Plastic Hollow forming refers to the use of compressed air blown into a hollow container and vacuum suction into the shell container. Blow molding hollow containers are mainly used in the manufacture of thin-walled plastic bottles, barrels and toy-type plastic parts. Blister hollow containers are mainly used in the manufacture of thin-walled plastic packaging supplies, cups, bowls and other disposable containers. The Hollow blow molding is to put the plastic type billet in the plastic state in the mold, the compressed air injected into the billet will blow up, so that the shape of the product after blowing and the shape of the mold cavity is the same, cooling the stereotypes to get the products needed.
According to the different forming methods, can be divided into extrusion blow molding, injection blow molding, injection stretch blow molding, multi-layer blow molding, sheet metal blow molding form.
(1) Hollow blow molding process classification
Extrusion Blow Molding
Extrusion blow Molding is the main method of forming hollow plastic parts. First, the extruder is extruded tubular billet, and a section of the tube is cut into the mold. Closing off the mold at the same time clamping the upper and lower ends of the billet, into the cavity into the compressed air, so that the expansion of the mold cavity wall formed, and then the pressure, and finally cooling stereotypes, you can eliminate compressed air and open mold out of the plastic parts. Extrusion Blow molding die structure simple, less investment, easy to operate, suitable for a variety of plastic hollow blow molding.
The disadvantage is that the wall thickness is not uniform, plastic parts need to be processed to remove the flying edge.
Injection blow Molding
Injection blow molding is made by injection molding machine in injection mold, and then the hot-type billet into the hollow blow molding mold for hollow blow molding. The injection molding machine is injected into the injection mold by injecting the molten plastic into the molding billet, and the core and the Parison are moved into the blow moulding the core is hollow and has holes on the wall, and the compressed air is made from the pipe of the mandrel, so that the parison is blown up and affixed to the mold cavity wall, and the compressed air is released after the pressure-retaining and cooling-setting, and the molded parts are taken out.
After injection molding molded parts of the wall thickness uniformity, no flying edge, no post-processing, from the dry injection of the bottom, so there is no spelling and sewing, high strength, high production efficiency, but the equipment and mold price is expensive, used for small plastic parts of mass production.
Injection Stretch Blow Molding
The process of stretching is increased by comparing the injection molding with injection molding. First, a hollow-bottomed parison is injected, the Parison is moved to the stretching and blow-moulding station, the stretch is carried out, the blow molding, the holding pressure is cooled, and the molded parts are opened after cooling. There's another one. The method of injection stretch blow molding, i.e. cold billet forming method, the injection of Parison and the stretch blow molding of plastic parts are carried out on different equipments respectively, after the injection of the type billet, and then to blow the blow molding machine, at this time the Parison has distributed some heat, need to be two times heating to ensure the shape of the stretch blow molding temperature,
The main feature of this method is that the device structure is relatively simple.
Related Industry Knowledge
- Injection system
- Clamping system
- Hydraulic system
- Electrical control
- Heating / cooling
- Lubrication system
- Safety monitoring
- Before operating the main points
- Classification and purpose
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