Principle of plastic extrusion equipment
Plastic extrusion equipment is widely used in the processing of pipes, rods, monofilaments, plates, films, wire and cable coatings, and profiles.
The principle of a plastic extruder is that solid plastic is melted, plasticized under the conditions of heating and screw rotation and pressure of the extruder, and is made into a continuous plastic product with the same cross-section as the shape of the die through a die of a specific shape. Its manufacturing materials are mainly carbon structural steel, alloy tools, etc. Some extrusion molds are also inlaid with wear-resistant materials such as diamond on parts that require wear resistance. The extrusion process is generally only applicable to the production of thermoplastic products, and its structure is significantly different from injection molds and compression molds.
Principle of plastic extrusion equipment
Foam extrusion: Thermoplastic elastomer tpv can be foamed by chemical and mechanical methods. For chemical foaming, a blowing agent such as a heavy hydrochloride salt can be used. The achievable specific gravity of foam density ranges from 0.97 (typically unfoamed tpv) to 0.70. Lower density is affected by patents. The blowing agent will degrade at 180 ° C to 190 ° C, because most of the tpv basis is performed at 195 to 215 ° C.
Multi-layer extrusion: Co-extrusion is a technology that combines two materials into one part in an extrusion process. The two extruders are connected in series to provide a bottom die and co-extrud the respective polymer materials along corresponding channels to obtain an extruded glue of the two materials. Even materials such as tpv and polypropylene can be fused together. Multi-layer extrusion is a good way to mix hard and soft materials. More typically, high-hardness section sections, such as thermoplastic elastomers tpv, are generally used as support structures for components, while low-hardness materials provide flexibility. This is common in sealing applications because the sealing area is soft and the soft material can be crushed to obtain a good sealing effect. In the process of balancing the flow field, it is simpler to use a higher hardness thermoplastic elastomer tpv as a rigid material instead of polypropylene.
Welded joints: Thermal welding is a more popular method for joining extruded glue made of tpv. Heat is introduced to the connection surface to melt the surface, then the surfaces are bonded together, and a slight pressure is applied to ensure that no gas enters the contact surface. After cooling, the joint is almost as strong as the part itself. Another method of joining the extruded parts is to use an adhesive system.
