A new non-contact C-Check system has been introduced designed for in-line conductivity measurement of chimney strips directly after the extrusion process. Available from Germany machinery firm KraussMaffei Berstorff, it enables in-process detection of material defects and transmits a warning signal to the operator and the control system. Recipe-controlled positioning combined with automatic height adjustment of the test system ensures uncompromising flexibility and excellent precision.
“To reduce the rolling resistance of passenger car and truck tyres, tyre producers often replace carbon black by silica in their rubber compounds used in tread production. Silica is characterized by high electric resistance and acts as an isolator,” says Dr. Gerard Nijman, Head of R&D and Rubber Processing Technology at KraussMaffei Berstorff. “For this reason, a continuous conductive strip (chimney) on carbon black basis is required as additional component in the tread profile to eliminate the electrostatic charge from the tyre. The chimney strip has a width of a few millimeters only and avoids electrostatic charging by the contact with the road surface.”
The second development for in-line process monitoring is designed to detect instantly any metering errors in order to reduce production scrap and enhance line efficiency. This in-line measuring system is based on color measurement: light is projected into the melt, reflected and then detected by a high-resolution glass fiber sensor. Upon comparison with the previously defined setpoint, any deviation in terms of brightness or color is instantly recognized and indicated. It goes without saying that the color measuring system can be integrated into the overall line control.
The C-Check system checks the chimney conductivity in-line at variable production speeds. It is designed for non-contact measurement of the electric conductivity between the outside and inside of the tread. The electrode with flexible position charges the strip that is placed on an earthed conveying system. The fully functional chimney strip eliminates the electrostatic charge via an additional grounded electrode. If the electric resistance exceeds the preset value, a signal is transmitted to the operator and recorded by the control system.
The measurement is performed in real time. It can be displayed on a local control panel and additionally transmitted via an appropriate interface. The exceptional functionality of the C-Check system is simply unique on the market. Thanks to the non-contact monitoring principle, there are no restrictions as far as the use of marking systems is concerned. The system can also be integrated into existing lines.
“We presented the new system for the first time on the occasion of the TireExpo where its simple operation and exceptional measuring precision met with great acclaim among trade visitors,” says Gerard Nijman.