In the glass industry in the production process, often need to be transparent and opaque objects temperature, so temperature measurement and control is one of the very important and necessary means. Opaque objects, including mold, domes and glass melting furnace wall. Non-contact infrared temperature measurement because of its simple operation, fast response, aging, drift of small, flexible configuration, the solution does not pollute the glass on factors such as attention. In particular, the measurement of glass bit, in principle, the temperature of the glass bit is only through non-contact temperature measurement can be obtained.

The physical properties of glass

Glass is transparent to visible, near infrared spectroscopy in the spectral range, the wavelength of its emission rate and glass thickness. When the spectral range is between 5 ~ 8μm, the highest rate of its launch, so the temperature in the range of the glass can be reliably measured. Measurements consistent with the glass surface temperature has nothing to do with the thickness of the glass, in this context there are basically no radiation. In order to avoid measuring the impact of the air surrounding environment, thermometer using only a very narrow band of infrared spectra. High-quality thermometer only window in the spectral range of the so-called work environment, because there will not be caused by air humidity or carbon oxide absorption of infrared radiation, thus avoiding the measurement of distances by air humidity or changes in measurement caused by temperature error. Narrow range of 5 (about 5μm) used to measure the surface temperature. Thermometer generally 5.14μm spectral range, because in the region attempting the hot exhaust combustion does not affect the measurement.

For other application, measurements of the temperature inside the glass because the glass near the surface layer influenced by convection. It should be measured after the glass is melted, you need to use the near infrared range of the thermometer. Because different wavelengths are also different to the penetration depth, thermometer depends on the choice of glass thickness. Glass furnace, tin bath and annealing kiln non-contact temperature measurement in the glass furnaces are increasingly replacing traditional thermocouple. Thermocouple thermometer, compared with a high temperature and corrosive environmental conditions will soon be aging and drift, in order to protect the thermocouple, platinum metal in some places do need to protect the casing, so the cost will be increase in many. Specifically for this area, no cooling system in the environmental temperature reaches 250 ℃, can work through the use of fiber optic pyrometer that can significantly reduce installation and operating costs, fiber can be protected with sturdy stainless steel housing, can reach up to 30 meters. Installation of the required installation accessories such as branch angle, air cleaning, peep tube (can be used until the 1200 ℃).

Measuring the temperature of the glass mold

Measuring the temperature of the glass mold with a fast infrared thermometer required response time, because the glass mold will open and close very fast speed. Because here is to measure the temperature of metal objects, the thermometer should be in the shortwave infrared spectral range of sensitivity, response time to within 1 to 2 milliseconds. In addition to 0-20mA or 4-20mA output, the measured value can also choose to serial interfaces, so that data processing by computer.

Process measurement of glass drip

As the beat is very short, you need to use the thermometer response time soon, but also must be able to measure the internal temperature of the glass bit by bit, because the glass surface temperature influenced by environmental conditions, it does not accurately measure the surface temperature. Depth of penetration of the glass thermometer in the spectral range is determined, the choice of the time and according to the type of glass the size of the bit decision. Typically the maximum temperature values by means of short-term memory to maintain and display. Digital infrared thermometer, which measures the automatic glass production line in the bits of glass in the internal temperature, response time is 10 ms.

Measuring the temperature of flat glass production

Infrared temperature measurement is used in flat glass production line in the tin bath and annealing kiln process. The temperature for the glass we can use in the 5μm spectral sensitivity of the thermometer, that is only the surface temperature measurement of glass. As mentioned above, in the spectral range of radiation is very low, so that the radiation heat rays do not actually measure the impact.

Measurement of glass deep processing and bulb production in the temperature

Surface temperature of the bulb glass production, glass bending and annealing and thermal burn during the forming process is changing the parameters of our concern. Because here the temperature to be measured has nothing to do with the thickness of the glass, we can use the spectral sensitivity of the thermometer in the 5μm.