In-process Controlled Y-shape Tube Hydroforming with High Accurate Built-in Sensors

In this study, to improve the bulged shape accuracy in the former fuzzy adaptive controlled Y-shape tube hydroforming system with die-built-in sensors, a new highly-accurate contact sensor is developed and a new combination control scheme using two evaluation functions is introduced into the fuzzy control algorithm. The developed contact sensor consists of total 3 micro switches in orthogonal directions and enables setting into a counterpunch. The micro switches are aligned at 2 mm intervals on their central axis and the contact sensor has sensitivity of ± 1 mm. As a new combination control scheme, a new evaluation function was introduced into the previous input membership, and two types of evaluation functions at different locations, at the die-corner radius and the counterpunch head sites, are inputted into the input membership functions simultaneously and then the output membership functions are defuzzified, and finally the output control values can be determined. Compared the new in-process controlled Y-shape tube hydroforming system with the our previous one, the experimental result demonstrates a high filling at the bulged top head and higher shape accuracy and dimensional accuracy of bulged part.