Glass manufacturers analyze that the raw materials for the production of optical glass are some oxides, hydroxides, nitrates and carbonates, and according to the requirements of the formula, phosphates or fluorides are introduced. In order to ensure the transparency of glass, the content of coloring impurities, such as iron, chromium, copper, manganese, cobalt, nickel, etc., must be strictly controlled. When ingredients are required, accurate weighing and uniform mixing are required. The main production processes are smelting, forming, annealing and inspection.
1. Smelting
There are single crucible batch smelting method and pool kiln (see kiln) continuous smelting method. Single crucible melting method can be divided into clay crucible melting method and platinum crucible melting method. No matter what kind of smelting method is used, it needs to be stirred with a stirrer, and the temperature and stirring are strictly controlled to make the optical glass liquid reach a high degree of uniformity.
2. Forming
The molding methods of optical glass include classical breaking method, rolling method and pouring method, but leakage molding (using a single crucible or continuous melting to flow out the liquid) is more and more widely used, which can directly draw rods or drop molding. Or leakage to form large-sized blanks to improve gob utilization and yield.
3. Annealing
In order to eliminate the internal stress of the glass to the greatest extent and improve the optical uniformity, a strict annealing system must be formulated and precision annealing must be carried out.
4. Inspection
The indicators measured are: optical constant, optical uniformity, stress birefringence, fringes, bubbles, etc.
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