刀具-切屑接触区的应力分布建模方法研究

Mechanical Model of Contact Stress Distribution between Cutting Tool and Chip

刀具-切屑之间的接触区特性对切削过程中的切削力、切削热及刀具磨损等均有较大影响。利用UMT-2高速球-盘摩擦试验机进行硬质合金球(模拟刀具)和Al7050-T7451(模拟工件)的摩擦试验。测量摩擦后得到的沟槽三维形貌和硬质合金球上的磨痕形状,对硬质合金球和Al7050-T7451盘之间的三维接触应力状态进行分析计算,进而建立考虑相对运动速度和接触应力的滑动摩擦因数表达式。提出刀具-切屑接触区几何尺寸和应力分布的计算方法,设计正交车削试验测量主切削力和吃刀抗力,进而通过计算获得不同切削速度下的刀具-切屑接触长度、接触长度上黏结区的长度、以及黏结区、滑动区长度之比,从而量化不同切削条件下刀具-切屑的接触状态。

The ball-disc friction experiments have been performed by UMT-2 friction tester. The ball material is cemented carbide （material of cutting tool） while the disc material is A17050-T7451 （material of workpiece）. The 3D profile of groove on the disc after friction test and wear pattern on the ball have been measured to determine the contact stress in the 3D stress conditions. A model of average friction coefficient, which considers the effect of sliding speed and average contact stress, has been presented. Orthogonal cutting experiments have been performed and the cutting forces and thrust forces have been measured to calculate the mechanical model, which is presented to describe the contact between cutting tool and chip. The contact length between cutting tool and chip, length of sticking and sliding zone in the different cutting conditions has been calculated.