JP2525841Y2 - Drive structure of air spindle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a driving structure of an air spindle for performing high-precision rotation with a low load, such as a rotary table used for high-precision measurement of an aspherical lens.

[Conventional technology]

2. Description of the Related Art An air spindle having a spindle rotatably supported by a static pressure fluid is widely used in the field of precision measuring devices and the like for performing low-load, high-precision rotation.

In this air spindle, as a method of driving the spindle, a direct drive system in which a motor shaft is directly mounted on a spindle, or a belt drive system in which a belt is driven by passing a belt between a pulley mounted on a spindle and a pulley mounted on a motor shaft. there were.

[Problems of the prior art]

However, in the drive structure of the direct drive system described above, vibration, heat generation, run-out, and the like of the motor are directly transmitted to the spindle, and the spindle swings in the radial direction and the thrust direction, so that high rotational accuracy cannot be obtained.

Further, even in the case of the belt drive system, the adverse effect of the motor is easily transmitted via a belt, a pulley, and the like, and the rotation accuracy of the spindle cannot be increased.

As described above, the conventional drive structure has a problem that the high rotational accuracy inherent in the air spindle cannot be obtained.

[Means for solving the problem]

In view of the above, the present invention relates to an air spindle,
A pulley is provided at a position concentric with the spindle, a rod is attached to one of the pulley and the spindle, and two rollers are attached to the other in parallel with each other so that the rotation axis is in the radial direction of the pulley. The spindle and the pulley are connected by sandwiching the rod between the rollers, and the pulley is driven by a motor.

[Action]

According to the air spindle drive structure of the present invention, the pulley driven by the motor and the spindle are not fixed, but are connected by a rod and two rollers sandwiching the rod, and the rod is thrust between the two rollers. It is movable in the direction (rotation axis direction). Moreover, the two rollers are mounted in parallel with each other such that their rotation axes are in the radial direction (radial direction) of the pulley, and the rod held between the rollers is movable in the radial direction.
The vibrations of the motor and the like are absorbed in this portion, and can be hardly transmitted to the spindle.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The air spindle device shown in FIG. 1 supports a spindle 1 made of ceramics such as alumina by a bearing 2 also made of ceramics, and supplies a fluid such as air supplied from a tube T to a gap between the spindle 1 and the bearing 2. The spindle 1 is ejected and rotatably supported by the static pressure fluid. The bearing 2 is supported by a mounting plate 3, which is supported on a base 5 via an intermediate plate 4. The spindle 1 is connected to an encoder 12 attached to the intermediate plate 4 by a coupling 11 to enable high-resolution rotation.

Further, a pulley 6 is rotatably supported on the intermediate plate 4 at a lower concentric position on the spindle 1, and the pulley 6 is connected to driving pulleys 9 and 10 disposed on both sides thereof by a belt 7. A rotational driving force is applied to the pulley 6 by a motor 8 directly connected to the pulley 9.

2, a rod 13 is attached to the lower surface of the spindle 1, while a rod 13 is attached to the upper surface of the pulley 6.
The rollers 14 and 15 are arranged in parallel with each other such that their rotation axes are in the radial direction of the pulley 6, and are rotatably mounted by bearings or the like, and one roller 14 is fixed on the pulley 6, The other roller 15 is a spring
It is elastically attached by an elastic material such as 16. The spindle 1 and the pulley 6 are connected by sandwiching the rod 13 between these rollers 14 and 15.

Next, the operation of the drive structure shown in FIG. 1 will be described. First, when the driving pulley 9 is rotated by the motor 8,
When the pulley 6 is rotated by the belt 7 and is driven in the direction of the arrow as shown in FIG.
By 13, the driving force is transmitted to the spindle 1, and the spindle 1 can be rotated. At this time, since the roller 15 is elastically attached, the rod 13 is always pressed against the fixed roller 14, so that the rotational positioning can be accurately performed.

Since the two rollers 14 and 15 are mounted in parallel with each other so that their rotation axes are in the radial direction of the pulley, the rod 13 held between the rollers 14 and 5 is moved in the thrust direction and the radial direction of the spindle 1. In this state, the vibration of the motor 8 transmitted to the pulley 6 is absorbed by this portion, and the vibration in the thrust direction and the radial direction is not transmitted to the spindle 1. Further, since the rollers 14, 15 and the rod 13 are in point contact, the heat of the motor 8, the belt 7, the pulley 6, and the like is not easily transmitted to the spindle 1, and the influence of thermal expansion can be reduced.

In the above embodiment, the rod 13 is attached to the spindle 1 and the rollers 14 and 15 are attached to the pulley 6. However, the rollers 14 and 15 may be attached to the spindle 1 and the rod 13 may be attached to the pulley 6. Further, a plurality of rods 13 and rollers 14, 15 may be provided at symmetrical positions.

Further, the rod 13 and the rollers 14 and 15 may be made of a metal material, but those made of ceramics such as alumina are excellent in terms of wear resistance and high accuracy.

Next, an air spindle device having the drive device of the present invention shown in FIG. 1 was prototyped, and an experiment for measuring the rotational accuracy was performed together with a conventional direct drive air spindle device as a comparative example. The measurement method is as follows. The surface of a true sphere arranged at the center of rotation of the spindle 1, which is a rotating body, is measured with a non-contact type displacement meter, and a Lissajous circle is drawn. Was checked.

As a result, the displacement of the Lissajous circle of the comparative example is shown in FIG. 3 and the displacement of the Lissajous circle of the present invention is shown in FIG. 4, and the air spindle device having the drive structure of the present invention has excellent rotation accuracy. You can see that it is. Incidentally, in the Lissajous circle of the comparative example, the maximum displacement amount with respect to the perfect circle is about 1
In contrast, in the Lissajous circle of the present invention, the maximum displacement with respect to a perfect circle is 0.05 μm or less, which is the original rotation accuracy of the air spindle, and it can be seen that the adverse effect of the motor is almost completely eliminated.

[Effect of the invention]

As described above, according to the present invention, an air spindle is provided with a pulley driven by a motor at a position concentric with the spindle, and a rod is attached to one of the pulley and the spindle and two to the other. By attaching the rollers in the radial direction, sandwiching the rod between these rollers, and connecting the spindle and the pulley, the rotation of the spindle can be accurately positioned, and the influence of motor vibration, heat generation, etc. Thus, high-precision rotation can be performed without being transmitted, and there is an effect that the present invention can be applied to higher-precision precision measurement.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway side view of an air spindle device using the drive structure of the present invention, and FIG. 2 is a sectional view taken along line XX in FIG. FIG. 3 is a Lissajous circle showing radial deflection of a spindle by a conventional drive structure, and FIG. 4 is a Lissajous circle of the present invention. 1 ... Spindle, 2 ... Bearing 6 ... Pulley, 8 ... Motor 13 ... Rod, 14,15 ... Roller

Claims (1)

(57) [Scope of request for utility model registration] 1. An air spindle having a spindle rotatably supported by a hydrostatic fluid, comprising a pulley driven by a motor at a position concentric with the spindle, and a rod attached to one of the pulley and the spindle. On the other hand, two rollers are mounted in parallel with each other such that the rotation axis thereof is in the radial direction of the pulley, and the rod is sandwiched between these rollers to connect the spindle and the pulley. Drive structure of air spindle.