Actuator

Abstract

Provided is an actuator equipped with a rolling bearing that can be used in a highly clean environment, can prevent corrosion of grease used as a lubricant, and can reduce the amount of dust generated not only before decontamination with hydrogen peroxide or the like but also after decontamination. In an actuator equipped with a rolling bearing in which grease containing a base oil and a thickener is sealed, the base oil contains a fluorine oil that is a perfluoropolyether, the thickener contains polytetrafluoroethylene resin powder, the grease has a worked penetration of 200 or more and 295 or less, and the base oil has a kinematic viscosity at 40°C of 50mm 2 / s or more 65mm 2 / s or less, and the content of the thickener relative to the total mass of the grease is 33 mass % or more and 50 mass % or less.

Description

[Technical Field]

[0001] This invention relates to an actuator equipped with rolling bearings. [Background technology]

[0002] Rolling bearings have long been widely used in fields such as machinery and vehicles. In particular, rolling bearings lubricated with fluorine grease, for example, with fluorine oil as the base oil, are used to support the rotating parts of rotating equipment used in clean environments, vacuum environments, and high-temperature environments. Specifically, lubrication is achieved by filling the internal space of the rolling bearing with fluorine grease.

[0003] It is a well-known fact that particles are generated from the lubricant in rolling bearings within actuators when the device is in operation. Therefore, when using actuators in the various fields mentioned above, it is necessary to reduce the amount of particles generated from rolling bearings.

[0004] In particular, a cleaner environment is required in various fields such as food manufacturing, electronics, chemicals, and medicine. For example, equipment used in the field of regenerative medicine includes cell culture devices and cell stacking devices for manipulating cells. Since cells are susceptible to contamination by non-cellular substances such as particles generated from lubricants, the environment surrounding the equipment in the field of regenerative medicine must be kept extremely clean. Therefore, equipment used in the field of regenerative medicine undergoes a decontamination process involving exposure to hydrogen peroxide, etc., with the aim of reducing bacterial counts to a certain level.

[0005] Incidentally, Patent Document 1 discloses a rolling bearing in which a grease composition is filled with a grease composition that contains specific PTFE (polytetrafluoroethylene) fine particles in an amount of 30% to 90% by mass of the total amount of the grease composition, and which uses fluorine oil as the base oil. The above rolling bearing reduces the amount of perfluorooctanoic acid (PFOA) compounds that affect the global environment, and can reduce volatilization and scattering associated with the use of the rolling bearing. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-012700 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the rolling bearing described in Patent Document 1 above does not take such decontamination into consideration. For example, if a rolling bearing containing grease is exposed to hydrogen peroxide or the like, the grease may deteriorate, and it may not be able to maintain the desired lubricity. The amount of dust generated increases significantly due to the deterioration of the grease. In conventional rolling bearings, it is not possible to prevent the deterioration of the grease, especially after the decontamination process, and it is not possible to sufficiently reduce the amount of dust generated.

[0008] The present invention has been made in view of the above problems, and aims to provide a rolling bearing that can be used in a highly clean environment, can prevent deterioration of grease used as a lubricant, and can reduce the amount of dust generated even when exposed to hydrogen peroxide or the like, and an actuator equipped with this rolling bearing. [Means for solving the problem]

[0009] The above objective of the present invention is achieved by the following configuration (1) relating to a rolling bearing.

[0010] (1) A rolling bearing in which a grease containing a base oil and a thickener is sealed, The aforementioned base oil contains fluorine oil, The thickener contains polytetrafluoroethylene resin powder, A rolling bearing characterized in that the consistency of the grease is between 200 and 295.

[0011] Also, a preferred embodiment of the present invention relating to a rolling bearing relates to the following (2) to (8). (2) The base oil has a kinematic viscosity at 40 ° C of 10 mm 2 / s or more and 200 mm 2 / s or less, and the rolling bearing according to (1).

[0012] (3) The fluorine oil is perfluoropolyether, and the rolling bearing according to (1) or (2).

[0013] (4) The content of the thickener with respect to the total mass of the grease is 30% by mass or more and 50% by mass or less, and the rolling bearing according to any one of (1) to (3).

[0014] (5) The specific gravity of the grease is 1.50 or more, and the rolling bearing according to any one of (1) to (4).

[0015] (6) The oxidation stability of the grease is 10 kPa or less, and the rolling bearing according to any one of (1) to (5).

[0016] (7) The rolling bearing according to any one of (1) to (6), which is used in an environment exposed to an atmosphere containing at least one of hydrogen peroxide and peracetic acid.

[0017] (8) The rolling bearing according to any one of (1) to (7), which is included in a device used in the field of regenerative medicine.

[0018] The above object of the present invention is achieved by the following configuration (9) relating to an actuator. (9) An actuator comprising: a rolling bearing according to any one of (1) to (8); a ball screw supported by the rolling bearing; and a linear guide for guiding the moving direction of a member moved by the ball screw.

[0019] Furthermore, preferred embodiments of the present invention relating to actuators are described in (10) to (11) below. (10) The actuator according to (9), characterized in that a fluorinated low-temperature chromium plating film is formed on the surface of the ball screw and the surface of the linear guide.

[0020] (11) The actuator according to (9) or (10), which is used in an environment exposed to an atmosphere containing at least one of hydrogen peroxide and peracetic acid, and is characterized in that it does not have a cover that covers the rolling bearing, the ball screw and the linear guide. [Effects of the Invention]

[0021] The rolling bearing of the present invention specifies the base oil and thickener of the grease to be sealed in, and appropriately controls the consistency of the grease mixture, thereby preventing deterioration of the grease and maintaining excellent low-dusting characteristics even after the rolling bearing has been exposed to hydrogen peroxide or the like.

[0022] Furthermore, because the actuator of the present invention is equipped with the above-mentioned rolling bearing, it is possible to suppress the deterioration of actuator performance due to deterioration of grease or particles generated from grease, thereby enabling low-cost and long-term operation. [Brief explanation of the drawing]

[0023] [Figure 1] Figure 1 is a schematic cross-sectional view showing a rolling bearing according to this embodiment. [Modes for carrying out the invention]

[0024] The inventors of this invention have diligently studied technologies for achieving low dust generation characteristics in actuators and rolling bearings installed within actuators used in environments requiring high levels of cleanliness (hereinafter referred to as "clean environments"). As a result, they have found that by strictly adjusting the materials and physical properties of the grease used as a lubricant, it is possible to prevent deterioration of the grease, even when placed in environments exposed to hydrogen peroxide, and thereby maintain the low dust generation characteristics of the grease. This invention is based on these findings.

[0025] Furthermore, while the term "decontamination" is sometimes used below to describe environments in which rolling bearings are exposed to atmospheres containing hydrogen peroxide, etc., the above-mentioned environments are not limited to decontamination. For example, this also includes cases where rolling bearings are used in industrial applications that utilize hydrogen peroxide or peracetic acid.

[0026] The embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below, and can be modified and implemented as desired without departing from the spirit of the invention.

[0027] [Rolling bearings] Figure 1 is a schematic cross-sectional view showing a rolling bearing according to this embodiment. In Figure 1, a deep groove ball bearing is used as an example of the rolling bearing 1, and its configuration is briefly explained. The rolling bearing 1 includes an annular inner ring 3, an annular outer ring 5 arranged on the outer circumference of the inner ring 3, a plurality of balls (rolling elements) 7 that are rotatably mounted between the inner ring 3 and the outer ring 5 via a cage 9, a shield 11 that seals the inside of the bearing, and grease (not shown) sealed in the space sealed by the shield 11. Although the rolling bearing 1 shown in Figure 1 is provided with the shield 11, the configuration of the rolling bearing 1 is not limited in this embodiment, and it may be a rolling bearing without a shield 11. That is, the rolling bearing according to this embodiment is characterized by its grease, so the grease will be described in detail below.

[0028] <Grease> The grease contains a base oil and a thickener. The base oil contains fluorine oil, and the thickener contains polytetrafluoroethylene (PTFE) resin powder. The grease containing fluorine oil and PTFE has excellent high-temperature and low-temperature properties, as well as extremely good oxidation stability. Therefore, rolling bearings filled with the above grease can suppress the occurrence of rust and maintain high performance of the rolling bearings.

[0029] Examples of fluorinated oils include perfluoropolyethers (PFPE) and chlorotrifluoroethylenes (CTFE), but of these, PFPE is preferred.

[0030] (Grease consistency: 200 to 295) The consistency of the grease is a numerical value that represents the hardness of the grease, with a lower value indicating greater hardness. Conventionally, hard greases were generally used to reduce dust generation, i.e., to improve low-dust generation characteristics. In this embodiment, the consistency of the grease is appropriately defined within a higher value range than conventional methods, which is thought to improve the ability to prevent deterioration of the grease not only before decontamination but also after decontamination, i.e., to improve deterioration resistance. As a result, the rolling bearing is thought to be able to maintain excellent low-dust generation characteristics and ensure a clean environment.

[0031] When the consistency of the grease exceeds 295, the grease becomes too soft, so it is presumed that the grease is likely to scatter and easily contaminate the outside. Therefore, the consistency of the grease should be 295 or less, preferably 285 or less, and more preferably 275 or less. On the other hand, when the consistency is less than 200, the grease becomes too hard, so it is presumed that the grease cannot absorb excessive stress and undergoes compositional deformation, is easily affected by degreasing, and the dusting property deteriorates due to deterioration. Also, at normal temperature, it becomes difficult to fill the grease into the rolling bearing. Therefore, the consistency of the grease should be 200 or more, preferably 210 or more, and more preferably 220 or more. The consistency of the grease can be measured in accordance with JIS K 2220:2013.

[0032] (Kinematic viscosity of base oil at 40°C: 10 mm 2 / s or more and 200 mm 2 / s or less) By using a base oil with appropriately adjusted kinematic viscosity and adjusting the consistency of the grease as described above, the torque characteristics of the rolling bearing can be significantly improved. When the kinematic viscosity of the base oil at 40°C is 10 mm 2 / s or more, the desired lubricity can be obtained. Therefore, the kinematic viscosity of the base oil at 40°C is preferably 10 mm 2 / s or more, more preferably 30 mm 2 / s or more, and even more preferably 50 mm 2 / s or more.

[0033] On the other hand, when the kinematic viscosity of the base oil at 40°C is 200 mm 2 / s or less, an increase in frictional resistance can be suppressed, and even better low torque can be achieved. Therefore, the kinematic viscosity of the base oil at 40°C is preferably 200 mm 2 / s or less, more preferably 150 mm 2 / s or less, and even more preferably 100 mm 2It is even more preferable that the kinematic viscosity of the base oil be less than or equal to / s. The kinematic viscosity of the base oil can be measured in accordance with JIS K 2283:2000.

[0034] (Thickener content: 30% by mass or more and 50% by mass or less) The consistency of the grease is affected by the type of base oil used and the amount of thickener. When the amount of thickener is 30% by mass or more relative to the total mass of the grease, the properties of the grease can be ensured, and the consistency of the grease can be easily adjusted to 295 or less. Therefore, it is preferable that the amount of thickener relative to the total mass of the grease be 30% by mass or more. On the other hand, when the amount of thickener is 50% by mass or less relative to the total mass of the grease, it is easier to adjust the consistency of the grease to 200 or more. Therefore, it is preferable that the amount of thickener relative to the total mass of the grease be 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0035] (Specific gravity of grease: 1.50 or higher) The specific gravity of grease is affected by factors such as the amount of thickener and the type of base oil. It is also closely related to the consistency of the grease mixture. If the specific gravity of the grease is 1.50 or higher, The hardness of the grease is more easily kept within the desired range, deterioration of the grease is prevented even after decontamination, and excellent low-dusting and torque characteristics can be maintained. Therefore, the specific gravity of the grease is preferably 1.50 or higher, and more preferably 1.80 or higher. The specific gravity of the grease can be measured in accordance with JIS K 2249-1:2011.

[0036] (Oxidation stability of grease: 10kPa or less) The oxidation stability of grease can be improved by appropriately selecting the base oil and thickener contained in the grease. The oxidation stability of grease can be expressed by its oxidation stability degree. If the oxidation stability of grease is 10 kPa or less, the grease will not deteriorate even after decontamination, and it will maintain excellent low-dusting characteristics, thus maintaining good performance of the rolling bearing. Therefore, the oxidation stability of grease is preferably 10 kPa or less, and more preferably 5 kPa or less. Note that the oxidation stability of grease is defined in JIS standards. It can be measured in accordance with K 2220:2013.

[0037] (Additives in grease) The grease sealed in the rolling bearing according to this embodiment may consist of a fluorine oil as a base oil and polytetrafluoroethylene resin powder as a thickener, or it may contain various additives to further improve various performance characteristics. The amount of additives relative to the total mass of the grease is not particularly limited as long as it does not impair the objectives of the present invention.

[0038] <Operating Environments for Rolling Bearings> In conventional rolling bearings, when decontamination is carried out using hydrogen peroxide and peracetic acid, There was a problem in that the grease deteriorated, leading to a decrease in low-dust generation characteristics. Furthermore, in order to prevent a decrease in low-dust generation characteristics, it was necessary to install covers over the rolling bearings, ball screws, and linear guides, etc., to prevent the grease from deteriorating. In contrast, in this embodiment, the installation of covers, etc., is unnecessary, and even after the above-mentioned decontamination is carried out, excellent low-dust generation characteristics and torque characteristics can be maintained. Therefore, the rolling bearing according to this embodiment is preferably used in an environment exposed to an atmosphere containing at least one of hydrogen peroxide and peracetic acid, and more preferably in an environment exposed to an atmosphere containing hydrogen peroxide.

[0039] Fields in which these products are used in environments exposed to atmospheres containing hydrogen peroxide or peracetic acid include the medical and pharmaceutical fields, paper and pulp fields, textile fields, chemical industry, electronics industry, pollution control field, mining field, food industry, metal finishing and processing field, and wood processing field.

[0040] Specifically, in the medical and pharmaceutical fields, hydrogen peroxide and peracetic acid are used for decontamination of manufacturing equipment for regenerative medicine products, in the production of hydrogen peroxide solution, and as intermediate raw materials for pharmaceuticals. In the paper and pulp field, hydrogen peroxide and peracetic acid are used for bleaching various types of pulp and for deinking and bleaching recycled paper. In the textile field, hydrogen peroxide and peracetic acid are used for bleaching natural fibers such as cotton, wool, and silk, as well as synthetic fibers. In the chemical industry, hydrogen peroxide and peracetic acid are used as raw materials for organic and inorganic peroxides, organic compounds, and epoxy compounds. In the electronics industry, hydrogen peroxide and peracetic acid are used during the etching and cleaning of semiconductors and printed circuit boards. In the pollution control field, hydrogen peroxide and peracetic acid are used in sewage treatment and factory wastewater treatment (deodorization, sterilization, decolorization), and soil improvement. In the mining field, hydrogen peroxide and peracetic acid are used to oxidize metals in the smelting process. In the food industry, hydrogen peroxide and peracetic acid are used for sterilizing food manufacturing equipment and containers. In the metal finishing field, hydrogen peroxide and peracetic acid are used during surface treatment of metals and for purifying plating solutions. In the woodworking field, hydrogen peroxide and peracetic acid are used for bleaching wood and decorative panels.

[0041] As described above, devices used in the field of regenerative medicine require protection from product confusion and cross-contamination, as well as the reduction of microorganisms surviving in the structure and equipment to a predetermined bacterial count level. For this reason, devices used in the field of regenerative medicine undergo a decontamination process involving exposure to hydrogen peroxide or the like, with the aim of reducing the bacterial count to a certain level. Therefore, the rolling bearing according to this embodiment is preferably included in devices used in the medical and pharmaceutical fields, and is particularly preferably included in devices used in the field of regenerative medicine.

[0042] In the field of regenerative medicine, one method for decontaminating a work area is to evaporate and diffuse hydrogen peroxide. Specifically, hydrogen peroxide vaporized by a heater can be diffused into the inside of an isolator or work area, and the oxidizing power of hydrogen peroxide can kill microorganisms.

[0043] [Actuator] The actuator according to this embodiment comprises a rolling bearing according to this embodiment, a ball screw supported by the rolling bearing, and a linear guide that guides the direction of movement of a member moved by the ball screw. Because the actuator configured in this way is equipped with a rolling bearing with excellent low dust generation characteristics according to this embodiment, it can maintain excellent quality.

[0044] Furthermore, it is preferable that a low-temperature fluorinated chromium plating film is formed on the surface of the ball screw and the linear guide. Since the low-temperature fluorinated chromium plating film has excellent corrosion resistance, its formation on the surface of the ball screw and linear guide allows the actuator according to this embodiment to be used more effectively in a cleaner environment. It is even more preferable that stainless steel be used as the material for the ball screw and linear guide.

[0045] <Actuator Usage Environment> As described above, the rolling bearing according to this embodiment is suitably used in environments exposed to an atmosphere containing hydrogen peroxide. Therefore, the actuator equipped with the rolling bearing also exhibits excellent resistance to an atmosphere containing hydrogen peroxide. The fields in which the actuator is used in environments exposed to an atmosphere containing hydrogen peroxide and specific examples of its use are as described above, and it is particularly preferable to use the actuator according to this embodiment in the field of regenerative medicine.

[0046] Conventionally, when actuators are used in environments exposed to hydrogen peroxide, covers are generally attached to the rolling bearings, ball screws, and linear guides to prevent the scattering of particles from these components. In contrast, the actuator according to this embodiment maintains excellent low-dusting and torque characteristics even when exposed to environments containing hydrogen peroxide, as the grease does not deteriorate. Therefore, there is no need to attach covers to the rolling bearings, ball screws, and linear guides, and decontamination can be performed on the rolling bearings, ball screws, and linear guides without degrading the performance of the actuator. Therefore, the time and cost required for actuator maintenance can be reduced, enabling low-cost, long-term operation. [Examples]

[0047] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples, and modifications can be made to the extent that they are in line with the spirit of the present invention, and all such modifications are included within the technical scope of the present invention. Furthermore, the various conditions shown below are merely examples, and the present invention is not limited to these conditions.

[0048] [Experiment 1] By changing the type of grease, rolling bearings of Invention Example No. 1 and Comparative Example No. 1 were fabricated, and experiments were conducted to evaluate their cleanliness (low dust generation characteristics) and resistance to deterioration. The experimental procedure is shown below.

[0049] <Grease adjustment> A thickener and base oil were mixed to prepare the rolling bearing grease according to Invention Example No. 1. Furthermore, lithium soap and base oil were mixed to prepare the rolling bearing grease for Comparative Example No. 1. The mixing ratio of thickener to base oil in Invention Example No. 1 was 33:67. The materials of the grease are shown below. In addition, the kinematic viscosity of the base oil used in the grease was measured at 40°C and 100°C in accordance with JIS K 2283:2000.

[0050] (Grease for rolling bearings, Invention Example No. 1) Thickener: PTFE (polytetrafluoroethylene) Base oil: (linear) PFPE (perfluoropolyether) (Comparative Example No. 1: Grease for rolling bearings) Lithium soap Base oil: Mineral oil + poly-alpha olefin

[0051] <Measurement of grease properties> (Measurement of miscibility, specific gravity, and oxidation stability) The consistency of the obtained grease was measured in accordance with JIS K 2220:2013. The specific gravity of the grease was also measured in accordance with JIS K 2249-1:2011. Furthermore, the oxidation stability of the grease was measured in accordance with JIS K 2220:2013. The grease materials, base oil kinematic viscosity, and measured values ​​are shown in Table 1 below.

[0052] <Evaluation of rolling bearings> The obtained grease was sealed into the rolling bearing so as to almost completely fill its internal volume, and this rolling bearing was assembled into an actuator (manufactured by NSK Ltd., model number: XY-HS0005-734) to create an evaluation actuator. The ball screw and linear guide incorporated into the evaluation actuator were made of SUS440C material with a low-temperature fluorinated chromium plating film formed on the surface. Using the evaluation actuator, cleanliness evaluation tests before and after decontamination, as well as deterioration resistance evaluation tests, were conducted. The testing methods and evaluation criteria for each evaluation test are described in detail below. The evaluation results for each test are also shown in Table 1 below.

[0053] (Evaluation test method for cleanliness (before decontamination)) Under conditions of 23℃ and 50Rh%, the operating speed was set to 50 mm / s (1500 min). -1 ), and adjust the acceleration / deceleration to 200 mm / s 2As a condition for vertical placement, the evaluation actuator was operated for at least 180 minutes. The amount of dust generated from the evaluation actuator was measured from start to finish using a particle counter (MET ONE Model 3411 portable airborne particle counter, manufactured by Beckman Coulter, Inc.).

[0054] (Evaluation criteria for cleanliness (before decontamination)) Regarding the low-dusting characteristics before decontamination, we evaluated whether it met Class 100 standards based on the U.S. Federal Standard 209E (FED STD). That is, 1 cubic foot (1 ft 3 ) The number of particles larger than 0.5 μm is 100 (particles / ft 3 A value of less than or equal to ) was considered a pass (○). On the other hand, measurements were continued from the start to the end of operation, and 1 cubic foot (1 ft 3 ) The number of particles larger than 0.5 μm is 100 (particles / ft 3 If the score exceeded this limit, the student failed (×).

[0055] Furthermore, the evaluation criteria for particle quantity (number of particles) were based on the evaluation criteria of FED STD 209E.

[0056] (Test method for evaluating resistance to deterioration) Prior to the test, the molecular structure of the grease from the evaluation actuator was analyzed using Fourier Transform Infrared Spectroscopy (FT-IR). Then, the evaluation actuator was placed inside a safety cabinet, and a hose connected to a hydrogen peroxide gas decontamination system was passed through the safety cabinet to form a circulating flow. Decontamination was performed by using all 30 ml of 60% hydrogen peroxide concentrate. The safety cabinet was sealed to prevent leakage of hydrogen peroxide gas. After decontamination, the molecular structure of the grease from the evaluation actuator was analyzed again using FT-IR. The equipment used is listed below.

[0057] Safety cabinet: Manufactured by Japan Air Tech Co., Ltd., model number BHC-1310IIA2. Space volume approximately 0.5m 3 Hydrogen peroxide gas decontamination system: Manufactured by Optima Corporation, model number PASSTECH S1 FT-IR: BRUKER infrared spectrophotometer, model ALPHAII

[0058] (Evaluation criteria for resistance to deterioration) The FT-IR results of the grease in the evaluation actuator before decontamination and the grease in the evaluation actuator after decontamination were compared. A small change in the peak before and after decontamination was considered a pass (○). On the other hand, a significant peak after decontamination was considered a fail (×).

[0059] (Evaluation test method for cleanliness (after decontamination)) Using the evaluation actuator that underwent decontamination as described above, the evaluation actuator was operated in the same manner as the cleanliness evaluation test method before decontamination, and the amount of dust generated was measured.

[0060] (Evaluation criteria for cleanliness (after decontamination)) The criteria for evaluating cleanliness after decontamination were the same as the criteria for evaluation before decontamination.

[0061] [Table 1]

[0062] As shown in Table 1 above, the rolling bearing of Invention Example No. 1 has excellent resistance to deterioration because the grease material and mixing consistency are within the range specified in the present invention. The rolling bearing of Comparative Example No. 1 exhibited excellent low-dust generation characteristics before decontamination, and these characteristics were maintained even after decontamination. On the other hand, the rolling bearing of Comparative Example No. 1 had grease materials and mixing consistency outside the range specified in the present invention, resulting in poor evaluation results for deterioration resistance. The grease deteriorated after decontamination, and the low-dust generation characteristics after decontamination also decreased. These results indicate that the rolling bearing of Invention Example No. 1 is particularly suitable for equipment used in clean environments. Specifically, it was shown that even when strict decontamination is carried out, such as in the field of regenerative medicine, an increase in dust generation can be prevented, and the excellent performance of the rolling bearing can be maintained.

[0063] [Experiment 2] Two types of grease, which fall within the range defined in this invention, were prepared, and by sealing these greases into rolling bearings, rolling bearings of Invention Example No. 1 and Invention Example No. 2 were manufactured, and experiments were conducted to evaluate their torque characteristics. The experimental procedure is shown below.

[0064] <Grease adjustment> In the same manner as in Experiment 1 above, the rolling bearing grease of Invention Example No. 1 was prepared. Furthermore, the rolling bearing grease of Invention Example No. 2 was prepared by changing the ratio of fluorine oil and thickener used in the base oil. In addition, in the same manner as in Experiment 1, the kinematic viscosity of the base oil used in the grease was measured, and the consistency, specific gravity, and oxidation stability of the grease were also measured.

[0065] <Evaluation of rolling bearings> The obtained grease was sealed into a rolling bearing in the same manner as in Experiment 1 above, and an evaluation actuator equipped with this rolling bearing was fabricated. Then, the torque characteristics were evaluated using the evaluation actuator. The evaluation test method and evaluation criteria for torque characteristics are described in detail below.

[0066] (Test method for evaluating torque characteristics) Using the fabricated evaluation actuator, the operating speed was set to 50 mm / s (1500 min). -1 ), and adjust the acceleration / deceleration to 200 mm / s2 The motor was operated under vertical configuration conditions, and its operating torque was measured to confirm that it was functioning correctly. The actual motor operating torque was measured using software (Oriental Motor Co., Ltd., support software MEXE02).

[0067] (Evaluation criteria for torque characteristics) A test was judged as a pass (○) if the evaluation actuator operated without problems, and a fail (×) if the motor power of the evaluation actuator was insufficient and the operation stopped. The evaluation results for the base oil kinematic viscosity, grease consistency, specific gravity, oxidation stability, and torque characteristics of Invention Example No. 1 and Invention Example No. 2 are shown in Table 2 below.

[0068] [Table 2]

[0069] As shown in Table 2 above, the greases used in the rolling bearings of Invention Example No. 1 and Invention Example No. 2 were both prepared from materials specified in the present invention, and their consistency was within the range specified in the present invention. Furthermore, in the rolling bearing of Invention Example No. 1, the base oil kinematic viscosity was within the preferred range specified in the present invention, resulting in excellent torque characteristics. [Explanation of symbols]

[0070] 1. Rolling bearings 3. Inner Ring 5 Outer ring 7. Ball (rolling element) 9 Cage 11 Shields

Claims

1. An actuator comprising: a rolling bearing containing a grease comprising a base oil and a thickener; a ball screw supported by the rolling bearing; and a linear guide that guides the direction of movement of a member moved by the ball screw, The base oil contains a fluorine oil which is a perfluoropolyether, The thickener contains polytetrafluoroethylene resin powder, The consistency of the grease is 200 or more and 295 or less. The base oil has a kinematic viscosity of 50 mm at 40°C. ２ / s or more 65mm ２ / s or less, The content of the thickener relative to the total mass of the grease is 33% by mass or more and 50% by mass or less. It is used in an environment exposed to an atmosphere containing at least one of hydrogen peroxide and peracetic acid. An actuator characterized by being used in any of the following fields: medical / pharmaceutical, paper / pulp, textile, chemical industry, electronics industry, pollution control, mining, food industry, metal finishing, or woodworking.

2. The actuator according to claim 1, characterized in that the specific gravity of the grease is 1.50 or more.

3. The actuator according to claim 1, characterized in that the oxidation stability of the grease is 10 kPa or less.

4. The actuator according to any one of claims 1 to 3, characterized in that a fluorinated low-temperature chromium plating film is formed on the surface of the ball screw and the surface of the linear guide.

5. The actuator according to any one of claims 1 to 3, characterized in that it does not have a cover that covers the rolling bearing, the ball screw, and the linear guide.

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