Welding gun spatter shield

A welding gun spatter shield for insertion in the sleeve opening of a welding gun that prevents contact of spatter with the welding gun components and that prevents the accumulation of spatter on the welding gun. The shield is a body that fits within or over the opening of the welding gun sleeve and fills the opening forming a barrier beyond which the spatter may not pass. The body has a wire feed bore extending axially therethrough to permit the welding wire to extend therethrough. Further, the body includes communication passageways that permit the inert gas to pass through the body in an axial direction. The welding gun spatter shield uses either a friction fit or a retaining ring to maintain the body attached to the sleeve.

BACKGROUND OF THE INVENTION 
1. Field of Invention 
This invention relates to a spatter shield for a welding gun. More 
specifically, it is directed to a low cost insert that eliminates spatter 
from accumulating on the welding gun. 
In Metal Inert Gas (MIG) welding, also known as Gas Metal Arc Welding, a 
continuous feed of welding wire feeds through the welding gun and provides 
the source material for the weld while an inert gas supplied through the 
welding gun supplies a shielding gas for the welding operation. One 
difficulty associated with MIG welding is that the process generates 
substantial weld spatter. 
The weld spatter adheres to and accumulates on the various parts of the 
welding gun causing the parts to deteriorate. Accumulation of the spatter 
on the internal surface of the contact tube increases the friction and 
reduces the electrical contact with the welding wire and, thereby, slows 
the welding operation. Deterioration of the contact tube caused by the 
accumulation often results in "burn backs" wherein the arc extends to the 
contact tube. The burn backs may cause the welding wire to fuse to the 
contact tube leading to frequent required replacement of the contact tube. 
As weld spatter accumulates on the sleeve, or nozzle, of the welding gun, 
the accumulation restricts the flow of the welding gas to the weld. 
Insufficient shielding gas during the welding process will cause a flawed 
weld that delays the process and may cause waste of the pieces being 
welded. Therefore, the welding spatter must be frequently removed from the 
welding gun to ensure a proper weld. Removal of the spatter slows the 
welding process and reduces the efficiency of the process. In addition, 
the deterioration caused by the welding spatter requires periodic 
replacement of the sleeve. 
Thus, the accumulation of welding spatter on the welding gun creates 
inefficiencies in the welding process by (1) slowing the process, (2) 
requiring periodic replacement of the welding gun components, and (3) 
causing flawed welds. These problems associated with welding spatter 
increase the cost of the weld. 
2. Related Art 
The problems associated with welding spatter have long been known to the 
prior art. A number of prior efforts have attempted to address this 
problem. Illustrative of such efforts are U.S. Pat. No. 2,909,645 that 
issued to Berg, U.S. Pat. No. 3,430,837 that issued to Hein, U.S. Pat. No. 
4,280,043 that issued to Feix et al., U.S. Pat. No. 4,947,024 that issued 
to Anderson, and U.S. Pat. No. 5,278,392 that issued to Takacs. 
Previous efforts at resolving the problems associated with weld spatter 
have been directed at tapering the contact tube to reduce the surface area 
near the weld (Berg), coating the welding gun components with a layer of 
material having anti-stick characteristics (Hein, Anderson, and Takacs), 
or providing a mechanical scraper on the welding gun (Feix et al.). Though 
these efforts may be helpful in reducing spatter accumulation or in 
removing spatter that has accumulated on the welding gun, they do not 
eliminate spatter accumulation on the welding gun and its components. 
SUMMARY OF THE INVENTION 
Accordingly, the objectives of this invention are to provide, inter alia, a 
welding gun spatter shield that: 
eliminates spatter accumulation on the welding gun and its components; 
blocks the opening to the welding gun sleeve, or nozzle, and prevents 
welding spatter from entering the sleeve; 
permits the flow of inert gas therethrough; increases the efficiency of MIG 
welding by (1) reducing down-time required for removing spatter 
accumulation, (2) reducing the deteriorating effects associated with 
spatter accumulation, (3) preventing mechanical stoppages and wire feed 
retardation caused by the spatter accumulation, and (4) preventing 
restriction of the inert gas flow and the problems associated therewith; 
is simple to use and low in cost; and 
may be used with existing welding gun sleeve, or nozzle, designs allowing 
for greater universality and further reducing the costs associated 
therewith. 
Other objects of the invention will become apparent from time to time 
throughout the specification and claims as hereinafter related. 
To achieve such improvements, my invention is a welding gun spatter shield 
that has a body constructed and sized to fit at least partially within the 
opening of a welding gun sleeve, or nozzle. The body is constructed and 
sized to fill the opening and provide complete coverage of the cross 
sectional area of the opening. The body includes a wire feed bore that 
extends therethrough in an axial direction. The wire feed bore is 
sufficiently large to permit a welding wire to pass therethrough and is 
positioned in the body such that the wire feed bore is aligned with the 
welding wire when the body is mounted in the opening. At least one 
communication passageway extending in an axial direction through the body 
provides fluid communication through the body.

DETAILED DESCRIPTION OF THE INVENTION 
The preferred embodiment of my invention is illustrated in FIGS. 1 through 
9 and the welding gun spatter shield is depicted as 10. In general, the 
welding gun spatter shield 10 has a body 20, a wire feed bore 22 extending 
through the body 20 in an axial direction, at least one communication 
passageway 24 providing flow communication through the body 20 in an axial 
direction, and a retaining means 50 for removably maintaining the body 20 
in welding gun 60. 
FIG. 4 is a schematic of a typical MIG type welding gun 60. The welding gun 
60 includes a supply of welding wire 80 that furnishes a continuous feed 
of welding wire 80 for the weld. A contact tube 62 holds the welding wire 
80 in position. The welding gun 60 directs an inert gas that shields the 
welding process from the gas source 92 to the weld. The welding gun sleeve 
70 both directs the inert gas to the weld and protects the components of 
the welding gun 60. A power supply 90 is electrically connected to the 
contact tube 62 and a metal workpiece 100. Activating the power supply 90 
produces an electric arc between the workpiece 100 and the tip of the 
welding wire 80 that forges a weld fillet 110 formed of molten metal from 
the welding wire 80. 
Typically, the sleeve 70, or nozzle, of the welding gun 60 has an annular 
cross section along its full length and may be cylindrical or 
frustoconical. The contact tube 62 and the welding wire 80 are generally 
concentric with the sleeve 70. As shown in the figures, the forward end 74 
of the sleeve 70 defines an orifice into the opening 72 of the sleeve 70. 
Because the wall thickness of the sleeve 70 is typically uniform, the 
shape of the opening 72 is typically cylindrical or frustoconical. 
The body 20 of the welding gun spatter shield 10 has an axis and opposing 
faces. Because the welding gun spatter shield 10 is positioned in the high 
temperature environment of an arc weld, the material used for the body 20 
must be capable of withstanding relatively high temperatures. Likewise, 
because the purpose of the welding gun spatter shield 10 is to prevent the 
accumulation of spatter, the body 20 is preferably formed of a material 
having anti-stick characteristics. Examples of suitable materials for the 
body 20 include, inter alia, ceramic coated aluminum, anodized aluminum, 
and porous ceramic. 
The body 20 is constructed and sized for at least partial receipt within 
the sleeve opening 72. When placed in the opening 72, the body 20 fills 
the opening 72 and covers the full cross sectional area of the opening 72. 
In this way, the body 20 forms a barrier across the opening 72 beyond 
which no spatter may pass. To accomplish full coverage of the opening 72 
by the body 20, the shape of the body 72 is preferably the same as the 
opening 72. Typically, the sleeve opening 72 has a circular cross section 
throughout its full length. Accordingly, the body 20, or at least the 
portion of the body 20 to be inserted in the opening 72, also has a 
circular cross section. Likewise, a typical opening is cylindrical. 
Consequently, the portion of the body to be inserted in the opening 72 is 
also cylindrical. To enable the insertion and removal of the body in the 
opening 72 the diameter of the body 20 is slightly less than the diameter 
of the opening 72. So that the parts are aligned, the body 20 is 
preferably substantially coaxial with the sleeve 70 and the opening 72 
when mounted therein. 
As shown in FIGS. 2 and 7, the body 20 construction may facilitate its full 
insertion into the opening 72. Alternatively, the body 20 may have one or 
more portions that do not insert into the sleeve opening 72. 
In one preferred embodiment, the body 20 has an insert portion 30 and a lip 
portion 32. The insert portion 30 fits within the opening 72 and, 
therefore, has an outer diameter that is slightly less than the inner 
diameter of the opening 72. By contrast, the lip portion 32 has an outer 
diameter that is greater than the inner diameter of the sleeve 72 and does 
not fit within the sleeve opening 72. In this preferred embodiment, the 
lip portion 32 defines an abutment surface proximal the insert portion 30 
that lies in a plane substantially perpendicular to the axis of the body 
20. The abutment surface is preferably relatively flat and is constructed 
to abut the forward end 74 of the sleeve 70 when the welding gun spatter 
shield 10 is inserted in the opening 72. So that the welding gun spatter 
shield 10 will protect the forward end 74 of the sleeve 70 and prevent 
spatter contact therewith and accumulation thereon, the outer diameter of 
the lip portion 32 is preferably equal to or greater than the outer 
diameter of the sleeve 70 at its forward end 74. 
As shown in FIG. 8, the lip portion 32 may further include an overhang 36 
constructed to encase the forward end 74 of the sleeve 70 when the welding 
gun spatter shield 10 is mounted thereon. The overhang 36 further protects 
the sleeve 70 from the corrosive effects of the welding spatter by 
preventing welding spatter contact with the sleeve 70. This overhang 36 
could be extended to cover the full length of the sleeve 70. 
In another embodiment, the body 20 may comprise a body 20 that does not 
insert into the opening 72, but attaches over the forward end 74 of the 
sleeve 70 (see FIG. 9). In this embodiment, the body 20 has a diameter 
that is slightly greater than the outer diameter of the sleeve 70 and 
provides complete coverage of the opening 72. An overhang 36 attached to 
and extending from the periphery of the body 20 forms a cylinder. The 
resulting cylinder has an annular cross section and is concentric with the 
body 20. The inner diameter of the cylinder is slightly greater than the 
outer diameter of the sleeve 70; and, thus, the retaining means 50 is the 
friction fit between the cylinder and the sleeve 70. Therefore, the 
welding gun spatter shield 10 acts as a cap that covers the end of the 
sleeve 72. 
Often, the contact tube 62 extends near the forward end 74 of the sleeve 
70. Therefore, to accommodate the contact tube 62 and to permit the proper 
insertion of the welding gun spatter shield 10 into the sleeve 70, the 
body 20 may include a receiving cavity 40 in its rear surface, As shown in 
FIG. 1, the receiving cavity 40 extends partially through the body 20 and 
is sized and shaped to accommodate the contact tube 62 when the welding 
gun spatter shield 10 is mounted in the sleeve 70. Preferably, the 
receiving cavity 40 is coaxial with the body 20. 
To permit the welding wire 80 to extend sufficiently beyond the front 
surface of welding gun spatter shield 10, the body 20 may include a 
forward recess 42 in its front surface. As shown in FIGS. 5 and 6, the 
forward recess 42 sets the front surface of the body 20 back so that a 
welding wire 80 extending to the forward end 74 of the sleeve 70 will have 
more longitudinal clearance which will facilitate arcing between the 
welding wire 80 and the workpiece 100. The forward recess 42 may take many 
shapes. For example, FIG. 5 shows a semispherical forward recess 42; and 
FIG. 6 shows a cylindrical forward recess 42. 
Retaining means 50 maintains the body 20 in the opening 72 and may take 
many forms. The preferred embodiment for the retaining means 50 is 
friction between the body 20 and the sleeve 70. Constructing the body 20 
with a diameter that is very close to, but slightly less than, the 
diameter of the opening 72, creates sufficient friction between the body 
20 and the sleeve 70 when the welding gun spatter shield 10 is in the 
sleeve 70. Both FIGS. 5 and 6 show welding gun spatter shields 10 that 
utilize friction created by a close fit as the retaining means. 
A more preferred embodiment of retaining means 50 comprises a spring 
retaining ring 52 that fits within a groove 34 in the body 20. The groove 
34 extends about the circumference of the body 20 at an axial position 
intermediate the ends of the body 20. Further, the groove 34 is positioned 
axially in the body 20 so that when the body 20 is positioned in the 
opening 72 the groove 34 is encompassed within the sleeve 70. The 
retaining ring 52 is sized and constructed to fit within the groove 34. 
However, the retaining ring 52 in its natural, uncompressed state has a 
diameter that is greater than the diameter of the opening 72. A gap in the 
retaining ring 52 allows it to be compressed radially permitting its 
placement within the opening 72 of the sleeve 70 while the retaining ring 
52 is positioned in the groove 34. Because the retaining ring 52 is 
outwardly biased, when it is compressed, the retaining ring 52 exerts a 
force in the radial direction about its full circumference. Therefore, 
when placed within the sleeve 70, the retaining ring exerts a force 
against the sleeve 70. This force increases the friction between the 
sleeve 70 and the retaining ring 52 requiring greater axial force to 
effect a change in the axial position of the retaining ring 52. When 
compressed, the retaining ring 52 inner diameter is less than the outer 
diameter of the groove 34. Accordingly, the groove 34 abuts the retaining 
ring 52 when the retaining ring 52 is positioned within the groove 34 and 
the body 20 is positioned within the opening 72. Consequently, axial 
movement of the body 20 is made more difficult due to the increased 
friction created by the retaining ring 52 and its abutting relationship to 
the groove 34 in the body 20. 
To permit the welding wire 80 to pass through the welding gun spatter 
shield 10, the body 20 includes a wire feed bore 22 therethrough extending 
in the axial direction. The diameter of the wire feed bore 22 is 
sufficiently large to permit the welding wire 80 to pass therethrough. 
Further, the wire feed bore 22 is positioned for alignment with the 
welding wire 80 when the body 20 is mounted in the opening 72. Typically, 
the sleeve 70, the contact tube 62, and the welding wire 80 are coaxial. 
Accordingly, the body 20 and the wire feed bore 22 are preferably also 
coaxial with the sleeve 70, the contact tube 62, and the welding wire 80. 
So that the inert shielding gas may reach the weld, the body 20 has at 
least one, but preferably a plurality of, communication passageways 24 
that provide fluid communication through the body 20 in an axial 
direction. The number and size of communication passageways 24 are 
sufficient to permit the flow of the required amount of inert gas 
therethrough for proper welding. However, the communication passageways 24 
are sufficiently small that spatter may not travel therethrough. In 
certain materials, such as anodized aluminum or ceramic coated aluminum, 
the communication passageways 24 are small bores 26 that extend through 
the body 20 in an axial direction. In other materials, such as porous 
ceramic, the communication passageways 24 exist a property of the 
material. In other words, the material is sufficiently porous that the 
inert gas may pass through the body 20 without any further modification to 
the body 20. 
In operation, the welding gun spatter shield 10 is simply inserted into the 
opening 72 of the sleeve 70 prior to commencing the welding operation and 
is maintained therein during welding. Consequently, a method of preventing 
welding spatter accumulation in a welding gun sleeve 72 comprises packing 
the opening 72 with a porous material so that the opening 72 is fully 
covered. The material should be capable of withstanding relatively high 
temperatures and preferably has anti-stick characteristics. Additionally, 
the method includes the steps of extending the welding wire 80 through the 
wire feed bore 22 and maintaining the material in the opening 72 during 
welding. The material may take the form of the body 20 as previously 
described.