JPH1043987A - Balance correcting method of rotary shaft supported by static pressure bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely correct a balance of a rotary shaft by improving correcting workability, and shortening correcting time. SOLUTION: A rotary shaft 1 is rested, and resting time bearing rigidity ksl under supply pressure P1 to a radial static pressure bearing 12 and resting time bearing rigidity ks2 under supply pressure P2 are measured, and then, the rotary shaft 1 is rotated, and a swing ed1 of the rotary shaft 1 under the supply pressure P1 and a swing ed2 of the rotary shaft 1 under the supply pressure P2 are measured. Next, centrifugal force F is calculated by using the resting time bearing rigidity ks1 and ks2, the swing ed1 and the swing ed2 on the basis of F=[ed1×ed2×(ks2-ks1)/(ed1 ed2)], and mass (m) of a screw (w) installed in a screw hole 20a arranged on the circumference of a radius (r) of the rotary shaft 1 is determined from a radius (r), angular velocityty ω, centrifugal force F and F=mrω<2> , and, and an intermediate position of (+θ) and (-θ) of respective eccentric angles respectively measured by normally rotating and reversely rotating the rotary shaft 1, is judged as the eccentric direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a polishing apparatus having a rotating shaft supported via a radial static pressure bearing, which is supported by a static pressure bearing used at the time of attaching a grindstone such as when replacing a grindstone. The present invention relates to a method for correcting the balance of a rotating shaft.

[0002]

2. Description of the Related Art Conventionally, for example, in a polishing apparatus provided with a rotating shaft supported on a housing via a radial static pressure bearing, when a grindstone is attached to the rotating shaft to correct the balance, as shown in FIG. By disposing the displacement sensor 51 toward the bearing center O and attaching a mark M as a reference of the phase at the time of the balance correction to the rotating shaft 50, the runout E of the rotating shaft 50 due to the unbalance and the phase of the mark M Was to be detected.

The eccentric direction or the eccentric direction is 1
A known trial weight W is attached to an arbitrary position in the opposite direction by 80 ° to rotate the rotating shaft 50. At this time, the displacement sensor 51
Is compared with the run-out E of the rotary shaft 50 detected by the above, and the run-out E of the rotary shaft when the test weight W is not attached.
The corrected mass was determined.

[0004]

However, in the above-mentioned conventional method of correcting the balance of the rotating shaft supported by the hydrostatic bearing, when the rotating shaft 50 is rotated, the dynamic pressure is added to the static bearing rigidity. Bearing rigidity during rotation (Fig. 4
(A part hatched in (a))), the rotating shaft 50 is eccentric to a phase having a certain angle と from the eccentric direction. Furthermore, the eccentric direction is not always accurate because the eccentric angle に よ っ て changes depending on the magnitude of the unbalance amount. In addition, the unbalance amount of the rotary shaft 50 is obtained by the trial weight W. Therefore, even if the eccentric direction is determined, until the runout E of the rotating shaft 50 is almost eliminated,
In the eccentric direction or in the vicinity thereof, the replacement of the test weight W must be performed many times, and as a result, there is a problem that the correction of the balance is troublesome and difficult, and a lot of time is spent. Therefore, it was a conventional problem to solve this problem.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is intended to improve the workability of correction and shorten the time required for correction, and to correct the balance of the rotating shaft precisely. It is an object of the present invention to provide a method for correcting the balance of a rotating shaft supported by a hydrostatic bearing, which is possible.

[0006]

When a rotary shaft supported by a radial static pressure bearing is rotated, as shown in FIG. 1, in addition to the static bearing rigidity ks due to the static pressure, the rotational bearing due to the dynamic pressure is used. The rigidity Kd 'and the bearing rigidity Kd due to the squeeze force are generated.

At this time, if the total bearing stiffness kd, which is the sum of the stationary bearing stiffness ks, the rotating bearing stiffness Kd ', and the bearing stiffness Kd due to the squeeze force, can be measured in advance, the rotating shaft 1 shown in FIG. The centrifugal force F can be calculated based on the following equation: F = e × kd (F: centrifugal force due to unbalance (unbalance amount)). kd
′ Occurs in a direction delayed by an angle θ (eccentric angle θ) from the eccentric direction and depends on the magnitude of the centrifugal force F. The bearing stiffness kd due to the squeeze force is determined by a deflection (amount of eccentricity) e and It is difficult to measure the total bearing stiffness kd in advance because it depends on the rotation frequency.

However, the static bearing rigidity k due to the static pressure k
Focusing on the fact that s does not depend on rotation, and that the bearing stiffness kd 'during rotation due to dynamic pressure and the bearing stiffness kd due to squeeze force are not affected by changes in supply pressure, FIG. The bearing rigidity at rest ks1, the total bearing rigidity kd1, and the supply pressure P at the pressure P1
2 and the total bearing rigidity kd2, kd2-ks2 = α2, kd1-ks1 = α1, α1
The relationship α2 (= α) holds, and therefore, it is understood that the centrifugal force F can be calculated from the above F = e × kd by measuring the bearing stiffness ks1, ks2 at rest and the run-out e independent of the rotation.

When the rotation axis 1 is rotated forward and backward, attention is paid to the fact that the respective eccentric angles + θ and −θ are symmetrical in the rotational direction. It can be seen that the position is in the eccentric direction.

A method for correcting the balance of a rotating shaft supported by a hydrostatic bearing according to the present invention is performed based on the above-mentioned point of view. In the method, when correcting the balance of the rotating shaft supported by the radial static pressure bearing, the stationary bearing rigidity ks1 and the supply pressure P2 at the supply pressure P1 with respect to the radial static pressure bearing with the rotating shaft stationary.
At the time of static bearing ks2, and then, while rotating the rotating shaft, measure the deflection ed1 of the rotating shaft at the supply pressure P1 to the radial hydrostatic bearing and the deflection ed2 of the rotating shaft at the supply pressure P2. After that, the total bearing stiffness obtained by adding the bearing stiffness during rotation ks1 and the bearing stiffness during rotation and the bearing stiffness due to the squeeze force is kd1, and the bearing stiffness during rotation and the bearing stiffness due to the squeeze force are defined as the static bearing stiffness ks2. Assuming that the added total bearing stiffness is kd2, the relationship is established because the bearing stiffness during rotation and the bearing stiffness due to the squeeze force are not affected by the change in the supply pressure. ≒
kd1 = α + ks1, kd2 = α + ks2 obtained from the relationship of α2 (= α). Expression ed1 × kd1 for calculating the centrifugal force F due to the unbalance generated when the rotary shaft is rotated under the supply pressure P1 and the supply pressure P2. = F, ed2 × kd2 = F, and furthermore, the equation ed1 × ed2 × (ks2-ks1) / (ed1-ed
2) Calculate the centrifugal force F based on = F 2, and calculate the mass m of the corrected weight attached on the circumference of a predetermined radius r on the rotation axis by the radius r, the angular velocity ω, and the centrifugal force F,
And it determines from F = mrω ² Prefecture, and characterized by determining the direction of eccentricity of the intermediate position of the eccentric angle measured respectively the rotary shaft rotated forward and reverse rotation,
The configuration of the method of correcting the balance of the rotating shaft supported by the hydrostatic bearing is a means for solving the conventional problems.

According to a second aspect of the present invention, there is provided a method for correcting the balance of a rotating shaft supported by a hydrostatic bearing, wherein a plurality of correction weight mounting portions are provided on a circumference of a radius r in claim 2. It is characterized by.

The method for correcting the balance of a rotating shaft supported by a hydrostatic bearing according to the present invention includes correcting the balance of a rotating shaft supported by a radial hydrostatic bearing using hydraulic pressure, and a so-called hydrostatic gas using pneumatic pressure. It can be used for any of the balance correction of the rotating shaft supported by the bearing,
Due to the low rotational resistance and low bearing rigidity, it is desirable to apply the present invention to the balance correction of a rotating shaft supported by a hydrostatic gas bearing capable of measuring a minute displacement of the rotating shaft.

[0013]

According to the method of correcting the balance of the rotating shaft supported by the hydrostatic bearing according to the first aspect of the present invention, since the above-described configuration is employed, the method of correcting the balance of the rotating shaft supported by the radial hydrostatic bearing is employed. , The stationary bearing rigidity ks1 at the supply pressure P1 and the stationary bearing rigidity ks at the supply pressure P2 with respect to the radial hydrostatic bearing with the rotating shaft stationary.
2 and then, while rotating the rotating shaft, run-out ed1 of the rotating shaft at the supply pressure P1 to the radial hydrostatic bearing.
By measuring the deflection ed2 of the rotating shaft at the supply pressure P2, the centrifugal force F caused by the unbalance can be obtained, and each eccentric angle when the rotating shaft is rotated forward and backward is measured. If the intermediate position is determined as the eccentric direction, it is not necessary to change the test weight, so that the correction workability is improved, the correction time is shortened, and the balance of the rotating shaft is precisely corrected. Will be done.

According to the method of correcting the balance of the rotating shaft supported by the hydrostatic bearing according to the second aspect of the present invention, since the above-described configuration is employed, the mounting of the correction weight can be easily performed, and the correction workability can be further improved. And the correction time can be greatly reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view of a method of correcting the balance of a rotating shaft supported by a hydrostatic bearing according to the present invention, and FIGS. 2 and 3 show a rotary shaft supported by a hydrostatic bearing according to an embodiment of the present invention. 4 shows a main shaft portion of a polishing apparatus to which a shaft balance correcting method is applied.

As shown in FIG. 2, a main shaft 10 of the polishing apparatus is connected to a housing 11 and one end (the right end in the figure) housed in the housing 11 and connected to a polishing apparatus driving section (not shown). A rotating shaft 1 on which a grindstone T as a tool is attached to the other end (the left end in the figure), and radial static pressure bearings 12 supporting small diameter portions 1a provided on both ends of the rotating shaft 1; 12, an oil feed pump 13 for feeding oil to the radial static pressure bearing 12 via an oil feed passage 13a, an air source 14 communicating with the oil feed passage 13a via an air feed passage 14a, and an air feed passage 14a. A check valve 15 provided, a displacement meter 16 attached to the housing 11 so as to face a small-diameter portion 1a located at one end of the rotary shaft 1, and a housing 1
1 is provided with a rotation detector 17 attached so as to face the small-diameter portion 1a located on the other end side of the rotating shaft 1, a displacement gauge 16 for measuring the shake of the rotating shaft 1, and a rotation for measuring the phase of the shake. The detector 17 is connected to the arithmetic unit 18.

In the main shaft portion 10 of the polishing apparatus, during polishing, the oil supply pump 13 operates to feed oil higher in pressure than the compressed air sent from the air source 14 to the radial static pressure bearings 12, 12 so that the hydraulic pressure is increased. Supports the rotating shaft 1 by
On the other hand, during the balance correction, the oil supply pump 13 is stopped to send compressed air to the radial static pressure bearings 12 and 12 to support the rotary shaft 1 by air pressure.

In the main shaft portion 10 of the polishing apparatus, the grinding wheel T is sandwiched between the plate 20 fixed to the center of the other end surface of the rotating shaft 1 by a bolt (not shown) and the other end surface of the rotating shaft 1. In this case, as shown in FIG. 3, the plate 20 is provided with a plurality of screw holes (correction weight attachment portions) 20a located on the circumference of the radius r at substantially equal intervals.

In correcting the balance of the rotary shaft 1 with the grinding wheel T attached thereto in the main shaft portion 10 of the polishing apparatus, first, the oil feed pump 13 is stopped and the rotary shafts are mounted on the radial static pressure bearings 12, 12. 1 is supported by air pressure.

Next, while the rotating shaft 1 is stationary, a predetermined load is applied to the grindstone T as the supply pressure P1 to the radial static pressure bearings 12, 12, and the stationary bearing rigidity ks at this time is applied.
1 is measured by the displacement meter 16, and a predetermined load is similarly applied to the grindstone T as the supply pressure P <b> 2, and the stationary bearing rigidity ks <b> 2 at this time is measured by the displacement meter 16.

Subsequently, while the rotating shaft 1 is rotating, the rotation of the rotating shaft at the supply pressure P1 to the radial static pressure bearings 12 and 12 and the rotation of the rotating shaft at the supply pressure P2 are ed.
2 is measured by the displacement meter 16.

Here, the total bearing rigidity kd1 is obtained by adding the rotational bearing rigidity Kd 'and the bearing rigidity Kd due to the squeeze force to the static bearing rigidity ks1 and the static bearing rigidity kd1.
If the total bearing rigidity kd2 is obtained by adding the rotational bearing rigidity Kd 'and the bearing rigidity Kd due to the squeeze force to s2, the rotational bearing rigidity Kd' and the bearing rigidity Kd due to the squeeze force are not affected by changes in the supply pressure. As shown in FIG. 1, kd2-ks2 = α2, kd1-ks1 = α1, α1α
The relationship α2 (= α) holds.

That is, kd1 = α + ks1, kd2 =
α + ks2 is a formula for obtaining a centrifugal force F due to an unbalance generated when the rotary shaft 1 is rotated under the supply pressure P1 and the supply pressure P2, respectively. ed1 × kd1 = F, ed2 × kd
2 = F, and ed1 × ed2 × (ks2-ks1) / (ed1-ed) obtained by eliminating α.
2) From = F 2, the centrifugal force F is calculated by using the stationary bearing rigidity ks1 at the supply pressure P1, the rotational shaft runout ed1 and the stationary bearing rigidity ks2 at the supply pressure P2, and the rotary shaft runout ed2.

Next, the mass m of the screw (corrected weight) w to be attached to the plurality of screw holes 20a provided on the circumference of the plate 20 with the radius r is determined by the radius r, the angular velocity ω, and the centrifugal force F, F = determined from mrω ² Metropolitan.

Thereafter, the rotation shaft 1 is rotated forward and backward, and each time, the phase of the runout e of the rotation shaft 1 detected by the displacement meter 16 and the rotation pulse obtained from the rotation detector 17 are calculated by the arithmetic unit 18. The eccentric angles + θ and −θ are measured, and the intermediate position between the eccentric angles + θ and −θ is determined as the eccentric direction z. The screw w determined as described above is attached to the screw hole 20a located on the circumference of.

Therefore, in the method of correcting the balance of the rotating shaft supported by the static pressure bearing, the static bearing rigidity ks1 at the supply pressure P1 and the static bearing rigidity ks2 at the supply pressure P2, which can be accurately measured in advance, and the rotational Rotational shaft deflection ed1 at supply pressure P1 that can be measured by rotating shaft 1.
The centrifugal force F caused by the unbalance is obtained using the rotation shaft deflection ed2 at the supply pressure P2, and the eccentric angles + θ, − measured respectively by rotating the rotation shaft 1 forward and reverse. Since the eccentric direction is obtained by using θ, precise balance correction of the rotating shaft 1 is performed. In addition, since it is not necessary to perform the work of changing the test weight, which has been conventionally performed, the correction workability is improved. While improving,
The correction time can be shortened.

Further, since a plurality of screw holes 20a located on the circumference of the radius r are provided at substantially equal intervals in the plate 20 on which the grindstone 4 is attached to the rotating shaft 1, the screw w serving as a correction weight is provided. The attachment is simple, and as a result, the repair workability is further improved and the repair time is significantly reduced.

In the above-described embodiment, the case where the method of correcting the balance of the rotating shaft according to the present invention is applied to the main shaft portion 10 of the polishing apparatus has been described, but the present invention is not limited to this.

The detailed configuration of the method for correcting the balance of the rotating shaft according to the present invention is not limited to the above-described embodiment.

[0031]

As described above, according to the first aspect of the present invention,
In the method for correcting the balance of the rotary shaft according to the above, the configuration described above is adopted, and when correcting the balance of the rotary shaft supported by the radial static pressure bearing, the supply pressure P1 to the radial static pressure bearing while the rotary shaft is stationary. The static bearing stiffness ks1 at the supply pressure P2 and the static bearing stiffness ks2 at the supply pressure P2 are measured. Then, while the rotation shaft is rotating, the run-out e of the rotary shaft at the supply pressure P1 with respect to the radial static pressure bearing e
It is possible to obtain the centrifugal force F caused by the unbalance simply by measuring the runout ed2 of the rotating shaft at d1 and the supply pressure P2, and in addition, each eccentricity when the rotating shaft is rotated forward and backward. Just by measuring each angle, the intermediate position can be determined as the eccentric direction, and as a result, the balance of the rotating shaft can be corrected very precisely. In addition, the work of replacing the test weight, which was conventionally performed This eliminates the necessity of performing the above-described operations, thereby providing a very excellent effect that it is possible to improve the correction workability and shorten the correction time.

According to the method of correcting the balance of the rotating shaft supported by the hydrostatic bearing according to the second aspect of the present invention, the above-described configuration allows the correction weight to be easily attached.
Therefore, a very excellent effect that the improvement of the correction workability and the shortening of the correction time can be realized.

[Brief description of the drawings]

FIG. 1 is a graph (a) showing the relationship between bearing stiffness and supply pressure for explaining a method of correcting the balance of a rotating shaft according to the present invention.
FIG. 7B is an explanatory diagram (b) of an eccentric situation when the rotating shaft is rotating.

FIG. 2 is an explanatory cross-sectional view showing a main shaft portion of a polishing apparatus to which a method for correcting a balance of a rotating shaft according to the present invention is applied.

FIG. 3 is an explanatory front view of a plate fixed to a main shaft portion of the polishing apparatus in FIG. 2;

FIG. 4A is an explanatory diagram of a state of eccentricity when a rotating shaft is rotating, showing a conventional method of correcting the balance of a rotating shaft, and FIG. b).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary shaft 12 Radial static pressure bearing 20a Screw hole (Modified weight attachment part) w Screw (Modified weight)

Continued on the front page (72) Inventor Yu Owada Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Manabu Wakuda 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa, Nissan Motor Co., Ltd. (72) Invention Toshiichi Otani 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture, Nissan Motor Co., Ltd. (72) Inventor Minoru Ota 2 Takaracho, Kanagawa-ku, Yokohama City, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Katsutoshi Miyahara, Inventor Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa

Claims (2)

[Claims] When correcting the balance of a rotating shaft supported by a radial static pressure bearing, the stationary bearing stiffness ks1 and the supply pressure at a supply pressure P1 to the radial static pressure bearing with the rotating shaft stationary. The bearing rigidity at rest ks2 at P2 is measured. Then, while rotating the rotating shaft, the deflection ed1 of the rotating shaft at the supply pressure P1 to the radial hydrostatic bearing and the deflection ed2 of the rotating shaft at the supply pressure P2 are measured. After the measurement, the total bearing stiffness obtained by adding the bearing stiffness at rest ks1 to the bearing stiffness at rotation and the bearing stiffness due to the squeeze force is kd1, and the bearing stiffness at rotation ks2 and the bearing stiffness at rotation and the squeeze force are used. When the total bearing stiffness obtained by adding the above is kd2, the bearing stiffness during rotation and the bearing stiffness due to the squeeze force are affected by changes in the supply pressure. Established by the absence kd2-ks2 = α2, kd1-ks1 = α1, α1 ≒
kd1 = α + ks1, kd2 = α + ks2 obtained from the relationship of α2 (= α). Expression ed1 × kd1 for calculating the centrifugal force F due to the unbalance generated when the rotary shaft is rotated under the supply pressure P1 and the supply pressure P2. = F, ed2 × kd2 = F, and furthermore, the equation ed1 × ed2 × (ks2-ks1) / (ed1-ed
2) Calculate the centrifugal force F based on = F 2, and calculate the mass m of the corrected weight attached on the circumference of a predetermined radius r on the rotation axis by the radius r, the angular velocity ω, and the centrifugal force F,
And determines from F = mrω ² Prefecture, is supported by a hydrostatic bearing, wherein the determining the direction of eccentricity of the intermediate position of the eccentric angle measured respectively the rotary shaft rotated forward and reverse rotation How to correct the rotation axis balance. 2. The method for correcting balance of a rotating shaft supported by a hydrostatic bearing according to claim 1, wherein a plurality of correcting weight mounting portions are provided on a circumference of a radius r of the rotating shaft.