machinery feature | Pipe dies
Conextru is supplying
rotating pipe dies for specialist
applications
vertically installed pipes, while reducing noise. Other examples include:
l increasing the mechanical strength of PE pipe by orientating the outer layer; l adding internal oscillating ribs to PE cable duct piping – which reduces friction and increases pull- through length; l PE pipes with internal spiral ribs, to generate turbulent flow – and increase the thermal conductivity of geothermic pipes; l PP pipes with hollow profile in a spiral shape – which increases ring stiffness of the pipe; and, l PE or PP pipes with a glass fibre layer in a spiral shape – to increase pressure resistance. Rotation can be realised by using a motor to turn the die and mandrel independently, in a variety of ways. Rotation speed can be adjusted and is usually 0.5-30 rotations per minute (rpm) depending on the require- ment and application. For a basic pipe head, Conextu uses either helical
spiral or radial spiral technology for polyolefin pipes. A combination of the two can be used for multilayer pipes.
Co-extrusion crosshead Guill Tool has developed its Series 824 a co-extrusion crosshead for irrigation tubing. It features balanced flow design with spiral technol- ogy that improves flow characteristics at all extruder speeds. Dual feed ports provide concentric compound flow, while the splits flow from one extruder to feed the inside and outside layers via a manifold assembly. Capacities include a maximum die internal diameter (ID) of 1.875in, maximum core outside diameter (OD) of 1.250in, maximum tip OD of 1.500in and maximum emitter tool OD of 1.18in (30mm). The Series 824 design allows the emitter insertion
Guill says its Series 824
co-extrusion
crosshead for irrigation tubing has
improved flow characteristics at all extruder speeds
tool to pass completely through the crosshead ID. Gum space adjustment is performed with die nut rotation, while the Guill two-stage clamping mechanism allows easier concentricity adjustment. Quick-change tooling and a tool kit for disassembly and re-assembly are provided with the unit.
Bill Conley, sales manager for Guill, said: “On this project, the customer challenged us with an application that required precise placement and bonding of preformed emitters within the extruded tubing without melting them in the crosshead. It was also necessary to process either a low-cost ABA layer
30 PIPE & PROFILE EXTRUSION | June 2016
construction or single-layer construction within the same unit.”
The Series 824 helped the customer to reduce cost,
raise quality, cut scrap and improve uptime. Guill’s cool-tube design prevented the emitter from melting in the head and the overall unit mechanics allowed more rapid and easier changeover from a co-extrusion to a single layer.
Earlier, it introduced the Series 725, a co-extrusion
crosshead for tray cable applications. It incorporates the patented Guill Seal Right system of self-aligning tapered deflector and body design. Guill developed it in partnership with a customer, to
convert a production line from a Tandem line – with two heads a distance apart – into a co-extrusion line with a single head applying both layers of PVC in a single operation. The efficiency and improved profit potential from the new configuration was substantial, said Guill. Other benefits include: shorter changeover time;
less scrap; and improved product quality – thanks to increased adhesion between layers, because melt adheres to melt rather than extrudate. Additional features include multi-port spiral flow, easy disassembly and restart, positive seals for leak elimination, adaptability to all extruder brands, and a concentricity adjustment. Guill has also improved its Bullet extru- sion head – introduced last year – by adding the patent-pending Cam Lock deflector retaining system. Using the Cam Lock, it only takes a half-turn to remove and install the
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