The coaxiality measuring instrument of the testing machine can be used to detect the coaxiality of the testing machine, and it is necessary to ensure that the upper and lower fixtures of the clamping device of the testing machine are coaxial. This is very simple. Just put the upper and lower fixtures of the testing machine together to check. If the upper and lower fixtures are not in the same plane, it means that there is a problem with the geometric coaxiality of the testing machine itself, and the geometric coaxiality of the testing machine needs to be solved first. Ensure the geometric coaxiality of the testing machine in order to test the coaxiality of the clamping device of the testing machine.
In general, the coaxiality of the testing machine is tested using an automatic coaxiality tester or a heavy hammer; In practical operation, the coaxiality of the testing machine can be detected using a single-sided extensometer. After laboratory testing, it has been proven that this method is simple and feasible.
The coaxiality measuring instruments for testing machines are divided into two categories: electronic universal testing machines that use mechanical force and electronic measurement technology to measure mechanical performance parameters; An electro-hydraulic servo universal testing machine that uses hydraulic pressure as the power source and electronic measurement and control technology to measure mechanical performance parameters. The electronic universal testing machine is a symmetrical portal frame structure, and as long as the design is reasonable, there is generally no problem with the overall symmetrical force of the testing machine. The main reason for the different axial degrees of this type of testing machine is due to the clamping device, especially the fixture.
Therefore, when designing and manufacturing clamping devices including fixtures, it is necessary to consider the force symmetry and uniformity of the clamping device, and the fixture should have sufficient rigidity. The clamping device has two connection methods: rigid connection and flexible connection. The so-called flexible connection refers to the type with universal adjustment device.
The coaxiality measuring instrument of the testing machine adopts the uniaxial tensile method to measure the elastic modulus of metal materials, which has the advantages of easy operation, traceable data, and large equipment retention. This method has been widely used in the engineering field. When measuring the elastic modulus of metal materials, if a single-sided clamping deformation measuring device is used, if the coaxiality of the equipment is not good, it will cause the sample to tilt after installation, and it will not be on the same axis as the loading force direction of the test, which will have a significant impact on the accuracy of stress and strain measurement.
