CN110763399A - CT rotor static balance method - Google Patents

Abstract

The invention discloses a static balancing method of a CT rotor, which comprises the following steps of (1) controlling the CT rotor to rotate at a low speed of 4-6rpm in a driver speed mode, (2) collecting a motor current feedback signal and a rotor angle position feedback signal after the speed is stabilized, (3) identifying a wave peak value Imax, a wave trough value Imin a current waveform and a rotor angle value α corresponding to the wave peak value, (4) calculating a torque amplitude T = Kt [ (0.5 Imax + Imin) -Imax ], Kt is a motor constant, (5) calculating an unbalance amount m = T/(g r), r is a counterweight radius, and theta = α +90 degrees is a counterweight angle.

Description

CT rotor static balance method

Technical Field

The invention relates to the technical field of tomography medical instruments, in particular to a static balance method of a CT rotor.

Background

In the prior art, the static unbalance of the CT rotor is measured by a push-pull dynamometer to measure the thrust difference at different angles, the size and the position of the unbalance are identified, and balancing is performed. However, the following problems exist: when the push-pull dynamometer is used for measurement, different people are caused by the difference of static friction and dynamic friction, the difference of pushing speed and uniformity and the difference of individual angle defects, and the difference of the first thrust values at different times is large and inaccurate; an additional thrust gauge is needed to be operated manually, the operation is complex, and the efficiency is low. The thrust difference of each angle of a circle cannot be identified, the calculation accuracy is poor, and the thrust change caused by non-unbalance factors cannot be eliminated.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a static balance method of a CT rotor, which can automatically identify the size and the position of the unbalance; no extra instrument is needed, the operation is simple, and the efficiency is high; the method is not influenced by human factors, can eliminate the interference of non-unbalance factors and has high precision.

In order to achieve the purpose, the invention provides the following technical scheme: a static balancing method of a CT rotor comprises the following steps:

(1) under the speed mode of a driver, controlling the CT rotor to rotate at a low speed of 4-6rpm at a uniform speed;

(2) after the speed is stable, collecting a motor current feedback signal and a rotor angle position feedback signal;

(3) identifying a wave crest value Imax, a wave trough value Imin and a rotor angle value α corresponding to the wave crest value in the current waveform;

(4) calculating a torque magnitude T = Kt [ (0.5 (Imax + Imin) -Imax ], Kt being a motor constant;

(5) calculating the unbalance m = T/(g r), wherein r is the radius of the counterweight, and theta = α +90 degrees is the angle of the counterweight;

(6) and (4) termination judgment: if the unbalance amount m r is smaller than the allowable unbalance amount, ending; otherwise, stopping rotation, adding a balancing weight with mass m at the radius of r and the angle of theta, or decomposing an equivalent vector to add weights in two fixed weight directions, and then returning to the step (1).

Further, the uniform rotation speed of the CT rotor in the step (1) is 5 rpm.

In conclusion, the CT rotor static balance method can automatically identify the size and the position of the unbalance amount; no extra instrument is needed, the operation is simple, and the efficiency is high; the method is not influenced by human factors, can eliminate the interference of non-unbalance factors and has high precision.

Drawings

FIG. 1 is a flow chart of the process control of the present invention;

FIG. 2 is a graph of current phase angle in an embodiment of the present invention.

Detailed Description

An embodiment of a static balancing method for a CT rotor according to the present invention is further described with reference to fig. 1.

A static balancing method of a CT rotor comprises the following steps:

(1) under the speed mode of a driver, controlling the CT rotor to rotate at a low speed of 4-6rpm at a uniform speed;

(2) after the speed is stable, collecting a motor current feedback signal and a rotor angle position feedback signal;

(3) identifying a wave crest value Imax, a wave trough value Imin and a rotor angle value α corresponding to the wave crest value in the current waveform;

(4) calculating a torque magnitude T = Kt [ (0.5 (Imax + Imin) -Imax ], Kt being a motor constant;

(5) calculating the unbalance m = T/(g r), wherein r is the radius of the counterweight, and theta = α +90 degrees is the angle of the counterweight;

(6) and (4) termination judgment: if the unbalance amount m r is smaller than the allowable unbalance amount, ending; otherwise, stopping rotation, adding a balancing weight with mass m at the radius of r and the angle of theta, or decomposing an equivalent vector to add weights in two fixed weight directions, and then returning to the step (1).

In this embodiment, preferably, the uniform rotation speed of the CT rotor in step (1) is 5 rpm.

The examples, taking Minfound CT256 as an example, are described as follows:

(1) controlling the CT rotor to rotate at 5rpm under the speed mode of the driver;

(2) after the speed is stable, collecting a motor current feedback signal and a rotor angle position feedback signal;

after the data are transferred into excel, a current (ordinate) phase angle (abscissa) curve is shown in fig. 2;

(3) identifying a peak value Imax =2.444, a trough value Imin =1.486, and a rotor angle value α =177 ° corresponding to the peak value in the current waveform;

(4) calculating a torque magnitude T = Kt [ (0.5 (Imax + Imin) -Imax ] =8.3Nm, Kt =17.33 is the motor constant;

(5) calculating the unbalance amount m = T/(g r) =1.04kg, r =0.815m is the radius of the counterweight, and theta = α +90 degrees =267 degrees is the angle of the counterweight;

(6) at 267 °, 0.815m from the center of rotation, a 1.04kg weight plate was added to complete the balancing.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.

Claims (2)

1. A static balancing method of a CT rotor is characterized by comprising the following steps:

(1) under the speed mode of a driver, controlling the CT rotor to rotate at a low speed of 4-6rpm at a uniform speed;

(2) after the speed is stable, collecting a motor current feedback signal and a rotor angle position feedback signal;

(3) identifying a wave crest value Imax, a wave trough value Imin and a rotor angle value α corresponding to the wave crest value in the current waveform;

(4) calculating a torque magnitude T = Kt [ (0.5 (Imax + Imin) -Imax ], Kt being a motor constant;

(5) calculating the unbalance m = T/(g r), wherein r is the radius of the counterweight, and theta = α +90 degrees is the angle of the counterweight;

(6) and (4) termination judgment: if the unbalance amount m r is smaller than the allowable unbalance amount, ending; otherwise, stopping rotation, adding a balancing weight with mass m at the radius of r and the angle of theta, or decomposing an equivalent vector to add weights in two fixed weight directions, and then returning to the step (1).

2. The CT rotor static balancing method of claim 1, wherein: the CT rotor in the step (1) rotates at a constant speed of 5 rpm.

Images