What is the design principle of the hole generated when forming the self sealing pocket? Let's have a professional analysis.
Some self sealing pockets form a blind hole and then drill through. This method is suitable for thin and deep holes and prevents the core from deforming during the molding process. Plastic products have no holes after molding, and the holes are processed in the later stage. The latter two methods are limited to a few easy to cut materials such as nylon. At the same time, due to secondary processing, low production efficiency and difficult to ensure the quality of fine holes, it is rarely used. This section mainly introduces the design principle and processing method of the hole directly generated during forming.
For the holes directly generated during forming, no matter what type, they should be set at the parts that are not easy to weaken the strength of the products, and the shape of the holes should not complicate the mold manufacturing process. It is an important factor of residual welding line and strength weakening in molded products. A raised edge is set around it for reinforcement. At the same time, the spacing of holes and the distance to the edge of the product should also be appropriate.
The dimensional relationship shown is determined. When the sizes of the two holes are different, take the smaller 7L; 75% of the values in table 2-7 shall be taken for the injection products of thermoplastic self sealing bags. For the depth of holes, the depth of different types of holes varies with different forming methods. Through hole injection molded products L are widely used, and the cores used to form through holes generally have different installation methods.
The inner end of the core is fixed and formed, which is easy to produce flash, and the iron core is easy to bend when it is thin. This method of fixing the iron core cannot form deep holes. It consists of two iron cores fixed at both ends, because one iron core is designed to be larger than the other. About 5-1mm to ensure the concentricity of the hole, which will not cause difficulties in the installation and use of the soil, but also increase the stability of the core and the accuracy of the hole is low.
It is composed of a core body with one end fixed and one end guided and supported, so that the core body has good strength and stiffness and can ensure concentricity, but the guide part is easy to produce arc flash due to guide error wear. No matter what fixing method is used above, the depth of the hole should not be too large, and the ruled core will bend.
The depth of Jinan self sealing pocket with good fluidity can reach 10 times the aperture, and the medium fluidity can not exceed 7 times the aperture. The hole depth of plastic products with poor fluidity is less than 4 times the diameter of 7L, otherwise it can only be obtained by machining.
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