Let's talk about the improvement of glass quality
The systematic management of float glass quality is the foundation for the stability and continuous improvement of glass quality. The following is a brief summary of the management requirements of each process link according to the process flow, and we will discuss with you briefly and do not hesitate to teach you what is lacking or wrong.
1. Raw material control
1. Precise control of ingredients: Accurately analyze and prepare the chemical composition of major raw materials such as silica sand, soda ash, and limestone. There are differences in the composition of raw materials in different origins, and it is necessary to purchase and use them in strict accordance with the formula requirements to ensure the stability of the glass composition. For example, the silica content in silica sand should be kept within a specific range, and small deviations may affect the melting point, viscosity, and final properties of the glass.
2. Strict restrictions on impurities: Impurities in raw materials, such as iron, titanium, etc., even trace amounts will have a significant impact on the transparency and color of glass. Magnetic impurities and other harmful impurities in raw materials are removed through processes such as magnetic separation and flotation, and the impurity content is regularly tested to ensure compliance with quality standards.
3. Raw material homogenization treatment: pre-homogenization yard, horizontal stack vertical picking, horizontal vertical picking, multi-point grabbing orMultiple warehouse matching and other methods to fully homogenize raw materials. Make the raw material composition of each batch put into production uniform and consistent, and avoid the unstable glass quality caused by raw material fluctuations. Switching batches should be tested in advance to adjust ingredients according to usage progress.
2. Production process monitoring
1. Melting process monitoring
o Precise temperature control: The glass melting temperature is usually 15 to 60°C - 1610°C (infrared temperatureMicro-temperature fluctuations will affect the uniformity and clarification effect of the glass liquid. The temperature of the melting kiln is monitored in real time using high-precision thermocouples, and the fuel supply is adjusted through the automated control system to ensure stable temperature.
o Atmosphere Regulation: The atmosphere within the melting kiln is crucial for the quality of the glass. Under the oxidizing atmosphere, iron impurities exist in a high valence state, making the glass lighter. The atmosphere of reduction is the opposite. According to the requirements of glass varieties, the ratio of combustion air and fuel is accurately adjusted to control the atmosphere in the melting kiln.
o Melting time and flow rate: ensure that the glass liquid has sufficient melting and clarification time in the melting kiln, and stabilize the discharge flow rate of the glass liquid. By adjusting the opening of the flow gate, stabilizing the flow channel temperature and the kiln pressure of the cooling section, Make the flow of glass liquid uniform and stable, and avoid the glass liquid with large temperature fluctuations from entering the molding process.
2. Molding process monitoring
o Tin tank temperature and atmosphere: The temperature of the tin tank gradually decreases from the inlet to the outlet, and it needs to be controlled precisely in sections. At the same time, maintain the reducing atmosphere in the tin tank to prevent the oxidation of the tin liquid from affecting the surface quality of the glass. The infrared thermometer was used to monitor the outlet temperature of the tin tank (610°C) to maintain the desired atmosphere by passing a protective gas (such as a mixture of nitrogen and hydrogen) into the tin tank.
o Pull speed and thickness: The pull speed is closely related to the thickness of the glass, and the two need to be accurately matched according to the production specifications. The pulling speed and width of the glass are controlled by equipment such as the edge pulling machine, and the glass thickness is monitored in real time by laser thickness gauge, and the pulling speed is adjusted with feedback to ensure uniform glass thickness.
o Flatness detection: Optical flatness testing equipment is used to detect the flatness of the glass surface in real time. Timely detect the waves, warping and other problems caused by the fluctuation of the tin liquid, uneven pulling and other reasons, and adjust the equipment parameters.
3. Annealing process monitoring
o Temperature system: Formulate a reasonable annealing temperature curve to gradually cool the glass and eliminate internal stress. According to factors such as glass thickness and composition, the temperature of each section of the annealing kiln is precisely controlled. For example, thick glass should cool down more slowly than thin glass.
o Stress testing: Use a stress gauge to regularly inspect glass sectionsstress and surface stress, ensuring that the stress value is within the allowable range. If the stress is too large, the glass is prone to cracking during subsequent processing or use. According to the stress test results, the annealing process parameters are adjusted.
3. Finished product testing
1. Appearance inspection
o Dimensional specifications: Use calipers, tape measures, and other tools to measure the length, width, and thickness of the glass to ensure that it meets the dimensional tolerance range specified by the product standard. Note that the measuring tool should be calibrated regularly or every shift to prevent excessive deviations from causing dimensional errors.
o Surface defects: through manual visual inspection,Automated inspection equipment to check the presence of glass surfacesbubbles, stones, scratches, pockmarks and other defects. For different uses of glass, the degree of tolerance for surface defects is different, such as the surface defect standards of architectural glass and electronic glass are quite different.
2. Performance testing
o Optical performance: detect the optical indicators such as light transmittance, reflectance, and color of the glass. Use spectrophotometers and other instruments for accurate measurement to ensure that the optical properties of the glass meet the requirements of use, such as architectural lighting glass needs to have high light transmittance.
o Mechanical properties: The mechanical strength of the glass is tested through impact test, flexural strength test and other methods. Understand the performance of glass when subjected to external forces to ensure its safety and reliability in actual use.
4. Quality improvement
1. Data collection and analysis: Establish a complete quality data collection system, covering raw materials, production process parameters, finished product testing results and other data. Use statistical analysis methods, such as control charts, causal charts, etc., to find out the causes and laws of mass fluctuations. For example, key parameters in the production process are monitored through control charts to detect abnormal fluctuations in time; Use causal diagrams to analyze the potential factors of defects in finished products.
2. Continuous improvement measures: Formulate targeted improvement measures based on data analysis results. for quality problems caused by equipment failure, timely repair or update equipment; Due to the quality fluctuation caused by unreasonable process parameters, the process parameters should be optimized. Regularly evaluate the effect of improvement measures to form a closed-loop management of quality improvement. At the same time, employees are encouraged to put forward quality improvement suggestions, reward effective suggestions, and create a good atmosphere for all employees to participate in quality improvement.
