Error Modeling And Analysis Of The Large Structure Transport Jigs & Tools

This paper studies the approach for error modeling of the nose transport jig assembly error of Major Component Aircraft Transport Jigs & Tools (MCATJT), and deals with error analysis and the evaluation of assembly accuracy. The following constributions have been made.Using spatial pose representation of objects, this paper studies the influence of the manufacturing imperfection in locators and workpiece surfaces on workpiece's pose accuracy in a 3-2-1 fixturing scheme, and presents the modeling methodology to study the workpiece's pose error. On the basis of 3-2-1 fixturing scheme, this paper discusses the approach for error modeling of the 4-2-1 fixturing scheme. Based upon this modeling methodology, this paper models the Front Frame (FFR) of MCATJT using the homogeneous transformation matrix(HTM) method, and indicates that the error model of FFR can be used to evaluate the error of the Front Cradle (FFC). Based on the Monte Carlo simulation for error analysis, this paper presents an approach to simulating two kinds of fit clearance error. Corresponding to the error modeling methodology, this paper presents a method to deal with spatial assembly dimension chain. This method divides the spatial dimension chain into simple dimension chains relating to the coordinate of single locating point, as the result of this, it not only simplifies the problem of spatial dimension chain, but also realizes error analysis for manufacturing.From the error analysis simulation of some points, this paper yeilds that the coordinates error of points are relevant to the locating mode and the layout of locators. And the evaluated accuracy of points'coordinates have been simulated based on the given tolerance design. Error simulation of some points of FCR has been made using the error model of FFR.The experimental measurement of the nose transport jig assembly has been carried out using the laser traker. The analysis of the measurement data shows that the results of simulation have a good match with the experiment results.