The main components of the servo universal testing machine and their respective functions
1. Measurement of force value
The force measurement system is mainly composed of force sensor, amplifier and data processing system.
2. Force sensor
The most common so-called force sensor on the market is the strain sensor. Its main components are strain gauges, elastic elements and some accessories (compensating elements, protective covers, wiring sockets and loading parts), which can turn mechanical quantities into power output devices. The main categories are: cylindrical force sensor, spoke force sensor, S double connection hole sensor, cross beam sensor, etc.
3. Elastic elements
That is to say, a component that uses the elasticity of materials to complete various functions, and its working principle on the tensile machine takes the S-type sensor as an example. When the sensor is under the action of the tensile force P, since the surface strain of the elastic element is proportional to the magnitude of the external force P, the strain gauge is connected to the measuring circuit, and its output voltage can be measured to measure the magnitude of the force.
4. Data system processing
1. The output signal of the sensor is very weak, usually only a few mV. If this signal is directly measured, it is very difficult and cannot meet the requirements of high-precision measurement. Therefore, the weak signal must be amplified by the amplifier, and the amplified signal voltage can reach 10V. The signal at this time is an analog signal, which is converted into a digital signal through a multiplex switch and an A/D conversion chip, and then data is processed. So far, the force measurement has come to an end.
2. Measurement of beam displacement: The principle is roughly the same as that of deformation measurement. The displacement of the beam is obtained by measuring the number of output pulses of the photoelectric encoder.
3. Deformation measurement: It is measured by a deformation measurement device, which is used to measure the deformation of the sample during the test. There are two chucks on the device, which are connected to the photoelectric encoder installed on the top of the measuring device through a series of transmission mechanisms. When the distance between the two chucks changes, the shaft of the photoelectric encoder is driven to rotate, and the photoelectric encoder outputs a pulse signal. Then, the signal is processed by a single-chip microcomputer, and the deformation of the sample can be obtained.