Characteristics of Wuhan Handern low foaming extrusion equipment
DATE：2020/12/30 8:43:08 / READ： / SOURCE：This station
Characteristics of Wuhan Handern low foaming extrusion equipment
1. Extruder for low foaming molding
Although the low foaming extrusion can be carried out by ordinary single screw extruder, the length diameter ratio of the screw must be 20-28. In order to restrain heating, the compression ratio is 2 ~ 2.5. The following conditions should be met: ① the temperature of the foaming hopper should be lower than that of the extruder; ⑤ the temperature of the extruder should be kept lower than that of the extruder.
For PVC, if the temperature of screw can be adjusted by warm oil, high quality products can be obtained.
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2. Die for low foaming extrusion
The basic structure of the die for low foaming extrusion is the same as that of the general profile extrusion, but special attention should be paid to the following situations: because the foaming material is different from the general molding material, the molten material contains foaming gas. When the internal pressure of the die changes dramatically, the bulge in this part will cause the rapid expansion of the gas and lead to uneven thickness arrangement or inconsistent density of the products Therefore, the product of the material in the mold should be gradually compressed as shown in figure 9-89. The molding surface of the die should be shortened as much as possible, and its surface should be highly ground and plated.
It is a complicated technology to determine the shape of the die. According to the hidden surface of the foam profile, the accurate size of the die can be determined through repeated tests. This size depends on the parameters of the equipment, such as the geometry of the screw, the number of screw revolutions, the cross section and formula of the profile, etc. According to the experience, the number of expansion section is about 30% in the direction of extrusion short axis and about 10% in the direction of extrusion short axis,
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3. Low foaming molding cooling setting device
The shrinkage of the foamed profile is very small, so it can be considered that the cross section of the shaping equipment is very similar to the final cross section required by the profile. When designing the size of the cross hidden surface of the shaping equipment, it must be considered that the extruded profile can not be forced when entering the shaping equipment, so as to avoid the profile bubble being compacted.
The method of cooling and shaping should be based on whether the profile is open, hollow or thick walled (see "shaping technology of profile forming"). It is different from the general profile molding is that it can not be quenched, and the cooling time is long. Embossing film equipment wwww.handern.com
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