结构振动试验转接器的设计及安装问题

一些产品及其相关部件在作振动试验时，由于产品的外形或特殊要求不能直接安装在振动台面上，需要通过特别设计的转接器（夹具）来进行连接，这种夹具实际上是一种附加结构，它作为台面与试件之间的中介，如设置不当将影响振动试验结果的可靠性。本文通过对某事例的分析与研究，从试验频带、允许误差、跟随条件以及安装共振频率等方面阐明与讨论了相关夹具的特性、设计原则与安装等问题。     

一种简单的S参数去嵌入技术

介绍了在低成本夹具上，任意微带结构二端口网络S参数去嵌入的方法；该方法用于获取放大器模块的S参数，根据这些参数设计的C波段的放大器实测结果与仿真一致。     

薄壁钢管切割夹具设计

针对薄壁钢管加工过程中存在的装夹效率低、加工精度差等问题,设计一种从钢管内部夹紧、加工范围大、一次装夹可实现多次多段切割的新型夹具,分析夹具整体结构特点和受力情况,对于提高钢管切割效率、保证切割精度、优化工艺过程起到了积极作用。     

A functional approach for the formalization of the fixture design process

The design of machining fixtures is a highly complex process that relies on designer experience and his/her implicit knowledge to achieve a good design. In order to facilitate its automation by the development of a knowledge-based application, the explicit definition of the fixture design process and the knowledge involved is a prior and a fundamental task to undertake. Additionally, a fundamental and well-known engineering principle should be considered: the functional requirements and their associated constraints should be the first input to any design process. Considering these two main ideas, this paper presents the development undertaken to facilitate the automation of the fixture design process based on a functional approach.In this context, the MOKA methodology has been used to elicit fixtures knowledge. IDEF0 and UML have been used to represent the fixture design process. A methodology based on the function concept and aiming to formalize such design process is proposed. Fixture functional requirements have been defined and formalized. Functional fixtures elements have been used to create a functional design solution, the link of these elements with the functional requirements and with typical commercial fixture components has been defined via tables and rules mapping. And finally, a prototype knowledge-based application has been developed in order to make an initial validation of the proposed methodology.     

Efficient simplex computation for fixture layout design

Fixture, to hold an object by making multiple contacts, is a fundamental tool in manufacturing. A fixture layout is an arrangement of contacts on an object’s surface. Designing a fixture layout of an object can be reduced to computing the largest simplex and the resulting simplex is classified using the radius of the largest inscribed ball centered at the origin. We present three different algorithms to compute such a simplex: a simple randomized algorithm, an interchange algorithm, and a branch-and-bound algorithm. We also present methods to combine different algorithms to improve the performance and highlight their performance on complex 3D models consisting of thousands of triangles. Our randomized algorithm computes a feasible fixture layout in linear time and is well-suited for real-time applications. The interchange algorithm computes an optimal simplex in linear time such that no single vertex can be changed to enlarge the simplex, and it provides a practical method for complex 3D objects. The branch-and-bound algorithm computes the largest simplex by using lower and upper bounds on the radius of the inscribed ball, by which the computation time is reduced by a factor of five in comparison with the brute-force search.     

基于变动几何的机床夹具误差预测

将变动几何约束网络应用于夹具误差预测.提出一种针对夹具的变动几何约束网络的建立方法;给出公差向变动几何旋量矩阵的映射关系,以及旋量参数约束式,依据约束式采用极值法计算夹具误差.最后用实例验证方法的有效性.     

Modeling and analysis of workpiece stability based on the linear programming method

After being located on a machine bed, a workpiece will be subject to gravity and cutting forces during the machining operation. In order to keep the locating precision as well as the production safety, it is necessary to maintain the workpiece stability. In this paper, a linear programming method is proposed for stability analysis of the workpiece. Based on the linear approximation of the friction cone, a quantitative criterion is established to verify the workpiece stability in association with the rationality of the clamping sequence, magnitude of clamping forces and clamping placement. This criterion allows designers to plan reasonably the clamping sequence, magnitude of clamping forces as well as clamping placement. Compared with existing methods, the main advantage of this approach lies in that the sophisticated computing of contact forces between fixture elements and the workpiece is avoided. In this work, both friction and frictionless cases can be easily taken into account in stability analysis. Mathematical formulations of the method are given and some numerical tests are finally demonstrated to validate the proposed method.     

MTConnect compliant monitoring for finishing assembly interfaces of large-scale components: A vertical tail section application

Monitoring is a significant issue for finishing the assembly interfaces of large-scale components before final assembly. Acquisition and supervision of the pivotal data is essential to ensure the security and reliability for machining the large and complicated components with high-value. This process is generally cumbersome and time-consuming because there are various types of data coming from different components and sensors. The problem becomes more serious when considering the whole shop floor. Recently, MTConnect has been proven to be an effective method to realize standardized data collection and monitoring process. However, MTConnect is still under development and cannot cover the whole finishing process such as on-machining measuring (OMM) and fixturing. To address the issue, an MTConnect compliant method with extended data models is proposed in this paper to implement a standardized monitoring system. Firstly, a finishing system for the assembly interfaces is introduced, including the framework, workflow and key procedures and data. Then extended MTConnect data models are proposed to represent the finishing system including on-machine touch-trigger probe and sensor-based intelligent fixturing related information. Based on the extended MTConnect data models, a web-based monitoring system is developed for data collection and monitoring by combining an MTConnect agent and an OPC adapter. The proposed approach is validated by collecting and monitoring the key process data using an airplane vertical tail as an application. The advantages of using MTConnect would be more significant when extended to the entire factory and implemented in cloud manufacturing in the future.     

一种铅锭搬运机器人真空吸附夹具的设计与分析

设计了一种基于真空系统原理的工业机器人真空吸附夹具,用于铅锭搬运,取得了良好的效果。介绍了真空吸附夹具的结构组成。阐述了真空回路和真空发生器的工作原理及技术特点。对真空吸盘、真空发生器和电磁阀等主要组成元器件进行计算和选型,并设计了夹具支架,运用Solidworks软件对夹具支架进行了有限元分析。     

汽车主模型ABS轻量化后地板检测模块的设计制造研究

后地板检测模块在燃油车与电动车内饰切换时拆卸频繁,为操作方便,需将后地板模块轻量化。而传统铝制模块密度大,质量易超标,因此,有必要采用轻量化材料如丙烯腈-丁二烯-苯乙烯共聚物(ABS)塑料来制备后地板检测模块。ABS材料密度小,成本低,但硬度低,强度弱,表面光洁度差。为解决这些问题,采用铝制骨架与ABS模块喷漆相结合的设计方式,通过设计阶段的强度计算,确定了质量轻、强度与表面质量均满足要求的后地板检测模块的设计方法。