A new forming block design, high internal cooling, and engineering thermoplastics on wear parts help increase output in the UC100/81iV corrugator. It produces structured wall pipe from 10 mm inner diameter to 125 mm outer diameter. Throughput is 580 kg/hr for PVC and 650 kg/hr for HDPE.
Forming blocks, cast in an aluminum alloy with a ceramic coating for good release properties, allow chilled water (4 to 8C) from a feed line along the bottom guide track to circulate through channels in each block. The water runs from one block side to the other, transferring heat into the return channels. Instead of a cooling medium being pumped through cooling channels as in traditional systems, it is sucked by means of vacuum pumps, says Ralf Mittermaller, general sales manager for Unicor. This facilitates better cooling, he says. For double wall pipes, additional cooling on the inside of the pipe comes from a chilled mandrel attached to the die tool.
Up to 81 pairs of forming blocks travel through the forming tunnel on a self-lubricating nylon guide. Each guide block lies on top of the guide, independent of the others. This allows operators to swiftly lift a block off the track without tools during dimension changes. Each block takes 10 seconds to remove and replace. All mold blocks are the same height, so no additional adjustment of the corrugator is needed. Cooling water reportedly does not escape from the system during changes because it circulates under low vacuum pressure.
Forming blocks are driven by upper and lower gear wheels powered by servocontrolled a-c motors. Another drive on the return channel reduces mechanical stress on the outer curves. Since the carrier form and mold block are made of the same material and are one unit, thermal expansion problems between the block and base, which can require special sealings, don't occur, Mittermaller says. Unicor GmbH Rahn Plastmaschinen, Hassfurt, Germany; +49 9521 690111; www.unicor.com