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Published on: February 5, 2017
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Experimental observations on unsafe zones in milling processes
Zoltan Dombovari1,2, Alex Iglesias2, Tamas G Molnar1
1Department of Applied Mechanics, Budapest University of Technology and Economics, Muegyetem rkp. 3, H1111 Budapest, Hungary.
Summary
Machining processes can enter unsafe zones, leading to chatter. This study identifies these bistable regions using nonlinear delay differential equations and experimental validation, improving cutting stability.
Area of Science:
- Mechanical Engineering
- Nonlinear Dynamics
- Control Theory
Background:
- Regenerative chatter in milling processes poses a significant challenge to machining stability.
- Unsafe zones in the parameter space can cause transitions between stable cutting and chatter.
- Understanding these zones is crucial for optimizing machining operations.
Purpose of the Study:
- To mathematically model and experimentally identify the unsafe (bistable) zones in milling processes.
- To investigate the role of unstable quasi-periodic oscillations in limiting stable cutting.
- To differentiate hysteresis loops from dynamic bifurcation phenomena.
Main Methods:
- Utilized a nonlinear extension of the semidiscretization method for mathematical modeling.
- Employed time-periodic nonlinear delay differential equations to represent the system.
- Conducted experimental validation including parameter variation and harmonic burst excitations.
Main Results:
- Identified parameter ranges corresponding to unsafe (bistable) zones.
- Accurately distinguished hysteresis loops from dynamic bifurcation.
- Experimental results confirmed the existence and extent of bistable parameter regions.
Conclusions:
- The study successfully identified and characterized unsafe zones in milling, crucial for preventing chatter.
- The developed methods provide a reliable approach for analyzing nonlinear dynamics in delay systems.
- Findings contribute to enhanced stability and predictability in machining operations.
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