高温合金振动钻削断屑实验研究及机理分析

对振动钻削理论进行了分析,建立了振动钻削时断屑的数学模型,利用自制的振动钻削实验装置,采用不同的振动钻削参数进行高温合金振动钻削试验,对轴向振动钻削的断屑效果以及轴向钻削力和扭矩进行了研究,分析了各加工参数对加工过程的影响,发现振动钻削力随钻削参数的变化比较平稳,在大进给量或高转速状态下,振动钻削的钻削力比普通钻削力小得多。通过比较振动钻削与普通钻削所得切屑可知:振动钻削有利于断屑,切屑体积小,排屑顺畅。     

变进给量振动钻削提高微小孔加工质量的分析

应用压电陶瓷振动台振动钻削装置,采用变进给量振动钻削法加工微小孔,并用工具显微镜对入钻定位误差和出口毛刺进行测量。采用最小二乘法对所得试验数据进行处理,从而得到进给量与出口毛刺之间的关系,通过对两种条件下(变进给量振动钻削和普通钻削)所得试验数据的比较可知,变进给量振动钻削能使加工质量得到很大提高。     

低频扭转振动钻削参数选择

介绍了低频扭转振动的实验装置，分析了切屑的大小与工艺参数的关系，通过钻削加工实验，得以证明，选用较小的进给量，中等切削速度，大振幅，有利于小深孔钻削加工的断屑和排屑，从而保证和提高了小深孔钻削加工的质量，有利于低频扭转振动工艺得到更广泛的应用。     

错齿BTA深孔钻削切屑变形及刀屑接触长度分布规律研究

断排屑问题一直是错齿BTA内排屑深孔钻削的难点,通过建立切屑流经断屑台的几何变形模型分析了刀屑接触长度对错齿BTA钻削切屑的变形断裂的影响,采用有限元分析软件DEFORM-3D建立了错齿BTA钻头钻削仿真模型,对各刀齿切屑的形成及变形规律进行了分析,研究了刀屑接触长度随刀齿钻削半径分布规律及其随钻削条件的变化规律,并利用实验对仿真结果进行了验证分析。结果表明,仿真结果可信,刀齿钻削半径对切屑的变形及刀屑接触长度影响很大,刀屑接触长度随钻削进给量增大而增大,随转速增大而减小,随工件材料强度增大而增大。     

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。     

基于DEFORM-3D轴向振动钻削304不锈钢有限元仿真

难加工材料微小孔钻削过程中存在钻削力大、断屑难及钻削温度高等加工问题,而轴向振动钻削方法可以解决此类问题。基于轴向振动钻削机理,对轴向振动钻削的运动特性和变厚切削特性进行了分析。通过DEFORM-3D软件建立了轴向振动钻削有限元模型,对304不锈钢进行了振动频率为550 Hz,振幅为16μm,转速为3 000 r/min,进给量为50μm/r的轴向振动钻削和普通钻削仿真试验,对比分析了两种加工过程中的切屑形态、轴向力和扭矩等。结果表明：与普通钻削相比,轴向振动钻削具有更好的断屑效果,可以降低平均轴向力约48.1%,降低平均扭矩约38.2%。     

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。     

超声振动钻削切屑形成机理及实验研究

针对难加工材料钻孔不易断屑、加工难度高等问题,采用超声振动技术进行加工.对振动钻削的切屑形成机理进行分析,建立了切削刃的运动轨迹方程,推导出了不同相位差下的切削刃运动轨迹和切屑厚度方程,研究了切削厚度变化情况和断屑特性,得到了振动钻削中的完全几何断屑的条件.最后,通过201不锈钢钻削实验,对得出的切屑进行对比分析,验证了断屑条件,进而实现了对难加工材料钻孔切屑的有效控制.     

深孔加工轴向振动装置设计

深孔加工在孔加工中占有较大的比重,深孔加工技术的难点之一是连续自动排屑。本文基于振动钻削机理,结合现有轴向振动钻削装置,在此基础上进行改进,设计了一套轴向振动装置。装置中使用压电陶瓷致动器有效地避免了机械传动所产生振动的不稳定性。基于Deform-3D软件对轴向振动钻削进行切屑模拟实验,并通过实验验证了轴向振动钻削较普通钻削而言在断屑方面及孔表面质量方面所具有的优势。     

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.     

TC4钛合金低频振动钻削切屑形态和钻削力研究

为研究TC4钛合金低频振动钻削过程中切屑形态与钻削参数和振动参数对钻削力（轴向力和扭矩）的影响规律，基于一种自主研制的低频振动刀柄，分别采用单因素法和正交试验法对钛合金进行了低频振动钻削试验，分析了不同钻削条件下的切屑形态和钻削力，建立了轴向力和扭矩的经验公式，并对钻削力的影响因素进行直观分析与方差分析。结果表明：试验系统在低频振动钻削TC4钛合金时，振幅与进给量之比接近临界断屑值0.81时断屑可靠，排屑顺畅；低频振动瞬时钻削力呈现出规律的正弦波形，钻削力动态分量远大于普通钻削，轴向力和扭矩均值可比普通钻削分别降低10%~15%和15%~20%；进给量对钻削力影响最为显著，振幅次之，钻削速度影响最小；建立的振动钻削经验模型误差保持在10%以内，可以较为准确地对该试验系统所选参数范围内的钻削力进行预测。     

小直径深孔振动钻削钻头的研究

分析了小直径深孔振动钻削对钻头的要求；设计了一种新型内排屑深孔钻头；分析了该钻头的结构和刃磨特点，进行了振动钻削试验。试验表明，合理匹配切削参数和振动参数，可实现断屑可靠且排屑顺畅，能钻出尺寸精度高、表面粗糙度参数值小、直线度较高的深孔。分析了用新型钻头进行振动钻削提高工艺效果的原因，表明该种钻头具有良好的工艺性能。     

Suppression of forced vibration due to chip segmentation in ultrasonic elliptical vibration cutting of titanium alloy Ti–6Al–4V

Ultrasonic elliptical vibration cutting of titanium alloy Ti–6Al–4V is investigated in this research. Because products made of Ti–6Al–4V alloy are usually designed for possessing low-rigidity structures or good-quality cut surfaces, machining requirements such as low cutting forces and slow rate of tool wear need to be fulfilled for realization of their precision machining. Therefore, the ultrasonic elliptical vibration cutting is applied as a novel machining method for those products. Machinability of Ti–6Al–4V alloy by the ultrasonic elliptical vibration cutting with cemented carbide tools is examined to figure out suitable cutting conditions for precision machining of Ti–6Al–4V alloy. As experimental results, generated chips, cutting forces, and profiles of cut surfaces are indicated. A forced vibration problem occurred due to the segmented chip formation, which is also well-known in the ordinary non-vibration cutting. Therefore, characteristics of the forced vibration due to the chip segmentation are investigated in this research. Through the experiments, it is found that the frequency and magnitude of the forced vibration have relation with the average uncut chip thickness and cutting width. Especially, it is found that the averaging effect can suppress the forced vibration, i.e. the chip segmentation tends to occur randomly over the large cutting width, and hence the force fluctuations with random phases tend to cancel each other as the cutting width increases relatively against the average uncut chip thickness. Based on the investigations, a new practical strategy to suppress the forced vibration due to chip segmentation is proposed and verified. Using the proposed method significantly decreased cutting forces and good quality of surfaces are obtained when the forced vibration is suppressed compared to the ordinary non-vibration cutting results. Therefore, the results suggest that the precision machining can be realized without sacrificing the machining efficiency by increasing the width of cut and decreasing the average uncut chip thickness.     

振动钻削改善排屑效果机理的研究

通过建立常规钻削加工排屑管中切屑颗粒的运动方程 ,推导出振动钻削加工条件下切屑颗粒的运动特点 ,研究了振动参数对排屑速度的影响 ,分析了振动钻削提高排屑能力的原因 ,并提出优先选择振动频率的低频振动钻削加工原则 ,为振动钻削的参数匹配提供了理论基础     

Machining Accuracy Analysis for Step Multi-Element Varying-Parameter Vibration Drilling of Laminated Composite Materials

Laminated composite materials are being extensively used in various fields, and their micro-hole machining is difficult because of their layer structures and particular characteristics. To solve the problem effectively, a new method of step multi-element varying-parameter vibration drilling is proposed. Drilling laminated composite materials is a multi-zone operation which involves the entrance zone, the mid zones, the reciprocal zones and the exit zone. In each zone, optimum parameters including vibration frequency, amplitude and feed should be chosen so as to improve the machining accuracies of micro-holes. Based on the principle of multi-element orthogonal polynomial regression, parametric optimisation experiments of single materials are carried out, and optimum parameters for each zone are obtained. The proposed drilling method can be achieved by using these optimum values for each zone. Comparative experiments using the proposed method indicate that the deflection of the drill r, the error of the micro-hole diameter _D and the height of burrs H can be decreased compared to ordinary drilling, so machining accuracies can be improved.     

振动钻削改善孔壁粗糙度的因素分析

在振动钻削试验的基础上，通过对加工过程和钻削结果的观察和分析，全面论述了振动钻削改善孔壁粗糙度的原因。即振动钻削改善孔壁粗糙度是因为它具有以下的有利因素：良好的断屑和排屑效果，充分的润滑，对切削振动的抑制，对积屑瘤的消除以及对已加工孔壁的往复熨压抛光作用等。     

切屑折断界限的理论研究

从上向弯曲切屑折断界限理论出发,推导出刀片二维槽形切屑流出圆半径及极限进给量的理论预报公式;根据横向卷曲短螺卷屑形成过程中切屑动力学及其折断判据理论,得出了极限背吃刀量的理论预报公式;并通过系统的试验研究,证明试验结果与理论预报结果比较符合。为刀片三维槽形的槽形设计及断屑预报系统建立打下理论基础。     

轴向振动钻削提高钻孔定位精度研究

分析了轴向振动钻削条件下系统的振动响应,发现振动钻削具有明显的减振效果,并在自行研制的振动车床上进行对比实验,发现入钻定位精度随振幅、频率的增大而增大.