Field Balancing 의 절차와 방법 Field Balancing 의 절차와 방법

최 성 필 박사㈜터보링크

한국수자원공사 교육 자료 (2005. 9. 8)

2

Balancing 이란 ?

ISO 1925

회전체의 질량 분포를 조사하고 필요하다면 저널의 진동과 베어링의 작용력들이 운전속도에 대응하는 주파수에서 특정한 한계 내에 있도록 조정하는 절차

ISO 1925

회전체의 질량 분포를 조사하고 필요하다면 저널의 진동과 베어링의 작용력들이 운전속도에 대응하는 주파수에서 특정한 한계 내에 있도록 조정하는 절차

3

Balancing Machine

Shop Balancing Field Balancing

Low Speed Balancing Machine

Soft Mount Type

Hard Mount Type

High Speed Balancing Machine

Soft Mount Type

Hard Mount Type

Balancing

4

불평형 원인

Manufacturing ( 제작 ) 소재 밀도 (material density) 의 불균일 가공 정밀도 비대칭 형상 Etc.

Assembly ( 조립 ) 조립 공차

Operation 부식 이물질 부착

5

회전체 분류 (ISO)

Rigid Rotor( 강성 회전체 ) 양면 밸런싱으로 수정가능한 로터로써 , 로터의 최대 운전속도까지

승속하여도 잔류 불평형량이 변하지 않는 로터 .

Flexible Rotor( 탄성 회전체 ) Rigid Rotor 를 제외한 모든 로터

Rigid Rotor Flexible Rotor

Speed (N)

Am

plit

ud

e

1st Critical Speed for Flexible Mode

6

밸런싱 용어

Unbalance Unit: g·mm

U = m x r

7

밸런싱 용어

Unbalance Static Unbalance

Couple Unbalance

Dynamic Unbalance

F

Cg

e

F1

F2

Cg

F1

F2

StaticUnbalance

CoupleUnbalance

DynamicUnbalance

Principle inertia axis

Shaft axis

CgPrinciple inertia axis

Shaft axis

8

허용잔류불평형

Balancing Grade for Rigid Rotor ISO 1940

API

max 6350 [g mm]

Journal static load [kg]

Max. speed [rpm]

WU

NW

N

9

허용잔류불평형

Balancing Grade for Rigid Rotor ISO 1940

10

허용잔류불평형

Example for Turbine Rotor Rotor Weight 400 kg

Max. Speed 10,000 rpm

ISO 1940 G2.5

API

max

2006350

10000

= 127.0 [g mm]

kgU

rpm

max 2.4 400

= 960.0 [g mm]

U m kg

11

밸런싱 방법

Graphic Method: Single Plane Vector method

4 Run method

Static couple method

Influence Coefficient Method: Multi Plane Standard influence coefficient method

Least square influence coefficient method

Modal Method Critical speed mode shape, Modal influence balancing coefficients

12

밸런싱 방법

Phase Angle

High Spot

Phase Angle

High Spot

Phase Reference Pickup

Vibration PickupPhase Angle (θ)

T

t

360t

T

Heavy Spot Angle (θ)

Heavy Spot

13

밸런싱 방법

Phase Angle

High Spot

+ Phase Angle

High Spot

Phase Reference Pickup

Vibration Pickup

Heavy Spot Angle (θ)

T

t

360t

T - 90˚

- 90˚

Phase Angle (θ)

360t

T

Heavy Spot

14

밸런싱 방법 (Single plane) Vector Method

Zo : 초기진동 벡터

ZT : 시험질량을 취부한 진동벡터

= Zo+ T.W

Zo

ZT

T.W

ZT - ZO

C.WZo – ZT : 시험질량만의 효과

T.W : 시험질량C.W : 수정질량

15

밸런싱 방법 (Single plane)

Vector Method

0

0

0

0

0

T T

T

T

a U

a U

a

Z

Z U

U

Z U

U a

a

0T

T

Z

Ua

Z

00

T

T

a UU

Z Z

0

T

Z

Z

0

( )T TU W

U

a

초기 진동 벡터

시험 질량을 취부한 진동 벡터

초기 불평형량

시험 질량을 취부한 불평형량

영향계수

16

밸런싱 방법 (Single plane)

Vector Method

0 25 95Z

30 175TZ

35 220TW

10 180Tm g

10 : 35 : 25

10 25

35

7.14

C

C

c

g m m m

g mm

m

g m

0 25 95Z

30 175TZ 35 220TW

35 220TW

10 180Tm g

7.14 55Cm g 235 o

0Z

0

0 0 0 0 00

( )

( ) 180 (95 180 ) 220 235

c T T

c T T

m m Z W

m m Z W

7.14 235Cm g

17

밸런싱 방법 (Two plane)

Pick Up Pick Up

Phase

Plane 2 Plane 1

F N

18

밸런싱 방법 (Two plane)

180o0o

90o

360o

180o

N

Plane 1

Initial vibration

0o

90o

360o

F

Plane 2

Rotation

Phase

19

밸런싱 방법 (Two plane)

90o

360o

180o

N2

Plane 1

Trial weight – plane 1

0o

90o

360o

180o

F

Plane 2

A

F2

N

0o

Rotation

Phase

20

밸런싱 방법 (Two plane)

90o

360o

180o

Plane 1

Trial weight – plane 2

0o

90o

360o

180o

F

Plane 2

F3

N3 N

0o

Rotation

Phase

21

밸런싱 방법 (Two plane)

90o

360o

180o

- N

Plane 1

Trial weight – plane 2

0o

90o

360o

180o

F

Plane 2

N

- F

A

A + (B) = - N B + (A) = - F

0o

Rotation

Phase

22

0 deg

90

180

270

o

No.1 end

Static component

No. 1 end No. 2 ends

N0. 1 dynamic component

N0. 2 dynamic component

A

C

BNo.2 endN0. 2

dynamic component

N0. 1 dynamic component

B

A

밸런싱 방법

Static/Couple Method

23

밸런싱 방법

Modal Balancing Mode Shape

Modal Distribution

24

밸런싱 프로그램

Input Module

25

밸런싱 프로그램

Input Module

26

밸런싱 프로그램

Input Module

27

밸런싱 프로그램

Output Module

28

회전체 분류 (ISO)

Class 1 : Rigid Rotor : These rotors may be balanced in any two

arbitrary axial planes and will remain in balance throughout the

operating speed range

(ex., Gear wheel etc.)

Class 2 : Quasi-flexible Rotors : These rotors are not perfectly rigid but

may be adequately balanced in a low-speed balancing machine and

will maintain smooth operation throughout the speed range

(ex., Shaft with grinding wheel, Jet-engine compressor rotor, Printing-

press roller, Computer memory drum, Five-stage centrifugal pump,

Multistage pump impeller, Impeller pump, Steam turbine rotor)

Single and two plane constant-speed balancing is usually adequate

29

회전체 분류 (ISO)

Class 3 : Flexible Rotors : These rotors cannot be balanced in a

low-speed balancing machine and require one or more high-speed

trim plane corrections

( ex : Generator rotor etc.)

Class 4 : Flexible-attachment Rotors : These rotors have

components within themselves or flexibly attached

(ex : Rotor with centrifugal switch)

Class 5 : Single-speed Flexible Rotors : These rotors could be class

3 flexible rotors but are balanced for operation at one speed only

(ex : High-speed motor)

A least-squared-error influence coefficient

or combined modal technique is preferred