AU2011101397A4 - A Rotary Welding System - Google Patents

Abstract

-9 A rotary welding system 10 comprises a carriage 12, a rotatable arm 14, a centralising stabiliser system 16, and a welder application mechanism 18 in the 5 form of a ram 28 supported on the arm 14. The carriage 12 is capable of travelling along an inside of a pipe 20 and rotatably supports the arm 14 which extends in a radial direction relative to the pipe 20. A welding machine 22 is supported on the arm 14 and coupled to one end of a ram 28. By controlling flow of air through the ram 28, the welder 22 can be moved linearly in the radial 10 direction into and out of operative contact with an inside surface of the pipe. A pressure regulator and valve enable adjustment of contact pressure between the welder 22 and the inside surface of pipe 20. 2902978_1 (GHMatters) P88556 AU

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Innovation Patent Applicants: Travis McRobert and Craig Hamilton McRobert Invention Title: A Rotary Welding System The following statement is a full description of this invention, including the best method for performing it known to me/us: -2 A ROTARY WELDING SYSTEM Technical Field 5 A rotary welding system is disclosed for welding on an inside surface of a pipe. Background Art Medium to large diameter concrete pipes used for in sewerage systems are 10 quickly corroded and eroded by gases given off by sewerage. One way to prevent this, or to refurbish/repair a damaged concrete pipe, is to line them with sleeves made from a gas impervious and resistant plastics material. To prevent seepage of gas between and then behind the sleeves, it is necessary to weld abutting ends of the sleeves together or otherwise adhere a gas tight bead 15 across the adjacent ends to form a seal. Extrusion welders are used for this purpose. An extrusion welder heats both a cord of plastics material and the surface of the sleeves in the region of their abutting ends. The plastics material melts and is extruded from an end of the welder and forms a bead that extends across the abutting ends creating a gas tight seal. The extrusion welder is a 20 relatively heavy piece of equipment and the work space for its use is often cramped. This leads to rapid fatigue and injury of a worker tasked with this job. Summary of the Invention 25 In one aspect there is provided a rotary welding system for welding an inside surface of a pipe, the rotary welding system comprising: a carriage capable of travelling along an inside of a pipe, the carriage rotatably supporting a radially extending arm, the arm arranged to demountably receive a welding machine; 30 a centralising stabiliser system supported on the carriage and arranged to fix the carriage in the pipe in a welding position where an axis of rotation of the arm is substantially co-incident with an axis of the pipe, the centralising stabiliser system having at least one moveable stabiliser which is selectively movable between a first position where the movable stabiliser is in contact with 35 the pipe and fixes the carriage in the welding position, and a second position where the movable stabiliser is spaced from the pipe a distance sufficient to enable the carriage to move along the pipe; and, 2902978.1 (GHMatters) P88558 AU -3 a welder application mechanism arranged to move a welding machine supported on the arm in a radial direction of the pipe to a deployed position where the welding machine is in operative contact with the inside surface of the pipe and, a park position where the welder is spaced from the inside surface of 5 the pipe. Brief Description of the Drawin-gs An embodiment of a rotary welding system will now be described by way of 10 example only with reference to the accompanying drawings in which: Figure 1 is a front view of an embodiment of a rotary welding system inside a pipe; Figure 2 is a rear view of the rotary welding system shown in Figure 1; and, 15 Figure 3 is a close up view of a portion of a centralising stabiliser system incorporated in the rotary welding system. Detailed Description of Preferred Embodiment 20 An embodiment of a rotary welding system 10 comprises a carriage 12, a rotatable arm 14, a centralising stabiliser system 16, and a welder application mechanism 18 supported on the arm 14. The carriage 12 is capable of travelling along an inside of a pipe 20 and rotatably supports the arm 14 which extends in a radial direction relative to the pipe 20. The arm 14 is arranged to 25 demountably receive a welding machine in the form of an extrusion welder (hereinafter "welder") 22. More particularly the arm 14 is provided with a bracket 24 that can be manipulated to selectively either hold the welder 22 on the arm or allow the welder 22 to be released. 30 Arm 14 is in the form of a U channel 26 made from a metallic material such as aluminium or steel. Seated in the U channel 26 is the welder application mechanism 18 which takes the form of a pneumatic ram 28. Ram 28 is provided with a piston 30 which is connected at its distal end to the bracket 24. By controlling flow of air through the ram 28, the piston 30 can be extended or 35 retracted resulting in a corresponding linear motion in the radial direction for the welder 22. The welder application mechanism 18 also comprises a pressure regulator and valve to enable adjustment of air pressure applied to the ram 28 2902978_1 (GHMaIlers) P88558 AU -4 when the welder 22 is in the deployed position. This enables an adjustment of contact pressure between the welder 22 and the inside surface 20. The carriage 12 is in the form of a box framed trolley 32 which supports the arm 5 14, centralising stabiliser system 16, as well as other components of the rotary welding system 10 such as an accumulator 34 which essentially stores compressed air, a motor 36 which provides torque for rotating the arm 14, gear boxes (not shown) providing power transmission between the motor 36 and arm 14 and other equipment incorporated in the rotary welding system 10. Carriage 10 12 also comprises a number of wheels 38 rotatably mounted on axles 40 that enable the carriage 12 to be moved along the pipe 20. The centralising stabiliser system is supported on the carriage 12 and arranged to fix the carriage 12 in the pipe 20 in a position where an axis of rotation 42 of 15 the arm 14 is substantially coincident with a central axis of the pipe 20. The centralising stabiliser system 16 comprises: one or more, but in this embodiment only one, movable stabiliser 44; and, one or more, but in this case two, fixed stabilisers 46. The stabilisers 44 and 46 are angularly spaced about the axis 42. In the present embodiment they are evenly by 1200, but this need 20 not be the case for every embodiment. The movable stabiliser 44 is in the form of two pneumatic rams 48 (see Figure 3) each having a respective piston 50 connected to a common buffer 52. The movable stabiliser 44 can be moved between a first position where it, and in 25 particular the buffer 52, contacts an inside surface of the pipe 20 (as shown in Figures 2 and 3) and a second position where the movable stabiliser 44 (i.e. buffer 52) is spaced from the inside surface of the pipe 20. The movable stabiliser 44 when in the second position is spaced by a distance sufficient to enable the carriage 12 to be moved along the pipe 20. 30 The fixed stabilisers 46 are in the general form of rectangular frames attached to the carriage and extending by a distance such that when the carriage 12 is in the pipe 12, and the wheels 38 are lifted from the surface of the pipe 20 the stabilisers 46 contact the inside of the pipe 20. 35 The welder application mechanism 18 is arranged so that it can linearly move the welder 22 when attached to the arm 14 between a deployed position where 2902978_1 (GHMatlrs) P88556 AU -5 the welder 22 is in operative contact with the inside surface of the pipe enabling the welder 22 to make a weld on the inside surface; and a park or retracted position, where the welder is spaced from the inside surface. Here the inside surface is the inside surface of a collar or sleeve inserted inside the pipe. That 5 is, the pipe 20 is to be considered both a primary or outer pipe which is undergoing repair. For example a concrete pipe, and a number of inner sleeves or collars placed inside the primary pipe for the purposes of forming a lining to the primary pipe. 10 When the welder 22 is in operative contact with the inside surface of the pipe, plastics material extruded from the welder forms a bead of molten material. When the arm 14 is rotated this bead is progressively laid circumferentially about the pipe generally between abutting ends of adjacent collars or sleeves. This forms a complete rotary join and seal between the adjacent collars or 15 sleeves. When the welder application mechanism 18 is in the park or retracted position, it holds the welder 22 at a location where the welder does not significantly heat the inside surface of the pipe 20. 20 Electrical power is provided to the welder 22 via a power cord 54 which in turn may be plugged into a power socket held on the carriage 12. An umbilical cord provides power to the power socket (as well as compressed air to the accumulator). It will be recognised that as the arm 14 rotates the power cord 25 54 will commence winding about the axis 42. Eventually, the cord 54 will become fully wound and prohibit further rotation of the arm 14. Prior to this occurring in one form of the system 10, the direction of rotation of the arm 14 is rotated. However in an alternate embodiment a rotary power coupling is provided to enable transmission of electrical power from a power source or a 30 power socket on the carriage to the welder 22 while the arm 14 is rotating. The rotary power coupling can be in the form for example of slip rings or a commutator type arrangement enabling electricity to pass between relative rotating bodies. In this embodiment the winding of the cord 54 is avoided by the use of a rotary power coupling and it is therefore possible to always rotate 35 the arm 14 in the same direction for each successive weld formed along the pipe. 2902978_1 (GHMotlers) P88556 AU -6 The rotary welding system 10 may also comprise a wheel retraction system enabling the wheels 38 to be retracted or lifted from the inside surface of the pipe 20 prior to deployment of the centralising stabiliser system 16 and rotation of arm 14. This simply lifts the wheels 38 from the inside surface so that the 5 fixed 46 contact the inside surface of the pipe. Subsequently the movable stabiliser 48 is moved to the first position where it contacts the inside surface of the pie 20. Once the weld has been completed the movable stabiliser 48 is moved to the second position and the wheels 38 lowered back into contact with the inside surface of the pipe 20 effectively lifting the fixed stabilisers 46 from 10 contact of the pipe 20. The carriage 12 can now be linearly moved along the pipe 20 to the location of the next weld. The wheel retraction system can be in the form of rams connected between the wheel axles and frame of the carriage which are operated to list and lower the wheel axles. In another embodiment it may be in the forms of a simple manually operated single wheeled lever or jack 15 similar to that used to lift racing cars when pitted for a tyre change. Modifications and variations of the rotary welding system 10 that are obvious to persons of ordinary skill in the art are deemed to be within the scope of the present invention the nature of which is to be determined from the above 20 description and the appended claims. 2902978_1 (GHMatters) P88558 AU

Claims (5)

1. A rotary welding system for welding an inside surface of a pipe, the rotary welding system comprising: 5 a carriage capable of travelling along an inside of a pipe, the carriage rotatably supporting a radially extending arm, the arm arranged to demountably receive a welding machine; a centralising stabiliser system supported on the carriage and arranged to fix the carriage in the pipe in a welding position where an axis of rotation of 10 the arm is substantially co-incident with an axis of the pipe, the centralising stabiliser system having at least one moveable stabiliser which is selectively movable between a first position where the movable stabiliser is in contact with the pipe and fixes the carriage in the welding position, and a second position where the movable stabiliser is spaced from the pipe a distance sufficient to 15 enable the carriage to move along the pipe; and, a welder application mechanism arranged to move a welding machine supported on the arm in a radial direction of the pipe to a deployed position where the welding machine is in operative contact with the inside surface of the pipe and, a park position where the welder is spaced from the inside surface of 20 the pipe.

2. The rotary welding system according to claim 1 wherein the centralising stabiliser system comprises at least two stationary stabilisers each of which contact the inside surface of the pipe when the movable stabiliser is in the first 25 position.

3. The rotary welding system according to claim 1 or 2 wherein the welder application mechanism comprises a pressure adjustment system arranged to enable variation in contact pressure of a welding machine when in the deployed 30 position against the inside surface of the pipe.

4. The rotary welding system according to any one of claims 1 to 3 comprising a rotary power coupling enabling electrical power transmission from a power source or a power socket on the carriage to a welding machine while 35 the arm is rotating.

5. The rotary welding system according to any one of claims 1 to 4 wherein 2902978_1 (GHMatters) P88555 AU -8 the carriage comprises a plurality of wheels enabling the carriage to be moved along the pipe, and a wheel retraction system arranged to selectively raise the wheels from, and lower the wheel to, contact an inside surface of the pipe. 5 2902978_1 (GHMatters) P88556.AU