Improving the ramp-up process of a body-construction line by numerical supported design of clamping devices and FEM based tolerance prognosis

The manufacturing process of body parts starts with the step of sheet metal forming. The single parts, produced at the press shop, are put into clamping devices in order to align and fix them. The fixation takes part before further operations, such as joining, can be carried out. In order to simulate the process chain of add-on body parts realistically, the clamping process (closing the clamping device) has to be taken into account [1]. The stationary surfaces of a clamping device are called "passive surfaces", whereas the movable surfaces are "'active surfaces". If the clamping process is calculated by means of active surfaces, their positions need to be measured in the state of a closed clamping device. While the passive surfaces of a body construction device can be measured with high reproducibility, the measurement of active surfaces is impracticable in the state of a closed device. This is due to the loss of accessibility. Furthermore, if the parts to be clamped or the position of the clamping device differ from their designed position, the assembly works, such as a flat spring against the clamping device, in all spatial directions. The active surface does not reach the position which has been measured before. In order to take these facts in clamping simulations into account, the end position of the active surfaces should be known. A clamping device concept, based on a measuring probe for optical measurement systems, has been developed. It is possible to determine the position of active surfaces with high reproducibility while the parts are clamped. It can be shown, that the presented clamping device concept contributes to significantly better results of clamping simulations. Thus a better starting basis can be offered for further simulations along the process chain