1-Description

> The Coriolis Composites fiber placement system uses the 6 motion axes of the polyarticulated robot plus external ones, for, for instance a tool command and a robot positioning axis. A robotized cell commonly has a 8 axes system “”. The robot as the whole cell comply with the aeronautical specifications concerning the fiber placement and cutting accuracy as well as the repetitivity and reliability of the process.

A- Robot cell

Coriolis Composites has selected ABB and Kuka for their robot supply according to their performances in the placement field, particularly:

-Accuracy and reliability,
-Triggers anticipation for cut and restart on the fly
-8 axes local pooling including the robot 6 axes, linear and two dimensional (horizontal and vertical) positioning

B- The Fiber Placement

The fiber placement system consists of the robot, the Coriolis Composites robot head, a creel (bobbins stand) and the guiding pipes.

The guiding pipes system insures the supply of the prepreg fibers to the head. They mainly secure the tension of the fibers during the whole process even when lost trough rapid unreels. They also protect the fibers by providing them a protected, fixed temperature enclosure. At the start of the placement the first fibers are guided through a flexible pilot. The service tension is very low and their enclosure cooled. The guidance concept has completed a two years experiment on the Coriolis Composites pilot cell, giving the proof of the excellence of the solutions. Despite harsh experiments at maximal speeds on very large as on small forms, the pipes have shown neither tear nor accumulation. In case of incident, the pipes can be easily replaced and their stiffness, combined with their rectangular section eliminates all breaks and twisting of the fibers even during the most complexes moves.

> The head

The design of the head has is extremely compact and light, to comply with medium range robots capacity. It contains three easily and separately removable units:

-Heating unit,
- Guidance unit,
- Mobile unit loaded with the cutting, final guidance and reforwarding devices and the electro pneumatic triggers.

Main data :

- Dimensions 8x1/4’’ (50 mm) broad 24x1/4’’ (150 mm) ‏height 50kg to 70 kg
- Minimal fiber length on even surfaces : 80 mm.
- Maximum placement speed: 1 m/s.
- Maximal speed on fly between to placements: 2 m/s.
- The compacting strength can vary from 100 to 1 500 N, allowing placements on special surfaces like honeycombs, inserts and complicated forms.
- Through an infra red lamp the head also heats the wrapping zone, adjustable a °30°C to 200°C temperature range.

> The creel

- The spools of the creel run freely. Their motion occurs through a patented pre delivery device, the Multiwinch®. The Multiwinch® role is to feed the head on command while reducing the tensile strength to near zero g in the whole range of placement speeds, It works with an unique motor
- Each bobbin makes a unit with quick electrical and pneumatic connectors. It contains spooling, unspooling interleaf and axis braking devices and is equipped with strength and rotation sensors - The Creel stops the robot head in case of :

- Fiber breaks
- Empty bobbin
- Faulty start on a new fiber placement,
- Damaged reel giving an overstrenght by spooling off

2-Measured productivity

> For a square surface of 1 m x 1 m with 16 fibers 1/4'':

- 1 mn / ply, 60 m²/hr
- a 60 m²/hr floor to floor production can be reached with 2 robots: one on duty, the other on preparation - 60 m²/h with 300 g/m² gives 18 kg/h production.

3-Precision

> Robot

- Gap between two stripes: -0 +0.5 mm
- Option «calibrated robot «: the factory calibration of the robot is integrated in its control device
- Option “Absolute accuracy”: the moves under loads are automatically software corrected for an absolute precision
- Trajectory repeatability: +/- 0.3 mm (max loads and speeds.
- Repetitiveness on move: +/- 0.1 mm (max load).
- Précision measurements under maximal load:
- For the head position as measured by the robot, the absolute precision on the form is usually under +/- 0.5 mm

> Placement head

- Cutting and restart précision : +/- 0.5 mm
- Cutting and restart precision on fly: +/- 2 mm
- Cutting and restart on fly repetitiveness at 0.3 m/s : ±2 mm.