JP2014124643A - Covering method of steel material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a covering method of a steel material for covering a surface of a steel material easily with high reliability in covering the surface of the steel material with a corrosion-resistant metal plate.SOLUTION: A plurality of covering plates 12 are arranged on a surface of a steel material 10 so that end parts of the adjacent covering plates 12 overlap each other. Resistance seam welding is carried out continuously on a one side part 11a1 intersecting an overlap part 17 of the plurality of covering plates 12 with the overlap part 17 interposed on the steel material 10 while pressurizing by roller electrodes 32a, 32b. Then, a boundary of the one side part 11a1 of the plurality of covering plates 12 is finally welded so as to close a gap generated between the one side part 11a1 and the steel material 10.

Description

  The present invention relates to a steel structure and method for covering steel structures (steel materials) such as bridges, steel towers, water tanks, tanks, piers, and pontoons with metal plates, and in particular, long-term durability by covering the steel materials with corrosion-resistant metal plates. The present invention relates to a steel coating structure and method for improving the strength.

  Steel structures such as bridges, steel towers, aquariums, tanks, piers, and pontoons cause red rust, yellow-brown floating rust, and flow rust due to corrosion, which not only damages the landscape but also reduces the thickness due to corrosion. The strength as a thing is reduced. For this reason, some anticorrosion measures are required. As a corrosion prevention measure for steel structures, a coating method is common, and although heavy anticorrosion coating with improved long-term durability is also known, there is a problem that the service life is limited. There is a problem that maintenance is high because periodic repainting is necessary.

  In order to solve these problems of the painting method, a method of coating the surface of a steel structure with a thin plate of corrosion-resistant metal (corrosion-resistant metal) is known. As the corrosion resistant metal, stainless steel, nickel-base alloy or the like is used. These metals have high corrosion resistance, and theoretically, semi-permanent use is possible by covering the surface of the steel structure with these corrosion-resistant metal plates.

  As a method for fixing a corrosion-resistant metal plate to a steel material, an adhesive, a shell fold (see Patent Document 1), a fitting (see Patent Document 2), mortar, concrete (see Patent Document 3), and welding (Patent Documents 4-6) A method for coating a corrosion-resistant metal plate using a reference is known.

JP 2003-253820 A JP 2005-213810 A JP-A-8-232261 Japanese Patent Laid-Open No. 11-129090 JP-A-11-179552 JP 2007-162117 A

  However, the above-described coating method of the corrosion-resistant metal plate has the following problems.

  Social infrastructures are required to have a service life of 50 to 100 years. In the method of coating a corrosion-resistant metal plate using an adhesive, simply attaching the corrosion-resistant metal plate with an adhesive The bonding strength is low, and the corrosion-resistant metal plate may be dropped.

  In the coating method described in Patent Document 1 (shell folding), although it is easy to construct, moisture may permeate through the gap and the steel material may corrode. Further, when the thickness of the corrosion-resistant metal plate is thin, there is a disadvantage that the tensile strength of the joint portion (folded portion) is weak.

  Further, in the coating methods described in Patent Document 1 (Helse Fold) and Patent Document 2 (Fitting), the joining of the steel material and the corrosion-resistant metal plate is performed only around the corrosion-resistant metal plate. There is a problem that the adhesion strength of the whole plate is low. In addition, the corrosion-resistant metal plates are not welded to each other, but the corrosion-resistant metal plates are folded and sealed with resin, or the metal plates are folded and the resin films on the metal plates are joined together. However, there is a problem that long-term durability is not as high as welding between corrosion-resistant metal plates.

  In the coating method described in Patent Document 3 (mortar, concrete), an organic adhesive, mortar, or concrete is used for joining the steel material and the corrosion-resistant metal plate, and when the periphery of the corrosion-resistant metal plate is not welded, Corrosion factors (for example, chloride ions) that have entered the gap may concentrate, causing crevice corrosion or peeling of the metal plate.

  If the metal plate is welded to the steel material, the above problem of the coating method described in Patent Documents 1-3 can be solved. As a general welding method for welding a metal plate to a steel material, plug welding or strip welding classified as arc welding is used, but in order to perform these welding, a corrosion-resistant metal having a thickness of usually 0.8 mm or more is used. A board is required. When using a corrosion-resistant metal sheet with a thickness less than this, if there is a gap between the steel surface and the corrosion-resistant metal plate, the heat during welding is difficult to dissipate and the corrosion-resistant metal plate is damaged by the heat during welding. There is a problem of (melting away).

  Patent Document 4 (welding) describes a method of welding a corrosion-resistant metal plate having a thickness of 0.8 mm or less to a steel material. However, Patent Document 4 only describes a method of welding a single corrosion-resistant metal plate to a steel material, and a welding method in a case where a plurality of corrosion-resistant metal plates are arranged so that their ends overlap each other is described. Not listed. When covering a large area steel material, it is necessary to arrange | position a some corrosion-resistant metal plate so that each edge part may overlap.

  In Patent Document 5 (welding), a plurality of corrosion-resistant metal plates are arranged so that their end portions overlap each other, and the overlapping end portions of adjacent corrosion-resistant metal plates are continuously subjected to resistance seam welding along the overlapping portion. It is described. However, with only resistance seam welding, there is an unavoidable gap in the overlapped area, and there is a risk that seawater may enter through the gap.

  In Patent Document 6 (welding), as shown in FIG. 6, a plurality of coating materials 2 are arranged on the outer periphery of the steel pipe 1 in the circumferential direction so that the ends of the adjacent coating materials overlap each other, and the adjacent coating materials are arranged. The two overlapping ends are continuously resistance seam welded in the pipe axis direction (continuous resistance seam welds are indicated by reference numeral 3), and the ends of the plurality of covering materials 2 are overlapped in the circumferential direction of the steel pipe 1 In order to avoid this, the resistance seam is discontinuously welded (the discontinuous resistance seam weld is indicated by reference numeral 4), and the strip member 5 for the covering material is wrapped around the steel pipe 1 so as to cover the boundaries of the plurality of covering materials 2. Winding in the direction, one end of the strip member 5 for covering material is TIG welded to the steel pipe 1 (the TIG welded portion is indicated by reference numeral 6), and the other end portion of the strip member 5 for covering material is TIG to the covering member 2 A method for coating a steel pipe to be welded (a TIG weld is indicated by 7) is described.

  According to the coating method described in Patent Document 6, the gap formed between the plurality of coating materials 2 and the steel pipe 1 can be closed by the coating material strip-shaped member 5. Further, the heat generated when TIG welding the band member 5 for covering material to the covering material 2 escapes to the steel pipe 1 through the resistance seam welded portion 4 of the covering material 2. For this reason, it can prevent that the thin coating | covering material 2 melts.

  However, the steel pipe coating method described in Patent Document 6 requires a belt member 5 for a covering material, and thus there is a problem that it takes time and effort for welding.

  The present invention has been made in view of the circumstances as described above, and provides a method for coating a steel material that can be coated with high reliability and simplicity when the surface of the steel material is coated with a corrosion-resistant metal plate. With the goal.

  In order to solve the above problems, according to one aspect of the present invention, a plurality of coating plates are arranged on the surface of a steel material so that ends of adjacent coating plates overlap each other, and the plurality of coatings are applied while pressure is applied by a roller electrode. One side part perpendicular to the overlapping part of the plates is continuously resistance seam welded with the overlapping part sandwiched between the steel materials, and then the boundary of the one side part of the plurality of covering plates to the steel material, the one side part and the one side This is a method of coating a steel material, characterized in that the main welding is performed so as to close a gap generated between the steel material and the steel material.

  According to the present invention, the one side perpendicular to the overlapping portion of the plurality of cover plates is deformed according to the step of the overlapping portion by the pressure of the roller electrode, and the gap between the one side and the steel material is eliminated as much as possible. One side can be resistance seam welded to steel. Heat generated when the boundary of one side of the plurality of covering plates is main-welded to the steel material escapes to the steel material via the resistance seam welded portion on one side. For this reason, it can prevent that a some coating | coated board melts. Since the metal plate which covers the boundary of the one side part of a some coating plate is not required, it becomes a simple coating method.

FIG. 1 is a process diagram of a steel material coating method according to the first embodiment of the present invention (showing a stage in which a coated plate is resistance seam welded to a steel material, FIG. 1A is a plan view, and FIG. 1B is FIG. 1A); (B) is a cross-sectional view taken along the line b-b of FIG. 1, and FIG. FIG. 2A is a plan view, and FIG. 2B is a diagram illustrating a stage of a steel material coating method according to the present embodiment, showing a stage in which a steel plate is main welded and a metal plate is main welded to the steel plate. 2 (a) is a cross-sectional view taken along the line bb of FIG. 2, and FIG. 2 (c) is a cross-sectional view of part c of FIG. Process drawing of the steel material coating method of the present embodiment (plan view showing a stage where a sealing plate is welded to a metal plate) The perspective view which shows the example which coat | covered the steel plate with the coating plate using the coating method of the steel materials of this embodiment Schematic diagram of an indirect resistance seam welder used in the steel material coating method of the present embodiment (FIG. 5 (a) shows an example of welding one coated plate to a steel material, and FIG. 5 (b) shows two sheets. (An example of welding the overlapping parts of the cover plate is shown) Side view of conventional steel pipe covering structure

  Hereinafter, the steel material coating method of the present embodiment will be described in detail. 1 to 3 show process diagrams of a method for coating a steel material according to an embodiment of the present invention. FIG. 1 shows a stage in which coating materials 11a, 11b, and 11c made of a plurality of coating plates 12 are arranged on a steel material 10 in the X-axis direction, and the coating materials 11a, 11b, and 11c are resistance seam welded to the steel material 10, and FIG. The stage which carried out the main welding of the materials 11a and 11c to the steel material 10, and also welded the strip | belt-shaped metal plate 15 to the edge part of coating | covering materials 11a, 11b, and 11c is shown. FIG. 3 shows a stage where the sealing plate 16 is welded to the metal plate 15. Throughout the specification, the same components are denoted by the same reference numerals.

  As shown in FIG. 1, the surface of the steel material 10 of this embodiment is formed in a plane. The width direction of the surface of the steel material 10 is defined as the X-axis direction, and the direction orthogonal to the width direction is defined as the Y-axis direction. The plurality of covering materials 11a, 11b, and 11c are arranged at predetermined intervals in the X-axis direction. The left region of the first covering material 11a, between the first covering material 11a and the second covering material 11b, between the second covering material 11b and the third covering material 11c, and the third covering The region on the right side of the material 11c is an exposed portion of the steel material.

  The covering materials 11a, 11b, and 11c are formed of a plurality of rectangular covering plates 12 arranged so that the ends of the adjacent covering plates 12 overlap each other. The plurality of cover plates 12 are arranged so that ends in the Y-axis direction overlap each other (see the cross-sectional view in FIG. 1B). The overlapping portion 17 extends elongated in the X-axis direction. The plurality of cover plates 12 are arranged so as to overlap only in the Y-axis direction, and are not arranged so as to overlap in the X-axis direction. That is, the adjacent cover plates 12 are arranged so that two sheets overlap each other, but are arranged so as not to overlap three or more sheets. This is because the covering plate 12 is thin, and if three or more sheets are stacked and welded, heat during welding is not easily dissipated and defects are likely to occur.

  The covering plate 12 is made of seawater resistant stainless steel or nickel-base alloy having a pitting index (PI) of 40 or more. Here, PI = Cr [%] + 3.3 × Mo [%] + 16 × N [%]. When tungsten W is included, PI = Cr [%] + 3.3 × (Mo [%] + 0.5 W [%]) + 16 × N [%]. In addition, there exists a problem that corrosion generate | occur | produces in seawater when a coating plate with PI less than 40 is used.

  One side portion 11a1 perpendicular to the overlapping portion 17 of the covering material 11a is resistance seam welded to the steel material 10 in the Y-axis direction. The resistance seam weld 14b is indicated by a broken line. Resistance seam welding is a type of resistance welding (welding where a large current is passed through the welded joint, heated by the resistance heat generated here, and pressure is applied) It is resistance welding performed continuously. In resistance seam welding, welding is continuously performed by applying pressure and energization while rotating a roller electrode. The resistance seam welder will be described later.

  One side portion 11a1 of the covering material 11a is continuously subjected to resistance seam welding with the overlapping portion 17 interposed therebetween. A step is formed in the overlapping portion 17 by the lower cover plate 12, and a gap is provided between the upper cover plate 12 and the steel material 10 by the thickness of the lower cover plate 12. The upper cover plate 12 is bent in a step by applying pressure with a roller electrode of a resistance seam welder so that the gap between the upper cover plate 12 and the steel material 10 is eliminated as much as possible. Resistance seam welding is performed on the steel material 10. As shown in FIG. 1B, a resistance seam welded portion 14 a 1 (nugget) is formed between the upper cover plate 12 and the steel material 10. In the overlapping portion 17, a resistance seam welded portion 14 a 1 (nugget) is also formed between the upper covering plate 12 and the lower covering plate 12.

  The one side portion 11c2 perpendicular to the overlapping portion 17 of the covering material 11c is resistance seam welded to the steel material 10 in the Y-axis direction in the same manner as the one side portion 11a1 of the covering material 11a. The resistance seam weld 14a1 is indicated by a broken line.

  As shown in FIG. 1A, the overlapping portion 17 is continuously resistance seam welded also in the X-axis direction. A resistance seam weld is indicated by 14b. As shown in the cross-sectional view along the Y-axis direction in FIG. 1 (c), between the upper cover plate 12 and the lower cover plate 12 and between the lower cover plate 12 and the steel material 10. A resistance seam weld 14b (nugget) is formed.

  Furthermore, the end portion 11a2 of the first covering material 11a and the end portion 11b1 of the second covering material 11b that face each other are also continuously resistance seam welded in the Y-axis direction. The end portion 11b2 of the second covering material 11b and the end portion 11c1 of the third covering material 11c facing each other are also continuously resistance seam welded in the Y-axis direction. A resistance seam weld is indicated by 14a.

  As shown in FIG. 2 (a), the boundary of one side portion 11a1 perpendicular to the overlapping portion 17 of the covering material 11a is subjected to main welding so as to close the gap between the covering material 11a and the steel material 10 after resistance seam welding. The This welding part is shown by the code | symbol 14d (refer also sectional drawing of FIG.2 (b)). For the main welding, at least one of TIG welding, MIG welding, covered arc welding, and plasma welding is used. A material having higher corrosion resistance than that of the cover plate 12 such as a nickel alloy filler rod (JIS Z 3334 YNiCrMo-3) is used for the melt of the main welding. Since the resistance seam welded portion 14a1 is formed in advance on one side 11a1 of the covering material 11a, the heat generated during the main welding escapes to the steel material 10 via the resistance seam welded portion 14a1. For this reason, it is possible to prevent the thin cover plate 12 from being melted (lost due to melting) by heat generated during the main welding.

  Similar to the one side portion 11a1 of the covering material 11a, the boundary between the overlapping portion 17 of the covering material 11c and the one side portion 11c2 is also subjected to the main welding so as to close the gap between the covering material 11c and the steel material 10 after resistance seam welding. Is done.

  As shown in the cross-sectional view along the Y-axis in FIG. 2C, the overlapping portion 17 is also subjected to main welding so as to close the gap generated in the overlapping portion 17 after resistance seam welding. This welding part is shown with the code | symbol 14c. Only the end portion of the upper cover plate 12 melts and is coupled to the lower cover plate 12. A resistance seam weld 14b is formed between the overlapping cover plates 12, and a resistance seam weld 14b is also formed between the lower cover plate 12 and the steel material 10, so that heat generated during the main welding is formed. Escapes to the steel material 10 through the resistance seam weld 14b. For this reason, it is possible to prevent the thin cover plate 12 from being melted (dissolved and lost) by heat generated during the main welding.

  As shown in FIG. 2A, the end portion 11a2 of the first covering material 11a and the end portion 11b1 of the second covering material 11b that are opposed to each other extend elongated along the end portions of the covering materials 11a and 11b. A strip-shaped metal plate 15 is welded. For welding, at least one of TIG welding, MIG welding, covering arc welding, and plasma welding is used. The metal plate 15 covers the boundary of the first covering material 11a. One end in the width direction (X-axis direction) of the metal plate 15 is welded to the first covering material 11a. One end of the metal plate 15 in the width direction is positioned at the resistance seam weld 14a of the first covering material 11a. Since heat generated when welding the metal plate 15 escapes to the steel material 10 via the resistance seam welded portion 14a, the first covering material 11a can be prevented from being melted. The other end in the width direction of the metal plate 15 is welded to the steel material 10. The strip-shaped metal plate 15 is also main-welded to the end portion 11b2 of the second covering material 11b and the end portion 11c1 of the third covering material 11c that face each other. The metal plate 15 is made of seawater resistant stainless steel or nickel base alloy having a pitting index (PI) of 40 or more. When a metal plate having a PI of less than 40 is used, there is a problem that corrosion occurs in seawater. The plate thickness of the metal plate 15 is set to 0.8 mm or more, preferably 1.2 mm or more. When the plate thickness is less than 0.8 mm, there is a problem that general welding such as TIG welding cannot be performed.

  FIG. 3 shows a stage where the sealing plate 16 is welded to the metal plate 15. The sealing plate 16 covers the exposed portion of the steel material 10 between a pair of adjacent metal plates 15. The sealing plate 16 is welded so as to straddle a pair of adjacent metal plates 15. One end in the width direction of the sealing plate 16 is welded to the metal plate 15, and the other end in the width direction of the sealing plate 16 is welded to the remaining metal plate 15. For welding, at least one of TIG welding, MIG welding, covering arc welding, and plasma welding is used. The sealing plate 16 is made of seawater-resistant stainless steel or nickel-base alloy having a pitting index (PI) of 40 or more. When a metal plate having a PI of less than 40 is used, there is a problem that corrosion occurs in seawater. The thickness of the sealing plate 16 is set to 0.8 mm or more, preferably 1.2 mm or more. When the plate thickness is less than 0.8 mm, there is a problem that general welding such as TIG welding cannot be performed.

  Since the metal plate 15 is set to 0.8 mm or more, heat when the sealing plate 16 is welded to the metal plate 15 escapes to the metal plate 15, and the sealing plate 16 can be welded to the metal plate 15 without any problem. After welding the sealing plate 16 to the metal plate 15, each covering plate 12 may be spot-welded to the steel material 10. Spot welding prevents the covering plate 12 having a large area from wavy.

  By welding the sealing plate 16 to the pair of metal plates 15 as described above, the covering materials 11a, 11b, and 11c arranged in the X-axis direction can be connected, and the steel material 10 having a large area can be connected to the covering material 11a, 11b and 11c can cover the entire surface. Further, the side portions 11a1 and 11c2 in the X-axis direction of the covering materials 11a and 11c are subjected to main welding to the steel material 10 after resistance seam welding. Therefore, seawater can be prevented from entering the covering materials 11a and 11c from the one side portions 11a1 and 11c2 of the covering materials 11a and 11c. In addition, although description was abbreviate | omitted in the said embodiment, the some coating | coated board 12 arranged in the Y-axis direction is wound around the steel material 10, and is connected endlessly.

  The coating method of the above embodiment can be performed in a factory or at an installation site. When manufacturing a big structure, the division body of the steel material 10 is manufactured at a factory, and a division body is combined and welded at the installation site. In this case, the process until the covering materials 11a, 11b, 11c and the metal plate 15 are welded to the divided body of the steel material 10 is performed at the factory, and the process of welding the divided body of the steel material 10 and welding the sealing plate 16 is performed. Performed on site. The sealing plate 16 covers the welded portion between the divided bodies of the steel material 10. The covering materials 11a, 11b, and 11c are arranged at positions away from the welded portion between the divided bodies of the steel material 10 so as not to be affected by heat during welding of the steel materials 10.

  The shape of the steel material 10 that is a structure may be formed in a shape having a flat surface as in the above-described embodiment, or may be formed in a cylindrical shape, such as a steel pipe column that supports a jacket. FIG. 4 shows an example in which the steel pipe 21 is covered with a plurality of covering plates 22. The plurality of cover plates 12 are arranged in the circumferential direction so that the end portions overlap each other. One side portion 22 a perpendicular to the overlapping portion 23 of the plurality of cover plates 22 is subjected to main welding so that the boundary of the one side portion 22 a closes the gap between the one side portion 22 a and the steel pipe 21 after resistance seam welding to the steel material 10. The resistance seam weld is denoted by reference numeral 26 and the main weld is denoted by reference numeral 27. The overlapping portion 23 of the plurality of cover plates 22 is also subjected to main welding after resistance seam welding. The resistance seam weld is indicated by reference numeral 28 and the main weld is indicated by reference numeral 29. Thereby, it becomes possible to block all the gaps generated between the steel pipe 21 and the plurality of covering plates 22. In addition, if it is one side part 22a perpendicular | vertical to the overlap part 17 when expand | deployed on a plane, it will be said that it is the one side part 22a perpendicular | vertical to the overlap part 17. FIG.

  FIG. 5 shows a schematic diagram of an indirect resistance seam welder used in the coating method of the present embodiment. As shown in FIG. 5 (a), the indirect resistance seam welder includes a movable table 31 that is movable in a direction perpendicular to the paper surface, pressurizing devices 31a and 31b supported by the movable table 31, and a pressurizing device. The welding side roller electrode 32a pressurized by 31a and the earth side roller electrode 32b pressurized by the pressurization apparatus 31b are provided. The welding side roller electrode 32a is placed on the covering plate 12, and the ground side roller electrode 32b is placed on the steel material 10. The pressing force of the ground side roller electrode 32b is set larger than the pressing force of the welding side roller electrode 32a.

  When viewed in a cross section including the rotation axis of the roller electrodes 32a and 32b, a tapered portion 34 formed of an inclined surface is provided on the peripheral surface of the roller electrodes 32a and 32b so as to reduce the contact area of the roller electrodes 32a and 32b. . The tapered portions 34 are provided at both ends in the width direction of the peripheral surfaces of the roller electrodes 32a and 32b. By providing the taper portion 34, a flat portion 35 having a width of 3 mm or less is formed on the roller electrodes 32a and 32b. The width of the flat portion 35 is smaller than the width of the roller electrodes 32a and 32b. Also, arc portions can be provided at both ends in the width direction of the circumferential surfaces of the roller electrodes 32a and 32b in place of the taper portion 34, or the entire circumferential surfaces of the roller electrodes 32a and 32b can be formed in the arc portions. it can. The diameters of the roller electrodes 32a and 32b are 100 mm to 300 mm.

  In this way, by forming the flat portion 35 having a width of 3 mm or less on the roller electrodes 32a and 32b, or forming the entire peripheral surface of the roller electrodes 32a and 32b in an arc portion, the contact area of the roller electrodes 32a and 32b is small. Therefore, the pressure applied to the roller electrodes 32a and 32b can be increased. For this reason, it is possible to bend the covering plate 12 along the steps. The plate thickness of the covering plate 12 is 0.3 to 0.8 mm, and the pressure of the welding side roller electrode 32a is set to 2000 to 6000N, preferably 3000 to 5000N. When the thickness of the cover plate 12 is less than 0.3 mm, the cover plate 12 is wrinkled when pressed by the welding side roller electrode 32a, and welding becomes difficult. If the thickness of the covering plate 12 exceeds 0.8 mm, the covering plate 12 cannot be deformed, and the covering plate 12 does not adhere to the steel material 10. Further, if the pressure of the welding side roller electrode 32a is less than 2000 N, the covering plate 12 cannot be deformed, and the covering plate 12 does not adhere to the steel material 10. When the pressing force of the roller electrode 32a exceeds 6000 N, the end of the welding-side roller electrode 32a is deformed, so that the length capable of good indirect resistance seam welding is shortened.

  FIG. 5A shows a front view seen from the moving direction of the roller electrodes 32a and 32b. The outer shape of the roller electrodes 32a and 32b in FIG. 5A is the same as that of the roller electrodes 32a and 32b. Matches the cross-sectional shape.

  The two roller electrodes 32a and 32b are electrically connected via a power source. When a current is applied while pressurizing the welding side roller electrode 32a and the ground side roller electrode 32b, the contact portion between the cover plate 12 having the greatest resistance and the steel material 10 generates heat and a part of the contact portion is melted. The melted portion becomes the resistance seam welded portion 14 a 1 that fixes the covering plate 12 and the steel material 10. When the movable table 31 is moved in the direction orthogonal to the paper surface and the welding side roller electrode 32a and the ground side roller electrode 32b are rolled, a continuous resistance seam welded portion 14a1 elongated in the moving direction is formed.

  FIG. 5B shows an indirect resistance seam welder when the overlapping portion 17 of the covering plate 12 is welded. The welding-side roller electrode 32a rides on the overlapping portion 17 from the top of only one cover plate 12. The ground side roller electrode 32b remains on the surface of the steel material 10. When an electric current is applied while pressurizing the welding side roller electrode 32a and the ground side roller electrode 32b, the upper covering plate 12 resists the steel member 10 with the gap between the upper covering plate 12 and the steel member 10 reduced as much as possible. Seam welding can be performed (see also FIG. 1B).

  The end portions of the plurality of covering plates 12 were overlapped, and one side portion 11 a 1 perpendicular to the overlapping portion 17 of the plurality of covering plates 12 was resistance seam welded to the steel material 10. The material and thickness of the covering plate 12 and the indirect resistance seam welding conditions are as shown in Table 1 below. In all of the examples and comparative examples, steel material 10 having a material: SM490YB and a plate thickness: 32 mm was used.

  In Table 1, SUS312L (UNS S31254) is stainless steel having a composition of 20Cr-18Ni-6Mo-0.8Cu-0.2N, and SUS836L (UNS S32053) is 23Cr-25Ni-5.5Mo-0.2N. Stainless steel having a composition, UNS N08354, is a stainless steel having a composition of 23Cr-35Ni-7.5Mo-0.2N. In all of the examples and comparative examples, steel material 10 having a material: SM490YB and a plate thickness: 32 mm was used. Further, the end portion 30R means that an arc portion having a radius of 30 mm is formed on the entire peripheral surface of the roller electrode.

  After indirect resistance seam welding, the boundary of the one side portion 11a1 of the cover plate 12 was main-welded to the steel material 10. In Examples 1 to 10, the cover plate 12 was not melted by the heat generated during the main welding. In Comparative Example 1, welding was not possible because the cover plate 12 was wrinkled when pressed by the welding side roller electrode 32a. In Comparative Example 2, welding was discontinuous at the stepped portion. In Comparative Example 3, the covering plate 12 was not attached to the steel material 10. In Comparative Example 4, since the end of the welding roller electrode 32a was deformed, good welding could only be performed about 0.5 m.

  In addition, this invention is not limited to being embodied in the said embodiment, It can change into various embodiment in the range which does not change the summary of this invention.

  For example, in the above-described embodiment, one side of the plurality of cover plates is perpendicular to the overlapping portion, but may be crossed even if not perpendicular.

  The shape of the steel material as the structure may be formed in a box shape. When the steel material is box-shaped, the covering plate is bent 90 degrees in accordance with the corners of the steel material.

  You may paint at least one part of several coating plates. For example, the connecting portion between the jacket and the steel pipe column is difficult to cover because it is a connection between the plane and the cylinder. It is desirable to coat such a portion that is difficult to be coated and where corrosion is alleviated without overlapping the corrosion-resistant metal plate so as to overlap the corrosion-resistant metal plate.

DESCRIPTION OF SYMBOLS 10, 21 ... Steel materials 12, 22 ... Cover plate 17, 23 ... Overlapping part 11a1, 22a ... One side part 32a, 32b perpendicular | vertical to the overlap part of a cover plate ... Roller electrode 34 ... Tapered part 35 of roller electrode ... Roller electrode flatness Part

In order to solve the above problems, according to one aspect of the present invention, a plurality of covering plates having a plate thickness of 0.3 to 0.8 mm are arranged on the surface of a steel material so that ends of adjacent covering plates overlap each other, and a roller While applying pressure of 2000 to 6000 N with an electrode, one side that intersects with the overlapping portion of the plurality of covering plates is continuously resistance seam welded to the steel material with the overlapping portion interposed therebetween, and then the plurality of covering plates The steel material covering method is characterized in that main welding is performed on the steel material at a boundary of one side portion so as to close a gap formed between the one side portion and the steel material.

Claims (7)

Arrange a plurality of covering plates on the surface of the steel material so that the ends of the adjacent covering plates overlap each other,
While applying pressure by the roller electrode, one side that intersects the overlapping portion of the plurality of covering plates is continuously resistance seam welded across the overlapping portion to the steel material,
Then, the steel material covering method characterized by carrying out main welding to the steel material at the boundary of the one side portion of the plurality of covering plates so as to close a gap formed between the one side portion and the steel material. The overlapping end portions of the adjacent cover plates, and the lower cover plate and the steel material are continuously resistance seam welded along the overlap portions,
2. The steel material covering method according to claim 1, wherein the welding is performed by welding the overlapping end portions of the adjacent covering plates so as to close a gap formed between them.   The arc surface or the taper portion is provided on the circumferential surface of the roller electrode so as to reduce a contact area of the roller electrode when viewed in a cross section including the rotation axis of the roller electrode. 2. The method for coating a steel material according to 2.   The steel material coating method according to claim 3, wherein a flat portion having a width of 3 mm or less is provided on a peripheral surface of the roller electrode.   The steel material coating method according to claim 3 or 4, wherein a thickness of the covering plate is set to 0.3 to 0.8 mm, and a pressing force of the welding side roller electrode is set to 2000 to 6000 N. .   A covering structure manufactured by the steel covering method according to any one of claims 1 to 5. A resistance seam welder used in the steel coating method according to any one of claims 1 to 5.

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