A combined plastic mold for compression molding, extrusion molding, injection molding, blow molding and low-foaming molding, which mainly includes a die combination base plate, a die combination and a die combination card with a variable cavity. The punch is a punch with a variable core, which is composed of a punch combination base plate, a punch assembly, a punch combination card board, a cavity cutting assembly and a side section combination plate. Coordinated change of mold convex, concave mold and auxiliary forming system. It can process a series of plastic parts of different shapes and sizes. In the plastic processing industry, it is matched with plastic molding machines to give plastic products a complete configuration and precise size tools. Due to the variety of plastic varieties and processing methods, and the complex and simple structures of plastic molding machines and plastic products, the types and structures of plastic molds are also diverse.

　　With the rapid development of the plastics industry and the continuous improvement of the strength of general-purpose and engineering plastics, the application scope of plastic products is also expanding, and the amount of plastic products is also rising.

　　A plastic mold is a tool for producing plastic products. It consists of several groups of parts, and this combination has a molding cavity. During injection molding, the mold is clamped on the injection molding machine, the molten plastic is injected into the molding cavity, and cooled and shaped in the cavity, and then the upper and lower molds are separated, and the product is ejected from the cavity through the ejection system to leave the mold, and finally the mold is closed again. For the next injection, the entire injection process is cyclic.

　　Generally, a plastic mold consists of a movable mold and a fixed mold. The movable mold is installed on the moving template of the injection molding machine, and the fixed mold is installed on the fixed template of the injection molding machine. During injection molding, the movable mold and the fixed mold are closed to form a gating system and a cavity. When the mold is opened, the movable mold and the fixed mold are separated to take out the plastic product.

　　Although the structure of the mold may vary due to the variety and performance of plastics, the shape and structure of plastic products, and the type of injection machine, the basic structure is the same. The mold is mainly composed of pouring system, temperature regulation system, forming parts and structural parts. Among them, the gating system and the molding parts are the parts that are in direct contact with the plastic, and change with the plastic and the product. They are the most complex and most variable parts in the mold, and require the highest processing finish and precision.

　　The gating system refers to the part of the runner before the plastic enters the cavity from the nozzle, including the main runner, the cold material hole, the runner and the gate. Molded parts refer to various parts that make up the shape of the product, including movable molds, fixed molds and cavities, cores, molding rods, and exhaust ports.