JPWO2013118202A1 - Rolling bearing and film transport device - Google Patents

Abstract

Lubricant in an amount of 1.0 g or more and 10 g or less per 1 m 2 of the total surface area is applied to the raceway surfaces of the inner ring (1) and outer ring (2) of the rolling bearing and the rolling surface of the ball (3). The cage (4) is formed by injection molding a resin composition containing ETFE (tetrafluoroethylene-ethylene copolymer) as a main component and containing a fibrous filler. The guide type of the cage (4) is referred to as rolling element guide.

Description

  The present invention relates to a rolling bearing having an inner ring, an outer ring, a plurality of rolling elements, and a cage, and particularly suitable for use in supporting a rotating shaft of a driven roller that rotates by a frictional force with a film in a film conveying device. About.

  The film is used as a material for an FPD (flat panel display) or a solar cell. In these applications, it is possible to exert functions of light emission and power generation by laminating films made of different materials. Therefore, the development of a thin film has been carried out, and a film having a thickness of several tens of μm actually exists. If the thickness or length of the film is uneven, problems occur during lamination, causing defective products.

FIG. 11 is a perspective view showing a part of the film transport apparatus. As shown in this figure, in the film transport apparatus 73, the film 70 is supported and transported by a large number of transport rollers 71 arranged in parallel to each other. These transport rollers 71 rotate around a rotation shaft, and a rolling bearing 72 is attached to each rotation shaft.
The conveyance roller 71 includes a driving roller that applies a driving force to the film 70 and a driven roller that rotates by a frictional force generated between the moving film 70. There are more follower rollers than drive rollers. The driven roller is arranged to smoothly convey the film 70 by changing the relative position of the front and rear rollers to change the angle in the vertical direction of the film surface.

  It is important that the driven roller is rotated only by the frictional force with the film 70 and the peripheral speed of the roller surface is the same as the traveling speed of the film 70. Therefore, the driven roller needs to start rotating with an extremely small force applied from the film 70 in the tangential direction of the driven roller, and needs to continue to rotate stably. Therefore, the rolling bearing 72 that supports the rotating shaft of the driven roller is required to have low dynamic friction torque and high durability.

Deep groove ball bearings equipped with corrugated cages are widely used as rolling bearings, but because of their high dynamic friction torque, they are not suitable as rolling bearings 72 for this application.
Patent Document 1 describes a bearing ring guide type cage that is made of synthetic resin, is formed in an annular shape, and includes a plurality of pocket portions that hold a plurality of rolling elements one by one in the circumferential direction. Yes. It is described that the torque of the rolling bearing is suppressed by devising the shape of the pocket portion.

  Specifically, an elliptical inner peripheral surface (first inner peripheral surface) is provided on the radially inner end edge of the pocket portion formed of the cylindrical inner peripheral surface. This elliptical inner peripheral surface is formed as a strength reinforcing part to reduce the torsion of the cage during high-speed rotation and prevent the cage and rolling elements from sliding unnecessarily, thereby suppressing an increase in torque. ing. Since the rotating shaft of the driven roller of the film conveying device is a low-speed rotation of several tens to several hundreds per minute, it is useful even if the cage of Patent Document 1 is used as a cage for a rolling bearing for this application. There is no effect.

On the other hand, rolling bearings are used by being lubricated with a lubricant. However, since the lubricant generates stirring resistance with the rotation of the bearing, the amount of the lubricant used can be reduced to a minimum (a small amount of lubrication). The dynamic friction torque can be lowered. With regard to such a small amount of lubrication, for example, Patent Document 2 describes that the thickness of the lubricating coating is 1 to 10 g / m ² .
Patent Document 3 describes that a rolling bearing retainer is formed by injection molding of a resin composition containing ETFE (tetrafluoroethylene-ethylene copolymer) as a main component and a fibrous filler. ing.

JP 2007-56930 A JP 2009-18929 A JP 2011-169466 A

  An object of the present invention is to provide a rolling bearing having a dynamic friction torque reduced as compared with a conventional rolling bearing.

In order to solve the above problems, a rolling bearing according to an aspect of the present invention is a rolling bearing having an inner ring, an outer ring, a plurality of rolling elements, and an annular cage, and the cage is an ETFE (tetra Fluoroethylene-ethylene copolymer) as a main component and formed by injection molding a resin composition containing a fibrous filler, and the guide type of the cage is rolling element guide, The inner ring and outer ring raceway surfaces and the rolling surfaces of the rolling elements are coated with a lubricant in an amount of 1.0 g to 10 g per 1 m ² of the total surface area.

According to the rolling bearing of this aspect, an amount of 1.0 g or more and 10 g or less (preferably 4.0 g or less) per 1 m ² of the total surface area on the raceway surfaces of the inner and outer rings and the rolling surface of the rolling element. Thus, the torque can be kept low.
In addition, since the cage is made of a resin composition containing ETFE (tetrafluoroethylene-ethylene copolymer) as a main component and a fibrous filler, the cage is made of a resin composition containing polyamide as a main component. Compared to this, the dynamic friction torque of the rolling bearing under a minute amount of lubrication can be reduced. Polyamide has been conventionally used as a material for cages made of synthetic resin.

  In other words, since ETFE is excellent in water repellency, in a cage mainly made of ETFE, the lubricant adhering to the rolling element in the pocket under a small amount of lubrication does not transfer to the pocket, and the rolling element The state where the lubricant is adhered is maintained. As a result, since the rolling element and the pocket surface are kept in a non-contact state, the frictional resistance between the rolling element and the cage under a small amount of lubrication is reduced.

In addition, since the cage is formed by injection molding a resin composition containing ETFE as a main component, a cage formed by a method other than injection molding using the same resin composition; In comparison, the dynamic friction torque of the rolling bearing can be reduced.
That is, in the injection molding, since the resin flows along the surface of the mold and is molded, the surface layer portion (skin layer) of the molded product is formed in a layer shape along the flow of the resin. Moreover, the longitudinal direction of the fibrous filler contained in the resin composition extends along the skin layer, and is arranged in parallel without being entangled with each other. Therefore, in the rolling bearing of this aspect, the frictional resistance accompanying sliding between the pocket of the cage and the rolling element is reduced.

On the other hand, in the cage obtained by cutting from the compression molding material of the same resin composition, the cross section of the resin flow and the cross section of the fibrous filler are exposed on the pocket surface of the cage. The frictional resistance associated with the sliding between the pocket and the rolling element increases. Further, as a method for producing a cage made of synthetic resin, cutting is difficult and injection molding is suitable.
In addition, since the cage guide type is a rolling element guide, the cage and the inner ring and the outer ring do not slide (the frictional resistance between them becomes zero), so that the cage ring guide is compared with the case of the raceway guide. This reduces the dynamic friction torque of the rolling bearing.

If the rolling bearing of this aspect has a number of rolling elements corresponding to 70% or more and 90% or less of the maximum number, the dynamic friction torque can be further reduced as compared with rolling bearings having other numbers of rolling elements. it can.
The maximum number of rolling elements that a rolling bearing can have is determined by the dimensions of the inner ring and outer ring to be combined. Moreover, the number of rolling elements which a normal rolling bearing has is the maximum number. The reason is that the larger the number of rolling elements, the more easily the load applied to the rolling bearing is dispersed, which is advantageous in improving the life of the bearing due to metal fatigue.

  On the other hand, the smaller the number of rolling elements, the smaller the number of elastic deformations of the inner ring and outer ring due to the passage of the rolling elements, so the dynamic friction torque of the rolling bearing decreases. However, if the number of rolling elements is too small and the rolling element row becomes a polygon that cannot be approximated to a circle, the rotational performance of the rolling bearing is affected. When the number of rolling elements is a number corresponding to 70% or more and 90% or less of the maximum number, the rotational performance of the rolling bearing can be satisfactorily maintained while reducing the dynamic friction torque.

Further, as a rolling bearing for supporting the rotating shaft of a driven roller that rotates by a frictional force with a film in a film conveying device, when the bearing inner diameter is d, the bearing outer diameter is D, and the bearing width is t, the following (1 In many cases, thin-walled bearings satisfying the formula (radial bearings having a dimension series of 08 and 09) are used.
((D−d) / 2) /t≦1.07 (1)

  This thin bearing has a smaller outer diameter when the inner diameter is the same as that of the rolling bearing that does not satisfy the formula (1). Therefore, the bearing box can be made small. Further, in a film transport apparatus having a large number of driven rollers, adjacent driven rollers can be arranged closer to each other. Therefore, the installation area of the entire film transport apparatus can be reduced by using a thin bearing that satisfies the above equation (1) as the rolling bearing that supports the rotating shaft of the driven roller of the film transport apparatus.

  Further, this thin bearing has a narrow inner diameter space in comparison with a rolling bearing that does not satisfy the formula (1), so that the diameter of the rolling elements arranged is small and the maximum number of rolling elements is large. Therefore, even if the reduction number from the maximum number of rolling elements is increased, the rotational performance of the rolling bearing is hardly affected. Therefore, when the rolling bearing of this aspect has the number of rolling elements corresponding to 70% or more and 90% or less of the maximum number, the deterioration of the rotational performance of the rolling bearing can be suppressed by satisfying the expression (1). .

The rolling bearing of this aspect is suitable for an application for supporting the rotating shaft of a driven roller that rotates by a frictional force with a film in a film conveying device. Examples of the film transport apparatus include those having the following configurations (a) and (b).
(a) A plurality of conveyance rollers that are arranged in parallel to each other and convey the film while supporting it, and a rolling bearing that supports the rotation shaft of the conveyance roller.
(b) The conveying roller includes a driving roller that applies a driving force to the film, and a driven roller that rotates by a frictional force generated between the moving film.
In addition, it is useful to provide the rolling bearing of this aspect as a rolling bearing that supports the driven roller of the film transport apparatus having the above-described configurations (a) and (b) because of the advantages described above.

  According to the present invention, there is provided a rolling bearing having a dynamic friction torque reduced as compared with a conventional rolling bearing.

It is sectional drawing which shows the rolling bearing of embodiment. It is a front view which shows the holder | retainer which comprises the rolling bearing of FIG. It is a schematic block diagram which shows the test apparatus for tangential force measurement used in the Example. It is a graph which shows an example of the relationship between a dynamic friction torque value and the rotation time of a measured value. It is a graph which shows the result of the test which investigated the dynamic friction torque in the reference example, Comprising: A vertical axis | shaft is a nominal value of the dynamic friction torque value at the time of 15-minute progress, and a horizontal axis is the fluctuation amount of the torque value. . It is a graph which shows the result of the test which investigated the dynamic friction torque in Example 1, Comprising: A vertical axis | shaft is a nominal value of the dynamic friction torque value at the time of 15-minute progress, and a horizontal axis is the fluctuation amount of the same torque value. is there. It is a schematic block diagram which shows the test apparatus for particle measurement used in the Example. 6 is a graph showing the results of particle measurement performed in Example 1. It is a graph which shows the result of the test which investigated the dynamic friction torque in Example 2, Comprising: A vertical axis | shaft is a nominal value of the dynamic friction torque value at the time of 15-minute progress, and a horizontal axis is a fluctuation amount of the same torque value. is there. It is a graph which shows the result of the particle measurement performed in Example 2. FIG. It is a perspective view which shows a part of film transport apparatus.

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.
Drawing 1 is a sectional view showing the rolling bearing of an embodiment.
The rolling bearing of this embodiment includes an inner ring 1, an outer ring 2, 15 balls (rolling elements) 3, a crown-shaped cage 4, and a shield plate 5. The maximum number of balls 3 in this rolling bearing is 21.

  An inner ring raceway groove (inner ring raceway surface) 12 is formed in the axially central portion of the outer circumferential surface 11 of the inner ring 1. Both end portions 13 in the axial direction of the outer peripheral surface 11 of the inner ring 1 are formed in small diameter portions having dimensions corresponding to the center holes 51 of the shield plate 5. An outer ring raceway groove (outer ring raceway surface) 22 is formed in the axially central portion of the inner peripheral surface 21 of the outer ring 2. Mounting grooves 23 for the shield plate 5 are formed at both axial ends of the inner peripheral surface 21 of the outer ring 2.

The inner ring 1, the outer ring 2 and the ball 3 are made by a normal method using a material made of SUJ2 or SUS440C.
The inner ring raceway groove 12, the outer ring raceway groove 22 and the surface (rolling surface) of the ball 3 are coated with an amount of lubricant of 1.0 g or more and 10 g or less per 1 m ² of the total surface area (S). In this way, a small amount of lubricant can be applied by dipping the inner ring raceway groove 12, the outer ring raceway groove 22 and the ball 3 in the lubricant and pulling them up, or by lubricating the inner ring raceway groove 12, the outer ring raceway groove 22 and the surface of the ball 3. This can be done by spraying the agent. The actual application amount can be calculated by dividing the mass difference between the rolling bearings before and after applying the lubricant by the total surface area S.

The cage 4 is formed by performing injection molding using a resin composition containing ETFE as a main component and containing a fibrous filler (carbon fiber, whisker, or glass fiber).
As shown in FIG. 2, the cage 4 is an annular body including 15 pocket portions 41 at equal intervals in the circumferential direction. Each pocket portion 41 is open at one end in the axial direction of the torus. The opening dimension B of the opening 42 is smaller than the diameter of the ball 3. The ball 3 is inserted into the pocket 41 by elastically deforming the opening 42. Thereby, the ball 3 is held without dropping from the pocket portion 41. Each pocket portion 41 of the cage 4 is composed only of a spherical rolling element holding surface 41 a concentric with the ball 3.

The guide type of the cage 4 is rolling element guidance, and the inner circumferential surface of the cage 4 and the outer circumferential surface 11 of the inner ring 1 do not slide.
The shield plate 5 is obtained by pressing a steel plate made of SPCC or SUS304.
According to the rolling bearing of this embodiment, a small amount of lubrication is performed, and the cage 4 is used as a rolling element guide as an injection-molded product of a resin composition containing ETFE as a main component and a fibrous filler. By setting the number to 15 (71%), which is less than the maximum of 21, the rotational performance can be maintained well while reducing the dynamic friction torque.

  In addition, although this embodiment demonstrated the ball bearing whose rolling element is a ball | bowl, this invention is not limited to a ball bearing, It is applied also to the roller bearing whose rolling element is a cylindrical shape or a conical roller (roller). it can. In the case of a roller bearing, since the rolling surface of the roller is a peripheral surface, the roller end surface is not included in the surface area of the rolling element included in the total surface area.

[Example 1]
In Example 1, the difference in the dynamic friction torque of the rolling bearing and the number of particles generated due to the difference in the material of the cage and the amount of lubricant was examined.
<Dynamic friction torque test>
Using a deep groove ball bearing having a nominal number of 6200 as the rolling bearing of FIG. 1, a test for examining the dynamic friction torque was performed by the following method. The dimensions are a bearing inner diameter d = 10 mm, a bearing outer diameter D = 32 mm, and a bearing width t = 9 mm.
The inner ring 1 and the outer ring 2 are made of SUJ2 and manufactured by a normal method. The ball 3 is made of SUJ2 and produced by a normal method. The number of balls 3 is eight as usual (maximum number). The shield plate 5 is obtained by press forming a steel plate made of SPCC.

  The cage 4 has the same shape as that of FIG. 2, but has 8 pockets, and is made of a resin composition (ETFE: potassium titanate whisker = 90: 10 by mass ratio) composed of ETFE and potassium titanate whiskers. What was obtained by injection molding of a resin composition (mass ratio nylon 66: carbon fiber = 85: 15) obtained from injection molding (cage A) and nylon 66 and carbon fiber (cage C) ) Was prepared.

ETFE: "Fluon ETFE C-55AP" manufactured by Asahi Glass
Potassium titanate whisker: “Tismo” manufactured by Otsuka Chemical, fiber diameter 0.2 μm to 0.6 μm, fiber length 10 μm to 20 μm
Nylon 66: “UBE nylon 66” manufactured by Ube Industries
Carbon fiber: “Kureka chop M-102S” manufactured by Kureha Chemical Industry Co., Ltd., average fiber diameter: 14.5 μm, length: 0.2 mm
As the grease, lithium grease for clean room (“LG2” manufactured by NSK) was prepared.

First, as a reference example, an amount of grease corresponding to 30% by volume of the bearing space was filled, and four bearings using the cages A and B were assembled.
The test apparatus shown in FIG. 3 was tested by attaching two rolling bearings each having the same cage as the test bearing 61. Two bearings with four cages A were attached and the first test was conducted, and the remaining two were attached and the second test was conducted. Similarly, two of the bearings to which four cages B were attached were attached to perform the first test, and the remaining two were attached to perform the second test.

  The test apparatus shown in FIG. 3 is attached to a rotary drive device (not shown), and has a rotary shaft 60 disposed horizontally, a bearing holder 62 disposed between two test bearings 61, a preload spring 63, and one end. It has the thread | yarn 64 fixed to the bearing holder 62, and the force gauge 65 to which the other end of the thread | yarn 64 was fixed. The inner rings of the two test bearings 61 are attached to the rotary shaft 60, and the bearing holder 62 is fitted on the outer ring. A preload load (axial load) is applied to the inner ring by a preload spring 63. The thread 64 extends in a tangential direction from an intermediate point between the outer rings of the two test bearings 61.

  When the inner ring of the test bearing 61 is rotated by the rotation of the rotating shaft 60, the outer ring is rotated due to friction. This accompanying tangential force (tangential load) is measured by a force gauge 65. Since the measured value is the value of the two test bearings 61, one value is calculated by dividing by two. Then, the dynamic friction torque value is calculated by multiplying the measured value of the tangential force by the radius of the bearing holder 62.

  An example of the relationship between the dynamic friction torque value and the rotation time is shown in the graph of FIG. As shown in this graph, the dynamic friction torque value has a swing width. Therefore, the torque performance is compared with a graph in which the vertical value is the nominal value (average value of measured data) of the dynamic friction torque value and the horizontal axis is the amount of runout. In the case of this graph, the smaller the nominal value and the fluctuation width of the dynamic friction torque value, the closer the plot position is to the lower left corner.

The normal value of the dynamic friction torque value (converted value from the tangential force) at the time when the rotating shaft 60 is rotated in one direction at room temperature, normal pressure, and a rotational speed of 150 min ⁻¹ and 15 minutes have elapsed, and The amount of deflection (b in FIG. 4) was examined, and the result is shown in the graph of FIG. The load conditions are a preload load (axial load) of 88.2 N (9 kgf) by the preload spring 63 and a load (radial load) by the weight of the housing.

  As shown in the graph of FIG. 5, a bearing provided with a cage A (main material ETFE) indicated by a plot “◯” and a bearing provided with a cage B (main material nylon 66) indicated by a plot “Δ”. There was no significant difference in the dynamic friction torque value. This is probably because the agitation resistance of the lubricant becomes the main factor of the dynamic friction torque due to the presence of a large amount of lubricant in the bearing space, and the difference in the material of the cage and the lubrication state in the pocket has little effect. .

Next, the cage A is used to apply grease in an amount of 1.0 g, 10.0 g, and 11.0 g per 1 m ² of the total surface area of the inner ring raceway groove 12, outer ring raceway groove 22, and ball 3. Then, two bearings were assembled. Further, using the cage B, grease of an amount of 1.0 g and 10.0 g per 1 m ² of the total surface area is applied to the surfaces of the inner ring raceway groove 12, the outer ring raceway groove 22 and the ball 3. Individual bearings were assembled.

As in the case of the reference example, these bearings were tested on the test apparatus shown in FIG. 3 by attaching two rolling bearings having the same cage as the test bearing 61 and examining the dynamic friction torque of the test bearing 61. . Except for the amount of lubricant, the test was performed under the same conditions as in the reference example. The results are shown in the graph of FIG.
As shown in the graph of FIG. 6, when the amount of lubricant applied is the same, the plot of the bearing provided with the cage A (ETFE cage: main material is ETFE) shows the cage B (PA cage: main material is From the plot of the bearing with nylon 66), it is closer to the lower left corner. That is, it can be seen that the dynamic friction torque value under a minute amount of lubrication can be reduced by using ETFE as the main material of the cage, compared with the case of using nylon 66.

Slight Further, in the bearing having a retainer A, the coating amount of the lubricant in comparison to the case of 10.0 g / m ² and 11.0 g / m ^2, the difference in coating amount of 1.0 g / m ² In spite of the amount, the nominal value of the dynamic friction torque is significantly larger in the bearing of the application amount of 11.0 g / m ^{2 than in} the bearing of the application amount of 10.0 g / m ² . From this result, it can be said that 10.0 g per 1 m ² of the total surface area of the inner ring raceway groove 12, the outer ring raceway groove 22, and the ball 3 is the upper limit value that can reduce the dynamic friction torque value under a minute amount of lubrication. it can.

<Particle number measurement>
Using cage A, grease of an amount of 0.75 g, 1.0 g, and 10.0 g per 1 m ² of the total surface area of the inner ring raceway groove 12, outer ring raceway groove 22, and ball 3 (Nippon Seiko “ LG2 ") was applied to assemble one bearing each.
These bearings were attached as the test bearing 81 of the particle measuring apparatus shown in FIG. 7, and the number of particles generated by the rotation of the test bearing 81 was measured.
7 includes a rotating body 82 fitted into the inner ring of the test bearing 81, a rotating shaft 83 having one end fixed to the rotating body 82 with a bolt, a housing 84 of the test bearing 81, and a test bearing 81. An annular body 85 and a spring 86 for applying an axial load to the outer ring are provided.

A cylindrical protrusion 821 of the rotating body 82 is fitted on an annular portion 831 formed at one end of the rotating shaft 83. The other end side of the rotating shaft 83 is connected to a motor 83b through a coupling 83a. The rotating shaft 83 is horizontally disposed and is rotatably attached to the housing 88 by support bearings 87 disposed at two positions in the longitudinal direction.
The test bearing 81 is present in the sealed space 9 formed by the cylinder 91 made of acrylic, the front plate 92, and the partition plate 93. A clean air introduction port 94 and a discharge port 95 are formed in the front plate 92 of the sealed space 9.

  A magnetic seal 89 is disposed between the annular portion 831 of the rotating shaft 83 and the annular body 881 fixed to the housing 88 of the support bearing 87. That is, the magnetic seal 89 seals between the housing 84 of the test bearing 81 and the housing 88 of the support bearing 87. As a result, particles from the support bearing 87 generated as the rotating shaft 83 rotates and particles in the atmosphere passing through the inside of the support bearing 87 and the fitting portion do not enter the sealed space 9. ing.

  Using this device, the rotary shaft 83 is connected with a pipe for introducing clean air (standard air containing no particles) connected to the inlet 94 and a pipe directed to the air inlet of the particle counter connected to the outlet 95. Rotate. At that time, the gas in the sealed space 9 is discharged from the outlet 95 toward the particle counter, and clean air having the same volume as the discharged gas is introduced from the inlet 94.

In this state, the rotating shaft 83 is rotated in one direction under the conditions of normal temperature, normal pressure, an axial load of 29.4 N (3.0 kgf), and a rotational speed of 1700 min ⁻¹ , and ¹ The number of particles per (cubic foot) (thickness of 0.1 μm or less) was continuously measured 5 times. The value with the smallest number among the five measurement results was plotted in the graph of FIG.

  It should be noted that immediately after the start of rotation, the number of particles to be counted increases rapidly as the particles adhering to the rotating portion are scattered, and decreases rapidly when the scattering ends. Therefore, immediately after the start of rotation, the measurement interval is measured about once every hour until 5 hours later. A plurality of plots immediately after the start of the rotation are present at positions close to the horizontal axis “0” in FIG.

As shown in the graph of FIG. 8, the number of particles generated from the bearings with the lubricant application amounts of 1.0 g / m ² and 10.0 g / m ² is from 1 × 10 ⁷ times to 10 × 10 ^{7 There} was no significant change up to ⁷ times, and it was 300 pieces / CF or less. If the number of particles of 0.1 μm or less is 350 / CF or less, it corresponds to class 10 in the standard of FED-STD-209. Therefore, it can be seen that the bearings with the lubricant application amounts of 1.0 g / m ² and 10.0 g / m ² have high cleanliness.

In contrast, if the coating amount of the lubricant is 0.75 g / m ^2, the total number of revolutions exceeds 6 × 10 ⁷ times, since the number of particles generated increases rapidly, the total rotation number 7 × 10 ⁷ times The measurement was finished. This is probably because the amount of lubricant applied was too small and the bearing reached the end of its life due to insufficient lubrication.
From this result, as the amount of lubricant applied, 1.0 g per 1 m ² of the total surface area of the inner ring raceway groove 12, the outer ring raceway groove 22 and the ball 3 is 7 × 10 ⁷ revolutions while reducing the dynamic friction torque value under a small amount of lubrication. It can be said that this is the lower limit for obtaining a bearing life of.

[Example 2]
In Example 2, the difference in the dynamic friction torque of the rolling bearing and the number of particles generated due to the difference in the number of rolling elements was examined.
<Dynamic friction torque test>
Using a deep groove ball bearing having a nominal number of 6812 as the rolling bearing of FIG. 1, a test for examining the dynamic friction torque was performed by the following method. The dimensions are: bearing inner diameter d = 60 mm, bearing outer diameter D = 78 mm, bearing width t = 10 mm, A = ((D−d) / 2) = 9 mm, A / t = 0.9. That is, this rolling bearing satisfies the above formula (1).

  The inner ring 1 and the outer ring 2 are made of SUJ2 and manufactured by a normal method. The ball 3 is made of SUJ2 and produced by a normal method. The number of balls 3 is 21 (maximum number), 20 (95.2% of the maximum number), 19 (90.5% of the maximum number), 18 (85.7% of the maximum number), 17 (81.0% of maximum number), 16 (76.2% of maximum number), 15 (71.4% of maximum number), 14 (66.7% of maximum number), 13 12 types (61.9% of maximum number), 12 (57.1% of maximum number), 11 (52.3% of maximum number), 10 (47.6% of maximum number) . The shield plate 5 is obtained by press forming a steel plate made of SPCC.

  The retainer 4 was obtained by injection molding of a resin composition (ETFE: potassium titanate whisker = 90: 10 by mass ratio) having the shape shown in FIG. 2 and comprising ETFE and potassium titanate whiskers (ETFE retention). Prepared). The same ETFE and potassium titanate whisker as in Example 1 were used.

With respect to 12 types of rolling bearings having different numbers of balls 3, an amount of lubricant (1.0 g and 10.0 g per 1 m ² of the total surface area of the inner ring raceway groove 12, outer ring raceway groove 22 and the surface of the ball 3 ( The same clean room-compatible lithium grease as in Example 1 was applied to assemble two rolling bearings (24 types) having the same configuration. The number of pocket portions 41 of the cage 4 is Z, and in a sample in which the number of balls 3 is smaller than Z, the balls 3 are not put in a part of the pocket portions 41 of the cage 4. At that time, the plurality of balls 3 were arranged evenly in the circumferential direction of the cage 4 as much as possible.

As in the case of the reference example, these bearings were tested on the test apparatus shown in FIG. 3 by attaching two rolling bearings having the same cage as the test bearing 61 and examining the dynamic friction torque of the test bearing 61. .
The nominal value (a in FIG. 4) of the dynamic friction torque value (converted value from the tangential force) at the time when the rotating shaft 60 is rotated in one direction at room temperature, normal pressure, and rotational speed 70 min ⁻¹ and 15 minutes have passed. The results are shown in the graph of FIG. The load conditions are a preload (axial load) of 88.2 N (16 kgf) by the preload spring 63 and a load (radial load) of 4.9 N (500 gf) by the weight of the housing.

As shown in the graph of FIG. 9, as the rolling element loading ratio (ratio when Z is set to 100) decreases, the dynamic friction torque value decreases to about 60%. Yes. The reason for starting to rise is presumed to be that the rotational performance of the rolling bearing decreases with the polygonalization of the rolling element rows.
And although there is a difference in the rolling element loading rate that starts to increase between the case where the lubricant application amount is 1.0 g / m ^{2 and} the case where it is 10.0 g / m ² , the result is that the lubricant application amount is 1 It can be said that setting the rolling element loading rate in the range of 0.0 to 10.0 g / m ² to 70% or more and 90% or less is effective in reducing the dynamic friction torque value.

<Particle number measurement>
The inner ring 1, the outer ring 2, the ball 3, the cage 4, and the shield plate 5 were the same as those used for the dynamic friction torque test.
The number of balls 3 is 21 (maximum number), 19 (90.5% of the maximum number), 17 (81.0% of the maximum number), 15 (71.4% of the maximum number), There were 6 types of 13 pieces (61.9% of the maximum number) and 11 pieces (52.3% of the maximum number).
With respect to six types of rolling bearings having different numbers of balls 3, an amount of lubricant of 1.0 g per 1 m ² of the total surface area of the inner ring raceway groove 12, the outer ring raceway groove 22, and the surface of the ball 3 (Example 1 and The same clean room-compatible lithium grease was applied to assemble two rolling bearings (six types) having the same configuration.

These bearings were attached as the test bearing 81 of the particle measuring apparatus shown in FIG. 7, and the number of particles generated by the rotation of the test bearing 81 was measured by the same method as in Example 1. The test conditions were normal temperature, normal pressure, rotational speeds 70 min ⁻¹ and 300 min ⁻¹ , a preload load (axial load) of 88.2 N (16 kgf) by the preload spring 63 and a load of 4.9 N (500 gf) by the weight of the housing. (Radial load).

After 24 hours from the start of rotation, the number of particles per 1 CF (cubic foot) in the sealed space 9 (particle size of 0.1 μm or less) was continuously measured five times. The value of the smallest number among the five measurement results was plotted in the graph of FIG. 10 for each rotation speed.
As shown in the graph of FIG. 10, in both cases where the rotational speed is 70 min ⁻¹ and 300 min ⁻¹ , the number of particles rapidly increases when the rolling element loading rate becomes smaller than 70%. This is presumed to be due to a decrease in the rotational performance of the rolling bearing accompanying the polygonalization of the rolling element rows. From this result, it can be said that when the application amount of the lubricant is 1.0 g / m ² , a rolling element loading rate of 70% or more is preferable.

DESCRIPTION OF SYMBOLS 1 Inner ring 11 Outer ring surface of inner ring 12 Inner ring raceway groove 2 Outer ring 21 Inner ring surface of outer ring 22 Outer ring raceway groove 23 Mounting groove of shield plate 3 Ball (rolling element)
DESCRIPTION OF SYMBOLS 4 Holder 41 Pocket part 41a Rolling body holding surface 42 Opening part 5 Shield plate 60 Rotating shaft 61 Test bearing 62 Bearing holder 63 Preload spring 64 Thread 65 Force gauge 70 Film 71 Conveying roller 72 Rolling bearing 73 Film conveying apparatus 81 Test bearing 82 Rotating body 821 Cylindrical projection of rotating body 83 Rotating shaft 831 Annular portion of rotating shaft 83a Coupling 83b Motor 84 Housing 85 Annular body 86 Spring 87 Support bearing 88 Housing 881 Annular body 89 Magnetic seal 9 Sealed space 91 Cylindrical body 92 Front plate 93 Partition plate 94 Inlet 95 Outlet

Claims (5)

An inner ring, an outer ring, a plurality of rolling elements, and an annular retainer;
The cage is formed by injection molding a resin composition containing ETFE (tetrafluoroethylene-ethylene copolymer) as a main component and a fibrous filler,
The guide form of the cage is rolling element guide,
A rolling bearing characterized in that a lubricant amount of 1.0 g or more and 10 g or less per 1 m ² of the total surface area is applied to the raceway surfaces of the inner ring and the outer ring and the rolling surfaces of the rolling elements.   The rolling bearing according to claim 1, wherein the number of rolling elements is a number corresponding to 70% to 90% of the maximum number. The rolling bearing according to claim 1 or 2, wherein a bearing inner diameter is d, a bearing outer diameter is D, and a bearing width is t, the following expression (1) is satisfied.
((D−d) / 2) /t≦1.07 (1)   The rolling bearing according to any one of claims 1 to 3, wherein the rolling bearing is used for supporting a rotating shaft of a driven roller that is rotated by a frictional force with a film in a film conveying device.   The film conveying apparatus provided with the rolling bearing as described in any one of Claims 1-3.

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