线切割加工锥度时刀位点的修正

线切割加工廓形精度要求较高的锥度刀具时，应采用偏摆钼丝法，并要对走丝轨迹进行修正。文章介绍了刀位点的修正方法导出了相关公式，给出了在线切割CAD／CAM软件中实现修正的步骤。     

大螺旋角齿条刀的线切割加工工艺

齿条刀是典型的多角度刀具，在平置加工时其角度参数超出了线切割机床上下异形角度加工极限。通过改变加工时的安装角度和合理编制加工程序，可取得线切割加工齿条刀的良好效果。本文举出加工实例，说明了具体实施方法及加工要点。     

采用接刀方法线切割加工大长度齿条刀具

线切割加工是制造齿条刀具的关键工序 ,齿条刀具的全部齿形参数———齿距、齿厚、全齿高、螺旋角、后角、齿形角等均通过该工序一次成形。由于我厂所用ＣＨＡＲＭＩＬＬＥＳ 2 90型线切割机床的行程限制 ,只能加工长度≤ 35 0ｍｍ的齿条刀具 ,而用户订货的齿条刀具最大长度达 4 80ｍｍ ,为了利用现有设备加工出超行程的大长度齿条刀具 ,只能采用接刀方法进行加工。接刀加工是将一把齿条刀具分为两段分别加工。线切割机床的上、下喷嘴是按程序编制的加工轨迹移动 ,喷嘴周围有较大空间 ,因此可根据程序的加工方向将齿条刀具的一端固定在加工…     

如何在线切割机床上实现接刀加工

各种型号的线切割机床,都有自己的走刀范围,被切割件的切割部位尺寸如超过了这个范围,则不能加工。通过实践,我们摸索出了一套接刀的加工方法,成功地解决了上述问题,使机床扩大了加工范围。现将这一方法介绍如下。     

曲面笔式加工刀位点曲线的实时拟合

针对曲面高速高精度加工问题,给出一种刀位点轨迹实时生成算法。该方法的实现包括曲面上离散刀触点的生成和基于三次非均匀B样条曲线的刀位点轨迹实时高精度拟合两部分。第一部分,由导动曲线和刀触点轨迹的运动学关系,通过计算导动曲线参数,间接得到投影在曲面上的离散刀触点;第二部分,通过合理参数化、构建模长因子等实现刀位点参数曲线的分段实时拟合。仿真实例表明该算法简单易于编程,曲线拟合精度高,适用于自由曲面笔式加工中刀具路径计算与生成,从而满足复杂曲面高性能数控加工需求。     

线切割中加工不良原因分析与排除

线切割中加工不良现象很多,高加工精度和效率是追求的最终目标,斜度加工是加工中的难点。本文针对加工精度不良现象,从工艺方案、加工材料、加工参数、电极丝、工作液和走丝系统6个方面进行了分析,从高速走丝和低速走丝2种不同机床对线切割速度不良进行了阐述,从机床、工件材质和电极丝3个方面的原因对斜度加工不良进行了研究。详细地介绍了产生这些不良现象的原因,并提出了有效的克服办法,以期对从事线切割加工领域的相关人员起到借鉴作用。     

线切割加工成形车刀

用线切割加工棱体成形车刀，可直接利用工件的廓形进行编程，无须进行修正计算，刀具廓形一次加工成形，简介如下。     

提高线切割加工精度的方法

电火花切割是一种直线电极的展成加工方法,因为它使模具(尤其是复杂模具)加工工序简化、生产周期缩短而倍受人们欢迎,被广泛地应用于模具制造行业。但由于我国快走丝线切割机床的结构设计、制造精度以及加工工艺指标等方面和国外同类机床相比还有差距,所以在加工精度要求较高的模具时,我国的一般线切割机床不能满足精密加工     

数控车床、铣床刀位点的选择

介绍了数控车床、铣床刀位点的选择方法和原则。     

宝塔件的线切割加工

介绍了一种宝塔件的加工工艺,同时对其使用的夹具作了主要分析和研究。     

An experimental investigation of oblique cutting mechanics

In this study, an experimental investigation of oblique cutting process is presented for titanium alloy Ti-6Al-4V, AISI 4340, and Al 7075. Important process parameters such as shear angle, friction angle, shear stress, and chip flow angle are analyzed. Transformation of the data from the orthogonal cutting test results to oblique cutting process is applied, and the results are compared with actual oblique cutting tests. Effects of hone radius on cutting forces and flank contact length are also investigated. It is observed that the shear angle, friction angle, and shear stress in oblique cutting have the same trend with the ones obtained from the orthogonal cutting tests. The transformed oblique force coefficients from orthogonal tests have about 10% discrepancy in the feed and tangential directions. For the chip flow angle, the predictions based on kinematic and force balance results yield better results than Stabler's chip flow law. Finally, it is shown that the method of oblique transformation applied on the orthogonal cutting data yields more accurate results using the predicted chip flow angles compared to the ones obtained by the Stabler's rule.     

Modeling and experimental verification of chip flow deviation in oblique cutting

The reasons for chip deviation from the orthogonal direction in machining are (i) restricted cutting effect, (ii) nonzero inclination angle, and (iii) tool-nose radius. The present article has incorporated the concept of effective inclination angle in the models for predicting chip flow direction in oblique cutting. Model 1 takes into account the role of the effective principal cutting edge angle (as point function) and the concept of effective inclination angle has been incorporated in the model. Model 2 addresses the same roles but determined as path functions. Models 1 and 2 do not address the variation in the chip load along the width of cut. This has been addressed in Model 3 along with effective inclination angle. The models have been validated against the experimental data while turning two different medium carbon steels with uncoated carbide inserts over a wide domain of depth of cut, feed, cutting velocity, nose radius, rake angle, inclination angle and principal cutting edge angle. The major contribution of this work is the introduction of effective inclination angle along the effective cutting edge.     

大角度斜面激光切割加工的工艺研究

分析了大角度斜面激光切割的可行性和激光切割加工工艺。结果表明：当激光功率为1260W,光斑直径为0.18mm,以0.08MPa的氧气作用为辅助气体,切割速度为1.4m/min,使喷嘴离工件的距离保持在0.5mm-0.8mm之间并选取适当的CNC程序直线插补步长,可以实现6mm厚的15Cr2Mo1钢大角度斜面的激光切割,切口质量良好。     

Fundamental modeling for oblique cutting by thermo-elastic-plastic FEM

In this paper, the finite deformation theory and updated Lagrangian formulation were used to describe the oblique cutting process. Either the tool geometrical location condition or the strain energy density constant was combined with the twin node processing method to act as the chip separation criterion. An equation of three-dimensional tool face geometrical limitation was first established to inspect and correct the relation between the chip node and the tool face. And, a three-dimensional finite-difference heat transfer equation was derived. Based on this approach, tool advancement was achieved in displacement increment step by step from the initial tool contact with the workpiece till the formation of steady cutting force. In this case, a large deformation thermo-elastic–plastic finite element model for oblique cutting was established. The mild steel was used as the workpiece, the tool was P20 and the cutting speed was 274.8 mm/s in this article. The chip deformation process and temperature effect on the strain energy density, chip flow angle, cutting force and specific cutting energy were studied first. Finally, the integrity on machined workpiece surface was explored from the variation of residual stresses and temperature distribution on it after cutting. During the chip deformation process, the chip flow angle obtained by this simulation result was approximately equal to the tool inclination angle, which confirmed with the geometrical requirement of Stabler’s criterion. Besides, the simulated specific cutting energy was compared with the experimental specific cutting energy value, the result of which was within acceptable range. It is obvious from the above findings that the model presented in this paper is consistent with the geometrical and mechanical requirements, which verifies the proposed model is acceptable.     

零件斜面交线位置的3种精确测量方法

以冲头零件为例,论述了准确确定斜面交线位置的3种确定(测量)方法:设计阶段和试生产期间的仪器测量;检验人员在大批量生产中能迅速反馈测量结果的比较测量;用于加工者加工中不受限制的间接测量.     

Thermoviscoplastic modelling of oblique cutting: forces and chip flow predictions

A modelling of oblique cutting for viscoplastic materials is presented. The thermomechanical properties and the inertia effects are accounted for to describe the material flow in the primary shear zone. At the tool–chip interface, a temperature-dependent friction law is introduced to take account of the extreme conditions of pressure, velocities and temperature encountered during machining. The chip flow angle is calculated by assuming that the friction force is collinear to the chip flow direction on the tool rake face. Due to the temperature dependence of the friction law at the tool–chip interface, the chip flow angle predicted by the model, is affected by the cutting speed, the undeformed chip thickness, the normal rake angle, the edge inclination angle and the thermomechanical behavior of the work material. This dependence and the trends predicted by the present approach are confirmed by experimental observations. Effects of cutting conditions on the cutting forces are also presented and compared to experiments.     

上下异形零件的线切割加工

通过实例,介绍上、下异形零件的线切割加工工艺及编程具备的必要条件。     

线切割加工中电极丝精确定位方法

介绍线切割加工中精确定位电极丝的两种方法。在定位过程中应保证最后两次找正位置的坐标值相同或相近