Pneumatic System Cuts Welding Cycle Time in Half
Every automobile requires a starter, and for decades, Bosch Auto Parts has been the world’s leading supplier of this key engine component. The company manufactures starters around the clock on seven assembly lines at its plant in Hildesheim, Germany.
Each line features 25 machines that surround a self-contained diffusion welding unit designed and built by GAteK (Gesellschaft für Automatisierungstechnik und Konstruktion). Thorsten Hoffmeister and Volker Thomas, managing directors at GAteK, have been designing automation systems for Bosch’s Hildesheim plant for three decades.
GAteK’s initial welding machines had three separate control processes for contact movement during welding. These three movements resulted in fairly long cycle times, acknowledges Hoffmeister. The supplier’s latest machine, however, uses a state-of-the art pneumatic system that cuts welding cycle time nearly in half.
“Compared with the [older] machines, we achieve a faster, more stable process, optimize weld quality and extend the machine service life,” says Hoffmeister. “This also cuts cycle times by 50 percent, [so] we reduced the number of [welding] machines [per line] from three to two.”
Welding begins after a metal framework is transported on workpiece pallets, aligned for detection, and brought into position by grippers. After welding, additional grippers return the framework to the pallets, which transport it to the next production step. Loading, welding and transporting are done quickly to maintain the line’s high production rate.
Four key components, all supplied by Aventics GmbH, optimize the welding system’s pneumatics. The ED electropneumatic pressure regulator combines control electronics, a pressure sensor and a direct drive (via proportional solenoids) into a single closed unit. Based on a target-to-actual-value comparison, the regulator immediately generates the necessary pressure change for process stability.
An AV03 valve ensures that the regulator delivers consistent pressure. GAteK selected the valve because it’s compact (due to a diagonally arranged spool) and features a flexible AES fieldbus control that supports all conventional systems and protocols.
Hoffmeister says that some pneumatic cylinders are equipped with a SM6 distance measuring sensor to determine their exact position and required travel time during each stroke. The sensor also provides feedback on wear, enabling Bosch to perform preventive maintenance while maintaining high-precision welding.
Finally, the pneumatics system is equipped with AS3 maintenance units that keep compressed air quality high and prevent air waste. Equally important, notes Thomas, the units increase machine safety. Their integrated 3/2 shut-off valves provide safe ventilation and exhaust, and they switch off redundantly in an emergency.
Founded in 2001, GAteK provides engineering services and builds custom machines for tool optimization, small batch production and self-contained manufacturing cells (including control technology). Bosch remains impressed with GAteK after many years, and has asked the company to develop a new diffusion welding system.
“It is very flexible and viable for the long term,” says Thomas of the system being built. “We can keep the [same] concept, even though we only have [basic information about] the new type of starter to be produced on the line.”
For more information on pneumatic systems, call 859-254-8031 or visit www.aventics.com/us/en.