The production method of glass lenses may not be a secret to those in the industry. But many friends who have never been in contact with optical glass lenses will be very curious, how are optical glass lenses produced?
This article introduces the production method of optical glass lenses
The raw materials for the production of optical glass are some oxides, hydroxides, nitrates and carbonates, and according to the requirements of the formulation, 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.
①Smelting 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 glass liquid reach a high degree of uniformity. Clay crucibles can smelt most crown and flint glasses with low cost, and are used when the melting temperature of the glass exceeds the use temperature of platinum. The platinum crucible can smelt high-quality glass that has a serious erosive effect on the clay crucible, such as heavy crown, heavy barium flint, rare earth glass and fluorine phosphorus glass. The platinum crucible is heated by electricity, generally using a silicon carbon rod or a silicon molybdenum rod electric furnace. However, high-frequency heating can be used to manufacture glass that has a large tendency to crystallization, requires rapid cooling, and has certain requirements for atmosphere.
Since the 1960s, various countries have successively adopted continuous kilns lined with platinum for melting, which has greatly increased the output and quality of optical glass, which is the main trend of the development of optical glass production technology.
②The molding methods for molding optical glass include classical crucible method, rolling method and pouring method, but leakage molding (using a single crucible or continuous melting to flow out the material liquid) is more and more widely used, which can directly pull the rod or drop the material. Pressing or leaking 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.