Folding Mechanism

Folding Fixture

folding fixture
The mechanism that we developed for folding the stainless steel sheets is shown in figure above.  The folding mechanism is operated in the follwing manner:

Determination of Folding Angle Sequence

beam cross section
undesired configuration
desired configuration
Desired Triangular Cross-Section for the Stainless Steel Beams
Undesirable Configuration When Folding the Beam
Desirable Configuration When Folding the Beam

To acheive the desired triangular cross section for the stainless steel beams requires three sequential bends to the flat steel sheet.  Although the folding fixture is currently operated by hand, the aim is to fully automate the process.  As such, when the folds are completed, we want the structure to naturally tend to assume the triangular cross section so it can then be fed into a triangular channel and sealed in place.  This means that as the third fold is being completed, we want the edge P3P4 to travel down the clamp and not up (as was observed in some initial trials).  

To determine the conditions when that happens, we model each side of the triangle as a robotic link and then see what the required angular motion is for each link to guarantee the desired ending configuration.  This led to a static anaysis based on a pseudo-rigid compliance model and the resulting nonlinear equations were solved using MATLAB.  We then chose a set of angle sequences from the results.  In practice we use around  89° for the first fold (gamma), 101° for the second fold (beta), and 60° for the third fold (alpha).