MACHINERY | DIE DEVELOPMENTS
Right: Conextru’s new cross-heads can coat both steel and plastic pipes
production mode much faster, which saves time for further operations.”
Self-centring tube dies are available for single- or multi-layer tubes – with or without fabric reinforce- ment – in the 3-120mm diameter range, and for different extrusion pressures. Automatic adjustment allows the floating die inside the extrusion head to be displaced in any required direction. In the event of batch changes, new head parameters are set at the push of a button. Setpoint deviations, in terms of wall thickness and concentricity, are corrected and displayed on the control panel.
Chemical transport Tecnomatic has developed a new set of die-heads for making multilayer polyethylene pipe with an inner layer of either polyamide or PVDF. The PA-containing pipe is aimed at transporting
hydrogen gas – which could begin to replace natural gas – while the PVDF offers an inner protective layer. Hydrogen is seen as a clean, efficient way of
Below: Tecnomatic has developed multi-layer pipe die heads to combine PE with either PA or PVDF
reducing carbon emissions. However, hydrogen transportation poses challenges, as it requires special materials and technologies to ensure its safe handling and delivery. Tecnomatic says its new die-heads are specifically designed to solve this. Using polyamides as an inner layer provides high resistance to hydrogen permeation and robust mechanical properties. Polyamides have high tensile strength, elastic modulus and impact resistance – and are resistant to many chemicals, including hydrocarbons and alcohols. An inner layer of PVDF (polyvinylidene fluoride)
– a resistant and chemically inert material – protects against corrosion and chemical attack. It is widely used in the chemical industry for handling harsh liquids such as concentrated acids, as well as
compounds such as halogenated, aliphatic, and aromatic solvents. Tecnomatic says the die-heads consider not just mechanical performance, but also the specific char- acteristics of the polymers being processed. It uses materials and treatments that are tailored for polyamide and PVDF, so that the die-heads can achieve optimal processing efficiency while minimising potential material degradation.
Pipe-coating cross-heads Austria-based Conextru has developed a range of cross-heads that can coat both steel and plastic pipes. Pipe coating offers flexible production and can
be integrated into existing extrusion lines. The coating structure can be mono- or multi-
layer. Monolayer coating is mostly as a final protection layer and applications are diverse. Examples include a PP protection layer for water pressure pipes, or a PE-RT layer for an RTP pipe used in oil and gas applications. “The range in diameters goes from very small up to 1200 mm,” says Josef Dobrowsky, managing director of Conextru. Multi-layer structures are also possible, and can be applied to steel or plastic pipe. Typical polymers for such applications include polyamide, PET, EVOH and PPS. A cross-head system typically consists of a helical or radial spiral distributor. Conextru offers a library of geometries for this melt distribution systems and – depending on material and output – the most suitable geometry is applied. Each head is specially design for the application. There is no standard product range as each head is tailored for a project. Making a new one
26 PIPE & PROFILE EXTRUSION | May/June 2023
www.pipeandprofile.com
IMAGE: TECNOMATIC
IMAGE: CONEXTRU
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
