Simplified Manufacture for Complex Aero Structures

Example components
Example components

Modern airframes are highly complex structures made from thousands of component parts. Each component must be manufactured economically without sacrificing quality. Companies invloved in airframe component production require innovative solutions to complex problems, guaranteeing high efficiency while at the same time ensuring airworthiness of the finished assembly. Delcam plc, working closely with a large airframe component manufacturer, has created a solution that eases the route to manufacture for complex parts, while at the same time reducing material costs and improving quality.

The Problem

See Figure 1 - Typical Component

This test part shows many of the features that make this type of component difficult and expensive to manufacture. The part is curved, and has thin, tapered ribs, bevelled pockets, uneven wall thicknesses and other features. Manufacture requires 5 axis machining, using two separate setups. The overall curvature also means that the initial stock is quite large.

See Figure 2 - Component and initial (minimum) stock

The Customer's Solution

The customer's initial solution to this problem was to completely redesign the component to remove the curvature. This had two benefits.

• The part could be machined in a single setup (though still using 5 axis).
• The initial material requirement was reduced.

Once the part had been 'flattened' it could then be machined, and finally bent back to the desired overall form. However, this re-design process typically took several days of intensive work, virtually eliminating any savings made during machining. The customer was keen to find an alternative, more efficient method of redesigning the part, and turned to Delcam for advice.

The Delcam Solution

Over recent years Delcam has introduced powerful morphing technolgy into PowerSHAPE, its hybrid modeller. Morphing allows whole-body edits to be applied to complex 3D models. Shapes can be bent, stretched and twisted interactively and with total control, yet in a very simple to use and understand fashion. Such morphing has been used extensively in applications such as press and mould tool desing to fine-tune models to compensate for the sag or warp that occurs during the manufacturing process. Morphing has also been used to mdify existing designs to alter their aesthetic appearance.

To achieve the desired effect and successfully flatten the test part, two simple surfaces were created. The first of these was a segment of cylinder that represented the curved outer face of the component. The second surface was a flattened version of the first, with care being taken to ensure that the lengths of all the defining curves were the same on both surfaces. These surfaces are known as the 'Reference' and 'Control' surfaces respectively.

See Figure 3 - Component, Reference (blue) and Control (red) Surfaces.

The component was then 'morphed' by the difference between the Reference and Control surfaces, to create the finished part.

See Figure 4 - The finished component

The entire process, including designing the Reference and Control surfaces takes only a few minutes, and the result is a perfectly flattened version of the original, ready for machining in a single setup.

Benefits of the New Method

• Reduced modelling (huge time saving)
• Automated (less chance of human error)
• Reduced material usage (less waste of expensive material)
• Machined in one setup (less time)
• Does not require full 5-axis (lower cost)