【作者】 肖露；

【导师】 刘献礼；

【作者基本信息】 哈尔滨理工大学 ， 机械制造及其自动化， 2002， 硕士

【摘要】 淬硬钢是典型的耐磨和难加工材料，采用PCBN刀具实施硬态切削工艺可改变传统切削-淬硬-磨削制造工序，能有效地提高工件的疲劳强度及生产率、降低能量消耗。PCBN刀具切削淬硬钢时切削力的变化规律是衡量PCBN刀具切削性能的重要因素之一。探明PCBN刀具切削力的变化规律有助于选择高刚性的机床、消除切削过程的振动、优化PCBN刀具结构及监控硬态切削过程等。因此，本文在实验的基础上对硬态切削力进行了研究，针对硬态切削的特点，建立了硬态切削模型，并对硬态切削力进行了预报和控制。采用De Beers公司的AMBORITE DBC50 PCBN刀具在CA6140可变频调速车床上对淬硬轴承钢GCr15进行了一系列切削力实验。实验结果表明径向力最大，其次是主切削力和轴向力。切削力随进给量、背吃刀量和倒棱宽度的增大而线性增大；硬态切削力与切削速度和工件硬度的变化规律有别于普通的切削理论，实验结果表明切削速度和工件硬度均存在一个临界值，在该临界值上切削力有最小值。研究硬态切削力的影响因素及其变化规律可为PCBN刀具结构和刃口的制备、切削参数的选择、切削过程控制提供理论依据，对于指导生产实践有着重要的参考价值。提出了一种考虑刀具刃口作用的切削模型来预报硬态切削力的方法。采用考虑PCBN刀具倒棱刃口作用的最小能量法预报剪切角，同时提出了基于单刃刀具和等效切削刃弦法的流屑角新模型，给出了流屑角模型的求解，在此基础上，通过研究切削刃刃口附近的作用机理和刃口力的大小，建立了硬态切削力方程，在MATLAB环境下对切削力进行了预报，预报结果很好的反映了切削力的变化趋势，与实验结果吻合较好，为进一步研究硬态切削工艺系统、已加工表面完整性和切削过程监控提供了参考数据。从硬态切削力的特点出发，根据MATLAB/SIMULINK设计了硬态切削径向力控制系统。对比了普通PID控制算法和PID/PD复合控制算法的恒定切削力控制性能。PID/PD控制器具有更好的稳定性和可靠性，可很好的满足对径向力Fy的控制，从而防止加工过程中的振动，提高切削加工精度和刀具寿命。更多还原

【Abstract】 As the hardened steel is a typical scuff -resistance and bad machining material, the traditional manufacture order such as cutting-harden-grinding may be changed by using PCBN tool carry out hard turning, and the weariness strength and productivity of workpiece is improved, and the consumed power is reduced The change rule of cutting force while cutting hardened steel by PCBN tools is an importance factor of cutting property of PCBN tools. Study of the change rule of PCBN tool is used to choose high property lathe, eliminate librations, optimize PCBN tools structure and supervising hard turning process, etc. In this paper, the hard cutting force based on experiment is studied, for characteristic of hard turning, harden cutting model is built, and the harden cutting force is forecasted and controlled. In this paper, the hardened bearing steel GCr15 is selected to be the material，a series of cutting forces experiments were done with AMBORITE DBC50 PCBN tool which was supplied by De Beers Industrial Diamonds with CA6140 lathe. The results indicate that in general, the radial force was the highest, followed by the tangential and axial forces. Cutting forces increased almost linearly with feed rate and depth of cut and width of edge, and the change rule of cutting force affected by cutting speed and rigidity of workpiece is different of ordinary cut theory. The results show that there are critical cutting speed and critical rigidity of workpiece, at the critical value, the cutting force is the lowest. The study of effect factors and change rule of cutting force provide theoretic foundation for PCBN tool structure and edge manufacture, cutting parameter selection and process control, and there is important reference meaning for guide production practice.A new cutting force model coupled with edge forces for hard turning is developed to evaluate cutting forces. The least energy method coupled with the effect of PCBN tool edge is developed to evaluate chip flow angle, at the same time, An new analytical chip flow angle model based on single edge tool and equivalent edge is developed, and the solution of chip flow angle model is provided. The equation about harden turning force is established by studying of edge force and acting<WP=6>mechanism near cutting edge, and the cutting force is forecasted in MATLAB environment. Forecasting results reflect cutting force change trend and consistent with experimental result. It provides reference data for more researching cutting technology system, integrality of machined surface and supervising cutting process.A system for control radial force is designed to application in hard turning process, which based on MATLAB/SIMULIINK. A simple PID control algorithm and PID/PD control algorithm is presented and their performances are compared. The PID/PD control algorithm shows relatively security and stabilization, and it very satisfies the demand for control radial force, so it can avoid librations in machining process and improve turning precision and tool life.更多还原