The production process of glass includes: ingredients, melting, forming, annealing and other processes.
Here are the following:
The ingredients, according to the design of the material prescription, the various raw materials in a mixing machine mix evenly.
The main raw materials of glass are quartz sand, limestone, feldspar, soda, boric acid and so on.
The molten material is heated by high temperature to form a homogeneous, bubble-free glass solution.
This is a very complicated physical and chemical reaction process.
The melting of glass is carried out in the furnace.
There are two main types of melting furnace: one is the crucible kiln, the glass is in the crucible, and it is heated outside the crucible.
The small crucible kiln has only one crucible, which can be as large as 20 crucibles.
The crucible kiln is produced in the gap type, and now only the optical glass and the color glass are produced by the crucible kiln.
The other is the pool kiln, the glass material in the furnace melt, the open fire on the glass surface heating.
Most of the glass temperature of the melted in 1300 ~ 1600 ゜ c.
Most of them are heated by flame, and some are heated by electric current, which is called electric melting furnace.
Now, the pool kiln is continuously produced, small pond kiln can be several meters, big can be big to more than 400 meters.
Forming is the conversion of molten glass into solid products with a fixed shape.
Forming must be done within a certain temperature range. This is a cooling process. Glass is first converted from a viscous liquid to a plastic state and then into a brittle solid.
Forming methods can be divided into two categories: artificial forming and mechanical forming.
There is also (1) blowing, with a nickel-chromium alloy blowpipe, a glass of glass in the mold side of the edge blowing.
It is mainly used for forming glass bubble, bottle and ball.
(2) pull, after blowing into vesicle, another worker stuck to the top plate, and the two of them blew and pulled mainly to make glass tubes or rods.
(3) press and select a ball of glass, cut it with the scissors to drop it into the concave mould, and then press the punch.
Mainly used for forming cups, plates and so on.
(4) free forming, using pliers, scissors, tweezers and other tools to make handicrafts directly.
Due to the large labor intensity, high temperature and poor condition, most of the artificial forms have been replaced by mechanical forming.
In addition to pressing, blowing and drawing, there is also (1) calendering method, which is used to produce thick flat glass, engraved glass, metal wire glass and so on.
(2) casting method to produce optical glass.
(3) centrifugal casting method is used to manufacture large diameter glass tubes, vessels and large capacity reaction POTS.
This is to inject the glass melt into a high-speed rotating mold, as the centrifugal force causes the glass to cling to the mold wall, and the rotation continues until the glass is hardened.
(4) sintering method for producing foam glass.
It is used in the glass powder to add foaming agent, in the metal mold with cover to heat, the glass in the heating process to form a lot of close mouth bubble this is a very good insulation, sound insulation material.
In addition, the forming of plate glass has vertical introduction, flatness and float.
Float is the method that allows the glass liquid to float on the surface of molten metal (tin) to form a plate glass. The main advantage is that the glass is of high quality (smooth and smooth), and the drawing speed is fast and the output is large.
Annealing, the glass has undergone a drastic change in temperature and shape, leaving thermal stress in the glass.
This thermal stress reduces the strength and thermal stability of glass products.
If it is cooled directly, it is likely to burst in the process of storage, transportation and use during the cooling process.
In order to eliminate the phenomenon of cold explosion, glass products must be annealed after forming.
Annealing is a period of heat preservation or slow cooling within a certain temperature range to eliminate or reduce the thermal stress in the glass to the allowable value.