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Dynamic Simulation of Boring Process

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?.

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Dynamic Simulation of Boring Process

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  1. Dynamic Simulation of Boring Process B. Moetakef-Imani , N.Z.Yussefian 10 July 2009 Aaron Boyd October 28, 2009

  2. FUNCTION • To simulated the dynamic response in boring processes • To predict vibrations in the operation

  3. 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.

  4. References

  5. Boring Process • Process of enlarging a previously drilled hole • High Precision and good surface finish

  6. Vibrations • 3 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

  7. Chatter Loop

  8. Equations of Motion Euler-Bernoulli Beam Differential Equation Beam Deflection Natural Frequency

  9. Kinematics of Chip-Load Formation Cutting Edge Equations B-Spline Parametric Curves

  10. Instantaneous Chip Load Cutting Edge Contact Length

  11. Dynamic Simulation

  12. Tests • Test A: • Undergoes transient vibrations, but stabilizes • Chatter free • Vibrates at constant amplitude • Test B: • Process that doesn’t stabilize • Chatter present

  13. 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

  14. 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

  15. Conclusions • More accurate than previous models • Previous 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

  16. Impacted Industries • Automotive Industry • Firearms • Pretty much any industry that involves drilling holes

  17. 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.

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