The force measurement accuracy and displacement control of the cardboard compression testing machine are its core performance indicators, which directly determine the reliability and repeatability of the test results. The key technologies can be analyzed from three aspects: sensor accuracy, drive system design, and closed-loop control algorithm.
In terms of sensor accuracy, high-precision force sensors are the cornerstone of data acquisition. Modern devices commonly use 24 bit high-precision AD converters, combined with explosion-proof pressure sensors, to convert mechanical deformation into electrical signals. The resolution can reach 1/1000000, and the force measurement error is controlled within ± 0.01% of the full range. For example, when testing a cardboard box with a 50kN range, the sensor can accurately capture small changes of 0.5N, ensuring real-time and accurate data collection. At the same time, the sensor needs to eliminate environmental interference such as temperature and vibration through dynamic calibration technology, and perform temperature compensation within the range of -10 ℃ to 50 ℃ to avoid measurement deviation caused by thermal expansion and contraction.
In terms of drive system design, the equipment often adopts a double screw vertical structure, driven by a servo motor synchronous belt and high-precision ball screw transmission, to achieve uniform linear motion of the pressure plate. For example, a certain device is controlled by a dual axis motor linkage, and the speed error of the pressure plate movement is ≤± 1%. Coupled with a spring damping shock absorber, it can eliminate mechanical resonance and noise interference. In terms of displacement resolution, the device achieves a micrometer level positioning of 0.01mm through a grating ruler or magnetic grating ruler, ensuring the stability of the testing process.
In terms of closed-loop control algorithm, the equipment is equipped with an ARM processor and a variable frequency speed regulation system, which adjusts the pressure plate speed and pressure in real time through PID control algorithm. For example, in the constant pressure deformation measurement mode, the system monitors the pressure value at a sampling frequency of 1000Hz. When the actual pressure deviates from the set value, the motor speed is automatically adjusted to correct the deviation; In the stacking test, the system can simulate continuous pressure for 24 hours and analyze the creep characteristics of the cardboard box through the pressure time curve.