In-process temperature measurement of glass

A non-contact infrared temperature sensor has been launched,which is suitable for measuring the temperature of glass products and surfaces during production, as well as glass substrates used in semiconductor processing and for the manufacture of solar cell panels.

The Optris CT glass infrared thermometer, developed by precision sensor manufacturer Micro-Epsilon, uses a 5.2µm wavelength detector to accurately measure temperatures from 100°C up to 1,650°C of glass surfaces or products, including solar panels, flat glass lines, light bulbs, car glass finishing and glass containers.

The average measuring wavelength of 5.2µm provides a low depth of penetration and enables reflection effects to occur for the infrared measurement of glass. Using shorter wavelengths than this would mean the sensor would measure through the glass rather than measuring the true temperature of the glass itself.

The measurement of temperature of glass surfaces is critical in glass process lines. Take container glass production, for example. The operator must obtain the temperature of the glass gob (molten glass that is poured into a blow mould) to observe the ratio between glass viscosity and gob weight. The mould temperature measurement is therefore critical for balancing the cooling levels of mould shells. Pharmaceuticals manufacturers also require temperature sensors to monitor and control the temperature of the glass when sterilising bottles.

As Ulrich Kienitz, General Manager at Micro-Epsilon Optris states: "In the production of flat glass, automotive glass and construction glass, homogeneity of the complete glass panel is important, particularly when it comes to bending, annealing and tempering zones. The double laser aiming of the CT glass marks the real spot location and spot size up from 1mm at any distance. The 70:1 optics with selectable focus, provide a very small spot size of just 1mm. To put this into perspective, the smallest spot size amongst competing sensor products in this class is 2.5mm. The speed and high resolution optics are also unique for a sensor in this class."

CT glass has a stainless steel sensor head and can be used in ambient temperatures of up to 85°C without cooling and to protect the laser aiming optics, has an automatic laser switch off at 50°C. Cooling and protection accessories are also available for harsh environmental conditions. For example, a water-cooled version is available for ambient temperatures of up to 175°C.

CT glass comes with a separate controller electronics for programming and display of measured temperature. This enables easy wiring of standard analogue outputs 0/4-20mA, 0-5/10V, thermocouple type K or J. There´s also an optional, integrated Profibus DP interface or other plug-in digital interfaces, including USB, RS232, RS485 or CANbus.