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The pressure molding method is suitable for mass
production of products with stricter size requirements or the upper part is
usually not flat. It is a commonly used method in the production of cast
products. Inject the mixed rubber material into the mold, stay for a period of
time, and close the mold when it gels and press it into shape. The key to this
method is the mastery of the gel point. It is too early to close the mold and
pressurize, and the squeezing force of the rubber material is not enough, and
it is difficult to completely discharge the internal bubbles; pressurized after
the gel point, the material is cross-linked, and the elasticity is large and
easy to crack. The gel point should be determined through experience based on
specific conditions. The characteristic of the material when it reaches the gel
point is that the surface is not sticky, but it has not been completely
hardened (the touch of the available material). It is also possible to use gel
material for pressure molding. According to the size of the mold, cut the gel
sheet into an appropriate size and install it in the mold. The mold temperature
or processing temperature is 90-120°C, and the pressure vulcanization time
depends on the part, shape and size. It can also be press-molded with granular
gel materials. This method requires higher mold strength.
Among CPU products, the most type is molded products.
Generally, molded products have complex shapes and are not easy to machine. The
required dimensions are relatively accurate, and the internal quality
requirements are also high, such as seals for hydraulic systems, elastic
couplings, etc. Molded products have various shapes and a wide range of
applications. The formula is different. How to improve the yield of molded
products requires continuous summing up of experience and improving the level
of operation. Here are two points: First, the structure of the mold must be
carefully considered, not only the yield of the product, but also the
convenience of operation and the manufacturing cost of the mold; the second is
that the timing of mold clamping must be accurate, otherwise it will lead to
waste. The clamping time of different formulas is not the same. It must be
determined according to the specific situation, and needs to constantly explore
and accumulate experience in practice.