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

Abstract

The invention relates to a manufacturing technique of a wood-gum tubular element, in particular to a disposable injection molding technique and device of a CPVC bent tubular element. The technique comprises technical processes of charge mixture, drying, injection molding, pressure maintaining and open modeling, wherein a heating position of a charging barrel of an injection machine is divided into seven segments in the process of injection, the temperature ranges of the segments are respectively 150-155 DEG C, 168-173 DEG C, 162-167 DEG C, 160-165 DEG C, 155-160DEG C, 150-155 DEG C, and 145-150DEG C, and the temperature of a mould is controlled between 60 and 70 DEG C. When injecting, pressures of ejection is divided into three segments which are respectively 58 MPa, 65 MPa and 80 MPa. The pitch of screw of a screw rod of the injection machine used by the method is equal to the diameter of the screw rod, a feeding segment takes up 25 percent of the total length, a compression segment takes up 50 percent of the total length, and a homogenizing segment takes up 25 percent of the total length. The invention achieves the disposable injection molding of a DN400 large-scale bent tubularelement via the improvement of the technique and the device.

Description

technical field 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 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: start up: Derivation: RH+Cl→R+HCl R+Cl 2 →RCl+Cl Termination: R+Cl→RCl Cl+Cl→Cl 2 R+R→R 2 (RH stands for PVC, → stands for heating) PVC-C is produced according to the chlorination reaction mechanism of PVC free radicals mentioned above, controlling a certain percentage of chlorine content, controlling start-up temperature and other process factors. Its chlorine content is as high as 74%, and its Vicat softening point temperature is 123°C. Concep...

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Problems solved by technology

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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