With help from Festo, Aston Martin’s engineering task force developed a special machine which quickly, efficiently, and safely releases the bedplate from the engine block of the Aston Martin V8, rotates it and sets it down. Skilfully crafted, the semi-automatic system is designed to provide the greatest protection possible at the Aston Martin Engine Plant in Cologne.
Power needs precision
A look at the technical details of the system reveals why this latest development is so special. The bedplate lies under the engine block of the Aston Martin V8 and together they surround the crankshaft. During driving, this transmits a maximum power of 430 hp at 7300 rpm to the transmission system of the V8 Vantage S. This is sufficient for a top speed of 305 km/hr and a brutish pulling power of 490 Nm at 5000 rpm.
Precision is essential, and the bedplate and engine block must be tightly connected during machining of the crankshaft bearing channel. However, during subsequent processing the workpieces need to be separated again as coolant residue could cause a problem by getting in between the two aluminium workpieces and into the mechanical guide sleeves, causing unwanted adhesion.
Fluidic muscles
The previous system mechanically pulled the bedplate from the engine block on the linear axis. It then had to be rotated manually through 180° and set down sideways on the workpiece carrier. This was no small feat since the load bearing crankshaft bed weighed 14 kg. When rotating and setting down, there was a risk of injury from the sharp outer edges of the cast aluminium part.
The new system makes it much easier. It does not pull the bedplate off; instead it shakes it free. Festo fast switching valves oscillate a total of four Festo fluidic muscles at 2 Hz, gently but forcefully releasing the bedplate. The fluidic muscle is a diaphragm contraction system, in other words a tube that shortens under pressure. It consists of a hollow elastomer cylinder with embedded aramid fibres.
When the fluidic muscle is pressurised, its diameter increases and its length contracts in a defined manner. This enables a flowing, elastic movement.
The fluidic muscle enables motion sequences that approximate human movements in terms of kinematics, speed, force and finesse. It can exert 10 times the force of a comparably sized cylinder, is very robust, and can be used under extreme conditions.
Exceptional achievement
By simultaneously pressing the start levers, the operator can gently but forcefully set the system in motion.
It lowers and attaches itself to the bedplate using this patent-pending technology. The operator then switches the lever pair, the inner machine unit lifts up slightly, and a uniform vibration releases the bedplate. Within less than a second it floats unattached above the massive Aston Martin V8 engine block. The bedplate is automatically rotated 180° and reveals its interior. At this point, the operator presses the start lever again and with just a little pressure moves the machine – which weighs 270 kg – sideways, where the bedplate is set down on a workpiece carrier.
Control system on board
Another important function is weight compensation and this is fulfilled by a standard Festo cylinder. It supports operators when lifting and lowering loads and ensures that they can always operate the semi-automatic machine with the same low level of force. In this system a CPX/MPA valve terminal safely and swiftly controls a total of 22 pneumatic and electric actuators. The valve terminal is attached to the rear side of the special machine and travels along with the system during all the work steps. As the pneumatic control can be attached directly to the machine, only one slim Profibus cable is connected to the control cabinet.
Models save time
It took about 18 months to develop this innovative machine. Following the brainstorming and basic design phases, Festo was included as a partner early on in the development phase to provide advice on pneumatic solutions. The aim was to create a small, compact and especially lightweight design suited to quick motion sequences. Festo’s virtual 2D and 3D models made the development phase shorter and easier as the development team was able to download these models over the Internet and integrate them into their own design plans.
Festo FluidDraw software was used to create the circuit diagrams straight away. This allowed the team to create a system combining technical finesse and ease of use, so achieving a high level of acceptance by operators. New machines with improved safety systems are only successful if the operators are also convinced that the improvements are beneficial. This required an ergonomic adaptation to the operators’ needs. It was possible to make this precise adaptation by using sophisticated pneumatics software from Festo in the run up to the system’s production.
For more information contact Tracey Swart, Festo, +27 (0)11 971 5500, [email protected], www.festo.co.za
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