KR100228024B1 - Overhaul method of large scale rotor system using strain gauge - Google Patents

Abstract

The present invention provides a more optimized maintenance by establishing a system capable of aligning the rotating shaft in the state in which the coupling is fastened, enabling continuous measurement in the rotating shaft axial alignment, and the continuous monitoring through the mortar. The present invention relates to a maintenance method of a large rotating body using a strain gauge, and to detect and adjust the amount of shaft deformation of a rotating body coupled to a driving force generating means in multiple stages in a power generation facility. Attaching a strain gauge to the step of detecting the quantitative strain of each coupling part due to the bending moment by the following equation; Detecting the bending moment value of the rotating body by the following equation using a proportional relationship between the strain value and the bending moment; The bending moment value maintenance method of a large rotating body using a strain gauge comprising the step of detecting the feed amount of the bearing by the following formula (3).

Where M: bending moment of the rotor axis, E: Young's Modulus

: 축방향 스트레인,R: radius of the rotor shaft, f: stress concentration coefficient

: Axial strain,

Where L is the distance from the center of the coupling to each gauge

R: Radius of rotating shaft with strain gauge

: 스트레인 게이지에서 측정된 스트레인 값

: Strain value measured in strain gage

f: stress concentration coefficient of rotating shaft with strain gage

: 위상각

Phase angle

Where M is the measured bending moment, K is the rigid matrix acting on the rotating body, and U is the adjustment amount of the bearing.

Description

Maintenance Method of Large Rotating Body Using Strain Gage

The present invention relates to a maintenance method of a large rotating body, and more particularly, it is possible to align the rotating shaft in the state in which the coupling is fastened, continuous measurement in the rotating shaft alignment is possible, and through monitoring The present invention relates to a method of maintaining a large rotating body using a strain gauge so that a system that can be continuously monitored can be built for more optimized maintenance.

Numerous and various large rotors are operated in power plants such as nuclear power, hydropower, and thermal power, and as one of the representative large rotors, a turbine, which is a driving source of a generator, has a complex structure such as a shaft, a blade, a coupling, and a bearing. Currently, power generation turbines are difficult to design and manufacture due to the unique technology of domestic companies, and power generation turbines operated in Korea are manufactured in foreign countries, and various support for maintenance and maintenance of turbines is difficult. Therefore, regular and continuous maintenance of a large rotating body of a power plant can be said to be a shortcut for securing the stability and reliability of the facility.

In a large rotor, a shaft with a large load is rotated at a high temperature and a high pressure, and after a certain period of time, misalignment due to offset, angle, and combination between the shaft and the shaft occurs. This misalignment not only acts as a noise and vibration source of power generation facilities, but also causes stress concentration on the coupling part, which is the weakest part of a large rotating body, which shortens the life of the device and, in the worst case, breaks during rotation. May result.

Currently, shaft alignment is only possible by manual operation using a dial gauge, and thus, shaft alignment in an optimal state is impossible, and the operating state of the rotating body during operation cannot be measured except vibration. In order to prevent metal fatigue of large rotors, the bending moment of the coupling part, which is called a weak part, should be kept at "0". However, the conventional method using a dial gauge cannot measure the quantitative bending moment. The moment generated during operation may cause metal fatigue and lead to aging of the equipment. In addition, the time required for the shaft alignment is long, there is a waste of manpower and time in the maintenance work, and there is an inefficient aspect in the operation of the power generation equipment.

Based on this, the axis alignment method by dial gauge can be divided into the coupling disassembly process and the reassembly process.

The coupling disassembly process stops the rotating body, and removes the optimum materials, foreign substances, and pate attached during operation.On average, the thermal power plant is cooled for 7 days and the nuclear power plant is cooled for 3 days. do. After measuring the runout and bearing position before disconnecting the coupling, remove the coupling bolt and check the Rim & Face. Based on this, the vertical and horizontal angles and parallelisms are calculated, and the state change before and after disassembly depends only on the result value, and the state of all changes in the process of work is not known at all. It takes about a day.

In the coupling reassembly process, after axial alignment is completed by using a dial gauge, each coupling is temporarily assembled to match each other, and the first bolt is fastened to check the condition. Run-out measurement is performed again, and finally the bolt is fastened. After the above process, the final state such as center deviation and resonance departure is checked. Even during the reassembly as described above, since the coupling is assembled in the final shaft alignment state, only the final shape before coupling is known, so there is no knowledge of any change in the progress of the fastening operation.

The value to adjust the bearing to the optimum value of face is H.

If the bearing close to the coupling is the reference, the change amount of Ri is C.

If the bearing that is far from the coupling is the reference, then the amount of change in Rim is C _D ,

here,

L1: Distance from the reference coupling to the nearest bearing

L2: Distance from reference coupling to distant bearing

F: Angle between faces for reference coupling

D: diameter of rotating shaft

R is the main offset of the coupling

H, C, and C _D are obtained using equations (1) to (3), and the deflection adjustment amounts of the bearings are obtained from the following equations using these values.

The equation for calculating the shim adjustment of the bearing close to the reference coupling is

To obtain the shim adjustment of the bearing far from the reference coupling

to be. Equations (6) and (10) are mainly used, and most of the other equations are often used for comparison. 2 of the accompanying drawings shows F and R as schematic diagrams of the rotor simulator, and L1 and L2 change accordingly when the reference coupling is changed.

Although the shaft is aligned by using the above calculation formula, the two shafts are connected by coupling and operated as one axis. Without resorting to the situation, it is almost impossible to obtain the necessary values for maintenance. In other words, the result is obtained only in the final decomposition state, but finding the cause without any intermediate process starts with the empirical ground. Improvement of maintenance method had to be urgently prepared.

Accordingly, the present invention has been made to solve the above problems, the object of which is to enable the alignment of the rotating shaft in the state of coupling coupling, the continuous measurement in the rotating shaft alignment, It is to provide the maintenance method of large rotating body using strain gauge to build a system that enables continuous monitoring through monitoring for more optimized maintenance.

In order to achieve the above object, the present invention, in detecting and adjusting the shaft deformation amount of the rotating body coupled to the driving force generating means in a multi-stage in the power generation equipment, a strain gauge is attached to each coupling portion of the rotating body Detecting the quantitative strain of each coupling part by the bending moment by the following equation, and detecting the bending moment value of the rotating body by the following equation by using the proportional relationship between the strain value and the bending moment. ; The bending moment value is characterized by including the step of detecting the conveying amount of the bearing by the following equation.

here,

M: bending moment of the rotor shaft, E: Young's Modulus

: 축방향 스트레인,R: radius of rotor shaft, f: stress concentration coefficient

: Axial strain,

here,

M: Distance from the center of coupling to each gauge

R: Radius of rotating shaft with strain gauge

: 스트레인 게이지에서 측정된 스트레인 값

: Strain value measured by strain gauge

f: stress concentration coefficient of rotating shaft with strain gage

: 위상각

Phase angle

Where M is the measured bending moment, K is the rigid matrix acting on the rotating body,

U: adjustment amount of bearing

1 is a schematic diagram of a rotor simulator with a dial gauge.

2 is a schematic diagram showing the structure of a strain gauge to which the present invention is applied.

3 is a schematic front and side views of a rotating body with a strain gauge according to the present invention attached.

4 is a graph showing the distribution of strain according to the phase angle of the rotating body.

* Explanation of symbols for main parts of the drawings

10: strain gauge 12: gauge base

14: water resistant resistor 16: lead wire

20: Object to be measured 30: Rotating body

32: coupling

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on attached drawing.

The general structure of the strain gauge 10 is as shown in FIG. 2, the gauge base 12 of the electrical insulator, the thin water-resisting resistor 14 fixed with an adhesive on the base 12, and the water-resisting resistor 14 The gauge lead wire 16 is slightly thicker than the water-resist resistor 14 welded or soldered to the conductive material. The gauge base 12 is insulated from the receptor 14, and the resistor 14 is an element for detecting deformation of an object, and the gauge lead wire 16 connects the resistor 14 to a measurement instrument. Note is a metal wire.

After attaching the strain gauge 10 to the surface of the object to be measured 20, the strain generated in the object is transmitted to the water-receiving resistor 14 via the strain gauge base 12.

Accordingly, the water resistant resistor 14 brings about a change in the electric resistance value as the electric field changes. Therefore, when the test piece or structure is subjected to stress, the same resistance strain as the water-resistant resistor 14 adhered thereto will result in a change in the resistance value. Therefore, there is a constant relationship between strain and resistance change, and the value of strain can be found from the change in resistance value.

The greatest stress appears in the weakest part of the rotor of the power plant. That is, the coupling bolt and the coupling bolt for fixing and integrating it may be said to be the weakest part. Therefore, the method of adjusting the position of the bearing and indicating the angular deviation of the coupling is a key point of the present invention.

In FIG. 2, a bending moment is applied to the rotating body 30 by its own weight. When the strain gauge 10 described above is attached near the coupling 32 which is a weak part of the rotating body 30, the bending moment is applied. Based on the fact that the strain value obtained by acting is proportional to the bending moment of the rotating body 30, the bending moment value is obtained by the following equation.

here,

M: bending moment of the rotor shaft, E: Young's Modulus

: 축방향 스트레인,R: radius of rotor shaft, f: stress concentration coefficient

: Axial strain,

라 하였을 때, 굽힘 모멘트는 다음과 같이 얻을 수 있다.As shown in FIG. 2, the distance from the center of the coupling 32 to each gauge 10 is L, and the radius of the rotating shaft 30 to which the strain gauge 10 is attached is measured at R, the strain gauge 10. The strain value f, the stress concentration coefficient f of the rotating shaft with the strain gage 10 attached thereto,

The bending moment can be obtained as follows.

By deciding between adjustment of each bearing part using the bending moment obtained from the above equation and the stiffness matrix of the rotating body by the following equation, the loss of manpower and time can be greatly reduced.

here,

M: measured bending moment, K: rigid moment acting on the rotating body,

U: adjustment amount of bearing

The rigid matrix can be obtained from the following equation.

here,

X is a thermal matrix of forces acting on points on some elastic structure.

u: thermal matrix of displacements corresponding to each point

K: rigid matrix

Therefore, the present invention, by applying a strain gauge capable of high-precision measurement to the rotating body, it is possible to perform the maintenance of the rotating body quickly and quantitatively by using the dynamic relationship of the displacement amount, the bending moment, the bearing feed amount of the rotating body, the rotating body Even if it is not disassembled, it is a very essential invention to determine the feed amount of the bearing supporting the rotating body, which enables not only quick and convenient maintenance but also reduction of maintenance time and manpower, so that efficient power plant operation can be realized.

Claims (2)

In detecting and adjusting the shaft deformation amount of the rotating body coupled to the driving force generating means in multiple stages in the power generation equipment, a strain gauge is attached to each coupling part of the rotating body by the following equation. Detecting quantitative strain in the coupling portion; Detecting the bending moment value of the rotating body by the following equation using a proportional relationship between the strain value and the bending moment; The bending moment value maintenance method of a large rotating body using a strain gauge comprising the step of detecting the feed amount of the bearing by the following formula (3).

Where M is the bending moment of the rotor axis and E is the Young's Modulus. R: radius of rotor shaft, f: stress concentration coefficient

: Axial strain,

Where L is the distance from the center of the coupling to each gauge R: Radius of rotating shaft with strain gauge

: Strain value measured by strain gauge f: stress concentration coefficient of rotating shaft with strain gage

Phase angle

Where M is the measured bending moment, K is the rigid matrix acting on the rotating body, and U is the adjustment amount of the bearing. The method of claim 1, wherein the rigid matrix is calculated by the following equation.

Where M is the thermal matrix of forces acting on the points on any elastic structure. u: thermal matrix of displacements corresponding to each point K: rigid matrix

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