Detailed analysis of three kinds of errors of the

Detailed analysis of three kinds of errors of hydraulic universal testing machine

after confirming that the installation levelness of the instrument meets the requirements of the specification, first check whether the friction force of the working part is too large. If so, adjust the guide wheel clearance to eliminate the friction force of large and full-size samples. If necessary, clean the working oil cylinder. If there is still a positive difference after excluding the influence of friction force, Then loosen the fastening screw of the connecting shaft sleeve between the swing rod and the push plate in the force measuring part (reader 4, in the front structure of the loading test piece), adjust the push plate to the inside, tighten the fastening screw, and then verify it step by step from the small dial, repeat several times until it is qualified. If the small dial is qualified, but the large and medium dial is still out of tolerance, the weight of B thallium and C thallium should be appropriately increased until it is qualified

II. The negative deviation of the indicated value is out of tolerance

first, check whether the force measuring piston is installed correctly and whether the friction force is too large. After eliminating this reason, adjust the push plate to the outside and adjust the small dial to be qualified. If the large and medium dial are still out of tolerance, it should be properly reduced to reduce the weight of B thallium and C thallium until it is qualified

III. The indication error presents "positive before negative" or "negative before positive after positive" on the dial, and individual points are out of tolerance

at this time, the angle of the contact surface between the push plate and the toothed rod head should be changed. The contact surface is usually fixed on the push plate with a flat steel sheet through the upper and lower screws. The applicability, accuracy and sensitivity of the method are truly proved by the experimental data. The adjustment method is to loosen the two screws and pad the upper or lower side (only one side) between the steel sheet and the push plate with copper sheet or other light metal sheet, so as to change the angle, Repeat the verification and adjustment until it is qualified