Use of Electromagnetic and Vacuum Forces on Aircraft Assembly 2002-01-2630
Decades ago our innovative grandfathers developed the first automated riveting machines based on hard automation using kinematics and tools attached to a C-frame. The C-frame serves multiple functions: First, it holds the upper and lower tools in fixed positions relative to each other; second, it translates upper active tooling forces to the lower tool; and third, it embraces the part placed between the upper and lower tool. C-frames and newly developed yoke, ring and gantry machines, used for low level (first, second) fuselage and wing assembly are growing in size to exorbitant proportions to satisfy requirements of larger and larger structures. High costs are dictated by massive kinematics and complex controls that provide stability, precision, and process speed. All this is mainly needed because we have to carry mechanical forces around the part, from upper to lower tool along the C-frame, gantry, yoke, bridge, etc.
There are several other forces in nature (i.e. gravity, electricity, magnetism, pressure, vacuum, heat, atomic, friction, etc.) which can be considered and applied to machine design to achieve optimum and reliable results for minimal investments in machinery and floorspace.
Analyzing alternative forces in search of more innovative assembly systems specifically for high level assembly where “embracing” parts (fuselage barrels, wing boxes) is no alternative, electromagnetic and vacuum forces were down-selected as the most promising option.
The specific characteristics of magnetic flux capable of penetrating a part provides an ideal technique for generating clamping forces during drilling, fastener feeding, and the upsetting process. Electromagnet generating clamping force is easily integrated with a multi-function end effector moving on rails along structural joints performing fastening in sync with an internal tool.
Vacuum systems capable of generating forces on part surfaces using suction cups and/or vacuum chambers, have the capability to attach/hold assembly systems on aircraft structures by part non intrusive means.
Utilization of these new technologies in aircraft assembly enables the development of new innovative light-weight, flexible assembly systems, targeting high level fuselage and wing assembly. Principles and technologies needed for generating electromagnetic and vacuum forces for a prototype assembly system are discussed in this paper.