Marble ruler

Marble ruler is mainly used to measure the straightness and flatness of workpieces and equipment installation. It can also be used to check the flatness and straightness of machine tool workbench, guide rail and detailed work. It is applicable to industrial production and laboratory measurement

key points of using marble ruler

1. Use marble ruler with care, preferably wear gloves, and do not touch the working surface of angle ruler with hands. During handling, it is not allowed to lift only the long side of the angle ruler, but hold the short side with one hand and the long side with the other hand

2. The marble ruler and workpiece need to be cleaned and wiped

3. The marble ruler shall be verified periodically to obtain the certificate of conformity

4. Do not put the marble ruler upside down

5. After measurement, the angle ruler should be cleaned and wiped, coated with anti rust oil, put into a pair of boxes, and placed in a dry and warm place. It is not allowed to stack the granite ruler with other tools and fixtures. If the length of the marble ruler exceeds 2000mm, its width needs to be thickened accordingly

straightness detection method of marble ruler

I. perpendicularity of the side of the ruler to the working surface

place the marble ruler on the flat plate, so that the base equipped with a dial indicator with a division value of 0.001mm passes through the standard round rod, and zero on the standard square. Then make the gauge base close to one side of the ruler in the same way, and the reading of the dial indicator is the Perpendicularity Error of the side. Similarly, detect the Perpendicularity Error of the other side, and take the larger error value

II. The area ratio of the contact point of the marble ruler

apply the display agent on the working surface of the inspected ruler, grind it on a cast iron plate or ruler with a precision not lower than its accuracy, and show obvious contact points on the working surface of the inspected ruler. Then use one at 50mm × 2.5mm within 25mm × Place the transparent thin plate (such as glass plate) with 200 small squares of 2.5mm on any position of the working surface of the leveling rule to be inspected, and observe the proportion of the area of each square containing the contact point in turn (in 1/10 unit). Calculate the sum of the above proportions and divide by 2 to obtain the ratio of the contact area of the detected part

III. The Marble ruler is supported by equal height blocks at the standard support marks 2l/9 from both ends of the ruler, and the appropriate detection bridge slab is selected according to the length of the working face of the ruler (generally 8-10 steps, and the span is between 50-500mm); Then place the bridge slab on one end of the ruler and fix the reflector or level on the bridge slab; The bridge slab is gradually moved from one end of the leveling ruler to the other end according to the span. For each span moved, the position reading is read from the autocollimator with the division value of 1 "(or 0.005mm/m) or the electronic level with the division value of 0.001mm/m (the level 1 leveling ruler with the working surface length greater than 500mm can use the image level with the division value of 0.01mm/m, and the level 2 leveling ruler can use the frame level with the division value of 0.02mm/m); The difference between the larger value and the smaller value is the straightness error of the working surface of the ruler. For the straightness error of any 200mm of the working face, the bridge slab of 50mm or 100mm can be selected, and it can be checked and determined within any 200mm according to the above method

IV. parallelism of the upper working surface and the lower working surface of the marble ruler, and parallelism of the working surface and the lower bearing surface

when there is no applicable flat plate, it is allowed to place the side of the ruler on a certain bearing surface, and measure the height difference of the ruler with a lever micrometer with a division value of 0.002mm or a gauge with a division value of 0.002mm