When grinding journals with surface roughness Ra0.02-0.04μm and accuracy h4–h5 in large-scale engineering machinery precision parts processing and manufacturing plants, the processing of ultra-precision parts is performed on expensive high-precision grinders. However, general engineering machinery repair factories do not have high-precision grinders. It is very difficult to grind such low surface roughness and such high journal accuracy. We carry out a large number of tests on the existing equipment M131W ordinary cylindrical grinder, and carry out necessary inspection, scraping and adjustment on it. Through dressing and fine balance grinding wheel, more contour micro-edges can be properly formed on the abrasive grains. , It can completely realize ultra-high-precision, low-roughness grinding pins, and can effectively grind parts with precision h4–h6 and roughness Ra0.02–0.04μm. The method is simple, convenient and easy to implement, and the processing effect of ultra-precision parts is quite good.
2 Superfinishing grinding mechanism
The ultra-precision grinding used in the processing of ultra-precision parts is carried out by the feature that a large number of abrasive micro-edges of the same height can be trimmed on the working surface of the grinding wheel. These micro blades of equal height can cut out the thin, still have some trace defects and trace shape and size errors and margins from the working surface. Therefore, the use of these and other micro-cutting tools is a large number. If the amount of grinding is appropriate, it is possible to leave a large number of extremely fine cutting marks on the machining surface of the ultra-precision part, so a very low surface roughness can be obtained. In addition, because there are still obvious effects of friction, sliding, polishing, and calendering in the non-flare polishing stage, the surface roughness of ultra-precision parts processing secrets is further reduced.
3 Overhaul of ordinary grinder
In order to grind the workpiece with a roughness of Ra0.02-0.04μm on the flexible grinder, the following items should be tested on the old flexible grinder. If it does not meet the accuracy requirements, it must be scraped and repaired.
(1) Overhaul the bed guide rail
1) Testing and how to scrape the bed V-shaped guide rail: the non-straightness in the vertical plane should not exceed 0.01mm in the length of 1m; the non-straightness in the horizontal plane should not exceed 0.01mm in the length of 1m; and The non-verticality of the sliding saddle rail should not exceed 0.02mm in the length of 250mm; the contact point requires 12-14 points (25×25) mm.
2) What kind of flat guide rail of the scraper bed tested: The unequal degree of the V-shaped guide rail shall not exceed 0.02mm in the length of 1m; the unevenness in the vertical plane shall exceed 0.01mm in the length of 1m; contact The spots require 12-14 points (25×25) mm.
(2) Overhaul sliding saddle rails
1) Check and how to scrape the saddle V-shaped guide rail; the non-straightness in the vertical plane must not exceed 0.01mm in the total length; the contact spot requires 10–12 points (25×25) mm.
2) Detection and what kind of sliding slide saddle flat guide rail: the non-parallelism of the V-shaped guide rail shall not exceed 0.02/1000mm in the total length; the contact spot requires 10–12 points (25×25) mm.
(3) Adjust the gap between the main shaft of the grinding wheel and the bearing bush
Paint on the shaft diameter of the grinding wheel spindle and rotate the bearing bush. Use a scraper to scrape the bearing surface of the bearing bush. The contact spot should reach 12-14 points (25×25) mm. After that, install and adjust the grinding wheel spindle and the bearing bush. Adjust the gap to 0.0025–0.005mm. In this way, the disadvantages of round edges in the workpiece can be overcome during grinding.