CMM In Car Inspection Product Line

With car industry development in our country, car industry faces more furious competition after China enters WTO. CMM (Coordinate measuring machine) will play a very important role in car industry which needs high quality and more functionality. Especially, CMM is used not only in metrology centre, but also in workshop and product line. More accuracy and high efficiency is urgently required for car inspection with CMM.This dissertation addresses the measurement method of car underpan, white car body and engine block using CMM in car inspection product line. The following achievements have been gained:1, The hole and slot searching algorithm and thickness compensation algorithm have been developed to solve the measuring interrupt problem due to the big sheet metal deformation which influences measuring efficiency.2 In order to solve the problem, which is that fixing Sheet metal directly will cause big deformation and influence measuring accuracy, Sheet metal is fixed by Five system, Witte system and special fixturing tool, at the same time sheet metal fixing points must be indicated by Designer who should analyze part functionality.3, Many complicated positions need to be measured on the engine block, but it is difficult to measured many positions with one stylus. In this paper, a tool change method, which can change probe or stylus automatically without interrupt and raise measuring efficiency, is proposed.4, In order to keep product line stable, batch data is analyzed with statistics software. Subsequently, the product line can be adjusted on the basis of the statistical result.