| US3681560A | 1972-08-01 | |||
| US3777103A | 1973-12-04 |
| 1. | Weld path tracking apparatus, comprising a support assembly, a pair of tracking wheels supported for rotation by said support assembly, one of said tracking wheels having bevels at its opposite sides around its _ circumference to provide a sharp edge around its cir¬ cumference, the other of said wheels being grooved about its circumference, said wheels being supported in a tan¬ dem arrangement to be rollable along a single path, said sharp edged wheel being adapted to engage in an open welding groove to track said welding groove, said grooved wheel being adapted to engage about a weld bead to track the weld bead, whereby said apparatus will track a weld path comprising an open welding groove or a weld filled welding groove, or both. |
| 2. | The combination of claim 1, said support assembly including connection means for rigid connection thereof to a welding apparatus with said wheels po¬ sitioned to roll along the weld path preceding said welding apparatus to guide said welding apparatus along said weld path. |
| 3. | The combination of claim 2, said grooved wheel preceding said sharp edged wheel in travel to be adapted to commence tracking a previously formed weld bead as said welding apparatus approaches the previously formed weld bead forming a weld bead to be continuous therewith. |
| 4. | The combination of claim 3, including means for biasing said wheels toward the weld path and separate means permitting said grooved wheel to independently yield when it encounters a previously formed weld bead in the welding groove, whereby said sharp edged wheel may be engaged in an open welding groove while said grooved wheel is engaged with a weld bead. & Zl"S' .Si . |
| 5. | The combination of claim 4, said biasing means and said yielding means each comprising compression spring means. |
| 6. | The combination of claim 5, including means for maintaining said wheels in aligned positions and for preventing transverse rotational twisting thereof. |
| 7. | Tracking apparatus for guiding a welding torch along a welding groove whether or not a weld bead has been formed in the welding groove, comprising a first wheel having an edge form adapted for rolling en¬ gagement along a welding groove, a second wheel having an edge form adapted for rolling engagement along a weld bead in the welding groove, said wheels being disposed in tandem with, said second wheel preceding said first wheel in rolling movements along said welding groove. |
| 8. | The combination of claim 7, said first wheel having a sharp edge about its circumference and said second wheel having a groove about its circumference. |
| 9. | The combination of claim 8, at least one of said sharp edge and said groove having a Vshaped cross sectional shape. |
| 10. | The combination of claim 9, said wheels being of substantially the same diameter. |
| 11. | The combination of claim 9, said wheels having at least substantially parallel axes. |
| 12. | The combination of claim 10, said wheels hav¬ ing at least substantially parallel axes. |
| 13. | The combination of claim 9, said wheels being rigidly connected to a welding torch for travel along a welding groove therewith, said wheels pre¬ ceding the welding torch in travel along the welding groove to guide the welding torch along the welding groove. |
| 14. | The combination of claim 13, said wheels being Gfϊ „**_?„« m■? i biased toward the welding groove and said second wheel being resiliently supported with respect to said first wheel whereby said first wheel may be engaged in the welding groove while said second wheel is engaged astride a weld bead within the welding groove. |
| 15. | The combination of claim 14, said wheels being pivotally interconnected. |
| 16. | The combination of claim 15, said second wheel being separately resiliently biased toward the welding groove. |
| 17. | The combination of claim 16, including means for preventing transverse rotational displacement of said wheels with respect to said welding torch. |
| 18. | In combination with a welding torch, a tracking means for guiding said welding torch adapted to track either or both of an open welding groove and a welding groove having a weld bead therein. |
| 19. | The combination of claim 18, said tracking means comprising an outwardly narrow edged wheel en gageable in an open welding groove to follow the welding groove, and an outwardly grooved wheel engageable about a weld bead to follow the weld bead. |
| 20. | The combination of claim 19, said wheels being resiliently biased toward said welding groove and bead, and said grooved wheel being resilient with re¬ spect to said narrow edged wheel. SUBST.TUTΞSHEET. |
WELDING GROOVE TRACKING APPARATUS
Background of The Disclosure
Tracking of a welding groove to insure that a welding apparatus will accurately follow the welding groove is not an easy problem. In tracking a welding groove about the inside or the outside of a circular pipe, the welding apparatus sooner or later will come to a place previously welded, so that the feeler or groove following wheel will be forced off course, with the result that the weld will no longer follow the groove, unless made to do so manually. While it is known to track a welding groove with a sharp edged wheel which will remain in an open welding groove, there is no means known which will track the groove after a weld has been formed therein. The present invention seeks to provide a solution to this problem in the art.
Summary of The Invention
The invention provides an apparatus capable of following an open welding groove and capable also of following a welding groove in which a weld has been formed, so that the apparatus will track a welding groove completely around a circular or other loop shaped object without being thrown off course when the welding apparatus reaches a section of groove in which a weld has already been formed. In the case of welding large pipe lengths end to end to form a pipeline, this is particularly
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important, since it has been the practice and is neces¬ sary to weld the pipe ends together in a plurality of arcuate segments in order to overcome adverse effects caused by expansion of the pipe metal as a result of the heat of welding. In the pipeline construction industry, it has been the practice to weld opposite 90. degree segments and then to weld the other opposite 90 degree segments of the pipe periphery, in order that the pipe will not be distorted excessively during welding. Of- ten, in automatic pipe welding systems, four welding ap¬ paratuses are used, mounted 90 degrees apart around the pipe. Two opposite apparatuses first form welds around two opposite quadrants, with the other two apparatuses traveling in the same direction but not welding. Then, the other two apparatuses weld the other two opposite quadrants around the pipe, with the first two opposite apparatuses being returned to their original positions without welding. Thus, the entire pipe circumference is welded in two two-quadrant passes. Each quadrant weld is slightly greater than 90 degrees, so that the weld ends will be overlapped. When the second pair of quad¬ rant welds near completion, the welding apparatuses will arrive at ends of the first pair of quadrant welds, and the groove tracking apparatus will not be able to follow the groove, in which a weld is already in place. So that the weld tracking device will be able to follow a welding groove whether or not there is weld material in the groove, the present invention provides a tracking device which includes two groove following wheels instead of one, as heretofore. One tracking wheel is sharp edged to engage in the groove. The other tracking wheel is grooved circumferentially to engage the hump of a weld bead, to follow it. The two tracking wheels act in concert, the sharp edged wheel following the groove when there is no weld in the groove, with the grooved
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wheel in contact with opposite sides of the groove but without tracking function. When there is a weld in the groove, the sharp edged wheel runs along the weld without tracking function, while the grooved wheel engages op- posite sides of the weld bead and provides tracking function. Thus, when the apparatus arrives at the end of a quadrant and engages a previously formed weld in the adjacent quadrant, the grooved wheel engages the weld to continue the tracking function which thereto- fore was provided by the sharp edged wheel disposed in the open groove. It is, therefore, preferable that the grooved wheel be in advance of the sharp edged wheel so that there will be no lack of or break in tracking con¬ tinuity when a previously formed weld is encountered. A principal object of the invention is to pro¬ vide a weld groove tracking apparatus which will track both an open weld groove and a weld groove having a weld bead therein. Another object of the invention is to pro¬ vide such an apparatus having a sharp edged tracking wheel and having a circumferentially grooved tracking wheel. A further object of the invention is to provide such an apparatus in which the tracking wheels are biased toward the welding groove. Yet another object of the invention is to provide such an apparatus in which the two track- ing wheels are arranged in tandem. Another object of the invention is to provide such an apparatus which is simple, efficient, easily operated and repaired, durable, and economical.
Other objects and advantages of the invention will appear from the following detailed description of a preferred embodiment of apparatus according to the invention, reference being made to the accompanying drawings.
SUBSTITUTE
Brief Descriptions of the Drawings
FIG. 1 is a side elevation of a preferred em¬ bodiment of apparatus according- to the invention.
FIG. 2 is a top view of a portion of the ap¬ paratus shown in FIG. 1, taken at line 2-2 of FIG. 1. FIG. 3 is a partial view, partly in vertical cross section, showing an element of the apparatus of FIG. 1.
FIG. 4 is a partial view, partly in vertical cross section, showing another element of the apparatus of FIG. 1.
Description of the Preferred Embodiment
Referring now to the drawings in detail, a body 10 is provided, which may be supported by one or more screws (not shown) which may be engaged through screw- holes 11 through flange 12, so that body 10 is fully supported adjacent welding tip 14 to travel along the weld path therewith. The weld path is defined by welding bevel 15 at the interior of the wall of pipe 16, only a portion of which is shown. The end of pipe 16 is abut¬ ted with the end of another pipe 17, which also has an interior bevel 15, and the two bevels 15 form a weld¬ ing groove at the joint between the pipe ends. Around the bevels 15, the pipe ends have unbeveled portions 18, outwardly of which are the exterior bevels 19 forming an exterior welding groove. A weld is formed first at the interior groove formed by bevels 15, and an exterior weld is then formed at the exterior groove formed by bevels 19. During welding, the pipes are held in aligned positions by an internal pipe clamp, not shown, the na¬ ture and function of • which are well known -in the art. The apparatus herein described and claimed may be carried by an apparatus such as that disclosed in application for Letters Patent Serial No. 06/567 ,738, filed January 3, 1984, and entitled "Internal Pipe Welding Apparatus". As shown in that application, the apparatus is supported between two pipe clamp assemblies each internally engaged with one of the pipes 16, 17.
Body 10 has a longitudinal bore 20 into which is received a shaft 21 slidably disposed therein. Shaft 21 carries a pin 22 which slides in slot 23 formed in body 10. Pin 22 and slot 23 limit longitudinal move¬ ments of shaft 21 and prevent rotation of shaft 21 in bore 20.
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The outer end of shaft 21 is formed as a bar or block 24. A pair of arms 25, 26 extend into a slot 27 of a bar 28. A pin 30 disposed through openings through bar 28 at opposite sides of slot 27 and through matching openings through arms 25, 26 serves as the axle of a rotative wheel 32. Wheel 32 is beveled around its cir¬ cumference at both sides at.33 to have a sharp edge 34 therearound.. A second wheel 35 is similarly mounted on a pin 36 which passes through openings through op- posite sides of bar 28 at slot 37 thereof, and through spacer formations 38, 39 at the opposite sides of slot 37, as shown.
A spring recess is formed around bore 20 at its end toward bar 24, and a helical compression spring 40 is disposed therein around shaft 21 to engage bar 24. Spring 40 biases bar 24 and the wheels 32, 35 toward pipe wall 16 to maintain firm contact of the wheels with the pipe wall. A second spring 41 has one end disposed in a recess 42 in bar 24 and its other end is disposed in a cylindrical passage 43 through bar 28 between slots 27, 37 thereof. Passage 43 is threaded at at least its outer end and a threaded plug 44 screwed therein can be tightened or loosened against the end of spring 41 to adjust its compressive force. Spring 28 resiliently biases bar 28 and wheel 35 toward pipe wall 16. While wheel 32 remains firm against the pipe wall because of the force of spring 40, wheel 35 can be moved slightly inwardly of the pipe wall because of the resiliency of spring 41. Plate 46 fixed to the end of bar 24 facing the welding tip 14 is for the purpose of preventing weld spatter from reaching the wheels 32, 35.
Since the wheel assembly is for the purpose of guiding the welding tip along the weld path, the weld¬
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ing tip 14 and body 10 must in most cases by carried by a common support. For example, the apparatus disclosed in application for Letters Patent Serial No. 06/610,317, filed May 14, 1984, and entitled "Internal Welding Head Assembly", shows such an arrangement. The tracking ap¬ paratus herein disclosed may be used with other apparatuses whenever suitable.
Referring now to FIGS. 3-4, FIG. 3 shows the wheel 32 having the sharp circumferential edge 34 dis- posed in the welding groove formed by bevels 15. In FIG. 4, it is shown that wheel 35 has a circumferential groove 48 therearound. A weld bead 49 is shown in the groove formed by bevels 15, and the groove 48 rolls along the weld bead, as shown, with the opposite edges 51, 52 of groove 48 at opposite sides of the weld bead. Thus,- wheel 32 follows the welding groove because edge 34 is engaged in the groove, while wheel 35 follows the weld bead because wheel groove 48 engages the weld bead. Since the two wheels 32, 35 are rigidly connected together by bar 28, the assembly will follow a weld track whenever one of the wheels is engaged as described. The engaged wheel does the tracking, while the other wheel travels along without tracking function. The wheel 32, when at a weld bead, will roll along the bead while wheel 35 tracks the bead, and wheel 35 will roll along the groove while wheel 32 tracks the groove.
The weld bead 49 is shown in FIG. 1 being formed by tip 14 and welding wire 54 as the apparatus travels in the direction shown by arrow 55. The weld bead 49 to the right in FIG. 1 has been previously formed by the same or other welding equipment. As the equipment reaches the previously formed bead, wheel 35 commences to track the bead, while wheel 32 is still tracking the groove. When wheel 32 reaches the bead, it will roll onto the bead and along it as wheel 35 provides the tracking func-
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tion. After the bead at the left in FIG. 1 has reached the bead at the right and overlapped it, welding is dis¬ continued and, as earlier described, the welding apparatus ma -be moved in the direction opposite arrow 55. Wheel 35 will track the bead in this movement, so that the welding equipment stays "on track" even when welding is not being done, to move the entire apparatus back prior to the following welding operation. As should by now be clear, the apparatus will track a weld path whenever one or both of the wheels is engaged with the groove or with a weld bead.
The disclosed apparatus is an improvement over the prior art devices, with which tracking is discon¬ tinued when a previously formed weld bead is encountered. Use of automatic welding will be improved, since tracking will remain effective under all conditions of the weld¬ ing grooves.
While a preferred embodiment of the apparatus according to the invention has been described and shown in the drawings, many modifications thereof may be made by a person skilled in the art without departing from the spirit of the invention, and it is intended to pro¬ tect by Letters Patent all forms of the invention falling within the scope of the following claims.
SUBSTITUTE SHEET