Cincinnati presents complete line concept for glass fiber reinforced 3-layer pipes made of PP-R
3-layer pipes made of PP-R with a glass fiber reinforced middle layer are an interesting alternative to conventional heating and sanitary pipes for hot and cold water transport in buildings. The Viennese machine manufacturer Cincinnati Extrusion GmbH offers a tailor-made engineering solution to meet the special requirements of the task of producing them.
The pipes consist of two outer PP random polymer layers and a middle layer made of PP homopolymer filled with a 10 to 20% weight component of short glass fiber. The normal distribution of layer thicknesses in the three-layer pipes varies between 25/50/25 % and 33/33/33 %. The main advantage of these pipes, an increase in stability and e-module, is achieved by glass fiber reinforcement. In contrast to conventional pipes, the glass fiber content reduces the lengthwise expansion of the pipes especially in hot water transport and consequently lessens their deflection. This again allows the installation of heating and sanitary pipes with larger intervals between fixtures, which considerably facilitates their laying.
For the production of these pipes, Cincinnati Extrusion recommends an extruder combination consisting of two Talos single-screw extruders. While the extruder for the inner and outer layers is equipped with a 30 D processing unit including a grooved feed section, the extruder for the middle layer has a length of only 25 D and a smooth processing unit with special anti-wear protection for processing PP with glass fiber content. Like all machines from the Viennese manufacturer, both extruders come with maintenance-free AC motors and screw geometries perfectly tailored to the requirements of this application. They are also synchronized by means of a microprocessor control system and consequently extremely easy to operate.
The die, an IRIS 25-3 coex triple spiral mandrel die, is suitable for all pipe dimensions from 16 to 250 mm and can be adapted very easily to different layer thickness distributions. It belongs to the proven series of IRIS pipe dies featuring optimally designed spiral distribution channel geometries and flow channels. Apart from their fast and easy cleaning properties, IRIS dies stand out above all by their low pressure build-up, low shearing stress and short dwell times. In this way, they ensure optimal melt distribution and narrow thickness tolerances. A special gloss heating element in the die guarantees an absolutely smooth inner surface for the pipe.
One special feature of the line concept from Cincinnati Extrusion is the downstream equipment for pipes up to 63 mm in diameter. While pipes up to 32 mm are normally cooled in a full bath, spray cooling is recommended for larger pipe diameters. To cover both variants with a single downstream unit, the machine manufacturer has designed a variable water cooling bath, which, depending on the application, can be switched over from spray bath cooling to full bath cooling without any effort involved in the changeover. Via a belt haul-off, the pipes are passed on to the cutting saw at a speed of 25 m/min and finally to the tilting table. For pipes with diameters between 32 and 250 mm, the line is equipped for speeds up to 15 m/min and comes with a standard spray cooling unit, a caterpillar haul-off, cutting saw and tilting table.
