JP2011005511A - Torch for tig welding and repair welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the volume of a recess for removing defects as small as possible and make the shape of the recess cylindrical, to improve machinability in forming the recess and reduce the welding volume, heat input during welding, and thermal deformation, and further to enable filler metal to be supplied to the center or in the vicinity of the center of a molten pool for improvement of weldability.SOLUTION: In a torch for TIG welding, an electrode 5 and the filler metal 6 are arranged in parallel with the center line of the torch, and are rotatably supported integrally around the center line of the torch, at least the electrode is eccentrically situated with respect to the center line, and the lower end of the electrode is cut obliquely so that the tip end is made to face a wall face.

Description

  The present invention relates to a repair welding method when a torch for TIG welding and a weld have defects.

  When welding is performed, the welded part is inspected by non-destructive inspection methods such as X-ray inspection and ultrasonic inspection. If there is a defect, the peripheral part including the defect is deleted, repair welding is performed, and the defect is Is to be removed.

  As a conventional repair welding method, there is one disclosed in Patent Document 1, and the conventional repair welding method will be described with reference to FIGS. Patent Document 1 shows a repair welding method using a TIG welding method.

  When a defect is found in the welded portion, the required range is deleted so as to include the defective portion, and the boat-shaped concave portion 2 is formed in the base material 1. The size of the recess 2 is such that the torch tip 3 of the welding machine can be inserted and moved. Further, an electrode 5 for generating an arc 4 is provided at a position eccentric from the center of the torch tip 3 so that the base material 1 is melted to the periphery of the recess 2, and a filler metal 6 is provided at the tip of the torch. It is supplied eccentrically with respect to the center of the part 3.

  In the above-described conventional repair welding method, when the defect is at a deep position, the volume of the recess 2 is increased, and the processing time is increased to form the recess 2, and the repair time is increased. Moreover, many filler metals 6 are required, welding time becomes long, and the deformation | transformation by the heat at the time of welding becomes large.

  Furthermore, since the position where the arc 4 is formed and the supply position of the filler metal 6 are deviated and the filler metal 6 cannot be supplied to the center of the molten pool, there are problems such as poor weldability.

JP-A 61-253181

  In view of such circumstances, the present invention reduces the volume of the recess for removing defects as much as possible, and the shape of the recess is cylindrical, thereby improving the processability of forming the recess and reducing the welding volume. The amount of heat input is reduced to reduce thermal deformation, and further, filler metal can be supplied to or near the center of the molten pool to improve weldability.

  In the present invention, in the torch for TIG welding, the electrode and the filler metal are arranged in parallel to the center line of the torch, and the electrode and the filler metal can be rotated integrally around the center line of the torch. At least the electrode is supported at an eccentric position with respect to the center line, and the lower end of the electrode relates to a torch for TIG welding that is cut obliquely so that the tip is directed to the wall surface.

  Further, the present invention relates to a TIG welding torch in which the center of the filler metal is located at a position deviated by a predetermined distance from the long axis of the ellipse formed at the lower end of the electrode.

  According to the present invention, the electrode and the filler metal are held by a cylindrical electrode holder, a shield gas nozzle is provided concentrically with the electrode holder, and a shield is provided between the shield gas nozzle and the electrode holder. The present invention relates to a torch for TIG welding in which gas is ejected.

  In the present invention, the electrode and the filler metal are held by a cylindrical electrode holder, the lower end surface of the electrode holder is formed obliquely, the lower end surface is a mirror surface, and the lower end surface is opposed to the lower end surface. An imaging apparatus is provided, and the present invention relates to a torch for TIG welding in which generation of an arc can be confirmed by the imaging apparatus through the lower end surface.

  In the repair welding method using the torch for TIG welding, the present invention also cuts into a cylindrical shape so as to include a defect, forms a recess, inserts the electrode into the recess, and supplies filler metal. The present invention relates to a repair welding method including a pretreatment step in which at least one rotation is performed while an arc is generated in a state where no arc is generated.

  The present invention also relates to a repair welding method including a step of performing arc welding, forming a molten pool, supplying a filler metal to the molten pool, and performing main welding after the pretreatment step.

  The present invention also relates to a repair welding method for generating an arc so that the molten pool is formed from the center of the recess to the wall surface.

  Furthermore, the present invention relates to a repair welding method in which the arc is raised while rotating and welded continuously in a spiral manner from the lower end to the upper end of the recess.

  According to the present invention, in the torch for TIG welding, the electrode and the filler metal are arranged in parallel with the center line of the torch, and the electrode and the filler metal rotate integrally around the center line of the torch. Supported at least, the electrode is at an eccentric position with respect to the center line, the lower end of the electrode is cut obliquely so that the tip is directed to the wall surface, the molten pool is formed at an eccentric position, The filler metal can be supplied at or near the center of the molten pool, so that welding efficiency is improved and corner welding can be performed without tilting the torch.

  According to the present invention, the center of the filler metal is located at a position away from the long axis of the ellipse formed at the lower end of the electrode by a predetermined distance. The filler metal can be supplied to an appropriate position of the molten pool.

  According to the invention, the electrode and the filler metal are held by a cylindrical electrode holder, and a shield gas nozzle is provided concentrically with the electrode holder, and between the shield gas nozzle and the electrode holder. Since the shielding gas is ejected from the gas, the gas shielding range is small and a good gas shielding is possible.

  According to the invention, the electrode and the filler metal are held by a cylindrical electrode holder, the lower end surface of the electrode holder is formed obliquely, and the lower end surface is a mirror surface and faces the lower end surface. Since the imaging device is provided and the imaging device can check the occurrence of the arc and the welding status through the lower end surface, it is possible to check for the occurrence of arcing or the like, the penetration failure, etc. Can be prevented.

  According to the present invention, in the repair welding method using the torch for TIG welding, a recess is formed by cutting into a cylindrical shape so as to include a defect, and the electrode is inserted into the recess. In this state, a pretreatment process is performed in which at least one rotation is performed while an arc is generated in a state where no arc is supplied, so that the edge portion or the like of the bottom surface of the recess is eliminated, and the occurrence of defects can be prevented.

  In addition, according to the present invention, after the pretreatment step, an arc is generated, a molten pool is formed, a filler metal is supplied to the molten pool, and a main welding process is performed. Can be prevented.

  Further, according to the present invention, since the arc is generated so that the molten pool is formed over the wall surface from the central portion of the concave portion, the arc is rotated so that welding is performed over the entire area of the bottom surface of the concave portion. It becomes possible.

  Furthermore, according to the present invention, since the arc is rotated while being raised, and the overlay welding is continuously performed spirally from the lower end to the upper end of the concave portion, it is possible to perform filling welding in a single process, and welding work It exhibits excellent effects such as improved weldability and improved quality.

It is sectional drawing of the torch front-end | tip part for TIG welding in which this invention is implemented. It is an AA arrow line view of FIG. It is explanatory drawing of the torch front-end | tip part for TIG welding which shows the other Example of this invention. It is sectional drawing which shows a prior art example. It is a BB arrow line view of FIG. It is CC arrow line view of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a tip portion of an example of a torch for TIG welding used in the present invention. In FIG. 1, the same components as those shown in FIG. 4 are denoted by the same reference numerals.

  8 is a cylindrical electrode holder for holding the electrode 5, the electrode 5 is held in parallel with the axial center of the electrode holder 8, and the filler metal 6 is inserted into the electrode from the inside of the electrode holder 8. 5 is supplied in parallel with 5.

  As shown in FIG. 2, the electrode 5 is disposed at a position eccentric from the center of the electrode holder 8. The tip of the electrode 5 is cut obliquely, and the direction of cutting is such that the extension of the cut surface 9 (having an elliptical shape) intersects the filler metal 6 below the electrode 5. The major axis 10 of the surface 9 (ellipse) is inclined at a required angle, for example, 30 °, in a state projected onto a plane with respect to a straight line connecting the center of the electrode 5 and the center of the filler metal 6. The inclination angle is not limited to 30 °, and the long axis 10 may be deviated from the filler metal 6 by a predetermined distance so as not to affect the generation of the arc 4.

  The filler metal 6 is eccentric with respect to the center of the electrode holder 8 and further away from the electrode 5 by a predetermined distance, deviates from the center of the arc 4, and the center of the filler metal 6 is It is set so as to be located in the molten pool 11 formed by the arc 4.

  The electrode holder 8 is housed in a shield gas nozzle 12, and a cylindrical space 13 is formed between the shield gas nozzle 12 and the electrode holder 8, and the space 13 is a shield gas supply (not shown). A shield gas 14 is ejected from the space 13.

  The electrode holder 8 is rotatable about the axis of the electrode holder 8, or the shield gas nozzle 12 and the electrode holder 8 are integrally formed with the shaft of the electrode holder 8. It can be rotated around the heart. The structure is not particularly limited as long as the electrode 5 and the filler metal 6 can rotate integrally.

  The operation will be described below.

  The welded portion is inspected nondestructively, and whether or not there is a defect in the welded portion is inspected. If there is a defect, the cylindrical recess 2 including the defective portion is removed by a drill or an end mill so as to remove the defect. Drill. The diameter of the recess 2 may be a space in which the electrode 5 and the filler metal 6 are inserted and can be rotated.

  A shield gas 14 is ejected from the shield gas nozzle 12 to create an atmosphere of the shield gas 14 in and around the recess 2. Since the shield gas 14 is ejected from between the shield gas nozzle 12 and the electrode holder 8, a good gas shield can be achieved even if the gas shield range is small.

  In a state where the shielding gas 14 is ejected, the electrode 5 is energized to generate an arc 4 between the base material 1 and the electrode 5. The arc 4 is generated in the direction of the shortest distance (low resistance) between the lower end of the electrode 5 and the base material 1, that is, between the lower end of the electrode 5 and the bottom surface of the recess 2. Furthermore, the tip of the electrode 5 is cut obliquely, and as a result, the tip is eccentric to the wall surface side of the recess 2, and the arc 4 is placed on the wall surface side so as to include the tip of the filler metal 6. Occurs eccentrically.

  As a pretreatment for the main welding, the electrode holder 8 is rotated once in a state where the arc 4 is generated and the filler metal 6 is not supplied, and the bottom surface of the recess 2 is melted over the entire surface. As a pretreatment, the arc 4 may be rotated a plurality of times with the arc 4 being generated.

  By melting the bottom surface of the recess 2, the conical depression at the center of the bottom surface of the recess 2 and the edge portion at the periphery of the bottom surface formed when drilling is performed.

  Next, as the main welding, an arc 4 is generated, the base material 1 is melted to form the molten pool 11, and the filler metal 6 is supplied so as to be inserted into the molten pool 11. The filler metal 6 melts from the tip and is built up inside the recess 2. Further, by rotating the electrode holder 8, the entire bottom surface of the recess 2 can be welded.

  In addition, the shape and size of the molten pool 11 to be formed is a shape that extends from the center of the recess 2 to the wall surface, so that the electrode holder 8 is rotated once to make the entire bottom surface of the recess 2 Overfilling is possible.

  Accordingly, by moving the torch tip 3 upward while rotating the electrode holder 8, it is possible to perform overlay welding continuously spirally from the bottom surface to the upper end of the recess 2. The whole hole filling welding can be performed. In addition, since the edge portion is eliminated by executing the pretreatment, it is possible to prevent the occurrence of defects when building up by main welding.

  The arc 4 is generated inside the recess 2, and by supplying the shield gas nozzle 12, the shield gas 14 fills the recess 2 and a good shield state is realized.

  Further, since the arc 4 is biased toward the filler metal 6, the molten pool 11 is formed below the filler metal 6, and the filler metal 6 is inserted near the center of the molten pool 11, The filler metal 6 is efficiently melted and weldability is improved.

  According to the present invention, it is only necessary to form a concave portion of a vertical hole including only a defective portion, cutting is easy, the volume of the concave portion is small, the amount of deposited metal is small, and the amount of heat input is small, so that welding deformation is suppressed. In addition, the welding time can be shortened and work efficiency is improved.

  In the present invention, since the arc 4 is generated inside the recess 2, the arc 4 cannot be observed from the outside.

  FIG. 3 shows another embodiment in which the state of the arc 4 generated inside the recess 2 can be observed.

  The lower end of the electrode holder 8 is cut obliquely, preferably at 45 °, and the lower end surface is mirror-finished, or aluminum or chrome plating is used as the mirror surface 15. An imaging device 16 such as a CCD camera having a horizontal optical axis facing the mirror surface 15 is disposed. In the figure, reference numeral 17 denotes a display device for displaying an image obtained by the imaging device 16.

  The state of the arc 4 is imaged by the imaging device 16 via the mirror surface 15 and further displayed on the display device 17. The image displayed on the display device 17 is an image from directly above the arc 4, and the state of the arc 4 can be reliably confirmed even when the concave portion 2 has a small diameter and is deep.

DESCRIPTION OF SYMBOLS 1 Base material 2 Concave part 3 Torch front-end | tip part 4 Arc 5 Electrode 6 Filler metal 8 Electrode holder 9 Cut surface 10 Long axis 11 Molten pool 12 Shield gas nozzle 13 Space 14 Shield gas 15 Mirror surface 16 Imaging device 17 Display device

Claims (8)

  In the torch for TIG welding, the electrode and the filler metal are arranged in parallel with the center line of the torch, and the electrode and the filler metal are supported so as to be integrally rotatable around the center line of the torch, and at least The TIG welding torch according to claim 1, wherein the electrode is in an eccentric position with respect to the center line, and a lower end of the electrode is cut obliquely so that a tip thereof faces the wall surface.   The torch for TIG welding according to claim 1, wherein the center of the filler metal is at a position deviated by a predetermined distance from the major axis of an ellipse formed at the lower end of the electrode.   The electrode and the filler metal are held by a cylindrical electrode holder, a shield gas nozzle is provided concentrically with the electrode holder, and a shield gas is ejected from between the shield gas nozzle and the electrode holder. The torch for TIG welding according to claim 1.   The electrode and the filler metal are held by a cylindrical electrode holder, the lower end surface of the electrode holder is formed obliquely, the lower end surface is a mirror surface, and an imaging device is provided facing the lower end surface. The torch for TIG welding according to claim 1, wherein generation of an arc can be confirmed by the imaging device through the lower end surface.   In the repair welding method using the torch for TIG welding according to claim 1, a recess is formed by cutting into a cylindrical shape so as to include a defect, the electrode is inserted into the recess, and filler metal is not supplied. A repair welding method comprising a pretreatment step of rotating at least once while generating an arc in a state.   6. The repair welding method according to claim 5, further comprising a step of performing arc welding, forming a molten pool, supplying a filler metal to the molten pool, and performing main welding after the pretreatment step.   The repair welding method according to claim 5 or 6, wherein the arc is generated so that the molten pool is formed over the wall surface from the central portion of the concave portion.   The repair welding method according to claim 7, wherein the arc is raised while rotating, and overlay welding is performed in a spiral manner from the lower end to the upper end of the recess.

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