Claims:We claim:
1. A process for full penetration butt welding of sheet metal plates, the process comprising steps of:
providing a first and a second sheet metal plates (1, 2) arranged to square shaped butt against each other in such a way that a root gap (G) is between the first and second sheet metal plates (1, 2);
forming a through weld between the first and second sheet metal plates (1, 2) in the root gap (G);
forming a weld bead on one side of the first and second sheet metal plates (1, 2) by fusion welding process using a pair of wire electrodes/welding consumable materials converging towards the root gap (G) and extending transversely with respect to a direction of extension of the root gap (G), the weld bead penetrating into the root gap (G) by an amount equal to a fraction of the thickness of the first and second sheet metal plates (1, 2); and
after welding one side of the first and second sheet metal plates (1, 2), gouging on the opposite side of the first and second sheet metal plates (1, 2) using grinding.
2. The process as claimed in claim 1, wherein the thickness of the first and second sheet metal plates (1, 2) is in range of 5 mm to 8 mm, preferably 5 mm.
3. The process as claimed in claim 1, wherein the root gap (G) of the first and second sheet metal plates (1, 2) is in range of 2 mm to 3 mm, preferably 2 mm.
4. The process as claimed in claim 1, wherein the fusion welding process is comprised of Shielded / Manual Metal Arc Welding (SMAW / MMAW), Gas Metal Arc Welding (GMAW) or MIG / MAG welding, preferably SMAW.
5. The process as claimed in claim 1, wherein the first and a second sheet metal plates (1, 2) are arranged to square shaped butt joint by the process of SMAW using 3.15 mm dia.
6. The process as claimed in claim 1, wherein the process further comprising:
forming the weld with or without preheating and or post heating temperature, and
controlling welding voltage, current and travel speed.
7. The process as claimed in claim 1, wherein length of arc is provided with short/medium/long arc, preferably short arc.
8. The process as claimed in claim 1, wherein the preheat temperature at 1200C.
9. The process as claimed in claim 1, wherein the weld is provided through manual, mechanized, semi–automated, robotic and/or automated welding modes.
10. The process as claimed in claim 1, wherein the penetration of weld is made in the voltage of 16 – 18V.
11. The process as claimed in claim 1, wherein the penetration of weld is made in the current of 120 – 125A.
, Description:METAL PLATES
FIELD OF INVENTION:
[001] The present subject matter described herein, relates to a process for butt welding of sheet metal plates without edge preparation, in particular to, a process for butt welding of 5 mm to 8 mm thick sheet metal plates by fusion welding processes (Shielded/Manual Metal Arc Welding (SMAW/MMAW), Gas Metal Arc Welding (GMAW or MIG/MAG) to fabricate components as per ASME or equivalent code for penetration of welds to meet code requirement.
BACKGROUND AND PRIOR ART AND PROBLEM IN PRIOR ART:
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[003] In general, to ensure full penetration welds in 5 to 8 mm thick plates, single V or J type edge preparation will be done prior to weld. At the time of fit up, 2 to 3 mm root gap will be provided between the joining surfaces (Figure 01). After that the weld will be done from single side to ensure full penetration welds to meet the code of construction or acceptance criteria. The welds will be subjected to the non-destructive inspection methods depending upon the acceptance criteria/procedure requirements. The same method cannot be used in all types of requirements as detailed as;
[004] Insufficient availability of parent material width, to make a single V edge preparation we need a minimum of 15 mm width on a single side; J groove weld will not result in full penetration welds always; and ASME and equivalent codes are not permitting any type of penetration related flaws in the weld joints.
[005] In a prior art document as IN 2796 DELNP 2012 A, the prior art discloses butt welding of plate-like work pieces, improper butting of the work pieces partially creates a weak welding area. The work pieces therefore need to be properly butted to each other in a stage prior to the butt welding. A generally-known method uses a pusher to press work pieces from behind towards a stopper (including the case when one of the work pieces, which is fixed in a predetermined position, serves as a stopper) and thus carries out accurate positioning of the work pieces. This method has not many problems if the work pieces are substantially rectangular in shape. On the other hand, if the edges to be butted and the opposite edges in the work pieces extend slantwise relative to a pressing direction or if they curve, pressing the opposite edges with the pusher causes the problem that a component force acts upon a pressing point, which leads to unsuccessful pressing.
[006] To solve the problem of the prior art, the work piece positioning device is provided with an actuator driven reciprocating member under a receiving board on which a work piece is placed. A suction device is supported by the reciprocating member so as to be movable in a vertical direction and also tiltable. The suction device sucks the lower face of the work piece placed on the receiving board.
[007] The reciprocating member is displaced by the actuator and made to press the work piece towards a stopper. According to a positioning device like this one, even if the opposite edges of the work pieces extend at a slant or if they curve, the pressing can be carried out by sucking the lower face of the work piece by using the suction device.
[008] Another prior art document as WO2010046937A1, the prior art discloses a butt welding method for sheet metal plates comprises the following steps: providing a first and a second sheet metal plate edge (Pl, P2) arranged to butt against each other in such a way that a gap (G) is left between them; and forming a through weld between the first and second sheet metal plate edges in the gap. The formation of the through weld comprises the following operations: forming a first weld bead (DW) on one side of the plate edges by continuous wire arc welding using a pair of wire electrodes (21a, 21b) converging towards the gap and extending transversely with respect to the direction of extension of the gap, this first weld bead penetrating into the gap by an amount equal to a fraction of the thickness of the plate edges; and forming a, second weld bead (UW) on the opposite side of the plate edges, using continuous wire arc welding, this second weld bead penetrating into the gap until it meets the first weld bead. The prior art document is related to continuous wire welding only. Though, the patent talks about sheet metal plates which is limited to 3.15 mm thick only and it does not specify about the thickness of the plate.
[009] Another prior art document US 8,097,826 B2, the prior art document discloses a Penetration Enhancing Activating Flux (PEAF) in paste form for autogenous TIG Welding of austenitic stainless steels adapted for ready application with a brush on top weld surface prior to conducting autogenous TIG welding to favor single weld pass, of austenitic stainless steels of AISI 304LN and AISI 316LN varieties with weld bead penetration up to a section thickness of 12 mm. Importantly the (PEAF) paste based TIG Welding of the invention achieves an increase in weld bead penetration of about 300% over the conventional TIG process without activating flux. The PEAF paste based TIG Welding also favors higher productivity and high quality apart from being cost-effective due to less requirement of consumables and controlled heat input to arrest distortion, making it widely acceptable for variety of industrial applications for welding of austenitic stainless steel. This prior art document is related to penetration of enhancing flux.
[0010] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention. However, none of the prior arts process deals with the processing for square shaped butt welding of 5 mm to 8 mm thick plates.
OBJECTS OF THE INVENTION:
[0011] It is therefore the object of the invention to overcome the aforementioned and other drawbacks in prior art processes.
[0012] The principal objective of the present invention is to provide a new process for butt welding of 5 mm to 8 mm thick sheet metal plates without edge preparation for full penetration welds to meet ASME or equivalent code requirement.
[0013] Another object of the present invention is to develop joining method for achieving full penetration welds with square butt edge preparation in 5 mm to 8 mm thick sheet metal plates by fusion welding processes (Shielded / Manual Metal Arc Welding (SMAW/MMAW), Gas Metal Arc Welding (GMAW or MIG/MAG).
[0014] Yet another object of the present invention is directed to improve upon the productivity using the modified process.
[0015] A further object of the present invention is to avoid V or J groove edge preparation.
[0016] 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:
[0017] This summary is provided to introduce concepts related to a process for butt welding of 5 mm to 8 mm thick sheet metal plates without edge preparation for penetration welds to meet ASME code requirement. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0018] The present subject matter relates to a process for butt welding of 5 mm to 8 mm thick sheet metal plates without edge preparation. The process comprising steps of: providing a first and a second sheet metal plates arranged to butt against each other in such a way that a root gap is between the sheet metal plates; forming a weld bead on one side of the sheet metal plates by fusion welding process using a pair of wire electrodes/welding consumable materials converging towards the root gap and extending transversely with respect to a direction of extension of the root gap; after welding one side of the sheet metal plates, gouging on the opposite side of the sheet metal plates using grinding.
[0019] In an aspect, the thickness of the first and second sheet metal plates is in range of 5 mm to 8 mm.
[0020] In an aspect, the root gap of the first and second sheet metal plates is in range of 2 mm to 3 mm.
[0021] In an aspect, the fusion welding process is comprised of Shielded / Manual Metal Arc Welding (SMAW/MMAW), Gas Metal Arc Welding (GMAW) or MIG/MAG welding, preferably SMAW.
[0022] 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
[0023] 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:
[0024] Fig. 1 illustrates a conventional diagram of V and J type joint edge preparations welding;
[0025] Fig. 2 illustrates a square butt edge preparation of a first and a second sheet metal plates, in accordance with an embodiment of the present subject matter; and
[0026] Fig. 3 illustrates a macrographs of the weld without defects/discontinuity, in accordance with an embodiment of the present subject matter.
[0027] 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:
[0028] 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.
[0029] 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.
[0030] The present subject matter relates to a process for butt welding of 5 mm to 8 mm thick sheet metal plates without edge preparation. The process comprising steps of: providing a first and a second sheet metal plates arranged to butt against each other in such a way that a root gap is between the sheet metal plates; forming a weld bead on one side of the sheet metal plates by fusion welding process using a pair of wire electrodes/welding consumable materials converging towards the root gap and extending transversely with respect to a direction of extension of the root gap; after welding one side of the sheet metal plates, gouging on the opposite side of the sheet metal plates using grinding.
[0031] 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 and are included within its spirit and scope. 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.
[0032] 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.
[0033] Fig. 1 illustrates a conventional diagram of V and J type joint edge preparations welding. The penetration welds in 5 mm to 8 mm thick sheet metal plates could be achieved by single V or J type edge preparation and welding will be carried out from one side with sufficient root gap. At the time 2 mm to 3 mm root gap will be provided between the joining surfaces. After welding the single side, the penetration welds to meet the ASME code of construction or acceptance criteria. The welds will be subjected to the non-destructive inspection methods depending upon the acceptance criteria/procedure requirements. The same method cannot be used in all types of requirements.
[0034] Fig. 2 illustrates square butt edge preparation of a first and a second sheet metal plates, in accordance with an embodiment of the present subject matter. In the new innovative process developed, penetration welds were achieved with square butt edge preparation between a first and a second sheet metal plates (1, 2).
[0035] The steps of process, providing the first and second sheet metal plates (1, 2) arranged to square shaped butt against each other in such a way that a root gap (G) is between the first and second sheet metal plates (1, 2); forming a through weld between the first and second sheet metal plates (1, 2) in the root gap (G). A weld bead is formed on one side of the first and second sheet metal plates (1, 2) by fusion welding process using a pair of wire electrodes/welding consumable materials converging towards the root gap (G) and extending transversely with respect to a direction of extension of the root gap (G) such that the weld bead is penetrating into the root gap (G) by an amount equal to a fraction of the thickness of the first and second sheet metal plates (1, 2). After welding one side of the first and second sheet metal plates (1, 2), gouging on the opposite side of the first and second sheet metal plates (1, 2) using grinding.
[0036] Accordingly, the sheet metal plates (1, 2) will be taken up after cleaning the joining surfaces with the root gap (G) of 2 mm to 3 mm, preferably 2 mm. The thickness of the sheet metal plates (1, 2) is in range of 5 mm to 8 mm, preferably 5mm.
[0037] The penetration of weld bead can be done from one side of the sheet metal plates (1, 2) with appropriate parameters such as welding current, voltage, welding speed and etc. On completion of the weld bead from one side of sheet metal plates (1, 2), the process can be reversed and back gouging can be done by grinding or any other similar process.
[0038] Accordingly, in the process for cleaning the sheet metal plates (1, 2) after completion of weld, slag, spatter, etc. In the present invention, Dye/liquid penetrant testing/inspection on the ground areas will be carried out to ensure that no flaw.
[0039] Fig. 3 illustrates macrographs of the weld without defects/discontinuity, in accordance with an embodiment of the present subject matter.
[0040] In accordance with an embodiment of the present subject matter relates to the sheet metal plates (1, 2) taken up and welded with square butt joints by SMAW process using 3.15 mm dia., and specification of the electrodes is E 8018 B2, also 120° C of pre-heat temperature, as shown in Table 1.
[0041] The typical welding parameters can be shown in Table 1.
Description Values
Process SMAW
Type of Current DCEP
Electrode Specification E 8018 B2
Size Dia. 3.15
Voltage 16-18V
Current 120-125A
Preheat Temperature 1200C
Arc Length Short Arc
Joint Type Square Butt
Root Gap 2mm to 3mm

[0042] 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.”
[0043] 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.
[0044] 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.