Vibration Analysis Predictive Technologies PdM Techniques.
-
Upload
diane-lester -
Category
Documents
-
view
229 -
download
2
Transcript of Vibration Analysis Predictive Technologies PdM Techniques.
Vibration Analysis
Predictive Technologies
PdM Techniques
Richard HenryVibration and Alignment Specialist
VibrAlign, Inc.
Cardan Shaft Misalignment Identification
Cardan shafts (shafts with universal joints) are often neglected.
Cardan Shaft Alignment
Cardan Shaft Alignment Technical principle
Relative angular velocity
Cardan Shaft Alignment Technical principle
Degree of irregularity
Cardan Shaft Alignment Technical principle
Homokinetic operation is reached by a second cardan joint
Cardan Shaft Alignment Technical principle
Benefits of cardan shaft alignmentVibrations
Vibrations is transfered to gear box and motor
High wrap angle
Benefits of cardan shaft alignment Why is it important?
• Vital part in drives for process machines, breakage of cardan shafts causes down time.
• Badly aligned cardan shafts set limitation in production capacity and product quality.
• Stands for a considerable cost when repair is needed or a breakdown occurs.
• Badly aligned cardan shafts reduces lifetime in gearboxes and motors.
• Break down of a cardan shaft in running condition could be extremly dangerous.
Cardan Shaft Misalignment Typical vibration symptoms
• Unbalance of the drive line (high 1X).
Drive line will not have the same center of rotation as the U-Joints.
• High amplitude 2X and 4X driveline speed.
• Torsional oscilliation
Cardan shaft alignment Measurement principle
Angular error
Cardan shaft alignment Tolerances
No standard, but…
• Angular error within 0.25 mils/in
• Offset within specifications.
Cardan shaft alignment Procedure - Coning
Coning -axis of rotation
Cardan shaft alignmentCase story
Background:
A customer contracted VibrAlign to identify the source of an on-going U-Joint and Gearbox DE Bearing failure problem.
Reasons for the in depth analysis were:
Cardan shaft alignmentCase story
• High vibration level.• Axial bearing had to be changed every 8-10 week.
Cost about $1500 every time.• Reduced production for about 10 hours at a cost about
$1000/hour for each failure.• Necessary to have bearings in stock.• Problem with thermal expansion (high bearing
temps).• No method to perform the alignment.
Cardan shaft alignmentCase story
Vibralign arrived on site and collected initial vibration data. Vibration symptoms indicated severe cardan shaft misalignment.
Using a set of brackets specially designed to measure cardan shaft misalignment, we were able to identify an angular error of approximately 1.5 mils/inch of angularity in both the horizontal and vertical planes.
Cardan shaft alignmentCase story
Vertical angular adjustments were made to the motor by shimming and the motor was repositioned horizontally.
The following spectra and waveforms clearly show an improvement to the operation of this machine.
Gearbox DE Vertical
Gearbox DE Vertical
Gearbox DE Horizontal
Gearbox DE Horizontal
Gearbox DE Axial
Gearbox DE Axial
Cardan shaft alignmentCase story
Results:
• Significant decreasing vibration level.
• The alignment was performed in February -98 and no change of bearing in the gearbox has been done since then.
• Increased production capacity.