The word extrude consists of the Latin "ex" (away) and "trudere" (push), which graphically describes the extrusion process of "applying pressure to drive the material through the mold."
In processing, the polymer in the form of powder or granular form is usually added to the barrel of the extruder. Under the action of the screw or the plunger, the polymer moves forward along the groove or the barrel and gradually melts to become sticky. The fluid is then formed into a continuous body similar in shape to the die of the mold through a mold disposed at the end of the barrel, and finally cooled and shaped to form a product of a desired shape, such as various plastic tube bars and sheets. , plastic steel doors and windows, film, decorative skirting and so on.
General design points of plastic extrusion die
Extrusion mold is the core part of extrusion production. The state of extrusion mold technology is directly related to the stability of extrusion production, the quality of extruded products, the efficiency of extrusion production and the service life of the mold itself. Therefore, the design of the extrusion die is very important. In the design of the nose, the following points should be noted:
The inner cavity of the nose should be streamlined
In order to make the material evenly extruded along the flow path of the machine head, to avoid the material from being overheated and decomposed due to stagnation, it must not be sharply reduced in the machine head, and there should be no dead angles and stagnant areas. The flow path should be smoothed as much as possible. Surface roughness Ra value is 0.4μm
Sufficient compression ratio
According to the different varieties of plastic products and plastics, it is designed to produce a sufficient compression ratio head to eliminate the joint seam caused by the shunt bracket to make the product dense.
Correct section shape
Due to the properties, pressure, density, shrinkage and other factors of the plastic, the shape of the die-forming section of the machine head is different from the true cross-sectional shape of the product. This factor should be considered in the design so that the die has a reasonable cross-sectional shape. .
Compact and easy to disassemble
Under the condition of satisfying the mechanical properties, it is necessary to design a nose with a rhythm walking, a tight joint, a uniform heat transfer, convenient disassembly and assembly, and no leakage.
Reasonable material selection
The machine head should be made of steel with corrosion resistance, friction resistance, good tensile strength and high hardness. Some are also chrome-plated depending on the situation.