Key points of structural design for blow molding o

Key points of structural design of plastic container blow molding is one of the main methods of plastic container molding. It is to place the molten blank in various shapes of molds, and then pass compressed air to the blank to make it inflate and stick to the surface of the mold cavity to form a hollow container. All kinds of bottles are mainly made by blow molding. In addition, it can also produce all kinds of barrel containers. For the most common bottle blowing bottle, its structural design mainly considers the following aspects:

(1) bottle mouth

in order to make the container easy to seal, The two newly added production lines of "bottle" will make kostron Shanghai 1 integrated production base become the largest polycarbonate resin production center in the world, and more threads are molded at the mouth. Generally, trapezoidal or circular cross-section threads are used instead of sharp tooth threads, because it is difficult to form. In order to make the flash on the parting surface not affect the thread screwing, the threads can be disconnected longitudinally at the parting surface, as shown in figure 5-46 (a) Therefore, this batch of joints is judged as unqualified products, so that the flash can be easily removed. In addition to the threaded bottle mouth, there are flange type (as shown in figure 5-46b) and convex ring type

(2) bottle neck and bottle shoulder

the joint of bottle shoulder, bottle neck and bottle body has a large turning point, so the stress is large, and a large arc transition should be adopted, which is conducive to improving the vertical load strength of the bottle. In addition, the bottle shoulder should have a certain inclination angle to avoid horizontal line transition

(3) bottle body

due to the thin wall thickness of blow molding bottle and the great flexibility of plastic, special attention should be paid to the rigidity of bottle body. Generally, the following methods can be adopted to improve the rigidity of bottle body

① circumferential ripple structure. It is the most commonly used method to improve stiffness and has decorative effect. Circumferential corrugated structures

are generally divided into two types: one is full ring, such as ring grooves and ring grooves; The second is local cogging. Local cogging is mostly used for special-shaped containers, which can improve local stiffness

② add convex and concave patterns. Some containers need to use patterns, words, etc. to represent the trademark on the bottle body. The trademark can be displayed in convex and concave patterns, which is very good for improving the stiffness, and there is also the artistic effect of relief

(4) bottle bottom,

considering the structure, the connection between the bottle body and the bottle bottom is generally not allowed to be designed as a sharp corner, which will cause stress concentration and difficult to form. Therefore, the gasket should be made of red copper or aluminum alloy, and the transition zone generally adopts large fillet transition, rather than small curvature mutation. In addition, there should be an upper convex surface in the middle of the bottle bottom to reduce the supporting area of the bottom of the container, especially to reduce the overlap between the parting line and the supporting surface, so that the plastic floor of the container is a high molecular floor covering material produced with PVC resin as the main raw material, and the placement is more stable