JP5402660B2 - Rolling bearing device - Google Patents

Description

  The present invention relates to a rolling bearing device having a rolling bearing and an injection nozzle for injecting oil and air. For example, the present invention relates to a rolling bearing device suitable for use in supporting a main shaft of a machine tool or the like.

  A ball bearing for supporting a spindle of a machine tool needs to support a spindle of a machine tool rotating at a high speed with low resistance. Also, in such ball bearings rotating at high speeds, oil-air lubrication or oil mist lubrication, in which a small amount of oil is transported and injected around the bearing surface of the bearing with compressed air, is suitable as a method of lubricating the raceway surface of the race Used for. This is because, by adopting oil-air lubrication in a ball bearing that rotates at a high speed, it is possible to achieve high-speed rotation of the rotating wheel, low temperature rise of the ball bearing, low power loss of the main shaft, and the like.

  However, when oil-air lubrication is used, high-speed rotation of the rotating wheel can be realized, while compressed air passes through the ball bearing, and the revolving ball interrupts the flow of compressed air intermittently. Therefore, annoying high frequency noise (wind noise) of about 100 dB is generated.

  In addition, if the amount of compressed air is reduced in order to suppress this noise, the injection force of the compressed air becomes weak and the oil becomes difficult to enter the bearing, and the gap between the rolling element of the ball bearing and the raceway surface is reduced. Seizure occurs due to lack of lubricant.

  As a ball bearing proposed in order to avoid these problems, there is one described in Japanese Patent Laid-Open No. 2008-75882 (Patent Document 1).

  In this ball bearing, the shape of the outer peripheral surface of the inner ring is tapered, thereby promoting the supply of oil to the inside and changing the direction of air supply to suppress wind noise. However, in this ball bearing, if the oil does not propagate well on the tapered outer peripheral surface of the inner ring, lubrication may be lost, and wind noise may not be sufficiently suppressed depending on the air flow.

Japanese Patent Laying-Open No. 2008-75882 (FIG. 1)

  SUMMARY OF THE INVENTION An object of the present invention is to provide a rolling bearing device that can suppress unpleasant wind noise and is less likely to lose lubrication between a rolling element and a raceway surface.

In order to solve the above problems, the rolling bearing device of the present invention is
An outer ring having a raceway surface on the inner peripheral surface;
An inner ring having a raceway surface on the outer peripheral surface;
A plurality of rolling elements disposed between the raceway surface of the outer ring and the raceway surface of the inner ring;
A cage having a plurality of pockets that are positioned at substantially the same interval in the circumferential direction and that accommodates the plurality of rolling elements, and
Injecting oil and air between the outer ring and the inner ring, and a plurality of injection nozzles arranged at substantially the same interval in the circumferential direction,
The number of rolling elements is x, the number of spray nozzles is y,
When the rotational speed of the relative rotation of the inner ring with respect to the outer ring is an allowable rotational speed, the relative rotational speed of the cage with respect to each of the injection nozzles is z1 [HZ],
X and y are prime to each other,
In addition, x × y × z1 [HZ] is characterized by being larger than the frequency in the audible range.

  The rotational speed of the bearing is restricted by a temperature rise mainly due to frictional heat inside the bearing, and if it reaches a speed exceeding a certain limit, continuous operation cannot be performed due to the seizure of the bearing. The allowable rotational speed is defined in the specification, and is defined as an allowable rotational speed that can be continuously operated without generating heat that would cause seizure in the bearing.

  According to the present invention, when the rotation speed of the relative rotation of the inner ring with respect to the outer ring is an allowable rotation speed, the relative rotation speed of the cage with respect to each of the injection nozzles is z1 [HZ], and the number of rolling elements. Since x and the number y of injection nozzles are relatively prime, and x × y × z1 [HZ] is larger than the frequency in the audible range, it is injected from the rolling element and the injection nozzle at an allowable rotational speed. The main frequency of sound fluctuation caused by collision with air and non-collision becomes larger than the frequency in the audible range. Therefore, unpleasant wind noise can be greatly suppressed.

In one embodiment,
x ≧ 6 and y ≧ 2.

  When the number of rolling elements is 6 or more and the number of injection nozzles is 2 or more, the wind noise generally increases. However, according to the present embodiment, the main frequency of sound fluctuation is larger than the frequency in the audible range at the allowable rotational speed. Therefore, unpleasant wind noise can be greatly suppressed even at the permissible rotational speed and other usage speeds.

In one embodiment,
When the rotational speed of the relative rotation of the inner ring with respect to the outer ring is 10,000 rpm, when the relative rotational speed of the cage with respect to each of the injection nozzles is z2 [HZ],
x × y × z2 [HZ] is larger than the frequency in the audible range.

  In conventional lubrication for injecting oil and air, the rotational speed of the rotating wheel (outer ring or inner ring) is about 10,000 rpm, and unpleasant wind noise is often generated. According to the above embodiment, an unpleasant wind noise can be greatly suppressed when the rotational speed of the rotating wheel is 10,000 rpm.

In one embodiment,
When the rotational speed of the relative rotation of the inner ring with respect to the outer ring is the rated rotational speed of the rotating shaft to which the outer ring or the inner ring is fixed, the relative rotational speed of the cage with respect to each injection nozzle is z3 [HZ]. When
x × y × z3 [HZ] is larger than the frequency in the audible range.

  According to the above embodiment, the main frequency of sound fluctuation when the rotational speed of the relative rotation of the inner ring with respect to the outer ring is the rated rotational speed of the rotating shaft is greater than or equal to the audible range. Therefore, unpleasant wind noise can be greatly suppressed at the frequently used rotational speed.

  According to the rolling bearing device of the present invention, at the permissible rotational speed, the main frequency of sound fluctuation caused by collision and non-collision between the rolling element and the air injected from the nozzle is larger than the frequency in the audible range. . Therefore, unpleasant wind noise can be greatly suppressed.

It is sectional drawing of the axial direction of the angular ball bearing apparatus of one Embodiment of this invention. It is a figure explaining the principle of this invention. It is a figure explaining the principle of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view in the axial direction of an angular ball bearing device which is an embodiment of the rolling bearing device of the present invention.

  This angular ball bearing device has an inner ring 5, an outer ring 6, a cage 9, 24 balls 7 as an example of a rolling element, and 17 injection nozzles 10.

  The inner ring 5 is externally fitted on the outer peripheral surface of a main shaft (not shown) of a machine tool as a rotating shaft, and rotates in synchronization with the main shaft. The inner ring 5 has a raceway groove 15 as an example of a raceway surface. On the other hand, the outer ring 6 is fitted into the inner peripheral surface of a housing (not shown) of the machine tool. The outer ring 6 has an angular type raceway groove 16 as an example of a raceway surface.

  The cage 9 has two annular parts and a plurality of pillar parts (not shown), and each pillar part connects the two annular parts. The plurality of column portions are arranged at substantially equal intervals in the circumferential direction. The plurality of balls 7 are disposed between the raceway grooves 15 of the inner ring 5 and the raceway grooves 16 of the outer ring 6 with substantially equal intervals in the circumferential direction while being held by the cage 9. ing.

  The plurality of injection nozzles 10 are formed inside the inner ring 5. Each said injection nozzle 10 is substantially the same. Each of the injection nozzles 10 opens in the raceway groove 15 of the inner ring 5. The plurality of injection nozzles 10 are arranged at substantially equal intervals in the circumferential direction.

  In addition, this angular ball bearing device is based on the ratio of the outer diameter of the raceway groove 15 of the inner ring 5 and the outer periphery of the ball 7 when the rotational speed of the relative rotation of the inner ring 5 with respect to the outer ring 6 is an allowable rotational speed. The relative rotational speed of the cage 9 with respect to each injection nozzle 10 is z1 [HZ]. Further, when the rotational speed of the relative rotation of the inner ring 5 with respect to the outer ring 6 is 10,000 rpm, the relative rotational speed of the cage 9 with respect to each injection nozzle 10 is z2 [HZ]. Also, in this angular ball bearing device, when the rotational speed of the inner ring 5 relative to the outer ring 6 is the rated rotational speed of the main shaft, the relative rotational speed z3 of the cage 9 with respect to each injection nozzle 10 is 100 [HZ]. It has become.

  In this angular ball bearing device, 24 × 17 × z1 [HZ] is larger than the frequency in the audible range. Further, 24 × 17 × z2 [HZ] is larger than the frequency in the audible range. 24 × 17 × z3 = 24 × 17 × 100 = 40800 [HZ].

  Here, it is said that the frequency of a person's audible range is generally about 15000 [HZ], and it is said that any person cannot hear a sound having a frequency of 20000 [HZ] or higher. Therefore, if the frequency of the audible range is set to 15000 [HZ], the main frequency of unpleasant wind noise fluctuation is cut, and unpleasant feeling can be remarkably suppressed.

  Hereinafter, with reference to FIGS. 2 and 3, when the number x of balls and the number y of injection nozzles are relatively prime numbers, and the rotation speed of the relative rotation of the inner ring with respect to the outer ring is in the set rotation speed region. When the relative rotation speed of the cage with respect to each injection nozzle is z [HZ], if x × y × z [HZ] is a frequency higher than the audible range, an unpleasant wind noise is greatly suppressed. Explain why.

  2 and 3, as a comparative example, a case where the number of balls is 24 and the number of spray nozzles is 16 will be described.

First, when factoring 24, the number of balls, into prime factors,
24 = 2 × 2 × 2 × 3.

Further, when prime factorization of 16 which is the number of spray nozzles,
16 = 2 × 2 × 2 × 2.

  Therefore, in this case, the greatest common divisor of the number of balls and the number of injection nozzles is 8.

  FIG. 2 is a diagram showing the positions of 16 injection nozzles equally distributed in the circumferential direction.

  FIG. 3 is a diagram showing the positions of 24 balls equally distributed in the circumferential direction.

  Here, when the cage holding the balls with respect to each injection nozzle makes one rotation relatively, the number of cases where the injection nozzle and the balls collide is 24 × 16 = 384.

  However, this 384 has a bulge of 8 times, which is the greatest common divisor calculated earlier. That is, in FIG. 2 and FIG. 3, when a certain injection nozzle and a certain ball overlap in the circumferential direction, the other seven injection nozzles and the other seven balls necessarily overlap. If it demonstrates in a figure, the eight injection nozzles which will show the position of the circumferential direction with a solid line in FIG. 2, and the eight balls which will show the position of the circumferential direction with a solid line in FIG. 3 will collide simultaneously. Therefore, when the cage holding the balls relative to each injection nozzle makes one rotation, the number of cases where the injection nozzles collide with the balls is 384/8 = 48.

  In other words, qualitatively, if the number of spray nozzles and the number of balls are not relatively prime, the number of cases is calculated by dividing the simple product of both by the greatest common divisor of both. On the other hand, if both are relatively prime, the number of cases does not need to be divided by the greatest common divisor, so the number of cases increases frequently, and the collision between the injection nozzle and the ball held in the cage does not collide. Will be repeated.

  Next, a method for calculating the relative rotational speed between the inner ring and the cage will be described. The outer diameter of the raceway groove of the inner ring and the distance of the outer periphery of the ball (2πr ′ where the radius of the ball is r ′) are determined in advance. Therefore, the frequency of the revolution of the ball relative to the inner ring when the ball makes one rotation relative to the inner ring is determined by the outer diameter of the raceway groove of the inner ring and the distance of the outer periphery of the ball. Therefore, the relative rotation speed of the cage with respect to each injection nozzle when the inner ring is rotating at a specific rotation speed is determined by the rotation speed of the inner ring, the outer diameter of the raceway groove, and the outer peripheral distance of the ball. Determined uniquely.

  Hereinafter, specifically, calculation is performed for one example in the case of the above example.

  First, in the case where the number of balls is 24 and the number of spray nozzles is 16, a sound variation of 16 × 24/8 = 48 times occurs for one relative rotation of the inner ring with respect to each ball.

  If the inner ring is rotating at 12000 rpm (200 HZ), the frequency of revolution of each ball relative to the inner ring can often be set to about 100 HZ. Therefore, the frequency of the generated sound is 100 × 48 = 4800 HZ as the main component.

  In contrast, in the embodiment of the present invention, when the number of injection nozzles is 17 and the number of balls 24 is relatively prime, 24 × 17 = 408 times for one relative rotation of the inner ring and the balls. Therefore, when the frequency of revolution of each ball relative to the inner ring is about 100 Hz, the main component of the generated sound is 408 × 100 = 40800 Hz, which exceeds the human audible range. is there.

  According to the angular ball bearing device of the above embodiment, when the rotational speed of the relative rotation of the inner ring 5 with respect to the outer ring 6 is an allowable rotational speed, the relative rotational speed of the cage 9 with respect to each injection nozzle 10 is z1 [HZ]. And the number x of the balls and the number y of the injection nozzles are relatively prime and x × y × z1 [HZ] is larger than the frequency of the audible range. The main frequency of the fluctuation of the sound caused by the collision with the air injected from the injection nozzle and the non-collision becomes higher than the frequency in the audible range. Therefore, unpleasant wind noise can be greatly suppressed.

  Further, according to the angular ball bearing device of the above embodiment, since x ≧ 6 and y ≧ 2, in the case of a conventional device, the wind noise is particularly disturbing. However, according to the present embodiment, the main frequency of sound fluctuation is larger than the audible frequency at the permissible rotational speed, so that unpleasant wind noise is generated even at the permissible rotational speed and other operating speeds. Can be greatly suppressed.

  Further, according to the angular ball bearing device of the above embodiment, the relative rotation of the cage 9 with respect to each injection nozzle 10 when the rotational speed of the relative rotation of the inner ring 5 with respect to the outer ring 6 is 10,000 rpm. When the number is z2 [HZ], since 24 × 17 × z2 [HZ] is larger than the frequency in the audible range, unpleasant wind noise often occurs in the conventional device, and the rotational speed of the rotating wheel Even at 10,000 rpm, an unpleasant wind noise can be greatly suppressed.

  Further, according to the angular ball bearing device of the above embodiment, when the rotational speed of the relative rotation of the inner ring 5 with respect to the outer ring 6 is the rated rotational speed of the main shaft, the main frequency of the sound fluctuation is above the audible range. Therefore, an unpleasant wind noise can be greatly suppressed at a frequently used rotational speed.

  In the angular ball bearing device of the above embodiment, when the number of balls is 24, the number of injection nozzles is 17, and the rotational speed of the relative rotation of the inner ring 5 with respect to the outer ring 6 is the rated rotational speed of the main shaft, The relative rotation speed z3 of the cage 9 with respect to each injection nozzle 10 was 100 [HZ]. However, in the present invention, the number of balls may be 19, the number of injection nozzles may be 15, and z3 may be 100 [HZ] or the like. In one embodiment, the number of rolling elements is x, the number of spray nozzles is y, and the cage for each spray nozzle when the rotational speed of the relative rotation of the inner ring 5 with respect to the outer ring 6 is the rated rotational speed of the main shaft. X and y are relatively prime and x × y × z3 [HZ] is greater than the frequency in the audible range, each of x and y can be any number. good.

  In the angular ball bearing device of the above embodiment, the number of rolling elements is x, the number of injection nozzles is y, and the rotational speed of the relative rotation of the inner ring 5 with respect to the outer ring 6 is the rated rotational speed of the main shaft. When the relative rotation speed of the cage with respect to each spray nozzle is z3, x and y are prime to each other, and x × y × z3 [HZ] is larger than the frequency in the audible range. However, in the present invention, the number of rolling elements is x, the number of injection nozzles is y, and the relative rotation speed of the inner ring with respect to the outer ring is the rated rotation speed of the main shaft. When the relative rotation speed is z3, x and y are relatively prime, and x × y × z3 [HZ] does not have to be larger than the frequency in the audible range. In this invention, the number of rolling elements is x, the number of injection nozzles is y, and the relative rotation speed of the cage with respect to each injection nozzle when the rotation speed of the relative rotation of the inner ring with respect to the outer ring is an allowable rotation speed. When z1 [HZ], x × y × z1 only needs to be a frequency that exceeds the frequency above the audible range.

  In the angular ball bearing device of the above embodiment, the injection nozzle 10 is formed in the inner ring 5 that is a rotating wheel and does not rotate relative to the rotating wheel. Is formed inside the outer ring, which is a stationary wheel, or is arranged at a distance from the inner and outer rings so that it does not rotate relative to the stationary wheel while rotating relative to the rotating wheel. It may be. The stationary wheel may be an inner ring or an outer ring.

  In the angular ball bearing device of the above embodiment, the cage 9 has two annular portions and a plurality of pillar portions that connect the two annular portions. The cage may be a crown type cage having only one annular portion.

  In the above embodiment, the outer ring 6 has an angular type raceway groove having a counterbore. However, in the present invention, the outer ring may be a deep groove type raceway groove.

  Moreover, in the said embodiment, although the rolling element was the ball 7, the rolling element of this invention may consist only of rolling elements other than balls, such as a cylindrical roller and a tapered roller. Moreover, the rolling bearing device of the present invention may have two or more rolling elements of balls, cylindrical rollers and tapered rollers.

  Further, in the angular ball bearing device of the above embodiment, as shown in FIG. 1, the opening of the injection nozzle 10 is oriented in a direction inclined in the axial direction. However, in this invention, the injection nozzle may face the axial direction. The injection nozzle may be formed inside the outer ring and may be directed in a radial direction or a direction inclined in the radial direction. Further, the injection nozzle may be formed in the inner ring and may be directed in a radial direction or a direction inclined in the radial direction. The injection nozzle may be separate from the inner and outer rings and may face in the axial direction and the direction inclined in the axial direction. In short, the injection nozzle may be injected from any angle and from any location as long as it faces between the inner and outer rings.

  Further, in the angular ball bearing device of the above embodiment, the plurality of injection nozzles are all the same. However, in the present invention, the plurality of injection nozzles only have to be arranged at substantially equal intervals in the circumferential direction. The plurality of spray nozzles may not all be the same. That is, if the number of injection nozzles is N (N is a natural number), only M (M is a natural number satisfying 0 ≦ M ≦ N) of them may be substantially the same.

  Further, in the present invention, when the rotating shaft is rotating, oil droplets may be intermittently mixed into the air while always blowing air between the inner and outer rings, or the rotation shaft A type in which air containing oil mist is always sprayed when the shaft rotates may be used.

5 Inner ring 6 Outer ring 7 Ball 9 Cage 10 Jet nozzle 15 Inner ring raceway groove 16 Outer ring raceway groove

Claims (3)

An outer ring having a raceway surface on the inner peripheral surface;
An inner ring having a raceway surface on the outer peripheral surface;
A plurality of rolling elements disposed between the raceway surface of the outer ring and the raceway surface of the inner ring;
A cage having a plurality of pockets that are positioned at substantially the same interval in the circumferential direction and that accommodates the plurality of rolling elements, and
Injecting oil and air between the outer ring and the inner ring, and a plurality of injection nozzles arranged at substantially the same interval in the circumferential direction,
The number of rolling elements is x, the number of spray nozzles is y,
When the rotational speed of the relative rotation of the inner ring with respect to the outer ring is an allowable rotational speed, the relative rotational speed of the cage with respect to each of the injection nozzles is z1 [HZ],
X and y are prime to each other,
In addition, the rolling bearing device is characterized in that x × y × z1 [HZ] is larger than an audible frequency. The rolling bearing device according to claim 1,
A rolling bearing device, wherein x ≧ 6 and y ≧ 2. In the rolling bearing device according to claim 1 or 2,
When the rotational speed of the relative rotation of the inner ring with respect to the outer ring is 10,000 rpm, when the relative rotational speed of the cage with respect to each of the injection nozzles is z2 [HZ],
x * y * z2 [HZ] is larger than the frequency of an audible range, The rolling bearing apparatus characterized by the above-mentioned.

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