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Tool Life Prediction and Avoidance of Cutting Tool Breakage in CNC System

数控系统刀具寿命预测及刀具破损避免

基本信息

批准号：
61550091
负责人：
UEDA Kanji
金额：
$ 0.77万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61550091/
关键词：
Cutting tool breakage Tool life prediction Fracture mechanics Adaptive control Interrupted machining Avoidance of tool breakage 工具欠損回避工具欠損寿命欠損回避予測制御 CNCシステム

项目摘要

Brittle failure of the cutting edge of a tool, such as chipping, fracturing and fatigue cracking, may cause substantial damage to the tool, the workpiece and the machine tool. Extensive efforts have been focused on solving this problem from various points of view including the analytical forecast, monitoring technique and the adaptive control approach. However, an effective method preventing brittle failure has not yet been developed. Therefore, cutting conditions have inevitably been restricted for safety reasons to an underestimated level below the optimum value, and this has necessarily resulted in poor production performances. This is in contrast to gradual type failure, i.e. wear of cutting tool, which have been overcome somewhat successfully by various methods.In this study, a new approach is proposed for adaptive control in interrupted turning where brittle failure predominates, and efficient cutting is performed by optimizing the cutting conditions within time-varying safe-limit determined on the basis of an analysis of the tool life due to brittle failure. This paper first proposes a concept for the adaptive control system, then describes an analytical prediction based on fracture mechanics of the brittle failure of the cutting edge, and discuss adaptive control experiments conducted to avoid brittle failure.The adaptive control experiments are conducted during an interrupted CNC (Computer Numerical Control) turning operation on a plain carbon steel workmaterial using a tungsten carbide tool. It is found that brittle failure avoiance is accomplished in most cutting conditions employed, furthermore quite significant reduction in cutting time is achieved through the adaptive control system. The region where either brittle or wear-type failure can become predominant is also discussed. The proposed system is found more effective when used with larger feed rates, at lower cutting speeds, and with increased rel-cut ratios.

刀具刃口的脆性失效，如切屑、断裂和疲劳开裂，可能会对刀具、工件和机床造成重大损害。人们从分析预测、监测技术和自适应控制方法等多个角度对这一问题进行了大量研究。然而，目前还没有一种有效的防止脆性破坏的方法。因此，由于安全原因，切割条件不可避免地被限制在低于最佳值的低估水平，这必然导致生产性能不佳。这与渐进式失效相反，即刀具的磨损，已经通过各种方法成功地克服了这种失效。本文提出了一种以脆性失效为主的中断车削自适应控制新方法，通过分析脆性失效导致的刀具寿命，在时变安全极限范围内优化切削条件，实现高效切削。本文首先提出了自适应控制系统的概念，然后描述了基于断裂力学的刃口脆性破坏的分析预测，并讨论了为避免脆性破坏而进行的自适应控制实验。利用碳化钨刀具对一种普通碳钢材料进行了中断式数控车削加工，并进行了自适应控制实验。研究发现，该自适应控制系统在大多数切削条件下都能避免脆性破坏，并显著缩短了切削时间。文中还讨论了脆性或磨损型失效占主导地位的区域。当使用较大的进给速度，较低的切削速度和增加的再切削比时，所提出的系统更有效。