JP2008240845A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing capable of achieving speeding up, extension of lifetime, and maintenance-free structure by using only grease filled in the bearing, stably providing a clearance for grease base oil supply, and reducing cost by simplification of manufacturing. <P>SOLUTION: This bearing includes an inner ring 1, an outer ring 2 and a plurality of rolling elements 3 put between raceway surfaces 1a, 2a of the inner and the outer rings 1, 2. A step surface 2b continuing the raceway surface 2a is provided on a fixed side raceway ring 2 which does not rotate out of the inner ring 1 and the outer ring 2 which are the raceway rings, in a direction separating from the rolling elements 3. A clearance forming piece 7 butting on the step surface 2b at a tip 7a thereof and forming a channel 14 with the fixed side raceway ring 2 at a circumference wall is provided. A grease pocket 6 communicating with the channel 14 is provided. A clearance forming groove 7aa forming a clearance 15 between the step surface 2b of the fixed side raceway ring 2 and the tip 7a of the clearance forming piece 7 is provided at a part of the tip 7a of the clearance forming piece 7 in a circumference direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rolling bearing with a lubrication mechanism for grease lubrication of a machine tool main shaft or the like.

  As a lubrication method for machine tool spindle bearings, grease lubrication that can be used maintenance-free, air-oil lubrication in which lubricating oil is mixed with carrier air and oil is injected into the bearing from the nozzle, jet that injects lubricating oil directly into the bearing There are methods such as lubrication. In recent machine tools, in order to increase machining efficiency, there is a tendency for higher speed, and lubrication of main shaft bearings is also relatively inexpensive and air-oil lubrication that can be speeded up easily is often used. However, this air oil lubrication method has a problem from the viewpoint of cost, noise, energy saving, and resource saving because it requires an air oil supply device as ancillary equipment and requires a large amount of air. There is also a problem of deteriorating the environment due to the scattering of oil. In order to avoid these problems, recently, speeding up by grease lubrication has begun to attract attention, and requests have been increasing.

  Since grease lubrication is performed only with the grease enclosed at the time of bearing assembly, high-speed operation may lead to premature seizure due to deterioration of the grease due to bearing heat generation and oil film breakage on the raceway surface, especially the inner ring. . In particular, it is difficult to guarantee the grease life in a high-speed rotation region where the dn value exceeds 1 million (bearing inner diameter mm × rotational speed rpm).

  New proposals have been introduced as a means of extending the life of grease. One of them is that a grease reservoir forming part having a grease reservoir formed therein is provided in contact with the stationary side race ring (for example, the outer ring), and extending from the grease reservoir forming part to the vicinity of the raceway surface of the stationary side race ring, A gap forming piece for forming a gap is provided between the fixed side raceway and the grease reservoir and the raceway surface of the fixed side raceway are communicated via the gap (for example, Patent Documents). 1, 2).

  According to the rolling bearings of Patent Documents 1 and 2, when the bearing is stopped, the base oil of the grease moves into the gap due to the thickener in the grease and the capillary phenomenon of the gap. When the bearing is operated, the base oil stored in the clearance is discharged from the clearance due to the volume expansion caused by the temperature rise of the fixed-side raceway and the air flow generated by the revolution and rotation of the rolling elements. It moves while adhering to the raceway surface of the raceway and is continuously supplied to the rolling element contact portion.

In the case of the above configuration, the management of the gap formed between the fixed-side race and the gap forming piece is very important.
In view of this, a configuration has been proposed in which the gap is managed by providing protrusions in contact with the fixed-side raceway at a plurality of circumferential positions at the tip of the gap forming piece (for example, Patent Document 3). ).
JP 2005-180629 A JP 2006-132765 A JP 2005-299757 A

  However, the one disclosed in Patent Document 3 has a problem in that protrusions are provided at a plurality of positions in the circumferential direction at the tip of the gap forming piece, and if the protrusions are formed by cutting or grinding, it takes a lot of work. is there. In addition, in the case of press working or resin molding, not only a mold is required, but high-precision processing is not easy.

  The object of the present invention is to solve these problems, and it is possible to achieve high speed, long life and maintenance-free by using only the grease enclosed in the bearing, and supply grease base oil. It is an object of the present invention to provide a rolling bearing capable of stably obtaining a gap for use and reducing costs by facilitating manufacture.

  The rolling bearing of the present invention is a rolling bearing having an inner ring, an outer ring, and a plurality of rolling elements interposed between the raceway surfaces of these inner and outer rings. A stepped surface following the raceway surface is provided in a direction away from the rolling element, and a gap forming piece is formed to form a flow path between the tip of the stepped surface and the fixed side raceway ring at the peripheral wall, and communicated with the flow path. And a gap forming groove for forming a gap with the stepped surface of the stationary side raceway is provided in a part of the tip of the gap forming piece in the circumferential direction.

The rolling bearing having this configuration is used by filling grease in a flow path formed between a grease reservoir and a stepped surface of the stationary raceway and the peripheral wall of the gap forming piece. Grease as an initial lubricating oil is sealed inside the bearing. The base oil separated from the grease is discharged to the raceway surface of the stationary side raceway through the gap due to the pressure fluctuation due to the heat cycle in the grease pool accompanying the repeated stoppage and resumption of operation of the rolling bearing. Supply is ensured. In addition, since the base oil is discharged onto the raceway surface of the stationary raceway by the capillary phenomenon in the gap, the lubrication is further ensured.
In particular, a gap forming groove for forming a gap between the stepped surface of the stationary side race ring is provided in a part of the circumferential direction at the tip of the gap forming piece, so that cutting or cutting is performed on the tip of the gap forming piece. The gap forming groove can be formed easily and with high precision simply by grinding. In addition, since the tip of the gap forming piece is brought into contact with the step surface of the stationary race, the gap is secured between the step surface and the gap forming groove at the tip of the gap forming piece. The gap can be easily managed to an appropriate dimension without considering dimensional tolerances. Further, a die as in the case of press working or resin molding is not required, and the cost can be reduced.
This makes it possible to achieve high speed, long life, and maintenance-free operation using only the grease sealed in the bearing, stably providing a gap for supplying the grease base oil, and reducing the cost by facilitating manufacture.

In the present invention, the gap forming grooves may be provided at two locations 180 degrees apart from each other in the circumferential direction.
In the case of this configuration, when the gap forming groove is processed, two gap forming grooves can be processed by moving a tool such as a grindstone to the tip surface of the gap forming piece in the diameter direction. Therefore, processing is easy. In addition, since the two gaps are arranged at positions 180 ° apart from each other in the circumferential direction, the lubricating oil is discharged from the gaps to the raceway surface of the fixed-side raceway substantially evenly in the circumferential direction. Is called.

When the gap forming grooves are provided at two positions separated by 180 ° in this way, the width of the gap forming groove is set to the width of the step surface contact portion which is a portion between the adjacent gap forming grooves at the tip of the gap forming piece. It may be wider.
In the case of this configuration, since the gap can be provided over a wide range in the circumferential direction, the lubricating oil is more stably discharged from the gap to the raceway surface of the fixed-side raceway.

  In the present invention, the fixed-side raceway ring may be an outer race. When the stationary ring is an outer ring, the stepped surface is provided on the outer ring, but when the bearing is rotated in a grease-filled state, the sealed grease scatters to the inner diameter of the outer ring by centrifugal force. The base oil is securely connected to the raceway surface. Therefore, the base oil that is consumed as the lubricating oil in the rolling element contact portion is replenished to the raceway surface from the grease reservoir through the gap, and the lubricating oil is more stably replenished.

  In this invention, the rolling bearing may be an angular ball bearing, and the stepped surface may be formed following an edge portion on the opposite side to the direction in which the contact angle occurs on the raceway surface. When the angular ball bearing is provided, the stepped surface is provided on the side opposite to the direction in which the contact angle is generated, so that the stepped surface is more easily disposed directly below the rolling element. The step surface can be brought close to the center of the rolling element, and lubricating oil can be replenished from the gap to the raceway surface more efficiently.

  The rolling bearing of the present invention is a rolling bearing having an inner ring, an outer ring, and a plurality of rolling elements interposed between the raceway surfaces of these inner and outer rings. A stepped surface following the raceway surface is provided in a direction away from the rolling element, and a gap forming piece is formed to form a flow path between the tip of the stepped surface and the fixed side raceway ring at the peripheral wall, and communicated with the flow path. And a gap forming groove that forms a gap with the stepped surface of the fixed side raceway is provided in a part of the circumferential direction at the tip of the gap forming piece. Using only grease, high speed, long life, and maintenance-free can be achieved, and the gap for supplying grease base oil can be obtained stably, and the cost can be reduced due to easy manufacturing.

  An embodiment of the present invention will be described with reference to FIGS. In FIG. 1A, this rolling bearing has a plurality of rolling elements 3 interposed between raceways 1a and 2a of an inner ring 1, an outer ring 2, and inner and outer rings 1 and 2, and a grease reservoir 6 and a gap formation. And a piece 7. The plurality of rolling elements 3 are held by a cage 4, and one end of the bearing space between the inner and outer rings 1 and 2 is sealed with a seal 5. This rolling bearing is an angular ball bearing, the seal 5 is provided at the end on the bearing back side, and the grease reservoir 6 and the gap forming piece 7 are provided on the bearing front side. The grease reservoir 6 also serves as a seal on the front side of the bearing, preventing grease leakage from the front side of the bearing. In the figure, the crossed hatched portions indicate the portions filled with the grease 11. The inner ring 1 of the rolling bearing is fitted to a main shaft (not shown) so as to be rotatable, and the outer ring 2 is fixedly supported in a fitted state on the inner periphery of a housing (not shown) in the spindle unit.

  On the outer ring 2 serving as a fixed-side raceway, a step surface 2b following the raceway surface 2a follows the outer ring front side away from the rolling elements 3, that is, the edge on the opposite side to the direction in which the contact angle occurs on the raceway surface 2a. Is provided. The step surface 2b is a surface that extends from the raceway surface 2a to the outer diameter side and faces the outer ring front side.

  The grease reservoir 6 is a ring-shaped component having a grease reservoir space 8, and is disposed in contact with the width surface on the front side of the outer ring 2, and is disposed on the outer diameter side of the inner ring positioning spacer 26. In this example, the grease reservoir 6 includes an outer ring positioning spacer 9 provided in contact with the front-side width surface of the outer ring 2 and an outward groove-shaped grease reservoir main body fitted to the inner diameter surface of the outer ring positioning spacer 9. 10 and. An internal space sandwiched between the outer ring positioning spacer 9 and the grease reservoir main body 10 is a grease reservoir space 8. The outer ring positioning spacer 9 has an engaging step portion 9a for fitting the tip of the side wall portion 10a of the grease reservoir main body 10 at the end opposite to the outer ring 2 on the inner diameter surface. The grease reservoir main body 10 is configured to engage the side wall portion 10a with the engaging step portion 9a of the outer ring positioning spacer 9 after the grease reservoir space 8 is filled with the grease 11, and fix it to the inner diameter surface of the engaging step portion 9a. A part is used to fix the outer ring positioning spacer 9 in the axial direction. On the inner diameter surface of the grease reservoir main body 10 between the outer diameter surface of the side wall portion 10a and the engaging stepped portion 9a in the outer ring positioning spacer 9, and the adjacent portion of the outer ring positioning spacer 9 and the outer ring 2 in contact with the outer ring positioning spacer 9. Are provided with sealing parts such as an O-ring (not shown), thereby preventing leakage of the grease 11. The outer ring positioning spacer 9 and the grease reservoir body 10 are made of a metal material such as steel.

  The gap forming piece 7 is a ring-shaped member that is disposed along the inner diameter surface 2 c of the outer ring 2, has a tip abutting against the step surface 2 b, and forms a flow path 14 and a gap 15 between the outer ring 2. The gap forming piece 7 is formed integrally with the grease reservoir main body 10. That is, the grease reservoir main body 10 extends integrally from the outer diameter end of the side wall 10b adjacent to the bearing.

The flow path 14 is formed by the peripheral wall of the tip 7a of the gap forming piece and the inner diameter surface 2c of the outer ring 2 facing this. The base 7b of the gap forming piece 7 has a smaller diameter than the tip 7a. A portion surrounded by the outer diameter surface of the base portion 7 b and the inner diameter surface 2 c of the outer ring 2 is a part of the grease reservoir space 8, and the flow path 14 communicates with the grease reservoir space 8.
3A and 3B show a front view of the grease reservoir main body 10 as viewed from the tip 7a side of the gap forming piece 7, and a cross-sectional view of the grease reservoir main body 10. FIG. As shown in FIG. 3A, a gap forming groove 7aa that forms a gap 15 between the stepped surface 2b of the outer ring 2 is formed in a part of the tip 7a of the gap forming piece 7 in the circumferential direction. The remaining portion in the circumferential direction is a step surface contact portion 7ab that contacts the step surface 2b. 1A shows a cross-sectional view of the rolling bearing taken along the gap forming groove 7aa, and FIG. 2 shows a cross-sectional view of the rolling bearing taken along the stepped surface contact portion 7ab. In this embodiment, as shown in FIG. 3 (A), the gap forming groove 7aa at the gap forming piece tip 7a is disposed at two positions 180 degrees apart from each other in the circumferential direction. These two gap forming grooves 7aa are obtained by grinding the tip end surface of the circular gap forming piece 7 by passing a grinding wheel in the diameter direction, for example, and both side edges of the two gap forming grooves 7aa. Is formed in a shape along two straight lines a and a parallel to the diameter direction of the gap forming piece 7. Further, the width of the gap forming groove 7aa is made wider than the width of the stepped surface contact portion 7ab which is a portion between the adjacent gap forming grooves 7aa and 7aa at the tip 7a of the gap forming piece 7.

The operation of the above configuration will be described. When the bearing is assembled, grease 11 is filled in the grease reservoir 6 and the flow path 14. In addition, grease for initial lubrication is sealed in the bearing. When the bearing is operated, the base oil and the thickener having different expansion coefficients are separated in the grease 11 stored in the sealed grease reservoir 6 except for the gap 15 due to a temperature rise during operation. At the same time, the internal pressure of the sealed grease reservoir 6 increases. Due to this internal pressure, the separated base oil is discharged from the gap 15 toward the raceway surface 2 a of the outer ring 2. When the temperature rises and reaches a steady state, the internal pressure increase factor disappears, so that the internal pressure gradually decreases in parallel with the base oil discharge, and the base oil discharge amount per unit time also decreases. Thereafter, when the operation is stopped, the temperature of the grease reservoir 6 also decreases, and the internal pressure of the grease reservoir 6 becomes almost atmospheric pressure. At this time, the base oil is not discharged by pressure, and the gap 15 is filled with the base oil. Therefore, in the operation stop state, the grease reservoir 6 is in a sealed state.
Thereafter, when the operation is resumed, the internal pressure of the grease reservoir 6 rises again. Due to such a heat cycle of temperature rise and fall, pressure fluctuations in the grease reservoir 6 are repeated, and the base oil separated from the grease 11 reliably moves to the gap 15 and is repeatedly supplied to the raceway surface 2a of the outer ring 2. Is done.

  In addition to the base oil discharging action by the heat cycle, a base oil discharging action by the capillary action shown below is also added. That is, when the bearing is stopped, the base oil of the grease 11 moves from the flow path 14 to the gap 15 due to the thickener in the grease 11 and the capillary phenomenon of the gap 15, and the capillary phenomenon and the surface tension of the oil are combined. The base oil is held oily in the gap 15. When the bearing is operated, the base oil stored in the clearance 15 is discharged from the clearance 15 due to the volume expansion caused by the temperature increase of the outer ring 2 generated by the operation and the air flow generated by the revolution and rotation of the rolling element 3, and the outer ring It moves while adhering to the two raceway surfaces 2a and is continuously supplied to the rolling element contact portion.

  As described above, in this rolling bearing, the base oil separated from the grease 11 due to the pressure fluctuation due to the heat cycle in the grease reservoir 6 due to repeated operation stop and operation restart passes through the gap 15 to the raceway surface 2a of the outer ring 2. Since the oil is discharged, the lubricating oil is reliably supplied. In addition, since the base oil is discharged to the raceway surface 2a of the outer ring 2 also by the above-described capillary phenomenon in the gap 15, lubrication is further ensured.

In particular, in this rolling bearing, a gap forming groove 7aa that forms a gap 15 between the stepped surface 2b of the outer ring 2 that is a stationary raceway is provided in a part of the tip 7a of the gap forming piece 7 in the circumferential direction. Because of the configuration, the gap forming groove 7aa can be formed easily and with high precision simply by subjecting the tip 7a of the gap forming piece 7 to cutting or grinding. Further, the gap 15 is secured between the step surface 2b and the gap forming groove 7aa of the gap forming piece tip 7a by bringing the tip 7a of the gap forming piece 7 into contact with the step surface 2b of the outer ring 2. Therefore, the gap 15 can be easily managed to an appropriate dimension without considering the dimensional tolerance of each part. Further, a die as in the case of press working or resin molding is not required, and the cost can be reduced.
This makes it possible to achieve high speed, long life, and maintenance-free operation using only the grease sealed in the bearing, stably providing the gap 15 for supplying the grease base oil, and reducing the cost by simplifying production. .

  Further, in this embodiment, the gap forming groove 7aa of the gap forming piece 7 is formed at two positions 180 degrees apart from each other in the circumferential direction. Therefore, when machining the gap forming groove 7aa, a tool such as a grindstone as described above is used. The gap forming grooves 7aa at two locations can be processed by moving the tip of the gap forming piece 7 in the diameter direction. Therefore, processing is easy. Further, the two gaps 15 are arranged at positions 180 ° apart from each other in the circumferential direction, and the lubricant oil is discharged from the gap 15 to the raceway surface 2a of the outer ring 2 substantially evenly in the circumferential direction. Can be made.

  Since the width of the gap forming groove 7aa is larger than the width of the stepped surface contact portion 7ab, the gap 15 can be provided over a wide range in the circumferential direction, and the gap 15 extends from the raceway surface 2a of the outer ring 2. Lubricating oil is replenished more stably.

  In this embodiment, the fixed raceway ring is the outer ring 2, and the stepped surface 2b is provided on the outer ring 2, but when the bearing is rotated in a grease-filled state, the sealed grease is subjected to centrifugal force by the centrifugal force. Therefore, the base oil is securely connected between the gap 15 and the raceway surface 2a. As a result, the base oil that is consumed as the lubricating oil in the rolling element contact portion is replenished to the raceway surface 2a from the grease reservoir 6 through the gap 15, and the lubricating oil is more stably replenished.

  In this embodiment, the rolling bearing is an angular ball bearing, and the step surface 2b is formed following the edge opposite to the direction in which the contact angle occurs on the raceway surface 2a. It becomes easy to arrange directly under the moving body 3. Thereby, the step surface 2b can be brought close to the center of the rolling element 3, and the lubricating oil can be replenished from the gap 15 to the raceway surface 2a more efficiently.

  FIG. 4 shows another embodiment of the present invention. In the rolling bearing of this embodiment, in the embodiment shown in FIGS. 1 to 3, the grease pool 6 </ b> A is arranged on the inner diameter surface 2 c of the outer ring 2, so that the grease pool space is formed inside the bearing space between the inner and outer rings 1 and 2. 8 is formed. In this example, the outer ring positioning spacer 9 in the embodiment shown in FIGS. 1 to 3 is not a component of the grease reservoir 6A, and is a single component corresponding to the grease reservoir body 10 in the embodiment shown in FIGS. Thus, a grease reservoir 6A is formed. The grease reservoir 6A has an outwardly grooved cross-sectional shape, and the gap forming piece 7 is integrally provided.

In this embodiment, the length on the bearing front side, which is the arrangement side of the grease reservoir 6A, is made longer than the length from the center of the raceway surface 2a of the outer ring 2 to the width surface on the bearing rear side, and the inner diameter of the outer ring of this elongated portion is increased. A grease reservoir 6A is fitted to the surface 2c. In this case, the inner and outer rings 1 and 2 have the same width dimension, the width dimension is larger than the standard dimension in one direction, and the inner diameter surface 2c of the portion where the width dimension of the outer ring 2 is increased is as described above. The grease reservoir 6A is fitted.
The side wall 6a outside the bearing of the grease reservoir 6A is engaged with an engaging step 2d formed on the inner surface 2c of the outer ring, and a fixing component is used on the inner surface of the engaging step 2d to fix it in the axial direction. It is.

  The inner diameter surface of the inner ring 1 in the increased width dimension is a small diameter surface portion 1c having a smaller diameter than the portion of the inner diameter surface 1b adjacent to the raceway surface 1a. By extending the inner diameter portion of the grease reservoir 6A toward the small diameter surface portion 1c, the grease reservoir space 8 is secured widely. The other structure is the same as that of the rolling bearing of FIGS.

  In this embodiment, since the grease reservoir 6A is disposed on the inner diameter surface 2c of the outer ring 2, this rolling bearing can be incorporated into a spindle device or the like with the grease reservoir space 8 filled with grease. Therefore, the workability of the bearing assembly is improved.

  FIG. 5 shows an example of a spindle device for a machine tool using the rolling bearing of the embodiment shown in FIGS. In the spindle device for machine tools, two of the rolling bearings are used as a back surface combination. The two rolling bearings 23 and 24 rotatably support both ends of the main shaft 21 within the housing 22. The inner ring 1 of each rolling bearing 23, 24 is positioned by an inner ring positioning spacer 26 and an inner ring spacer 27, and is fastened and fixed to the main shaft 21 by an inner ring fixing nut 29. The outer ring 2 is positioned and fixed in the housing 22 by an outer ring positioning spacer 9, an outer ring spacer 30, and outer ring pressing lids 31 and 32. The housing 22 is formed by fitting a housing inner cylinder 22A and a housing outer cylinder 22B, and an oil passage groove 33 for cooling is provided in the fitting portion.

  The spindle 21 is provided with a chuck (not shown) for detachably attaching a tool or a work (not shown) to the front end 21a, and a drive source such as a motor transmits rotation to the rear end 21b. They are connected via a mechanism (not shown). The motor may be built in the housing 22. This spindle apparatus can be applied to various kinds of work such as a machining center, a lathe, a milling machine, and a grinding machine.

  According to the spindle device having this configuration, the rolling bearings 23 and 24 of this embodiment can effectively exhibit the effects of speeding up, extending the service life, and making maintenance free.

(A) is sectional drawing of a part of rolling bearing concerning one Embodiment of this invention, (B) is the elements on larger scale of (A). It is sectional drawing of the other part of the rolling bearing. (A) is the front view which looked at the grease reservoir main body in the rolling bearing from the front-end | tip side of a gap formation piece, (B) is sectional drawing of the grease reservoir main body. FIG. 5 is a partial cross-sectional view of a rolling bearing according to another embodiment of the present invention. It is sectional drawing of the spindle apparatus for machine tools using the rolling bearing of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Inner ring 2 ... Outer ring 1a, 2a ... Raceway surface 3 ... Rolling element 6, 6A ... Grease reservoir 7 ... Gap formation piece 7aa ... Gap formation groove 7ab ... Step surface contact part 14 ... Flow path 15 ... Gap

Claims (5)

  In a rolling bearing having an inner ring, an outer ring, and a plurality of rolling elements interposed between the raceway surfaces of these inner and outer rings, a stepped surface following the raceway surface is formed on the stationary side raceway that does not rotate among the inner ring and outer ring that are raceway rings. Provided in a direction away from the rolling element, provided with a gap forming piece that forms a flow path between the tip of the stepped surface and the fixed-side raceway at a peripheral wall, and provided with a grease reservoir communicating with the flow path, A rolling bearing comprising a gap forming groove for forming a gap between the stepped surface of the stationary side raceway and a part of the gap forming piece in a circumferential direction.   The rolling bearing according to claim 1, wherein the gap forming grooves are two places that are 180 ° apart from each other in the circumferential direction.   The rolling bearing according to claim 2, wherein a width of the gap forming groove is wider than a width of a stepped surface abutting portion that is a portion between adjacent gap forming grooves at a tip of the gap forming piece.   The rolling bearing according to any one of claims 1 to 3, wherein the fixed-side race ring is an outer ring. 5. The rolling bearing according to claim 4, wherein the stepped surface is formed following an edge portion on a side opposite to a direction in which a contact angle occurs on the raceway surface.

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