切削温度与切削力综合测量的虚拟仪器

介绍了综合测量切削平均温度和三向切削力并对其进行分析处理的虚拟仪器。利用PCI－1200卡采集热电偶测温仪和电阻应变式测力仪传输的数据。利用Lab VIEW平台开发。具有显示力和温度波形曲线、热电偶标定和测力仪刻度标定、确定切削温度和切削力指数公式的能力。提出了基于切削力和切削温度信息的切削状态判定方法。     

高速切削中金刚石涂层Si3N4刀具磨损与切削力分析

利用热丝化学气相沉积(HFCVD)法在Si3N4刀具上涂覆一层金刚石薄膜,用以对灰口铸铁进行加工.切削试验的主要参数:切削速率为500m/min、700m/min和900m/min,刀具进给量0.1mm/r、0.25mm/r和0.4mm/r,切削深度保持恒定为1mm.为了评估切削过程中的刀具性能,着重对刀具切削力进行分析,证实了切削力随着进给量的增加而显著增大.金刚石薄膜的存在使切削过程保持稳定,同时在刀具上观察到来自工件的铁和锰元素的黏附现象.切削试验是在配有三轴测力仪的数控机床上进行的,由国产软件采集并记录测试结果.通过配有X射线能谱仪的扫描电子显微镜分析刀具磨损并利用轮廓仪进行刀具表面分析.     

车梳复合切削特性试验研究

本文围绕车梳复合切削的轴向切削过程中的切削性能问题和切削效率问题,分别在相同的切削参数和材料去除率的条件下,对三种不同齿数车梳刀片的切削力和切削温度进行对比试验.探索了切削刃数目的变化对切削性能及切削效率的影响关系.切削试验包括梳切42CrMo的切削温度及切削力的测量.通过研究结果表明:不同齿数的车梳刀片在不同切削参数下切削温度和切削力有较大差异.在相同的切削参数条件下,多齿刀片的切削力与刀齿数量正相关,分配到每齿上的切削力值小于单刃切削时的数值.且三齿刀具与单齿刀具的切削力值相近;对切削温度而言,各刃口处测量值之间相差不大,单齿切削的切削温度比多齿刀片小.在相同材料去除率的条件下,单齿刀片的切削力数值较高,而三齿刀片和五齿刀片的该值相差不大,且单齿刀片加工后的表面粗糙度较其它两种刀片大.     

基于LabVIEW和单片机的切削温度数据采集系统

在切削加工过程中,切削温度是影响被加工工件的表面质量和刀具磨损的重要因素,因此对切削温度的研究有着重要意义.以人工热电偶为温度传感器,设计了热电偶的安装方法和以P87LPC768为核心,以串口为通讯方式的数据采集硬件电路,该电路对K型热电偶有冷端补偿功能.并利用LabVIEW提供的VISA接口,开发了用于实验室的切削温度实验数据采集的虚拟仪器,实现了对切削温度的在线测量和实时显示.     

车削加工过程建模与MATLAB仿真分析

建立了车削加工过程模型,考虑伺服机构、切削过程和测力仪等环节,并用Matlab对模型进行仿真,分析了阻尼系数、固有频率和切削力指数等参数变化对切削力的影响,研究结果对加工过程的计算机控制具有指导意义.     

基于分子动力学的金属钛纳米振动切削研究

采用分子动力学模拟方法进行了金属钛的纳米振动切削和普通纳米切削的比较研究.结果表明:在相同仿真条件下,单向振动X、Y向切削力平均值仅为普通切削的1/3左右;椭圆振动切削(elliptical vibration cutting,EVC)相比单向振动切削,剪切角变大,切屑的塑性变形降低,同时主切削力以及背吃刀力值均降低;单向振动切削和EVC的切削温度呈近似正弦脉冲变化, 对比普通加工,振动切削的温度显著下降;相比于单向振动切削EVC的工件平均切削温度略高.     

航空钛合金切削过程有限元数值模拟分析

切削加工过程模拟的实质是采用有限元方法求解非线性问题的过程。建立了钛合金构件切削有限元模型,其切屑分离准则是以材料损伤理论为基础确立的;利用已有的研究成果,构建了求解切削温度场和切削力的有限元模型;利用有限元软件ABAQUS/Explicit进行模型建立、材料输入、部件装配、局部细分网格、运动仿真等;通过对钛合金切削过程的仿真计算得到切削温度、切削力等的一般规律。结果表明:模拟结果与实际生产结果相符合。     

振动切削振幅对切削力影响的理论与实验研究

建立了振动切削中切削力的理论模型,研究了振动切削中振幅对切削力的影响机理,并通过数值模拟的方法,从理论上给出精密振动切削中振幅对切削力的影响规律.利用自行设计的超声振动切削系统进行了切削力随振幅的变化规律的实验研究.     

超声振动辅助车削颗粒增强金属复合材料的温度实验研究

对超声切削颗粒增强金属基复合材料的温度进行了实验研究.采用自然热电偶法测量了整个切削过程的温度,发现超声切削温度曲线比普通切削的温度曲线更接近三角形分布的热源模型.采用T型热电偶测量出了超声切削温度的典型特征曲线,即波峰和波谷处均有5个大小基本相等的锯齿状微幅振动的峰值.还分别测量了普通和超声两种加工方式下的切削温度,发现普通车削的温度比超声车削的温度普遍高20℃以上,切削温度随切削速度、进给量和切削深度的增大而升高,但影响程度不同.     

基于切削力的PCBN复合片表面摩擦系数研究

实验使用四种不同成分的PCBN复合片刀具切削淬硬轴承钢GCr15,利用Kistler测力仪测量四种刀具在相同的刀具几何角度、切削用量下的切削力,研究刀具在相同切削条件下的切削力、摩擦力及摩擦系数的差异.结果表明,PCBN复合片的粘结剂、CBN晶粒含量和大小的不同对切削淬硬轴承钢GCr15时的切削力和摩擦系数均有较大影响:导热性较差的陶瓷粘结剂的复合片切削力、摩擦系数明显小于采用金属粘结剂的复合片,并且TiAlCN陶瓷粘结剂复合片的值最小;四种刀具中CBN晶粒的颗粒度越小,含量越少,切削力和摩擦系数越小.     

Modelling of dynamic cutting coefficients in three-dimensional cutting

A new theory to determine the dynamic cutting coefficients from steady state cutting data for three dimensional cutting has been developed. It is based on direct measurements of cutting forces, without any hypothesis relating to the steady state cutting. The experimental results show fairly good coincidence with the theoretical prediction of the stability limit.     

Three-dimensional cutting process analysis with different cutting velocities

This paper uses the large deformation large strain finite-element theory, the updated Lagrangian formulation and the incremental theory approach to develop a 3D elastic-plastic analytical model that examines metal cutting on the tool tip and twin nodes on the machined face. The geometric position and the critical value of strain energy density, combined with twin node treatment, are also introduced to serve as the continuous chip separation criterion.

Finally, the 3D low-velocity cutting condition of mild steel was explored to analyze changes in the appearances of the workpiece and the chip, the distribution of stress and strain, and the progress of changes in the cutting force. The impact of different cutting velocities and the initial conditions of the residual stress were studied to understand the impact of various cutting conditions on the machined workpiece. The numerical average cutting forces are compared with the experimental cutting forces with the different low-cutting velocities to verify that the 3D cutting model that has been developed is reasonable.     

陶瓷刀具在干切削加工中的应用

文章论述了陶瓷刀具的特点和切削性能,对陶瓷刀具在干切削中的使用进行了分析.     

Identification of the specific cutting force for geometrically defined cutting edges and varying cutting conditions

Cutting force modeling is a major discipline in the research of cutting processes. The exact prediction of cutting forces is crucial for process characterization and optimization. Semi-empirical and mechanistic force models have been established, but the identification of the specific cutting force for a pair of tool and workpiece material is still challenging. Existing approaches are depending on geometrical idealizations and on an extensive calibration process, which make practical and industrial application difficult. For nonstandard tools and five axis kinematics there does not exist a reasonable solution for the identification problem.In this paper a co-operative force model for the identification of the specific cutting forces and prediction of integral forces is presented. The model is coupled bidirectionally with a multi-dexel based material removal model that provides geometrical contact zone information. The nonlinear specific forces are modeled as polynomials of uncut chip thickness. The presented force model is not subjected to principal restrictions on tool shape or kinematics, the specific force and phase shift are identified with help of least square minimization. The benefit of this technique is that no special calibration experiments are needed anymore, which qualifies the method to determine the specific forces simultaneously during the machining process. In this paper, experiments with different cutting conditions are analyzed and systematically rated. Finally, the method is validated by experiments using different cutting conditions.     

The effect of vibration cutting on minimum cutting thickness

In the ultra-precision diamond cutting process, the rake angle of the tool becomes negative because the edge radius of a tool is considerably larger compared to the sub-micrometer depth of the cut. The effects of plowing due to the large negative rake angle result in an unstable cutting process without continuous chip. For this reason, it is important to determine minimum cutting thickness in order to enable greater machining accuracy to be obtained by fine and stable machining. It was previously reported that the critical depth of cut with a continuous chip was determined by the tool sharpness and the friction coefficient between a workpiece and a tool [S.M. Son, et al., Effects of the friction coefficient on the minimum cutting thickness in micro cutting, International Journal of Machine Tools and Manufacture 45 (2005) 529–535]. For the same edge radius of a tool, the higher the friction coefficient of the tool–workpiece, the thinner the minimum cutting thickness becomes. Therefore, it is believed that increasing the friction coefficient by a physical method would be effective to achieve thinner stable cutting. In this study, the possibility of reducing the minimum cutting thickness was investigated through changing the friction coefficient of a tool–workpiece. The vibration cutting method is applied to increase the friction coefficient. Experimental results show that the cutting technology is efficient for increasing the friction coefficient and decreasing the minimum cutting thickness. The minimum cutting thickness was reduced by about 0.02–0.04 μm depending on materials and vibration conditions.     

自动切管机切割路径的运动学分析

切管机是管材加工及应用行业的专用加工设备,管材的管-板相贯的几何特点给切割一次成形带来了很大的困难,基于一次成形的考虑,提出了管-板相贯求交的一个通用算法,根据这一算法设计的数控切管机成功地实现了这类坡口一次数控切割成形,并通过一个较为典型的例子作一详细的论述.     

具有斜切功能的钢管火焰切割机

管道施工中的钢管切割不能采用钢管旋转的方式,而只能采用割炬绕钢管旋转的方式.在目前的设备和技术水平条件下,依靠链条的爬管式钢管火焰切割机有明显的技术和经济优势.