840缸盖铸件的生产工艺

介绍了840缸盖的铸件结构及技术要求,详细阐述了铸造工艺方案:采取平浇的方式,压边冒口进铁液,浇口比为ΣF直:ΣF横:ΣF内=2:2.3:1,一箱4件造型,水套芯与油嘴孔芯使用热芯盒制芯,其余的砂芯均使用冷芯盒制芯;利用ABP中频电炉熔炼,出铁温度1 455℃,出铁时进行随流孕育和引爆法蠕化,使用75SiFe孕育剂,出铁时孕育量为0.2%~0.3%,二次孕育的孕育量为0.4%,蠕化剂使用REMg和RESiFe,加入量分别为0.2%±0.05%和0.3%±0.05%。浇注温度1 415±10℃,浇注时间18±2 s。最终得到的铸件内外表面清洁、无披缝、粘砂、气孔、裂纹等问题,表面粗糙度小于Rz100,气道粗糙度小于Rz80;铸件蠕化率达到55%~75%,试棒抗拉强度380~430 MPa,缸盖进、排气道间底面硬度180~195 HB,珠光体体积分数20%~40%。

Production Process of 840 Cylinder Head Castings

The 840 casting cylinder head structure and technical requirements were introduced. The casting process was elaborated as follows：horizontal casting was used and iron liquid was poured at connor feeder. The gating ratios was ΣFpouring：ΣFrunner：ΣFflow=2：2.3：1. The casing system was one type and four pieces. Water-jacked core and nozzle hole core were made by hot box process while other cores were made by cold box process. Smelting was carried out by ABP intermediate frequency electric furnace and tapping at 1 455 ℃. For primary inoculation,75 SiFe was added with stream or pour over by 0.2%~0.3%. And for second inoculation,REMg and RESiFe were added by 0.2%±0.05% and 0.3%±0.05% respectively. Pouring temperature was1 415±10 ℃ and pouring time was 18±2 s. As a result,the final casting was clean on inside and outside surfaces,with no crack,sand fusion,gas holes,or other defects. The roughness of surface was less than Rz100 and that of air flue was less than Rz80. The vermicularity rate of casting was 55%~75% and tensile strength was 380~430 MPa. The hardness of the bottom surface between air inlet and air vent on cylinder head was 180~195 HB. Volume fraction of pearlite in castings was 20%~40%.