JP6417779B2 - Spindle device and machine tool equipped with the same - Google Patents

Description

  The present invention relates to a spindle device and a machine tool including the spindle device, and more particularly, to a built-in motor type spindle device for high-speed rotation used in a machine tool or a general industrial machine, and a general machine tool or a composite machine including the spindle device. It relates to processing machine tools.

  FIG. 6 shows the structure of a built-in motor type spindle device described in Patent Document 1. In FIG. 6, the housing of the spindle head 101 is divided into a front housing 102 and a rear housing 103, and both are fastened with bolts 104. The main shaft 105 is supported by the front housing 102 via the front bearings 106 and 107, and is supported by the rear housing 103 via the rear bearings 108 and 109 and the bearing case 110. The main shaft 105 includes a built-in motor rotor 111 and a draw bar 112 for clamping a tool.

JP 2007-1010 A

  By the way, the transition part of the stator coil called the end coil 114 protrudes from both axial ends of the stator 113 of the built-in motor. 6, the front housing 102 into which the front bearings 108 and 109 are fitted is formed on the outer side in the axial direction of the end coil 114, and the span between the front and rear bearings 106, 107, 108, and 109 is large. It has become. For this reason, there has been a problem that the overall length of the main shaft 105 is increased and the overall dimensions are increased.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to shorten the span between the front and rear bearings of the rotary shaft, thereby shortening the overall length of the rotary shaft and reducing the overall axial dimension. It is an object of the present invention to provide a spindle device and a machine tool provided with the same.

The above object of the present invention can be achieved by the following constitution.
(1) A main shaft device in which a rotating shaft is rotatably supported by a housing via front and rear bearings, and the rotating shaft is rotationally driven by a built-in motor,
The housing includes an outer cylinder housing to which a stator of the built-in motor is mounted, a front bearing housing in which an outer ring of the front bearing is fitted, and a rear part of the outer cylinder housing. A rear bearing housing, wherein the outer ring of the rear bearing is internally fitted or supported via a bearing sleeve,
The front bearing housing is formed in a stepped shape having an outer peripheral surface having a large-diameter outer peripheral surface and a small-diameter outer peripheral surface,
At least a part of the small-diameter outer peripheral surface of the front bearing housing is arranged inside the end coil of the stator so as to overlap with the end coil of the stator when viewed from the radial direction,
The front bearing includes a motor side bearing closer to the built-in motor, and an anti-motor side bearing away from the built-in motor with respect to the motor side bearing,
The motor-side bearing has a smaller outer diameter than the anti-motor-side bearing, and is fitted into the front-side bearing housing at a position overlapping the small-diameter outer peripheral surface of the front-side bearing housing when viewed from the radial direction ,
In the front bearing, an outer ring spacer is disposed between the outer rings of the motor side bearing and the counter motor side bearing,
The outer ring spacer is in contact with the outer ring of the non-motor side end at the non-motor side end, and at the motor side end is a shoulder formed on the inner peripheral surface of the front bearing housing and the motor side bearing. A main shaft device formed so as to contact an outer ring .
(2) The spindle device according to (1), wherein the motor side bearing has an inner diameter dimension equal to that of the anti-motor side bearing.
(3) The motor-side bearing and the anti-motor-side bearing are angular contact ball bearings that are combined with each other on the back and to which a fixed position preload is applied,
The spindle device according to (1) or (2), wherein the outer ring of the motor side bearing is fitted into the front bearing housing with a fitting clearance.
(4) The motor-side bearing and the anti-motor-side bearing are angular contact ball bearings that are combined with each other on the back and to which a fixed position preload is applied,
The spindle device according to any one of (1) to (3), wherein the outer ring of the motor side bearing is positioned in the axial direction with respect to the front bearing housing with an axial clearance. (5) The outer ring of the rear bearing is fitted into the bearing sleeve, and the bearing sleeve is fitted into the rear bearing housing,
(1) to (4), wherein at least a part of the bearing sleeve is disposed inside the end coil of the stator so as to overlap the end coil of the stator when viewed from the radial direction. The spindle device according to any one of the above.
(6) The outer ring of the rear bearing is fitted into the rear bearing housing,
(1) to (4), wherein at least a part of the rear bearing housing is disposed inside the end coil of the stator so as to overlap the end coil of the stator when viewed from the radial direction. ) The spindle device according to any one of the above.
(7) A machine tool comprising the spindle device according to any one of (1) to (6).
(8) The machine tool according to (7), wherein the spindle device is mounted on a tilt mechanism or a turning mechanism.

  According to the present invention, the front bearing housing is formed in a stepped shape having an outer peripheral surface having a large-diameter outer peripheral surface and a small-diameter outer peripheral surface, and at least a part of the small-diameter outer peripheral surface of the front bearing housing is an end coil of the stator. The front bearing is arranged inside the end coil of the stator so as to overlap when viewed from the radial direction, and the front bearing is a motor-side bearing near the built-in motor, and the anti-motor-side bearing separated from the built-in motor with respect to the motor-side bearing The motor-side bearing has a smaller outer diameter than the non-motor-side bearing, and is fitted into the front bearing housing at a position overlapping the small-diameter outer peripheral surface of the housing when viewed from the radial direction. Therefore, the span between the front and rear bearings can be shortened, contributing to the shortening of the overall length of the rotary shaft, thereby making it possible to reduce the axial dimension of the spindle device and reduce its weight. In addition, by reducing the span between the front and rear bearings of the rotating shaft, the natural frequency of the shaft can be increased, the maximum rotational speed can be increased, and the dynamic rigidity is increased to reduce vibration. It can also be suppressed. In addition, by reducing the inertia of the rotating part, an improvement in rapid acceleration and an energy saving effect by reducing power can be expected. In addition, when mounted on a tilt mechanism or a turning mechanism, the structure of the tilt mechanism or the turning mechanism can be made compact by making the spindle device compact and lightweight.

It is sectional drawing of the main axis | shaft apparatus which concerns on 1st Embodiment of this invention. It is the II section expanded sectional view of FIG. It is the III section expanded sectional view of FIG. It is sectional drawing of the main axis | shaft apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing of the main axis | shaft apparatus which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the conventional main axis | shaft apparatus.

  Hereinafter, a spindle device according to each embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
A spindle device M of the present embodiment shown in FIG. 1 is of a built-in motor type, and is used by being assembled in a machine tool having a tilt mechanism and a turning mechanism. In the spindle device M, the rotary shaft 80 is rotatably supported by the housing H via the front and rear bearings 40 and 60, and the rotary shaft 80 is rotationally driven by the built-in motor 70.

  The housing H includes an outer cylinder housing 10 fixed to a bracket of a machine tool (not shown), a front bearing housing 20 provided at the front portion of the outer cylinder housing 10, and a rear bearing provided at the rear portion of the outer cylinder housing 10. The housing 30 has a bearing sleeve 36 which is disposed inside the rear bearing housing 30 and is movable relative to the rear bearing housing 30 in the axial direction.

  As shown in FIG. 2, the front bearing 40 is disposed between the front bearing housing 20 and the front portion of the rotating shaft 80, and has a motor-side bearing 41 near the built-in motor and a built-in function with respect to the motor-side bearing 41. An anti-motor-side bearing 42 that is separated from the motor 70. The motor-side bearing 41 and the non-motor-side bearing 42 include outer rings 41a and 42a fitted inside the front bearing housing 20, inner rings 41c and 42c fitted around the rotary shaft 80, outer rings 41a and 42a, and inner rings 41c and 42c. Angular contact ball bearings having a plurality of balls 41b and 42b as rolling elements that roll with a contact angle with each other, and are combined on the back via an outer ring spacer 43 and an inner ring spacer 45.

  Further, the outer rings 41a and 42a are described in detail below, but in the axial direction between the front bearing housing 20 and the outer ring holding member 47 fixed to the front bearing housing 20 via the outer ring spacers 43 and 44. Positioned. Further, the inner rings 41 c and 42 c are axially connected to the screw grooves 80 a formed in the rotating shaft 80 by tightening the bearing fixing nut 86 toward the step portion 80 d of the rotating shaft 80 through the inner ring spacers 45 and 46. Thus, a preload is applied to the bearings 41 and 42.

  The bearing fixing nut 86 is disposed between the rear end portion of the front bearing housing 20 and the front end portion of the rotor 72 (rotor sleeve 81 in this embodiment) inside an end coil 73 of the stator 71 described later. The The thread groove 80a into which the bearing fixing nut 86 is screwed is formed on the outer peripheral surface of the rotary shaft 80 into which the front bearing 40 is fitted, and has a larger diameter than the outer peripheral surface into which the rotor sleeve 81 is fitted. Further, the outer peripheral surface of the blade side end portion of the rotary shaft 80 is formed to have a larger diameter than the outer peripheral surface of the rotary shaft 80 with which the front bearing 40 is fitted, and a seal that forms a labyrinth seal structure together with the outer ring spacer 44. Part 80e. Therefore, the rotating shaft 80 is formed such that the outer peripheral surface thereof is reduced in diameter intermittently from the end on the blade side toward the rear.

  Further, as shown in FIG. 3, the rear bearing 60 is also disposed between the bearing sleeve 36 and the rear portion of the rotary shaft 80, and has a motor-side bearing 61 near the built-in motor and a built-in function with respect to the motor-side bearing 61. An anti-motor side bearing 62 that is separated from the motor 70. The motor-side bearing 61 and the non-motor-side bearing 62 include outer rings 61a and 62a fitted inside the bearing sleeve 36, inner rings 61c and 62c fitted around the rotary shaft 80, outer rings 61a and 62a, and inner rings 61c and 62c. Angular contact ball bearings having a plurality of balls 61b and 62b as rolling elements that roll with a contact angle between each other, and are combined on the back via an outer ring spacer 63 and an inner ring spacer 64.

  The outer rings 61 a and 62 a are positioned in the axial direction between the bearing sleeve 36 and the outer ring holding member 65 fixed to the bearing sleeve 36 via the outer ring spacer 63. Further, the inner rings 61 c and 62 c are tightened with a bearing fixing nut 87 in a thread groove 80 b formed in the rotating shaft 80 toward the step portion 80 f of the rotating shaft 80, so that the inner ring spacer 66 and the detected portion of the speed sensor 95 are detected. It is fixed in the axial direction via the ring member 67 for use, and thereby preload is applied to the bearings 61 and 62.

  Returning to FIG. 1, the built-in motor 70 is disposed in a space between the front bearing 40 and the rear bearing 60, and rotates with a stator 71 fixed to the inner periphery of the outer cylinder housing 10 via the cooling cylinder 11. And a rotor 72 shrink-fitted on a rotor sleeve 81 provided on the outer periphery of the shaft 80, and end coils 73 of the stator coil project as substantially annular convex portions at both axial ends of the stator 71. . The rotor sleeve 81 is fastened by shrinkage on the outer periphery of the rotary shaft 80.

  In addition, a cooling groove 10 a is formed on the inner peripheral surface of the outer cylinder housing 10, and the cooling cylinder 11 is fitted therein to constitute a cooling path. Further, the cooling oil groove 20a is formed on the outer peripheral surface of the front bearing housing 20 between the inner peripheral surface of the outer cylinder housing 10 and the outer peripheral surface of the front bearing housing 20 that are fitted to each other. A cooling path is configured.

  A draw bar 93 extending in the axial direction on the inner diameter portion of the rotary shaft 80, a clamping unit 90 provided on the tip side of the draw bar 93 for fixing a tool holder (not shown) to the tapered portion 80 c of the rotary shaft 80, and a draw bar A disc spring 94 is installed between the rotary shaft 80 and the rotary shaft 80 and pulls the clamping unit 90 to the side opposite to the tool. Further, an unclamping unit (not shown) for unclamping the tool holder by compressing the disc spring 94 incorporated in the inner diameter portion of the rotating shaft 80 is attached to the rear side of the rear bearing housing 30.

  Here, as shown in FIG. 2, in the present embodiment, the front bearing housing 20 includes a large-diameter outer peripheral surface 21 whose outer peripheral surface is fitted to the inner peripheral surface of the outer cylinder housing 10, and the large-diameter outer peripheral surface 21. A stepped shape having a small diameter outer peripheral surface 22 is formed. Further, at least a part of the small-diameter outer peripheral surface 22 of the front bearing housing 20 is disposed inside the end coil 73 of the stator 71 so as to overlap the end coil 73 of the stator 71 when viewed from the radial direction.

  Further, in the front bearing 40, the motor side bearing 41 is smaller in size than the anti-motor side bearing 42, specifically, the outer diameter dimension is made smaller than the anti-motor side bearing 42, while the inner diameter dimension is made equal. Things are used.

  The motor-side bearing 41 is fitted into the front-side bearing housing 20 at a position overlapping the small-diameter outer peripheral surface 22 of the front-side bearing housing 20 when viewed from the radial direction. The inner peripheral surface of the front bearing housing 20 includes a small-diameter inner peripheral surface 23 into which the motor-side bearing 41 is fitted, and a large-diameter inner peripheral surface 24 into which the anti-motor-side bearing 42 and outer ring spacers 43 and 44 are fitted. It is formed in a stepped shape. Moreover, in this embodiment, the motor side bearing 41 is arrange | positioned inside the end coil 73 of the stator 71 so that it may overlap with the end coil 73 of the stator 71 seeing from radial direction.

  In the present embodiment, the motor side bearing 41 has the same inner diameter dimension as the anti-motor side bearing 42, but the motor side bearing 41 has an inner diameter dimension larger than that of the anti-motor side bearing 42 as necessary. It may be small.

  The fitting clearance L1 between the outer ring outer diameter of the non-motor side bearing 42 and the inner diameter of the front bearing housing 20 is smaller than the fitting gap L2 between the outer ring outer diameter of the motor side bearing 41 and the inner diameter of the front bearing housing 20 (L1). <L2).

That is, the fitting clearance L1 between the outer diameter of the non-motor side bearing 42 and the inner diameter of the front bearing housing 20 is about 0 μm to 20 μm, more preferably about 0 μm to 10 μm, until the diameter clearance.
On the other hand, the fitting clearance L2 between the outer diameter of the outer ring of the motor side bearing 41 and the inner diameter of the front bearing housing 20 is about 10 μm to 5 mm (= ΔR) up to the clearance of the diameter.

  Increasing the internal clearance between the outer ring outer diameter of the motor-side bearing 41 and the inner diameter of the front bearing housing 20 increases the internal preload caused by centrifugal force and the inner / outer ring temperature difference during high-speed rotation. As a result, the outer ring 41a expands in the clearance. The expansion action of the outer ring 41a acts in the direction in which the preload is released, and has the effect of reducing the increase in preload as the entire front bearing 40. Therefore, seizure of not only the motor side bearing 41 but the entire front side bearing 40 can be prevented.

When the fitting clearance L2 exceeds 5 mm, in the case of a bearing having a bearing inner diameter of φ100 mm or less (standard spindle size), it is impossible to secure a shoulder plane that fixes the outer ring 42a of the non-motor side bearing 42.
On the other hand, if the fitting clearance L2 is smaller than 10 μm, when the outer ring 41a expands, the clearance portion disappears and the effect of reducing the preload becomes insufficient. In practice, the fitting clearance L2 is preferably about 10 to 200 μm.

  In the present embodiment, the outer ring 42a of the non-motor side bearing 42 is fixed to the shoulder 25 of the front bearing housing 20 via the outer ring spacer 43 at one end side (or may be directly contact-fixed). The other end side is fixed by an outer ring holding member 47 via an outer ring spacer 44 and positioned in the axial direction.

On the other hand, one end of the outer ring 41a of the motor side bearing 41 is fixed to the anti-motor side bearing 42 via the outer ring spacer 43 (or may be directly contacted and fixed to the anti-motor side bearing 42), and the other end. Are arranged with an axial clearance (ΔA) between the other shoulder 26 of the front bearing housing 20. The axial clearance ΔA is not particularly limited as long as ΔA> 0.
In this case, the outer ring spacer 43 that contacts the shoulder portion 25 of the front bearing housing 20 has different inner diameter dimensions at the notch portions at both ends, and the motor side end portion is opposed to the outer ring 41a. It has a smaller diameter than the side end.

In particular, in the case of a precision spindle, in order to suppress distortion deformation when tightening the outer rings 41a and 42a, it is necessary to control the accuracy of the pressing allowance to a variation of several μm to several tens of μm, and two different outer diameter dimensions. It is very difficult to fix the bearings 41 and 42 to the shoulder portions 25 and 26 at the same time with an appropriate pressing allowance, respectively.
On the other hand, as in this embodiment, an axial clearance (ΔA) is provided, that is, ΔA> 0 in consideration of machining errors of individual parts of the outer ring single body width of the bearing 41 and the width of the small-diameter inner peripheral surface 23. If the dimensions of the outer ring single body width of the bearing 41 and the width of the small-diameter inner peripheral surface 23 are set so as to be, post-processing and fine adjustment at the time of assembling the spindle are not necessary. The front bearing 40 is fixed in the axial direction after confirming the dimensional difference between the outer ring individual width of the bearing 42 and the outer ring spacers 43 and 44 with respect to the width of the large-diameter inner peripheral surface 24, and then the width of the outer ring holding member 47. It is possible only by adjusting (similar to daily spindle assembly work).
Temporarily, unlike the present invention, when the bearing 41 is simultaneously tightened with the same presser allowance as the front bearing 40, the width of the small-diameter inner peripheral surface 23 (shoulder 25, 26) is required to be adjusted at a level of several μm, and fine adjustment processing is extremely difficult because the processing site is the back of the hole.

Normally, the front side (blade side) bearing 40, which is a fixed side bearing, is loaded with a fixed position preload in order to ensure rigidity and rotational accuracy. Therefore, the outer ring 41a of the motor side bearing 41 is separated from the outer ring spacer 43 by the preload. Close fitting. Therefore, if the non-motor side bearing 42 is fixed as shown in FIG. 2, even if the clearances (ΔR and ΔA) are present, the outer ring 41a of the motor side bearing 41 cannot rotate with the inner ring 41c during rotation. Absent.
Also in this configuration, the radial load applied to the main shaft during machining is loaded by the non-motor-side bearing 42 having a large size and a large load capacity, so there is no problem.

As described above, in the spindle device M having the configuration of the present embodiment, the front bearing housing 20 is formed in a stepped shape having the outer peripheral surface having the large-diameter outer peripheral surface 21 and the small-diameter outer peripheral surface 22. At least a part of the small-diameter outer peripheral surface 22 is disposed inside the end coil 73 of the stator 71 so as to overlap the end coil 73 of the stator 71 when viewed from the radial direction, and the front bearing 40 is a motor closer to the built-in motor. A side bearing 41 and an anti-motor side bearing 42 away from the built-in motor 70 with respect to the motor-side bearing 41. The motor-side bearing 41 has a smaller outer diameter than the anti-motor side bearing 42, and the front side The bearing housing 20 is fitted into the front bearing housing 20 at a position that overlaps with the small-diameter outer peripheral surface 22 of the bearing housing 20 when viewed from the radial direction.
As a result, the motor-side bearing 41 having a small outer diameter can be disposed in the end coil 73, the spindle can be shortened, and the overall length of the rotary shaft 80 can be shortened. The axial dimension can be made compact and light.

  Further, by reducing the span between the front and rear bearings 40, 60 of the rotary shaft 80, the natural frequency of the rotary shaft 80 can be increased, the maximum rotational speed can be increased, and the dynamic rigidity is increased. Thus, vibration can be suppressed to a small value. In addition, by reducing the inertia of the rotating part, an improvement in rapid acceleration and an energy saving effect by reducing power can be expected. Further, when mounted on a tilt mechanism or a turning mechanism, the structure of the tilt mechanism or the turning mechanism can be made compact by reducing the size and weight of the spindle device M.

In the present embodiment, the motor-side bearing 41 has the same inner diameter as the anti-motor-side bearing 42, that is, the load capacity of the anti-motor-side bearing (that is, the blade-side bearing that loads the cutting load) 42. Larger bearings are used. Accordingly, a large cutting load can be applied by the anti-motor side bearing 42, and an extension of the fatigue life of the bearing can be ensured.
Further, the dmn (dm: product of ball pitch circle diameter and n: rotation number (min- ¹ )) value of the motor-side bearing 41 that is easily subjected to a thermal load due to the heat generated by the rotor 72 can be reduced, and is likely to occur during high-speed rotation. The seizure of the motor side bearing 41 can be prevented.

  In the present embodiment, the bearing sleeve 36 includes the cylindrical portion 37 disposed inside the end coil 73 of the stator 71 so as to overlap the end coil 73 of the stator 71 when viewed from the radial direction. The overall length of the shaft 80 can be further shortened. Furthermore, since the motor side bearing 61 of the rear side bearing 60 is disposed inside the end coil 73 of the stator 71, the total length of the rotating shaft 80 can be shortened more effectively.

  As a modification of the present embodiment, the front bearing 40 is a parallel combination bearing, the rear bearing 60 is a parallel combination bearing, and a coil spring or the like is disposed between the two so that a load acts in the axial direction. A main shaft structure (constituting a four-row rear combination bearing with a contact angle of C as the whole main shaft) that constitutes constant pressure preload (axial direction) may be used.

(Second Embodiment)
Next, a spindle device according to a second embodiment of the present invention will be described in detail based on FIG. Note that the same or equivalent parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified.

  In the first embodiment, a combination angular contact ball bearing is used as the rear bearing 60. However, in this embodiment, a single-row cylindrical roller bearing 68 is used as the rear bearing 60 as shown in FIG. ing.

  For this reason, the outer ring 68 a of the cylindrical roller bearing 68 is directly fitted in the rear bearing housing 30 and is fixed in the axial direction by the outer ring restraining member 65 fixed to the rear bearing housing 30. Further, the inner ring 68c of the cylindrical roller bearing 68 is fitted on the rotary shaft 80, and the bearing fixing nut 87 is tightened in the thread groove 80b, whereby the inner ring 68c is axially passed through the inner ring spacer 69 and the detected member ring member 67. Fixed to. A plurality of cylindrical rollers 68b are disposed between the outer ring 68a and the inner ring 68c.

The rear bearing housing 30 has a cylindrical portion 31 disposed inside the end coil 73 of the stator 71 so as to overlap the end coil 73 of the stator 71 when viewed from the radial direction. Therefore, by using the single row cylindrical roller bearing 68, it is possible to further reduce the length as compared with the spindle device of the first embodiment.
Further, as in the present embodiment, at least a part of the cylindrical roller bearing 68 is overlapped with the end coil 73 when viewed from the radial direction, so that the size can be further reduced.
Other configurations and operations are the same as those in the first embodiment.

(Third embodiment)
Next, a spindle device according to a third embodiment of the present invention will be described in detail with reference to FIG. Note that the same or equivalent parts as those in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted or simplified.

In the present embodiment, as shown in FIG. 5, the front bearing 40 has the anti-motor side bearing 42 as two large parallel combination angular ball bearings, and the motor side bearing 41 as two small parallel combination angular ball bearings. Both of them are constituted by a four-row back side angular contact ball bearing with the inner ring spacers 45 and 46 and the outer ring spacers 43 and 44 interposed therebetween.
Further, as the rear bearing 60, a single-row cylindrical roller bearing 68 is used as in the second embodiment.

Also in this embodiment, the outer diameter dimension of the motor side bearing 41 of the four-row rear combination angular ball bearing is reduced, and at least a part of the motor side bearing 41 is in the radial direction with the small diameter outer peripheral surface 22 of the front bearing housing 20. Since it is fitted into the front bearing housing 20 at a position that overlaps when viewed from above, it is possible to extend the life of the spindle by increasing the load capacity of the bearing while maintaining a reduction in size.
Other configurations and operations are the same as those in the first and second embodiments.

  In the present embodiment, the inner ring spacer and the outer ring spacer are arranged between the angular contact ball bearings of the four-row rear combination angular contact ball bearing. You may plan.

  Further, the configuration of the four-row back side angular contact ball bearing of this embodiment may be applied to the front bearing of the first embodiment or the second embodiment, and the rear bearing housing, the bearing sleeve, and the rear bearing are connected to the end coil. You may comprise so that it may overlap with 73.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably.

For example, when two or more rows of angular contact ball bearings are applied to the rear bearing, the same as the front bearing, for example, the outer diameter of the outer ring of the motor-side bearing is larger than the outer diameter of the outer ring of the motor-side bearing. You may make a configuration.
Further, as described in the third embodiment, the front bearing of the present invention may include a plurality of motor-side bearings and may include a plurality of anti-motor-side bearings.

M Spindle device 10 Outer cylinder housing 20 Front bearing housing 21 Large-diameter outer peripheral surface 22 Small-diameter outer peripheral surface 30 Rear-side bearing housing 36 Bearing sleeve 40 Front-side bearing 41 Motor-side bearing 42 Anti-motor-side bearing 60 Rear-side bearing 61 Motor-side bearing 62 Anti-side Motor side bearing 70 Built-in motor 71 Stator 72 Rotor 73 End coil 80 Rotating shaft

Claims (8)

A rotary shaft is rotatably supported by the housing via front and rear bearings, and the rotary shaft is driven to rotate by a built-in motor.
The housing includes an outer cylinder housing to which a stator of the built-in motor is mounted, a front bearing housing in which an outer ring of the front bearing is fitted, and a rear part of the outer cylinder housing. A rear bearing housing, wherein the outer ring of the rear bearing is internally fitted or supported via a bearing sleeve,
The front bearing housing is formed in a stepped shape having an outer peripheral surface having a large-diameter outer peripheral surface and a small-diameter outer peripheral surface,
At least a part of the small-diameter outer peripheral surface of the front bearing housing is arranged inside the end coil of the stator so as to overlap with the end coil of the stator when viewed from the radial direction,
The front bearing includes a motor side bearing closer to the built-in motor, and an anti-motor side bearing away from the built-in motor with respect to the motor side bearing,
The motor-side bearing has a smaller outer diameter than the anti-motor-side bearing, and is fitted into the front-side bearing housing at a position overlapping the small-diameter outer peripheral surface of the front-side bearing housing when viewed from the radial direction ,
In the front bearing, an outer ring spacer is disposed between the outer rings of the motor side bearing and the counter motor side bearing,
The outer ring spacer is in contact with the outer ring of the non-motor side end at the non-motor side end, and at the motor side end is a shoulder formed on the inner peripheral surface of the front bearing housing and the motor side bearing. A main shaft device formed so as to contact an outer ring .   The spindle device according to claim 1, wherein the motor side bearing has an inner diameter equal to that of the anti-motor side bearing. The motor-side bearing and the anti-motor-side bearing are angular contact ball bearings that are combined with each other on the back to be given a fixed position preload,
3. The spindle device according to claim 1, wherein an outer ring of the motor side bearing is fitted into the front bearing housing with a fitting clearance. 4. The motor-side bearing and the anti-motor-side bearing are angular contact ball bearings that are combined with each other on the back to be given a fixed position preload,
4. The spindle device according to claim 1, wherein the outer ring of the motor side bearing is positioned in the axial direction with respect to the front bearing housing with an axial clearance. 5. An outer ring of the rear bearing is fitted into the bearing sleeve, and the bearing sleeve is fitted into the rear bearing housing;
The at least part of the bearing sleeve is arranged inside the end coil of the stator so as to overlap with the end coil of the stator when viewed from the radial direction. 2. The spindle device according to item 1. An outer ring of the rear bearing is fitted into the rear bearing housing,
The at least part of the said rear side bearing housing is arrange | positioned inside the end coil of the said stator so that it may overlap with the end coil of the said stator seeing from radial direction. The spindle device according to any one of the preceding claims.   A machine tool comprising the spindle device according to claim 1.   The machine tool according to claim 7, wherein the spindle device is mounted on a tilt mechanism or a turning mechanism.

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