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] The present invention relates to an actuator equipped with a rolling bearing. [Background technology]

[0002] Conventionally, rolling bearings have been widely used in the fields of machinery, vehicles, etc. In particular, rolling bearings lubricated with fluorine grease, for example, based on fluorine 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 well known that the rolling bearings in actuators generate particles from the lubricant when the device is in operation. Therefore, when actuators are used in the various fields mentioned above, there is a need to reduce the amount of particles generated by the rolling bearings.

[0004] In particular, in various fields such as food manufacturing equipment, the electronics industry, the chemical industry, and medicine, ever cleaner environments are required. For example, devices used in the field of regenerative medicine include cell culture devices and cell layering devices for manipulating cells. Because cells can be adversely affected by contamination with non-cellular substances, such as particles generated from lubricants, in the field of regenerative medicine, the environment surrounding the device must be kept extremely clean. Therefore, devices used in the field of regenerative medicine undergo a decontamination process in which they are exposed to hydrogen peroxide or the like to reduce the number of bacteria to a certain level.

[0005] Incidentally, Patent Document 1 discloses a rolling bearing filled with a grease composition that contains specific PTFE (polytetrafluoroethylene) microparticles in an amount of 30% by mass to 90% by mass of the total amount of the grease composition and uses a fluorinated oil as a base oil. The rolling bearing has a reduced content of perfluorooctanoic acid (PFOA) compounds, which have an impact on the global environment, and can reduce volatilization and scattering that accompanies the use of the rolling bearing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-012700 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the rolling bearing described in Patent Document 1 does not take into consideration the above-mentioned decontamination. For example, if a rolling bearing filled with grease is exposed to hydrogen peroxide or the like, the grease may change in quality and may not be able to maintain the desired lubrication. Deterioration of the grease significantly increases the amount of dust generated. Conventional rolling bearings cannot prevent grease deterioration, particularly after a decontamination process, and are unable to sufficiently reduce the amount of dust generated.

[0008] The present invention has been made in consideration of these problems, and has as its object to provide a rolling bearing that can be used in a highly clean environment, can prevent deterioration of the 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 object of the present invention is achieved by the following rolling bearing configuration (1).

[0010] (1) A rolling bearing in which grease containing a base oil and a thickener is sealed, The base oil contains a fluorinated oil, The thickener contains polytetrafluoroethylene resin powder, A rolling bearing characterized in that the grease has a worked penetration of 200 or more and 295 or less.

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

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

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

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

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

[0016] (7) The rolling bearing according to any one of (1) to (6), characterized in that it 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), characterized in that it 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 the 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 that guides the direction of movement of a member moved by the ball screw.

[0019] Furthermore, preferred embodiments of the present invention relating to the actuator relate to the following (10) to (11). (10) The actuator according to (9), characterized in that a low-temperature chrome fluoride 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), characterized in that it is used in an environment exposed to an atmosphere containing at least one of hydrogen peroxide and peracetic acid, and 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 enclosed grease and appropriately controls the worked penetration of the grease, thereby preventing deterioration of the grease and allowing the rolling bearing to maintain its excellent low dust generation properties even after being exposed to hydrogen peroxide, etc.

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

[0023] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a rolling bearing according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] The present inventors have conducted extensive research into technologies for achieving low dust generation characteristics for actuators used in environments requiring high cleanliness (hereinafter referred to as clean environments) and for rolling bearings installed within the actuators. As a result, they have found that by carefully adjusting the materials and physical properties of the grease used as a lubricant, it is possible to prevent deterioration of the grease, even when the actuator is placed in an environment exposed to hydrogen peroxide, etc., and thereby maintain the low dust generation characteristics of the grease. The present invention is based on these findings.

[0025] Note that, below, an environment in which a rolling bearing is exposed to an atmosphere containing hydrogen peroxide or the like is sometimes referred to as decontamination, but this type of environment is not limited to decontamination. For example, it also includes cases in which the rolling bearing is used in industrial applications that use hydrogen peroxide or peracetic acid.

[0026] Hereinafter, embodiments of the present invention will be described in detail. Note that the present invention is not limited to the embodiments described below, and can be implemented with any modifications within the scope of the gist of the present invention.

[0027] [Rolling bearings] FIG. 1 is a schematic cross-sectional view showing a rolling bearing according to this embodiment. In FIG. 1, a deep groove ball bearing is used as an example of the rolling bearing 1, and its configuration will be briefly described. The rolling bearing 1 has an annular inner ring 3, an annular outer ring 5 arranged on the outer periphery of the inner ring 3, a plurality of balls (rolling elements) 7 mounted between the inner ring 3 and the outer ring 5 via a cage 9 so that they can roll, a shield 11 that seals the interior of the bearing, and grease (not shown) that is sealed in the space sealed by the shield 11. Note that the rolling bearing 1 shown in FIG. 1 is provided with the shield 11, but in this embodiment, the configuration of the rolling bearing 1 is not limited, and it may not be provided with the shield 11. That is, the rolling bearing according to this embodiment is characterized by the grease, and the grease will be described in detail below.

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

[0029] Examples of fluorine oils include perfluoropolyether (PFPE) and chlorotrifluoroethylene (CTFE), and among these, it is preferable to use PFPE.

[0030] (Grease consistency: 200 to 295) Worked penetration is a numerical value that indicates the hardness of a grease, with the harder the grease, the smaller the numerical value. Conventionally, to reduce the amount of dust generated, i.e., to improve low-dust generation characteristics, it has been common to use hard greases. In this embodiment, the worked penetration of the grease is appropriately specified within a range of values ​​higher than conventional values, which is believed to improve the ability to prevent grease deterioration, i.e., resistance to deterioration, not only before decontamination but also after decontamination. As a result, it is believed that the rolling bearing can maintain excellent low-dust generation characteristics and ensure a clean environment.

[0031] If the worked penetration exceeds 295, the grease becomes too soft, which is thought to make it more susceptible to scattering and contaminating the exterior. Therefore, the worked penetration of the grease is set to 295 or less, preferably 285 or less, and more preferably 275 or less. On the other hand, if the worked penetration is less than 200, the grease becomes too hard, which is thought to make it unable to absorb excessive stress and cause compositional deformation, making it more susceptible to decontamination and causing deterioration that worsens dust generation. In addition, it becomes difficult to fill rolling bearings with grease at room temperature. Therefore, the worked penetration of the grease is set to 200 or more, preferably 210 or more, and more preferably 220 or more. The worked penetration of the grease can be measured in accordance with JIS K 2220:2013.

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

[0033] On the other hand, if the kinematic viscosity of the base oil at 40°C is 200mm 2 When the kinematic viscosity of the base oil at 40°C is 200mm / s or less, the increase in frictional resistance can be suppressed, and even better torque reduction can be achieved. 2 / s or less is preferable, and 150 mm 2 / s or less is more preferable, and 100 mm 2The 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 worked penetration of the grease is affected by the type of base oil used and the content of thickener. If the content 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 worked penetration of the grease can be easily adjusted to 295 or less. Therefore, the content of thickener relative to the total mass of the grease is preferably 30% by mass or more. On the other hand, if the content of thickener is 50% by mass or less relative to the total mass of the grease, the worked penetration of the grease can be easily adjusted to 200 or more. Therefore, the content of thickener relative to the total mass of the grease is preferably 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 more) The specific gravity of grease is affected by the amount of thickener and the type of base oil, etc. It is also closely related to the mixed consistency of the grease. If the specific gravity of the grease is 1.50 or higher, The hardness of the grease is easily adjusted to the desired range, deterioration of the grease is prevented even after decontamination, and excellent low dust generation and torque characteristics can be maintained. Therefore, the specific gravity of the grease is preferably 1.50 or more, and more preferably 1.80 or more. 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) By appropriately selecting the base oil and thickener contained in the grease, the oxidation stability of the grease can be improved. The oxidation stability of the grease can be expressed by its oxidation stability. If the oxidation stability of the grease is 10 kPa or less, the grease will not change even after decontamination, and it can maintain its excellent low dust generation properties, thereby maintaining good performance of the rolling bearing. Therefore, the oxidation stability of the grease is preferably 10 kPa or less, and more preferably 5 kPa or less. The oxidation stability of the grease is determined according to JIS Measurements can be made in accordance with K 2220:2013.

[0037] (Additives in grease) The grease filled in the rolling bearing according to this embodiment may be composed of a fluorinated oil as a base oil and a polytetrafluoroethylene resin powder as a thickener, and may contain various additives to further improve various performance characteristics. The content of the additives relative to the total mass of the grease is not particularly limited as long as it is within a range that does not impair the object of the present invention.

[0038] <Rolling bearing operating environment> In conventional rolling bearings, when decontamination is carried out using hydrogen peroxide and peracetic acid, There has been a problem in that the grease deteriorates and its low dust generation properties deteriorate. Furthermore, in order to prevent the deterioration of the low dust generation properties, it has been necessary to attach covers that cover the rolling bearings, ball screws, linear guides, etc., and to perform work to prevent the grease from deteriorating. In contrast, in this embodiment, the attachment of covers, etc. is not necessary, and excellent low dust generation properties and torque properties can be maintained even after the above-mentioned decontamination is carried out. Therefore, the rolling bearing according to this embodiment is preferably used in an environment where it is exposed to an atmosphere containing at least one of hydrogen peroxide and peracetic acid, and more preferably used in an environment where it is exposed to an atmosphere containing hydrogen peroxide.

[0039] Fields in which the product is used in an environment where it is exposed to an atmosphere containing hydrogen peroxide or peracetic acid include the medical and pharmaceutical fields, paper and pulp fields, textile fields, chemical industry fields, electronics industry fields, pollution treatment fields, mining fields, food industry fields, metal finishing processing fields, and wood processing fields.

[0040] Specifically, in the medical and pharmaceutical fields, hydrogen peroxide and peracetic acid are used to decontaminate manufacturing equipment for regenerative medicine products, to manufacture hydrogen peroxide, and as intermediate raw materials for pharmaceuticals. In the paper and pulp field, hydrogen peroxide and peracetic acid are used to bleach various pulps and to deink and bleach waste paper. In the textile field, hydrogen peroxide and peracetic acid are used to bleach 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 in etching and cleaning semiconductors and printed circuit boards. In the pollution treatment industry, hydrogen peroxide and peracetic acid are used in sewage treatment and industrial wastewater treatment (deodorization, bacteria removal, decolorization) and soil improvement. In the mining industry, 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 to sterilize food manufacturing equipment and containers. In the metal finishing industry, hydrogen peroxide and peracetic acid are used in the surface treatment of metals and the purification of plating solutions. In the wood processing industry, hydrogen peroxide and peracetic acid are used to bleach wood and decorative panels.

[0041] As mentioned above, it is necessary for devices used in the field of regenerative medicine to prevent product mix-up and cross-contamination, and to reduce the number of microorganisms living in the structure and equipment to a pre-specified bacterial count level. For this reason, devices used in the field of regenerative medicine are subjected to a decontamination process in which they are exposed to hydrogen peroxide or the like, with the aim of reducing the number of bacteria 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 particularly preferably in devices used in the field of regenerative medicine.

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

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

[0044] It is preferable that a low-temperature chrome fluoride plating film is formed on the surface of the ball screw and the surface of the linear guide. Since low-temperature chrome fluoride plating film has excellent corrosion resistance, by forming it on the surfaces of the ball screw and the linear guide, the actuator according to this embodiment can be used even more suitably in a clean environment. It is more preferable that stainless steel be used as the material for the ball screw and the linear guide.

[0045] <Actuator operating environment> As described above, the rolling bearing according to this embodiment is suitable for use in environments exposed to an atmosphere containing hydrogen peroxide. Therefore, an actuator equipped with this rolling bearing also has excellent resistance to an atmosphere containing hydrogen peroxide. Fields in which it 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 an actuator is used in an environment exposed to hydrogen peroxide, covers have generally been attached to the rolling bearings, ball screws, and linear guides to prevent particles and the like from scattering from the rolling bearings or ball screws. In contrast, in the actuator according to this embodiment, even when exposed to an environment containing hydrogen peroxide or the like, the grease does not deteriorate and excellent low-particle generation and torque characteristics can be maintained. Therefore, there is no need to attach covers to cover the rolling bearings, ball screws, and linear guides, and the rolling bearings, ball screws, and linear guides can be decontaminated without degrading the performance of the actuator. Therefore, the time and cost required for maintaining the actuator can be reduced, and long-term operation can be achieved at low cost. [Example]

[0047] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples and can be practiced with modifications within the scope of the present invention, all of which are included in 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] Rolling bearings of Example No. 1 and Comparative Example No. 1 were manufactured using different types of grease, and experiments were conducted to evaluate the cleanliness (low dust generation characteristics) and resistance to deterioration. The experimental procedures are as follows.

[0049] <Grease adjustment> The thickener and base oil were mixed to prepare grease for rolling bearings as invention example No. 1. Lithium soap and base oil were mixed to prepare grease for rolling bearings as Comparative Example No. 1. The blending ratio of thickener to base oil in Inventive Example No. 1 was 33:67. The grease ingredients are listed below. 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 of invention example No. 1) Thickener: PTFE (polytetrafluoroethylene) Base oil: (linear) PFPE (perfluoropolyether) (Comparative Example No. 1 Rolling Bearing Grease) Lithium soap Base oil: mineral oil + poly-α-olefin

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

[0052] <Evaluation of rolling bearings> The obtained grease was filled into the spatial volume of a rolling bearing so that it was almost completely filled, and this rolling bearing was incorporated into an actuator (manufactured by NSK Ltd., model number: XY-HS0005-734) to produce an evaluation actuator. The ball screw and linear guide incorporated into the evaluation actuator were made of SUS440C, with a low-temperature chrome fluoride plating film formed on the surface. Then, using the evaluation actuator, cleanliness evaluation tests before and after decontamination, and evaluation tests for deterioration resistance were carried out. The test methods and evaluation criteria for each evaluation test are explained in detail below. The evaluation results for each test are also shown in Table 1 below.

[0053] (Test method for evaluating cleanliness (before decontamination)) In an environment of 23°C and 50% RH, the operating speed is 50 mm / s (1500 min -1 ), acceleration / deceleration 200mm / s 2The actuator was operated for at least 180 minutes in a vertical position, and the amount of dust emitted from the actuator was measured using a particle counter (MET ONE Model 3411, portable airborne particle counter, manufactured by Beckman Coulter, Inc.) from the start to the end of operation.

[0054] (Certification criteria for cleanliness (before decontamination)) The low dust generation characteristics before decontamination were evaluated based on Federal Standard 209E (FED STD) to see if they met Class 100. 3 ) in which the number of particles of 0.5 μm or more is 100 (pieces / ft 3 ) or less was considered to be a pass (○). On the other hand, measurements were continued from the start to the end of operation, and 3 ) in which the number of particles of 0.5 μm or more is 100 (pieces / ft 3 ) was deemed to be a failure (×).

[0055] The evaluation criteria for particle quantity (particle count) were based on FED STD 209E.

[0056] (Test method for evaluating resistance to deterioration) The molecular structure of the grease in the evaluation actuator was analyzed in advance using Fourier transform infrared spectroscopy (FT-IR). The evaluation actuator was then placed in a safety cabinet, and a hose connected to a hydrogen peroxide gas decontamination system was passed through the safety cabinet, forming a circulatory flow system. The decontamination operation was performed so that all 30 ml of 60% hydrogen peroxide concentrate was used. The safety cabinet was sealed to prevent hydrogen peroxide gas from leaking. The molecular structure of the grease in the evaluation actuator after decontamination was then analyzed using FT-IR. The equipment used is shown below.

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

[0058] (Evaluation criteria for resistance to deterioration) The FT-IR results of the grease in the evaluation actuator before and after decontamination were compared, and if there was little change in the peak before and after decontamination, it was judged as passing (◯).On the other hand, if a significant peak appeared after decontamination, it was judged as failing (×).

[0059] (Test method for evaluating cleanliness (after decontamination)) Using the evaluation actuator that had been decontaminated by the above-described deterioration resistance test, the evaluation actuator was operated in the same manner as in the cleanliness evaluation test method before decontamination, and the amount of dust generated was measured.

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

[0061] [Table 1]

[0062] As shown in Table 1 above, the rolling bearing of Example No. 1 has excellent resistance to deterioration because the grease material and worked penetration are within the ranges specified in the present invention. The results showed that the low dust generation characteristics were excellent before decontamination, and that these characteristics were maintained even after decontamination. On the other hand, the rolling bearing of Comparative Example No. 1 had a grease material and worked penetration outside the ranges specified in the present invention, so the evaluation result for deterioration resistance was poor, the grease deteriorated after decontamination, and the low dust generation characteristics after decontamination deteriorated. These results demonstrate 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 rigorous 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 within the range specified by the present invention were prepared, and rolling bearings of invention examples No. 1 and No. 2 were fabricated by filling the rolling bearings with these greases, and an experiment was conducted to evaluate the torque characteristics. The experimental procedure is as follows:

[0064] <Grease adjustment> Grease for rolling bearings of Inventive Example No. 1 was prepared in the same manner as in Experiment 1 above. Grease for rolling bearings of Inventive Example No. 2 was also prepared by changing the ratio of fluorinated oil and thickener used in the base oil. Furthermore, in the same manner as in Experiment 1, the kinematic viscosity of the base oil used in the grease was measured, and the worked penetration, specific gravity, and oxidation stability of the grease were also measured.

[0065] <Evaluation of rolling bearings> The obtained grease was filled into a rolling bearing in the same manner as in Experiment 1, and an evaluation actuator equipped with this rolling bearing was fabricated. The evaluation actuator was then used to evaluate torque characteristics. The evaluation test method and evaluation criteria for torque characteristics are described in detail below.

[0066] (Test method for evaluating torque characteristics) The actuator was fabricated for evaluation, and the operating speed was set to 50 mm / s (1500 min -1 ), acceleration / deceleration 200mm / s2 The motor was operated in a vertical position, and the operating torque of the motor was measured to confirm that it was operating normally. The actual motor operating torque was measured using software (support software MEXE02, manufactured by Oriental Motor Co., Ltd.).

[0067] (Evaluation criteria for torque characteristics) If the evaluation actuator operated without any problems, it was rated as passed (○), and if the evaluation actuator's motor power was insufficient and it stopped operating, it was rated as failed (×). The evaluation results of the base oil kinematic viscosity, grease worked penetration, specific gravity and 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 Samples 1 and 2 were both prepared from materials specified in the present invention, and their worked penetrations were also within the range specified in the present invention. Furthermore, the rolling bearing of Invention Sample 1 had excellent torque characteristics because the base oil kinematic viscosity was within the preferred range specified in the present invention. [Explanation of symbols]

[0070] 1, rolling bearings 3. Inner circle 5 outer ring 7 balls (rolling elements) 9 Cage 11 Shield

Claims

1. An actuator comprising: a rolling bearing in which grease containing a base oil and a thickener is sealed; a ball screw supported by the rolling bearing; and a linear guide that guides a moving direction of a member moved by the ball screw, 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, The base oil has a kinematic viscosity of 50 mm at 40°C. ２ / s or more 65mm ２ / s or less, An actuator, wherein a content of the thickener relative to the total mass of the grease is 33 mass % or more and 50 mass % or less.

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

3. 2. The actuator according to claim 1, wherein the grease has an oxidation stability of 10 kPa or less.

4. 4. The actuator according to claim 1, which is used in an environment exposed to an atmosphere containing at least one of hydrogen peroxide and peracetic acid.

5. 4. The actuator according to claim 1, wherein a low-temperature chrome fluoride plating film is formed on the surface of the ball screw and the surface of the linear guide.

6. 4. The actuator according to claim 1, wherein the actuator is used in an environment exposed to an atmosphere containing at least one of hydrogen peroxide and peracetic acid, and does not have a cover that covers the rolling bearing, the ball screw, and the linear guide.

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