The Italian machinery integrator Cosma developed a production line for refrigerators for Whirlpool. When it comes to clinching refrigerator cabinets, Cosma is exploring new avenues: Instead of the usual hydraulic solution, two quartets of electromechanical ElectricDrive clinching tongs from TOX® PRESSOTECHNIK are used. The tongs for refrigerator production set the clinch points very quickly, repeatably and significantly more quietly.
Cosma S.R.L. based in Vigevano (PV) in Italy near Milan is one of the leading suppliers of customized production systems for appliances. The northern Italians are attaching particular value to the continuous further development of their products and close cooperation with their customers. Cosma is working with reputable manufacturers of kitchen appliances from all over the world, such as Whirlpool. The company holdings include such well-known brands as Kitchen Aid, Maytag and Bauknecht under its roof. For the Italian Whirlpool subsidiary, Cosma was tasked with creating a production line for refrigerators. True to their claim to innovation, the plant manufacturers broke new ground and focused on electromechanical systems instead of hydraulics.
The clinch procedure of TOX® PRESSOTECHNIK GmbH & Co. KG from Weingarten is ideal for joining the sheet metal of the refrigerator cabinet: it joins sheet metals reliably and quickly. Compared to joining with riveting or welding, when clinched, the painted surfaces and material structure remain intact. “So far, hydraulic tongs have been used for clinching the refrigerator cabinets”, says Marco Maffioli, who is the responsible Project Manager at Cosma. “For the new system, we chose a modern approach in the form of an electromechanical solution." It was clear from the start that this had to come from TOX® PRESSOTECHNIK. Both companies have been collaborating successfully for many years, and the products, service and inventiveness of the people in Upper Swabia already impressed with various previous projects. Due to the tight space conditions, Cosma used highly compact hydraulic solutions with special tong shapes in earlier systems. “However, Whirlpool is already successfully using other tongs with ElectricDrive drives from TOX® PRESSOTECHNIK, and was keen to use these drives here as well”, says Mr. Maffioli. “And as we were very tight for space again with the new system, we contacted our innovative partner again.” The engineers in Weingarten then developed a space-saving, fast, reliable and quiet electromechanical solution.
Four tongs join simultaneously
The concept was developed at the main plant in Weingarten, the Italian subsidiary TOX® PRESSOTECHNIK S.R.L. took over order processing for the electromechanical clinching tongs with punch, die and stripper. The tongs which have a reach of 40 and a tool opening of 50 millimeters provide the required 20 kilonewton press force. Each electromechanical TOX®-ElectricDrive EPMR servo drive provides the necessary force with 55 kilonewtons available. It enables strokes of up to 100 millimeters, a maximum speed of 160 millimeters per second and a positional repeatability of ± 0.01 millimeters. “We have taken the existing solution and optimized the ElectricDrive tongs respectively”, says Joachim Kreh from Technical Sales at TOX® PRESSOTECHNIK in Weingarten. “This resulted in two star-shaped clinching units consisting of four tongs each, which could be housed in a comparatively tight space.”
In the home position, the tongs are very close together. When a refrigerator cabinet reaches the clinching station, the tongs simultaneously move to the corners of the cabinet, set the four, four millimeter diameter clinch points, and join the painted, 0.45 millimeter thick sheet metals safely, quickly and reliably. The surface coating remains intact.
Furthermore, users benefit from the additional advantages of an electromechanical solution: it requires less energy, reduces environmental hazards and operates more quietly than hydraulic systems.
This relieves employees and increases occupational safety. “This is what we had hoped for”, says Mr. Maffioli. "We are very pleased with the collaboration. As always, TOX® PRESSOTECHNIK has supplied us with just the right solution.”