Molding method for biaxial orientation polyvinyl chloride pipe for water supply

Abstract

The invention provides a molding method for a biaxial orientation polyvinyl chloride pipe for water supply. The molding method comprises the following steps that premolding is carried out, wherein a pipe mold blank is cooled to the melting and softening temperature; then, the melt and softened material is made to pass through a pipe mold of an extruding machine, and meanwhile the material passes through a premolding sizing sleeve, wherein a pipe mold mandrel extends and enters the premolding sizing sleeve; the pre-set material passes through a molding sizing sleeve connected to the premolding sizing sleeve of the extruding machine; the set material then passes through a small pipe-expanding machine arranged at the tail end of the pipe mold mandrel to carry out expanding; the longitudinal crystallization orientation material receives the traction action of a tractor; and finally, the transverse crystallization orientation material is cooled. The biaxial orientation polyvinyl chloride pipe manufactured through the technology and used for water supply is very high in anti-shock and anti-pressure ability, and thus the service life of the pipe can be prolonged.

Description

technical field [0001] The invention relates to the field of plastic building material production, in particular to a method for forming biaxially oriented polyvinyl chloride pipes for water supply Background technique [0002] PVC is an amorphous polymer material. Due to the existence of polar chlorine elements in the molecule, PVC has high rigidity. Between the glass transition temperature and the melting temperature, under the action of external force, the molecular segments are arranged from disorder Transforming to an ordered arrangement, the material changes from isotropic to anisotropic. Ordinary PVC-U water supply pipes are only axially oriented under the action of traction, so the minimum required strength MRS of ordinary PVC-U water supply pipes is 25MPa, while PVC-O pipes are biaxially stretched and oriented. Orientation crystallization is carried out, so the MRS of PVC-O water supply pipe can be up to 50MPa. The 50-year safety factor of ordinary PVC-U water sup...

AI Technical Summary

Problems solved by technology

[0004] However, since the molding methods of PVC-O water supply pipes are mostly monopolized by foreign technologies, the country is still