摘要
夾具作為機(jī)械制造業(yè)的一種重要工藝裝備，它的設(shè)計(jì)與制造會(huì)直接影響到產(chǎn)品的研發(fā)周期和質(zhì)量?？s短夾具設(shè)計(jì)周期，是計(jì)算機(jī)輔助夾具設(shè)計(jì)研究的重要領(lǐng)域，也是提高企業(yè)快速反應(yīng)能力的一個(gè)重要環(huán)節(jié)。隨著船舶工業(yè)和制造業(yè)的發(fā)展，市場(chǎng)對(duì)各類管件的需求量不斷增加。目前，針對(duì)眾多空間走向多樣化的管件焊接，一般都采用專用焊接夾具，雖然其能保證定位精度，但同時(shí)也將導(dǎo)致諸如夾具制作周期長(zhǎng)、資金重復(fù)投入，夾具使用后的存放占用空間大，使用范圍小，功能單一化和工裝管理難度增加等問題。因此亟需設(shè)計(jì)一套行之有效的管件焊接柔性?shī)A具，同時(shí)，由于管件焊接夾具存在一定的柔性，因此有必要對(duì)如何能快速有效地確定裝夾方案進(jìn)行深入研究，進(jìn)一步擴(kuò)大管件焊接夾具的使用范圍。
針對(duì)上述現(xiàn)實(shí)問題，本文在已有管件焊接夾具設(shè)計(jì)工作的基礎(chǔ)上提出了管件焊接夾具裝夾方案智能CAD系統(tǒng)體系，開發(fā)了夾具裝夾方案智能CAD系統(tǒng)，論文的主要研究工作包括以下幾個(gè)方面：
(1) 在分析某企業(yè)管件特征的基礎(chǔ)上，利用柔性化思想，設(shè)計(jì)了能夠滿足大多數(shù)管件焊接所需要的夾具平臺(tái)，實(shí)現(xiàn)了夾具的柔性化；
(2) 對(duì)已有管件焊接夾具及管件對(duì)象的信息進(jìn)行分析、歸納、總結(jié)，構(gòu)建了管件焊接夾具實(shí)例庫(kù)，實(shí)現(xiàn)了包括對(duì)實(shí)例的檢索、修改、添加、刪除等功能的實(shí)例庫(kù)管理；
(3) 在構(gòu)建管件焊接夾具實(shí)例庫(kù)的基礎(chǔ)上，提出將知識(shí)推理技術(shù)運(yùn)用于裝夾方案設(shè)計(jì)過程中，通過兩層相似度計(jì)算算法，檢索新管件焊接夾具的最相似實(shí)例。首先計(jì)算管件對(duì)象及夾具結(jié)構(gòu)上的相似及夾具布局局部相似度，其次利用線性Hamming復(fù)合算法計(jì)算整體相似度，保證了檢索出的實(shí)例與新對(duì)象夾具相似程度最高。在檢索出相似度最高的實(shí)例中，利用機(jī)械設(shè)計(jì)規(guī)則選用元件規(guī)格及空間坐標(biāo)轉(zhuǎn)換技術(shù)計(jì)算定位件的夾緊區(qū)域，并結(jié)合SolidEdge的二次開發(fā)技術(shù)，實(shí)現(xiàn)了對(duì)實(shí)例的自動(dòng)修改，完成對(duì)夾具及夾具裝夾方案的調(diào)整。根據(jù)相似實(shí)例的裝夾方案，來設(shè)計(jì)待求管件的裝夾方案；
(4) 針對(duì)焊接管件擺放空間位置不確定而存在的裝夾不合理，本文引入旋轉(zhuǎn)法來求解焊接管件的空間位置，編程實(shí)現(xiàn)了管件在夾具中空間擺放的最優(yōu)位置；
(5) 通過需求分析，利用VisualBasic語言和SolidEdge軟件混合編程技術(shù)實(shí)現(xiàn)了夾具裝夾方案智能CAD系統(tǒng)的開發(fā)。

關(guān)鍵字 柔性?shī)A具；管件焊接；實(shí)例推理；夾具CAD系統(tǒng)；裝夾方案

Abstract
As an important process equipment in mechanical manufacturing, fixture directly effect product quality and design cycle. Shorten fixture design cycle is very important research field in the computer-aided fixture design, as well as a key link in enhancing enterprise rapid reaction capability.
With development of shipbuilding industry and manufacturing, the market is in increasing demand for various types of tube. In present enterprise, special welding fixtures are used generally to locate a lot of welding tube with the variety space tendency. The special welding fixture ensure the location accuracy but it brings a series of problems such as long fixture production cycle、repeat investment funds、a large storage space、limited usage、simplification function、more difficult fixture management and so on. Therefore a set of effective tube welding fixture should be imperative. Owing to tube welding fixture being certain flexibility, it is necessary to study how to determine fixture plan rapidly and effectively in order to expand further the use of tube welding fixture.
Aiming at those problems, the intelligent system of tube welding fixture clamping plan was advanced and developed, based on the abundant experience of designing welding fixture. The main job of the thesis includes in the following aspects:
(1) A set of tube welding fixture which meets most of the tube welding and realize the fixture flexible is explored on the basis of analyzing feature of tube parts and using flexible thinking;
(2) The tube welding fixture case library was constructed based on clearing up a mass of tube welding fixture we have had. The system realizes case library management, including searching of existing welding fixture、modifying the case、adding or deleting the case of welding fixture;
(3) The method of fixture plan design using knowledge reasoning technology is put forward base on the construction of the case library of the tube welding fixture. The most similar case is searched by using two-layer similarity algorithm. First，the local similarity which contains the similarity on the tube object and fixture structure and the similarity on fixture layout is calculated; Second, global similarity is calculated by using linear Hamming complex algorithm. This index way ensures to retrieve the case with the highest similarity to the new tube fixture. The design rule which choose components and coordinate transforming technique which calculates positioning parts clamping area ,with the secondary development technology base on SolidEdge are used to modify the case which is of the highest similarity in order to assemble automatically and complete the fixture clamping program adjustment Fixture plan of new problem would be designed based on this one;
(4) In this thesis, aiming at the problem that the spatial location of tube in welding is not reasonable enough, the rotation rule has been adopted for solving the tube welding spatial location. The arithmetic has been implemented in the system module;
(5) On the basis of analyzing re..