基于快速刀具伺服的自由曲面车削中切削力建模与分析

发布时间：2018-03-13 00:01

本文选题：自由曲面　切入点：快速刀具伺服　出处：《吉林大学》2016年硕士论文　论文类型：学位论文

【摘要】：快速刀具伺服(Fast tool servo,以下简称FTS)是安装在车床上的一种辅助运动轴,不仅可实现刀具沿x或z轴的快速往复直线运动,也可实现刀具绕B轴的快速往复摆动。在此“快速”是一个相对的概念,主要是指比传统上直接利用车床的运动轴作往复运动可以获得更高的运动频率;“伺服”则是强调对刀具的运动轨迹进行跟踪控制。FTS主要涉及如下三个方面的工程应用:(1)车削具有非回转对称性的轴类或孔类零件。(2)车削具有非回转对称性的光学自由曲面或微结构表面零件。(3)主动补偿车床的综合误差,尤其是非单调的动态误差成分,可有效解决机床大惯性运动轴无法快速往复运动的问题以及运动轴误差补偿时误差发散为题。采用快速刀具伺服(FTS)的车削加工系统主要是用于精密或超精密加工,对工件的加工表面质量有更高的要求,因此对切削力的产生机理和建模过程有必要进行更为透彻的研究。建立有效的切削力模型将有助于更好的让人们了解伺服切削过程、刀具的磨损机制,同时对快速刀具伺服切削加工、设计有着重要的指导意义。快速刀具伺服车削与传统车削存在很大不同,主要差异总结为如下两个方面:(1)快速、往复变化的交变切削力。其中变化体现在切削力的方向与切削厚度两个方面;(2)快速刀具伺服车削的切削用量很小,往往在微纳米级,因此刀尖的钝圆半径与刃口圆弧对切削力以及切削表面将产生重大影响。针对以上所提出的问题,本论文的主要包括以下工作内容:1、根据快速刀具伺服的切削过程及切削特点,建立了一种引入刀尖圆弧、刀尖钝圆的基于正交切削的复合切削力模型,即在不同的切削深度利用不同的切削机理对切削力进行预测。分别对刀具前刀面、刀尖钝圆上半部分和刀尖钝圆下半部分利用解析法得到切削力的预测值。2、基于切削力的理论模型对切削力进行了Matlab仿真,同时也分析了模型中各个参数对切削力变化的影响大小。从数值分析的角度初步验证了切削力模型的准确性和合理变化趋势。3、设计了一种带有测量切削力功能的单自由度FTS,解决了在FTS切削过程中切削力测量困难及不准确的问题,由于本文设计FTS的初衷是为了通过实验的方法进一步验证模型的准确性,因此测力FTS的实用性和可靠性就必须得到保证。单自由度的设计相对于两自由度、三自由度FTS的可靠性将有很大提高。本文所设计的FTS通过合理的布置压力传感器的位置,能有效测量Y向(主切削力方向)切削力,因此相比其他测力FTS,有效、准确的测量Y向切削力将更有意义。
[Abstract]:Fast tool Servo (FTS) is a kind of auxiliary motion shaft installed on lathe, which can not only realize the fast reciprocating straight line motion of the tool along x or z axis. It is also possible to realize the rapid reciprocating and swinging of the tool around the B axis. In this case, "fast" is a relative concept. "Servo" is an engineering that emphasizes tracking and controlling the movement path of the tool. FTS mainly involves the following three aspects. Using 1) turning shafts or holes with non-rotational symmetry.) turning optical free-form surfaces with non-rotational symmetry or micro-structural surface parts. 3) actively compensating the synthetic error of lathe. Especially the nonmonotone dynamic error components, It can effectively solve the problem that the large inertia moving shaft of machine tool can not move quickly and the error divergence when the error of moving shaft is compensated. The turning system with fast tool servo FTS is mainly used for precision or ultra-precision machining. It is necessary to make a more thorough study on the mechanism of cutting force and the modeling process because of the higher quality of machined surface of the workpiece. Establishing an effective cutting force model will help people to understand the servo cutting process better. The wear mechanism of the tool is also of great significance to the design of the servo cutting of the fast cutting tool. There is a great difference between the servo turning of the fast tool and the traditional turning. The main difference is summarized as follows: 1) fast. Reciprocating alternating cutting force. The change is reflected in the direction and thickness of the cutting force) the cutting parameters of the fast tool servo turning are very small, often at the micro and nanometer level. Therefore, the radius of blunt circle and the arc of cutting edge have great influence on the cutting force and cutting surface. In view of the above mentioned problems, this paper mainly includes the following work contents: 1, according to the cutting process and cutting characteristics of the rapid cutting tool servo, A compound cutting force model based on orthogonal cutting is established, which introduces the arc of the tool tip and blunt circle of the cutter tip, that is, the cutting force is predicted by using different cutting mechanism at different cutting depth. The prediction value of cutting force is obtained by analytic method. The cutting force is simulated by Matlab based on the theoretical model of cutting force. At the same time, the influence of each parameter of the model on the cutting force change is analyzed. The accuracy and reasonable change trend of the cutting force model are preliminarily verified from the point of view of numerical analysis, and a kind of cutting force measuring function is designed. The single degree of freedom FTS solves the difficulty and inaccuracy of measuring cutting force in FTS cutting process. Since the original intention of this paper is to verify the accuracy of the model by the experimental method, the practicability and reliability of the force-measuring FTS must be guaranteed. The design of single degree of freedom is relative to that of two degrees of freedom. The reliability of 3-DOF FTS will be greatly improved. The FTS designed in this paper can effectively measure the cutting force in Y direction (in the direction of main cutting force) by reasonably arranging the position of the pressure sensor. Accurate measurement of Y cutting force will be more meaningful.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG51

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