可转位浅孔钻的径向力分析及试验研究

为了分析可转位浅孔钻钻孔的径向力,将可转位浅孔钻的切削刃离散为一系列无限小的单刃斜角切削单元。借用单刃斜角切削模型,并根据斜角切削和钻削之间的力变换关系对可转位浅孔钻钻孔的切削力进行分析。通过分析可转位浅孔钻切削刃上各点的几何角度,确定相应斜角切削单元的几何角度。最后对Al7050-T7451进行多组不同切削参数的钻削实验,数值计算和实验结果的比较验证了所提出数学模型的有效性。     

基于FEM的可转位浅孔钻几何参数的优化

建立了刀体与刀片的坐标系，定义出可转位浅孔钻的五个主要安装角度，并对其进行优化，得到径向合力近似为零的结果。为浅孔钻的结构设计和进一步研究钻削力、钻削温度等提供了依据。     

可转位浅孔钻的实体建模及网格划分

可转位浅孔钻内外刀片的径向非对称分布,导致钻削时将会产生径向合力,从而影响被加工孔的质量。为最大限度的减小加工时的径向合力,有效研究浅孔钻钻削过程,需借助有限元软件对其进行三维斜角切削分析。由于浅孔钻结构复杂,为创建有限元分析所需要的几何模型,采用Solid-Works软件建立可转位浅孔钻三维模型,并详细介绍了其建模过程;同时在有限元分析软件ANSYS里对其进行网格划分,为后续浅孔钻的应力、应变等分析做好充分准备工作。     

可转位浅孔钻的径向力平衡

可转位浅孔钻的径向力平衡成都成量集团公司（６１００５１）曹昌明在标准ＧＢ／Ｔ１４２９９－９３和ＧＢ／Ｔ１４３００－９３中,可转位螺旋沟和直沟浅孔钻的规定直径为ｄ＝２１～５６ｍｍ,通常采用两个ＷＣＭＸ的刀片分布于钻轴的两侧,分为外刀片和内刀片。刃尖...     

可转位浅孔钻参数优化的数值解法

采用斜角切削理论和试验相结合的方法建立可转位浅孔钻钻削力数值仿真的数学模型。该模型用于研究刀片在刀体上的空间位置参数对钻削力和扭矩的影响,并在给定已知条件下求出经过优化的径向合力为最小的刀片位置参数。     

可转位浅孔钻受力分析及试验研究

对可转位浅孔钻进行受力分析,推导内刀片偏置角β计算公式。通过可转位浅孔钻切削试验,分析其切削力和被加工件尺寸随角β的变化趋势,对内刀片偏置角β进行验证。     

硬质合金可转位浅孔钻

在机械加工中,钻孔约占26～30％。由于钻孔主要使用高速钢麻花钻,切削速度只有20～30m/min,因此实际上钻削占全部切削工时的40％。据统计,钻φ20～60mm的浅孔(孔深≤3D)占钻孔总数的27％左右,也就是占整个切削加工工时的8～10％。一、国外硬质合金可转位浅孔钻概况 70年代中期,国外开始发展硬质合金可转位浅孔钻。1975年首次出现在国际市场上,立即引起广泛重视,被认为是继60年代喷吸钻之后的又一重大突破,     

92—0237螺纹加工的新动向

目前,“钻攻”已成为螺纹加工领域中一项最热门的新工艺。这种方法是将浅孔钻削及螺纹铣削合二为一——应用单轴扦及一把组合刀具直接高速加工螺纹孔。加工时,一把尖端有钻削刃而刀体带有螺纹铣削刃的组合刀具连续不停的高速旋转,刀具先在工件上钻削出规定深度的孔并退出一个螺距的距     

浅孔钻硬质合金刀片槽型及涂层对切削性能的影响研究

选择三款不同槽型及涂层结构的可转位硬质合金涂层刀片对碳钢C45进行钻削实验,通过对实验的切削力、切屑变形及刀具磨损测试分析,研究浅孔钻硬质合金刀片槽型及涂层对切削性能的影响。结果表明:T1刀片具有更好的综合切削性能,W1、W2刀片前刀面更易发生粘结磨损;W1、W2刀片槽型反屑角θ较大,具有更好的排屑效果;从后三种刀片的刀面磨损情况来看,AlCrN+TiSiN复合结构涂层具有最长的钻削寿命,TiAlN涂层钻削寿命最短。     

BTA深孔钻的合理使用

ＢＴＡ深孔钻是内排屑深孔钻的一种典型结构 ,它是在单刃内排屑深孔钻的基础上改进而成 ,其切削刃呈双面错齿状 ,切屑从双面切下 ,并经双面排屑孔进入钻杆排出孔外。ＢＴＡ深孔钻切削力分布均匀 ,分屑、断屑性能好 ,钻削平稳可靠 ,钻削出的深孔直线性好。　　1　ＢＴＡ深孔钻的结构特点ＢＴＡ深孔钻具有以下结构特点 :(1)刀体上分布有外刃刀片、中刃刀片、内刃刀片、导向块和双面排屑孔 ,并通过刀体上的浅牙多头矩形螺纹与空心钻杆联接。(2 )钻芯部分由内刀刃代替了麻花钻的横刃 ,从而克服了麻花钻横刃较长、轴向阻力较大的缺点 ;由于钻芯相…     

基于FEM的可转位浅孔钻钻削应力分析

以安装两片硬质合金刀片的可转位浅孔钻为例,对浅孔钻的刀片所受应力进行了研究。根据内外两个刀片的切削刃在加工中的实际状态,分别对其建立有限元模型,利用Matlab对刀片在优化后稳态加工时有效切削刃的载荷分布进行了多项式拟合,并进行了应力分析;在不同切削用量时对刀片的应力变化情况进行了数值仿真。为浅孔钻结构(主要是刀片槽形)设计、使用的刀片的几何参数的确定,以及加工中切削用量的选用等提供了理论模型和可供参考的结构参数,而且所建立的模型和所采用的研究方法为其它类型的可转位刀具切削力的计算与数值仿真提供了可供借鉴的途径。     

Drill point geometry of multi-flute drills

This paper presents a comprehensive mathematical model for analysis of the geometries of conical, hyperboloidal, and ellipsoidal drills. The proposed method includes three particular features. The first is that a rotational disk-type abrasive wheel is modeled by revolution geometry, thus allowing for the normal and tangent vectors of an abrasive wheel to be obtained explicitly. Consequently, the tangent and normal vectors along the cutting edges and chisel edges of the produced drill can be obtained. The second feature is the ability of the model to determine and express drill geometries and characteristics (semi-point angle, tool cutting edge inclination, chisel angle, normal rake angle and normal clearance angle) according to all current international standards. Thirdly, the drill’s working geometries are investigated by taking the effect of feed motion into consideration. We found that cutting edge geometry can be studied without significant error even though we neglect the effect of feed. The chisel edge working geometry shows greater variation than tool geometry. Consequently, the effect of feed must be taken into consideration when studying chisel edge action during drilling operation.     

Drill point geometry of multi-flute drills

This paper presents a comprehensive mathematical model for analysis of the geometries of conical, hyperboloidal, and ellipsoidal drills. The proposed method includes three particular features. The first is that a rotational disk-type abrasive wheel is modeled by revolution geometry, thus allowing for the normal and tangent vectors of an abrasive wheel to be obtained explicitly. Consequently, the tangent and normal vectors along the cutting edges and chisel edges of the produced drill can be obtained. The second feature is the ability of the model to determine and express drill geometries and characteristics (semi-point angle, tool cutting edge inclination, chisel angle, normal rake angle and normal clearance angle) according to all current international standards. Thirdly, the drill’s working geometries are investigated by taking the effect of feed motion into consideration. We found that cutting edge geometry can be studied without significant error even though we neglect the effect of feed. The chisel edge working geometry shows greater variation than tool geometry. Consequently, the effect of feed must be taken into consideration when studying chisel edge action during drilling operation.     

Modeling and experimental verification of chip flow deviation in oblique cutting

The reasons for chip deviation from the orthogonal direction in machining are (i) restricted cutting effect, (ii) nonzero inclination angle, and (iii) tool-nose radius. The present article has incorporated the concept of effective inclination angle in the models for predicting chip flow direction in oblique cutting. Model 1 takes into account the role of the effective principal cutting edge angle (as point function) and the concept of effective inclination angle has been incorporated in the model. Model 2 addresses the same roles but determined as path functions. Models 1 and 2 do not address the variation in the chip load along the width of cut. This has been addressed in Model 3 along with effective inclination angle. The models have been validated against the experimental data while turning two different medium carbon steels with uncoated carbide inserts over a wide domain of depth of cut, feed, cutting velocity, nose radius, rake angle, inclination angle and principal cutting edge angle. The major contribution of this work is the introduction of effective inclination angle along the effective cutting edge.     

Edge micro-creation of Ti(C,N) cermet inserts by micro-abrasive blasting process and its tool performance

Abstract

In this study, the cutting edge passivation by a micro-abrasive blasting method for cermet inserts and its machining performance were investigated. The micro-abrasive blasting parameters for cermet inserts were optimized and the micro-creation of cutting edge was determined with detail. A Back Propagation (BP) neural network prediction model was further established based on our micro-abrasive blasting experiment datum, which can directly evaluate the micro-abrasive blasting ability to generate the specific edge radius. The improvement of cutting performance of micro-abrasive blasted cermet inserts benefits from the strengthening of cutting edge that caused by the obvious elimination of a large number of micro-defects rooted around the edge, and the formation of circular cutting edge is the result of brittle removal and plastic removal. The micro-creation of inserts can acquire a circular cutting edge, and the optimal edge radius is 15?μm under the selected cutting conditions when the tool life was chosen as an optimization target and the surface roughness was simultaneously taken into account. It is found that the blasted cermet inserts can prolong the tool life by at least 86% and the machined-surface quality can be improved by up to 1.65?μm, compared to inserts without micro-abrasive blasting.     

可转位浅孔钻“非稳态”加工时的力学建模

以刀体上装有两个等边不等角六边形硬质合金可转位刀片的浅孔钻为例,用向量矩阵法分析了可转位浅孔钻的几何参数。根据浅孔钻加工特性划分了各个加工阶段,在建立各阶段数学模型的基础上,采用经典斜角切削理论和经验公式相结合的方法进一步分别建立了浅孔钻“钻入”五个阶段和“钻出”三个阶段的力学模型。为进一步研究浅孔钻所受切削力、切削热以及浅孔钻结构的改进、使用等打下了必要的基础。     

Effect of tool edge wear on the cutting forces and vibrations in high-speed finish machining of Inconel 718: an experimental study and wavelet transform analysis

High-speed machining has been receiving growing attention and wide applications in modern manufacture. Extensive research has been conducted in the past on tool flank wear and crater wear in high-speed machining (such as milling, turning, and drilling). However, little study was performed on the tool edge wear??the wear of a tool cutting edge before it is fully worn away??that can result in early tool failure and deteriorated machined surface quality. The present study aims to fill this important research gap by investigating the effect of tool edge wear on the cutting forces and vibrations in 3D high-speed finish turning of nickel-based superalloy Inconel 718. A carefully designed set of turning experiments were performed with tool inserts that have different tool edge radii ranging from 2 to 62???m. The experimental results reveal that the tool edge profile dynamically changes across each point on the tool cutting edge in 3D high-speed turning. Tool edge wear increases as the tool edge radius increases. As tool edge wear dynamically develops during the cutting process, all the three components of the cutting forces (i.e., the cutting force, the feed force, and the passive force) increase. The cutting vibrations that accompany with dynamic tool edge wear were analyzed using both the traditional fast Fourier transform (FFT) technique and the modern discrete wavelet transform technique. The results show that, compared to the FFT, the discrete wavelet transform is more effective and advantageous in revealing the variation of the cutting vibrations across a wide range of frequency bands. The discrete wavelet transform also reveals that the vibration amplitude increases as the tool edge wear increases. The average energy of wavelet coefficients calculated from the cutting vibration signals can be employed to evaluate tool edge wear in turning with tool inserts that have different tool edge radii.     

The role of tool composition and tool geometry in controlling the surface finish in machining wood

An examination of several brazed cemented carbide tool inserts that were used in service for cutting cured (dry) pine is described. A laboratory test is also described where the relative resistance to chipping of the brazed tool inserts was measured.It is shown that tool wear occurs through a continuous increase in the tool cutting edge radius that produces a deterioration in the appearance of the machined surface. It is also shown that an increase in either the binder volume fraction or the tool wedge angle produces an increase in the energy absorbed on impact. It is suggested that if progressive wear determines the useful life of a cemented carbide cutting tool then a low volume fraction of binder is required whereas if tool edge chipping determines the useful life of a cutting tool then a large volume fraction of binder and a large tool wedge angle are required.     

复合钻削刀具负载的建模与验证研究

针对复合钻削刀具钻孔过程负载计算误差较大,负载动特性预测精度较低的问题,对复合钻削的切削负载动态过程进行了研究。基于斜角切削理论,针对主切削刃负载和倒角刃单元负载受力分析,分别建立了主切削刃和倒角刃的等效切削模型。由于复合钻削过程的复杂性,采用数学分析和经验值相结合的方法,提出了钻削过程动态负载模型。同时考虑钻削过程中主轴径向跳动对切削性能的影响,进一步优化了复合钻削负载模型。通过对复合刀具不同刃不同切削工况的负载叠加融合,提出了复合钻削动态负载模型,并进行了仿真和实验。结果表明,考虑主轴径向跳动所建立模型相较于未考虑主轴径向跳动模型更能够准确地描述复合钻削刀具的动态负载特性,其负载误差比未考虑主轴跳动的情况减小了10%。