Hardness tester common fault and its maintenance

- Jan 23, 2019-

Metallic Rockwell, Brinell, and Vickers hardness testers are the most commonly used in industrial and mining enterprises and research institutes. Metal Rockwell and metal Brinell hardness testers are simple in structure with respect to metal Vickers hardness testers. The repair of common faults is not very difficult. The following is a general troubleshooting of the metal Vickers hardness tester. Before starting the verification and repair work, you should start from the level of the adjustment workbench, based on years of work practice. Then observe whether the spindle, lever, lifting screw, buffer mechanism and measuring device are normal and flexible. Ensure a basic understanding of device performance. Then solve the problem one by one. Then check the switch, light bulb, etc. If it does not light after removing these factors, first check if the hardness tester power supply is connected. It is necessary to see if the load is fully added or if the reed switch is normal. After the exclusion is still not normal, it must be gradually checked from the line (circuit). 2, can not see or see the indentation, measuring the turbidity inside the microscope is still unclear after adjustment, this should start from adjusting the microscope focal length and light. Then rotate the objective lens and the eyepiece separately, and move the three flat mirrors with dashed lines, solid lines and engraved lines in the mirror separately, carefully observe which mirror surface the problem is on, then remove it, scrub with long-fiber cotton wool with absolute alcohol. Clean, install in reverse order and observe, if not resolved, repair or replace the micrometer. 3. The position of the indentation changes greatly. The indentation is not in the field of view or the table is slightly rotated. Therefore, the indentation is adjusted in the following order. 1 Adjust the movable clearance at the lower end of the main shaft. The reason for this is that the indenter is fixed to the bottom end of the working shaft due to the different axial axes of the indenter, the measuring microscope and the table. The lower end surface of the guide seat is not directly in contact with the taper surface of the spindle; 2 adjust the side screw of the rotating shaft so that the working shaft and the main shaft are the same (axis). After adjusting, an indentation is pressed on the test block to observe its position in the microscope. And record; 3 gently turn the table (to ensure that the test block does not move on the table) under the microscope to find a point on the test block that does not rotate, this point is the axis of the table; 4 slightly loosen the lift screw plate The upper screw and the bottom screw are used to gently move the entire lifting screw so that the axis of the table coincides with the position of the indentation recorded in the measuring microscope, and then the platen screw and the adjusting screw are fastened, and an indentation is pressed against each other. Repeat the above steps until they are completely coincident. 1 Measurement microscope scale is not allowed. Check with a standard micrometer. If it is not allowed to be repaired or replaced. 2 to see if it meets the requirements of the diamond indenter verification procedures. Replace the indenter if there is a defect. Diamond indenter defect. Observed with an 80-fold stereo microscope. 3 Check with a small load third-class standard dynamometer. If the load exceeds the requirement (±1.0%) but the direction is the same, the negative (load) load exceeds the regulation requirements or the load is unstable. In this case, the lever ratio changes, the spindle protection cap can be loosened, the force point contact is rotated, and the adjustment load (lever ratio) is adjusted and tightened. If the load is unstable, it may be caused by the blunt force of the blade, the wear of the fulcrum ball or the difference between the working axis and the spindle, and the large friction in the working shaft. At this time, check the blade and the steel ball. If it becomes dull or worn, it should be trimmed or replaced. Check the working shaft and clean it. Be sure to pay attention to the alignment of the shaft steel ball and the adjustment of the same shaft.