Hydraulic system and cylinders for bimetal snap-action disc punching machine.

Our customer's snap-action discs have proven themselves in numerous industrial and household applications all over the world: from toasters and industrial motors to temperature controllers and over-temperature protection. Thus, the Austrian WURMB GmbH, as a renowned manufacturing and automation specialist, regularly relies on our hydraulics solutions in the area of testing and production technology, and has done so for many years.

In this particular case, WURMB contracted us with designing and implementing a hydraulic system together with hydraulic cylinders for use in a bimetal snap-action-disc punching machine in Mexico. The special strip material as well as the small construction size placed high demands on the hydraulic design of the overall machine.

Bimetal snap-action discs are temperature-dependent switching elements, that actuate an electrical contact or trigger a mechanical action. The switch-on and switch-off temperatures are determined during production of the bimetal snap-action discs according to the specific application. The result is an economical, reliable and highly precise switching element.

The punching discs are made from heat-sensitive bimetal (thermostatic bimetal) and have a spherical bulge. A rise in temperature or reaching the upper snap temperature (TOS) creates an unstable state of stress, causing the discs to snap into the opposite curved shape. Cooling the bimetal snap-action discs to the lower snap temperature (TUS) causes the discs to react in exactly the opposite way. This allows quick and precise switch operations, so that high currents can safely be switched in electrical applications.

The hydraulic drive system for the punching machine is designed for cycle rates of up to 10,000 pieces per hour and extremely compact as per the machine manufacturer's specifications. Here again it was shown that the interaction of individual components increases process efficiency, especially in long-term use. For the hydraulic cylinder, a double acting tie rod cylinder was used for pressure ranges of up to 200 bar.

As a result of many years’ experience building this unit and continually optimizing the process during our cooperation, the hydraulic unit can now be optimally used as a modular system for installing numerous punching machines worldwide.