What is the rubber extrusion mold design discussion?

What is the rubber extrusion mold design discussion?

Discussed the effective thickness design of monomer rubber extrusion mold cavity, extrusion mold cavity repair debugging and composite rubber extrusion mold design of a variety of composite materials in the synchronous composite extrusion, composite skeleton into the mold and extrusion outlet mold composite position locking, adjusting the composite gap and with the tilt angle of the problem, in the microwave vulcanization process, through the mold design, vulcanization process control and the aid of the shaped cushion belt. Means of conformal products.

In the rubber products industry with microwave vulcanizing line production of extruded rubber products with high production efficiency, economic benefits, based on the production of rubber products are widely used in automotive manufacturing and other industries. Extrusion mold design is a key issue that directly affects the quality of extruded products.

The design of rubber extrusion molds is significantly different from that of molding molds. For rubber molding die, the rubber is in the mold cavity of the fixed inclusion and restriction is vulcanized stereotypes, so the shape of its products and the shape of the mold cavity perfectly match, as long as the design of the shrinkage ratio is correct, you can get qualified molded products. Contrary to the ratio, the extrusion mold mouth section shape and extrusion after the final rubber product section shape is not the same, or even very different, the reason is that the vulcanization of rubber extruded products in the open microwave (or other vulcanization) vulcanization production line to complete. Its products from the extrusion mold is extruded from the moment, the product cross-section shape is constantly changing. Firstly, when the product is extruded from the mold, its section shape will be unevenly expanded, which is the first deformation. Subsequently, the product enters the microwave vulcanization box by attracting ultra-high frequency wave (UHF) and its own heat, soften, under the influence of self-weight the whole section will be deformed, the thinner rubber "leaves" will be sagging deformation, and even make the similar rubber body stick together with each other, and the hollow products will be in the trapping deformation, so that the section will be flattened and so on, which is the second deformation. Deformation. When the products into the high-temperature heating insulation box will make the deformation of the section switch to continue to change and be gradually fixed down, this is the third deformation. In the cooling process due to the contraction of rubber rest will occur and make the section size changes again. These 4 deformation caused by the extruded product cross-section shape and size are just extruded from the mold with a big difference.

At present, the rubber extrusion mold can be divided into two kinds, namely monomer rubber extrusion mold and compound rubber extrusion mold. These two types of extrusion molds that have commonality, but also personality.

single rest rubber extrusion mold

For any extrusion mold, the main point of its design is to ensure that the cross-section of the extruded product size and shape in line with the design requirements. The main factors affecting the following six aspects: ① any rubber from the extrusion mold extrusion will occur when different expansion, when the hardness of the rubber from small to large, the extrusion section of the expansion rate from large to small. ② When the extruder temperature from low to high, the extrusion section expansion rate from small to large. ③ When the extruder speed is low and high, the size of the extruded product section changes from small to large. (4) The expansion rate of the extruded product section is different for different kinds of rubber or different rubber content blends. ⑤ The expansion rate of each part of any extruded product section is not the same, and this is especially true for shaped sections. (6) Different design forms of extrusion molds will have different effects on the shape and size of the extruded product section. Here are some design ideas on one of the above factors.

extrusion mold cavity design thickness

Extrusion mold cavity design of 100 degrees must match the specifications of the extruder. In terms of the current general medium-sized extruder, the effective thickness of the cavity of the withdrawal mold if less than 8mm, the dimensional stability of the extruded section is relatively poor, the gel surface is not smooth. In the production process, the extruder screw speed adjustment fluctuations or feed section size changes will make the extrusion mold cavity pressure fluctuations. The effective thickness of the mold cavity is too small will make this pressure fluctuation effect is not enough to be overcome, the rubber material through the cavity surface extrusion and friction deformation to the extruded product section shape and size, the formation of the "wave extrusion" effect; at the same time, the effective thickness of the cavity is too small will result in the extrusion force is too small, so that the extruded products of density At the same time, the effective thickness of the cavity is too small will cause the extrusion force is too small, so that the density of the extruded products, resulting in the surface is not smooth, burrs, poor conformability, on the other hand, the effective thickness of the extrusion die cavity is too large will also affect the normal assembly with the head of the extruder, and make the mold repair difficulties, so that the debugging cycle is too long. Therefore, for general medium-sized extruder, the effective thickness of the cavity of the monomer rubber extrusion mold can be taken as 10 to 15cm.