Production equipment and process for large-diameter biaxial-stretching PVC pipe fitting

Abstract

The invention discloses production equipment and process for a large-diameter biaxial-stretching PVC pipe fitting. The equipment mainly comprises a tapered double-screw extruder, an extruder head, a vacuum sizing device A, a first traction device, a reheating device, a stretching and diameter expanding molding device, a vacuum sizing device B and a second traction device which are sequentially and linearly arrayed to form a production line; the stretching and diameter expanding molding device is composed of an inflation rod, an expansion bag, an expansion sizing mould and a shaping bag; each of the expansion bag and the shaping bag is of an annular bag-shaped structure; the expansion bag is continuously expanded and retracted under the action of the inflation rod; a pipe fitting to be expanded moves by a certain distance through the action of an outer ring circular-arc surface of the expansion bag when the expansion bag is expanded once, so that each point of the pipe fitting can be subjected to annular expansion; the stretching is generated in the axial direction of the pipe fitting through a stretching ratio between the first traction device and the second traction device. By adopting the production equipment and process, the continuous production of the diameter-expanded pipe fitting is successfully realized, the thermal contraction of the pipe fitting is small and the axial mechanical property can be enhanced.

Description

technical field [0001] The invention relates to a production technology of large-diameter PVC pipes, in particular to biaxial stretching equipment and technology, and belongs to the field of extrusion molding of polymer materials. Background technique [0002] At present, there are mainly three types of plastic pipes used in China: polyethylene (PE), polyvinyl chloride (PVC), and random copolymerized polypropylene (PP-R). Among them, PVC pipes account for the largest share, accounting for about 70% of the market. share. Due to the characteristics of light weight, excellent chemical resistance, good electrical insulation, simple construction and low price, traditional PVC pipes are widely used in many fields. However, for large-diameter pipes, the traditional PVC pipe manufacturing process is difficult to meet the strength requirements of large-diameter pipes. Due to technical limitations, there are few domestic enterprises that can produce large-diameter pipes. However, th...

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Problems solved by technology

[0004] Domestic research on biaxially stretched pipes started late. Although some scientific research results have been achieved, most of the production methods are discontinuous, requiring high production equipment, and the performance of the produced products is unstable. There is no domestic application of this technology. Based on the reports of large-diameter pipes, the content involved in the present invention just fills up the blank in this field in China

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