JP2012000630A - Laser welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser welding apparatus capable of continuous lamination welding, especially whose welding quality is stable in a laser welding method in which a welding part of a material to be welded is irradiated with a laser beam and laminate welding is applied to a groove part while supplying a welding wire to an irradiation part of the laser beam.SOLUTION: The laser welding apparatus includes: a machining head 8 for irradiating the material to be welded with a collected laser beam; a feeding means 16 for feeding the welding wire to the irradiation part of the laser beam; a shielding gas supply means 6 for protecting a molten pool formed by the irradiation of the laser beam and the vicinity; a means for moving the machining head or the material to be welded; a machining head protection means for protecting an optical component of the machining head from a welding product generated from a molten part; a sucking means 19 for sucking fume produced in welding; a protection means 18 for protecting the machining head from the reflected laser beam and radiation heat from the welding part; and a cleaning means 20 for removing the welding product deposited on a surface of welding metal lamination-welded.

Description

  The present invention is particularly suitable for laser welding in which a welded portion of a material to be welded is irradiated with a laser beam and the groove portion is laminated and welded while supplying a welding wire to the irradiated portion of the laser beam, and the welding quality is particularly high and stable. The present invention relates to a laser welding apparatus capable of continuous lamination welding.

  In laser welding, since the energy density of the laser beam of the heat source is high, deep penetration can be obtained as compared with ordinary arc welding. Furthermore, since a highly accurate welded portion with low distortion can be obtained at a high speed, it is used in various directions. On the other hand, laser welding has a difficulty in that the tolerance to the gap of the welded portion is low because the condensing spot size of the laser beam is small. Therefore, when a welding gap cannot be avoided in butt welding, laser welding is performed while supplying a welding wire.

  Furthermore, although laser welding has a high energy density, it is not easy to join thick steel plates by through welding. In order to weld a thick plate exceeding 25 mm in thickness, even with a laser with a maximum output of several kW to several tens of kW widely used in general, a groove is provided at the time of butt welding, and the laser and the weld Multi-layer welding is performed by using a wire together.

  Patent Document 1 discloses a lamination welding method in which a welded portion is set to a narrower groove width and a laser beam is applied to the welding wire while supplying the welding wire.

  In Patent Document 2, in a groove laser welding method in which a welding wire is added, the energy and welding time required for preheating the welding wire and melting the welding wire are reduced, and the aspect of the welded portion is about 2 or more. A laser welding method is disclosed.

  In Patent Document 3, a narrow groove is provided at the butt portion, a curvature and a root surface are provided at the bottom of the groove, and the ratio of the penetration depth to the penetration width of the weld metal is 1 or more and 1.4 or less. A laser welding method is disclosed.

  In Patent Document 4, in order to prevent the smoke and spatter generated from the melting portion on the protective glass of the processing head, an air outflow means and a suction device for sucking out the air flowing out through a filter are provided below the protective glass. A laser welding apparatus is provided.

  Patent Document 5 discloses a laser processing apparatus including an oscillator that emits a continuous wave or pulse wave thermal processing laser and a pulse wave surface treatment laser beam.

Non-Patent Document 1 discloses that in a groove laser welding method using a CO ₂ laser, a plasma removal side nozzle having an inner diameter of 1 mm is arranged in front of the laser irradiation portion in the welding progress direction, and a gas is blown. Discloses a laser welding method for welding while supplying a welding wire.

JP-A-9-201687 JP 2005-515895 A JP 2007-190586 A JP 59-16692 A JP 2008-254006 A

Yoshiaki Arata, Hiroshi Maruo, Isamu Miyamoto, Ryoji Nishio.High Power CO2 Laser Welding of Thick Plate.Transactions of JWRI, 15 (2), 1986, 27-34

  In the welding of large structures of thick cylindrical plates such as core shrouds for nuclear power plants, when welding is performed by forming a welding groove, multilayer welding requires a lot of time and is continuously It is desirable to weld. However, in high-power laser welding with an output of several kW or more, welding generation such as fumes (metal fine particles and metal compound fine particles generated by solidification of metal vapor) and spatter (molten metal scattered matter) generated from the welded part A lot of radiant heat and reflected light are generated from the object and the melted part, and continuous welding for a long time is not realized.

  As shown in FIG. 7, laser multi-layer welding is performed by butting the welded materials 1a and 1b, forming a groove 2 at the butted portion, and irradiating laser beam 4 while feeding a welding wire 3 to the groove 2. Metal 5 is laminated and welded. In laser welding, the laser beam 4 is irradiated under defocus conditions while shifting the focal position in order to ensure penetration into the workpiece and to melt the welding wire 3 stably. Further, in order to increase the amount of weld metal filling the groove 2, a high output condition is used. 6 is a shield gas nozzle, 7 is an optical system protection cylinder, 8 is a processing head having an optical system for condensing laser light, 9 is a fume, 10 is reflected light of the laser light, and 11 is an optical fiber.

  Since laser welding has a high energy density, the laser irradiation causes metal evaporation and molten metal scattering on the surface of the material to be welded, and a large amount of fume and spatter are generated. The amount of generation of fumes and sputtering tends to further increase when the laser output is high or under defocus conditions.

  When fume is explained in particular, fume adheres to the surface of the weld metal that has been melted and solidified and to the groove wall. When the next layer is laminated with fume attached, welding defects such as poor fusion and porosity occur. In order to prevent fume from adhering to the surface of the weld metal, a shielding gas is supplied to the weld in order to shield the weld from the air and prevent oxidation of the weld metal.

  However, when the groove is deep, it is difficult to completely prevent fume adhesion. Then, after welding, the welding product of the fumes adhering to the weld metal and the groove wall is physically removed with a brush or the like, and then the next layer is welded. For this reason, in the case of circumferential welding of a cylindrical object, since the welding metal surface and the groove wall need to be cleaned for each pass welding, continuous welding cannot be performed and welding efficiency is poor. Further, fumes are metal fine particles and metal compound fine particles generated by solidification of metal vapor, and there is a problem that it becomes more difficult to remove due to moisture absorption or the like.

  Further, if fume or spatter adheres to the laser light condensing optical system of the processing head or its protective glass, filter, etc., the laser output, beam shape, etc. change, so stable welding cannot be performed. For this reason, conventionally, as disclosed in Patent Document 4, air is blown out below the protective glass to prevent fume and spatter from adhering to the optical system. However, since the processing head having a condensing optical system is also affected by the reflection of laser light from the molten metal part and the radiant heat of the molten part, the temperature of the processing head and head drive system during long-time welding such as continuous welding. There exists a subject that it is easy to produce the damage by a raise, reflected light, etc.

  The present invention has been made in view of the above-described problems, and provides a laser welding apparatus that can stably obtain a high-quality welded portion even when continuous lamination welding is performed.

  A laser welding apparatus of the present invention for solving the above-described problems includes a processing head that has an optical system for condensing laser light and irradiates the workpiece with laser light, and a laser beam irradiation portion of the workpiece. A wire feeding means for feeding a welding wire, a shield gas supply means for shielding the melted portion formed in the welded material and its vicinity by irradiation of laser light, and the processing head and the welded material are relatively A moving means that moves the laser beam to the groove formed at the joint of the material to be welded to feed the welding wire, melt the material to be welded and the welding wire, and stack the groove In the laser welding apparatus for welding, the laser welding apparatus includes a suction means for sucking a welding product generated by welding, and a machining head protecting hand for protecting the machining head from reflected light of the laser beam and radiation heat of a welded portion. When, characterized in that it has a cleaning means for removing the welded products deposited laminated welded surface of the weld metal.

  The laser welding apparatus may further include an optical system protection unit that protects the optical system of the processing head from a weld product generated from the melted portion.

  In the laser welding apparatus, the welding product includes at least one of fume and spatter.

  Further, in the laser welding apparatus, a trailer member is provided between the processing head for irradiating the laser beam and the welding product suction means to protect the weld metal from the atmosphere and guide the suction by the welding product suction means. It is characterized by that.

  Further, in the laser welding apparatus, the machining head protection means is a plate-like member that is installed between the machining head and the material to be welded and protects the machining head and its accessory device from laser reflected light and welding part radiant heat. It is characterized by that.

  In the laser welding apparatus, the machining head protection means has a concave curved surface.

  Further, in the laser welding apparatus, the processing head protection means has a shield gas supply means and a water cooling structure.

  Furthermore, in the laser welding apparatus, the cleaning means for removing the weld product deposited on the surface of the weld metal laminated and welded includes pulse laser irradiation means.

  Further, in the laser welding apparatus, the cleaning means for removing the weld product deposited on the surface of the weld metal laminated and welded includes a mechanical removal means.

  Further, in the laser welding apparatus, the mechanical removal means of the cleaning means includes a rotating brush for removing the weld product deposited on the surface of the weld metal, a gas spraying means, and a suction means for sucking the removed weld product. It is characterized by having.

  Further, in the laser welding apparatus, the cleaning means for removing the weld product deposited on the surface of the weld metal laminated and welded includes a pulse laser irradiation means and a mechanical removal means.

  According to the present invention, laser welding is performed by laminating and welding the welded material and the welding wire while irradiating the laser beam to the groove formed at the joint portion of the welded material and feeding the welding wire. In the apparatus, the laser welding apparatus is laminated and welded with suction means for sucking a weld product generated by welding, processing head protection means for protecting the processing head from reflected light of the laser beam and radiant heat of the welded portion. By having a cleaning means that removes weld products deposited on the surface of the weld metal, it is possible to remove weld products such as fumes and spatters adhering to the weld metal surface and groove wall surface along with the progress of welding. Laser welding is possible.

  Further, since it is possible to eliminate the influence on the machining head and its drive system due to the reflection of the laser beam from the molten metal part and the radiant heat of the molten part, continuous welding for a long time is possible.

The perspective view which shows the laser welding apparatus of Example 1 of this invention The schematic diagram which shows the welded structure of this invention Example 1. Schematic diagram of the welding groove of the welded structure of Example 1 of the present invention Schematic diagram of a weld bead cross section of Example 1 of the present invention The perspective view around the welding head of the laser welding apparatus of Example 1 of this invention Schematic diagram showing Example 2 of the present invention Perspective view around the welding head of the conventional laser multi-layer welding apparatus

  Hereinafter, embodiments of the laser welding apparatus of the present invention will be described with reference to the drawings.

  FIG. 1 shows a perspective view of the welding apparatus of the first embodiment of the present invention. The laser beam 4 oscillated from the laser oscillator 12 is transmitted by the optical fiber 11 and sent to the machining head 8. The laser beam 4 condensed by the processing head 8 by a condensing optical system (not shown) is irradiated into the groove 2 formed by the materials to be welded 1a and 1b, and the materials to be welded 1a and 1b and the welding wire 3 are melted. Then, welding is performed while forming the molten pool 13, and the weld bead 5 is formed.

  The welding wire 3 is fed into the molten pool 13 from the front in the welding progress direction by a wire feeding device 16 controlled by a wire feeding control device 17. The molten pool 13 and the vicinity thereof are shielded from the atmosphere by the shielding gas ejected from the shielding gas nozzle 6. The shield gas is supplied from the gas cylinder 14 to the shield gas nozzle 6 through the gas flow rate control device 15.

  The welding material is melted by irradiating the materials to be welded 1a and 1b with the laser beam 4. At that time, the radiant heat is generated from the fumes 9, the reflected light 10 of the laser beam 4 and the melted portion. In order to prevent the fume 9 from adhering to the condensing optical system of the processing head 8, the condensing lens of the condensing optical system (not shown) of the processing head 8 and the lower part of the protective glass are arranged in a direction substantially perpendicular to the laser beam 4. Air is passed through the air nozzle 36. Further, an optical system protection cylinder 7 for preventing the fume 9 from adhering to the optical system is attached to the condensing optical system of the processing head 8.

  A protective plate 18 that protects the machining head 8 from reflected light of laser light and radiant heat from the welded portion is attached to the tip of the optical system protection cylinder 7. The protection plate 18 has a substantially dish-like concave shape, and is entirely cooled with water by a cooling device (not shown). The protection plate 18 has a function of blocking the radiant heat generated from the melting portion and the reflected light of the laser beam reflected from the melting pool, and protecting the processing head 8 and its peripheral driving portion. The protective plate 18 may have a flat plate shape or any other shape, and the size thereof is sufficient to sufficiently protect the processing head 8 and its attached equipment.

  Further, although fume is generated in laser welding, the amount of generated fume is particularly large in long-time welding. Therefore, the protective plate 18 also has a role of suppressing fume diffusion and assisting suction of the fume. Since the shield gas nozzle 6 is attached closer to the laser irradiation part than the protective plate 18 and is affected by reflected light and radiant heat, it has a water cooling structure.

  The fume 9 in the groove and in the vicinity of the weld is sucked by the fume suction nozzle 19. A laser cleaning head 20 for cleaning the laminated weld metal surface and groove wall surface is attached to the rear portion of the fume suction nozzle 19. The laser cleaning head 20 has a movable joint structure capable of moving in the height direction, front and rear, left and right directions, and is configured to sufficiently clean the groove surface to which the fume adheres. The laser cleaning head 20 is connected to a pulse laser oscillator 23 through a fiber, and the laser cleaning head 20 irradiates a pulsed laser beam into the groove, and adheres to the laminated weld metal and the surrounding groove wall surface. The welding product by the fume 9 is removed.

  By combining the suction of the fume by the fume suction nozzle 19 and the irradiation cleaning of the pulse laser from the laser cleaning head 20, the welded product by the fumes adhering to the laminated weld metal and the surrounding groove wall surface is almost completely obtained. Can be removed. Most welding products can be removed by either fume suction or cleaning by pulsed laser irradiation, but in order to obtain welds free from welding defects such as poor fusion and porosity, a combination of both is used. Is most effective.

  The laser oscillator 12, the wire feed control device 17, the gas flow rate control device 15, the positioner 21 for controlling rotation of the workpieces 1a and 1b, the pulse laser oscillator 23, and the fume suction device 35 are connected to the welding control device 22. Welding is performed by controlling welding conditions such as laser output, welding speed and wire feed speed, operation timing, and the like.

  The cylindrical workpieces 1a and 1b shown in FIG. 2 were butt welded by the welding apparatus of Example 1. The cylindrical workpieces 1a and 1b are austenitic stainless steel SUS316L having a diameter of about 6 m and a plate thickness of 50 mm. This cylindrical object is placed on a welding positioner (not shown) so that it can perform circumferential welding while rotating. Welding was performed from both sides in a horizontal posture.

  FIG. 4 shows a cross-sectional shape of the weld groove formed in the butt portion 24. The welding groove is formed by abutting the materials to be welded 1a and 1b. At the center of the welding groove, a root face 25 is formed by combining the surfaces of the welded materials, and groove grooves 26 are formed on both sides thereof. The length L of the root face 25 was 15 mm. This is the length that the butt face of the root face 25 can be welded from both sides and completely melted by the laser output used in the first embodiment. The groove groove portion 26 other than the root face 25 is a narrow groove having a groove bottom width W of 3 mm and a groove angle θ of 4 °. The bottom width W of the groove is the distance between the intersections of the extension lines on both sides of the groove and the extension lines of the groove bottom. In addition, the edge part of a groove bottom face has a curvature.

  In FIG. 1, only one set of welding apparatus is shown, but the equipment having the same configuration is also installed on the opposite surface of the cylindrical object, and the laser beam output from the laser oscillator 12 is switched to change the surface. Welding was alternately performed from the direction and the back surface direction. Since the material to be welded in Example 1 is a cylindrical object, the upper side in FIG. 4 is the outer side of the cylindrical object, and the lower side in FIG. 4 is the inner side.

  As the laser oscillator, a disk laser device that oscillates laser light having a wavelength of 1030 nm was used. In the case of a laser having a long oscillation wavelength, such as a CO2 laser, the welding apparatus becomes large in size, and since plasma is easily generated, defects are likely to occur in the welded portion, so that the equipment can be downsized and high-quality welding is possible. It is preferable to use a laser having a wavelength capable of fiber transmission of about 1 μm, such as a YAG laser, a semiconductor laser, a fiber laser, or a disk laser, which can easily obtain a part.

  Further, the welding wire feeding device 16 may be provided with a heating means by resistance heating or the like, and a facility for feeding the heated welding wire.

  In the welding, after assembling the groove into the shape shown in FIG. 3, the laser beam 4 focused on the center of the bottom of the groove groove portion 26 is irradiated from the outside, and the long and thin shape penetration as shown in FIG. 27 and melt-bond approximately 60% to 70% of the bonded face of the root face 25, then from the inside of the opposite side to the root face 25 in a similar manner to 60% to 70% of the root face length L. % Of the long and long shaped penetration 27, the penetration bead formed from the outside and the penetration bead formed from the inside are wrapped around the center of the root face 25, and the butted portion of the root face 25 Are completely melt bonded. After welding the root face 25, the welding wire 3 is fed into the narrow groove, the wire is melted with the laser beam 4, and the groove is filled with the laminated weld metal 28, so that the materials to be welded are melt-bonded.

  The welding of the groove portion is performed by repeating the lamination of the laminated weld metal 28 formed by melting the welding wire 3 and the material to be welded, and finally a welded portion as shown in FIG. 4 is formed. This lamination is performed by alternately repeating the lamination welding of the outer groove groove and the inner groove groove, and after the lamination of one of the groove grooves is completed, the other groove groove Laminate welding may be performed, but it is preferable to alternately perform inner and outer laminate welding in terms of welding deformation.

  In welding the root face 25 and the groove groove 26, nitrogen gas was used as a shielding gas for protecting the melted portion and the vicinity thereof. As a result of continuous lamination welding using the welding equipment of this example, it was possible to obtain a good weld with no welding defects.

  If the laser welding apparatus of Example 1 is used, there is no damage to the machining head and the drive unit due to the radiant heat and reflected light generated during welding, and the weld metal attached to the weld metal and the groove surface as welding progresses. A laser welding apparatus that can be removed, can be continuously welded for a long time, and a high-quality welded part can be obtained.

  Further, as shown in FIG. 5, a trailer member that supplies a shielding gas following the movement of the machining head between the laser irradiation part of the machining head 8 and the fume suction nozzle 19 in order to suppress oxidation of the weld metal in the high temperature part. 29 may be installed. Since the trailer member 29 is effective not only for suppressing oxidation of the weld metal but also for promoting fume suction, it is possible to reduce weld products adhering to the weld metal surface and the groove wall surface. Since the trailer member 29 is affected by the reflected light of the laser beam and the radiant heat from the welded portion, it is preferable to have a water cooling structure. The trailer member 29 may be a simple plate-shaped guide member that does not supply shield gas. Even in this case, the trailer member 29 can act as a guide member that forms a suction passage for fume.

  FIG. 6 shows a second embodiment of the present invention. In Example 1 shown in FIG. 1, the laser cleaning head 20 is configured as a welding product removing means attached to the weld metal surface and the groove wall surface immediately after the fume suction nozzle 19 for removing the fume. On the other hand, in Example 2, welding which removes the welding product adhering to the surface of the weld metal and the groove wall surface is separated from the welding head portion composed of the processing head 8 to be welded, the shield gas nozzle 6 and the fume suction nozzle 19 and the like. Product removal means are provided.

  In the second embodiment, the weld product removing means is disposed at a position of about 90 degrees with respect to the center of the cylindrical work piece behind the machining head 8. By separating the processing head 8 and the weld product removing means, the weld product removing means has an effect of making it less susceptible to the influence of radiant heat and reflected light from the welded portion. In Example 2, the weld product adhering to the weld metal surface and the groove wall surface is removed by a mechanical physical method using a rotating brush.

  In the welding product removing means, the rotating brush 30 is attached to the brush pressing device 31 and is pressed against the surface of the weld metal and the groove wall surface while rotating, and the welding product is removed. Gas is jetted from the gas spray nozzle 32 to the front surface of the rotary brush 30, and the welded product peeled off by the rotary brush 30 is carried by the gas jetted from the gas spray nozzle 32, and is installed at the rear part of the rotary brush 30. The suction nozzle 33 is sucked and removed.

  The suction nozzle 33 is provided with a suction auxiliary plate 34 that is inserted into the groove to assist the suction of the weld product.

  The rotating brush 30 uses a bundle of a plurality of resin films having slits. In Example 2, although it is the structure which has one welding product removal means adhering to the weld metal surface and a groove wall surface, you may provide multiple this. As a result of continuous lamination welding of the circumference of an austenitic stainless steel SUS304 piping material having a plate thickness of 30 mm and a diameter of 600 mm using the apparatus of this configuration, stable welding is performed without damaging the welding apparatus. A quality weld was obtained.

  Thus, by using the laser welding apparatus of the present invention, continuous lamination welding for a long time is possible in the lamination welding of a welded portion of a large structure having a groove. In addition, a weld with stable welding quality can be obtained.

  In the examples of the present invention, the results were explained by applying to a cylindrical body of austenitic stainless steel, but the welding apparatus of the present invention is not limited to this.

DESCRIPTION OF SYMBOLS 1 ... Material to be welded, 2 ... Groove, 3 ... Welding wire, 4 ... Laser beam, 7 ... Optical system protection cylinder, 8 ... Processing head, 9 ... Fume, 10 ... Reflected light, 11 ... Optical fiber, 12 ... Laser Oscillator 13 ... Melting pool 18 ... Protection plate 19 ... Fume suction nozzle 20 ... Laser cleaning head 22 ... Welding control device 23 ... Pulse laser oscillator 29 ... Trailer member 30 ... Rotating brush 31 ... Brush pressing Device: 32 ... Gas spray nozzle, 33 ... Suction nozzle, 34 ... Suction auxiliary plate, 35 ... Fume suction device, 36 ... Air nozzle

Claims (11)

A processing head having an optical system for condensing laser light and irradiating the welding material with laser light, wire feeding means for feeding a welding wire to the laser light irradiating portion of the welding material, A welded gas joining means for shielding the melted part formed in the welded material by irradiation and the vicinity thereof; and a moving means for moving the working head and the welded material relative to each other. In a laser welding apparatus for irradiating a laser beam to a groove formed on the groove and melting the welding material and the welding wire while feeding a welding wire, and laminating and welding the groove,
The laser welding apparatus includes a suction unit that sucks a weld product generated by welding, a processing head protection unit that protects the processing head from the reflected light of the laser beam and radiant heat of the welded portion, and a weld metal that is laminated and welded A laser welding apparatus having a cleaning means for removing a weld product deposited on the surface of the laser.   2. The laser welding apparatus according to claim 1, further comprising optical system protection means for protecting the optical system of the processing head from a weld product generated from the melted portion.   3. The laser welding apparatus according to claim 1, wherein the welding product includes at least one of fume and spatter.   3. The laser welding apparatus according to claim 1, wherein the weld metal is protected from the atmosphere between the processing head for irradiating the laser beam and the welding product suction means, and suction by the welding product suction means is performed. A laser welding apparatus comprising a trailer member for guiding.   3. The laser welding apparatus according to claim 1, wherein the processing head protection means is installed between the processing head and a material to be welded, and protects the processing head and its accessory device from laser reflected light and welded portion radiant heat. 3. The laser welding apparatus according to claim 1, wherein the laser welding apparatus is made of a plate-like member.   6. The laser welding apparatus according to claim 5, wherein the machining head protection means has a concave curved surface.   7. The laser welding apparatus according to claim 5, wherein the machining head protection means has a shield gas supply means and a water cooling structure.   The laser welding apparatus according to at least one of claims 1 to 7, wherein the cleaning means for removing the weld product deposited on the surface of the weld metal laminated and welded includes pulse laser irradiation means. Laser welding equipment.   8. The laser welding apparatus according to claim 1, wherein the cleaning means for removing the weld product deposited on the surface of the weld metal laminated and welded includes mechanical removal means. Laser welding equipment.   10. The laser welding apparatus according to claim 9, wherein the mechanical removal means of the cleaning means is a rotary brush for removing a weld product accumulated on the surface of the weld metal, a gas spraying means, and a suction of the removed weld product. A laser welding apparatus comprising suction means for performing   8. The laser welding apparatus according to claim 1, wherein the cleaning means for removing the weld product deposited on the surface of the weld metal laminated and welded includes a pulse laser irradiation means and a mechanical removal means. A laser welding apparatus characterized by that.

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