JPH0968231A - Spindle supporting device and bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the speed by surely feeding the air oil, to improve the rotational accuracy by improving the assembly accuracy of a bearing, to reduce the number of parts, and to realize miniaturization. SOLUTION: A spindle 1 is supported by a housing 5 at two points through bearing parts A, B consisting of a plurality of angular ball bearings. A nozzle 21 for ejecting the air oil which is open toward an inner ring rolling surface side and a discharge passage 22 of the ejecting air oil are provided on an outer ring 16 of each bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle support device and a bearing for use in a high-speed spindle bearing device for machine tools and other general equipment, and in the case of rolling oil bearings such as angular ball bearings with air-oil lubrication or jet lubrication. .

[0002]

2. Description of the Related Art FIG. 3 shows an example of the construction of a machine tool spindle bearing device when an angular ball bearing is air-oil lubricated.
The bearings 52 (52 _{A to} 52 _D ) are connected to the shaft 51 through the spacer 53 a and the nozzle-equipped spacer 56 in a parallel rear face combination.
And a bearing box 55, and fixed with a nut 54 and a lid 57. In the spacer 56 with nozzle, a nozzle 58 for supplying bearing lubricating oil is formed from the back side of the bearing toward the inner race rolling surface. To lubricate the bearing, the oil mixed with the carrier air in the air-oil supply unit 62 is supplied from the pipe 63 to the bearing box supply hole 61 and the circumferential groove 60 on the outer diameter surface of the spacer 56 with a nozzle.
It is performed by ejecting from the nozzle 58 via and. The air oil exhausted for lubrication is exhausted from the exhaust hole 64. The initial preload of the bearing, the outer ring size difference in the width dimension and an inner bearing 52 _B, 52 _C of the inner ring spacer 53b, given by adjusting the axial clearance of the bearing. At this time, the width dimensions of the bearings 52 _A and 52 _B and the inner and outer ring spacers 53 a 56 between the bearings 52 _C and 52 _D must be the same.

[0003]

There are two problems that are likely to occur in the above conventional technique. One is the outer ring spacer 56
The air oil leaks at the fitting portion between the bearing housing 55 and the bearing box 55. In general, the fit of the outer ring spacer 56 is loosely fitted because of a problem of assembling. However, if there is a gap in the fitting portion, air-oil leakage will occur from that portion, and the amount of ejection from the nozzle 58 will be reduced. That is, the leakage of the air oil from the fitting portion leads to a decrease in the air oil ejection speed and a decrease in the amount of lubricating oil supplied to the bearing, which is a factor that impedes speeding up. It also leads to waste of air and oil.

Secondly, it affects the accuracy of rotation of the spindle.
It is the accuracy of the spacer accuracy of the inner and outer rings. In the example of FIG. 3, a spacer of 3 points on the inner ring side and a spacer of 4 points on the outer ring side are used to fix the bearing 52. However, if the number of parts increases in this way, the cumulative error of accuracy increases. Therefore, the original function of the bearing cannot be fully utilized, and the rotation accuracy and the like often deteriorate. In order to improve the rotational accuracy of the main shaft, it is important to reduce the number of parts as much as possible and make full use of the bearing functions. In this way, further speedup in the future,
In machine tool main bearings, which require high precision, it is necessary to improve the air-oil supply method and ensure the precision when assembling the bearings. The above problems also occur in the case of jet lubrication.

The present invention solves the above problems, and by making the bearing and the nozzle an integral structure, it is possible to speed up the spindle by ensuring the supply of a lubricating fluid such as air oil, and to improve the accuracy of bearing assembly. It is an object of the present invention to provide a spindle support device and a bearing that have improved rotation accuracy, reduced number of parts, and are compact.

[0006]

A spindle support device of the present invention supports a plurality of axially distant portions of a spindle on a housing via bearing portions each consisting of a plurality of or one rolling bearing aligned in the axial direction. It is in the form of letting. In this type of spindle support device, the rolling bearing has an outer ring having a nozzle for jetting a lubricating fluid that opens toward the inner ring rolling surface side and a discharge passage for the jetted fluid. The lubricating fluid is air oil or oil. In the above-mentioned structure, an annular shoulder portion is provided on the inner diameter surface of the housing, outer rings of a plurality of bearings of each bearing portion are arranged side by side on both sides, and an inner ring spacer is provided on the spindle corresponding to the shoulder portion. The inner rings of the plurality of bearings of each bearing may be arranged side by side on both sides thereof. In the bearing, an annular protrusion is provided on the inner diameter surface of the outer ring adjacent to the rolling surface, and a circumferential groove for supplying a lubricating fluid is provided on the outer diameter surface of the outer ring corresponding to the annular protrusion. In addition, a hole extending from the bottom surface of the circumferential groove to the inner diameter side and a nozzle for ejecting a lubricating fluid, which communicates with the hole and opens toward the inner ring rolling surface side, may be provided. Further, a cutout portion serving as the discharge path is provided in a part of the inner diameter surface of the annular protrusion in the circumferential direction.

By integrally providing the nozzle for jetting the lubricating fluid on the outer ring in this way, the outer diameter difference between the spacer with nozzle and the bearing outer ring is different from the case where a separate spacer with a nozzle is provided. It is possible to make the outer diameter dimension of the entire bearing portion the same including the nozzle formation portion without causing a problem. Therefore, the fitting gap can be reduced, leakage of the lubricating fluid such as air oil from the fitting portion can be prevented, and a stable lubricating fluid injection speed and supply amount can be secured. Moreover, since the jetting position of the lubricating fluid is fixed, the lubricating fluid can be reliably supplied to the inner ring rolling surface. Therefore, the speed can be increased. Further, since a separate spacer is not required, it is possible to prevent an increase in accuracy accumulated error, and it is easy to maintain the initial accuracy of the bearing even after the bearing is assembled in the housing. Therefore, the rotation accuracy is improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In this spindle support device, as each bearing 2 (2 _A to 2 _D ) that supports the spindle 1, a nozzle integrated type shown in FIG. 2 is used. Bearing 2
Is an angular contact ball bearing in which a rolling element 17 held by a cage 18 is interposed between an inner ring 15 and an outer ring 16 and is provided on the inner surface of the outer ring 16 on the rear surface side (that is, the contact line) with respect to the rolling surface. An annular projection 16a is integrally provided so as to be adjacent to the inclined side). The annular protrusion 16a is for forming the nozzle 21, and is provided with a circumferential groove 19 for supplying air oil on the outer ring outer diameter surface corresponding to the annular protrusion 16a. The annular protrusion 16a has a hole 2 extending from the bottom surface of the circumferential groove 19 toward the inner diameter side.
0 is provided at one or a plurality of positions in the circumferential direction, and the holes 20
Is provided with a nozzle 21 for ejecting air-oil, the base end of which communicates with the nozzle and which opens toward the inner raceway surface side. Annular protrusion 1
A cutout portion 22a serving as the discharge passage 22 is formed in a part of the inner diameter surface of 6a in the circumferential direction along the axial direction. The cutout portion 22a communicates with a radial discharge groove 22b formed in the width surface of the outer ring 16, and the cutout portion 22a and the discharge groove 22b form a discharge passage 22. Two types of bearings are used, one having the discharge groove 22b formed on the outer ring width surface and the other having no discharge groove 22b. Further, in this example, the nozzle 21 is provided at one place, and the discharge passage 22 is formed at a position shifted from this by 180 °.

FIG. 1 shows a cross section of a spindle support device using the bearing 2 of FIG. This spindle support device serves as a spindle support device for a machine tool such as a grinding machine, a machining center, or a lathe, and has a plurality of axially separated portions of the spindle 1, for example, two front and rear ends arranged in the axial direction. The rolling bearing 2 (2 _{A to} 2 _D ) is supported by the housing 5 via bearing portions A and B. The housing 5 is a bearing box that serves as a housing of a spindle head of a machine tool, and an annular shoulder portion 5a is provided at the center of the cylindrical inner diameter surface in the axial direction, and housing lids 34a and 34b are bolted at both ends. It can be installed by tightening. Bearing 2 _A , 2 of each bearing A, B
_B and the bearings 2 _C and 2 _D are arranged directly adjacent to each other with their width faces in contact, and the outer ring 16 of these bearings 2 _A to 2 _D is supported by being sandwiched between the shoulder portion 5 a of the housing 5 and the housing lids 34 a and 34 b. To be done. The inner ring 15 of each of the bearings 2 _{A to} 2 _D is fitted to the outer periphery of the spindle 1, and the inner rings 15 of the two front bearings 2 _A and 2 _{B have} the enlarged diameter portion 1 a at the front part of the spindle 1 and the central portion. It is arranged between the inner ring spacers 26a. The inner rings 15 of the two rear bearings 2 _C and 2 _D are arranged between the inner ring spacer 26 a at the center and the inner ring spacer 26 b at the rear end, and are screwed to the male screw portion 1 b at the rear end of the spindle 1. It is tightened by the nut 35. That is, each bearing inner ring 15 on the outer periphery of the spindle 1 is axially fastened together with the inner ring spacers 26a and 26b between the nut 35 and the enlarged diameter portion 1a of the spindle 1.

Four bearings 2 _A consisting of angular contact ball bearings
To 2 _D includes a front two bearings 2 _A, 2 _B, behind two bearings 2 _C, 2 and _D, arranged in a parallel back-to-back facing each other with the annular projection 16a side of the nozzle forming . In this, the outer two bearings 2 _A, 2 _D, using a bearing having a discharge groove 22b to the outer ring width surface shown in FIG. 2 (A), the discharge groove inside two bearings 2 _B, 2 _C A bearing having a shape in which 22b is omitted is used.

Explaining the air-oil path, in the housing 5, there is an in-housing supply hole 29 that communicates with the outer ring circumferential groove 19 of each of the bearings 2 _A to 2 _D from the connection ports provided in the housing lids 34 a and 34 b. The air-oil supply unit 27 is formed by a directional hole and a radial hole, and each of the connection ports is connected via a pipe 28. A discharge hole 33 is formed in the housing 5, and the discharge hole 33 is formed.
Is an axial hole 33a penetrating the inside of the housing 5 over the holes 33e of the housing lids 34a, 34b on both sides, a central radial hole 33b penetrating from the axial hole 33a to the inner diameter surface of the shoulder 5a, From the axial hole 33a to each bearing A,
It is configured by a bearing portion radial hole 33c penetrating the discharge groove 22b on the bearing width surface in B. Further, discharge holes 36 are formed in the housing lids 34a, 34b at positions corresponding to the gaps between the bearing inner and outer races 15, 16.

According to the spindle support device having this structure,
Air oil is supplied through the route of air oil unit 27-pipe 28-in-housing supply hole 29-outer ring circumferential groove 19-hole 20-nozzle 21 and sprayed onto the inner ring rolling surface. The air oil is exhausted through the exhaust holes 33 and 36. In this case, the nozzle 21 is directly formed on the bearing outer ring 16, so to speak, the bearing outer ring 16 is a conventional bearing outer ring and a nozzle-equipped spacer. for that reason,
The outer diameter of the outer ring 16 is the same over the portion corresponding to the spacer with nozzle, and the fitting gap can be made smaller than that of the conventional one. The fit between the bearing 2 and the housing 5 is typically a few microns. This means that, during operation, the outer ring 16 and the housing 5 may be in an interference fit state due to the temperature rise, and the air-oil leakage from the fitting portion is eliminated. That is, the set amount of oil and the amount of air are reliably supplied into the bearing 2, and the speed can be increased as compared with the conventional one. Moreover,
Since the nozzle 21 is integrated with the bearing outer ring 16, the jetting position of air oil is fixed, and the air oil is reliably supplied to the inner ring rolling surface.

Further, since a separate spacer with a nozzle is not required, it is easy to maintain the initial accuracy of the bearing 2 even after the bearing 2 is assembled in the housing 5. That is, in the spindle support device of this example, the inner ring spacer 2 is different from the conventional example of FIG.
Points and 4 parts of the outer ring spacer can be reduced. This means that the cumulative error caused by using a large number of spacers can be avoided, and the deterioration of the bearing mounting accuracy due to the spacers can be avoided. Also, when setting the initial preload of the bearing,
It is only necessary to adjust the two dimensions, that is, the width of the inner ring spacer 26a and the width of the shoulder portion 5a of the housing 5, and the setting can be made easier and more accurately than before.

In the above-described embodiment, the air oil is jetted from the nozzle 21, but a pressure oil supply source may be connected instead of the air oil supply unit 27 to jet jet oil from the nozzle 21. . Even in that case, the same effects as described above can be obtained.

[0015]

According to the spindle support device and the bearing of the present invention, since the nozzle for jetting the lubricating fluid such as air oil and the discharge passage for the jetted fluid are provided on the bearing outer ring, the nozzle is opened toward the inner raceway surface. The set amount of lubricating fluid can be reliably supplied into the bearing, leading to higher speed. In addition, the accuracy of assembling the bearing is improved, which leads to the improvement of the rotation accuracy of the spindle. Further, the number of parts is small, and the axial length after the bearing is assembled is small, which leads to downsizing.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a spindle support device according to an embodiment of the present invention.

FIG. 2 is a sectional view and a front view of a bearing used in the spindle support device.

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

1 ... Spindle, 2, 2 _{A to} 2 _D ... Bearing, 5 ... Housing, 5a ... Shoulder, 15 ... Inner ring, 16 ... Outer ring, 16a ... Annular protrusion, 19 ... Circumferential groove, 20 ... Hole, 21 ... Nozzle , 22
... discharge path, 22a ... notch, 22b ... discharge recess, 26a
... Inner ring spacer, 27 ... Air-oil unit, 29 ... Supply hole, 33 ... Discharge hole, 35 ... Nut, A, B ... Bearing part

Claims (4)

[Claims] 1. A spindle supporting device for supporting a plurality of axially distant portions of a spindle on a housing via bearing portions each consisting of a plurality of or one rolling bearing aligned in the axial direction. A spindle support device having an outer ring having a nozzle for jetting a lubricating fluid such as air oil or oil, which is open toward the wheel rolling surface side, and a discharge passage for the jetted fluid. 2. The spindle support device according to claim 1, wherein outer rings of a plurality of bearings of each bearing portion are arranged side by side on both sides of an annular shoulder portion projecting from an inner diameter surface of the housing, and the shoulder portion and A spindle support device in which inner rings of a plurality of bearings of each of the bearing portions are arranged side by side on both sides of an inner ring spacer provided on the spindle correspondingly. 3. An annular protrusion is provided on the inner diameter surface of the outer ring of the bearing adjacent to the rolling surface, and a circumferential groove for supplying a lubricating fluid is provided on the outer diameter surface of the outer ring corresponding to the annular protrusion. A hole extending from the bottom surface of the circumferential groove to the inner diameter side is provided in the annular projection, and the nozzle is provided in communication with the hole, and the discharge passage is provided in a part of the inner circumferential surface of the annular projection in the circumferential direction. The spindle support device according to claim 1 or 2, further comprising a notch portion. 4. An annular projection is provided on the inner diameter surface of the outer ring adjacent to the rolling contact surface, and a circumferential groove for supplying a lubricating fluid is provided on the outer ring outer diameter surface corresponding to the annular projection, The protrusion is provided with a hole extending from the bottom surface of the circumferential groove to the inner diameter side, and a nozzle for ejecting a lubricating fluid is provided which is in communication with the hole and opens toward the inner raceway surface. A rolling bearing in which a cutout portion serving as the discharge path is provided in a part of the inner diameter surface of the inner peripheral surface in the circumferential direction.