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Machine making
Because of the high labor intensity, high temperature and poor condition of artificial forming, most of them have been replaced by mechanical forming except free forming. In addition to pressing, blowing and drawing,
(1) Calendering method, used to produce thick flat glass, engraved glass, glass with metal wire, etc.
(2) Casting method to produce optical glass.
(3) Centrifugal casting is used to manufacture large diameter glass tubes, utensils and large capacity reaction pots. This is to inject glass melt into the high-speed rotating mould, because the centrifugal force makes the glass close to the wall of the mould, and the rotation continues until the glass hardens.
(4) sintering process is used to produce foam glass. It is added foaming agent in glass powder, and heated in covered metal mould. During the heating process, glass forms many closed bubbles, which is a good insulation and sound insulation material. In addition, flat glass is formed by vertical pull-up method, flat pull method and float method. Floating method is a method of forming flat glass by floating liquid glass on the surface of molten metal (tin). Its main advantages are high quality of glass (smooth and smooth), fast drawing speed and large output.
4. After annealing, glass undergoes intense temperature and shape changes during forming, which leave thermal stress in the glass. This thermal stress will reduce the strength and thermal stability of glass products. If it is cooled directly, it is likely that it will break itself in the process of cooling or later storage, transportation and use (commonly known as the cold explosion of glass). In order to eliminate cold explosion, glass products must be annealed after forming. Annealing means holding or slowly cooling for a period of time in a certain temperature range to eliminate or reduce the thermal stress in glass to the allowable value. |
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