JPH05141417A - Main shaft device - Google Patents

Abstract

PURPOSE:To improve support rigidity and suppress oscillations of a main shaft by rotatably supporting the main shaft through a roller bearing, inside a bearing case which is slidably supported through a static pressure bearing, and providing a spring which pressurizes a bearing case sliding surface against a housing sliding surface. CONSTITUTION:A main shaft 32 is driven by a built-in motor and is under a cutting work. A support rigidity of the main shaft 32 is improved because a diametral cutting resistance generated in the main shaft 32 is received by a static pressure bearing 12. Diametral oscillations generated on the main shaft 32 can be eliminated by oil resistance generated when it ties to push aside the oil of the static pressure bearing 12 entered between a bearing case 13 and a housing 11. The oscillations can be also eliminated by a frictional force between sliding surfaces 22 and 23 which is generated when the sliding surface of a bearing case 13 is pressurized against the sliding surface 22 of a stopping ring 20 by means of a coil spring 24. The frictional force also prevents the bearing case 13 from moving over a support center of the static pressurie bearing which may caused by the static pressure bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle device for machine tools capable of suppressing vibration of the spindle.

[0002]

2. Description of the Related Art There is a main shaft device of a machine tool in which a main shaft is rotatably supported by a housing through a rolling bearing. This product has a problem that the vibration generated during cutting is large. In order to reduce this vibration, as shown in FIG. 3, the main shaft 3 is rotatably supported by the bearing case 1 via the rolling bearing 2, and the bearing case 1 is slightly moved in the housing 4 in the radial direction of the main shaft 3. There is one in which the silicone oil 6 is sealed by an O-ring 5 provided between the housing 4 and the bearing case 1 so that the silicone oil 6 can be fitted.

[0003]

In the above-mentioned one, although the vibration of the main shaft 3 is damped by the silicone oil 6, there is a problem that the supporting rigidity of the main shaft 3 is low.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention slidably supports a bearing case in a housing via a hydrostatic bearing, and a rolling bearing is provided in the bearing case. The main shaft is rotatably supported around an axis parallel to the sliding direction of the bearing case, and a sliding contact surface is formed on each end surface of the bearing case and the housing so as to relatively slide in the radial direction of the main shaft. A spring for pressing the contact surface against the sliding contact surface of the housing is provided between the bearing case and the housing.

[0005]

With the above construction, the main shaft is supported by the housing via the bearing case and the hydrostatic bearing. This hydrostatic bearing increases the support rigidity of the spindle. When the main shaft vibrates in the radial direction, the oil of the hydrostatic bearing between the bearing case and the housing must be pushed back, and the vibration of the main shaft can be suppressed by the resistance of the oil generated when pushing the oil away. Further, the vibration of the main shaft can be suppressed by the frictional force generated between the sliding surface of the bearing case and the sliding surface of the housing.

[0006]

Embodiment An embodiment of the present invention will be described below with reference to FIG. Reference numeral 10 denotes a main spindle device, and a housing 11 constituting the main spindle device 10 is slidably fitted with a bearing case 13 via a hydrostatic bearing 12. This hydrostatic bearing 12 has a bearing case 13 as shown in FIG.
An annular supply groove 14 formed on the outer periphery of the
4, a throttle groove 15 formed in the sliding direction of the bearing case 13, a pocket 16 formed in the circumferential direction of the bearing case 13 from each throttle groove, and a housing 11.
And an annular discharge groove 17 formed in the. From the supply passage 18 provided in the housing 11 to the supply groove 14,
Pressure oil is supplied to the pocket 16 via the throttle passage 15, and the pressure oil in the supply groove 14 and the throttle passage 15 is supplied to the bearing case 1.
The bearing case 13 is hydrostatically supported by flowing into the pocket 16 through the gap between the housing 3 and the housing 11.
The pressure oil supplied to the pocket 16 is the bearing case 13
And the housing 11 so as to flow to the discharge groove 17. A plurality of throttle grooves 15 and pockets 16 are provided in the circumferential direction of the bearing case 13.

A retaining ring 20 is integrally fixed to the front end of the housing 11, and a retaining ring 21 is provided inside the housing 11.
Are fixed together. The bearing case 1 is provided on the rear surface of the retaining ring 20 and the front end surface of the bearing case 13.
Sliding contact surfaces 22 and 23 are formed so as to relatively slidably contact each other in the radial direction. A plurality of coil springs 24 that press the sliding contact surface 23 of the bearing case 13 against the sliding contact surface 22 of the retaining ring 20 are circumferentially interposed between the retaining ring 21 and the bearing case 13. The spring 24 is not limited to the coil spring, but may be an air spring or a hydraulic spring.

The bearing case 13 holds two angular ball bearings (rolling bearings) 30 and 31, and these angular ball bearings 30 and 31 enable the main shaft 31 to rotate about an axis parallel to the sliding direction of the bearing case 13. Is supported by. A tool (not shown) is detachably attached to the front end of the main shaft 32, and the main shaft 32 is rotationally driven by a built-in motor (not shown).

Next, the operation will be described based on the above configuration. The spindle 32 is rotationally driven by a built-in motor, and a work is cut by a tool. Spindle 3
The radial cutting resistance 2 is received by the hydrostatic bearing 12, so that the support rigidity of the main shaft 32 is improved. The radial vibration of the main shaft 32 can be absorbed by the resistance of the oil that is generated when the oil of the hydrostatic bearing 12 that has entered between the bearing case 13 and the housing 11 is pushed away. Also,
Vibration of the main shaft 32 in the radial direction is suppressed by the friction force generated between the sliding surfaces 22 and 23 by pressing the sliding surface 23 of the bearing case 13 against the sliding surface 22 of the retaining ring 20 by the coil spring 24. be able to. This frictional force does not generate a force that returns the bearing case 13 to the support center of the hydrostatic bearing 12, but suppresses the movement of the bearing case 13 beyond the support center of the hydrostatic bearing by the hydrostatic bearing 12. Have a function.

In the above-described embodiment, an example in which the main shaft 32 is not oscillated has been described, but a recess is formed in the sliding surface 22 of the retaining ring 20, and pressure oil is supplied to this recess to fix the bearing case 13 to the bearing case 13. The bearing case 13 is moved backward by stopping the supply of the pressure oil to the recess, and the coil spring 24
The main shaft 32 may be oscillated by advancing. In this case, when the main shaft 32 is being oscillated, no frictional force is generated between the sliding surfaces 22 and 23.
When the spindle 32 is not oscillating, the spindle 3
The same effect as that without the oscillation function of 2 can be obtained.

[0011]

As described above, according to the present invention, the bearing case is slidably supported in the housing via the hydrostatic bearing, and the main shaft is slidable in the bearing case via the rolling bearing in the sliding direction of the bearing case. The bearings are rotatably supported around parallel axes, and sliding contact surfaces are formed on the end faces of the bearing case and the housing so as to relatively slide in the radial direction of the main shaft. Since the spring that presses against is provided between the bearing case and the housing, the static pressure bearing improves the support rigidity of the main shaft. Further, due to the frictional force acting between the two sliding surfaces and the hydrostatic bearing, the effect of suppressing the vibration of the main shaft can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a spindle device according to the present invention.

[Fig. 2] Development view of bearing surface of hydrostatic bearing

FIG. 3 is a sectional view of a conventional spindle device.

[Explanation of symbols]

 10 Spindle Device 11 Housing 12 Hydrostatic Bearing 13 Bearing Case 20 Stop Ring 21 Stop Ring 22 Sliding Contact Surface 23 Sliding Contact Surface 24 Coil Spring 30 Angular Ball Bearing (Rolling Bearing) 31 Angular Ball Bearing (Rolling Bearing) 32 Spindle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Lee Xuan Quay 1-1 Asahi-cho, Kariya city, Aichi prefecture Toyota Koki Co., Ltd.

Claims (1)

[Claims] 1. A bearing case is slidably supported in a housing via a hydrostatic bearing, and a main shaft is rotatably supported in the bearing case via a rolling bearing about an axis parallel to the sliding direction of the bearing case. Then, a sliding contact surface is formed on each end surface of the bearing case and the housing so as to relatively slide in the radial direction of the main shaft, and a spring for pressing the sliding contact surface of the bearing case against the sliding contact surface of the housing is provided between the bearing case and the housing. A spindle device characterized by being provided between them.