JP2007303571A - Tapered roller bearing lubricating structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tapered roller bearing lubricating structure suitable to high speed operation for uniformly supplying lubricating oil to a roller end face over the whole periphery of a bearing while reducing agitating resistance and avoiding the starvation of the lean lubricating oil on the roller end face. <P>SOLUTION: A roller 4 of the tapered roller bearing 1 is a hollow roller which has a through-hole 4a passing through both ends. A nozzle 9 is provided adjacent to the back face side of the tapered roller bearing 1 for supplying lubricating air oil (a) into a bearing space between an inner ring 2 and an outer ring 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lubricating structure for a tapered roller bearing used for supporting a high-speed spindle such as a spindle for machine tools.

Angular ball bearings are mainly used to support high-speed spindles such as machine tool spindles in order to suppress heat generation of the bearings. However, although angular ball bearings are suitable for high-speed rotation, the bearing rigidity is lower than that of roller bearings.Therefore, when a large external force is applied to the spindle end, such as heavy cutting, the deflection of the spindle increases and It is difficult to improve the shape accuracy of the work.
There is also an example in which a cylindrical roller bearing is disposed at the end of the main shaft to improve radial rigidity and an angular ball bearing that receives an axial load is used in combination. In this case, since the assembly width of the bearing becomes large, the main shaft becomes long and it is difficult to make it compact.

  Tapered roller bearings that can simultaneously apply radial and axial loads are available as bearings that can improve the rigidity and compactness of the spindle. An example of a spindle device using a tapered roller bearing is shown in FIG. 4, and an enlarged sectional view of the bearing portion is shown in FIG. For the lubrication of the bearing in this spindle device, air oil lubrication effective for high-speed operation by supplying a trace amount of oil is employed. Specifically, on the back side of the tapered roller bearing 41, the inner diameters of the inner ring collar 42c and the cage 45 are passed from the air oil supply devices 50A and 50B shown in FIG. Air oil is supplied between the tapered roller 44 and the raceway surface 42a of the inner ring 42 and between the tapered roller 44 and the retainer 45 by supplying air oil between them. Further, on the front side of the tapered roller bearing 41, the inner ring large collar 42b and the inner diameter surface of the retainer 45 are connected to each other from the air oil supply devices 50A and 50B of FIG. Lubricating between the roller large end surface 44a and the inner ring large collar 42b surface, which is a guide surface thereof, is performed by blowing air oil from the nozzle 54 to the large end surface 44a of the tapered roller 44.

The problem when the tapered roller bearing is operated at high speed is the lubrication of the sliding portion between the roller large end surface with relatively large slippage between the tapered roller and the raceway surface and the inner ring large collar surface that guides this. . As the lubrication technology, the following two have been proposed.
(1) By providing a guide rod in sliding contact with the large end surface of the tapered roller on the outer ring side, lubricating oil supplied from the small end surface side of the tapered roller is secured on the guide surface of the guide roller ( Patent Document 1).
(2) The lubricating oil is forcibly supplied from the outside to the guide surface of the inner ring large collar by connecting the outer oil filling section and the inner ring large collar section through the oil hole provided in the inner ring (Patent Document 2). .
Japanese Patent Publication No.53-8856 JP-A-8-270660

In the lubrication technique disclosed in Patent Document 1, an oil drain hole is provided in the outer ring in order to suppress agitation resistance due to stagnant oil at the outer ring guide rod. There is a problem that it is difficult to set the number of holes.
In addition, the lubricating technique disclosed in Patent Document 2 has a problem in that the structure is complicated although the lubricating oil does not stay.
Further, in the structure in which lubricating oil is supplied from a plurality of nozzles or oil supply holes distributed on the circumference of the bearing as in the lubricating technique shown in FIGS. 4 and 5 and the lubricating technique disclosed in Patent Document 2. Since the tapered roller revolves while rotating, there is a difference in the amount of lubricating oil adhering to the roller large end face depending on where the tapered roller is located on the circumference. Further, the lubricating oil discharged from the nozzle or the oil supply hole and immediately after adhering to the large end face of the roller is in an abundant state, but the adhering oil is reduced by the centrifugal force due to the rotation and revolution of the tapered roller. Therefore, immediately before the roller large end surface reaches the position on the circumference facing the nozzle and oil supply hole, the lubricant oil on the roller large end surface becomes a thin starvation state, that is, a deficient state, ensuring an oil film on the sliding part. Becomes difficult.

  An object of the present invention is to provide a tapered roller bearing that can supply lubricating oil evenly to the roller end face over the entire circumference of the bearing, has low stirring resistance, and is suitable for high-speed operation that does not cause dilute lubrication of the lubricating oil on the large roller end face. It is to provide a lubrication structure.

The lubricating structure of the tapered roller bearing according to the present invention is such that the roller of the tapered roller bearing is a hollow roller having a through-hole penetrating at both ends, and is adjacent to the back side of the tapered roller bearing, and the bearing inner space between the inner ring and the outer ring A nozzle for supplying air oil for lubrication is provided.
According to this configuration, the air oil supplied from the nozzle provided adjacent to the back side of the bearing moves together with the air flow from the back side to the front side due to the pumping action that occurs as the bearing rotates. At this time, the air-oil flow flowing along the outer ring raceway surface causes oil to adhere to the raceway surface and the roller outer diameter surface, and this adhered oil is used for lubrication between the raceway surface and the rolling surface. Further, the hollow roller revolves while rotating to cause a pumping action by the inner diameter surface of the through hole. That is, by rotation of the bearing, air oil supplied from the nozzle sucks and flows into the through-hole using the back side of the through-hole of the roller as an inlet, and forms a series of flows that are discharged from the front side of the through-hole. At this time, the oil in the air oil adheres to the inner wall surface of the through hole inside the through hole of the roller, and the flow of the attached oil occurs toward the front side. The oil adhering to the inner wall surface of the through hole flows out from the front side opening while adhering to the large roller end surface, and functions as lubricating oil at the front side end surface. Oil adherence to the roller end surface is steadily generated regardless of the revolution position of all the rollers, and the dilute starvation of the lubricating oil on the roller end surface can be suppressed.

  In the present invention, the nozzle may be an annular slit concentric with the tapered roller bearing. In this configuration, since the nozzle is an annular slit concentric with the tapered roller bearing, air oil is uniformly supplied from the nozzle to the bearing inner space between the inner ring and the outer ring in the circumferential direction. In combination with the pumping action that occurs in association with the rotation of the bearing, the supply of air oil and the adhesion of oil to the lubrication-necessary site are effectively performed.

  In the present invention, the radial position of the discharge port of the nozzle may be a position between the inner diameter edge of the cage and the outer diameter edge of the inner ring at the end on the bearing back side. By setting the position of the discharge port of the nozzle in this way, the air oil is smoothly sucked and introduced from the discharge port of the nozzle into the through hole, and the lubrication function is more effectively exhibited.

  The lubricating structure of the tapered roller bearing according to the present invention is such that the roller of the tapered roller bearing is a hollow roller having a through-hole penetrating at both ends, and is adjacent to the back side of the tapered roller bearing, and the bearing inner space between the inner ring and the outer ring Since the nozzle that supplies air oil for lubrication is provided, the air oil supplied from the nozzle adheres to the outer diameter surface of the raceway surface and is used for lubrication, and pumping accompanying the rotation of the bearing Due to the action, the oil flows into the through-hole and is also used for lubrication of the large end of the roller on the front side, and can evenly supply lubricating oil to the roller end face over the entire circumference of the bearing, so that the stirring resistance is low, and the lubricating oil on the roller end face This is suitable for high-speed driving without the occurrence of the starvation. Further, only by supplying air oil from the back side of the bearing, the sliding portion on the front side of the bearing is effectively lubricated, and the number of components and the amount of air consumed by the air oil can be reduced.

  An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an example of a high-speed spindle device having a tapered roller bearing lubrication structure of this embodiment. The spindle device 24 is applied to a machine tool, and a tool or workpiece chuck is attached to the front side (machining side) end of the main shaft 25. The main shaft 25 is supported by a plurality (two in this case) of tapered roller bearings 1 separated in the axial direction. The inner ring 2 of each tapered roller bearing 1 is fitted to the outer diameter surface of the main shaft 25, and the outer ring 3 is fitted to the inner diameter surface of the bearing box 26. As for the tapered roller bearing 1 on the front side of the main shaft, the inner ring 2 is fixed in the bearing box 26 by the stepped surface 25a of the main shaft 25 and the outer ring 3 by the pressing lid 28A through the first outer ring spacer 6. As for the tapered roller bearing 1 on the rear side of the main shaft, the inner ring 2 is fixed in the bearing box 26 by the inner ring positioning spacer 27 and the outer ring 3 is fixed by the pressing lid 28B through the first outer ring spacer 6. The bearing box 26 has a double structure of an inner peripheral bearing box 26A and an outer peripheral bearing box 26B, and a cooling groove 29 is formed between the inner and outer bearing boxes 26A, 26B. A second outer ring spacer 7 is disposed on the back side of the outer ring 3 of both tapered roller bearings 1, and an inner peripheral bearing box 26 </ b> A is interposed between the outer ring spacers 7. An inner ring spacer 30 is interposed between the inner rings 2 of the both tapered roller bearings 1. A bearing fixing nut 31 that presses against the inner ring positioning spacer 27 and fixes the tapered roller bearing 1 is screwed to the rear end portion of the main shaft 25.

  The holding lids 28A and 28B are provided with air oil introduction holes 33 for introducing air oil from air oil supply devices 32A and 32B which are air oil supply sources for air oil lubrication of the tapered roller bearing 1, respectively. It communicates with an air oil supply path 34 provided in the inner peripheral bearing box 26A. In addition, oil pressure holes 35 are provided in the presser lids 28A and 28B, and these oil pressure holes 35 communicate with an oil drain path 36 provided in the inner circumferential receiving box 26A. In air oil lubrication, lubricating oil is mixed with carrier air and supplied.

  As shown in the sectional views of FIGS. 2 and 3, the tapered roller bearing 1 includes a single row having an inner ring 2, an outer ring 3, and a tapered roller 4 that is a rolling element interposed between the inner and outer rings 2 and 3. Tapered roller bearing. The inner ring 2 has a raceway surface 2a that is a conical surface on the outer diameter surface, and a large collar 2b and a small collar 2c on the large diameter side and the small diameter side of the outer diameter, respectively. The outer ring 3 has a raceway surface 3 a that is a conical surface on the inner diameter surface facing the raceway surface 2 a of the inner ring 2. A plurality of tapered rollers 4 are movably interposed between the raceway surfaces 2a and 3a. These tapered rollers 4 are held by a cage 5 at a predetermined interval in the circumferential direction. The tapered roller 4 is a hollow roller having a through hole 4a penetrating through both ends at the center thereof along the axial direction. In addition, illustration of the holder | retainer 5 is abbreviate | omitted in FIG.

  The lubricating structure of the tapered roller bearing in the spindle device 24 is such that an outer ring spacer 7 having an oil supply passage 8 for supplying air oil to the tapered roller bearing 1 is disposed adjacent to the back side of the tapered roller bearing 1. The oil supply passage 8 of the outer ring spacer 7 communicates with the air oil supply passage 34 of the inner peripheral bearing box 26A. The outer ring spacer 7 includes a spacer body 7a and a slit forming component 7b, and an oil supply path 8 is formed in the spacer body 7a. An annular slit nozzle 9 concentric with the tapered roller bearing 1 is formed between the inner diameter surface of the spacer main body 7a and the outer diameter surface of the slit forming component 7b. The slit nozzle 9 has a gap size of 0.05 to 0.1 mm. The oil supply passage 8 extends from the outer surface of the spacer main body 7a toward the inner diameter side and opens into a circumferential groove 9a formed over the entire inner diameter surface of the spacer main body 7a. The slit nozzle 9 communicates with the oil supply passage 8 through 9a. The radial position of the discharge port 9b of the slit nozzle 9 is a position between the inner diameter edge of the cage 5 and the outer diameter edge of the small collar 2c of the inner ring 2 at the end on the bearing back side. The air oil supplied from the air oil supply path 34 of the inner peripheral bearing box 26A to the oil supply path 8 is discharged from the discharge port 9b of the slit nozzle 9 toward the inner diameter side of the cage 5 in the bearing space S of the inner ring 2 and the outer ring 4. The

  The two outer ring spacers 6 and 7 are attached to an inner peripheral bearing box 26A to which the outer ring 3 of the bearing 1 is attached. An oil drain hole 6 a is formed in the first outer ring spacer 6 on the outer ring 3 side, with one end opening on the large end surface 4 b side of the roller 4 and the other end opening on the outer diameter surface side of the outer ring spacer 6. ing. Further, an oil drain hole 7c is formed in the portion of the second outer ring spacer 7 on the outer ring 3 side so that one end opens to the small end surface 4c side of the roller 4 and the other end opens to the outer diameter surface side of the outer ring spacer 7. Has been. Air oil supplied as lubricating oil into the bearing 1 is discharged from the oil drain holes 6a and 7c provided in the outer ring spacers 6 and 7 to the outside through the oil drain passage 36 (FIG. 1) of the inner peripheral bearing box 26A. Discharged.

The operation of the lubricating structure of the tapered roller bearing will be described. The air oil supplied from the air oil supply devices 32 </ b> A and 32 </ b> B reaches the oil supply path 8 of the outer ring spacer 7 through the air oil supply path 34 of the bearing box 26. The air oil that has reached the oil supply path 8 is accelerated by the slit nozzle 9 from the circumferential groove 9a, is discharged from the discharge port 9b, and is injected to the small end face 4c portion of the tapered roller. The air oil discharged from the slit nozzle 9 becomes two flows by the pumping action generated by the rotation of the bearing, and lubricates the tapered roller bearing 1 while passing through the tapered roller bearing 1.
One is a flow along the raceway surface 3 a of the outer ring 3 from the back side to the front side of the tapered roller bearing 1. The air oil is blown in the direction of the outer ring raceway surface 3a by the centrifugal force accompanying the rotation, and flows along the raceway surface 3a from the smaller diameter side (back side) of the outer ring 3 toward the larger diameter side (front side). At this time, the oil in the air oil adheres to the raceway surface 3a of the outer ring 3 by centrifugal force and serves as lubricating oil for the rolling portion with the rolling surface of the tapered roller 4.

  Another flow is a flow in the through hole 4 a of the tapered roller 4. The through hole 4a of the tapered roller 4 has an inclined structure in which the diameter of the circumference connecting the center of the bearing back side opening 4aa of each tapered roller 4 is smaller than the diameter of the circumference connecting the center of the bearing front side opening 4ab. Therefore, a pumping action is generated in the through hole 4a, and the air in the vicinity of the bearing back side opening 4aa is sucked into the through hole 4a, moved to the front side, and exhausted. At this time, the air oil a discharged from the slit nozzle is also sucked into the through hole 4a from the bearing back side opening 4aa (see arrow b in FIG. 3). In the through-hole 4a, the oil in the air oil adheres to the inner wall surface of the through-hole 4a due to the centrifugal force caused by the rotation and revolution of the tapered roller 4 and moves in the direction of the front side (see arrow c in FIG. 3). )

  The oil that has reached the front opening 4ab moves while adhering from the wall surface of the through hole 4a to the roller large end surface 4b from the edge of the front opening 4ab (see arrow d in FIG. 3). The oil that has moved to the roller large end surface 4b is a sliding portion between the large collar 2b of the inner ring 2 and the large end surface 4b, and is surely supplied to the site where the lubricating oil is most needed. Served as lubricating oil. Further, since the movement of the oil to the roller large end face 4b is performed in the total number of tapered rollers 4, a lubricating action can be expected from the entire circumference of the tapered rollers 4, and the inner ring 2 between the large collar 2b and the large end face 4b, This is effective for suppressing the dilute starvation of the lubricating oil and also reduces the stirring resistance. As a result, the tapered roller bearing 1 can be rotated at a high speed.

Thus, since the tapered roller 4 is a hollow roller having a through hole 4a, the inner ring 2 on the front side of the bearing can be obtained only by supplying air oil from the back side of the bearing without providing air oil supply means on the front side of the bearing. Lubrication of the sliding portion between the large flange 2b and the large end surface 4b is effectively performed, the number of parts can be reduced and the amount of air consumed by air oil can be reduced, and the lubricating structure is simplified. In addition, since each flange lubricating oil is steadily supplied from the total number of rollers 4, it is difficult for the lubricating oil to be diluted in the large end face 4b of the roller, and the speed can be further increased.
In addition, by making the connection part 4ac from the front side opening 4ab to the roller large end surface 4b into the R surface, oil scattering from the roller large end surface 4b is prevented, and oil movement to the roller large end surface 4b is made more effective. The

  Further, since the slit nozzle 9 has an annular shape concentric with the tapered roller bearing 1, the air oil discharged from the discharge ports 9b acts equally on all the tapered rollers 4, and lubricates the large roller end surface 4b. The suppression of oil starvation becomes more effective. Further, the radial position of the discharge port 9b of the slit nozzle 9 is the position between the inner diameter edge of the cage 5 and the outer diameter edge of the small collar 2c of the inner ring 2 at the end on the bearing back side. The air oil discharged from the discharge port 9b is efficiently sucked into the through hole 4a from the bearing back side opening 4aa, and compared to the case where the air oil is directly injected into the roller or the cage using the nozzle, Wind noise is reduced and noise can be reduced.

  In the above embodiment, an example of a single-row tapered roller bearing has been described, but a double-row tapered roller bearing may be used.

It is sectional drawing of the spindle apparatus provided with the lubrication structure of the tapered roller bearing concerning one Embodiment of this invention. It is an expanded sectional view of the lubricating structure of the tapered roller bearing. FIG. 3 is a further enlarged view of FIG. 2 and shows the flow of air oil. It is sectional drawing of the spindle apparatus provided with the lubrication structure of the conventional tapered roller bearing. It is an expanded sectional view of the lubricating structure of the tapered roller bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Tapered roller bearing 2 ... Inner ring 3 ... Outer ring 4 ... Tapered roller 4a ... Through-hole 5 ... Cage 9 ... Slit nozzle a ... Air oil S ... Bearing space

Claims (3)

  The roller of the tapered roller bearing is a hollow roller having a through-hole penetrating at both ends, and a nozzle that supplies air oil for lubrication to the bearing inner space between the inner ring and the outer ring is provided adjacent to the back side of the tapered roller bearing. Lubricating structure for tapered roller bearings.   2. The lubricating structure of a tapered roller bearing according to claim 1, wherein the nozzle is an annular slit concentric with the tapered roller bearing.   3. The tapered roller bearing according to claim 1, wherein the radial position of the discharge port of the nozzle is a position between the inner diameter edge of the cage and the outer diameter edge of the inner ring at the end on the back side of the bearing. Construction.

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