B_4C增强铝基复合材料钻削温度的非接触测量和多目标分析(英文)

采用光学高温计对在不同钻削条件下的B4C金属基复合材料的钻削温度进行非接触测量。研究了颗粒含量、切削速度、进给速率和刀具材料对最高钻削温度的影响。基于最高切削温度和刀具磨损对钻削参数进行优化。结果表明:对最高切削温度影响最大的因素主要为颗粒含量、进给速率以及切削速率与颗粒含量间的相互作用。切削速率与切削材料对最高切削温度的影响相对较小。当颗粒含量较小,切削速度较低,进给速率较高,利用硬质合金刀具时,切削温度较低。采用优化后的钻削参数可以获得较低的切削温度和较小的刀具磨损。     

TiN涂层刀具切削淬硬H13钢切削性能试验研究

为研究TiN涂层刀具切削淬硬H13钢的切削性能,进行了TiN涂层刀具车削加工淬硬H13钢试验。分析了切削用量与切削力、切削温度的关系及涂层刀具磨损机制。研究得出切削速度、切削深度、进给量都对主切削力Fz和切深抗力Fx影响较大,对切削进给抗力Fy影响相对较小;切削速度对切削温度的影响最大;对刀具磨损观察发现刀具的前刀面有明显的月牙洼磨损,刀尖部位出现了微崩刃现象,后刀面出现磨粒磨损。研究结果为生产加工中优化切削用量及提高刀具寿命提供了技术支持和试验依据。     

钻削B4C颗粒增强铝合金工艺参数对刀具磨损和孔尺寸精度影响的分析和优化

基于刀具磨损和钻孔尺寸误差等多个性能指标,对B4C颗粒增强铝合金切削加工参数进行评估和优化。通过Taguchi的L27,3水平4因子正交阵列进行实验设计。研究结果表明：磨粒磨损和积屑瘤一般在刀具磨损时形成,同时,边角磨损也具有重大意义。影响切削刀具的侧面磨损主要决定因素是合金中的颗粒质量分数,其次分别是进给速率、钻头的硬度和主轴转速。在所有使用的刀具中,有TiAlN涂层的硬质合金钻头在刀具磨损以及孔尺寸方面具有最佳性能。灰关系分析表明：钻头材料的影响比进给速度和主轴转速的影响更大。在最佳的钻探参数下可以得到最小的刀具磨损和孔直径误差。     

基于整体刀具的铣削加工温度有限元分析

在对金属切削的热力学以及热传导过程进行理论分析的基础上,基于整体刀具建立了铝合金薄壁件铣削加工的三维有限元模型。改变切削深度、切削速度以及进给率等工艺参数,分析了铣削工艺参数对温度的影响。仿真结果表明：切削深度对铣削温度影响最大,切削速度和进给率对铣削温度的影响相对较小。将仿真结果与试验测量结果进行对比分析,仿真结果温度值略高于试验结果,但总体变化趋势和规律基本一致。     

切削SiCp/6005Al复合材料的PCD刀具磨损

为研究SiCp/6005Al切削时的刀具磨损机制及刀具磨损对切削力、切削温度、工件表面质量的影响，进行不同转速V和不同进给速度f下的切削试验，观察每组试验刀具切削后的磨损形貌，并通过监测动态切削力和切削温度来探究刀具的磨损机制。结果表明：工件转速提高使切削温度明显升高，但对切削力的影响很小；进给速度提高使切削力明显升高，而切削温度的变化范围较小。改变进给速度带来的力载荷变化是影响前刀面磨损的主要因素，改变工件转速带来的切削温度变化是影响后刀面磨损的主要因素。此外，刀具磨损是磨粒磨损、黏结磨损的综合作用结果，且刀具磨损会对切削力、切削温度和加工表面质量产生不利影响。     

铣削大理石切削参数对PCD刀具磨损的影响

目的探索PCD刀具磨损机理,以延长刀具使用寿命。方法设计正交试验,研究不同加工参数切削大理石对刀具磨损的影响情况。分析主轴转速、进给速度与切削深度对PCD刀具磨损量的影响规律,以优化切削参数来减小刀具磨损量。根据经验公式,建立单位时间刀具磨损量和固定行程磨损量模型。通过对试验过程刀具振动情况记录,结合刀具实际磨损情况,给出了刀具磨损等级。结果主轴转速的提高可以减少刀具磨损量,进给速度的增大会加剧刀具磨损,而切削深度小于1 mm时,其对刀具磨损量的影响很小,但切削深度大于1 mm时,继续增大切削深度会使刀具快速磨损。利用预测模型能够很好地对刀具磨损情况进行预判,根据磨损等级,得出刀具与机床发生共振时磨损最为严重,在刀具表面产生了明显的犁沟、磨损以及金刚石颗粒脱落。结论在实际加工中,通过提高主轴转速、降低进给速度以及减小切削深度有助于增强刀具的耐用度,避开共振切削参数可以有效降低刀具磨损,主轴转速、进给速度、切削深度分别为12000r/min、500 mm/min、0.5 mm时的切削效果较佳,有最小的刀具磨损量。     

基于刚粘塑性变分原理的金属切削过程数值模拟

为了研究切削过程中的切削力和切削温度的分布和刀具磨损,优化高速切削参数,基于刚粘塑性有限元方法,采用有限元计算软件建立适于金属切削过程的三维有限元模型。模拟了45号钢的切削加工过程。主要研究了切屑的形成过程、切削力、温度场的分布以及切削应力的分布。详细分析了切削速度、进给量以及切削深度对切削力、刀尖温度以及刀具磨损的影响。该研究为金属切削加工选择合理的加工参数提供了理论依据。     

基于刀具磨损率及加工效率的工艺参数优化

钛合金环槽铆钉因其高的铆接强度及良好的防松性能被广泛应用于航空航天行业。钛合金切削性能差,切槽刀具工作环境恶劣,使得切槽车刀的磨损更加严重。以钛合金环槽车削加工为研究对象,运用数值方法,得到不同的切削速度、进给量参数下,钛合金车削加工环槽时硬质合金刀具后刀面的磨损速率。通过数据分析,建立刀具后刀面磨损速率预测模型,利用最小二乘法进行参数辨识。应用遗传算法对考虑刀具后刀面磨损速率和切削加工效率的双目标进行优化,得到最优工艺参数组合。结果表明,经过优化的工艺参数,使整体目标值提高了2.9%。     

结构创新的CircoTecRX铰削系统

铰削工艺在传统上是一种高进给、低切速的加工方式，但随着刀具材料的不断进步，目前铰削加工也能采用更高的进给率和切削速度。此外，在刀具设计上，开发出了可换式铰削头，使用户在铰刀磨损后只需更换铰削头而不必更换整个刀具。     

高速切削钛合金的涂层硬质合金刀具粘结磨损

针对粘结磨损对涂层硬质合金刀具使用寿命的影响问题,为了优化刀具涂层材料,降低刀具磨损率,基于热力学理论,计算了硬质合金刀具涂层材料的焓值,分析了涂层材料的耐磨性,研究了涂层硬质合金刀具粘结磨损规律。通过涂层硬质合金刀具切削加工钛合金的实验,使用EDS分析仪和白光干涉仪分别对涂层硬质合金刀具切削加工后的元素能谱和表面形貌进行了分析。结果表明:采用热力学理论分析方法可以获得较好的粘结磨损预测精度,高速切削时刀具磨损区域发生了粘结磨损,磨损原因与元素扩散密切相关;粘结磨损主要发生在中速切削时;随着切削速度的提升,粘结磨损率先增加后降低。所得结论将为优化切削参数、提高刀具寿命提供有益的参考。     

干式钻进金刚石钻头的制备及钻进性能研究

对干式钻进金刚石钻头的优点和国内干式钻进市场的现状,以及干式钻进钻头胎体设计的原则等问题进行了概述,实验中引入超细钨铜合金粉末来解决钻头烧结及钻进过程中存在的问题。实验结果显示:采用质量分数为45%的钨铜合金粉末,配合Cu、Co及Ni等金属粉组成胎体,通过制粒、预压成型、脱蜡、烧结、焊接等工艺制备了实验钻头,当烧结温度为850℃,压力25 MPa,保温时间180s时,钻头刀头的硬度超过HRB110,金刚石出刃效果好。与韩国某公司钻头进行花岗岩钻进对比显示:本实验钻头钻进效率提高7%,寿命和韩国某公司钻头相当,体现出了良好的干式钻进性能。      

双轴钻床钻轴刚度失谐对钻削颤振的影响

运用近频摄动理论分析了双轴钻床钻轴刚度失谐后对钻轴系统固有振动频率的影响。模拟计算结果表明：引入适当的钻轴刚度失谐量，能够分离原钻轴系统彼此接近的固有频率，避免两钻轴间固有近频振型之间的耦合，从而抑制钻削颤振现象的发生.     

Deep hole drilling

Deep hole drilling processes, which differ significantly from conventional drilling processes, are relevant for a lot of different applications where holes with high length-to-diameter-ratios and very good qualities are necessary. This paper gives an overview of different methods, which are established to produce bore holes with demanding aspects related to diameter, length-to-diameter-ratio, bore hole quality, workpiece materials and complex internal contours. Beside the detailed explanation of the deep hole drilling methods and tools also the fundamentals of the deep hole drilling principle are explained and completely new developed figures and tables summarize the state of the art. In addition for the most important areas the latest results of process and tool development are included.     

Friction drilling of cast metals

This study investigates the friction drilling process, a nontraditional hole-making technique, for cast metals. In friction drilling, a rotating conical tool is applied to penetrate work-material and create a bushing in a single step without generating chip. The cast aluminum and magnesium alloys, two materials studied, are brittle compared to the ductile metal workpiece material used in previous friction drilling research. The technical challenge is to generate a cylindrical shaped bushing without significant radial fracture or petal formation. Two ideas of pre-heating the workpiece and high speed friction drilling are proposed. Effects of workpiece temperature, spindle speed, and feed rate on experimentally measured thrust force, torque, and bushing shape were analyzed. The thrust force and torque decreased and the bushing shape was improved with increased workpiece temperature. Varying spindle speed shows mixed results in bushing formation of two different work-materials. The energy, average power, and peak power required for friction drilling were calculated and analyzed to demonstrate quantitatively the benefits of workpiece pre-heating and high spindle speed in friction drilling.     

Burr minimizing scheme in drilling

In conventional drilling, burr formation can be changed by varying the drill’s geometry, i.e. the step angle and point angle. To minimize burr formation, it is proposed that a step drill be used. The step drill performs front edge cutting before step edge cutting. The burr formed in first cutting by front cutting edge can be removed in second cutting by step edge. In particular, new burrs are formed through the second cutting. They can be minimized by changing the drill’s geometry. A laser sensor is used to measure the burr formed in the drilling.     

Chip thickening in deep-hole drilling

In conventional turning and milling cutting process models, chips are free of external forces after leaving the cutting area. However, in a drilling process, chip flowing is constrained by the drill flute, causing the change of chip shape and drilling forces. In this research, it is found that when drilling deep holes, the chip thickness increases as drilling progresses deeper into the workpiece. It is also found that during a deep-hole drilling process a significant part of the drilling force increase is due to the chip thickening effect. An analytical model was developed to predict the force increase caused by chip thickening. Experiments have been carried out to verify the model.     

Continuous chip formation in drilling

The formation of coil continous chips in drilling often leads to chip disposal problems. This paper investigates the drill chip formation process of continuous chips (spiral chips and string chips). Chip removing motions and forces are analyzed. Two models are developed to predict the spiral and string chip formation, respectively. Based on the level of bending due to the chip generation at the cutting edge and deflection by the flute, these models qualitatively investigate relationship of the point angle and flute helix angle on the average chip length. Drilling experiments validate the chip length for spiral and string chip predicted by both models.     

Tool wear in friction drilling

This study investigates the tool wear in friction drilling, a nontraditional hole-making process. In friction drilling, a rotating conical tool uses the heat generated by friction to soften and penetrate a thin workpiece and create a bushing without generating chips. The wear of a conical tungsten carbide tool used for friction drilling a low carbon steel workpiece is studied. Tool wear characteristics are quantified by measuring its weight change, detecting changes in its shape with a coordinate measuring machine, and making observations of wear damage using scanning electron microscopy. Energy dispersive spectrometry is applied to analyze the change in chemical composition of the tool surface due to drilling. In addition, the thrust force and torque during drilling and the hole size are measured periodically to monitor the effects of tool wear. Results indicate that the carbide tool is durable, showing minimal tool wear after drilling 11,000 holes, but observations also indicate the progressively severe abrasive grooving on the tool tip.     

High-throughput drilling of titanium alloys

Experiments of high-throughput drilling of Ti–6Al–4V at 183 m/min cutting speed and 156 mm³/s material removal rate (MRR) using a 4 mm diameter WC–Co spiral point drill were conducted. The tool material and geometry and drilling process parameters, including cutting speed, feed, and fluid supply, were studied to evaluate the effect on drill life, thrust force, torque, energy, and burr formation. The tool wear mechanism, hole surface roughness, and chip light emission and morphology for high-throughput drilling were investigated. Supplying the cutting fluid via through-the-drill holes has proven to be a critical factor for drill life, which can be increased by 10 times compared to that of dry drilling at 183 m/min cutting speed and 0.051 mm/rev feed. Under the same MRR of 156 mm³/s with a doubled feed of 0.102 mm/rev (91 m/min cutting speed), over 200 holes can be drilled. The balance of cutting speed and feed is essential to achieve long drill life and good hole surface roughness. This study demonstrates that, using proper drilling process parameters, spiral point drill geometry, and fine-grained WC–Co tool material, the high-throughput drilling of Ti alloy is technically feasible.