磁致效应在精密磨削过程中的作用机制及其应用研究

The steady control of machined surface quality in the precision grinding process is very important. However, the local high temperature due to the action between grits and machined surface could influnce the surface integrity greatly. In this study, intense magnetization field is input into the grinding zone. The magnetization induced effect, including magnetostriction, magnetization induced cooling, magnetization induced phase transfer, et al, could weaken the local high temperature and the residual stress of grinding process. And the ground surface quality could be improved. The split Hopkinson pressure bar technology is employed in the analysis of dynamic mechanical properties of specimen with and without magnetization. The coupled relationship among magnetization energy, deformation energy and heat energy is analyzed and the mechanism of demagnetization cooling is proposed. Taking the microstructure evolution of workpiece materials in the magnetization assisted grinding process as the research objective, the effect of magnetization induced cooling on material removal process is analyzed. And the generation mechanism of machined surface integrity, including material plastic flow, machined surface deteriorate, residual stress, is presented. The amplitude transformer is used in the control of magnetic lines. And the application of intense magnetization field during the grinding process is preliminarily studied. Finally the mechanism and application method of magnetization assisted machining is summarized, which could be used in the other machining processes.

精密磨削过程中已加工表面质量的稳定控制十分重要，而砂轮上单颗磨粒与工件表面作用产生的局部高温对已加工表面质量造成极大的负面影响。本研究拟将强磁场能量连续输入磨削区域，利用磁致冷却等磁致效应抵消或削弱磨削中的局部高温和残余应力等对已磨削表面质量产生的不利影响。具体研究内容包括：利用充磁前、后试样的分离式Hopkinson压杆实验，研究磁能--变形能--热能的耦合过程和转化关系，进而研究磁致冷却现象发生的机制；以强磁场作用下精密磨削过程中的微观组织演变为研究对象，分析磁致冷却等磁致效应对工件材料磨削去除过程的影响，进而研究强磁场对已磨削表面塑性流动、表面变质、残余应力等完整性指标的影响；利用高导磁率的聚能器对磁力线方向进行控制，对强磁场在磨削过程中的高效、定向、连续施加方法进行初探。最终形成一整套强磁场辅助加工的工艺实现方法。

精密磨削过程中已加工表面质量的稳定控制十分重要，而砂轮上单颗磨粒与工件表面作用产生的局部高温对已加工表面质量造成极大的负面影响。本课题将强磁场能量连续输入磨削区域，利用磁致冷却等磁致效应抵消或削弱磨削中的局部高温和残余应力等对已磨削表面质量产生的不利影响。完成的主要研究工作包括：进行了充磁前、后试样的分离式Hopkinson压杆实验，研究磁能--变形能--热能的耦合过程和转化关系，进而研究磁致冷却现象发生的机制；分析了磁致冷却等磁致效应对工件材料磨削去除过程的影响，进而研究强磁场对磨削力、磨削温度和已加工表面质量的影响；开发在线磁场辅助磨削转呗，对强磁场在磨削过程中的高效、定向、连续施加方法进行初探，最终形成一整套强磁场辅助加工的工艺实现方法。