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Hot melt glass
- Apr 27, 2018 -

The main includes: (1) pre processing of raw materials. The bulk material (quartz sand, soda ash, limestone, feldspar, etc.) is crushed to dry wet raw materials and iron - containing raw materials are treated with iron removal to ensure the quality of glass. 2. Preparation of mixture. (3) melting. The glass batch is heated at a high temperature (1550~1600 degree) in a pool kiln or a crucible kiln to form uniform, non bubble and liquid glass conforming to the molding requirements. (4) forming. The liquid glass is processed into products of the desired shape, such as plates, containers, etc. Heat treatment. Through annealing, quenching and other processes, the stress, phase separation or crystallization inside the glass can be eliminated or changed, and the structural state of the glass will be changed.

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First, the grinding and polishing of the glass surface
The plain glass of the early stage is poor in appearance and appearance quality. The surface needs to be ground and polished before deep processing. At present, floatation technology has greatly improved the surface quality of glass, and generally no longer needs to be polished in the processing of building glass and automobile glass, but in the electronic glass, polishing is still a more important process.
Grinding and polishing are two different processes, which are commonly referred to as "polished". During the polishing process, the micro cracks on the surface of glass can be removed and the strength of glass can be improved to a certain extent.
Polishing is divided into mechanical grinding, polishing and chemical polishing.
The main method of mechanical lapping is to grind the surface of the glass with abrasive and grinding discs to remove the micro protruding part of the glass surface. Abrasive discs are usually made of wool felt. The most commonly used polishing material is cerium oxide. The mechanism of glass grinding is generally considered to start with grinding action, and then the fresh surface of the glass is hydrolyzed with water to produce silica gel film. The silica film is then grinded again. After repeated repetition, the surface of the glass is gradually polished into a smooth surface.
There are many factors that affect the grinding and polishing. Grinding speed, abrasive hardness, abrasive particle size and grinding pressure will all affect the grinding effect.
The mechanical effect of glass grinding is the main, so the hardness of abrasive must be greater than that of glass. Optical glass and daily glass are usually made of corundum or emery as abrasive, and flat glass is usually made of cheap quartz sand as abrasive.
Chemical polishing mainly uses the corrosive effect of hydrofluoric acid to polish the surface of glass. Hydrofluoric acid destroys the silicon oxygen structure on the surface of glass and causes the glass surface to peel off to obtain a new clean surface.
Chemical polishing of glass is a chemical reaction between hydrofluoric acid and glass surface, which generates SiF4, NaF, KF, CaF2, and then generates fluorosilicate, because some fluorosilates are not soluble in water, so sulphuric acid is often added to the polishing solution to dissolve some fluorosilicate and prevent the chemical reaction of glass surface from being hindered.
The factors affecting chemical polishing include chemical composition of glass, ratio of acid solution, temperature and reaction time between acid solution and glass.
Because of the limitations of the use and the impact on the environment, the chemical polishing process is basically not used in the processing of float glass, but the method of making process glass using hydrofluoric acid etching is still a lot of use.

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Two. The cutting of glass
High pressure water cutting: the water is pressurized to the super high pressure of 200 ~ 400MPa, and through the wear alloy nozzle of about 0.8 ~ 1mm diameter. The mixture liquid of water and abrasive impact on the surface of glass at high speed, so that the glass surface produces a tiny area of brittle failure, and the glass can be penetrated continuously to form cutting. The CNC water cutting machine can cut all kinds of glass of any thickness. Because the running cost of water cutting is high, the nozzle, the guide sleeve and the high pressure seal are all the frequently replaced consumables, the price is more expensive, and the cutting speed is low and the production efficiency is very low. With the use of high pressure water cutting machine to cut glass for building glass,
Mechanical cutting: manual cutting and automatic cutting
Manual cutting is first cut with diamond and diamond cutters. Because of the high cost of the cutter head, it is gradually replaced by high hardness alloy. This kind of cutting is only used in small batch of glass cutting. It has been replaced by automatic cutting machine in large scale deep processing plant.

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