The product made from rubber as raw material and vulcanized under high temperature and high pressure in a mold is called a rubber model product. The larger one has automobile tires, and the smallest one has a lighter sealing ring with a diameter of only one millimeter. The mold material, dimensional accuracy, exhaust and mold opening difficulty directly affect the quality, labor intensity, and production efficiency of rubber products. At the same time, the selection of mold material, heat treatment and other manufacturing processes and mold assembly quality directly affect the service life of the mold. Therefore, when designing the mold, first of all should carefully analyze and study the characteristics of the shape and structure of the rubber parts, and based on this, select and design a reasonable mold structure, reasonable material and heat treatment process to meet the requirements of rubber products and the use of molds. It is required that the mold is easy to open after vulcanization, which can provide the production efficiency and the service life of the mold, thereby improving the economic benefit.

    In order to vulcanize rubber products with accurate dimensions, mold designers must be familiar with the shrinkage rate of various rubbers with different hardness and rubber content.

    The different pressing principles of rubber products can be divided into three main categories: filling molds, injection molds and injection molds.

    1. Filling and pressing mold

    The filling mold fills the rubber material into the mold cavity, and the mold obtained by pressing and heating the rubber product by a flat vulcanizer is called the filling mold. The filling die can be divided into 3 kinds.

    1. Open filling die

    Open-type filling and pressing die The open-type filling and pressing die uses the upper and lower plates to contact, and presses the product with external force. The upper mold has no guide and no feeding cavity. The rubber is easy to flow out of the parting surface, and the product has horizontal extrusion. side.

    The advantages of the open-type filling and pressing die are simple structure, low cost, easy to remove air when pressing the product, but easy to lose the rubber, and a large amount of rubber consumption. The mold with this structure occupies a relatively large proportion in the mold.

    2. Closed filling and pressing die

    The closed filling and pressing mold has a feeding cavity and the upper mold is guided. In the process of pressing the product, the rubber is not easy to flow out, the rubber is under high pressure, the product is dense, and the amount of glue is small. However, the exhaust is poor, the mold requires high precision, and the manufacturing cost is also high.

    a. Semi-closed type filling mold From a structural point of view, it has the advantages of both an open type filling mold and a closed type filling mold. The fluidity of the rubber material is restricted to a certain extent when the mold of this structure is pressed, and only a part of the rubber can flow out. The pressing pressure is higher than that of the open filling mold, and the rubber product is denser.

    3. Semi-closed filling die

    b. Compression injection molding Compression injection molding is a rubber product obtained by putting the rubber into the compression cavity, using the pressure transmitted by the plunger to press the rubber into the cavity through the injection port. The rubber products pressed by injection molding have high density and good product quality, which can improve production efficiency. It is suitable for manufacturing products with inserts, complex shapes, and difficult to install glue.

    2. Insert injection mould

    c. Injection Mold The injection mold uses the pressure of a special injection agent to squeeze and inject the rubber heated into a plastic state into the mold cavity after the mold is locked to form a vulcanized rubber product mold.

    Three, injection mold

    The determination of the structure of the injection mold should be based on the structure of the injected product, the type of the injection machine, and the structure. This kind of mold is suitable for the production and use of mass products, with high production efficiency and good product quality.