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Process for producing silver-plated conductors via Electromagnetic pulse technology (EMPT)

IP.com Disclosure Number: IPCOM000237979D
Publication Date: 2014-Jul-24
Document File: 4 page(s) / 179K

Publishing Venue

The IP.com Prior Art Database

Related People

Markus RICHTER: INVENTOR [+2]

Abstract

Silver plated surfaces are used in electrical connections of high current applications in order to achieve low contact resistance. Yet, conventional silver-plating has drawbacks especially for bigger parts. In order to use silver plating for larger parts, such as elongated conductors, components of high voltage switching equipment, such as gas-filled high voltage switching equipment and the like, the disclosed concept comprises using silver plated connection parts only, that are welded or crimped onto the larger parts, such as conductors. Generally, nearly any conducting item of electrical equipment can be permanently equipped with a silver plated connection part when using the electromagnetic pulse technology technique (EMPT) as disclosed. The connections created with EMPT are mechanically very stable and robust and ensure a low resistivity.

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Alternative process for silver-plated parts via Electromagnetic pulse technology (EMPT)

By Markus Richter and Matthias Kudoke

Hereinafter, a method for equipping conductive metallic parts with silver-plated components is disclosed.

Electromagnetic forming (EM forming, or magneforming, or "electromagnetic pulse technology" - EMPT) is a type of high velocity, cold forming process for electrically conductive metals, most commonly copper, aluminum, and also steel and other alloys. A work piece is reshaped by high intensity pulsed magnetic fields that induce a current in the work piece and a corresponding repulsive magnetic field, rapidly repelling portions of the work piece. The work piece can be reshaped without any contact from a tool, although in some instances the piece may be pressed against a die or former.

A rapidly changing magnetic field induces a circulating electrical current within a nearby conductor through electromagnetic induction. The induced current creates a corresponding magnetic field around the conductor. Because of Lenz's Law, the magnetic fields created within the conductor and the work coil strongly repel each other. In practice, the metallic work piece to be fabricated is placed in proximity to a heavily constructed coil of wire (called the work coil). A huge pulse of current is forced through the work coil by rapidly discharging a high voltage capacitor bank using an ignitron or a spark gap as a switch. This creates a rapidly oscillating, ultra-strong electromagnetic field around the work coil.

The high work coil current (typically tens or hundreds of thousands of amperes) creates ultra- strong magnetic forces that easily overcome the yield strength of the metallic work piece, causing permanent deformation. The metal forming process occurs extremely quickly (typically tens of microseconds) and, because of the large forces, portions of the work piece undergo high acceleration reaching velocities of up to 300 m/s. The forming process is most often used to shrink or expand cylindrical tubing, but it can also form sheet metal by repelling the work piece onto a shaped die at a high velocity. High-quality joints can be formed, either by electromagnetic pulse crimping with a mechanical interlock or by electromagnetic pulse welding with a true metallurgical weld. Since the forming operation involves high acceleration and deceleration, mass of the work piece plays a critical role during the forming process. The process works best with good electrical conductors such as copper or aluminum, but it can be adapted to work with poorer conductors such as steel.

Application in power generation equipment and power distribution equipment

Silver-plated surfaces are used in electrical connections of high current applications in order to achieve low contact resistance, primarily to reduce losses and the accompanying heat production. Up to now, state of the art was to add silver-platings directly to conductors or connectors vi...