Hannover, Germany —Switching to a PC-based control system has increased production performance of Continental Mould & Machine Factory's tire building machine. Similar to a lathe with head and tail stock sections, the KM 92 tire building machine brings together a number of components to form the new tire carcass. Various conveyor belts supply the materials to a drum mounted on the driving box of the head stock end, while the tail stock contains a sliding rotary drive.
Previously, control of the tire building machine and material feed system was carried out using programmable logic controllers. Achieving the high quality demanded by Continental with this type of control, however, required a long setup time. The control system now employed is based on an industrial PC configuration from Beckhoff Industrie Elektronik. The Pentium PC operates at 200 MHz and runs Beckhoff's TwinCat real-time expansion for Windows NT. This replaces the former PLC technology with its separate motion control and PC for visual displays.
TwinCat maintains independent control of the tire builder's nineteen axes and encoders. It provides both a numerical control and a PLC function with the NC function offering an axis cycle time of two msec and the PLC cycle giving six msec. The Lightbus optical fiber bus handles communications between the PC and the sensor and actuator input/output devices.
Software includes a library of functions for motion control and communications. Remote connection to higher-level systems using the TCP/IP Internet protocol allows diagnostics and programming via standard PCs.
The industrial PC contains the positioning algorithms as function blocks for controlling the KM 92. Once the tire beads have been inserted manually into the machine, the PC centers them and the first and second plies are fed automatically. Then the drum expands to set the beads. The process continues with the formation of the rim loop and the application and rolling of the sidewalls. The drum collapses to remove the finished tire.
Depending on tire structure, the whole cycle takes 20 to 40 sec. Previously, special hardware was needed involving many interfaces to the subsystem—all of which increased cost. Setup on the old system also involved the trimming of numerous analog settings, often using an oscilloscope.
Frank Lubitz, Conti FMF's Design Manager, adds that "a shortened machine cycle is not the only benefit. An important advantage is the reduction in the setup time in commissioning the machine. The PC-based control system has enabled us to reduce setup time by 50%."
Contact Beckhoff Automation LLC; 12204 Nicollet Ave. S., Minneapolis, MN, 55337; Tel: (612) 890-0000; Fax: (612) 890-2888; firstname.lastname@example.org .