基于离散元法的磁性磨粒干压成型工艺参数优化

Optimization of dry compression molding process parameters for magnetic abrasive grains based on discrete element method

为探究磁性磨粒坯体压制阶段的各工艺参数对其成型质量的影响,优化磁性磨粒的烧结法制备参数,制备出质量优良的磁性磨粒,以铁基氧化铝磁性磨粒为研究对象,建立磁性磨粒干压成型的离散元模型。通过改变压制力、压制方式、摩擦系数、模具高径比等工艺参数,探究其对磁性磨粒坯体成型质量的影响,并实现压制过程中工艺参数的优化。结果表明:压制力越大,坯体孔隙率越小,但压制力过大,坯体外表面产生裂痕,影响坯体表面形貌的完整性,故宜选择75~125 MPa的压制力;双向压制得到的坯体密度更均匀、力学性能更好;模具的高径比越大,坯体的孔隙率相对较大,坯体的轴向应力相对较小;磨料颗粒间摩擦系数及侧壁与磨料颗粒之间的摩擦系数越小,坯体的孔隙率越小、致密度越好,坯体的均匀性也越好。在磁性磨粒混合阶段加入适量润滑液,可适当减小磨料颗粒间及颗粒与模具侧壁间的摩擦系数,进而提高磨粒坯体质量。

In order to explore the influence of various process parameters in the pressing stage of magnetic abrasive grain bodies on their forming quality,optimize the sintering preparation parameters of magnetic abrasive grains,and prepare high-quality magnetic abrasive grains,the dispersion element model of dry pressing forming of magnetic abrasive grains was established with iron-based alumina magnetic abrasive grains as the research object.By changing the pressing force,pressing mode,friction coefficient,die height-diameter ratio and other process parameters,the influence of each process parameter on the forming quality of the magnetic abrasive grain bodies was explored,and the optimization of process parameters in the pressing process was realized.The results show that the larger the pressing force,the smaller the porosity of the green body.However,if the pressing force is too large,cracks will appear on the outer surface of the green body,affecting the integrity of the surface morphology of the green body.Therefore,a pressing force of 75 to 125 MPa should be selected.The density of the green body obtained by two-way pressing is more uniform,and the mechanical properties are better.The higher the height-diameter ratio of the mold,the higher the porosity of the green body,and the smaller the axial stress of the green body.The smaller the friction coefficient between particles and between the side wall and particles,the smaller the porosity,the better the density and the better the homogeneity of the green body.When adding an appropriate amount of lubricant in the mixing stage of the magnetic abrasive particles,the friction coefficient between the magnetic abrasive particles and between the particles and the side wall of the mold can be appropriately reduced,thereby improving the quality of the abrasive body.