3D Assembly Yield Modeling Of Single Station And Robust Design Of Process Paramaters

Three-dimensional assembly is a typical character of modern equipment manufacturingindustry. Taking the parts three dimensional assembly processes for research object, the threedimensional single station assembly variation model based on pin-hole/slot vice arbitraryplacement, three dimensional assembly yield model and the robust design method ofpin-hole/slot vice layout are investigated. The robust design modeling method of productassemble variation deviation in three dimensional assembly system is developed.Firstly, the literature on the research topic is introduced. Then, the importance of productassembly dimensional variation analysis is explicit. The related research of home and aboardon dimensional variation propagation modeling, assembly yield modeling and pinholeposition layout robust design is summarized. The, main contents, general structure schemeand innovation points of this dissertation are given.Secondly, the fixture locating deviation of three-dimensional assembly system, the partsvariation, the parts variation caused by the fixture locating deviation and the influence ofdifferent joint types to variation propagation during assembly processes is analyzed. Thethree dimensional single station assembly variation modeling method based on pin-hole/slotvice arbitrary placement is explored by combining the parts variation caused by fixturedeviation and the assembly variation propagated through different joints. Then, taking anassembly which consists of four simple sheet metal as an example, combining with theMonte-Carlo method, the assembly deviation distribution characteristics of reference pointsare analyzed through the assembly deviation model.Thirdly, the difference between Number theoretical net sampling method andMonte-Carlo sampling method is expounded and the advantages of former are introduced.Then, the calculation method of product three-dimensional assembly yield is researched. Firstof all, the parts variation and fixture deviation are sampled by Number Theoretical NetMethod. Then, adopted the three dimensional single station assembly variation model basedon pin-hole/slot vice arbitrary placement to get the qualified samples and the eligible samplesdivided by the total number of samples is the assembly yield of product. Combined with casestudies, for the purpose of verifying the assembly variation model the simulation analysis ispreceded through3DCS. It provides a method to solve the problem that modeling assemblyyield in three-dimensional multi parameters assembly processes.Fourthly, based on Taguchi orthogonal experiment and3DCS, a method of pin-hole/slotvice locator layout robust design of parts assembly is presented. First of all, based on the3-2-1locator principle of three dimensional assembly, taking the car lampshade assemblyprocesses as an example, the influence of pin-hole/slot vice locator design parameters on theassembly variation of part is analyzed and the pin-hole/slot vice locator design parameterslevel of car lampshade is determined. Then, Taguchi orthogonal experiment is arranged considering the pin-hole/slot vice locator coordinates of car lampshade as design parametersand locating variation as noise parameters. A robustness evaluation function of assemblyquality is proposed considering the assembling clearance between turn light and headlight asevaluation index. Following, the SNR calculation method of pin-hole/slot vice locator layoutrobust design is put forward. In the end,3DCS is used to analysis the robustness of assemblyquality to variation parameters under different pin-hole/slot vice locator schemes and therobust layout scheme is determined.Finally, based on the regression orthogonal combination experiment, the relationshipbetween the pins’ tolerance and assembly yield is analysed, then the response surface modelof assembly yield and locating pins’ tolerance is established. Based on tolerance sensitiverobust design model, the sensitivity function of pins’ manufacture cost function and assemblyyield function to design parameters and noise factors is analyzed. Through introducing theweighting factor and assigning different weights to the sensitivity function and locating pins’manufacture cost function, taking sensitivity and locating pin manufacture cost minimun asthe objective and assembly yield as constraint, the locating pin tolerance sensitive robustdesign is processed and the sensitive robust design result is obtained.