A large pvc plastic pipe fitting injection mold hot runner disc pouring device

Abstract

The invention relates to a dish type pouring device for a hot runner of a large PVC (polyvinyl chloride) plastic pipe injection mold. The device comprises a fixed mold plate, a movable mold plate, a mold core provided with a groove in the upper end surface, as well as a hot runner system, wherein the hot runner system comprises a main runner sleeve as well as an upper dish-shaped sub-runner plate and a low dish-shaped sub-runner plate which are located in the groove; at least five mold core sprue holes communicated with a mold cavity are uniformly distributed in the wall of the groove in the circumferential direction, a sub-runner plate runner is formed between the lower end surface of the upper runner plate and the upper end surface of the lower runner plate, sub-runner plate sprue holes are formed between the upper sub-runner plate and the lower sub-runner plate and along the circumferential flanges, the main runner hole is communicated with an upper runner plate through hole, sub-runner plate runners, sub-runner plate sprue holes and the mold core sprue holes, heaters are arranged in the flanges of the upper sub-runner plate and the lower sub-runner plate, and radiators are arranged above and below the mold core sprue holes. The pouring system doesn't have condensate waste, flowing of plastic melt in the runners is facilitated, weld bond can be avoided or reduced, the cost is saved, the production efficiency is high, and the quality of a finished product is good.

Description

technical field [0001] The invention relates to the field of injection molding processing of large-scale PVC plastic pipe fittings, in particular to a hot-runner dish pouring device for the injection mold of large-scale PVC plastic pipe fittings. Background technique [0002] Polyvinyl chloride (PVC) plastic has the advantages of excellent mechanical properties, acid and alkali corrosion resistance, electrical properties, and low price. It is often used in large or ultra- Injection molding processing of large plastic pipe fittings, large plastic pipe fittings are widely used in municipal road pipe network, chemical transportation pipe network and oil pipeline and other fields. Since PVC is an amorphous heat-sensitive polymer, the melt fluidity is poor during the injection molding process, and it is easy to be thermally decomposed. For large PVC plastic pipe fittings, it is not only necessary to meet the large flow of PVC melt to quickly fill the mold cavity in a short time, ...

AI Technical Summary

Problems solved by technology

The above-mentioned straight sprue cold runner gating system requires a long cooling time and a long injection molding cycle. It is difficult to remove the thick gating system condensate on the product, resulting in a large amount of gating system condensate waste. Moreover, the size of the gate is limited, and it is generally not possible to More than 5 times the wall thickness of the workpiece, the size of the pipe fittings is limited

[0004] Hot runner technology has been widely used in injection molds. According to the number of gates, it can be divided into multi-gate and single-gate hot runners. At present, for multi-gate hot runners, the runners of the gating system are generally multi-pipe and multi-level. Tree structure, complex gating system structure, unsmooth melt flow, easy to form stagnant material in the gating system, resulting in thermal decomposition of the melt after being heated for a long time, and a large number of weld lines formed by multiple gates, affecting the quality of molded parts

[0005] For single-gate hot runners, such as Chinese patent application number ZL201010167649.4, a valve switch is set at the gate. Although the runner structure is smooth and the gate size can be larger, for large or super-large injection molding pipe fittings, the direct gate The cold runner gating system is similar, the melt flow of single gate injection molding is long, and the melt is easy to be insufficiently filled, which cannot better meet the requirements of injection molding

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