Manufacturing method for PVC straight-through pipe and PVC straight-opening reducer tee joint

Abstract

The invention relates to a manufacturing method for a PVC straight-through pipe and a PVC straight-opening reducer tee joint. The manufacturing method comprises the following steps that pipe-shaped objects are cut into required lengths and angles through a multi-angle pipe sawing machine; the cut pipe-shaped objects are placed on a welding machine clamp and well fixed; the to-be-welded end faces of the two pipe-shaped objects are treated to be level and smooth; the end faces are folded, the centering situation is checked, the staggered edges of the two to-be-welded end faces are no more than 10% of the wall thickness, and otherwise, adjusting is conducted through the clamping force of the clamp and the end faces are treated to be level and smooth again; a welding machine heating plate is placed between the two pipe ends, the pressure P1 is gradually exerted within the time T1, so that the pipe ends are pressed on the heating plate to be heated, after uniform welding beads are formed, the pressure is gradually decreased to be P2 and maintained to be P2, and heat is absorbed; the pipe ends are released, the heating plate is taken out, and then the pipe ends are folded again; the pressure is gradually increased from 0 to P1, so that the pipe welding parts inwards and outwards form uniform turned edges; and the pressure P1 is maintained, so that the welding parts are naturally cooled.

Description

technical field [0001] The invention relates to the technical field of pipe materials, in particular to a heat-melt welded PVC pipe, a pipe joint and a manufacturing method thereof. Background technique [0002] At present, as a new type of chemical building material, plastic pipes have been widely used in fluid transportation in various fields because of their light weight, convenient installation, corrosion resistance and many other advantages. [0003] PVC pipe is the main variety of plastic pipes. Compared with other plastic pipes, it has the advantages of high strength, wide source of raw materials and relatively low price. It is an early development and application of plastic pipes and has always maintained a good momentum of development. In the research and development of PVC pipes, various scientific research institutes and production enterprises have strong interests. [0004] The tensile strength of PVC pipes can reach more than 50MPa, PE pipes are only 23MPa, and...

AI Technical Summary

Problems solved by technology

During the heat absorption process, a non-uniform melting softening section with gradually increasing melt strength is actually formed. This non-uniform melting softening section is extremely unstable during the subsequent pressurized butt joint, and may bend to the inner side of the pipe wall. , It may also be bent to the outside of the pipe wall. This irregular bending will cause dislocation of the welding joint and a change in the shape of the circular tube, that is, a good weld cannot be formed. Therefore, the hot-melt welding technology of PVC has not been realized. Thus limiting the application of PVC pipes in the field of large-diameter pipes

In the disclosed content of the above-mentioned patent CN101112792A, in the endothermic stage, P (drag), which is consistent with the hot-melt welding of PE materials, is still adopted to apply P (drag), that is, drag pressure. This is a standard welding process for PE materials. It can be found in other public materials. For the hot-melt welding of PVC, due to the characteristic of PVC without fixed solder joints, it cannot be effectively implemented at all, and the hot-melt butt joint of PVC pipes cannot be realized in practical applications: welding of PE materials In the process, the consideration of the dragging pressure is because the hot-melt welding of PE pipes is basically on-site operations, and the PE pipes are very long, basically more than 10 meters. The minimum sliding friction force during on-site dragging is to consider the pressure applied in the on-site operating environment. The dragging pressure is very small, and P1 is 40 to 120 times the dragging pressure. In the PVC welding process, dragging is definitely not applied Hot-melt welding of PVC can be realized by dynamic pressure

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