The production process of glass includes: batching, melting, forming, annealing and other processes.
1. Ingredients: weigh all kinds of raw materials and mix them evenly in a mixing machine according to the designed recipe. The main raw materials of glass include quartz sand, limestone, feldspar, soda and boric acid.
2. Melted, the high-temperature heating, with good materials to form homogeneous glass without bubbles. This is a very complex physical and chemical reaction process. Glass melted in the melting furnace. Furnace mainly has two types: one is a crucible furnace, glass material is filled in the crucible, outside the crucible heated. Small only put a crucible crucible kiln, can be more big to 20 crucible. Crucible furnace is a batch production, now only optical glass and color glass USES the crucible kiln production. The other is a tank furnace, glass material inside YaoChi melted, flame heating. On the surface of the glass temperature of the melted glass, is mostly in the 1300 ~ 1600 ゜ c. Most of them are heated by flame, while a few are heated by current, which are called electric melting kilns. Nowadays, the pool kilns are continuously produced, and the small ones can be several meters, and the large ones can be more than 400 meters.
The forming process can be divided into two categories: artificial and mechanical.
A. artificial forming. (1) blowing, with A nickel-chromium alloy blowpipe, pick A ball of glass in the mold in turn while blowing. Mainly used for forming glass bulb, bottle, ball cross (lens use), etc. (2) the drawing, after blowing into vesicles, in particular of the other workers stick, two people blow while mainly used to make A glass tube or bar. (3), pick A ball of glass, with scissors cut makes it fall into the concave die, with A punch press. Mainly used for forming A cup, plate, etc. (4) the free forming, carry with forceps, scissors, tweezers, etc after material tool directly to make arts and crafts.
Mechanical forming. B. because artificial labor intensity, high temperature, the condition is poor, so, in addition to the free forming, most have been replaced by mechanical forming. In addition to suppress, blowing and drawing mechanical forming, there are (1) calender method, used in the production of thick plate glass, patterned glass, glass clip wire, etc. (2) casting, production of optical glass. (3) the centrifugal casting method, used in the manufacture of large diameter glass tube, utensils, and the large capacity of reaction pot. This is the glass melt injection mold in high speed rotation, due to centrifugal force close to the mold wall glass, rotate to continue until the glass hardening. (4) the sintering process , used in the production of foam glass. It is in the glass powder adding foaming agent, heating in the covered metal mold, glass formed in the process of heating a lot of silent air bubbles which is a kind of very good thermal insulation, sound insulation materials. In addition, the flat glass forming a vertical law, between law and float upward. Float is to make the glass flow floating in the molten metal (tin) formed on the surface of flat glass, the method of its main advantages are high quality glass (smooth, bright and clean), pull speed, large output.
4. Annealing glass after forming into withstood intense temperature change and shape change, this change left the thermal stress in the glass. The thermal stress can reduce the glass strength and thermal stability. If direct cooling, probably in the process of cooling or later in the process of storage, transportation and use their own rupture (commonly known as glass cold blast). In order to eliminate the phenomenon of cold blast, glass annealing must be conducted after forming. Annealing is at a certain temperature range insulation or slow cooling for a period of time in order to eliminate or reduce the thermal stress in glass to the allowable values. In addition, some glass products can be hardened to increase their strength. And chemical rigidization (ion exchange), used for coating glass on the watch, aero-glass, etc. The principle of rigidization is to produce compressive stress on the glass surface to increase its strength.