JP2000320615A - How to correct hollow shaft balance - Google Patents

Abstract

(57) [Problem] To provide a hollow shaft balance correction method that can surely correct balance even with a long and thin hollow shaft. SOLUTION: After measuring and grasping a residual imbalance on a large number of cross sections in the axial direction of a hollow shaft 10, a polishing amount necessary for correcting the residual imbalance is calculated and polished. As a result, despite the fact that the engine is vibrated and the cause is unknown even though the balance is obtained by the conventional two-plane balance correction method, the residual unloading on a large number of cross sections in the axial direction is performed. By losing balance,
The balance can be maintained over the entire length of the hollow shaft 10, and stable operation can be achieved without vibration even when the hollow shaft 10 is mounted on the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting the balance of a hollow shaft, and more particularly to a method for correcting the balance of an LP shaft or the like which becomes longer as the size of a jet engine increases.

[0002]

2. Description of the Related Art In a jet engine, for example, FIG.
As shown in (a), the low-pressure compressor 1, the high-pressure compressor 2, the high-pressure turbine 3, the intermediate-pressure turbine 4, and the like are rotated at a high speed such as the LP shaft 5 of the low-pressure compressor 1 and the intermediate-pressure turbine 4. In the hollow shaft, balance correction is performed to correct imbalance due to a manufacturing error or the like.

In order to correct the balance of the shaft, for example, as shown in an enlarged view in FIG. 3B, balance lands 6 for polishing and correcting are provided in advance at both ends of the shaft 5 to reduce the dynamic imbalance. After measuring and calculating the circumferential phase to be polished by the balance land 6 and the amount of polishing, the balance land 6 is polished based on the calculation result to correct the balance.

On the other hand, as the size of the jet engine increases, the overall length of the shaft tends to be longer, and the outer diameter tends to be relatively smaller.

[0005]

However, in the case of such a hollow shaft 5 having a long overall length and a small outer diameter, the vibration of the engine may be caused even when the balance lands 6 formed at both ends are apparently balanced. There is a problem that there is.

The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a method of correcting the balance of a hollow shaft that can reliably correct the balance of a long and thin hollow shaft.

[0007]

SUMMARY OF THE INVENTION In order to solve the problems of the prior art, a concrete structure of the method for correcting the balance of a hollow shaft according to the first aspect of the present invention is as follows. After measuring and grasping the residual imbalance on a large number of cross sections in the axial direction of the shaft, the polishing is performed by calculating a polishing amount required for correcting the residual imbalance.

According to this method of correcting the balance of the hollow shaft, after measuring and grasping the residual imbalance on a large number of cross sections in the axial direction of the hollow shaft, the amount of polishing required for correcting the residual imbalance is calculated. By measuring the residual unbalance on a large number of cross sections in the axial direction and calculating the amount of polishing required to eliminate this, polishing is performed over the entire length of the hollow shaft. Therefore, the vehicle can be driven without vibration even when mounted on the engine.

According to a second aspect of the present invention, there is provided a method for correcting the balance of a hollow shaft, wherein the residual imbalance is obtained by measuring the eccentricity of the inner and outer diameters and the thickness distribution. On the other hand, the polishing amount is calculated based on the circumferential phase and magnitude of the residual unbalance.

According to this method of correcting the balance of the hollow shaft, the residual unbalance is grasped by measuring the eccentricity of the inner and outer diameters and the thickness distribution, while the polishing amount is determined by the circumferential phase and magnitude of the residual unbalance. The residual unbalance is known from the eccentricity of the inner and outer diameters and the thickness distribution on each cross section in the axial direction, and the polishing amount based on this is determined by the circumferential phase of the residual unbalance and By calculating based on the size, a specific balance correction can be performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method for correcting the balance of a hollow shaft according to the present invention will be described below in detail with reference to the drawings.

First, in this method of correcting the balance of the hollow shaft, as shown in FIG. 1, the residual imbalance is measured and grasped on a large number of cross sections in the axial direction over the entire length of the hollow shaft 10.

The measurement and grasp of the residual imbalance are performed, for example, by measuring the deflection and the thickness distribution of the inner and outer diameters with respect to the central axis 11 on a large number of axial cross sections over the entire length of the hollow shaft 10. From this, the axial position, circumferential phase, and magnitude of the residual unbalance are obtained.

That is, many measurement positions 1 to n are determined over the entire length of the hollow shaft 10, and the cross-sectional shape of the hollow shaft 10 at each measurement point is precisely measured. Thus, for example, the thickness distribution at the measurement position at the center of the hollow shaft 10 in FIG. 2 can be obtained as a deviation from the original thickness (NOMARL thickness) together with the circumferential phase, and there is no deviation. It can be seen that the wall thickness distribution occurs in each circumferential phase (shown by the time on the clock) with respect to the perfect circle in the case of (shift = 0).

In this way, when the thickness distribution is known together with the circumferential phase from the result of the precise measurement of the cross-sectional shape at each measurement point, the unbalance amount (g) of each circumferential phase at each measurement position is obtained.
· Cm).

After the circumferential phase and magnitude of the unbalance amount at each measurement position in the axial direction of the hollow shaft 10 are determined in this way, the thick part is polished to become equivalent to the thin part. Up to the outer diameter,
Polish smoothly in the axial direction. At this time, the polished portion is set so as to be within the allowable thickness.

In the hollow shaft 10 which has been subjected to such a balance correction, the cause of the vibration in the engine is unknown in a state where the balance is obtained by the conventional dynamic balance correction using the balance lands at the front and rear ends. Even in such a situation, there is no residual imbalance at the center of the hollow shaft 10 or the like, and it is possible to prevent the generation of vibrations and rotate stably at high speed.

In this method of correcting the balance of the hollow shaft, the balance can be surely corrected by measuring the residual unbalance and correcting the balance by eccentric polishing or the like so as to eliminate the residual unbalance. The balance correction can be performed with higher accuracy than the balance correction.

By correcting the imbalance completely, theoretically, even if the critical speed of the shaft is in the operating range, no problem such as vibration occurs, and the outer diameter of the shaft can be made thinner. Will be possible.

It should be noted that the present invention is not limited to the above-described embodiment, and the number of processings and steps may be further increased depending on the circumferential phase at which residual unbalance occurs.

In order to obtain the residual unbalance, the shape measurement on the cross section at each measurement position may be performed by using an ultrasonic thickness measuring device or the like. Anything that can measure the height may be used.

Further, the applicable range is not limited to the hollow shaft of the jet engine, but can be widely applied to balance correction of a long and narrow hollow shaft.

[0023]

As described above in detail with one embodiment, according to the method for correcting the balance of the hollow shaft according to the first aspect of the present invention, the hollow shaft has a large number of cross sections in the axial direction. After measuring and grasping the residual unbalance, the amount of polishing required to correct the residual unbalance was calculated and polished, so based on the measurement results of the residual unbalance on many cross sections in the axial direction. By calculating and polishing the amount of polishing required to eliminate this, it is possible to balance over the entire length of the hollow shaft, and balance is achieved by the conventional two-sided balance correction, and the cause of vibration is unknown. Even in such a case, it is possible to stably operate the apparatus mounted on the engine without generating vibration.

According to the method of correcting the balance of the hollow shaft according to the second aspect of the present invention, the residual unbalance is determined by measuring the eccentricity of the inner and outer diameters and the thickness distribution, while the polishing amount is determined by the residual. Since the calculation is based on the phase and magnitude of the unbalance in the circumferential direction, the residual unbalance can be determined from the eccentricity of the inner and outer diameters and the thickness distribution on each cross section in the axial direction, and the polishing amount based on this Is calculated based on the circumferential phase and magnitude of the residual unbalance,
The balance of the actual hollow shaft can be easily corrected.

[Brief description of the drawings]

FIG. 1 is a principle explanatory diagram according to an embodiment of a hollow shaft balance correcting method of the present invention.

FIG. 2 is a graph showing a measurement result of a residual unbalance according to an embodiment of the hollow shaft balance correcting method of the present invention.

FIG. 3 is an explanatory view of a hollow shaft of a jet engine to which the present invention is applied.

[Explanation of symbols]

 10 Hollow shaft

Claims (2)

[Claims] When correcting the balance of a hollow shaft, after measuring and grasping a residual imbalance on a large number of cross sections in the axial direction of the hollow shaft, a polishing amount required for correcting the residual imbalance is calculated. A method for correcting the balance of a hollow shaft, characterized in that the shaft is polished. 2. The method according to claim 1, wherein the residual unbalance is determined by measuring an eccentric amount of inner and outer diameters and a thickness distribution, and calculating the polishing amount based on a circumferential phase and a magnitude of the residual unbalance. The method for correcting the balance of a hollow shaft according to claim 1, wherein: