WO2020090277A1

WO2020090277A1 - Spindle device having built-in motor

Info

Publication number: WO2020090277A1
Application number: PCT/JP2019/036849
Authority: WO
Inventors: 恭平松永; 翔一郎小栗
Original assignee: 日本精工株式会社
Priority date: 2018-10-31
Filing date: 2019-09-19
Publication date: 2020-05-07
Also published as: JP7067637B2; TW202017678A; JPWO2020090277A1

Abstract

A spindle device (10) having a built-in motor, wherein a flinger (40) is fixed to one end side of a rotating shaft (11) and a labyrinth seal (44) is formed between the flinger (40) and a housing H. The housing H has: at least one air purge hole (72) that connects to outside the spindle device (10); and an annular groove (71) into which the air purge hole (72) opens and which faces the labyrinth seal (44). As a result, water-resistance performance can be improved, high-temperature air from heat generated by the motor can be prevented from passing through front bearings, and premature damage to bearings can be prevented.

Description

Motor built-in spindle device

The present invention relates to a motor built-in type spindle device.

A spindle device applied to machine tools, etc., is equipped with a cutting tool at the tip of the rotary shaft and rotates at high speed to perform cutting and grinding of the workpiece. Generally, in machining, a large amount of machining liquid is supplied to the machining site for the purpose of lubricating and cooling the cutting tool and the machining site. That is, due to the lubricating effect of the working fluid, it is possible to improve the machinability, suppress the wear of the working edge, and extend the tool life. In addition, the cooling effect of the machining fluid suppresses the thermal expansion of the cutting tool and the workpiece to improve the machining accuracy and prevent the heat welding of the machining site to improve the machining efficiency and the surface texture of the machined surface. Planned.

However, the distance between the spindle device and the machining area may be short, and problems may occur due to the large amount of machining fluid also on the front surface of the spindle device. That is, a large amount of machining fluid supplied may infiltrate into the bearing that supports the rotary shaft, and if the machining fluid infiltrates into the bearing, it may cause lubrication failure or seizure of the bearing. Therefore, various waterproof mechanisms are applied to the spindle device for the purpose of improving the waterproof property of the spindle device and preventing the machining fluid from entering the inside of the bearing.

In particular, in a spindle device used in a machine tool, when the bearing has a dmn value of 400,000 or more (more preferably 500,000 or more), the spindle device rotates integrally with the rotary shaft at the front end (tool side). A non-contact waterproof mechanism called a flinger is often applied. The flinger narrows the clearance between the flinger and the housing to form a so-called labyrinth seal to improve waterproofness. This is because contact seals such as oil seals and V seals generate a large amount of heat from the seal contact portion during high-speed rotation, and the seal members wear and it is difficult to maintain waterproof performance for a long period of time.

In addition, in recent years, in spindles for machine tools, the spindle speed has been increasing in order to improve machining efficiency, and along with that, motor built-in spindle devices have been adopted. For example, Patent Document 1 discloses a spindle device having a motor built-in structure including a flinger.

FIG. 4 is a sectional view showing an example of a conventional spindle device having a motor built-in structure including a flinger. The spindle device 100 has a motor 101 inside the spindle device 100, and drives the motor 101 to rotate a rotary shaft 102. The flinger 105 is fixed to the front end portion of the spindle device 100 so as to rotate integrally with the rotary shaft 102, and forms a labyrinth seal portion 108 between the front housing 106 of the housing 103 and the front outer ring retainer 107. .. As a result, the flinger 105 integrally rotates at a high speed together with the rotary shaft 102, so that the working fluid applied to the flinger 105 is spun outward in the radial direction by centrifugal force along with the above-mentioned labyrinth effect, and the inside of the spindle device 100, in particular, Also, it has an effect of suppressing the infiltration of the working fluid into the inside of the front bearing 109.

Japanese Patent Laid-Open No. 2016-26900

By the way, in the spindle device 100 as shown in FIG. 4, thermal energy is generated in the motor 101 due to various losses that occur when the motor is driven. The heat energy heats the air in the motor chamber 104, in which the motor 101 is housed, into high-temperature air, particularly inside the housing 103. Further, since the spindle device 100 is generally designed so that air, water, dust, etc. do not enter from the outside as much as possible, except for the labyrinth seal portion 108 provided in the front portion of the rotary shaft 102, In many cases, there is no hole or the like that connects the internal space of the spindle device 100 to the outside. Therefore, the internal space of the spindle device 100 (in particular, the motor chamber 104) has a higher pressure than the outside due to the high temperature air.

On the other hand, the vicinity of the flinger 105 is the portion where the peripheral speed becomes the highest during the rotation of the rotary shaft 102, and the air near the flinger 105 is accompanied by the rotation of the flinger 105. According to Bernoulli's theorem, the pressure drops as the velocity of the fluid increases. That is, the air that accompanies the rotation of the flinger 105, which has the highest peripheral speed in the spindle device 100, has the highest speed in the air in the vicinity of the spindle device 100, and thus the pressure thereof is also the lowest.

As described above, the thermal energy generated in the motor 101 raises the pressure of the air in the motor chamber 104, while the rotation of the flinger 105 lowers the pressure of the air in the vicinity of the flinger 105. Causes a phenomenon in which air flows from the motor chamber 104 toward the front surface of the spindle device 100 (direction toward the flinger 105).

Further, in this case, since the front bearing 109 is located in the middle of the space connecting the internal space of the spindle device 100 and the labyrinth seal portion 108, the high temperature air in the motor chamber 104 is rotated by the front bearing while the rotating shaft 102 is rotating. It passes through the gap in 109. The movement of the hot air forcedly moves the lubricant (oil, grease, etc.) of the front bearing 109 from a place suitable for lubrication, and the hot air passes through the inside of the front bearing 109, so that the bearing Since the internal temperature of the bearing 109 rises and the environment in which the bearing 109 is used becomes harsh, there is a risk that the bearing 109 may be damaged early.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to improve the waterproof performance, suppress hot air due to heat generation of a motor from passing through the front bearing, and prevent early damage of the bearing. It is an object of the present invention to provide a spindle device of a motor built-in system capable of preventing the above.

The above object of the present invention is achieved by the following configurations.
(1) The rotation axis,
A front bearing and a rear bearing that rotatably support the rotating shaft with respect to the housing,
A motor having a rotor arranged to be rotatable integrally with the rotary shaft between the front bearing and the rear bearing, and a stator arranged around the rotor.
A motor built-in spindle device comprising:
A flinger fixed to the front end side of the rotating shaft to form a labyrinth seal with the housing,
The motor-built-in type spindle device, wherein the housing has at least one air purge hole communicating with the outside of the spindle device, and an annular groove having the air purge hole opened and facing the labyrinth seal.

According to the motor built-in type spindle device of the present invention, the waterproof performance is improved by the flinger, and one end of the air purge hole is opened in the annular groove facing the labyrinth seal to supply the air from the outside of the spindle device to the labyrinth seal. By doing so, the pressure difference between the labyrinth seal and the motor chamber is eliminated. This prevents hot air in the motor chamber, which is heated by the heat energy generated from the motor, from passing through the front bearing, reducing the temperature rise inside the front bearing, and improving the reliability of the front bearing and, by extension, the spindle device. Can be improved.

1 is a sectional view of a motor built-in type spindle device according to a first embodiment of the present invention. It is sectional drawing of the spindle device of a motor built-in system which concerns on 2nd Embodiment of this invention. It is sectional drawing of the spindle device of a motor built-in system which concerns on 3rd Embodiment of this invention. It is sectional drawing of the conventional spindle device.

Hereinafter, each embodiment of the motor built-in type spindle device according to the present invention will be described in detail with reference to the drawings. In the following description, the side of the rotary shaft on which the tool is attached (tool side) is also referred to as the front side, and the side opposite to the tool side is also referred to as the rear side.

(First embodiment)
FIG. 1 is a cross-sectional view of a motor built-in type spindle device according to a first embodiment of the present invention.
As shown in FIG. 1, in a motor-built-in type spindle device 10 for machine tool spindles (hereinafter also simply referred to as “spindle device 10”), a rotary shaft 11 is arranged on the tool side (left side in FIG. 1). It is rotatably supported by the housing H by two rows of

front bearings

50, 50 and two rows of

rear bearings

60, 60 arranged on the opposite side of the tool (on the right side in FIG. 1). The housing H is mainly composed of a front housing 12, an outer cylinder 13, a rear housing 14, and a rear lid 15 in this order from the tool side, and is fastened and fixed by bolts (not shown).

Each front bearing 50 is an angular ball bearing having an outer ring 51, an inner ring 52, balls 53 as rolling elements arranged with a contact angle, and a cage (not shown), and each rear bearing 60. Is an angular contact ball bearing having an outer ring 61, an inner ring 62, balls 63 as rolling elements arranged with a contact angle, and a cage (not shown). The front bearings 50, 50 (parallel combination) and the rear bearings 60, 60 (parallel combination) are arranged so as to cooperate with each other to form a back surface combination.

The

outer rings

51, 51 of the

front bearings

50, 50 are internally fitted to the front housing 12, and the outer ring spacer 54 is fixed by the front outer ring retainer 16 screwed and fixed to the female screw 27 formed in the front housing 12. It is positioned and fixed in the axial direction with respect to the front housing 12 via. The female screw 27 projects forward from the front end surface 12a of the portion of the front housing 12 into which the

outer races

51, 51 are fitted, and is formed on the inner peripheral surface of the front cylindrical portion 12b facing the flinger 40 described later. ..

The

inner rings

52, 52 of the

front bearings

50, 50 are fitted onto the rotary shaft 11 by the nut 17 fastened to the rotary shaft 11 via a flinger 40 and an inner ring spacer 55 described later. It is positioned and fixed in the axial direction.

The outer rings 61, 61 of the

rear bearings

60, 60 are fitted in the sleeve 18 which is slidably fitted in the rear housing 14 in the axial direction, and are integrally formed in the sleeve 18 by bolts (not shown). The fixed rear outer ring retainer 19 positions and fixes the sleeve 18 in the axial direction via the outer ring spacer 64.

The inner rings 62, 62 of the

rear bearings

60, 60 are fitted onto the rotating shaft 11 by another nut 21, which is fastened to the rotating shaft 11, via the

inner ring spacers

65, 65. It is positioned and fixed in the axial direction. A coil spring 23 is arranged between the rear housing 14 and the rear outer ring retainer 19, and the spring force of the coil spring 23 pushes the rear outer ring retainer 19 together with the sleeve 18 rearward. As a result, preload is applied to the

front bearings

50, 50 and the

rear bearings

60, 60.

The tool side of the rotary shaft 11 is provided with a tool mounting hole and a female screw (not shown) formed in the axial direction through the center of the shaft. The tool mounting hole and the female screw are used to mount a tool (not shown) such as a cutting tool on the rotary shaft 11. Instead of the tool mounting hole and the female screw, a conventionally known draw bar (not shown) may be slidably inserted into the shaft core of the rotary shaft 11. Each of the drawbars has a collet portion for fixing a tool holder (not shown), and is biased in the direction opposite to the tool side by the force of the disc spring.

A rotor 31 that is integrally rotatable with the rotating shaft 11 and a stator 32 that is arranged around the rotor 31 are disposed substantially in the axial center between the

front bearings

50 and 50 and the

rear bearings

60 and 60 of the rotating shaft 11. A motor 30 including is provided. The stator 32 is fixed to the outer cylinder 13 by fitting the cooling jacket 33 shrink-fitted into the stator 32 into the outer cylinder 13 forming the housing H.

An electric wire 35 that is connected to the coil of the stator 32 and supplies electric power to the stator 32 is inserted into the rear housing 14 and the wiring holes 36 a and 36 b provided in the rear lid 15, and is connected to an external power source. The motor 30 supplies electric power to the stator 32 via the electric wire 35 to generate a rotational force in the rotor 31 to rotate the rotating shaft 11. The motor 30 is housed in a motor chamber 34 that is a space surrounded by the front housing 12, the outer cylinder 13, the rear housing 14, and the sleeve 18 around the rotary shaft 11. The rear lid 15 has an opening cover 28 that closes the opening 15a formed at the rear end.

As described above, the flinger 40 is externally fitted to the front end side of the rotary shaft 11 on the tool side (left side in the drawing) of the

front bearings

50, 50, and is fixed to the rotary shaft 11 together with the

inner rings

52, 52 by the nut 17. ing.

The flinger 40 includes a boss portion 41 which is fitted onto the rotary shaft 11, a disc portion 42 which extends radially outward from the boss portion 41, and a ring shape which extends rearward from the outer peripheral portion of the disc portion 42. And an extended annular portion 43.

The inner side surface of the disk portion 42 in the axial direction is arranged to face the front housing 12 and the front end surface of the front outer ring retainer 16 in the axial direction with a slight axial clearance, for example, a clearance of about 0.5 mm. The inner peripheral surface of 43 is radially opposed to the outer peripheral surface of the front housing 12 with a slight radial gap, for example, a gap of about 0.5 mm. As a result, a so-called labyrinth seal 44 is formed between the flinger 40, which is a rotating member, and the front housing 12 and the front outer ring retainer 16, which are non-rotating members.

An annular groove 71 is formed on the outer peripheral surface of the front housing 12 facing the inner peripheral surface of the annular portion 43 of the flinger 40, over the entire circumference. The annular groove 71 is connected to one end of an air purge hole 72 that is formed by bending through the housing H (rear lid 15, rear housing 14, outer cylinder 13, and the housing 12), and the other end of the air purge hole 72 is connected. Is connected to a pump P to supply air to the annular groove 71 from the outside of the spindle device 10. Since the annular groove 71 is a circumferential groove formed on the outer peripheral surface of the front housing 12 over the entire circumference, air is supplied over the entire circumference of the annular groove 71, and the pressure of the labyrinth seal 44 is reduced. Is homogenized in the direction.
The other end of the air purge hole 72 is not connected to the pump P, and even if it is opened, it has the effect of sending air to the opening to the flinger 40, but more preferably the pump P is used. By using it, the above effect can be further promoted.
Further, when the pump P is used, the air pressure and the air flow rate of the pump P can be arbitrarily set, but the air is sent by using the pump P having appropriate specifications according to the maximum rotation speed of the spindle and the size of the flinger 40. Thereby, the internal pressure in the annular groove 71 can be quickly equalized.

Further, in the spindle device 10 of the present embodiment, even when the flinger 40 rotates together with the rotating shaft 11, the pressure of the motor chamber 34 is controlled by supplying the external air from the air purge hole 72 to the annular groove 71. The pressure on the labyrinth seal 44 is balanced. Therefore, the air in the motor chamber 34, which has become hot due to the heat generated by the motor 30, does not easily move to the front of the spindle device 10 through the gap in the front bearing 50. Therefore, the forced movement of the lubricant in the front bearing 50 and the abnormal temperature rise of the bearing portion are suppressed, the early damage of the front bearing 50 can be prevented, and the reliability of the spindle device 10 is improved.

Furthermore, by introducing external air into the labyrinth seal 44 from the air purge hole 72, the pressure of the labyrinth seal 44 becomes higher than that of the outside of the spindle device 10, and an air curtain is formed. It is possible to prevent the machining fluid that falls on the spindle device 10 from entering the

front bearings

50, 50 side. Further, even if the machining fluid or dust enters the labyrinth portion, it can be discharged from the annular portion 43 to the outside by the swinging-off effect by the centrifugal force of the flinger 40, and the machining fluid or dust enters the rotary shaft 11. Can be prevented.

In the present embodiment, the number of air purge holes 72, the phase in the circumferential direction, the cross-sectional area of the opening, and the like can be appropriately designed according to the specifications of the spindle device 10, usage conditions, and the like. Further, a filter member (not shown) such as a silencer may be attached to the pump P in order to prevent foreign matter such as dust and mist from entering.

(Second embodiment)
Next, a second embodiment of the spindle device will be described with reference to FIG. As shown in FIG. 2, the annular groove 73 of the present embodiment is formed in an annular shape on the axial end surface of the front housing 12 facing the disk portion 42 of the flinger 40. Air is supplied to the annular groove 73 from the outside of the spindle device 10A by the air purge hole 72 to which the pump P is connected, as in the spindle device 10 of the first embodiment. Therefore, as in the first embodiment, by supplying external air from the air purge hole 72 to the annular groove 73, the pressure in the motor chamber 34 and the pressure in the labyrinth seal 44 are balanced, and the heat generated by the motor 30 causes a high temperature. It becomes difficult for the air in the motor chamber 34, which has become the above, to move to the front of the spindle device 10 through the gap in the front bearing 50. Further, since the annular groove 73 is also a circumferential groove formed over the entire circumference on the axial end surface of the front housing 12, the pressure of the labyrinth seal 44 is equalized in the circumferential direction.
Other configurations and operations are similar to those of the first embodiment of the present invention.

(Third Embodiment)
Next, a third embodiment of the spindle device will be described with reference to FIG. As shown in FIG. 3, in addition to the configuration of the spindle device 10 of the first embodiment, the spindle device 10B of the present embodiment has a plurality of bypass holes 24 that connect the motor chamber 34 and the labyrinth seal 44 to the front housing. 12 are formed. The air resistance of the bypass hole 24 is smaller than the air resistance of the internal clearance of the front bearing 50 due to the size of the cross-sectional area and the like.

The bypass hole 24 is a straight hole that extends in the front housing 12 in the axial direction, and has a circular cross-sectional area that does not change in the longitudinal direction, and can be easily processed. In addition, in this embodiment, the plurality of bypass holes 24 are formed by the inner peripheral surface of the portion of the front housing 12 into which the outer rings 51, 51 of the

front bearings

50, 50 are fitted, and the female screw 27 with which the front outer ring retainer 16 is screwed. It is formed on the outer diameter side with respect to the outer diameter side and on the inner diameter side with respect to the cooling groove 26 formed on the outer peripheral surface in the radial direction.

By providing the air purge hole 72 connecting the annular groove 71 and the outside of the spindle device 10B and the bypass hole 24 in combination, the rotation of the rotary shaft 11 at the initial stage of rotation and at the initial stage of stoppage, that is, the pressure of the labyrinth seal 44 and the pressure of the motor chamber 34. There is a risk that air will move when the front bearing 50 is not balanced, but since the moving air passes through the bypass hole 24 without passing through the front bearing 50, the temperature rise of the front bearing 50 is suppressed and the front bearing 50 is suppressed. The early damage of 50 can be prevented.
Other configurations and operations are similar to those of the first embodiment of the present invention.

It should be noted that the present invention is not limited to the above-described respective embodiments, and modifications, improvements, etc. can be made as appropriate.
For example, the motor built-in type spindle device of the present invention can be preferably used for a spindle of a grinder.

As described above, the following items are disclosed in this specification.
(1) The rotation axis,
A front bearing and a rear bearing that rotatably support the rotating shaft with respect to the housing,
A motor having a rotor arranged to be rotatable integrally with the rotary shaft between the front bearing and the rear bearing, and a stator arranged around the rotor.
A motor built-in spindle device comprising:
A flinger fixed to the front end side of the rotating shaft to form a labyrinth seal with the housing,
The motor-built-in type spindle device, wherein the housing has at least one air purge hole communicating with the outside of the spindle device, and an annular groove having the air purge hole opened and facing the labyrinth seal.
According to this configuration, the waterproof performance is improved by the flinger, one end of the air purge hole is opened in the annular groove facing the labyrinth seal, and the air is supplied from the outside of the spindle device, so that the motor chamber and the labyrinth seal are separated. Balance the pressure. As a result, the high temperature air in the motor chamber is suppressed from moving in the front bearing due to the pressure difference between the motor chamber and the labyrinth seal, so that the temperature rise of the front bearing is reduced and the front bearing, and by extension, the spindle device. The reliability can be improved.

(2) The motor built-in type spindle device according to (1), wherein the housing includes at least one bypass hole that communicates the motor chamber in which the motor is arranged with the labyrinth seal.
According to this configuration, the high-temperature air in the motor chamber, which has been heated by the thermal energy generated from the motor, is exhausted from the bypass hole that communicates the motor chamber and the labyrinth seal without passing through the front bearing. It is possible to suppress the temperature rise inside the bearing and improve the reliability of the front bearing, and thus the spindle device.

(3) The motor built-in spindle device according to (1) or (2), which is for a machine tool spindle.
According to this structure, it can be suitably used for a machine tool spindle.

(4) The motor built-in type spindle device according to (1) or (2), which is for a spindle of a grinding machine.
According to this structure, it can be suitably used for a spindle of a grinding machine.

The present application is based on the Japanese patent application (Japanese Patent Application No. 2018-205652) filed on October 31, 2018, the contents of which are incorporated by reference into the present application.

10, 10A, 10B Motor built-in type spindle device 11 Rotating shaft 12 Front housing 13 Outer cylinder 14 Rear housing 15 Rear lid 24 Bypass hole 30 Motor 31 Rotor 32 Stator 34 Motor chamber 40 Flinger 41 Boss portion 42 Disc portion 43 Circular ring Part 44 Labyrinth seal 50 Front bearing 51 Outer ring 52 Inner ring 53 Ball 60 Rear bearing 61 Outer ring 62 Inner ring 63

Balls

71, 73 Annular groove 72 Air purge hole H Housing

Claims

A rotation axis,
A front bearing and a rear bearing that rotatably support the rotating shaft with respect to the housing,
A motor having a rotor arranged to be rotatable integrally with the rotary shaft between the front bearing and the rear bearing, and a stator arranged around the rotor.
A motor built-in spindle device comprising:
A flinger fixed to the front end side of the rotating shaft to form a labyrinth seal with the housing,
The motor-built-in type spindle device, wherein the housing has at least one air purge hole communicating with the outside of the spindle device, and an annular groove having the air purge hole opened and facing the labyrinth seal.
The motor built-in spindle device according to claim 1, wherein the housing includes at least one bypass hole that communicates a motor chamber in which the motor is arranged with the labyrinth seal.
The motor built-in spindle device according to claim 1 or 2 for a machine tool spindle.
The motor built-in type spindle device according to claim 1 or 2 for a spindle of a grinding machine.