Page 27 - Welding Robots Technology, System Issues, and Applications

11
Introduction and Overview

tubular in cross section with the fluxing agents on the inside. The process was
called Dualshield®, which indicated that external shielding gas was utilized, as
well as the gas produced by the flux in the core of the wire, for arc shielding. This
process, invented by Bernard, was announced in 1954, but was patented in 1957,
when the National Cylinder Gas Company reintroduced it.

In 1959, an inside-outside electrode was produced which did not require external
gas shielding. The absence of shielding gas gave the process popularity for non-
critical work. This process was named Innershield®.

The electroslag welding process was announced by the Soviets at the Brussels
World Fair in Belgium in 1958. It had been used in the Soviet Union since 1951,
but was based on work done in the United States by R.K. Hopkins, who was
granted patents in 1940. The Hopkins process was never used to a very great
degree for joining. The process was perfected and equipment was developed at the
Paton Institute Laboratory in Kiev, Ukraine, and also at the Welding Research
Laboratory in Bratislava, Czechoslovakia. The first production use in the U.S. was
at the Electromotive Division of the General Motors Corporation in Chicago,
where it was called the Electro-molding process. It was announced in December
1959 for the fabrication of welded diesel engine blocks. The process, and its
variation using a consumable guide tube, is used for welding thicker materials.

The Arcos Corporation introduced another vertical welding method, called
Electrogas, in 1961. It utilized equipment developed for electroslag welding, but
employed a flux-cored electrode wire and an externally supplied gas shield. It is an
open arc process since a slag bath is not involved. A newer development uses self-
shielding electrode wires and a variation uses solid wire but with gas shielding.
These methods allow the welding of thinner materials than can be welded with the
electroslag process.

Robert F. Gage invented plasma arc welding in 1957. This process uses a
constricted arc or an arc through an orifice, which creates an arc plasma that has a
higher temperature than the tungsten arc. It is also used for metal spraying and for
cutting.

The electron beam welding process, which uses a focused beam of electrons as a
heat source in a vacuum chamber, was developed in France. J.A. Stohr of the
French Atomic Energy Commission made the first public disclosure of the process
on November 23, 1957. In the United States, the automotive and aircraft engine
industries are the major users of electron beam welding.

Friction welding, which uses rotational speed and upset pressure to provide friction
heat, was developed in the Soviet Union. It is a specialized process and has
applications only where a sufficient volume of similar parts is to be welded
because of the initial expense for equipment and tooling. This process is called
inertia welding.