Assembly solution for plastic mouldings uses a Mitsubishi Electric RV-E2 robot

Citation

(1999), "Assembly solution for plastic mouldings uses a Mitsubishi Electric RV-E2 robot", Industrial Robot, Vol. 26 No. 3. https://doi.org/10.1108/ir.1999.04926caf.008

Assembly solution for plastic mouldings uses a Mitsubishi Electric RV-E2 robot

Keywords Assembly, Robots

Mitsubishi robotics system integrators, Barr and Paatz Ltd, have developed a new automation solution for a plastic moulding assembly project using a Mitsubishi RV-E2 six axis small industrial robot. The new system, developed for ITW Fastex Engineered Components, assembles a spring release mechanism into the plastic sleeves which hold head restraints into car seats. Each assembly comprises three pieces, the main sleeve which fits into the seat back, a bar spring to hold the head restraint in place and a push button to release it. The main sleeve and push button are different for left and right hand fittings and the tube heads are angled to fit the seat. The RV-E's unique combination of speed and accuracy makes the complex assembly possible in a cycle time of only five seconds (see Plate 7).

Plate 7 Barr and Paatz use a Mitsubishi RV-E2 six axis industrial robot to achieve a cycle time of only five seconds for a complex plastic moulding assembly project

The sleeves are fed into a vibratory bowl feed hopper as mixed left and right fittings and as each is presented to the robot a vision system recognises it as right or left and registers the angle of presentation. This information is passed to the robot which collects a spring and assembles it with the appropriately handed push button. This involves tilting the spring to engage a small hook on one side of the button then compressing the spring and turning it to locate a second hook. This action requires precision to within 0.lmm. The sprung button assembly is then located into a slot in the sleeve head and pushed home.

The robot finally presents the completed assembly to a second vision system which checks that the spring is correctly aligned and the button correctly installed. Correct assemblies are then sorted into a left or right handed hopper as appropriate and any rejects are dropped straight down. Cycle time for the assembly of each unit is five seconds. The Barr and Paatz assembly unit will replace a repetitive manual operation on which operators usually work for only a few weeks. This will free operators for more skilled and interesting tasks.

The RV-E robot can take payloads of up to 3kg, move them through five or six axes and place them with a repeatability of 0.03mm at speeds of up to 6m/sec. It uses AC servo motors fitted with absolute position encoders. These are not only responsible for the exceptional repeatability of the system but also ensure that the robot can resume operation without needing a return to home operation after a power failure.

For further information contact: Mitsubishi Electric Ltd, Industrial Automation Systems Division UK, Travellers Lane, Hatfield, Herts AL10 8XB, UK. Tel: +44 (0) 1707 276100; Fax: +44 (0) 1707 278555.