Extrusion International 5-2025

61 Extrusion International 5/2025 ow resistance is also identical, which in turn in uenc - es the throughput or layer thickness. The Y-block and the two pipe heads are mounted on a xed pipe head carriage or frame. Due to the greater overall length of the 4-layer version compared to the 2-layer version, it was necessary to use an additional pipe head support, which is designed for the 4-layer head and can be swiveled in if required. An essential component of the system is the pipe cool- ing, which enables high line speeds to be achieved. Cooling is provided by two separate cooling sections, which are arranged on the left and right. The systems consist of a 9 m long vacuum full bath with two cham- bers, followed by four baths, each 9 m long, in spray bath design. Each vacuum bath is equipped with two separate vac - uum pumps and two separate spray pumps. The vacuum is controlled via PLC in the extruder con- trol system of the main extruder. The vacuum is set via the speed of the vacuum pump motor. Either the speed or the pressure in mbar can be speci ed as the setpoint. The water temperature in the vacuum bath is also controlled by the extruder control system, and the cool- ing water temperature can be set as a target value. To ensure a constant water temperature, a fresh water in- let and a controlled cooling water outlet are installed. The process data can be viewed and modi ed both in the extruder control system and on the operating terminal on the tank. Of course, the two operating ter- minals also feature buttons for the “pump on/off” and “vacuum on/off” functions, as well as for operating the motorized longitudinal adjustment. The decision to use a high line speed is essential to ensure smooth running of the pipe. The special design, which does not require silicone seals, is an essential pre - requisite. In this con guration, line speeds of 40 meters per minute per strand can be achieved, which corresponds to a total speed of up to 80 meters per minute. In this case, twin-screw extrusion is a sensible method. The two draws can be controlled independently of each other. Relative meter weight control can be imple- mented very well by means of optical measurement, which keeps the production process constant. The use of gravimetric dosing to control the output per extruder is standard practice and an absolute neces- sity. The advantage of such a system lies in the possibility of producing two different products from the same ma- terial at high performance with only four extruders. The task at hand was solved in a special way, which makes it truly remarkable. However, it is unlikely that this solution can be considered standard in the future. Rather, this example illustrates the technical possibilities of twin-screw extrusion. CONEXTRU thus demonstrates that it is actively com- mitted to developing special solutions, in contrast to other suppliers of extrusion systems who mainly work with standard solutions. Such special one-off solutions are of secondary importance to these companies due to the uniqueness of the high engineering content and the risk involved. By J. Dobrowsky CONEXTRU Klosterstarsse 19, 3011 Irenental, Austria Dobrowsky.j@conextru.eu 2 Strand / 2 Chamber Vacuum Tank Control page for process datas cooling