Ribs and frames are the forming elements for the structure of an aircraft wing. The ribs are attached to the main spar and, repeated at frequent intervals, form a skeletal shape for the wing. Ribs usually incorporate the airfoil shape of the wing and the skin adopts this shape when stretched over the ribs.
The problem becomes apparent when we realise that almost every rib is a different shape and size. So they need to adapt to the geometry of the airfoil and slowly change from one to the next. Besides, there is always a symmetric part for the other wing.
We repeatedly see how customers are confronted with this situation so we designed a suitable strategy to help manufacturers.
How to be flexible?
For this project we focused on a specific set of ribs of around 1,300 x 330 x 100 mm and used our Makino MAG1 5-axis horizontal machining centre.
We designed a couple of fixtures. One fixture clamps the parts using a dovetail pre-machined shape on the raw material. In this way, we clamp the assembly in a low surface for the vertical and longitudinal directions. The second fixture applies the same principle but uses numerous small screws to keep the part in the required position.
To enhance rigidity we use a side bracket.
To enhance the rigidity we use a side bracket
Once the fixture is ready, it's time to start cutting. With the fixture designed in this way, we enjoy spindle access to all features of the part so we can cut all the features in just one operation.
As the fixture rigidity is rather high, we also have the opportunity to exploit our unique machining capabilities to machine the part.