Plastic mold design knowledge 1. Design basis The accuracy of dimensional accuracy and related dimensions. According to the specific requirements and functions of the whole product of plastic products, which kind of external quality and specific size are determined: plastic products with higher appearance quality requirements and lower dimensional accuracy, such as toys; functional plastic products, size requirements Strict; plastic products that require strict appearance and size, such as cameras. Is the draft angle reasonable? The draft angle is directly related to the release and quality of the plastic product, that is, whether the injection can be carried out smoothly during the injection process: the draft angle is sufficient; the slope is to be in the form of a part or a part of the molded part of the plastic product. Adaptation; whether it will affect the accuracy of the appearance and wall thickness; whether it will affect the strength of a certain part of the plastic product. Second, the design process for the analysis and digestion of plastic products and physical (real sample): A, the geometry of the product; B, size, tolerance and design basis; C, technical requirements; D, plastic name, brand E, surface requirements The number of cavities and the arrangement of the cavities: A, the weight of the product and the injection volume of the injection machine; B, the projected area of the product and the clamping force of the injection machine; C, the outer dimensions of the mold and the effective area of the mold for the injection machine, (or injection Drawer rod spacing) D product accuracy, color; E product with or without side shaft core and its processing method; F production batch; G economic benefit (production value per mold) After the number of cavities is determined, the cavity is Arrangement, ie the arrangement of the cavity positions, the arrangement of the cavities involves the dimensions of the mould, the design of the gating system, the balancing of the gating system, the design of the core (slider) mechanism, the design of the inserts and cores, the design of the heat exchange system The above problems are related to the selection of the parting surface and the gate position. Therefore, in the specific design process, necessary adjustments should be made to achieve a more perfect design. Third, the determination of the parting surface does not affect the appearance; it is conducive to ensure product precision, mold processing, especially the processing of the cavity; Conducive to the design of the pouring system, exhaust system, cooling system; Conducive to mold opening (parting, taking off The mold ensures that the product is left on the side of the movable mold when the mold is opened; the arrangement of the metal insert is facilitated. Fourth, the design of the gating system The design of the gating system includes the selection of the main channel, the shape and size of the cross-section, the choice of the position of the gate, the form of the gate and the size of the cross-section of the gate. When using the gate, in order to To ensure the shedding of the runner, attention should also be paid to the design of the degasser and the nine-gate mechanism of the demister. When designing the gating system, first select the location of the gate. The choice of gate location is directly related to the quality of the product and the smooth progress of the injection process. The choice of gate location should follow the following principles: 1 The gate location should be selected on the parting surface to facilitate the processing and use of the gate. 2; the distance between the gates and the parts of the cavity should be as uniform as possible, and the process should be the shortest; 3 The position of the gate should ensure that the plastic flows into the cavity, and the cavity is wide and thick, so as to facilitate the plastic. Smooth inflow; 4 gate position should be opened at the thickest part of the plastic part; 5 Avoid plastic straight into the cavity wall, core or insert when flowing down the cavity, so that the plastic can flow into the cavity as soon as possible, and avoid The core or insert is deformed; 6 try to avoid causing the product to have weld marks, or make the weld mark appear in the unimportant part of the product; 7 the gate position and the plastic inflow direction should be such that the plastic can flow along the cavity when flowing into the cavity The parallel flow of the cavity is uniform and facilitates the discharge of gas in the cavity; 8 The gate should be placed on the most easily removed part of the product without affecting the appearance of the product as much as possible. V. Design of the exhaust system The exhaust system plays a vital role in ensuring the quality of the product. A. Using the venting groove, the venting groove is generally located at the portion where the cavity is finally filled. The depth of the venting groove varies depending on the plastic, and is basically determined by the maximum allowable gap in which the plastic does not generate a flash. For example, ABS 0.04 is 0.02 or less with ash of 0.02 mm or less. BUsing the clearance of the core insert pusher or the like or the special exhaust plug to exhaust; C sometimes in order to prevent the product from causing vacuum deformation when it is ejected, the air pin must be provided; D sometimes to prevent vacuum adsorption of the product and the mold, The design of the anti-vacuum adsorption element. Sixth, the design of the cooling system The design of the cooling system is a relatively cumbersome work, that is, to consider the cooling effect and the uniformity of cooling, but also to consider the impact of the cooling system on the overall structure of the mold. The arrangement of the cooling system and the specific form of the cooling system; the specific location and size of the cooling system; the cooling of key parts such as moving molds or inserts; the cooling of side slides and side cores; the design and cooling standards of cooling elements Selection of components; sealing structure design.