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How Does Special Optical Glass Improve The Annealing Temperature And Increase The Strength

Edit:Shanghai TaiYang Technology Co.,Ltd      Date:Oct 16, 2017

How does special optical glass improve the annealing temperature and increase the strength

As a result of the intense temperature change, the annealing of the underlying reasonable glass in the molding process. So that the temperature gradient inside and outside the wall, and due to the finished product shape, thickness, degree of cooling and other glass mechanical differences, resulting in products produce irregular thermal stress. This thermal stress can reduce the mechanical strength and thermal stability of the product, but also affect the optical uniformity of the glass, if the stress exceeds the ultimate strength of the finished product, it will break itself. So there is uneven thermal stress in the glass product is a serious error. optical glass Falling annealing is a heat treatment process that allows the thermal stress in the glass to be eliminated or reduced to the allowable value as much as possible. In addition to glass fiber and thin-walled small hollow products, indeed all glass products are necessary to perform annealing. Glass products in the thermal stress, according to its existence characteristics, divided into temporary stress and permanent stress two.

Due to its poor thermal conductivity, ① temporary stress. Glass is heated or cooled below the strain point temperature. Each part will form a temperature gradient, resulting in a certain thermal stress. This thermal stress, with the existence of the temperature difference between the greater the temperature difference, the greater the stress, and with the disappearance of the temperature disappeared. This thermal stress is called temporary stress.

But in the temperature before the imbalance should pay attention to the temporary stress can be self-dispelling. When the stress value exceeds the limit strength of the glass, optical glass the glass will break itself, so the glass in the brittle temperature range of heating or cooling rate should not be too fast.

Optical glass from the thermal stress generated by the temperature, ② permanent stress. When the glass starts to cool from above the strain point temperature. Glass cooled to room temperature, the internal and external temperature disorders, and can not be completely dissipated, the glass still like a trace of some of the stress, optical glass this stress is called water stress. The magnitude of the permanent stress depends on the cooling rate of the finished product above the strain point temperature, the glass viscosity, the heat shrinkage factor, and the thickness of the product.

Is to have a permanent stress of the optical quartz glass products re-heated to the glass internal particles can move the temperature, the glass annealing. The displacement of the controlled particles causes the stress to be dispersed (called stress relaxation) to eliminate or diminish the permanent stress. The stress relaxation rate depends on the glass temperature, the higher the temperature, the faster the relaxation rate. Therefore, a suitable annealing temperature range, the glass is the key to the quality of the key to the actual production process, the complete elimination of permanent stress is impossible through the annealing wish the residual stress increase or homogenization within the minimum control to enhance the glass machinery Strength and thermal stability of the characteristics of thick glass annealing thick glass production pattern is important to reverse the method and baffle method two, optical glass where important negotiations baffle method to produce thick glass when the annealing. The main principle of the thick glass produced by the baffle method is to "thaw" the glass fence area. An important feature of its annealing is as follows. This method produces thick glass due to the cold side of the glass, the thickness of the edge of the glass is thin, so the side of the compressive stress is large. 2. The thicker the glass, the longer the heat is in the glass body. 3. In order to meet the cutting request, it is necessary to reduce the steel stress. 4. To prevent the edge in the post-annealing area cooling too fast, the edge of the child at the beginning of a higher tensile stress, resulting in longitudinal loss.

Control the thickness of the edge of the thickening of the glass and the thickness of the glass curve is closely related to the improvement of annealing thickness curve. Especially the thickness of the edge of the glass plate, the individual requirements of the thickness curve to ensure that the edge of 25 mm thickness than the thickness of about 1 mm thin. In the past, I often can not do this, mainly because the edge is too thin to reduce the load to reduce the steel stress thick glass production due to the increase in thickness, leading to heat in the glass body through the connection time delay, if the production under high load Thick glass will lead to increased vitreous stress in the glass body, to the back of the cutting and customers to change the difficulties, but also make the annealing caused by trouble, optical glass increased burst, reduce the yield. Therefore, it is necessary to reduce the load to meet the appropriate tempering stress in the A zone to increase the gas spray gun and increase the chilled water after the washing machine. As mentioned above, the advantages and disadvantages of the edge stress directly affect the slitting interest, which requires the glass in the annealing furnace Area A and Zone B as far as possible to the edge of the temperature, because the entrance of the annealing kiln has been added to the gap gun, is to add a pair of gas gun in the A zone is a good choice to advance the glass edge of the tensile stress. Similarly, after the addition of chilled water in the washing machine is also abnormal can improve the edge of the right and Zhang stress, to improve the purpose of slitting

Its heat to keep the glass in the longer time, the import of optical quartz glass properly down A zone temperature as mentioned above, the thicker the glass. Echo the time it is longer. Since the annealing length of the annealing furnace is flowing, it is possible to delay the annealing zone by properly lowering the temperature of the zone A, and finally achieving the purpose of reducing the stress of the glass to increase the edge gas zone. Thick glass production of the largest loss of the glass longitudinal, if the occurrence of longitudinal cracks, then half an hour, many times there may be a few hours, so I want to prevent a similar situation in the production of thick glass, you can May be to improve the thickness curve; optical glass to control the edge thickness; reduce the load; A area to increase the gas gun and in the washing machine after the increase in chilled water; properly down A zone temperature; RET area to increase the edge of the gas gun and other measures to achieve the best yield and Best cutting quality.


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