JP2007218356A - Separator for linear drive device, and linear drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear drive device having a necessary durability even when used under a condition that an oil film is hardly formed. <P>SOLUTION: A solid lubricating coating 1A having a solid lubricating material with an area ratio of 75% or more is formed in a surface to make at least a concavity (retaining surface) 1a of separator 1 for the linear drive device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a separator interposed between a plurality of rolling elements in a linear motion device (for example, a ball screw, a linear guide, a linear ball bearing).

In machine equipment such as machine tools and industrial robots in machining centers, linear motion is provided with balls and rollers as rolling elements in order to convert rotational motion into linear motion and to smoothly perform linear motion such as work tables. Many devices are used.
A ball screw, which is an example of a linear motion device, includes a screw shaft having a thread groove (track surface) formed on the outer peripheral surface, a nut having a thread groove (track surface) formed on the inner peripheral surface, and a space between these screw grooves. A plurality of balls (rolling elements) that are arranged so as to roll on a ball rolling path formed on the outer periphery of the ball, and formed on the outer peripheral surface of the nut to circulate the ball from one end side to the other end side of the ball rolling path. A circulation path (for example, a tube or a piece) is provided, and when the ball rolls, the nut moves linearly relative to the screw shaft.

In such a ball screw, the friction loss during operation is almost negligible, so the driving efficiency is extremely high, and since there is no sliding during the relative rotation of the screw shaft and the nut, the friction of the component parts is extremely low. There is an advantage. On the other hand, in the ball screw, adjacent balls come into contact with each other, and relative sliding occurs at the contact surface at twice the rolling speed of the ball. Therefore, when the driving speed of the ball screw is increased, the surface of the ball is compared. In some cases, wear may exceed the allowable limit within a short time, or the surface of the ball or the thread groove may be seized due to frictional heat.
In view of this, there has been proposed a technique for suppressing the above-described relative slip by alternately arranging balls and spacer balls having a slightly smaller diameter than the balls and rotating the spacer balls in a direction opposite to the balls.

  However, a ball screw with spacer balls can prevent wear and seizure on the surface of the ball, but the number of balls is reduced by about half because the spacer balls are interposed. The axial load is approximately doubled, and the allowable load and rigidity of the ball screw is approximately half that of a case where no spacer ball is interposed. Therefore, in order to smoothly drive the ball screw at high speed, it is necessary to increase the number of balls by increasing the axial dimension of the nut, leading to an increase in product cost, an increase in the size of the entire machine, The increase in inertial mass may make it difficult to control when starting or stopping. In addition, when the ball screw is driven at high speed, the ball and spacer ball collide when starting or stopping, causing wear such as indentation or peeling on the surface of the ball, or driving noise. There is also.

Therefore, in Patent Documents 1 to 3, as a method for making it difficult to generate wear and driving noise on the surface of a ball without significantly reducing the allowable load, in Patent Documents 1 to 3, rolling of these balls is performed between a plurality of balls. A method for interposing a separator having a holding surface for holding the surface has been proposed.
In Patent Document 1, it is proposed that the holding surface of the separator is a concave surface having a radius of curvature larger than the radius of the ball.

In Patent Document 2, it is proposed to form a plurality of protrusions on the holding surface of the separator in a distributed manner so that the tips thereof follow the spherical surface of the ball.
Patent Document 3 proposes that the outer diameter of the separator is smaller than the outer diameter of the ball and that the outer diameter difference between the ball and the separator is larger than the amount of elastic deformation generated by the ball when an allowable load is applied. ing.

  In such a ball screw described in Patent Document 1 to Patent Document 3, since a larger number of balls that receive an axial load can be disposed compared to the ball screw in which the spacer ball is disposed, a reduction in allowable load and rigidity is suppressed. In addition, the balls do not easily come into contact with each other, and the lubricant can be held on the holding surface of the separator.

By the way, as a method for making it difficult to cause wear on the surface of the ball without interposing a separator, in Patent Document 4, a fine particle of molybdenum disulfide is sprayed onto the surface of the ball to be fixed by collision. A method of forming a solid lubricating film having a thickness of 0.5 μm or less has been proposed.
JP 11-315835 A JP 2000-199556 A JP 2001-21018 A JP 2004-60742 A

  However, in order to further improve the performance of the above-mentioned mechanical device, the linear motion device used in this mechanical device is subjected to short stroke reciprocating motion under high temperature and high load, etc. (For example, if the oil film parameter is 3 or less), the technique described in Patent Document 1 to Patent Document 3 described above may cause wear on the surface of the ball, and the durability required for the linear motion device cannot be obtained. There is.

  On the other hand, in order to make it difficult to cause wear on the surface of the ball, in the linear motion device in which the separators described in Patent Documents 1 to 3 are disposed, the solid lubricating film described in Patent Document 4 is formed on the surface of the ball. Can be considered. However, when the solid lubricant film described in Patent Document 4 is formed on the surface of the ball, the sphericity of the ball is not sufficient, and thus drive noise may easily occur. Further, since the solid lubricating film described in Patent Document 4 is easily peeled off when used under conditions where the oil film described above is difficult to form, even if this solid lubricating film is formed on the surface of a ball, The required durability may not be obtained.

  Then, even if it is a case where it is a case where it is used on the conditions where an oil film is hard to form, this invention makes it the subject to provide the linear motion apparatus provided with required durability.

  In order to solve such a problem, it is interposed between a plurality of rolling elements that are movably disposed between a first member and a second member having raceways facing each other, and In a linear motion separator having a holding surface that receives the rolling surface of the rolling element on an opposing surface, a solid lubricating film having a solid lubricant of 75% or more in area ratio is formed on at least the surface forming the holding surface. A separator for a linear motion device is provided.

  According to the separator for a linear motion device of the present invention, since the solid lubricating film having a solid lubricant having a specific area ratio or more is formed on at least the surface of the separator, the solid lubricating film adheres to the surface. Therefore, it is difficult to cause wear on the rolling surface of the rolling element to be held. Therefore, by interposing this separator for a linear motion device between a plurality of rolling elements arranged between the first member and the second member of the linear motion device, it is difficult to form an oil film (for example, an oil film parameter). Even if it is used in 3 or less), the durability required for the linear motion device can be obtained.

In the linear motion separator according to the present invention, it is preferable that the solid lubricant film has a solid lubricant having an area ratio of 95% or less.
According to this, since the solid lubricating film is further formed in close contact with the surface of the separator, it is possible to further prevent wear on the rolling surface of the rolling element to be held. Here, when the solid lubricant forming the solid lubricant film is present in an area ratio of more than 95%, the effect obtained by the solid lubricant film is saturated, and the solid lubricant film is peeled off to generate foreign matter, acoustic defects, And an increase in vibration is likely to occur.

Furthermore, in the separator for a linear motion device according to the present invention, it is preferable that the solid lubricant film is formed with a thickness of 0.10 μm or more and 8 μm or less.
Here, when the thickness of the solid lubricating coating is less than 0.10 μm, it becomes impossible to effectively suppress the occurrence of wear. On the other hand, when the thickness of the solid lubricating film exceeds 8 μm, the adhesion strength of the solid lubricating film cannot be obtained, and therefore, generation of foreign matter, acoustic failure, and increase in vibration are likely to occur.

Furthermore, in the linear motion device separator according to the present invention, it is preferable that the solid lubricant film is formed on a surface having a minute recess of 0.10 μm to 5 μm.
According to this, the solid lubricant film is filled in the minute recess formed on the surface of the separator, and the solid lubricant film is further closely adhered to the surface. Here, if the surface micro-dent is less than 0.10 μm, the solid lubricant film is not formed in close contact with the surface, whereas if it exceeds 5 μm, the effect obtained by the micro-indentation is saturated.

Furthermore, in the linear motion device separator according to the present invention, the solid lubricant film may be formed on a surface having an arithmetic average roughness (Ra) defined in JIS B 0601 of 0.10 μm or more and 0.50 μm. preferable.
Furthermore, in the linear motion device separator according to the present invention, in order to make it easier to hold the lubricant, to easily apply an elastic preload to the rolling element during assembly, and to obtain a centering effect on the rolling element of the separator, It is preferable to form a lip portion in contact with the rolling element on the outer peripheral edge of the holding surface of the separator.

  In the present invention, the area ratio of the solid lubricant forming the solid lubricant film refers to the area ratio when the solid lubricant is present on the entire surface of the formed solid lubricant film as 100%. For example, a solid lubricant film in which 75% of the solid lubricant is present in area ratio means that the solid lubricant is present in 75% of the surface of the formed solid lubricant film, and the solid lubricant is formed in the remaining 25%. Without a hole.

  Further, the solid lubricant forming the solid lubricant film in the present invention is not particularly limited as long as it has a required strength on the surface of the separator and has good adhesion to the surface. For example, molybdenum disulfide, polyethylene, fluororesin, nylon, polyacetal, polyolefin, polyester, PTFE (polytetrafluoroethylene), metal soap, tungsten disulfide, boron nitride, graphite, calcium fluoride, barium fluoride, tin, tin Alloys, metal oxides, copper, copper alloys, iron, iron alloys, aluminum, aluminum alloys, zinc, zinc alloys and the like can be mentioned.

  Further, the method for forming the solid lubricant film in the present invention is not particularly limited. For example, a method for forming the solid lubricant film by shot peening processing in which the solid lubricant is spray-fixed on the surface as a shot material, or a solid lubricant A solid lubricating film is formed by plastic deformation of the material, and a solid lubricant and a thermoplastic resin such as paraffin wax are kneaded at a high temperature to obtain a semi-molten liquid, followed by firing to obtain a solid lubricant. The method of forming a film is mentioned. In particular, it is preferable to use shot peening in order to form a solid lubricating coating on the surface more closely.

Furthermore, the method for forming the micro-indentation on the surface in the present invention is not particularly limited. For example, the micro-indentation is formed by transferring using a mold in which the micro-indentation is formed in advance when the separator is manufactured. Alternatively, after forming the separator, a minute recess may be formed by shot peening, barrel processing, or laser processing.
Furthermore, the material of the separator in the present invention is not particularly limited, and examples thereof include resins such as nylon 66, nylon 46, PPS (polyphenyl sulfide), and PEEK (polyether ether ketone).

  The present invention also includes a first member and a second member having raceway surfaces arranged to face each other, a plurality of rolling elements arranged to be freely rollable between the first member and the second member, A separator interposed between a plurality of rolling elements and having a holding surface that receives the rolling surface of the rolling element on a surface facing the rolling element, and the rolling element rolls to form the first In the linear motion device in which one of the member and the second member linearly moves relative to the other, the separator is a linear motion device separator according to the present invention. .

According to the linear motion device separator of the present invention, the solid lubricant film is formed in close contact by forming a solid lubricant film having a solid lubricant of 75% or more in area ratio on at least the surface forming the holding surface. Therefore, it is difficult to cause wear on the rolling surface of the rolling element held on the surface.
Therefore, the separator for linear motion device of the present invention is used under a condition in which an oil film is difficult to be formed by interposing between a plurality of rolling elements arranged between the first member and the second member of the linear motion device. Even in this case, since it is difficult for the rolling surface of the rolling element to be worn, durability required for the linear motion device can be obtained.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing an example of a linear motion device separator according to the present invention.
The separator 1 has a substantially cylindrical shape, and concave surfaces (holding surfaces) 1 a that hold the surface (rolling surface) of the ball (rolling body) 2 are formed on both bottom surfaces of the column. The concave surface 1a has a Gothic arch shape in which the radius r of the ball 2 to be held has a large curvature radius R. By having such a concave surface 1a, the thickness t of the central portion becomes smaller with respect to the maximum length L of the column forming the separator 1, so that a plurality of balls 2 can be arranged and the ball 2 and the separator 1 The contact area is reduced, and sliding resistance can be reduced.

  On the entire surface including the concave surface 1a of the separator 1, minute depressions (dimples) having a depth of 0.10 to 5 μm are formed, and the arithmetic average roughness (Ra) of the entire surface is 0.10 to 0.10. 0.50 μm. A solid lubricating film 1A having molybdenum disulfide (solid lubricant) having an area ratio of 75% or more is formed on the entire surface including the concave surface 1a of the separator 1 with a thickness of 0.10 to 8 μm.

According to the separator 1 of the present embodiment, since the solid lubricating film 1A having a solid lubricant with a predetermined area ratio is formed on the entire surface including the concave surface 1a, a short stroke reciprocating motion is performed under high temperature and high load. Even when it is incorporated in a linear motion device that is used under conditions where an oil film is difficult to be formed, wear on the surface of the ball 2 held by the concave surface 1a can be made difficult to occur.
As a linear motion apparatus incorporating this separator 1, what is shown in FIGS. 2-6 is mentioned.

FIG. 2 is a front view showing an example of a ball screw as the linear motion device according to the present invention. 3 is a cross-sectional view showing a state in which only the nut of the ball screw in FIG. 2 is cut along AA in FIG. FIG. 4 is an enlarged cross-sectional view showing the ball and separator in FIG.
This ball screw 10 includes a screw shaft (first member) 11 having a spiral thread groove (track surface) 11a on the outer peripheral surface and a nut (first member) having a spiral thread groove (track surface) 12a on the inner peripheral surface. 2 members) 12 and these thread grooves 11a
, 12a, a plurality of balls (rolling elements) 2 disposed so as to be freely rollable on a ball rolling path formed between the two balls 12a, and a plurality of separators 1 interposed between the balls 2.

Further, a notch 12 </ b> A is provided on the outer peripheral surface of the nut 12. A return tube 13 for circulating the ball from one end side to the other end side of the ball rolling path is fixed to the notch portion 12A by a tube presser 14.
Furthermore, a flange 15 for fixing the nut 12 to a table or the like is provided at one axial end of the nut 12. Further, the dust 15 is sealed between the flange 15 and the screw shaft 11 and between the other axial end of the nut 12 and the screw shaft 11. As the ball 2 rolls, the nut 12 moves linearly relative to the screw shaft 11.

FIG. 5 is a partial cross-sectional perspective view showing an example of a linear guide as the linear motion device according to the present invention.
The linear guide 20 has a guide rail (first member) 21 having a substantially rectangular cross section and a slider (second member) that is movable in the longitudinal direction of the guide rail 21 and has a substantially U-shaped cross section. 22 and a plurality of balls (rolling elements) that are arranged to be freely rollable on a ball rolling path formed by a ball rolling groove 21 a provided on the guide rail 21 and a ball rolling groove 22 a provided on the slider 22. ) 2 and a plurality of separators 1 interposed between the balls 2.

  Further, end caps 23 are detachably provided on the slider 22 at both ends in the axial direction by end cap fixing bolts 23a. A ball return path for circulating the ball 2 from one end side to the other end side of the ball rolling path is provided in the end cap 23, and the ball return path is provided through a substantially U-shaped ball passage hole. It is connected to the ball rolling path. As the ball 2 rolls, the slider 22 moves linearly relative to the guide rail 21.

FIG. 6 is a front view showing an example of a linear ball bearing as the linear motion device according to the present invention.
The linear ball bearing 30 is used by being externally fitted to a linear shaft (first member) 31, and is an outer cylinder (second member) 32 and a cylinder fixed to the inner peripheral surface of the outer cylinder 32 by a retaining ring 33. -Shaped cage 34, a plurality of balls (rolling elements) 2 that are arranged in a freely rolling manner in ball rolling grooves provided in an oval shape extending in the axial direction on the circumferential surface of cage 34, and these balls A plurality of separators 1 interposed between the two.

The ball rolling groove on the inner peripheral surface side of the cage 34 is provided with a notch 34a, and the ball 2 exists in a state of projecting from the inner peripheral surface of the cage 34 at the notch 34a. To do. As the ball 2 rolls, the outer cylinder 32 moves linearly relative to the linear shaft 31.
By incorporating the separator 1 described above into these linear motion devices 10, 20, and 30, the surface of the ball 2 held by the concave surface 1 a of the separator 1 as compared with the case where the solid lubricant film 1 A is not formed on the surface of the separator 1. Wear is less likely to occur. Therefore, durability required for the linear motion device can be obtained even when used under conditions in which an oil film is difficult to be formed, such as reciprocating a short stroke under high temperature and high load.

Hereinafter, the results of verifying the effects of the present invention based on examples will be described.
In this embodiment, a ball screw (screw shaft diameter: 25 mm, lead: 10 mm, screw shaft total length: 500 mm, ball diameter: 4.762 mm) having a nominal number C5 defined in JISB 1192 is shown in the following procedure. It was made with.
In this embodiment, four types of separators A to D were produced by the following procedure. The separators A to D have the same configuration as the separator 1 described above, and the outer diameter thereof is 0.8 times the diameter of the rolling element.

The separator A was first processed into the shape of a separator using a material made of nylon 66. Next, dimples were formed on the entire surface including the concave surface by barrel processing, and then a solid lubricant film was formed by shot peening.
The separator B was manufactured by forming a solid lubricating film directly by shot peening without forming dimples on the entire surface including the concave surface after processing into a predetermined shape in the same manner as the separator A.

The separator C was manufactured by forming dimples by barrel processing on the entire surface including the concave surface after processing into a predetermined shape like the separator A.
The separator D was fabricated without forming dimples or solid lubricant coatings on the entire surface including the concave surface after processing into a predetermined shape in the same manner as the separator A.
The barrel processing for forming the dimples was performed by using SiC as an abrasive. Moreover, the shot peening process for forming a solid lubricating coating was performed by injecting molybdenum disulfide as a shot material under an injection pressure of 0.2 to 0.5 MPa and an injection time of 5 to 15 minutes.

The area ratio of the solid lubricant forming the solid lubricating film and the thickness of the solid lubricating film were measured using the separator destructive inspection sample thus obtained.
Here, the area ratio of the lubricant forming the solid lubricant film was measured by the following procedure. First, using EPMA (Electron Probe Microanalyzer), the surface of the separator was observed for 2000 fields at 2000 times. Next, the 200 μm square of the surface of the separator is enlarged 1000 times, and the solid lubricant is present in the portion where the X-ray intensity 10 times or more of the element characteristic X-ray intensity before the solid lubricant film is formed is detected. Judged as an area. Then, the results for 30 fields of view were subjected to image analysis, and the average value of the area ratio of the solid lubricant forming the solid lubricant film was calculated. The results are shown in Table 1.

  Moreover, the thickness of the solid lubricating coating was measured by the following procedure. First, the separator was cut, and the cut surface was surface-finished by buffing, and then observed for 30 fields of view at 5000 times using an electron microscope. At this time, in each field of view, the separator is arranged so that the cross-sectional layer of the solid lubricant film is observed in the lateral direction, and divided into six sections along the vertical direction (thickness direction of the solid lubricant film), The film thickness of each section was calculated. And the average film thickness of 30 visual fields was computed using the average film thickness of 1 visual field calculated from the average value of the film thickness of 6 sections, and this result was combined with Table 1 and shown.

Similarly, the dimple depth and the arithmetic average roughness (Ra) of the surface after barrel processing were measured using the obtained sample for destructive inspection of the separator.
Here, the dimple depth on the surface after barrel processing was measured by the following procedure. First, using a three-dimensional non-contact surface shape measuring instrument, observation was performed for 30 fields of view at 100 times. Next, the obtained image was converted into a cross-sectional profile, and five cross-sections in the XY directions were observed. The results are shown in Table 1 as average values. Moreover, the arithmetic mean roughness (Ra) of the surface after barrel processing was measured with the well-known roughness measuring machine.

In the present embodiment, a screw shaft and a nut were produced by the following procedure.
First, after processing a material made of SCM435 (alloy steel for mechanical structure) into a predetermined shape, in a furnace in which a mixed gas (Rx gas + enrich gas + ammonia gas) is introduced, it is 920-940 ° C. for 4-6 hours. Carbonitriding by heating and holding, oil quenching, and tempering by heating and holding at 160 to 320 ° C. for 2 hours were performed. Thereby, in the surface layer portion (portion from the surface to 50 μm) forming the screw shaft and the screw groove of the nut, the amount of retained austenite was set to 15 to 40% by volume, and the hardness was set to HRC 62 to 67 (Hv 746 to 900).

In the present embodiment, a ball was manufactured according to the following procedure.
First, a material composed of two types of high carbon chromium bearing steel (SUJ2) is processed into a predetermined shape, and then heated and maintained at 840 ° C. for 3 hours in a furnace in which a mixed gas (RX gas + enrich gas + ammonia gas) is introduced. The carbonitriding process by performing, the oil quenching process, and the tempering process by heat-maintaining at 180-200 degreeC for 2 hours were given, and the roughing was performed. Thereby, in the surface layer portion (portion from the surface to 50 μm) forming the rolling surface of the ball, the amount of retained austenite was 15 to 40% and the hardness was HRC 62 to 67 (Hv 746 to 900). Next, tumbling was performed on the rolling surface of the ball, and finishing was performed until it corresponded to grade G20 defined by JIS.

  The ball screw was assembled using the ball screw, nut, ball, and separator life test sample thus obtained. At this time, when it is assumed that the total clearance in the ball rolling path is larger than 0 and one separator corresponding to the tail is removed, the clearance between the leading ball and the trailing ball is the outer diameter of the separator. It was set to be smaller than 0.8 times the size.

And the life test of the ball screw was done by operating this ball screw on the conditions where an oil film is hard to be formed as shown below (oil film parameter is 3 or less). This life test is performed by operating the ball screw with an upper limit of three times the theoretical life time. When the nut test temperature rises by 10 ° C compared to the initial temperature, or the vibration value is compared with the initial vibration value. The ball screw operation was stopped when it reached 3 times or more. The time until the operation of the ball screw was stopped was measured as the lifetime. Moreover, in this life test, it carried out 10 times in each Example, and calculated L10 life based on the Weibull distribution function. Then, this result was obtained from No. 1 using the separator D. The results are shown in Table 1, with the ratio of 25 as 1.
<Life test conditions>
Testing machine: NSK Ltd. Ball screw durability life testing machine Load: Axial load 5800N (P / C = 0.5)
Rotational speed: 200min ^-1
Stroke: 60mm
Lubricant: Mineral oil based grease Test temperature: 100 ° C

As shown in Table 1, No. 1 in which a solid lubricant film having a solid lubricant of 75% or more in area ratio was formed on the surface of the separator. 1-No. 24, No. 25-No. Compared to 30, the life was longer.
No. 1-No. 24, in which a solid lubricating film is formed on the surface having dimples. 9-No. 16 and no. 19-No. In 24, the lifetime was particularly long.
No. 1-No. 6 and no. Nos. 7 and 8 and No. 9-No. 15 and No. From the result of 16, it can be seen that the lifetime is particularly long when the area ratio of the solid lubricant forming the solid lubricant film is 95% or less.

Furthermore, no. 3 and no. 17 and 18 and No. 11 and no. From the results of 19 and 20, it can be seen that the lifetime is increased by setting the thickness of the solid lubricating coating to 0.10 to 8 μm.
Furthermore, no. 11 and no. From the results of 21 and 22, it can be seen that the lifetime is further extended by setting the depth of the dimple on the surface on which the solid lubricant film is formed to 0.10 to 5 μm.
Furthermore, no. 11 and no. From the results of Nos. 23 and 24, it can be seen that the lifetime becomes longer when the arithmetic average roughness (Ra) of the surface on which the solid lubricant film is formed is 0.10 to 0.50 μm.

Of the results shown in Table 1, No. 1-No. No. 16 result and no. 27-No. Based on the results of 30, the graph of FIG. 7 showing the relationship between the area ratio of the solid lubricant forming the solid lubricant film formed on the surface of the separator and the life of the ball screw was prepared.
From the graph of FIG. 7, by forming a solid lubricant film having a solid lubricant of 75% or more in area ratio on the surface of the separator, It can be seen that a life of 6.5 times longer than 25 is obtained. In addition, by forming a solid lubricant film having a solid lubricant with an area ratio of 75% or more on the surface having dimples having a depth of 0.10 to 5 μm, No. 1 is obtained. It can be seen that a lifetime of 8.5 times 25 or more is obtained.
From the above results, even when the oil film is used under a condition in which an oil film is difficult to be formed by using a separator in which a solid lubricant film having a solid lubricant of 75% or more in area ratio is formed on the entire surface, It was confirmed that the life of the ball screw can be extended.

It is sectional drawing which shows an example of the separator for linear motion apparatuses which concerns on this invention. It is a front view which shows an example of a ball screw as a linear motion apparatus which concerns on this invention. It is AA sectional drawing in FIG. It is an expanded sectional view which shows the ball | bowl and separator in FIG. It is a partial cross section perspective view which shows an example of a linear guide as a linear motion apparatus which concerns on this invention. It is a perspective view which shows an example of a linear ball bearing as a linear motion apparatus which concerns on this invention. It is a graph which shows the relationship between the area ratio of the solid lubricant which forms the solid lubricant film formed in the surface of a separator, and the lifetime of a ball screw.

Explanation of symbols

1 Separator 1a Concave surface (holding surface)
1A Solid lubricant film 2 Ball (rolling element)
10 Ball screw (linear motion device)
11 Screw shaft (first member)
12 Nut (second member)
20 Linear guide (linear motion device)
21 Guide rail (first member)
22 Slider (second member)
30 Linear ball bearing (linear motion device)
31 Linear shaft (first member)
32 Outer cylinder (second member)
33 Retaining Ring 34 Cage

Claims (6)

A rolling surface of the rolling element is interposed between a plurality of rolling elements that are rotatably arranged between a first member and a second member having raceway surfaces that face each other. In the linear motion separator having a holding surface for holding
A separator for a linear motion device, wherein a solid lubricant film having a solid lubricant of 75% or more in area ratio is formed on at least a surface forming a holding surface.   2. The linear motion device separator according to claim 1, wherein the solid lubricant film has a solid lubricant of 95% or less in area ratio.   3. The linear motion device separator according to claim 1, wherein the solid lubricant film is formed with a thickness of 0.10 μm to 8 μm.   The separator for a linear motion device according to any one of claims 1 to 3, wherein the solid lubricating coating is formed on a surface having a minute recess of 0.10 µm to 5 µm.   5. The linear motion device according to claim 1, wherein the solid lubricant film is formed on a surface having an arithmetic average roughness (Ra) of 0.10 μm or more and 0.50 μm. Separator. Between the plurality of rolling elements, a first member and a second member having raceway surfaces arranged to face each other, a plurality of rolling elements arranged to be freely rollable between the first member and the second member, and And a separator having a holding surface that holds a rolling surface of the rolling element, and when the rolling element rolls, one of the first member and the second member becomes the other. In a linear motion device that moves relatively linearly,
The said separator is a separator for linear motion apparatuses of any one of Claims 1-5, The linear motion apparatus characterized by the above-mentioned.

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