Ultrasonic thickness gauge thickness calibration and speed of sound adjustment
Due to the influence of factors such as ambient temperature and operating voltage, some parameters of the measuring system drift from time to time, so the instrument should be calibrated for thickness when measuring. The calibration operation is to use the instrument to measure a piece of 5mm thick standard test piece, if the instrument display is not equal to 5mm, the thickness should be calibrated. Older thickness gauges were realised by adjusting the potentiometer knob. This design is completed by the thickness calibration key, when you need to calibrate, press the thickness calibration key, the microcontroller executes the thickness calibration procedure, so that the measurement results and the standard thickness comparison, according to the results of the addition and subtraction processing, complete the calibration.
Sound speed setting
Ultrasonic thickness gauge in measuring the thickness of different materials, due to ultrasonic waves in different materials propagation speed is different, need to set the speed of sound of the material, such as steel speed of sound 5950m / s, zinc speed of sound 4170m / s. This operation in the old instrument is a mechanical 3-bit BCD code disc switches and can be preset counters to control the number of gates to complete the number of times the speed of sound of the material, the gate opens the gate more often, and the low sound velocity material, the gate opens the gate more often. For materials with low speed of sound, the gate opens less often. The design of the cast steel, steel, aluminium, copper, brass, zinc, quartz glass, polyethylene, polyvinyl chloride, nine typical materials of the speed of sound, in the form of a table into the storage unit, the use of the speed of sound set by the key to select, and then by the microcontroller's P1.7 port collection of transmitting pulses to subtract the counting of the number of times it controls the gate to open the speed of sound set the number of times, so that the operation of the operation is very simple.
Sound speed adjustment
The sound speed setting for the 9 typical materials mentioned above is selected by the sound speed setting key. When measuring the thickness of non-typical materials, the sound speed setting is done by the two function keys of sound speed increase and sound speed decrease. Press the key of sound speed increase or sound speed decrease, the LCD screen shows the sound speed value is increasing or decreasing, until it is adjusted to the sound speed we need, at this time, the sound speed adjustment programme will be adjusted to the value of the sound speed storage unit to be used.
