JP2005081403A - Laser beam welding equipment and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method in which timing for performing laser irradiation and feeding a welding wire to a weld zone is controlled in the manner suppressing a possibility of generation of weld defects. <P>SOLUTION: The laser welding equipment is provided with an irradiation head 2 for emitting a laser beam 12 to a weld zone of a workpiece 10 and a welding wire feeding device 4 for feeding a welding wire 11 to the weld zone. In this equipment, after a voltage is preliminarily applied from the power source 13 to the welding wire 11, the welding wire 11 is fed until coming into contact with the workpiece 10. An electric current passed to the wiring 14 by this contact is detected with a relay 15. Thereafter, emission of the laser beam 12 from a laser oscillator 1 is started from the irradiation head 2 to the weld zone, so that the timing is obtained in which the welding wire 11 is surely fed to the weld zone at the start of the welding. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laser welding apparatus and a laser welding method, and relates to a technique for controlling the start of laser irradiation in laser welding.

  In welding for workpieces that are prone to high temperature cracking such as austenitic stainless steel, welding is performed with the addition of a filler material in order to make δ ferrite in an appropriate amount to prevent this high temperature cracking. In general, in laser welding, when a welding wire as a filler metal is supplied to a welded part using the laser irradiation start as a trigger, the distance between the welding start point (laser irradiation start point) and the tip of the welding wire. In addition, it is required from the need to obtain a good welded portion by controlling the supply speed of the welding wire and controlling the welding wire to be appropriately added to the welded portion at the start of welding.

  In the combined welding method that combines laser irradiation and consumable electrode gas shielded arc welding in order to efficiently obtain a good weld, laser irradiation is triggered by turning on the welding power source used for consumable electrode gas shielded arc welding. The technical matter for adjusting the timing is well known. (For example, refer to Patent Document 1.)

JP 2003-25081 A

  In the combined welding method that combines laser irradiation and consumable electrode gas shielded arc welding, there is a welding power source on one of the consumable electrode gas shielded arc welding means, so the timing of laser irradiation in relation to turning on the welding power source However, if it is not such a composite welding method, the timing of laser irradiation cannot be achieved because there is no welding power source.

  Further, in the previous composite welding method, the arrival of the welding wire to the welded portion is not the timing of laser irradiation.

  For this reason, a laser welding method is adopted in which a welding wire as a filler material is supplied to the welded part without using a welding power source, and the supplied welding wire is melted by the heat of the laser. In this case, it is difficult to match the arrival of the welding wire to the weld and the timing of laser irradiation.

  Therefore, in laser welding that does not employ the composite welding method, for example, if the supply of the welding wire is too early, the welding wire is excessively supplied to the welded part before the laser irradiation starts, and the welding wire that is insufficiently melted, that is, does not melt, is welded. The result will remain on top. Alternatively, in the welding of austenitic stainless steel or the like, when the supply of the welding wire is delayed, there is a high possibility that high temperature cracking occurs because sufficient filler metal is not supplied to the welding start point. This deteriorates the quality of the weld.

  An object of the present invention is to suppress deterioration in quality of a welded part in laser welding in which a welding wire is melted by laser heat without adopting a composite welding method.

  As means for achieving the object of the present invention, a laser welding apparatus comprising means for irradiating a laser beam from an irradiation head to a welded portion set on an object to be welded, and a welding wire supply device for supplying a welding wire to the welded portion. In this case, laser irradiation is performed from means for applying a voltage to the welding wire, means for detecting an electric current applied when the welding wire comes into contact with the workpiece, and means for irradiating the laser based on the detection. And a laser for irradiating a laser beam to a welding part set on an object to be welded and supplying a welding wire to the welding part to weld the welding part. In the welding method, the welding wire is supplied in the direction of the welding portion in a state where a voltage is applied to the welding wire in advance, and the welding wire is brought into contact with the workpiece to be passed. Currents detects, possible to provide a laser welding method to start irradiation of the laser on the basis of the detection.

  According to the present invention, since the timing of laser irradiation in laser welding can be controlled without adopting the composite welding method, there is an effect that quality deterioration of the laser welded portion can be suppressed.

  In an embodiment of the present invention, in order to achieve the object of the present invention, a voltage is applied to the welding wire 11 in advance, and then the welding wire 11 is fed by the welding wire supply device 4 so that the welding wire 11 is to be welded. 10 is energized, and this current is detected by the control device 5, and the laser oscillator 1 is actuated as a trigger to start laser irradiation, so that the welding wire 11 is reliably supplied at the start of laser irradiation. In addition, there has been proposed a laser welding method characterized in that positioning of the welding wire 11 tip before feeding and setting of the supply speed of the welding wire supply device 4 can be facilitated.

  Further, by changing the supply speed of the welding wire 11 by the welding wire supply device 4 before and after the start of laser irradiation, the welding wire 11 is used to obtain a trigger for starting laser irradiation and in the molten pool in the main welding. It has been proposed that stable laser welding can be performed by setting the welding wire 11 to a suitable condition for each.

  In addition, after a voltage is applied to the welding wire 11 in advance, the welding wire 11 is fed by the welding wire supply device 4, and when the welding wire 11 comes into contact with the workpiece 10, the current is energized. By detecting and using this as a trigger, the irradiation head 2 is moved by the irradiation head moving device 8 and welding is performed, so that the laser irradiation starts in a state where the welding wire 11 is reliably supplied at the start of the laser irradiation. By welding along, it is possible to form a stable weld bead at the start of welding.

  In addition, after a voltage is applied to the welding wire 11 in advance, the welding wire 11 is fed by the welding wire supply device 4, and when the welding wire 11 comes into contact with the workpiece 10, the current is energized. Detecting this, and using this as a trigger, the workpiece 10 is moved by the welding portion moving device 9 and welding is performed, so that the laser irradiation is started in a state where the welding wire 11 is reliably supplied at the time of starting the laser irradiation. By welding along the groove, it is possible to form a weld bead at the start of stable welding.

  For example, when the laser irradiation spot diameter is equal to or smaller than that of the welding wire 11, a voltage is applied to the welding wire 11 in advance, and then the welding wire 11 is fed by the welding wire supply device 4 from the welding progress direction side. When the welding wire 11 comes into contact with the workpiece 10, the current is detected by the control device 5, and laser irradiation is started, so that the welding wire 11 is melted on the front side in the traveling direction of the laser beam 12. By welding, the influence on the molten pool that solidifies behind the melted portion may be reduced, and the formation of a weld bead at the start of stable welding may be enabled.

Further, for example, when the laser irradiation spot diameter is equal to or larger than that of the welding wire 11, a voltage is previously applied to the welding wire 11, and then the welding wire 11 is sent by the welding wire supply device 4 from the opposite side of the welding progress direction. When the welding wire 11 comes into contact with the workpiece 10 to be welded, the current is detected by the control device 5, and by starting the laser irradiation, the welding wire 11 is directly irradiated with the laser beam 12, and the base metal In order to prevent the irradiation of a certain welded part 110 from being hindered and hindering the melting of the work piece 10 to be welded, the welding wire 11 is supplied into the molten pool formed by the work piece 10 being melted by the laser beam 12. Thus, insufficient melting may be suppressed, and formation of a weld bead at the start of stable welding may be enabled.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of a laser welding apparatus according to an embodiment of the present invention that uses a YAG laser as a laser oscillator 1. The laser welding apparatus according to the present embodiment includes a laser oscillator 1 that generates a laser beam 12 and an irradiation head that adjusts and converges the laser beam 12 to irradiate the workpiece 10 with the laser beam 12 emitted from the laser oscillator 1. 2. Laser conveying device 3 for conveying the laser beam 12 from the laser oscillator 1 to the irradiation head 2 (in this embodiment, an optical fiber is used), welding wire supply for feeding the welding wire 11 to the welded portion side Device 4, conduit tip 6 through which welding wire 11 is passed to supply welding wire 11 to a predetermined position of the weld, welding to protect welding wire 11 from welding wire supply device 4 to conduit tip 6 Conduit cable 7 through which wire 11 is passed, laser beam is irradiated to irradiate the welding groove that is the welded portion of workpiece 10 during welding Power source for applying voltage to the welding wire 11 via the irradiation head moving device 8 for moving the head 2 side, the welded portion moving device 9 for moving the work piece 10 side, and the conduit tip 6 13. Wiring 14 for forming a circuit so that a current flows through the applied power source 13 → the conduit chip 6 → the welding wire 11 → the workpiece 10 → the control device 5 when the welding wire 11 comes into contact with the workpiece 10; And a circuit of a relay 15 that is employed as means for detecting the current and that operates when the current flows.

  This relay circuit is built in the control device 5 of the laser welding apparatus together with a personal computer (hereinafter referred to as a personal computer). The control device 5 recognizes that the current is detected by the operation of the circuit of the relay 15 by inputting it into a personal computer as a welding wire contact signal, and uses it for controlling the laser welding device.

  Next, an operation procedure of the laser welding apparatus when performing welding using the laser welding apparatus controlled by the control apparatus 5 will be described with reference to a timing chart shown in FIG.

  First, it is assumed that a voltage is applied to the welding wire 11 via the conduit tip 6 with the applied power supply 13 in a state where the welding wire 11 is not in contact with the workpiece 10. Next, a normal rotation (rotation direction for supplying the welding wire 11 to the welded portion) command is issued from the control device 5 to the welding wire supply device 4, and the welding wire 11 is directed toward the welded portion of the work 10 to be welded. send.

  When the welding wire 11 fed toward the welded part of the workpiece 10 contacts the workpiece 10, a voltage is applied to the welding wire 11 by the applied power source 13, and therefore the applied power source 13 → conduit tip 6 → weld. A current flows from the wire 11 to the workpiece 10 to the wiring 14 to the relay 15. This current, that is, a welding wire contact signal, is input as an input signal to a personal computer in the control device 5, and a laser irradiation signal as an output signal is sent from the personal computer to the laser oscillator after time T1 using a clock in the personal computer. Laser irradiation is started. Further, an output signal, which is the laser irradiation signal output from the personal computer in the control device 5, is used as an input signal to the personal computer, and a laser in the personal computer in the control device 5 is used to start laser irradiation, that is, laser irradiation. After the time T2 is received, the irradiation head 2 or the welded portion moving device 9 is operated, and welding is performed while supplying the welding wire 11 along the welding groove line of the workpiece 10.

  The times T1 and T2 are set according to each welding depending on the welding conditions depending on the material and shape of the workpiece 10. As for the welding wire supply speed, as shown in FIG. 2, after the welding wire contact signal is detected, the supply speed of the welding wire 11 is set to the case 1 according to a program pre-installed in the personal computer in the control device 5 according to the welding conditions. , Case 2 and Case 3 are changed. The timing from time T3 to T5 and the transmission / reception of input / output signals described below were also controlled by a personal computer in the control device 5.

  At the end of welding, after the irradiation head moving device 8 or the welded portion moving device 9 is operated, the irradiation head moving device 8 or the welded portion moving device 9 is stopped after the time T5 has elapsed, and the welding wire is supplied after the time T3 has elapsed after the stop. The forward rotation command of the device 4 is stopped, the supply of the welding wire 11 is stopped, and a reverse rotation (rotation direction opposite to the normal rotation) command is issued to the welding wire supply device 4, and the welding wire 11 is pulled out from the welded portion.

  After the welding wire 11 is pulled out from the welded portion, the welding wire 11 stops in a state of slightly protruding from the distal end portion of the conduit tip 6 on the workpiece 10 side. Laser irradiation is stopped after time T4 after the supply of the welding wire 11 is stopped, and the welding is finished. The times T3 and T4 are set in accordance with the welding conditions depending on the material and shape of the work piece 10 and the time T5 is set in accordance with each welding by the welding speed and the welding length.

Also, the welding wire supply speed is the same as the laser irradiation signal described above. When the welding wire 11 comes into contact with the workpiece 10, a voltage is applied to the welding wire 11 by the applied power supply 13, so the applied power supply 13 → the conduit chip 6 → A current flows from the welding wire 11 to the workpiece 10 to the wiring 14 to the relay 15, and this current, that is, the welding wire contact signal is input to the personal computer in the control device 5 as an input signal, and the clock in the personal computer is used. After the time T1, a rotation speed setting signal of the welding wire supply device 4 as an output signal is transmitted from the personal computer to the wire supply device, and the wire supply speed shown in FIG. 2 is the same as before the welding wire 11 contacts the workpiece 10 Case 1, wire supply speed is faster than before welding wire 11 contacts workpiece 10 Case 2, wire supply speed is welding wire 11 The faster it becomes casing 3 than before contacting the object to be welded 10. These are set and executed in any case depending on the output of the laser to be irradiated, the welding speed, the groove shape, the required weld penetration depth, and the like.

Example 1 in which welding was performed using a laser welding apparatus using the above YAG laser is shown in FIG.
(B) (c) Shown in (d). The workpiece A21 is a thin plate having a material of SUS316L and a thickness of about 7 mm, and the workpiece B22 is a thin plate having a material of SUS316L and a thickness of about 1 mm. As in the assembled state before welding shown in FIG. 3A, an I-shaped welding groove is provided as a welding groove at the butt portion between the workpiece A21 and the workpiece B22. The butt portion was welded by supplying SUS316ULC as the welding wire 11 with the laser welding apparatus shown in FIG.

  The workpiece A21 and the workpiece B22 are fixed during welding, and the irradiation head moving device 8 in FIG. 1 is operated to connect the irradiation head 2 and the conduit tip 6 to the workpiece A21 and the workpiece B22. Welded it by moving it relatively. Further, the welding wire supply speed was set such that the wire supply speed as shown in case 2 of FIG. 2 was faster than before the welding wire 11 contacted the workpiece 10.

  After welding, a liquid penetration test was conducted on the welded portion 23 shown in FIG. 3 (b). When the conventional method was used, welding defects such as hot cracks were found in 4 out of 100 test locations. However, in this example, no defects were found in 600 test locations. In Example 1, nitrogen gas was used as the shielding gas for preventing oxidation of the welded portion, and the welding posture was downward.

  Next, Example 2 welded using a laser welding apparatus using the YAG laser is shown in FIGS. As shown in FIG. 4A, the workpiece C31 is a columnar body made of SUS316L, and the workpiece D32 is a thin cylindrical body having a material of SUS316L and a plate thickness of about 1 mm. As in the pre-weld assembly state shown in FIG. 4B, the right side of the workpiece C31 is fitted inside the workpiece D32, and the portion where the workpiece C31 and the workpiece D32 are abutted with each other. The welding groove is applied to the welded portion 34. The welding groove is an I-shaped welding groove.

  As shown in FIG. 4B, the workpiece C31 is attached to the positioner 33 by the chuck of the positioner 33 while the workpiece C31 and the workpiece D32 are fitted together. The positioner 33 can rotate the chucked workpiece C31 around the cylindrical central axis of the workpiece D32.

  The workpiece C31 and the workpiece D32 attached to the positioner 33 are welded by the laser welding apparatus shown in FIG. 1 along the welding groove at the butt portion between the workpiece C31 and the workpiece D32. . At the time of the welding, the welding wire 11 to be used is made of SUS316ULC, and the welding wire 11 of the material is supplied to the welding groove to perform the welding.

During the welding, welding was performed by rotating the workpiece C31 and the workpiece D32 with the positioner 33. The positioner 33 uses the output signal, which is the laser irradiation signal output from the personal computer in the control device 5, as an input signal to the personal computer, and uses the clock in the personal computer in the control device 5 to start the laser irradiation. After receiving the laser irradiation signal and after a time T2, the rotation of the positioner 33 is started, and the welding wire 11 is welded along the welded portion C31 of the workpiece C31 and the workpiece D32 (the welding groove is shown before welding). Welding while supplying By the welding, a welded portion 34 (referred to as a weld bead after welding) shown in FIG.

  The welding wire 11 is supplied by changing the rotation direction of the positioner 33, as shown in FIG. 5, in the rotation direction A35 in which the welding wire 11 is supplied from the front in the welding progress direction and in the rotation direction B36 in the case where the welding wire 11 is supplied from the rear in the welding progress direction. Two cases were carried out. Moreover, the diameter of the welding wire 11 used the thing equivalent to the spot diameter in the welding part 34 of a laser beam (laser beam 12).

  After the welding, the liquid penetration test was performed on the welded portion 34. The welding direction 11 is a rotation direction A35 when the welding wire 11 is supplied from the front of the welding direction and a rotation direction B36 when the welding wire 11 is supplied from the rear of the welding direction. In any case, no welding defects such as hot cracks were observed. In Example 2, argon gas was used as the shielding gas for preventing oxidation of the weld 34, and the welding posture was downward.

  In this embodiment, the welding is performed by rotating the work piece side. However, if the relative movement of the irradiation head 2 and the conduit tip 6 and the work piece is taken into consideration, the work piece (the present embodiment) is reversed. Then, welding may be performed by fixing the workpiece C31 and the workpiece D32) and rotating the irradiation head 2 and the conduit tip 6 along the groove of the workpiece.

In any of the embodiments of the present invention, after a voltage is applied to the welding wire 11 in advance, the welding wire 11 is fed to the welding portion by the welding wire supply device, and is energized when the welding wire 11 contacts the workpiece, By detecting this current with the control device 5 and using this as a trigger to activate the laser oscillator 1 and start laser irradiation, it is possible to create a situation in which the welding wire 11 is reliably supplied to the weld at the start of laser irradiation. Thus, there is an effect of preventing hot cracking due to insufficient melting of the welding wire 11 or insufficient addition of the welding wire.

It is a block diagram of the laser welding apparatus concerning this invention. It is a timing chart figure of operation in welding work by a laser welding apparatus concerning the present invention. 1 shows a first embodiment related to welding work by the laser welding apparatus of the present invention, wherein (a) is a plan view showing a butt assembly state of a workpiece to be welded before welding, and (b) is a workpiece to be welded after welding. The top view which shows the state of an object, (c) A figure is AA sectional drawing of (a) figure, (d) figure is BB sectional drawing of (b) figure. Fig. 2 shows a second embodiment related to welding work by the laser welding apparatus of the present invention, wherein (a) is an elevation view showing a state before butt assembly of the workpieces before welding, and (b) is before welding. FIG. 5C is an elevation view showing a state in which the assembly after butt assembly of the workpiece is attached to the positioner as viewed from the left side of the positioner in FIG. 5, and FIG. 5C is a vertical view showing the state of the workpiece after welding. FIG. It is a general view of the laser welding apparatus used in Example 2 related to the construction of welding by the laser welding apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser oscillator, 2 ... Irradiation head, 3 ... Laser conveying apparatus, 4 ... Welding wire supply apparatus, 5 ... Control apparatus, 6 ... Conduit chip, 7 ... Conduit cable, 8 ... Irradiation head moving apparatus, 9 ... To-be-welded part Moving device, 10 ... workpiece to be welded, 11 ... welding wire, 12 ... laser beam, 13 ... applied power supply, 14 ... wiring, 15 ... relay, 21 ... workpiece to be welded A, 22 ... workpiece to be welded B, 23, 34 ... Welding part, 31 ... welded object C, 32 ... welded object D, 33 ... positioner, 35 ... rotating direction A, 36 ... rotating direction B.

Claims (6)

In a laser welding apparatus comprising: means for irradiating a laser beam from an irradiation head to a welded portion set on an object to be welded; and a welding wire supply device for supplying a welding wire to the welded portion.
Means for applying a voltage to the welding wire;
Means for detecting an electric current energized when the welding wire comes into contact with the workpiece;
Control means for controlling to start laser irradiation from means for irradiating the laser based on the detection;
A laser welding apparatus comprising:   2. The laser welding apparatus according to claim 1, further comprising control means for controlling the welding wire supply device so as to change a supply speed of the welding wire based on the detection.   2. The apparatus according to claim 1, further comprising means for moving the irradiation head or the workpiece, and the movement so as to relatively move the irradiation head and the workpiece along the weld based on the detection. The laser welding apparatus provided with the control means which controls the means to make. In a laser welding method of irradiating a laser beam to a welded part set on a workpiece and supplying a welding wire to the welded part to weld the welded part,
Supplying the welding wire in the direction of the weld with a voltage applied in advance to the welding wire;
Detecting an electric current energized when the welding wire comes into contact with the workpiece,
A laser welding method for starting irradiation of the laser based on the detection.   5. The laser welding method according to claim 4, wherein a supply speed of the welding wire is changed based on the detection. 5. The laser welding method according to claim 4, wherein the irradiation head and the workpiece are relatively moved along the welded portion based on the detection.

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