基于TwinCAT的自适应数控车削系统设计

发布时间：2018-04-29 03:07

本文选题：开放式数控系统 + 恒负荷切削　；参考：《西南交通大学》2017年硕士论文

【摘要】：开放式数控系统是为了适应机床制造业在技术、市场和生产组织等多方面新的变化而提出的,其目的是使数控系统易变,具有很好的适应性和二次开发性。在CAK6136车床上进行了基于TwinCAT的开放式数控系统改造,对CAK6136车床的主轴控制、伺服轴控制、刀架转位控制等强电部分进行了整理分析,确定了所需TwinCAT模块的数量种类,通过TwinCAT PLC中关于轴控制的相关功能块和库实现了 CAK6136车床的伺服功能和相关辅助功能,完成了对CAK6136车床的开放式数控改造。恒负荷切削是一项极具工程意义的研究,国内外自适应切削主要就是恒负荷自适应切削。文章研究了基于主轴电流的切削力间接测量方案,通过实验论述了以电流有效值作为切削状态表征量可靠性,为了避免各种随机性因素对电流有效值产生影响,提出了以实时测量空载电流,并以切削电流有效值与空载电流有效值的差值作为切削状态表征量的方案。最后通过BP神经网络,实现了切削状态的在线检测以及恒负荷加工中进给量的计算。车削过程中颤振是导致切削不稳定的主要原因,通过实验发现颤振时主轴电流的概率密度分布情况与切削是否发生颤振有密切关系,切削状态越接近于颤振状态,电流的概率密度分布的双峰性越明显。通过核概率密度函数估计方法来在线辨识切削状态是否为稳态切削,并通过在线调节进给量来防止颤振的发生。最终实验表明在CAK6136车床上运用变进给量车削能提高加工表面的质量并能加大切削效率。
[Abstract]:Open CNC system is proposed to adapt to the new changes in technology, market and production organization of machine tool manufacturing industry. The purpose of the system is to make CNC system changeable, with good adaptability and secondary development. The open CNC system based on TwinCAT was reformed on CAK6136 lathe. The main axis control, servo shaft control and tool frame transposition control of CAK6136 lathe were arranged and analyzed, and the quantity and types of TwinCAT modules were determined. The servo function and related auxiliary function of CAK6136 lathe are realized by using the relevant function blocks and libraries about shaft control in TwinCAT PLC, and the open NC transformation of CAK6136 lathe is completed. Constant load cutting is a research of great engineering significance. Adaptive cutting at home and abroad is mainly constant load adaptive cutting. In this paper, the indirect measuring scheme of cutting force based on spindle current is studied. Through experiments, the reliability of current RMS as the cutting state token quantity is discussed. In order to avoid the influence of various random factors on the current RMS, A scheme of measuring no-load current in real time and using the difference between the effective value of cutting current and the effective value of no-load current as the characteristic of cutting state is put forward. Finally, the on-line detection of cutting state and the calculation of feed rate in constant load machining are realized by BP neural network. The chatter is the main cause of cutting instability during turning. It is found that the probability density distribution of spindle current is closely related to whether the cutting chatter occurs or not, and the cutting state is closer to the chatter state. The bimodal distribution of probability density of electric current is more obvious. The kernel probability density function estimation method is used to identify whether the cutting state is steady-state or not, and to prevent chatter from occurring by on-line adjusting the feed rate. The final experiment shows that using variable feed turning on CAK6136 lathe can improve the quality of the machined surface and increase the cutting efficiency.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG519.1

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