硬态切削用刀具技术最新进展

作为具有广泛应用前景的加工工艺,硬态切削以其加工柔性、经济性和环保性等优点,在汽车、模具等行业被广泛应用。该工艺成功实施的关键因素是刀具的合理选择及其性能的发挥。该技术近年来发展迅速,诸多人员和机构对硬态切削工艺所用的刀具进行了深入的研究,有效地推动了该工艺的应用。本文综述了近年来针对硬态切削工艺用刀具的刃型结构、材料选择、刀具涂层等方面的研究成果,并分析了目前被广泛采用的典型刀具型号及其性能,从而为硬态切削工艺用刀具的选用及设计提供指导作用。     

涂层硬质合金刀具干式切削淬硬钢的试验研究

通过采用涂层硬质合金刀具对淬硬 4 5钢硬态干式切削试验 ,分析硬态干式切削淬硬钢的特点 ,研究了涂层硬质合金刀具及其几何参数的优化 ,讨论了涂层硬质合金刀具磨损形式、刀具耐用度及加工表面粗糙度 ,得出了可应用于实际干式切削加工的切削条件和参数     

涂层硬质合金刀具干式切削淬硬钢的试验研究

通过采用涂层硬质合金刀具对淬硬45钢硬态干式切削试验,分析硬态干式切削淬硬钢的特点,研究了涂层硬质合金刀具及其几何参数的优化,讨论了涂层硬质合金刀具磨损形式、鼠具耐用度及加工表面粗糙度,得出院要中应用于实际干式切削加工的切削条件和参数。     

智能生产 绿色制造——以车代磨的绿色工艺

硬态切削是指采用超硬刀具对硬度大干50HRC淬硬钢进行精密切削加工的工艺。通常金属加工中,切削加工一般为软加工,即零件淬火前进行的粗加工。随着高硬度刀具材料和机床的发展,硬态切削技术得到了大量应用,目前硬态切削技术主要是指硬车削技术,即“以车代磨”,而硬态铣削工艺应用较少。     

基于AdvantEdge的硬态精车过程仿真

为探讨硬态精车过程中工艺参数对工件和刀具的影响,采用专门的金属切削仿真软件Advant Edge,建立精车H13淬硬钢的三维有限元模型,对其车削力、刀片切削温度、刀片应力以及切屑进行分析。结果表明:硬态车削过程中,切深抗力在切削过程中起着重要作用,在进给量小于一定值时,切深抗力可以大于主切削力;切削速度越大,刀片温度越高,切削力越小,刀片应力越小,有利于加工表面成型;切削刃半径越小,切削力小,刀片应力小,有利于提高切削加工性能,但小的切削刃半径容易导致刀片磨损;硬态车削切屑呈锯齿状,切屑温度带状分布,切削速度越高,进给量越大,切屑温度越高。研究结论可用于硬态切削过程中的工艺参数优化和刀具及其涂层材料的选择与设计。     

以车代磨的绿色工艺

硬态切削是指采用超硬刀具对硬度大于50HRC淬硬钢进行精密切削加工的工艺。通常金属加工中,切削加工一般为软加工,即零件淬火前进行的粗加工。随着高硬度刀具材料和机床的发展,硬态切削技术得到了大量应用,目前硬态切削技术主要是指硬车削技术,即"以车代磨",而硬态铣削工艺应用较少。硬车加工中,通常采用涂层硬质合金刀具、陶瓷刀具和立方氮化硼(CBN)刀具在新型车床或车削中心上对淬硬钢进行精密车削,取代粗磨甚至是精磨加工。与磨削相比,硬态     

硬态切削与磨削工艺的表面完整性

硬态切削具有良好的加工柔性、经济性和环保性,在对工件性能起关键作用的精加工中,已成为磨削加工的有力挑战者。表面完整性是评价加工质量和工件机械性能的重要指标。本文介绍了硬态切削和磨削工艺的加工表面完整性(包括白层、表面形貌、表面粗糙度、表面残余应力、表面硬化层等),并对二者进行了比较。此外,还分析了硬态切削与磨削工艺相互结合的应用前景。     

硬态切削冷挤压凸模表面粗糙度的试验研究

应用正交试验法研究了硬态切削冷挤压凸模时,切削用量与刀尖圆弧半径对加工表面粗糙度的影响规律,找出了影响加工表面粗糙度的主要因素,得出了最优切削加工参数组合,最后通过了验证试验。     

丝杠硬态旋铣工艺的多目标参数优化

为了进行丝杠硬态旋风铣削下工艺能耗与工艺性能协同优化研究,提出一种同时考虑切削比能、表面粗糙度和表层残余应力的多目标优化方法。基于Box-Behnken试验设计,采用响应曲面法对丝杠硬态旋铣的切削比能、表面粗糙度和表层残余应力进行建模,进一步构建了以丝杠硬态旋铣工艺参数为变量、以低能耗和高性能为优化目标的多目标优化模型。采用改进型非支配排序遗传算法对该模型进行求解,并通过试验数据和优化结果的比较论证了本文优化方法的有效性。     

淬硬钢高速微小孔钻削工艺试验研究

从淬硬钢高速微小孔钻削时钻头承受的负荷入手,以HRC62淬硬轴承钢材料为对象,通过试验的方法,检测和分析钻削过程中动态切削力(轴向力和扭矩)的特征,研究淬硬钢微小孔钻削的可行性和切削条件。并通过试验研究切削速度、进给量等钻削工艺参数对切削力的影响规律,提出改善硬态切削性能、提高钻头耐用度的淬硬钢微小孔钻削工艺规范。     

A key parameter to characterize the kerf profile error generated by abrasive water-jet

As the only cold high-energy beam machining technology, abrasive water-jet (AWJ) is one of the most rapidly developed techniques in material manufacturing industry. However, the application of AWJ is limited by the cutting accuracy it can achieve. Kerf profile generated by AWJ is different as the cutting parameters change. As a result, it has become a major factor which affects the cutting accuracy when AWJ is used as a machining tool. Researchers used taper error to characterize kerf profile error generated by AWJ in the past years. And many efforts have been put on how to eliminate taper error by using a tilting cutting head of a 5-axis AWJ machine. However, using taper error to characterize the kerf profile error generated by AWJ is not accurate since kerf profile error might appear in different styles. And using a 5-axis AWJ machine to eliminate taper error is only effective in some special cases. To effectively eliminate taper error, the first thing needs to do is to find out whether the kerf profile error can be compensated or not. Based on research, a key parameter, named kerf profile coefficient O, which can be used to characterize kerf profile error and further to guide people to use different ways to compensate kerf profile error, has been defined in this paper. To further illustrate the efficiency of this coefficient, a series of cutting experiments have been carried out and the experimental results have been discussed.     

An experimental study on the machining characteristics in ductile-mode milling of BK-7 glass

Glass is considered as one of the most challenging materials to machine because of its high hardness coupled with high brittleness. The challenge, in machining such a brittle material, lies in achieving the material removal through plastic deformation rather than characteristic brittle fracture. It has already been established that every brittle material, no matter how brittle it is, can be machined in ductile mode under certain critical conditions. The critical conditions are material specific, and hence, every material tends to show unique behavior in terms of critical conditions during machining process. This paper outlines the results of an experimental study to determine the critical chip thickness for ductile–brittle transition, chip morphology, and the effect of cutting speed on the critical conditions in peripheral milling process of BK-7 glass. It is established experimentally that the cutting speed affects the chip morphology, machined surface quality, and critical conditions due to possible thermal effects in such a way that ductile–brittle transition phenomenon is facilitated at high cutting speeds.     

恒定加工条件及定期补偿下的刀具渐变可靠性灵敏度分析方法

据统计,由刀具失效导致的停机时间超过机床被迫停机时间的1/3,故开展刀具渐变可靠性及其灵敏度分析的研究对提高机床的运行可靠性具有重要意义。采用连续时间、连续状态、具有非减独立增量的非平稳Gamma过程描述刀具磨损量的变化过程。根据加工偏差不大于机床给定加工精度的原则,构建刀具制造及磨损量检测有无误差两种情形下、恒定加工条件及定期补偿的刀具渐变状态函数,由此推导出相应的渐变可靠度模型。在此基础上给出渐变可靠度模型对各个参数的灵敏度计算方程。通过数值实例分析,阐述了通过提出的渐变可靠性模型及灵敏度分析方法提高刀具运行可靠性的应用过程。这一工作为提高恒定加工条件及定期补偿下刀具的运行可靠性提供切实可行的理论和方法基础。     

一类蜗杆传动啮合方程的研究

本文导出了某一类蜗杆传动的啮合函数一般公式,它适用于轨迹曲面蜗杆（这种蜗杆齿面由一条曲线作刚体运动而产生）传动和化为这种类型的蜗杆传动。文中对加工蜗杆齿面时刀刃曲线的不同形状,依据公式得到了相应蜗杆传动啮合方程的可解规律。工业生产中几种重要的蜗杆传动的啮合方程,都可化为关于某参数的至多四次代数方程。     

Surface layer microhardness changes with high-speed turning of hardened steels

In high-speed cutting of hardened steels, the surface layer is strongly affected by thermal effects and mechanical forces. Due to this, the surface layer of the machined material changes noticeably. Microhardness, one parameter of the surface integrity, is the most important. This paper deals with an investigation of microhardness. Measuring results are presented, and reasons for the sometimes significant changes in microhardness are analysed. It is proved on which part of the cutting edge the material removal will not take place but the cutting edge deforms the material plastically and how this part of the cutting edge can be reduced. With the measurement of the cutting force, the hypothesis is proved that the values of the cutting force components related to each other are different compared to the traditional turning. The passive force is 1.88?C2.25 times higher than the main cutting force. Hence, the force taking place on the flank face of the cutting tool is very high and the friction power significantly influences the cutting temperature. The friction taking place on the flank face of the cutting tool generates 2.8?C3.9 times higher heat than the cutting force. Due to the changes that occur in the surface layer, the hardness of this layer is higher with 100?C150?HV in depth of 0.1?mm than the original hardness or the hardness prescribed in the technical drawings. This phenomenon can be observed not only in internal hard turning but also machining of external and conical surfaces. Microhardness is compared after hard turning and after grinding. According to the measurements, the ground surface has not become a harder surface layer but softer. As an average result of many measurements, it has been proven that the original hardness (700?HV) after case hardening will increase to 800?C850?HV after hard turning and will decrease to 500?C550?HV after grinding. Microhardness changes are analysed considering the typical chip removal characteristics of hard turning. In this article, the focus is on how changes in microhardness influence the functional behaviour of the components and may affect their lifetimes. In this article, it has been proven that independently from the surface of the machined gear (bore, conical or face surface) the changes in the surface layer regarding microhardness do not differ.     

基于钝圆尺寸效应的微细切削机理试验研究

通过微细车削试验,研究了微细切削加工参数对切削力、表面质量、切屑形成的影响,发现切削厚度与刃口半径的比值是影响微细切削的关键因素,当该比值过小时,刃口尺寸效应作用极其显著,导致切削比能迅速增大,表面质量恶化,切屑形成困难。根据这一结论可确定微细切削加工参数选择的下限范围,从而为微细切削加工参数选择提供理论依据。     

干式冷风车削不锈钢的高速钢刀具磨损试验研究

采用低温冷风射流技术,对高速钢刀具加工不锈钢工件的磨损情况进行了试验研究。加工时采用低温冷风射流空气代替传统的切削液,不仅起到有效的冷却和润滑作用,而且能够避免环境污染。通过干式常温切削和干式冷风切削1Cr18Ni9Ti的不锈钢的对比实验,探讨了干式低温冷风切削对高速钢刀具寿命的影响,并且发现了在冷风切削作用下积屑瘤生成的新特点。     

基于共边切割方法的板材切割路径优化

常规的板材切割是切割完一个零件后再去切割另一个零件,如果两个零件的边有公共部分,则利用共边切割方法只进行一次切割就可以完成,这不但能提高切割效率而且还能节省切割成本.然而目前有关共边切割方法的研究还不太深入,共边切割方法对于切割路径的优化效果还没有完全发挥出来.提出了基于图论的"一笔画"共边切割方法和针对阵列矩形的"阶梯形"共边切割方法,并给出了实例.实例结果表明,提出的共边切割方法比现有的方法在割嘴和空行程和打孔点数上都有了很大的优化.     

振动切削技术及最新发展

振动切削是近年来发展起来的一种新型切削加工技术,它能获得普通切削无法比拟的工艺效果,是现代切削技术的一个重要发展方向.文中对振动切削及其分类、特点进行了综述,介绍了近年来振动切削的最新研究应用状况,指出了振动切削目前仍然存在的问题,并对今后研究的发展方向进行了展望.     

Prediction of regenerative chatter in the high-speed vertical milling of thin-walled workpiece made of titanium alloy

With the wide application of high-speed cutting technology, high-speed machining approach of titanium alloy has become one of the most effective ways to improve processing efficiency and to reduce the processing cost, but the cutting chatter which often occurs in the cutting process not only affects the machining surface quality but also reduces the production efficiency. Regenerative chatter is a typical phenomenon during actual cutting, and it has the greatest impact on the cutting process. With the purpose of avoiding regenerative chatter and selecting appropriate cutting parameters to achieve a steady cutting process and a high surface quality, it is necessary to determine the critical boundary conditions where chatter occurs. Built on the work of previous theoretical researches of regenerative chatter, this paper utilized Visual C++ software to calculate the chatter stability domain during the finish machining of titanium alloy. It was shown that the border between a stable cut and an unstable cut can be visualized in terms of the axial depth of cut as a function of the spindle speed. Using the result, it can find the specific combination of machining parameters, which lead to the maximum chatter-free material removal rate. In order to verify the result, the high-speed milling experiment of an I-shaped thin-walled workpiece made of titanium alloy was conducted. It revealed that the actual machining result was consistent with the calculation prediction. This study will offer a useful guide for effective parameter selection in future CNC machining applications.