Vacuum Furnace Temperature Uniformity Test

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The temperature uniformity of the heat treatment furnace reflects the degree of deviation of the temperature of each test point in the effective heating area of ​​the equipment furnace relative to the control set temperature. The equipment level can be divided by the temperature uniformity, which reflects the temperature control ability of the equipment. The temperature uniformity test requires a series of measurements of the temperature change in the effective heating zone of the heat treatment furnace by means of a calibrated and qualified measurement system. The temperature uniformity measurement system usually consists of temperature sensor, compensation wire, measuring instrument (system device) and temperature measuring frame.

Thermocouple:

Vacuum furnaces generally use K-type thermocouples and N-type thermocouples as temperature sensors for temperature uniformity testing. The vacuum furnace should use an armored thermocouple, or a thermocouple with a protective tube can be used. The protection tube generally uses a metal protection tube, because of its high sensitivity to temperature changes, when the working temperature exceeds 1300 ℃, a non-metal protection tube should be selected. It should be emphasized that the protection tube should have good air tightness.

Compensation wire:

The compensation wire is a wire with an insulating layer with the same nominal value of the thermoelectromotive force of the thermocouple. The reference end of the thermocouple can be extended to a place far away from the heat source or the ambient temperature is relatively constant, so as to reduce the interference of the environment on the temperature measurement and ensure the measurement temperature is stable. By using conversion devices such as connectors, plugs or sockets with thermal characteristics corresponding to the thermocouple, the connection between the compensation wire and the thermocouple is more convenient, and the applicability to the structure and size changes of the heat treatment equipment is stronger.

Thermometer

Temperature measuring instruments are divided into circuit detectors, furnace temperature trackers and automatic patrol instruments. There are differences in the degree of automation among the three.

Temperature measuring rack:

Usually stainless steel or high temperature alloy, titanium alloy and other materials are used to make the temperature measuring frame, which needs to be degassed before use to prevent the vacuum furnace from being polluted during the heating process.

Temperature measurement method:

The particularity of the temperature uniformity test of the vacuum furnace is that the sealing of the furnace must be ensured while the temperature is measured. Therefore, the selected measurement method is usually related to the structural design of the vacuum furnace. The traditional way of measuring the temperature uniformity of vacuum furnace is to use the temperature measuring frame to arrange thermocouples, the general flange structure to realize the insertion or extraction of thermocouples, and the rubber sealing ring to ensure the vacuum degree in the furnace.

Summarize:

The temperature test of the vacuum furnace must take into account the two important indicators of vacuum and temperature. The temperature uniformity test requires a series of measurements of the temperature change in the effective heating area of ​​the heat treatment furnace through a calibrated and qualified measurement system.