The temperature control of the ion nitriding furnace is indeed a difficult task, because there is a certain deviation between the temperature transmitted by the thermocouple and the instrument display, and this deviation is not small, some of which reach more than 100 degrees, and the most difficult thing is the furnace temperature. It is not uniform, and the temperature difference between different parts is also large. It is more difficult to determine the temperature of the place far from the thermocouple. Therefore, it is necessary to rely on experience to clear the approximate difference between the temperature displayed by the furnace meter and the actual temperature, and the range of the furnace temperature difference.

The temperature field in the ion nitriding furnace is not uniform. It is recommended to place one near the thermocouple when mounting parts. In this way, the measured temperature is close to the temperature of the part. Otherwise, it is possible to have a difference of more than 100°.

1. The size of the viewing hole on the device. In theory, the infrared instrument only needs a small opening to detect the object to be measured, but furnace equipment requires other peripheral equipment to obtain the working environment, such as vacuum pumps for vacuum furnaces, continuous carburizing furnaces, small Continuous carburizing furnace, so the furnace body will vibrate to a certain extent. If the observation hole is too small, it is likely to cause the infrared radiation to be deflected when the infrared instrument is vibrated, so that the real workpiece temperature cannot be obtained; to solve this problem, it is necessary to start from the The size of the observation hole and the fixing method of the infrared instrument are started at the same time. Since the internal temperature of the sealed furnace equipment is very high, most of the infrared instruments are installed outside the equipment using a bracket, but the bracket will play a role in amplifying the vibration, so try not to use it. The threaded fixing method is not conducive to adjusting the direction of the ray, so a suitable installation method must be selected.

2. The material and opening of the thermal insulation material in the furnace. High-temperature furnace equipment will use a layer of thermal insulation material between the heating body and the furnace wall to reduce power consumption, enhance thermal insulation performance in the furnace and protect the accessories installed on the furnace wall such as sealing rings. As the temperature of the furnace increases, the furnace-type insulation layer at 2000°C will reach more than 150mm, so it takes some brains to make the infrared rays pass through the insulation layer smoothly. The hole opened on the heat insulation layer corresponds to the position of the observation hole on the furnace wall. It does not matter if the observation hole on the furnace wall is larger, but the observation hole of the heat insulation layer is too large, which will cause running temperature. Observing the furnace wall The hole will also be in danger of burning out, so the opening of the insulation layer should not be too large; another point should consider the thermal deformation of the insulation material, sometimes the openings on the insulation material and the furnace wall look cold The correspondence is very good, but after the temperature is high, the thermal insulation layer will be deformed due to thermal expansion, which will move the position of the opening, causing the rays that could have passed through the opening to shine on the thermal insulation material, and the measured temperature will be different. Correct.

3. The placement of the object to be measured. The ideal state is to let the infrared rays just irradiate the surface of the object to be measured. If the object to be measured in the furnace is a whole piece, there will be basically no problems. If it is a pile of small pieces and there is a gap between them, it is necessary to Pay attention to see if the ray will pass through the gap between the workpieces and irradiate the opposite insulation material, so the measured temperature value will also have a large deviation.