DESC:A METHOD FOR EVALUATING ARC STABILITY USING FOURIER TRANSFORM
FIELD OF INVENTION
[001] The present invention relates to a method for evaluation of arc welding power sources testing in general and specifically to a method to determine arc stability through Fourier Transform analysis.
BACKGROUND OF THE INVENTION
[002] Generally, the arc welding consists of several processes that utilize an electric arc produced by electric current passing through an ionized gas as a source of heat to melt and join metals. Typically, the welding arc is formed between the piece being welded, or base metal, and an electrode. A "good" weld is commonly defined as a weld which fuses metals in a bond having strength to withstand any stresses which are expected to be encountered.
[003] There are many causes of defects which can occur during the welding process, preventing this fusion from occurring and creating welds which will often not withstand stress. Specific types of weld defects which can occur during the arc welding process include a condition commonly referred to as spatter in which a considerable amount of spatter or filler metal is produced which does not enter the weld due to motion of the filler metal during the welding process. Loss of shielding gas, used to protect the arc and weld zones from air and provide desired arc characteristics in gas metal arc welding, can further result in weld defects.
[004] The patent search has been carried out on this subject, but the complete information related to this invention is not directly available. The following patent documents (US 6,621,049 B2, US 5,756,967 A, US 6,943,318 B2, US 6,703,585 B2, US 6,441,342 B1, US 8,569,646 B2, JP2017535431A, US 8,063,340 B2, JP2010184256A, US20090188903A1, US 9,836,995 B2, US 8,131,401 B2, US 5,569,984 A, and US20120205359A1). These prior art documents relate to method or approach to estimate arc stability using different analyses.
[005] The prior art document US 6,621,049 B2, assigned to “Central Motor Wheel Co Ltd”. The prior art relates to an apparatus for assessing start-of-weld and steady state welding stability in pulsed arc consumable electrode gas-shielded welding. According to the present welding stability assessment apparatus, in order to obtain a pass/fail decision on start-of-weld welding stability for pulsed arc welding, an irregularity value is computed by a computer means, based on detected values from a detector means; and a pass/fail decision is made by an assessment means, thus making it possible to perform accurate assessment of start-of-weld welding stability in pulsed-arc welding.
[006] The prior art document US 5,756,967 A, assigned to GOVERNMENT OF United States. The prior art relates to a method for sensing and controlling an arc welding process employs a high equency rate of sampling of electrical signals from the welding circuit. The sampled signals are operated upon by predetermined processes to determine electrical resistance, shielding gas quality, and short circuit frequency. The process measurements are compared to a predetermined set of tolerance levels and evaluated using a window technique that updates the evaluation of the data samples at the sampling rate. This prior art document correlates to predetermined set of values and does not analyses or validates the measurements using scientific approach.
[007] The prior art document US 6,943,318 B2, assigned to “Daido Tokushuko KK”. The prior art relates to a contact provided in a welding tip of an arc welding apparatus includes a tip body adapted to be mounted to a welding torch body and a tip end member formed integrally therewith. The tip end member is divided into two parts, i.e., first and second halves by means of a slit formed along the axis of the tip end member, and the first half having the predetermined rigidity is movable around a connection between itself and the tip body. A spring member fitted on the tip end member applies a spring force thereto, whereby the contact has improved durability.
[008] The prior art document US 6,703,585 B2, assigned to Central Motor Wheel Co. Ltd. The prior art is one of the closest that could be related to the filed patent. This prior art relates to an arc welding quality evaluation apparatus for consumable electrode gas shielded arc welding comprises a heat input detection means 8 for detecting heat input applied to a work piece to be welded; a welding time detection means 11 for detecting the welding time of the work piece; a spatter weight detection means 16 for detecting the weight of spatter produced during the welding time of the work piece; a heat compensation means 17 for compensating for heat loss due to spatter occurring during the welding time of the work piece; an effective heat input computation means 12 for computing effective heat input per unit welding time, based on detected values of the detection means 8 and 11, and a compensation value of the heat compensation means 17; and a weld quality assessment means 22 for comparing an output of the effective heat input computation means 12 to a reference standard value, and assessing weld quality acceptability based on the degree of separation of the computation means output from the reference standard value.
[009] The prior art document US 6,441,342 B1, assigned to “Lincoln Global Inc.”. The prior art corresponds to a virtual welding station where a monitor for an electric arc welder s created as the welder performs a selected arc welding process by creating actual welding parameters, such as arc current and arc voltage, between an advancing welding wire and a work piece, where the process involves an arc and is defined by a series of rapidly repeating wave shapes constituting a weld cycle with a cycle time, the wave shapes are each segmented into time states having command signals corresponding to the actual parameters and a time duration. The monitor selects a specific wave shape state, reads one of the actual parameters, compare the actual read parameter with a function of the command signal corresponding to the actual parameter, and uses-the comparison to generate a characteristic of the welding process during the selected state.
[0010] The prior art document US 8,569,646 B2, assigned to “Lincoln Global Inc.”. The prior art is similar to the description of weld quality monitoring systems that are built all around. The monitor is capable of monitoring variables during a welding process and weighting the variables accordingly, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications. These are passive parameters that are used for quality assurance for weld but do not comment on the process parameters in its dynamic state.
[0011] The prior art document JP2017535431A, assigned to “Lincoln Global Inc.”. The prior art relates to system and method for arc welding process monitoring. The system, according to the state of the waveform in the welding process variables are monitored, and in accordance with the weighting variables, welding defect is detected, defect diagnosis of possible causes, by quantifying the overall quality of the welding, welding is used in acquiring data indicating and, automated welding processes and improve productivity for quality control, a proper welding technique taught, specifies the cost savings for the welding process, welding process or in different applications can be used as a pre-set optimum welding set is derived. It explains more on the recording and display of the process parameters and do not involve any mathematical approach to comment on the dynamic characteristic of the process. It also does not have any provision to comment on arc stability.
[0012] The prior art document US 8,063,340 B2, assigned to “University of Michigan” and “GM Global Technology Operations LLC”. The prior art relates to a method for monitoring and controlling the process consistency of an arc welding process. The weld voltage signal is monitored and analysed to determine the occurrence of the detachment of a weld droplet. The weld droplet detachment is determined via statistical techniques as having occurred at a normal interval following a prior detachment indicating consistent weld process or as a sporadic detachment having occurred at an irregular interval with respect to the prior detachment and indicating inconsistent weld process. The weld process is adjusted by controlling the weld process variables to maximize the predominance of droplet detachment at normal intervals and minimize the occurrence of the sporadic detachments. It is suggested here that the approach suggested by the current patent could be included in this system as an algorithm for getting better results.
[0013] The prior art document JP2010184256A, assigned to “Kobe Steel Ltd”. The prior art relates to a welding control apparatus includes an integrator for starting calculation of a voltage error integral value Sv2 when a first pulse period ends and a second pulse period starts in a pulse cycle, based on various data. The prior art invention strives to provide a technology for correctly suppressing a variation in arc length caused by disturbance in the pulse arc welding of consumable electrode type. It takes all process parameters and adjust the welding arc control parameters. This is a feedback circuit that hypothesize the resultant control action as a resultant of independent set of parameters and does not try to predict/estimate the individual parameters.
[0014] The prior art document US20090188903A1, assigned to “University of Michigan” and “GM Global Technology Operations LLC”. The prior art relates to a method for monitoring and controlling the process consistency of an arc welding process. The weld voltage signal is monitored and analysed to determine the occurrence of the detachment of a weld droplet. The weld droplet detachment is determined via statistical techniques as having occurred at a normal interval following a prior detachment indicating consistent weld process or as a sporadic detachment having occurred at an irregular interval with respect to the prior detachment and indicating inconsistent weld process. The weld process is adjusted by controlling the weld process variables to maximize the predominance of droplet detachment at normal intervals and minimize the occurrence of the sporadic detachments. This method also strives to get the control parameters for droplet detachment of GMAW process in general. The method is used as a feedback for controlling the detachment and there is not talk on arc stability of these parameters.
[0015] The prior art document US 9,836,995 B2, assigned to “Lincoln Global Inc.”. The prior art relates to a system for simulating, in virtual reality space, a weld puddle having real-time molten metal fluidity and heat dissipation characteristics. The system is further capable of importing data into the virtual reality welding system and analysing the data to characterize a student welder's progress and to provide training. The weld process is simulated in the system in real time with welder’s hand movements and have no correlation with respect to the real time weld process characterization.
[0016] The prior art document US 8,131,401 B2, assigned to “POWER ANALYTICS CORP.”. The prior art relates to system and method for intelligent monitoring and management of an electrical system is disclosed in this invention. The system includes a data acquisition component, a power analytics server and a client terminal. The data acquisition component acquires real-time data output from the electrical system. The power analytics server is comprised of a real-time electrical system security index engine that calculates real-time system security index values from stability indices data generated from a virtual system model of the electrical system. The client terminal displays the system security index values to assess the security and stability of the electrical system. The system is used for evaluation of arc stability.
[0017] The prior art document US 5,569,984 A, assigned to “Philips North America LLC”. The prior art relates to a method for detecting arc instabilities in a gas discharge lamp by evaluating the deviations of an electrical parameter of the lamp. A method suitable for detecting frequencies at which acoustic resonance induced instabilities occur evaluates the deviations measured over a range of frequencies. Selection of an operating frequency to avoid acoustic resonance is based on an evaluation of the deviations, such as the frequency at which the lowest standard deviation occurs for the electrical parameter measured. Resonance detection is achieved both during run-up and the steady state substantially without inducing visible flicker. The method and ballast employ universal techniques suitable for operating HID lamps of different types, wattages and manufacturers despite the occurrence of acoustic resonance/arc instabilities among these lamps over a fairly broad frequency range. The concept and execution of the proposal is different from the process requirements of welding.
[0018] The prior art document US20120205359A1, assigned to “Lincoln Global Inc.”. The prior art relates to an arc welding system and methods. The system is capable of monitoring variables during a welding process, according to wave shape states, and weighting the variables accordingly, detecting defects of a weld, diagnosing possible causes of the defects, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications. The invention does not talk of ensuring weld quality in real time dynamics with respect to parameters including arc stability.
[0019] In accordance with the prior art documents are different from the present invention. The prior art documents were highlighted from a detailed review of that there exists no method or approach to estimate arc stability using Fourier Transform in the literature.
[0020] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
OBJECTS OF THE INVENTION
[0021] The principal object of the present invention is to evaluate welding arc stability dynamically during welding process by acquiring arc voltage and welding current and transforming the components.
[0022] Another object of the present invention is to identify the amplitude peaks in Frequency domain using Fourier Transform.
[0023] Yet another object of the present invention is to provide categorization of the arc stability as poor, satisfactory, and good.
[0024] Yet another object of the present invention is to retrieve a number of short circuits happening in the process and the corresponding response from welding power source from the information.
[0025] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION
[0026] One or more drawbacks are overcome through the processes claimed in the present invention along with the additional advantages. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[0027] The present subject matter relates to a method for evaluating arc stability dynamically during welding process by acquiring arc voltage and welding current and transforming the components to identifiable amplitude peaks in frequency domain using Fourier Transform. The method involves accessing quantum of stability associated with welding arc during a welding process such that the welding arc is recorded as a function of time with respect to welding voltage and current by using Hall effect sensor and a voltage sensor. The ability of power source is commented to deliver rated values of the voltage and current from statistical analysis. The data acquisition of the welding is provided by getting a data logger connected across the welding power source, wherein the data is converted into frequency domain using Fourier transform.
[0028] Accordingly, the arc stability can be categorized as poor, satisfactory, and good, when the nature of the arrangement of the individual frequency components. The differentiating factor in evaluation of arc stability is the application of Fourier Transform.
[0029] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0031] FIG. 1 illustrates schematic block diagram of system evaluating arc stability using Fourier transform, in accordance with a present subject matter; and
[0032] FIG. 2 illustrates flow diagram of method for evaluating arc stability using Fourier transform, in accordance with a present subject matter.
[0033] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0034] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0035] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0036] The present subject matter relates generally to The present subject matter relates to a methodology to evaluate arc stability dynamically during welding process by acquiring arc voltage and welding current and transforming the components to identifiable amplitude peaks in Frequency domain using Fourier Transform. From the nature of the arrangement of the individual frequency components, the arc stability can be categorized as poor, satisfactory, and good. The differentiating factor in evaluation of arc stability is the application of Fourier Transform as a tool which is unique and has not been attempted before.
[0037] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0038] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0039] Referring may be made as FIG. 1 illustrating schematic block diagram of system for evaluating arc stability using Fourier transform, in accordance with a present subject matter. The block diagram relates to the connections using a Hall effect sensor (for current) and a voltage sensor (for arc voltage) whose output will be sampled at a frequency of not less than 200 samples per second using Data Acquisition Hardware. The samples are taken to the custom made user interface that could read, log and trend the data.
[0040] Accordingly, the data logged from the welding process is analysed with respect to frequency domain analysis. The frequency domain analysis provides the amplitude of occurrence of distinct frequency components. It was observed during repeated trials that whenever there are isolated peaks of amplitude with unique occurrence and other components being subdued if the arc is stable. For a disturbed arc, the frequency components are more evenly distributed in terms of amplitude peaks and the likelihood of a dominant peak is minimal. Hence, it is inferred that there is a correlation between the frequency component distribution of arc voltage and current parameters with arc stability. The data stored is analysed both statistically and graphically for the logical flow indicated in Fig. 2 Flowchart to comment on the arc stability.
[0041] Referring may be made as FIG. 2 illustrating flow diagram of method for evaluating arc stability using Fourier transform, in accordance with a present subject matter. The method comprising the steps of accessing quantum of stability associated with welding arc during a welding process; and recording the welding arc as a function of time with respect to welding voltage and current by using Hall effect sensor and a voltage sensor. Hence, the process is subjected to data acquisition by getting a data logger connected across the welding power source. The data is highly disrupted by environmental and process conditions and in addition the measured values also have a low amplitude value. Hence, a suitable low pass filter is designed to isolate the actual signal from the measured parameter. The data now logged will be reflecting that of the process and will reveal the characteristics of the welding process as per the processing methodology.
[0042] In accordance with an embodiment of the present subject matter relates to provided the voltage and current which tends to respond with variations in the amplitude depending on the occurrence of the short circuits. The statistical methods are used to get values which reflect the time response characteristics. The ability of the power source to deliver the rated values of voltage and current can be commented from the statistical analysis. However, there is no uniqueness to the analysis as this will treat the frequency of occurrence only as a number. The number of short circuits happening in the process and the corresponding response from welding power source are to be retrieved from the information. Hence, the data is converted into frequency domain using Fourier Transform.
[0043] Accordingly, the process is hypothesised that instability is characterised by a finite frequency component that becomes repetitive when arc is unstable. Therefore, if the arc is to be deemed stable, there should not be multiple disturbances recorded at different frequencies. A disturbance is likely to create unstable dynamics which are going to be recorded with their unique frequency components. In case of unstable arc, these frequency components will increase and hence the Fourier transform will present a graph which provides with multiple frequency components in the range of 200 Hz. The less the frequency components in this range, more stable will be arc. This validation is visual and is supplemented with statistical parameters of time and frequency domain. The values that are proposed for the threshold are derived from the visual interpretation of arc stability during welding. A good power sourced should respond to the unstable arc with variation in process parameters. Hence, a feedback is provided if the analysis results in an unstable arc.
[0044] As shown in figure 2, at step 201, the data of arc voltage and welding current signals is recorded using Hall effect sensor and a voltage sensor as function of time. The data is recorded with the logger and time based record of the signals are made available. The data logger is interfaced with a computer in which a front end is developed for display of all data and analysis. The front end is made from NI LabVIEW software.
[0045] At step 202, the data is highly disrupted by environmental and process conditions and in addition the measured values also have a low amplitude value. Hence, a suitable low pass filter is designed to isolate the actual signal from the measured parameter. At step 203, the data now logged will be reflecting that of the process and will reveal the characteristics of the welding process as per the processing methodology.
[0046] At step 204, the weld process parameters of voltage and current are logged at high frequency and the data is transformed into a series of time response parameters aligned with short circuiting phenomena in welding. The short circuiting duration, peak, frequency and the surge are accounted and averaged for the time interval.
[0047] At step 205, the conversion of time domain signals (as recorded) to frequency domain signals (like Fourier Transform) is governed by the following mathematical formula:

[0048] When this information is converted into Fourier Transform, it can be inferred that each transient state of the welding process can be mapped for this uniqueness of frequency components. Hence, it is possible to ascertain whether the arc is stable by analysis of frequency components of the Fourier Transform. There will be no ambiguity or mismatch for stability identification as the frequency domain interpretation is immune to process and environmental disturbances and cannot be duplicated
[0049] At step 206, comparing the frequency component with the threshold values to decide the stability of the arc.
[0050] In one embodiment of the present subject matter, isolation of frequency ranges for different modes of metal transfers and inferring arc stability therein is possible as follows:
• If the frequency components fall between 0 to 200 Hz with a singular peak of more than 3 x 105 times, then the arc stability is good.
• If the frequency components fall between 0 to 200 Hz with multiple differentiable peaks in the region up to 3 x 105 times, then the arc stability is poor.
• If the frequency components fall between 0 to 200 Hz with a singular peak of less than3 x 105 times, then the arc stability is satisfactory.
[0051] At step 208, if arc is not stable, welding process variables are changed to receive the stable arc at step 209.
[0052] In accordance with an embodiment of the present subject matter, aggregation of voltage and current signals from an arc welding power source in terms of frequency components is unique for estimation and evaluation of arc stability.
[0053] In accordance with an embodiment of the present subject matter, to estimate the arc stability is proposed using Fourier Transform Analysis of welding process data. The weld process parameters of voltage and current are logged at high frequency and the data is transformed into a series of time response parameters aligned with short circuiting phenomena in welding. The short circuiting duration, peak, frequency and the surge are accounted and averaged for the time interval. When this information is converted into Fourier Transform, it can be inferred that each transient state of the welding process can be mapped for this uniqueness of frequency components. Hence, it is possible to ascertain whether the arc is stable by analysis of frequency components of the Fourier Transform. Therefore, the Fourier Transform analysis of frequency components will be no ambiguity or mismatch for stability identification as the frequency domain interpretation is immune to process and environmental disturbances.
[0054] In accordance with the present subject matter provides many advantages over conventional process. The arc stability is important attribute in welding which is to be considered of process quality metrics. The stable arc is important to achieve stable rate of metal transfer, reducing spatter, and effecting uniform penetration. However, the assessment of arc stability has been a subjective proposition with no quantitative representation. Welding is to be highly nonlinear process adds to the complexity of this assessment. Statistical approaches are unable to predict the uniqueness of the event occurrence so that the time response parameters of the system could be used for prediction or estimate of the arc stability.
[0055] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0056] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0057] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.
,CLAIMS:We claim:
1. A method for evaluating arc stability using Fourier transform, the method comprising the steps of:
receiving arc voltage and welding current data using Hall effect sensor and a voltage sensor as function of time;
isolating the time domain signals using low pass filters to obtain actual time domain signals;
converting received time domain signals into frequency domain signals using the Fourier Transform;
assessing stability of the arc stability by comparing the isolated frequency domain signals with threshold values.

2. The method as claimed in claim 1, wherein the arc stability is good when:
the isolated frequency domain signals fall between 0 to 200 Hz with a singular peak of more than 3 x 105 times.
3. The method as claimed in claim 1, wherein the arc stability is poor when:
the isolated frequency domain signals between 0 to 200 Hz with multiple differentiable peaks in the region up to 3 x 105 times.
4. The method as claimed in claim 1, wherein the arc stability is satisfactory when:
the isolated frequency domain signals between 0 to 200 Hz with a singular peak of less than3 x 105 times.

5. The method as claimed in claim 1, wherein the time domain signals converted into frequency domain signals using the Fourier Transform equations:

6. The method as claimed in claim 1, wherein the method further comprises controlling the weld process variables when arc is not stable.
7. The method as claimed in claim 1, wherein the voltage and current signals are aggregated from the arc welding power source in terms of frequency components.
8. The method as claimed in claim 1, wherein welding process parameters of the voltage and current are logged at high frequency and the data is transformed into a series of time response parameters aligned with short circuiting phenomena in welding.