Level meter - introduction of instrument inspection method
The inspection of the spirit level must be carried out in accordance with the corresponding standards. The temperature in the inspection room should be 20±2°C, and the inspection should be carried out under the condition of firmness, no vibration, and away from heat sources. Before the inspection, all parts of the level must be scrubbed clean, and then the level should be placed on the metal plate in the inspection room, and the same temperature time should not be less than 3h. spirit level
(1) Appearance inspection: For the new factory spirit level, the working surface should be flat and smooth, and there should be no defects such as blisters, pores, bruises, scratches, and corrosion. Stripped paint, rust and obvious defects are not allowed on non-working surfaces. The level should be clean and transparent, the engraved line should be clear and uniform, there should be no discoloration, and the engraved line should be perpendicular to the axis of the level. On the non-working surface of the spirit level, the name of the manufacturer, serial number and division value shall be marked.
(2) Interaction of each part:
The main level should be installed firmly, and the zero adjustment device should be easy to use and reliable. The movement of the bubbles should be smooth, and there should be no visible jumping or stagnation. When the room temperature is 20°C, the length of the bubble should be equal to the distance between the two long scale lines, and the deviation should not exceed ±1 division for those with a division of 0.02 to 0.05mm/m; for those with a division of 0.06 to 0.10mm /m shall not exceed ±0.5 divisions. The stability of the movement of the bubbles and the length of the bubbles should be checked on a level tester.
(3) The flatness of the working surface:
No protrusions are allowed on the working surface of the spirit level, and its flatness shall meet the requirements in Table 6-10-54. The length of the working face is 150～200 250～300, and the flatness deviation is <0.003 <0.005. For the grinding and grinding working face, the flatness is verified by the zero-level knife-edge ruler whose size is not less than the length of the inspected face, and the light gap method is used for verification , this verification work should be carried out at several positions in the longitudinal, transverse and diagonal directions of the working face. The largest gap seen is the flatness deviation of the surface. When estimating the size of the gap, it can be compared with the standard gap composed of gauge blocks.
For the flatness of the scraped working surface, use a zero-level flat plate to verify the coloring method. The number of spots in a square area with a side length of 25mm should not be less than 25 points for a level with a division value of 0.02 to 0.05mm/m, and should not be less than 20 for a level with a division value of 0.06 to 0.10mm/m Spots should be evenly distributed.
The straightness of the V-shaped working surface is verified by the method of painting with the verification mandrel. Put the mandrel coated with red lead powder on the V-shaped surface to rotate, and the contact line seen on the V-shaped surface is not allowed to have a discontinuity of more than 10mm.
(4) Zero inspection of the spirit level:
The offset of the bubble to the middle position should not exceed 1/4 of the graduation value. The inspection of the zero position of the lower working face of the level can be carried out on the zero-level plate, or on the level calibration instrument; the zero inspection of the lower V-shaped working face of the level should be carried out on a special tool; for the frame level The zero position of the upper plane working surface, the upper V-shaped working surface, the side plane working surface and the side V-shaped working surface should also be carried out on special tools.
The stability of the zero position of the level meter requires that after the zero position of the lower working face is verified, the zero position shall be verified again at an interval of 4 hours, and the change shall not exceed the allowable range of the zero position deviation.
(5) Verification of level division value error:
It should be done on a level gauge calibrator. The difference between the measured average angle value and the nominal angle value shall not exceed 10% of the nominal angle value. The unevenness of the graduation value should not exceed 20% of the graduation value. That is, the difference between adjacent readings is within the range of 0.8 to 1.2 divisions. The verification of the division value error of the level meter should be carried out on the left and right scales of the bubble. In order to eliminate the influence of the dead distance of the micro-motion screw of the level meter calibrator, the micro-motion screw should be rotated in one direction.
