通过切削试验 ,研究了限制接触刀具前刀面的刀—屑接触长度逐渐减小时切削力的变化规律。试验结果表明 :当刀具前刀面刀—屑接触长度减小时 ,前刀面上的法向力Fn 和切向力Ff 呈非线性减小 ,且Ff-l曲线存在两个拐点 ,根据这两个拐点可间接测量前刀面的刀—屑接触长度L和紧密型接触长度lf1。 Through the cutting test, the change law of the cutting force when the contact length of the tool-shaving debris that contacts the tool rake face is reduced is studied. The experimental results show that the normal force Fn and the tangential force Ff on the rake face decrease nonlinearly when the tool rake-chip contact length decreases, and there are two inflection points on the Ff-1 curve An inflection point can indirectly measure the rake knife-chip contact length L and close contact length lf1.