issue: July 2003 APPLIANCE Magazine Motor Technology Lamination Die Technology	Share  Printable format  Email this Article  Search
Varilok� is a proprietary lamination die technology that is said to change the rules by which laminated stacks can be designed.

"The main attribute of Varilok is that it grants the product designer heretofore impossible control of laminated stack geometry in the Z axis. That may sound simple, but that allows limitless enhanced part features," explains Tom Neuenschwander, vice president of Technology. "Perhaps the need is to fit more power into a confined space. Maybe integral stator core mounting features would help accomplish that. The appliance engineer can design the electromagnetic core to conform more closely to the allowable space, available mounting surfaces, and for better control of secondary processes such as winding."

Varilok permits the stamping, collating, and interlocking of laminations of multiple outside perimeters into assembled stacks inside the die. The technology is said to be perfectly suited to the high-volume production of coil-on-plug ignition cores, specifically the cylindrically shaped laminated parts often referred to as "pencil cores." However, notes Mr. Neuenschwander, Varilok's ability to produce previously impossible 3D geometric shapes, with laminations stamped and assembled in the die, extends to an infinite variety of parts.

"Varilok is applicable to electric motor design, so it is, by extension, applicable to any appliance incorporating a motor drive for any purpose," says Mr. Neuenschwander. "The technology, however, will also apply to any appliance utilizing other types of electromagnetic devices as well. These might include electrically driven linear or rotary actuation, solenoids, generators, and transformers."

According to Mr. Neuenschwander, all the possible variations are derived from the primary Varilok principle—the capability of stamping laminations of varying outside configurations and interlocking them together in the die. The variety of lamination shapes is created by a series of selectively actuable punches. The number of punches, and thus the number of different laminations permitted in the stack, is limited only by the linear space available (in the feed direction) in the press and die. Placing the contouring punches/die openings in a transversely moving sub-die(s) can mitigate even that limitation. Precisely positioned by servomotor-driven lead screws, the sub-die stamps each lamination's contour in the desired sequence.

As the strip advances through the progressive die, the contour of each individual lamination is selectively trimmed to shape, and the entire operation is sequenced so that each lamination arrives at the assembly, or choke station, in the desired order. The choke station is designed to precisely locate each subsequent lamination in relation to the previous lam of the stack-in-process. All the while the choke is holding that stack and a number of previously completed stacks in an interference fit, thus providing resistance against the incoming lamination—resistance that is necessary to facilitate the interlocking operation.