Draft, commonly used in dense foam injection molding processing parts of the draft also applies to structure, for smooth surface, select 2 - mostly
A minimum of 0.
, while the polystyrene minimum 1 & deg;
, the surface has the texture of slope can be appropriately increased.
Parts of the wall thickness can affect the mould for Angle size, when the wall thickness to reduce need greater slope.
Structure of the foam products can use without reinforcement or less reinforcement, has been relatively flat products.
on the wall through the hole of the parts, can be in after molding, products after processing and/or setting insulating plug at the site of the hole, block the flow of resin adhesive mould to form a hole, with a wall of convex or concave hole, when the design can be designed into blind holes, stay after molding, products according to the need to the depth of cut.
In addition, the two parts design into an organic whole, forming open pore structure, is also a kind of method.
the biggest advantage is its structure foam products with high specific strength, and therefore is widely used in various large-scale molding parts.
Wall thickness design, mainly depending on the purpose, low density foam products should take larger wall thickness, but thin-walled structure foam has good surface quality.
Parts allows for a larger wall thickness change, but don't cloud creek mutations, streamline thickness is proposed between the smooth transition, uniform wall thickness is helpful to control the quality of the products.
if the designed products have higher strength than the quality, then the structural foam should be a better choice.
Structure of foamed plastic parts with dense skin layer and foam core layer, apply Yu Chengli structure.
Can there are many kinds of molding method, using injection molding is a main forming method of this kind of foam structure.
Pretty similar manufacturing process with normal injection molding, the main difference is in the plastic components joined the foaming agent.
in the structure of the injection molding foam plastic, the most is the low pressure method is used to process, in addition to high pressure, back pressure and injection molding process.
In addition to increasing complexity, on craft are the main difference on the products is bubble pore structure and surface quality of the product.
Wall thickness variability is large, the lower limit of wall thickness is 4 mm, upper limit depending on the needs, household appliances shell wall thickness option 4 -
5 mm, used as a tray of wall thickness can be up to 25 mm.
preferable trapezoidal metric coarse thread and sawtooth thread.
Diameter smaller external thread, can use technology to realize embedded spiral.
In addition to pay attention to thread length shoulds not be too tight, not too long, in order to avoid stress concentration, at the beginning of the thread should be equipped with the steps, the roots are not allowed to have sharp corners, and generation with rounded corners.
Due to the need of the function set holes, should be based on the type of injection hole processing specific treatment.
although the wall thickness is much higher than ordinary solid plastic, but there is no ordinary plastic surface shrinkage, sag caused by thickness, also won't produce buckling deformation.
Can have a large surface area and good dimension stability, high flatness.
As a result of low pressure molding process, internal stress is small.
Using low pressure molding process the structure of the foam products, its surface will appear corrugated, need through the surface treatment, get the required appearance.
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