高速切削切屑折断界限变化规律

为进行高速切削切屑折断界限变化规律研究,采用具有代表性的三维复杂槽型车刀片进行11种常速、高速断屑试验.在分析试验数据基础上,得到切屑折断界限曲线及其共性切屑折断界限曲线.在对三次样条函数插值方法进行分析,以及应用二次、三次多项式拟合方法建立切削速度与极限进给量、断屑范围之间变化规律的数学模型的基础上,优选出误差小、计算简单的数学模型.发现在各种切削速度下极限背吃刀量是定值,并且极限背吃刀量曲线是垂直直线,为此建立新的极限背吃刀量数学模型.结合具有代表性的三维复杂槽型车刀片,研究极限进给量变化规律,并推导出极限进给量理论预报公式.三维复杂槽型切屑折断界限曲线及其数学模型的建立,可为今后高速切削领域里三维复杂槽型车刀片断屑机理及其预报系统的研究打下理论与试验基础.     

复杂槽型数控车刀片断屑预报系统的研究

针对数控车削加工过程中切屑折断难以预测问题,依据切屑折断界限理论建立了极限进给量和极限切削深度的预报数学模型:以上述数学模型为核心,开发了复杂槽型数控车刀片的断屑预报系统.为了验证预报结果的准确性,选取了典型的复杂断屑槽型车刀片切削45钢的断屑试验结果与预报结果进行了对比,对比结果显示二者基本一致,从而证明断屑预报结果的准确性和断屑预报系统具有一定的实用性.     

复杂槽型车刀片切屑约束与折断预报的研究

在刀片槽型结构对切屑约束的影响研究基础上,建立了复杂槽型车刀片切屑约束与折断预报模型,提出了基于切屑约束的复杂槽型车刀片切屑卷曲与折断预报方法,并进行了三维复杂槽型车刀片切屑约束与折断的试验研究。结果表明:该模型对于复杂槽型车刀片断屑性能的预报和刀片槽型的优选具有实际应用价值。     

新型圆弧角回转断屑器设计与切屑折断实用预报公式的建立

依据断屑原理,研究和设计一种新型圆弧角回转断屑器。该断屑器在整体上呈圆台状,在锥面上均匀设置了圆弧角。结合压板,断屑器实现断屑可靠、断屑范围宽、操作简便、使用寿命长等功效。同时推导出在该装置下的切屑过销钉的回转轴线与切屑流速方向所形成的剖面内的折断和切屑沿回转断屑器回转折断两种极限情况的切屑折断实用预报公式;进行了两种极限情况的断屑试验,试验研究结果验证了该断屑器的有效性。     

硬质合金刀片嵌入式辅助断屑器的设计

为了扩大硬质合金刀片的断屑范围,结合硬质合金刀片三维槽型的结构特征和刀片安装方式,设计并制作了一种嵌入式辅助断屑器。进行了铝合金切削实验,观察了切屑形貌,并分析了切屑折断机理。实验结果表明,未安装嵌入式辅助断屑器时,硬质合金刀片在小切深下可以实现断屑;但在大切深时,产生长螺卷屑,硬质合金刀片的断屑效果变差。安装嵌入式辅助断屑器后,在大切深时,硬质合金刀片产生了C形屑。嵌入式辅助断屑器的反屑面增加了断屑台的高度和角度,进一步减小了切屑的卷曲半径,促进了切屑的折断。安装了嵌入式辅助断屑器的刀片具有较高的断屑率,扩大了硬质合金刀片的断屑范围。     

基于WTK软件的切屑形成与折断过程虚拟现实的研究

采用虚拟现实 (VR)技术 ,以 VC++6 .0和虚拟现实软件 World Tool Kid9.0为开发平台 ,以切屑折断数学模型为理论研究基础 ,对于给定的切削参数 ,实现了三维复杂槽型刀片在车削加工时切屑形成与折断过程的虚拟现实 ,预报了切屑折断过程 ,从而可评估切削刀片槽型设计质量 ,优选槽型 ,有利于缩短刀片设计和制造周期     

切屑空间运动轨迹及其约束方程的研究

切屑控制技术是现代先进机械制造系统中的基础关键技术，切屑　控制技术不解决，任何一个理想的自动化过程都不能实现。系统研究了切屑的空间运动轨迹　，获得了切屑空间运动轨迹数学模型；建立了切屑在形成过程中与障碍物（工件及刀具）表面　的约束方程。上述研究成果是研究切屑形成与折断过程的有效途径，为进行刀片槽型优选及　设计以及切屑折断预报系统的研制奠定理论基础。     

硬质合金刀片断屑槽槽型对其切削性能的影响

采用具有多种断屑槽槽型的同种基体材质的刀片进行车削实验,应用高速摄影机捕捉切削区域切屑产生、流出、卷曲和折断过程。通过磨损测量仪观测断屑槽,并结合切屑形态分析,明确断屑槽合理几何形状;通过三维受力分析仪采集切削过程中的振动和切削力信号,揭示断屑槽对切削力的影响规律;综合切削参数、断屑槽几何结构和切削力三方面的因素,最终确立断屑槽槽型与进给量对切屑折断的作用机制。研究数据以期为断屑槽设计与车削刀具的应用提供数据支撑。     

断屑槽型的计算机辅助设计

本文是根据切屑折断界限理论，进行的二维断屑槽型可转位刀片计算机辅助设计的总结，使用本文所述ＣＡＤ系统，可实现ＴＮＭＭ，ＳＮＭＭ三种ＣＮＭＭ（３５°，５５°，８０°）刀片５种尺寸规格的自动设计。     

新型金属陶瓷刀片

加工低碳钢等材料时，容易形成软质切屑，不易折断排出。日本住友电工公司针对这一特点，开发出一种新型可转位刀片，配以FA型断屑槽。新型刀片在切削刃尖端部分和侧壁部分作了较大改进，断屑排屑性能大为提高，切屑沿径向卷曲成小卷，可在最佳尺寸处折断。前刀面尖端部分的前角为20°，前刀面上有小坑，可将切屑引人凹面断屑槽，并在1～3cm范围内折断。刀片材料系住友公司新开发的高韧性金属陶瓷，耐磨性和抗崩刃性均有较大改善，与过去的金属陶瓷相比，使用寿命提高2～4倍，可用于高精度切削加工。此种刀片拟于1997年4月投放市场，届时该…     

车削中三维复杂断屑槽刀具断屑仿真研究

为有效缩短现有断屑槽刀具的设计周期、降低设计成本,采用有限元方法模拟了切削过程中切屑折断过程。利用Solid Works软件建立了三种刀具的三维模型,并在Deform 3D软件中对车削45钢工件过程进行了三维切削仿真。其中,工件材料采用了Johnson-Cook模型和Cockroft-Latham韧性断裂准则,仿真模型采用了有效参数设置以保证数值计算精度与效率。通过仿真研究了不同切削参数下的切屑形态、断屑过程及主切削力等。研究结果表明,仿真结果与试验结果吻合良好,该仿真模型及方法能有效应用于断屑槽刀具断屑性能研究,是三维复杂断屑槽刀具设计和切削参数优化的一种新方法。     

Effect of high-pressure cooling on life of SiAlON tools in machining of Inconel 718

High-pressure cooling has proven to be very effective when machining with carbide inserts. Longer tool life and improved chip breaking are among the most commonly mentioned advantages. Nevertheless, this cooling method has been reported to reduce the life of ceramic tools in machining of heat-resistant alloys. The main reason for that is said to be the accelerated notch wear. Therefore, in this study, SiAlON ceramic inserts with improved resistance to notching were tested in machining of Inconel?718 under high-pressure cooling. The results were compared to conventional cooling. It turned out that, while notch wear was still slightly increased when high-pressure cooling was applied, it was no longer critical for the tool life. Flank wear, on the other hand, was reduced, which led to significantly longer tool life. The variation of the tool life appeared to be slightly less and chip breaking was considerably improved. This shows that, when used properly, high-pressure cooling can help to increase the productivity in machining of heat-resistant alloys with ceramic tools.     

Efficient Chip Breaker Design by Predicting the Chip Breaking Performance

As machining technology develops toward the unmanned and automated system, the need for chip control is considered increasingly important, especially in continuous machining such as in the turning operation. In this study, a systematic chip breaking prediction method is proposed using a 3D cutting model with the equivalent parameter concept. To verify the model, four inserts with different chip breaker parameters were tested and their chip breaking areas were compared with those obtained from the model. Finally, a new type insert (MF1) for medium-finish operations with variable parameters was designed by modifying the commercial one. The chip breaking region predicted by using the modified 3D cutting model for the above insert agrees with the one obtained experimentally. The newly designed insert showed better chip breaking ability than the base model, and other performance tests such as surface roughness, cutting force and tool wear also showed good results.     

A STUDY ON CHIP BREAKING LIMITS IN MACHINING

Prediction of chip breaking in machining is an important task for automated manufacturing. This paper presents a study on chip breaking limits. Based on the chip breaking curve, the critical feed-rate is modeled through an analysis of up-curl chip formation, and the critical depth-of-cut is formulated through a discussion of side-curl dominant chip formation processes. Factors affecting chip-breaking limits are also discussed.

In order to predict the chip breaking limits, semi-empirical models are established. Although the coefficients that occur in the model are estimated through machining tests, the models are applicable to a broad range of machining conditions. The model parameters include machining conditions, tool geometry, and workpiece material properties.     

A STUDY ON CHIP BREAKING LIMITS IN MACHINING

Abstract

Prediction of chip breaking in machining is an important task for automated manufacturing. This paper presents a study on chip breaking limits. Based on the chip breaking curve, the critical feed-rate is modeled through an analysis of up-curl chip formation, and the critical depth-of-cut is formulated through a discussion of side-curl dominant chip formation processes. Factors affecting chip-breaking limits are also discussed.

In order to predict the chip breaking limits, semi-empirical models are established. Although the coefficients that occur in the model are estimated through machining tests, the models are applicable to a broad range of machining conditions. The model parameters include machining conditions, tool geometry, and workpiece material properties.     

FORECAST OF BREAKING LENGTH OF SIDE CURLING SHORT-SPIRAL CHIPS

０　ＩＮＴＲＯＤＵＣＴＩＯＮＯｎｅｏｆｔｈｅｃｒｉｔｉｃａｌｐｒｏｂｌｅｍｓｎｅｅｄｓｔｏｂｅｓｏｌｖｅｄｉｍｍｅｄｉａｔｅｌｙｉｎａｕｔｏｍａｔｉｏｎｏｆｍａｃｈｉｎｉｎｇｉｓｄｉｓｐｏｓａｌｏｆｃｈｉｐｓａｎｄｔｈｉｓｌｉｅｓｐａｒｔｉａｌｌｙｉｎｔｈｅｂｒｅａｋｉｎｇｏｆｃｈｉｐｓｉｎｔｏａｃｅｒｔａｉｎｌｅｎｇｔｈ．Ｃｈｉｐｂｒｅａｋｉｎｇｉｓｎｏｔｏｎｌｙｒｅｌａｔｅｄｔｏｔｈｅｓｈａｐｅａｎｄａｎｇｌｅｓｏｆｔｈｅｔｏｏｌ,ｂｕｔａｌｓｏｔｏｔｈｅｍａｃｈｉｎｉｎｇｍａｔｅｒｉａｌ…     

聚晶金刚石刀具的断屑槽尺寸参数设计

为解决聚晶金刚石(PCD)刀具在铝合金材料切削过程中的切屑缠绕问题,在PCD刀具的前刀面上设计了断屑槽.通过对切屑受力过程和断屑槽断屑机理的分析、切削几何关系的推导和有限元切削仿真实验,提取了5个PCD刀具断屑槽参数,即棱带宽度、倾角、反屑角、槽宽和反屑面转角.建立了PCD刀具断屑槽棱带宽度和反屑角的计算公式;改进了槽...     

利用VC和Pro/Engineer联合编程设计三维复杂槽型车刀片

作者用Pro/Engineer的二次开发软件包Pro/TOOLKIT开发了三维复杂槽型车刀片的自动化设计系统,使用起来方便,界面简单直观,降低了设计人员的工作量,缩短了刀片的设计周期,改变了目前存在的车刀片设计靠经验加实验定性的局面,而且车刀片的三维复杂槽型可以有效折断切屑,避免了因断屑问题引起的非正常停机,提高了设备利用率和产品竞争力,适应了当前竞争日益激烈的市场要求。     

Prediction of chip flow angle in orthogonal turning of mild steel by neural network approach

Improvement of chip control is a necessity for automated machining. Chip control is closely related to chip flow and it plays also a predominant role in the effective control of chip formation and chip breaking for the easy and safe disposal of chips, as well as for protecting the surface-integrity of the workpiece. Although several ways to predict the chip flow angle (CFA) have been subjected in some researches, a good approximation has not been achieved yet. In this study, using different indexable inserts and cutting conditions for turning of mild steel, the chip flow angles were measured and some of the collected data from this experimental study were used for training with a two hidden layered backpropagation neural network algorithm. A group was formed from randomly selected data for testing. The chip flow angle values found from multiple regression, neural network (NN) and studies of previous researchers under the same turning conditions of the present study were compared. It has been seen that the best prediction was obtained by neural network approach.