SENSOR-SUPPORTED GRIPPER SURFACES FOR OPTICAL MONITORING OF DRAPING PROCESSES

Abstract

With the aid of the optical sensor system, the user is able to monitor the draping process online or to evaluate it using stored data. Using these data, it was demonstrated that the draping behavior of consolidated and non-consolidated fabrics differed from each other. The consolidated fabric reacts similarly to a non-drapable material because the stresses are horizon-tally and vertically degraded rather than along the fiber direction, as occurs with the non-consolidated fabric. Due to the gliding direction along the fibers, the latter material behaves as pre-dicted in theory. This provides us with the predictability of the draping behavior. Also, the data suggest the higher drapability, which is unambiguous given because of the low shear strength. On the basis of this fact, the non-consolidated fabric should be used in subsequent test runs. The data additionally show that the draping processes differ from one test run to another despite the identical process configuration. The non-consolidated fabric has on average the lowest gliding be-havior, but the larger variation over all six test runs. This suggests that during the draping process, particularly the easily drapable materials have different effects which cannot be foreseen. In the following studies, the sensor data should be used to optimize the draping quality in the sense of deviation from the real to theoretically determined fiber angles and wrinkle formation of the cut-piece positioned in the tooling. For this purpose, a large number of test runs have to be carried out in which the suction intensity of the suction units will be varied and this configuration will be eval-uated by means of the fiber angle and boundary curve sensor data. The goal will be to develop an optimal draping strategy, which can be documented on the one hand with the help of the sensory data and on the other hand it can help to counteract draping deviations of the actual to the optimal gliding behavior. For this, it will be necessary to intervene online in the draping process. For such an active draping mechanism, a control system must be developed which is capable of influencing the holding forces of the suction units by varying the volumetric flow. If the system now detects an actual sliding vector deviating from the target, the system can intervene. It can reinforce the holding force in the area correspondingly if a deviating gliding behavior has taken place or reduce the holding force if it prevents a required gliding.