麻花钻的受力状态对钻削稳定性的影响

分析了钻削过程中麻花钻的受力情况,讨论了作用在麻花钻上的力和力矩、单元力和力矩以及动量矩对钻削稳定性的影响,提出了提高孔加工精度的措施。     

麻花钻钻削加工过程的有限元分析

对WC硬质合金麻花钻加工45#钢工件上孔的过程,用Deform软件进行了有限元分析。研究了加工过程中刀具的轴向力和扭矩随切削时间的变化规律,得到了工件最大主应力的分布区域。分析了麻花钻加工过程中的温度变化,得到了刀具和工件温度云图。研究结果为麻花钻实际加工切削用量的选择提供了参考。     

钻头几何参数对低频振动钻削CFRP/钛合金叠层材料钻削轴向力及温度的影响

通过开展低频振动钻削叠层材料单因素试验,研究了刀具的顶角、螺旋角和后角对钻削轴向力及温度的影响。结果表明:钻头顶角越大,轴向力越大,螺旋角的变化对钻削CFRP层轴向力影响较小;在钻削钛合金层时,轴向力随着螺旋角的增大呈先下降后上升的趋势,钻头后角越小,轴向力越大;钻头几何参数对钻削温度的影响可以忽略,得出较为适合CFRP/钛合金叠层材料振动制孔的钻头几何参数为顶角120°、螺旋角25°、后角20°。     

轴向超声振动钻削的钻削力和切屑形态研究

建立了钻削加工仿真模型,并采用麻花钻对钛合金进行振动钻削试验。利用ABAQUS软件进行轴向超声振动钻削仿真,试验验证和对比分析了轴向超声振动钻削在不同加工参数下的切屑形态和钻削力。仿真与试验结果表明:随着进给量和振幅增加,钻削力增大,但进给量对钻削力的影响大于振幅;无论是进给量还是振幅的改变,对切屑形态均有影响。     

扭转振动骨钻切削参数与钻削力的试验研究

在骨科矫形固定手术的骨钻孔过程中会产生大量切削热,一旦温度超过47℃可导致不可逆转的骨坏死,从而影响骨愈合。同时手术钻削效果对于提高手术质量,减轻病人出血至关重要。应用低频振动骨钻,测定了主轴转速、进给速度和激振频率对钻孔力学参数、钻孔温度以及表面加工和质量的影响关系。实验表明:随着激振频率的增加,轴向力、扭矩和温度都逐渐减小,引入低频振动,可以在较小切削力下高效地钻孔,从而有效降低钻孔温度,获得较好表面质量。     

不同钻尖角下不锈钢钻削性能研究

为了研究不同钻尖角下钻头的钻削性能,提高钻削质量,减少毛刺的发生,对不锈钢0Cr18Ni11Ti进行钻削实验。首先对不锈钢0Cr18Ni11Ti在不同钻尖角(120°,140°,160°)下的出口部位毛刺和切屑的形貌进行了对比,并且进一步探讨了3种钻尖角下钻头的轴向力和钻削转矩。研究结果表明:钻尖角的增大,能够有效地抑制孔加工出口部位的毛刺,切屑变得更加光滑,孔加工质量得到很大改善;钻尖角增大,钻削轴向力增大,钻削转矩减小,加工残余量变少;在切削速度为120m/min、进给量为0.15mm/r、钻尖角为160°时,钻削质量达到最佳状态。     

整硬麻花钻横刃轴向前角对TC4钛合金钻削性能的影响研究

TC4钛合金在钻削加工过程中存在切削力大、切削温度高、刀具磨损严重以及寿命短等问题,属于典型的难加工材料。采用三款不同横刃轴向前角的整体硬质合金麻花钻对TC4钛合金进行钻削实验,分析不同轴向前角对切削力、切屑形态、刀具磨损与寿命的影响。结果表明：正轴向前角的钻头切削更锋利,切削阻力小;正轴向前角钻头的寿命高于0°轴向前角和负轴向前角钻头。在TC4钛合金的钻削加工中,横刃轴向前角取正值可以提升刀具寿命。     

医疗钻头钻削力和钻削温度的试验研究

在高速钻削猪胫骨过程中,钻削力和钻削温度对改进医疗钻头的设计是非常重要的.研究结果表明:在钻削骨头的过程中,钻削力和钻削温度受进给速度和钻削速度的影响.相比不锈钢麻花钻,带三个切削刃的新型医疗钻头能够取得更小的钻削力和低于47℃的钻削温度.     

后刀面微织构内冷麻花钻钻削Ti6Al4V的性能研究

Ti6Al4V具有强度高、导热性低等特点,广泛应用于航空、航天等领域高端装备中。钻削制孔时,在热-力作用下,切削力和切削温度较高,产生严重的刀具磨损,导致加工效率低和加工质量差。本文采用激光技术在内冷麻花钻后刀面制备出平行于主切削刃(PT)、垂直于主切削刃(VT)、倾斜45°于主切削刃(LT)的三种沟槽型微织构,进行Ti6Al4V的钻削试验,对钻削力、切屑形态以及被加工孔表面粗糙度进行研究,并与无织构麻花内冷钻(NT)对比。结果表明:在内冷麻花钻后刀面加工微织构能有效减小钻削力,其中,相对于NT型麻花钻,PT和VT型麻花钻的钻削力降低23%～31%,而LT型麻花钻相对于NT型刀具钻削力降低46%;对于切屑形态,微织构麻花钻能降低切屑堆积性,增加其断屑性能,LT型麻花钻几乎没有缠屑;对于被加工孔的表面质量,微织构麻花钻可有效降低其R_a值,其中LT型麻花钻的粗糙度R_a值达到了1.28μm,比NT型麻花钻降低了约54.4%,综合效果最好。     

基于Deform3D不锈钢钻削机理的仿真研究

采用大型有限元分析软件Deform 3D对普通麻花钻钻削过程的机理进行了仿真研究.应用Deform-3D有限元软件,将工件、刀具材料的一些特性参数结合起来,分析和定义了载荷边界条件、刀具前刀面与切屑之间摩擦状况,选择了切屑分离准则,完成了有限元分析仿真的预处理工作.利用有限元仿真分析,建立麻花钻三维钻削有限元模型,介绍...     

Analysis and predictive modeling of performance parameters in electrochemical drilling process

In this paper, the effect of feed rate, voltage, and flow rate of electrolyte on some performance parameters such as surface roughness, material removal rate, and over-cut of SAE-XEV-F valve-steel during electrochemical drilling in NaCl and NaNo₃ electrolytic solutions have been studied using the main effect plot, the interaction plot and the ANOVA analysis. In continuation, in this case which the training dataset was small, an investigation has been done on the capability of the optimum presented regression analysis (RA), artificial neural network (ANN), and co-active neuro-fuzzy inference system (CANFIS) to predict the surface roughness, material removal rate and over-cut. The predicted parameters by the employed models have been compared with the experimental data. The comparison of results indicated that in electrochemical drilling using different electrolytic solutions, CANFIS gives the best results to predict the surface roughness and over-cut as well, while ANN is the best for predicting the material removal rate.     

Workpiece and electrode influence on micro-EDM drilling performance

In recent years, the need for products containing micro-features has shown a pronounced and steady growth in several fields of application. For the development of micro-holed devices, one of the most important technologies is micro-EDM (Electro Discharge Machining). Micro-EDM can be considered as an ideal process to obtain burr-free micron-size features with high aspect ratios. In particular, micro-EDM is a non-contact material removal process in which rapid electric spark discharges remove the material composing the workpiece by means of melting and vaporizing phenomena. The present work deals with the fabrication of micro holes using micro-EDM technology. The investigation focuses on the influence of different electrodes and workpiece materials on the process performance, expressed in terms of tool wear ratio. In particular, the influence of four different workpiece materials (stainless steel, titanium, magnesium and brass), three electrode materials (copper, brass and tungsten carbide) and two different electrode shapes (cylindrical and tubular) was investigated. Moreover, an analysis of the geometrical characteristics of the micro holes in terms of conicity and diametrical overcut was carried out. An influence of electrode geometries, electrode material and workpiece material on the final output was found.     

Electroplastic cutting influence on power consumption during drilling process

Electron beam melting (EBM) has been recognized as an emerging additive manufacturing technology, which allows the production of fully dense parts from various metals. The technique builds parts using an electron beam to melt metal powder, layer by layer, in a powder bed. Thus, complex parts, including internal structures, can be made directly from 3D CAD models without special fixtures and cutting tools. Much research is conducted to study the microstructure and mechanical properties of EBM-built parts or to investigate the effects of EBM process parameters on the quality of parts. However, using EBM for building new features on an existing part has received little attention from the research community. Due to its performance, EBM seems able to transform an end-of-life (EoL) part/existing part into a new part without returning to the level of raw material. The aim of this study is to validate such principle. In this paper, an EBM machine was used to produce new Ti-6Al-4V features on a Ti-6Al-4V plate, which was considered as a useful core retrieved from an EoL product. The built samples, including EBM-built features and Ti-6Al-4V plate, were investigated in terms of their microstructure and mechanical properties. The results showed that EBM technique allows new features with a suitable microstructure and controlled mechanical properties to be built on an existing part. Moreover, the EBM-built features have a strong bond with the existing part leading to the same mechanical characteristics as original part. These demonstrate that the EBM technology has a promising potential for producing new parts from EoL parts/existing parts.     

高速钻削碳纤维复合材料加工参数对入口分层的影响研究

高速切削技术一直以来都是提高生产效率和节约成本的关键技术。碳纤维复合材料以其耐磨性、耐腐蚀性等一系列优点倍受人们的青睐。研究了碳纤维复合材料在高速钻削过程中切削速度、进给速度和钻头刀尖角对钻削入口分层的影响;利用三水平的全因子分析法进行钻削试验,同时将得到的分层因子建立二元非线性回归模型,并进行方差分析和响应面分析。研究结果表明:分层对进给速度的敏感性更强;随着切削速度的提高,分层因子逐渐减小;小的刀尖角更有助于获得好的加工孔质量。所构造回归模型的预测结果与试验结果基本一致,表明该模型可以有效地预测钻削表面的分层状况。     

基于过程神经网络的航空发动机性能参数预测

针对传统方法难以对性能参数进行有效预测的问题,提出一种基于过程神经网络的性能参数预测方法。为解决反向传播学习算法收敛速度慢、易陷于局部极小点等问题,开发了一种基于正交基函数展开的Leven-berg-Marquardt学习算法。为提高过程神经网络的泛化能力,从提高训练样本的质量和规模入手,研究了实际测量数据的预处理方法,并提出一种基于样条函数拟合和相空间重构理论的训练样本集构造方法。最后,将该方法用于某型航空发动机性能参数的预测,获得了满意的结果。     

Studies on the influence of process parameters on the AISI 316L resistance spot-welded specimens

Energy saving and improving product performance are long-term concerns in extrusion process. Therefore, this paper proposes a novel extrusion process called alternate extrusion (AE). The proposed process uses split punches alternately instead of the overall structure to apply the downward load, but receives an unexpected load-saving and grain refinement effect. Experimental and finite element method (FEM) methods were used to investigate the effects of different extrusion ratios on microstructure and mechanical properties. Results indicate that load value is significantly reduced, grain size is considerably refined, and tensile strength and elongation of material are improved after AE processing. The fractography shows that the fracture mode of AZ31 magnesium alloy changes from brittle to ductile. Although the actual extrusion ratio decreases in AE process, additional shear forces produced by different punch-alternating loads at the interface improve microstructure and mechanical properties. Therefore, AE can achieve grain refinement and load saving and improve strength and plasticity of magnesium alloys.     

工艺参数对芯片围坝成形结构尺寸性能的影响研究

尺寸性能是影响芯片围坝成形结构精度的重要指标,主要受围坝材料特性及成形工艺参数的影响,其中入口驱动压力、基板/喷管运动速度等为可控工艺参数。针对围坝成形的动态过程,建立了该过程流体动力学模型以及可控工艺参数对围坝高度及其内外围面积的尺寸预测模型,并通过数值仿真和实验进行了验证。结果表明,围坝高度和外围面积随入口驱动压力的增大而增大,但随基板/喷管运动速度的增大而减小;内围面积与高度和外围面积的变化趋势相反;其中基板/喷管运动速度的变化对尺寸性能的影响最为明显。另外,所建模型能对围坝成形结构的尺寸精确预测。研究结果可为围坝尺寸控制提供指导。     

关键结构参数对弹簧离合器传扭性能影响分析

弹簧离合器具有结构简单、传递功率密度大的特点,但目前对其传扭失效特征尚不明晰。采用有限元数值计算方法,建立了2000 kW弹簧离合器模型;重点研究了弹簧离合器的变截面弹簧间隙及其激发圈厚度等关键结构参数对离合器传扭性能的影响;分析了不同结构参数下弹簧内外圈应力以及弹簧离合器的传扭失效特征;实验测试了弹簧激发圈厚度较小时离合器传扭性能,验证了其打滑失效特征。研究表明:较大的弹簧间隙会降低弹簧离合器传递扭矩能力,导致其打滑失效;适当减小弹簧间隙,可提高传递扭矩能力,使应力分布更合理;减小弹簧激发圈厚度,激发扭矩减小,易导致弹簧离合器打滑。弹簧离合器传扭性能的研究,为弹簧离合器的优化设计提供了依据。