JP2005042771A - Linear bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear bearing with excellent maintainability which can increase an oil impregnating amount of a porous body even when the fluidity of lubricating oil is low and can make an oil replenishing interval in the porous body longer. <P>SOLUTION: The linear bearing is constituted as follows. The porous body 5 supplies fluorine-containing oil (the lubricating oil) to a ball (a rolling body) 3 passing through the inside of a passage hole 4a2. A fluorine-containing coating 6, which is composed of a fluorine-containing compound having excellent affinity with the oil, is formed on the surface of the passage hole of the porous body 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear bearing used in a semiconductor manufacturing apparatus or the like.
[0002]
[Prior art]
The linear motion bearing includes a plurality of balls and a moving member that is movably disposed on the guide shaft by these balls, and the moving member and the mechanical component connected to the member move along the guide shaft. To support. By the way, in such a linear motion bearing, the guide shaft is usually provided in a state of being exposed to the outside, and the lubricant (lubricating oil) tends to flow out from the guide shaft, and the lubricating oil tends to decrease. It was necessary to repeat the replenishment. Therefore, in a conventional linear motion bearing, a porous resin pipe material having a passage hole through which a ball can pass is inserted into a through hole formed in the moving member, and the pipe material is lubricated. There is one in which oil is impregnated and lubricating oil impregnated into the ball passing through the passage hole is supplied from the pipe material (for example, see Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-161916 (second page, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional linear motion bearing, it is generally difficult to ensure a sufficient oil content of the resin pipe material. Specifically, it is possible to increase the oil content of the pipe material by increasing the thickness of the pipe material or increasing the porosity. However, even when the oil content of the pipe material is increased as described above, depending on the fluidity of the lubricating oil specified by the viscosity, the oil may penetrate from the surface of the passage hole of the pipe material to the pores existing deeply. In some cases, the pipe material cannot be impregnated with lubricating oil up to its oil content, and the oil content of the pipe material cannot be increased. As a result, the period during which the lubricating oil can be supplied to the ball from the passage hole side is shortened, and it is necessary to frequently replenish the pipe material including the mounting and detaching operations of the resin pipe material (porous body). In some cases, the maintainability of the linear motion bearing may deteriorate.
[0005]
In view of the conventional problems as described above, the present invention can increase the oil content of the porous body even when the fluidity of the lubricating oil is low, and increase the oil replenishment interval in the porous body. An object of the present invention is to provide a linear motion bearing with excellent maintainability.
[0006]
[Means for Solving the Problems]
The linear motion bearing of the present invention includes a moving member that is movably supported by a guide shaft via a plurality of rolling elements, and is provided in the moving member. The rolling element passes through the rolling element and passes through the rolling element. A linear motion bearing provided with a passage hole constituted by a porous body for supplying impregnated lubricating oil,
A fluorine-based oil is used as the lubricating oil, and a film made of a fluorine-based compound is formed on at least the surface of the passage hole.
[0007]
In the porous body in the linear motion bearing configured as described above, since the fluorine-based film having good affinity with the fluorine-based oil is formed on the surface of the passage hole, the oil in the porous body is formed. The permeability to can be increased. As a result, the oil easily penetrates from the surface side of the passage hole of the porous body to the inner side, and even if the fluidity of the oil is low, the porous body exists deep from the surface of the passage hole unlike the conventional example. The oil can be reliably held within the pores to be increased, and the oil content of the porous body can be increased. Accordingly, the period during which the lubricating oil can be supplied from the passage hole side to the rolling element can be lengthened, and therefore the maintenance interval of the linear motion bearing can be improved by providing a long oil replenishing interval for the porous body. Can do.
[0008]
In the linear motion bearing, the porous body may be configured using at least one of a ceramic material, a carbon material, and a fluororesin.
In this case, the porous body is composed of a material having excellent heat resistance, and in combination with the use of the fluorine-based oil having excellent heat resistance, the heat resistance temperature of the linear motion bearing is increased to increase the temperature. A linear motion bearing that can be used in an environment can be configured.
[0009]
Moreover, in the linear motion bearing, it is preferable that the kinetic viscosity of the fluorinated oil is 1000 to 2200 (cSt).
In this case, by setting the kinematic viscosity of the fluorinated oil to 1000 (cSt) or more, scattering and dust generation of the oil can be suppressed. In addition, by setting the kinematic viscosity to 2200 (cSt) or less, it is possible to smoothly move the rolling elements by restricting the viscosity resistance of the oil while ensuring necessary fluidity.
[0010]
Moreover, in the linear motion bearing, it is preferable that the porous body contains 30 to 50% fluorine-based oil with respect to the pore volume.
In this case, by setting the oil volume ratio of the fluorinated oil to 30% or more of the pore volume, the necessary lubricity is secured, and the dust generation property of the oil is suppressed by limiting it to 50% or less. it can.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the linear bearing of the present invention will be described with reference to the drawings. In the following description, a linear motion bearing incorporated in a semiconductor manufacturing apparatus used in a high temperature and vacuum environment will be described as an example.
FIG. 1 is a longitudinal sectional view of a linear motion bearing according to an embodiment of the present invention. 2A is an enlarged cross-sectional view taken along the line II-II in FIG. 1 and shows a main part configuration of the linear motion bearing shown in FIG. 1, and FIG. 2B is an enlarged cross-sectional view of a portion A in FIG. 1 and 2, a linear motion bearing 1 according to this embodiment includes a guide shaft 2 and a moving member 4 supported by the guide shaft 2 through a plurality of balls (rolling elements) 3 so as to be movable. The linear motion bearing 1 supports a movable part (not shown) of the semiconductor manufacturing apparatus connected to the moving member 4 side that moves linearly along the guide shaft 2.
The moving member 4 includes a housing 4a and side plates 4b and 4c that are detachably attached to the left and right sides of the housing 4a. The housing 4a and the side plates 4b and 4c are provided with a ball circulation path, and the ball 3 moves in the ball circulation path in accordance with the movement of the movable part and the moving member 4, so that these movable parts and The moving member 4 can move smoothly.
[0012]
More specifically, the housing 4a is disposed so as to face the surface of the guide shaft 2, and includes a load rolling part 4a1 (FIG. 1) on which the ball 3 rolls between the surface of the guide shaft 2 and the housing 4a. For example, a first passage hole 4a2 forming a return passage for returning the ball 3 to the load rolling part 4a1 is provided so as to penetrate in the left-right direction in the figure in a circular shape in cross section.
Further, as shown in FIG. 1, the side plates 4b and 4c are respectively formed with second passage holes 4b1 and 4c1 that are curved in a semicircular shape. The left and right end sides of the load rolling part 4a1 are connected to one end sides of the passage holes 4b1 and 4c1, and the left and right end sides of the passage hole 4a2 are connected to the other end sides of the passage holes 4b1 and 4c1. The ball circulation path is formed.
[0013]
The first passage hole 4a2 is constituted by a hollow cylindrical porous body 5 as lubricating oil supply means for supplying lubricating oil to the ball 3 passing through the inside. The porous body 5 is impregnated with lubricating oil, and the lubricating oil is sequentially applied to the balls 3 circulating in the ball circulation path to maintain the lubricity of the balls 3.
The porous body 5 is detachably attached to the through hole 4a3 inside the housing 4a, and can prevent the lubricating oil from splashing outside the moving member such as the guide shaft surface as much as possible. It is possible to replenish as appropriate.
The porous body 5 is made of a material having a heat resistance of 200 ° C. or higher, such as a SiC-based ceramic material, and has a predetermined inner diameter larger than the diameter of the ball 3. It is formed as follows. The length of the porous body 5 is equal to the length of the passage hole 4a2.
[0014]
The porous body 5 is sintered after the ceramic material is hardened by press molding, and has a porosity of about 10 to 30%. Furthermore, the porous body 5 is impregnated with, for example, fluorine-based oil as a lubricating oil whose oil content hardly evaporates even in a high temperature (for example, Max 260 ° C.) and vacuum environment, and the ball 3 passes through the porous body 5. The oil is oozed out to the inner space side by capillary action and adheres onto the ball 3 passing through the porous body 5 to form an oil film.
Further, on the surface of the passage hole 4a2 of the porous body 5, as shown in FIG. 2, a fluorine-based coating 6 having excellent heat resistance and good affinity with fluorine-based oil is formed. The coating 6 improves the permeability of the porous body 5 with respect to the oil.
[0015]
Specifically, the fluorine-based coating 6 is formed by immersing the porous body 5 in a treatment tank filled with the liquid fluorine-based compound for a predetermined time, and is in the submicron order (preferably, 0.1. It is formed on all the outer surfaces (that is, the inner and outer peripheral surfaces and the axial end surfaces on the left and right sides in the figure) of the porous body 5 so as to have a predetermined thickness of about 1 to 0.3 μm (however, FIG. 2 ( In a), only the coating 6 formed on the inner peripheral surface (surface of the passage hole 4a2) is shown.)
In addition, as shown in FIG. 2 (b), the coating 6 exists not only from the peripheral surface of the pore 5 a near the inner peripheral surface of the porous body 5 but also from the inner peripheral surface inside the porous body 5. It is also provided on the peripheral surface of the pore 5b. Specifically, a part of the pores 5b communicates with the outside of the porous body 5 (not shown), and the fluorine-based compound is formed from the outside of the porous body toward the pores 5b at the time of film formation. The coating 6 is formed on the porous body surface surrounding the pores 5b. Thus, the fluorine-based coating 6 is formed on the surface of the porous body 5 including the peripheral surfaces of all the pores 5a and 5b that can communicate with the outside, and the oil is coated 6 regardless of its fluidity. It becomes easy to penetrate from the outer side to the inner side of the porous body 5 along the line, and the oil permeability in the porous body 5 is improved.
Further, even when the porous body 5 supplies oil to the ball 3, an appropriate amount of oil can be smoothly oozed along the coating 6 by the capillary phenomenon and supplied from the passage hole 4a2. Further, the fluorine-based coating 6 has self-lubricating properties, and the lubricity of the porous body 5 with respect to the balls 3 can be improved.
[0016]
Moreover, the oil whose oil dynamic viscosity is 1000-2200 (cSt; centistokes) is selected. Further, this oil is diluted with a solvent, and can be easily impregnated with 30 to 50% of fluorine-based oil with respect to the pore volume of the porous body 5. Thus, by selecting the oil kinematic viscosity and the oil volume ratio, the porous body 5 can supply an appropriate amount of oil to the balls 3 even under the high temperature vacuum environment.
Specifically, by selecting a kinematic viscosity of 1000 (cSt) or more, the adhesion (retention property) of the fluorinated oil to the surface of the ball 3 is enhanced, and the oil is scattered and dusting even in a high temperature vacuum environment. And the occurrence of external contamination by oil can be suppressed. In addition, by setting the kinematic viscosity to 2200 (cSt) or less, the required fluidity can be secured and the amount of oil supplied on the ball surface can be prevented from decreasing, and the oil viscosity resistance is limited. Thus, it is possible to suppress the oil from hindering the ball motion of rolling in the porous body 5 as much as possible.
Further, by selecting an oil volume ratio of 30% or more, necessary lubricity can be ensured, seizure or the like can be prevented, and the life of the linear bearing 1 can be extended. Moreover, the dust generation property of the oil can be suppressed by limiting the oil volume ratio to 50% or less.
[0017]
When the kinematic viscosity is less than 1000 (cSt) or when an oil volume ratio of less than 30% is selected, it is difficult to form or maintain an oil film having an appropriate thickness on the ball surface under the high temperature vacuum environment. , Oil may splatter and bearing life may be reduced. In addition, when a kinematic viscosity exceeding 2200 (cSt) is selected, it becomes difficult to supply oil from the porous body 5 to the ball surface side, and the bearing life is reduced. Further, when the oil volume ratio exceeds 50%, the oil supply amount increases, and external contamination due to oil scattering tends to occur.
[0018]
In the linear motion bearing 1 of the present embodiment configured as described above, since the fluorine-based coating 6 improves the permeability of the fluorine-based oil in the porous body 5, the fluidity is high due to high viscosity and the like. Even when the porous body 5 is impregnated with low oil, the porous body 5 can permeate and hold the oil in the pores 5a and 5b. As a result, even when the fluidity of the oil is low, the oil content of the porous body 5 can be increased. As a result, the period during which the lubricating oil can be supplied to the ball 3 from the passage hole 4a2 side can be lengthened. Therefore, the porous body 5 can be removed from the housing 4a, and the period (oil replenishment interval) in which the porous body 5 needs to be replenished with oil can be extended to improve the maintainability of the linear motion bearing 1. be able to. In addition, since the oil can easily permeate all the pores 5a and 5b that can hold the oil present in the porous body 5, the oil content capacity that can be impregnated by the porous body 5 is reduced in a short time. Oil can be impregnated.
[0019]
Here, the verification test and result example of the oil content increase performed by the inventors of the present application will be described.
In the verification test, two types of test products were prepared for the porous body made of the ceramic material having the same size and shape and the same porosity, with and without the fluorine-based coating formed on the surface. Then, each of these test products was impregnated with a fluorine-based oil having a kinematic viscosity of about 1500 (cSt) under the same conditions (conditions of being immersed in an oil tank at room temperature and atmospheric pressure for the same time). As a result, the test product with the coating contained almost 100% of the oil content. On the other hand, the test product without the coating contained only about 60% of the maximum oil content. Further, in order to impregnate 100% oil in the same time into a test product without the coating, it was necessary to externally increase the oil osmotic pressure using a vacuum impregnation apparatus.
[0020]
In the above description, the case where the present invention is applied to a linear motion bearing incorporated in a semiconductor manufacturing apparatus used in a high-temperature vacuum environment has been described. In a porous body that sequentially supplies fluorine-based oil to the rolling elements, any porous film having a good affinity with the oil may be formed on at least the surface of the passage hole. It can be applied to various linear motion bearings.
[0021]
Specifically, materials having excellent heat resistance other than the above ceramic materials include carbon (graphite) materials, composite materials of these ceramic materials and carbon materials, and fluororesins. Ceramic materials, carbon materials, and A porous body may be formed using at least one of fluororesin, and a fluorine-based film may be provided on the surface of the passage hole. When the ceramic material is used, the wear resistance can be improved and the life of the porous body can be extended. Moreover, when a carbon material or a fluororesin is used, the self-lubricating property of the porous body can be enhanced. In addition, by forming a self-lubricating fluorine-based coating on the surface of the porous body using a low-friction material such as the ceramic material, the area where the ball contacts the metal on the ball circulation path is reduced. In addition, even if a shortage of lubricating oil occurs, the metal contact area of the ball is reduced, so that adhesion (seizure) of the metal material due to the shortage of lubricating oil can be prevented.
[0022]
【The invention's effect】
According to the linear motion bearing of the present invention, even when the fluidity of the fluorinated oil (lubricating oil) is low, the oil content of the porous body can be increased and the oil supply interval in the porous body can be increased. The maintainability of the bearing can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a linear motion bearing according to an embodiment of the present invention.
2A is an enlarged cross-sectional view taken along line II-II in FIG. 1 and shows an essential configuration of the linear motion bearing shown in FIG. 1, and FIG. 2B is an enlarged cross-sectional view of part A of FIG. .
[Explanation of symbols]
1 Linear motion bearing 2 Guide shaft 3 Ball (rolling element)
4 Moving member 4a2 Passage hole 5 Porous body 6 Fluorine coating

Claims (4)

A movable member supported by a guide shaft through a plurality of rolling elements, and a moving member provided in the movable member, through which the rolling elements pass, and supply impregnated lubricating oil to the passing rolling elements A linear motion bearing provided with a passage hole constituted by a porous body,
While using a fluorine-based oil for the lubricating oil,
A linear motion bearing characterized in that a coating made of a fluorine compound is formed on at least the surface of the passage hole. The linear motion bearing according to claim 1, wherein the porous body is configured by using at least one of a ceramic material, a carbon material, and a fluororesin. The linear motion bearing according to claim 1, wherein the fluorinated oil has a kinematic viscosity of 1000 to 2200 (cSt). The linear motion bearing according to any one of claims 1 to 3, wherein the porous body contains 30 to 50% of fluorinated oil with respect to the pore volume.

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