JP6476377B2 - Rolling device and method of using the same - Google Patents

Description

The present invention relates to the improvement of a rolling device.

In Patent Document 1 and Patent Document 2, a rolling contact element which receives a load from a rolling contact point changing path by forming a rolling contact point changing path in which the contact radius of the rolling element is reduced is formed It is disclosed that the structure of the "autonomous distributed rolling bearing" which forms a space between the succeeding rolling elements and that the competition between the rolling elements can be eliminated.

Further, in Patent Document 3, in the experiment of FIG. 13, by applying a plated film of a fibrous carbon nanomaterial in which SiC particles are attached to a pocket of a retainer of a rolling bearing, a friction force of 10 to 20 N is 14.5 minutes It is stated that it was reduced to about 2.5N. Although it is a short time, it can be understood from the description of the experimental load of 9.8 N that the friction coefficient of the sliding portion is improved from 1 to 2 to 0.25.

Further, in Patent Document 4, the nano rolling element has a function of preventing the initial direct contact between solids on a micron scale in a boundary condition, in which solid portions shearing each other act at boundary conditions; Water containing 5% of 5nBD (bucky diamond, a kind of nano rolling element) showed a surprisingly small μ value (coefficient of friction) of around 0.005 to 0.01. This super-lubrication is held for at least 500 minutes and a sufficient number of It has been disclosed that a spacer has been used. "

Japanese Patent Application Publication No. 2007-177993 JP 2007-192412 A JP, 2013-104533, A Japanese Patent Publication No. 2013-538274 gazette

However, the rolling devices of Patent Documents 1 and 2 eliminate the competition between the rolling elements or between the rolling elements and the cage, and reduce the surface pressure of the rolling contact portion even if lubrication to the outside is unnecessary. For this purpose, it is useful to use a small amount of liquid film indicated by the fluid lubrication theory to the outside. If a large amount of oil or grease is supplied to the rolling device, this problem is solved, but the excess oil or grease is not preferable because it becomes the stirring resistance of the rolling device, and a small amount of liquid film is secured in the rolling contact portion Method is an issue.

Also, when solid lubricants such as the carbon nanomaterials of Patent Document 3 and the nano rolling elements of Patent Document 4 are applied to the sliding surface of a rolling device, low friction can be maintained for a very short time unlike existing oil and grease lubrication. There is a problem. The reason is that solid lubricants do not reform the oil film due to surface tension such as oil lubrication.
The mechanism by which the nano rolling element which is a kind of solid lubricant and is also a rolling element is excluded from the rolling contact portion will be described below.

FIG. 5 shows the main part of a conventional ball bearing. FIG. 5 (A) is a cross-sectional view in the direction perpendicular to the rotation axis, and FIG. 5 (B) is a plan view of the outer ring raceway surface viewed from the inner ring side.
Between the outer ring raceway surface 1 a of the outer ring 1 and the inner ring raceway surface 2 a of the inner ring 2, a millimeter rolling element 3 having a millimeter size is interposed. The millimeter rolling element 3 is rotatably surrounded by a cage 4 so as to avoid direct contact with the adjacent millimeter rolling element. The nano rolling element 5 having a diameter of several nm is mixed with the fluid serving as the dispersing agent at a concentration of several% disclosed in, for example, Patent Document 3, and covers the surface of the raceway surface, the millimeter rolling element, and the cage as a lubricant. ing.

The outer ring raceway surface 1 a and the millimeter rolling element 3 are in contact via the nano rolling element 5 to support a load. The contact ellipse 1b of FIG. 5 (B) indicates this contact range.
In addition, the dimensional ratio of the millimeter rolling element shown to nano rolling element is not correct, and the figure is the drawing which expanded nano rolling element about 1 million times.
Further, in FIG. 5 (B), 1c shows both side ends of the outer ring raceway surface, and the contact ellipse 1b shows a contact area between the outer ring raceway surface 1a and the millimeter rolling element 3. The contact ellipse 1 b is a drawing enlarged about 10 times the width of the outer ring raceway surface.

If the nano rolling element 5 is regarded as a lubricant, the millimeter rolling element 3 is a known bearing that rotates and revolves by the relative rotation of the outer ring 1 and the inner ring 2, but the nano rolling element 5 is regarded as a rolling element performing rolling movement. In this case, it may be understood that a structure in which the millimeter rolling elements 3 and the nano rolling elements 5 are interposed in series between the raceways.
In that understanding, when the outer ring 1 is fixed and the inner ring 2 is rotated in the right direction, the friction coefficient μm of the rolling bearing due to rolling only of the millimeter rolling element 3 and the friction coefficient of the rolling bearing only due to rolling of the nano rolling element 5 If the relationship of μn is μm <μn, the millimeter rolling element 3 performs known rolling motion (revolution in the right direction and rotation around the right), and the nano rolling element 5 does not roll in the illustrated Vn direction ( The action of the nano rolling elements at that time will be described later).

On the contrary, in the case of μm> μn, the millimeter rolling element 3 does not move, and a few nano rolling elements 5a in contact with the millimeter rolling element 3 are sandwiched between the raceway surface 1a and the millimeter rolling element 3 to obtain driving force. It is considered that the trajectory is rolled in the Vn direction shown. However, since the nano rolling elements 5 not in contact with the millimeter rolling elements 3 have no driving force, the nano rolling elements 5 covering the outer ring raceway surface 1 a do not revolve around the track as a whole. Therefore, the density increases and the friction coefficient μn increases and / or spreads in the lateral direction around the nano rolling element 5 pressed by the nano rolling element 5 a which obtains the driving force, and a part 5 b is excluded from the outer ring raceway surface 1 a It will

Practically, the nano rolling element 5 intervenes on the true contact surface (not shown in the figure) in the contact ellipse 1 b between the millimeter rolling element 3 and the raceway surface, and the true contact of the millimeter rolling element 3 and the retainer sliding portion 4 a At the moment when nano rolling elements do not intervene in the surface, etc., when μ m becomes larger than μ n, the nano rolling elements are greatly flowed and lost, and the low friction state is not maintained, the nano rolling elements It is a problem when introduced.

  The present invention uses the difference in the coefficient of friction between the two types of friction in the rolling device, rolling friction and sliding friction in the rolling contact surface, and the former is carried on the rolling motion of the millimeter rolling element, and the latter is nano rolling. An object of the present invention is to allow a nano rolling element to stay on a rolling contact surface without causing a large flow of the nano rolling element by supporting the rolling motion of a moving body, and to maintain a low friction state with a small amount of lubricant for a long time.

The invention according to claim 1 comprises at least one pair of orbits capable of relative movement and a plurality of millimeter rolling elements rollably interposed between the orbits, and the orbits of the rolling mills are partially "Autonomous distributed rolling bearing that creates a space between the millimeter rolling element that receives load from the contact point variation path and the succeeding millimeter rolling element by forming a contact point variation path with a small contact radius The friction coefficient of the rolling bearing by rolling of the millimeter rolling element is μm, and the rolling bearing by rolling of the nano rolling element. When the coefficient of friction is μn, it is characterized in that μm <μn .

Since the consumption of nano rolling elements is reduced, it is possible to provide a rolling device which maintains low friction without replenishing for a long time.

It is an embodiment of a ball bearing. Example 1 It is an example in non-circulation cylindrical roller linear motion guidance. (Example 2) It is a durability evaluation device for ball bearings. (Example 3) It is the endurance evaluation result in a ball bearing. (Example 3) This is a conventional example of a ball bearing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the drawings are for the purpose of illustration only, and do not limit the descriptive scope of the present invention.

FIG. 1 shows the main part of the embodiment of the ball bearing. FIG. 1A is a cross-sectional view of an essential part in a direction perpendicular to the rotation axis, and FIG. 1B is a plan view of the outer ring raceway surface viewed from the inner ring side.
A plurality of millimeter rolling elements 3 (rolling elements of substantially the same size selected from the range of 0.1 mm to 100 mm in diameter) between the outer ring raceway surface 1a of the outer ring 1 and the inner ring raceway surface 2a of the inner ring 2 capable of relative movement The ball of is rolled freely.
A contact angle changing path (not shown in the drawing) described in Patent Document 1 is formed on the outer ring raceway surface 1a, whereby the millimeter rolling element 3 discharged from the contact angle changing path is the same as the succeeding millimeter rolling element 3. A “autonomous distributed rolling bearing” is created to create a gap between the two, and a gap is created between the millimeter rolling element that receives the load out of the contact point change path and the succeeding millimeter rolling element.
Since this embodiment intends a bearing that operates for a long time in a very small amount of liquid film environment, the outer ring 1 and the inner ring 2 are subjected to low temperature black chromium treatment to prevent rust, and the ball as the millimeter rolling element 3 is It uses stainless steel or ceramic or silicon alloy.
The nano rolling element 5 (a quasi-spherical high hardness particle whose particle diameter is distributed in a range of several nm to 20 nm) is mixed with, for example, a fluid serving as a dispersant at a concentration of 0.1% to 10%, and the outer ring raceway surface 1a , The inner ring raceway surface 2 a and the surface of the millimeter rolling element 3.

  The dimensional ratio of the millimeter rolling element 3 and the nano rolling element 5 shown in the drawings is not accurate, and the nano rolling element 5 is enlarged by about one million times the actual size. Further, in FIG. 1 (B), 1c indicates both ends of the outer ring raceway surface, and the contact ellipse 1b indicates a contact area between the outer ring raceway surface 1a and the millimeter rolling element 3. For example, the width of both sides 1c of the outer ring raceway surface of the ball bearing provided with the millimeter rolling element 3 with a diameter of 4 mm is approximately 3 mm, and the size of the contact ellipse 1b under general load is approximately 0.37 mm, an oval radius, and a short circle. The radius is 0.11 mm. Therefore, the contact ellipse 1b in the figure is a drawing enlarged about 10 times the width of the outer ring raceway surface.

  The structure of FIG. 1 is the same as that of FIG. 5 in that the millimeter rolling elements 3 and the nano rolling elements 5 are interposed in series between a pair of tracks. Therefore, when the outer ring 1 is fixed and the inner ring 2 is rotated in the right direction, the relationship between the friction coefficient μm of the rolling bearing due to rolling of the millimeter rolling element 3 and the friction coefficient μn of the rolling bearing due to rolling of the nano rolling element 5 If μm <μn is established, the millimeter rolling element 3 with small friction first performs rolling motion (revolution in the right direction and rotation in the right direction), and the nano rolling element 5 with large friction is in the direction of Vn shown. And it is not excluded from the orbit as shown in FIG.

  The value of μ n is the safety side according to the description of “the friction coefficient of an aqueous colloidal solution containing 1% of 5 nBD sandwiched between sapphire and silicon plane is 0.005 to 0.01” in Example 3 of Patent Document 4 Use 0.005 as the value of the side where the moving body is not excluded from the orbit).

  On the other hand, the value of μm is the experimental value of the rolling friction of a steel ball not restrained by the same cage as the millimeter rolling element of this embodiment. The rolling friction coefficient 0.00002 "of the steel ball can be taken into consideration. Therefore, according to the present embodiment, it is sufficiently possible to satisfy μm <μn, and the millimeter rolling element 3 performs the well-known rolling movement, and the nano rolling element 5 is excluded because it does not roll in the direction of Vn. I have nothing to do.

Next, the role of the nano rolling element 5 will be described. As well known, within the contact ellipse of the rolling contact portion, differential sliding due to the difference in the radial dimension of the rolling element (the rolling element has different rolling radius due to the central portion and the peripheral portion of the contact oval There is a difference in the amount of revolution per degree of rotation, and this difference slips at the contact surface with the track. Since the operation slippage is a relative movement between the raceway surface 1a and the millimeter rolling element 3 when viewed locally, the micro rolling device is formed by interposing the nano rolling element 5 therebetween.

Specifically, in FIG. 1 (B), most of the nano rolling elements 5 distributed on the outer ring raceway surface 1a are stationary, but inside the contact ellipse 1b, the center side with the pure rolling portion 1d as the boundary The nano rolling element 5 rolls in the direction opposite to the revolution of the millimeter rolling element (solid arrow in the left direction in the figure), and the nano rolling element 5 in the direction of revolution of the millimeter rolling element (solid arrow in the figure in the figure) at both ends. Since the nano rolling elements 5 are dispersed in the liquid, this rolling causes a pressure difference such that the broken line area P1 in the figure is high in pressure and P2 is low in pressure, creating a circulating flow of the liquid shown by the broken arrow. Since the nano rolling elements 5 are circulated, a minute rolling device is formed to reduce friction, and the nano rolling elements are recycled, so that the rolling device can maintain a low friction state for a long time.

Since the contact ellipse 1b moves by the revolution of the millimeter rolling element 3, there is a nano rolling element 5c which deviates from the contact ellipse, but there is also a nano rolling element 5d which newly enters the contact ellipse and circulates. Therefore, the movement of the contact ellipse 1b does not significantly change the density of the nano rolling elements in and around the contact ellipse.
Further, even within the contact ellipse 1b, the gap between the raceway surface 1a and the millimeter rolling element 3 and the dimensions of the nano rolling element 5 are not constant, so all the nano rolling elements do not perform the circulating motion as illustrated.
The above contact ellipse 1b is formed on the contact surface between the outer ring raceway surface 1b and the millimeter rolling element 3, but the same contact ellipse is also applied to the contact plane between the inner ring raceway surface 2a and the millimeter rolling element 3 And the action of the nano rolling element 5 is also the same.
In addition, spin slip and gyro slip that occur in the rolling contact portion can also reduce friction due to the circulation of the nano rolling elements, similarly to differential slip.

Although the present embodiment has been described as the configuration of the “autonomous distributed rolling bearing”, the present invention is not limited to this.
For example, insert a shim between all mm rolling elements and apply an axial preload to the bearing before removing it, even if it is a full ball bearing that does not use a cage, and then remove all the shims Thus, the present invention can be applied to the same state as that of FIG.

FIG. 2 is a non-recirculation type in which cylindrical rollers are rotatably interposed as a plurality of millimeter rolling elements 3 between the rail raceway surface 11a of the rail 11 capable of relative movement and the slider raceway surface 2a of the slider 2 An example of the linear motion guidance of FIG. 2A is a cross-sectional view of a main part in a direction perpendicular to the axis that is the rotation center of the cylindrical roller, and FIG. 2B is a cross-sectional view in a direction parallel to the axis that is the rotation center of the cylindrical roller. A contact point change path (not shown in the drawing) described in Patent Document 2 is formed on the slider raceway surface 12a, whereby the millimeter rolling element 3 discharged from the contact point change path is the same as the succeeding millimeter rolling element 3. It forms an "autonomous distributed rolling bearing" that creates a gap between them. In contrast to the first embodiment, the millimeter rolling element 3 changes from a ball to a cylindrical roller, and the track changes from an annular ring to an end straight line, but the operation and effect of the invention are the same as the first embodiment. The differences are described below.

In FIG. 2 (B), the surface roughness of the raceway surface 1 and the outer diameter surface of the millimeter rolling element is described in the scale indicating the scale of the nano rolling element in the direction indicating the surface roughness. When the millimeter rolling element is a cylindrical roller, there is no mention of differential slippage due to the difference in the radial dimension of the rolling element, but actually the difference in the radial dimension of the rolling element due to the surface roughness (R2 shown) Since there is> R1), this radius difference causes slip, also referred to as actuation slip. And, by the cyclic movement of the nano rolling element in the contact area, the friction and the wear due to the operation slip can be reduced.

Other rollers that can be used for the millimeter rolling element include conical rollers and barrel rollers, and crowning may be performed to reduce the outer diameter of both ends of the roller outer diameter surface. It is obvious that the present invention can be applied to these roller shapes as well as R2 and R1 in the figure, because they have a difference in the radial dimension of the rolling element.

For the ball bearings, the characteristics of the coefficient of friction were evaluated. Table 1 shows the specifications of the evaluation bearing.
The bearing type is an angular contact ball bearing 708C (open type, outer diameter 22 mm, tangent angle 15 °, ball diameter 4 mm).
In Example A, the bearing structure is “autonomous dispersion type rolling bearing” (English initials ADB), the material is SUJ2, and the nanodiamond blended oil of Nanolube (USA) is used as a lubricant.
In Example B, since Example A rusted in the middle, the inner and outer rings and the nano rolling elements were used as rustproof specifications.
In the conventional example A, the bearing structure is ADB, and the lubricant is a machine tool hydraulic oil having a kinematic viscosity of 2.2 mm ² / s.
In Conventional Example B, a nanodiamond-containing oil was used for a caged bearing without friction and having a coefficient of friction of 0.005 or more.

  The endurance evaluation device is shown in FIG. The test bearing 20 was subjected to ultrasonic cleaning with white kerosene, heated and dried, and then the lubricant shown in Table 1 was dropped and assembled to the weight 21. No subsequent lubricant replenishment was performed. A motor (not shown) was connected to the weight 21 and the inner ring of the test bearing 20 was rotated at 120 rpm, the time from when the motor was released to when the inner ring stopped was measured, and converted to a coefficient of friction by the following equation. The measurement was basically performed every 24 hours, during which the continuous operation at 120 rpm was performed as it is in the state of FIG.

Coefficient of friction μ = 2 × J × N / (F × Dp × ts)
J: Weight 21 inertia 5.27 × 10E-3 [kgm ² ]
N: Number of rotations at the start of measurement 12.6 [rad / s] (= 120 rpm)
F: Axial load by weight 21 42.1 [N]
Dp: Pitch diameter of millimeter rolling element 3 0.015 [m]
Ts: Time until bearing inner ring stops [s]
Although the bearing inner diameter d is adopted in the calculation formula that the bearing manufacturer mentions for the moment distance when converting torque into friction force, it is necessary to compare with the friction coefficient of Patent Document 4 here, and the engineeringally correct millimeter The pitch diameter Dp of the rolling elements 3 was used.

The endurance evaluation results are shown in FIG. In the conventional example A, the friction coefficient increased rapidly in 36 hours and ended. The cause of the rapid increase in friction coefficient is considered to be the loss of lubricating oil.
In Conventional Example B, the friction coefficient increased rapidly in 84 hours and ended. The coefficient of friction exceeds 0.005 after the measurement at 36 hours, and it is estimated that the nano rolling elements on the raceway surface and the surface of the milli rolling element are largely moved and lost.

In Example A, corrosion was observed on the steel ball along the way, and the process was terminated in 156 hours exceeding 1 × 10E6 rotation. The coefficient of friction is as low as 0.0022 at the maximum, 0.0035 at the maximum, and 0.0019 at the censoring point, so it can be judged that the effect is remarkable. Rusting is a problem due to the balance with the environment.
Example B still has a coefficient of friction at 612 hours, averaging 0.00086.

From this durability evaluation result, in a rolling device that aims to eliminate the competition of rolling elements by the configuration of an autonomous dispersion type rolling bearing etc., by using a fluid or a fluid mixture in which at least nano rolling elements are dispersed in a lubricant It has been found that the mean value of the coefficient of rolling friction can be less than 0.005 without replenishing the lubricant for 1 × 10E6 revolutions.
Durability evaluation is continuing, but as a prospect, it is considered that "without replenishing the lubricant during 3 × 10E7 rotation" or "the maximum value of the rolling friction coefficient is less than 0.005" can be achieved.
The evaluation was that the seal was an open type bearing, and the condition was that the lubricant was likely to flow away due to the vertical axis installation and no cage, but like oil pans and greases that are subject to gravity restrictions It is very useful in the industry that the lubricating action can be maintained for a long time without relying on a thickener.

As mentioned above, although the explanation was made based on the embodiment, in the mechanism of the present invention, both the millimeter rolling element and the nano rolling element are mechanical rolling, and the functions of both rolling elements are separated by the friction coefficient. Therefore, applicable applications, materials, and the like are not limited to the description in the embodiments, but are various.
For example, the rolling device of the present invention can be applied to a ball screw, a linear motion guide or the like having a circulating structure of rolling elements described in Patent Document 1 and Patent Document 2.
In addition to bearing steel, stainless steel, titanium, ceramic, silicon alloy, carbon, glass, resin, aluminum or the like can be applied to the material of the millimeter rolling element and the raceway.
Furthermore, the surface treatment of the millimeter rolling element and the track may be triiron tetroxide coating, chromium plating, titanium nitride, ceramic thermal spraying, DLC, hard alumite, tafram or the like.

In addition, the nano rolling element has a particle diameter such as SiC particles disclosed in Patent Document 3 or nano rollers (detonation nano diamond, bucky diamond, boron nitride, corundum) disclosed in Patent Document 4 and the like. It is sufficient if it is a high hardness particle of nm to 20 nm.
Furthermore, a fluid that is a dispersant for nano rolling elements is disclosed in Patent Document 4; polyhydric alcohols including ethylene glycol, polyoxyethylene, alkylene glycol, polyoxyalkylene, glycerin, and derivatives thereof, water, high Boiling point alcohols and ionic liquids can be applied.
As a solution in which the nano rolling elements are dispersed, nanoamand of Nano Carbon Research Institute, Inc. other than Example 3 can be applied.

It can be widely used in rolling devices used in industrial machines, transport machines, etc.

1 outer ring 1b contact oval 2 inner ring 3 mm rolling element 4 cage 5 nano rolling element 11 rail 12 slider 20 test bearing 21 weight

Claims (4)

A contact composed of at least one pair of relative movable orbits and a plurality of millimeter rolling elements rollably interposed between the orbits, the orbit having a smaller contact radius of the millimeter rolling elements with respect to a part of the orbits By forming a point change path, the structure of an “autonomous distributed rolling bearing” is provided which creates a space between the millimeter rolling element coming out of the contact point changing path and receiving a load and the millimeter rolling element of its successor. Using a fluid in which at least nano rolling elements are dispersed in a lubricant, the friction coefficient of the rolling device by rolling of the millimeter rolling elements is μm, and the friction coefficient of the rolling device by rolling of the nano rolling elements is μn And a rolling device characterized in that μm <μn . The rolling device according to claim 1, wherein a dynamic friction coefficient without lubrication is less than 0.005 .   The rolling device according to claim 1, characterized in that the mean value of the rolling friction coefficient between them is less than 0.005 without replenishing the lubricant for 1 x 10E6 revolutions. The rolling device according to claim 1, wherein a material of the millimeter rolling element is stainless steel, ceramic, or silicon alloy.

Images