Blow molding, also known as hollow molding, is a manufacturing process for forming hollow plastic parts: it is used to form glass bottles in the initial stage. Generally speaking, there are three main blow molding methods: extrusion blow molding, injection blow molding and injection stretch blow molding. The blow molding process begins with melting the plastic and forming it into a parison, or during injection and injection stretching, the blow molding parison is a tubular plastic part with a hole at one end through which compressed air can pass.
The utility model relates to a molding method for blowing thermoplastic closed in a mold into hollow products by using gas pressure, which is used for manufacturing hollow products. Then clamp the parison into the mold and blow air into it. The air pressure is then pushed out of the plastic to match the mold. Once the plastic cools and hardens, the mold opens and the part is ejected.
It is widely used in toy industry, daily necessities industry, chemical industry, cosmetics industry, food industry and so on. Common blow molding products include: toy car, teapot, toolbox, wheel, mineral water bottle, lampshade, flowerpot, bucket, can, pipeline building materials, automobile conduit, hose, container, oil depot equipment, stadium seats, etc. The higher the molding temperature, the greater the proportion of irreversible deformation in the product, and the better the shape stability of the product.
The process of extrusion blow molding includes forming a tube blank, extruding through an extruder and hanging in a pre separation cavity directly below the die head. The influencing factors of biaxial tensile process are different. The appropriate tensile temperature of various resins is different. Generally, the temperature with large elongation is taken as the tensile temperature.
The screw rotates to fill the plastic raw material into the waiting room until it is fully loaded. It is used through the screw in conjunction with the external heater. After the feed mixing, the softened and melted plastic is pressed out into a hollow tube while it is hot. The tube body hanging from the top is clamped in the hollow mold with a pre designed shape, and the softened plastic is inflated to the inner wall of the mold with high-pressure air, Then remove the excess part of the bottle mouth from the outside of the mold.
