AISI 316L奥氏体不锈钢作为典型的难加工材料，存在着加工效率低和加工过程热-力载荷大的问题。现有关于改善不锈钢加工性能的若干方法，如采用润滑措施、设计刀具表面结构等，均存在明显缺陷，例如，切削液的大量使用不利于环境和人体健康，刀具表面结构的不合理设计反而会加剧刀具磨损。针对现有方法无法很好改善奥氏体不锈钢加工过程热-力载荷大等问题，文中设计了一种新型变接触长度的限制接触刀具，用于加工AISI 316L奥氏体不锈钢，其与传统限制接触刀具相比可以有效减小切削力和摩擦系数。研究中首先基于非等距剪切区模型和切削力学理论，建立了用于预测变限制接触长度的限制接触刀具在车削时的切削力半解析模型；然后，在硬质合金刀具前刀面上通过线切割和微细电火花加工出常规和新设计的限制接触形状（矩形以及梯形限制接触形状），并进行了大量实验用于验证预测模型。结果表明：利用所建立的半解析模型预测出的切削力与实验数据吻合较好；与传统限制接触刀具相比，变限制接触长度的刀具能明显减小切削力。此外，文中还对比分析了传统和变接触长度的限制接触刀具在干切削条件下对切削性能的影响，发现变限制接触长度的刀具比传统限制接触刀具能更有效地降低切削温度和减少刀具磨损。文中研究结果可为切削难加工材料的刀具的设计提供参考。

As a typical difficult-to-machine material, AISI 316L austenitic stainless steel has the problems of low machining efficiency and large thermo-mechanical load during machining. The present methods to improve the machining performance of stainless steel such as adopting lubrication, designing tool surface structure, etc., all exist obvious defects. For example, the extensive use of cutting fluid is detrimental to the environment and human health, and tool wear will be aggravated if the tool surface structure is designed unreasonably. Given that the existing methods fail to well deal with the problems like large thermo-mechanical load during machining austenitic stainless steel, a new restricted contact tool with variable contact length was designed aiming at machining AISI 316L auste-nitic stainless steel. Compared with traditional restricted contact tools, the new tool is superior in reducing cutting force and friction coefficient. This paper first developed a semi-analytical model for turning to predict cutting forces for inconstant restricted contact length based on the non-equidistant shear zone model and the principles of unified cutting mechanics. Then, the conventional and variable-length restricted contact pattern (rectangular and trapezoidal restricted contact pattern) was fabricated on the rake surface of uncoated cemented carbide by the W-EDM and micro-EDM process. Subsequently, extensive experiments were performed to validate the proposed model. Results show that the cutting forces predicted by the proposed semi-analytical model are in good agreement with the experimental values. As compared with conventional restricted contact tools, the developed restricted contact tool can significantly reduce cutting forces. Furthermore, the influences of conventional and developed restricted contact tools on cutting performance were compared and analyzed under dry machining conditions. The restricted contact tool developed in this paper can effectively decrease the cutting temperature and tool wear. This study can provide a basis for designing the cutting tools in machining difficult-to-cut materials.