Special Focus : Robotics
per shift, enhances product quality and increases available capacity. The system comprises four robotic manufacturing cells capable of independent operation to allow maintenance and retooling to be undertaken without interrupting production. The system is designed to manufacture both 105mm and 155mm shells, with quick changeover routines embodied within the manufacturing processes. Each of the four Fanuc robots has a gripper to handle the shell either on its outside diameter or on the fuse bore. One cell includes an inspection system into which the robot loads and unloads machined shells. In another cell the robot picks and loads a driving band to a machined groove, which is then press-fitted.
Picking the best
It is not always a simple choice between Cartesian and Scara robots, and some applications can benefit from the use of both, as Ricoh found when it automated the assembly of toner cartridge shutters. Ricoh design engineer Matt Talbot says: “In the past, pick-and-place activity was done by pneumatics or by hand. Our experience was in small assembly jigs, so this project was a big learning curve.” Evershed Robotics suggested using a combination of a
Toshiba Machine TH650 Scara robot, a Toshiba Machine Cartesian robot to work with six bowl feeders, and a rotary index table (Fig. 1). This system assembles five components in 7.5 seconds and operates for three shifts per day, six days a week. After the parts are unloaded, they are stacked in trays before being moved to the next stage of the assembly line. Talbot comments: “The parts are quite delicate, and some
of the seals can be easily dislodged, so we need precision. The Scara robot uses sensitive parallel grippers to pick a raw body from a bowl feeder and place it on the table. Then, from the next unit clockwise around the table, it picks up a completed assembly. This assembly is then rotated through 90 degrees so it is in the correct position to be packed and secured. To do that process with pneumatics would have been a nightmare - we have 72 positions on the packing tray!” The packing trays are supported by a Cartesian robot, held by a vacuum attachment, and the 72 pockets in the tray are arranged in an eight-by-nine array (Fig. 2). Talbot adds: “Without the robots and the automation, the cost of doing this job manually would be very high, and the quality of the assembled parts could not be guaranteed.” On a somewhat larger scale, Kuka is playing a key role in
developing an innovative automated system for assembling complex aircraft structures in collaboration with Airbus. This system performs a variety of drilling and fastening tasks on the upper and lower wing covers of a lateral wing box demonstration unit being built at the Airbus facility in Filton. Kuka’s collaboration with Airbus is part of the €100 million,
EC-backed, Advanced Low Cost Aircraft Structures (Alcas) project that aims to identify new composite manufacturing and assembly strategies. One of the project’s main objectives is to improve efficiency by using a horizontal wing build philosophy instead of the conventional vertical manual method, which is a time-consuming and labour-intensive process. Markus Gruber, Kuka’s aerospace manager, says: “An
effective assembly system was devised that incorporates Kuka’s 18-tonne payload Omnimove, a mobile positioning device
that provides an alternative to using a crane for manoeuvring the carbon fibre wing covers into the jig. “The Omnimove is also used to position a pair of
platform-mounted Kuka robots for drilling holes in the lower wing cover. The assembly system also includes an identical pair of robots installed on a high-level gantry for the upper wing cover operation” (Fig. 3).
Adaptive guidance
Two of the robots are equipped with an adaptive guidance system for monitoring the accuracy of the drill head position, while the others feature a multi-function end effector that is designed to drill holes ranging in diameter from 6-22mm in materials up to 110mm thick. The design offers a choice of spindle systems for axial and orbital drilling capabilities, as well as other integrated features such as a fastener insertion facility and non-contact optical measurement probe.
Fig. 2. Ricoh’s assembly system outputs shutters to packing trays that are supported by a Cartesian robot, held by a vacuum attachment, enabling the tray’s 72 pockets to be accessed.
The integration of robots within intelligent manufacturing systems is something with which Mitsubishi Electric is also involved. Robot technology from Mitsubishi Electric now allows the economical use of flexible location robots in production environments; even during the movement of the robot arm, the robots react to changes in their environment and adapt their trajectory to suit. Cleverly, the self-positioning of the robot and the pinpointing of other moving objects within the workcell are achieved without the use of an image processing system. Moreover, the sensor-guided real-time control does not require elaborate programming. A key element of this flexible handling technology for
industrial automation is the VRFloor (Virtual Reality Floor) positioning system developed by Robotics Technology Leaders. This utilises passive markers with a constant identity, sensors for registering the marking points, and a control computer for analysing the information. The markers are fitted beneath the floor, and an air cushion provides for
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