Keywords
Citation
(1999), "Vision system in robot cells eliminates manual handling of windscreens", Assembly Automation, Vol. 19 No. 3. https://doi.org/10.1108/aa.1999.03319caf.005
Publisher
:Emerald Group Publishing Limited
Copyright © 1999, MCB UP Limited
Vision system in robot cells eliminates manual handling of windscreens
Vision system in robot cells eliminates manual handling of windscreens
Keywords: Machine vision, Robots, Automotive
Of the 35 different types of car windscreen manufactured by Pilkington Automotive in Birmingham, ten need mirror bosses affixed to the inner surface. Until recently, this was carried out manually in a 50 second cycle, but the job has now been integrated into existing Comau robotic handling cells in which the cycle time has been extended by only six seconds.
Production throughput is consequently higher and a tedious manual job has been eliminated. Most important, however, has been the significant reduction in costly scrap caused by damage to windscreen surfaces and edges which is the inevitable result of manual handling. The improvement was immediately apparent on the first screens through the cells, destined for Range Rover and Jaguar (see Plate 2).
The two identical robotic cells originally entered service in 1996 to take laminated windscreens off assembly line conveyors, invert them and palletise them ready for autoclaving. As part of the cycle, the robot lifts the screen using four suction cup grippers and presents one edge to a station where an aluminium spacer clip is added. Its purpose is to allow the screens to be palletised vertically without the top edged clashing together.
Plate 2 One of the Comau robotic cells in use at Pilkington Automotive, showing a car windscreen being presented for mirror boss and spacer clip application prior to being palletised vertically
Senior electrical design engineer, Steve Brown, recognised that an extra, simultaneous operation could be added at this point, namely pressing on the self-adhesive mirror boss. However, whereas spacer clip attachment is an open-tolerance application, the presentation of a printed patch on the curved windscreen to the mirror boss required a level of precision which was only possible with a vision system.
This was duly installed in both cells and the extra operation incorporated very successfully, with only a small increase in glass-to-glass cycle time from 16 to 22 seconds. Accuracy of alignment between windscreen patch and boss is þ 0.3mm in X and Y and þ0.1 degree in the angle of presentation.
Each Comau C3G-900 controller uploads co-ordinate data on these three axis positions from the vision system and displays them on a pendant-mounted user screen. Any deviation from tolerance may thus be easily observed, whilst correction is automatic via live offsets.
The robots themselves, which operate 24 hours a day 6ø days a week, are Comau six-axis CNC Smart 3.125 models capable of carrying 125kg on the wrist.
Three further Comau robots are in use further down the windscreen production line, after the autoclave. One depalletises the screens and the other two present them to finishing pods for edge finishing prior to delivery.
Contact John D'Angelillo, UK manager, Comau UK Ltd, Unit 3, Hortonwood 32, Telford, Shropshire, TF1 4EU. Tel: +44 (0)1952 670396; Fax: +44 (0)1952 670398.