Robot operated C-frames are used for riveting and clinching operations within the automotive industry. The performance of a C-frame is measured by its weight and amount of angular misalignment of the jaws during the riveting process. ALFGAM participated in the invention of a new type of C-frame, called the Aligned C-Frame (ACF). This new C-frame technology reduces the weight to 50-60% of a conventional C-frame and completely eliminates angular misalignment. The ACF's are produced by C-Power Technologies.
An ACF must be perfectly balanced to assure its superior characteristics. For this very large 980x170 mm C-frame an appropriate design was impossible to achieve by hand. In cases like this ROpt is unbeatable as a design tool.
The FE-model of the ACF was imported to ROpt and 26 design variables were applied to the structure. Some of the variables controlling the beam nodes can be seen as red arrows to the left. Constraints were set on stresses in the material and on angular and vertical deflection of the jaws. The objective function of the optimisation was set to minimise the weight of the frame.
By using structural optimisation an almost impossible design problem was solved. The optimised ACF to the right measures 1.5x1.1 m externally at a weight of only 109 kg. The jaws of the optimised ACF has a vertical opening of 6 mm and zero angular misalignment at 55 kN load. Stresses are sufficiently low to guarantee infinite fatigue life.