Magnetic folding machines for sheet metal introduced at MACH 2008

The design is open-ended with unlimited throat depth, allowing the production of large, complex components. Six models are available with maximum bending length from 625 mm up to 3.2 metres. Full-length bending capacity in mild steel is up to 1.6 mm thick, or 1.0 mm in stainless steel. Even aluminium or other non-ferrous materials may be processed as the magnetic clamping force passes through them and pulls the clamp bar down onto the sheet.

In essence, the machine is a long electromagnet with a steel clamp bar located above it. The only power needed for operation is a 240-volt, single-phase supply. At the press of a button, a sheet metal workpiece is clamped between the bar and magnet by a force of several tonnes.

A bend is formed around the front edge of the bar by manually pulling the handle of the rotating the beam, which is mounted on special hinges at the front of the machine. The angle of bend is read from a graduated scale. Returning the handle to its original position automatically releases the clamping force, whereupon the folded workpiece is either removed or repositioned for another bend.

If a large lift is required, such as to allow the insertion of a previously bent workpiece, the clamp bar may be manually lifted to any required height. Conveniently located adjusters at each end of the bar allow easy adjustment of the bend radius for various workpieces thicknesses. If the rated capacity of Electrabrake is exceeded, the bar immediately releases to avoid damaging the machine.

Magnetic clamping means that bending loads are taken exactly at the point where they are generated; forces do not have to be transferred to support structures at the ends of the machine. This in turn means that the clamping member does not need much structural mass, so it can be made more compact and does not obstruct the bending operation. Indeed, the thickness of the clamp bar is determined only by the requirement for it to carry sufficient magnetic flux, and not at all by structural considerations.

The centreless compound hinges, developed especially for Electrabrake, are distributed along the length of the bending beam and thus, like the clamp bar, take bending loads close to where they are generated. The combined effect of magnetic clamping with the special centreless hinges means that Electrabrake is very compact and has a high strength-to-weight ratio. Machines can be ganged end to end for bending long workpieces.

Accessories such as backstops for locating the workpiece, and a set of short clamp bars that plug together are standard with all models. Further accessories include narrow clamp bars, slotted bars for forming shallow boxes more quickly, foot-switches, and power shears with a guide for straight, distortion-free cutting.

Special tooling can be quickly made by the customer from pieces of steel to help fold difficult shapes; and for production work the standard clamp bar can be replaced by specialised tooling. Operator safety is enhanced by a two-handed electrical interlock that ensures a safe pre-clamping force is applied before full clamping occurs.