Chlorinated polyvinyl chloride DN400 loose flange once injection moulding technique and device thereof

Abstract

The invention relates to a productive technology for producing wood-gum flange, in particular to a technology and device for one time injection molding of chlorinated polyvinyl chloride lap joint flanges. The technology comprises industrial processes of burdening, drying, injection molding, pressure maintaining and model opening, wherein in the injection molding process, the heating portion of a charging barrel of an injection machine is divided into seven segments, the temperature ranges of the segments are respectively 150-155 DEG C, 168-173 DEG C, 162-167 DEG C, 160-165 DEG C, 155-160 DEG C, 150-155 DEG C, and 145-150 DEG C, the temperature of a die is controlled between 60 and 70 DEG C, the injection pressure when injection molding is divided into three segments which are respectively56 MPa, 59MPa and 76MPa. The pitch of a screw of the injection machine used in the method is equal to the diameter of the screw, the delivery segment occupies 25 percent of the whole length, the compressing segment occupies 50 percent of the whole length, and the homogenizing segment occupies 25 percent of the whole length. The invention realizes one time injection molding of DN400 large-scale lap joint flanges via improving the technology and the device.

Description

technical field The invention relates to a production process of a resin flange, in particular to a one-time injection molding process and equipment for a chlorinated polyvinyl chloride loop flange. 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. Conceptually, PVC...

AI Technical Summary

Problems solved by technology

DN400 looper flange refers to a large-scale looper flange with a nominal diameter of 400. When the existing process is used for one-time injection molding of DN400 looper series flanges, the following problems often exist: (1) due to PVC-C ( Chlorinated polyvinyl chloride) resin has a large proportion of raw materials, and the torque generated by the screw of the injection molding machine in the pre-molding exceeds the design requirements of the standard screw; (2) PVC-C (chlorinated polyvinyl chloride) resin has high chlorine content and temperature control The range deviation is small, and the friction heat generated by the screw during pre-molding is difficult to control, so the pre-molding time required for the DN400 loop flange is long, and the material is easily burnt in the barrel; (3) PVC-C (chlorinated polyvinyl chloride) Vinyl chloride) resin has good toughness, high impact strength, and large cutoff. In 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 looper series flanges

Images