Tunable and Transferrable Bar Feeder Damping Design for Advanced Manufacturing

The economical production of high-value, low-volume, machined components is an important subtopic of advanced manufacturing. Bar feeders, a well-established technology for adding a high degree of automation to CNC turning centers by feeding 12′ lengths of stock through the machine spindle, have limitations in this realm. They rely on supporting the entire length of the stock in a continuous fluid bearing in order to suppress potential vibrations. Although this results in excellent vibration suppression, long tooling changeovers make them impractical for small batch sizes. Additionally, the expense of the tooling can render them cost-prohibitive. Thus a bar feeder technology is desired that provides comparable vibration suppression for a wide variety of stock sizes without the need for size-specific tooling changes. In this, a movable point support having tunable viscoelastic properties is studied for controlling the vibration of varying lengths of bar stock in a given speed range. The transverse vibration of mounted bar stock is modeled as a Bernoulli-Euler beam. The effects of the support position, viscoelastic model, and their associated parameters on the resonant frequencies, damping ratios, and vibration response of the bar stock are studied. Such a study will be instrumental in developing passive/active vibration control strategies for future bar feeders.