Temperature control system block diagram

(1) System configuration or The controlled object of this system is an 8-cliff annealing furnace heated by burning natural gas . The natural gas burner adopts the self-contained air mode.
Annealing furnaces are used for heat treatment of actinium materials to change the physical properties of the steel. The measured parameter is mainly temperature, and the measurement range is 0-1000-C. For this purpose,
the 8031 ​​leather sheeting machine is used as the host machine. The principle is shown in Figure 27-46. The temperature value of the measured parameter is measured by the thermocouple Tl to obtain a millivolt signal, which
is converted into an O~5V voltage signal by the transmitter. The temperature of the eight annealing furnaces is measured by a multi-channel switch. The signal is sent to the sample/hold and A/
D converter in a time-sharing manner, and the converted digital quantity is sent to the processor through the I/O interface for analog/digital conversion. After the data is processed in the CPU
(digital filtering, scaling transformation and digital control calculations), it is sent to display on the one hand. And determine whether an alarm is needed} On the other hand, compare with the given value
, and then perform control calculations based on the deviation value. The controller output is converted into a 4-20mA signal by a ^/D converter to drive the electric actuator
to move. When the sampling value (temperature) is greater than the given value, close the natural gas valve, otherwise open the idle door. In this way, by changing the flow rate of natural gas
entering the annealing furnace , the temperature can be controlled. This system can not only perform constant temperature control, but also control according to a certain temperature rise curve through software design . When an ultra-low or high-eye alarm occurs in an annealing furnace in the system, an audible and visual alarm signal will be emitted to remind the operator to pay attention and take corresponding measures. 1_. -     (2) Hardware circuit of the temperature control forging system. The hardware of this system mainly includes temperature measurement, A/D conversion, microcontroller system, keyboard operating system , temperature display circuit, alarm circuit, b/A conversion, etc.