Extruder developments | machinery feature The latest developments in extruder technology include more
energy-effi cient pipe production, better control of pipe thickness and the incorporation of glass fi bres. Lou Reade reports
Production improvement: extruder developments
Extrusion is a well-established industry process, and can be considered a mature technology. However, basic and fundamental research continue to improve the process – in terms of product quality, for example. Chinese researchers have devised a control scheme
that can improve the quality of products made on single screw extruders. The scheme has been implemented in a controller and tested on a pilot-scale line. “It is a challenging task to achieve quality control,”
said the researchers, in a paper presented at the recent Antec conference in the USA. “Our overall objective is to control quality accuracy.” The researchers, from Kunda Mould of Shenzhen, Nanjing University and Hong Kong University, said that direct control of process parameters such as pressure and temperature is common, but direct control of end product quality – such as pipe diameter – is less common. In an experiment, a quality accuracy control loop was
www.pipeandprofile.com
devised with three inputs – the set-points of melt pressure, barrel temperature and haul-off speed – and just one output (pipe diameter). As it is diffi cult to measure haul-off speed directly, the voltage of tractor speed was measured instead. Each three input parameters were then correlated
against the single output, by reaching a steady state and changing one input parameter at a time. The research- ers found that melt pressure and haul-off speed had a far greater effect on quality than barrel temperature. “In industry, the high demand on extrusion effi ciency
determines that the melt pressure must be set as large as possible, so here the haul-off speed is chosen as the manipulated variable for quality accuracy control,” said the researchers. Ultimately, the results showed good performance on an actual extrusion line – showing the process was able to guarantee good product quality, said the researchers.
July/August 2016 | PIPE & PROFILE EXTRUSION 13 Amut’s
co-extruded pipe is used for hot water piping and
soundproofi ng drainage piping
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58
