Chlorinated polyvinyl chloride DN400 elbow pipe fitting once injection moulding technique and device thereof

Abstract

The invention relates to a production process of resin pipe fittings, in particular to a one-time injection molding process and equipment for chlorinated polyvinyl chloride elbow pipe fittings. The process includes batching, drying, injection molding, pressure holding, and mold opening process. During the injection molding process, the heating part of the barrel of the injection molding machine is divided into seven sections, and the temperature range of each section is 150-155°C and 168-173°C. , 162~167℃, 160~165℃, 155~160℃, 150~155℃, 145~150℃, the mold temperature is controlled between 60~70℃; the injection pressure during injection molding is divided into three sections, respectively 58MPa , 65MPa and 80MPa. The pitch of the injection molding machine screw used in the method is equal to the diameter of the screw, the feeding section accounts for 25% of the total length, the compression section accounts for 50% of the total length, and the homogenization section accounts for 25% of the total length. The invention realizes one-time injection molding of DN400 large elbow pipe fittings through the improvement of process and equipment.

Description

technical field [0001] The invention relates to a production process of resin pipe fittings, in particular to a one-time injection molding process and equipment for chlorinated polyvinyl chloride elbow pipe fittings. Background technique [0002] PVC-C (chlorinated polyvinyl chloride) is produced by the chlorination of PVC free radicals. The general chlorine content is 63% to 69%. Different chlorination methods, states and chlorine reactions, the resulting PVC-C has Big difference. Its chlorination reaction process is as follows: [0003] start up: <chemistry num="0001"> <chem file="200610150656_CML001.XML" / > < / chemistry> [0004] Derivation: RH+Cl→R+HCl [0005] R+Cl 2 →RCl+Cl [0006] Termination: R+Cl→RCl [0007] Cl+Cl→Cl 2 [0008] R+R→R 2 [0009] (RH stands for PVC, → stands for heating) [0010] PVC-C is produced according to the chlorination reaction mechanism of PVC free radicals mentioned above, controlling a certain percentage of ...

AI Technical Summary

Problems solved by technology

[0011] DN400 elbow pipe fittings refer to large elbow pipe fittings with a nominal diameter of 400. When the existing technology is used for one-time injection molding of DN400 elbow series pipe fittings, the following problems often exist: (1) due to PVC-C (chlorinated polyvinyl chloride) (2) PVC-C (chlorinated polyvinyl chloride) resin has a high chlorine content, and the temperature control range deviation is small , the friction heat generated by the screw during pre-molding is difficult to control, so the pre-molding time required for DN400 elbow fittings is long, and the material is easily burnt in the barrel; (3) PVC-C (chlorinated polyvinyl chloride) resin Good toughness, high impact strength, large cut, during the process of processing, the rotation speed of the injection molding machine oil motor is unstable during pre-molding

Due to the above reasons, according to the existing technology and process, it is impossible to solve the problem of one-time injection molding of DN400 elbow series pipe fittings

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