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Breakthrough in the quality management of toughened glass must start from the strengthening process

Published:2017-4-6

 Glass tempering process has three basic requirements, only to meet these basic requirements to produce qualified products:
First of all, the glass must be heated to the required temperature, the glass surface of the various parts of the temperature to be uniform, the difference can not be too large, the glass surface and the middle can not be too large. To control this master three aspects:
First, according to the load of the electric furnace, select the reasonable heating temperature and effectively control the furnace temperature. In the heating furnace of glass are: conduction, radiation and convection, electric load is not mentioned here refers to the glass cover area of electric furnace, it refers to the relationship between the glass thickness, heating temperature and heating time, heating and tempering electric furnace used in the present most manufacturers generally can be divided into many heating zones very small, each district can be individually controlled by the host computer, under normal circumstances, the electric heating central heating element within the region, the total glass in the heat, in this area has been in the furnace, glass, this is the area of the heating effect is regional, if a district electric furnace heat consumption over heating effect, the temperature in this area began to decline, which is over loading, glass tempering success mainly depends on the minimum temperature of the glass plate The party, once the electric furnace has overload, furnace temperature will decline, resulting in the cooling period caused by cooling the glass broken. The heating temperature setting, according to the toughened glass thickness, tempered glass to be thinner, the temperature must be high, to toughened glass is thicker, the temperature will lower the heating temperature control and operation personnel to understand changes in glass furnace temperature and heating time and temperature relationship the thickness of different values, so I can not clear what kind of temperature setting is best, because the quality is still the choice of temperature depends largely on the original glass. In addition, the measured temperature of the heating system is not the bottom temperature of the roller, but tempering furnace bottom heating element compensation roller average temperature of heat absorption of glass, for this reason, the measured temperature is generally higher, higher than the upper temperature measured by the temperature, so the upper part of the tempering furnace under normal circumstances set to be higher than the lower temperature. The following is an example of controlling the temperature of the furnace, if we are in the production, to make the glass from the furnace to the temperature of the cooling chamber 10,
Second, choose a reasonable heating time. The heating power of the furnace is certain, the heating time is often set (heating time furnace) is about 35-40 seconds per mm thickness of glass, such as heating time 6mm the thickness of the glass is about 6 x 38 seconds =228 seconds, this calculation method is suitable for thickness less than 12mm thick glass flat toughened glass, when the thickness of the glass in the 12mm-19mm, the basic calculation method of heating time is 1mm per glass thickness is about 40-45 seconds. The production of bent tempered glass, the heating time of the thickness of the thickness of the glass 2.5-5 seconds. With slotted holes or glass, heating time to this calculation method on 5%. (with sharp angle less than 30 degrees) of the glass and gray glass heating time in this method to 2.5%. below I give you an example to explain the temperature control, heating temperature and time, if we are in the production of toughened 6mm glass, the heating temperature is 705 DEG C, the heating time of 215 seconds, to make the glass from the furnace to the quench chamber temperature of 10 DEG C, there are two ways to realize: the first method is to improve the furnace temperature 10 DEG C; the second method is to increase the heating time, the furnace temperature is kept constant. Note: the temperature is close to the glass tempering temperature before the heating speed is slow, we need to know about such a basic principle: IF furnace temperature setting changes of several degrees, we should also make the heating temperature of the glass is also in the same temperature, it is necessary to change the heating time was t seconds, can make the glass from electric furnace the temperature within T seconds remains unchanged.
Third, in order to realize the uniform heating, the arrangement of the glass in the table is also very important. The reasonable layout of the discharge is mainly to ensure the uniformity of the longitudinal and transverse load in the electric furnace, that is to say, the layout of each furnace and the clearance time of each furnace should be uniform. We want to understand the temperature rule from the furnace to the quench chamber in the process, must understand the glass plate layout depends on factors: when moving along the glass furnace before and after, the edge of the glass roller adjacent the area prone to overheating, the phenomenon of the roll surface between two pieces of glass are easy to occur. In the actual production, if the glass plate in tempering furnace has been put forward movement of the same layout, each roller temperature is relatively obvious, the unloading position change, the glass will in the heating furnace is coved or broken in the quench chamber. In order to get the best tempered effect, we need to remember that note: when put in order to avoid the gap between the vertical glass plate lead to address the furnace temperature is too high, put the glass plate placed on the stage of the film is more reasonable, more easy to keep the roller temperature consistency, that is to say when placed vertical gap, next time to fill this gap. In addition, the gap in the longitudinal long (greater than or equal to 1/2) laid down a glass furnace and its adverse effect than in the longitudinal length of glass is more obvious, this is because of the high temperature of the void start affected in heating, must have sufficient time to make a balanced temperature down.
Secondly, as far as possible to the glass cooling to cool the fastest, the cooling rate depends on other properties in the thickness of the glass and glass, two surface cooling glass to be balanced; the ideal cooling medium stage tempering process is dry cold air, the unit area about the cooling capacity is certain, so the cooling capacity 5mm glass needed is equal to two times of 6mm glass, 12mm glass cooling capacity also need is only half of 10mm glass, for this reason, considering the influence of the thickness of the glass to the cooling speed, so you can say: 5mm glass cooling rate is four times of 6mm glass, 1/4. cooling rate of 12mm the glass is only 6mm
Third, in the process of tempering glass to stop the movement, the glass surface can not scratch and deformation of the traces left. This movement include glass in the heating furnace thermal heat pendulum swinging movement, movement is in order to make uniform heating of the glass surface of the parts; also including glass in air-cooled in cold rotary motion, cold pendulum motion to various parts of the toughened glass broken glass to ensure uniform, uniform block. Requirements for the quality of the original plate glass, the original plate glass can not have a layer of miscellaneous, explosion, scratches, bubbles, etc., these conditions can cause the glass in air cooling broken.
Editor: Mammon