JP2010091065A - Bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device having simple construction preventing an unnecessary slip inside bearings when a fixed-position preload escapes. <P>SOLUTION: A spindle 3 of a machine tool is installed on a housing 2 via the load-side bearing 5A and the counter-load-side bearing 5B. Both bearings 5A, 5B are angular ball bearings arranged back to back. The load-side bearing 5A has an outer ring 11A which is positioned and fixed onto the housing 2 in the axial direction, and the counter-load-side bearing 5B has an outer ring 11B which is not positioned and fixed to the housing 2 in the axial direction. The axial positions of inner rings 12A, 12B of both bearings 5A, 5B are restricted to give the fixed-position preload to both bearings 5A, 5B. Between the back face of the outer ring 11B of the counter-load-side bearing 5B and the housing 2, an elastic body 10 is laid for energizing the outer ring 11B of the counter-load-side bearing 5B to the front-face side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bearing device including a multi-row angular ball bearing used for supporting a machine tool spindle.

  A multi-position angular contact ball bearing of a fixed position preload combination used for supporting a machine tool spindle is used in a state where a certain preload is applied during assembly in order to obtain spindle rotation accuracy and rigidity. However, when receiving a large axial load during processing, preload loss may occur in the bearing on the opposite load side. In particular, preload loss often occurs when the amount of preload is still small in the low speed rotation range. Usually, in consideration of excessive preload in the high speed rotation range, the preload amount at the time of incorporation is often set small.

  As an example of the arrangement of the angular ball bearings of the fixed position preload combination, there is an example in which two rows of angular ball bearings 25A and 25B are arranged in a back-to-back orientation as shown in FIG. In general, in such a bearing arrangement, when the angular ball bearings 25A and 25B assembled with the preload amount Ga receive an axial load F (= 2.828 × Ga) that is 2.828 times the preload amount Ga, as shown in FIG. On the other hand, the preload of the angular ball bearing 25B on the anti-load side is lost.

  FIG. 11 is an explanatory view of the preload loss. In FIG. 11A, I indicates a load-side bearing, II indicates an anti-load-side bearing, Fo indicates a preload amount, Fa indicates an axial load, and δo indicates an axial relative displacement amount between the inner and outer rings. . FIG. 11B is a diagram in which the configuration of FIG. 11A is replaced with an equivalent spring mechanism. (1) is before the preload, (2) is after the preload, and (3) is the axial load action. Each state is shown. FIG. 11C is a graph showing the relationship between the axial load acting on each angular ball bearing and the axial displacement of the inner ring. 10 and 11, it can be seen that when the inner ring moves in the axial direction by the displacement δo due to the load of the axial load F, the preload of the angular ball bearing on the non-load side is released. That is, the load-side angular ball bearing 25B is elastically deformed by the displacement amount δo by receiving the axial load F.

Therefore, in order to prevent preload loss even when a relatively large axial load is applied in the low-speed rotation range, a certain amount of preload can be secured in advance during assembly, and operation is possible without excessive preload up to the high-speed rotation range. One having a preload switching mechanism is known (for example, Patent Document 1).
Japanese Patent No. 2602325

As described above, when preload loss occurs during rotation of the main shaft, a gap is generated inside the anti-load side bearing 25B as shown in FIG. It is not appropriate to use the bearing in a state where there is a gap, and an oil film is not formed well between the raceway surface and the ball due to unnecessary sliding, which may cause adverse effects such as metal contact. If a large amount of preload is set so that preload is not lost, preload loss can be prevented. However, when operating at high speed, there is a risk of overheating due to thermal expansion and centrifugal force, leading to an overheating condition.
If a preload switching mechanism is used as in the technique disclosed in Patent Document 1, it is possible to set a large preload at the time of incorporation, and an excessive preload in the high speed rotation region can be avoided, but the structure becomes complicated. is there.

  An object of the present invention is to provide a bearing device that can prevent unnecessary slip inside a bearing when a preload loss occurs with a simple structure.

The bearing device according to the present invention is configured such that a main shaft of a machine tool is disposed on a load side, which is an end portion where a load acts on the main shaft, and a bearing disposed on an anti-load side with respect to the load side bearing. The load-side and anti-load-side bearings installed in the housing are angular ball bearings, respectively, facing each other, and the load-side bearing has the outer ring fixed in the axial direction with respect to the housing. The load-side bearing is a bearing device in which the outer ring is fixed in a non-positional position with respect to the housing in the axial direction, the axial positions of the inner rings of the bearings on both sides are regulated, and a fixed position preload is applied to both the bearings. An elastic body for biasing the outer ring of the anti-load side bearing toward the front side is interposed between the rear surface of the outer ring of the side bearing and the housing.
According to this configuration, since the elastic body for biasing the outer ring of the bearing on the anti-load side to the front side is provided, the outer ring is moved to the front side even after the pre-load release in the fixed position pre-load occurs in the bearing of the anti-load ring. Continues energizing with light axial load. For this reason, there is no gap in the interior of the bearing on the anti-load side, and the bearing can be rotated without unnecessary slip. That is, in this bearing device, an unnecessary slip inside the bearing when preload loss occurs can be prevented with a simple structure.

  In this invention, the elastic body may be an O-ring concentric with the bearing. When an O-ring is used, the configuration can be further simplified, the pressing force can be reduced, and the influence of excessive preload can be avoided by adding the pressing force by the elastic body to the preload by the fixed position preload.

  In the present invention, the elastic body may be a plurality of coil springs distributed in the circumferential direction. When a coil spring is used, it is easy to obtain an appropriate pressing force.

  In this invention, the elastic body may be a disc spring concentric with the bearing. When the disc spring is used, it is easy to make the pressing force by the elastic restoring force strong when the preload loss of the fixed position preload occurs.

  In this invention, between the outer ring of the bearing on the load side and the outer ring of the bearing on the anti-load side, an annular inner diameter protruding to the inner diameter side from the bearing fitting surface on which the outer rings of the bearings on both sides of the housing are fitted A side protrusion may be interposed, and the elastic body may be provided on the end face of the inner diameter side protrusion. By providing the elastic body on the housing side in this way, it is not necessary to perform processing for arranging the elastic body on the bearing outer ring, and a bearing having a normal configuration can be used as it is.

  In this invention, you may provide the said elastic body in the outer ring | wheel of the bearing of the said anti-load side. When the outer ring of the bearing is provided with an elastic body, the bearing can be manufactured and prepared with an elastic body, and the housing does not require processing for the arrangement of the elastic body. Configuration becomes easy.

  In this invention, between the outer ring of the bearing on the load side and the outer ring of the bearing on the anti-load side, an annular inner diameter protruding to the inner diameter side from the bearing fitting surface on which the outer rings of the bearings on both sides of the housing are fitted A side protrusion may be interposed, and an outer ring spacer may be disposed between the inner diameter side protrusion and the outer ring of the bearing on the anti-load side, and the elastic body may be provided in the outer ring spacer. When an elastic body is provided in the outer ring spacer, the elastic body is provided in the outer ring spacer, which is a member that is smaller than the housing and is simpler than the bearing outer ring. Thus, the configuration can be further simplified.

  In the present invention, either one or both of the load side and the anti-load side may be a combination of a plurality of rows of bearings. Even in such a combination of a plurality of rows of bearings, an effect of preventing unnecessary slipping inside the bearing when preload is lost can be obtained.

The machine tool spindle device of the present invention is obtained by supporting the spindle of a machine tool with the bearing device having any one of the configurations of the present invention.
According to this configuration, even if a pressure loss occurs in the bearing device, unnecessary slip inside the bearing can be prevented, so that the spindle rotation accuracy and rigidity can be ensured, and the machining accuracy can be improved.

The bearing device according to the present invention is configured such that a main shaft of a machine tool is disposed on a load side, which is an end portion where a load acts on the main shaft, and a bearing disposed on an anti-load side with respect to the load side bearing. The load-side and anti-load-side bearings installed in the housing are angular ball bearings, respectively, facing each other, and the load-side bearing has the outer ring fixed in the axial direction with respect to the housing. The load-side bearing is a bearing device in which the outer ring is fixed in a non-positional position with respect to the housing in the axial direction, the axial positions of the inner rings of the bearings on both sides are regulated, and a fixed position preload is applied to both the bearings. Because the elastic body that urges the outer ring of the load side bearing toward the front side is interposed between the rear surface of the outer ring of the side bearing and the housing, the inside of the bearing is not required when preload loss occurs due to a simple structure. Nasube It can be prevented.
In the machine tool spindle device of the present invention, since the spindle of the machine tool is supported by the bearing device of the invention, even if a preload loss occurs in the bearing device, unnecessary slip inside the bearing can be prevented, and the spindle rotation accuracy and rigidity can be prevented. Can be ensured, and the processing accuracy can be improved.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1A is a sectional view of a spindle device of a machine tool in which the bearing device of this embodiment is used. The main shaft device 1 is a housing 2 in which a main shaft 3 is rotatably supported by a bearing device 4. The spindle 3 has a tool or spindle chuck (both not shown) attached to the front end 3a. The bearing device 4 is a multi-row angular contact ball bearing.

  The bearing device 4 includes a bearing 5A disposed on the front end side, that is, a load side that is an end portion side where a load acts on the main shaft 3, and a bearing 5B disposed on the side opposite to the bearing 5A. , 5B, the front end side of the main shaft 3 is installed in the housing 2. The load-side and anti-load-side bearings 5A and 5B are formed of angular ball bearings having outer rings 11A and 11B, inner rings 12A and 12B, balls 13A and 13B, and cages 14A and 14B for holding the balls 13A and 13B, respectively. , They are facing each other. Between the outer ring 11A of the bearing 5A on the load side and the outer ring 11B of the bearing 5B on the anti-load side, the inner diameter side of the bearing fitting surface where the outer rings 11A and 11B of the bearings 5A and 5B on both sides of the housing 2 are fitted. An annular inner-side protruding portion 2a protruding is interposed. An inner ring spacer 6 is interposed between the inner rings 12A and 12B of both bearings 5A and 5B.

  The load-side bearing 5 </ b> A has its outer ring 11 </ b> A fixed in the axial direction with respect to the housing 2. Specifically, the outer ring 11A of the bearing 5A on the load side is fixed in the axial direction by being sandwiched between the outer ring holding lid 7 fixed to the front end of the housing 2 and the end surface of the inner diameter side protruding portion 2a of the housing 2. Has been. The bearing 5B on the non-load side has its outer ring 11B fixed to the housing 2 in the axial direction. Specifically, the outer ring 11 </ b> B of the bearing 5 </ b> B on the opposite load side is loosely fitted to the bearing fitting surface of the housing 2.

  The axial positions of the inner rings 12A and 12B of the both bearings 5A and 5B are restricted. Specifically, one end face of the inner ring 12A of the bearing 5A on the load side is engaged with the end face of the shoulder portion 3b protruding from the outer periphery of the main shaft 3, and the inner ring spacer 6 is interposed between the inner rings 12A and 12B of both bearings 5A and 5B. The one end surface of the inner ring 12B of the bearing 5B on the opposite load side is fastened with a nut 9 via a spacer 8 which is a cylindrical member. As a result, the axial positions of the inner rings 12A and 12B of both bearings 5A and 5B are restricted, and a fixed position preload is applied to both bearings 5A and 5B.

  Between the back surface of the outer ring 11B of the bearing 5B on the anti-load side and the housing 2, an elastic body 10 that urges the outer ring 11B of the bearing 5B on the anti-load side to the front side is interposed. Specifically, as shown in FIG. 1 (B), which is an enlarged view of portion A in FIG. 1 (A), an annular circumferential groove 15 concentric with the bearings 5A and 5B on the end face of the inner diameter side protruding portion 2a of the housing 2. And an O-ring is accommodated as the elastic body 10 in the circumferential groove 15. The elastic body 10 made of an O-ring is compressed in a state where the fixed position preload is applied to both the bearings 5A and 5B, and the outer ring 11A of the anti-load side bearing 5B is urged to the front side by the restoring force. Yes.

FIG. 2 (A) shows that in the bearing device 4, an axial load F is applied to the load-side bearing 5 </ b> A from the outside during rotation of the main shaft 3, and preload loss in the fixed position preload occurs in the non-load-side bearing 5 </ b> B. Indicates the state. At this time, in the case of the conventional configuration in which the elastic body 10 is not interposed as shown in FIG. 3, as shown in an enlarged view in FIG. 4, the axial load F is not applied (FIG. 4 (A)). When the load F is applied and the preload loss occurs in the bearing 5B on the opposite load side, the outer ring 11B is rattled in the axial direction. In this case, an oil film is not formed well between the raceway surfaces of the inner and outer rings 12B and 11B and the ball 13B due to unnecessary slip, and there is a possibility that an adverse effect such as metal contact may occur.
On the other hand, in the bearing device 4 of this embodiment, the outer ring 11B of the bearing 5B on the anti-load side is biased to the front side by the elastic body 10, and the B part in FIG. As shown in FIG. 2B, the O-ring which is the elastic body 10 is not completely restored even after the preload loss occurs in the bearing 5B of the anti-load wheel, and the outer ring 11B is lightly moved to the front side. Continues energizing with directional load. For this reason, there is no gap in the bearing 5B on the anti-load side, and the bearing 5B can rotate without causing unnecessary slip. That is, in this bearing device 4, an unnecessary slip inside the bearing 5B when a preload loss occurs can be prevented with a simple structure.

  Further, the spindle device 1 of the machine tool provided with the bearing device 4 can prevent unnecessary slip inside the bearing even when a preload loss occurs in the bearing device 4, so that the spindle rotation accuracy and rigidity can be ensured. .

  FIG. 5 shows another embodiment of the present invention. In this embodiment, in the bearing device 4 shown in FIG. 1 to FIG. 4, an elasticity composed of a plurality (6 to 10) of coil springs between the back surface of the outer ring 11B of the bearing 5B on the anti-load side and the housing 2 is provided. The body 10A is interposed. Specifically, a plurality of concave portions 16 are provided in the circumferential direction on the end surface of the annular inner shape protruding portion 2a protruding toward the inner diameter side of the housing 2, and a coil spring is provided as an elastic body 10A in these concave portions 16. Each is housed. The recess 16 is formed of a round hole or the like. The elastic body 10A made of a coil spring is compressed in a state where the fixed position preload is applied to both the bearings 5A and 5B, and the outer ring 11A of the anti-load side bearing 5B is urged to the front side by the restoring force. Yes. Thus, when a coil spring is used as the elastic body 10A, it is easy to obtain an appropriate pressing force. Other configurations and operational effects are the same as those of the embodiment of FIGS.

  FIG. 6 shows still another embodiment of the present invention. In this embodiment, in the bearing device 4 shown in FIGS. 1 to 4, an elastic body formed of a disc spring concentric with the bearings 5 </ b> A and 5 </ b> B between the rear surface of the outer ring 11 </ b> B of the bearing 5 </ b> B on the anti-load side and the housing 2. 10B is interposed. Specifically, an elastic body 10B made of a disc spring is interposed between the end surface of the annular inner side protruding portion 2a protruding toward the inner diameter side of the housing 2 and the back surface of the outer ring 11B of the bearing 5B facing this. I am letting. Thus, when a disc spring is used as the elastic body 10B, it is easy to make the pressing force by the elastic restoring force strong when the preload loss of the fixed position preload occurs. Other configurations and operational effects are the same as those of the embodiment of FIGS.

  FIG. 7 shows still another embodiment of the present invention. In this embodiment, in the bearing device 4 shown in FIGS. 1 to 4, an annular circumferential groove 17 concentric with the bearings 5 </ b> A and 5 </ b> B is provided on the back surface of the outer ring 11 </ b> B of the bearing 5 </ b> B on the opposite load side. An O-ring is accommodated as the elastic body 10C. When the elastic body 10C is provided on the outer ring 11B of the bearing 5B in this way, the bearing 5B can be manufactured and prepared with an elastic body, and processing for arranging the elastic body is not required on the housing 2 side. Thus, the structure of the housing 2 that becomes the spindle housing of the machine tool becomes easy. Other configurations and operational effects are the same as those of the embodiment of FIGS.

  FIG. 8 shows still another embodiment of the present invention. In this embodiment, in the bearing device 4 shown in FIGS. 1 to 4, an outer ring spacer 18 is disposed between the inner diameter side protruding portion 2 a of the housing 2 and the outer ring 11 B of the bearing 5 B on the opposite load side. An elastic body 10D is interposed between the spacer 18 and the inner diameter side protruding portion 2a. Specifically, an annular circumferential groove 19 concentric with the bearings 5A and 5B is provided on an end surface of the outer ring spacer 18 facing the inner diameter side protruding portion 2a, and an O-ring is accommodated in the circumferential groove 19 as an elastic body 10D. is doing. When the elastic body 10D is provided in the outer ring spacer 18, the elastic body 10D is provided in the outer ring spacer 18 which is a member which is smaller than the housing 2 and has a simple shape as compared with the bearing outer ring 11B. While providing the elastic body 10D, the configuration can be further simplified. Other configurations and operational effects are the same as those of the embodiment of FIGS.

FIG. 9 shows still another embodiment of the present invention. In this embodiment, in the bearing device 4 shown in FIGS. 1 to 4, the load-side bearing 5 </ b> A and the anti-load-side bearing 5 </ b> B are each a combination of two rows of bearings. Specifically, as the bearing 5A on the load side, angular ball bearings with the front side facing the front end 3a side of the main shaft 3 are arranged in two rows in the axial direction, and as the bearing 5B on the anti-load side, the front side is the main shaft 3 Angular ball bearings facing the rear end are arranged in two rows in the axial direction. Of the two rows of bearings 5B and 5B on the opposite load side, the elastic body 10 is interposed between the back surface of the outer ring 11B of the bearing 5B near the inner diameter side protruding portion 2a of the housing 2 and the inner diameter side protruding portion 2a. . As described above, even when the plurality of bearings 5A, 5A and the bearings 5B, 5B are arranged side by side, an effect of preventing an excessive slip when the fixed position preload is released can be obtained. Other configurations and operational effects are the same as those of the embodiment of FIGS.
In the embodiment shown in the figure, the type of elastic body and the elastic body installation structure shown in FIGS. The number of bearing arrangements of the load-side bearing 5A and the anti-load-side bearing 5B is not limited to two, and may be three or more, and only one of the bearings 5A and 5B is a plurality of rows. Also good.

  In each of the above embodiments, the front side bearing of the housing 1 is the load side bearing 5A and the rear side bearing is the anti-load side bearing 5B. However, the front side bearing is a bearing device comprising an array of a plurality of angular ball bearings. The rear side bearing may be configured by a bearing device including an arrangement of cylindrical roller bearings, and the present invention may be applied to the front side bearing device.

(A) is sectional drawing of the spindle apparatus of the machine tool carrying the bearing apparatus concerning 1st Embodiment of this invention, (B) is an enlarged view of the A section in (A). (A) is sectional drawing which shows the preload loss state of the bearing apparatus, (B) is an enlarged view of the B section in (A). It is sectional drawing which shows the structure of the prior art example which abbreviate | omitted the elastic body in the bearing apparatus of FIG. 1 (A). It is explanatory drawing of the preload loss state in the bearing apparatus of the structure of FIG. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. It is explanatory drawing of the preload loss state in a prior art example. It is explanatory drawing of preload loss.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main shaft apparatus 2 ... Housing 2a ... Inner diameter side protrusion part 3 ... Main shaft 4 ... Bearing apparatus 5A ... Load side bearing 5B ... Anti-load side bearings 10, 10A, 10B, 10C, 10D ... Elastic bodies 11A, 11B ... Outer ring 12A, 12B ... Inner ring 18 ... Outer ring spacer

Claims (9)

The spindle of the machine tool is installed in the housing via a bearing arranged on the load side, which is the end side where the load acts on the spindle, and a bearing arranged on the opposite side of the load side bearing, and the load The bearings on the side and the anti-load side are angular ball bearings, respectively, facing each other, the bearing on the load side fixes the outer ring in the axial direction with respect to the housing, and the anti-load side bearing has the outer ring In the bearing device in which the housing is non-positionally fixed in the axial direction, the axial positions of the inner rings of the bearings on both sides are regulated, and a fixed position preload is applied to both the bearings
A bearing device characterized in that an elastic body for biasing the outer ring of the anti-load side bearing toward the front side is interposed between the rear surface of the outer ring of the anti-load side bearing and the housing.   The bearing device according to claim 1, wherein the elastic body is an O-ring concentric with the bearing.   The bearing device according to claim 1, wherein the elastic body is a plurality of coil springs distributed in the circumferential direction.   The bearing device according to claim 1, wherein the elastic body is a disc spring concentric with the bearing.   5. The bearing fitting surface according to claim 1, wherein the outer rings of the bearings on both sides of the housing are fitted between the outer ring of the bearing on the load side and the outer ring of the bearing on the anti-load side. A bearing device in which an annular inner diameter side protruding portion that protrudes further toward the inner diameter side is interposed, and the elastic body is provided on an end surface of the inner diameter side protruding portion.   The bearing device according to claim 1, wherein the elastic body is provided on an outer ring of the bearing on the anti-load side.   5. The bearing fitting surface according to claim 1, wherein the outer rings of the bearings on both sides of the housing are fitted between the outer ring of the bearing on the load side and the outer ring of the bearing on the anti-load side. An annular inner diameter protruding portion that protrudes further toward the inner diameter side is interposed, and an outer ring spacer is disposed between the inner diameter side protruding portion and the outer ring of the bearing on the anti-load side, and the elastic body is disposed on the outer ring spacer. Bearing device provided with.   5. The bearing device according to claim 1, wherein one or both of the load side and the anti-load side bearings are a combination of a plurality of rows of bearings. 6.   A machine tool spindle device in which a spindle of a machine tool is supported by the bearing device according to any one of claims 1 to 8.

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