CA2265215C

CA2265215C - Welding monitoring system

Info

Publication number: CA2265215C
Application number: CA002265215A
Authority: CA
Inventors: Christopher Hsu
Original assignee: Lincoln Global Inc
Current assignee: Lincoln Global Inc
Priority date: 1998-04-02
Filing date: 1999-03-11
Publication date: 2004-06-22
Anticipated expiration: 2019-03-11
Also published as: JP3141290B2; AU715597B2; ID22395A; CA2265215A1; AU2256999A; KR19990082797A; SG88749A1; RU2225285C2; JPH11320093A; SA99200002B1; KR100318301B1

Abstract

An apparatus and method of welding-two pipe sections together by use of an electrode and moving the electrode toward a gap between the pipe sections as the electrode is moved about the outer peripheral surface of the pipe sections during the welding operation.
During the welding process, welding parameters are recorded and correlated with a determined position. The position of the formed weld bead is determined by GPS satellites.

Description

ï»¿l0 l5 20 25 30 CA 02265215 2001-11-01 WELDING MONITORING SYSTEM The invention relates to the art of welding with an electric arc and more particularly to a method an apparatus for monitoring and controlling a welding system during the welding process. The present invention relates to the welding of pipe sections and monitoring thereof. United States Letters Patent No. 5,676,857 may be referred to as background information for its discussion of welding sections of pipe together. BACKGROUND OF THE INVENTION This invention relates to the ï¬eld of arc welding and particularly to an apparatus and method of welding two steel plates together by use of a consumable electrode and monitoring the welding parameters during the welding process, and more particularly to an apparatus and method of short circuiting arc welding pipe sections together with a cored electrode and the monitoring of the welding parameters and the determining of the location of the formed weld bead. Pipe systems are used to transport a variety of materials such as oil, gas and water to a desired location. Such pipe systems can extend hundreds and even thousands of miles. In many instances, these pipe systems traverse remote and many times undeveloped locations. In the art of welding the ends of large diameter pipe, it is conventional to machine the ends of each pipe to provide an external bevel and a narrow ï¬at land; bring the machined ends into axle alignment with the lands in close but usually spaced relationship to form a gap between the two ends of the pipe; and then to position one or more welding heads around the pipe so as to form a 360Â° weld. The weld bead is usually made in several steps. First, a root pass is made where at least the inner edges or lands of the pipes are fused and the gap between the lands filled with weld metal. Thereafter, several ï¬ller passes are made wherein the space formed by the bevel is filled so that the weld metal is at least flush with the outer surface of the pipe. The root pass is a very important part of the welding operation. Once the root pass is completed, the alignment of the pipes is assured. Thus, during the root pass, a 100% sound weld bead must be laid. Soundness of the weld bead means the complete fusion of both the lands clear through to the inner surface of the pipes and the complete ï¬lling of the ï»¿10 15 20 25 âCA 02265215 1999-03-ll L-2041 gap between the lands with the weld metal. Depositing of the weld metal in the gap is difï¬cult because the weld bead must be made by moving the weld heads around the pipe such that the welding position varies from downhand welding, vertical up or down welding, to overhead weld as the root pass is formed around the pipe. Furthermore, weld metal formed during the root pass should ï¬ll the gap between the pipe sections, but should not be allowed to pass through the gap and accumulate on the interior surface of the pipe. The weld bead should also form a relatively smooth surface with respect to the interior of the pipe which has very little, if any, protrusion into the interior of the pipe. Excessive protrusion of the weld bead in the pipe can: 1) create problems with apparatuses running inside the pipes to detect the soundness of the pipe system, and 2) cause unwanted ï¬uid mixing and turbulence as the ï¬uids are transported through the pipe system. A welding apparatus which creates an acceptable root bead is disclosed in United States Letters Patent No. 5,676,857. This patent discloses two welding bugs which continuously move on a track around the periphery of the pipe and include a special short circuiting power source to apply a root bead between the two ends of a pipe. This patent discloses that by selecting the proper bug speed and welding wire speed, only a slight burn through each edge of the bevel occurs and a small ï¬at weld is formed on the interior of the pipe. The Lincoln Electric Company has found that the welding apparatus disclosed in United States Letters Patent No. 5,676,857 can be modified for use with a ï¬ux cored electrode to obtain the desired composition-of the weld bead so that composition of the weld metal closely matches the composition of the metal pipe to form a strong and durable weld bead. The welding apparatus can be further modiï¬ed to ensure that a shielding gas protects the weld head from the adverse effects of the environment by using a self shielding ï¬ux system which forms a shielding gas during welding. Pipe systems are typically designed to be hundreds of miles in length. Due to the length of such pipe systems, the assembly of the pipe system may be formed in parts along the route of the pipe system. In view of the extensive length of the pipe systems and the importance of properly welding the pipe sections together, a team of welding technicians must be present to inspect the progress and quality of the pipe system and the quality of the weld bead formed between each pipe -2- ï»¿10 15 20 25 CA 02265215 1999-03-ll L-2041 section. In remote locations, the costs associated with using a team of technicians can be very costly. Such costs may prevent the pipe line ï¬'om ever being built. In addition, the team of technicians may be exposed to undesirable conditions when laying the pipe system in remote and/or undeveloped locations. Such undesirable conditions may adversely affect the health of the technicians and/or impair their ability to_ constantly monitor the quality of the welding process, thus causing delays, increased costs and defective weld beads along the pipe system. In addition to the problems associated with the maintaining of a team of technicians at the welding site, there are inherent problems associated with the determination of the progress of welding along the pipe line and identifying the location of a welding problem or other problem which has occurred âalong the pipe line. In remote and/or undeveloped locations, it can be very difï¬cult, if not impossible, to ascertain the geographic location of the welder along the pipe system and the location of the weld beads formed by the welder along the pipe line so as to report the progress and/or problems of the welding process. In view of the problems associated with the welding of pipe sections of large pipe systems, there is a need for a welding monitoring system which monitors the quality of a formed weld bead and the location of such weld bead. SUMMARY OF THE INVENTION The present invention relates to a method and apparatus of welding together two steel plates and monitoring the parameters of the welding process and more particularly to a method and apparatus of welding pipe sections together and to monitor one or more welding parameters during the formation of the weld bead between the pipe sections and associating such welding parameters with a location. However, the invention has broader applications and can be used to weld together other long metal workpieces such as track rails, airplane and ship components, bridges, etc.. In accordance with the preferred embodiment of the present invention, there is provided a workpiece having one or more components, a welder designed to produce a weld bead to weld one or more components of the workpiece, a welding monitor to record one or more parameters of the welding process, and a location identiï¬er to determine the location of a formed weld bead. The I -3- ï»¿10 15 20 25 CA 02265215 1999-03-ll L-2041 monitored welding parameters can include, but are not limited to, voltage and/or current across the electrode, voltage and/or current produced byethe power supply, electrode type and/or electrode feed rates, ï¬ux type and/or ï¬ux feed rates, shielding gas type and/or shielding gas feedrates, welding gas type and/or welding gas feedrates, welding cycle, direction and/or speed of welding head, time of day, ambient temperature and/or conditions, date, type of welding procedure, position of the welding head on the workpiece, interruptions during the welding process, errors (electronic and/or mechanical) during the welding process, the type and/or shape of the workpiece. One or more of these parameters or others can be electronically stored, electronically transferred to another location, printed out and/or displayed on a monitor. The location identiï¬er is designed to determine the location of a particular formed weld bead. This location information or location parameter can then be associated to one or more welding parameters of the formed weld bead. For long workpieces such as pipe lines, railroad tracks, and other large workpieces wherein the welder is moved along the workpiece to perform a welding operation at a plurality of locations, the location identiï¬er determines the position of the welder with respect to a certain reference point and the monitored welding parameters are correlated with or associated with the determined location. The recorded welding parameters and location parameter can be electronically stored, electronically transferred to another location, printed out and/or displayed on a monitor. The recorded data can be immediately analyzed and/or analyzed at a later time to review the welding parameters at a particular location on the workpiece for purposes of quality control. In accordance with another embodiment, the location identiï¬er is designed to detect two or more signals from a relatively ï¬xed location and to calculate a location parameter based upon the detected signals. The signals are preferably land based and/or global satellite based signals. In one preferred embodiment, the location identiï¬er calculates a location parameter using satellites of the Global Positioning System (GPS). The GPS is a multiple-satellite based radio positioning system in which the GPS satellite transmits data that allows a device to precisely measure the distance from selected ones of the GPS satellites and to thereaï¬er compute position and time parameters to a high degree of accuracy, using known triangulation techniques. The signals provided by the GPS can be -4- ....-.......W....._.....................l............,...a,... .. .. ï»¿10 15 20 25 CA 02265215 1999-03-ll L-2041 received both globally and continuously. The GPS comprises space and control segments. The space segment, when fully operational, consists of twenty-one operational satellites. These satellites are positioned in a constellation such that typically seven, but a minimum of four, satellites are observable by a device anywhere on or near the earthâs surface. Each satellite transmits signals on two ï¬equencies known as L1 (1575.42 MHZ) and L2 (l227.6 MH2), using spread spectrum techniques that employ spreading functions. C/A and P pseudo random noise (PRN) codes are transmitted on frequency L1 and/or L2. Both P and C/A codes contain data that enable a receiver to determine the range between a satellite and the device. Superimposed on both the P and C/A codes is the navigation (Nav) message. The Nav message contains GPS system time; a handover word used in connection with the transition from C/A code to P code tracking; ephemeris data for the particular satellites being tracked; and almanac data for all of the satellites in the constellation, including information regarding satellite health, coefï¬cients for the ionospheric delay model for C/A code users, and coefï¬cients used to calculate universal coordinated time (UTC). The control segment comprises a master control station (MCS) and a number of monitor stations. Updated ephemeris and clock data are uploaded to each satellite for re-transmission in each satelliteâs navigation message. The purpose of the control segment is to ensure that the information transmitted from the satellite is as accurate as possible. A GPS receiver includes an antenna assembly, an RF assembly, and a GPS processor assembly. The antenna assembly receives the L-band GPS signal and transmits the received signal to the RF assembly. The RF assembly mixes the L-band GPS signal down to a convenient IF frequency. Using various known techniques, the PRN code modulating the Lâband signal is tracked through code-correlation to measure the time of transmission of the signals from the satellite. The Doppler shift of the received L-band signal is also measured through a carrier tracking loop. The code correlation and carrier tracking function can be performed using either analog or digital processing. The control of the code and carrier tracking loops is provided by the GPS processor assembly. By differencing this measurement with the time of reception as determined by the deviceâs clock, the pseudo range between the device and the satellite being tracked may be determined. This pseudo range includes both the range to the satellite -5- ï»¿10 15 20 25 CA 02265215 1999-03-ll L-2 041 and the offset of the deviceâs clock from the GPS master time reference. The pseudo range measurements and navigation data from thesatellites are used to compute a position and calibrate the deviceâs clock offset, and to provide an indication of GPS time. The processing and memory ï¬mctions include monitoring channel status and control, signal acquisition and reacquisition, code and carrier tracking loops, computing pseudo range (PR) and delta range (DR) measurements, determining data edge timing, acquisition and storage of almanac and ephemeris data broadcast by the satellites, processor control and timing, address and command decoding, timed interrupt generation, interrupt acknowledgment control, and GPS timing, for example. The _ navigation processing and memory ï¬mctions performed by a the GPS receiver includeâ-satellite orbit calculations and satellite selection, atmospheric delay correction calculations, navigation solution computation, clock bias and rate estimates, computation of output information, and preprocessing and coordinate conversion of aiding information, for example. When using GPS to determine the location of the formed weld bead on the workpiece, the GPS provides global longitudinal and latitudinal accuracy of about lâl00m. In accordance with yet another aspect of the present invention, the location parameter and M one or more welding parameters are electronically stored and/or printed out for real-time review and/or for later review on-site and/or electronically stored for transmission to a remote location. The ability to record one or more welding parameters and associate such welding parameters with a location parameter enables a technician to periodically monitor the quality of a formed weld bead without having to be present at each welding location. Upon review of the recorded and/or printed data, the technician can determine what weld parameters existed during the formation of a particular weld bead along the workpiece. The technician may review the data hourly, daily, weekly or even monthly, and upon review of such data, determine the quality of a formed weld head at each location on the workpiece. In addition to or alternatively, the recorded data may be sent electronically via the telephone, Internet, satellite, ratio signal, etc. to a remote location for real time and/or delayed monitoring of the welding process at speciï¬c locations. When the welding process is performed at a remote location, a satellite may be the only way to form a communication link between the welding -6- ï»¿10, 15 20 25 CA 02265215 1999-03-ll L-2041 site and remote location. The data storage mechanism, such as a computer, can be designed to store information and, at preselected times during the day, a data link may be formed manually or automatically with a remote location via the satellite. In addition, the data storage unit may be designed to receive signals from a remote location and download, upon command, the information which is electronically stored. In accordance with still yet another aspect of the present invention, the welding controller for the welder is designed to receive information from a remote location via a telephone, Internet, satellite, radio signal, etc. and/or an on-site technician and thereby use such received information to alter one or more of the welding parameters during the welding process. In one particular embodiment, the weld controller alters one or more welding parameters upon analyzing the location parameter and determining that the welder is at a particular location. In another particular embodiment, a technician and/or control device at a remote location receives data from the welder via the telephone, Internet, satellite, radio signal, etc. and upon determining that the welder is at a particular location, sends updated information to the welding controller via the telephone, Internet, satellite, radio signal, etc. to alter one or more welding parameters. In accordance with another embodiment of the present invention, the workpiece includes two pipe sections which are positioned together and form a gap between the ends of the two pipe sections and are welded together by a welding system which includes a welding carriage positioned around the gap formed by the two pipe sections, a welding power supply, a welding current circuit which controls one or more welding parameters during the welding process, a location device that determines the location of the welder relative to a ï¬xed location, and a data storage device. The pipe sections are preferably aligned together by the use of clamps at least until a root bead has been applied to the gap between the pipe sections. The welding carriage preferably extends at least 180Â° around the circumference of the gap and preferably 360Â° around the circumference of the gap. The welding carriage is designed to slide along a track as it moves around the circumference of the gap, which track is secured about the periphery of the pipe. The welding carriage includes a drive motor to move the welding carriage along the track and around the circumference of the gap at a desired -7- ï»¿10 15 20 25 CA 02265215 1999-03-ll L-2041 speed. If an electrode is used during welding, the welding carriage includes a mechanism which controllably moves the consumable electrode toward the gap during the welding process. The mechanism for controlling the movement of the electrode may be integrated with or separate from the mechanism for controllably moving the carriage about the gap during welding. The location device is designed to receive two or more radio signals to calculate a location of the formed weld bead relative to a particular location. The data storage device is designed to store one or more welding parameters during the welding process and a location parameter from the location device. In accordance with yet another aspect of the present invention, the welding current circuit includes a ï¬rst circuit for controlling the current ï¬ow during the short circuit condition wherein the molten metal at the end of the consumable cored electrode is primarily transferred into the molten metal pool between the gap by surface tension action. The transfer current includes a high current pinch pulse across the shorted melted metal which helps facilitate the transfer of the molten metal from the electrode to the weld pool. The welding current circuit also includes a second circuit to create a melting current. The melting current is a high current pulse which is passed through the are which preferably has a preselected amount of energy or wattage used to melt a relatively constant volume of metal at the end of the consumable cored electrode when the electrode is spaced from the welding pool. The second circuit of the welding current circuit is preferably designed to provide a high energy boost during the initial portion of the arcing condition. The high current boost preferably has a preselected I(t) area or energy for melting a relatively constant volume of metal on the end of the consumable wire when the wire is spaced from the welding pool. Preferably after the initial high current plasma boost current, the high current is maintained for a preselected period of time and then subsequently decayed over a period of time until the desired amount of energy or wattage is applied to the electrode to melt the desired volume of the electrode. The welding current circuit is also preferably designed to limit the amount of energy directed to the electrode so as to prevent the unnecessary melting of the workpiece during the application of the weld bead and/or to maintain too hot of a weld bead during welding to thereby prevent molten metal from reducing the quality of the welded area. The welding current circuit also preferably includes a circuit to produce -3- ï»¿10 15 20 25 CA 02265215 1999-03-ll L-2041 a background current. The background current is a low level current which is maintained just above the level necessary to sustain an are after the termination of a short circuit condition. The background current is preferably maintained throughout the welding cycle to insure that the arc is not inadvertently extinguished during welding. The primary object of the present invention is the provision of a welding system which monitors one or more welding parameters during the formation of a weld bead on a workpiece and the determined location of the weld bead formed under by welding parameters. Another object of the present invention is the provision of a welding system which stores one or more welding parameters during the formation of a weld bead on a workpiece and the determined location of the weld bead formed by such welding parameters. Still another object of the present invention is the provision of a welding system which determines the location of a formed weld bead on a workpiece by receiving two or more signals from a relatively ï¬xed location and calculating a position based upon the received signals. Yet another object of the present invention is the provision of a welding system which utilizes GPS to determine the location of a formed weld bead. Another object of the present invention is the provision of a welding system transmits welding information and corresponding weld bead location information to remote locations. Still another object of the present invention is the provision of a welding system which provides access to welding information and corresponding weld bead location information from remote locations. Still yet another object of the present invention is the provision of a welding system which allows for real time or delayed quality control review of a welded workpiece. Another object of the present invention is the provision of a welding system which provides for cost effective quality control of welding operations in remote and/or undeveloped areas. Still another object of the present invention is the provision of a short circuiting arc welding system and method which forms a high quality weld bead between two metal plates. Another objective of the present invention is the provision of a short circuiting arc welding -9- ï»¿10 15 20 25, CA 02265215 2002-11-26 L-2041 system and method whic_h accurately tracks a desired current proï¬le during the welding of two metal plates together. _ I Other objectives and advantages will become apparent from the following description taken 0 together with the accompanied drawings. I 1 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram illustrating the welding system of the present invention using a satellite system to determine the location of the formed weld beadialong the pipeline; and . Figure 2 is a block diagram of the operation of the welding system. 0 PREFERRED EMBODIMENTS or THE INVENTION â Refening now to the drawings wherein the showings are for the purpose of illustrating the preferred embodiments of the invention only and not for the purpose of limiting same, Figure 1 illustrates a welding system 10 for welding pipe sections 20 of a pipe system togetherand for detennining the location of the formed weld bead 30 along. the pipe system. The pipe sections 20 â are illustrated as being welded by a short circuiting arc welding system 40. The preferreditype of short circuitingwelding is SURFACE TENSION TRANSFER or STT type of welding. The welding circuit and control arrangement for such type of welding is disclosed in United States âLetters Patent Nos.â 5,148,001; 5,001,326; 4,972,064; 4_,897,5_23:; 4,866,247; and 4,7 17,807._ The weldingsystem 10 for welding pipe sections 20 includes power supply 42 is preferably 1 a D.C._ power supply. The power supply preferably includes a motor, such as a gas motor, which powers a generator to produce an AC current. The AC current is _then rectiï¬ed by a rectiï¬er to form a -DC current. A phase controller controls the rectifier to produce a substantially uniform DC current. The current is then directed into a pulse widthrnodulator. The shapes of the pulse Â° H widths are controlled by a shaping circuit to thereby create a desired pulse with the DC. current. As can be appreciated, the power supply 42 need not be a rectiï¬ed output but can be any other appropriate DC source. The DC current from the pulse width modulator is directedacross a welding ' area which includes a consumable cored electrode 50 _ andpipe section 20. -10- ï»¿10 15 20 25 CA 02265215 1999-03-ll L-2041 Referring to the welding of the pipe section 20, the current to electrode 50 alternates between a short circuit condition when the electrode 50 engages pipe sections 20 and an arcing condition where the electrode 50 is spaced ï¬'om the pipe sections 20. During the arcing condition, an electric arc is created between the pipe and the electrode for purposes of melting and maintaining molten the end of the electrode as it is fed toward pipe sections for a subsequent short circuit condition. Referring to Figure 1, each pipe section 20 includes an edge 22. Edge 22 is a beveled surface which forms a groove when two pipe sections are positioned closely adjacent to one another. When two pipe sections are positioned next to one another, the pipe edges are spaced apart such that a gap 24 exists between the pipe edges. In accordance with known practice, the pipe edges are positioned and secured together, preferably by clamps, until at least a root bead is applied to the groove between the pipe edges, thereby ï¬lling the gap. A pipe ground engages the pipe to complete the arc circuit between electrode 50 and the pipe sections 20. Electrode 50 is unwound ï¬om electrode and spool 52 directed toward gap 24 between the two pipe ends by electrode nozzle 44. During the welding cycle, the electrode is fed through electrode nozzle 44 so as to transfer the molten metal at the end of the electrode into the gap between the pipe ends to form a weld bead 30. Electrode 50 is a consumable cored electrode which includes an outer metal sheath and an electrode core. Preferably the metal electrode sheath is made up of carbon steel, stainless steel or some other type of metal or metal alloy. Preferably the composition of the metal sheath is selected to be similar to the base metal component of the pipe sections 20. The electrode core preferably includes ï¬uxing agents and/or alloy and metals. F luxing agents may include compounds to create a slag over the weld bead to protect the weld bead until it solidiï¬es, to retain the weld bead in position until it solidiï¬es and/or to shield the weld metal during the fonnation of the weld bead. The ï¬ux may also include components which produce a shielding gas to protect the weld bead from the adverse effects of the environment. Preferably the ï¬ux components include ï¬uoride and/or carbonate to generate a shielding gas during welding so as to eliminate the need for external shielding gases during welding. When a self shielding electrode is used, the need for an external shielding gas is eliminated. The slag which forms on the weld bead further shields the weld bead -11- ï»¿10 15 20 25 CA 02265215 1999-03-ll L-2041 from the environment, thus resulting in the formation of quality weld beads. The alloying agents are preferably included in the electrode core. The alloying agents are selected such that the alloying agents in combination with the composition of the metal electrode sheath form a weld bead having a composition substantially similar to the metal composition of the pipes 20. A desired current profile to produce low spatter during welding and to prevent the weld bead from passing through the gap and into the interior of the pipe system includes a pinch portion, a plasma boost portion, a plasma portion and a background portion wherein the arc is to be maintained.â The plasma boost portion includes a decaying portion referred to as the plasma portion. Following the decaying portion, the welding circuit shiï¬s to the background current level whichâ maintains the plasma or arc. The welding circuit maintains a preselected background current level, thereby preventing the current level through the are from ever falling below the preselected current low current level and allowing the arc to extinguish. The welding circuit is designed to produce all the melting of the electrode during the plasma boost and plasma portion of the welding cycle. Further melting of electrode 50 does not take place when the background current level occurs since the IR necessary for melting the electrode is not obtainable through an are maintained only by the background current. Thus, the background current only serves to maintain the arc and the ball of molten metal in the molten state. The amount of molten metal at the end of electrode 50 which is formed by the plasma boost and plasma portion is selected to melt a preselected volume of molten metal at the end of the electrode, and the plasma portion of the current is reduced to the background current once the preselected volume is obtained. The duration of the plasma boost and plasma portion is also selected to prevent unnecessary melting of the metal around pipe ends 22. Such over- melting of the metal can result in the weld metal seeping into the interiorâ of the pipe sections. During the formation of the molten metal ball, the jet forces of the high current repel the melted metal from the welding pool until the preselected amount of molten metal has been melted at the end of the electrode. Once the current is reduced, the molten metal is allowed to form into a ball and the molten metal pool in the gap is allowed to stabilize, thereby allowing for a smooth contact between the substantially spherical ball and the quelled weld metal pool. The desired amount of molten metal -12- ï»¿10 15 20 25 CA 02265215 1999-03-ll Lâ2041 at the end of the electrode is controlled by directing a preselected amount of energy or wattage into the electrode during the plasma portion of the welding cycle. All during the time the molten metal ball is being formed at the end of the electrode, the core components are releasing shielding gases to shield the molten ball and the weld metal in the gap from the atmosphere. The shield gases continue until the molten ball is transferred into the molten metal in the gap. Once the molten metal ball is formed during the plasma boost and the plasma portion of the welding cycle, the molten ball is forced into the molten pool by feeding the electrode into the pool, thereby forming a short circuit condition. When the melted metal ball engages the molten metal pool, it is transferred into the pool by surface tension. This action causes an ultimate necking down of the molten metal extending between the pool and the wire in the electrode, and then a rupture and separation of the ball ï¬om the wire occurs. Since there is only a low background current during the separation, little if any spatter occurs. Preferably, the necking of the molten metal ball is monitored such that when the neck rapidly reduces in diameter by electric pits, the current ï¬ow during the pinch curve increases more gradually until a detection of an impending fuse is obtained. Once the detection of an impending fuse occurs, the current is reduced to the background current until the molten metal at the end of the electrode transfers into the weld pool. The welding cycle which is repeated several times per second must be accurately controlled by a welding circuit to reduce spatter during the welding cycle. In the preferred embodiment, the operating frequency of the pulse width modulator controller is 20 KHz with a width of the successive current pulse being determined by a current shape controller. The demanded current for the welding cycle changes 220,000 times each second. Since the highest rate of the welding cycle is generally in the neighborhood of 100 to 400 cycles per second, many update pulses are provided during each , welding cycle. Referring to Figure 1, a welding monitor 60 is provided which monitors one or more welding parameters during the formation of weld bead 30. Preferably welding monitor 60 monitors the current to electrode 50, the feed rate of electrode 50, the total amount of energy to electrode 50 during each weld cycle, and the speed at which the welding head travels around pipe sections 20. -13- ï»¿10 15 20 25 CA 02265215 2002-11-26 L-2 04 1 Additional welding parameters may be monitored. Furthermore, data from other sensors and/or inspection instruments may be monitored by welding monitor 60. Welding monitor 60 includes a display to allow a technician to view real-time and/or historical data which is or has been monitored by welding monitor 60. Welding monitor 60 also includes a data entry arrangement 64 to a) allow a technician to alter one or more welding parameters to welder 40, b) display different data on display 62, 3) access historic data, d) activate or deactivate a welding control program or some other operation. Preferably welding monitor 60 includes one or more components of the welding circuit that controls the current to electrode 50. Welding monitor 60 includes a data storage device to store a portion or all of the monitored information. Preferably, one or more welding parameters are stored on a disk drive or tape. A sufficient number of welding parameters are preferably stored so that the quality of the weld bead 30 formed between the two pipe ends 22 can be reviewedâ by a technician. Welding monitor 60 also includes a location circuit to locate the geographic position of formed weld bead 30. The location circuit includes an antenna 66, a GPS reference receiver and a ' microprocessor for calculating the position of the formed weld bead. Antenna 66 may comprise any of a number of commercially available low-gain antennas. The GPS reference receiver is designed to determine the global latitude and longitude of the formed weld bead welding system by sensing the signals 70 ï¬om satellites 80. A memory unit is provided in welding monitor 60 for storing location information supplied by a GPS unit, record the history of travel of the GPS unit, and include information corresponding to the global latitude and longitude information. A clock is provided in welding monitor 60 for supplying time and date information to the tracking circuit. The welding monitor 60 preferably includes a telecommunicating circuit to link to a remote location so as to upload and/or download information to and from the welding monitor. Preferably aptelephone system and a satellite transmission unit are included in the welding monitor to provide a data link to a remote location. The operation of the GPS tracking circuit is known in the art and will not be further described. The welding system 10 shown in Figure 1 may include a welding carriage adapted to move the welding head, e.g. electrode 50, about the outer peripheral surface of the plates and along a gap between the plates. The welding carriage may continuously move along the plates. The speed of the welding carriage may be varied. Referring to Figure 2, the operation of the welding system will now be brieï¬y described. -14- ï»¿10 15 20 CA 02265215 1999-03-ll L-2041 The welding circuit includes preset and/or loaded welding parameters. The welding circuit controls the formation of the weld bead 30 on pipe sections 20. Weld monitor 60 monitors and stores various welding parameters during the formation of the weld bead. The welding monitor also monitors and stores information provided by other sensors and inspection instruments used to form the pipe system. The monitored information is stored, preferably on a disk drive. As the weld bead is being formed, the positioning circuit senses signals 70 from GPS satellites 80. Preferably three or more signals are sensed and processed to determine the global longitudinal and latitudinal position of the formed weld bead. The positional information is correlated with the monitored parameters and stored on the disk drive. The stored location and corresponding monitored parameters can be immediately reviewed or later reviewed on-site or at a remote site via telephone, Internet, radio wave or satellite connection. A technician, upon reviewing the recorded data on-site and/or at a remote location can review the stored information to determine the quality of a formed weld bead at a particular location along the pipe system. The technician after reviewing the data can input new welding parameters for future weld bead formation and/or correct a problem with a previously formed weld bead. The ability of the welding system to provide information on how a particular weld bead is formed and the location of such weld bead along a pipe system, allows a technician to monitor welding operations world-wide and to ensure that quality weld beads are formed. The recorded information can be used to ascertain future failure problems of a weld bead and/or to correct a problem with a previously formed weld bead. The invention has been described with reference to a preferred embodiment and alternates thereof. It is believed that many modifications and alterations to the embodiments disclosed will readily suggest themselves to one skilled in the art upon reading and understanding the detailed description of the invention. It is intended to include all such modiï¬cations and alterations insofar as they come within the scope of the present invention. -15-

Claims

What is claimed is:

1. A welding system for welding two plates together which comprises:
a. a welder including a welding circuit and a welding head to supply heat to said plates to form a weld bead therebetween, said welding circuit directing a controlled amount of current through an electrode to form said weld bead on said two plates;
b. a welding monitor to monitor at least one welding parameter during the formation of said weld bead;
c. a positioning circuit to sense a plurality of electromagnetic signals originating from a relatively fixed, remote location and to determine the location of said formed weld bead;
d. a record circuit to electronically record mechanical and electronic errors during a welding process and said determined location to the remote location; and, e. a transmit circuit to transfer said recorded information to a location remote of said welder.

2. The welding system as defined in claim 1, wherein said positioning circuit senses a plurality of signals from global satellites and determines a global longitudinal and latitudinal position of said formed weld bead.

3. The welding system as defined in claim 1 or 2, wherein the record and transmit circuit transmits at least a portion of said one monitored welding parameter in real-time-

4. The welding system as defined in any one of claims 1 to 3, wherein said record circuit records additional information selected from the group consisting of the amount voltage across the electrode, the amount of current across the electrode, the amount of voltage produced by the power supply, the voltage profile, the amount of current produced by the power supply, the current profile, the amount of power directed to the electrode, the rate of power directed to the electrode, the electrode type, the electrode feed rate, the flux type, the flux feed rate, the shielding gas type, the shielding gas feed rate, the welding gas type, the welding gas feed rate, the welding cycle, the direction of movement of welding head, the rate of speed of welding head, the time of day, the ambient conditions, the date, the type of welding procedure, the type of power supply, the type of welder, the type of welding components, the position of the welding head on the workpiece, the polarity of the electrode during welding, the interruptions during the welding process, the type of the workpiece, the shape of the workpiece, and combinations thereof.

5. The welding system as defined in any one of claims 1 to 4, wherein the welding circuit has a first circuit to create a transfer current arid a second circuit to create a melting current, said second circuit supplying a sufficient amount of current to said electrode to form said weld bead on said two plates.

6. The wielding system as defined in any one of claims 1 to 5, wherein the welding circuit creates a series of small width current pulses and controls the polarity of the current pulses between a first polarity with said electrode which is positive and a second polarity with said electrode which is negative, said series of current pulses constituting a welding cycle with a short circuit transfer portion and a plasma arc melting portion, said current pulses in said cycle each having a given electrical polarity of said electrode with respect to said two plates.

7. The welding system as defined in any one of claims 1 to 6, further including a welding carriage adapted to move said welding head about the outer peripheral surface of said plates sections and along a gap between said plates.

8. The welding system as defined in any one of claims 1 to 7, further including a consumable electrode for forming said weld bead.

9. The welding system as defined in claim 8, wherein said consumable electrode is a cored electrode.

10. The welding system as defined in claim 8 or 9, wherein said electrode is a self-shielding electrode.

11. The welding system as defined in any one of claims 8 to 10, wherein said electrode includes alloying components to form said weld bead having a substantially similar composition as the composition of said plates.

12. The welding system as defined in any one of claims 5 to 11, wherein said second circuit directs a preselected amount of energy to said electrode to melt a relatively constant volume of an electrode during each welding cycle.

13. The welding system as defined in any one of claims 5 to 12, wherein said welding circuit limits an amount of energy directed to said electrode to prevent molten metal from passing through a gap between said two plates.

14. The welding system as defined in any one of claims 5 to 13, wherein said welding circuit reduces the amount of current to said electrode before said molten metal on said electrode forms a short circuit condition with a gap between said two plates.

15. The welding system as defined in any one of claims 5 to 14, wherein said welding circuit creates an alternating current.

16. The welding system as defined in any one of claims 5 to 15, wherein said welding circuit forms part of an STT power supply.

17. The welding system as defined in any one of claims 5 to 16, wherein said electrode moves about the outer peripheral surface of said metal plates and substantially along a gap between the plates.

18. The welding system as defined in claim 7, wherein said welding carriage continuously moves along said plates sections and wherein the speed of said welding carriage can be varied.

19. The welding system as defined in any one of claims 5 to 18, wherein said two metal plates are two pipe sections.

20. A method of welding two plates together, said method comprising the steps of a. providing a welding circuit, a welding head and a consumable electrode;
b. moving said welding head toward said plates;
c. directing a controlled amount of current through said electrode to form a weld bead between said plates;
d. monitoring mechanical and electrical errors during the formation of said weld bead;
e. determining the position of said formed weld bead relative to a remote location by sensing a plurality of electromagnetic signals originating from the remote location;
f. electronically recording and saving said monitored mechanical and electrical errors and associating said errors with said determined position; and, g. transmitting said recorded information to a location remote of said welder.

21. The method as defined in claim 20, wherein the transmitting step transmits at least a portion of said one monitored errors in real-time.

22. The method as defined in claim 20 or 21, further including the step of monitoring and recording welding parameters selected from the group consisting of the amount voltage across the electrode, the amount of current across the electrode, the amount of voltage produced by the power supply, the voltage profile, the amount of current produced by the power supply, the current profile, the amount of power directed to the electrode, the rate of power directed to the electrode, the electrode type, the electrode feed rate, the flux type, the flux feed rate, the shielding gas type, the shielding gas feed rate, the welding gas type, the welding gas feed rate, the welding cycle, the direction of movement of welding head, the rate of speed of welding head, the time of day, the ambient conditions, the date, the type of welding procedure, the type of power supply, the type of welder, the type of welding components, the position of the welding head on the workpiece, the polarity of the electrode during welding, the interruptions during the welding process, the type of the workpiece, the shape of the workpiece, and combinations thereof.

23. The method as defined in any one of claims 20 to 22, wherein said step of determining the position of said formed weld includes the step of sensing a plurality of signals from global satellites.

24. The method as defined in any one of claims 20 to 23, wherein said step of determining the position of said formed weld includes the step of determining a global longitudinal and a lateral position of said formed weld bead.

25. The method as defined in any one of claims 20 to 24, wherein said two plates are ends of two pipe sections.

26. The method as defined in any one of claims 20 to 25, wherein said weld bead is formed from a consumable electrode.

27. The method as defined in claim 26, wherein said consumable electrode is a self --shielding electrode.

28. The method as defined in any one of claim 26 or 27, wherein said electrode is a cored electrode.

29. The method as defined in any one of claims 26 to 28, wherein said electrode includes alloying components to form said weld bead having a substantially similar composition as the composition of said two plates.

30. The method as defined in any one of claims 26 to 28, further including the step of providing a welding carriage which moves said welding head about the outer peripheral surface of said plates.

31. The method as defined in claim 30, wherein the speed of said welding carriage is varied as said carriage moves about said plates.

32. ~The method as defined in any one of claims 26 to 31, further including the step of melting said electrode by an electric wave, said step of directing a preselected energy to said electrode to melt a relatively constant volume of said electrode during each welding cycle.

33. ~The method as defined in claim 32, wherein said electric wave includes a background current, said background current having a high inductance component and a low level just above the level necessary to sustain an arc after the termination of a short circuit condition which is maintained throughout each welding cycle.

34. ~The method as defined in any one of claims 26 to 33, further including the step of limiting the amount of energy directed to said electrode to prevent molten metal from passing through a gap between said two plates.

35. ~The method as defined in any one of claims 26 to 34, further including the step of reducing the amount of current to said electrode prior to said molten metal on said electrode forms a short circuit condition with a gap between said two plates.

36. ~The method as defined in any one of claims 32 to 36, wherein said electric wave is an alternating current.

37. ~The method as defined in any one of claims 32 to 36, wherein said electric wave is formed by an STT power supply.

38. ~The method as defined in any one of claims 26 to 37, including the step of moving said electrode about the outer peripheral surface of said metal plates and substantially along a gap between the plates.

39. ~The method as defined in any one of claims 20 to 38, wherein said metal plates are two pipe sections.