JP5034962B2 - Rolling bearing - Google Patents

Description

  The present invention includes, for example, industrial machinery, robot joints and turning mechanisms, machine tool spindles, rotary tables and spindle turning mechanisms, medical equipment, semiconductor / liquid crystal manufacturing apparatuses, optical and optoelectronic devices, and the like. The present invention relates to a rolling bearing used in the above.

  As a conventional rolling bearing, a synthetic resin crown-shaped cage provided with a cutting portion at one place in the circumferential direction has been proposed (for example, see Patent Documents 1 and 2). In the rolling bearing described in Patent Document 1, by providing a cutting portion, the tension force generated between the ball and the pocket due to the difference in thermal expansion coefficient between the inner and outer rings and the ball and the cage is alleviated. It is described that the wear and the like are prevented.

Further, in the rolling bearing described in Patent Document 2, a cutting part is provided at one place in the circumferential direction, and the circumferential width of the cutting part is set as an extension of the cage due to a change in temperature and a change in water absorption rate. It is described to secure a guide clearance.
JP 2003-336640 A JP 2006-226696 A

  By the way, in the rolling bearing described in Patent Document 1, the ball guide method is adopted, and the radial clearance between the ball and the pocket is set to be small. (For example, when the inner ring, outer ring and ball are made of bearing steel, and the cage is made of synthetic resin such as polyamide resin) It is difficult to expand, and the relative expansion is directed in the circumferential direction.

  As a result, the clearance in the circumferential direction of the cutting part of the cage is reduced, and if the temperature rise value of the bearing is high, including the operating environment temperature, the circumferential end surfaces of the cutting part of the cage are stretched and interfered, There is a problem that heat generation, wear, and damage occur in the interference portion. In addition, when the cage is formed of a general general-purpose synthetic resin such as a polyamide resin, the cage may expand by absorbing moisture in the air, and the amount of expansion due to water absorption is also a problem.

  Further, in the rolling bearing described in Patent Document 2, the circumferential width of the cut portion is defined as the extension of the cage (temperature expansion + water absorption expansion) due to temperature change and water absorption change. However, under conditions where the temperature rise is small or the atmosphere is dry, the change in the circumferential width of the cut part is small, and the circumferential distance between the balls at the part across the cut part is It becomes larger than the circumferential distance between the balls, and uneven distribution in the circumferential direction of the balls occurs.

  If the balls are not evenly distributed in the circumferential direction, the radial rigidity of the bearing will be non-uniform in the circumferential phase (decrease in rigidity due to the phase of the unevenly distributed portion of the ball in the circumferential direction). A swing corresponding to the revolution period of the ball, a so-called NRRO value (a cycle of about once per two rotations of the inner ring) increases. In particular, when this bearing is used in a rotation support part such as a spindle of a machine tool, a rotary table, and a turning mechanism part of the spindle that require rotational accuracy, the rotation of the rotary shaft becomes large (NRRO value is large), and milling There is a problem that a striped pattern is generated on the processed surface in machining, and a stitching defect on the processed surface or a deterioration in roundness occurs in lathe processing.

  The present invention has been made in order to eliminate such inconveniences, and the object of the present invention is to reduce rolling around the rotating shaft by suppressing the uneven distribution of the rolling elements in the circumferential direction. It is to provide a bearing.

The above object of the present invention can be achieved by the following constitution.
(1) An inner ring having an inner ring raceway surface on an outer peripheral surface, an outer ring having an outer ring raceway surface on an inner peripheral surface, and a plurality of rolling elements provided in a freely rollable manner between the inner ring raceway surface and the outer ring raceway surface. In a rolling bearing provided with a synthetic resin cage having a cutting portion formed in at least one place in the circumferential direction and holding the plurality of rolling elements at substantially equal intervals in the circumferential direction,
The retainer absorbs moisture in the resin up to a predetermined equilibrium moisture content and expands in advance , and absorbs moisture to the predetermined equilibrium moisture content and expands in a circumferential width of the cutting portion. features There is formed to be substantially equal to the elongation caused by the predetermined temperature change of the cage, thereby that you suppress circumferential unequal distribution of the rolling element width by reducing the cutting portion Rolling bearing.
(2) The rolling bearing according to (1), wherein the cage is a crown type cage.
(3) The rolling bearing according to (1) or (2), wherein the rolling element is a ball.
(4) The rolling bearing according to (1) or (2), wherein the rolling element is a cylindrical roller.
(5) The rolling bearing according to any one of (1) to (4), wherein grease is sealed in a bearing space between the inner ring and the outer ring.
(6) The rolling bearing according to (5), further comprising a contact-type or non-contact-type seal member disposed at an axial end portion on the fixed ring side of the inner ring and the outer ring.
(7) The rolling bearing according to (5) or (6), wherein the grease is enclosed in the bearing space after the cage has absorbed water up to the predetermined equilibrium moisture content.
(8) The rolling bearing according to any one of (1) to (4), wherein an oil film is formed on a surface of the cage.

  According to the rolling bearing of the present invention, the cage is formed so that the circumferential width of the cutting portion is substantially equal to the extension due to the predetermined temperature change of the cage in a state where water is absorbed to a predetermined equilibrium moisture content. Therefore, the uneven distribution of the rolling elements in the circumferential direction can be suppressed, and the swinging of the rotating shaft can be suppressed to a small value.

  Hereinafter, rolling bearings according to embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIG. 1, a rolling bearing 10 (hereinafter also referred to as a narrow ball bearing 10) of this embodiment is an angular ball bearing, and two rows of angular ball bearings are combined in the back (contact angle is C). Array). Each rolling bearing 10 is freely rollable between an inner ring 11 having an inner ring raceway surface 11a on an outer peripheral surface, an outer ring 12 having an outer ring raceway surface 12a on an inner peripheral surface, and an inner ring raceway surface 11a and an outer ring raceway surface 12a. A plurality of balls (rolling elements) 13 provided, and a cutting portion 14 (see FIG. 4) is formed at one place in the circumferential direction, and the plurality of balls 13 are made of synthetic resin that holds the balls 13 in the circumferential direction at substantially equal intervals. The crown-shaped cage 15 is provided. Further, non-contact type seal members 16 are mounted on the inner peripheral surfaces of the outer ends of the outer rings 12 of the two rows of narrow ball bearings 10 in the axial direction. The seal member 16 may be a contact type, and the material and shape are not particularly limited.

  In this embodiment, in order to save space in the axial direction, the axial sectional width B and the radial sectional height H of the rolling bearing 10 (= (outer ring outer diameter D−inner ring inner diameter d) / 2) and The cross-sectional dimension ratio (B / H) is set to B / H <0.63.

  B / H is theoretically B / H> 0, but in reality, considering the design, selection, etc. of the ball diameter, cage, and seal member to be used, B / H> 0. 10, preferably B / H> 0.20, more preferably B / H> 0.30.

  Further, in the case of standard size ball bearings defined by the International Organization for Standardization (ISO), those with a B / H of around 1.0 account for the majority. Therefore, if B / H <0.5 is set, the narrow ball bearings 10 for two rows can be disposed in the width direction space for about one row of standard ball bearings, and space saving can be achieved.

  In the case of angular contact ball bearings, only one axial load can be received in one row and moment load cannot be received. However, by combining two or more rows, the axial load and moment load in both directions can be reduced. Load becomes possible. In addition, since preload can be applied, it is possible to save space and increase radial rigidity, axial rigidity, moment rigidity, and the like.

  Moreover, if B / H <0.25, it is possible to arrange four rows of narrow ball bearings in a space in the width direction of about one row of standard ball bearings with further space saving, and further increase rigidity. Improvement is possible.

Here, FIG. 10 and FIG. 11 show the ultra-thin ball bearings (bearing inner diameter: φ38.1 mm, bearing outer diameter: φ47.625 mm, bearing width: 4.762 mm, standard sectional ratio ( B / H) = 1) as a reference, the radius of the inner and outer ring rings when the bearing inner diameter is changed without changing the bearing outer diameter and bearing width, that is, when the value of (B / H) is changed. direction of deformation characteristics (see FIG. 8: an inner ring of illustration) and radial cross-sectional secondary moment I: shows the result of comparison (see FIG. 9 calculated by I = bh ^3/12).

  FIGS. 12 and 13 show ultra-thin ball bearings that are used as standard (bearing inner diameter: φ63.5 mm, bearing outer diameter: φ76.2 mm, bearing width: 6.35 mm, cross-sectional dimension ratio = 1). ) And the radial deformation characteristics and radius of the inner and outer ring rings when the bearing inner diameter is changed without changing the bearing outer diameter and bearing width, that is, when the value of (B / H) is changed. The result of having compared the cross-sectional secondary moment I of the direction is shown.

  In any of the bearings, (B / H) = 0.63 or less, and the change in the rigidity increase rate gradient is noticeable. That is, when (B / H) = 0.63, the increase in the secondary moment I of the cross section becomes significant, and the decrease in the deformation amount of the inner and outer ring in the radial direction becomes saturated. This can prevent bearing deformation due to lathe processing and grinding processing forces when manufacturing inner and outer rings, which is a problem with conventional ultra-thin ball bearings, and improves bearing accuracy such as roundness and uneven thickness. be able to.

  Also, by setting (B / H) to less than 0.63, when the bearing is incorporated in the shaft or housing (especially when it is assembled by clearance fitting with the shaft or housing), the outer ring is pressed against the end face, and the inner ring is the bearing. It is possible to suppress deformation of the inner and outer rings (especially worsening of roundness) when they are fixed with nuts, etc., as well as torque failure and rotation accuracy caused by deformation, or problems such as increased heat generation, wear and seizure. Can be prevented.

  Furthermore, by setting (B / H) to less than 0.63, the width of the bearing is about half that of a conventional standard single-row ball bearing, so the ball diameter is also about half that of a conventional ball bearing. Conversely, the number of balls per row increases at least twice, and the bearing stiffness increases compared to conventional ball bearings.

  The dimension series defined by the International Organization for Standardization (ISO) is 18 (for example, 6820), 19 (for example, 6938), 10 (for example, 7016A), 02 (for example, 7224C), 03 (for example, 7350A). In the case of standard size ball bearings such as the above, when the inner diameter of the bearing is φ5 mm to φ500 mm, the cross-sectional dimension ratio (B / H) is B / H = 0.63 to 1.17. Since the ball bearing 10 is narrow in the axial direction, it does not correspond to the above-described cross-sectional dimension ratio.

  In the narrow ball bearing 10 of this embodiment, in order to increase the load capacity and rigidity of the bearing, the pitch between the balls 13 adjacent in the circumferential direction is made as small as possible, and the number of balls is increased as much as possible. In a normal ball bearing, the number of balls is at most about 30 to 40 or less per row, but in this embodiment, 50 or more, preferably 60 or more, more preferably 70 or more per row. .

  In the case of an angular contact ball bearing, the contact angle is approximately 60 ° or less, preferably 50 ° or less in order to suppress the ball and the inner / outer ring groove contact portion from riding on the shoulder portion of the inner / outer ring groove when a large moment load is applied. More preferably, it is 40 ° or less, but if it is less than 20 °, the allowable axial load and moment rigidity are lowered, which is not preferable. The appropriate ball diameter in the present embodiment varies depending on whether or not a seal member or the like is mounted. However, in order to increase rigidity, if the ball diameter is extremely reduced, the surface pressure between the contact portions between the balls and the track grooves of the inner and outer rings is reduced. In general, in the case of a single row, 30 to 90% of the bearing width (B), and in the case of a double row, 15 to 45% of the bearing width (B2) is desirable. .

  Furthermore, in this embodiment, the axial pitch of the balls 13 is shifted as much as possible to the opposite side of the combination side end face (FIG. 1: X1> X2), and the annular portion 17 (see FIGS. 2 to 5) of the cage 15 is a bearing. It arrange | positions so that it may become a combination end surface side, the axial direction thickness of the annular part 17 is enlarged, and the distance between action points for raising moment rigidity can be taken large.

  The material of the bearing is not particularly limited, such as standard bearing steel (SUJ2 or SUJ3), but if necessary, these materials can improve mechanical properties such as dimensional stability and wear resistance of the bearing. In order to achieve this, sub-zero processing may be performed on at least one of the inner ring 11 and the outer ring 12.

  As a sub-zero treatment method, for example, immediately after quenching, an atmosphere of about −150 ° C. is formed using liquid nitrogen, and tempering is performed after the sub-zero treatment. Then, the sub-zero process and the tempering process are repeated several times. In the sub-zero treatment using liquid nitrogen as the cooling solvent, the number of repetitions may be at most about 3. Residual austenite (γR) in the structure is transformed into martensite by the sub-zero treatment. In addition, since the stabilization of the crystal grains is promoted, this improves the mechanical properties such as prevention of dimensional change with time and wear resistance.

  In the case of the present embodiment, since the axial widths of the inner ring 11 and the outer ring 12 are narrow, there is a tendency that dimensional changes such as warpage and roundness failure tend to occur. Accordingly, the sub-zero treatment can suppress the dimensional change with time, and in particular, in rotation support parts such as a rotary table of a machine tool, a spindle turning mechanism part, and a rotary mechanism part such as a drum of a printing machine that require bearing accuracy. When the narrow ball bearing 10 of the present embodiment is used, it is possible to prevent malfunctions of the equipment due to deterioration of the bearing accuracy, and it is possible to maintain a good function in the long term.

  For example, in vacuum applications and corrosive environments, in addition to bearing steel, stainless steel materials that are corrosion resistant materials (for example, martensitic stainless steel materials such as SUS440C, austenitic stainless steel materials such as SUS304, precipitation of SUS630, etc.) Hardened stainless steel material), titanium alloy or ceramic material (for example, Si3 N4, SiC, Al2 O3, ZrO2 etc.) may be employed.

  The lubrication method is not particularly limited, and mineral oil grease or synthetic oil grease (for example, lithium or urea) or oil can be used in a general usage environment. Oil, or a solid lubricant such as fluororesin or MOS2 can be used.

  Further, as shown in FIGS. 2 to 5, the crown-shaped cage 15 used in the present embodiment has an annular portion 17 and one end portion in the axial direction of the annular portion 17 at equal intervals in the circumferential direction. And a spherical pocket portion 19 that holds the ball 13 so as to be able to roll in the circumferential direction between the column portions 18. In addition, a cutting portion 14 (see FIG. 4) having a predetermined circumferential width is formed at one column portion 18 in the circumferential direction. In the present embodiment, the entrance portion of the pocket portion 19 is slightly smaller than the ball diameter and has a catching allowance (pachin allowance). Thus, when the retainer 15 is assembled to the inner ring 11 and the outer ring 12, the ball 13 The assembly of the bearing is made easy by preventing the drop of the bearing.

  For example, a polyamide resin such as polyamide 46, polyamide 6, polyamide 66, or polyamide 6T is used as the material of the cage 15, but a synthetic resin material such as polyacetal or polyphenylene sulfide may be used. As needed, it is good also as a material which mixed reinforcing materials, such as glass fiber and carbon fiber, in the synthetic resin material. The shape of the cage 15 is not limited to this embodiment, and can be changed as appropriate.

  Here, in the present embodiment, in the state where the cage 15 has absorbed water up to the equilibrium moisture content, the circumferential width ΔL of the cutting portion 14 of the cage 15 is the extension due to a predetermined temperature change of the cage 15. It is formed so as to be substantially equal.

  That is, when the circumferential width ΔL of the cutting portion 14 in a state where the cage 15 is wetted to the equilibrium moisture content, when the bearing rises to a predetermined temperature, between the bearing parts (for example, the inner ring 11, the outer ring 12 and the ball) 13 is a bearing steel and the cage 15 is made of a synthetic resin such as polyamide resin), the clearance in the circumferential direction of the cut portion 14 is 0 or less due to the relative expansion of the cage 15 due to the difference in coefficient of linear expansion. Negative).

  Thus, in this embodiment, since the expansion | swelling part by water absorption is previously added to the circumferential direction width | variety of the cutting | disconnection part 14, the part of the cutting | disconnection part 14 after making the cage | basket 15 water-containing to the equilibrium moisture content by that amount. The circumferential width ΔL can be reduced. Thereby, even in the condition where the temperature rise is small or the dry atmosphere condition, the uneven distribution in the circumferential direction of the balls 13 can be suppressed, and as a result, the rotation of the rotating shaft can be suppressed small.

  Further, even when the temperature rise value of the bearing including the use environment temperature is high, the end faces in the circumferential direction of the cutting portion 14 of the cage 15 may interfere with each other if the temperature rise is within a predetermined temperature rise. In addition, even if the temperature rises to a predetermined temperature or more temporarily, resulting in contact interference between the end faces, and further, relative expansion of the cage 15 occurs in the radial direction, The maximum temperature-predetermined temperature), and the amount until the radial clearance between each ball 13 and the pocket portion 19 of the cage 15 becomes negative is not so large. The tension force between 19 does not work, and stable rotation performance can be obtained.

  More specifically, for example, a resin cage produced by injection molding (for example, polyamide 66 resin (grade with no reinforcing material added) generally widely used) is in an absolutely dry state immediately after molding, and contains water. The rate is almost 0%. However, when this cage is stored in the air, it absorbs moisture in the air and gradually expands.

  As shown in FIG. 6, in polyamide 66 resin (grade without addition of reinforcing material), the equilibrium moisture content is around 3% in air with a relative humidity of usually 50 to 70%. The rate of change reaches 0.5 to 0.6%. However, once the equilibrium moisture content is reached, the moisture content hardly changes under the general environmental conditions in the atmosphere.

Further, for example, even if some temperature change or humidity change occurs due to a temperature rise due to rotation of the bearing, the moisture content hardly changes in a short time. Even if the use application of the narrow ball bearing 10 of this embodiment is rocking rotation, reciprocating rotation, or continuous rotation, the dmn value of the bearing (dm: ball pitch circle diameter (mm) × n: rotational speed (Min ⁻¹ )) is about 200 to 300,000 or less, and the rotational speed of the bearing is relatively low. Therefore, the temperature rise value due to heat generation of the bearing itself is small, and the moisture content hardly changes. In addition, a lubricant such as oil or grease is supplied to the bearing during operation or sealed in advance, and an oil film is always formed on the surface of the cage 15, which causes evaporation and intrusion of moisture. Hateful. In particular, in the case of grease lubrication, since a considerable amount of grease is filled in the internal space of the bearing, there is an advantage that it is extremely difficult to be affected by changes in atmospheric conditions (such as humidity changes).

  In the present embodiment, when the cage 15 that has reached the equilibrium moisture content is once incorporated in the bearing, the moisture content can be maintained even if some humidity and temperature changes occur under general environmental conditions in the atmosphere. The change is less likely to occur, and the dimensional change (during use) is achieved by allowing the moisture content to be absorbed into the resin up to the equilibrium moisture content after the cage 15 has been injection molded or cut. Can be minimized.

  On the other hand, when the cage is incorporated in the bearing while being kept in an absolutely dry state, elongation due to moisture expansion and temperature expansion occurs in the cage, so the circumferential direction of the cut portion does not interfere with the cross sections of the cut portion. It is necessary to set a large width, and uneven distribution in the circumferential direction of the balls becomes prominent. In other words, if a cage that does not reach the equilibrium moisture content is incorporated into the bearing and a lubricant such as grease is enclosed, the bearing will be used with insufficient moisture absorption. Since the circumferential width of the part is large, the NRRO value becomes large.

  Furthermore, if the moisture content is low, the toughness value of the cage (value defined by IZOT impact strength, etc.) is also reduced, so that the impact resistance is also lower than that of a cage that has been subjected to equilibrium moisture treatment. The effect of the present invention is exhibited as the resin material has a higher equilibrium moisture content, that is, a larger dimensional change due to water absorption. For example, the effect of the present invention is great for polyamide resin materials such as polyamide 46, polyamide 6, polyamide 66, and polyamide 6T.

  If a sufficient oil film is formed on the surface of the cage 15 by, for example, filling the bearing space with grease after the assembly of the bearing, it is possible to further prevent the moisture content from changing. It is even better if the bearing space is filled with grease while absorbing water up to the equilibrium moisture content. Further, as described above, by attaching the seal member 16 to the inner peripheral surface of the outer side of the outer ring 12 of each of the two rows of narrow ball bearings 10 in the axial direction, it is difficult for the grease to flow out to the outside. The oil film on the surface of the cage 15 becomes difficult to peel off, and the change in moisture content can be further suppressed.

  In addition, when there is a heat source near the bearing due to a structure with a built-in motor, etc., the temperature temporarily rises around the bearing. In this case, the cage 15 expands due to temperature expansion, but the moisture content increases due to the temperature rise. Since it is slightly reduced, shrinkage occurs, and the dimensional change of the cage 15 is canceled out. When the bearing is stopped and the room temperature is reached, the water absorption rate of the cage 15 returns to the equilibrium water content again. However, in the case of a built-in motor, it is usual to adopt a cooling structure such as circulating cooling oil around the stator of the motor, and in this respect, the temperature of the bearing part usually does not rise so much .

  The moisture content when the cage 15 absorbs water in advance is a predetermined equilibrium moisture content obtained by the material of the cage 15 and the amount of reinforcing material (glass fiber, carbon fiber, aramid fiber, etc.) added. For example, in the case of the above-mentioned polyamide 66 (grade with no reinforcing material added), the temperature of the environment where the bearing is stored or used is 20 to 25 ° C., the average relative humidity is 50 to 70%, and the equilibrium moisture content is 2.9. % (See FIG. 6). The tolerance of the equilibrium moisture content of the cage 15 may be an appropriate value depending on the processing conditions, but is preferably about ± 0.5%.

  Although the average relative temperature varies depending on each region, it is usually used or stored in an indoor environment with proper air conditioning as judged from the product field in which the narrow ball bearing 10 of this embodiment is used. is there. Therefore, it may be considered that the environmental temperature is 20 to 30 ° C. and the relative humidity is 50 to 70%. Therefore, even when a material other than the above synthetic resin material is applied as the material of the cage, the equilibrium moisture content under the above environmental temperature condition is set.

  Moreover, in the narrow ball bearing 10 like this embodiment, the following effects are produced by forming the cutting part 14 in the circumferential direction of the crown type cage 15.

  That is, in a conventional narrow ball bearing having an annular crown-shaped cage without a cut portion, the ball diameter is limited by the dimension in the width direction and becomes small because the bearing is narrow. Therefore, the cross-sectional thickness of the annular portion of the cage is reduced, and the rigidity of the annular portion is small. Further, the deformation due to the measurement pressure at the time of measuring the dimension is large, the measurement of the radial dimension cannot be performed, and it cannot be determined whether or not the cage has an appropriate accuracy. If the pitch circle diameter at the center of the pocket diameter is deviated from the ball pitch circle diameter, the ball and the pocket portion interfere in the diameter direction because of the ball guide method.

  Even if the dimensional accuracy of the cage is appropriate, since the ball diameter is small, the cross-sectional thickness of the annular portion of the cage is thin, and the rigidity of the annular portion is small. The shape accuracy deteriorates. In addition, due to temperature rise and water absorption, the cage expands in the diameter direction, causing tension between the ball and the pocket, causing problems such as wear on the pocket surface, large heat generation during rotation, uneven torque, and large torque. To do.

  On the other hand, in the narrow ball bearing 10 of the present embodiment, the rigidity is further reduced by forming the cut portion 14, but conversely, even if the pitch circle diameter is deviated, the elastic deformation is easy, and the ball pitch circle Since it adapts to the diameter, interference with a strong contact pressure between the ball 13 and the pocket portion 19 is unlikely to occur. Further, the flexibility is improved by allowing the cage 15 to absorb water up to the equilibrium moisture content, and the pitch circle diameter becomes more easily compatible with the ball pitch circle diameter.

  Therefore, in the narrow ball bearing 10 of the present embodiment, for example, when the cage 15 is formed by injection molding, the circumferential width of the cutting portion 14 is from an absolutely dry state to a state where a predetermined equilibrium moisture content is reached. The size is set to be approximately equal to a total amount in which the amount of extension of the cage 15 in the circumferential direction and the amount of elongation of the cage 15 in the circumferential direction due to a predetermined temperature change are considered in advance. Then, the cage 15 after processing is hydrated until a predetermined equilibrium moisture content is reached, and the cage 15 absorbs moisture.

  After that, the cage 15 that has absorbed water up to a predetermined equilibrium moisture content is assembled in the bearing space to hold the plurality of balls 13 to assemble the narrow ball bearing 10, and a lubricant such as grease or oil is sealed in the bearing space. To do. As a result, the retainer 15 that has absorbed water up to a predetermined equilibrium moisture content disposed in the bearing space is less likely to cause a change in moisture content as described above. The structure of the retainer 15 is substantially the same as the extension due to a predetermined temperature change, and the balls 13 can be incorporated in a state in which the uneven distribution in the circumferential direction of the balls 13 is reduced. Therefore, when the bearing is used, if the temperature change is within a predetermined range, the circumferential width ΔL of the cutting portion 14 does not become negative, and the above-described stable rotation performance can be obtained.

(Second Embodiment)
The rolling bearing according to the second embodiment of the present invention shown in FIG. 14 has a configuration in which the seal member 16 is omitted from the two rows of narrow ball bearings combined in the back surface of the first embodiment. In this embodiment, since the seal member 16 is not provided, the ball diameter can be increased. Moreover, when the ball | bowl of the same diameter of 1st Embodiment is used, since the sealing member 16 is not provided, the axial direction width | variety of a bearing can be made thinner.
Other configurations and operations are the same as those of the first embodiment.

(Third embodiment)
The rolling bearing according to the third embodiment of the present invention shown in FIG. 15 has a ball pitch circle diameter of (ball pitch circle diameter)> (D + d) / 2 with respect to that of the second embodiment. In this embodiment, compared with the ball pitch circle diameter = (D + d) / 2, it is possible to increase the number of balls per row of bearings, increase the load capacity of the bearings, and further improve the rigidity. .
Other configurations and operations are the same as those of the first embodiment.

(Fourth embodiment)
The rolling bearing according to the fourth embodiment of the present invention shown in FIG. 16 differs from that of the second embodiment in the ball diameter and ball pitch circle diameter of the left and right narrow ball bearings 10. In this embodiment, when the axial load is uneven between the left and right bearings, a bearing having a large ball diameter is provided on the side where the large load is applied, thereby preventing damage to the bearing and improving the life.
Other configurations and operations are the same as those of the first embodiment.

(Fifth embodiment)
The rolling bearing according to the fifth embodiment of the present invention shown in FIG. 17 has a configuration in which no seal groove is formed on the outer peripheral surface of the inner ring 11 opposed to the seal member 16 with respect to that of the first embodiment. Thereby, the shape of the inner ring 11 can be simplified.
Other configurations and operations are the same as those of the first embodiment.

(Sixth embodiment)
In the rolling bearing according to the sixth embodiment of the present invention shown in FIG. 18, the non-contact type seal members 16 are respectively mounted on the inner peripheral portions of both ends in the axial direction of the outer ring 12 of the narrow ball bearing 10. In this embodiment, it is possible to prevent the grease from flowing out of the bearing, and it is difficult for foreign matters to enter the bearing.
Other configurations and operations are the same as those of the first embodiment.

(Seventh embodiment)
The rolling bearing according to the seventh embodiment of the present invention shown in FIG. 19 has two rows of narrow ball bearings 10 as the front combination. In this embodiment, the contact angle is a reverse C shape, and the moment rigidity is reduced with respect to the rear combination. Therefore, if it is inevitable that the relative inclination of the inner ring 11 and the outer ring 12 during installation is unavoidable, Internally generated load can be reduced.
Other configurations and operations are the same as those of the first embodiment.

(Eighth embodiment)
The rolling bearing according to the eighth embodiment of the present invention shown in FIG. 20 has three rows of narrow ball bearings 10 as the back combination. In this embodiment, the rigidity and load capacity of the bearing can be improved.
Other configurations and operations are the same as those of the first embodiment.

(Ninth embodiment)
The rolling bearing according to the ninth embodiment of the present invention shown in FIG. 21 has four rows of narrow ball bearings 10 as the back combination. In this embodiment, the rigidity and load capacity of the bearing can be further improved.
Other configurations and operations are the same as those of the first embodiment.

(10th Embodiment)
The rolling bearing according to the tenth embodiment of the present invention shown in FIG. 22 is a double-row narrow ball bearing 100 in which two rows of inner rings 11 are integrated with an inner ring 101 as compared with that of the seventh embodiment shown in FIG. It is. In this embodiment, the single row narrow ball bearing 10 can be replaced with two rows, and since the contact angle is a reverse C shape, the moment rigidity is reduced with respect to the rear combination. The cross-sectional dimension ratio (B2 / H2) between the axial cross-sectional width B2 and the radial cross-sectional height H2 (= (outer ring outer diameter D2-inner ring inner diameter d2) / 2) of the double row narrow ball bearing 100 is B2. /H2<1.2 is preferable, and more preferably, B2 / H2 <1.0 can be easily replaced with a standard size ball bearing.
Other configurations and operations are the same as those of the first embodiment.

(Eleventh embodiment)
The rolling bearing according to the eleventh embodiment of the present invention shown in FIG. 23 has two rows of outer rings 12 as an integrated outer ring 102 and has a contact angle of C with respect to that of the seventh embodiment shown in FIG. This is a double row narrow ball bearing 110 having a letter shape. In this embodiment, the single row narrow ball bearing 10 can be replaced with two rows, and since the contact angle is a square shape, the moment rigidity is increased with respect to the front combination. The sectional dimension ratio (B2 / H2) between the axial sectional width B2 and the radial sectional height H2 (= (outer ring outer diameter D2—inner ring inner diameter d2) / 2) of the double row narrow ball bearing 110 is B2. /H2<1.2 is preferable, and more preferably, B2 / H2 <1.0 can be easily replaced with a standard size ball bearing.
Other configurations and operations are the same as those of the first embodiment. A contact type or non-contact type seal member may be attached to both ends of the outer ring 102 in the axial direction.

(Twelfth embodiment)
A rolling bearing according to a twelfth embodiment of the present invention shown in FIG. 24 includes an inner ring 121 having a double row inner ring raceway surface 121a on the outer peripheral surface, an outer ring 122 having a double row outer ring raceway surface 122a on the inner peripheral surface, A plurality of cylindrical rollers (rolling elements) 123 provided between the inner ring raceway surface 121a and the outer ring raceway surface 122a so as to roll freely, and a cutting portion 124 (see FIG. 5) at the position of at least one column portion 127 in the circumferential direction. 25), and a double-row cylindrical roller bearing 120 including a synthetic resin crown-shaped cage 125 that holds a plurality of cylindrical rollers 123 at substantially equal intervals in the circumferential direction. Referring to FIG. 25, the retainer 125 has a cylindrical pocket portion 126, and an intersection of the inner peripheral surface of the pocket portion 126 and the inner diameter surface of the retainer 125, or the inner peripheral surface of the pocket portion 126 and the retainer. This is a roller guide system in which the cylindrical roller 123 and the retainer 125 are in radial contact with each other at an intersection with the outer diameter surface of 126. The setting method of the circumferential width ΔL of the cutting part 124 is the same as that of the first embodiment.

(13th Embodiment)
The rolling bearing according to the thirteenth embodiment of the present invention shown in FIG. 26 differs from that of the second embodiment shown in FIG. The outer ring guide method is applied using the device 150. A cutting portion (not shown) is provided at at least one column portion (not shown) position in the circumferential direction of the machined cage 150. The setting method of the circumferential width ΔL of the cutting portion is the same as that of the first embodiment. In the state where the cage 150 has absorbed water up to the equilibrium moisture content as described above, the circumferential width ΔL of the cutting portion is set. It may be an amount corresponding to a circumferential expansion due to a predetermined (assumed) temperature rise.

  Here, in the case of the conventional machined type cage having the annular portions on both sides in the axial direction, it is relatively strong, which is advantageous for maintaining appropriate dimensions. However, in the case of the outer ring guide system, there is a possibility that the guide clearance is lost due to the temperature rise or the expansion due to water absorption, and there is a possibility that the outer ring guides the worst. If the guide clearance is large enough to avoid galling, the cage swings under conditions that do not cause expansion, resulting in problems such as noise. However, in the machined type retainer having a cutting portion as in the present embodiment, it is possible to minimize the decrease in the guide clearance and prevent problems such as biting on the guide surface.

(14th Embodiment)
The rolling bearing according to the fourteenth embodiment of the present invention shown in FIG. 27 differs from that of the second embodiment shown in FIG. The inner ring guide method is applied using the device 160. A cutting portion (not shown) is provided at at least one column portion (not shown) position in the circumferential direction of the machined cage 160. The method of setting the circumferential width ΔL of the cutting part is the same as that of the first embodiment.

  In the case of a cage without a cutting portion of the conventional inner ring guide system, the guide clearance becomes too large due to temperature rise or expansion due to water absorption, and noise due to abnormal vibration of the cage is generated. In a machined type cage having a cut portion, an increase in guide clearance can be minimized, and abnormal vibration and noise of the cage can be prevented.

  In addition, this invention is not limited to embodiment mentioned above, A change, improvement, etc. are possible suitably. For example, the cutting part 14 of the cage 15 of the present invention may be formed at least at one place in the circumferential direction, and as shown in FIG. 14 may be formed. In this case, the circumferential width ΔL of the cutting portion 14 is ΔL = ΔL1 + ΔL2.

  Here, an embodiment in which the circumferential width ΔL of the cutting portion 14 is set for the retainer 15 incorporated in the two rows of back combination angular contact ball bearings having the same structure as FIG. 1 will be described.

The bearing specifications of this example are as follows.
<Bearing specifications>
Bearing dimensions: inner diameter φ170 mm, outer diameter φ215 mm, width 13.5 mm (single width), contact angle 35 °, ball diameter 6.35 mm, 80 balls, ball pitch circle diameter = φ192.5 mm, B / H = 0 .60
・ Cage material: Polyamide 66 (no reinforcement material mixed) Linear expansion coefficient: 80 × 10 ⁻⁶ (K ⁻¹ )
-Inner ring, outer ring and ball material: bearing steel (SUJ2) linear expansion coefficient: 12.5 × 10 ^-6 (K ^-1 )

  Further, assuming that the use environment of the bearing is an average temperature: 23 ° C. and an average humidity of 60%, the equilibrium moisture content is about 2.9% from FIG. Also, the maximum expected temperature rise of the bearing is set to 80 ° C. (For example, if the application is a machine tool rotary table with a built-in motor or a direct motor rotation support portion, the temperature rise will be a maximum of 80 ° C. during motor load rotation. is expected).

In this case, the circumferential width ΔL of the cut portion 14 is ΔL = 192.5π × (80-12.5) × 10 ⁻⁶ × 80 = 3.27 mm, and the circle of the cut portion 14 at the equilibrium moisture content is The circumferential width ΔL may be 3.27 mm.

  When the cage is manufactured by injection molding, it is in an absolutely dry state (moisture content ≈ 0%) immediately after injection molding. Therefore, the dimensions during molding (before water treatment) are shown in FIG. Since the dimensional change rate at 2.9% is 0.45% (the circumferential direction of the cage ring portion is the resin flow direction at the time of injection molding, the solid line in FIG. 7 corresponds). Expansion due to equilibrium water treatment: 192.5π × 0.0045 = 2.72 mm is expected, and the circumferential width ΔL = 3.27 + 2.72 = 5.99≈6 mm at the time of injection molding Good.

It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 1st Embodiment of this invention. FIG. 2 is a partial perspective view of a crown-shaped cage incorporated in the rolling bearing shown in FIG. 1. FIG. 2 is a cross-sectional view of a crown-shaped cage incorporated in the rolling bearing shown in FIG. 1. It is the figure which fractured | ruptured the part seen from the arrow A direction of FIG. It is the figure which fractured | ruptured the part seen from the arrow B direction of FIG. It is a graph which shows the relationship between the equilibrium moisture content of polyamide 66, and relative humidity. It is a graph which shows the dimensional change rate by the water absorption of the polyamide 66. FIG. It is explanatory drawing for demonstrating the deformation amount of the radial direction of an inner ring | wheel. It is explanatory drawing for demonstrating the calculation method of the cross-sectional secondary moment of an inner ring | wheel. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and the deformation amount of the inner and outer ring | wheels of a radial direction. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and the cross-sectional secondary moment I of an inner-outer ring. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and the deformation amount of the inner and outer ring | wheels of a radial direction. It is a graph which shows the relationship between a cross-sectional dimension ratio (B / H) and the cross-sectional secondary moment I of an inner-outer ring. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 2nd Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 3rd Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 4th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 5th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 6th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 7th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 8th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 9th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 10th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 11th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 12th Embodiment of this invention. It is the figure which fractured | ruptured a part which looked at the holder | retainer integrated in FIG. 24 from the arrow A direction of FIG. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 13th Embodiment of this invention. It is principal part sectional drawing for demonstrating the rolling bearing which concerns on 14th Embodiment of this invention. It is a figure which shows the modification of a crown-shaped cage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rolling bearing 11a Inner ring raceway surface 11 Inner ring 12a Outer ring raceway surface 12 Outer ring 13 Rolling element 14 Cutting part 15 Cage 16 Seal member

Claims (8)

An inner ring having an inner ring raceway surface on an outer peripheral surface, an outer ring having an outer ring raceway surface on an inner peripheral surface, a plurality of rolling elements provided rotatably between the inner ring raceway surface and the outer ring raceway surface, In a rolling bearing comprising a cut portion formed in at least one place in the circumferential direction, and a cage made of synthetic resin that holds the plurality of rolling elements at substantially equal intervals in the circumferential direction,
The retainer absorbs moisture in the resin up to a predetermined equilibrium moisture content and expands in advance , and absorbs moisture to the predetermined equilibrium moisture content and expands in a circumferential width of the cutting portion. features There is formed to be substantially equal to the elongation caused by the predetermined temperature change of the cage, thereby that you suppress circumferential unequal distribution of the rolling element width by reducing the cutting portion Rolling bearing.   The rolling bearing according to claim 1, wherein the cage is a crown type cage.   The rolling bearing according to claim 1, wherein the rolling element is a ball.   The rolling bearing according to claim 1, wherein the rolling element is a cylindrical roller.   The rolling bearing according to claim 1, wherein grease is sealed in a bearing space between the inner ring and the outer ring.   The rolling bearing according to claim 5, further comprising a contact-type or non-contact-type seal member disposed at an axial end portion on the fixed ring side of the inner ring and the outer ring.   The rolling bearing according to claim 5 or 6, wherein the grease is enclosed in the bearing space after the cage has absorbed water to the predetermined equilibrium moisture content.   The rolling bearing according to any one of claims 1 to 4, wherein an oil film is formed on a surface of the cage.

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