Manually aligning and joining completed aircraft sections is historically a time-consuming and cumbersome process. To increase both the efficiency as well as the quality and safety of the join process, Brötje Automation has developed the Automated Positioning and Alignment System. There are two versions, one for joining fuselage sections and the other for mating wings to the fuselage.
The company's positioning and alignment systems are designed with the flexibility to use on a range of aircraft, all fully automatic.
Brotje calls its solution the Final Assembly Line (FAL). Several FALs are in operation.
Precise measurement is the key factor in a successful alignment and can be accomplished using a variety of measurement technology. The most commonly used technologies for this are laser trackers, indoor GPS, and laser radar systems. In any case, precisely measured points on the aircraft are communicated to the “best fit” software inside the control station, which determines the best possible location of each of these points for mate-up and sends the coordinates to the CNC for positioning. In the case of a regional jet application, the customer chose the laser radar system for measurements.
The FAL for the regional jet consists of 50 CNC axes on 20 NC positioners for measuring and aligning each of the five fuselage sections. Another 26 CNC axes on 10 NC positioners are used in the wing join station (three NC positioners are used for each wing, four for the completed fuselage).
The following parameters were specified by the customer for design of the automated positioning and alignment assembly and were successfully implemented:
• Positioning accuracy of ± 0.2 mm
• Repeatability of ± 0.1 mm
• Maximum feed rate (fuselage join) X-axis of 1000 mm/min
• Maximum feed rate (fuselage join) Y/Z-axes: 300 mm/min
• Maximum feed rate (wing join) X/Z-Axes: 1000 mm/min
• Maximum feed rate (wing join) Y-Axis of 500 mm/min
The controller for the NC positioners is the Siemens Sinumerik 840D, of which two are deployed because of the high number of axes.
The NC positioners were designed with the technical details listed below. Although based on the same modular concept, each positioner requires a different range depending on its placement (fuselage join requires large X-axis movement, wing join requires large Y-axis movement), which is the reason for the range of values:
• X-stroke varies from 100 – 1800 mm
• Y-stroke varies from 600 – 2000 mm
• Z-stroke of 100 mm
• Maximum load Z-axis (dynamic) of 6000 kg
• Maximum load Z-axis (static): 21000 kg
• Maximum load X- (or Y-) axis (dynamic) of 500 kg (mate-up force)
• Load cells of X, Y, and Z-axes
The measurement data from the laser radar is automatically collected and analyzed by the “spatial analyzer” software from New River Kinematics, and all coordinates are stored in a database. Using this measurement data to calculate a “best fit” mate-up scenario and transferring the resulting coordinates to the CNC control is taken care of inside the Brötje automation control center. Each control center contains an HMI for the 840D controller, an operator PC, and a service and measurement PC.
The PC is the operator’s interface to the entire alignment and join process. Customized software that provides step-by-step instruction is a simple and clear method for controlling and/or monitoring the alignment and join system. From here the operator can maintain full control and operation, from measurement all the way to mate-up—all controlled from a single operator desk.
In the case of the regional jet, the Brötje system improved cycle time for alignment from three days to one. In general, even greater improvements are possible because FALs are custom-designed and thus can incorporate more automation—for example, an automated drilling and fastening machine for both the longitudinal and circumferential splices.
This article is based on SAE technical paper 2009-01-3118 by Holger Maylaender of Brötje Automation GmbH and Brian O’Rourke of Brötje Automation USA Inc.