JP2003290948A - 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 sheet metal butt welding, and to highly efficiently carry out a penetration welding in a sheet metal 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 the vicinity of laser focal point 8 or the laser focal point of a YAG laser 9 to the base materials to be welded 31 and 32 with the filler wire 20 and connecting a power source for applying power to wire 22 between a wire 20 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 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 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 melting and processing by the arc discharge in the above-described 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. 2), the laser beam passes through and a welding defect occurs. For this reason, severe cutting of the weld end surface of the material to be welded and a method of restraining the weld are required; -In lap welding, the joining interface width of the penetrating bead from the upper plate to the lower plate (for example, (d) in FIG. 2). ) Is narrow and the joint strength cannot be obtained.-Even in the fillet welding, the penetration width (for example, (e) in FIG. 2) cannot be sufficiently obtained in the same manner as above, and the 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.

An object of the present invention is to increase the gap allowance in butt welding of thin plates and to perform penetration welding in lap welding of thin plates and fillet welding with high efficiency.

[0017]

According to the present invention, a filler wire (20) is used to aim at a laser irradiation point or a vicinity (8) of a YAG laser (9) on a base metal (31, 32) to be welded, and the filler wire (20) is used. A filler wire power application power source (22) is connected between the filler wire and the welding target base metal in a state where the wire is not in contact with the welding target base metal, and the YAG laser is irradiated to the welding target base metal. An arc is induced and maintained in the filler wire by the YAG laser plasmatized gas and metal vapor, and then the filler wire is applied to the YAG laser.
The laser is supplied near the laser irradiation point so that it does not come into contact with the molten pool, and the plasmatized gas and metal vapor that contribute to the sustained stability of the induced arc are kept inside and outside the keyhole to perform welding using both YAG laser and induced arc (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 less than 1, that is, the filler wire supply speed is made lower than the welding speed, and Welding is controlled so that the supply speed is such that the filler wire does not come into contact with. For example, the detection circuit (2
The resistance value is calculated by detecting the current value and voltage value between the filler wire and the base metal to be welded according to 6), and the ratio Vf / V of the filler wire supply speed Vf to the welding speed V is set within a setting range of less than 1. When the detected resistance value is out of the range of the high resistance value, the supply speed of the filler wire is increased, and when the detected resistance value is out of the low side, the supply speed is decelerated, and the ratio Vf / V of the filler wire supply speed Vf to the welding speed V is set. The filler wire feed rate is controlled so that is within the set range of less than 1.

As a result, it is possible to obtain the effects of widening the welding gap tolerance, eliminating the excess height of excess metal, and optimizing the excess metal shape (preventing the convex shape) particularly in a butt joint having a relatively thin plate thickness.
On the other hand, if the above-mentioned Vf / V is 1 or more, the overfilled shape becomes a convex shape, and the penetration depth decreases.

As other effects, an increase in the joint interface width in thin plate lap welding, an increase in the penetration width in fillet welding, etc. can be obtained.
The joint strength can be secured, and stable welding results without welding defects can be obtained.

Since the heat input of the wire due to the induced arc contributes 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. It is possible to easily implement a mode in which laser light is dividedly supplied from one YAG laser light source to a plurality of laser irradiation heads.
It is easy to reduce the equipment cost per laser irradiation head.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0025]

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. The wire guide 19 is the hood 15
It also penetrates the wire netting 16 and is fixed to the hood 15. The filler wire 20 is fed from the wire feeding device 25 and fed into the wire guide 19, and is fed from the wire feeding tip at the lower end of the wire guide 19 to the vicinity of the laser focus 8. At the bottom of the hood 15, wheels 23 and 24 are provided to open a minute gap between the base material 32 to be welded and the lower end of the hood 15.

When the thin plates 31 and 32 shown in FIG. 1 are butt-welded together, a shielding gas is blown into the relay sleeve 13 through the base 14 attached to the relay sleeve 13, and the power switch 21 of the wire power application power source 22 is closed to close the thin plate 31. And 32, an unloaded voltage is applied to the filler wire 20 between the filler wire 20 and the thin plate which are not in contact with each other, and irradiation with the YAG laser beam 9 is started. An arc is induced between the filler wire 20 and the thin plates 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 starts to be driven in the y direction, and the filler wire 2
Feeding is started so that 0 does not contact the molten pool. As a result, a stable welding state is achieved in the thin plate. 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 prevents the plumes from scattering inside and outside the keyhole to form a plume inside and outside the keyhole. stop.

The detection circuit 26 detects the voltage and current between the base materials 31 and 32 to be welded and the filler wire 20, calculates the resistance value according to the voltage value and the current value, and sends a signal representing the resistance value to the wire. To the device 27. The wire feeding device 27 sets the resistance value to a set value (a value corresponding to a predetermined induced arc length).
It is determined whether or not it is within a set range centered on the line. If it is outside the set range, the wire feeding device is instructed to accelerate, and if it is out of the low side, deceleration is instructed. That is, the ratio Vf / V between the filler wire supply speed Vf and the welding speed V is controlled to be less than 1 so that a predetermined induced arc length is obtained.

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 above welding work, a butt weld bead as shown in FIG. 2B could be obtained. In the figure, reference numeral 33 is a site where the base material is melted and solidified, and 34 is a bead formed by the filler wire 20. There is no excess buildup, and the buildup shape and penetration depth are suitable. High-speed, stable quality welding is possible. The welding conditions at this time are as follows: (Welding example 1) Welding base material 31: Material A5052 plate thickness 2 mm Welding base material 32: Material A5052 plate thickness 2 mm Butt joint YAG laser: output 4 kW, assist gas (center) Gas) None No-load voltage: 20V Current 120A Shield gas: Ar 25 liters / min Welding speed: 4m / min Butt joint filler wire: Standard A5356WY Feeding speed:
2m / min (Welding example 2) Welding base material 31: Material A5052 Plate thickness 1mm Welding base material 32: Material A5052 Plate thickness 1mm Butt joint YAG laser: Output 3.5kW, no assist gas (center gas) No load voltage: 20V 100A Shielding gas: Ar 25 liter / min Welding speed: 6m / min Butt joint filler wire: Standard A5356WY Feeding speed:
2m / min

[0033]

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 even if there is a slight change in the butt gap, stable beads can be obtained with a proper bead with extra height and extra shape. Therefore, high-speed welding is possible. In addition, since the plume is retained in and around the keyhole by YAG laser irradiation, it is possible to apply to welding having a deep penetration and a wide joint interface width.

[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 power application power source 23, 24: Wheel 31, 32: Base material for welding 33: Molten and solidified part of base material 34: Beads 41, 42 formed by filler wire: Base material for welding 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 BA06 BC01 CH07 CJ01 4E082 AA01 BA01 EB01 EB11 EB21 EF16 EF21

Claims (5)

[Claims] 1. A YAG laser is welded to a base material to be welded by aiming a laser irradiation point of the YAG laser with a filler wire and connecting a filler wire power application power source between the filler wire and the base material to be welded. By irradiating the target base material, supplying the filler wire in the vicinity of the generated plasma-generated gas and metal vapor, after inducing an arc in the filler wire by the action of the plasma-generated gas and metal vapor, Supplying the filler wire Y
A YAG laser-induced arc filler wire composite welding method in which welding using both a YAG laser and an induced arc is performed while keeping the gas and metal vapor generated into plasma by the AG 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 less than 1. 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 the base metal to be welded; 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 And a power source that supplies enough electric power to sustain the arc after the arc is induced; and Click is Kyusuru wire feeder feeding a filler wire to last stably; comprises, YAG laser induced arc filler wire hybrid welding apparatus. 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 filler wire penetrates the gas rectifier to aim a laser irradiation point of the YAG laser welding head on the base material to be welded;
AG laser induced arc filler wire composite welding equipment.