Calibration and adjustment of measuring system of tensile testing machine

The tensile test machine is the main machine for tensile testing. The tensile signal can be calibrated by two prescriptions: standard dynamometer or electrical calibration. In essence, it is to adjust and calibrate the measurement circuit. The measurement accuracy of a standard tensile testing machine can generally reach 0.15%, and it is connected in series to the force sensor of the test machine. First adjust the "coarse balance" and "fine balance" of the phase balance and amplitude in the measurement circuit and then make the current output zero.

Then slowly load. When the tensile tester reaches the force value of the standard force gauge, the value displayed by the force sensor and the common amplification circuit is the full load range. Adjust the amplification factor of the measurement amplifier to make the voltage value a standard value, such as 10v. Use this as the standard voltage. After unloading and re-calibrating several times, the full scale calibration is completed, and then a linear inspection of a certain proportion of the scale is performed.

Since the gains of the same test machine vary in different control states and different test pieces, the relevant parameters must be adjusted according to the requirements of accuracy and width, so the operator must constantly adjust the relevant parameters according to the test requirements to achieve excellent performance. The reasonable operation and adjustment of the electro-hydraulic control system of the test machine is now briefly introduced as follows.

When powering on, the console should be powered on first, and then the hydraulic source should be started. If the hydraulic source is started first without putting the console in a control state, on the one hand, the hydraulic oil is inserted into the hydraulic rainbow due to the zero position bias of the servo valve, causing the piston to move in one direction until it hits the cylinder head, and sometimes even a cylinder crash accident occurs; on the other hand, some electronic devices need to be heated up, especially the circuit of the strain gauge, which requires preheating for more than half an hour to make the zero position more stable. Therefore, when powering on, you should first turn on the console to check whether all instruments are in normal conditions. For test machines with several control states such as position, force and deformation control, the control state should be placed at the position control point first, and then switched to the corresponding control state as needed after all the power is started.