Development of an automatic check sheet creation program for precision check of a jig in a car sash welding

A jig used in a welding equipment for car sashes and parts requires high precision for accurate alignment of parts and tools. Jig precision is determined by comparison between checkpoint of a jig obtained from CAD data and direct measured data from the jig itself. The creation of a check sheet that contains these checkpoints is generally done, in small-to-medium sized companies, by translating 3-D modeling data of a part into 2-D drawing and by selecting checkpoints from it, because that companies cannot usually afford to possess and utilize a high cost 3-D CAD package. And, because it is difficult and inaccurate to show free surfaces of a part in the 2-D drawing, the check sheet created in this way cannot avoid containing errors to some extent. Furthermore, the creation activity of the check sheet by use of a translated 2-D drawing requires time consuming manual operation and eventually reduces company's productivity. In order to solve all these problems, an automatic check sheet creation program for precision check of the jig in a car welding was developed.