Research And Application Of Checking-fixture Design System For Automotive Pipe Based On NX

The bended pipe is an important part of the car.Checking-fixture for bended pipe,is a tool to test whether the pipeline product is qualified or not.Traditionally,the design mainly depends on artificially drawing in three-dimensional CAD software.The design process,heavily dependent on workers experience,having a large amount of operations like space transformations.It's long design cycle and poor efficiency,makes traditional design unable to meet the requirement of modern industry.Based on this,companies are in desperate need of professional checking-fixture design software,hoping to promote fast and automatic design of checking-fixture for automotive bended pipe.Checking-fixture design software helps to shorter the design cycle,promote production equality and efficiency,and ensure the market competitiveness of enterprise.In the design process,interactive design and assembly of check-fixture's parts is the core and difficulty points.The thesis summarizes the current situation about checking-fixture CAD on both home and abroad.The checking-fixture CAD system based on NX9.0,using parametric design,template technology and feature-based Automatic Assembly technology,realize automated and intelligent design.The main work of this article include:(1)General plan of checking-fixture system.On the basis of demand analysis,confirming and dividing the functional modules and software process of checking-fixture system,analyzing dependence relationship between modules and determining data transform mode.(2)Build a library of checking-fixture's standard prat.build the library of standard part based on parameterized design,template technology and assembly-oriented modeling technology,resulting in effectively reducing repeated work in the assembly process(3)Automatic assembly of checking-fixture's parts and optimization of assembly process.Automatic assembly based on feature is proposed.Assembly features is divided into three part: size features,voxel features and relationship features.By obtaining these three kind of features,we can get 3D models of part to be assembled,assembly datum and assembly relationship,so as to realize automatic assembly of check-fixture's parts.Algorithm was proposed to solve orientation and reverse problems.By Deducing pose transformation matrix of two motion forms,rotate about axis or move along the axis is realized.(4)Implement of other functions.Deducing pose transformation matrix of two motion forms: rotate about axis or move along the axis,so as to change the position and direction of checking-fixture's part;Through querying and modifying expressions of parts,realizing the functions of modify plane and modify checking;By charting function and create directional projection,the function of two-dimensional drawing is realized;By the order of reading the database,geting the data of tube-control points,then creating points,lines and pipeline,finally realizing the function of tube creating and tube modifying;In the last,UI design and interface beautification is carried out to enhances customer experience.After all these works,checking-fixture CAD system has been build,with automatic assembly function and other functions performing correctly.The system has been applied to production practice of enterprise.Feedback result shows that the application of check-fixture design system greatly shorten the design cycle,promote the work efficiency and normalization of check-fixture design.