Contact-free feed
The contact-free feed is an innovative technology for forming machines ( pressing , punching ). It combines the advantages of roller and gripper feeds. A magnetic traveling wave generates the feed force without contact on the surface of the slit strip . This clearly exceeds the feed force of mechanical automatic feeders. Due to the high feed force and the low accelerated mass, the slit strip is fed into the press faster and more gently. The forming time and / or the number of strokes can be increased due to the small feed angle.
The non-contact feed technology induces a current in the slit strip with a traveling magnetic wave in the feed direction. In interaction with the current and the traveling magnetic field, a Lorentz force acts on the surface of the slit strip in the feed direction . The traveling field is generated with energized coils, which are embedded in an iron yoke to increase the air gap induction.
Investigations on a prototype showed that slit strips with a strip weight of 3 kg are accelerated with a feed force of more than 800 N. Without mechanical contact or stress, slit strips are fed gently and quickly into the press.
Electrically conductive slit strips, such as B. aluminum, copper, stainless steel or steel. By adapting the traveling wave frequency, the same feed force is achieved in the different materials. The feed force is proportional to the surface of the slit strip and increases with larger widths of the slit strip. The feed force does not increase with increasing sheet thickness. These properties correspond to those of roller feeds.
The slit strip is neither significantly heated nor permanently magnetized. The technology also enables the slit strip to be heated inductively quickly. The feed length is not limited. Coated, varnished, textured and sensitive slit strips are gently, quickly and precisely positioned in the tool. The smaller footprint of the contact-free feed enables it to be placed directly in the press work area. The result is improved positioning of the slit strip in the tool due to the shorter free slit strip length.
Energy consumption and maintenance effort
The clamping takes place with the control method of the traveling wave, which sets the rest position of the slit strip. "Ventilation" takes place by simply switching off the traveling wave in a few milliseconds. Accordingly, the hydraulic or pneumatic auxiliary drives required for roller and gripper feeds are not required. Apart from the slit strip, there are no moving parts in the non-contact feed. Slit strips are fed into the press with little energy consumption and significantly less wear, which significantly reduces downtimes, maintenance intervals and energy costs.