Claims:We Claim:
1. A method for correction of buckling arising during fabrication and assembly of thin walled sheet metal panels, the method comprising:
marking of correction zones;
placing of fixture (200) within the marked zones by means of a stopper plate;
pumping of heat energy using gas burners up to a temperature value beyond which no metallurgical changes are observed; and
cooling up to ambient temperature.
2. The method as claimed in claim 1, wherein the fixture comprises of a rectangular stopper bar being attached to thin walled sheet metal panel (100).
3. The method as claimed in claim 1, wherein the bar is attached with the sheet metal panel (100) along the axis where area moment of inertia is maximum over the centerlines of stiffeners or two stiffened thin walled sheet metal panels.
4. The method as claimed in claim 1, wherein the gas burners are high velocity non-oxidizing gas burners.
5. The method as claimed in claim 1, wherein the cooling of the thin walled sheet metal panel (100) is a natural cooling process.
6. The method as claimed in claim 1, wherein the mounting of fixture (200) is dependent upon the direction of distortion.
7. The method as claimed in claim 1, wherein the direction of mounting of fixture (200) is perpendicular to the direction of the thin walled sheet metal panel (100) resulting into a force exerted by the fixture (200) wherein first the distortion increases and then plastic deformation occurs.
, Description:A METHOD FOR CORRECTION OF BUCKLING IN THIN WALLED SHEET METAL PANELS

FIELD OF INVENTION
[001] The present subject matter described herein, relates to a method for correction of buckling in metallic panels. More particularly, to a method for correction and correction of buckling arising during fabrication and assembly of thin walled sheet metal panels.
BACKGROUND, PRIOR ART AND PROBLEM IN PRIOR ART
[002] Thin plates or sheet metals are used in a variety of applications ranging from ducts, wind boxes of boilers to panel modules in ship building. In order to reduce the operational deflection and to strengthen the sheet metal, stiffeners are attached with the sheet metal at pre-determined locations. When thin sheets are welded with high section modulus stiffeners, distortion occurs at an amplified rate due to the eccentricity between the line of application of heat and the neutral axis of the stiffener.
[003] With the application of heat energy, as a part of fabrication process, high aspect ratio panels or in other words, sheet metal and thin plates distort, when the heat energy is sufficient to induce thermal stresses exceeding the yield stress of that particular material at elevated temperature. Reduction of distortions results in the escalation of residual stresses as they are complimentary in nature and hence, either of these occur when the other outcome is being controlled.
[004] Distortion, in general can be classified into longitudinal distortion, angular or twisting distortion and buckling or waviness. When the number of stiffeners increase, the magnitude of distortion also increases accompanied with the difficulty in correcting the distortion.
[005] Chinese patent CN 201410129396 describes a method for calculating the flame parameter in feeding the input for the correction of welding deformation of stiffened panel a planking and beam structure used in ship building applications. This method involves a pure thermal correction methodology and uses oxy acetylene flame for heating the distorted sheet metal.
[006] US patent US2969299A describes a method of retaining the preferred shape or flatness of the sheet metal by applying pressure on the sheet metal using rigid plates thereby enabling the thin sheet to slide in between to account for the thermal expansion. This is a control methodology as the distortion is prevented from happening and happens during the process of welding.
[007] However, despite of the above described available methods, buckling or waviness method of distortion is harder to correct by the conventional methods and remedies. Therefore, in order to overcome the limitations of the existing provisions, there is a need in the art to provide an entirely new method for correction of buckling arising during fabrication and assembly of thin walled sheet metal panels and for reducing the amplitude of the dished mode of distortions occurring in thin plates constrained between stiffeners.
OBJECTS OF THE INVENTION
[008] It is therefore the object of the invention to overcome the aforementioned and other drawbacks in prior art.
[001] The principal objective of the present invention is to provide for a method for correction of buckling distortion arising during fabrication and assembly of thin walled sheet metal panels.
[002] Another object of the present invention is to provide for a method for reducing the amplitude of the dished mode of distortions occurring in thin plates constrained between stiffeners.
[003] Another object of the present invention is to ensure correction of dished mode of distortion with the highest resistance against correction.
[004] These and other objects and advantages of the present subject matter would 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
[005] One or more drawbacks of the conventional technology based on existing correction methods are overcome, and additional advantages are provided through a novel buckling correction method as claimed in the present disclosure. 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.
[006] In an embodiment of the present subject matter, a method for correction of buckling arising during fabrication and assembly of thin walled sheet metal panels, the method comprising marking of correction zones, placing of fixture within the marked zones by means of a stopper plate, pumping of heat energy using gas burners up to a temperature value beyond which no metallurgical changes are observed and cooling up to ambient temperature.
[007] In another embodiment of the present subject matter, the fixture comprises of a rectangular stopper bar being attached to thin walled sheet metal panel.
[008] In yet another embodiment of the present subject matter, the bar is attached with the sheet metal panel along the axis where area moment of inertia is maximum over the centerlines of stiffeners or two stiffened thin walled sheet metal panels.
[009] In yet another embodiment of the present subject matter, the gas burners are high velocity non-oxidizing gas burners.
[0010] In yet another embodiment of the present subject matter, the cooling of the thin walled sheet metal panel is a natural cooling process.
[0011] In yet another embodiment of the present subject matter, the mounting of fixture is dependent upon the direction of distortion.
[0012] In yet another embodiment of the present subject matter, the direction of mounting of fixture is perpendicular to the direction of the thin walled sheet metal panel resulting into a force exerted by the fixture wherein first the distortion increases and then plastic deformation occurs.
[0013] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[0014] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] 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:
[0016] Figure 1 illustrates a schematic view of a distorted thin thin walled stiffened metal sheet.
[0017] Figure 2 illustrates a schematic view of a fixture in accordance with an embodiment of the invention;
[0018] Figure 3 illustrates a schematic view of a mounted fixture on a distorted thin thin walled metal sheet panel in accordance with an embodiment of the invention;
[0019] Figure 4 illustrates a schematic view of a convention for mounting the fixture on the panel in accordance with an embodiment of the invention;
[0020] Figure 5 illustrates a schematic view of process of distortion correction in accordance with an embodiment of the invention;
[0021] 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.
DETAILED DESCRIPTION
[0022] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein are not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
[0023] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0024] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0025] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0026] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0027] 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.
[009] The present subject matter describes a method for correction of buckling arising during fabrication and assembly of thin walled sheet metal panels and for reducing the amplitude of the dished mode of distortions occurring in thin plates constrained between stiffeners.
[0028] The thin sheet metal panels are made of high strength low alloy steel (DMR249A), used for ship building applications. The present method is capable of reducing the distortion drastically and allows simultaneous and parallel fine variations when the correction procedure or process is in progress. The notable advantage of the present method is that it requires lesser crew thus requiring lesser effort and results in close to acceptable flatness levels with lesser noise.
[0029] This method uses thermo-mechanical means of correction. Restriction of thermal expansion induces thermal stresses, which in turn induce yielding of the distorted material where the system is controlled and corrected.
[0030] The given Figure 1 illustrates a schematic view sketch of a stiffened thin plate with buckling mode of distortion. The kind of distortion illustrated in Figure 1 is harder to correct than the kinds of distortions and is even difficult to correct during assembling operations as the overall stiffness escalates.
[0031] Further, Figure 2 illustrates a cross-sectional view of a fixture. With reference to the illustration in Figure 3, Figure 4 and Figure 5, which illustrates a schematic view of a mounted fixture on a distorted thin thin walled metal sheet panel in accordance with an embodiment of the invention and the method respectively, the method for correction of buckling arising during fabrication and assembly of thin walled sheet metal panels comprising of the following steps beginning with marking of correction zones where the correction is to be carried out. The marking of zones is followed by mounting and placing of fixture (200) within the marked zones by means of a stopper plate and pumping of heat energy using gas burners up to a temperature value beneath which no metallurgical changes are observed. This is followed by cooling the fixture (200) and panel set-up to ambient temperature naturally.
[0032] The fixture as shown in Figure 3 to 5 comprises of a rectangular stopper bar being attached to thin walled sheet metal panel (100). The bar is attached with the sheet metal panel (100) along the axis where area moment of inertia is maximum over the centerlines of stiffeners or two stiffened thin walled sheet metal panels. The gas burners used in the method are high velocity non-oxidizing gas burners.
[0033] Further, the mounting of fixture (200) is dependent upon the direction of distortion and the direction of mounting of fixture (200) is perpendicular to the direction of the thin walled sheet metal panel (100) resulting into a force exerted by the fixture (200) wherein first the distortion increases and then plastic deformation occurs.
[0034] The method has certain additional advantages such as the method maybe carried out locally over panels; the method simplifies the effort required in the correction of hard to correct mode of welding distortion (buckling) especially under assembled conditions. The method also uses the advantage of the self-locking property of irreversible machines. The complete process is a noiseless process and is a thermally assisted technique to induce yielding in the distorted panel during correction.
[0035] 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). 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.”
[0036] 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.
[0037] 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.