Electric heating – Metal heating – By arc
Reexamination Certificate
2001-09-28
2004-02-10
Elve, M. Alexandra (Department: 1725)
Electric heating
Metal heating
By arc
C219S137430
Reexamination Certificate
active
06689988
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to welding systems, and particularly to a wire-feed welding gun having a tip to guide wire through the welding gun.
BACKGROUND OF THE INVENTION
Welding is a method of joining pieces of metal together into one solid piece. Welding guns are used in a number of different types of welding. For example, welding guns are typically used in arc welding. An arc welding system typically comprises an electric power supply coupled to a welding gun that houses an electrode. The electric power supply typically includes a conductive cable and a clamp for securing the conductive cable to the metal piece to be welded. The electrode in the welding handle, along with the metal piece and conductive cable, completes an electrical circuit with the power supply when the electrode is placed against the metal piece. The contact between the electrode and the metal piece produces an electric arc between the electrode and the metal piece. The heat of the electric arc is concentrated on the metal piece, or pieces, to be joined. The heat of the arc melts the metal piece, or pieces. A filler material is added to the molten metal. The molten mass then cools and solidifies, joining the metal pieces.
MIG (Metal Inert Gas) welding is one type of arc welding. MIG welding is also referred to as “wire-feed” or GMAW (Gas Metal Arc Welding). In MIG welding, a metal wire is used as the electrode to produce the arc. The wire is shielded by an inert gas and the metal wire acts as the filler for the weld. The inert gas is used to shield the electric arc from outside contaminants and gases that may react with the weld. Non-inert gases, such as CO
2
, also are used in MIG welding.
Typically, the wire and gas are fed through a hand-held welding gun. The wire and gas are fed to the welding gun from a wire feeder. The wire feeder is, in turn, coupled to a power source and a source of gas, such as a gas cylinder. The wire is directed to a workpiece through a tip in the welding gun. The welding gun, typically, has a switch, or trigger, that is coupled to the wire feeder. When the trigger is operated, gas and wire are fed through the tip towards the target.
Submerged arc welding is another type of arc welding. In submerged arc welding, a granular flux, rather than a gas, is used. The flux is fed through a wire feeder, along with electricity from the power source. The wire is used to complete an electrical circuit and creates an arc to melt the object metal. In submerged arc welding, the actual point of metal fusion and the arc are submerged within the flux. The flux is a granular composition of chemical and metallic materials that shields the arc. The granular flux is continuously deposited just ahead of the electrode. The electrical current melts the electrode to form the weld puddle. The portion of the flux that is adjacent to the electrode tip and the puddle melts, forming a slag layer that refines the weld and excludes air. As in MIG welding, the wire is fed through a tip within the welding gun. The welding gun, typically, has a switch, or trigger, that is coupled to the wire feeder. When the trigger is operated, the flux and wire are fed through the tip towards the target.
For many years, the tips for MIG and SMAW welding guns have been made from copper, or a copper alloy. Copper and copper alloys are very good at conducting electrical current and heat. They also have a fair resistance to wear characteristics. The alloys of copper tend to enhance the wear characteristics but very often are difficult to machine and are relatively expensive. In addition, the drawing process to produce the bar stock from which the tips are made tends to leave an irregular finish on the interior diameter of the tip, which can enhance wear of the tip as the wire feeds through. Furthermore, the welding gun produces a significant amount of weld spatter (small droplets of molten metal) that tends to adhere to the face of the tip, building up a deposit of weld spatter on the face of the tip. Eventually, the weld spatter breaks away, taking a piece of the tip with it, thereby eroding the tip.
There exists then a need for a welding gun that has an improved tip that will prevent, or minimize, the buildup of weld spatter on the tip. Furthermore, there is a need for an improved method of making a tip to improve the ability of the tip to withstand wear.
SUMMARY OF THE INVENTION
The present technique may solve one or more of the problems outlined above. According to one aspect of the present technique, a novel wire-feed welding system is featured. The welding system features an electrical power source, a wire feeder having a wire electrically coupleable to the electrical power source; and a welding gun adapted to receive the wire from the wire feeder. The welding gun has a tip to guide the wire through the welding gun. The tip has a body and a passage through the body. The body has an outer surface layer of electrolytic nickel and the passage has an outer surface layer of electroless nickel.
According to another aspect of the present technique, a tip for a wire-feed welding system is featured. The tip has a first surface layer disposed over a first portion of the tip. The first surface layer comprises electrolytic nickel. The tip also has a second surface layer disposed over a second portion of the tip. The second surface layer comprises electroless nickel.
According to yet another aspect of the present technique, a method for adapting a tip for use with a welding gun is featured. The method comprises the act of applying a first layer of nickel to the tip in an electroless process. The method also comprises the act of subsequently applying a second layer of nickel to the tip in an electrolytic process.
According to still yet another technique, a method for assembling a wire-feed welding gun is featured. The method comprises the act of adapting a tip to have a passageway extending through the tip. The method also comprises the act of applying a first layer of electroless nickel to the tip. The method further comprises the act of subsequently applying a second layer of electrolytic nickel to the tip. The method also comprises assembling the welding gun with the tip.
REFERENCES:
patent: 4733052 (1988-03-01), Nilsson et al.
patent: 4766349 (1988-08-01), Johansson et al.
patent: 4904843 (1990-02-01), Hori et al.
patent: 4947024 (1990-08-01), Anderson
patent: 5205469 (1993-04-01), Capitanescu
patent: 6093907 (2000-07-01), Hidaka
Niemann Douglas J.
Wakeman Robert W.
Elve M. Alexandra
Fletcher Yoder
Illinois Tool Works Inc.
McHenry Kevin
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