Completing the Building Envelope
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THE PROBLEMS IN THE PROCESS OF ALUMINIUM ROD PREHEATING
The aluminum rod is preheated before entering the extruder. The traditional idea is that aluminum rods must be heated to solution temperature in heating furnace, but experience has shown that this is not correct to some extent. As long as the aluminum rod is properly cast and homogenized, it is not necessary to reach solution temperature in the aluminum rod preheating furnace.
Some typical problems show when doing temperature measurement in aluminum rod preheating zone:
1. Two-point thermocouple readings will be low
2. Two-point thermocouple routine maintenance is often overlooked
3. Homogenization heat treatment temperature is the key parameter of aluminum rod
4. The operator tends to overheat the aluminum rod
5. The operator tends to reduce the extrusion speed to fine-tune the aluminum extrusion manufacturers temperature.
6. Overheating and slow squeezing all waste preheated energy
Benchmarking companies are aware that the aluminum rod should be heated to the lowest temperature that can be squeezed and that the temperature at the exit of the extruder must be guaranteed to reach its target value. By lowering the preheating temperature of the aluminum rod, the extrusion speed can be raised so that the energy consumption of the furnace is reduced. Practice has proved that such a change can save 15-20% of gas furnace energy consumption.
For gas heating furnace, aluminum bar interval temperature is the use of two-point thermocouple temperature. Because these instruments have high requirements for maintenance, the use of such a meter either requires high maintenance costs or loss of accuracy. In some aluminum extrusion plants, non-contact sensors have been used to detect and control the temperature of the heating zone in the aluminum rod area. Not only does it reduce the reliance on contact thermocouple thermometers, it also reduces maintenance and accuracy issues due to instrument limitations.
In the induction heating system, the infrared temperature sensor is directly aligned with the surface of the aluminum rod, which can directly monitor the temperature, thereby reducing the inconsistency in the use of the two-point thermocouple. Similarly, for gas-fired furnaces, the sensor can be installed at the exit of the furnace (at the entrance to the extrusion barrel) to monitor the temperature of the surface of the aluminum rod. This temperature is also used to correct the temperature deviation measured by the thermocouple or infrared thermometer. Aluminum rod section is the best location for aluminum bar temperature measurement.
For gradient-heated aluminum rods, one sensor can be mounted on the side of the aluminum rod conveyor to monitor the temperature or two sensors can be installed to measure the temperature at each cross-section of the aluminum rod. Accurate Gradient Heating Temperature is very important for continuous delivery of aluminum rods into the extruder. Inaccurate temperature measurement makes gradient heating meaningless.