铝合金加工用变导程钻头的优化

研究发现,变导程钻头能够有效改善铝合金材料在切削钻削中出现的粘刀、排屑难、易断刀等现象,但并没有找出适合加工铝合金材料的变导程钻头设计参数。改变变导程钻头的螺旋角参数及螺旋角渐变的位置,做进一步的对比试验,找出加工铝合金材料的变导程钻头参数选取的一般规律,为以后铝合金加工用变导程钻头的参数设计奠定基础。     

铝合金材料专用麻花钻的开槽刀

随着铝合金材料的广泛使用,加工铝合金麻花钻的需求量大增。但用普通麻花钻钻削铝合金材料时,钻削不顺畅,使用效率低。我们用普通钻头做了一次切削试验(切试工件为铝合金缸盖),发现在钻削过程中钻尖处粘屑很严重,钻削速度慢且振动较大,钻头寿命低。为此,我们设计了轻合金材     

抛物线钻头在深孔加工中的应用

东风汽车公司在加工深孔零件时过去大多采用普通麻花钻 ,在加工过程中时常发生加工质量不合格或钻头折断现象 ,造成零件报废 ,有时废品率可达3%以上。究其原因 ,主要是因为用普通麻花钻进行深孔钻削时存在以下不利因素 :①钻头细长 ,刚性差 ,加工时容易弯曲和振动 ,难以保证孔的直线度 ;②普通麻花钻的横刃为负前角 ,钻削时横刃处于挤刮状态 ,易引起钻头振动 ;③切屑长 ,且排屑通道长而窄 ,断屑、排屑困难 ;④切削液不易进入切削区 ,钻头易磨损 ;⑤钻头螺旋角和主切削刃前角较小 ,切削刃不锋利 ,排屑不畅。为提高深孔加工质量和加工效率 ,我…     

麻花钻后刀面螺旋面刃磨法的三维实体建模

介绍了后刀面为渐开螺旋面麻花钻常用的两种刃磨方法,根据麻花钻的钻刃曲线方程及普通螺旋面刃磨法原理、变导程螺旋面刃磨法原理,建立了普通螺旋面刃磨法的数学模型;提出了在UG环境下用普通螺旋面刃磨法和通过Lagrange插值法实现的变导程螺旋面刃磨法刃磨麻花钻后刀面的三维实体建模方法,解决了螺旋面刃磨法三维实体建模的难题;并且利用草图与表达式功能实现其参数化建模,为麻花钻进行几何设计、制造、切削性能分析和对钻削过程进行仿真研究奠定基础。     

加厚钻心麻花钻的应用

普通标准结构麻花钻往往不适合生产中使用,原因是寿命常常太短,必须频繁换刀。捷克一家汽车厂采用了加厚钻心的麻花钻,在生产条件下钻削汽车转向节上的孔。这种钻头在重切削条件下使用,获得了良好的效果。以前采用普通标准钻头加工上述工件,最多只钻80个孔,现采用新钻头,平削可钻削333个孔。     

基于Pro/E与ANSYS的麻花钻模态分析

麻花钻是孔加工中的重要工具之一,它本身的固有属性影响着孔加工的质量和加工效率。利用Pro/E三维造型软件建立麻花钻三维模型,基于切削和振动理论,利用ANSYS中的动力分析技术对钻头整体做模态分析,得出了麻花钻的前五阶固有频率。根据钻头的振型图中的最大位移量,通过分析研究,从理论上论证了钻头的固有频率对孔加工质量的影响,从而为钻头设计中改变材质和尺寸以及加工中选择合适钻头等提供了一定的理论依据,提高加工质量。     

麻花钻头双后角刃磨法

<正> 麻花钻后角是钻头重要的几何角度,也是刃磨钻头时最主要的切削参数。钻头后角数值和刃磨合理与否,直接影响被加工孔的生产效率、质量及钻头耐用度。标准麻花钻的主切削刃只有一个后面,也只有一个后角,且主     

变导程螺旋齿圆锥铰刀螺旋槽的铣削

螺旋齿圆锥铰刀是在机械制造工业中使用比较普遍的一种刀具。它主要用于加工圆锥孔,在切削加工时比较平稳,排屑性能较好,但制造工艺性差。螺旋齿圆锥铰刀一般都在万能卧式升降台铣床上用铣削一般螺旋槽的方法,按恒螺旋导程来加工的。实际上螺旋齿圆锥铰刀的直径是变化的,因此,当螺旋角β不变时,导程 T是变化的。恒导程的螺旋齿圆锥铰刀较变导程的螺旋齿圆锥铰刀的加工平稳性及排屑性能差,并且在制造过程中铣削螺旋槽时会随着直径的增大而出现负前角,给刃磨铰刀前刀面带来很大困难。下面介绍一种铣削变导程螺旋齿圆锥铰刀的方法…     

复合精孔钻

复合精孔钻,是一种专门加工精孔的钻头。尤其在加工非标准孔及无专用铰刀的情况下,能直接钻出精度和光洁度较高的孔。复合精孔钻,是在标准麻花钻和普通群钻的基础上,通过改变切削角度和几何参数修磨出来的。改变了标准麻花钻主切削刃太长、切屑难于排除、切屑宽度大、切削条件差、散热性不好、磨损快等缺点。克服了普通精扩孔钻因刃倾角为正值,而使切屑划伤已加工表面等现象。     

麻花钻刃磨切削部分要素的检测方法

麻花钻刃磨中应对其切削部分的主要角度等要素正确控制,否则在进行切削加工中易出现各种问题,影响加工质量,缩短钻头寿命,提高成本。下面笔者根据多年经验,对刃磨时麻花钻切削部分要素的控制方法逐一进行分析。     

Cutting performance of an indexable insert drill for difficult-to-cut materials under supplied oil mist

In this study, the cutting performance of an indexable insert drill with an asymmetric geometry for cutting difficult-to-cut materials was investigated. A solid twist drill with a symmetric geometry was used to compare the cutting characteristics. The cutting characteristics were evaluated using the thrust force, inner-surface roughness of the drilled hole, wear behavior, and tool temperature. Workpieces made of stainless steel, titanium alloy, and nickel-based alloy were selected as difficult-to-cut materials, and carbon steel was also selected. The tool temperature was higher in the order of carbon steel, stainless steel, titanium alloy, and nickel-based alloy for every drill under minimum quantity lubrication cutting. The influence of the workpiece material on the thrust force was different from that of the tool temperature for the indexable insert drill, whereas that of the solid twist drill was similar to the tool temperature tendency. When cutting the titanium alloy and nickel-based alloy, the tool temperature and thrust force of the indexable insert drill were lower than those of the solid-type twist drill. The inner-surface roughness of a hole drilled with the indexable insert drill had almost the same quality as that of a hole drilled with the solid-type twist drill when cutting the difficult-to-cut materials. The wear behavior of the indexable insert drill was remarkably different from that of the solid-type twist drill, and the flaking of the coating and the abrasion wear at the rake face were notable in the indexable insert drill.     

麻花钻后刀面建模方法的优化

在分析和研究麻花钻锥面刃磨法、变导程螺旋面刃磨法及螺旋锥面刃磨法的基础上,提出了横刃及圆柱螺旋线扫掠法,并构建了其数学模型。该方法预先设计横刃,以横刃及螺旋线复合扫掠的方法构建主后刀面。采用该方法得到了麻花钻直线主刀刃和理想的横刃及后角值分布;解决了采用变导程螺旋面刃磨法钻芯强度较弱以及采用锥面刃磨法存在的主后刀面"翘尾"现象;解决了两主后刀面磨削自然形成横刃形状的可控性。     

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...     

高温合金NiCr20TiAl钻削加工特性研究

高温合金是金属材料中最难加工的材料之一,使用M42高性能高速钢非涂层麻花钻,对变形高温合金材料NiCr20TiAl进行钻削加工.通过改变切削参数和冷却条件,对切削加工过程中刀具的寿命、切屑形态和刀具失效机理进行了试验研究.结果表明,高性能高速钢M42麻花钻主要的失效方式是后刀面磨粒磨损、粘结磨损、扩散磨损、沟槽磨损和崩...     

The effect of starting hole geometry on borehole quality and tool life of twist drills

This paper reports about the relationship between starting hole geometry and twist drill performance, which is determined by the location error and diameter of the drilled borehole as well as the tool life of the employed twist drills. The experimental results lead towards the conclusion that the type of starting hole has a significant effect on borehole quality. This, however, is not as commonly assumed attributed to a variation in the location error of the different starting holes themselves, but to how a starting hole allows the subsequent twist drill to engage in the cutting process. Although twist drills that drill straight into the workpiece material achieved the longest tool life due to a gentle engagement, a deep starting hole (‘pilot hole’) results in the most satisfying overall twist drill performance.     

枪钻与麻花钻加工质量的对比研究

利用台式钻床和深孔加工机床分别对常用Q235钢、45钢和铝材进行孔加工试验。通过对孔表面质量的观测和粗糙度的检测,对比研究上述两种加工方法的表面质量。结果表明:麻花钻加工材料越软孔口毛刺越明显,枪钻加工软硬材料的孔口部都呈平整无毛刺。一般条件下,枪钻加工铝合金有色金属材料的孔表面粗糙度值Ra为0.9μm左右,麻花钻为1.6μm左右;枪钻加工碳钢材料孔的表面粗糙度值Ra为1.8μm左右,麻花钻孔的表面粗糙度值Ra9.6-5.6μm;对于不同硬度的碳钢,麻花钻加工孔质量变化明显,一般硬度高的质量较好,枪钻则变化不显著;相比有色金属,麻花钻及枪钻加工孔的质量都优于碳钢。     

钛合金材料的钻孔技术分析

钛合金热稳定性好,高温力学变形系数小,具有良好的抗腐蚀性和粘接性能,主要应用于航空航天等领域中。但是钛合金导热系数低,单位面积上的切削力大,造成钛合金在钻削时,刀具磨损快,易导致钻头烧结、卡钻、钻斜、尺寸超差等。本文针对钛合金磨削钻削难加工问题,通过正确选择钻头角度、钻削用量、钻削冷却液等参数,保证钛合金零件钻削精度要求。     

The influence of end mill helix angle on high performance milling process

The results of experimental research on the influence of the helix angle on high performance milling of AlZn5.5MgCu alloy are presented. End mills with a wavy shape of a cutting edge, dedicated to rough high performance machining, were used. The helix angle was changed in the range of 20° to 50° with a step of 5°. During the milling tests, three cutting force components were measured. After each test cutting, chips were collected and analyzed. A recording of the chip evacuation process using a high-speed camera was also conducted. The influence of the helix angle on cutting force components was determined and the mathematical models of the forces were calculated. The significance of coefficients in the obtained equations was analyzed as well. The recorded images of the chip evacuation were analyzed. The displacement and the angle of the chip evacuation were determined. Based on the analysis of the selected images the impact of the helix angle on the direction and evacuation velocity of chips was determined. The size and shape of the obtained chips was also analyzed.

     

An explicit finite element model to study the influence of rake angle and friction during orthogonal metal cutting

A fundamental understanding of the tribology aspects of machining processes is essential for increasing the dimensional accuracy and surface integrity of finished products. To this end, the present investigation simulates an orthogonal metal cutting using an explicit finite element code, LS-DYNA. In the simulations, a rigid cutting tool of variable rake angle was moved at different velocities against an aluminum workpiece. A damage material model was utilized for the workpiece to capture the chip separation behavior and the simultaneous breakage of the chip into multiple fragments. The friction factor at the cutting tool–workpiece interface was varied through a contact model to predict cutting forces and dynamic chip formation. Overall, the results showed that the explicit finite element is a powerful tool for simulating metal cutting and discontinuous chip formation. The separation of the chip from the workpiece was accurately predicted. Numerical results found that rake angle and friction factor have a significantly influence on the discontinuous chip formation process, chip morphology, chip size, and cutting forces when compared to the cutting velocity during metal cutting. The model was validated against the experimental and numerical results obtained in the literature, and a good agreement with the current numerical results was found.