For fast fasteners, see Scara

Citation

(1999), "For fast fasteners, see Scara", Assembly Automation, Vol. 19 No. 4. https://doi.org/10.1108/aa.1999.03319daf.009

For fast fasteners, see Scara

Keywords Assembly, Robots

The latest project undertaken by Toshiba and systems integrator, Evershed Robotics, technical partners for 15 years, is a system for machining lockable fasteners for car panels.

The machine comprises four twin drill heads arranged either side of a Toshiba SR-504HSP Scara robot. A wide range of fasteners, measuring between 9.5 and 50mm in length, are introduced to the drilling area from a bowl feeder via an escapement mechanism that presents them in rough orientation. Working in conjunction with a simple recognition system, the Scara robot picks the fastener up and then performs extremely fast, accurate, correctly orientated placements to any one of the free drill heads. Once the fasteners have been machined, they are automatically ejected into an output tray.

Evershed designed the system with flexibility in mind, using one, two, three or all four drills in series, according to throughput requirements. At full output, the machine is capable of producing a finished fastener every four seconds and can handle up to 15 different fastener types (Plate 9).

Plate 9 The ultra high-speed, four-axis Toshiba SR-504HSP Scara robot helps this Evershed Robotics fastener machining system

With its very high-speed four-axis capability, the Toshiba Scara suits such pick-and-place functions ideally. The robot's SR7000 series controller gives the robot the ability to pick an object up from a moving conveyor, or receive input from a recognition device. It can then transfer it extremely quickly to the target position with repeatability accuracy of þ0.02mm.

Toshiba's Scara robots have arm reaches ranging from 504mm to 1,054mm. The SR-654HSP has achieved record-breaking traversing rates of 600mm in 0.93 seconds, carrying a 2kg payload while, even with a 5kg payload, the robot achieved the same distance in just 1.16 seconds. The reinforced arm can handle up to 20kg at half-speed, or 10kg at full speed.

The SR7000 robot controller is capable of simultaneously processing input and output signals during robot motion, so no time is wasted waiting for signal processing to be completed. The controller uses absolute encoder feedback rather than incremental signals, thereby obviating the need to implement a zero return on start-up following a shut-down.

There are options for PTP, short-cut, linear interpolation and circular interpolation motion modes. With a total memory capacity of 6,400 points (12,800 steps), the controller also offers a multitask function, allowing a maximum of four tasks in any one programming. The mechanical movements of the Scara robots are controlled using Toshiba's own revolutionary digital servo motors, amplifiers and motion controllers.

For further information contact: Mr Nigel Knapp, Toshiba International (Europe) Limited, 1 Roundwood Avenue, Stockley Park, Uxbridge, Middlesex UB11 1AR. Tel: +44 (0) 181 756 6000; Fax: +44 (0) 181 848 4969.