Bosch Rexroth is supplying the hydraulic systems to operate the 16 platforms required for two wing jigs for the Airbus A400M multi-role military transport. The aircraft’s wing boxes are 23 m long and 4 m wide, and each has a mass of 3 t. They are believed to be the largest carbon-fiber-reinforced plastic composite wings ever made.
The U.S. company Electroimpact is manufacturing the jigs, which have been supplied to the Airbus Wing Manufacturing facility in the U.K. Rexroth has also supplied hydraulic systems for use with ancillary equipment associated with the jigs.
The jigs incorporate two elevating platforms on each side of the wing, one with a lift of 3.5 m, the other of 2.5 m. An essential requirement is that the motion of the cylinders used to lift the platforms be accurately synchronized to ensure they remain precisely level under all operating conditions. Rexroth produced cylinder and valve block assemblies compatible with Electroimpact’s existing design for receivers. These are chambers sunk into the concrete floor below the elevating platforms to accommodate the lifting assemblies to enable the platforms to be lowered to the floor.
The platforms have a “worst-case” load of 13 t, and each is driven by two cylinders. Additional guidance and support for the lifting system is provided by linear slides, and the cylinders are fitted with linear transducers to provide the accurate positional feedback needed for the control system to maintain synchronism, according to Rexroth. The cylinders are fitted with safety manifold blocks to prevent uncommanded descent of the platforms.
The cylinders have a maximum working pressure of 210 bar. They have seals compatible with Castrol Anvol SWX FM hydraulic fluid that incorporate fire-resistant properties. Flexible gaiters are used to protect the lifting mechanism from the abrasive effects of carbon-fiber dust and swarf. Power for the lifting system comes from a 2000-L hydraulic power unit incorporating two 55-kW electrically driven pumps, each delivering 220 L/min at 135 bar. To maximize energy efficiency, the pumps are fitted with pressure control arranged so that they deliver only the pressure and flow necessary to satisfy the current demand on the system.
The control system for the elevating platforms is built around the Rexroth HNC100 digital axis controllers used in a closed-loop configuration and arranged to provide the accurate synchronization needed between the two cylinders used on each platform.