Vibration Abatement in a Turning Process Via Application of an Actively Controlled Tool Holder
 
 

Dongming Liu | PhD | 1998

ABSTRACT:

The vibration of the cutting tool in a turning process is known to have detrimental effects on the surface finish of machined parts. For a given cutting condition, better surface finish can be achieved by suppressing the vibration. Passive vibration absorbers are difficult to use for cutting tool vibration abatement due to the random nature of the vibration. In this dissertation, an active system for cutting tool vibration abatement and surface finish enhancement in a turning process is presented. The system is a specially designed tool holder that can maneuver the cutting tool position with a magnetostrictive actuator during cutting. The cutting tool vibration can be reduced by applying appropriate control signals to the magnetostrictive actuator.

A model that accounts for both the dynamic response of the cutting process and the magnetostrictively actuated tool holder was developed. Based on the model, controllers were synthesized using both H2 optimal control and m-synthesis methods. The nonlinearity of the magnetostrictive actuator, the nonlinearity of the cutting force system, and the regeneration effect were modeled as structured uncertainties in the m-synthesis design. The controllers were implemented for the tool holder digitally by a DSP.

The effectiveness of the magnetostrictively actuated tool holder in vibration abatement and surface finish improvement was examined via experiments. Impulse response tests showed that the actively controlled tool holder effectively reduced the vibration of the cutting tool. Cutting experiments were also conducted using the tool holder and experimentally obtained surface profiles were compared to surface profiles obtained without the vibration control. It is shown that the system can improve the surface texture generated by the turning process.

If you have any comments or suggestions please e-mail jwsuther@mtu.edu.