Patent Application
20150314407
The present disclosure relates to joining enclosed workpieces. More particularly, the present disclosure relates to a method of using a combination of a limitedly accessible backing member with a resilient member to support the backing member during a welding operation.
Joining techniques such as welding may be applied to fixedly connect two workpieces. In various cases, prior to the joining process of a first workpiece and a second workpiece, the first workpiece and the second workpiece are positioned together relative to each other, in an optimum weld position. In other words, connecting portions of the two workpieces are positioned next to each other, thereby defining an attachment region. In this position, a backing may be provided to impart rear support to the attachment region during a welding process for groove weld joints, such as bevel groove, V groove, flare bevel groove, square edge groove, etc. The backing strip may be secured in preferred location and orientation by use of tack weld, underneath and in between the first workpiece and the second workpiece. Upon attachment of the backing member to the first workpiece and the second workpiece, the first workpiece and the second workpiece are welded together from the other side of backing member with respect to the workpieces.
Various workpieces to be joined, may have an enclosed structure. Such enclosed workpieces, when positioned near each other, may be joined along corresponding peripheral ends, to define the attachment region. This may result in no access to the interior portions of the defined attachment region. Due to inaccessibility of the rear portion of the attachment region of the enclosed workpieces, the supporting backing members in applications with enclosed structures are difficult and expensive. It may be difficult to hold or secure the ceramic backing strip at the rear portion. Further, it may be a tedious task to tack weld or use the adhesive for attachment of the ceramic backing strip in such workpieces, prior to create a joint. Hence, there may be weakness in the joint.
U.S. Pat. No. 3,578,233 discloses a method of welding two pipes by thermit welding. For this process, an inflatable rubber seal ring is used. However, the inflatable rubber seal ring used in this reference is to seal against an inside pipe surface. Hence, the reference does not discuss welding of enclosed structures and means for supporting a backing member for joining such enclosed structures.
Various aspects of the present disclosure describe a method to join a first enclosed workpiece and a second enclosed workpiece. The first enclosed workpiece includes a first connecting end, a first internal surface, and a first cavity region. The second enclosed workpiece includes a second connecting end, a second internal surface, and a second cavity region. The method includes placement of a backing member in the first connecting end. The backing member includes a first end and a second end, such that the first end of the backing member is within the first cavity region of the first enclosed workpiece. A resilient member is positioned in the first cavity region and is surrounded by the backing member. The first end of the backing member is pushed against the first internal surface. The resilient member includes a first portion and a second portion, wherein the first portion is placed within the first cavity region. The second enclosed workpiece is positioned proximal to the first enclosed workpiece such that a gap is defined between the first connecting end and the second connecting end. Upon positioning of the second workpiece, the second end of the backing member is placed within the second cavity region. The second end of the backing member is thus pushed against the second internal surface. The second portion of the resilient member is placed within the second cavity region. The first connecting end of the first enclosed workpiece is then welded with the second connecting end of the second enclosed workpiece, over the backing member near the gap.
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The second enclosed workpiece 14 includes a body 20 with a second connecting end 22, a second cavity region 24 (
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A backing member 34 is attached to the peripheral groove 28. However, in an embodiment, there may be three or more backing members 34, being contingent on the structure of the first connecting end 18 and the second connecting end 22. In the exemplary embodiment, the backing member 34 is complementarily rectangular in shape, with respect to the peripheral groove 28. The backing member 34 is complementarily attached relative to four corners of the rectangular-shaped first connecting end 18. Together, the backing member 34 substantially surrounds the first internal surface 30 and the first cavity region 32. The backing member 34 may be ceramic-based, copper-based, and/may be inclusive of other suitable materials. The shape, size, and dimension of the backing member 34 may vary, as a shape of the connecting ends 18 and 22 may also vary.
The backing member 34 includes a periphery 36, a first end 38, a second end 40, an interior surface 42, and an exterior surface 44. The periphery 36 is positioned at the first end 38. The first end 38 attaches to the peripheral groove 28, such that the first end 38 is housed within the first cavity region 32. The second end 40 is provided for attachment with the second enclosed workpiece 14 such that the second end 40 is housed within the second cavity region 24 (
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At step 60, the backing member 34 is positioned inside the first connecting end 18. The backing member 34 are attached to the peripheral groove 28 of the first connecting end 18, such that the first end 38 of the backing member 34 is within the first cavity region 32. The method 56 proceeds to step 62.
At step 62, the resilient member 46 is positioned into an encompassed space or hollow portion defined by the placement of the backing member 34, such that the first portion 50 of the resilient member 46 is placed within the first cavity region 32 of the first enclosed workpiece 12. In addition, the resilient member periphery 48 is in contact with the interior surface 42 of the backing member 34. The resilient member 46 is then inflated. The first end 38 of the backing member 34 will be pushed against the first internal surface 30. In case of inflatable resilient members 46, a pressure exerted by the resilient member 46 may be controlled to hold the backing member 34 at a predetermined contact pressure against the first internal surface 30. The method 56 proceeds to step 64.
At step 64, the second enclosed workpiece 14 is positioned proximal to the first enclosed workpiece 12, such that a gap, G is defined between the first connecting end 18 and the second connecting end 22. Upon positioning of the second enclosed workpiece 14, the second end 40 of each of the backing member 34 is positioned in the second cavity region 24, such that the exterior surface 44 is in contact with the second internal surface 26. In addition, the second end 40 of the backing member 34 may be pushed against the second internal surface 26. The method 56 proceeds to step 66.
At step 66, the first connecting end 18 of the first enclosed workpiece 12 is welded to the second connecting end 22 of the second enclosed workpiece 14 over the backing member 34 near the gap, G. The method 56 ends at step 68.
In operation, the disclosed method 56 uses the resilient member 46 to facilitate connection of the first enclosed workpiece 12 and the second enclosed workpiece 14. An operator disposes the backing member 34 in the peripheral groove 28 of the first enclosed workpiece 12. The operator then places the resilient member 46 between the backing member 34 and inside the first cavity region 32. In an embodiment, the resilient member 46 may be inflated for stable engagement of the workpieces 12 and 14, via the backing member 34. The workpieces 12 and 14 to be welded are held in position as the backing member 34 are pushed against the first internal surface 30 and the second internal surface 26. Elastic force of the resilient member 46 provides support to hold the backing member 34 from an internal side, prior to bringing the second enclosed workpiece 14 to the assembly 10. The first connecting end 18 and the second connecting end 22 are then welded together at the gap, G, on the backing member 34. In other words, weld material is filled in the gap to join the first enclosed workpiece 12 and the second enclosed workpiece 14.
The disclosed method 56 is advantageous for enclosed structures. One of the advantages when compared to conventional methods, is that, there is no requirement of tack welds to provide support to the backing member 34. Elimination of a requirement of tack welds assists in the maintenance of optimum fatigue strength. In addition, the welding of the first enclosed workpiece 12 and the second enclosed workpiece 14 may be performed from an exterior of the assembly 10, without welding from a rear side of the joint. This increases efficiency of the welding for varying sizes and shapes of the workpieces 12 and 14. Further, the resilient member 46 is left between the first enclosed workpiece 12 and the second enclosed workpiece 14, upon welding. This reduces efforts in the welding of the two workpieces 12 and 14.
The many features and advantages of the disclosure are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the disclosure that fall within the true spirit and scope thereof. Further, since numerous modifications and variations will readily occur to those skilled in the art. It is not desired to limit the disclosure to the exact construction and operation illustrated and described, and, accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the disclosure.
