Robot dynamics for metal cutting processes
PROBLEM DESCRIPTION
In recent years, there has been renewed interest in using robots for metal cutting processes. In high-precision manufacturing, Computerized Numerical Control (CNC) machine tools are the standard for metal cutting processes because of their high stiffness and limited degrees of freedom, which allow for precise motion control. However, CNC machine tools are very expensive, difficult to relocate, and lack the flexibility to machine complex parts. On the other hand, robots are more affordable, easier to move, and offer greater flexibility.
Despite these advantages, robots still have several shortcomings: propagation of dimensional error between links; low-stiffness at the joints; joint backlash; and angular positioning errors at the joints due to the absence of a second encoder. These challenges have motivated various lines of research, in particular, to better understand the robot dynamics during metal cutting operations.
Modeling robot dynamics and vibrations is a difficult task due to the complex structure of links and joints in robots, as well as the constant variation of modal parameters. Engineers seek to understand how robotic arms respond to external and cutting forces, as these forces can generate unwanted vibrations that deteriorate the quality of the surface finish. By gaining deeper insights into these dynamics, researchers aim to develop strategies to suppress such vibrations and enhance robotic machining performance.
OBJECTIVES / EXPECTED OUTCOMES
To model the main factors affecting robot dynamics during metal cutting and provide recommendations to prevent instabilities.
Participants are expected to propose models for the metal cutting dynamics, develop theoretical approaches, perform numerical simulations, explore different stability criteria, discuss strategies to mitigate unwanted vibrations, and summarize their findings.
REFERENCES
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Altintas, Y. (2012). Manufacturing automation: Metal cutting mechanics, machine tool vibrations, and CNC design (2nd ed.). Cambridge University Press.
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Munoa, J., Beudaert, X., Dombovari, Z., et al. (2016). Chatter suppression techniques in metal cutting. CIRP Ann. - Manuf. Technol., 65(2), 785–808. https://doi.org/10.1016/j.cirp.2016.06.004
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Insperger, T., & Stépán, G. (2011). Semi-Discretization for time-delay systems: stability and engineering applications. Springer.
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Liu, Z., Deng, Z., Yi, L., et al. (2024). A review of research on robot machining chatter. J. Adv. Manuf. Technol., 135, 49–79. https://doi.org/10.1007/s00170-024-14533-4