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.