模具3D型腔粗铣加工中刀具优化选择研究

在含岛和复杂曲面的模具3D型腔粗铣加工过程中,在尽可能提高加工效率的目标下,选择合适的刀具是关键。根据型腔的实体模型,分析并提取了影响刀具选择的几何约束,建立了刀具优化选择的数学模型,开发了基于定步长的切削层优化合并算法,确定了各组合层所使用的刀具直径,实现了对NC编程人员的计算机辅助刀具选择,实例验证了该方法的有效性。     

模具型腔数控粗铣工艺分析研究

进行了模具型腔数控铣削加工工艺分析研究。介绍了数控铣削刀具与切削用量。对模具型腔加工特征进行详细分析,基于UGNX软件确定了对应于各种特征的加工方法和刀具。提出了模具型腔粗铣加工刀具简易组合方法,进行了走刀方式分析比较。     

模具型腔切削加工技术

模具型腔加工技术水平对模具质量影响非常大，如何更好更高效加工模具型腔?本文将从以下几个方面进行阐述。     

型腔模具的加工工艺研究

论述了型腔模具的主要材料和结构特点,分析了高速铣削加工、电火花加工、快速成型等型腔模具的加工方法,同时对型腔模具的加工刀具,以及两款典型的加工设备进行了介绍。     

型腔模具加工的工艺设计

对型腔模具加工的工艺性进行了分析,并以斜齿轮加工为例,就工具电极、定位板的结构设计以及斜齿轮具体的加工过程等方面进行了阐述。实践结果表明,合理的加工工艺可以在很大程度上提高工件的加工质量和生产效率,提高企业的经济效益。     

型腔模具加工工艺设计

基于模具镶件加工实例,结合HSM铣削加工与EDM放电加工在模具型腔加工中的应用特点,阐述了应用HSM与EDM加工模具型腔工艺设计方法,剖析了工艺设计的关键技术,实际生产结果表明:合理运用HSM铣削加工与EDM放电加工可以提高加工质量和生产率。     

模具型腔的高速数控加工

通过三维建模、生成刀具轨迹、轨迹仿真、后置设置、生成G代码,经CF卡传入数控机床,完成一典型模具型腔零件的数控加工。整个加工流程贯穿高速加工思想。经检验,《CAXA制造工程师》软件可完成较复杂零件的高速数控加工,相对国外同类软件具有物美价廉的优势,在数控加工领域具有一定的应用前景。     

NC Assembly在模具型腔加工中的应用

在模具加工刀路编制时,很多用户会将C reo设计模型导入M aster C A M、C im atron等软件中进行加工刀路编制,往往引起很多数据转换的问题。文中采用C reo软件的一个加工模块N C A ssem bly进行无缝衔接,完成刀路编制。并结合一个实例进行了工艺分析,进而实现粗加工和精加工。     

面向刀具序列的模具型腔高效加工策略

为了实现模具型腔的高效加工,提出了一种面向刀具序列的模具型腔高效加工策略。在该策略中,刀具选用圆弧角铣刀和球头刀。按照优先选用圆弧角铣刀和大直径刀具的原则,根据建立的最大可行刀具数字化加工几何模型,确定了刀具序列中每把刀所对应的加工区域和实际加工中每把刀只切除所对应的加工区域。应用该策略可以避免加工特征的识别,同时克服了高速加工刀具刚性差的缺点。验证了加工策略,证明该加工策略对模具型腔的高效加工具有较高的实用价值。     

An algorithm for precise machining area computation in rough machining of complex 3D pocket

The layer-by-layer machining approach is extensively used in both pocket and surface roughing process. Traditionally, the machining area is bounded by the intersecting curve of the part model and slicing plane. However, for the complex 3D pocket composed of inclined faces and groove feature, part of the area may be inaccessible for the cutting tool, resulting in interferences in the rough machining process. To tackle the problem, a novel algorithm that can avoid interferences is proposed. In this method, some basic terms such as static machining area (SMA), fringe edge (FE), and area side property (ASP) are described at first. The SMA can be generated through splitting the original machining area by the projection lines of FEs. Based on the ASP, the projection lines and original boundaries can be divided into two types: boundary line (BL) and non-BL. The boundaries of SMA can be constructed by linking BLs based on the accessibility analysis method. At last, two case studies are given to verify the feasibility and effectiveness of the proposed approach. The results show that the proposed algorithm can eliminate the interferences in the machining process.     

Application of fuzzy and rough sets theory in the optimization of machining parameters for mold milling operations

NC milling operation has become one of the main means of mold manufacturing in recent years, and the determination of milling conditions is important to assure the quality and minimize the costs of molds. This paper first constructs an optimization model of machining parameters for mold milling operations, focusing on minimizing the production costs. Then, based on the properties of the machining parameters database, it also proposes an extended model of fuzzy and rough sets theory for incomplete information systems, including incomplete continuous attribute values, and applies the model to rules learning from the machining database. Thus, by rule reasoning, the feasible solution space of optimization model can be easily established. At last, an example is presented to detail the optimization of machining parameters in the case of the cavity milling of an injection plastic mold.     

Time modeling in high-speed machining of mold pocket

Numerical control milling (NCM) at high speed is the most used machining process in the manufacture of molds because it offers high productivity and workpiece surface quality. The aim of this work is to establish a methodology to evaluate the rough machining time, during high speed milling. In pocket machining, a 2.5D milling has been considered. The proposed approach considers the roughing cutting time as the ratio of the pocket volume by the removed material rate. The pocket is divided into volumes distributed according to the real radial depth. Since the radial depth varies during machining, the removed material rate is not constant. In this paper, an experimental study is carried out to validate models of machining time calculation. The obtained results show that the proposed method offers fast and easy calculation of the machining time of pocket roughing.     

RCF65型铣刀几何参数对铣削加工铝合金的影响

使用有限元软件Advant Edge建立有限元模型,结合文献验证所建有限元模型的准确性后,采用正交实验法分析了左、右螺旋角、前角及后角对硬质合金RCF65型铣刀加工6061-T6铝合金时的温度、功率和切削力的影响。结果表明,在给定的参数变化范围内,对切削力和功率的影响左、右螺旋角后角前角;对温度的影响前角后角左、右螺旋角。综合考虑温度、功率和切削力,RCF65型铣刀右螺旋角选25°、左螺旋角选30°、前角选12°、后角选14°时,刀具的铣削性能最佳。     

板式换热器模具高速铣削工艺分析

根据板式换热器模具的特点,全面分析了高速铣削过程,对高速铣削加工板式换热器模具从工艺方案拟定、NURBS插补和铣削路径优化方面进行了分析,描述了高速加工板式换热器模具的可实现性.对推进高速铣削技术在工业企业的深入应用以及发展我国制造业总体水平有着十分重要的意义.     

Chatter prediction based on frequency domain solution in CNC pocket milling

Chatter has been a problem in CNC machining process especially during pocket milling process using an end mill with low stiffness. Since an iterative time-domain chatter solution consumes a computing time along tool paths, a fast chatter prediction algorithm for pocket milling process is required by machine shop-floor for detecting chatter prior to real machining process. This paper proposes the systematic solution based on integration of a stability law in frequency domain with geometric information of material removal for a given set of tool paths. The change of immersion angle and spindle speed determines the variation of the stable cutting depth along cornering cut path. This proposed solution transforms the milling stability theory toward the practical methodology for the stability prediction over the NC pocket milling.     

Solving 3D geometric constraints for closed-loop assemblies

In the design activity, part geometry is assembled to create an assembly model. The number of parts may range from a few tens to a few million and typically the relationship among them constructs closed-loops with under-constrained states. In this paper, a 3D constraint solving method is proposed for closed-loop assemblies with under-constrained states. The proposed constraint solving method determines assembly configurations by applying the following procedures: 1. Transform the geometric mating relations into the kinematic joint relations, 2. Convert the closed-chain kinematic assembly to an open kinematic assembly by removing a joint, 3. Compute an open kinematic configuration by solving the open kinematic problem and 4. Obtain the closed-loop kinematic configuration by pasting the ‘cut’ links of the open assembly. The cut and paste operations minimise the number of constraint variables that have to be solved simultaneously. Thus, it can maximise the efficiency and robustness of an assembly constraint solver. The proposed constraint solving method combines the simplicity of a sequential solving approach with the universality of a simultaneous solving approach.     

三维运动分析中的运动-立体双匹配约束

为保证在基于点特征的三维运动分析中运动物体不同时刻任意物方特征点的对应,对该过程中存在的图像运动-立体匹配问题进行了研究。提出了运动-立体匹配相结合,分阶段的运动-立体双匹配约束的方法。即采用松弛法点特征匹配算法完成图像间的基本匹配,通过运动-立体双匹配约束完成运动物体特征点的对应。给出了一组真实的实验数据,结果表明:该算法总的正确率达76.5%,基本达到了三维运动物体定位跟踪中特征点对应的要求。     

3D打印钛合金结构件铣削加工技术

1引言钛合金具有密度低、比强度高、屈强比高、耐腐蚀及高温力学性能优异等特点,在航空、航天、船舶、汽车等行业的应用越来越多,在关键零部件中的材料占比也越来越高。但由于钛合金材料本身的性能特点,采用“锻造、铸造+机械加工”等传统技术制造复杂钛合金结构件时,存在制造工艺复杂、加工工序多、生产周期长、材料去除率高和制造成本高等缺点,制约了钛合金结构件在先进工业及国防装备中的应用。     

Selection of optimal cutting conditions for pocket milling using genetic algorithm

Pocket milling is the most known machining operation in the domains of aerospace, die, and mold manufacturing. In the present work, GA-OptMill, a genetic algorithm (GA)-based optimization system for the minimization of pocket milling time, is developed. A wide range of cutting conditions, spindle speed, feed rate, and axial and radial depth of cut, are processed and optimized while respecting the important constraints during high-speed milling. Operational constraints of the machine tool system, such as spindle speed and feed limits, available spindle power and torque, acceptable limits of bending stress and deflection of the cutting tool, and clamping load limits of the workpiece system, are respected. Chatter vibration limits due to the dynamic interaction between cutting tool and workpiece are also embedded in the developed GA-OptMill system. Enhanced capabilities of the system in terms of encoded GA design variables and operators, targeted cutting conditions, and constraints are demonstrated for different pocket sizes. The automatically identified optimal cutting conditions are also verified experimentally. The developed optimization system is very appealing for industrial implementation to automate the selection of optimal cutting conditions to achieve high productivity.