JP4207242B2 - Machine tool spindle equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spindle device of a machine tool including a bearing that supports a rotating shaft, and more particularly to a technique for cooling the bearing.
[0002]
[Prior art]
Generally, heat generated in the rotor and bearings of the motor is dissipated to the outside air through the housing. However, in a built-in motor type spindle device, the bearing that supports the opposite end portion of the spindle is normally slidably held in the axial direction so as to allow the spindle to extend. It may be difficult to escape and the bearing may overheat and be damaged. Further, in this type of main shaft device, since the bearing is provided in a closed space in the housing in order to protect the bearing from cutting fluid and chips, it is difficult to directly cool the bearing by outside air. Therefore, conventionally, in Japanese Patent No. 2521566, a tool tension bar is inserted into the center hole of the main shaft, an air passage, a suction fan, and a discharge fan are provided in the tool tension bar, and a screw for air propulsion is engraved in the center hole of the main shaft. A technique has been proposed in which a screw and a fan are rotated integrally with a main shaft, cooling air is allowed to flow over the entire length of the main shaft, thermal displacement of the main shaft is suppressed, and the bearing is indirectly cooled.
[0003]
[Problems to be solved by the invention]
However, according to this main shaft device, it is necessary to provide a plurality of fans and screws to flow cooling air in the main shaft, and it is necessary to connect the air passage to an external air supply source. There was a problem of increasing complexity. In particular, in the case of an electric motor or a small spindle device in which the rotating shaft is relatively short and thermal displacement is not considered as a problem, such a complicated cooling mechanism is unsuitable, and rather emphasizes a bearing that supports the opposite end of the rotating shaft. A cooling mechanism was desired.
[0004]
Accordingly, an object of the present invention is to cool a bearing provided in a closed space in a housing, in particular, a bearing that supports the end portion on the opposite side of the rotating shaft with a simple mechanism so that the bearing is not damaged by overheating. It is to provide a spindle device of machine tools that can be prevented.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, a bearing device for a machine tool according to the present invention includes a stator and a rotor disposed in a closed space in a housing, the stator fixed to the housing, the rotor fixed to the main shaft, The load side end on the front side in the axial direction is supported on the housing by the first bearing, the second bearing is provided on the end on the non -load side on the rear side in the axial direction of the main shaft , and the second bearing is held in the housing by the bearing holding member. The bearing holding member is provided with an opening for communicating the first space ahead of the second bearing and the second space behind the second bearing , while the main shaft is opened by the first space and the second space before and after the bearing holding member. And forming a fan member by forming a plurality of radial grooves or holes in a balance ring for adjusting the rotational balance fixed to the main shaft in the first space in front of the second bearing. Radial member A groove or hole is fixed to the main shaft at a position corresponding to the first space side opening of the air passage, in the housing by the rotation of the fan member air bearing holding member through the opening of the air passage and the bearing holding member of the main shaft It is comprised so that it may circulate between 1st space before and behind, and 2nd space (Claim 1).
[0006]
In order to reduce the temperature of the circulating air, it is preferable to provide a heat exchange fin in the housing .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is embodied in a built-in motor type spindle device installed in a machining center will be described with reference to the drawings. As shown in FIG. 1, the housing 1 of the spindle device is configured in a small size having a front plate 3 and a rear cap 4 assembled to a main body 2 and having a total length of, for example, about 400 mm. A large number of radiating fins 5 are provided on the outer periphery of the main body 2 to efficiently release the heat of the built-in motor into the atmosphere, and heat exchange fins 6a and 6b are provided on the inner and outer surfaces of the rear cap 4. Is provided. A terminal box 7 is attached to the rear cap 4.
[0010]
A stator 8 and a rotor 9 constituting a built-in motor are disposed in a closed space in the housing 1, the stator 8 is fixed to the inner periphery of the main body 2, and the rotor 9 is an intermediate portion of a main shaft 10 exemplified as a rotation shaft. It is fixed to. The main shaft 10 is formed with substantially the same length as the housing 1, and a pair of first bearings 12 are fixed to the load side end portion 11 with nuts 13, and a pair of second bearings 15 are provided to the non-load side end portion 14. It is fixed with a nut 17 via a labyrinth 24 and a spacer 16.
[0011]
The front plate 3 is provided with a recess 19 in which the first bearing 12 is fitted, and a retainer 20 that holds the first bearing 12 in a fixed position of the housing 1. A holder 22 as a bearing holding member for holding the second bearing 15 is assembled to the mounting wall portion 21 formed at the rear end of the main body portion 2, and the holder 22 and the mounting wall portion 21 are used for the second bearing 15 side. The closed space is divided into a first space 30 and a second space 31.
[0012]
The second bearing 15 is fitted in the recess 23 of the holder 22 so as to be slidable in the axial direction so as to allow the extension of the main shaft 10. A speed detector 25 for detecting the rotational speed of the main shaft 10 is attached to the holder 22, and a detection ring 26 is fixed to the spacer 16 on the main shaft 10 side so as to face the detector 25 in a non-contact manner.
[0013]
An air passage 28 is formed in the axial direction in the opposite end portion 14 of the main shaft 10, and its front end opens in a first space 30 in front of the second bearing 15 (rotor 9 side) via a plurality of radial holes 29. The rear end opens in the second space 31 behind the second bearing 15. The mounting wall 21 of the main body 2 is provided with a notch 32 that allows the spaces 30 and 31 to communicate with each other. The holder 22 may be attached to the housing 1 via a plurality of arms, and the two spaces 30 and 31 may be communicated with each other through an opening between the arms.
[0014]
In front of the second bearing 15, the main shaft 10 is provided with a balance ring 34 for adjusting the rotational balance. A plurality of radial grooves 35 as shown in FIG. 2 are formed on the end surface of the balance ring 34 on the second bearing 15 side, and the balance ring 34 has a function as a fan member. The balance ring 34 is fixed to the main shaft 10 by means such as shrink fitting at a position where the radial groove 35 corresponds to the radial hole 29 of the air passage 28, and the air in the housing 1 is removed by the rotation of the rotor 9. The first space 30 and the second space 31 are circulated through the passage 28 and the notch 32. Instead of the radial groove 35, a radial hole may be provided in the balance ring 34.
[0015]
That is, during operation of the main shaft device, the rotor 9, the main shaft 10 and the balance ring 34 are rotated together, and a circulating air flow as shown by arrows in FIG. The anti-load side end 14 of the main shaft 10 and the second bearing 15 that supports the main shaft 10 are cooled by the air flowing through the air passage 28 of the main shaft 10, and the temperature-increased air passes through the radial holes 29 and passes through the first space 30. The air in the first space 30 is sent to the second space 31 through the notch 32, where it is rapidly cooled by the heat exchange fins 6a and 6b of the rear cap 4, and the cooled air is air. The second bearing 15 is cooled again by the cooling air sucked into the passage 28.
[0016]
According to the spindle device of this embodiment, since the fan member that forms the circulating air flow is configured using the balance ring 34, the single ring 34 has two functions to reduce the number of parts. Can do. Further, since the radial groove 35 of the balance ring 34 and the radial hole 29 of the air passage 28 are provided at the same location on the main shaft 10, the air in the air passage 28 is strongly sucked into the first space 30. Can be sent. Therefore, the air in the housing 1 can be efficiently circulated by the single balance ring 34, and the second bearing 15 is intensively cooled by a simple mechanism that does not require an external air supply source. It is possible to reliably prevent damage due to overheating.
[0017]
FIG. 3 shows another embodiment of the present invention. In this spindle apparatus, a single second bearing 15 is held in the housing 1 by a flexible holder 37 as a bearing holding member. The flexible holder 37 includes a thick portion 38 that is fixed to the housing 1, a holding portion 40 that includes a concave portion 39 into which the second bearing 15 is fitted, and a thin plate portion that connects the holding portion 40 to the thick portion 38. 41, the thin plate portion 41 is assembled in an elastically deformed state, and the elastic restoring force is used to apply a preload in the direction of the main shaft axis to the second bearing 15. ing. The thin plate portion 41 is formed with a communication hole 42 that allows the first space 30 and the second space 31 to communicate with each other.
[0018]
In the spindle device of this embodiment, since the thin plate portion 41 is provided in the flexible holder 37, the heat of the second bearing 15 is unlikely to escape to the housing 1 side. However, since the second bearing 15 is efficiently cooled by the circulating air flow accompanying the rotation of the balance ring 34 as in the above-described embodiment, the second bearing 15 can be reliably prevented from being damaged due to overheating. In FIG. 3, 43 is a retainer that holds the second bearing 15 in the recess 39, and 44 is an attachment member for the speed detector 25.
[0019]
In addition, it is also possible to change and implement suitably the shape and structure of each part in the range which does not deviate from the meaning of this invention.
[0020]
【The invention's effect】
As described above in detail, according to the present invention, a bearing provided in a closed space in the housing, particularly a bearing that supports a non-load-side end portion of a rotating shaft such as a main shaft is intensively cooled by a simple mechanism. Thus, it is possible to prevent the bearing from being damaged due to overheating.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a spindle device showing an embodiment of the present invention.
FIG. 2 is a perspective view showing a balance ring of the apparatus.
FIG. 3 is a cross-sectional view of a main part of a spindle device showing another embodiment of the present invention.
[Explanation of symbols]
1 ·· Housing, 6a, 6b · · Heat exchange fins, 8 · · Stator, 9 · · Rotor, 10 · · Spindle, 11 · · Load side end, 12 · · 1st bearing, 14 · · Anti-load Side end, 15 ... second bearing, 22 ... holder, 28 ... air passage, 29 ... radial hole, 30 ... first space, 31 ... second space, 32 ... notch, 34 ... -Balance ring, 35 ... Radial hole, 37 ... Flexible holder.

Claims (2)

A stator and a rotor are disposed in a closed space in the housing, the stator is fixed to the housing, the rotor is fixed to the main shaft, and the load side end portion on the axial front side of the main shaft is supported on the housing by the first bearing, A second bearing is provided at the opposite end of the main shaft in the axial direction , and the second bearing is held in the housing by a bearing holding member . The bearing holding member has a first space in front of the second bearing and a rear first shaft . While providing an opening for communicating with two spaces,
More to the main shaft, the first space and so as to form an air passage opening at the second space, balancing ring for adjusting the rotational balance fixed to the main shaft in a first space forward of the second bearing of the front and rear of the bearing holding member The fan member is configured by forming a radial groove or hole of the fan, and the fan member is fixed to the main shaft at a position where the radial groove or hole corresponds to the first space side opening of the air passage.
The spindle device of the machine tool configured to circulate the air in the housing through the air passage of the spindle and the opening of the bearing holding member between the first space and the second space before and after the bearing holding member by the rotation of the fan member. . The spindle device of machine tool according to claim 1, wherein the fins of the heat exchanger is provided in the housing.

Images