JP2013022675A - Spindle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle device suppressing influence of thermal expansion and centrifugal force on a bearing to prevent malfunction such as seizing or the like caused by an increase in preload on the bearing in a high speed operating rotary shaft.SOLUTION: One pair of front side inner ring spacers 32 disposed face to face on both side surfaces of an inner ring 52 of a front side bearing 50 rotatably supporting the rotary shaft 12 have flange-shaped protrusions 32b axially protruded from outer peripheral sides and fitting on an outer peripheral surface 52a of a shoulder of the inner ring 52 and are made of a material smaller in thermal expansion coefficient and larger in specific modulus than the inner ring 52.

Description

  The present invention relates to a spindle apparatus, and more particularly to a spindle apparatus that can be applied to a multi-axis control machine tool and can rotate at high speed.

  Conventionally, when fitting members having different linear expansion coefficients, for example, a shaft made of steel, an inner ring made of ceramics having a smaller linear expansion coefficient than the shaft, and an inner peripheral surface fitted with an outer peripheral surface of the inner ring A spacer that is tightly coupled to the inner ring, and a clearance fit between the shaft and the inner ring and pressing the inner ring with the spacer so that no stress is applied to the inner ring due to thermal expansion of the shaft when the temperature rises. An attachment device for a shaft and an annular body that prevents breakage of the shaft is disclosed (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 1-295025

  By the way, in recent years, with the increase in the rotation speed of machine tool spindles, the setting of optimum conditions corresponding to this has been demanded, and bearing and motor design specifications corresponding to high-speed rotation are indispensable. That is, at high speed rotation, the expansion of the bearing inner ring groove due to the centrifugal force increases, and the thermal expansion (particularly, radial thermal expansion) of the inner ring also increases due to the temperature rise of the motor and the main shaft. These two factors overlap. For example, in an angular ball bearing, the internal clearance decreases, and in the case of a structure in which preload is applied to the bearing in advance, the preload of the bearing further increases. In particular, during high-speed rotation, the PV value (P: contact surface pressure, V: sliding speed) of the rolling contact portion between the inner ring groove and ball and between the outer ring groove and ball increases, resulting in poor lubrication such as running out of the lubricating oil film. This may cause a seizure defect.

  The device described in Patent Document 1 is a clearance fit fitting between the shaft and the inner ring, and cannot be applied to a spindle device in which the shaft and the inner ring are fitted with an interference fit of zero or more.

  The present invention has been made in view of the above-described problems, and its purpose is to suppress the influence of thermal expansion and centrifugal force on the bearing in the rotating shaft that rotates at high speed, resulting from an increase in the preload of the bearing. An object of the present invention is to provide a spindle device capable of preventing problems such as seizure.

The above object of the present invention can be achieved by the following constitution.
(1) a rotating shaft;
Front and rear bearings that respectively support the rotary shaft rotatably with respect to the housing;
With
A spindle device in which the rotating shaft and inner rings of the front and rear bearings are fitted with an interference of zero or more,
A pair of inner ring spacers disposed opposite to both side surfaces of at least one inner ring of the front and rear bearings and externally fitted to the rotary shaft;
The inner ring spacer has a hook-shaped protrusion that protrudes in the axial direction from the outer peripheral side and is fitted on the outer peripheral surface of the shoulder of the inner ring, and has a smaller thermal expansion coefficient and a higher specific modulus than the inner ring. A spindle device characterized by being formed from.
(2) The outer peripheral surface of the shoulder portion of the inner ring has an outer peripheral taper portion whose diameter gradually decreases toward the axial end portion,
The inner peripheral surface of the flange-shaped protrusion of the inner ring spacer has an inner peripheral taper portion whose diameter gradually increases toward the axial end,
The spindle device according to (1) above, wherein the outer peripheral taper portion of the inner ring and the inner peripheral taper portion of the flange-shaped protrusion of the inner ring spacer are fitted.
(3) The inner ring spacer is formed in an annular shape and externally fitted to the rotating shaft, and the hook-shaped protrusion formed separately from the main body portion,
And consist of
The spindle apparatus according to (1) or (2), wherein the hook-shaped protrusion is fastened and fixed to the outer peripheral surface of the main body.
(4) The spindle device according to any one of (1) to (3), wherein the hook-shaped protrusion is formed in an annular shape.
(5) The spindle device according to any one of (1) to (3), wherein the hook-shaped protrusion is formed from a plurality of protrusions that are spaced apart in the circumferential direction.
(6) The spindle device according to any one of (1) to (5), wherein the inner ring spacer is made of a carbon fiber composite material.
(7) In addition to the inner ring spacer, the rotating shaft is further formed of a carbon fiber composite material.
(8) The main shaft device includes a motor built-in in which a motor having a rotor fitted to the rotating shaft between the front and rear bearings and a stator arranged around the rotor is arranged. The main spindle apparatus according to any one of (1) to (7), wherein the main spindle apparatus is a type of main spindle apparatus.

  According to the main shaft device described in (1) above, the inner ring spacer is provided so as to be opposed to at least one side surface of the inner ring of the front and rear bearings that rotatably supports the rotating shaft and to be externally fitted to the rotating shaft, The inner ring spacer has a hook-shaped protrusion that protrudes in the axial direction from the outer peripheral side and is fitted on the outer peripheral surface of the shoulder of the inner ring, and is formed of a material having a higher specific elastic modulus and a smaller thermal expansion coefficient than the inner ring. The Therefore, the expansion of the inner ring spacer due to the centrifugal force during high-speed rotation is suppressed, the inner ring is restrained by the hook-shaped protrusion of the inner ring spacer that is fitted around the outer peripheral surface of the inner ring shoulder, and the inner ring is subjected to centrifugal force expansion. Can be suppressed. Furthermore, the amount of radial thermal expansion of the inner ring spacer that accompanies the temperature rise of the spindle device is smaller than the amount of radial thermal expansion of the inner ring, so the inner ring is pressed down by the difference in the amount of thermal expansion to further increase the thermal expansion of the inner ring. Can be pressed in small. As a result, an increase in the internal load of the bearing can be suppressed and occurrence of seizure or the like can be prevented.

  According to the spindle device described in (2) above, the outer peripheral taper portion formed on the outer peripheral surface of the shoulder portion of the inner ring and gradually decreasing in diameter toward the end in the axial direction is formed on the flange-shaped protrusion of the inner ring spacer. Since it fits with the inner peripheral taper portion formed on the inner peripheral surface, it is possible to appropriately adjust the fit of the taper fitting portion by adjusting the axial fastening force between the inner ring and the inner ring spacer. . Further, it is possible to suppress a decrease in the axial fastening force between the inner ring and the inner ring spacer due to the relative thermal expansion difference in the axial direction between the rotating shaft, the inner ring, and the inner ring spacer.

  According to the main shaft device described in (3) above, the inner ring spacer is formed in an annular shape and externally fitted to the rotating shaft, and the hook-shaped protrusion formed separately from the main body portion. Therefore, it can be easily assembled with an interference between the inner ring and the inner ring spacer.

  According to the spindle device described in the above (4), since the hook-shaped protrusion is formed in an annular shape, the inner ring spacer holds down the entire outer circumference of the inner ring, and the centrifugal force expansion of the inner ring is ensured. Radial thermal expansion can be regulated.

  According to the spindle device described in (5) above, the hook-shaped protrusion is formed from a plurality of protrusions that are spaced apart in the circumferential direction, so that the heat dissipation of the inner ring is formed by the gap formed between the adjacent protrusions. Can be increased.

  According to the main shaft device described in (6) above, since the inner ring spacer is formed of a carbon fiber composite material, an inner ring spacer having an appropriate specific modulus and thermal expansion coefficient can be manufactured.

  According to the main shaft device described in (7) above, in addition to the inner ring spacer, the rotating shaft is further formed of a carbon fiber composite material, so that the main shaft device can be reduced in weight and inertial force can be reduced. Increasing the movement acceleration improves production efficiency. In addition, since the motor load is reduced, it is possible to reduce the size of the motor and further reduce the size of the spindle device.

  According to the spindle device described in the above (8), since it is a motor built-in type spindle device in which a motor is disposed between the front and rear bearings, even if heat is generated from the motor, It is possible to prevent the occurrence of seizure or the like by suppressing the influence of the heat of the motor on the front and rear bearings by suppressing the thermal expansion of the inner ring by the difference in the amount of thermal expansion between the inner ring spacer and the inner ring.

It is sectional drawing of the main axis | shaft apparatus which concerns on 1st Embodiment of this invention. (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus shown in FIG. 1, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. (A) is sectional drawing which expands and shows the front bearing vicinity of the main axis | shaft apparatus which concerns on 2nd Embodiment of this invention, (b) is a side view of a front inner ring spacer, (c) is a front view of a front inner ring spacer. It is. (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus which concerns on 3rd Embodiment of this invention, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. It is. (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus which concerns on 4th Embodiment of this invention, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. It is. (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus which concerns on 5th Embodiment of this invention, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. It is. (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus which concerns on 6th Embodiment of this invention, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. It is. (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus which concerns on 7th Embodiment of this invention, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. It is. (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus which concerns on 8th Embodiment of this invention, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. It is. (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus which concerns on 9th Embodiment of this invention, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. It is. FIG. 11 is a view for explaining a method of fastening the front inner ring spacer and the inner ring in the spindle device shown in FIG. 10, (a) is a view before tightening the nut, and (b) is a view after tightening the nut. . (A) is sectional drawing which expands and shows the front side bearing vicinity of the main axis | shaft apparatus which concerns on 10th Embodiment of this invention, (b) is a side view of a front side inner ring spacer, (c) is a front view of a front side inner ring spacer. It is. It is sectional drawing which expands and shows the rear side bearing vicinity of the main axis | shaft apparatus which concerns on 11th Embodiment of this invention.

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

(First embodiment)
As shown in FIG. 1, the spindle device 10 of the first embodiment is a motor built-in system, and has a hollow shape made of a metal material, more specifically, a chromium molybdenum steel material (SCM material) at the center in the axial direction. A rotating shaft 12 is provided, and a draw bar (not shown) is slidably inserted into the shaft core of the rotating shaft 12. The draw bar urges a collet portion for fixing a tool holder (not shown) in the counter tool side direction (right direction in the figure) by the force of the disc spring, and the tool holder is fitted with the tapered surface of the rotary shaft 12. Match. A tool is attached to the tool holder, and as a result, the rotary shaft 12 can clamp the tool at one end (left side in the figure) and attach the tool.

  The rotary shaft 12 is rotatably supported by the housing H by two rows of front bearings 50 and 50 that support the tool side, and two rows of rear bearings 60 and 60 that support the opposite tool side. The housing H is composed of a front cover 40, a front bearing outer ring presser 29, an outer cylinder 19, a rear housing 24, and a rear lid 26 in order from the tool side.

  The rotor 20 is fitted on the outer peripheral surface of the rotary shaft 12 between the front bearings 50 and 50 and the rear bearings 60 and 60 of the rotary shaft 12 by shrink fitting. The stator 22 arranged around the rotor 20 is fixed to the outer cylinder 19 by fitting a cooling jacket 23 shrink-fitted into the stator 22 into the outer cylinder 19 constituting the housing H. Therefore, the rotor 20 and the stator 22 constitute a motor M, and by supplying electric power to the stator 22, a rotational force is generated in the rotor 20 and the rotating shaft 12 is rotated.

  Each front bearing 50 is an angular ball bearing having an outer ring 51, an inner ring 52, a ball 53 as a rolling element arranged with a contact angle, and a cage 54. An angular ball bearing having an outer ring 61, an inner ring 62, a ball 63 as a rolling element, and a cage 64. The front bearings 50 and 50 (parallel combination) and the rear bearings 60 and 60 (parallel combination) are arranged to cooperate with each other to form a back combination.

  The outer rings 51, 51 of the front bearings 50, 50 are fitted into the outer cylinder 19 and are attached to the outer cylinder 19 via the front outer ring spacer 30 by a front bearing outer ring retainer 29 bolted to the outer cylinder 19. It is positioned and fixed in the axial direction. Further, the inner rings 52, 52 of the front bearings 50, 50 are externally fitted to the rotary shaft 12 with zero or more interference, and are rotated with the step portion 13 of the rotary shaft 12 via the plurality of front inner ring spacers 32. It is sandwiched between a nut 31 fastened to the shaft 12 and positioned with respect to the rotating shaft 12.

  The outer rings 61, 61 of the rear bearings 60, 60 are fitted into a sleeve 25 that is slidable in the axial direction inside the rear housing 24, and the rear side is bolted to the sleeve 25. The bearing outer ring retainer 33 is positioned and fixed in the axial direction with respect to the sleeve 25 via the rear outer ring spacer 34. The inner rings 62, 62 of the rear bearings 60, 60 are externally fitted to the rotary shaft 12 with zero or more interference, and the rear inner ring spacer 36 is secured by another nut 35 fastened to the rotary shaft 12. It is positioned and fixed to the rotary shaft 12 via

  Next, the front and rear inner ring spacers 32 and 36 and the inner rings 52 and 62 of the front and rear bearings 50 and 60 will be described in detail. Since the front inner ring spacer 32 and the front bearing 50, and the rear inner ring spacer 36 and the rear bearing 60 have the same configuration, in the following description, the front inner ring spacer 32 and the front bearing 50 are taken as an example. It shall be explained in

  2A is an enlarged cross-sectional view showing the vicinity of the front bearing 50 of the spindle device 10, FIG. 2B is a side view of the front inner ring spacer 32, and FIG. 2C is a front view of the front inner ring spacer 32. Each inner ring 52 has a pair of front inner ring spacers 32 that are fitted on the rotary shaft 12 so as to face each other.

  The front inner ring spacer 32 is an annular main body part 32a and a circle that protrudes in the axial direction from the outer peripheral side of the main body part 32a and is fitted on the outer peripheral surface 52a of the shoulder part of the inner ring 52, and is integrally formed with the main body part 32a. And an annular hook-shaped protrusion 32b. The front inner ring spacer 32 is made of a material having a smaller coefficient of thermal expansion than the inner ring 52 and a large specific elastic modulus, such as a carbon fiber composite material (CFRP).

  The flange-like protrusion 32b of the front inner ring spacer 32 is fitted on the outer peripheral surface 52a of the shoulder of the inner ring 52 with zero or more interference when assembled, and the outer peripheral surface 52a of the shoulder of the inner ring 52 is It is pressed against the inside in the radial direction by the hook-shaped protrusion 32b over the entire circumference. Here, the flange-shaped protrusion 32b and the outer peripheral surface 52a of the shoulder portion of the inner ring 52 are fitted with an interference of zero or more when the temperature rises with the operation of the spindle device 10 and the thermal expansion of both. Since the interference is in the direction of increasing due to the difference in the coefficient, there is no gap between them, and the restraint of the outer peripheral surface 52a of the shoulder portion of the inner ring 52 by the flange-shaped protrusion 32b can be maintained.

  The maximum interference (diameter method) between the flange-like protrusion 32b of the front inner ring spacer 32 and the outer peripheral surface 52a of the shoulder of the inner ring 52 is the shape and meat of the front inner ring spacer 32 (hook-like protrusion 32b). Although it depends on the thickness, considering the ease of incorporation, the thickness is preferably 60 μm or less, more preferably 40 μm or less, and even more preferably 20 μm or less.

  Further, the axial width of the fitting portion between the flange-shaped protrusion 32b and the outer peripheral surface 52a of the shoulder portion of the inner ring 52 is 10% of the axial width of the inner ring 52 in order to maintain the fitting state of both. The above is desirable. In the present embodiment, since the outer diameter of the hook-shaped protrusion 32b is smaller than the inner diameter of the retainer 54, the hook-shaped protrusion 32b and the inner ring are prevented from interfering with the retainer 54. The axial width of the fitting part with the outer peripheral surface 52a of the shoulder part of 52 can be enlarged.

  For the same reason as described above, the fitting of the front inner ring spacer 32 and the rotating shaft 12 and the fitting of the inner ring 52 and the rotating shaft 12 are performed with an interference of zero or more when assembled. It is good. As a result, the fitting state is maintained even when the temperature rises, and creep between the two is prevented, and the fitting state between the flange-like protrusion 32b and the outer peripheral surface 52a of the shoulder portion of the inner ring 52 is firmly maintained. can do.

  The front inner ring spacer 32 made of a carbon fiber composite material has a higher specific elastic modulus, a lower specific gravity, and a smaller coefficient of thermal expansion than the inner ring 52 made of metal, and therefore, centrifugal force expansion due to centrifugal force during operation. And the amount of thermal expansion due to temperature rise is reduced. Therefore, the outer peripheral surface 52a of the shoulder portion of the inner ring 52 is pressed by the hook-shaped protrusion 32b by the difference in expansion amount between the front inner ring spacer 32 and the inner ring 52, and the expansion of the inner ring 52 can be effectively suppressed. This also contributes to maintaining the fit between the rotating shaft 12 and the inner ring 52. The effect of restraining the inner ring 52 by the hook-shaped protrusion 32b is particularly effective in the spindle device 10 that rotates at a high speed such that dmn is 1 million or more.

  In addition, as a carbon fiber composite material, for example, a woven fabric (sheet-like) formed of yarns made of carbon fibers made of PAN (polyacrylonitrile) in parallel, or made of yarns made of carbon fibers. It is manufactured by laminating a plurality of sheets impregnated with a thermosetting resin such as an epoxy resin containing a curing agent, wrapping the sheet around a cored bar and the like, followed by heat curing.

As characteristics of the carbon fiber composite material, for example, when carbon fiber type: HTA of Toho Tenax Co., Ltd. is used, the tensile strength is 2060 MPa, the tensile elastic modulus is 137 GPa, and the specific gravity is 1.55 g / cc. The tensile strength is equivalent or higher, and the specific gravity is about 1/5. Moreover, since the coefficient of thermal expansion can be made −5 to + 5 × 10 ⁻⁶ (K ⁻¹ ) by optimizing the fiber direction and angle, it is ½ to 1 compared to conventional carbon steel. / 10 or so.

  As described above, according to the main shaft device 10 of the present embodiment, the front inner ring between the front inner rings that are disposed opposite to both side surfaces of the inner ring 52 of the front bearing 50 that rotatably supports the rotary shaft 12 and is fitted on the rotary shaft 12. A seat 32 is provided. The front inner ring spacer 32 has a hook-shaped protrusion 32b that protrudes in the axial direction from the outer peripheral side and is fitted on the outer peripheral surface 52a of the shoulder of the inner ring 52, has a higher specific modulus than the inner ring 52, and has a thermal expansion coefficient. Is formed from a small material. Accordingly, since the front inner ring spacer 32 has a small centrifugal force expansion due to the centrifugal force during high-speed rotation, the inner ring 52 is constrained by the hook-shaped protrusion 32b that is fitted on the outer peripheral surface 52a of the shoulder of the inner ring 52, and the inner ring 52 is restrained. The centrifugal force expansion can be suppressed. Furthermore, since the amount of radial thermal expansion of the front inner ring spacer 32 accompanying the temperature rise of the spindle device 10 is smaller than the amount of radial thermal expansion of the inner ring 52, the inner ring 52 is pressed down by the difference in the amount of thermal expansion. The thermal expansion of 52 can be suppressed smaller. As a result, an increase in preload of the bearing 50 and an increase in internal load can be suppressed to prevent the occurrence of seizure.

  Further, since the hook-shaped protrusion 32b of the front inner ring spacer 32 is formed in an annular shape, it can be pressed down by the front inner ring spacer 32 over the entire circumference of the outer peripheral surface 52a of the shoulder of the inner ring 52. Centrifugal force expansion and radial thermal expansion of the inner ring 52 can be restricted.

  Further, since the front inner ring spacer 32 is formed of a carbon fiber composite material, it is possible to manufacture the front inner ring spacer 32 having an appropriate specific elastic modulus and thermal expansion coefficient.

  Further, since the motor built-in type spindle device 10 is provided with the motor M built in between the front and rear bearings 50 and 60, the front inner ring spacer 32 even if heat is generated from the motor M. It is possible to prevent the occurrence of seizure or the like by suppressing the influence of the heat of the motor M on the front bearing 60 by suppressing the thermal expansion of the inner ring 52 small by the difference in thermal expansion amount between the inner ring 52 and the inner ring 52.

  Note that, as described above, the rear bearing 60 and the rear inner ring spacer 36 of the present embodiment have the same configuration as the front bearing 50 and the front inner ring spacer 32, so that the same effect can be obtained. Needless to say.

(Second Embodiment)
Next, the spindle apparatus 10 of 2nd Embodiment is demonstrated with reference to FIG. In the inner ring 52 of the present embodiment, the outer peripheral surfaces 52a of the shoulder portions on both sides have a small diameter to form a small diameter portion 52b. Further, the inner peripheral surface of the flange-shaped protrusion 32b of the front inner ring spacer 32 has a small diameter in accordance with the diameter of the small diameter portion 52b. In other words, the hook-shaped protrusion 32b is formed to be thicker than the hook-shaped protrusion 32b of the first embodiment, and the strength of the hook-shaped protrusion 32b is improved, so that the inner ring 52 is not easily damaged. Can be firmly suppressed. Other configurations and effects are the same as those of the spindle device of the above-described embodiment.

(Third embodiment)
Next, the spindle apparatus 10 of 3rd Embodiment is demonstrated with reference to FIG. The inner ring 52 of the present embodiment is formed to have a wider axial width than the outer ring 51, and accordingly, the hook-like protrusion 32b has a narrower axial width of the main body 32a, and the shaft of the hook-like protrusion 32b. The direction width is formed wide. Therefore, the outer peripheral surface 52a of the shoulder portion of the inner ring 52 can be suppressed by the hook-shaped protrusion 32b with a relatively wide axial width (area) without affecting the structure inside the front bearing 50. Other configurations and effects are the same as those of the spindle device of the above-described embodiment.

(Fourth embodiment)
Next, the spindle apparatus 10 of 4th Embodiment is demonstrated with reference to FIG. The inner ring 52 of the present embodiment is a combination of the inner ring 52 and the front inner ring spacer 32 of the second and third embodiments. The inner ring 52 is formed wide and the outer peripheral surfaces of the shoulder portions on both sides. The small diameter part 52b is formed in 52a. Thereby, while improving the intensity | strength of the collar-shaped protrusion 32b of the front side inner ring | wheel spacer 32, the small diameter part 52b (outer peripheral surface 52a) of the inner ring | wheel 52 can be suppressed firmly with a wide axial direction width | variety. Other configurations and effects are the same as those of the spindle device of the above-described embodiment.

(Fifth embodiment)
Next, the spindle apparatus 10 of 5th Embodiment is demonstrated with reference to FIG. The inner ring 52 of the present embodiment increases the outer diameter of the hook-like protrusion 32b while reducing the axial width of the holder 54 to prevent contact (interference) between the holder 54 and the hook-like protrusion 32b. ing. Thereby, the collar-shaped protrusion 32b can increase the thickness and improve the strength, and can effectively suppress the outer peripheral surface 52a of the shoulder portion of the inner ring 52. Other configurations and effects are the same as those of the spindle device of the above-described embodiment.

(Sixth embodiment)
Next, the spindle apparatus 10 of 6th Embodiment is demonstrated with reference to FIG. The flange-like protrusions 32b of the front inner ring spacer 32 of the present embodiment are composed of a plurality of (three in this embodiment) protrusions 32c that are spaced apart from each other in the circumferential direction and protrude in the axial direction from the main body part 32a. It is formed integrally with the part 32a. As described above, by providing the plurality of protrusions 32c apart from each other in the circumferential direction, the heat of the inner ring 52 can be radiated by the gap formed between the adjacent protrusions 32c.

  Note that the number, the circumferential length, the circumferential interval, and the like of the protrusions 32c can be appropriately set in consideration of the heat dissipation of the inner ring 52, the strength of the hook-shaped protrusions 32b, and the like. Moreover, the hook-shaped protrusion 32b of the present embodiment is applicable to any of the spindle devices described in the above-described embodiments, and in addition to the effects described in the above-described embodiments, further improves the heat dissipation of the inner ring 52. It is possible to make it. Other configurations and effects are the same as those of the spindle device of the above-described embodiment.

(Seventh embodiment)
Next, the spindle apparatus 10 of 7th Embodiment is demonstrated with reference to FIG. The front inner ring spacer 32 of the present embodiment includes a main body portion 32a formed in an annular shape and a hook-shaped protrusion 32b formed separately from the main body portion 32a. Similar to the sixth embodiment, the hook-shaped protrusion 32b includes three protrusions 32c that are spaced apart from each other in the circumferential direction, and each protrusion 32c is fastened and fixed to the outer peripheral surface of the main body 32a by a screw 37. 52 is fitted on the outer peripheral surface 52a of the shoulder portion with zero or more interference.

  As described above, in this embodiment, the hook-shaped protrusion 32b of the front inner ring spacer 32 and the outer peripheral surface 52a of the shoulder of the inner ring 52 are fitted with zero or more interference so as to be hooked. Since the plurality of protrusions 32c constituting the protrusions 32b are configured to be tightened by the screws 37, the assembling property can be improved. Furthermore, since a gap is formed between the protrusions 32c adjacent in the circumferential direction, the heat of the inner ring 52 can be radiated from this gap.

  The spindle device of the present embodiment can be applied to any of the spindle devices described in the above-described embodiments, and other configurations and effects are the same as those of the spindle device of the above-described embodiments.

(Eighth embodiment)
Next, the spindle apparatus 10 of 8th Embodiment is demonstrated with reference to FIG. The spindle device 10 of this embodiment includes an inner ring 52 and a front inner ring spacer 32 having the same shape as that of the sixth embodiment (see FIG. 7), and the rotating shaft 12A is made of the same material as the front inner ring spacer 32. It is formed of a fiber composite material.

  Thus, in addition to the front inner ring spacer 32, the rotary shaft 12A is also made of a carbon fiber composite material, whereby the spindle device 10 can be reduced in weight and the natural frequency (resonance frequency) can be increased. At the same time, since the acceleration / deceleration inertia is reduced, the acceleration / deceleration time of the spindle device 10 can be reduced, and as a result, a large amount of actual machining time is secured to improve productivity. Furthermore, the load on the motor is reduced. Therefore, when the acceleration / deceleration time is the same, a low torque motor can be employed, and the spindle device 10 can be downsized.

  In addition, when the rotating shaft 12 and the front inner ring spacer 32 are formed of the same material (carbon fiber composite material), the centrifugal force expansion amount of the rotating shaft 12 becomes the centrifugal force expansion amount of the front inner ring spacer 32 due to the difference in thickness between the two. Since there is a tendency to become smaller, it is necessary to consider the difference in the expansion amount due to the centrifugal force, and to appropriately prevent the clearance between the rotating shaft 12 and the front inner ring spacer 32 from occurring even at the maximum rotation. Must be selected. If a clearance is generated between the rotating shaft 12 and the front inner ring spacer 32, the centrifugal force expansion and thermal expansion of the inner ring 52 may not be suppressed by the front inner ring spacer 32.

  The spindle device of the present embodiment can be applied to any of the spindle devices described in the above-described embodiments, and other configurations and effects are the same as those of the spindle device of the above-described embodiments.

(Ninth embodiment)
FIG. 10 is an enlarged sectional view showing the vicinity of the front bearing 50 of the spindle device 10 according to the ninth embodiment. The inner ring 52 of the present embodiment is formed with an outer peripheral tapered portion 52c whose diameter gradually decreases toward the axial end on the outer peripheral surface 52a of the shoulder, and becomes thinner toward the axial end. . Further, the front inner ring spacer 32 is formed with an inner peripheral taper portion 32d having a diameter gradually increasing toward the axial end portion on the inner peripheral surface of the flange-shaped protrusion 32b, and toward the axial end portion. It is thick. And the inner ring | wheel 52 is restrained from radial direction outer side by the outer peripheral taper part 52c of the inner ring | wheel 52 and the inner peripheral taper part 32d of the collar-shaped protrusion 32b of the front side inner ring | wheel spacer 32 fitting.

  Below, with reference to FIG. 11, the fastening method of the inner ring | wheel 52 and the front side inner ring | wheel spacer 32 in this embodiment is explained in full detail. First, as shown in FIG. 11 (a), the inner ring 52 and the front inner ring spacer 32 are in a state where the outer peripheral tapered part 52c of the inner ring 52 and the inner peripheral tapered part 32d of the hook-shaped protrusion 32b are in contact with each other. Are arranged opposite to each other via an axial gap ΔL (> 0). Next, the inner ring 52 is positioned in the axial direction by tightening the nut 31 (see FIG. 10) brought into contact with the front inner ring spacer 32 toward the rear in the axial direction until the axial clearance ΔL becomes zero, The outer peripheral taper portion 52c of the inner ring 52 and the inner peripheral taper portion 32d of the flange-shaped protrusion 32b are fitted to each other (see FIG. 11B).

  As described above, according to the spindle device 10 of the present embodiment, by appropriately setting the value of the axial clearance ΔL before the nut 31 is tightened (the state shown in FIG. 11A), the inner ring 52 and the front inner ring are separated. By adjusting the fastening force in the axial direction of the seat 32, it is possible to appropriately adjust the fit between the outer peripheral tapered portion 52c and the inner peripheral tapered portion 32d. Further, since the outer peripheral tapered portion 52c of the inner ring 52 and the inner peripheral tapered portion 32d of the flange-shaped protrusion 32b of the front inner ring spacer 32 are fitted, the shaft of the rotary shaft 12, the inner ring 52, and the front inner ring spacer 32 is provided. It is possible to suppress a reduction in the axial fastening force between the inner ring 52 and the front inner ring spacer 32 due to the relative thermal expansion difference in the direction. Other configurations and effects are the same as those of the spindle device of the above-described embodiment, and the spindle device 10 of the present embodiment can be applied to any of the spindle devices 10 of the above-described embodiment.

  In addition, as a structure for not reducing the axial direction fastening force of the inner ring 52 and the front side inner ring spacer 32, it is not limited to the structure of this embodiment, For example, between the inner ring 52, the nut 31, and the front side inner ring spacer 32. A configuration in which an elastic member such as a disc spring (not shown) is disposed on the front, a configuration in which the tightening force of the nut 31 is increased, and the front inner ring spacer 32 made of a carbon fiber composite material is elastically deformed in advance is used. May be.

(10th Embodiment)
In the spindle device 10 of the above-described embodiment, the configuration in which the two rows of angular ball bearings (front bearings) 50 are combined in parallel has been described. However, like the spindle device 10 of the tenth embodiment shown in FIG. Further, the back surface may be combined. Similarly, the rear bearing 60 may also be constituted by an angular ball bearing 50 combined on the back surface.

(Eleventh embodiment)
Furthermore, the rear bearing 60 may be a cylindrical roller bearing as in the spindle device of the eleventh embodiment shown in FIG. In this case, on both side surfaces of the rear bearing 60, a rear inner ring spacer 36 composed of a main body portion 36a and a hook-like protrusion 36b is disposed to face the inner ring by the hook-like protrusion 36b of the rear inner ring spacer 36. The outer peripheral surface 62a of the shoulder portion of 62 is suppressed, and the expansion of the inner ring 62 is suppressed.

  In addition, this invention is not limited to each embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. For example, the front and rear bearings 50 and 60 have been described as angular ball bearings. However, the present invention is not limited to this, and the type, number of rows, arrangement, arrangement, etc. of the bearings, such as combinations of ball bearings and cylindrical roller bearings, are arbitrary. Can be set to

  Further, in the above-described embodiment, the front bearing 50 and the front inner ring spacer 32 and the rear bearing 60 and the rear inner ring spacer 36 have the same configuration, but both have the same configuration. There is no need, and a pair of inner ring spacers 32, 36 having hook-shaped protrusions 32 b, 36 b on both side surfaces of at least one inner ring 52, 62 of the front and rear bearings 50, 60 may be arranged to face each other.

10 Spindle device 12 Rotating shaft 32 Front inner ring spacer (Inner ring spacer)
32a Body portion 32b Hook-like projection 32d Inner circumferential taper portion 32c Projection 36 Rear inner ring spacer (inner ring spacer)
36a Body portion 36b Hook-like projection 50 Front bearing 52 Inner ring 52a Outer peripheral surface 52c Outer taper portion 60 Rear bearing 62 Inner ring 63 Ball 64 Cage H Housing (housing)
ΔL Axial clearance (Axial clearance)

Claims (8)

A rotation axis;
Front and rear bearings that respectively support the rotary shaft rotatably with respect to the housing;
With
A spindle device in which the rotating shaft and inner rings of the front and rear bearings are fitted with an interference of zero or more,
A pair of inner ring spacers disposed opposite to both side surfaces of at least one inner ring of the front and rear bearings and externally fitted to the rotary shaft;
The inner ring spacer has a hook-like protrusion that protrudes in the axial direction from the outer peripheral side and is fitted onto the shoulder of the outer peripheral surface of the inner ring, and has a smaller thermal expansion coefficient and a higher specific elastic modulus than the inner ring. A spindle device characterized by being formed from. The outer peripheral surface of the shoulder portion of the inner ring has an outer peripheral taper portion whose diameter gradually decreases toward the axial end.
The inner peripheral surface of the flange-shaped protrusion of the inner ring spacer has an inner peripheral taper portion whose diameter gradually increases toward the axial end,
2. The spindle device according to claim 1, wherein the outer peripheral taper portion of the inner ring and the inner peripheral taper portion of the flange-shaped protrusion of the inner ring spacer are fitted. The inner ring spacer is formed in an annular shape and externally fitted to the rotating shaft, and the hook-shaped protrusion formed separately from the main body portion,
And consist of
The spindle apparatus according to claim 1, wherein the hook-shaped protrusion is fastened and fixed to an outer peripheral surface of the main body.   The spindle apparatus according to claim 1, wherein the hook-shaped protrusion is formed in an annular shape.   The spindle apparatus according to any one of claims 1 to 3, wherein the hook-shaped protrusion is formed from a plurality of protrusions that are spaced apart in the circumferential direction.   The main shaft device according to any one of claims 1 to 5, wherein the inner ring spacer is formed of a carbon fiber composite material.   The spindle apparatus according to claim 6, wherein, in addition to the inner ring spacer, the rotation shaft is made of a carbon fiber composite material.   The main shaft device is a motor built-in main shaft in which a motor having a rotor fitted to the rotary shaft between the front and rear bearings and a stator arranged around the rotor is disposed. The main shaft device according to claim 1, wherein the main shaft device is a device.

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