Mold design and manufacture are closely related to plastic processing. The success or failure of plastic processing largely depends on the effect of mould design and the quality of mould manufacturing, and the design of plastic mould is based on the correct design of plastic products.
The structural elements considered in the design of plastic moulds are as follows:
The parting surface is the contact surface between the die and the punch when the die is closed. The selection of its position and form is influenced by the shape and appearance of the product, wall thickness, forming method, post-processing technology, die type and structure, demoulding method and the structure of the forming machine.
(2) Structural parts, i.e. slider, inclined top, straight top block of complex die, etc. The design of structural parts is very critical, which is related to the life, processing cycle, cost and product quality of the die. Therefore, the design of complex core structure of the die requires a higher comprehensive ability of the designer, and pursues a simpler, more durable and more economical design scheme as far as possible.
(3) Mould accuracy, that is, avoidance of cards, precise positioning, guide pillars, positioning pins, etc. The positioning system is related to the appearance quality of products, the quality and life of dies. According to the different structure of dies, different positioning modes are selected. The positioning accuracy control mainly depends on processing. The positioning of internal dies is mainly considered by the designer to design a more reasonable and easy-to-adjust positioning mode.
(2) The pouring system, i.e. the feeding passage from the nozzle of the injection machine to the cavity, includes the main passage, the shunt passage, the gate and the cold hole. In particular, the selection of gate location should be conducive to filling the cavity of molten plastics in a good flow state, and the solid runner attached to the product and the cold material of the gate are easy to eject and remove from the die when opening (except the hot runner die).
(3) Shrinkage of plastics and various factors affecting dimensional accuracy of products, such as manufacturing and assembly errors of moulds, wear of moulds, etc. In addition, the matching of technological and structural parameters of the moulding machine should also be considered when designing the compression and injection moulds. Computer aided design technology has been widely used in plastic mould design.