dynamic simulation of boring process
DESCRIPTION
Dynamic Simulation of Boring Process. B. Moetakef-Imani , N.Z.Yussefian 10 July 2009 Aaron Boyd October 28, 2009. FUNCTION. To simulated the dynamic response in boring processes To predict vibrations in the operation. Why Important?. - PowerPoint PPT PresentationTRANSCRIPT
Dynamic Simulation of Boring ProcessB. Moetakef-Imani , N.Z.Yussefian
10 July 2009
Aaron BoydOctober 28, 2009
FUNCTIONTo simulated the dynamic response in boring
processesTo predict vibrations in the operation
Why Important?Tool vibrations result in reduced tool life,
poor surface finish and may also introduce chatter.
Predicting these vibrations allow the operator to know under what conditions the operation will be most efficient.
References
Boring ProcessProcess of enlarging a previously drilled holeHigh Precision and good surface finish
Vibrations3 types
Free/Transient: most common, caused by initial engagement between tool and part, will vibrate naturally until damped
Forced: applied to tool structure, commonly caused by multi-insert tools and run-out of the tool tip; also caused by other machinery; if it hits natural frequency, resonance can occur
Self-Excited: caused when tool cuts, chatter occurs when parameters (DOC, feed rate, etc.) are incorrect; can cause part deflection
Chatter Loop
Equations of MotionEuler-Bernoulli Beam Differential Equation
Natural Frequency
Beam Deflection
Kinematics of Chip-Load FormationCutting Edge Equations
B-Spline Parametric Curves
Instantaneous Chip Load
Cutting Edge Contact Length
Dynamic Simulation
Tests
Test A: • Undergoes transient vibrations, but stabilizes• Chatter free• Vibrates at constant amplitude
Test B: • Process that doesn’t stabilize• Chatter present
Results (test A)Simulated peak frequency is 672 Hz
compared to a measured value of 594 Hz – 12.94% error.
Deviation stems from overestimation by the Euler-Bernoulli beam equation
For x, y and z measurements – 9%, 2%, and 12% error respectively
Results (test B)• simulation shows chatter• chattering freq. at 573 Hz• random oscillation• variation increases• tool plunges into workpiece• makes prediction almost impossible• However, still useful to predict chatter
ConclusionsMore accurate than previous modelsPrevious models only predicted stability
region, while this model predicts dynamic region – very useful
In chatter-free operation, the simulation predicts within +/- 15% of the actual measured value
It is a valid simulation for both smoothing and roughing
Predicts chatter so operators can avoid it completely
Uses all influential parameters
Impacted IndustriesAutomotive IndustryFirearmsPretty much any industry that involves
drilling holes
Useful?There seemed to be a lack of some vital
information, but this information could be found by referring to the references (the refer to them often).
However, the results will allow operators to know what to expect from their operations. They will be able to know what frequencies to expect and will be able to prevent chatter.
Overall, it’s a rather useful paper.