Sat Apr 29 15:22:39 CST 2023
Extrusion moulds are moulds for the production of continuous shaped plastic profiles, also known as extrusion moulds, extrusion heads or die heads.
The word extrude is made up of the Latin words "ex" (to leave) and "trudere" (to push) and describes the extrusion process in which "pressure is applied to drive the material through the mould". The polymer is then passed through a die set at the end of the barrel to form a continuum that resembles the shape of the die's orifice, and is finally cooled and shaped to form the desired shape of the product, such as a variety of plastic pipes, bars, sheets, plastic windows and doors, and plastic materials, sheets, plastic steel doors and windows, films, decorative skirting, etc.;
Extrusion mould is the core part of extrusion production, the technical state of the extrusion mould is directly related to the stability of extrusion production, the quality of extruded products, extrusion production efficiency and the service life of the mould itself. Therefore, the design of the extrusion die becomes very important. In the design of the head, the following points should be noted:
The internal cavity of the head should be streamlined
In order to enable the material to be extruded evenly along the head runner, to avoid overheating decomposition of the material due to stagnation, there must not be a sharp reduction in the head, let alone dead ends and stagnation areas, should try to make the runner smooth, the recommended surface roughness Ra value in 0.4μm
Adequate compression ratio
Depending on the plastic product and the plastic variety, the head should be designed to produce a sufficient compression ratio to eliminate the bonding seam caused by the manifold and to make the product dense.
Correct cross-sectional shape
Due to the properties of the plastic, pressure, density and shrinkage, the shape of the moulded section of the head differs from the real section of the product.
Compact rhythm and easy disassembly
Under the condition of satisfying the mechanical properties, the head should be designed with a rhythm, tight joints, uniform heat transfer, easy disassembly and no material leakage.
Reasonable material selection
The head should be made of corrosion-resistant, friction-resistant, good tensile strength and high hardness steel. Some also have to be chrome plated according to the situation.