JP5789973B2 - Cylindrical roller bearings and spindles for machine tools - Google Patents

Description

  The present invention relates to a cylindrical roller bearing and a spindle device for a machine tool, and more particularly to a cylindrical roller bearing used for a spindle of a machine tool that rotates at high speed, a high-speed motor, and the like, and a spindle device for a machine tool using the same.

  For example, spindle devices of machine tools such as machining centers, CNC lathes, and milling machines tend to be operated at high speed for reasons such as increasing the machining efficiency and accuracy of workpieces.

  Generally, in a spindle device of a machine tool, the spindle is rotatably supported with respect to a housing by rolling bearings arranged on the front side and the rear side, respectively, and the front rolling bearing normally does not allow the axial displacement of the spindle. The rear rolling bearing absorbs or releases the amount of axial expansion of the main shaft due to heat during operation, and thus has a structure that allows the axial displacement of the main shaft (free side).

  Cylindrical roller bearings are used as rolling bearings supported on the free side of the main shaft. As the cylindrical roller bearing 101, for example, as shown in FIG. 10, a cage 105 that holds a plurality of cylindrical rollers 104 disposed between an outer ring 102 and an inner ring 103 protrudes from the outer peripheral surface of a column part 105b. The outer ring is guided by using the outer peripheral surfaces of the pair of rim portions 105 a as the guide portion 106.

  In the spindle device, the rolling bearing is lubricated by a lubrication method such as oil mist lubrication, air-oil lubrication, direct injection lubrication, jet lubrication, or grease lubrication according to usage conditions.

  In addition, as a bearing used under high temperature and high pressure where lubricity such as grease cannot ensure lubrication, a cage is made of a lubricating material, and the guide unit contacts and guides the raceway of the raceway. (For example, refer to Patent Document 1) and those in which a solid lubricant is disposed in a recess formed on the outer peripheral surface of a cage and the solid lubricant is slidably contacted with a raceway surface ( For example, see Patent Document 2.) Furthermore, in a split type retainer configured by combining a plurality of arc-shaped retainer elements in series in the circumferential direction, a structure in which a guide portion is provided in a part of a column portion is disclosed (for example, a patent) Reference 3).

Japanese Patent Laid-Open No. 9-49525 JP 2003-239993 A JP 2009-97525 A

  By the way, in the rolling bearing that supports the main shaft, if the lubricant dischargeability inside the bearing is poor, the inside of the bearing becomes excessively lubricated, and abnormal temperature rise or temperature pulsation occurs due to stirring heat. Therefore, if the bearing temperature rises, the rolling bearing may be damaged. In particular, in the case of a cylindrical roller bearing, the rolling contact portion between the inner ring raceway surface and the outer ring raceway surface and the cylindrical roller is in line contact, so that the temperature rises more easily than a point contact ball bearing.

  Furthermore, when grease-lubricating a cylindrical roller bearing, a so-called running-in operation in which the enclosed grease is evenly distributed inside the bearing or surplus grease is moved to the periphery of the bearing is indispensable.

  For this reason, in the case of a cylindrical roller bearing having an outer ring guide retainer as shown in FIG. 10, the clearance between the guide surface of the retainer and the outer ring raceway surface is narrow, so that the lubricant tends not to be discharged easily. Also, it takes time to run the grease.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cylindrical roller bearing capable of smoothly discharging a lubricant and suppressing abnormal temperature rise and temperature pulsation, and the same. It is providing the spindle apparatus for machine tools which used the.

The above object of the present invention can be achieved by the following constitution.
(1) an outer ring having an outer ring raceway surface formed on the inner circumferential surface;
An inner ring having an inner ring raceway surface formed on the outer peripheral surface;
A plurality of cylindrical rollers arranged to roll freely between the outer ring raceway surface and the inner ring raceway surface;
A cage having a pair of annular rim portions and a plurality of column portions connecting the pair of rim portions in the axial direction, and forming a plurality of pockets for rotatably holding the plurality of cylindrical rollers;
A cylindrical roller bearing comprising:
The retainer has guide portions that protrude in the radial direction from the outer peripheral surface or inner peripheral surface of the rim portion over the entire circumferential direction on the outer peripheral surface or inner peripheral surface of the pillar portion at least at three locations. And the guide is guided by the raceway,
The guide surface of the guide portion is formed over the entire circumferential direction of the outer peripheral surface or inner peripheral surface of the column portion by an arc surface of the same radius with the center of curvature of the cage as the center of curvature.
When the axial width of the cylindrical roller is L, the axial width of the pocket is P, and the difference between the axial width L of the cylindrical roller and the axial width P of the pocket is ΔP, the axial direction of the guide portion The cylindrical roller bearing characterized in that the width M is equal to or less than the axial width P of the pocket and is set to M ≦ L−ΔP.
(2) A spindle device for a machine tool, wherein the spindle is rotatably supported by the cylindrical roller bearing described in (1).

  According to the cylindrical roller bearing of the present invention, the cage has guide portions that protrude in the radial direction from the outer peripheral surface or inner peripheral surface of the rim portion on the outer peripheral surface or inner peripheral surface of at least three column portions, Since the guide ring guides the raceway, the lubricant can be discharged smoothly, and abnormal temperature rise and temperature pulsation can be suppressed.

  Further, according to the spindle device for machine tools of the present invention, the spindle is rotatably supported by the cylindrical roller bearing of the present invention in which abnormal temperature rise and temperature pulsation are suppressed. It is possible to keep the accuracy at a high level.

It is a longitudinal cross-sectional view which shows the spindle apparatus for machine tools with which the cylindrical roller bearing of this invention is applied. It is sectional drawing of the cylindrical roller bearing of FIG. (A) is a partial top view of a holder | retainer, (b) is sectional drawing along the III-III line of (a). It is sectional drawing of the modification which changed the axial direction width | variety of the guide part with respect to the cylindrical roller bearing of FIG. It is sectional drawing of the other modification which changed the axial direction width | variety of the guide part with respect to the cylindrical roller bearing of FIG. It is the modification which changed the number of guide parts with respect to the cylindrical roller bearing of FIG. 2, (a) is a partial top view of a holder | retainer, (b) is along VI-VI of (a). FIG. It is sectional drawing of the modification which changed the shape of the guide part with respect to the cylindrical roller bearing of FIG. 1 is a cross-sectional view of a cylindrical roller bearing in which the present invention is applied to an inner ring guide type cage. (A) is a sectional view of a cylindrical roller bearing to which an inner ring guide type cage is applied in the cylindrical roller bearing of FIG. 2, and (b) is an outer ring guide type cage in the cylindrical roller bearing of FIG. It is sectional drawing of the applied cylindrical roller bearing. It is sectional drawing of the conventional cylindrical roller bearing.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a cylindrical roller bearing according to the invention and a spindle device for a machine tool using the same will be described in detail based on the drawings.

  FIG. 1 is a longitudinal sectional view of a spindle device for machine tools to which a cylindrical roller bearing of the present invention is applied. As shown in FIG. 1, the main shaft 11 of the main shaft device 10 is supported in a main shaft housing 13 by an angular ball bearing 12 and a cylindrical roller bearing 1 which are rolling bearings.

  The spindle housing 13 is a housing body 14, a front bearing housing 15 that is fitted and fixed to the front end (left side in the figure) of the housing body 14, and a rear side (right side in the figure) that is fitted and fixed to the rear side of the housing body 14. A side bearing housing 16, an outer ring pressing member 17 provided at the end of the front bearing housing 15, and a cover 19 provided at the rear of the rear bearing housing 16 are provided.

  The main shaft 11 is supported by two angular ball bearings 12, 12 fitted in the front bearing housing 15 and one cylindrical roller bearing 10 fitted in a sleeve 18 provided inside the rear bearing housing 16. Thus, the spindle housing 13 is rotatably supported. A plurality of outer ring spacers 20 are arranged between the outer rings of the two angular ball bearings 12 and 12 and on the outer side in the axial direction of the outer ring, and between the inner rings and between the inner rings on the outer side in the axial direction of the inner ring. A seat 21 is arranged. Further, a plurality of outer ring spacers 30 and 30 are arranged on both sides in the axial direction of the outer ring 2 (see FIG. 2) of the cylindrical roller bearing 1, and on both sides in the axial direction of the inner ring 3 (see FIG. 2). A plurality of inner ring spacers 31, 31 are arranged.

  A rotor 40 is fitted and fixed to a substantially central portion of the main shaft 11 in the axial direction. On the outer peripheral surface side of the rotor 40, a stator 41 is coaxially arranged with a predetermined distance. The stator 41 is fixed to the housing body 14 via a stator fixing member 42 disposed on the outer peripheral surface side of the stator 41. A groove 43 is formed between the housing body 14 and the stator fixing member 42 in a direction along the circumferential direction of the main shaft 11. A coolant for cooling the stator 41 flows in the plurality of grooves 43.

  Similarly, a groove 44 is formed between the housing main body 14 and the front bearing housing 15 and on the outer peripheral side of the angular ball bearing 12 to allow the coolant for cooling the housing and the bearing to flow.

  The two angular ball bearings 12 and 12 and the cylindrical roller bearing 1 are lubricated with grease, and the housing main body 14, the front bearing housing 15 and the rear bearing housing 16 are grease discharge passages for discharging the grease out of the apparatus. 45 is formed. These bearings 12, 12, and 1 may be grease replenishment lubrication in which grease is replenished to the bearings from the outside of the bearing using a lubrication device, but in this embodiment, grease is preliminarily sealed inside the bearings. Grease lubrication for lubricating the bearings 12, 12, 1 is performed.

  The cylindrical roller bearing 1 shown in FIG. 2 has an outer ring 2 having no flanges on the inner circumferential surface of which the outer ring raceway surface 2a is formed, an inner ring raceway surface 3a is formed on the outer circumferential surface, and an inner ring raceway surface 3a on both sides. An inner ring 3 having a portion 3b, a plurality of cylindrical rollers 4 rotatably disposed between the outer ring raceway surface 2a and the inner ring raceway surface 3a, and a plurality of pockets for rotatably holding the plurality of cylindrical rollers 4, respectively. And an outer ring guide type cage 5 forming 5c.

  As shown also in FIG. 3, the cage 5 has a pair of annular rim portions 5a and a plurality of column portions 5b that connect the pair of rim portions 5a in the axial direction, and is formed by injection molding a resin material. Is done. The cage 5 has a plurality of guide portions 6 projecting radially outward from the outer peripheral surface of the rim portion 5 a on the outer peripheral surface of each column portion 5 b, and the outer ring is guided by these guide portions 6. The outer peripheral surface of the guide portion 6 constituting the guide surface is formed along an arc surface with the center of the cage 5 as the center of curvature, and a guide gap (diameter gap) g between the guide surface and the outer ring raceway surface 2a is formed. 0.20 to 1.0 mm.

  The axial width M of the guide 6 is less than the difference between the axial width L of the cylindrical rollers 4 and the axial width P of the pocket 5c by ΔP (ΔP = PL). (That is, M ≦ L−ΔP). In this case, even if the cage 5 moves in the axial direction by the clearance of the pocket 5c, the grease is not scraped off by the cage 5, and the grease can be held in the vicinity of the cylindrical roller 4.

  The axial width M of the guide portion 6 may be set to be equal to or smaller than the axial width P of the pocket 5c in consideration of scraping of grease by the cage 5 (see FIG. 4). The direction width L is preferably set to be equal to or smaller than that (see FIG. 5), but as shown in FIG. 2, it is more preferably set to be equal to or smaller than L−ΔP.

  On the other hand, the axial width M of the guide portion 6 is preferably 1/3 or more of the axial width L of the cylindrical roller 4, more preferably the axial direction, considering the unevenness of the guide portion 6 due to the inclination of the cage 5. It is preferable that it is 1/2 or more of the width L.

  In the cylindrical roller bearing 1 configured as described above, the guide portion 6 is provided on the outer peripheral surface of the column portion 5b, whereby the grease can be discharged smoothly and abnormal temperature rise can be suppressed. In addition, the time for running the grease can be shortened. Furthermore, when the machine tool has not been used for a long time, even if the grease accumulates inside the bearing, the grease is better discharged, and the possibility that the bearing will be damaged due to abnormal temperature rise is reduced.

  Further, the cylindrical roller bearing 1 of the present embodiment has a cylindrical roller 4 having a guide portion 106 of the cage 105 which is located near both axial sides of the cylindrical roller 104 as compared with the cylindrical roller bearing 101 as shown in FIG. A grease reservoir G can be formed in the vicinity. Since grease contains a base oil in a thickener, the base oil can move to some extent within the grease when an action such as a temperature rise is applied, and the grease reservoir G is connected to the outer ring raceway surface 2a. If so, the surface tension effect and the wettability effect also act, and it is easy to guide the grease to the rolling contact portion between the outer ring raceway surface 2a and the rolling surface of the cylindrical roller 4, and the occurrence of oil film breakage can be suppressed. In this embodiment, a large grease reservoir G can be secured inside the bearing, and more grease can remain inside the bearing. Therefore, even with the grease lubrication with the encapsulated grease as in the present embodiment, a sufficient lubrication life can be ensured.

  Further, the main shaft 11 of the machine tool main spindle device 10 is mainly in the case of inner ring rotation, and the temperature distribution of the main shaft 11 is such that the temperature of the rotating side member (inner ring side) is higher than the temperature of the stationary side member (outer ring side). Get higher. In the case of a so-called motor built-in main shaft in which a motor is provided between the front bearing (fixed side) and the rear bearing (free side) of the main shaft 11 as in this embodiment, the influence of heat generation of the motor is added. The Since the cylindrical roller bearing 1 of the present embodiment can increase the allowable sliding amount of the inner ring 3 relative to the outer ring 2 (Δr1 <Δr2), compared with the cylindrical roller bearing 101 shown in FIG. 10, the main shaft 11 expands due to a temperature rise. Even if the inner ring 3 moves to the rear of the main shaft with respect to the outer ring 2, it is possible to prevent the guide portion 6 of the cage 5 from being detached from the outer ring raceway surface 2a.

  In addition, this invention is not limited to each embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.

  In the above embodiment, the guide portions 6 are provided in all the column portions 5b. However, the guide portions 6 may be provided in at least three column portions 5b at equal intervals in the circumferential direction. For example, as shown in FIG. The guide part 6 may be provided on every other pillar part 5b.

  Moreover, as shown in FIG. 7, the guide part 6 may have the recessed part 6a which is formed along the circumferential direction in the axial direction intermediate part, and comprises a grease reservoir. The grease can be accumulated in the recess 6a to improve the lubrication life, and the grease can be discharged from the recess 6a in the axial direction to improve the leveling of the grease.

  Furthermore, the present invention also provides the same effects as those of the above embodiment when applied to the inner ring guide type cage 5. That is, as shown in FIG. 8, a cylinder having an outer ring 2 in which an outer ring raceway surface 2a and a flange portion 2b are formed on an inner peripheral surface, and a wrinkleless inner ring 3 in which an inner ring raceway surface 3a is formed on an outer peripheral surface. In the roller bearing 1, the guide portion 6 is provided on the inner peripheral surface of the column portion 5b so as to protrude radially inward from the inner peripheral surface of the rim portion 5a.

  Further, the cage 5 shown in FIG. 2 and FIG. 8 is configured to be guided by the outer ring 2 or the inner ring 3 having no flange, but may be configured to be guided by the outer ring 2 or the inner ring 3 having the flange portions 2b and 3b. Good. That is, as shown in FIG. 9 (a), it may be an inner ring guide type cage 5 in which a guide portion 6 is disposed in a raceway groove formed by the inner ring raceway surface 3a and the flange portions 3b on both sides. Further, as shown in FIG. 9B, an outer ring guide type retainer 5 may be used in which guide portions 6 are arranged in a raceway groove formed by the outer ring raceway surface 2a and the flange portions 2b on both sides.

  In the spindle device 10 for machine tools of the present invention, an example in which two angular ball bearings 12 and 12 are arranged on the front side of the motor and one cylindrical roller bearing 1 is arranged on the rear side is given. The arrangement and number are not limited to the above, and can be arbitrarily set. For example, one cylindrical roller bearing and two angular ball bearings may be arranged on the front side of the motor, one cylindrical roller bearing may be arranged on the rear side, and four angular ball bearings may be arranged on the front side. One cylindrical roller bearing may be arranged on the side.

  Further, the lubricant for lubricating the angular ball bearings 12 and 12 and the cylindrical roller bearing 1 is not limited to the grease as in the present embodiment, and may be a lubricating oil.

DESCRIPTION OF SYMBOLS 1 Cylindrical roller bearing 2 Outer ring 2a Outer ring raceway surface 3 Inner ring 3a Inner ring raceway surface 4 Cylindrical roller 5 Cage 5a Rim part 5b Column part 5c Pocket 6 Guide part 10 Main shaft apparatus 11 Main axis

Claims (2)

An outer ring having an outer ring raceway surface formed on the inner circumferential surface;
An inner ring having an inner ring raceway surface formed on the outer peripheral surface;
A plurality of cylindrical rollers arranged to roll freely between the outer ring raceway surface and the inner ring raceway surface;
A cage having a pair of annular rim portions and a plurality of column portions connecting the pair of rim portions in the axial direction, and forming a plurality of pockets for rotatably holding the plurality of cylindrical rollers;
A cylindrical roller bearing comprising:
The retainer has guide portions that protrude in the radial direction from the outer peripheral surface or inner peripheral surface of the rim portion over the entire circumferential direction on the outer peripheral surface or inner peripheral surface of the pillar portion at least at three locations. And the guide is guided by the raceway,
The guide surface of the guide portion is formed over the entire circumferential direction of the outer peripheral surface or inner peripheral surface of the column portion by an arc surface of the same radius with the center of curvature of the cage as the center of curvature.
When the axial width of the cylindrical roller is L, the axial width of the pocket is P, and the difference between the axial width L of the cylindrical roller and the axial width P of the pocket is ΔP, the axial direction of the guide portion The cylindrical roller bearing characterized in that the width M is equal to or less than the axial width P of the pocket and is set to M ≦ L−ΔP. A spindle device for a machine tool, wherein the spindle is rotatably supported by the cylindrical roller bearing according to claim 1.

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