Extruder worm for very wide range of thermoplastics - has core blending from cylindrical into polygonal cross=section

摘要

The shortest distance between the outer edge of the propelling spiral and the highest surfaces of the polygonal core of the worm of an extrusion press. is >=2mm and also =6.7% of the external dia. of the worm. The greatest distance between the outer edge of the propelling spiral and the lowest surface of the polygonal core of the worm is >=10% but also =22% of the outer dia. of the worm. The worm acts on the cylinder for the continuous prepn. of thermoplastic masses and consists of an inlet zone and a mixing and delivery zone with a continuous spiral coil. From the inlet zone the cylindrical core of the worm passes through a short transition zone intoa polygonal form. Used to provide an extrusion worm with a geometry which permits it to have the widest possible application for the plasticising of different thermoplastic materials, under conditions ensuring the gentlest treatment of the materials so that interchanging of worms is unnecessary. The advantage of the new worm is that it works without compression and kneads the thermoplastic against the wall of the cylinder.