), a ball screw device 20 of the linear motion device is arranged so that a ball nut 22 encloses a screw shaft 21, and a plurality of balls B are arranged to roll freely in a space formed by a screw groove 22a formed in a spiral shape on the inner periphery of the ball nut 22 and a screw groove 21a formed in a spiral shape on the outer periphery of the screw shaft 21 opposite to the ball nut 22.

[0056] A ball tube 23 having a generally U-shaped outer shape is attached to the ball nut 22 so that both ends of the ball tube 23 face the screw groove 21a of the screw shaft 21. Inside the ball nut 12, the ball B goes around the screw shaft 21 multiple times, is picked up from one end of the ball tube 23, passes through the ball circulation path 28, and is then returned from the other end of the ball tube 23 to the screw groove 21a of the screw shaft 21, repeating this circulation.

[0057] The device also includes a linear moving body 25 that is fitted onto the shaft (screw shaft 21) and moves linearly along the shaft (screw shaft 21), a number of balls B that are held by ball grooves 21b formed on the outer surface of the shaft (screw shaft 21) and ball grooves 24 formed on the inner surface of the linear moving body 25 and roll between the linear moving body 25 and the shaft (screw shaft 21), separators 40 interposed between each ball B, and a circulation passage 28 formed in the linear moving body 25 for circulating the balls B from one end side to the other end side of the ball grooves 24. As shown in FIG. 3(b), separators 40 are interposed between the balls B to eliminate collision noise between the balls.

[0058] Also, for example, as shown in Fig. 3(c), a linear guide device 30 of a linear motion device includes a guide rail 31 having rolling grooves 32 on its outer surface, and a slider assembled across the guide rail 31. The surface of the slider facing the rolling grooves 32 of the guide rail 31 is partially open, and together with the rolling grooves 32 of the guide rail 31, forms a ball circulation path 33 having a generally track-shaped cross section. A large number of balls B are accommodated in the ball circulation path 33 so as to be able to roll freely. Also, as shown in Fig. 3(d), a separator 40 is interposed between the balls B to eliminate the sound of the balls colliding with each other.

[0059] In the linear motion devices of these ball screw devices 20 and linear guide devices 30, a portion of the surface of the circulation passages 28, 33 is made of a member formed by injection molding with PA4T (melting point 300 to 340°C), or at least a portion of the surface of at least one of the circulation passages 28, 33 and the separator 40 is made of a member formed by injection molding with PA4T (melting point 300 to 340°C).

[0060] The circulation channels 28, 33 or separators 40 of this environmentally friendly mechanical component, which are made of semi-aromatic polyamide PA4T (melting point 300-340°C), use a base resin with higher heat resistance than the conventionally used polyamide 66, thereby suppressing thermal deformation during high-speed operation and improving reliability. In addition, by using 1,4-butanediamine derived from plant-derived tall oil as one of the raw materials, the bio-content can be increased to approximately 40%, making it an environmentally friendly material. In other words, by using PA4T, which is made from 1,4-butanediamine derived from plant-derived tall oil, as the resin material for the resin part of a resin pulley, it is possible to create an environmentally friendly linear motion device.

[0061] In addition, 1,4-butanediamine derived from plant-derived tall oil can be used, and PA4T is a polycondensate of terephthalic acid and 1,4-butanediamine in a molar ratio of 1:1, so the bio content (bio ratio) can be increased to approximately 40%. 1,4-butanediamine may also be replaced with another copolymer component to form a copolymerized polyamide.

[0062] The molecular weight of the polyamide resin is within a range that allows injection molding, specifically, a number average molecular weight of 13,000 to 28,000, and more preferably, in consideration of fatigue resistance and moldability, a number average molecular weight of 18,000 to 26,000. If the number average molecular weight is less than 13,000, the molecular weight is too low, resulting in poor fatigue resistance and low practicality. On the other hand, if the number average molecular weight exceeds 28,000, the melt viscosity becomes too high, making it difficult to precisely manufacture the circulation channels 28, 33 or the separator by injection molding, which is undesirable.

[0063] The base resin alone exhibits a certain level of durability, and is advantageous in preventing wear of the mating components (rolling elements) that may come into contact with the circulation passages 28, 33 or the separator, and functions satisfactorily as a cage. However, since use under more severe conditions may result in damage, deformation, or wear of the circulation passages 28, 33 or the separator, a reinforcing material may be blended to further enhance reliability.

[0064] Preferred reinforcing materials include glass fiber, carbon fiber, aramid fiber, potassium titanate whisker, aluminum borate whisker, etc., and those surface-treated with a silane coupling agent or the like are more preferred in consideration of adhesion to the above-mentioned polyamide resins. Furthermore, a combination of multiple types of these reinforcing materials can be used. Considering impact strength, it is preferable to blend fibrous materials such as glass fiber or carbon fiber, and considering damage to the mating material, it is preferable to blend whisker-like materials in combination with fibrous materials. When mixed, the mixing ratio varies depending on the type of fibrous material and whisker-like material, and is selected appropriately in consideration of impact strength, damage to the mating material, etc.

[0065] In addition, glass fibers with a general average fiber diameter of 10 to 13 μm are preferred, as well as those with an average fiber diameter of 5 to 7 μm, which can improve strength and abrasion resistance with a small content, or those with an irregular cross section. Furthermore, if strength is a priority, PAN-based carbon fibers are suitable, but pitch-based fibers are also usable because of their cost advantage. The average fiber diameter is preferably 5 to 15 μm. Carbon fibers have high strength and elastic modulus, making it possible to achieve higher strength and elastic modulus in the cage compared to glass fibers.

[0066] As the aramid fiber, para-aramid fiber, which has excellent reinforcing properties, can be preferably used. The average fiber diameter is preferably 5 to 15 μm. Unlike glass fiber and carbon fiber, aramid fiber does not damage steel materials and does not deteriorate the surface condition of the mating member with which the cage comes into contact. Therefore, when the acoustic characteristics of the linear motion device are important, aramid fiber is even more preferable.

[0067] When these reinforcing materials are contained, they are preferably blended in a proportion of 10 to 40% by weight, particularly 15 to 30% by weight, based on the total weight. If the blending amount of the reinforcing material is less than 10% by weight, the improvement in mechanical strength is small, which is not preferred. If the blending amount of the reinforcing material exceeds 40% by weight, the moldability decreases and, depending on the type of reinforcing material, the likelihood of damaging the mating material increases, which is not preferred.

[0068] Furthermore, it is preferable to add an iodide-based heat stabilizer or an amine-based antioxidant, either alone or in combination, to the resin as an additive to prevent deterioration due to heat during molding and use.

[0069] As described above, by using PA4T, a semi-aromatic polyamide with excellent heat resistance, as the base resin forming the circulation passages 28, 33 or the separator as the resin material for the separator retainer of a linear motion device, it is possible to provide a linear motion device that combines high reliability and low cost and can be used in a variety of environments. Furthermore, by using PA4T, which is made from 1,4-butanediamine derived from plant-derived tall oil, as the resin material for the resin part of the resin pulley, an environmentally friendly linear motion device can be created. [Industrial Applicability]

[0070] The present invention can be applied to industrial machinery in general. [Explanation of symbols]

[0071] 1 Deep groove ball bearing (rolling bearing) 2. Inner circle 3 outer ring 4 rolling elements 5 Cage (crown type cage) 6 Main Section 7 Claw 8 pockets 9 Sealing material 10 Rolling bearings (deep groove ball bearings) 11 Resin part 12 Inner diameter cylindrical part 13 Belt guide surface 14 Outer diameter cylindrical part 15 Disc section 16 Ribs Gate 17 18 Groove 19 Contact rubber seal 20 Ball screw device 21 Screw shaft 22 ball nut 23 Ball Tube 24 ball grooves 25 Linear motion body 28 Ball circulation path (circulation passage) 30 Linear guide device 31 Guide rail 32 Rolling groove 33 Ball circulation path (circulation passage) 40 Separator 41 Concave B Ball (rolling element)

Claims

1. An environmentally friendly mechanical part used as a component of industrial machinery, characterized in that it is formed from a polyamide resin composition containing polyamide 4T produced from raw materials derived from biomass and a reinforcing material.

2. The industrial machine is a rolling bearing comprising an inner ring, an outer ring, a cage, and rolling elements, 2. The environmentally friendly mechanical part according to claim 1, wherein the cage, which is a component of the rolling bearing, is an environmentally friendly mechanical part, and the reinforcing material is contained in an amount of 0 to 40% by weight.

3. The industrial machine is a rolling bearing comprising an inner ring, an outer ring, and rolling elements, The environmentally friendly mechanical component according to claim 1, characterized in that the pulley is made of a resin part integrally attached to the outer peripheral surface of the outer ring of the rolling bearing, and the reinforcing material is contained in an amount of 20 to 55% by weight.

4. The industrial machine, A linear motion device comprising: a linear motion body fitted onto a shaft and moving linearly along the shaft; a number of balls that are held by a ball groove formed on the outer surface of the shaft and a ball groove formed on the inner surface of the linear motion body and roll between the linear motion body and the shaft; and a circulation passage formed in the linear motion body for circulating the balls from one end side to the other end side of the ball groove, 2. An environmentally friendly mechanical component according to claim 1, wherein the circulation passage of the linear motion device is an environmentally friendly mechanical component, and the reinforcing material is contained in an amount of 10 to 40% by weight.

5. The industrial machine, A linear motion device comprising: a linear motion body fitted onto a shaft and moving linearly along the shaft; a number of balls that are held by a ball groove formed on the outer surface of the shaft and a ball groove formed on the inner surface of the linear motion body and roll between the linear motion body and the shaft; separators interposed between the balls; and a circulation passage formed in the linear motion body for circulating the balls from one end side to the other end side of the ball groove, The environmentally friendly mechanical component according to claim 1, characterized in that at least one of the separator and the circulation passage of the linear motion device is an environmentally friendly mechanical component, and the reinforcing material is contained in an amount of 10 to 40% by weight.

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