Patent Application
20100089888
The present disclosure relates generally to apparatuses and methods for welding and joining two members, and more particularly, to apparatuses and methods for improving fatigue life of a welded joint.
One concern with welded joints relates to weld fatigue. Weld fatigue failure is believed to occur at the weld toe due at least in part to high stress concentrations at the weld toe. Such stress concentrations are believed to often be the byproduct of a cold lap. To reduce the stress concentrations and/or the effects of cold laps, it may be desirable to develop a weld-bead geometry that has a smooth transition between the surfaces of the members being welded and the base of the weld-bead. One welding method that may address this desire is a method sometimes referred to as “multi-pass welding,” which may suffer from a number of possible drawbacks, such as, for example, a welded joint having minimal weld penetration.
Other methods for forming welded joints include, for example, the method disclosed in U.S. Pat. No. 6,649,870 (“the '870 patent”) issued to Barton et al. on Nov. 18, 2003. The '870 patent discloses providing a welding system and method that includes an arc welding subsystem, which utilizes one or more controlled process variables to facilitate geometric control of a toe angle, a toe radius, a throat dimension, and a penetration depth associated with the joining of the fillet weld and the one or more members. Although the welding method disclosed in the '870 patent may provide improvements in a fillet weld, it may not be suitable for providing a fillet weld with, for example, a general concave shape.
The apparatuses and methods of the present disclosure may be directed toward mitigating or overcoming drawbacks associated with existing welding technology.
In one aspect, the present disclosure is directed to a method for welding an edge of a first member to a side surface of a second member. The first member and the second member may be joined to one another at a joint. The method may include beveling an edge of the first member. The method may also include positioning the edge of the first member proximate the side surface of the second member. The method may further include supplying welding material via a welding wire along the edge of the first member to create a joint between the first member and the second member. Supplying welding material may include controlling a feed rate of the welding wire, such that a weld bead formed at the joint may define a concave cross-section.
In another aspect, a method for improving fatigue life of a welded joint between a first member and a second member may include positioning an edge of the first member proximate a side surface of the second member. The method may also include supplying welding material via a welding wire along the edge of the first member to create a joint between the first and the second members. The method may further include controlling a feed rate of the welding wire according to a formula, VW≦K·VT·Sweld·(DW)−2, where VW is the feed rate of the welding wire, K is a coefficient, VT is a travel speed of a welding assembly configured to supply welding material, Sweld is a cross-sectional area of the joint between the first and the second members, and DW is related to a cross-sectional area of the welding wire.
In yet another aspect, an apparatus for welding an edge of a first member to a side surface of a second member may include a welding assembly operable to weld the edge of the first member to the side surface of the second member. The welding assembly may be configured to supply a welding wire to a joint between the first and second members at a feed rate. The apparatus may further include a processor operably coupled to the welding assembly. The processor may be configured to store one or more weld variable parameters, and to control the welding assembly based on at least one of the weld variable parameters and a formula, VW≦K·VT·Sweld·(DW)−2, where VW is the feed rate of the welding wire, K is a coefficient, VT is a travel speed of the welding assembly, Sweld is a cross-sectional area of the joint between the first and second members, and DW is related to a cross-sectional area of the welding wire.
An exemplary embodiment of a welding assembly 10 is schematically illustrated in
According to some embodiments, for example, as shown in
According to some embodiments, welding robots may be employed to operate welding assembly 10. This includes, for example, welding robots from ABB Ltd., Motoman, Inc., FANUC Robotics, Inc., Panasonic Factory Solutions Company of America, and/or other welding devices known to those skilled in the art. In some embodiments, operation of welding assembly 10 may be controlled via the use of memory 20 and/or controller 30. For example, memory 20 may be configured to store a plurality of weld variable parameters associated with welding assembly 10. The plurality of parameters may include, for example, a travel speed of welding assembly 10, a feed rate of a welding wire, a cross-section and/or diameter of the welding wire, and/or a cross-sectional area of welded joint 60. Other weld variable parameters are contemplated. Controller 30 may be operably coupled to memory 20, and controller 30 may be configured to control welding assembly 10 based on one or more of the plurality of weld variable parameters, which may be stored in memory 20.
While memory 20 and controller 30 are shown in
As illustrated in
According to some embodiments, edge 70 may be beveled. For example, a portion of edge 70 may be removed, such that an angle δ may be formed by a surface 68 of first member 40 and beveled surface 69. Angle δ may range from about forty-five degrees to about seventy-five degrees. For example, angle δ may be about sixty degrees.
According to some embodiments (not shown), a supply of welding material may be operably coupled to welding assembly 10. For example, the welding material supply may be located internal and/or external to welding assembly 10. For some embodiments, welding material may be supplied via one or more welding wires. The welding wires may be made from materials that are in the same class and/or category as first member 40 and second member 50. For example, the welding wires may be metals and metal alloys.
Welding assembly 10 may be configured to supply welding material to joint 60. For example, welding assembly 10 may be configured to feed welding material to joint 60 at a feed rate configured to result in a fatigue-resistant weld. The feed rate may be controlled manually, for example, via an operator holding and guiding welding assembly 10, and/or automatically via welding assembly 10 according to pre-adjusted settings. As welding material is fed to joint 60, welding material may collect and form a weld bead 90 at joint 60.
Weld bead 90 may generally define a cross-sectional area defining at least one concave side, for example, such that weld-bead surface 66 is concave with respect to surface 68 of first member 40 and/or side surface 80 of second member 50. Weld bead 90 may define cross-sectional areas having various shapes, depending on factors, such as, for example, the relative orientation of first member 40 and second member 50.
It is contemplated that the supply of welding material to joint 60 may be controlled either manually or automatically. For example, an operator may manually hold and guide welding assembly 10 along edge 70 such that welding wire is fed at a feed rate to form weld bead 90. According to some embodiments, the supply of welding material may be controlled, for example, based on a plurality of weld variable parameters. According to some embodiments, the weld variable parameters may be similar to the plurality of weld variable parameters described previously herein. For example, the feed rate of the welding wire may be automatically controlled via welding assembly 10, thereby forming weld bead 90 at joint 60.
According to the exemplary embodiment shown in
V
W
≦K·V
T
·S
weld·(DW)−2,
where VW is the feed rate of the welding wire, K is a coefficient, VT is a travel speed of the welding assembly, Sweld is a cross-sectional area of the joint between the first and second members, and DW is related to the cross-sectional area of the welding wire (e.g., a diameter of the welding wire).
Referring to
In some embodiments, edge 70 may be beveled such that a portion of edge 70 may be removed. The beveling of edge 70 may help to define a space at joint 60. The space may serve to deepen the penetration of weld bead 90 at joint 60 (i.e., relative to weld bead 90 that may be formed at joint 60 in instances where edge 70 may not have been beveled). The penetration of weld bead 90 at joint 60 may, for example, range from about 7 millimeters to about 9 millimeters. The deeper penetration at joint 60 may serve to improve the strength of weld bead 90. The deeper penetration at joint 60 may also serve to improve the fatigue life of weld bead 90. Weld bead 90 may generally define a cross-sectional area defining at least one concave surface (e.g., weld-bead surface 66). The concave surface may serve to improve the fatigue life of weld bead 90, which may also strengthen the connection between first member 40 and second member 50 at joint 60.
In embodiments where the supply of the welding material may be controlled according to the formula,
V
W
≦K·V
T
·S
weld·(DW)−2,
where VW is the feed rate of the welding wire, K is a coefficient, VT is the travel speed of the welding assembly, Sweld is the cross-sectional area of the joint between first member 40 and second member 50, and DW is the diameter the welding wire, the following exemplary values may be used for each of the parameters listed in the formula. For example, K may range from about 0.382 to about 0.573, VT may range from about 4 inches per minute to about 12 inches per minute, Sweld may range from about 20 square millimeters to about 35 square millimeters, and DW may range from about 0.035 inches to about 0.064 inches (e.g., 0.035 inches, 0.052 inches, or 0.064 inches). In embodiments where shielding gas may used, the shielding gas may be a mixture of Argon and Carbon Dioxide. Further, in embodiments where a multi-pass welding technique is employed, it is contemplated that during different passes, the welding wire may be oriented differently with respect to plane A. For example, during an initial pass, the welding wire may be fed in an orientation that may be at about 20 degrees with respect to plane A. During subsequent passes, the welding wire may be fed in an orientation that may be generally orthogonal to plane A. Alternatively, the welding wire may be fed at the same orientation with respect to plane A during all passes, or the welding wire may be fed in different orientations with respect to plane A during the passes.
It will be apparent to those skilled in the art that various modifications and variations can be made in the disclosed apparatuses and methods for welding and improving fatigue life of a welded joint of two members. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed embodiments herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims.
