Vacuum induced membrane end-effector for micro laminates

Abstract

The research investigates the creation of an end-effector capable of pick-and-placing thin laminates of various materials. The chosen end-effector design induces a pressure differential with a membrane, and is capable to achieve a large switching force for various delicate and geometric complex laminates. The concept utilizes an array of holes, over which a membrane is suspended, hereafter called suction cups. By applying pressure upon the suction cups, the membrane deforms, resulting in a vacuum capable of generating large switching forces. During contact the vacuum is created, and during release the membranes are expanded to release the laminate.
The design variables (radius, membrane height, membrane thickness, Young's modulus of membrane) of the concept are numerically investigated to analyze their influence on the suction pressure, the deformation of the membrane and the corresponding stresses in membrane and laminate. The numerical results indicated that the membrane thickness and material are vital. As an increase in thickness and young's modulus results in an exponential increase in switching force. These numerical results and the end-effector production method determine the final dimensions. The prototype is then used to perform a set of experiments to validate the numerical model.
The measurement results on the deformation of the end-effector membrane confirm model results. However, production inaccuracies and the application method of the membrane resulted in inconsistencies in the dimensions and its performance. The force measurement results indicate that the force created by the end-effector is heavily impeded by the sealing performance of the suction-cups. Improving the sealing performance resulted in values in accordance with the numerical model. The pick-and-place experiment indicates that a substantial force is created by the suction cups, capable of pick-and-placing rigid laminates. For the transportation of flexible laminates (thinner and/or smaller young's modulus), smaller forces are created due to the compliance of the laminate, therefore more accurate production and a thinner and more flexible membrane is required. Depending on the laminate material and shape, certain design guidelines are in place. A larger force can be created on more rigid laminates, allowing for the application of a less flexible membrane. For thinner laminates the switching force is reduced, and therefore the membrane needs to be very flexible and thin. For a more complex shape, smaller and more suction cups are required, impacting the other variables. Additional guidelines for various laminate materials and shapes are found at the end of this report.
In conclusion, an end-effector based on the membrane induced pressure differential is a design path which is worth investigating further for pick-and-placing thin laminates. Depending on the application and thus the target laminates, certain design guidelines are set up at the end of this report. These can be used for further research to pick-and-place geometric intricate laminates of various materials.