JP2003290949A - Process and equipment for yag laser induced arc filler wire complex welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a gap tolerance expansion for a thick plate butt welding and the prevention of the shortage of the height of reinforcement of weld, and to highly efficiently carry out a penetration welding in a thick plate lap welding or fillet welding. <P>SOLUTION: A YAG (yttrium aluminum garnet) laser induced arc filler wire complex welding process is performed inducing an arc on a filler wire by a plume, that is gas and metallic fumes generated in an plasma state by irradiating the base material to be welded with the YAG laser and limiting a plume produced with the YAG laser in and outside a keyhole, in the state aiming at a laser focal point 8 of YAG laser 9 to the base material to be welded 32 with a filler wire 20 and connecting a power source for wire heating 22 between the filler wire and the base material to be welded. A welding surface is covered with a hood 15, a straightening wire net 16 is put into an inside, the circumference of a welding focal point 8 is enveloped in the straightened flow of shield gas to protect from an oxidation, and the plume is retained. The filler wire 20 in a heating state is sent to a welding pool. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a YAG laser composite welding method and a YAG laser composite welding apparatus using a YAG laser and an electric arc in combination, and in particular, induced arc energy induced at the tip of a filler wire by the YAG laser and the YAG laser. TECHNICAL FIELD The present invention relates to a YAG laser-induced arc filler wire composite welding method and apparatus for performing welding by utilizing the above.

[0002]

2. Description of the Related Art YAG laser welding has the following characteristics and is widely used for automatic welding of steel materials for automobiles and the like: Focused laser light can be obtained, low distortion and high speed welding are possible. Since the laser light absorptivity of the metal material is several times that of the CO ₂ laser, efficient welding is possible. Further, since the wavelength is 1/10 of that of the CO ₂ laser, it is less likely to be affected by plasma generated during welding. Since the laser light can be transmitted through a flexible optical fiber, handling is easy and an articulated robot can be used. In addition, optical transmission to distant places up to about 100 m is possible. Since the laser light can be time-divided (time-sharing) and space-divided (power-sharing), a high utilization efficiency can be obtained by commonly using the laser light in a divided form at a plurality of processing stations.

However, application to laser welding is often restricted to the processing of thin plate layers as compared with welding of other gases, electricity, arc, etc., because joint accuracy is often required. As a technique for improving this restriction, a welding method using both laser light and arc has been devised and disclosed.

For example, JP-A-53-137044, JP-B-56-49195 and JP-A-61-23.
Japanese Patent Publication No. 2079, Japanese Patent Publication No. 4-51271, and Japanese Patent Laid-Open No. 5-69165 disclose a welding method in which a TIG arc and laser light are used in combination. A welding method is disclosed in which a molten pool is irradiated with a laser to deepen the penetration.

Japanese Patent Laid-Open Nos. 53-137044, 61-232079, and 7-246484 disclose a welding method which uses plasma arc and laser light in combination. A welding method is disclosed in which a base material is melted, and a laser is applied to the molten pool to deepen the penetration.

Japanese Unexamined Patent Publication (Kokai) No. 10-216972 discloses a butt welding method using a combination of a laser and a consumable electrode type arc, which is a combined welding method of a laser and a consumable electrode type arc in which a leading laser and a trailing consumable electrode type arc are used. Is disclosed.

In Japanese Patent Laid-Open No. 2000-233287,
The nozzle is provided in a position facing the work in a position substantially coaxial with the optical axis of the laser light system and is supplied with a high voltage for arc discharge, and melts the work by irradiating the laser light. There is disclosed a melting and processing apparatus using a laser beam and an arc for performing melting and processing by the arc discharge in the above state.

On the other hand, the welding process technology using both laser light and filler wire is applied to widen the margin against variations in the groove gap, suppress the reduction of the bead width in high-speed welding, and improve the undercut of the butt portion. Has been done.
As the filler wire to be used, a filler wire which is not electrically heated, a so-called cold wire or a filler wire which is electrically heated, a so-called hot wire is disclosed.

For example, in Japanese Unexamined Patent Publication No. 4-344873, a wire having a diameter of 0.4 mm is fed from a direct current power source, the wire feeding is started, and it is detected that the tip of the wire comes into contact with the base metal. A hot wire TIG that starts an arc (page 4, column 5, lines 9 and 10), heats the wire from the contact tip to a semi-molten state, and sends it to the molten pool formed by TIG arc welding.
Welding is presented. In this Japanese Laid-Open Patent Publication No. 4-344873, an additive wire having a diameter of 0.6 mm or less is electrically heated to form a weld metal, and a wire contact member is used to form the welded wire through an elastic body. Pressing the wire to heat the wire by energizing
There is also a proposal that plasma arc, electron beam or laser may be used in addition to G arc.

[0010]

The welding with the YAG laser alone has the following problems: The YAG laser collects a light beam to increase the energy density and perform welding, but the focused spot diameter is φ0.3 to φ.
Since it is as small as 1 mm, in the case of butt welding, if there is a butt gap (for example, (c) in FIG. 3), the laser beam passes through and a welding defect occurs. For this reason, severe cutting of the end surface of the welded part of the material to be welded and a method of restraining the welded part are required. ) Is narrow, and joint strength cannot be obtained.-In fillet welding as well, the penetration width (for example, (e) in FIG. 3) cannot be sufficiently obtained, and joint strength cannot be obtained; When the filler wire is simultaneously supplied to the YAG laser welded portion for the purpose of improving the surface bead and the like and welding is performed, energy is consumed for melting the filler wire and the weldability is deteriorated. Since the YAG laser device has a high initial cost, the equipment cost becomes enormous when introducing a plurality of equipments such as an automobile production line.

In Japanese Utility Model Laid-Open No. 62-82194, in laser welding, plasma gas and metal vapor, that is, a plume in and above a keyhole formed in a base metal to be welded by laser irradiation absorbs a laser beam. Therefore, assuming that welding with deep penetration cannot be performed, a nozzle structure is proposed in which a shielding gas is blown into the keyhole to guide the plume to the exhaust passage formed outside the laser optical path, and suction and exhaust from the exhaust passage. . Although this is an approach to make the laser heat input to the base material efficient, at the wavelength of the YAG laser, the YAG laser light is absorbed in the plasma gas and metal vapor or plume inside the keyhole and above it. The degree is low, and the force to push down the keyhole disappears when the gas and metal vapor turned into plasma are exhausted.
The penetration depth becomes shallow.

JP-A-53-137044, JP-B-56-49195, JP-A-61-232079, JP-B-4-51271 and JP-A-5-6.
Japanese Patent No. 9165 discloses combined welding of TIG and laser in which a base material is melted by using a TIG arc and a molten pool is irradiated with a laser to deepen the penetration. These are the approaches of forming a shallow but wide melt pool by TIG and obtaining a narrow but deep penetration by laser. The TIG widens the melting width of the base material surface by a wide melting pool, fills the butt gap shown in FIG. 2 (c), and the laser forms deep penetration, for example, as shown in FIG. 2 (e). Since the penetration width is wide (the penetration is deep), the welding efficiency is improved and the welding quality is improved as compared with the case where only the laser is used.

However, at the deep position, only the penetration by the laser occurs, so that the penetration width is narrow and the welding strength is low. For example, the joint interface width of lap welding shown in FIG. 2D is narrow, and its increase is desired. This is Japanese Patent Laid-Open No. 7-2464.
The same applies to the plasma arc disclosed in Japanese Patent Application Laid-Open No. 84-18497 and Japanese Patent Application Laid-Open No. 2000-233287.

As a welding method in which a laser beam and a filler wire are used in combination, a filler wire which is not electrically heated, a so-called cold wire, has been generally used, and a part of laser light energy for melting the base material is used. There is a problem that the filler wire is consumed for melting and the weldability is deteriorated. On the other hand, the above-mentioned JP-A-4-34487
Japanese Patent Publication No. 3 discloses a hot wire TIG using a filler wire with a diameter of 0.6 mm or less for the purpose of forming a narrow and stable weld bead in high-speed welding of thin plates, and proposes to change the TIG arc to laser irradiation. is there.

However, since a sufficient penetration depth cannot be obtained, the welding strength is low. In particular, it is not suitable for lap welding or fillet welding, which requires a deep penetration depth.

It is an object of the present invention to prevent the expansion of the gap tolerance and the excess height of the butt welding in thick plate butt welding, and to perform the penetration welding in thick plate lap welding and fillet welding with high efficiency. And

[0017]

According to the present invention, a laser irradiation point (8) of a YAG laser (9) is applied to a base metal (31, 32) to be welded.
Aim at the vicinity with the filler wire (20), the filler wire heating power source (22) is connected between the filler wire and the welding target base material in a state where the filler wire is not in contact with the welding target base material, After irradiating the YAG laser to the base metal to be welded and inducing and maintaining an arc in the filler wire by the gas and metal vapor turned into plasma by the YAG laser, the filler wire is heated to a vicinity of the irradiation point of the YAG laser. Supply so as not to contact the molten pool,
Welding using both YAG laser and induced arc is carried out by keeping plasma gas and metal vapor, which contribute to stable induction arc, inside and outside the keyhole (Fig. 1).

In order to facilitate understanding, symbols in parentheses that correspond to corresponding elements of the embodiments shown in the drawings and described later or corresponding items are added for reference. The same applies to the following.

According to the present invention described above, in the usual combined use of laser and TIG welding, high-frequency spatter is blown between the electrode and the base material, thereby separating the gas and generating an arc, but high-frequency spark is not required. The gas and the metal vapor or plume turned into plasma by the YAG laser and the arc become high temperature and high pressure to push down the molten metal,
Further, due to this heat conduction, it is possible to obtain a welding result in which the speed is higher than the welding speed of the laser alone and the bead width is wide, and the penetration is deep.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiment of the present invention, the ratio Vf / V of the filler wire supply speed Vf to the welding speed V is 1 or more, that is, the filler wire supply speed is not less than the welding speed and the wire is heated by a heating power source. The filler wire feed rate is controlled so that the filler wire comes into contact with the molten pool while heating. For example, filler wire /
The voltage value and current value between the welding base materials are detected and the resistance value between the filler wire / welding base material is calculated. When the calculated resistance value deviates from the higher side of the set range so as to be within the set range corresponding to the range where the supply speed of the filler wire comes into contact with the molten pool, the wire supply speed Vf is increased, Decelerate when moving to the lower side.

As a result, in particular, widening of the gap tolerance and elimination of insufficient excess in butt welding of thick plates, and elimination of insufficient excess due to increase in penetration depth with increased penetration depth in lap welding where the plate thickness increases. It is possible to increase the penetration width in fillet welding, ensure the joint strength, and obtain stable welding results without welding defects. On the other hand, if the above-mentioned Vf / V is less than 1, insufficient build-up height and burn-through will occur.

Since the heat input of the wire due to the induced arc and the resistance heating of the energization of the filler contribute to the melting of the filler wire, the joint use of the filler wire does not deteriorate the weldability. Not only that, due to the heat input of the induced arc to the base material, a welding performance equivalent to that of a high-output YAG laser can be obtained with a low-output YAG laser. A mode in which laser light is dividedly supplied from one YAG laser light source to a plurality of laser irradiation heads can be easily implemented, and the facility cost per laser irradiation head can be easily reduced.

[0023]

FIG. 1 shows a YAG laser-induced arc filler wire composite welding apparatus according to an embodiment of the present invention. A YAG laser beam 9 is guided to a YAG irradiation head 10 from a YAG laser light source (not shown) through an optical fiber cable (not shown), converges through a lens 11 in the head 10,
It passes through the objective sleeve 12 and the relay sleeve 13 toward the focal point 8 (irradiation point).

An objective hood 15 is fixed to the lower end of the relay sleeve 13. In the hood 15, there is a gas rectifying wire net 16 which divides the internal space into a gas supply space which is an upper space and a welding space which is a lower space. The hood 15 and the wire mesh 16 have openings 17 and 18 through which the laser beam 9 directed to the focal point 8 passes.

A wire guide 19 penetrates the hood 15 and the wire net 16 and is fixed to the hood 15. The filler wire 20 is fed from a wire feeding device (not shown) and fed into the wire guide 19,
The wire is fed to the vicinity of the laser focus 8 from the wire feeding tip at the lower end of the. At the bottom of the hood 15, the base material 3 to be welded
There are wheels 23, 24 to open a small gap between 2 and the lower end of the hood 15.

When the base materials 31 and 32 shown in FIG. 1 are lap-welded, the shield gas is blown into the relay sleeve 13 through the base 14 attached to the relay sleeve 13, the power switch 21 of the wire heating power source 22 is closed, and the base material is closed. An unloaded voltage is applied to the filler wires 31 and 32 between the filler wire 20 and the base material which are not in contact with each other.
Irradiation of the G laser beam 9 is started. An arc is induced between the filler wire 20 and the base materials 31 and 32 by the action of the plume generated by this irradiation. If the filler wire target position is outside the plume generated by laser irradiation, this arc is not induced, so the wire target position is determined so that the filler wire tip is inside the plume generated by laser irradiation. After the arc is induced in the filler wire, the YAG irradiation head 10 is started to be driven in the y direction, and the feeding is started so that the filler wire 20 comes into contact with the molten pool at a speed. This results in a stable welded state. That is, laser irradiation welding and arc welding continue in parallel.

In this welding state, the shield gas blown from the mouthpiece 14 into the relay sleeve 13 passes through the opening 17 from the relay sleeve 13 into the gas supply chamber above the rectifying wire net 16 in the hood 15, where it is located. , Diffusing in the x and y directions to form a substantially vertical rectification through the mesh of the rectifying wire net 16 and descending to the surface of the base metal 32 to be welded, and passing through the gap at the lower end of the hood 15 along the surface. And go out of the hood. With such a flow of shielding gas,
The inside of the hood 15 is filled with shielding gas, and the wire mesh 16
In the welding space below, the shield gas is gently rectified in the vertical direction, and wraps around the focal point 8, that is, the keyhole by laser irradiation, and the plume inside and outside thereof.

This surrounding gas shields the molten pool at the focal point 8 and the filler wire 20 from the air (oxygen) to prevent them from oxidizing, and also suppresses the plume scattering inside and outside the keyhole to form a plume inside and outside the keyhole. stop.

The detection circuit 26 detects a voltage value and a current value between the base metal to be welded and the filler wire, and calculates a resistance value between the base metal to be welded and the filler wire based on these detected values to obtain the resistance. An electric signal representing the value is given to the wire feeding controller 27. The wire feed control device 27 has a ratio Vf / V of the filler wire supply speed Vf and the welding speed V of 1
It is judged whether the detected resistance value is within the range of the resistance value between the welding target base metal / filler wire in the above setting range, and if the detected resistance value deviates to the upper side of the range, the speed increase deviates to the lower side. To the wire feeding device 25, and in response to this, the wire feeding device 25 increases or decreases the wire feeding speed.
As a result, the filler wire 20 is heated by the filler wire heating power source 22, and the filler wire 20 is fed at a speed at which the ratio Vf / V between the filler wire supply speed Vf and the welding speed V is 1 or more.

A keyhole is schematically shown in FIG. The irradiation of YAG laser, that is, the injection of high-density energy, causes the plume in the keyhole to become an explosive high temperature and high pressure, which pressurizes the molten metal in the keyhole, melts the bottom of the keyhole, and causes deep penetration. Occurs. If a strong shield gas flow that strongly removes (blowns out) the plume is focused on the focal point 8, the induced arc will not continue stable and the penetration will be extremely shallow. It is essential to keep it in the keyhole. This was confirmed by experiments.

By the welding work described above, a lap welding bead as shown in FIG. 2B could be obtained. In the figure, 33 is a molten and solidified portion of the base material, and 34 is a bead formed by the filler wire 20. Wide welding interface width, deep penetration, high speed, stable quality welding are possible. The welding conditions at this time are as follows: welding base material 31: material A5052 plate thickness 2 mm welding base material 32: material A5052 plate thickness 2 mm lap joint YAG laser: output 4 kW, current without assist gas (center gas): 150A No-load voltage: 20V Shield gas: Ar 25 liter / min Welding speed: 2m / min Filler wire: Standard A5356WY Feeding speed:
2m / min

[0032]

As described above, since the arc is induced by the plume generated by the laser irradiation, it is not necessary to start the arc by applying the high frequency high voltage. YAG
Since arc welding is added to laser welding, the heat input to the base metal surface layer is large, and by fixing the plume in and around the keyhole by YAG laser irradiation, even if there is a small butt gap, there is no excess and no deep melting. In addition, stable and reliable welding with a wide joint interface width is possible, and high-speed welding is possible.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a welding head portion of a YAG laser-induced arc filler wire composite welding apparatus according to an embodiment of the present invention.

2A is a schematic enlarged cross-sectional view around the focal point 8 shown in FIG. 1, and FIG. 2B is a YA using the welding apparatus shown in FIG.
It is an expanded sectional view which shows typically a welding bead which is a result of G laser induction arc filler wire compound welding. (C)
Is an enlarged sectional view showing a butt gap in the case of general butt welding, (d) is an enlarged sectional view showing a joint interface width in the case of lap welding, and (e) is a penetration width in the case of fillet welding. It is an expanded sectional view shown.

[Explanation of symbols]

8: Focus of YAG laser light flux 9: YAG laser light flux 10: YAG irradiation head 11: Lens 12: Objective sleeve 13: Relay sleeve 14: Base 15: Objective hood 16: Gas rectifying wire mesh 17, 18: Opening 19: Filler wire guide 20: Filler wire 21: Power switch 22: Wire heating power source 23, 24: Wheel 31, 32: Base material for welding 33: Molten and solidified portion of base material 34: Beads 41, 42 formed by filler wire: Welding Target base material 43,44: Base material for welding 45,46: Base material for welding

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B23K 9/16 B23K 9/16 K 26/14 26/14 Z (72) Inventor Hirofumi Sonoda Chiba Narashino City Higashi Narashino 7-61-1 Nittetsu Welding Industry Co., Ltd. (72) Inventor Kenji Okuyama 7-6-1, Higashi Narashino Higashi Narashino, Narashino City, Chiba Equipment and Opto (72) Inventor, Junichi Kurobu, 7-6-1, Higashi Narashino, Narashino City, Chiba Prefecture, Nippon Steel Welding Industry Co., Ltd. (72) Inventor, Takanori Yaha, Wako, Saitama, Chuo 1-4-1 Incorporated Honda Technical Research Institute (72) Inventor Masato Takigawa 1-4-1 Chuo, Wako-shi, Saitama Incorporated Honda Technical Research Institute (72) Inventor 1 Yasushi Tomo 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Co., Ltd. Corporate Technology Development Division (72) Inventor Toshiyasu Ueana 2-6-3 Otemachi, Chiyoda-ku, Tokyo F-term of Nippon Steel Corporation ( Reference) 4E001 AA03 BB12 DC02 DD02 EA01 EA03 4E068 BC01 CH07 CJ01 4E082 AA01 BA01 EB01 EB11 EB21 EF16 EF21

Claims (5)

[Claims] 1. A YAG laser irradiation point on a base metal to be welded is aimed by a filler wire, a filler wire heating power source is connected between the filler wire and the base metal to be welded, and the YAG laser is welded on. Irradiate the base material,
The filler wire is supplied in the vicinity of the generated gas and metal vapor that are turned into plasma, and after the arc is induced in the filler wire by the action of the gas and metal vapor that is turned into plasma, the filler wire is fed in a heated state. A YAG laser-induced arc filler wire composite welding method in which welding using both YAG laser and induced arc is performed while keeping the gas and metal vapor generated into plasma by the YAG laser inside and outside the keyhole. 2. The YAG laser induced arc filler wire composite welding method according to claim 1, wherein a ratio Vf / V of the supply speed Vf of the filler wire and the welding speed V is 1 or more. 3. The inside of a hood covering the welding surface of the base metal to be welded is divided into a welding space and a gas supply space on the side of the welding surface by a gas rectifying body having a large number of openings, and the hood and the gas conditioning are arranged. By irradiating the base material with a YAG laser through the opening of the fluid and supplying a shield gas to the gas supply space, a shield gas atmosphere is created around the laser irradiation point and the tip of the filler wire through the gas rectifier, and the shield gas is shielded. The YAG laser-induced arc filler wire composite welding method according to claim 1 or 2, which suppresses the disturbance of the gas and metal vapor that have been turned into plasma in the keyhole due to the gas. 4. A YAG laser welding head; a hood mounted on the tip of the head, having an opening through which the YAG laser emitted by the head penetrates, and having a side facing the base metal to be welded open; fixed to the hood A filler wire guide for guiding the filler wire of the YAG laser welding head aiming at a laser irradiation point on a base metal to be welded; a filler wire guide from a position apart from the filler wire to the hood so as not to follow the outer peripheral surface of the filler wire guide. Gas supply port for supplying shield gas; arc between the filler wire and the filler wire by the plasma gas and metal vapor generated by the irradiation of the YAG laser to the weld metal Power source for inducing an electric current and heating the filler wire; and a filler wire to keep the induced arc stable. A YAG laser-induced arc filler wire composite welding device, comprising: a wire supply device for feeding a yarn. 5. The filler wire guide further comprising: a gas rectifier having a large number of openings, which divides the interior of the hood into a welding space on the base metal side to be welded and a gas supply space on the laser welding head side. The YAG laser-induced arc filler wire composite welding device according to claim 4, wherein the filler wire penetrates the gas rectifier, and aims at the laser irradiation point of the YAG laser welding head on the base material to be welded or near the irradiation point; .