Innovative technology for quiet punching
The evolution of production towards a constant increase in performance has been associated with an increase in the machines' operational speed together with a reduction in the weight of their mobile components. As a result of these two tendencies, the problem of vibration and noise pollution in industry is more and more widespread. Recently acquired knowledge of the damping and noise-absorbing properties of different materials has opened the way to new possibilities through the application of passive and active noise control techniques. Though they provide an adequate solution for the reduction of noise emissions at low frequencies, passive methods such as the use of noise-absorbing materials often lead to an unacceptable increase in mass and volume. The NOISELESS project therefore proposed an alternative method to control repetitive impact noise produced by punch press machines as close to the source as possible. In Active structural acoustic control (ASAC), minimisation of noise emissions is achieved by modifying the machine's vibrations using dampers directly attached to the vibrating components. More specifically, project partner, Cedrat Technologies in France focused on the use of piezoelectric dampers for vibration control. The key benefits of using piezoelectric dampers instead of other control actuators are their low weight and volume. Furthermore, when combined with high power linear amplifiers, multiple dampers can be incorporated into the machine's structure. By multiplying the available electrical power of standard power supplies, the high power amplifier can provide the voltage levels needed to drive the piezoelectric dampers. They also allow for the fine tuning of the control system and ultimately for the control of noise over a wide frequency bandwidth. The Cedrat Technologies' experience in developing smart control systems has made possible the wider use of piezoelectric dampers for reducing noise produced by industrial activities.
