Electromechanical Clinching Tongs by TOX PRESSOTECHNIK; Ideal Solution for Whirlpool commissioned by COSMA


Whirlpool commissioned Cosma, an Italian machinery integrator, to design a refrigerator production line. Cosma is pursuing new possibilities when it comes to securing refrigerator cabinets: Two quartets of electromechanical ElectricDrive clinching tongs from TOX® PRESSOTECHNIK are utilised instead of the traditional hydraulic approach. The tongs used in refrigerator production establish the clinch points much more swiftly, consistently, and softly.

Cosma S.R.L., based in Vigevano near Milan, is one of the main suppliers of bespoke appliance manufacturing systems. Northern Italians place a premium on product innovation and close customer collaboration. Cosma collaborates with famous kitchen equipment manufacturers from throughout the world, such as Whirlpool. Under the company’s umbrella are well-known brands like Kitchen Aid, Maytag, and Bauknecht. Cosma was charged with developing a refrigerator production line for a Whirlpool subsidiary in Italy. True to their boast of innovation, the plant manufacturers forayed into uncharted territory by focusing on electromechanical systems rather than hydraulics.

Marco Maffioli

The clinch procedure from Weingarten’s TOX® PRESSOTECHNIK GmbH & Co. KG is ideal for joining refrigerator cabinet sheet metal: it joins sheet metals reliably and quickly. When clasped, as opposed to riveting or welding, the painted surfaces and material structure stay intact. “Until now, the refrigerator cabinets have been clinched with hydraulic tongs,” says Marco Maffioli, Cosma’s Project Manager. “We picked a modern approach in the form of an electromechanical solution for the new system. This had to come from TOX® PRESSOTECHNIK, it was obvious from the outset."

Both enterprises have worked together effectively for many years, and the people of Upper Swabia have already been impressed with their products, service, and innovation in prior initiatives. Cosma utilised highly small hydraulic solutions with specific tong forms in older systems due to the severe space constraints. “However, Whirlpool has had experience with other tongs using TOX® PRESSOTECHNIK ElectricDrive drives, and we were eager to apply these drives here as well,” Mr. Maffioli continues. “And, because we were running out of space with the new system, we reached out to our creative partner once more.” Weingarten engineers then devised a space-saving, rapid, dependable, and noise-free electromechanical solution.

The design was created at the main facility in Weingarten, and order processing for the electromechanical clinching tongs with punch, die, and stripper was taken up by the Italian subsidiary TOX® PRESSOTECHNIK S.R.L. The tongs, with a reach of 40 millimetres and a tool opening of 50 millimetres, produce the needed push force of 20 kilonewtons. With 55 kilonewtons available, each electromechanical TOX®-ElectricDrive EPMR servo drive provides the required force.

It has a stroke length of up to 100 millimetres, a top speed of 160 millimetres per second, and positional repeatability of fewer than 0.01 millimetres. “We took the existing system and optimised the ElectricDrive tongs,” says Joachim Kreh of TOX® PRESSOTECHNIK in Weingarten, who works in Technical Sales. “As a consequence, two star-shaped clinching units with four tongs each were created, which could be housed in a relatively small space.”

The tongs are fairly close together in the home position. When a refrigerator cabinet arrives at the clinching station, the tongs move to the cabinet’s corners at the same time, setting the four four-millimetre-diameter clinch points and safely, rapidly, and reliably joining the painted, 0.45-millimetre-thick sheet metals. The surface finish is still intact.

Furthermore, customers benefit from the extra advantages of an electromechanical solution: it consumes less energy, poses fewer environmental risks, and is quieter than hydraulic systems. Employees are relieved, and workplace safety is improved. Mr Maffioli comments, “This is exactly what we had hoped for.” “The collaboration has been a great success for us.” TOX® PRESSOTECHNIK, as usual, has provided us with the ideal solution.”


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