Float glass runner is an important part connecting the furnace and the tin bath, and it is the throat of the molten glass flowing from the cooling part of the furnace to the tin bath. The molten glass enters the tin bath through the runner and the launder, and enters the annealing kiln through the transition spoke after being formed in the tin bath. In this process, the molten glass (plate) is in direct contact with the gate, lip brick, molten tin, etc., and the quality of the glass is closely related to the bottom brick of the tin bath, so it is easy to form related defects. Hundreds of tons of molten glass at about 1100 ℃ pass through the launder every day, causing erosion and erosion of the launder bricks. The flow channel brick mainly includes the side wall channel brick and the lip brick. Because the lip brick is directly impacted by the glass flow here, it is eroded faster by the glass flow. Once the lip brick is seriously eroded, it will directly lead to defects such as lines, glass bars and bubbles on the glass plate surface, which will seriously affect the quality and output of glass. Sometimes the glass bubbles due to lip tile problems are somewhat close to the bubbles at the bottom of the tank, which is not easy to judge and requires careful observation and analysis.
Bubble analysis
According to the position, shape and size of the bubble, the bubble is preliminarily judged to be the bubble at the bottom of the tank. The appearance of the bubble is directly related to the reduction of the drawing amount, which may be that the brick joint at the bottom of the groove in the high temperature area changes in the process of the reduction of the drawing amount, the temperature of the molten glass breaks the original balance of the brick joint, the molten tin in the brick joint or flows to the steel plate at the bottom of the groove along the brick joint, and the gas evaporated from the residual moisture of the brick at the bottom of the groove is squeezed out, and the bubble at the bottom of the groove on the lower surface is caused by the rise of the gas. Solution to the bubble at the bottom of the
tank: temperature rise and bubble discharge method, temperature reduction and inhibition method
. The temperature rise and bubble discharge method is to raise the temperature at the bottom of the tank first, so that the residual gas can be discharged as soon as possible, and then the temperature can be lowered back. It is not recommended to adopt the method of temperature rise and bubble discharge in this line, mainly considering that the tin liquid may leak to the bottom of the tank bottom brick after temperature rise, which is risky. If the temperature exceeds 150, the molten tin and steel plate will form tin-iron alloy, which will affect the structure of the tin bath. The main measures of the
cooling inhibition method are as follows: the drawing amount is not changed to keep the temperature of the melting furnace stable; the air volume of the high temperature area at the bottom of the tank is increased to cool the temperature at the bottom of the tank in the high temperature area; Turn on the 3 "trough bottom fan to supply air to high temperature, set up a temporary fan and compressed air to cool the 2bay position on the left side, draw out the 2 'water drum in the high temperature area of the tin trough, and further reduce the temperature of the trough bottom in the high temperature area; add tin, and stabilize the tin level in the middle section at 60mm. However, after taking a series of measures, there is no change in the shape, size, position and quantity of bubbles.
The above series of cooling measures for the tin bath do not have the effect of reducing bubbles. After analysis, it is concluded that the cause of bubbles may not be in the tin bath. To this end, first open the Ibay and continue to check, and it is found that there are bubbles coming down from the upstream of the Ibay. Further open the sealing brick under the lip brick and check the lip brick, and it is found that there are cracks in the lip brick, and there is cold glass in the cracks, as shown in Figure 3. After cleaning with a hook and subsequent verification, it was determined that the cause of the bubble was caused by a crack in the lip tile.
Lip tile bubbles are a common type of shaped bubble. According to the information, the glass bubbles formed by the wear, erosion, cracking and defects of the lip brick are also located on the lower surface of the glass plate, generally along the direction of glass pulling, and the horizontal position of the glass plate is relatively fixed. The position of the bubble belt will not change after adjusting the width of the plate and the position of the original plate in the tin bath. Bubbles can be large or small, and the diameter is generally 0.05 ~ 0.5mm. Some bubbles are open, some are closed, and most of them are closed.
This time, the lip brick bubbles are slightly different, one is that the size is too large, and the other is that they are all open. The main reason is that when there is a large crack in the lip tile, the molten glass will infiltrate from the crack and slowly flow down. The temperature here is low and the flow rate of the molten glass is small. Only when it reaches a certain amount, it will drip down. The dripping glass may also be wrapped in the tin bath gas to form bubbles. The cold and hot glass phase will cause the change of gas solubility in the glass, and will also precipitate gas to form bubbles. The dripped cool glass adheres to the lower surface of the glass sheet at the rear of the normal glass sheet root as it is carried out of the glass sheet, forming a lower surface opening bubble. Solve
the problem of
bubbles. The cracks of lip tiles have affected the quality of glass plate surface, and the generation of bubbles and ripples is directly related to it. In order to ensure the stability of glass quality, the best way is to replace the lip tile as soon as possible. However, there is no spare lip brick for the time being, and it will take at least 3 months to order. Therefore, emergency measures should be taken to control the generation of bubbles. The specific scheme is as follows:
(1) The temperature of the flow passage
should be gradually reduced by 3 ~ 10 ℃. After the implementation of this measure, the quality of glass is sometimes good and sometimes bad, and bubbles will still appear intermittently, which lasts for 2 to 14 hours.
And (2) that problem can not be completely sol by making a wat bag to plug the crack
of the lip brick and cooling the flow channel, and the source of bubbles can only be eliminated from the source. Under the condition that the conditions for replacing the lip brick are not mature, it is considered whether the crack can be plugged, so a caulking water bag is designed, as shown in Figure 4. Insert the tip of the plug marked 5 in Figure 4 into the lip tile crack. After the implementation of this measure, the glass bubbles did not appear again until a new lip tile was replaced.
Conclusion
Forming bubble is a defect in the process of float glass forming. Through the analysis of the source of bubbles in float glass production, in the absence of replacement of spare lip tiles, a specially designed water bag was made to plug the cracks of lip tiles, prevent molten glass from passing through the cracks, so that bubbles were no longer produced, and normal production was ensured for a period of time before the replacement of lip tiles, thus reducing the impact on glass quality and output.
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