The only wheelbarrow manufacturer still making all its parts in the UK, The Walsall Wheelbarrow Company’s production process has five main stages: pan pressing, tube bending, welding, powder coating and assembly.
Due to business expansion, the hydraulically powered, operator-controlled tube bending machines used to produce the company’s wheelbarrow frames had become a production bottleneck. As part of a drive towards highly automated production, the business decided to look at using a twin-headed, all-electric tube bender – a machine that would accelerate the manufacture of the symmetrical shapes used in wheelbarrow construction.
Such a move would increase the precision and repeatability of frame bending and eliminate the small differences in bend angles that can occur due to drift on hydraulic machines – differences that can sometimes cause problems in the downstream process stages.
Unison Ltd designed a solution based around one of its highly proven 5-axis, all-electric Breeze ‘twinhead’ tube bending machines. With closed-loop motion control, the Breeze machine ensures that all frames are bent precisely with complete repeatably. As a result of eliminating the small differences in bend angles that can happen when using hydraulic machines, minor issues with subsequent manual welding and assembly are also eliminated. To further optimise bending speed, Unison also designed an automated cell around the tube bender, which included a tube bundle loader, a multifunction processing station, an intermediate dual-arm loader, and an articulated robotic handler.
Once the work cell’s hopper is filled and the program selected, the cell operates completely automatically. The loader feeds tubes individually to the multifunction station, which performs weld seam detection, tube orientation and centralising, and all-electric hole punching. The tube is then transferred to the bender by the dual-arm loader and, after bending, is removed by the handler and placed on a storage rack. Hole punching and bending functions take place simultaneously. This overlap decreases cycle time – allowing the cell to bend more than two frames a minute.
The Unison work cell handles almost the same volume as the wheelbarrow manufacturer’s previous three hydraulic twin-head benders, but with much lower energy consumption. As the Unison work cell also punches holes, The Walsall Wheelbarrow Company has been able to redeploy staff and accelerate the development of new products. The reliability of the production cell has also improved process flow, helping to expedite the welding and powder coating stages.
