Analysis of the situation and causes of tempering glass produced by tempering furnace

The following is the toughening furnace production of tempered glass usually encountered circumstances and cause analysis.
(1) if the glass is out of the furnace, the glass breaks in the hot cooling time in the wind grid. This indicates that the heating temperature is too low or the heating time is too short, which causes the residual stress in the original piece to be completely removed, or the glass surface temperature is uneven to break the glass, if the glass burst in the cooling stage, it is due to the excessive wind pressure or the raw material. The material is defective, resulting in too many holes and holes on the glass.
(2) if the glass is cooled, the surface waves: This is due to the high furnace temperature, the long heating time, or the poor glass material itself.
(3) there are pitting on the surface of glass: this can be divided into two cases:
A if the pitting is star shaped, it is due to the normal appearance of the initial production stage of the new furnace or because the surface of the ceramic surface is dirty or the surface of the glass surface is not clean or the surface of the cooling roller of the curved wind gate is not clean.
B if the pitting is dense orange peel, this is due to the excessive surface temperature after the glass is released, and the surface temperature of the tempered thick glass enters the ceramic roller is too high.
(4) the central part of the glass is a white mist or a change in the optical aspect of the glass. It is easy to appear in the glass before each production, because the surface temperature of the ceramic roller is too high; the interval of the inlet is too long; the lower temperature is set too high; the heat balance blowing pressure is too low. The main reason is that the effect of the heat released from the roller is greater than the heat released by the heating element, so that the glass is first bent upward in the heating furnace, which makes the roller and the middle part of the glass too large.
(5) there is a crack on the tempered surface: This is due to the low temperature of the glass from the heating furnace to the wind gate; the turning speed of the bending steel is too fast; the air leakage in the arc forming process; the ambient temperature of the glass before production is too low; the curved steel thick glass is half small, and the front angle of the glass front is too small.
(6) the two ends are bent upward. The main reason is that when the glass enters the cooling section from the heating section, the surface temperature of the glass is higher than the lower surface, and the cooling speed on the cooling section is slower than the cooling rate below. Therefore, the upper air pressure can be increased by increasing the lower temperature or reducing the blowing distance of the upper wind gate, too. It can reduce the lower blow pressure or blow distance. If the furnace is flat and the upward bending is made, the lower temperature should be raised, especially when the furnace is full.
(7) double bend: the common saying "flash" is that the bending direction is not fixed, and the force will bend toward the other side. The reason is that when glass enters the cooling section from the heating section, the temperature of the middle glass is lower than the edge temperature, and the continuous production (mostly thin plate glass) appears more, and the glass back warp and the middle drum can be seen in the furnace. Without contact with ceramic rolls, the lower temperature can be raised, and the surface temperature of the ceramic roller can be greatly higher than the upper temperature. If the high temperature fan can increase the waiting frequency to increase the surface temperature of the ceramic roller, the heating temperature of the middle part can be improved by the advantage of the matrix heating.
(8) self detonation of glass: the fundamental reason for self detonation is that the original film is in the NIS crystal. Because of the rapid cooling, the high temperature crystal NIS crystal has not yet been converted to the cryogenic phase, so the NIS in the tempered glass at normal temperature has a tendency to convert to the low temperature, while the conversion of the crystal is accompanied by the volume expansion and the internal stress in the tempering. The greater the force, the smaller the critical diameter of the NIS crystal will change the crystal type, that is, the probability of self explosion is greatly increased. If the difference of the surface stress of the same glass is larger, the probability of the transformation will be increased. A lot of data show that the tempered glass with internal stress less than 140Mpa is not easy to explode, so the measure is that 1. will be tempered. Control within a certain range; 2. improve the uniformity of tempering.
(9) blast furnace: 1. because the glass warped in the swing and vibrate to make the plate split open. This type of blast furnace fragment is larger, and many measures are taken on the 12 glass. If the glass is a rectangle, it is placed vertically to reduce the warpage of the glass, because the warping direction is along the direction of the ceramic roll; B. will be used in front of the A. before entering the furnace. The surface temperature of the ceramic roller is lowered; C. reduces the heating reciprocating speed, and uses the "low speed time" and "low speed" parameters. 2. as a result of excessive heating, the temperature gradient is produced in the direction of glass thickness to produce pressure stress on the glass surface, which produces Zhang Yingli, defects or holes in the glass, which produces a deep frying furnace, which is small, like the steel, and has obvious stress layer and stress line. The type of blast furnace appears in 15 and 19 production. Measures should be taken to reduce the surface temperature of the ceramic roller by using 660 A. B. at low temperature and use the side bar to blow the furnace. C. if the hole is both sides of the hole closer to the furnace with a small side bar close to the hole, in order to reduce the velocity of expansion on both sides of the hole and the speed of shrinkage when cooling. D. as far as possible to fill the furnace into the furnace, quickly reduce the furnace temperature, heating slowly at the beginning of heating, 500S temperature gradient will be reduced after the rapid heating. E. do not use high temperature blower or balance valve to prevent glass from warping, and make the top crack on top of ceramic roller when swinging.
(10) the glass evenness of different positions in the same furnace is quite different.
Especially with the working thin glass, because the influence of the wind gate on the thin glass is much bigger than the heating section, it is likely that the wind knife in the wind gate has the sundries in the wind blade.