Because glass has light transmission and reflection, and is easy to color, it is often used in occasions that have certain requirements for light and color, such as optical instruments and various art decoration. Modern technology has brought new vitality and energy to the glass industry, but also the performance of glass has been greatly improved. We will briefly introduce how the glass tube should be blown into shape and explain the main raw materials for glass products.
First, how should the glass tube be blown into shape
The processing of liquid glass into a product of fixed geometry. When the glass is cooled, the liquid state, the plastic state, and the solid state are connected to the production stage of the glass feed, shape and shape. The viscosity of liquid glass is usually 102.2Pa·s when the material is manually picked. When the mechanical automatic feeding is 102 ~ 103Pa·s, it is equivalent to 10 ~ 100 times the viscosity of the liquid glass when it is clarified. The appropriate viscosity of the glass drop mold is usually 103.5Pa·s, and the viscosity of the release mold should be 106Pa·s, and the glass material is cut, bonded, blown, calented and other molding operations in this plastic range. If the production time is longer, the glass composition must be adjusted to slow the viscosity transition and reduce the tendency to crystallization, so as to avoid hardening too fast and crystallization during the molding process. Commonly used glass forming methods are blowing method, pressing method, drawing method, pouring method, calendering method, etc.
Glass tube blowing method: used to make hollow glass products, such as water cups, utensils, bottles, cans, light bulbs, etc. When manual blowing is used, the length of about 1.5m hollow iron blow pipe is used, one end is dipped in glass liquid (picking material), and the other end is a mouthpiece. After picking the material, roll it evenly on the rolling plate (bowl) and blow it to form a glass material bubble, and blow it into a product in the mold; It can also be freely blown without mold and then knocked off the blow pipe. When large products are formed, it is necessary to repeatedly pick and roll evenly to collect enough material. During mechanical blowing, the glass liquid flows out from the outlet of the glass melting kiln, forms a set weight and shape of the feed machine, cuts into the initial mold to blow or press into the initial mold, and then transfers into the molding mold to blow into the product. Blowing into the initial shape and then blowing into products called blowing - blowing method, suitable for making small mouth utensils and bottles. Press into the initial shape and then blow into the product of the weighing pressure-blowing method, suitable for making large mouth utensils and thin-walled bottles.
Second, what are the main raw materials for glass products
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① Acid oxide raw materials: there are SiO2, B2O3, Al2O3 and other raw materials. SiO2 is the skeleton of the glass structure in silicate glass. It gives the glass height, good chemical stability, heat resistance and low expansion, but it will increase the melting temperature of the glass and increase the viscosity. The quoted raw material of SiO2 is silica sand or sandstone and quartzite. Adding B2O3 to glass can reduce the thermal expansion of glass, improve the refractive index, heat resistance and chemical erosion resistance, reduce the viscosity of glass at higher temperatures, and improve the viscosity of glass at lower temperatures. The quoted raw material for B2O3 is borax or boric acid. Adding Al2O3 to glass can reduce the glass crystallization tendency and enhance the chemical stability, improve the degree, and increase the glass viscosity. The quoted raw material is usually feldspar with K2O or Na2O and SiO2, and industrial alumina can also be used. Cangzhou Tianchang technology glass products factory has experience in producing various types of high borosilicate glass tubes
② Alkali metal oxide raw materials: Na2O, K2O raw materials. The addition of Na2O and K2O to the glass can reduce the melting temperature and viscosity, but it will make the chemical stability of the glass worse. The quoted raw materials are soda ash (Na2CO3) and potassium alkali (K2CO3).
③ Alkaline earth metal oxide raw materials: there are CaO, MgO, BaO, ZnO, PbO raw materials. Adding CaO and MgO to glass can weaken the crystallization tendency of sodium-silicon glass, enhance the chemical stability, reduce the viscosity of glass at high temperature, and promote the melting and clarification of glass, but the viscosity increases quickly when the temperature decreases, and the molding operation is difficult. The quoted raw materials are limestone (CaCO3) and magnesite (MgCO3), or dolomite containing both CaO and MgO. BaO and ZnO are often added to the glass to adjust the chemical stability and refractive index of the glass, and the quoted raw materials are often industrial ZnO and BaCO3, BaSO4 or Ba(NO3)2. The addition of PbO in glass can significantly improve the refractive index and dispersion, so that the glass can absorb short-wavelength rays, at the same time, the specific gravity is increased, the melting temperature is reduced, and the metal infiltration is good. The quoted raw materials for PbO are red lead and yellow lead or industrial lead nitrate.
In addition, broken glass is also a main raw material, often called clinker, can melt at a lower temperature, contributing to the melting of glass compounds