钛合金铣削加工中的刀具扩散磨损的研究

本文针对在较高切削速度下使用硬质合金刀具铣削钛合金时的刀具扩散磨损的作用机理进行了研究。通过对刀刃剖面的元素浓度的分布进行电子探针的波谱分析和俄歇能谱分析,发现在钛合金高速铣削时刀具的扩散磨损是由于刀具材料中的粘结相钴和硬质相中的碳元素作用的结果。并发现了硬质相中的碳元素扩散的新规律,碳元素的扩散在刀具和工件的界面处形成富碳层,而不是通常所认为的缺碳层,而在刀具的次表面才形成脱碳层。这样更加完善地解释了刀具表面层弱化以及其次表面层的脆化的联合作用而形成刀具的扩散磨损的作用机理。同时也对刀具材料中的钨元素以及工件材料中的钛元素的扩散进行了探讨。     

发动机汽门座环和汽门导管衬套孔切削工具的研究

介绍了该厂九十年代引进的SOFIM发动机生产线上,尤其是汽门座环和汽门导管衬套孔加工自动线上用的两种孔加工刀具的切削性能和结构特点。     

提高拉伸条件下的钛合金高温抗氧化性

钛合金高温成形时氧化问题严重影响产品的质量,采用有效的表面涂层防护是解决这一问题的重要途径,而目前的多种防护涂层都存在一些问题。因此选择锆英石粉末在TC4钛合金(Ti6Al4V)表面进行等离子喷涂,并对TC4合金在高温条件下氧化过程以及涂层对材料超塑性能的影响进行研究。在800℃、850℃及900℃温度条件下,对有氧化锆涂层和无涂层的试样以0．000 1 s-1,0．001 s-1,0．01 s-1和0．1s-1的应变速率进行拉伸试验。高温氧化时,无涂层的试样表面被氧化生成了氧化膜,XRD及EDS分析表明,氧化膜主要由TiO2组成,氧化温度和时间决定了膜的厚度。在有涂层保护的试样上,未发现该种氧化膜。在所有温度及应变速率下,有涂层试样的断面收缩率均比无涂层试样的断面收缩率有较大提高,且两种试样断面收缩率差距大小随试验温度和应变速率变化而变化,而抗拉强度和屈服强度并没有太大改变。但是,涂层本身由于塑性差,氧化锆涂层在拉伸过程后期涂层表面也会产生裂纹。     

STABILITY PREDICTION OF TITANIUM MILLING WITH DATA DRIVEN RECONSTRUCTION OF PHASE-SPACE

Significant research effort has been carried out in the detection of chatter, which is one of the main barriers against titanium milling. State-of-the-art techniques are unable to satisfy requirements of industry in terms of in-process chatter detection. The present study reports the use of sensor-signal driven reconstructed phase space attractors combined with image correlation as a solution of chatter prediction during milling of titanium in industry. The method uses Poincaré sections of reconstructed phase space attractor as patterns to identify the onset of chatter in the apparently random behavior of vibrations in the milling process. Image correlation of Poincaré sections indicates the onset of chatter in the milling process.     

小孔法测量残余应力时孔边塑性应变的有限元分析及修正

小孔法测量高残余应力时,小孔周围材料接近于屈服状态,由于产生塑性变形而引入塑性附加应变,使得测量结果产生很大的误差。研究了应变释放系数与主应力之间的双轴比、主应力方向与应变花方向夹角以及应力水平之间的关系,通过有限元数值试验的方法对应变释放系数进行标定,使其包含有塑性附加应变的影响,并利用标定后的应变释放系数对焊接残余应力测量结果进行了修正,得到了较好的结果。     

钛合金振动攻丝降低攻丝扭矩的研究

应用弹塑性理论分析了振动医疗丝降低已加工表面弹性回复的机理,从根本上解释了振动攻丝降低攻丝扭矩的原因,也为合理选用钛合金振动攻丝的工艺参数提供了理论依据。     

钛合金的深孔钻削技术研究

钛合金的切削加工性能差,其深孔钻削的技术难度更大。枪钻是深孔钻削的高效刀具,能有效解决钛合金的深孔加工问题。本文基于对钛合金材料切削性能和深孔钻削工艺的分析,通过深孔钻削试验,改进了钛合金叶片深孔钻削工艺,提高了枪钻寿命。     

STUDY ON NEAR DRY CUTTING OF ALUMINUM ALLOYS

Series of orthogonal cutting tests of aluminum alloys with different amount of silicon content have been carried out to investigate the chip formation process and adhesion of the work material to the rake face of the cutting tool under near dry cutting conditions. No adhesion is observed when cut with the sintered diamond tool regardless of the amount of the silicon content. On the other hand, the amount of adhesion increases with an increase in the silicon content in the aluminum alloys when cut with the cemented carbide and DLC-coated tools. No adhesion is formed when the nominal coefficient of friction on the rake face is 0.3 or less, and adhesion is formed when the nominal coefficient of friction is 0.4 or more. The amount of adhesion decreases with an increase in the rake angle when cut with the cemented carbide tools and the DLC-coated tool.     

STUDY ON NEAR DRY CUTTING OF ALUMINUM ALLOYS

Series of orthogonal cutting tests of aluminum alloys with different amount of silicon content have been carried out to investigate the chip formation process and adhesion of the work material to the rake face of the cutting tool under near dry cutting conditions. No adhesion is observed when cut with the sintered diamond tool regardless of the amount of the silicon content. On the other hand, the amount of adhesion increases with an increase in the silicon content in the aluminum alloys when cut with the cemented carbide and DLC-coated tools. No adhesion is formed when the nominal coefficient of friction on the rake face is 0.3 or less, and adhesion is formed when the nominal coefficient of friction is 0.4 or more. The amount of adhesion decreases with an increase in the rake angle when cut with the cemented carbide tools and the DLC-coated tool.     

EFFECTS OF COOLANT SUPPLY METHODS AND CUTTING CONDITIONS ON TOOL LIFE IN END MILLING TITANIUM ALLOY

Titanium machining poses a great challenge to cutting tools due to its severe negative influence on tool life primarily due to high temperature generated and strong adhesion in the cutting area. Thus, various coolant supply methods are widely used to improve the machining process. On account of this, tool life and cutting force are investigated based on dry cutting, flood cooling, and minimum quantity lubrication (MQL) techniques. The experimental results show that MQL machining can remarkably and reliably improve tool life, and reduce cutting force due to the better lubrication and cooling effect.     

铝锂合金热变形穿晶韧性断裂原因分析

采用Gleeble-1500热／力模拟试验机，对铸态1420铝锂合金在变形温度为350℃-450℃、应变速率为0．01s^-1-10.0s^-1的条件下，进行高温拉伸热模拟实验研究。利用扫描电镜，能谱分析、X射线衍射以及金相实验等手段对该合金的热变形穿晶韧性断裂进行分析。结果表明，Al3Fe相的存在是引起1420铝锂合金热变形穿晶韧性断裂的根本原因。     

EFFECTS OF COOLANT SUPPLY METHODS AND CUTTING CONDITIONS ON TOOL LIFE IN END MILLING TITANIUM ALLOY

Titanium machining poses a great challenge to cutting tools due to its severe negative influence on tool life primarily due to high temperature generated and strong adhesion in the cutting area. Thus, various coolant supply methods are widely used to improve the machining process. On account of this, tool life and cutting force are investigated based on dry cutting, flood cooling, and minimum quantity lubrication (MQL) techniques. The experimental results show that MQL machining can remarkably and reliably improve tool life, and reduce cutting force due to the better lubrication and cooling effect.     

紧固孔原始疲劳质量控制与制孔技术研究

对飞机结构耐久性和安全性有重要影响的紧固孔原始疲劳质量进行了分析,建立了制孔技术与紧固孔原始疲劳质量的内在联系。提出用满足９５％要求的当量初始裂纹尺寸ａｉ值来定量描述紧固孔原始疲劳质量。给出通过紧固孔原始疲劳质量评定和符合性检查来选择或验证制孔技术的方法。     

微细深孔超声轴向振动钻削装置的设计

基于高频振动切削原理 ,设计了一种振频 2 0± 1KHz、振幅 2 5 μm的新型超声轴向振动钻削装置 ,该装置由数字锁相环频率自动跟踪式晶体管型超声波发生器、轴向半波长圆柱型压电陶瓷换能器、半波谐振圆锥型变幅杆以及工具系统组成 ,可在软质材料上实现微细深孔的精密、超精密加工     

利用非晶态合金进行平面应力磁测法的研究

基于铁磁材料压磁效应的应力测量是一种新技术。目前对该技术的研究重点是如何提高它的测试准确性和灵敏度。非晶态合金材料具有良好的磁特性,可以用于应力测量。文中对这种应变计的工作原理及其磁输出特性进行理论分析,并利用铁基非晶态合金薄带进行实测试验。试验结果显示,该方法具有测试灵敏度高、测试系统简单等特点,是一种很有发展前景的应力测试方法。     

THE IMPACT OF HOLE MAKING PROCESSES ON THE FATIGUE LIFE VARIANCE OF THE MACHINED COMPONENTS

It is well known that a large variance can be associated with the fatigue life of nominally identical components. It may be intuitively true for some experts in surface integrity that different processes may produce different variances of fatigue life. However, little is known in the literature about the potential level of impact of different manufacturing processes on the variation of fatigue life, thus this study. Holes have been made on Ti 6Al-4V samples and finished by drilling and internal grinding using handbook recommended conditions. Tension fatigue tests of constant amplitude under load control have been conducted subsequently. Statistical analysis of the results showed a very significant impact of the hole making processes on the variance of the fatigue life. This finding proves the importance and urgency for further studying the issue in a scientific way.     

THE IMPACT OF HOLE MAKING PROCESSES ON THE FATIGUE LIFE VARIANCE OF THE MACHINED COMPONENTS

ABSTRACT

It is well known that a large variance can be associated with the fatigue life of nominally identical components. It may be intuitively true for some experts in surface integrity that different processes may produce different variances of fatigue life. However, little is known in the literature about the potential level of impact of different manufacturing processes on the variation of fatigue life, thus this study. Holes have been made on Ti 6Al-4V samples and finished by drilling and internal grinding using handbook recommended conditions. Tension fatigue tests of constant amplitude under load control have been conducted subsequently. Statistical analysis of the results showed a very significant impact of the hole making processes on the variance of the fatigue life. This finding proves the importance and urgency for further studying the issue in a scientific way.     

锉配件的钻孔工艺安排与钻孔方法

针对在锉配件上钻削孔距精度要求较高的孔的难点,介绍根据所钻孔在锉配件上所具有的不同特征,安排合理的钻孔工艺和选择合适钻孔的方法,其目的是保证钻孔的孔距精度要求。     

MODELLING OF HOLE TAPER AND HEAT AFFECTED ZONE DUE TO LASER BEAM PERCUSSION DRILLING

Determination of hole taper and extent of heat affected zone is a challenging task for manufacturing engineers from the quality and accuracy point of view of the laser-drilled hole especially in reflecting materials like aluminum. In this article, an axisymmetric finite element method-based thermal model has been developed for the determination of the transient temperature distribution in the aluminum sheet, which is further used for determination of hole profile, hole taper and extent of heat-affected zone during laser beam percussion drilling. Simulation results showing the effect of pulse width, pulse frequency, and peak power on hole taper and extent of heat affected zone incorporating the temperature dependent thermal properties and phase change have been presented. The developed model is also capable of predicting the hole profile through the isotherm generated along the depth of hole due to repeated laser pulses. The predicted values of hole taper are compared with the experimental results. It is found that the effect of pulse width on hole taper is more prominent than the peak power and extent of heat affected zone increases with the increase of pulse width, pulse frequency but it decreases with the increase of peak power.     

钛合金螺旋铣孔与传统钻孔的加工质量对比

对钛合金进行了螺旋铣孔与传统钻孔试验,研究了两种孔的加工质量及影响因素。结果表明:钛合金螺旋铣孔的质量相对较高,表面粗糙度相对较小;对于螺旋铣孔工艺,轴向每转进给量是影响孔表面粗糙度的主要因素,切向每齿进给量是影响孔圆度的主要因素,螺旋铣孔参数对孔径的影响不大;对于传统钻孔工艺,轴向每转进给量是影响孔表面粗糙度、圆度和孔径的主要因素。