Highly flexible: reliably capable of a throughput of 5 tons/hour
Stuttgart, October 2015 – Coperion Pelletizing Technology GmbH, Offenbach, has developed an automatic strand conveying system (ASC) often required by compounding systems for pelletizing at very high throughput rates. Designed to work in conjunction with Coperion's two large strand pelletizers, the SP 500 HD (working width 500 mm) and the SP 700 HD (700 mm), this new conveying system is likewise available in two sizes: the ASC 500 for throughput rates of up to 3.5 tons/hour and the ASC 700 for up to 5 tons/hour. The conveying system automatically guides the extruded strands via a cooling water chute and downstream conveyor belt into the feed mechanism of the pelletizer. A likewise automatic start-up mechanism facilitates the start-up operation, while any possible machine malfunctions caused by broken strands are avoided by the system's ability to rethread the strands. Compared to other processes, strand pelletizing ensures an extremely gentle treatment of the product, as it operates with much lower pressures. Other convincing advantages are the reduced complexity of the system and the low rate of wear. These benefits combined with its relatively low operating costs make strand pelletizing an obvious choice for the compounder.
The new SK92 die head has been developed specially for high throughput rates. Homogeneous heating/cooling ensures completely uniform extrusion of the strands across the entire width of the extrusion die. The die head is distinguished by its optimal rheology and efficient heat transfer, providing maximum possible throughput while ensuring gentle handling of the product. This feature makes the SK92 die head ideally suited to the increased throughput capabilities of the ZSK Mc18 extruder series.
The ASC automatic strand conveying system is modular, permitting flexible and rapid adaptation to the requirements of the process. If, for example, the extruded material requires more intensive cooling, the strands – after being cooled in the water chute – can also be spray-cooled with cold water on the downstream perforated conveyor. The spray bars used for this purpose can be turned on and off individually and can be readily exchanged during regular maintenance operations. Freely positionable suction stations in the conveyor system generate powerful streams of air that free the strands from adhering water. This post-cooling unit can also easily be converted to an intensive cooling section, if required. A strand drying unit in the last section of the conveyor system ensures that residual moisture is absolutely negligible when the strands are fed into the pelletizer.
Coperion's new automatic strand conveying system may be used for a broad spectrum of materials. It is equipped as standard with a vertical adjustment permitting different points of strand placement on the water chute depending on the material being processed. An integrated strand monitoring device helps to maintain high take-off speeds in conjunction with a high number of strands and hence high throughput rates in fully automatic operation. Combination with a Coperion extruder permits direct integration of the strand conveying control into the control system of the extruder, thus affording yet a further reduction in operating effort.