Electrostatic behaviour of web/roller systems

Au, Andrew Man Kit (1981) Electrostatic behaviour of web/roller systems. University of Southampton, Doctoral Thesis.

Abstract

The theoretical predictions of web/roller charging system reported by Horvath and Herta in 1975 showed very interesting behaviour in terms of web surface charge density variations. The aim of this investigation primarily is to extend these threoretical predictions and to verify experimentally the charging and discharging behaviour of multiple contact systems. Web behaviour has been investigated for different roller diameter, web surface conductivity, velocity and tension. In order to study the web and roller systems, a computer model was set up to simulate a web moving over a rotating earthed roller. This enabled a prediction of the charging behaviour of the system and how the charge density and electric field distribution along the web surface varied for different web conditions. Experimental investigations were carried out using single roller contact initially and later, multiple roller contact were evaluated. In a single roller contact system, the onset of charge retention showed remarkably good correspondence with the theoretical predictions. Different discharge patterns were observed between web and roller using sari- conducting and insulating webs (10-11 S and 11-15 S). A relationship ofthe sparking onset of the system was found to be related to the web surface conductivity, velocity and tension. In a multiple roller contact system, the charging characteristics were investigated, and the effects of the roller diameter, web conductivity, velocity and tension were identified. In addition, discharge observations at the incoming and departing positions revealed two types of discharges - surface and gap discharges. Computation techniques were used for data-processing the charging signal, and an image intensifier was used for discharge observations.

This record has no associated files available for download.

Contributors

Download statistics