Plastic insert

Abstract

The invention discloses a plastic insert, which is used in various plastic pipelines such as polypropylene (PP-R) pipelines, polyethylene (PE) pipelines, polyethylene of raised temperature resistance (PERT) pipelines, polybutylene (PB) pipelines, polyvinyl chloride (PVC) pipelines and the like. The plastic insert serving as a threaded transition piece comprises an internal threaded insert and an external threaded insert and is an important constituent part of threaded transition pipe fittings of the PP-R pipelines, the PE pipelines, the PERT pipelines, the PB pipelines, the PVC pipelines and the like, wherein both the internal threaded insert and the external threaded insert comprise a cylindrical main body part and a threaded part; an internal thread is arranged on the inner wall of a main body of the insert; an external thread is arranged at the upper end of the main body of the insert; and a groove which is coaxial with the external cylindrical surface is formed on the bottom face of the cylindrical main body part far away from a threaded interface. By adopting a special structure, the insert in the threaded transition piece of the plastic pipelines can be changed from a metal piece into a plastic piece; and the threaded transition piece which is made of the insert with the structure through secondary injection molding has higher comprehensive performance than that of a pipeline made of a metal insert, and phenomena of cracking and leakage are prevented.

Description

technical field [0001] The invention relates to a threaded connection piece of a plastic pipe, in particular to a plastic insert. Background technique [0002] Nowadays, in the domestic and international society, various plastic pipes such as PP-R, PE, PERT, PB, PVC are widely used. This kind of pipe has many advantages such as hygiene, lightness, convenient installation, reliable performance, and low cost. The strength of the material itself is low, and it is not allowed to be made into threads. Therefore, the parts of these pipes that need to be threaded are made of threaded transition pieces that are combined with metal parts and plastics through injection molding. These transition pieces are all combined with threaded metal parts and plastics by injection molding process. For the sake of appearance, most of the metal parts are electroplated with nickel or chrome. The commonly used metal material is brass, generally H59-1. [0003] At present, the structure used for the...

AI Technical Summary

Problems solved by technology

But in actual use, the following problems will also occur: 1. Since the copper parts of the accessories are all made of brass, the brass is relatively brittle. During construction, if the construction personnel work brutally, the copper parts will crack; 2. In the metal Occasional leakage occurs between the contact surface with the plastic, especially as the internal pressure of the pipe increases, this phenomenon will become more frequent

Many enterprises and individuals hope to make some improvements to the existing technology, and have made some attempts, that is, the materials used will be changed to engineering plastics, and the structure of the current general product is still adopted. In order to enhance the sealing performance, the width of the groove along the cross-sectional direction will be made Make it smaller and increase the number of grooves; as now, there are generally two dovetail grooves with a width of 3mm. In order to achieve a good effect, four grooves with a width of 1mm are changed, which can also properly enhance the sealing performance; because the plastic insert is made of injection molding Process production, dovetail grooves cannot be made, and the sealing performance is still not fully guaranteed; experiments have proved that the leakage of this structure is still relatively frequent, especially the leakage rate of internal threaded fittings is very high, and the reliability of threaded transition pieces is low

The above two defects are determined by the material and structure of the product, and it is impossible to completely eliminate them.

In addition, as we all know, compared with plastic parts, copper parts have the following disadvantages: 1. Copper is a mineral resource, which is non-renewable, and the cost of copper parts is relatively high; 2. Long-term contact of copper with air or water will produce copper rust, which is called verdigris; 3. The production energy consumption of copper parts is high, which is a high energy-consuming product; 4. Copper parts are processed by machinery, and the control of dimensional tolerance is greatly affected by human factors, and the defective rate in actual production is high; 5. Copper parts are machined Processing, low production efficiency, is a labor-intensive product; 6. For the sake of beauty, copper parts are generally electroplated, and electroplating is a polluting process

Therefore, so far, in the application of plastic pipes, there is no example of using plastic inserts in batches, and the use of plastic inserts instead of metal inserts has become an urgent problem to be solved.

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