Experimental investigation of rotary sinking electrochemical discharge milling with high-conductivity salt solution and non-pulsed direct current

Electrochemical milling is a modified technique of traditional electrochemical machining (ECM) that can be used to manufacture some helicopter transmission system parts. The use of rotary tools and an inner-jet electrolyte supply pattern can greatly improve the material removal rate (MRR) in a single pass. However, the feed speed is generally limited to minimize the tool wear. To increase the MRR, electrical discharge machining (EDM) is introduced into the electrochemical milling process. The tool rotation is employed to interrupt the discharge and the high-conductivity salt solution and non-pulsed direct current power supply are also adopted to increase ECM, eventually, a new machining method is proposed, which can be called rotary sinking electrochemical discharge milling (RSECD milling). The mechanism of it is explored in this study by analyzing the machined current, MRR, surface morphology, and tool wear at different applied voltages and feed speeds. Besides, the RSECD milling using the tool with a larger diameter is also conducted to further verify the effectiveness. In particular, the MRR can be increased by 742.5% when using the tool with a diameter of 20 mm at the applied voltage of 20 V.     

In-process adaptive milling for large-scale assembly interfaces of a vertical tail driven by real-time vibration data

Assembly interfaces, the joint surfaces between the vertical tail and rear fuselage of a large aircraft, are thin-wall components. Their machining quality are seriously restricted by the machining vibration. To address this problem, an in-process adaptive milling method is proposed for the large-scale assembly interface driven by real-time machining vibration data. Within this context, the milling operation is first divided into several process steps, and the machining vibration data in each pro...     

不同材质刀具在7075铝合金高速铣削中的磨损研究

为了研究7075铝合金高速铣削中不同材质刀具的磨损与选用,采用化学气相沉积法（（CVD）制备微米（MCD）/纳米（NCD）金刚石涂层刀具,利用场发射扫描电镜观察膜层的表面形貌,结合拉曼谱仪分析CVD金刚石涂层刀具薄膜的结构和成分;分别采用同规格尺寸的硬质合金刀具、MCD涂层刀具在无润滑干切条件下,进行粗加工高速铣削试验,观测两种刀具在加工一定距离后的磨损状况;分别采用同规格尺寸的硬质合金刀具、MCD涂层刀具、NCD涂层刀具在无润滑干切条件下,进行精加工高速铣削试验,观测和分析工件精加工铣削后的表面粗糙度值。结果表明：在大切深高速粗加工铣削7075铝合金时,MCD涂层刀具的寿命为硬质合金刀具的3倍;在小切削深度大进给的高速精加工7075铝合金中,三种刀具铣削后的工件表面粗糙度平均值分别为0.981、1.122和0.960 μm,NCD涂层刀具的加工效果要优于MCD涂层刀具;同时通过同一材质刀具的粗、精加工试验对比,发现同规格尺寸的刀具在小切深大进给高速精加工中的寿命是大切深大进给高速粗加工寿命的10倍。这说明7075铝合金的粗加工铣削优选MCD涂层刀具,精加工铣削优选NCD涂层刀具。     

Cutting tool temperature prediction method using analytical model for end milling

Dramatic tool temperature variation in end milling can cause excessive tool wear and shorten its life, especially in machining of difficult-to-machine materials. In this study, a new analyt-ical model-based method for the prediction of cutting tool temperature in end milling is presented. The cutting cycle is divided into temperature increase and decrease phases. For the temperature increase phase, a temperature prediction model considering real friction state between the chip and tool is proposed, and the heat flux and tool-chip contact length are then obtained through finite element simulation. In the temperature decrease phase, a temperature decrease model based on the one-dimension plate heat convection is proposed. A single wire thermocouple is employed to mea-sure the tool temperature in the conducted milling experiments. Both of the theoretical and experi-mental results are obtained with cutting conditions of the cutting speed ranging from 60 m/min to 100 m/min, feed per tooth from 0.12 mm/z to 0.20 mm/z, and the radial and axial depth of cut respec-tively being 4 mm and 0.5 mm. The comparison results show high agreement between the physical cutting experiments and the proposed cutting tool temperature prediction method.     

整体叶盘盘铣加工切削力及刀具磨损实验研究

本文对整体叶盘开槽粗加工时从切削速度、进给量、径向切深等切削参数对切削力的影响进行研究。选用正交实验的方法进行盘铣切削实验,得到切削参数对切削力的影响变化规律,并对刀具在切削过程中的磨损进行分析,进一步验证优化的切削参数,为整体叶盘的盘铣加工参数的合理制定与加工工艺的优化提供参考。     

飞机装配中的先进制孔技术与装备

制孔加工是飞机装配过程中的重要工作之一.生产效率的高要求,加工质量、精度的苛刻标准,以及复合材料、钛合金等难加工材料的大量使用,使得飞机装配制孔技术不断面临新的挑战.而基于不同切削原理的制孔新方法与技术装备,成为解决当下飞机装配制孔难题的途径之一.     

基于智能制造某航空机匣工艺验证与应用

本文基于某型航空机匣铸件改机加工,结合航空企业智能制造实施应用,通过制定攻关方案,选择铣车复合工艺路线、定制外购刀具,选择自制夹具,优化数控加工工艺,完成了智能制造模式某型航空机匣在航空制造企业工艺验证与实施应用。     

镍基高温合金铣削加工的残余应力研究

对硬质合金与陶瓷两类不同刀具分别以低速湿式铣削和高速干铣削方式加工镍基高温合金GH4169时的已加工表面残余应力进行研究.采用X射线衍射法测量铣削后的工件表面残余应力.采用涂层硬质合金刀具在较低铣削速度30～90m/min并浇注切削液的条件下铣削GH4169时,可在工件表面形成残余压应力或相对较小的残余拉应力,对残余应力数据进行统计分析.结果表明,刀具和铣削速度对表面残余应力均有显著影响,而且表面残余应力总体上随着每齿进给量的增加而呈现拉应力增加的趋势.采用涂层Al2O3-SiCw和Sialon陶瓷刀具以较高铣削速度300～1100m/min干铣削GH4169时,工件表面都将形成很大的残余拉应力.镍基高温合金GH4169的精加工更适合采用硬质合金涂层刀具并浇注切削液充分冷却,而陶瓷刀具干铣削则更适合于GH4169的粗加工.     

钛合金径向超声振动铣削表面粗糙度研究

为提高钛合金零件加工质量,设计了径向超声振动辅助铣削试验装置,研究了切削速度、切削深度、进给速度和超声振动幅值对钛合金零件表面粗糙度的影响规律.试验结果表明,与普通铣削相比,径向超声振动铣削后工件上的刀痕更加平整、分布更加均匀,材料去除更彻底,有效减少了由于钛合金切屑粘刀造成的表面划痕和积屑瘤等现象.在不同的切削参数下,径向超声振动铣削均可以改善钛合金零件的表面粗糙度,这一点在低速切削时更为明显,而超声振动幅值过大或过小都会影响加工质量.对加工系统的切削力进行了分析,发现超声振动辅助铣削时系统的切削力明显减小,有助于提高加工系统的稳定性,从而能够获得较好的表面质量.     

GFRP铣槽加工铣削力及表面粗糙度研究

铣槽是复合材料较常用的机械加工形式之一。为研究玻璃纤维增强复合材料(Glass Fiber Reinforced Plastic,GFRP)铣槽加工中各加工参数对铣削力和表面粗糙度的影响,开展了以主轴转速、进给速度和轴向切深为因素的正交试验,研究铣削力和表面粗糙度的变化规律。并用Matlab软件对铣削力和表面粗糙度的试验数据进行回归分析,建立了铣削力和粗糙度的经验公式,最后通过试验验证铣削力和表面粗糙度经验公式的正确性。结果表明:轴向切深对铣削力影响最大,其次是主轴转速,进给速度对铣削力影响最小;主轴转速对粗糙度的影响最大,其次是进给速度,轴向切深对粗糙度的影响最小。试验结果与铣削力、表面粗糙度经验公式算得的数值对比,误差范围都在20%以内。