production process：
It mainly includes the steps of batch preparation, melting, forming, annealing and post-processing.
batch preparation
First, the raw materials are pre-processed, including the crushing of bulk raw materials, the pre-drying of wet raw materials, and the iron removal of iron-containing raw materials. The size of the crushed particle is preferably 0.25-0.5mm. Too coarse particles are not easy to be fully melted, and residual powder stones or silicon-rich nodules will be formed in the glass; too fine particles are easy to fly or agglomerate into clusters. The raw materials with a certain particle size are accurately weighed according to the formula, and then mixed with a drum, paddle or disc mixer.
melt
The glass batch is melted and clarified at high temperature to form a uniform glass liquid without bubbles and stones. The melting temperature of the glass batch varies with the composition, but is usually 1300-1600°C. The batch material undergoes a series of physical and chemical reactions at high temperature and gradually melts completely. As the temperature increases, the viscosity decreases significantly, and a large amount of air and the gas generated by the decomposition of the raw materials rise from the melt and escape, making the melt clear. While removing bubbles at high temperature, the chemical composition of the glass liquid tends to be uniform, and when necessary, mechanical external force is added to stir. After the clarification and homogenization are completed, the temperature is lowered to make the glass liquid uniformly reach the viscosity suitable for the molding requirements.
Melting takes place in a glass melting furnace. Continuous melting in pool kilns for mass production. The batch material is added at one end of the kiln, and the formed glass liquid is discharged at the other end. It is melted intermittently in a crucible kiln in small batches.
forming
The glass liquid is processed into products of fixed geometry. When the glass is cooled, it changes from a liquid state, a plastic state to a solid state, connecting the production stages of the glass supply and reclaiming, shaping and shaping. When picking materials manually, the viscosity of glass liquid is usually 102.2Pa·s; when mechanical automatic feeding is performed, it is 102-103Pa·s, which is equivalent to 10-100 times the viscosity of glass liquid when it is clear. The suitable viscosity of the glass droplet into the mold is usually 103.5Pa·s, and the viscosity should be 106Pa·s during demolding. In this plasticity range, the glass frit is subjected to shearing, bonding, blowing, calendering and other forming operations. If the production time is long, it is necessary to adjust the glass composition so that the viscosity transition tends to be moderate and the crystallization tendency is small, so as to avoid too fast hardening and crystallization during the molding process. Commonly used glass forming methods include blowing method, pressing method, drawing method, casting method, calendering method, etc.
Glass tube blowing method: used to manufacture hollow glass products, such as water cups, utensils, bottles, jars, light bulbs, etc. For manual blowing, a hollow iron blowing pipe with a length of about 1.5m is used, one end is dipped in glass liquid (picking material), and the other end is a blowing nozzle. After picking the material, roll it evenly on the rolling plate (bowl) and blow air to form glass frit, which is blown into the product in the mold; it can also be freely blown without a mold, and finally knocked off from the blow pipe. When large-scale products are formed, it is necessary to repeatedly pick and roll evenly to collect enough material. During mechanical blowing, the molten glass flows out from the outlet of the glass melting furnace, and is formed into gobs of set weight and shape through the feeder. product. The blow-blowing method, which is blown into a preliminary shape and then blown into a finished product, is suitable for making small-mouthed utensils and bottles. The weighing-blowing method of pressing into a primary shape and then blowing it into a finished product is suitable for making large-mouthed utensils and thin-walled bottles and cans.
