JP2015093314A - Welding method of rust-proof steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent pores caused by ejection of zinc (Zn) gas from being produced on a weld bead and to reliably prevent rust on the surface of rust-proof steel plate caused by un-attachment of coating material or the peeling of attached coating material from occurring when welding the rust-proof steel plate to be coated by electrodeposition along a predetermined weld line.SOLUTION: A positive electrode 3a and a negative electrode 3b are arranged on both side surface parts of rust-preventive steel plates 1a, 1b as both ends of a weld line 2, electric current is supplied between both electrodes 3a, 3b and a current path 4 through which the electric current flows in the direction of the weld line 2 in a range of a prescribed width including the weld line 2 of the rust-proof steel plates 1a, 1b, is formed. At this time, electric current of a direction opposite to a weld direction X is made to flow through the current path 4 formed in the prescribed range including the weld line 2, and thereby, a magnetic field M around the current path 4 is interlinked with an arc A, force is operated on the arc A, the arc A precedes a weld wire 7 and is moved, and Zn is melted and evaporated with heat of the arc A before a weld bead 8 is formed.

Description

  The present invention relates to a method for welding a rust-proof steel sheet in which a rust-proof steel sheet to be electrodeposited is welded along a predetermined weld line.

Usually, the outer plate surface constituting the body of an automobile is formed by pressing and welding a steel plate into a predetermined shape. For welding in this case, carbon dioxide gas (CO ₂ gas) or argon (Ar) is used. In general, arc welding using MAG (Metal Active Gas) having a ratio of CO ₂ to CO ₂ of 8: 2 as a shielding gas is applied.

However, in the case of arc welding using CO ₂ gas or MAG, slag that is an oxide is generated in the formed weld bead, and this slag is an insulator. There is a problem that the paint does not easily adhere to the top, and even if it adheres, the adhesion is weak and the paint is easily peeled off, which causes rusting on the outer plate surface of the automobile body.

Therefore, as a base metal welding method that requires electrodeposition coating, in order to reduce or prevent the generation of slag by arc welding using CO ₂ gas or MAG, the oxidizing component contained in the shield gas is removed, and Ar gas is used. It is conceivable to apply MIG (Metal Inert Gas) welding with 100% shielding gas. In this case, an oxide that easily emits electrons on the outer plate surface of the steel plate for the body, which is the welding base material, is used. As shown in FIG. 4, the weld bead B formed on the base material W is displaced from a predetermined weld line and greatly inconveniences.

In order to eliminate such inconvenience, conventionally, an oxide-based material, which is a 1: 1 mixture of MnO and SiO _2, is applied along the weld line to the base metal surface to induce an arc in MIG welding, It is considered to prevent meandering of beads (for example, Patent Document 1).

JP-A-2-258174 (see page 2, upper left column, second line to lower left column, first line)

  However, in the method of Patent Document 1 described above, the applied oxide-based material is equivalent to slag, and when the oxide-based material applied to the weld bead remains, the steel plate for body, which is the base material, is electrodeposited. In addition, there is a problem in that the paint does not adhere or the attached paint peels off, and as a result, the occurrence of rust on the outer surface of the automobile body cannot be prevented.

  Further, as a measure for preventing the occurrence of rust on the outer plate surface of an automobile body, it is generally considered that the steel plate for the body is preliminarily galvanized and the galvanized steel plate is arc-welded as described above. In both welding and MAG welding, since molten zinc (Zn) becomes a gas and is ejected from the bead B, as shown in FIG. 5, it is called a pit or a blow hole by the ejection of Zn gas to the bead B. The pores H are generated, and the quality of the bead B is deteriorated.

  The present invention prevents the formation of pores due to the ejection of zinc (Zn) gas in the weld bead when the rust-proof steel sheet to be electrodeposited is welded along a predetermined welding line, An object of the present invention is to reliably prevent the occurrence of rust on the surface of a rust-proof steel sheet due to the peeling of the adhered paint.

  In order to achieve the above-described object, the method for welding a rust-proof steel sheet according to the present invention is a method for welding a rust-proof steel sheet in which a rust-proof steel sheet to be electrodeposited is arc-welded along a predetermined welding line. A current path in which a current flows in the weld line direction is formed in a predetermined range including the weld line of the steel plate, and 100% argon gas is used as a shielding gas, and a current is passed through the current path in a direction opposite to the welding direction. A welding bead is formed by moving the welding wire along the welding line (claim 1).

  Further, an electrode through which a current flows in the weld line direction is disposed on the opposite side of the rust-proof steel plate to the weld surface, and a current is passed through the electrode in a direction opposite to the weld direction, so that the anti-corrosion steel plate is surrounded by the electrode. A welding bead may be formed by moving the welding wire along the welding line using 100% argon gas as a shielding gas while forming a magnetic field capable of containing a rust steel plate. ).

  According to the invention according to claim 1, using 100% argon gas as a shielding gas, while passing a current in a direction opposite to the welding direction in a current path formed in a predetermined range including the weld line of the rust-proof steel plate, In order to move the welding wire along the weld line to form a weld bead, a magnetic field according to the right-handed screw law is formed around the current path. The power of the law of works. At this time, since the current direction of the current path is opposite to the welding direction, the force acting on the arc by the magnetic field generated around the current path is the same as the welding direction, and the welding wire moves in the welding direction. Is preceded by an arc. As a result, due to the heat of the preceding arc, the zinc on the surface of the rust-proof steel plate is melted and evaporated before the weld bead is formed, and a weld bead is formed in the weld line portion from which the zinc has been removed.

  Therefore, when the rust-proof steel sheet to be electrodeposited is welded along a predetermined welding line, it is possible to prevent the formation of pores due to the injection of zinc gas in the weld bead as in the past, and in addition to argon By arc welding using 100% gas as the shielding gas, no slag is generated on the weld bead formed on the rust-proof steel sheet. It is possible to prevent the attached paint from being peeled off, and to reliably prevent the occurrence of rust on the rust-proof steel plate surface.

  Moreover, according to the invention which concerns on Claim 2, a rust-proof steel plate can be included in the circumference | surroundings of an electrode by sending an electric current through the electrode arrange | positioned on the opposite side to the welding surface of a rust-proof steel plate in the direction opposite to a welding direction. While forming the magnetic field, the welding wire is moved along the welding line by using 100% argon gas as a shielding gas to form a welding bead, so that a magnetic field is formed around the electrode according to the right-hand rule. As the magnetic field interlinks with the arc, Fleming's left-hand force acts on the arc, and the current flowing through the electrode at this time is opposite to the welding direction. The acting force is the same as the welding direction. When the welding wire moves in the welding direction, the arc precedes, and the heat of the preceding arc causes the zinc on the surface of the rust-proof steel sheet to form before the weld bead is formed. Melting and evaporated, the weld bead is formed on the weld line portion of zinc was removed. At this time, in order to allow the rust-proof steel sheet to be included in the magnetic field formed around the electrode, the rust-proofing is performed so that the force acting on the arc can be preceded by the movement of the welding wire by the linkage of the magnetic fields. The width dimension perpendicular to the weld line of the steel plate may be made small enough to be included in the magnetic field, and the current value flowing through the electrode may be set.

  Therefore, when the rust-proof steel sheet to be electrodeposited is welded along a predetermined welding line, it is possible to prevent the formation of pores due to the injection of zinc gas in the weld bead as in the past, and in addition to argon By arc welding using 100% gas as the shielding gas, no slag is generated on the weld bead formed on the rust-proof steel sheet. It is possible to prevent the attached paint from being peeled off, and to reliably prevent the occurrence of rust on the rust-proof steel plate surface.

It is a schematic front view of 1st Embodiment of the welding method of the rustproof steel plate which concerns on this invention. It is explanatory drawing of the welding operation in 1st Embodiment. It is the schematic of 2nd Embodiment of the welding method of the rustproof steel plate which concerns on this invention. It is a perspective view of the welding bead which meanders in a prior art example. It is a perspective view of the welding bead in which the pore produced in the conventional example.

<First Embodiment>
A first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

  As shown in FIG. 1 and FIG. 2, when welding a weld line 2 in which two rust-proof steel plates 1 a and 1 b as welding base materials overlap, both side portions of the rust-proof steel plates 1 a and 1 b corresponding to both ends of the weld line 2 The positive electrode 3a and the negative electrode 3b are electrically connected to the rust-proof steel plates 1a and 1b, respectively, and a current (in this case, a direct current) is passed between the positive-electrode 3a and the negative electrode 3b so that the rust-proof steel plates 1a and 1b A current path 4 through which a current flows in the direction of the weld line 2 is formed in a range of a predetermined width including the weld line 2.

  At this time, the positive electrode 3a and the negative electrode 3b are set so that a current opposite to the welding direction X indicated by an arrow in FIGS. 1 and 2 flows in a current path 4 formed in a predetermined range including the welding line 2. Arrange and flow direct current.

  Then, the welding bead 8 is formed by moving the welding wire 7 along the welding line 2 by MIG welding using Ar (argon) gas 100% as the shielding gas 6.

  In this way, when a direct current I is passed between the positive electrode 3a and the negative electrode 3b as shown in FIG. 2, a magnetic field M is formed around the current path 4 of both rust-proof steel plates 1a and 1b according to the right-handed screw law. Since the magnetic field M interlinks with the arc A, a force according to Fleming's left-hand rule acts on the arc A, and the current direction of the current path 4 is opposite to the welding direction X as described above. The force acting on the arc A by the magnetic field M around 4 is the same as that in the welding direction, and the arc A precedes when the welding wire 7 moves in the welding direction.

  As a result, before the weld bead 8 is formed on the weld line 2, the rust-preventing Zn (zinc) plated on the surfaces of the rust-proof steel plates 1a and 1b is melted and evaporated by the heat of the preceding arc A. Then, a predetermined range of Zn including the weld line 2 is removed, and the weld bead 8 is formed in the weld line 2 portion from which the Zn has been removed. No slag is generated in the weld bead 8 by MIG welding using Ar gas 100%.

  Therefore, according to the above-described first embodiment, it becomes possible to control the movement of the arc A in MIG welding using Ar gas 100% as the shielding gas 6, and the rust-proof steel plates 1a and 1b to be electrodeposited are attached. When welding along the weld line 2, it is possible to prevent the formation of pores due to the injection of Zn gas in the weld bead 8 as in the prior art, and MIG welding with Ar gas 100% as the shielding gas 6. Thus, no slag is generated in the weld beads 8 formed on the rust-proof steel plates 1a and 1b, and even if the rust-proof steel plates 1a and 1b are subsequently electrodeposited, the paint does not adhere to the slag or has adhered. The peeling of the paint can be prevented, and the occurrence of rust on the surfaces of the rust-proof steel plates 1a and 1b can be reliably prevented. For example, it is suitable for welding of steel plates for automobile bodies.

Second Embodiment
A second embodiment of the present invention will be described in detail with reference to FIG.

  As shown in FIG. 3, when welding a weld line 2 in which two rust-proof steel plates 1 a and 1 b which are welding base materials are overlapped, a weld line 2 is formed on the opposite surface side of the rust-proof steel plates 1 a and 1 b. A long rod-like electrode 10 parallel to the electrode 10 is arranged, and a direct current in the direction opposite to the welding direction X indicated by an arrow in FIG. The electrode 10 is not limited to a circular cross section, and may be a rectangle.

  As shown in FIG. 3, by passing a direct current I through the electrode 10, a magnetic field M capable of containing the rust-proof steel plates 1 a and 1 b is formed around the electrode 10, and Ar (argon) is used as the shielding gas 6. ) The welding bead 8 is formed by moving the welding wire 7 along the welding line 2 by MIG welding using 100% gas. At this time, a magnetic field M according to the right-handed screw law is formed around the electrode 10, and when this magnetic field M is linked to the arc A, a force according to the Fleming's left-hand law acts on the arc A and flows through the electrode 10. Since the direction of the current is opposite to the welding direction X, the force acting on the arc A by the magnetic field M around the electrode 10 is the same as the welding direction, and when the welding wire 7 moves in the welding direction, the arc Preceded by the heat of the preceding arc A, the Zn on the surface of the rust-proof steel plates 1a and 1b melts and evaporates before the weld bead 8 is formed, and the weld bead 2 is removed from the weld line 2 where the Zn is removed. 8 can be formed.

  By the way, in order to enable inclusion of the rust-proof steel plates 1a and 1b in the magnetic field formed around the electrode 10, the width dimension perpendicular to the weld line 2 of the rust-proof steel plates 1a and 1b is included in the magnetic field M. The current flowing through the electrode 10 may be set to a small value, and a force that precedes the movement of the welding wire 7 due to the linkage of the magnetic field M acts on the arc A.

  Therefore, according to the second embodiment described above, it becomes possible to control the movement of the arc A in MIG welding using 100% Ar gas as the shielding gas 6, and the rust-proof steel plates 1a and 1b to be electrodeposited are attached. When welding along the weld line 2, it is possible to prevent the formation of pores due to the injection of Zn gas in the weld bead 8 as in the prior art, and MIG welding with Ar gas 100% as the shielding gas 6. As a result, no slag is generated in the weld beads 8 formed on the rust-proof steel plates 1a and 1b. Even if the rust-proof steel plate is subsequently electrodeposited, the paint does not adhere to the slag or the attached paint is peeled off. Can be prevented, and the occurrence of rust on the rust-proof steel plate surface can be reliably prevented. In particular, it is suitable for welding the rust-proof steel plates 1a and 1b whose width dimension in the direction orthogonal to the weld line 2 is small.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.

  For example, in the above-described first embodiment, the positive electrode 3a and the negative electrode 3b are disposed on both side surfaces of the rust-proof steel plates 1a and 1b corresponding to both ends of the weld line 2, and are electrically connected to the rust-proof steel plates 1a and 1b, respectively. By passing a current (in this case, a direct current) between the positive electrode 3a and the negative electrode 3b, a current path 4 through which a current flows in the direction of the weld line 2 is formed in a range of a predetermined width including the weld line 2 of the rust-proof steel plates 1a and 1b. In short, it is only necessary to form a current path so that a magnetic field generated by passing a direct current through the current path including the weld line 2 of the rust-proof steel plates 1a and 1b can be linked to the arc.

  Moreover, although both above-described embodiment demonstrated the case where the welding line 2 of the two rust-proof steel plates 1a and 1b was welded, even if it is a case where the welding line of one rust-proof steel plate is arc-welded, this invention. It goes without saying that can be implemented in the same manner.

DESCRIPTION OF SYMBOLS 1a, 1b ... Rust-proof steel plate 2 ... Welding wire 4 ... Current path 6 ... Shielding gas 7 ... Welding wire 8 ... Welding bead 10 ... Electrode M ... Magnetic field A ... Arc

Claims (2)

In the welding method of the rust-proof steel sheet that arc-welds the rust-proof steel sheet to be electrodeposited along a predetermined welding line,
Forming a current path through which a current flows in the weld line direction in a predetermined range including the weld line of the rust-proof steel plate;
100% argon gas is used as a shielding gas, and a welding bead is formed by moving the welding wire along the welding line while flowing a current in the direction opposite to the welding direction in the current path. A method for welding rust-proof steel sheets. In the welding method of the rust-proof steel sheet that arc-welds the rust-proof steel sheet to be electrodeposited along a predetermined welding line,
An electrode through which current flows in the weld line direction is arranged on the opposite side of the weld surface of the rust-proof steel plate,
By forming a magnetic field capable of enclosing the rust-proof steel plate around the electrode by passing a current in the opposite direction to the welding direction to the electrode,
A welding method for a rust-proof steel sheet, wherein a welding bead is formed by using 100% argon gas as a shielding gas and moving the welding wire along the welding line.

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