WO2011099637A1 - Tigアーク溶接用電極及びtigアーク溶接方法 - Google Patents
Tigアーク溶接用電極及びtigアーク溶接方法 Download PDFInfo
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- WO2011099637A1 WO2011099637A1 PCT/JP2011/053304 JP2011053304W WO2011099637A1 WO 2011099637 A1 WO2011099637 A1 WO 2011099637A1 JP 2011053304 W JP2011053304 W JP 2011053304W WO 2011099637 A1 WO2011099637 A1 WO 2011099637A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
- B23K35/0255—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in welding
- B23K35/0261—Rods, electrodes, wires
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/32—Selection of soldering or welding materials proper with the principal constituent melting at more than 1550 degrees C
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/16—Arc welding or cutting making use of shielding gas
- B23K9/167—Arc welding or cutting making use of shielding gas and of a non-consumable electrode
Definitions
- the present invention relates to a TIG arc welding electrode and a TIG arc welding method, and more particularly to a TIG arc welding method for improving a bead shape and a penetration shape by improving a tungsten electrode shape.
- FIG. 10 shows a conceptual diagram of TIG welding (Tungsten Inert Gas Arc Welding).
- TIG welding is performed in an inert gas atmosphere such as argon gas using a tungsten electrode 1 that is a non-consumable electrode when welding a welding object 3 such as an iron plate (hereinafter also referred to as a base material 3).
- This is a welding method in which an arc 4 is generated from the tungsten electrode 1 toward the base material 3 to be welded to form a molten pool 5, where the base material 3 is melted, the weld metal is solidified, etc., as an inert gas.
- High-quality welding is possible because it is performed in an atmosphere and not in an oxidizing atmosphere.
- a welding material is added as necessary.
- the tungsten electrode 1 generally has a diameter of 1 to 10 mm, a cylindrical thorium-containing tungsten electrode (ThO 2 : 1 to 2% by weight), a cerium-containing tungsten electrode (CeO 2 : 1 to 2% by weight), or lanthanum.
- a tungsten electrode (La 2 O 3 : 1 to 2% by weight) is used, and the tip of the tungsten electrode 1 directed toward the base material 3 side is generally conical in order to increase the concentration and directivity of the arc 4. Polished one is used.
- a DC power source having a constant current characteristic is generally used as the welding power source 6, a DC power source having a constant current characteristic is generally used.
- the DC power source 6 and the base material 3 are connected to the positive electrode, and the DC power source 6 and the tungsten electrode 1 are connected to the negative electrode.
- the tip of the tungsten electrode 1 directed toward the base material 3 is polished in a conical shape, and after energization, the tip reaches a high temperature to emit thermoelectrons and generate an arc 4.
- the arc 4 is formed in a conical shape from the tip of the tungsten electrode 1 toward the base material 3, and current flows from the base material 3 toward the tip of the tungsten electrode 1. Lorentz force works.
- the current density in the vicinity of the tip of the tungsten electrode 1 is higher than the current density of the arc-shaped arc 4 in the vicinity of the base 3, and near the base 3 (high pressure) near the tip of the tungsten electrode 1 (high pressure).
- a pressure difference is generated toward the low pressure, and a plasma air flow 7 is generated.
- the temperature in the vicinity of the electrode tip reaches 17000K and is in a plasma state.
- the plasma airflow 7 collides with the molten pool 5 in which the base material 3 is melted by high heat, and an arc pressure (arc pressure) is generated in a direction in which the molten pool 5 is pressed.
- TIG welding is of high quality but has a drawback of low efficiency.
- methods for improving the efficiency have been proposed.
- the welding current is increased to 200 A or higher and the welding speed is increased to 150 mm / min or higher, the plasma air flow 7 becomes higher, the arc pressure increases, the central recess of the molten pool 5 becomes larger, and the molten pool bottom is exposed.
- a defective weld bead such as a humping bead that solidifies as it is or an undercut bead that remains as a groove is dug along the toe in the width direction of the molten pool.
- the current density near the tip of the tungsten electrode 1 is lowered, and the pressure difference between the tip of the tungsten electrode 1 and the base material 3 is reduced to reduce the plasma airflow. 7 may be reduced to reduce the arc pressure, and various countermeasures have been conventionally considered.
- a dent at the center of the molten pool 5 remains or cracks occur, so that a processing method at the end of welding, generally referred to as downslope and crater processing, is used.
- the welding is completed by gradually reducing the current and reducing the molten pool 5 to a small size.
- the arc length (the distance from the tip of the tungsten electrode 1 to the base material 3 in FIG. 10) is extremely shortened to about 1 mm.
- the tungsten electrode 1 is shaken at a high speed of 10 Hz or more at a right angle with respect to the welding progress direction, or the arc 4 is deflected by applying a magnetic field to the arc 4 so that the welding progress direction.
- these methods require a mechanism for swinging the tungsten electrode 1 at a high speed and a mechanism for deflecting and swinging the arc 4 with a magnetic field.
- the control for operating the welding torch part in which the metal is stored becomes complicated, the weight of the welding machine increases, making it difficult to apply to general-purpose robots that perform high-speed welding, and the welding torch part becomes large and assembled products There is a problem that the welded part cannot be applied due to interference or the like.
- FIG. 8 shows a tungsten electrode 1 in which the tip used for TIG welding is processed into a conical shape.
- the upper limit of the cone angle ⁇ is about 120 °, and if it is larger than that, the arc 4 shown in FIG. 10 may be generated from a specific conical surface and becomes unstable. In particular, the arc 4 tends to be generated from the conical surface at a small current indispensable for the processing method at the end of welding, and welding becomes unstable.
- the cause of the occurrence of the biased arc 4 in a small current region has a correlation between the magnitude of the current and the area where the arc 4 is generated at the tip of the tungsten electrode 1, and the arc 4 has the tungsten electrode 1 and the base material 3.
- the area where the arc 4 is generated can be small in a small current region, the distance between the shaft portion of the tip of the tungsten electrode 1 and the base material 3, the portion other than the shaft portion, and the base material 3 If the difference from the distance between the tungsten electrode 1 and the base material 3 becomes other than the axial part due to the influence of the deposits on the tip of the tungsten electrode 1, the arc 4 May occur, causing the arc 4 to be biased.
- FIG. 9 shows a truncated conical electrode 1 for processing the tip of the tungsten electrode 1 into a flat surface.
- This is a method of increasing the arc diameter at the tip of the tungsten electrode 1 by increasing the truncated diameter W2.
- the arc 4 is generated in a biased manner on a part of the truncated surface as described above.
- increasing the truncated diameter W2 may cause the arc 4 to be biased on a part of the truncated surface, which makes the arc 4 unstable.
- the arc 4 is generated with a deviation from the axis of the tungsten electrode 1, so that the penetration shape tends to be different on the left and right sides of the bead, or becomes shallower. A weld cannot be obtained.
- Patent Document 1 discloses a method using a tungsten electrode having a hole at the tip of the tungsten electrode. Specifically, as shown in Table 1 of Patent Document 1, a truncated head is provided at the tip of a tungsten electrode having a diameter of 8 mm, and a hole having a diameter of 3, 4 or 5 mm and a depth of 5 mm is provided at the center. ing. In this method, as described above, arcs are biased and generated in a small current region, so that the penetration shape tends to be different between the left and right sides of the bead or shallow, and a sound weld cannot be obtained. Japanese Patent Laid-Open No.
- Patent Document 2 introduces a method of generating an arc by using a hollow tungsten electrode and separately flowing an inert gas from the outside of the tungsten electrode and from the hollow portion. .
- an arc is generated from the tip of the doughnut-shaped tungsten electrode outside the hollow portion, but the arc is likely to be generated unevenly in a small current region as in the method described in Patent Document 1.
- the diameter of the tungsten electrode is increased due to the structure in which the inert gas flows from the hollow portion, the shortest distance from the tip portion to the base material is distributed in the circumferential direction. For this reason, arcs tend to be generated unevenly. For this reason, the penetration shape tends to be different between the left and right sides of the bead or becomes shallow, and a sound weld cannot be obtained.
- Patent Document 3 discloses that an arc is formed by forming the tip of the tungsten electrode into a tapered wedge shape and forming an indented groove at the width center of the tip. Is generated from both sides of the groove to reduce the concentration of the arc, and a magnetic probe is used to swing the arc in a direction perpendicular to the weld line to obtain a wide and shallow weld zone.
- FIG. 2 of Patent Document 3 discloses the shape of the tip of the tungsten electrode.
- FIG. 3 of Patent Document 3 discloses that the outer diameter of the tungsten electrode is 3.2 mm, and it is estimated from FIG. 2 of Patent Document 3 that the center-to-center distance is 1.6 mm. . This distance is too large as the slit width of the electrode tip used in the present invention described later, and is not an appropriate distance. Also, with this method, there is a difference in the penetration shape depending on the wedge-shaped attachment direction.
- the direction of the wedge shape at the tip of the tungsten electrode attached to the welding torch is made constant. It is not suitable for an automatic welding apparatus such as a robot because it needs to be taught. Further, when the electrodes are automatically exchanged, it is necessary to make the wedge-shaped attachment direction of the tip of the tungsten electrode attached to the welding torch constant, and this operation is also difficult. Furthermore, there is a problem that the use of a magnetic probe leads to an increase in the size of the welding machine.
- Patent Document 4 a slit is formed in the axial direction from the tip of a tungsten electrode to form two or more sharp tips (tips), and the two or more sharp tips.
- a method of obtaining a wide bead without oscillating by generating an arc in each specific direction from a plurality of points is disclosed.
- Patent Document 4 there is no description of the outer diameter or slit width of tungsten, but the tip is formed outside the outer diameter by illustration, and a plurality of arcs are formed from the respective tip toward the base material. Yes.
- the distance between the tips is almost equal to the outer diameter of tungsten, and this distance is too far as the slit width of the electrode tip used in the present invention described later, and is not an appropriate distance. Also, with this method, the strength of the arc from each tip is unevenly generated, particularly in a small current range, so the penetration shape tends to be different on the left and right sides of the bead, or shallow, and a sound weld can be obtained. Absent.
- Japanese Utility Model Laid-Open No. 4-98390 Japanese Utility Model Laid-Open No. 4-98390 (GB Publication 2250900A, US Pat. No.
- Patent Document 5 has a tungsten electrode formed of two separate parts, each of which has a tapered tip.
- a technique is disclosed in which sparks are induced while suppressing vapor deposition of metal ions by fixing and using objects facing each other with a gap therebetween.
- the object of the invention described in Patent Document 5 relates to the improvement of spark induction essential for a good arc start, and is different from the object of the present invention.
- Patent Document 5 does not describe the outer diameter of the tungsten electrode or the width of the gap portion, but paragraph [0006] of the specification describes the spark intended by the technique described in Patent Document 5 even when the slit width is extremely small.
- Patent Document 6 The object of the invention described in Patent Document 6 is to improve the problem of being unable to weld due to metal deposition from the molten pool, and is similar to the technique described in Patent Document 5 regarding improvement of spark induction essential for good arc start. This is an object and is different from the object of the present invention.
- Patent Document 6 there is a description that the diameter of the tungsten electrode is 4 mm and the diameter of the truncated portion at the tip is 1 mm, but there is no description about the width of the gap.
- the width of the gap is estimated to be 0.5 mm or less.
- Patent Document 5 describes that the slit width is extremely small, and the invention described in Patent Document 6 uses a truncated cone shape in which the cone tip of the tungsten electrode is flattened. Since it is 1 mm, the width of the slit is estimated to be 0.5 mm or less. In the case of such an interval between the tapered portions of the electrode tip (Patent Document 5) and a gap at the electrode tip (Patent Document 6), the arc spread near the tungsten electrode tip is small and the current density remains high.
- JP-A-52-144345 Japanese Unexamined Patent Publication No. 61-3683 JP 60-49891 A JP-A-61-273295 Japanese Utility Model Publication No. 4-98390 (GB Publication 2250900A, US Pat. No. 5,173,581) European Patent No. 67062 (US Pat. No. 4,471,208)
- the object of the present invention is to reduce the current density in the vicinity of the tip of the tungsten electrode while keeping the arc concentration in a large current region, and to reduce the pressure difference between the tip of the tungsten electrode and the base material, thereby reducing the plasma airflow.
- the object of the present invention is to provide a slit in the center direction of the electrode width (diameter) from the end face of the tungsten electrode, and to form the slit-processed tungsten electrode end face in a conical shape expanding in the axial direction from the vicinity of the center of the end face.
- it is polished into a polygonal pyramid, thereby forming at least two or more tips with a slit in the vicinity of the center of the electrode, and arcs generated from a plurality of adjacent tips obtained are attracted by Lorentz force, and one arc is drawn. This is achieved by the TIG welding tungsten electrode to be formed and the TIG welding method.
- the tip of the tungsten electrode is polished in a conical shape or a polygonal pyramid shape, and a slit having a width of 0.75 mm or more and 1.5 mm or less along the central axis of the tip is formed from the tip of the electrode.
- An electrode for TIG arc welding characterized by being provided along the axial direction on the base side.
- the invention according to claim 2 is the electrode for TIG arc welding according to claim 1, characterized in that the shape of the slit provided at the tip of the tungsten electrode is a single character or a cross shape when viewed from the tip.
- the invention according to claim 3 is the electrode for TIG arc welding according to claim 1, wherein the tip end angle of the tip of the tungsten electrode is 30 ° or more and 100 ° or less.
- the tip of the tungsten electrode is polished in a conical shape or a polygonal pyramid shape, and a constant slit having a width of 0.75 mm or more and 1.5 mm or less is formed along the central axis of the tip.
- TIG characterized by being provided along the axial direction from the tip to the base side, forming at least two tips with a slit in the vicinity of the center of the electrode, and forming one arc from a plurality of obtained close tips
- This is an arc welding method.
- the invention according to claim 5 is the TIG arc welding method according to claim 4, wherein welding is performed with the tungsten electrode attached to the welding direction in the same direction or in a direction other than the same direction. is there.
- the slit having a width of 0.75 mm or more and 1.5 mm or less along the central axis of the tip portion of the tungsten electrode is formed in the axial direction from the tip of the electrode to the base side. Since the arcs generated from the tip ends of the two or more electrodes have the same direction of current flow, they are attracted to each other by Lorentz force to form one arc and have the following effects. (1) Even with a large current of 200 A or more, welding is possible without generating irregular beads such as humping beads and undercut beads, and the distance between two or more tips close to the tungsten electrode that corresponds to the width of the slit is set appropriately.
- the current density near the tip of the tungsten electrode is lowered while maintaining the arc concentration, so that the difference between the pressure near the tip of the electrode and the pressure near the base metal is reduced, and the flow velocity of the plasma airflow is reduced.
- the arc pressure that slows down and pushes the molten pool is reduced, and a good weld can be obtained.
- a single arc is formed by setting the distance between two or more adjacent tips of the tungsten electrode to be 0.75 mm or more and 1.5 mm or less, so that fluctuation due to arc bias occurs. No bead meandering occurs.
- the shape of the slit provided at the tip of the tungsten electrode is a single letter or a cross when viewed from the tip side. Can be easily processed with a cutter.
- welding with no directivity can be performed even in the case of a single character, but when the diameter of the tungsten electrode exceeds 5.0 mm, welding with less directivity in the case of a single character than in the case of a single character is possible.
- the invention described in claim 3 has a difference in arc pressure when the tip angle of the conical or polygonal pyramid tip of the tungsten electrode is 30 ° or more and 100 ° or less.
- the bead depth / width ratio is almost the same between 0.17 and 0.20, which deepens the penetration of the beat.
- the polishing angle of the electrode tip exceeds 100 °, the arc generated from each tip spreads in the slit direction, so that the bead depth / width ratio is 0.17 to 0 when the slit direction is the welding progress direction. ..20 and smaller than 0.17 to 0.20 in the case of a right angle in the welding direction, a difference between the slit installation direction and the penetration shape occurs.
- the polishing angle is less than 30 °, the strength is insufficient and polishing is difficult, and the yield is 50% or less.
- the width / depth ratio of the bead is made substantially constant even if the direction of the slit of the tungsten electrode is changed with respect to the welding progress direction. As compared with a truncated electrode or a hollow electrode, the bead bottom is deeply melted, and defects such as poor fusion at the bead bottom do not occur.
- FIG. 1 (a) shows a front view (FIG. 1 (a)), a side view (FIG. 1 (b)), and a bottom view (FIG. 1 (c)) showing the shape of the tungsten electrode for the first embodiment of the present invention.
- FIG.1 (a) shows the front view (FIG.1 (a)), side view (FIG.1 (b)), and bottom view (FIG.1 (c)) which show the shape of the tungsten electrode for the 2nd Example of this invention.
- FIG. 3A shows an arc pressure distribution diagram measured using the tungsten electrode of FIG. 1,
- FIG. 3A shows a conical electrode having an electrode tip angle of 60 °, and
- FIG. 3B shows a slit width of 1 mm in the welding direction. When the slit is installed, FIG.
- FIG. 6A is a photograph of an arc using a tungsten electrode of the first example
- FIG. 6A is an arc with an electrode polished in a conical shape
- FIG. 6B is an arc with a slit electrode viewed from the slit direction
- FIG. 6A is an arc using a tungsten electrode of the first example
- FIG. 6A is an arc with an electrode polished in a conical shape
- FIG. 6B is an arc with a slit electrode viewed from the slit direction
- FIG. 6C shows an arc viewed from a direction perpendicular to the slit with a slit electrode. It is a slit width when performing arc welding using the tungsten electrode for a 1st example, a numerical value of a tip angle and a slit direction, a bead appearance photograph, and a cross-sectional macro model. They are a front view (Drawing 8 (a)) and a bottom view (Drawing 8 (b)) of a tungsten electrode where the tip of conventional technology is conical. A front view (FIG. 9A) and a bottom view (FIG. 9B) of a tungsten electrode having a truncated conical tip in the prior art are shown. It is a figure explaining the arc generation condition of an electrode.
- FIG. 1 to 7 show an electrode shape, arc pressure distribution diagram, measured value of arc pressure with respect to the width of the slit 2, and electrode when arc welding is performed using the tungsten electrode 1 in the first embodiment of the present invention.
- the measured value of the arc pressure with respect to the cone angle of the tip, the photograph of the arc, the appearance of the bead and the cross-sectional macro photograph are shown.
- Non-Patent Document 1 Hiraoka, Okada, Inagaki: "Effect of electrode shape on maximum arc pressure in TIG arc", JSME Journal, Vol. 3, No. 2, PP. 246-252 (1985) ) Measure using the method described in).
- a water-cooled copper plate was measured by a method in which a through hole having a diameter of 1 mm was provided, a pressure gauge was installed at the outlet of the through hole, and an arc was passed through the through hole.
- FIG. 3A shows measurement results of arc pressure (kPa) with a diameter of 3.2 mm, a tungsten electrode 1 containing 2% lanthanum, a tip polishing angle of 60 °, a welding current of 300 A, and an arc length of 3 mm.
- the arc 4 (Fig. 10) has an arc pressure distribution of 4 mm on one side and a maximum arc pressure of 2.8 kPa on both sides from the center, and the arc pressure is concentrated and large at the arc center.
- the vertical axis represents the arc pressure (kPa)
- the horizontal axis represents the length in the bead width direction.
- Table 1 shows the results of a bead placement test without adding a welding material such as a wire to a mild steel sheet
- FIG. 7 shows a typical bead appearance and cross-sectional macrostructure.
- the welding conditions are a welding current of 300 A, an arc length of 3 mm, and a welding speed of 200 mm / min. With no slit and with a slit width of 0.5 mm, a humping bead was generated under all conditions, and with a slit width of 0.75 mm, a humping bead was generated in the start part under some conditions, but after that, it became a normal bead. .
- the slit width is preferably 1.5 mm or less.
- the case where the direction of the slit 2 is the welding progress direction and the case where the direction of the welding progress direction is perpendicular are compared.
- the direction of the slit 2 in FIG. 3B is the welding progress direction
- the arc pressure was not affected by the direction of the slit 2 and was almost the same distribution.
- the penetration shape of the electrode 1 with a slit is a penetration shape suitable for the multilayer pile welding which piles up a bead from having the uniform penetration depth of the breadth spread.
- the polishing angle of the tip of the electrode 1 is 30 to 60 ° when the slit width is 0.75 and 1.0 mm, there is almost no difference in arc pressure, and the penetration shape has a bead depth / width ratio of 0.17 to 0. .20 is almost the same.
- the bead depth / width ratio is 0.17 to 0 when the direction of the slit 2 is the welding progress direction. Is smaller than 20 and is greater than 0.17 to 0.20 in the case of a right angle in the welding direction, resulting in a difference between the installation direction of the slit 2 and the penetration shape.
- the conical tip angle of the tip of the tungsten electrode 1 is preferably 30 ° or more and 100 ° or less.
- the arc spread on the base metal side is comparable between the electrode polished in the conical shape in FIG. 6 (a) and the slit electrode 1 in FIG. 6 (b) or FIG. 6 (c).
- the width of the arc on the tungsten electrode side is wider in the slit electrode 1 shown in FIGS. 6 (b) and 6 (c) than the electrode polished in a conical shape in FIG. 6 (a).
- the current density and pressure are lower than the conically polished electrode shown in FIG.
- the pressure difference between the vicinity of the electrode and the base material side becomes smaller than that of the electrode polished in a conical shape shown in FIG.
- the speed of the airflow is also reduced, and the arc pressure generated by the airflow is also lower than that of the electrode 1 polished in a conical shape.
- Table 2 shows the results of the bead placement test using the truncated electrode and the hollow electrode in the same manner as the slit electrode 1 described above.
- the test conditions used were the above conditions.
- the truncated electrode and the hollow electrode have a bead width of about 10 mm and are equivalent to the slit electrode 1, but the penetration depth is shallow and the bead depth / width ratio is 0.11 to 0.15, which is 0 of the slit electrode 1. It was found to be shallower than 17 to 0.20. In thick plate welding, it is necessary to sufficiently melt the bead overlap and base material so that defects such as poor fusion do not occur.
- the slit electrode 1 is used rather than a truncated electrode or a hollow electrode.
- the slit electrode 1 of this welding method is suitable because the penetration of the beads can be deepened.
- FIG. 2 shows the shape of a slitted tungsten electrode 1 according to a second embodiment of the present invention.
- FIG. 2 (a) is a front view
- FIG. 2 (b) is a side view
- FIG. 2 (c) is a bottom view. .
- a plurality of slits 2 may be inserted at the tip of the electrode 1 to increase the number of tips to 3 or more (FIG. 2 shows a cross-shaped slit). Even if the slit is a single character, welding without sufficient direction can be performed, but when the diameter of the tungsten electrode is larger than 5.0 mm, there is no more directivity in the case of ten characters than in the case of one character. Welding is possible.
- the electrode 1 of the present invention By using the electrode 1 of the present invention, welding is possible without generating irregular beads even at a large current of 200 A or more, such as 300 A, and in combination with hot wire TIG welding, the efficiency is approximately doubled (from 20 g / min). 40 g / min), TIG arc welding can be promoted for welding.
- Tungsten electrode (cylindrical) 2 Slit 3 Base material 4 Arc 5 Weld pool 6 Welding power source 7 Plasma airflow
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Abstract
Description
前記直流電源6と母材3とは正極、前記直流電源6とタングステン電極1とは負極に接続される。タングステン電極1の母材3側に向けられる先端部は円錐状に研摩され、通電後に先端部が高温に達して熱電子が放出されアーク4が発生する。アーク4はタングステン電極1の先端部から母材3に向けて円錐状に形成され、電流が母材3よりタングステン電極1の先端に向けて流れるためタングステン電極1の軸の外周から軸に向かってローレンツ力が働く。このため、タングステン電極1の先端部近傍での電流密度は母材3の近傍の末広がり状のアーク4部の電流密度より高くなり、タングステン電極1の先端部近傍(高圧)より母材3近傍(低圧)に向けて圧力差が生じてプラズマ気流7が発生する。このとき電極先端近傍の温度は17000Kにも達してプラズマ状態になっている。前記プラズマ気流7が、母材3が高熱により溶融した溶融池5にぶつかり、溶融池5を押圧する方向にアーク圧力(アークプレッシャー)が発生する。
図8にTIG溶接に使用する先端部を円錐状に加工したタングステン電極1を示す。この先端の円錐角度θを増大する方法がある。この方法はタングステン電極1の先端部近傍のアーク径を広げることにより、タングステン電極1の先端部近傍での電流密度と母材3の近傍の末広がり状のアーク4部の電流密度との大きさの差を小さくすることにより、タングステン電極1の先端部近傍と母材3近傍との圧力差を小さくしてアーク圧力を低下する効果がある。しかしながら、前記円錐角度θは約120°が上限であり、それ以上大きくすると図10に示すアーク4が特定の円錐面より発生することがあり、不安定になる。特に溶接終了時における処理方法に不可欠な小電流においてアーク4が円錐面から発生しやすく溶接が不安定になる。
特に小電流域でアーク4が偏って発生する原因として、電流の大きさとタングステン電極1の先端部でのアーク4の発生位置の面積に相関があり、アーク4はタングステン電極1と母材3との最短距離で発生するが、小電流域ではアーク4の発生位置の面積が小さくて済むため、タングステン電極1の先端部の軸部と母材3との距離と軸部以外と母材3との距離との差が微小の場合、又はタングステン電極1の先端部への付着物などの影響でタングステン電極1と母材3との最短距離が軸部以外になった場合にはそこからアーク4が発生することがあり、アーク4が偏って発生する原因になることが考えられる。
次に図9にタングステン電極1の先端部を平面に加工する切頭円錐電極1を示す。この切頭径W2を増大することによりタングステン電極1の先端部のアーク径を拡げる方法である。この方法では小電流域の場合には前記と同様に、切頭面の一部にアーク4が偏って発生する。また、切頭径W2を増大することでも切頭面の一部にアーク4が偏って発生することがあり、アーク4が不安定になる。
前記の2つの方法では特に小電流において溶接できたとしても、アーク4がタングステン電極1の軸から偏って発生するため溶け込み形状がビードの左右で違ったり、浅くなったりする傾向があり、健全な溶接部が得られない。
また、特開昭61−3683号公報(特許文献2)には中空式タングステン電極を用いてタングステン電極の外と中空部から別々に不活性ガスを流してアークを発生させる方法が紹介されている。この方法では中空部の外側にあるドーナツ状のタングステン電極先端部からアークが発生するが、前記特許文献1記載の方法と同様に小電流域でアークが偏って発生しやすい。本従来技術においても中空部から不活性ガスを流す構造のためタングステン電極の直径が大きくなるため、先端部から母材までの最短距離が円周方向に分布する。このため、アークが偏って発生しやすく、このため、溶け込み形状がビードの左右で違ったり、浅くなる傾向があり、健全な溶接部が得られない。
また、特許文献3の図3にはタングステン電極として外径が3.2mmであることが開示されており、特許文献3の図2から頂部の中心間距離は1.6mmであると推定される。この距離は後述する本発明で用いる電極先端のスリット幅としては大き過ぎ、適切な距離ではない。また、この方法では、くさび形状の取付け方向により溶け込み形状の違いが発生し、特にロボット等の自動溶接装置を使用する場合には溶接トーチに取付けたタングステン電極先端部のくさび形状の方向を一定にするティーチングを行う必要があり、その作業にはかなりの困難を要するためロボット等の自動溶接装置には向いていない。また電極の自動交換を行う場合に溶接トーチに取付けるタングステン電極先端部のくさび形状の取付け方向を一定にする必要があり、この作業においても困難性を要する。さらに、磁気プローブを用いるために溶接機の大型化につながるという問題があった。
また、タングステン電極1の形状として実開平4−98390号(GB公開2250900A、US特許5173581)(特許文献5)には、2つの別個の部分からなるタングステン電極をそれぞれの先端部を先細に加工したものを、間隙を空けて互いに対向させて固定し使用することにより金属イオンの蒸着を抑制しながら火花誘導を行う技術が開示されている。特許文献5記載の発明の目的は良好なアークスタートに不可欠な火花誘導の改善に関するもので、本発明の目的とは異なる。特許文献5にはタングステン電極の外径や間隙部の幅の記載はないが、明細書の段落[0006]には、スリットの幅が極めて小さい場合でも特許文献5記載の技術が目的とする火花誘導が良好に行えること、実質的に対向して接触させて互いに固定されても良いことが記載されており、スリット幅は0に近いことが推定される。この0に近いスリット幅は本発明に用いるスリット幅としては小さ過ぎて適切な距離ではない。
また、特許文献5記載の従来技術においては、アークを点弧するためにタングステン電極と母材間に高周波を印加するが、通常の円錐に研磨したタングステン電極では電極先端に金属イオンが蒸着し、アークスタート時の熱電子の放出が困難になりアークスタート性が悪くなる。タングステン電極先端に狭い空隙、スリットを設けると空隙、スリット内には金属イオンの蒸着がしにくいため、円錐面に金属イオンが蒸着しても空隙、スリット内より電子の放出が行われるためにアークスタート性が落ちない。この場合にタングステン電極先端部に設ける空隙、スリットは金属蒸気が入り込まないように狭く設定する必要がある。
次に、欧州特許第67062号(US特許4471208)(特許文献6)には、タングステン電極の先端部を円錐状に研磨し、さらにタングステン電極の先端部に空隙部を設ける方法が開示されている。特許文献6記載の発明の目的は溶融池からの金属の蒸着により溶接できなくなるといった問題を改善するもので、良好なアークスタートに不可欠な火花誘導の改善に関する前記特許文献5記載の技術と同様の目的であり、本発明の目的とは異なる。
特許文献6には、タングステン電極の直径が4mm、先端部の切頭部の直径が1mmであることなどの記載はあるが、空隙部の幅についての記載はない。しかしながら、特許文献6の本文中の記載から溶着物(deposits)の侵入を防止すべきことが記載されており、また特許文献6の図1より空隙部の幅は0.5mm以下と推定され、この距離は本発明に用いるスリット幅としては小さ過ぎて適切な距離ではない。
また、特許文献5にはスリット幅を極めて微小にすると記述されており,特許文献6記載の発明ではタングステン電極の円錐先端を平らにした切頭円錐形状を用いているが、切頭の直径が1mmであることから、スリットの幅は0.5mm以下と推定される。このような電極先端部の先細加工部分の間隔(特許文献5)や電極先端部の空隙(特許文献6)の場合、タングステン電極先端部の近傍のアークの広がりが小さく、電流密度が大きなままであり、このためタングステン電極の先端部近傍での電流密度と母材の近傍の末広がり状のアーク部の電流密度との大きさの差を小さくできず、タングステン電極の先端部近傍と母材3近傍との圧力差を小さくできないため、アーク圧力を低下する効果が得られない。
請求項1記載の発明は、タングステン電極の先端を円錐状または多角錐状に研磨し、該先端部の中心軸に沿って幅が0.75mm以上、1.5mm以下のスリットを電極の先端から基部側に軸方向に沿って設けたことを特徴とするTIGアーク溶接用電極である。
請求項2記載の発明は、タングステン電極の先端に設けたスリットの形状が先端部側から見て一文字状又は十文字状であることを特徴とする請求項1記載のTIGアーク溶接用電極である。
請求項3記載の発明は、タングステン電極先端の円錐状または多角錐状の先端角度が30°以上かつ100°以下であることを特徴とする請求項1記載のTIGアーク溶接用電極である。
請求項5記載の発明は、溶接進行方向に対するタングステン電極の取付け方向を同一方向にするか又は前記同一方向以外の方向にして溶接を行うことを特徴とする請求項4記載のTIGアーク溶接方法である。
(1)200A以上の大電流でもハンピングビードやアンダーカットビード等の不整ビードを発生させることなく溶接が可能であり、スリットの幅に当たるタングステン電極の近接した2以上の先端の距離を適正に設定することにより、アークの集中を保ったままで、タングステン電極の先端部近傍の電流密度を下げて電極の先端部近傍の圧力と母材近傍の間の圧力の差が小さくなり、プラズマ気流の流速が遅くなり溶融池を押すアーク圧力を軽減し、良好な溶接部を得ることができる。また、100A程度の小電流域でもタングステン電極の近接した2以上の先端の距離を0.75mm以上、1.5mm以下に設定することにより1つのアークを形成することからアークの偏りによるふらつきが発生せずビードの蛇行等は発生しない。
(2)溶接終了時のダウンスロープ、クレータ処理時のように小電流での溶接時にもアークの集中を保ち、ビードの蛇行やビードの幅が細くなり、凸ビードを発生させることのない安定した溶接を行えるため、TIG溶接の高速化や能率化を達成することができる。特に高速溶接が行われる汎用ロボットへの適用、組み立て製品などの溶接部への適用時に安定した溶接を行えるため、TIG溶接の高速化や能率向上を達成することができる。
(3)厚板溶接の多層盛溶接ではビードの重ね部や母材を、融合不良等の欠陥が入らないように充分に溶かすことができる。
請求項2記載の発明によれば、請求項1記載の発明の効果に加えて、タングステン電極の先端に設けたスリットの形状を先端部側から見て一文字状又は十文字状とすることで、ダイヤモンドカッター等で容易に加工できる。また一文字の場合でも十分に方向性の無い溶接が行えるが、特にタングステン電極の直径が5.0mmを越えて大きくなった場合に、十文字の場合に一文字の場合よりもいっそう方向性がない溶接が行える。
請求項3記載の発明は、請求項1記載の発明の効果に加えて、タングステン電極先端の円錐状または多角錐状の先端角度が30°以上かつ100°以下であると、アーク圧力の差はほとんど無く、溶け込み形状もビード深さ/幅比が0.17~0.20でほぼ同一で、ビートの溶け込みを深くする。また、電極先端の研磨角度が100°を超えると、各先端から発生するアークはスリットの方向に拡がるため、ビード深さ/幅比はスリットの方向が溶接進行方向の場合に0.17~0.20より小さく、溶接進行方向直角の場合に0.17~0.20より大きくなり、スリットの設置方向と溶け込み形状の違いが発生する。また、前記研磨角度が30°未満であると、強度が不足して研磨加工が困難となり歩留まりが50%以下となる。
請求項5記載の発明によれば、請求項4記載の発明の効果に加えて溶接進行方向に対してタングステン電極のスリットの方向を変えてもビードの幅/深さ比をほぼ一定とすることができ、切頭電極や中空電極に比較してビード底の溶け込みが深く、ビード底の融合不良等の欠陥が発生しない。
また、スリット幅を1mmより拡げて1.5mmにすると小電流の時に両先端からのアーク4の維持が難しくなり、片側からしかアーク4が発生しなくなる。この現象は従来技術においても説明したが、タングステン電極1の両先端部のそれぞれと母材3(図10)との距離差が生じ、いずれかのタングステン電極1の先端部と母材3との距離が最短になった場合には、最短になった箇所だけからアーク4が発生することがあり、アーク4が偏って発生する原因になることがあるためである。従って、スリット幅は1.5mm以下が良い。
前記スリットが一文字の場合でも十分に方向性の無い溶接が行えるが、特にタングステン電極の直径が5.0mmを越えて大きくなった場合に、十文字の場合に一文字の場合よりもいっそう方向性がない溶接が行える。
2 スリット
3 母材
4 アーク
5 溶融池
6 溶接電源
7 プラズマ気流
Claims (5)
- タングステン電極の先端を円錐状または多角錐状に研磨し、該先端部の中心軸に沿って幅が0.75mm以上、1.5mm以下のスリットを電極の先端から基部側に軸方向に沿って設けたことを特徴とするTIGアーク溶接用電極。
- タングステン電極の先端に設けたスリットの形状が先端部側から見て一文字状又は十文字状であることを特徴とする請求項1記載のTIGアーク溶接用電極。
- タングステン電極先端の円錐状または多角錐状の先端角度が30°以上かつ100°以下であることを特徴とする請求項1記載のTIGアーク溶接用電極。
- 電極の先端を円錐状または多角錐状に研磨し、該先端部の中心軸に沿って幅が0.75mm以上、1.5mm以下で一定のスリットを電極の先端から基部側に軸方向に沿って設け、電極中心付近でスリットを挟んで少なくとも2以上の先端を形成し、得られた複数の近接した先端より1つのアークを形成することを特徴とするTIGアーク溶接方法。
- 溶接進行方向に対するタングステン電極の取付け方向を同一方向にするか又は前記同一方向以外の方向にして溶接を行うことを特徴とする請求項4記載のTIGアーク溶接方法。
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CN102744527A (zh) * | 2012-07-13 | 2012-10-24 | 兰州理工大学 | 一种用于高速tig焊接的耦合电弧钨极 |
HRP20140363B1 (hr) * | 2014-04-17 | 2018-10-05 | ĐURO ĐAKOVIĆ TERMOENERGETSKA POSTROJENJA d.o.o. | Poboljšani postupak mehaniziranog elektrolučnog zavarivanja korijena spoja priključak na sabirnik |
JP2021027736A (ja) * | 2019-08-07 | 2021-02-22 | トヨタ紡織株式会社 | 積層構造体の製造方法及び積層構造体 |
CN116921817A (zh) * | 2023-09-15 | 2023-10-24 | 中建安装集团有限公司 | 自动tig焊电弧聚集度在线监测及智能预警方法 |
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DE102017214460A1 (de) * | 2017-08-18 | 2019-02-21 | Kjellberg Stiftung | Elektrode für einen Schweißbrenner oder einen Schneidbrenner |
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JPS5989690U (ja) * | 1982-12-09 | 1984-06-18 | 三菱重工業株式会社 | Tig溶接用電極 |
JPS6049891A (ja) * | 1983-08-30 | 1985-03-19 | Agency Of Ind Science & Technol | Tigア−ク溶接用電極 |
JPS61273295A (ja) * | 1985-05-29 | 1986-12-03 | Ishikawajima Harima Heavy Ind Co Ltd | 非消耗電極溶接方法 |
JPH0647576A (ja) * | 1992-07-30 | 1994-02-22 | Showa Alum Corp | Tig溶接用電極棒 |
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CN102744527A (zh) * | 2012-07-13 | 2012-10-24 | 兰州理工大学 | 一种用于高速tig焊接的耦合电弧钨极 |
HRP20140363B1 (hr) * | 2014-04-17 | 2018-10-05 | ĐURO ĐAKOVIĆ TERMOENERGETSKA POSTROJENJA d.o.o. | Poboljšani postupak mehaniziranog elektrolučnog zavarivanja korijena spoja priključak na sabirnik |
JP2021027736A (ja) * | 2019-08-07 | 2021-02-22 | トヨタ紡織株式会社 | 積層構造体の製造方法及び積層構造体 |
JP7379914B2 (ja) | 2019-08-07 | 2023-11-15 | トヨタ紡織株式会社 | 積層構造体の製造方法及び積層構造体 |
CN116921817A (zh) * | 2023-09-15 | 2023-10-24 | 中建安装集团有限公司 | 自动tig焊电弧聚集度在线监测及智能预警方法 |
CN116921817B (zh) * | 2023-09-15 | 2023-12-15 | 中建安装集团有限公司 | 自动tig焊电弧聚集度在线监测及智能预警方法 |
Also Published As
Publication number | Publication date |
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JP5832304B2 (ja) | 2015-12-16 |
JPWO2011099637A1 (ja) | 2013-06-17 |
CN102753299A (zh) | 2012-10-24 |
KR20120112743A (ko) | 2012-10-11 |
CN102753299B (zh) | 2015-06-10 |
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