1. Core component structure design
The core components of two-color liquid silicone mold mainly include front mold, back mold, rotating mechanism and injection system. The front mold and back mold are the key parts to form the appearance of silicone products. The cavity design needs to be carefully crafted according to the shape, dimensional accuracy and surface quality requirements of the product. When designing, the fluidity and shrinkage characteristics of silicone should be fully considered and appropriate margins should be reserved. For example, for products with complex shapes, the cavity surface needs to have a smooth transition to avoid dead corners that lead to insufficient silicone filling. The rotating mechanism is a characteristic component of the two-color mold. It is usually composed of a motor, a gear drive or a hydraulic drive device and a rotating shaft. The strength and stability of the rotating shaft are crucial. It must be able to withstand the pressure and friction during mold opening and closing and silicone injection. Its connection with other parts of the mold must be precise and firm to ensure concentricity and position accuracy during rotation. Generally, high-precision bearings and positioning pins are used for matching. The injection system includes two independent injection channels, corresponding to two different colors of silicone. The diameter, length and layout of the channels should be optimized according to the viscosity, injection volume and injection speed of the silicone to ensure that the rubber can be injected into the cavity evenly and stably.
2. Collaboration between the front mold and the rear mold
The front mold and the rear mold work closely together during mold closing to form a sealed cavity space. The mold closing force needs to be precisely controlled to ensure the sealing of the cavity and prevent silicone from overflowing, but it should not be too large to damage the mold or affect the service life of the mold. During the mold closing process, the guide devices of the front mold and the rear mold (such as guide pins and guide sleeves) play a key positioning role to ensure that the two are accurately aligned. The matching clearance is usually controlled within a very small range, generally 0.01-0.05 mm. When the silicone is injected into the cavity, the front mold and the rear mold jointly bear the pressure of the silicone. Their structural strength and rigidity must be sufficient to resist the expansion force of the silicone to avoid deformation of the cavity. During the mold opening stage, the front mold and the back mold are separated in a predetermined order. At this time, the adhesion between the silicone product and the mold needs to be considered. By reasonably designing the demoulding slope and demoulding mechanism, the product can be smoothly separated from the mold. For example, for some products with deep cavities or undercut structures, demoulding devices such as ejectors and push plates are used to push the product out of the cavity when the mold is opened.
3. Operation principle of the rotating mechanism
The main function of the rotating mechanism is to rotate the mold cavity to a specific position within a molding cycle to facilitate the injection of the second color of silicone. When the first color of silicone is injected into part of the cavity and initially solidified, the rotating mechanism starts. The motor or hydraulic device provides power, and drives the rotating shaft to rotate through gear transmission or other transmission methods. The rotating shaft drives the front mold or the back mold (depending on the mold design) to accurately rotate a certain angle, usually 180 degrees or other predetermined angles. During the rotation process, the positioning system of the rotating mechanism (such as induction switch, encoder, etc.) monitors the rotation angle and position in real time to ensure the accuracy and repeatability of the rotation. Once the rotation is in place, the mold is closed again to inject the second color of silicone, so that the two colors of silicone form a specific pattern or structure in the product. The speed and stability of the rotating mechanism have an important impact on the molding cycle and product quality. Too fast speed may cause mold vibration and unstable silicone flow, while too slow speed will extend the molding cycle and reduce production efficiency.
4. Coordination of the injection system with other components
The injection system works closely with other components of the mold to achieve accurate injection of two-color silicone. Before injection, the metering device of the injection system accurately controls the injection volume of the two colors of silicone to ensure accurate proportions. When the mold is closed, the injection cylinder pushes the screw or plunger to inject the silicone into the cavity through the injection channel. A reasonable gate needs to be designed at the connection between the injection channel and the cavity. The shape, size and position of the gate affect the filling speed and pressure distribution of the silicone. For example, the use of a pin-point gate can allow the silicone to enter the cavity quickly, but care should be taken to prevent gate blockage and silicone injection. During the injection process, the pressure sensor of the injection system monitors the injection pressure in real time, which is correlated with the cavity pressure of the mold. When the cavity pressure reaches a certain value, the injection system can adjust the injection speed or stop injection according to the preset program to avoid overfilling of silicone or the generation of bubbles. At the same time, the heating device of the injection system keeps the silicone in a suitable temperature range to ensure its good fluidity, and works in conjunction with the heating and cooling system of the mold to make the silicone uniformly solidified in the cavity, ultimately forming a high-quality two-color liquid silicone product.
