Pipe manufacturers aiming to be competitive in production these days need extrusion lines, which are powerful, flexible, and quickly adjustable, as well as cost-efficient in operation. Precisely these features are what the complete pipe extrusion line from battenfeld-cincinnati Germany has to offer, which was demonstrated for the first time at two customers’ events in mid-February.

Equipped with the new fast dimension change (FDC) system, the highly effective internal pipe cooling system (EAC), as well as melt cooling integrated in the die (VSI-T+) and a special execution for quick colour change, this high-speed 4-layer co-extrusion line provides an enormous amount of flexibility. Pipe dimensions can be changed quickly and automatically during production, and so can the color of the stripes or the pipe’s outer layer. “On the two days we demonstrated the equipment, our customers were shown the world’s most modern extrusion line for this application so far. With this, we offer our customers added value, which is unique in the industry”, Rainer Kottmeier, Division Manager Infrastructure, emphasises.

Battenfeld-cincinnati estimated that some 70 customers from Europe and the Near and Middle East responded with “enthusiasm about the quality of the 4-layer polyolefin pipes produced at the demonstrations of the co-extrusion line with a total output of 1,500 kg/h”; and owing also to the excellent quality of the pipe surface and the precise wall thickness distribution, which was immediately within tolerance again even after a changeover in dimensions, convinced even extremely skeptical visitors.

Special attributes of the dimension change system from battenfeld-cincinnati are its adjustability within an extremely wide range of dimensions, its easy-to-operate water flow adjustment system in the inlet zone of the calibrating sleeve, and the optimal roundness of the pipes. The latter is achieved by the calibrating sleeve, which consists of rolled sheet metal and ensures absolutely circular pipes with excellent wall thickness distribution by means of its cylindrical design. With optional pipe die centering, the wall thickness distribution lies within the bottom third of the tolerance margin required by the DIN standard. The even water cooling in the inlet zone of the calibrating sleeve is responsible for the homogeneous pipe surface without water marks and consequently for the high quality of the pipes. With the line on display, which was specially designed for a European customer, a range of pipe dimensions from 200 to 800 mm can be covered. This is why this line comes with two adjustable calibrating sleeves. While the first of these allows automatic adjustment of pipe dimensions between 200 and 355 mm, the second covers the range from 400 to 630 mm. In this case, flexibility also means that not only standard dimensions but also intermediate sizes and customised sizes can be produced without modification of the line. For the pipe dimension range from 710 to 800 mm, standard calibration systems are used in this customised version.

“The development of the FDC system was a logical next step for us in our strategy of offering our customers extremely economical pipe extrusion lines”, says Kottmeier. Over the last seven years, the output of battenfeld-cincinnati pipe extrusion lines has roughly doubled. While in former times lines with 600 kg/h were regarded as high-performance equipment, throughputs of 1,200 kg/h and more are today’s standard in the production of gas and potable water pipes. Reaching such throughputs requires not only extremely powerful, all-purpose extruders with innovative screw concepts, but above all appropriate cooling systems for fast pipe cooling, to ensure observance of pipe tolerances and to reduce the overall length of the line.

Lines from battenfeld-cincinnati have both: the solEX 75-40 main extruder exhibited on this occasion is a very powerful extruder with a processing length of 40 D, which provides gentle plasticising across a large processing window. Thanks to its combination of a smooth spiral mandrel for melt pre-distribution with a compact lattice basket for detail distribution, the helix 800 VSI-TZ+ pipe die used in this line offers the advantages of low pressure build-up and functionality independent of melt viscosity. The effective EAC internal pipe cooling system enables the high line speeds and, together with the active melt cooling system inside the die, minimises undesirable sagging. This also contributes to the excellent pipe quality.

The other line components are also laid out for maximum flexibility and cost efficiency. This is why, following the pipe head, the line operates with an adjustable melt gap instead of a pin-and-die combination, which would have to be exchanged for a dimension changeover. A coex radial distributor is integrated in this adjustable melt gap to enable color changes to be effected quickly and with maximum efficiency. Therefore it is possible to not only change the pipe dimension with minimum waste of material on the battenfeld-cincinnati FDC line, but to implement an equivalent color change of the outer layer as well. Due to the fast color change options, the benefit from this line has again been increased considerably. Moreover, with its 4-layer co-extrusion configuration, the line can produce pipes not only for standard applications, but also for special industrial applications, for example where an oxygen barrier layer must be integrated into the pipe wall.

The vacStream 800-6 vacuum tank has also been specially designed for the automatic dimension change and consequently the high flexibility of the line. It operates with a pipe support device across 180° of the pipe circumference and is steplessly adjustable across the entire range of dimensions (200 – 800 mm) without any structural changes. The flexible sealing at the end of the vacuum system stands out by its simple structure without any mechanically moving parts and has already been used many times for retrofitting on existing extrusion lines. During a dimension change, the haul-off and cutting devices are also adjusted automatically to the new dimension at exactly the right time. In order to effect the automatic changeover without any problems and fully automatically, the battenfeld-cincinnati specialists have optimally expanded the BMC touch extruder control system so that the changeover of all components takes no more than the push of a button.