JP2017172678A - Roller bearing for cryogenic environment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing for cryogenic environment in which an assembling characteristic of a separator can be improved without being restricted against resiliency of resin raw material having solid lubricating characteristic, it can be easily assembled into a location where the adjoining rollers are most approached to each other at the final stage of assembling work and after assembling work, the rollers can be rotated in stable manner.SOLUTION: This invention relates to a roller bearing in which several balls 3 are arranged between an outer peripheral surface of an inner ring and an inner peripheral surface of an outer ring, several separators S containing solid lubricants of fluorine-contained resin system are present between the adjoining balls 3, each of spherical-surface-shaped recesses 5 contacted with each of the rollers is formed at about a middle part in an axial direction of both side surfaces 4a of the separators S opposing to their peripheral directions to hold the balls 3 in a rotatable manner. A wall surface part 6 including one end surface of both end surfaces of the inner ring and the outer ring in their axial directions of one separator 4 of several separators S is a divided piece, remaining portions are applied as prismatic barrels 7 of the separators 4 including the other end surface and formed with recesses 5, the divided piece can be separated in an axial direction in respect to the remaining portions and the divided pieces are arranged under connected states with a bolt 8 against the remaining portions.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a rolling bearing for a cryogenic environment that is attached to a pump or the like that transfers a liquefied gas in a cryogenic state such as liquefied natural gas and is used at a cryogenic temperature.

In general, a rolling bearing used in a room temperature environment is one in which a rolling element is rotatably held between an inner ring and an outer ring and needs to be lubricated. For example, a liquefied gas is present at −100 ° C. or below or −200. It is difficult to perform liquid lubrication with a lubricating oil or the like for a rolling bearing used in an extremely low temperature environment such as ° C or less.
In addition, rolling bearings for cryogenic environments are liable to decrease in strength and durability due to shrinkage and deformation of components to be cooled, and must withstand such severe use conditions.

  Incidentally, liquefied natural gas (LNG), which is a typical example of cryogenic liquefied gas, has physical properties that liquefy when cooled to -161.5 ° C (about -162 ° C) or lower under normal pressure. For example, nitrogen, helium, etc. are mentioned as gas utilized in a liquefied state for a refrigerant | coolant, a heat medium, filling gas, etc.

In addition, when transporting or storing a cryogenic liquefied gas in a liquid state, it is necessary to use a pump of a type suitable for use at a cryogenic temperature. A submerged pump is known.
Since this type of pump is used by immersing the entire pump device including the motor in liquefied gas, there is no need for a mechanical seal for sealing the main body from the outside air, so there is little loss due to dissipation of the vaporized gas. Are better.

  However, since the submerged pump is used in a state where the rolling shaft that supports the motor shaft or the like is in direct contact with the liquefied gas, the submerged pump is lubricated by LNG having poor lubricity.

  In addition to the above, as an example of a rolling bearing for a cryogenic environment, the environment temperature in the high altitude space farther from the stratosphere far from the surface of the earth, and the environment temperature in a further far space should be about −50 to −270 ° C. Therefore, rolling bearings used in such artificial satellites and spacecraft are required to have the same characteristics for cryogenic environments as described above.

  By the way, as a rolling bearing used in such a cryogenic environment, a bearing formed of a fluororesin is known in order to allow the cage to be incorporated to exhibit solid lubricity (Patent Document 1).

  In addition, as a form of a cage for rolling bearings under the same usage conditions, there is a so-called separator having a form in which an annular retainer is divided in the circumferential direction or a form such as a spherical form, and between adjacent rolling elements. In order to properly maintain the interval, the separator is arranged as a rotating body or a non-rotating body, and such a separator is known to have a lubricity formed by a PTFE polymer material having excellent solid lubricity. (Patent Document 2).

Japanese Patent Application Laid-Open No. 2014-020490 JP 2002-147462 A

However, in the separator described above, grooves or recesses for holding the ball are formed on both side surfaces facing in the circumferential direction, and the distance (thickness) between the side surfaces of the separator other than the recesses is naturally between the recesses. Greater than the distance (thickness).
Therefore, when rolling elements and separators are alternately assembled between the inner ring and the outer ring in the manufacturing process of the rolling bearing, the separator is not deformed as it is with respect to the gap between the pair of adjacent rolling elements remaining at the end. In the final stage of the assembling operation, the separator had to be elastically deformed and forced to be pushed in.

  In order to improve the difficulty of such assembly work, the separator is provided with an elastic expansion / contraction mechanism for elastically reducing the circumferential width, and the separator is assembled in an elastically compressed state. We examined the response to make it easier.

  However, if the elastic force is insufficient due to the material of the cage, a gap remains between the cage and the rolling element plastically deformed by the pushing, and it is necessary to consider the possibility that the rotation of the rolling element becomes unstable.

  Therefore, the object of the present invention is to solve the above-mentioned problems, improve the incorporation of the separator without restricting the elasticity of the resin material having solid lubricity, and achieve the best of the adjacent rolling elements in the final assembly stage. It is a rolling bearing for a cryogenic environment that can be easily assembled in an approached place, and the rolling element can rotate stably after the assembly.

  In order to solve the above problems, in the present invention, a plurality of rolling elements are arranged between the inner ring outer periphery and the outer ring inner periphery, and a prismatic separator containing a solid lubricant is interposed between the adjacent rolling elements, In a rolling bearing that forms recesses for guiding the rolling elements on both side surfaces facing the circumferential direction of the inner and outer rings of the separator so as to rotatably hold the rolling elements, one end face of both end faces of the separator in the inner and outer ring axial directions A rolling bearing for a cryogenic environment, characterized in that a part of a separator including a part is a split piece that is axially separable from the remaining part, and the split piece is provided in a coupled state with the remaining part. It was.

  The rolling bearing for the cryogenic environment of the present invention configured as described above is configured by alternately incorporating rolling elements and separators between the inner ring and the outer ring, and with respect to the gap between a pair of adjacent rolling elements remaining at the end. , When inserting from one side of the rolling bearing in the axial direction, a part of the separator including one end surface of both end faces in the inner and outer ring axial directions of the separator is inserted into the axial direction of the rolling bearing in advance from the opposite side of the rolling bearing. By inserting the remaining part, this part and the split piece can be combined and integrated.

That is, when assembling the separator into the gap between the pair of adjacent rolling elements remaining at the end, it is the outer side of the recesses that are the farthest adjacent rolling elements that hinders the incorporation from one axial direction. It is the “both end surfaces of the inner and outer ring axial direction of the separator” located in, but part of the separator including one end surface of the both end surfaces is a split piece that can be separated in the axial direction from the remaining portion Thus, the end faces can be attached from both sides in the inner and outer ring axial directions of the rolling bearing.
If the split piece can be coupled to the remaining part of the separator with a screw or the like, the separator need not be elastically deformed. In particular, even if the rolling element is a ball and the recess is a spherical recess. In addition, the work of assembling the rolling elements and separator of the rolling bearing can be performed quickly and efficiently.

  The separator is preferably a separator in which a bonding line formed at the edge of the bonding surface between the split piece and the remaining portion is disposed on a surface other than the surface in contact with the rolling element on the separator surface. This is because it is naturally natural that the edge of the joint surface that fits the divided parts is the part where the mechanical strength is the weakest, so that the joint line does not touch the rotating rolling elements. As a result, damage to the edge of the coupling surface can be prevented, so that the durability of the separator is improved.

  In addition, the separator has a relief groove that overlaps with the coupling line when a coupling line formed at the edge of the coupling surface between the split piece and the remaining portion is disposed on the contact surface with the rolling element on the separator surface. By providing (also referred to as "Nusumi"), damage can be prevented because the connecting wire does not come into contact with the rotating rolling elements.

  The separator piece and the remaining part of the separator are joined by screws or rivets to form a rolling bearing for a cryogenic environment that is surely connected and has excellent durability.

  In addition, by using the above separator for rolling bearings for cryogenic environments, it becomes a separator with good embedding without being restricted by the elastic characteristics of the material containing the solid lubricant, and the rolling element is stable using this. Thus, it becomes a rolling bearing for a cryogenic environment that rotates.

  In the present invention, a part of the separator including one end face of both end faces in the inner and outer ring axial directions of the separator of the rolling bearing is provided in a coupled state so as to be axially separable from the remaining part. Improves the separator's incorporation without restricting the elasticity of certain resin materials, and can easily incorporate the separator at the closest location between adjacent rolling elements at the final stage of assembly. There is an advantage that it can be a rolling bearing for a cryogenic environment that can be stably rotated, and an advantage that it can be a separator for a rolling bearing for a cryogenic environment that exhibits such an advantage.

Side view of rolling bearing for cryogenic environment according to the first embodiment Sectional drawing which shows the relationship between the ball | bowl arranged in 1st Embodiment, and a separator The perspective view of the 1st separator used for a 1st embodiment. Perspective view of second separator Perspective view of third separator Perspective view of the fourth separator Sectional drawing of the principal part which shows the escape groove accumulated on the coupling line of the 4th separator

Embodiments of the present invention will be described below with reference to the accompanying drawings.
As shown in FIGS. 1-3, 1st Embodiment arrange | positions the several ball | bowl 3 between the outer peripheral surface of the inner ring | wheel 1 and the inner peripheral surface of the outer ring | wheel 2 of a deep groove ball bearing, and contains a fluororesin-type solid lubricant. A plurality of separators S are interposed between the adjacent balls 3, and the angular groove-shaped recesses 5 with which the rolling elements (balls 3) contact each other are formed in the middle in the axial direction of both side surfaces 4 a facing the separator S in the circumferential direction. Thus, it is a rolling bearing that holds the ball 3 rotatably.
Of the plurality of separators S of the rolling bearing, among the two end faces in the inner and outer ring axial directions of one separator 4, the wall surface portion 6 including one end surface is used as a split piece, and the remaining portion includes the other end surface and includes a recess 5. As the prism-shaped body portion 7 of the separator 4 formed with the poles, the divided pieces can be axially separated from the remaining portions, and the divided pieces are connected to the remaining portions by bolts 8. This is a rolling bearing for low temperature environments.

  The inner ring 1 and the outer ring 2 of the ball bearing of the embodiment are made of a material that can withstand use in a cryogenic environment. For example, the inner ring 1 and the outer ring 2 are martensitic stainless steel, ferritic stainless steel, austenitic stainless steel, These are precipitation hardened stainless steel or high-speed tool steel, which are hard and excellent in wear resistance.

The material of the rolling element exemplified by the ball 3 is preferably one having good wear resistance and excellent transferability of a solid lubricant such as a fluororesin. For example, the martensitic stainless steel, ferrite type described above It is preferable to use stainless steel, austenitic stainless steel, precipitation hardening stainless steel, high-speed tool steel, or ceramics. Examples of the type of ceramic used include silicon nitride, zirconia, silicon carbide, alumina, and other ceramics.
The rolling bearing is illustrated as a deep groove ball bearing as a representative example, but may be a ball bearing or a roller bearing as long as it is a rolling bearing employing a separator.

The separator 4 used in the present invention is made of a material containing a solid lubricant, and the solid lubricant includes a layered material such as graphite, tungsten disulfide and molybdenum disulfide, a soft metal such as gold, silver and lead, polytetrafluoroethylene ( It is preferable to use a resin material containing a fluororesin such as PTFE), a fluororesin molded body, a metal coated with a solid lubricant, ceramics, or a composite material thereof.
In particular, the separator 4 made of a fluororesin material such as PTFE is preferable in order to transfer a fluororesin as a solid lubricant to the surface of the rolling element even at an extremely low temperature so as to exhibit good and stable solid lubricity.

  In the embodiment of the separator 4, a short cylindrical shape having a required height that fits between the outer circumference of the inner ring 1 and the inner circumference of the outer ring 2, that is, a ring-shaped material is divided in the circumferential direction and the interval between the adjacent rolling elements. However, other known shapes may be employed.

  As shown in FIG. 3, the separator 4 has a substantially prismatic shape and is formed of a fluorine resin material having a fan-shaped axial cross section, and the wall surface portion 6 including one end surface of both end surfaces in the axial direction is divided into pieces, The remaining portion (the wall surface portion 9 including the other end surface and the prismatic body portion 7 of the separator 4 in which the recess 5 is formed) can be separated in the axial direction, and the divided piece and the remaining portion are separated from each other. The bolt 8 is screwed in the axial direction from the wall surface portion 6 including one end surface to the prismatic body portion 7 so as to be coupled.

  In the rolling bearing according to the first embodiment, when the balls 3 and the prismatic separator 4 including the solid lubricant are alternately assembled in the assembling process of the balls 3 and the separators 4, the rolling bearings are adjacent to each other. A wall surface portion 6 including one end face is coupled to the remaining portion by a bolt 8 from the axial direction in a gap between the balls 3.

  That is, according to the first embodiment, the wall surface portion 6 including one end face which is a divided piece is inserted from the opposite side of the axial direction of the rolling bearing in advance from the one side in the axial direction with respect to the remaining portion of the separator. The bolts 8 can be combined and integrated.

  In the separator 4, the connecting line 10 formed at the edge of the connecting surface between the split piece and the remaining portion is arranged on the surface of the separator 4 other than the surface that contacts the ball 3. By preventing the connecting wire 10 from coming into contact with the rotating balls 3 in this manner, the durability of the divided separators 4 in use is improved.

The second embodiment shown in FIG. 4 is the same as the first embodiment except that the separator split piece used in the first embodiment and the remaining part thereof are changed.
That is, the separator 11 used in the second embodiment is formed using a prismatic fluororesin material having a sectoral cross section, and is divided into two wall surfaces 12 including one end surface among both end surfaces in the inner and outer ring axial directions. Combine one of the prismatic body parts 13, for example, a “single-tooth high clog-like part” as one divided piece, and combine the remaining part of the same shape with 2 opposing coupling surfaces. It is a rolling bearing for a cryogenic environment connected by a bolt 8.

  As in the second embodiment, the third embodiment shown in FIG. 5 is also the same as the second embodiment except that the separator pieces and the remaining portions are changed. is there.

  That is, the separator 14 used in the third embodiment has a prismatic shape together with the wall surface portion 15 including one end face among both end faces in the axial direction when the separator 14 is formed using a prismatic fluorine resin material having a sectoral cross section. A pole provided by dividing the body part into two parts by a rectangular outer peripheral surface and an inner peripheral surface including two parallel diagonal lines, and connecting with one of the two divided prismatic body parts 16 by bolts 8 This is a rolling bearing for low temperature environments.

  As shown in FIGS. 4 and 5, for the separators 11 and 14 used in the second and third embodiments, the connecting lines 17 and 18 formed at the edge of the connecting surface between the split piece and the remaining part are connected to the separator 11. , 14 is arranged on a surface other than the surface that contacts the ball 3, so that the edge of the coupling surface can be prevented from being damaged by preventing the coupling lines 17 and 18 from touching the rotating ball 3, and the separator 11 , 14 is improved.

  The fourth embodiment shown in FIGS. 6 and 7 is also the same as the third embodiment except that the divided pieces of the separator 19 and the remaining portions are changed, and the other parts are configured in exactly the same manner. .

  That is, when the separator 19 used in the fourth embodiment is formed using a prismatic fluororesin-based material having a sectoral cross section, the inner and outer ring periphery together with the wall surface portion 20 including one end face among the both end faces in the inner and outer ring axial directions. A substantially spherical concave portion 21 for guiding the ball 3 is formed on both side surfaces 19a opposed to each other in the direction, and the axial direction is divided into two at the central portion of the separator 19, and each portion is connected by a bolt 8 This is a rolling bearing for low temperature environments.

  In the separator 19, a connecting line 22 formed at the edge of the connecting surface between the two divided parts is disposed through the inner part of the recess 21 that is a contact surface with the ball 3. An escape groove (also referred to as “Nusumi”) 23 is provided so as to overlap the wire 22 so that the connecting wire 22 does not come into contact with the rotating rolling elements 3 to prevent damage.

  As shown in FIG. 7, the shape of the relief groove 23 is not only a circular groove (FIG. 7 (a)) but also a known groove shape such as a triangular groove (FIG. 7 (b)) 23a and other polygonal grooves. it can.

  Since this separator 19 has the hemispherically curved concave portion 5 in the middle of both side surfaces 19a so as to be able to contact the ball 3 in as wide an area as possible, the contact area between the separator and the ball is wide, A fluororesin that is a solid lubricant can be supplied efficiently.

  In the first to fourth embodiments, the bolt 8 using a screw is shown as a connected state, but a combined state using a rivet by providing a hole penetrating the split piece and the remaining part can also be adopted. . In order to prevent loosening of the screw due to vibration during rotation of the rolling bearing, known loosening prevention means using adhesion or welding can be employed.

  As described above, the rolling bearings for the cryogenic environment according to the first to fourth embodiments of the present invention configured as described above can be applied as rolling bearings for liquefied gas pumps with extremely severe lubrication conditions as described above. Similarly, it can also be applied as a rolling bearing used for supporting or driving an artificial satellite antenna that cannot be liquid lubricated at extremely low temperatures.

  When the rolling bearing is used for a liquefied gas pump, it can be applied to a submerged pump for liquefied natural gas (LNG). In that case, the rolling bearing is in direct contact with the cryogenic LNG, but it is used for a long time. It is a rolling bearing for a cryogenic environment that is resistant to wear and has excellent durability without deterioration of wear resistance and lubricity.

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Balls 4, 11, 14, 19 Separator 4a Both side surfaces 5, 21 Recess 6, 12, 15, 20 Wall surface part including one end surface 7 Square columnar body portion 8 Bolt 9 Wall surface portion 10 including the other end surface 17, 18, 22 Connecting lines 13, 16 Divided prismatic body parts 23, 23a Escape groove

Claims (6)

A plurality of rolling elements are arranged between the inner ring outer periphery and the outer ring inner periphery, and a plurality of prismatic separators including a solid lubricant are provided. These separators are interposed between adjacent rolling elements, and the inner and outer ring circumferences of the separators. In the rolling bearing for holding the rolling element rotatably by forming a recess for guiding the rolling element on both side surfaces facing in the direction,
Among the plurality of separators, a part of the separator including one end face of both end faces in the inner and outer ring axial directions of at least one separator is a split piece that can be separated in the axial direction from the remaining part. A rolling bearing for a cryogenic environment, characterized in that is provided in a coupled state with the remaining portion.   The rolling bearing for a cryogenic environment according to claim 1, wherein the rolling element is a ball and the concave portion is a spherical concave portion.   3. The electrode according to claim 1, wherein the separator is a separator in which a bonding line formed at an edge of a bonding surface between the divided piece and the remaining portion is disposed on a surface other than a surface in contact with the rolling element on the separator surface. Rolling bearing for low temperature environment.   The separator is a separator in which a connecting line formed at the edge of the connecting surface between the split piece and the remaining part is disposed on the contact surface with the rolling element on the separator surface, and a relief groove is provided on the connecting line. The rolling bearing for a cryogenic environment according to any one of claims 1 to 3.   The rolling bearing for a cryogenic environment according to any one of claims 1 to 4, wherein the coupled state is a coupled state using bolts or rivets.   The separator used for the rolling bearing for cryogenic environments in any one of Claims 1-5.

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