Patent ID: 7797126

Claim:
Online determination of bulge/upset dimension x ST and rivet head end position K HS of a half-hollow punch rivet having a length L in a punch rivet process by a moveable punch and a die, comprising the following steps: a. capturing a path covered by a moveable punch during the punch rivet process with the help of a travel sensor, b. capturing a force F applied to the half-hollow punch rivet by the moveable punch during the punch rivet process depending on the covered path, c. determining an attachment point x 2 of the half-hollow punch rivet with punch to a joint part and a release point x 4 from the captured force/path data, while the release point x 4 identifies a release of the punch after the punch rivet process and d. calculating the rivet head end position K HS in accordance with K HS =x 2 +L−x 4 and bulge/upset dimension x ST in accordance with x ST =x−x 4 , where x is the maximum distance between facing sides of punch and die.