قیمت دستگاه بادکن پت دستی
It is also used for forming glass bottles or other hollow shapes.
In general, there are three main types of blow molding:
extrusion blow molding, injection blow molding, and injection stretch blow molding.
The blow molding process begins with melting down the plastic and forming it into a parison or,
in the case of injection and injection stretch blow molding (ISB),
a preform. The parison is a tube-like piece of plastic with a hole in one end through which compressed air can pass.
The parison is then clamped into a mold and air is blown into it.
The air pressure then pushes the plastic out to match the mold.
Once the plastic has cooled and hardened the mold opens up and the part is ejected.
The cost of blow molded parts is higher than that of
injection-molded parts but lower than rotational molded parts.
The process principle comes from the idea of glassblowing.
Enoch Ferngren and William Kopitke produced a blow molding machine and sold it to Hartford Empire
Company in 1938. This was the beginning of the commercial blow molding process.
During the 1940s the variety and number of products was still very limited and therefore blow molding did not take off until later.
Once the variety and production rates went up the number of products created soon followed.
The technical mechanisms needed to produce hollow bodied workpieces using the blowing technique were established very early on.
Because glass is very breakable, after the introduction of plastic,
plastic was being used to replace glass in some cases. The first mass production of plastic bottles was done in America in 1939.
Germany started using this technology a little bit later, but is currently one of the leading manufacturers of blow molding machines.
Today, an even greater number of products are blown and it is expected to keep increasing.
For amorphous metals, also known as bulk metallic glasses, blow molding has been recently
demonstrated under pressures and temperatures comparable to plastic blow molding.