两工位偏心镗孔实现断屑

断屑一直是人们研究的课题。断屑的基本方法,一是在切削过程中增加切屑的变形,习惯采用在前刀面设断屑台及改变刀具几何形状和调整切削用量;另一是采用间断切削如振动断屑、间隙进给等。我厂连杆生产,小头工艺扎的镗削(45锰钢,调质处理,孔径与孔长比为1:1.2,D_4)采用两工位偏心镗孔,较好地解决了断屑问题,对刀具刃磨无特殊要求,成本也较低。     

深孔加工振动断屑装置设计

针对深孔加工过程中切屑形态不稳定所形成的排屑不畅问题,基于振动钻削理论,设计振动断屑装置,有效控制切削形态,保证顺利排屑。通过给刀具施加轴向周期振动,振动断屑装置可实现变切厚钻削和钻头轴向振动,使切屑易断,并在一定程度上提高了表面加工质量。通过实验探究了切屑形态与切削参数的关系,分析了振动断屑装置的最佳工作参数。     

车削加工中的两种断屑装置

车削加工中,断屑一直是人们研究的课题。断屑的基本方法:一是在切削过程中增加切屑的变形;一是采用间断切削。下面介绍的两种断屑装置,就是周期性改变切屑的厚度,达到断屑的目的。     

断屑槽槽型在控屑过程中对刀具振动的影响

通过ABAQUS有限元软件分别对梯形、直线圆弧型和梯形双槽结构断屑槽刀具切削Ti6Al4V钛合金材料进行三维切削仿真,并分析其切削力的波动,得到断屑槽槽型在控制切屑卷曲过程中对刀具在主运动方向、进给方向和切削深度方向振动的影响。经过仿真发现,梯形、直线圆弧型和梯形双槽结构断屑槽在控制切屑卷曲的过程中对刀具振动的影响各不相同。三种槽型结构中,梯形断屑槽刀具的振动最弱,直线圆弧型断屑槽刀具的振动最强。     

振动切削深孔加工技术(下)——振动参数对切屑形状及表面质量的影响

一、振动断屑及其控制用枪钻振动钻孔的工作原理如图1所示。图 1 在所加轴向振动的影响下,切削过程中任意瞬间的实际切削参数都是周期性变化的,并随着振动频率f、振幅A_0、主轴转速n和进给量S_0的不同组合而变化,从而得到间断的或连续的切削过程。若所加的振动是按正弦规律变化的,即:     

轴向振动钻削的断屑机理研究

在对钻削加工的断屑方式简要分析的基础上,基于轴向振动钻削的变厚切削特性,分析了轴向振动钻削实现可靠断屑的内在实质,并进行了相应的试验验证.研究结果表明:与普通钻削相比,轴向振动钻削轴向瞬时切削厚度周期变化,具有变厚切削特性;通过合理选择工艺参数,可以使振动钻削过程实现几何断屑,从而保证了切屑的顺利折断.     

孔加工振动切削的断屑机理

分析孔加工中常用的麻花钻、扩孔钻、深孔单刃钻等振动切削的断屑机理,得出各种钻头振动切削的最佳条件,包括振动发生器的最小振幅、振动频率和工件转速断屑的最佳比值及各种情况的断屑层图。     

两种新型断屑装置

在车加工时有两种主要断屑方法：在切削刀片上制作断屑槽和附加断屑器。第一种方法有许多缺点，因为断屑槽将降低切削刀片的强度，在切削时引起刀片振动，从而加速车刀的磨损，显著降低加工质量。此外，若切削用量和断屑槽的形状选择不当，则在刀片上会出现积屑瘤，从而降低耐磨涂层刀片的切削效果，急剧降低断屑的稳定性。下面介绍两种新型断屑装置，可有效断屑和提高加工质量。带回转断屑器的车刀图１所示为带回转断屑器的车刀。在刀夹１内的销钉２上装有切削刀片４和支承刀片３，以及可在销钉上回转的断屑器５，见图１（a）。断屑器是一…     

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。     

BTA深孔钻断屑研究

通过对BTA深孔钻头排屑通道的研究,提出了理想切屑的形态以及断屑的主要措施。尤其对振动钻削断屑进行了深入的理论分析,通过试验,探讨了切屑形态变化与切削参数之间的关系,总结出断屑的最佳切削条件。     

机械式低频振动攻丝切削力实验研究

本文根据振动攻丝基本原理,研制出具有振动攻丝功能的振动攻丝卡头,并利用该卡头对振动攻丝切削力变化特点进行了大量的实验研究。结果表明采用振动攻丝切削力呈现出理想的波形化效果,切削力峰值略低于普通攻丝,切削力平均值为普通攻丝的１／５～１／２。     

绿色冷却切削技术在滚切齿轮中的试验研究

文中概述了几种主要的冷却方法，通过滚切齿轮试验，比较和分析了几种冷却方法下切削温度、刀具磨损、切屑形态，来揭示亚干式冷却和冷风射流冷却这两种绿色冷却技术的优越性。     

Thermomechanical approach for the modeling of oblique machining with a single cutting edge

This article aims to predict performances of oblique machining with a single cutting edge. A thermomechanical approach for the modeling of oblique cutting with a single cutting edge is proposed. A good agreement was found between predicted and experimental data. New rules were established to determine experimentally the average friction coefficient and chip flow angle at the rake face. The computation algorithm permits to predict all thermomechanical parameters such as cutting forces, cutting temperatures, and chip geometry. Besides, all predicted oblique machining parameters are mainly controlled by the Po-criterion, which is defined as the ratio of tool–chip contact length to uncut chip thickness.     

自由切削法与自由切削刀具

在深入研究非自由切削的实质和规律性的基础上，揭示实现自由切削的条件，提出自由切削法，其要点是合理刀具的前刀面，以疏导刀刃各部件的排屑，消除排屑干涉，实现自由切削。给出了两种自由切削刀具的原理及其设计方法，分析并实验验证了其优越性。     

金属切削中流屑角突变的实验研究

对金属切削中的一类非线性问题－切屑流屑角的突变进行了检测实验研究,得出了流屑角突变时刻的力,振动和声发射信号。多次实验表明,这3种信号中对切削过程的非线性特征以切削力信号最为灵敏。根据传感器突变信号的产生时间,可以计算出突变时的切削层厚度aW和切削层图形系数gs。     

精密切削过程三维有限元分析

采用有限元方法模拟三维精密切削过程,包括三维正交切削和三维斜角切削。切屑和刀具的摩擦应力采用修正库仑摩擦方程来计算,工件的流动应力是应力、应变、应变率和温度的函数,采用局部网格重划分技术。通过三维切削模拟可以获得在不同刃倾角精密切削过程的条件下切屑形状、切削力和切削温度场的分布情况。仿真结果表明:刃倾角对主切削力和切深抗力影响不大,但对切屑形状、进给抗力和切削温度场分布影响较大。     

An experimental investigation of oblique cutting mechanics

In this study, an experimental investigation of oblique cutting process is presented for titanium alloy Ti-6Al-4V, AISI 4340, and Al 7075. Important process parameters such as shear angle, friction angle, shear stress, and chip flow angle are analyzed. Transformation of the data from the orthogonal cutting test results to oblique cutting process is applied, and the results are compared with actual oblique cutting tests. Effects of hone radius on cutting forces and flank contact length are also investigated. It is observed that the shear angle, friction angle, and shear stress in oblique cutting have the same trend with the ones obtained from the orthogonal cutting tests. The transformed oblique force coefficients from orthogonal tests have about 10% discrepancy in the feed and tangential directions. For the chip flow angle, the predictions based on kinematic and force balance results yield better results than Stabler's chip flow law. Finally, it is shown that the method of oblique transformation applied on the orthogonal cutting data yields more accurate results using the predicted chip flow angles compared to the ones obtained by the Stabler's rule.     

HIGH SPEED MILLING OF GRAPHITE ELECTRODE WITH ENDMILL OF SMALL DIAMETER

Graphite becomes the prevailing electrode material in electrical discharging machining (EDM)currently.Orthogonal cutting experiments are carried out to study the characteristics of graph- ite chip formation process.High speed milling experiments are conducted to study tool wear and cutting forces.The results show that depth of cut has great influence on graphite chip formation.The removal process of graphite in high speed milling is the mutual result of cutting and grinding process. Graphite is prone to cause severe abrasion wear to coated carbide endmills due to its high abrasive- ness nature.The major patterns of tool wear are flank wear,rake wear,micro-chipping and breakage. Cutting forces can be reduced by adoption of higher cutting speed,moderate feed per tooth,smaller radial and axial depths of cut,and up cutting.     

Modeling and experimental verification of cutting forces in gear tooth cutting

Due to complex cutting edge profile of an involute cutter, calculations of chip width and consequently cutting force are quite problematical. This article presents a mechanistic approach in the prediction of cutting force components arising in the course of gear tooth cutting by an involute form cutter. To permit calculation of chip width (and so cutting forces), a discrete model is utilized and cutting force components are then derived using Kienzle approach. Moreover, several experiments are performed under different cutting conditions to prove the effectiveness and accuracy of the used method. The results have revealed that cutting force components can be predicted in form gear tooth cutting with a significant accuracy.     

基于独立分量分析的切削声发射源信号分离

针对切削声发射(Acoustic Emission,AE)信号的多目标状态源并行分离问题和同频干扰源分离问题,引入独立分量分析(Independent Component Analysis,ICA)技术作为研究工具,用刀具破损、切屑折断和环境噪声三个AE源的线性混合模拟切削AE信号,尝试用FastICA算法分离目标状态...