几种典型尺寸链的计算

在机加工中,当工艺基准（工序、定位、测量等）与设计基准不重合时,工序基准就无法直接取用零件图上的设计尺寸,因此必须进行尺寸换算来确定其工序尺寸。对于要求进行表面处理的零件,在加工中要提前计算相关的工序尺寸。工艺尺寸链的构成,取决于工艺方案和具体的加工方法。文中根据尺寸链原理绘制了尺寸链图,根据尺寸链图例计算,求得所需要的尺寸。     

工序尺寸的假废品问题分析

机械加工中，常用调整法进行加工零件．在确定工序尺寸时，常常由于工艺上的原因，使得工艺基准(定位基准或测量基准)与设计基准不重合而需进行尺寸换算。这种换算往往会伴随着“假废品”问题的存在。因工艺基准与设计基准不重合而换算得到的工序尺寸(简称工序尺寸)，当加工超差时，可被同一尺寸链中的其他组成环所补偿，而使间接保证的设计尺寸仍然合格的零件，称为假废品。因此，在零件加工和检验过程中。为了简便、直观、迅速、准确地确定假废品区域和列别假废品，本文推荐方法如下。     

基于工艺过程的工序尺寸确定方法

在制定零件机械加工工艺过程中,当定位基准与设计基准不重合时,需要建立工艺尺寸链来计算工序尺寸。当零件同一方向上设计尺寸较多时,定位基准需要多次转换才能保证这些设计尺寸,其工序尺寸的确定就变得比较复杂。本文通过实例介绍一种基于工艺过程的工序尺寸的确定方法,用这种方法建立工艺尺寸链、确定工序尺寸非常实用,具有一定的推广价值。     

工序尺寸假废品区域的确定

机械加工中，工艺基准、测量基准与设计基准不重合，会出现工序“假废品”，采用极值法解尺寸链确定“假废品区”，对降低产品成本，保证加工精度有一定的实用价值。     

工序尺寸假废品区域的确定

机械加工中,工艺基准、测量基准与设计基准不重合,会出现工序"假废品",采用极值法解尺寸链确定"假废品区",对降低产品成本,保证加工精度有一定的实用价值。     

基于工艺过程的工序尺寸确定方法

在制订零件的机械加工工艺过程中,当其定位基准与设计基准不重合时,需要通过建立工艺尺寸链来计算工序尺寸。当零件同一方向上的设计尺寸较多时,需要多次转换定位基准才能保证这些设计尺寸,其工序尺寸的确定就变得比较复杂。本文通过实例介绍一种基于工艺过程的工序尺寸的确定方法,用这种方法建立工艺尺寸链、确定工序尺寸非常实用,具有一定的推广价值。     

《基准不重合的工艺尺寸换算和工序废品》

计算工序尺寸和标注工序尺寸偏差是制定机械加工工艺规程的主要工作之一。工序尺寸是指零件在加工过程中各工序所应保证的尺寸,工序尺寸的极限偏差是各工序尺寸所允许的变化极限值。在制订零件的机械加工工艺过程时,往往由于零件的结构形状,工件在夹具中或在机床工作台上安装定位方便,稳定,可靠,以及机械加工的方便性和可能性等方面的原因而使得某些设计尺寸的加工在工序中不能选用该尺寸的设计基准做为定位基准或测量基     

工序尺寸图表法的巧用

在编制机械加工工艺规程时,除了按照＂优质、高产、低消耗＂的原则确定毛坯的材料、种类、加工方法、加工顺序和热处理工序等安排外,关键是要确定各工序的工序尺寸。当加工零件的工艺基准与其设计基准不重合时,确定工序尺寸又往往离不开计算工艺尺寸链。所以,工艺尺寸链的正确计算是编制机械加工工艺规程的一个重要环节。     

工艺尺寸链计算方法的研究

机械加工工艺制订过程中，工序尺寸的确定十分重要。当工序基准与设计基准重合时，可按工序余量和经济精度采用反推方法确定工序尺寸，当工序批准与设计不重合时，需用尺寸链原理计算工序尺寸。本文结合齿轮内孔的加工，详细介绍一种解算工艺尺寸链的新方法。     

工序尺寸中的假超差判定法

在零件的加工过程中,加工表面本身的尺寸以及各表面之间的尺寸都在不断地变化,这种变化无论是在一个工序内部,还是在各个工序之间都有一定的内在联系。当有些零件在加工工序中,其工艺基准(定位或测量基准)与设计基准不重合,或加工中需要转换定位基准时,就需要进行尺寸换算。但是,按换算后的工序尺寸加工(间接保证原设计尺寸要求时)存在一个假超差问题、这就是零件加工后,按算后的工序尺寸测量,零件是超差,从工序上看,此件即应报废,但按设计尺寸再进行测量验算,零件并不超等,这就是工序上报废而产品合格的所谓假超差问题。为正确、简捷地判定真超差还是假超差。笔者经多年实践,提出判定假超差的方法,应用比较简便     

在线测量技术在数字化车间应用探索

在线测量是一套贯穿数字化车间产品形成过程的品质解决方案,其可以在设计阶段对公差和装配方法进行优化,并根据定义的品质特征生成离线的测量程序,在加工产品时,利用数控加工中心自带测量工具,实现所加工零件在保持位置不变情况下,直接对零件进行测量的技术,同时自动生成测量结果统计表,形成一套闭环反馈系统。     

Using PCR-TOPSIS to optimise Taguchi's multi-response problem

The Taguchi method is an efficient method used in off-line quality control where experimental design is combined with quality loss. This method includes three stages—system design, parameter design, and tolerance design. In the real world it is obvious that more than one quality characteristic should be considered for most industrial products; i.e., in most applications the customer's concern is with multi-response problems. Nevertheless, the Taguchi method is not appropriate for optimising a multi-response problem since engineering judgment is the main optimisation procedure in Taguchi method. In order to overcome this problem, this paper proposes an effective procedure called PCR-TOPSIS that is based on process capability ratio (PCR) theory and on the theory of order preference by similarity to the ideal solution (TOPSIS) to optimise multi-response problems. Using PCR-TOPSIS, multiple responses in each experiment will be transformed into a performance index. Therefore, the optimal factors/levels combinations for the multi-responses can be determined. Two case studies in Tarng et al. and Reddy et al. are resolved using the proposed procedure. The result indicates that PCR-TOPSIS can yield a satisfactory solution for multi-response problems.     

计算机辅助尺寸测量及产品质量控制系统

论述了用于机械加工过程中,基于相对测量的计算机辅助尺寸测试系统。它不权能以图形方式实时地将测量结果显示器上,而且能够根据需要,利用统计法准确地绘制出产品的质量控制曲线图,进行误差分析,从而将不合格品消除在生产过程中,起到对生产直接控制的作用。     

典型大尺寸薄壁快速成型件的加工方法

在快速成型机加工大尺寸、薄壁零件时,快速成型机的激光功率、加工中的零件的受力情况和零件的支撑工艺都会影响到零件最终精度。结合在实际加工原型件中遇到的具体问题,进行了加工工艺方法的研究和解决,以便更有效地缩短产品的研发周期,提高产品质量和缩减产品的成本。     

Mobile spatial coordinate measuring system (MScMS) and CMMs: a structured comparison

In many branches of industry, most of manufacturing efforts are directed toward producing objects of specific forms and dimensions. Dimensional measurement is an important part of the production cycle, to check products compliance with specifications. For this, many substantial improvements in the existing technologies have been made, and new measuring systems have been introduced. This paper briefly introduces a recent measuring system—mobile spatial coordinate measuring system (MScMS)—which is suitable for performing dimensional measurements of large-size objects (dimension on the order of tens of meters). MScMS, thanks to its distributed wireless sensor network nature, is portable and can be easily arranged around the measured object. Furthermore, it does not require complex setup operations before being ready to perform measurements. After describing how the system works, we will compare it with well-tested and widespread instruments such as traditional coordinate measuring machines (CMMs), showing analogies and differences. The comparison is structured on the basis of different criteria, which are analyzed in detail in the first part of the paper. Although being able to perform similar measurements, CMMs and MScMS are different in technological features. CMMs are able to achieve higher level of accuracy, while MScMS is more flexible, cheap, and can be important to simplify the current measuring practices within large-scale industrial metrology. It can be concluded that these systems can easily coexist, as each system is suitable for specific applications.     

设计-工艺意图映射模型及其实现方法的研究

分析特征映射中的设计意图－－工艺意图（指非几何形状信息）映射的必要性,建立了意图到工艺意图映射的数学模型,并深入研究该映射函数实现中的关键技术,即特征映射实施过程中尺寸与形位公差映射的难点,特征交互作用后尺寸表达的变化及其有效性判定方法。     

A quality diagnosis method for the large equipments base on quality gene similarity

The quality of the products is one of the key factors for the enterprises to increase their core competitiveness. In order to resolve the problems that the quality diagnosis with respect to manufacturing process is not effective or the low efficiency in the large equipment manufacturing enterprises, we propose a quality diagnosis approach based on the similarity of product quality gene. First, we use a product quality gene model to calculate the similarity between the organisms and the products. Second, a kind of quality gene codes is adopted to describe the complex quality information for manufacturing process. Then, string and grey relation similarity are used to evaluate whether the quality is normal or not by considering the similarity between the detected product quality gene and the case genes. Finally, we use the rotary kiln bearing body as an example to illustrate the proposed algorithm process. Experimental results have shown that the proposed approach is able to support quality diagnosis.     

非线性辨识在涡旋盘加工精度评价中的应用

给出了一种处理机加工工件测量数据的非线性辨识方法,旨在对工件机加工质量进行适当评价,并以典型加工工件——涡旋盘为例,给出了具体的分析过程与计算实例,对一大类具有复杂型面零件的质量评价具有参考意义。