The design of rubber extrusion die is obviously different from that of compression die. For the rubber mold, the rubber compound is vulcanized and shaped under the fixed containment and constraint of the mold cavity, so the shape of its products is completely consistent with the shape of the mold cavity, and qualified molded products can be obtained as long as the design scale is correct.

On the contrary, because the vulcanization of rubber extrusion products is completed on the open microwave (or other vulcanization methods) vulcanization production line, the cross-sectional shape of the extrusion die is not the same as that of the final rubber product after extrusion, or even very different.

Then the extrusion die of the material,

Among the plastic products sold in the market today, the types of extruded products are increasing day by day. Plastic pipes, plates, films and special-shaped materials occupy a very important position in the application.

Extrusion molding is a continuous molding method in which powdered or granular raw materials are heated and melted, then extruded and then cooled and solidified. Therefore, extrusion molding equipment must have three types: melting, molding and curing.

Function.

The melting function is undertaken by the extruder, the forming function is undertaken by the extrusion die and the forming die, and the curing function is undertaken by the forming die and the cooling die. As a complete extrusion equipment, it needs auxiliary equipment such as tractor, cutter and crimper to sort out the extrudate.

The appearance and quality of the extrudate largely depend on the quality of the die. In addition, the uniformity of the melt conveyed by the extruder to the die and the mixing process of the melt in the die will also affect the quality of the extrudate. For extrudates with various cross-sectional shapes, the cross-sectional shapes are generally the same along the extrusion direction, but in some special cases, the cross-sectional shapes can be changed by setting special devices at the back of the die or adopting special operation methods. Such as embossing or blow molding.

In recent years, in addition to single material extrusion molding, there are many kinds of plastic integral extrusion molding methods. The extrusion technology of aluminum, iron, wood and other materials has also been developed, which makes the structure of extrusion die increasingly complex.

The die, which plays an important role in the extrusion molding device, is continuously supplied with molten material by a screw at a pressure of 3MPa-30MPa, and the molten material is molded into extrudates with required cross-sectional shapes through the die. In this process, the circular cross-section molten material sent from the cylindrical barrel enters the die with circular or rectangular groups through the coupler, and after the shape is changed in the die, the extrudate with the required cross-section shape is extruded from the gap at the end of the die. Therefore, it is necessary to ensure the gap of the melt flow path in the mold from the round or rectangular group to the outlet part, which becomes close to the cross-sectional shape of the molded product.

This change process is smooth, and the streamlined design does not retain parts.

In addition, because the plastic melt used is a non-Newtonian fluid, it has both viscous and elastic characteristics, so the role of elasticity must be fully considered in the flow characteristics of the melt.