Production technology of prefabricated direct-buried insulating pipe

Abstract

The invention discloses a production technology of a prefabricated direct-buried insulating pipe. The production technology comprises the following steps: derusting, degreasing, cleaning, drying spraying, spraying polyurethane, winding polyethylene, cooling extrusion, and carrying out cooling, end treatment and detection and putting in storage on an insulating pipe wound with a polyurethane. During the implementation process of the production technology, a polyethylene insulating layer is formed through adopting a high-pressure foaming machine to inject rigid polyurethane foaming plastic stoste in a cavity formed between a steel pipe and an external protective layer; and a high-density polyethylene protective layer is prefabricated into a black or yellow plastic pipe with certain wall thickness. The production technology is simple and short in production period, can conveniently adjust the thickness of a polyurethane foaming layer and a polyethylene winding pipe, can easy meet the market demand and is remarkable in economic benefit.

Description

technical field [0001] The invention relates to the technical field of production of prefabricated direct-buried thermal insulation pipes, in particular to a production process of prefabricated direct-buried thermal insulation pipes. Background technique [0002] The traditional production method of rigid polyurethane insulation pipe is the "pipe-in-pipe" production method. First, the standard polyethylene outer casing is processed by an extruder, and then the rust-removed steel pipe is inserted into the polyethylene outer casing with a support frame. Use pipe plugs to close both ends of the pipe, inject polyurethane raw materials into the annular space, and fill the entire space after polyurethane foaming, then seal the injection hole, remove the pipe plugs, and complete the production of the insulation pipe. This production method has the problem of excess quality. First, the expansion force of the polyethylene outer protective pipe to restrain the foaming of polyurethane ...

AI Technical Summary

Problems solved by technology

This production method has the problem of excess quality. First, the expansion force of the polyethylene outer protective pipe to restrain the foaming of polyurethane during the polyurethane injection molding process. In order to protect the safety of the pipe, its design thickness needs to be increased to form a technical process. Excess quality; the second is that whether the polyurethane injection material is in a horizontal form or an inclined form, the density distribution of the pipe is uneven. In order to ensure that the density index of each part of the pipe is not lower than the standard requirement, it is necessary to inject 40-50% more polyurethane raw materials. The same process excess mass in the process