Create Presentation
Download Presentation

Download Presentation
## Typical Steps of field Balancing

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -

**Balancing TrainingPart 1**Typical Steps of field Balancing Illustration with model 907 E-mail: sales@sendig.com, sendigbj@yahoo.com.cn Telephone: +8610 82895321Fax: +8610 82895320 http://www.sendig.com**An Overview of the Steps**• Collecting Machine data • Preparing Instrument & Sensor • Balancing really required ? • Balancing possible ? • Procedure of balancing**Step 1 - Collecting Machine data**• Understand the machine to be balanced as much as possible • Collect machine data • Take a photo of the machine**Sample: Machine to be balanced**• Impeller Parameter: • Diameter: 1400mm • Thickness: 500mm • Blade Number: 12 • Material:Fiberglass-Reinforced • Plastics • RPM: 1825 r/min • Bearing Model: ? • MotorParameter: • Power: 75kW • RPM: 1500 r/min • Others: • Belt transmission • Spring base • Manufacture: LG Bearing1 Bearing2 Impeller Motor**Step 2 - Preparing Instrument & Sensors**• Sendig-904/907 dual-channel data collector/analyser/balancer • A notebook computer • Sendig-MCM3 Analysis Software**Sensors & Cable connecting**Attach reflecting paper on shaft**Step 3 - Balancing really required?**• Use 904/907 to measure overall vibration values • Compare with ISO Standard 2) Use “Collector” to measure vibration 1) Switch to Analyzer**Horizontal VELOCITY is the critical parameter**6: Point: Motor-1-Side-2-X Alarm-mode: Displacement Freq-Range: 500Hz Sensor:4.6 ………………………… New Data Old Data ACC xxx / xxx m/s2 VEL 7.2 / 2.1 mm/s DISP 68 / 12 µm ENV xx / xx m/s2**Sample**Overall Value Measurement Acc. Vel. Disp. Envelope Peak ms-2 RMS mm/s P_P um RMS ms-2 Hor. 88.81 9.95 101.5 5.268 Ver. 55.89 5.554 38.77 7.362**Sample**Not Permissible, Balancing really required ! Measurement 9.95 mm/s**Step 4-1: Balancing possible?–“single peak spectrum”?**• Use 904/907 to measure vibration spectrum • Only “single peak spectrum” can go for balancing 2) Use “Collector” to measure vibration 1) Switch to Analyzer 3) Use “C-Spect” to see velocity spectrum**Sample of non-single peak spectrum- not suitable for**Balancing**Sample of non-single peak spectrum- Better change bearing**before balancing**Sample of single peak spectrum –**You can reduce the vibration by Balancing**Step 4-2: Balancing possible ?–“90o phase difference”?**• Use 904/907 to measure vibration phase difference between vertical and horizontal directions • Only “90o phase difference” can go for balancing 3) See if “90o phase difference” exist? 1) switch to balancer and use 2-planes balancing procedure 2) Page down to “Initial Measurement” to measure vibration phase at X & Y**Sample**Sample of “non-90o phase difference” – You cannot reduce the vibration by Balancing • Phase Measurement: • Velocity Amplitude Phase • Vertical: 9.416 320 • Horizontal: 3.08 116 Phase difference not 90o Since phase difference is not 90o nor closer to 90o ,this means the problem with the fan is something else other than unbalance.**Sample**Sample of nearly “90o phase difference” – You can reduce the vibration by Balancing • 1. Phase stable • 2. Phase Measurement: • Velocity Amplitude Phase • Vertical: 0.693 73 • Horizontal: 1.569 150 Phase difference is 77o ?**Balancing TrainingPart 2**Procedure of balancing**Different Kinds Of Imbalance**2-plane imbalance 1-plane imbalance**Characteristics Of Imbalance**1. The vibration frequency is mainly composed of RPM frequency. For each round the rotor turns, a vibration is occurred. 2. The wave is an approximate sine wave. 3. There is a difference of 90o between the vertical vibration phase and the horizontal one. 4. With RPM increasing, the vibration amplitude is increased**A**phase RPM amplitude Basic Principle Of 1 Plane Balancing 1 select a plane to fix trial mass and a point to measure, draw scale of phase and sign of 0o phase 2 measure initial vibration A0(phase and amplitude) 3 fix a trial mass Q on the plane, measure vibration A1 4 calculate influence coefficients: 5 calculate balancing mass P:****A1- A0 o A1 A0 K Q o P Illustration of 1 Plane Balancing • draw A0 &A1, calculate A1-A0 • measure the angle between A1-A0 and A0 • turn Q aalong the direction of , gain the correct location of balancing mass. • the weight of balancing mass is as the following :**Method of Influence Coefficients**• Method of influence coefficients is widely used, its step as the following (1 plane balancing as example): 1 measure initial vibration 2 fix a trial mass 3 measure the vibration with the trial mass 4 calculate the result of balancing mass**IF THE INFLUENCE COEFFICIENTS ARE KNOWN, THE STEP OF FIXING**TRIAL MASS ARE IGNORED The former steps are simplified as the following: 1) measure initial measurement 2) input influence coefficients 3) calculate the result of balancing mass**phase**Reflecting slice NOTICES DURING THE OPERATION • Confirm the dynamic balancing are needed according to spectrum and phase analysis. • Direction of phase: reverse to the direction of rotation**SELECTING PARAMETERS**• Measure displacement or velocity for middle or low speed machines • Measure velocity or acceleration for high speed machines**CONFIRM whether the trial is suitable**• The radius of loading trial mass is as same as loading the amended mass • The turning speed is steady**Tacho**sensor A Accelerometer 907 1-PLANE BALANCING Without influence coefficients**Operation Basic**• Prompt is displayed at the last line • Press ‘∧’ and ‘∨’ key to move the cursor up and down • Press Enter to select iterm • Press number keys to input digits • To other MENU, press PgDn or PgUp**Always make sure the “Setting” is correct before the**balancing Enter a digit, select 1 set of data from 10 Enter a digit, select plan number Change by “ENTER”, use displacement or velocity for most machines Input sensitivity (from accelerometer certificate)**INITIAL MEASUREMENT**• Press Enter to measure rotation speed first • Press Enter for a moment to measure vibration after rotation speed become steady • After phase and amplitude become steady, press Enter for a moment to end the measurement**TRIAL ESTIMATION**• Input the 4 parameters • When cursor on 6th line, press Enter to calculate trial range • Stop the machine, fix a trial mass according to the range**TRIAL MEASUREMENT**• Input phase and weight of the trial, confirm whether it will be removed afterward, restart the machine • Move cursor to 6th line, press Enter to measure rotation speed • When RPM steady, press Enter a moment to measure vibration • When amplitude and phase steady, press Enter for a moment to end the measurement**TRIAL RESULT**• See what the 6th line shows • If YES displayed, press Pg Dn to go on • If NO displayed, stop the machine, adjust trial mass, return to the early page of TRAIL MEASUREMENT, measure again**Cursor on 2nd line, press ENTER to calculate influence**coefficients The result is shown in 4th line Cursor on 2nd line, press Enter to calculate balancing mass The result is shown in 3rd line CALCULATION**Input the 2 angles**Display the results If nothing displayed at right side, change the order of the 2 angles and re-enter Pa2 Pa Pa1 Decomposing/Splitting**VERIFICATION**• Cursor on 2nd line, press Enter to measure rotation speed • When RPM steady, press Enter a moment to measure vibration • When amplitude and phase steady, press Enter for a moment to end the measurement • The last 2 lines displays the results**1-PLANE BALANCING**With influence coefficients, you do not need to add trial mass. You need only measure the initial vibration**SETTING PARAMETERS**Set “Yes” for the question of “Have influence Coefficient?”**INITIAL MEASUREMENT**• Press Enter to measure rotation speed • Press Enter for a moment to measure vibration after rotation speed become steady • When phase and amplitude become steady, press Enter for a moment to end the measurement**Move the cursor to the 4th line, input amplitude and angle**of coefficient Press Pg Dn to the next page INPUT COEFFICIENTS**Pa2**Pa Pa1 Calculation, Decomposition & verification • calculate balancing mass • Decomposition and verification are the same as illustrated earlier**2-PLANES BALANCING Without influence coefficients**The main difference than 1-plane: • Need to add trial mass one after another at the 1st plane and 2nd plane • Need to use 2 vibration sensors**Sensors & Cable connecting**Attach reflecting paper on shaft**INITIAL MEASUREMENT & TRIAL ESTIMATION**Get 2 lines of reading here**TRIAL I MEASUREMENT**• Input phase and weight of the trial on plane 1, decide if it will be removed, restart the machine**TRIAL II MEASUREMENT**• Input phase and weight of the trial on plane 2, decide if it will be removed, restart the machine**Pa2**Pb2 Pa Pb Pb1 Pa1 Calculation, Decomposition & Verification • calculate balancing mass • Decomposition and verification are the same as illustrated earlier