JP2005140269A - Cylindrical roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical roller bearing comprising a so-called comb type cage made of synthetic resin, preventing elastic deformation of pillar parts during high speed rotation and abnormal contact between the tips of the pillar parts and the rolling contact surfaces of cylindrical rollers caused by the elastic deformation, to prevent abnormal wear of the cage, to suppress the rise of bearing temperature and to reduce non-repeatable run-out (NRRO) at the same time. <P>SOLUTION: In the cage 4 formed by projecting a plurality of pillar parts 4b axially from one side face of an annular part 4a, the axial length Ta of the annular part 4a is set to 30-40% of the axial length Td of the cylindrical roller 3, and the axial length Tb of the pillar part 4b is set to 65-75% of the axial length Td of the cylindrical roller 3. Further, the whole rolling contact surface area of the cylindrical roller 3 is disposed axially inside of a boundary position X between a raceway surface 2a of an outer ring 2 and a chamfer part 2b. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a cylindrical roller bearing provided with a cage made of synthetic resin, for example, a cylindrical roller bearing used for supporting a rotating member that rotates at high speed such as a main spindle of a machine tool.

  As is well known, in a machine tool such as a machining center, a CNC lathe, a milling machine, etc., the main shaft is usually supported rotatably by a bearing with respect to the housing, and the orientation of the main shaft depends on the machine type. It is roughly divided into an axis (the axis is oriented in the vertical direction) and a horizontal axis (the axis is oriented in the horizontal direction). The lubrication system of the bearing that supports the main shaft employs oil lubrication such as grease lubrication or air-oil lubrication according to the usage conditions, and as a bearing type, a combination angular contact ball bearing or cylindrical roller bearing is used. Generally used widely.

  In this case, the cylindrical roller bearing used for supporting the main shaft of the machine tool is usually provided with a cage for holding a plurality of cylindrical rollers at predetermined intervals between the inner ring and the outer ring. is there. And, as this cage, a high-strength brass cast-out (machined) cage has been mainly used conventionally. However, there is a problem of lubricant deterioration due to wear powder of the cage during operation and weight reduction. From this point, in recent years, switching to a synthetic resin cage has progressed.

  With the transition of such technology, as a synthetic resin cage for cylindrical roller bearings currently used, for example, as described in Patent Documents 1 and 2 below, A plurality of column portions extending in one axial direction from the inner side surface and a plurality of pockets formed between the circumferential side surfaces of the column portions adjacent in the circumferential direction and rotatably holding the cylindrical rollers, A cage having a so-called comb shape is known. However, in this form of the synthetic resin cage, since the tip of the column portion is a free end, the column portion is relatively elastically deformed to the outer diameter side due to the centrifugal force during rotation, particularly at high speed rotation. As a result, the inner peripheral part of the tip side on the circumferential side is in strong contact (abnormal contact) with the rolling surface of the cylindrical roller, causing an oil film breakage at the contact part, resulting in abnormal wear or an increase in bearing temperature. May be an increase factor.

Therefore, according to Patent Documents 1 and 2, in order to cope with this problem, as shown in FIG. 12, the circumferential side surface 14b1 of the column portion 14b extending in the axial direction from the annular portion 14a of the retainer 14 is formed in a pocket. The roller PCD passing through the pocket center O of 14c is divided into an outer diameter side region and an inner diameter side region, and the outer diameter side region is formed on an arc surface (cylindrical surface) 14b11 along the rolling surface of the cylindrical roller 13. At the same time, by forming the inner diameter side region on the straight surface 14b12 parallel to the radial line r1 passing through the pocket center O over the entire axial length, the column portion 14b is moved to the outer diameter side by the action of centrifugal force during rotation. When elastically deforming, the inner diameter side region 14b12 of the circumferential side surface 14b1 of the column portion 14b is prevented from generating a radial contact pressure with the rolling surface of the cylindrical roller 3.
JP 11-166544 A (paragraph number 0027, FIG. 10) International Publication No. WO03 / 029670 (page 24, lines 17 to 26, FIG. 23)

  The main characteristics required for the main spindle of a machine tool are that high-speed rotation {usually, dmn value (= 1 million or more of rolling element pitch circle diameter mm × rotational speed rpm) and non-repetitive runout ( NRRO) is small, and this characteristic is mainly determined by the shaft support function of the bearing that supports the main shaft. However, it is difficult for the cylindrical roller bearings described in Patent Documents 1 and 2 to satisfy non-repetitive runout (NRRO) required for the spindle of a machine tool for the following reason.

  In other words, in the cylindrical roller bearing retainer 14 described in Patent Documents 1 and 2, the circumferential side surface 14b1 of the column portion 14b has an axial inner side area that is the entire axial length of the roller PCD as described above. It is formed on the straight surface 14b12, and when the column portion 14b is elastically deformed to the outer diameter side by the action of centrifugal force during rotation, the inner diameter side region 14b12 of the circumferential side surface 14b1 rolls the cylindrical roller 13. No contact pressure in the radial direction with the surface is generated. However, this configuration is effective in preventing abnormal contact between the circumferential side surface 14b1 of the column portion 14b and the rolling surface of the cylindrical roller 13, but on the other hand, the circumferential side surface 14b1 of the column portion 14b. As a result of forming the inner diameter side region of the cylindrical portion on the straight surface 14b12, the result is that the elastic deformation of the column portion 14b toward the outer diameter side is promoted. That is, by forming the inner diameter side region of the circumferential side surface 14b1 of the column part 14b on the straight surface 14b12, the normal pocket configuration (the entire region of the circumferential side surface of the column part is used as the rolling surface of the cylindrical roller). Compared to the pocket shape formed on the arcuate surface, the portion that restricts elastic deformation of the column portion 14b toward the outer diameter side is eliminated, and the circumferential thickness of the inner diameter side region of the column portion 14b is reduced. As a result, the rigidity of the column portion 14b is reduced, and the elastic deformation of the column portion 14b toward the outer diameter side is promoted.

  FIG. 13 shows a state (solid line) in which the column portion 14b of the retainer 14 of the cylindrical roller bearing described in Patent Documents 1 and 2 is elastically deformed to the outer diameter side by the action of centrifugal force during high-speed rotation (solid line). The state (dotted line) is schematically shown. As shown in the figure, in the cage 14 of the cylindrical roller bearing described in Patent Documents 1 and 2, when the column portion 14b is elastically deformed to the outer diameter side, the circumferential side surface 14b1 of the column portion 14b and the cylindrical roller 13 are shown. The pocket gap g between the first and second rolling surfaces is larger than the initial gap (gap before deformation). Moreover, as described above, the elastic deformation of the column part 14b toward the outer diameter side is promoted, and as a result, the pocket gap g is also increased. Then, due to the increase in the pocket gap g, the equal distribution function of the cylindrical roller is lowered, the revolution center of the cylindrical roller is shaken, and non-repetitive shake is generated in which the inner ring is shaken in an unstable manner. In particular, in a roller guide type cage, the degree of freedom in the radial direction of the cage is increased, so that a portion where the pocket gap g is increased and a portion where the pocket gap g is reduced can be formed, and the occurrence positions of these portions are not constant. In addition, the degree of non-repetitive shake increases. This non-repetitive run-out (NRRO) increases in proportion to the increase in the number of revolutions, and causes a reduction in machining accuracy by a tool attached to the main spindle of the machine tool.

  FIG. 14 is a typical longitudinal cross-sectional view showing a relative dimensional relationship between the annular portion 14a and the column portion 14b of the retainer 14 with respect to the cylindrical roller 13 in the cylindrical roller bearing described in Patent Literatures 1 and 2 (Patent Literature). As shown in FIG. 14, the axial length (thickness) Ta of the annular portion 14 a of the cage 14 is about 25% of the axial length Td of the cylindrical roller 13. Is set to about. That is, as can be understood from the other drawings of Patent Documents 1 and 2, the above-described dimensional relationship is set to about 25% in the known conventional synthetic resin cage. Was customary. The reason why such a setting is made is that the relationship between the axial length Te of the inner ring 11 and the outer ring 12 and the axial length Td of the cylindrical roller 13 is approximately unambiguous considering the function of the cylindrical roller bearing. If it is designed based on this and the characteristics of the resin material of the cage 14, the axial length Ta of the annular portion 14 a of the cage 14 is naturally the axial length Td of the cylindrical roller 13. This is due to the fact that it must be about 25% of the above.

  However, although the cylindrical roller bearing according to the conventional design can sufficiently perform its function in the low and medium rotational speed region, the bearing temperature is increased due to the elastic deformation of the column portion 14b of the cage 14 in the high rotational speed region. May rise unjustly. Moreover, even if it employ | adopts the method of forming the straight surface 14b12 as stated above in the pillar part 14b of the holder | retainer 14 as disclosed in patent document 1, 2, if it was said conventional design, for example, 13000rpm Alternatively, the bearing temperature may unduly increase in a high rotation speed region exceeding the rotation speed in the vicinity thereof (or in a region where the dmn value exceeds 1,650,000 or in the vicinity thereof). It can be said that the cause of such a phenomenon is that the pillar portion 14b of the cage 14 is largely elastically deformed to the outer diameter side by the action of centrifugal force.

  Even when measures are taken to prevent contact between the column 14b of the cage 14 and the cylindrical roller 13 in this way, the bearing temperature is improper in a very high rotational speed region due to elastic deformation of the column 14b. The present inventors have found that the phenomenon that the phenomenon of rising in the vertical direction can occur is largely derived from the axial length Ta of the annular portion 14a of the retainer 14. Therefore, if the dimensional relationship between the axial length Ta of the annular portion 14a of the cage 14 and the axial length Td of the cylindrical roller 13 is set as in the prior art, it is due to the action of a very large centrifugal force. There is a concern that it will be a major obstacle in accurately reducing the elastic deformation of the column portion 14b.

  An object of the present invention is to provide a cylindrical roller bearing provided with a so-called comb-shaped cage made of synthetic resin, elastic deformation of the column portion during high-speed rotation, and the leading end of the column portion and the rolling surface of the cylindrical roller resulting therefrom. This is to prevent abnormal contact of the cage, to prevent abnormal wear of the cage and to suppress a rise in bearing temperature, and to reduce non-repetitive runout (NRRO).

  The present invention made in order to solve the above technical problem includes an inner ring, an outer ring, a plurality of cylindrical rollers arranged to roll between the inner ring and the outer ring, and a cage made of synthetic resin. The retainer is formed between an annular portion, a plurality of column portions extending in one axial direction from an inner surface of the annular portion, and a circumferential side surface of the column portion adjacent in the circumferential direction, In the cylindrical roller bearing having a plurality of pockets for rotatably holding the cylindrical roller, the axial length of the annular portion of the cage is set to 30 to 40% of the axial length of the cylindrical roller. It is characterized by this.

  According to such a configuration, the axial length of the annular portion that cantilever-supports the column portion of the synthetic resin cage is set to 30 to 40% of the axial length of the cylindrical roller. In other words, the rigidity of the annular portion is relatively higher than that of the column portion because it is set to be appropriately larger than the conventional size ratio of about 25%. Therefore, since the column part is supported by the relatively rigid annular part and the support rigidity is increased, even if the column part tries to elastically deform to the outer diameter side due to the centrifugal force during rotation, It is possible to prevent an unreasonably large elastic deformation from occurring at the base end portion of the column portion (the base portion of the column portion), thereby suppressing the elastic deformation of the entire column portion. In this case, if the axial length of the annular portion is less than 30% of the axial length of the cylindrical roller, the rigidity of the annular portion, and thus the supporting rigidity of the column portion by the annular portion tends to be insufficient, particularly in the high rotation speed region. Since the amount of elastic deformation of the column portion toward the outer diameter side increases, abnormal contact occurs between the inner peripheral portion on the tip side of the column portion and the rolling surface of the cylindrical roller, for example, exceeding 13000 rpm or the number of rotations in the vicinity thereof. In this stage (or when the dmn value exceeds 1.65 million or a value close to it), abnormal wear of the cage and sudden rise in bearing temperature may occur, and non-repetitive runout (NRRO) may also occur. . In contrast, when the axial length of the annular portion exceeds 40% of the axial length of the cylindrical roller, the cylindrical roller is positioned over an unreasonably long distance in the axial direction with respect to the outer ring and the inner ring. Since the necessity to change arises, the fundamental problem on a structure arises, for example, the axial direction length of an outer ring and an inner ring is insufficient. In addition, if the dimensional relationship between the two exceeds 40%, the axial length of the cylindrical rollers becomes relatively short, and the load capacity is reduced. Therefore, if the dimensional relationship between the two is within a numerical range of 30 to 40%, these problems do not occur.

  In the above configuration, the axial length of the column portion of the cage is preferably set to 65 to 75% of the axial length of the cylindrical roller.

  That is, if the axial length of the column portion is less than 65% of the axial length of the cylindrical roller, the column portion cannot be properly held by the column roller during rotation, particularly during high-speed rotation, and the posture of the cylindrical roller is inappropriate. Therefore, even if the elastic deformation of the column portion can be suppressed, the original holding function of the cylindrical roller is hindered. On the other hand, when the axial length of the column portion exceeds 75% of the axial length of the cylindrical roller, the axial length of the annular portion is relatively long as described above. Even if the rigidity and the support rigidity of the column portion are increased, the axial length of the column portion may become long to such an extent that the elastic deformation during high-speed rotation cannot be sufficiently suppressed. Therefore, if the dimensional relationship between the two is set to 65 to 75% as described above, not only these problems do not occur, but also the axial length of the annular portion is set to the axial length of the cylindrical roller as described above. The technical idea of setting to 30 to 40% of the above will bring more important significance and effect.

  Further, in the above configuration, a chamfered portion is formed on the outer side in the axial direction of the raceway surface on which the cylindrical roller in the inner ring and / or the outer ring rolls, and the entire rolling surface of the cylindrical roller has the raceway surface and the chamfered portion. It is preferable that it is arrange | positioned axially inside rather than the boundary position.

  That is, if the axial length of the annular portion of the cage is elongated as described above, it is necessary to position the cylindrical roller on the outer side in the axial direction by a size corresponding to this, in which case the inner ring and / or Or, if the chamfered portion is formed on the outer side of the raceway surface in the outer ring, the rolling surface of the cylindrical roller may come into contact with the boundary position across the boundary position between the raceway surface and the chamfered portion. There is a fear. In this case, when the cylindrical roller rolls in a state where the rolling surface of the cylindrical roller straddles the boundary position between the raceway surface and the chamfered portion, the rolling surface of the cylindrical roller is locally moved from the boundary position to the rolling surface. Stress (edge stress) acts, and the essential function of this type of cylindrical roller bearing is hindered. However, if the entire rolling surface of the cylindrical roller is disposed on the inner side in the axial direction than the boundary position between the raceway surface and the chamfered portion as in the present invention, such a problem does not occur.

  In such a configuration, the chamfered portion is preferably formed with an inclination angle of 10 to 30 ° with respect to the cylindrical surface constituted by the raceway surface.

  That is, if the angle of inclination of the chamfered portion (tapered surface portion) is less than 10%, in the NN type cylindrical roller bearing, the inlet diameter (referred to as the lead-in chamfer diameter) on the bearing side surface becomes small. In this case, interference between the end face of the cylindrical roller and the width of the outer ring is likely to occur, and smooth assembly becomes difficult (the same applies to the NNU type cylindrical roller bearing). On the other hand, even when the inclination angle of the chamfered portion exceeds 30%, it is difficult to smoothly incorporate the cylindrical roller due to the large inclination of the chamfered portion when assembling the cylindrical roller bearing. It becomes. Therefore, if the inclination angle of the chamfered portion is set within a range of 10 to 30 °, such a problem does not occur.

  In the above configuration, the circumferential side surface of the column portion of the cage is formed as an arc surface along the rolling surface of the cylindrical roller at the proximal end side inner peripheral portion, and the column portion is centrifuged during rotation. A roller guide portion that guides the rolling surface of the cylindrical roller when elastically deformed to the outer diameter side by force, and a circumferential direction of the column portion at the tip end side inner peripheral portion rather than the roller guide portion It is preferable to have a relief portion that retracts to the center side and does not generate a contact pressure in the radial direction with the rolling surface of the cylindrical roller when the column portion is elastically deformed to the outer diameter side by centrifugal force during rotation.

  In this way, when the column portion is elastically deformed to the outer diameter side due to the centrifugal force during rotation, an arc surface along the rolling surface of the cylindrical roller is provided on the inner peripheral portion on the proximal side of the circumferential side surface of the column portion. The formed roller guide portion is displaced in a direction (outer diameter side) in which the pocket gap between the cylindrical roller and the rolling surface of the cylindrical roller is reduced, and guides the rolling surface of the cylindrical roller. Therefore, a good even distribution function of the cylindrical roller is ensured, and non-repetitive runout (NRRO) during high-speed rotation is reduced to a level where there is no problem. Note that the elastic deformation amount of the column portion is smaller on the proximal end side than on the distal end side, so that the abnormal contact between the two does not occur even when the cylindrical roller is guided by the roller guide portion on the inner circumferential portion on the proximal end side. On the other hand, the inner circumferential portion on the distal end side of the circumferential side surface of the column portion is provided with a relief portion that is retracted closer to the circumferential center side of the column portion than the roller guide portion, so the distal end side of the circumferential side surface The inner peripheral portion is not in contact with the rolling surface of the cylindrical roller, or is light enough to cause no contact pressure in the radial direction even when contacting. As a result, abnormal contact between the inner circumferential portion on the circumferential side surface and the rolling surface of the cylindrical roller during high-speed rotation is avoided, abnormal wear on the inner circumferential portion on the distal end is prevented, and a rise in bearing temperature is suppressed. Is done.

  Furthermore, by providing the roller guide portion as described above at the proximal side inner peripheral portion of the circumferential side surface, the circumferential thickness of the proximal end side inner peripheral portion of the column portion is increased, and the rigidity of the column portion is increased. Will improve. Therefore, the amount of elastic deformation in the outer diameter direction and the circumferential direction of the column portion due to the centrifugal force during rotation and the load from the cylindrical roller is reduced. Thereby, the favorable equal distribution function of a cylindrical roller is maintained.

  In the above configuration, the axial length of the relief portion is preferably 10% to 35% of the axial length of the cylindrical roller. In addition, the line connecting the radial start position of the relief portion and the pocket center of the pocket forms an angle of 20 degrees or less on the inner diameter side with respect to the tangent to the pocket PCD at the pocket center of the pocket. It is preferable to set a starting position in the radial direction. By forming the relief portion based on these standards, the above-described effects can be exhibited in the high-speed rotation range required for the machine tool spindle.

  Moreover, it is preferable that the circumferential side surface of the relief portion is a straight surface parallel to the circumferential center line of the column portion. Compared to the case where the circumferential side surface of the relief portion is a straight surface parallel to the radial line passing through the center of the pocket, the circumferential thickness of the inner peripheral portion on the tip side of the column portion is increased while obtaining the same effect. Thus, the rigidity of the column portion can be increased.

  Alternatively, the circumferential side surface of the relief portion may be an inclined surface that is inclined in a direction approaching the circumferential center line of the column portion. As a result, abnormal contact between the inner circumferential portion on the circumferential side surface of the column portion and the rolling surface of the cylindrical roller during high-speed rotation can be avoided more reliably, and the function as a lubricant reservoir in the escape portion Can be increased.

  The present invention is particularly suitable for a double row cylindrical roller bearing in which cylindrical rollers are arranged in a plurality of rows. In this case, it is preferable that each row of cylindrical rollers is individually held by the above cage. More preferably, it arrange | positions in the state which mutually attached the cyclic | annular parts of said holder | retainer holding each row | line | column of a cylindrical roller on the bearing center side.

  As described above, according to the cylindrical roller bearing according to the present invention, in the cylindrical roller bearing provided with the so-called comb-shaped synthetic resin cage, the axial length of the annular portion of the cage is set to the axial direction of the cylindrical roller. Since the column portion is set to 30 to 40% of the length, the column portion is supported by an annular portion having a relatively high rigidity, and the support rigidity is increased. Even if it is going to be elastically deformed to the side, it is possible to prevent an unreasonably large elastic deformation from occurring at the base end portion of the column portion, and consequently to suppress the elastic deformation of the entire column portion. As a result, abnormal contact between the tip of the column portion and the rolling surface of the cylindrical roller during rotation can be prevented, thereby preventing abnormal wear of the cage and suppressing increase in bearing temperature, and at the same time, non-repetitive. It is also possible to reduce runout (NRRO).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a double-row cylindrical roller bearing according to the first embodiment. This double-row cylindrical roller bearing is a spindle device of a machine tool that supports a main shaft that is driven to rotate at a high speed with respect to a housing. The double-row cylindrical roller bearing includes an inner ring 1 having a double-row raceway surface 1a, An outer ring 2 having a raceway surface 2a, a double-row cylindrical roller 3 disposed between the raceway surface 1a of the inner ring 1 and the raceway surface 2a of the outer ring 2, and a cylindrical roller 3 in each row are held. And a pair of synthetic resin cages 4. In this case, an inner collar 1b is provided at the central portion in the axial direction of the inner ring 1, and outer collars 1c are provided at both ends.

  Chamfered portions 2b are respectively formed on both outer sides in the axial direction of the raceway surface 2a of the outer ring 2, and relatively small chamfered portions 1d are also formed on both outer sides in the axial direction of the raceway surface 1a of the inner ring 1. In this case, the inclination angle α of the chamfered portion 2b of the outer ring 2, that is, the inclination angle α of the chamfered portion 2b with respect to the cylindrical surface constituted by the raceway surface 2a of the outer ring 2 is set to 10 to 30 °. The entire rolling surface of the cylindrical roller 3 is arranged on the inner side in the axial direction from the boundary position X between the raceway surface 2a of the outer ring 2 and the chamfered portion 2b. The inner ring 1 is fitted on the outer circumference of the main shaft, and the outer ring 2 is fitted on the inner circumference of the housing. The double-row cylindrical roller bearing is often operated in a state where the radial internal gap is negative, that is, a radial preload is applied, for example, with a small amount of lubricant such as air oil or grease. The inner ring 1 may have a tapered inner diameter surface. Therefore, the inner ring 1 is fitted to the outer peripheral surface of the main shaft formed in a tapered shape or the outer peripheral surface of the tapered sleeve fitted to the outer periphery of the main shaft. It may be.

  As shown in FIGS. 2 and 3 in an enlarged manner, the cage 4 has a self-lubricating property such as polyether ether ketone resin (PEEK), polyamide resin (PA: PA66, PA46), polyphenylene sulfide resin (PPS), and the like. A synthetic resin (if necessary, a required amount of filler such as carbon fiber (CF) and glass fiber (GF) is blended) is formed by injection molding, and the annular portion 4a and the inner surface of the annular portion 4a 4a1 is formed between a plurality of pillars 4b extending continuously in one axial direction from 4a1 and a circumferential side surface 4b1 of pillars 4b adjacent in the circumferential direction, and holds cylindrical roller 3 rotatably. And a plurality of pockets 4c. The plurality of column portions 4b are arranged at circumferentially equidistant positions. Each pocket 4c is surrounded from three sides by the circumferential side surface 4b1 of the column part 4b adjacent in the circumferential direction and the inner side surface 4a1 of the annular part 4a, and is open toward one side in the axial direction.

  In this case, as shown in FIGS. 1 and 3A, the axial length (thickness) Ta of the annular portion 4a in the cage 4 is 30% to 40% of the axial length Td of the cylindrical roller 3, In this first embodiment, it is set to 30%. In addition, the axial length Tb of the column portion 4b in the cage 4 is set to 65 to 75% of the axial length Td of the cylindrical roller 3, and is set to 70% in this first embodiment.

  On the other hand, as shown in FIGS. 3 (a) and 3 (b), both side surfaces 4b1 in the circumferential direction of the column part 4b in the retainer 4 are pocket PCDs (in the example shown in FIG. The pocket PCD is the same as the roller PCD passing through the center of the cylindrical roller 3.) An arc surface (cylindrical surface) 4b11 formed from the inner diameter side to the outer diameter side, and a relief portion 4b12 provided at the inner peripheral portion on the front end side. And.

  Specifically, the circular arc surface 4b11 of the column part 4b is drawn with an arc having a radius 1.005 to 1.1 times the radius (D / 2) of the cylindrical roller 3 with the pocket center O as the center. The outer diameter end is continuous with the straight surface 4b13 parallel to the radial line r1 passing through the pocket center O. The separation distance W1 between the straight surfaces 4b13 opposed to each other in the circumferential direction is smaller than the diameter D of the cylindrical roller 3, thereby restricting the cylindrical roller 3 from slipping out of the pocket 4c to the outer diameter side. The inner diameter end of the arcuate surface 4b11 extends to the inner diameter end of the column portion 4b on the base end side, and is continuous with the escape portion 4b12 on the inner peripheral portion on the distal end side. The minimum separation distance W2 between the base end side inner peripheral portions 4b14 of the circular arc surfaces 4b11 facing each other in the circumferential direction is smaller than the diameter D of the cylindrical roller 3. The base end side inner peripheral portion 4b14 serves as a roller guide portion that guides the rolling surface of the cylindrical roller 3 when the column portion 4b is elastically deformed to the outer diameter side by centrifugal force during rotation.

  The clearance part 4b12 of the distal end side inner peripheral part is formed from the distal end of the column part 4b to the middle part from the distal end along the axial direction to the proximal end part, and the circumferential center of the column part 4b is more than the proximal end inner peripheral part 4b14. The meat is cut so as to retract to the line r2. The axial length L1 of the escape portion 4b12 is 10% to 35% of the axial length Td of the cylindrical roller 3, and the radial start position of the escape portion 4b12 is based on the tangent m1 of the pocket PCD at the pocket center O. It is set so that θ ≦ 20 ° on the inner diameter side. The angle θ is an angle formed by a line m2 connecting the starting position in the radial direction of the relief portion 4b12 and the pocket center O with the tangent line m1. Further, the circumferential side surface of the relief portion 4b12 is formed on a straight surface parallel to the circumferential center line r2 of the column portion 4b. The relief portion 4b12 formed in such a manner forms a space portion that becomes a lubricant reservoir between the rolling surface of the cylindrical rollers 3 at the time of low speed rotation, and the column portion 4b has a centrifugal force at the time of high speed rotation. Even when elastically deforming toward the outer diameter side along the circumferential center line r <b> 2 by the above action, it does not come into contact with the rolling surface of the cylindrical roller 3. In addition, although the minimum separation distance between the circumferential direction side surfaces of the relief portion 4b12 opposed to each other in the circumferential direction is slightly smaller than the diameter D of the cylindrical roller 3, the relief portion 4b12 has an outer diameter along the circumferential center line r2. Since it is displaced to the side, it does not contact the rolling surface of the cylindrical roller 3. In this way, by forming the circumferential side surface of the relief portion 4b12 on a straight surface parallel to the circumferential center line r2, the tip of the column portion 4b is formed compared to the case where it is formed on a straight surface parallel to the radial line r1. The rigidity of the column part 4b can be increased by increasing the circumferential thickness of the side inner peripheral part.

  As shown in FIG. 1, in the first embodiment, the cage 4 is of a rolling element guide type, and the cage 4 rotates the circumferential side surface 4b1 of the column portion 4b on the rolling of the cylindrical roller 3 when the bearing rotates. It rotates while being guided by contact with the moving surface. Then, when the rotation of the bearing reaches a predetermined high-speed rotation region and the column portion 4b is elastically deformed to the outer diameter side by the centrifugal force at the time of high-speed rotation, the proximal end side inner peripheral portion of the circumferential side surface 4b1 of the column portion 4b ( The roller guide portion) 4b14 is displaced in the direction in which the pocket gap between the rolling contact surface of the cylindrical roller 3 is reduced (on the outer diameter side along the circumferential center line r2) and the rolling contact surface of the cylindrical roller 3 is changed. invite. In this case, the dimensional ratio of the axial length Ta of the annular portion 4a to the axial length Td of the cylindrical roller 3 is set to 30%, which is set larger than the conventional dimensional ratio (about 25%). The relative thickness of the annular portion 4a with respect to the cylindrical roller 3 is increased. Therefore, the amount of elastic deformation δ toward the outer diameter side of the tip of the column part 4b shown in FIG. 4 is reduced. More specifically, if the dimensional ratio is 30%, the rigidity of the annular portion 4a and thus the supporting rigidity of the annular portion 4a with respect to the column portion 4b are increased. Therefore, the column portion 4b is caused by centrifugal force during high-speed rotation. Even when elastically deforming to the outer diameter side, the amount of elastic deformation δ at the tip of the column portion 4b is small. As a result, contact with the rolling surface of the cylindrical roller 3 is appropriately avoided, a good equal distribution function of the cylindrical roller 3 is ensured, and non-repetitive runout (NRRO) during high-speed rotation is not problematic. Reduced.

  Further, since the axial length Tb of the column portion 4b is set to an appropriate length of 70% of the axial length Td of the cylindrical roller 3, the axial length Tb of the column portion 4b is unreasonably set. The shortage prevents the problem of hindering the function of holding the cylindrical roller 3 in the normal posture, and the axial length Tb of the column 4b is unduly long, so that the amount of elastic deformation δ of the column 4b is reduced. The problem that it is difficult to reduce is also avoided. Thereby, as described above, the advantage obtained by setting the dimensional ratio of the axial length Ta of the annular portion 4a to the axial length Td of the cylindrical roller 3 to 30% can be obtained more reliably.

  And since the escape side 4b12 is provided in the front end side inner peripheral part of the circumferential direction side surface 4b1 of the pillar part 4b, a contact with the rolling surface of the cylindrical roller 3 is avoided more reliably. Therefore, abnormal wear of the inner peripheral portion on the distal end side of the circumferential side surface 4b1 during high-speed rotation is prevented, and an increase in bearing temperature is suppressed.

  Furthermore, the base end side inner peripheral portion (roller guide portion) 4b14 of the circumferential side surface 4b1 is an arc surface along the rolling surface of the cylindrical roller 3, so that the base end side inner peripheral portion 4b14 of the column portion 4b has a circle. The circumferential thickness is increased, and the rigidity of the column portion 4b is improved. Therefore, the amount of elastic deformation in the outer diameter direction and the circumferential direction of the column portion 4b due to the centrifugal force at the time of high-speed rotation and the load from the cylindrical roller 3 is reduced, thereby maintaining a good even distribution function of the cylindrical roller 3. Is done.

  Further, since the entire rolling surface of the cylindrical roller 3 is disposed on the inner side in the axial direction than the boundary position X between the raceway surface 2a and the chamfered portion 2b of the outer ring 2, the rolling surface of the cylindrical roller 3 is By contacting in a state of straddling the boundary position X, a situation in which local stress (edge stress) is applied does not occur, and there is no room for the inherent functional hindrance of the cylindrical roller bearing. In this case, it is necessary to set the boundary position X between the raceway surface 2a and the chamfered portion 2b in consideration of the amount of relative movement in the axial direction of the inner and outer rings 1 and 2 due to mounting errors and thermal expansion of the main shaft.

  Further, since the chamfered portion 2b is formed with an inclination angle of 10 to 30 ° with respect to the cylindrical surface A constituted by the raceway surface 2a, the cylindrical roller 3 can be smoothly incorporated when the cylindrical roller bearing is assembled. Is possible.

  The cage 4 according to the second embodiment of the present invention shown in FIG. 5 is such that the dimensional ratio of the axial length Ta of the annular portion 4a to the axial length Td of the cylindrical roller 3 is 35%. Since the other components and operational effects are the same as those in the first embodiment, the same reference numerals are assigned to the components common to the both in FIG.

  The cage 4 according to the third embodiment of the present invention shown in FIG. 6 is such that the dimensional ratio of the axial length Ta of the annular portion 4a to the axial length Td of the cylindrical roller 3 is 40%. Since the other components and operational effects are the same as those in the first embodiment, the same reference numerals are given to the components common to both of them in FIG.

  The cage 4 shown in FIG. 11 has a dimensional ratio of the axial length Ta of the annular portion 4a to the axial length Td of the cylindrical roller 3 set to 45%, and departs from the spirit of the present invention. is there. That is, in this cage 4, since the annular portion 4 a is excessively thick, the rolling surface of the cylindrical roller 3 straddles the boundary position X between the raceway surface 2 a of the outer ring 2 and the chamfered portion 2 b. It touches. With such a configuration, local stress (edge stress) acts on the rolling surface of the cylindrical roller 3 from the boundary position X, and a fundamental problem occurs in the functional surface of the cylindrical roller bearing.

  The retainer 4 according to the fourth embodiment of the present invention shown in FIG. 7 is configured such that the outer diameter end of the escape portion 4b12 of the column portion 4b is inclined toward the inner diameter side from the distal end of the column portion 4b toward the base end portion. Is formed. Since other components and operational effects are the same as those in the first embodiment, the second embodiment, or the third embodiment, the same components as those in FIG. .

  The cage 4 according to the fifth embodiment of the present invention shown in FIG. 8 has an inclination in which the relief portion 4b12 of the column portion 4b is inclined in a direction in which the circumferential side surface approaches the circumferential center line r2 of the column portion 4b. It is formed to be a surface. This fifth embodiment may be combined with the fourth embodiment. Since other components and operational effects are the same as those in the first embodiment, the second embodiment, or the third embodiment, the same components as those in FIG. .

  In the first to fifth embodiments described above, the guide type of the cage is not limited to the rolling element guide, but may be an outer ring guide or an inner ring guide. That is, this invention does not ask | require the any guide form of a holder | retainer. 1, 5, and 6 exemplify NN type double row cylindrical roller bearings, the present invention can be similarly applied to NNU type and other bearing type double row cylindrical roller bearings. It is. Furthermore, the present invention is not limited to double-row cylindrical roller bearings but can be similarly applied to single-row cylindrical roller bearings and multi-row cylindrical roller bearings. Moreover, the above 1st-5th embodiment is this to the holder | retainer 4 by which escape part 4b12 is formed in all the some pillar parts 4b integrally extended to one side of the axial direction from the annular part 4a. Although the present invention is applied, the present invention can be similarly applied to the cage 4 in which the escape portions 4b12 are formed in every other or every second column portion 4b. It is.

  A double row cylindrical roller bearing (Example 1) in which the dimensional ratio of the axial length Ta of the annular portion 4a to the axial length Td of the cylindrical roller 3 shown in FIG. 1 is 30%, and the above dimensions shown in FIG. A double-row cylindrical roller bearing with a ratio of 35% (Example 2) and a conventional double-row cylindrical roller bearing with a dimensional ratio of 25% (Comparative Example 1) were produced and operated under air-oil lubrication. The temperature rise of the outer ring was compared. The test results are shown in FIG.

The test conditions are as follows.
Bearing product number: NN3020K
Cage material: Radial internal gap after resin assembly: -5 μm
Cylindrical roller: Roller diameter φ11mm, Roller length 11mm, Roller PCDφ126mm
Lubrication conditions: Air amount 30NL / min, Lubricating amount 0.02ml / 20min, Lubricating oil viscosity VG32, With housing cooling

  As shown in FIG. 9, in the rotation speed region where the bearing rotation speed is 6000 rpm (dmn = 760,000) or less, there was no significant difference in the outer ring temperature rise between Examples 1 and 2 and Comparative Example 1. In the rotation speed range from around 7000 rpm (dmn = 880,000) to 11,000 rpm (dmn = 1.38 million), there is a slight difference in the increase in outer ring temperature between Examples 1 and 2 and Comparative Example 1. In particular, when the bearing rotational speed exceeded 13000 rpm (dmn = 1.65 million), there was a significant difference in the temperature increase of the outer ring between Examples 1 and 2 and Comparative Example 1. That is, in the first and second embodiments, even when the bearing rotational speed exceeds 13000 rpm (dmn = 16.5 million), the outer ring temperature rises with a gradient substantially the same as the gradient in the lower rotational speed region. In Comparative Example 1, the outer ring temperature rapidly increased when the bearing rotation speed exceeded 13000 rpm (dmn = 16.5 million). From this result, it was concluded that Comparative Example 1 may be difficult to use appropriately in the high rotation speed region. In addition, when Example 1 and Example 2 are compared, even if Example 2 exceeds 15000 rpm (dmn = 1.89,000), Example 2 is substantially the same gradient as the gradient in a lower rotational speed region. However, in Example 1, the outer ring temperature rapidly increased when the bearing rotation speed exceeded 15000 rpm (dmn = 1.89 million). Therefore, the second embodiment can be used better in the higher rotation region than the first embodiment.

  Furthermore, a double row cylindrical roller bearing (Example 1) in which the dimensional ratio of the axial length Ta of the annular portion 4a to the axial length Td of the cylindrical roller 3 shown in FIG. A double row cylindrical roller bearing (Example 2) with a dimensional ratio of 35%, a conventional double row cylindrical roller bearing (Comparative Example 1) with a dimensional ratio of 25%, and a dimensional ratio of 15% The double-row cylindrical roller bearing (Comparative Example 2) and the double-row cylindrical roller bearing (Comparative Example 3) in which the dimensional ratio shown in FIG. The ratio of the point P at the base end side end position in the first lubricant reservoir 4b12 of the column part 4b shown in FIG. The comparison result is shown in FIG.

  As shown in FIG. 10, in Examples 1 and 2, for example, in the case where the rotational speed range of the bearing is 14000 rpm (dmn = 1.700,000), the above ratio is within 3%. In Comparative Example 1, when the bearing rotational speed is 14000 rpm (dmn = 1.700,000), the above ratio exceeds 4%, and in Comparative Example 2, the above ratio exceeds 7%. It has been. That is, in Examples 1 and 2, even when the bearing rotational speed is in the rotational speed region of 14000 rpm (dmn = 1.700,000), the amount of elastic deformation at the tip of the column portion of the cage does not cause a problem in use. On the other hand, in Comparative Examples 1 and 2, if the bearing rotational speed is in the rotational speed region of 14000 rpm (dmn = 1.7 million), the elastic deformation amount at the end of the column portion of the cage is inevitably difficult to use. End up. In Comparative Example 3, there is no problem with the amount of elastic deformation at the end of the column portion of the cage, but as described above, it causes structural problems and is difficult to use. In addition, the gradients of the five characteristic curves in the rotation speed region from 10000 rpm (dmn = 1.25 million) to 20000 rpm (dmn = 2.500,000) shown in FIG. When the ratio of the length in the axial direction is 30% or more, the ratio is gentle, but when the ratio is less than 30%, the slope is steep. Considering this, if the ratio is less than 30%, the setting of the axial length of the annular portion sensitively affects the limit rotational speed, so the ratio is 30% or more. It is convenient to set

It is sectional drawing which shows the principal part of the double row cylindrical roller bearing which concerns on 1st Embodiment of this invention. It is a perspective view which shows the principal part of the holder | retainer which concerns on 1st Embodiment of this invention. Fig.3 (a) is sectional drawing which shows the principal part of the holder | retainer concerning 1st Embodiment of this invention, FIG.3 (b) is the partial side view which looked at the holder from the front end side of the pillar part. . It is principal part sectional drawing which shows the effect | action of the holder | retainer which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the principal part of the double row cylindrical roller bearing which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the principal part of the double row cylindrical roller bearing which concerns on 3rd Embodiment of this invention. Fig.7 (a) is a perspective view which shows the principal part of the holder | retainer which concerns on 4th Embodiment of this invention, FIG.7 (b) is sectional drawing which shows the principal part of the holder | retainer. It is the partial side view which looked at the holder | retainer which concerns on 5th Embodiment of this invention from the front end side of the pillar part. It is a figure which shows a test result. It is a figure which shows an analysis result. Although not showing the embodiment of the present invention, it is a sectional view showing the important section of the double row cylindrical roller bearing relevant to the present invention. It is the partial side view which looked at the retainer in the conventional cylindrical roller bearing from the front end side of the column part. The figure which shows typically the state (solid line) when the pillar part of the cage | basket in the conventional cylindrical roller bearing is elastically deformed to the outer-diameter side by the effect | action of the centrifugal force at the time of high speed rotation, and the state (dotted line) before a deformation | transformation. It is. It is sectional drawing which shows the principal part of the conventional double row cylindrical roller bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 2a Outer ring raceway surface 2b Chamfered portion 3 of outer ring Cylindrical roller 4 Cage 4a Annular portion 4a1 Inner side surface 4b Column portion 4b1 Circumferential side surface 4b12 Escape portion 4b14 Roller guide portion Ta Axial direction of annular portion of cage Length Tb Axial length Td of cage column Axial length of cylindrical roller

Claims (7)

An inner ring, an outer ring, a plurality of cylindrical rollers rotatably disposed between the inner ring and the outer ring, and a synthetic resin cage, the cage comprising: an annular portion; and an inner portion of the annular portion A plurality of column portions extending in one axial direction from the side surface, and a plurality of pockets formed between the circumferential side surfaces of the column portions adjacent in the circumferential direction and rotatably holding the cylindrical rollers. In cylindrical roller bearings,
A cylindrical roller bearing characterized in that the axial length of the annular portion of the cage is set to 30 to 40% of the axial length of the cylindrical roller.   The cylindrical roller bearing according to claim 1, wherein the axial length of the column portion of the cage is set to 65 to 75% of the axial length of the cylindrical roller.   In the inner ring and / or outer ring, a chamfered portion is formed on the outer side in the axial direction of the raceway surface on which the cylindrical roller rolls, and the entire rolling surface of the cylindrical roller is a boundary position between the raceway surface and the chamfered portion. The cylindrical roller bearing according to claim 1, wherein the cylindrical roller bearing is disposed on an inner side in the axial direction.   The cylindrical roller bearing according to claim 3, wherein the chamfered portion is formed with an inclination angle of 10 to 30 ° with respect to a cylindrical surface constituted by the raceway surface.   A circumferential side surface of the column portion of the cage is formed as an arc surface along the rolling surface of the cylindrical roller on the inner peripheral portion on the proximal end side, and the column portion is on the outer diameter side by centrifugal force during rotation. A roller guide portion that guides the rolling surface of the cylindrical roller when elastically deformed, and retracts closer to the center in the circumferential direction of the column portion than the roller guide portion at the inner peripheral portion on the tip end side. The said pillar part has an escape part which does not produce a contact pressure of a rolling direction of the cylindrical roller and a radial direction when elastically deforming to the outer diameter side by centrifugal force at the time of rotation. The cylindrical roller bearing according to any one of 4.   6. The cylindrical roller bearing according to claim 5, wherein the axial length of the escape portion is set to 10% to 35% of the axial length of the cylindrical roller.   The cylindrical roller according to any one of claims 1 to 6, wherein the cylindrical rollers are arranged in a plurality of rows, and each row of the cylindrical rollers is individually held by the cage. bearing.