Dies Design for Plastics Pipe.

Nowadays about eleven different thermoplastics are used in the extrusion of tube on the industrial scale. Of these only rigid PVC, polyethylene and polypropylene are processed commercially. Hence, the common die designs are particularly intended for these thermoplastics, and the dies suitable for this purpose are the subject of this report. Plasticized PE is primarily used for small tube sections, rigid PVC predominantly in the range from 500 to 630 mm, whereas rigid PE covers all tube diameters up to heavy-duty pipe (up to about 1500 mm outer diameter). Accordingly, die designs are dependent upon the raw material and the tube dimensions. The report gives the following explanations: influence of the tube dimensions and raw materials on the design of the extrusion head; design and construction of pipe dies; heads for PVC pipe of small, medium and large diameter; heads for PE pipe of small diameter and for heavy-duty pipe; dies for high-speed pipe extrusion. The paper also describes calibration devices for inner diameter and outer diameter control, including auxiliary equipment like vacuum tank, etc. Forecast for the future development is included.