Analysis of commonly used electronic pull test machine slip reasons

Electronic pull test machine Electronic pull test machine, also known as almive material test machine is used for a variety of materials static load, stretching, compression, bending, shearing, stripping and other mechanical properties of mechanical performance testing machine, suitable for plastic sheet, pipe, special profile, plastic film and Various physical and mechanical performance tests of rubber, wire and cable materials are developed for materials, for physical testing, teaching research, quality control and other indispensable testing equipment, pull machine fixtures as an important part of the instrument, different materials need different fixtures, but also whether the test can be carried out smoothly and the accuracy of the test results is an important factor.
is the reason why the pull tester slips during use? Interstate GBPI technicians summarized that the reasons can be divided into human factors and device factors.
I. Human factors caused by human factors causing the pull test machine to slip are caused by the operator not operating according to the correct method of the test when carrying out the test, there are two main factors: the sample clamping length is shorter and the clamp of the fixture is not selected properly.
1, the test clamping length is short The correct way to use the test machine fixture should be, when the clamping length of the test piece is the same as the length of the clamp flank, first push the jaw with external force, so that it produces initial friction on the clamping surface, and then through the movement of the crossbar of the test machine On the sample loading, friction pull jaw (wedge mouth) due to the role of the slope, the greater the axial pull force, the greater the clamping force produced, the test machine clip specifically has two beveled wedges is based on the above clamping method, in accordance with the acceptance of uniform pressure stress design.
However, some operators did not operate in accordance with the requirements of the use of the test machine, the sample clamping length is short, or the sample processing is too short, resulting in the wedge mouth slope force is not equal, the wedge mouth local stress far exceeds the yield strength of the material, so that the wedge mouth produces plastic deformation, serious external flipping, so that the wedge mouth slope collapse or wear.
the fixture continues to be used in this case, reducing the angle of the wedge port, so that the grip body force state deteriorates and the slip phenomenon occurs.
2, clamp clamp selection improper pull test machine clip has a variety of different specifications and clamps, for different samples using different chucks, some operators in the test, the use of large-size jaw clamp holding small cut interview sample, or the use of flat clamp clamp holding large sample, so that the clamp and sample contact is not close, friction coefficient significantly reduced, intuitive performance for the clamp scale spikes are divided by grinding, friction force is greatly reduced.
when the force of the sample gradually increases to achieve a large static friction, the sample will slip, creating a false yield phenomenon from the surface.
, equipment causes the pull test machine slip equipment mainly because the pull machine in the pull sample due to iron oxide fell into the wedge block slope caused by slipping.
Metal sample in the pull process to produce metal iron oxide, iron oxide will fall into the wedge block and fixture combined slope, so that the slope of the flatness is destroyed, surface roughness is seriously reduced, so that the wedge (wedge block) movement is inflexible, in the increasing pull, the wedge block along the oblique slope of the swallow tail in the slide to create crawling (jumping).
, the sound of the horn, which often appears during the stretch loading process, is produced.
that's what's commonly referred to as slipping.