JP5245972B2 - Laser welding method and laser welding apparatus - Google Patents

Description

  The present invention relates to a laser welding method and a laser welding apparatus, and more particularly to a laser welding method and a laser welding apparatus using a hot wire as an auxiliary heat source.

  The laser welding method has a high energy density, a deep penetration can be obtained with a small amount of heat input, has little welding distortion, and enables high-precision welding.

  Conventionally, the laser welding method has been carried out by butt welding without using filler metal, and the target is usually welding of small precision parts or welding of thin plates.

  On the other hand, by applying laser welding to steel structures, high precision welding and improvement in welding work efficiency can be expected. In recent years, hybrid welding methods combining laser welding and TIG welding or MIG welding have been implemented. Has been.

  In the hybrid welding method, the filler metal is melted by an arc of TIG welding or MIG welding, and an appropriate bead that cannot be obtained by laser welding can be formed.

  However, in the hybrid welding method, it is necessary to provide two types of welding devices, ie, a laser welding device and a TIG welding device, or an MIG welding device, so that the device becomes a large-scale and expensive welding device. Furthermore, in the hybrid welding method, the heat input by the arc can be kept low, but by making it low, the generation of the arc is easily affected by the surface condition of the welding material, and the ground treatment applied to the surface of the welding material is completely completed. If not removed, there was a problem that the arc was not stable and the welding became unstable.

Special table 2004-512965 gazette JP 2003-320454 A

  In view of such circumstances, the present invention can be implemented with an inexpensive apparatus, and a suitable bead corresponding to the welding situation can be obtained, and a laser welding method and a laser welding capable of adjusting the bead width and bead height. A device is provided.

  The present invention provides a laser welding method for irradiating a welding site with a laser and supplying a heated filler wire, irradiating the laser in a defocused state, and at the same time, energy density average value / energy density maximum in a laser beam cross section. The present invention relates to a laser welding method in which the defocus state is set so that the value becomes a predetermined value.

  The present invention also relates to a laser welding method in which the average energy density value / maximum energy density value is set based on the required width or height of the bead.

  Furthermore, the present invention provides a welding torch for condensing and irradiating a laser on a welding member, a filler wire supply device for supplying a heated filler wire to a laser irradiation portion, and a condensing position changing means for changing a defocus state. And a control unit that controls the defocusing state of the converging position changing means so that the average energy density value / the maximum energy density value becomes a predetermined value.

  According to the present invention, in a laser welding method of irradiating a laser beam to a welding site and supplying a heated filler wire, the laser beam is irradiated in a defocused state, and an energy density average value / energy in a laser beam cross section is obtained. Since the defocus state is set so that the maximum density value becomes a predetermined value, it is possible to control the bead shape by simple adjustment, and since the filler wire is not melted by the arc, welding is stable and welding quality is improved. improves.

  Further, according to the present invention, the average energy density value / maximum energy density value is set based on the required width or height of the bead, so that the desired bead shape can be easily obtained.

  Furthermore, according to the present invention, a welding torch for condensing and irradiating a laser to a welding member, a filler wire supply device for supplying a heated filler wire to a laser irradiation portion, and a condensing position for changing a defocus state The bead shape can be easily controlled by including the changing means and a control unit that controls the defocus state of the condensing position changing means so that the average energy density value / maximum energy density value becomes a predetermined value. In addition, since the filler wire is not melted by arc, the welding is stable and the welding quality is improved.

It is the schematic which shows the laser welding apparatus by which this invention is implemented. In this laser welding apparatus, it is a diagram which shows the change of a weld metal cross-sectional area at the time of changing a defocus ratio. It is explanatory drawing which shows the state of a weld metal. It is explanatory drawing which shows the state of the defocus with respect to a welding member. It is a diagram which shows the relationship between the shape of a bead and the energy density of a bead.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, referring to FIG. 1, an example of a laser welding apparatus 1 in which the present invention is implemented will be described. In the figure, 2 is a welding torch, and 3 is a filler wire supply device. The laser used in this embodiment is a fiber laser, and a deep penetration depth is obtained.

  A laser emitted from a laser light source (not shown) is guided to the welding torch 2 by an optical fiber 4. The welding torch 2 incorporates a condensing optical system 5, and the laser 6 emitted from the optical fiber 4 is condensed at a required position of the welding member 7 by the condensing optical system 5. In FIG. 1, f is the focal length of the condensing optical system 5.

  The filler wire supply device 3 includes a wire drum 8, a wire straightening machine 9, a wire holder 11, etc., and the filler wire 12 sent out from the wire drum 8 has its curl corrected by the wire straightening machine 9 and the wire holder 11 is sent out.

  The wire holder 11 serves as a power supply unit for the filler wire 12, and a heating current is supplied to the filler wire 12 by the power supply unit 13 between the wire holder 11 and the welding member 7. By supplying current to the filler wire 12, the filler wire 12 is heated by Joule heat. The filler wire 12 delivered from the wire holder 11 is supplied to the irradiation unit of the laser 6.

  In addition, it is preferable that the heating temperature of the said filler wire 12 is heated to such an extent that it melt | melts when the front-end | tip of this filler wire 12 contacts a molten pool.

  Also, the wire supply speed of the filler wire supply device 3, the output of the laser 6, the moving speed of the welding torch 2 (welding speed), the power supply state (heating state) to the filler wire 12 and the adjustment of the focal position are controlled. It is controlled by the unit 10.

  The present inventor, when performing welding in the laser welding apparatus 1, determines the position of the focal point (defocus amount) from the surface of the welding member 7 and the formed bead width or penetration depth. The relationship was verified.

The welding conditions are a laser power of 3 kW, a current value supplied to the filler wire 12 of 50 A, and a welding speed of 1 m / s. Also, the vertical axis of the graph shown in FIG. 2 is the cross-sectional area mm ² of the weld metal, curve A shows the cross-sectional area of the deposited metal, curve B shows the cross-sectional area of the molten metal (see FIG. 3), and the horizontal axis shows the cross-sectional area. The focus ratio (defocus amount / focus: Df / f) is shown. Further,-in (Df / f) is a direction away from the surface of the welding member 7, and + in (Df / f) is a direction moving toward the inside of the welding member 7 (see FIG. 4).

  First, the relationship between the molten state on the base material side, that is, the cross-sectional area of the molten metal B and the defocus ratio, as seen in the curve B, is when the defocus ratio = 0, that is, the focus of the laser 6 is the welding member. 7 is the maximum and maximum when matching the surface, and decreases as the defocus ratio increases on the + and − sides. That is, the penetration amount decreases as the defocus ratio increases. This is because as the defocus ratio increases, the beam cross section increases and the energy density decreases.

  Next, the state of the weld metal, that is, the relationship between the cross-sectional area of the weld metal A and the defocus ratio is shown by a curve A. The cross-sectional area of the weld metal A is minimum and minimum when the defocus ratio is +0.2, and the defocus ratio is shifted from 0 to the + side.

  Further, as seen in the curve A, the weld metal A increases as it departs from the defocus ratio when the defocus ratio is a minimum value, and the defocus ratio becomes maximum at −0.2 and +0.4. If it separates, it will turn to decrease, and if it exceeds -0.3 and +0.4, welding will become impossible.

  Although not shown, the state of the weld metal changes by increasing or decreasing the current supplied to the filler wire 12.

  When the supply current to the filler wire 12 is increased / decreased, the influence of the weld metal A appears largely while maintaining the tendency of FIG. 2, and when the current is increased, the curve A moves in a direction in which the cross-sectional area increases. . When the current is decreased, the curve A moves in a direction in which the cross-sectional area decreases.

  Thus, by controlling the defocus ratio and the supply current to the filler wire 12, the welding state, that is, the penetration depth, the bead width, and the bead leg length can be controlled. In particular, even when the heat input is constant, controlling the defocusing state can control the welding state and bead forming state, such as increasing the build-up metal or increasing the penetration depth. can do.

  For example, when performing fillet welding, a large amount of deposited metal is required, so that the defocus ratio is increased, and if necessary, the power supplied to the filler wire 12 is increased for welding. In addition, when performing butt welding with an I-type groove, since a penetration depth is required, welding is performed in the vicinity of a defocus ratio (Df / f) = 0 or a defocus ratio = 0. is there.

  Next, when the laser 6 is defocused, the energy density at the center of the light beam is high and the energy density at the periphery is low. Therefore, when defocusing is performed, the beam diameter is increased and the energy density distribution is made non-uniform.

  The inventor of the present invention pays attention to such a phenomenon, and proposes to obtain the correlation between the energy density and the bead shape and control the welding state or the bead forming state by using the energy density as a factor.

FIG. 5 shows the energy density on the horizontal axis and the bead shape (bead width, bead height) on the vertical axis. As an index for evaluating the energy density, the energy density average value (E _ave ) / energy density maximum value (E _peak ) at the cross section of the laser beam was used. For example, (E _ave ) / (E _peak ) = 1 has a maximum value with no maximum value.

  Further, as welding conditions for obtaining FIG. 5, the amount of heat input was constant, and the laser power, the energization amount to the filler wire 12, the supply amount of the filler wire 12, and the welding speed were constant.

  In FIG. 5, a straight line C indicated by a plot ▽ indicates the width of the formed bead, and a straight line D indicated by a plot Δ indicates the height of the formed bead.

The straight line C increases in proportion to the increase in the value of (E _ave ) / (E _peak ), and the straight line D decreases in inverse proportion to the increase in the value of (E _ave ) / (E _peak ). ing.

Note that the value of (E _ave ) / (E _peak ), the width of the bead, and the height of the bead when defocused are calculated based on the data shown in FIG.

As shown in FIG. 5, the value of (E _ave ) / (E _peak ) and the width of the formed bead and the height of the bead are in a linear relationship, and the value of (E _ave ) / (E _peak ) Is a suitable factor for controlling bead formation.

Using the relationship between (E _ave ) / (E _peak ) in FIG. 5 and the bead width and bead height, for example, when the bead height is 1 mm, the bead width is approximately 5 mm. The shape can be easily set.

Next, when the laser welding method is applied to the laser welding apparatus 1 described above, the laser power, the welding speed, the amount of power supplied to the filler wire 12 and the like are fixed to predetermined conditions as shown in FIG. _ave ) / (E _peak ) -bead shape is obtained and set and input to the control unit 10.

When performing welding, the control unit 10 sets (E _ave ) / (E _peak ) based on FIG. 5 in consideration of welding conditions such as fillet welding, butt welding, and plate thickness. .

The controller 10 calculates or selects an optimum defocus ratio corresponding to the set (E _ave ) / (E _peak ), and _{moves the} welding torch 2 up and down so that the calculated or selected defocus ratio is obtained. Displace and set the defocus ratio and perform welding.

Further, the gradients of the straight lines C and D shown in FIG. 5 are changed by changing the laser power, the welding speed, and the supply speed of the filler wire 12. Therefore, for example, if a plurality of straight lines Cn and Dn are obtained when the laser power is changed using the laser power as a parameter, a variety of bead shapes corresponding to (E _ave ) / (E _peak ) can be obtained. Welding conditions are obtained.

  When the welding is performed, the filler wire 12 is not melted by the arc, so that the welding state is stable and high quality welding is possible.

  In the above embodiment, the focal position is changed by moving the welding torch 2 up and down as the condensing position changing means, but the condensing position changing means changes the focal length by changing the focal length. Optical condensing position changing means may be used.

  In the above embodiment, the fiber laser has been described. Needless to say, the present invention can also be implemented when an LD laser, a YAG laser, a CO2 laser, or the like is used.

DESCRIPTION OF SYMBOLS 1 Laser welding apparatus 2 Welding torch 3 Filler wire supply apparatus 4 Optical fiber 5 Condensing optical system 6 Laser 7 Welding member 8 Wire drum 9 Wire straightening machine 10 Control part 11 Wire holder 12 Filler wire 13 Power supply part

Claims (3)

  In a laser welding method of irradiating a laser beam to a welding site and supplying a heated filler wire, the laser beam is irradiated in a defocused state, and an energy density average value / energy density maximum value in a laser beam cross section is a predetermined value. A laser welding method, wherein a defocus state is set so as to be a value.   2. The laser welding method according to claim 1, wherein the average energy density value / maximum energy density value is set based on a width or height of a bead to be obtained.   A welding torch for condensing and irradiating a laser to a welding member, a filler wire supply device for supplying a heated filler wire to a laser irradiation portion, a condensing position changing means for changing a defocus state, and an energy density average value A laser welding apparatus comprising: a control unit that controls a defocus state of the condensing position changing means so that a maximum energy density value becomes a predetermined value.

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