JP5396941B2 - Laser welding method and laser welding apparatus for metal plate - Google Patents

Description

  The present invention relates to a laser welding method and apparatus for a metal plate, and more particularly to a laser welding method and apparatus for a metal plate that suppresses deterioration in welding quality due to spatter generated during welding adhering to a workpiece.

  Laser welding is a welding method in which a laser beam, which is a high-density energy beam, is condensed by an optical component, irradiated to a material to be welded, and the material to be welded is melted. According to laser welding, compared to other welding methods such as arc welding, high-speed welding is possible, and the heat affected range is small.

  Laser welding makes use of such characteristics, and examples of application to member welding such as assembly welding of automobiles and tailored blank welding can be seen. In addition, in a continuous line such as a pickling line or a cold rolling line that continuously treats a metal plate, in order to supply the metal plate to the continuous line without interruption, the rear end surface of the preceding metal plate and the following metal An example applied to a so-called coil joint welding process in which a front end surface of a plate is butt-welded is also seen.

  In an apparatus that welds the end faces to each other as in the coil joint welding process, in order to weld the end face of the preceding workpiece to be welded and the end face of the following workpiece to be welded with high precision, the cutting attached to the welding apparatus as pretreatment The end of the preceding workpiece and the end of the subsequent workpiece are cut by the apparatus. At this time, the end portion that forms the abutting portion may not have a flat surface but may have a minute variation in shape, and burr may occur on the cut end surface. When laser welding is performed in a state in which the shape of the end portion varies or burr is generated, there is a problem that a shape defect such as step welding or hole welding occurs due to a change in the end face butting gap.

  Therefore, by providing a pair of upper and lower shaping rolls between the cutting device and the welding machine and pressing the abutting portion after cutting with the shaping roll, the shape defect in the abutting portion such as burr produced by cutting or variation in cutting shape etc. Can be corrected. Furthermore, it is known that the gap at the time of butting resulting from the limit of cutting accuracy can be reduced, and a uniform and stable weld can be obtained in the welding process. This roll is called a front shaping roll.

  On the other hand, when the plate thickness of the preceding welded material is different from the plate thickness of the subsequent welded material, a step is generated between the welded portion and the base material. In addition, surface unevenness deformation such as bead bulging occurs in the welded portion by the welding process. When the material to be welded is supplied to a continuous line, which is a subsequent process, and undergoes repeated bending in a state in which such a level difference or surface unevenness has occurred, the bending stress acts on the weld and breaks at the weld. There is.

  Therefore, a method is known in which a pair of upper and lower shaping rolls are provided on the downstream side of the welding machine, and the welded portion is pressed with the shaping rolls to correct the step and the surface unevenness deformation. This shaping roll is called a rear shaping roll.

  By the way, in laser welding, since high-density energy is irradiated, the molten metal may be scattered from the molten pool formed with rapid melting of the metal. This may be a problem in securing the quality of the material to be welded. This scattered molten metal is called spatter.

  As described above, spatter adhered to the material to be welded by coil joint welding, for example, is rolled by a rolling roll in the next rolling process. The dents are transferred from the rolling roll to the surface, and the appearance quality of the product is impaired. Moreover, the sputter | spatter adhering to the metal plate surface is pushed into the inside of a metal plate, and becomes a factor of the plate fracture | rupture in subsequent rolling processes. As described above, the spatter adhering to the material to be welded reduces the quality of the material to be welded, so that it is necessary to perform grinding or the like, which becomes an obstacle to production efficiency.

  Patent Documents 1 to 5 are disclosed as countermeasures against such adhesion of spatter generated during welding. Japanese Patent Application Laid-Open No. H10-228561 discloses a spatter adhesion prevention method using a sputter shielding plate and a high-speed airflow. According to this, the spatter is shielded by the shielding plate, and the spatter passing through the light transmission hole in the shielding plate can be blown off by the high-speed air flow. Patent Document 2 discloses that the tip of a laser processing head is a double tubular nozzle and a shielding curtain is formed by an outer nozzle. Patent Document 3 discloses a method in which a gas having a gas pressure of 0.6 to 1.2 times the gas pressure supplied from a center cone is sprayed from a nozzle provided on a side from above an acute angle to scatter sputtering. Has been. According to this, for the spatter scattered from the molten pool, directivity can be given by the side gas flow immediately after detachment, and the amount of spatter entering the laser head can be reduced. In Patent Document 4, in addition to protection by protective glass, by flowing ultrasonic gas into the processing head, and by forming the tip of the processing nozzle into a funnel shape, the ability to suck spatter from the hole at the nozzle tip is improved. It is disclosed that the spatter scattered inside the processing nozzle is efficiently blown off. Patent Document 5 discloses a technique for injecting a fluid from a lateral direction between a laser processing nozzle and a material to be welded for circumferential welding of a pipe.

Japanese Patent Laid-Open No. 6-170577 JP-A-11-123578 Japanese Patent Laid-Open No. 10-328876 JP-A-9-164495 JP 2003-334686 A

  However, in the welding method using a welding apparatus provided with shaping rolls before and after the laser welding machine, even the methods described in Patent Documents 1 to 5 are insufficient in preventing deterioration of the surface quality due to the adhesion of spatter, which is a problem. I understood.

  Therefore, the present invention relates to a laser welding method and a laser welding apparatus for a metal plate, and more specifically, in laser welding by a welding apparatus having shaping rolls in front and rear of a laser welding machine main body, welding by sputtering generated during welding. It is an object of the present invention to provide a laser welding method and a laser welding apparatus for a metal plate that can prevent deterioration in the appearance quality of a material.

As a result of intensive studies, the inventors obtained the following knowledge and completed the invention.
(1) One of the causes of dents that impair the appearance quality is that spatter scattered from the molten pool is caught between the front shaping roll and the workpiece and between the rear shaping roll and the workpiece. . In other words, when spatter is caught between the front shaping roll and the workpiece, or between the rear shaping roll and the workpiece, dents caused by the spattering of the welded material, particularly at the welded portion and its surroundings, are generated. , Impair the appearance quality. Moreover, when a dent flaw is generated on the surface of the shaping roll due to the sputtering, it is transferred to the material to be welded and the appearance quality of the product is impaired. Furthermore, the dents in the material to be welded not only impair the quality of the appearance, but also cause a decrease in the strength of the welded part, causing the welded part to break in the next step.

  (2) Spatter wound between the front shaping roll or the rear shaping roll and the material to be welded, that is, the sputter immediately before being pressed by the shaping roll is fixed to the spatter that is not fixed to the welding material (non-fixed spatter). It is classified into spatter (fixed spatter).

  (3) The sputtering is blown off in the gas injection direction by blowing gas from the lateral direction against the sputtering scattered from the molten pool. As a result, the scattering time until the spatter adheres to the surface of the material to be welded is prolonged, the surface of the spatter is sufficiently cooled, and the spatter is scattered farther away from the molten pool, where the steel plate temperature is lower. Sticking to the plate surface is suppressed. That is, since the number of fixed spatters is greatly reduced, the entanglement of fixed spatters on the shaping roll is suppressed.

  (4) By blowing gas toward the sputter immediately before being wound on the shaping roll, the non-fixed spatter on the surface of the material to be welded is easily blown off, and the non-fixed spatter can be prevented from being caught on the shaping roll.

  (5) When providing a heating means such as an induction heating coil for heating the butted portion of the material to be welded before welding between the front shaping roll and the laser welding machine main body, or between the laser welding machine main body and the rear shaping roll The same applies to a case where a heating means such as an induction heating coil for heating the welded portion is provided therebetween.

  Here, the present invention relates to a metal plate in which end portions of a plurality of metal plates are butted together, a butted portion of the butted metal plates is irradiated with a laser beam, and the butted portions are welded to obtain a weld metal plate having a welded portion. In this laser welding method, gas is injected onto the surface of the metal plate immediately before it is bitten by the front shaping roll that shapes the metal plate front and back surfaces of the butt portion by pressing the butt portion before welding from the vertical direction of the plate thickness. And / or by injecting gas toward the surface of the metal plate immediately before being bitten by the rear shaping roll that shapes the welded portion by pressing the welded portion from the vertical direction of the plate thickness on the metal plate. A laser welding method for a metal plate, wherein welding is performed by irradiating a laser beam while blowing off spatter.

  In the present invention, it is further desirable to inject gas across the molten pool toward the spatter scattered from the molten pool of the metal plate formed by laser beam irradiation.

  Further, the present invention provides a metal plate laser in which end portions of a plurality of metal plates are butted and a laser beam is irradiated to the butted portions of the butted metal plates to weld the butted portions to obtain a weld metal plate having a welded portion. A welding apparatus, comprising: an oscillator that oscillates a laser beam; an optical fiber that transmits a laser beam emitted from the oscillator; and a laser welder main body having an optical system to which the optical fiber is connected, A front shaping roll that shapes the metal plate surface of the abutting portion by pressing the butted portion from the vertical direction of the plate thickness, and / or a rear shaping roll that shapes the welded portion by pressing the welded portion from the vertical direction of the plate thickness. And at least one of the front shaping roll and the rear shaping roll is bitten by the front shaping roll or the rear shaping roll. A laser welding apparatus of the metal plates, characterized in that it comprises a shaping roll gas injection means for injecting a gas toward the surface of the preceding metal plate.

  In the present invention, it is desirable to further have a weld gas injection means for injecting gas across the molten pool toward the spatter scattered from the molten pool of the metal plate formed by laser beam irradiation.

  In these inventions, it is desirable that the shaping roll gas injection means is disposed on each of both sides in the roll width direction of the front shaping roll and / or the rear shaping roll.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the external appearance quality of the to-be-welded material by the sputter | spatter which generate | occur | produces at the time of butt welding of laser welding can be prevented. That is, since the spatter scattered from the molten pool is suppressed from being caught in the shaping roll, it is possible to prevent the occurrence of dents in the material to be welded. Further, along with the suppression of the occurrence of dents, the fracture of the welded portion in the subsequent process is reduced.

It is the figure which showed typically each structure of the welding apparatus concerning 1st embodiment. It is a figure for demonstrating arrangement | positioning of a front gas injection nozzle. It is the figure which showed typically the structure of the welding means of the welding apparatus of FIG. It is the figure which showed typically each structure of the welding apparatus concerning 2nd embodiment. It is the figure which showed typically the structure of the welding means and welding part gas-injection nozzle of the welding apparatus of FIG. It is a figure for demonstrating the other example of arrangement | positioning of the welding part gas injection nozzle. It is a figure for demonstrating the other example of the welding part gas injection nozzle.

  The above-mentioned operation and gain of the present invention will be clarified from the following embodiments for carrying out the invention. Hereinafter, the present invention will be described based on embodiments shown in the drawings. In addition, although the following description illustrates a steel plate as a metal plate, it is not limited to this.

  First, the laser welding apparatus 10 according to the first embodiment will be described. FIG. 1 is an explanatory view schematically showing the configuration of the laser welding apparatus 10 and is a view of the laser welding apparatus 10 viewed from the upstream process side of the production line in a scene where the laser welding apparatus 10 is arranged on the production line. Therefore, the steel plate 1 (the steel plate is only one of the two to be abutted in the drawing) that is the material to be welded shown in FIG. 1 moves on the production line from the front of the paper to the back of the paper. The width direction of the steel plate is the left-right direction of the paper surface, and the butted portion of the steel plate is formed along the width direction. The laser welding apparatus 10 includes a frame 11, a cutting means 12, a pair of upper and lower front shaping rolls 20, a front gas injection nozzle 21 as a shaping roll gas injection means, a laser welding means 30 as a laser welding machine body, and a pair of upper and lower rear shaping. A roll 40 and a rear gas injection nozzle 41 as a shaping roll gas injection means are provided.

  Hereinafter, each configuration will be described with reference to FIG. In each of these components, each of the cutting means 12, the front shaping roll 20, the front gas injection nozzle 21, the laser welding means 30, the rear shaping roll 40 and the rear gas injection nozzle 41 is fixed to the frame 11 and formed integrally. ing.

  The frame 11 is substantially U-shaped having an upper member 11a, a lower member 11b, a standing member 11c, and an opening 11d from the viewpoint shown in FIG. 1, and includes each component on the inside thereof. It is formed to be able to. Therefore, it has predetermined rigidity and strength for holding each component with high accuracy. The frame 11 is movable in a horizontal direction (arrow Y in the figure) substantially orthogonal to the direction in which the steel plate 1 moves. Thereby, each component attached to the frame 11 can be moved just below and directly above the front and back surfaces of the steel plate 1 to act appropriately. The movement of the frame 11 and each operation of the components accompanying this will be described in detail later. The speed of movement is not particularly limited as long as welding described later can be appropriately performed, but is usually about 1.0 m / min to 15 m / min.

  Further, the cutting means 12, the front shaping roll 20, the front gas injection nozzle 21, the laser welding means 30, the rear shaping roll 40, and the rear gas injection nozzle 41, which are the above-described components of the laser welding apparatus 10, move the frame 11. They are arranged along the track parallel to the track. In the present embodiment, the frame 11 has a U-shape, but is not limited to this as long as the movement of the steel plate 1 and the appropriate operation of each component are ensured.

  The cutting means 12 is a means for cutting and aligning the ends of two steel plates that are arranged in the frame 11 and in the vicinity of the standing member 11c. Normally, the longitudinal end of the steel plate is a free end in rolling, so that it is necessary to cut the steel plate with high precision so that a large gap does not occur when the two steel plate ends are butted together. Therefore, the cutting means 12 is for that purpose. Therefore, the type of the cutting means 12 is not particularly limited, and a normal cutting means used for manufacturing a steel plate can be applied.

  The basic structures of the front shaping roll 20 and the rear shaping roll 40 are the same. As shown in FIG. 1, the front shaping roll 20 includes an upper front shaping roll 20a and a lower front shaping roll 20b, and the rear shaping roll 40 is an upper part. A rear shaping roll 40a and a lower rear shaping roll 40b are provided. Furthermore, the upper front shaping roll 20a and the upper rear shaping roll 40a are provided with a cylinder (not shown) that drives them in the vertical direction. The upper front shaping roll 20a and the lower front shaping roll 20b are arranged up and down, and similarly, the upper rear shaping roll 40a and the lower rear shaping roll 40b are arranged up and down. The upper front shaping roll 20a and the upper rear shaping roll 40a are arranged on a straight line in the Y direction. Similarly, the lower front shaping roll 20b and the lower rear shaping roll 40b are also arranged in a straight line in the Y direction. Has been placed. The vertical distance between the upper front shaping roll 20a and the lower front shaping roll 20b can be adjusted by the cylinder, and similarly, the vertical distance between the upper rear shaping roll 40a and the lower rear shaping roll 40b can be adjusted. It is. The front shaping roll 20 (20a, 20b) and the rear shaping roll 40 (40a, 40b) each have a structure that rotates around a support shaft (not shown).

  The front gas injection nozzle 21 and the rear gas injection nozzle 41 function as shaping roll gas injection means, and the basic structure is the same. The front gas injection nozzle 21 is a nozzle having an injection port that blows gas in a predetermined direction on the surface of the material to be welded immediately before being bitten by the upper front shaping roll 20a. On the other hand, the rear gas injection nozzle 41 is a nozzle having an injection port that blows gas in a predetermined direction on the surface of the material to be welded immediately before being bitten by the upper rear shaping roll 40a. Here, the predetermined direction is a direction in which gas is blown by forming an air flow so as to exclude spatter from the steel plate by the blowing. It suffices if the spatter can be removed from the tracks of the upper front shaping roll 20a and the upper rear shaping roll 40a by the air flow. However, it is most preferable to completely exclude spatter from the steel sheet. The kind of nozzle is not particularly limited, and any form of nozzle can be applied. Examples thereof include a flat nozzle having a rectangular injection port and a round tube nozzle made of a circular tube.

  FIG. 2 is a schematic diagram for explaining the attachment of the front gas injection nozzle 21. The broken line A indicates the gas injection direction with the axis of the nozzle, and the range between the dotted lines B indicates the region where the jet flows. 2A is a view seen from the side, FIG. 2B is a view seen from the front, and FIG. 2C is a view seen from above. The same applies to the rear gas injection nozzle 41, and the description thereof is omitted here. In FIG. 2, the lower front shaping roll 20b is omitted.

  As can be seen from FIG. 2, two front gas injection nozzles 21, 21 are provided, and the upper front shaping is performed so that the axis (A, A) of each front gas injection nozzle 21, 21 passes through the vicinity of point D. The roll 20a is installed at both the left and right sides at an inclination angle θ2. Here, the point D means an intersection of a line to be welded with a line perpendicular to the surface of the material to be welded and in contact with the outer periphery of the upper front shaping roll 20a (represented by a dashed line C). Moreover, each front gas injection nozzle 21 and 21 is inclined and provided by inclination-angle (theta) 1 with respect to the advancing direction of a to-be-welded material. The inclination angle θ2 is preferably 45 ° or more and less than 90 °, and the inclination angle θ1 is preferably 30 ° or more and 60 ° or less.

  Here, only the upper front shaping roll 20a and the upper rear shaping roll 40a have been described, but gas is also present on both sides of the lower front shaping roll 20b and the lower rear shaping roll 40b from the viewpoint of removing spatter on the lower surface (back surface) of the steel plate. It is desirable to provide an injection nozzle. Thereby, gas can be injected toward the lower surface (back surface) of the steel plate immediately before biting the steel plate.

  The laser welding means 30 includes a laser oscillator 31, an optical fiber 32, and an optical system 34. A schematic diagram is shown in FIG. The laser oscillator 31 is a device that oscillates a laser serving as a welding heat source. The type of laser used for laser welding by the welding apparatus 30 is not particularly limited as long as it can be transmitted by the optical fiber 32, and it is sufficient that such a laser can be oscillated. Examples thereof include an oscillator such as a YAG laser, a disk laser, and a fiber laser. These are excited by an excitation energy source such as a semiconductor laser to emit laser light. Thus, it is possible to perform welding efficiently by using a laser that can be transmitted through an optical fiber and can obtain a high output. The laser output is not particularly limited, but the effect of the present invention becomes more remarkable as the output is higher.

In the laser oscillator 31, the oscillation medium is preferably a fiber or disk crystal. According to this, since the fiber-like or disk-like crystals can be easily arranged in parallel, for example, a high output of 6 kW or more can be easily obtained.
The optical fiber 32 is means for transmitting a laser from the laser oscillator 31 to the optical system 34. By applying the optical fiber 32, it is possible to provide a laser welding apparatus 10 that can easily transmit a laser and can be easily maintained. The diameter of the optical fiber is not particularly limited, but a fiber having a diameter of 1.0 mm or less is usually used, and the diameter is preferably smaller from the viewpoint of the size and energy density of the condensing optical system, and is 0.6 mm or less. It is preferable. More preferably, it is 0.2 mm or less.

  The optical system 34 is connected to the output end 33 of the optical fiber, is a means for introducing the transmitted laser, controlling the laser to be suitable for welding, and emitting it to the welded portion. The optical system 34 includes a collimating lens 35 and a condensing lens 36, and the focal diameter is determined by the above-described diameter of the optical fiber 32 and the ratio of the focal lengths of both the lenses 35 and 36. For example, when the fiber diameter is Dfiber, the focal length of the collimating lens is F1, and the focal length of the condenser lens is F2, the spot diameter Ds at the focal position is expressed by Ds = Dfiber · (F2 / F1).

  Next, the laser welding apparatus 110 according to the second embodiment will be described. FIG. 4 is a diagram schematically showing the configuration of the laser welding apparatus 110. The laser welding apparatus 110 includes a frame 11, a cutting means 12, a pair of upper and lower front shaping rolls 20, a front gas injection nozzle 21 as a shaping roll gas injection means, a laser welding means 30, a pair of upper and lower rear shaping rolls 40, and a shaping roll gas. A rear gas injection nozzle 41 as an injection unit and a welded part gas injection nozzle 117 as a welded part gas injection unit are provided. In the following description, the configuration other than the welded part gas injection nozzle 117 is the same as that of the first embodiment and is omitted.

  The welded part gas injection nozzle 117 is a normal nozzle having a so-called injection port, and is capable of injecting gas in a predetermined direction from the injection port. Here, the type of nozzle is not particularly limited, and any form of nozzle can be applied. Examples thereof include a flat nozzle having a rectangular injection port and a round tube nozzle made of a circular tube.

  FIG. 5 shows a diagram for explaining the arrangement of the weld gas injection nozzle 117 and the like. As can be seen from FIG. 5, the weld gas injection nozzle 117 is disposed in the vicinity of the laser welding means 30. A broken line indicated by a symbol P in FIG. 5 indicates an axis in the gas injection direction of the welded portion gas injection nozzle 117, and a range surrounded by a dotted line indicated by a symbol Q indicates a region where the jet flows. Reference sign Pk indicates an extension line along the lower end of the injection port of the welded part gas injection nozzle 117 and substantially coincides with the lower end of the region where the jet flow indicated by reference sign Q. Moreover, the site | part shown with the code | symbol R is a site | part in which the molten pool R in the steel plate 1 which is a to-be-welded material is formed. As described above, the welding apparatus 110 is configured such that the axis P of the weld gas injection nozzle 117 and the extension line Pk pass right above the molten pool R, and the axis P and the extension line Pk are It is substantially parallel to the upper surface.

  The axis P and the extension line Pk do not necessarily need to coincide with the welding direction, but it is preferable that the axis P and the extension line Pk coincide with the welding direction in order to prevent spatter adhesion more efficiently. Further, in addition to the case where the extension line Pk is arranged so as to be parallel to the upper surface of the steel plate 1 as in the welding part gas injection nozzle 117 shown in FIG. 5, the welding part gas injection nozzle 117 ′, extension line is shown in FIG. 6. You may arrange | position as shown by P'k or welding part gas injection nozzle 117 '', and extension line P''k. That is, the extension gas P′k of the welded part gas injection nozzle 117 ′ is inclined θ ′ upward with respect to the extension line Pk, and the extension gas P ″ k of the welded part gas injection nozzle 117 ″ extends to the extension line Pk. It is arranged so as to incline θ ″ downward. Here, the magnitudes of θ ′ and θ ″ are not particularly limited, but both θ ′ and θ ″ are preferably 0 ° to 30 ° from the viewpoint of the arrangement of the injection nozzles, and particularly θ ′. More preferably, 'is 0 to 20 degrees.

  The width of the welded portion gas injection nozzle 117 (the width of the injection port in the direction orthogonal to the welding progress direction and the plate thickness direction of the steel plate) is the width of the molten pool R at the surface position of the steel plate 1 so as to cover the molten pool R. 1 times or more. Preferably it is 3 times or more. The thickness of the injection nozzle (the size of the injection port perpendicular to the width) is appropriately set depending on the injection flow rate and the injection pressure.

  The height direction of the welded part gas injection nozzle 117 (the vertical direction in FIG. 5 and FIG. 6) is extended lines Pk, P′k, P along the lower end of the injection port of the welded part gas injection nozzle 117 as will be described later. It is preferable that the vertical distance between ″ k and the molten pool R (the distance indicated by S in FIGS. 5 and 6) be adjusted to 3 mm or less.

  FIG. 7 is a view for explaining a welded part gas injection nozzle 127 which is a shape example of the welded part gas injection nozzle, and FIG. 7A is a view of the welded part gas injection nozzle 127 as seen from the injection port side. 7 (b) is a view as seen from the upper surface side in a posture in which the weld gas injection nozzle 127 is attached to the welding apparatus, and schematically shows an axis and a jet flow. As can be seen from FIG. 7, the welded part gas injection nozzle 127 is characterized in that the base part 127a has two parallel injection holes 127b and 127c. Therefore, the weld gas injection nozzle 127 can emit two jets Q2 and Q3 having two axes P2 and P3. Here, the welding portion gas injection nozzle 127 is arranged in the welding apparatus so that the injection ports 127b and 127c are at the same height position from the surface of the material to be welded. Moreover, it installs so that P4 which is an intermediate line of two axial lines P2 and P3 may pass just above a fusion | melting part. Also in this case, it is preferable that the vertical distance between the extension line along the lower ends of the injection ports 127b and 127c of the welded portion gas injection nozzle 127 and the molten pool is adjusted to be 3 mm or less.

  In FIG. 7A, if the interval inside the injection port indicated by Li becomes too narrow with respect to the molten pool width, the injection speed immediately above the molten pool increases, and the molten metal flows out of the molten pool and the spatter increases. On the contrary, if the width is larger than the molten pool width, the spatter scattered from the molten pool cannot be blown off, and therefore it is preferably 0.5 times or more and 1 time or less with respect to the molten pool width. Moreover, the space | interval of the outer side of the injection nozzle shown by Lo is 1 time or more of a molten pool width, Preferably it is 3 times or more so that a molten pool can be covered.

  Next, the welding method of the present invention will be described. For ease of understanding, here, welding using the above-described welding apparatuses 10 and 110 will be described. However, the welding method of the present invention is not limited to this, and any apparatus that exhibits the effects of the present invention can be used. Can be used.

  The welding method M1 according to the first embodiment is performed, for example, by welding using the welding apparatus 10 according to the first embodiment. That is, in the welding method M1, when the welded steel sheet 1 is irradiated with a laser beam and welded, the front gas injection nozzle 21 applies gas to the surface of the material to be welded immediately before being bitten by the upper front shaping roll 20a. Spray in a predetermined direction. On the other hand, the rear gas injection nozzle 41 blows gas in a predetermined direction on the surface of the material to be welded immediately before being bitten by the upper rear shaping roll 40a. Here, the predetermined direction is a direction in which gas is blown by forming an air flow so as to exclude spatter from the steel plate by the blowing. It suffices if the spatter can be removed from the tracks of the upper front shaping roll 20a and the upper rear shaping roll 40a by the air flow. However, it is most preferable to completely exclude spatter from the steel sheet. Thereby, the sputter | spatter biting into the upper front shaping roll 20a and the upper rear shaping roll 40a is suppressed, and generation | occurrence | production of the dent flaw of a to-be-welded material is suppressed.

  The range in which the gas is blown is desirably a range including the hatched area indicated by E in FIG. That is, the hatched area E is about one time the roll diameter L from the center line of the upper front shaping roll 20a in the welding direction toward the front of the welding (the direction indicated by F in FIG. 2C). In the perpendicular direction (the direction indicated by G in FIG. 2C), it is desirable to set the roll center at the center and about three times the roll width W. Further, it is desirable that the inclination angle θ1 is 30 ° to 60 ° and the inclination angle θ2 is 45 ° to 90 °.

  Although the kind of gas to spray is not specifically limited, Compressed air, an inert gas, etc. can be used. The conditions for spraying are preferably, for example, compressed air, a pressure of 0.3 MPa to 0.7 MPa, and a flow rate of 100 L / min to 300 L / min. In addition, although the said description is a case where both the upper front shaping roll 20a and the upper rear shaping roll 40a are provided and both the front gas injection nozzle 21 and the back gas injection nozzle 41 are used, it is not necessarily limited to this form. is not. Either one is acceptable.

  Here, only the upper front shaping roll 20a and the upper rear shaping roll 40a have been described. However, from the viewpoint of removing spatter on the lower surface (back surface) of the steel plate, the lower front shaping roll 20b and the lower rear shaping roll 40b are also provided on both sides. It is desirable to provide a gas injection nozzle and inject gas toward the lower surface (back surface) of the steel plate just before biting the steel plate.

  The welding method M2 which concerns on 2nd embodiment is performed using the welding apparatus 110 which concerns on 2nd embodiment, for example. That is, in the welding method M2, in addition to the welding method M1, gas is injected across the molten pool R toward the spatter scattered from the molten pool R formed by laser beam irradiation. For example, it is desirable that the vertical distance (S in FIGS. 5 and 6) between the extension line Pk along the lower end of the injection port of the weld gas injection nozzle 117 and the weld pool R is within 3 mm. Thereby, the molten metal scattered as spatter is blown off in the direction of the jet. As a result, the scattering time until the spatter adheres to the surface of the material to be welded is prolonged, and the surface of the sputter is sufficiently cooled. Moreover, since it scatters to the part where the steel plate temperature is further away from the molten pool R, the sticking to the steel plate surface is suppressed. That is, since the number of fixed spatters is greatly reduced, the entanglement of fixed spatters on the shaping roll is suppressed. The jet is preferably substantially horizontal with respect to the upper surface of the molten pool R, but is not limited thereto, and may have an angle in a direction away from or closer to the upper surface of the molten pool. . When the jet is blown to the molten pool, the molten metal flows out and spatter increases, so when the rear shaping roll 40 is provided, the sputter blown by the jet collides with the rear shaping roll 40, Since it is caught in a roll and a welding material, in order to prevent this, it is desirable that the gas injection direction is the front in the welding direction.

  In addition, although steel material was demonstrated to the example as a to-be-welded material so far, it is not limited to this, It can apply also to plate materials of other metals, such as stainless steel, titanium, and aluminum.

  Next, the embodiment will be described in more detail. However, the present invention is not limited to this embodiment.

  In the examples, using a laser welding apparatus having the basic configuration shown in FIG. 4, butt welding of steel sheets was performed under various conditions, and the sputter adhesion state at that time was evaluated.

<Conditions>
The common conditions in each example are as follows.
-Test steel plate (test metal plate): low carbon steel (C: 0.02 mass%), plate thickness 6.0 mm
・ Welding length: 1250mm
・ Laser oscillator: Fiber laser oscillator, output 10kW
-Collimating lens: Focal length 125mm
・ Condenser lens: focal length 200mm
・ Spot condition: Defocus amount 5mm
・ Welding speed: 3.4 m / min

  Here, as the front gas injection nozzle 21 and the rear gas injection nozzle 41, round tube nozzles having an inner diameter of 4 mm and an outer diameter of 6 mm were used. The inclination angle was set so that θ1 in FIG. 2 was 45 ° and θ2 was 45 °, and compressed air of 0.5 MPa was injected at an injection amount of 100 L / min.

  The injection nozzle is the welded part gas injection nozzle 127 shown in FIG. 7, and two round tubes having an inner diameter of 4 mm and an outer diameter of 6 mm are adjacent to each other in the horizontal direction. The nozzle tip position was arranged so as to be 12 mm away from the laser beam path. The distance between the extension line of the lower end of the injection nozzle and the molten pool was 2 mm, and 0.5 MPa of compressed air was injected at an injection amount of 100 L / min so that the jet flow crossed directly above the molten pool. Note that if the injection speed directly above the molten pool is large, molten metal flows out of the molten pool and spatter increases, but by using this nozzle adjacent to the round tube, the velocity distribution at the center is slow in the cross section of the jet. Therefore, it is possible to suppress spatter scattering from the molten pool.

<Evaluation>
Welding was evaluated by the number of times welding was performed 10 times and spatter was pushed into the material to be welded. The number of times of pressing was evaluated with 4 levels of “◎” for 0 times, “◯” for 1 to 2 times, “△” for 3 to 5 times, and “×” for 6 to 10 times. “Especially good”, “good”, “good”, “bad”. The results are shown in Table 1.

  As can be seen from Table 1, in all of the welding examples of the present invention, the number of spatter adhesions to the material to be welded can be suppressed to a small value, which is “OK” or higher. When either the front gas injection nozzle or the rear gas injection nozzle was used, it was “OK”, when both were used, it was “good”, and when the injection nozzle was used, it was “particularly good”.

  While the invention has been described in connection with embodiments that are presently practical and preferred, the invention is not limited to the embodiments disclosed herein, As long as the scope and the gist or idea of the invention that can be read from the entire specification are not violated, the laser welding method and its apparatus accompanying such changes are also included in the technical scope of the present invention. Must be understood.

DESCRIPTION OF SYMBOLS 10 Laser welding apparatus 20 Front shaping roll 20a Upper front shaping roll 20b Lower front shaping roll 21 Front gas injection nozzle (shaping roll gas injection means)
30 welding means 40 rear shaping roll 40a upper rear shaping roll 40b lower rear shaping roll 41 rear gas injection nozzle (shaped roll gas injection means)
DESCRIPTION OF SYMBOLS 110 Laser welding apparatus 117 Welding part gas injection nozzle (welding part gas injection means)

Claims (5)

This is a metal plate laser welding method in which end portions of a plurality of metal plates are butted against each other, and a laser beam is irradiated to the butted portions of the butted metal plates to weld the butted portions to obtain a weld metal plate having a welded portion. And
The gas on the surface of the metal plate just before biting the front shaping rolls to shape the metal plate front and rear surfaces of the butted portion is injected by the butt pressing part from a thickness in the vertical direction before welding, and by injecting gas toward the surface of the metal plate just before biting the rear shaping roll for shaping the welded portion by pressing the welded portion after welding from a thickness in the vertical direction, on the metal plate A laser welding method for a metal plate, wherein welding is performed by irradiating a laser beam while blowing off spatter.   Furthermore, the laser welding method of the metal plate of Claim 1 which injects gas across the said molten pool toward the spatter which scatters from the molten pool of the said metal plate formed by irradiation of the said laser beam. A metal plate laser welding apparatus that abuts end portions of a plurality of metal plates, irradiates the butted portions of the abutted metal plates with a laser beam and welds the abutted portions to obtain a weld metal plate having a welded portion. And
An oscillator that oscillates a laser beam, an optical fiber that transmits a laser beam emitted from the oscillator, and a laser welder body having an optical system to which the optical fiber is connected,
Front shaping rolls to shape the metal sheet surface of the abutting portion by pressing the butted portion from a thickness in the vertical direction, the welded portion by pressing the and front Symbol weld from a thickness in the vertical direction A rear shaping roll for shaping,
Further, the front shaping rolls, and the said rear shaping roll, each said front shaping rolls, the shaping rolls gas injection means for injecting a gas toward the surface of the metal plate just before biting before Symbol rear shaping rolls A laser welding apparatus for a metal plate, comprising:   4. The metal plate according to claim 3, further comprising a weld gas injection unit that injects gas across the molten pool toward the spatter scattered from the molten pool of the metal plate formed by irradiation of the laser beam. Laser welding equipment. The shaping rolls gas injecting means, said front shaping rolls, and before Symbol laser welding apparatus of metal plates according to claim 3 or 4 is disposed in each of both sides of the roll width direction of the rear shaping rolls.

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