刀尖圆弧半径补偿对球面零件车削加工影响的分析

采用刀尖圆弧半径为0.4 mm的刀片,以0、0.4 mm、0.8 mm、1.2 mm为刀尖圆弧半径补偿值,得到球面曲率半径不同的四个试件,基于三丰C-3200测量仪对球面轮廓度进行测量,分析刀尖圆弧半径补偿对球面零件车削加工的影响。分析结果表明,在进行凸球面零件加工时,HNC-818A数控系统中的刀尖圆弧半径补偿功能有效,球面的曲率半径与刀尖圆弧半径补偿值的单调性一致。当刀尖圆弧半径补偿值线性变化时,球面的曲率半径呈非线性变化。当设定刀尖圆弧半径为真实值时,球面轮廓最为理想。在球面零件加工实践中,使用刀尖圆弧半径补偿功能,精加工采用可转位机夹车刀,通过试切法合理修改刀尖圆弧半径补偿值,可以提高球面零件的车削加工质量。     

无线传感器网络中移动sink节点的路径规划

在无线传感器网络中,大量感知数据汇集到sink节点的采集方法会导致sink节点附近的节点能量耗尽,造成能量空洞。针对该问题,利用移动的sink节点进行数据收集是一种解决方法,其中移动sink的路径规划成为一个重要的问题。提出了一个移动sink路径规划算法,将无线传感器中随机分布的节点划分为不同的子区域,寻找sink节点移动的最佳转向点,最终得到最优的移动路径,以实现无线传感器网络生命周期最大化。仿真实验表明,与现有方案相比,该算法能显著延长网络的生命周期。     

Three-dimensional finite element analysis of geosynthetic-reinforced soil walls with turning corners

The paper presents in-depth three-dimensional finite element analyses investigating geosynthetic-reinforced soil walls with turning corners. Validation of the 3D numerical procedure was first performed via comparisons between the simulated and reported results of a benchmark physical modeling built at the Royal Military College of Canada. GRS walls with corners of 90°, 105°, 120°, 135°, 150°, and 180° were simulated adopting the National Concrete Masonry Association guidelines. The behaviors of the GRS walls with corners, including the lateral facing displacement, maximum reinforcement load, factor of safety, potential failure surface, vertical separation of facing blocks, and types of corners were carefully evaluated. Our comprehensive results show (i) minimum lateral displacement occurs at the corner; (ii) lower strength of reinforcements are required at the corner; (iii) higher corner angles lead to lower stability; (iv) potential failure surface forms earlier at the end walls; (v) deeper potential failure surfaces are found at the corners; (vi) larger numbers of vertical separations are found at walls with smaller corner angles. The paper highlighted the salient influence of the corners on the behaviors of GRS walls and indicated that a 3D analysis could reflect the required reinforcement length and the irregular formation of the potential failure surfaces.     

多轴线转向车辆转向机构的优化设计与试验研究

多轴线转向车辆转向机构是车辆实现转向功能的核心部件,根据某矿用车对转向机构的工作要求,设计和建立了多轴线转向车辆转向机构的仿真模型,并对转向机构进行了优化,同时对液压系统进行建模,通过分析软件对液压系统的特性进行仿真分析,通过试验测试,证明所设计转向杆系及液压系统的响应特性与仿真结果吻合,达到了预期效果。     

带自制跟刀架的振动车削细长轴实验研究

细长轴的车削面临振动和让刀两大核心问题。针对振动问题,研制了拉夹顶尖,将工件受到的压应力变为拉应力,从而克服了压杆稳定极限,并且降低了产生振动的可能性。建立了一端卡盘一端拉夹顶尖装夹形式下的力学模型。针对让刀现象,研制了超声振动车削系统和自制跟刀架。超声振动车削方式通过对刀具附加高频,一定振幅的振动信号,使得车削过程中的切削力,切削热显著降低,并且有优异的抑制振动的效果。自制跟刀架通过微分头的形式实现辅助支撑作用。通过超声振动车削细长轴的实验,证明了自制拉夹顶尖、超声振动车削方式和自制跟刀架的组合在加工细长轴的有效性。     

Experimental Study on Hybrid Cryogenic and Plasma-Enhanced Turning of 17-4PH Stainless Steel

This article presents machinability of 17-4PH stainless steel using a hybrid technique composed of plasma-enhanced turning and cryogenic turning. First of all, using some primary experimental tests and nonlinear regression, a mathematical model was developed for surface temperature of uncut chip as a function of plasma current and cutting parameters. Then, the influence of cutting speed (V_c), feed (f), and surface temperature of uncut chip (T_sm) was studied on surface roughness (R_a), cutting force (F_z), and tool flank wear (V_B). The results show that hybrid turning (HYT) is able to lower the main cutting force and tool flank wear in comparison with conventional turning. In addition, surface roughness was improved except for high level of surface temperature of uncut chip. However, hardness measurement of machined workpiece showed that HYT does not change the hardness of machined surface.     

Fundamental Turning Characteristics of Inconel 718 by Applying Ultrasonic Elliptical Vibration on the Base Plane

Inconel 718, a nickel-based superalloy, exhibits desirable properties over a wide temperature range, and it is widely used in industry. However, Inconel 718 is typically difficult to cut because of its strong work hardening, high temperature tensile strength, and shear strength. To improve the machinability of Inconel 718, this study proposes ultrasonic turning by applying elliptical vibration to the base plane. The principle and features of the ultrasonic elliptical vibration are discussed in detail. Experiments were conducted on a commercial ultrasonic cutting unit installed onto a commercial numerical control (NC) lathe; the cutting forces were found to be lower in the new method than in conventional turning (CT). Microchip particles were observed on both chip and work surface in CT but were almost absent on the surfaces prepared by ultrasonic elliptical vibration assisted turning (UEVT). Furthermore, the cutting tool used in CT developed built-up edge (BUE), and its flank wear became heavier; in contrast, negligible BUE and less flank wear were found on the cutting tool used in UEVT. The theoretical surface roughness of UEVT was calculated and it agreed much well with the measured surface roughness.     

圆盘类零件加工自动上下料系统设计

针对批量加工皮带轮用圆盘类零件中人工上下料问题,设计一种经济型数控车床适用的自动上下料方案,有效提高了生产自动化程度。整个装置基于CK6136-750机床,采用SolidWorks软件对自动上下料装置进行了设计,包括上料机构、下料机构、坯料推进机构等。通过数控系统二次开发,结合气动技术、PLC控制技术与传感器技术,开发自动上下料控制系统,并添加进CNC系统的辅助功能中,实现了上料、加工、下料的一体化控制,可以一人多机操作,降低了生产成本,缩短了加工时间,具有广泛的市场需求和工业应用前景。