| Every Kunstoff exhibition introduces some new developments in the plastics processing equipment segment. K 2004, with several new developments in extrusion technology, was no exception. Some of the newer developments exhibited at K 2004 are:
Two unusual dies with rotating core elements, said to make tougher film for down-gauging were the highlights for extrusion blown film systems. These blown film dies have unusual rotating cores, a technique commonly used in pipe and tubing dies to prevent weld lines, but not previously used in blown film. The core of the die rotates in contact with the melt surface, orienting it and making thinner film with 10% better elongation at break and modestly better tear properties.
DR-Pack also developed an adjustable IBC system, which opens like an umbrella with air coming out of the spokes tangentially onto the inside of the bubble. The air ring outside the bubble blows tangentially in the opposite direction, keeping the bubble more stable than a conventional air ring and IBC.
The second revolving die element at the show was a "rotating distributor" developed by the University of Paderborn in Germany. This is a slow turning disk driven by the melt at only about 3 rpm, just enough to put a slight orientation into the melt, and to prevent weld lines. This has been scaled upto 100 mm diameter for extruding 160 lb/hr of blown film in tests in the University's laboratory last year. It will also be tested for pipe extrusion.
The show was packed with new equipment for pipe and profile, including extruders redesigned for higher outputs and/or lower cost, plus new ways to adjust die and calibrator diameters or switch dies and calibrators more quickly.
PE and PVC pipe extruders are raising outputs. Maillefer SA in Switzerland showed a more powerful 60 mm single-screw extruder for PE pipe. Model MEH 60-30D with 30:1 L/D has a more powerful 145 hp AC motor capable of up to 350kgs/hr of PE pipe vs. 200kgs/hr for Maillefer's previous 60 mm extruder with only a 75 kw DC motor. It also has a quick-change die on a swing arm.
Single-screw extruders for polyolefin pipe are getting longer to provide higher throughput. Rollepaal B.V. from the Netherlands showed a new 120 mm, 55:1 L/D single-screw for compounding and extruding highly filled polyolefin pipe. Its output reportedly competes with that of a co rotating twin-screw. It can add up to 60% filler with two side feeders and hold 6000 kg/cm2 die pressure for direct pipe extrusion.
Krauss-Maffei's new KME extruder for polyolefin pipe has 36:1 L/D compared with 30:1 for its predecessor. Greater length plus a water-cooled inlet and low-temperature screw give the KME 30% higher output. Krauss-Maffei has built a 75 mm prototype that runs up to 1580 lb/hr. The KME comes in a vented version for processing PS, PC and PMMA.
This K show was the first to see significant numbers of new-generation synchronous torque motors on extruders. These developments were described in our earlier article Quiet motors arrive with a big bang |
