大尺寸薄壁铸件切削加工组合机床设计

对纺织机中墙板零件的特点进行了分析,制定了大尺寸面薄壁型墙板组合机床加工的定位夹紧方案;设计中扩铰复合刀的使用简化了加工工艺,提高了生产率且使得组合机床的布置更紧凑;加工中,采用了移动工位和固定工位相结合的方式,合理安排了墙板零件切削时序,解决了大尺寸面薄壁件铣、镗、扩、铰、钻多种切削类型组合加工的难题,提高了墙板的制造精度。     

Optimum orientation of a torus milling cutter: Method to balance the transversal cutting force

In this paper, a new method for tool positioning in milling on torus cutters with round inserts is presented. A new criterion associated with balancing of the transversal cutting force is used to compute a tool orientation. The considered tool inclination is towards the back of the tool. In this case, all inserts work simultaneously and generate a continuous cutting phenomenon. Each of the inserts produces a transversal cutting force; some being positive while others are negative. A small tool axis inclination angle leads to balancing the transversal cutting force exerted on the tool and then reducing deflection and vibrations in milling operations. Firstly, this approach to the dynamic aspects relating to cutting forces in the milling process is significant for mould and die manufacturing since it allows polishing time to be reduced. In addition, as vibrations are reduced, enhanced surface quality can be obtained directly on free-form surfaces such as aeronautic fittings.     

利用大进给量铣削提升模具制造生产率的研究

大进给量统削(High Feed Cutting/HFC)工艺是一种以整个铁刀直径用全切削(α_e=D)的方式,同时采用较小的切削深度(即背吃刀量α_p)和很高的进给速度进行切削的高效切削工艺,有很高的材料切除率。其目的是显著缩短粗加工或半精加工的时间,因此,原则上大进给量铣削(HFC)是属于高效铣削(HPC)工艺的范围。常规的高效铣削(HPC)工艺是一种通过高的吃刀量(α_p,α_e)、高的进给速度(v_f)和切削速度(v_c)实现高材料切除率的切削工艺。而大进给量铣削(HFC)工艺,顾名思义,显然是专注于通过很高的进给速度实现工件多余材料去除效率,进而提高模具制造生产率的一种制造工艺。实现这种大进给量铣削工艺需要有特殊的刀具,为此,众多刀具供应商开发了具有能实现大进给量铣削的几何形状的刀具,以达到提高生产率的目的,其原理就是通过减小刀具主偏角进而增大刀具切削刃与工件接触长度来实现的。     

Tool path generation and tolerance analysis for free-form surfaces

This paper focuses on developing algorithms that generate tool paths for free-form surfaces based on the accuracy of a desired manufactured part. A manufacturing part is represented by mathematical curves and surfaces. Using the mathematical representation of the manufacturing part, we generate reliable and near-optimal tool paths as well as cutter location data file for post-processing. This algorithm includes two components. First is the forward-step function that determines the maximum distance, called forward step, between two cutter contact (CC) points with a given tolerance. This function is independent of the surface type and is applicable to all continuous parametric surfaces that are twice differentiable. The second component is the side step function which determines the maximum distance, called side step, between two adjacent tool paths with a given scallop height. This algorithm reduces manufacturing and computing time as well as the CC points while keeping the given tolerance and scallop height in the tool paths. Several parts, for which the CC points are generated using the proposed algorithm, are machined using a three-axes milling machine. As part of the validation process, the tool paths generated during machining are analyzed to compare the machined part and the desired part.     

Stud welding within sheet metal working tools

Sheet metal parts often have to be connected by fasteners. Within conventional process chains for the production of sheet metal parts, fasteners like bolts are mostly welded individually after the forming process and outside the working tool. This spatial separation of production steps requires complex handling operations and has negative impact upon the positioning accuracy of the fasteners. Every executable manufacturing step inside the sheet metal working tool shortens the process chain significantly. Furthermore, using a combined process the precision of position and orientation of fasteners improves. The challenges of integrating the welding process into the sheet metal working tool are some appropriate feeding technique, handling the emissions and associated pollutions of the tool as well as creating a dependable monitoring-system for the welding-process. Within the scope of a research project, a reliable technology for the integration of capacitor discharge (CD) stud welding with tip ignition was developed and tested. It complements existing solutions for integrated resistance welding processes. Due to its high-speed capability, low insertion of energy and only needed one-sided accessibility, this technique is particularly suitable for the integration in sheet metal working tools. A newly developed exhaustion-system is installed and tested for the first time by the CD arc stud welding process. The new technology produced top quality welding results along with high process stability and robustness in long-term tests.     

The form error prediction in side wall machining considering tool deflection

In this research, an effective method for the form error prediction in side wall machining with a flat end mill is suggested. The form error is predicted directly from the tool deflection without surface generation by cutting edge locus with time simulation. The developed model can predict the surface form error accurately about 300 times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacturing. This study contributes to real time surface shape estimation and cutting process planning for the improvement of form accuracy.     

Productivity enhancement in dies and molds manufacturing by the use of C continuous tool path

The challenge of die and mold milling is to achieve the specified dimensional and geometrical accuracy, and improve the surface roughness, in order to minimize polishing operations, still necessary to meet the tight tolerances required by the automotive industry and the plastic injection sector. The present study investigates the multi-axis milling of a specific mold steel grade Super Plast ® 300* (SP300) [1], by a ball nose carbide tool coated with Ti(CN). Surface finish analysis given by 3D measurements and data processing techniques shows that micro-geometrical defects generated by C¹ continuous tool path are definitely less serious than those obtained by classical tool paths driven via linear interpolation. Also, polishing time saving is more than 30%. Thus, a substantial productivity enhancement is achieved in dies and molds manufacturing.     

连杆零件的双圆柱定位钻模

介绍一种加工连杆零件孔的双圆柱钻模的工作原理与实施方式,并对钻模进行了可行性分析。该钻模具有结构简单、制造工艺性好、布置灵活、调整方便、生产效率高和实用性强等特点。依据双圆柱的定位原理,可设计出铣削和磨削连杆零件端面的夹具,能有效地避免零件加工中刀具与夹紧元件之间的干涉问题。     

Concave edge-based part decomposition for hybrid rapid prototyping

As one of the solutions to the limitations of the current layered manufacturing, hybrid rapid prototyping systems that perform both machining and deposition are being introduced. In the hybrid rapid prototyping, a part of a complicated shape is realized by adding layers of a simpler shape, each of which is obtained by machining a sheet of constant thickness from its top and bottom surfaces. Thus it is desired to decompose a given part into the minimum number of layers while guaranteeing each layer to be fabricated from the given sheets using a 3-axis milling machine. To satisfy these requirements, a concave edge-based approach is proposed to decompose a part into layers by considering the tool accessibility, the total number of layers, and the allowable sheet thickness. In this approach, for a given build-up direction, the undercut edges, which cause a part to be inaccessible by a tool, are extracted and classified into two types and eliminated in two decomposition steps.     

用CATIA实现割缝筛管的数控铣削仿真

石油割缝筛管是油田采油防砂常用的工具。其上面的缝一般用铣削的方法加工而成。数控铣削仿真是对铣削加工的动态模拟方法。论文用CATIA软件,对石油割缝筛管进行数控铣削仿真。其基本思想为,根据筛管尺寸图纸,画出筛管三维图和工程图;对铣削的要素进行具体设置;对铣削加工进行加工路线仿真和加工过程仿真。采用这种方法,我们可在屏幕上观察到连续的、逼真的加工过程,可以部分或者完全取消试切环节。     

基于EdgeCAM的型材数控铣快速编程技术研究

为了编制型材铣床的数控程序,基于EdgeCAM软件平台,选择VB.NET为开发工具并结合PCI和PDI等二次开发语言开发了快速编程系统。提出了型材数控铣工艺规划,论述了编程操作构建和后置处理等关键技术,并以典型零件的数控编程实例证明了方法的有效性,实现了型材铣床程序的智能化和快速化生成,并在生产企业得到实际应用与推广。     

复合涂层刀具加工RuT500的铣削力研究及参数优化

为探究和改善蠕墨铸铁RuT500的铣削力，基于单因素试验，选用TiAlN/AlCrN、TiCN/Al₂O₃复合涂层硬质合金刀具对RuT500进行铣削加工，结合响应面探究涂层和铣削参数对RuT500铣削力的影响规律，并进行了铣削参数优化。结果表明：相比于TiAlN/AlCrN复合涂层硬质合金刀具，TiCN/Al₂O₃复合涂层硬质合金刀具铣削RuT500时会产生更大的铣削力；对蠕墨铸铁铣削力影响最显著的因素是背吃刀量，其次是进给量，铣削速度对蠕墨铸铁铣削力的影响程度相对较少；铣削参数交互作用对铣削力的影响具有一定的显著性；取较大的背吃刀量a_p、适当的进给量f和较大的铣削速度v_c时，可以获得较低的铣削力F和良好的加工效率。     

内旋包络法数控螺杆铣床的关键技术研究

介绍笔者研制的一种新型数控螺杆铣床,采用标准不重磨刀片构成的铣刀盘,通过内旋包络法成形机理实现螺杆螺旋面的铣削加工,降低了通常成形铣削法对刀具刃形的要求,具有加工效率高、通用性好、刀具成本低的特点。文章主要介绍螺杆螺旋面包络成形机理、刀具中心坐标的计算、机床总体机械结构组成以及包络点的优化计算等相关技术。     

A three-dimensional analytical cutting force model for micro end milling operation

In the present day manufacturing arena one of the most important fields of interest lies in the manufacturing of miniaturized components. End milling with fine-grained carbide micro end mills could be an efficient and economical means for medium and small lot production of micro components. Analysis of the cutting force in micro end milling plays a vital role in characterizing the cutting process, in estimating the tool life and in optimizing the process. A new approach to analytical three-dimensional cutting force modeling has been introduced in this paper. The model determines the theoretical chip area at any specific angular position of the tool cutting edge by considering the geometry of the path of the cutting edge and relates this with tangential cutting force. A greater proportion of the helix face of the cutter participating in the cutting process differs the cutting force profile in micro end milling operations a bit from that in conventional end milling operations. This is because of the reason that the depth-of-cut to tool diameter ratio is much higher in micro end milling than the conventional one. The analytical cutting force expressions developed in this model have been simulated for a set of cutting conditions and are found to be well in harmony with experimental results.     

Efficient Tool Paths and Part Orientation for Face Milling

High speed machining is pushing the limits of feeds and speeds. A different approach for high throughput is described here. The focus is on the maximum feed that can be obtained for a segment; the feed rate losses due to sharp changes in tool path are minimized. The interdependency of individual axis drive speeds for a tool path segment are analyzed. There exists an optimum work angle relative to the axes that reduces losses and increases allowable feeds for particular segments, saving valuable cycle time and balancing feed drive loads. Face milling and roughing steps of end milling are the most attractive application areas.     

楔横轧模具数控铣削仿真加工研究

为了进一步提高楔横轧模具加工效率,提出了平底块式楔横轧模具铣削加工方法.介绍了平底块式楔横轧模具的总体结构、自动化编程、工艺规划和数控铣削仿真加工过程.在此基础上,实现了楔横轧模具高速铣削加工自动化编程和仿真加工,成功地仿真加工出平底块式楔横轧模具,生成的NC代码可直接用于实际生产中.从理论与仿真加工两方面证明了高速铣削加工平底块式楔横轧模具的高效性与可行性.     

Rotary ultrasonic-assisted milling of brittle materials

In order to improve the machining efficiency of ultrasonic milling,the easiest and most effective approach was started with the improvement of tool design.The main objective of this research was to utilize rotary ultrasonic machining (RUM’s) effectiveness in removing brittle materials to extend the applications of this independent,innovative manufacturing method (self-driving rotary ultrasonic machining),and to experimentally investigate its milling application on brittle materials.The designed tool was used in the conjunction with previously established RUM machine tools,and glass was selected as workpiece for experiments.The interrelationship between feed rate and depth of cut was discussed.By measuring the surface roughness of workpiece,the overall efficacy of utilizing RUM for milling was evaluated and presented.Ultrasonic assisted milling results in the reduction of milling resistance,which leads to a greater process rate.     

七轴并联机床加工汽轮机叶片技术及其工作空间干涉检查研究

并联机构自从1980年就应用于机器人作业,但是第一台并联机床却出现在14年以后.目前,研究并联机床在铣削加工能力方面的文献很少,文章着力于研究并联机床在铣削加工尤其是加工自由曲面的能力.文中描述了并联机床在铣削加工汽轮机叶片的实际应用. 研究了基于UG CAD/CAM铣削汽轮机叶片技术,并考虑了并联机床粗加工和半精加工的效率和精加工的精度控制.UG CAM产生的刀具轨迹文件,不能直接被并联机床数控系统识别,所以必须进行后置处理,文中提出了面向七轴并联机床的刀具轨迹后置处理技术,以生成并联机床CNC系统可读的加工代码.最后为了避免机床在加工中的干涉,针对七轴并联机床的特性,提出了快速工作空间检查算法.     

车铣加工UG-CAM制造技术研究与应用

应用TCL（Tool Command Language）开发了车铣加工中心BUNMOTECS192FT后处理模块,实现了该机床刀具中心点B轴随动的高级功能,利用UG～CAM数控编程技术,使用平头立铣刀,在车铣加工中心进行C、X、y轴联动,完成了零件曲面加工刀轨设计,解决了T型铣刀加工曲面环槽干涉问题,通过将平头立铣刀轴与曲面法线倾斜一定角度,避开平头立铣刀底齿中心切削,达到零件精度要求。     

硬质合金铣刀铣削性能研究

为了探讨国内外高端产品的质量水平,为国产硬质合金铣刀性能提升提供有益的指导,对比研究了国内外知名品牌铣刀的耐磨性和失效形式。采用端面中心对称干切削方式,按照实验室铣刀试验规范对相同材质的国产某品牌刀片和国外刀片在相同工艺条件下进行了铣削对比实验,工件材料为45#钢。实验结果表明:两种刀片高速干式铣削45#钢的寿命没有明显差异。国产刀片失效形式主要为磨损失效,其在45#钢的高速干式铣削上显示出了较高的耐磨性;国外刀片同时表现出崩刃失效。