Optimisation of machining fixture layout under multi-constraints

Fixture layout including locator layout and clamp layout plays a vital role in fixture performance. Current researches have been focused on fixtures for components with regular geometry, the results of which are not always applicable for components with complex geometry. This paper presents a methodology of fixture layout optimisation carried out in consideration of the repeatability, immobility and stability of fixturing. The locator layout is optimised based on the criteria of workpiece repeatability and location accuracy. The clamp layout optimisation offers a method to minimize the magnitude of the clamping force. The procedure of clamp optimisation is (1) to find the feasible clamping position in terms of the immobility requirement; (2) to get the best clamp among the feasible clamping positions under constraint of the stability. The optimal fixture layout is considered in a global range and is especially suitable for the workpiece with complex surfaces. A fixture layout design for the aerofoil of a turbine blade is analysed as an example, and the optimal fixture layout is demonstrated.     

计算机辅助组合夹具设计系统的研究与实现

组合夹具是解决小批量多品种、生产柔性化的有效手段,计算机辅助组合夹具设计是先进制造系统发展的必然要求.在现有夹具设计方法的基础上,建立计算机辅助组合夹具设计(CAMFD)系统的架构,并提出参数化的组合夹具元件建模技术以及基于粗糙集知识发现的组合夹具设计技术.并以槽系要素的组合夹具为实例证明了系统的实用性和有效性.     

基于机械对称性知识的夹具快速设计

对机械对称性知识体系进行简要总结,分析机械对称性知识在机械设计与工艺规划领域的应用。对机械对称性所包含的结构对称性-功能对称性-原理对称性作用机制进行研究,提出根据机械对称性知识来进行夹具快速设计的基本思想。建立基于对称性知识的夹具信息模型,提出在机械对称性知识作用下夹具快速设计的关键技术与体系结构。根据对称性原理,在对SolidWorks进行二次开发的基础上,开发了应用于汽车同步器制造的CAFD系统,实现了基于机械对称性知识的夹具快速设计,验证了系统的实用性与有效性。     

An investigation of the effectiveness of fixture layout optimization methods

Deriving the optimal layout of fixture elements is critical to minimizing the impact of fixture–workpiece deformation on machined feature error. Various optimization methods for solving this problem have been reported. Unfortunately no investigation has been executed to compare their relative performance. This paper presents the methodology and results of an extensive investigation into the relative effectiveness of the main elements of these competing methods. All methods were tested over a broad range of conditions. Performance measures that were tracked included solution quality, solution repeatability, and computation time. The results of this investigation show that the best overall performance is provided by optimization methods that use both the genetic algorithm and continuous interpolation for the distribution of boundary conditions.     

利用滚/滑-铰杆增力机构的双工位夹具设计与分析

设计两种利用铰杆增力机构的非线性气液复合传动双工位夹具。介绍其工作原理并对这两种夹具的夹紧效率及优缺点进行分析。夹具采用单缸双出杆活塞来实现双工位夹紧,中间部分由管道油路连接,具有结构简单紧凑、环境适应性强的优点。     

一种工业机器人多功能夹具

针对目前工业机器人通用夹具可靠性低、夹持精度不高、生产效率低等问题,设计了一种多功能夹具,该夹具由两爪部分和三爪部分组成,可以实现平面类及轴类零件的装夹,并且拆卸简单、定位精度高,空间利用率高,能够保证工业机器人的工作效率。     

基于快速原型的夹具设计

在机械加工中,夹具有着不可替代的作用,但其传统的设计方法,存在许多不足之处,将快速原型技术用于夹具的设计;介绍了现阶段夹具设计存在的缺陷,分析了快速原型技术用于夹具设计的合理性;并通过具体的成型过程与实例展示,突出快速原型技术用于夹具设计的优势。     

基于杆件可重构的角度效应增力夹具系统的设计

利用杆件可重构的设计理念,通过串联组合铰杆重构出不同的增力机构.介绍4种利用直径不同的2只气动肌腱与可重构Toggle机构进行组合创新设计的角度效应增力夹具系统,分析其工作原理,并给出相应的力学计算公式.该夹具系统可满足不同夹紧力及结构尺寸的要求,适应绿色化的发展趋势,具有比较广阔的应用前景.     

A novel approach to fixture layout optimization on maximizing dynamic machinability

In the aerospace industry, the reasonable layout of fixture can efficiently suppresses machining vibration of thin-walled aerospace structure during machining. Based on the analysis of typical structural components encountered in the aerospace industry, a general frame-structure workpiece with fixture constraints can be equivalent as Mindlin plates with simultaneous elastic edges and internal supports. On basis of the equivalent models, the powerful pb-2 Ritz method defined by the product of a two-dimensional polynomial and basic functions can be introduced to be taken as trial functions. Substituting displacement functions into energy functional and minimizing total energy by differentiation leads to eigenfrequency equations of the workpiece–fixture system. Consequently, a novel nonlinear programming problem based on the frequency sensitivity can be built to optimize the layout of fixture supports to maximize the fundamental nature frequency of the workpiece–fixture system. The feasibility of the proposed approach is validated by a machining case.     

发动机连杆清洗夹具方案的研究

针对某型号汽车发动机连杆清洗过程中装夹自动化程度不高的问题,根据连杆自身的结构特点,介绍3种可行的夹具方案。通过综合分析对比各方案的优缺点,最终选择灵活性强、结构简单、稳定性高的悬挂夹具。     

门五金件孔槽数控加工的夹具设计方法研究

针对门五金件孔槽数控加工时多次装夹、多工序、多工位以及加工精度差、效率低等问题,从门五金件孔槽的结构特点及数控加工原理出发,分析门五金件孔槽数控加工机床夹具设计要求,提出一种新的门五金件孔槽数控加工夹具设计方法。该夹具系统能够实现木门全自动定位夹紧,且一次装夹可完成门五金件孔槽数控加工。该方法提高了加工精度、生产效率,对实现门五金件孔槽数控加工的规模化具有重要意义。     

并联夹具机构灵巧性分析

针对汽车行业对制造系统以及包括夹具在内的所有部件的高模块化和灵活性的要求,提出一种具有高自配置性和灵活性的夹具系统。其中,安装在并联机构末端执行器上的夹具具有高刚度、高精度、可重构性,并且可以通过编程使其在工作空间中移动的特点。而并联机构作为自配置夹具系统的支持单元,在工作空间和动态特性方面具有一定的局限性。为了提高并联机构的综合工作性能,在工作空间中,分别以全局运动条件数和全局动态条件数作为运动灵巧性和动态灵巧性的评价标准。以工作空间体积、全局运动条件指标和全局动态条件指标为目标函数,对并联夹具机构进行优化,得到优化后的结构参数。     

组合夹具管理及辅助设计系统

夹具设计是生产准备过程的一个重要组成部分,组合夹具是FMS实现真正柔性的关键技术之一.组合夹具由于具有效率高、柔性好、可重复使用、成本低等优点而受到人们的重视.根据组合夹具的特点及某企业的实际需要,开发了组合夹具管理及辅助设计系统.系统包括组合夹具及其元件的库存管理,夹具设计信息录入、夹具检索、夹具组装、设计结果入库等夹具设计功能,定位误差计算和夹紧力计算等功能,建立了基于Pro/E的三维组合夹具元件图形库.最后介绍了系统的特点.     

深孔类零件的工装设计及刀具改进

针对深孔类零件的加工要求,分析工件的装夹和定位,同时给出其夹具的设计,并针对该零件的加工要求,从不同方面分析刀具选用,有效地解决了原加工方案的加工效率低、成本高等问题,最后提出了提升刀具性能的方法及检测环节注意事项。     

先进焊接工装夹具及其在机械装备制造业中的应用

随着先进焊接技术的发展和进步,焊接工艺在机械装备制造业中的应用越来越广泛。合理地使用焊接工装夹具是保障零部件焊接工艺质量的基本要素之一。因此,焊接工装夹具在制造业中获得了广阔的应用空间。近些年来,基于模块化、标准化思想的精密组合焊接夹具系统凭借其在技术和生产应用方面的优异特点,在大型机械装备制造业中获得了广泛的应用。对模块化组合焊接工装夹具系统以及先进的计算机辅助焊接工装夹具设计系统在欧美领先工程装备制造业中的应用做一概述。     

焊接夹具方案设计智能CAD系统的知识表达

提出了基于实例和知识的焊接夹具方案设计总体设计策略,建立了基于框架和规则的知识表示方法,并以V形定位器为例,研究了智能CAD系统中实例库的设计。     

发电机轴支撑架工装设计及加工工艺优化分析

某企业的发电机轴支撑架年产量达4万件/年,该零件空间位置精度要求较高,存在加工效率低、产品质量加工不稳定等问题。为改善这一状况,针对零件的工艺进行优化并自行设计一款夹具,一次装夹完成所有工序,从而提高生产效率和产品质量。实践证明:采用优化后的加工工艺,产品精度均达到图纸要求,且加工效率大大提升,对于同类产品的加工具有一定借鉴意义。     

Aspects of reconfigurable and flexible fixtures

The design and manufacture of fixtures and other dedicated tooling for positioning of workpieces are among the major cost drivers in product industrialization. This has spurred research and commercial interest towards other fixturing solutions like reconfigurable fixtures, with the ability to be changed, or “reconfigured”, to suit different parts and products. When reconfiguring, the product interface not only has to be moved but moved to a desired position and orientation. Several different approaches have been used to move and position these devices, all with their own advantages and disadvantages. This article presents different methods used to position and reconfigure flexible fixture devices using a parallel kinematic device as a case. Discussing the different ways to reconfigure a flexible device, the article aims to arrange the techniques according to their key features.     

Machining fixture layout optimization using the genetic algorithm

Dimensional and form accuracy of a workpiece are influenced by the fixture layout selected for the machining operation. Hence, optimization of fixture layout is a critical aspect of machining fixture design. This paper presents a fixture layout optimization technique that uses the genetic algorithm (GA) to find the fixture layout that minimizes the deformation of the machined surface due to clamping and machining forces over the entire tool path. The advantages of the GA-based method over previously reported non-linear programming methods for fixture layout optimization are discussed. Two GA-based fixture layout optimization approaches are implemented and compared by applying them to several two-dimensional example problems.     

整体构件电解装置的设计

整体构件结构特殊,强度高,体积小,大大简化了零件的装配,提高了发动机的推重比,广泛应用于航空航天等制造领域;但整体构件腔体结构复杂,材料硬度高,采用机械加工刀具的加工难度非常大,甚至刀具无法到达加工区域。而电解加工可一次成型,生产率高,特别适合于加工复杂腔体零件。针对整体构件的形状特点,对电解加工的外装置进行了设计,确保加工过程零件的绝缘、导电、装夹。通过对零件的试加工,针对电解加工过程出现的密封问题、腔体位置偏离问题进行探讨,在设计结构的基础上进行了方案的优化设计。实验证明:合理的工装能够满足整个零件加工过程的需求,从而避免机床的腐蚀,并最终保证零件成形的位置以及尺寸。