SKF bearing in precision grinding of graphite seal ring
Several air pump unit production have to graphite M106H parts, type a letter representing a SKF bearing the typical parts such as shown in figure 1. This part for the sealing work, B surface as the sealing surface, the surface of high precision. Processing of B surface, precision machining is not up to the requirements, and the graphite is a brittle material, also containing an epoxy resin, and not by analyzing the grinding, grinding. In the absence of data reference case, the process test we on the graphite parts are grinded, finally draws the process of ideal, achieved the requirements of parts.
Part of the process route: rough turning, milling, grinding, finishing two slot B.
From the above process, the outer ring and the inner ring and shaft bearing seat hole assembly with SKF: B surface to ensure the grinding surface roughness Ra0.1 ? m, parallel 0.01mm, flatness 0.0006mm. The conventional dry grinding, the surface roughness and flatness of the two elements of the whole is not qualified, the measured flatness value competition up to required value of 4 ~ 7 times, that is 0.0024 ~ 0.0042mm.
Then from the material properties to analysis, M106H impregnated graphite, shore hardness 60, compressive strength of 117.6MPa, flexural strength of 49MPa. Through the process test, the micro layer extrusion principle. The specific method is: will the filtered powder and kerosene embedded grinding plate, and the plate surface polishing paste fine coarse grained cast, the powder particles protruding flat surface polished, highly consistent. Then, the parts are placed directly grinding, in this flat, flat on B surface is uniformly micro layer extrusion type cutting.
Parts in place for machining fine car, local collapse of sharp edges, grinding process steps are as follows:
1) processing site, the environment clean. The importance of SKF bearing shall carefully check the higher the grinding plate, parts are thoroughly cleaned, this step is very important to guarantee the processing of success.
2) rough lapping plate. 3 pieces of 300mm * 300mm unslotted cast iron plate, the best selection of low alloy high phosphorus cast iron plate. Because the microstructure the flat is flaky graphite and fine pearlite, more easy to make. A higher form accuracy and surface roughness. With W20 powder plus kerosene to research flat. For convenience of description, 3 pieces of plate numbers for 1, 2, 3, is expressed as a fraction of research methods, said upper plate, lower plate represents, in the following order: to research 1/2 → 1/3 → 2/3 → 2/1 → 3/1 → 3/2, according to the order of the cycle:
3) lapping plate. With W7 powder still according to the sequence of research. After the research, using 200mm a knife edge straight edge inspection, shall not be transparent or indentation uniform; can also be used with 80mm optical flat inspection, should be no more than a light wave interference with, and is uniformly convex. Note: the coarse, fine of research, has a large number of micro pores embedded plate, cage failure in SKF bearing failure forms a larger proportion of the powder on cutting graphite is enough, no pressure sand process.
4) polishing plate. 4 layers of silk shop in a block has been good on a flat plate, with kerosene will silk Jiaotou, then W7 chromium oxide polishing paste and the other 2 pieces of research good plate were polished in the silk cloth. Polishing is the role of cast plate fine coarse grain, and the embedded plate powder were highly identical. At the same time, improve the flat surface roughness, which is less than Ra0.1 ? M. This process is the key to the method of the.
5) in the 2 pieces of flat polished drop 1 to 3 drops of kerosene and instrument oil, cotton oil evenly on the plate, 3min, the flat surface oil wipe. So, into the flat pores in the kerosene and powder is mixed evenly, micro cutting fluid formed machining graphite.
The 6 part) will be placed on a flat plate of spiral movement cycle, Qingdao Rui precision electromechanical improve and lubrication problems to improve the SKF bearing in rolling mill forced his hands smooth, extrusion type cutting through the micro layer, to finish grinding plane B. Note the ground floor flat, remove debris and dirt.
The 7 part studies), with a clean cloth or cotton gently wipe grinding scraps. Take care not to oil liquid cleaning, after the test found, oil immersed, parts of the surface roughness variation.
