The electronic tensile testing machine adopts the integrated structure of DC servo motor and speed control system to drive the synchronous belt speed reduction mechanism, and drives the screw pair to load after deceleration. The gauge length measurement of rubber is an important part of the electronic tensile testing machine, which directly affects the accuracy of the test. Of course, there is also a close relationship between the tensile value and the gauge length in the tensile specimen. There are two main types of gauge distance measurement: manual measurement and automatic measurement!
1, automatic measurement
① installed in the holder;
② on the sample.
Electronic tensile testing machine Many automatic gauge measuring devices for rubber tensile testing machines use contact sensors to measure the change of gauge length in real time. There are two main installation positions for sensor mobile devices:
The sensor that mounts the mobile device to the holder has certain limitations. Since the elastic deformation of the rubber is very large, the moving distance of the gripper and the variation of the gauge length of the sample are greatly different. The gauge tester mounted on the gripper is more suitable for detecting the elastic deformation. The tensile properties of the specimen (such as metallic materials) cannot be used to test the tensile properties of the rubber.
The contact gauge length measurement method will have a great impact on the tensile test of the specimen. The reasons for the impact are as follows:
First, the self-weight of the gauge rod contacting the sample will pull the sample down, affecting the tensile force measurement;
Second, the clamping of the gauge rod has a certain influence on the stretching of the clamped portion, so that it cannot be freely stretched.
2, manual measurement
The error of manual measurement is very large:
① Observing the gauge length of the sample by eye force will cause a certain deviation;
② It is impossible to accurately track the change of the gauge length of the sample by manually moving the gauge length rod;
③ While the tester moves the gauge rod, it is difficult to record the gauge length value, and the electronic tensile tester cannot accurately describe the stress-strain curve after the test.
Manual measurement is to set a ruler and two horizontal gauge rods that can be moved vertically in the vertical direction of the gripper. When the tensile test is performed, the gauge length on the specimen is observed by eye force, and the manual control is performed. Two gauge rods to synchronize with the gauge length on the specimen, and record the moving distance of the gauge rod on the scale.