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Automated cells rivet airliner skin panels.

The Boeing Commercial Airplace Group, Wichita Div, is taking delivery of the first of two DNC/CND C-frame riveting machine cells with positioners from Broetje-Automation GmbH of Rastede, Germany. The second will be delivered in the spring of 1993.

The two systems, which are numerically controlled using the design database for machine programming, will be used for automatic assembly of cockpit section skin panels for the new-generation Boeing 777 wide-body aircraft. Similar machines are currently installed at Kawasaki Heavy Industries in Japan for the assembly of the 777.

The need for sophisticated high-production riveting equipment is evident from the fact that as many as a million rivets are used on a single aircraft. The C-frame riveting machines, similar to the one shown here, accommodate an advanced upper tooling system with automatic rivet selection and two swing-in drill spindles with automatic tool changers. Optical sensors, statistical process control, and work area monitors are included in the machine systems.

The frame positioner is equipped with an automatic clamping system for the fixture frame. It allows both horizontal and vertical loading, providing a skin panel working area up to 480" long and 240" wide.

Once the panel is positioned on the positioning frame using TV sensors and monitors, the work sequence is automatic. The panel is placed into the correct work height and position, and the first riveting point is found. The rivet path is controlled by off-line programmed DNC. No dots or markings are used. Off-line programming uses data from the CAD system.

Because the large sheet metal panels tend to sag due to their own weight, they don't remain in the necessary theoretical shape and position. A position correction must be made to the off-line programmed theoretical data. This takes place by the application of a specially designed ring sensor, which is installed around the drilling spindle at the upper tool. The ring sensor determines the deviation of the true surface line to the theoretical work line. The information obtained by the control is then used to automatically correct the offset. Positioning time from rivet to rivet at a distance of 22 mm, including program correction, is 1.5 seconds.

The correct rivet is selected either by program or automatically by measuring clamp thickness. A sensor indicates if a rivet is available or not at the riveting head. While drilling, chips are removed by vacuum system or blown away from the lower tool by compressed air. Sealant is injected and the rivet is inserted and then upset using about 30 kN (66,000 lb) of force. Rivet head height is then measured to assure proper installation.

The complete work cycle rivet to rivet is five seconds: 3.5 seconds for drilling, counter-sinking, sealant injection, and rivet insertion/upsetting, plus 1.5 seconds for driving to the next rivet position. During the approach of the next rivet point, all NC-axes of the positioner can be actuated simultaneously.

The production cycle can take up to ten hours because of the large number of rivets installed and the very large sizes of components. After part completion, the fixture with the part is unloaded, and a different fixture with a part is loaded on the positioner. The machine is then ready to process a completely different component.

For more information from Manca Inc, Westwood, NJ, circle 227.
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Copyright 1992 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Manufacturing Solutions; Boeing Co. Boeing Commercial Airplane Group's C-frame riveting machine cells with positioners
Publication:Tooling & Production
Date:Oct 1, 1992
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