Adjustable fixtures for Neuron structure

Citation

(2007), "Adjustable fixtures for Neuron structure", Aircraft Engineering and Aerospace Technology, Vol. 79 No. 5. https://doi.org/10.1108/aeat.2007.12779eab.004

Adjustable fixtures for Neuron structure

Adjustable fixtures for Neuron structure

Dedicated assembly tooling and sometimes robots are generally used for the manufacture of high-volume products within the aviation industry. For single unit production however, it is not economically viable to invest in that kind of tooling. Therefore, Saab Aerostructures has developed state of the art solutions for single unit production which for example will be used for parts and assemblies of the Neuron structure.

Saab Aerostructures primarily do series production of structural parts and assemblies for civil and military aircraft, but in certain cases single unit production is done. This is the case with Neuron, which is a demonstrator of an unmanned combat aerial vehicle that is being developed by several European aviation companies, one of which is Saab. Saab Aerostructures is to manufacture parts and assemblies of the single unit structure for the demonstrator utilising a cost effective production method.

In order to manufacture single unit products in an efficient way, Saab Aerostructures, together with Linköping University and a range of other industrial partners, have developed a method with adjustable fixtures called FlexAA, flexible and accurate automation.

“We cannot economically justify production using robots when it comes to single unit production. FlexAA provides us with a solution that enables us to replace the robot with a person who carries the work out as thoroughly” explains Magnus Engström, Project Leader at Saab Aerostructures.

The solution consists of a framework, a number of adjustable tool modules called hexapods, a measuring instrument and a computer to analyse the measuring data. With the aid of these parts flexible, precise, easy and cost effective manufacturing can be achieved relatively quickly. The actual jig and all corresponding components can be quickly and easily created and defined in CAD tools.

Figure 4 The solution consists of a framework, a number of adjustable tool modules called hexapods, a measuring instrument and a computer to analyse the measuring data

The tool modules, the hexapods (Figure 4), are adjusted by the securing points at the top of the hexapod being continuously measured by a measuring system. The measuring system is connected to a computer where a calculation is made of how much each leg must be extended, or shortened, in order for the fixing point to reach its desired position. Adjustments are made manually and each hexapod takes 5-10min to adjust.

“This method is unique in assembly production and is like nothing else we have seen before within the aviation industry. Hexapods are in themselves nothing new, but we are probably the first to use them for this application” says Magnus Engström.

There are many advantages in using the method. The lead-time in producing the tool is reduced as all parts are standard parts. Costs are also reduced as expensive dedicated assembly tooling is not required. The possibility of easily changing the settings of the hexapods manually also means that later changes in airframe design become easier to introduce. A further advantage is that the entire tool system can be reused for a different purpose after manufacturing is complete.

Saab also reports that it has developed a redesigned aileron for the Airbus Single Aisle family which in appearance is identical to the older one, but where the costs have been cut by 25 per cent. Recently, the first redesigned aileron was delivered to Airbus UK.

The production of ailerons for the Airbus single aisle-family is a high volume programme for Saab Aerostructures. Saab has developed a redesigned aileron which in appearance is identical to the older one regarding weight and performance, but where the number of components has been halved. Throughput time is considerably shorter and production cost has been reduced by a full 25 per cent. Recently, the first redesigned aileron was delivered to Airbus UK in Broughton.

This simplified design, which is adapted to high-production volume, has also been steered by production methods. Manufacture now takes place in what is known as pulsed production where there is considerable emphasis on ergonomics, and each workstation has certain tasks to be performed in a set time. Assembly has also been made more efficient through utilisation of an automated production line with fixed stations.

The ailerons are mostly made of composite and all laying-up of the composite material takes place in an automatic tape laying machine which cuts costs for laying-up and reduces material waste.

The aileron is assembled in a completely new pulsed production line. This line has been specially arranged to match the pulsed flow and to provide a good ergonomic workplace. All workstations perform tasks that have been adapted to suit the pulsed movement in assembly line that takes place according to a predetermined time plan. Performance of the various stations has been balanced and optimised to reduce costs and tooling. The number of stations can vary depending on how many units are to be manufactured per time period. The pulse rate is set and balanced to market needs.

The line is similar to those used in the automotive industry, but has been specially designed to suit this particular product. In certain respects this line is more advanced than those employed in automotive production.

Figure 5 Saab Aerostructures

Saab Aerostructures (Figure 5) has produced ailerons for the Airbus Single Aisle family since 2000, and the first delivery took place in 2001. The ailerons are delivered to Airbus UK in Broughton, Britain for the final wing assembly.