Low-emissivity (Low-E) glass, enhancing building energy efficiency, challenges traditional IR devices measuring temperature from above. The Top-Down Glass Inspection System (GIS) solves this by using high-resolution infrared cameras above the tempering line and a reference pyrometer below for emissivity correction. This dual approach ensures accurate temperature measurements, detects defects, and adjusts heating or cooling based on temperature distribution. The system employs Optris PI 640i G7 cameras, designed for the glass industry, with a spectral response of 7.9 μm and a temperature range of 150 °C to 1500 °C. Pre-assembled for easy installation, it connects to a PC via Ethernet and includes license-free PIX Connect software for flexible and comprehensive IR imaging.

Low-emissivity (Low-E) glass, designed to enhance energy efficiency in buildings, presents significant challenges for traditional infrared (IR) devices, which measure glass temperature from above as the panes exit the furnace. Commonly used for windows and facade components, Low-E glass is typically constructed as multi-pane insulating glass with a very low emissivity coating. This low emissivity complicates accurate glass temperature measurement by traditional infrared line scanner devices, as they generally target the coated side from above, leading to potential inaccuracies in temperature readings and quality control issues.

The Top-Down Glass Inspection System (Top-Down GIS) has been developed to address this issue. This system aims to provide accurate temperature measurements of Low-E glass during production. Unlike the Bottom-Up GIS, which measures from beneath the glass, the Top-Down GIS measures from above while using an additional reference pyrometer from below to correct for emissivity. This dual measurement approach ensures that defective or inhomogeneous surfaces can be detected and allows for adjustments in heating or cooling based on the temperature distribution, ensuring optimal quality and consistency in glass production.

Referencing from below is necessary for two reasons: the coated upper side of the glass has low emissivity, making accurate measurement difficult, and there is often insufficient space for cameras to measure from below due to the low furnace height. This setup would require more than one camera, and a wide-angle view could influence measurements differently. By using an additional reference pyrometer from below, the Top-Down GIS can correct for emissivity variations and ensure accurate temperature readings, even in the confined space of a furnace. This dual-camera approach enhances the system’s ability to detect defects and maintain precise control over the glass production process.

The Top-Down GIS employs two high-resolution infrared cameras positioned above the tempering line to measure the temperature of the top side of the glass. This system, particularly the Top-Down GIS 640 R, includes temperature referencing from a sensor below and automatic emissivity correction for both standard and Low-E glasses. It was specially developed for process control in glass tempering machines. The linescan function with the PI camera from above, combined with reference measurements from the pyrometer below, is essential because Low-E coatings minimize IR radiation through the glass but not the thermal effect of visible light. This dual-measurement approach ensures accurate temperature readings and effective process control, maintaining the quality and consistency of the glass production.

The infrared cameras used in the Top-Down GIS, such as the integrated PI 640i G7, have been specifically developed for the glass industry. These cameras have a spectral response of 7.9 μm and a temperature range of 150 °C to 1500 °C, making them suitable for a wide range of applications in glass production, refining, and further processing. Combining these cameras with the advanced reference pyrometer ensures accurate and reliable temperature measurements across various glass products, including glass panes. The high resolution enables precise temperature mapping and comprehensive coverage of the entire glass surface, ensuring no area is left unchecked.

The system includes a digitally controlled lens protection system (DCLP), which eliminates the need for extra air purging. This glass inspection system allows temperature differences during glass hardening processes to be quickly detected, thus avoiding rejects and providing automatic quality monitoring. The DCLP ensures that the lenses remain clean and operational, enhancing the overall reliability and efficiency of the system in maintaining high-quality glass production standards.

Optris infrared cameras come with license-free PIX Connect software, enabling the cameras to operate as line scan cameras. Traditional line scanners, used in the glass industry for various measurement procedures, are bulky, expensive, and require significant manual effort for setup. In contrast, the infrared camera system is compact and cost-effective, offering several benefits. The software allows for flexible positioning and dimensioning of the scan line, providing complete IR images for valuable additional information, especially during setup. This flexibility simplifies the installation process and enhances the overall efficiency and accuracy of temperature measurements in glass production.

The cameras can accurately measure the surface temperatures of moving objects using minimal apertures, a function particularly significant in the glass industry. Since the glass temperature directly impacts its quality, accurate temperature measurement at multiple points during production is crucial. The data collected is transmitted directly to the process control system, enabling real-time adjustments and ensuring optimal product quality. This capability helps maintain consistency, reduces the risk of defects, and enhances the overall efficiency of the production process.

In addition to measuring temperature distribution, the Top-Down GIS calculates the glass surface area. This capability is essential for process control and quality assurance, allowing for a detailed analysis of the glass during production. The system’s ability to provide accurate temperature data helps maintain the quality and consistency of the glass, which is critical for its performance in energy-efficient applications. By ensuring precise temperature monitoring and surface area calculation, the Top-Down GIS supports the production of high-quality glass products that meet stringent industry standards.

The Top-Down GIS is delivered as a pre-assembled system for easy installation on glass tempering furnaces. This turnkey solution simplifies the implementation process, allowing manufacturers to quickly integrate the system into their existing production lines. The system’s design ensures minimal disruption during installation while providing immediate benefits in terms of temperature measurement accuracy and process control. It consists of several pre-wired components ready for immediate use. The infrared glass system is supplied with 24V and connects to a PC via an Ethernet cable. The system can be used directly with the PIX Connect analysis software and a predefined layout, enabling seamless operation and efficient data analysis from the moment it is installed.

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