Glass bottle forming process
1. Molding process
The forming process of glass bottles and jars refers to a series of action combinations (including mechanical, electronically controlled, etc.), repeated in a given programming sequence, and the goal is to manufacture a bottle with a specific expected shape. There are currently two main processes in the production of glass and jar containers: blow blowing for narrow mouths and pressure blowing for larger diameter bottles and cans.
In these two forming processes, molten glass liquid, at its feed temperature (1,050-1,200°C), is cut by a shear blade to form cylindrical glass droplets called 'gobs'. The gobs The weight is enough to produce a bottle. Both processes start from shearing the molten glass, and the gobs fall under the action of gravity, and pass through the chute and diverting trough, into the primary mold, and then the primary mold is closed tightly, and is opened by the top The "dull head" is sealed.
During the blowing process, the glass is first pushed down by the compressed air passing through the bulkhead, so that the glass at the die is formed; then the core moves down slightly, and the compressed air passing through the gap at the core position expands from bottom to top Extruded glass fills the blank. With such glassblowing, the glass is formed into a hollow prefabricated shape, which is subsequently blown again by compressed air in a second stage to give the final shape.
The production of glass jars takes place in two main stages: in the first stage all the details of the mouth mold are formed, and the mouth is completed including the inner opening, but the main shape of the glass product will be much smaller than its final size. This semi-formed glass product is called a parison, and in the next moment, they will be blown into the final bottle shape.
From the perspective of mechanical action, the die and core form a closed space below. After the die is filled with glass (after puffing is complete), the core is retracted slightly so that the glass in contact with the core softens slightly. Then compressed air from bottom to top (back blowing) passes through the gap under the core to form the parison. Then the bulkhead rises, the initial mold is opened, and the turning arm is turned over to the forming side together with the die and the parison.
When the turning arm reaches the top of the mold, the molds on both sides will be closed and clamped to enclose the parison. The die opens slightly, releasing the parison; the flip arm then returns to the blank side, waiting for the next round of motion. The blowing head descends to the top of the mold, compressed air is poured into the parison from the middle, and the extruded glass expands to the forming mold to form the final shape of the bottle.
In the pressure blowing process, the parison is no longer formed by compressed air, but is formed by extruding glass in the closed space of the primary mold cavity through a longer core. Subsequent inversion and final shaping are consistent with the blow-and-blow method. Afterwards, the bottle will be clamped out of the forming mold by the pincer bottle, placed on the bottle stop plate with cooling air from bottom to top, and waits to be transported to the annealing process by pinching the bottle.
2. Bottle making machine
Bottle making machine refers to equipment that can make glass bottles and jars. Generally speaking, the bottle making machine includes the most basic 19 actions to form a bottle. Most of the current bottle making machines and mechanisms are driven by compressed air (high pressure 4.2 bar, low pressure 2.2 bar), the equipment is electronically controlled by a timer system and all actions are coordinated.
The most widely used bottle making machine is the individual group bottle making machine (IS machine). This machine has 2-20 identical groups, each of which contains a complete set of mechanisms to meet the needs of bottle and can production. Gobs from all groups are fed into each group by moving scoops called gob distributors. The bottle making machine can make one, two, three or four bottles at the same time (referred to as single, double, three and four drops). Up to now, even the 6-drop bottle making machine has been successfully developed and put into production. In the case of multiple gobs, the scissors cut the gobs simultaneously and fall into the blank at the same time.
As glass cools, it shrinks and solidifies. Uneven cooling and rapid cooling cause stress in the glass, which can make the glass brittle or explode. The function of the annealing furnace is to heat the glass bottles and jars to about 580°C, and then slowly cool them down to relieve the stress generated in the glass forming process and ensure the safety of the glass containers. This annealing process depends on the thickness of the glass, generally within a period of 20 - 60 minutes.