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地质钻探机中的传动件20CrMnMoA钢冲击活塞,精度要求较高(平直度与同心度<0.02mm,渗碳层深度1.5～1.8mm,洛氏硬度HR_C60～62)。在磨加工中发现零件开裂极为严重,废品率高达80%。裂纹多数与磨削方向垂直,呈直线分枝与网络状龟裂。甚至在零件表面出现严重的烧伤点与表面剥皮。工艺机械加工-)渗碳:920、930℃保温10小时,出炉空冷.冷至830~840℃油淬,再经550、600℃高温回火,保温30分钟(消除渗碳后零件表面层的碳化物网络)一淬火和回火:加热至820℃保温13分钟油淬.180℃回火,保温1.6小时出炉空冷-》磨削:采用单精刚玉砂轮,粒度48粒,硬度ZR:,转速829转/分.进给量0.03、0.O5mm;肥
Geological drilling rig transmission 20CrMnMoA steel impact piston, high precision (flatness and concentricity <0.02mm, carburized layer depth 1.5 ~ 1.8mm, Rockwell hardness HR_C60 ~ 62). In the grinding process found that parts cracking is extremely serious, rejection rate as high as 80%. Most of the cracks with the grinding direction perpendicular to the linear branches and network-like cracks. Severe burn points and surface peeling even on the part surface. Process mechanical processing -) Carburizing: 920,930 ℃ insulation 10 hours, baked cold. Cool to 830 ~ 840 ℃ oil quenching, and then 550,600 ℃ high temperature tempering, holding for 30 minutes (after carburizing the surface of the surface layer Carbide network) a quenching and tempering: heating to 820 ℃ heat 13 minutes oil quenching .180 ℃ tempering, holding 1.6 hours baked air cooling - "grinding: single corundum grinding wheel, particle size 48, hardness ZR :, speed 829 r / min. Feed 0.03,0.O5mm; fat