JP2002239731A - Wire heating control method for hot wire welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wire heating control method for hot wire welding, capa ble of automatically and properly controlling applied power for heating a wire even with high-speed welding, and maintaining an addition wire in a desired molten state without depending on a welder. SOLUTION: The presence or absence of a deflection and a curved state of this addition wire 6 are determined by monitoring an insertion state of the addition wire 6 into a welding part by a camera 15, and analyzing a picture taken by this camera 15 by a picture processing device 16. Then, when a deflection and a curve are detected, the applied electric power by a wire heating power source 10 is increased to perform automatic control so as to increase a heating amount to the addition wire 6. Moreover, when the deflection of the addition wire 6 is detected and it is also determined that the wire heating power source 10 is supplying a proper amount of heat, a driving mechanism such as a wire torch tilting mechanism 17 properly moves a wire torch 13, and thereby the insertion position of the addition wire 6 into the welding part is automatically controlled so as to approach to the side of the arc 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to hot wire welding, and more particularly to a wire heating control method used to appropriately maintain a molten state of an additive wire heated by a wire heating power supply.

[0002]

2. Description of the Related Art FIG. 6 is a configuration diagram showing a conventional general welding device used for hot wire TIG welding. In the figure, reference numeral 1 denotes a welding torch, 2 denotes a tungsten electrode, 3 denotes a base material of a workpiece to be welded, and 4 denotes an arc power source, and is used for direct current welding between the tungsten electrode 2 and the base material 3 in the welding torch 1. The arc 5 is formed in the argon shield gas with the tungsten electrode 2 as a negative electrode by connecting the arc power supply 4 and supplying the current Ia. Reference numeral 6 denotes an additional wire for welding, 7 denotes a wire feeder, and the wire reel 1
4 is fed from a wire feeder 7 to a conduit 8 and further passes through a contact tip 9 and a ceramic guide 11 provided on a wire torch 13 to a weld where an arc 5 is formed. Be guided.
Reference numeral 10 denotes a wire heating power supply for applying a current Iw to the additional wire 6 to generate heat.
By connecting 0 to the contact tip 9 and the base material 3 and passing an alternating current or a direct current, Joule heat is generated in the additional wire 6, so that the melting speed of the additional wire 6 increases. Reference numeral 12 denotes a weld pool formed by the arc 5, and reference numeral 23 denotes a weld bead after welding. In addition, laser welding method, etc.
When the hot wire method is applied to other welding methods, the device configuration on the hot wire side is the same.

[0003] The additive wire 6 is energized and heated at an extension portion e between the contact tip 9 and the base material 3, and the heating power applied to the extension portion e needs to be adjusted according to the wire feeding speed. Hot wire TI
The optimum wire melting state in G welding is the addition wire 6
Is brought into contact with the molten pool 12, and the additive wire 6 is completely melted very close to the contact point. Most desirably, the addition wire 6 is completely melted immediately before entering the molten pool 12 on the base material 3 and the molten metal is continuously melted down without being cut. In such a case, melting of the additive wire 6 and the molten pool 1
The molten metal transfer to 2 proceeds as the liquid flows in,
A good weld bead 23 is formed.

However, if the applied heating power is too low with respect to the feeding speed of the addition wire 6, the addition wire 6 enters the molten pool 12 deeply, and the heat from the molten metal in the molten pool 12 It finally melts by transmission. For this reason, when the heating power applied by the wire heating power supply 10 is insufficient, the additional wire 6 does not melt and strikes the bottom of the molten pool 12 to cause deflection, and the deflection of the additional wire 6 causes the welding bead. Inconveniences such as a deviation of the shape of the wire 23 and a trace of wire dragging on the weld bead 23 are likely to occur. Further, as shown in FIG. 7, the unmelted wire 19 may remain in the weld metal 20 forming the weld bead 23 and form a welding defect.

Further, if the applied heating power is excessive with respect to the feeding speed of the addition wire 6 and the energization of the addition wire 6 in an overheated state is continued, the addition wire 6 is melted while generating spatter, and After separation, the tip of the addition wire 6 and the base material 3
Discharge or between the electrode and the tungsten electrode 2 to disturb the arc 5 or to form a large droplet at the tip of the addition wire 6, thereby significantly impairing the welding workability.

For this reason, conventionally, Japanese Patent Publication No. 4-28470.
As shown in the publication, the power applied to the extension portion e of the additional wire 6 during welding is measured so that the heating power applied by the wire heating power supply 10 becomes a value corresponding to the wire feeding speed. Is widely adopted. However, the melting of the addition wire 6 is also affected by the amount of heat from the arc 5 and the molten pool 12.
It is not possible to keep the added wire 6 in an appropriate molten state only by measuring the applied power for heating the wire. That is,
In actual welding, a change in the arc length or a change in the insertion position into the molten pool 12 due to the bending habit of the additional wire 6 causes
Since the amount of heat applied from the arc 5 and the molten pool 12 to the addition wire 6 fluctuates, a phenomenon often occurs in which the addition wire 6 deviates from an appropriate molten state. Therefore, it is necessary for the welder to constantly monitor and adjust the applied power for heating the wire and the insertion position of the additional wire 6, and the burden on the welder for long-time welding is large.

Therefore, as a technique for promoting automation in hot wire welding, Japanese Patent Publication No. 5-75511 discloses a technique in which a DC pulse current is used as a current for heating the additive wire 6, and a wire terminal power when the current is not supplied. Is detected to determine whether or not the addition wire 6 and the base material 3 are in contact with each other. And
In Japanese Patent Publication No. 5-75512, this technology is used.
After the additional wire 6 is overheated and blown, the applied power for heating the wire is set lower than the applied power immediately before the blow, and then the applied power is gradually increased again to cause the overheated blow of the additional wire 6. The operation is controlled to be repeated. As described above, when the method of controlling the applied heating power while grasping the insertion position of the addition wire 6 is adopted, the addition wire 6 is automatically maintained in an appropriate molten state without adjustment by a welder. It becomes possible.

[0008]

SUMMARY OF THE INVENTION The above-mentioned Tokuho 5-7
The wire heating control method disclosed in Japanese Patent No. 5512 discloses a welding speed of 80 mm / min to 300 mm for ordinary hot wire TIG welding.
However, in high-speed welding at a welding speed of 300 mm / min or more, the addition wire 6 is fed at a high speed and the response speed of fusing cannot catch up, so it cannot be said that it works effectively. That is, in high-speed welding,
Monitoring and adjustment by the welder was still required.

In addition, since the width of the molten pool 12 is reduced in high-speed welding, it is necessary to more accurately control the insertion position of the additive wire 6 into the welded portion. Since the addition wire 6 is apt to bend, the insertion position of the addition wire 6 into the weld may be shifted due to the bend. The heat- and wear-resistant ceramic guide 11 shown in FIG. 6 is provided as a countermeasure, and the electrically heated addition wire 6 fed from the contact tip 9 of the wire torch 13 is provided.
In the process of guiding the weld to the weld, it serves to correct the bending habit. However, this ceramic guide 11 also cannot exert a sufficient correcting effect unless the additional wire 6 is heated with an appropriate applied power, and therefore, in high-speed welding where it is not easy to control the applied power for heating the wire, It was difficult to completely correct the bending habit of the additional wire 6, and also required monitoring and adjustment by a welder.

[0010] In short, in high-speed hot wire welding, a method has not been established for appropriately and automatically controlling the applied electric power for heating the wire in accordance with the melting state of the additional wire 6 and whether or not there is a bend. There is such a trouble that it is necessary to adjust the applied heating power and the insertion position of the additional wire 6 while monitoring the melting state of the wire 6, and the welding quality is not stable because it depends on the sense of the welder. . In particular, in the case of narrow groove welding requiring high welding quality, the welder must perform monitoring and adjustment over a long period of time, so that the burden is extremely large and welding defects are likely to occur.

The present invention has been made in view of the above-mentioned circumstances of the prior art, and has as its object to be able to appropriately automatically control the applied power for wire heating even at high speed welding, and to add the power without depending on the welder. An object of the present invention is to provide a method for controlling wire heating in hot wire welding, which can maintain a desired molten state of a wire.

[0012]

According to one aspect of the present invention, an additional wire for welding supplied from a wire feeder is inserted into a welding portion through a wire torch. In the wire heating control method of controlling the amount of heating by the wire heating power supply by hot wire welding to generate heat by connecting a wire heating power supply to the addition wire, monitoring the insertion state of the addition wire to the welded portion with a camera, By analyzing an image taken by this camera with an image processing device, it is determined whether or not the addition wire has been shaken, and if the addition wire has been detected, the heating amount is increased. I tried to make it.

In the case of hot wire welding, if the amount of heating of the additive wire is insufficient due to high-speed welding or the like, a phenomenon occurs in which the additive wire that cannot be melted pierces the bottom of the molten pool.
The added wire oscillates at the welded portion, and the presence or absence of this sway is determined by image processing, and when the sway is detected, if the applied power by the wire heating power supply is increased to increase the amount of heating of the added wire, the applied heating power becomes insufficient. Since it is automatically canceled, it becomes possible to maintain the additive wire in a desired molten state without depending on the welder even in high-speed welding.

In this solution, when the deflection of the additional wire is detected and the amount of heating by the wire heating power supply is determined to be appropriate, the insertion position of the additional wire into the weld is shifted and the heating is performed. If it is judged that the shortage has occurred and the insertion position of the addition wire to the welded part is automatically controlled to be closer to the arc side via the drive mechanism provided on the wire torch, the insertion position of the addition wire will shift. As a result, the shortage of the amount of heating caused by the above-mentioned problem is solved, so that the molten state of the additional wire can be further stabilized.

As another means for achieving the above-mentioned object, the present invention relates to a welding device in which a welding wire supplied from a wire supplying device is welded while correcting a bending habit by a guide member provided on a wire torch. In a wire heating control method of controlling the amount of heating by the wire heating power source by hot wire welding that generates heat by connecting a wire heating power source to the addition wire, Monitor with a camera, analyze the image taken by this camera with an image processing device, determine whether the addition wire has a bend, and if the bend of the addition wire is detected, The amount of heating was increased.

In hot wire welding, if the amount of heating of the additive wire is insufficient due to high-speed welding or the like, the guide member provided on the wire torch cannot sufficiently correct the bending habit of the additive wire. Will fluctuate. However, like this solution,
The degree of bending of the added wire is determined by image processing, and when bending is detected, increasing the amount of heating applied to the added wire by increasing the power applied by the wire heating power supply makes it easier to correct the bending habit. The bending habit of the wire can be reliably corrected. Therefore, it is possible to avoid poor welding caused by bending of the additional wire without depending on the welder.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
This will be described with reference to FIGS. However, FIG. 1 is a configuration diagram of the hot wire TIG welding device according to the first embodiment, FIG. 2 is a configuration diagram of the hot wire TIG welding device according to the second embodiment, and FIG. FIG. 4 is an image explanatory view showing a state of the added wire at the time of normal welding, FIG.
FIG. 4 is an image explanatory view showing a state in which a bending habit remains in the addition wire inserted into the welded portion.

In these figures, reference numeral 1 denotes a welding torch, 2 denotes a tungsten electrode, 3 denotes a base material, 5 denotes an arc,
Is an additive wire, 7 is a wire feeder, 8 is a conduit,
9 is a contact chip, 10 is a wire heating power source, 11 is a ceramic guide, 12 is a molten pool, 13 is a wire torch, 14 is a wire reel, 15 is a camera, 16 is an image processing device, 17 is a wire torch tilt mechanism, and 18 is a wire torch tilt. Drivers, 21a, 21b and 21c indicate upper scanning lines, 22a, 22b and 22c indicate lower scanning lines, and 23 indicates a weld bead. In these figures, parts corresponding to those in FIG. 6 used in the description of the related art are denoted by the same reference numerals, and redundant description will be omitted as appropriate.

In the first embodiment shown in FIG. 1, the state of insertion of the addition wire 6 into the welded portion is monitored by the camera 15,
The image taken by the camera 15 is taken into the image processing device 16 and can be analyzed. Although the camera 15 is a commercially available industrial camera, the arc light uses a special filter because the light intensity in the ultraviolet region is very high. The image processing device 16 is a device in which an image memory is mounted on a computer, and can process various information by processing image information captured from the camera 15 by software. Further, the image processing device 16 is connected to the wire heating power supply 10 by an electric signal line, so that the heating power applied to the additional wire 6 can be controlled according to the analysis result of the image processing device 16.

FIGS. 3 and 4 show images taken by the camera 15 in the first embodiment. The tungsten electrode 2 and the arc 5 appear very bright, but the surrounding area is dark. It is a shadow of light from the electrode 2 and the arc 5 and is dark. When welding is performed normally, as shown in FIG. 3, the addition wire 6 extends straight to a position overlapping with the center line of the tungsten electrode 2 and the arc 5. On the other hand, when the additional wire 6 that cannot be melted due to insufficient heating amount pierces the bottom of the molten pool 12, the additional wire 6 oscillates. Therefore, as shown in FIG. The image is projected at a position off the center line of the arc 2 and the arc 5. Therefore, if such an image is periodically taken into the image processing device 16 and the position of the addition wire 6 is measured, the addition wire 6
It can be determined whether or not the shake has occurred.
Note that the image captured by the image processing device 16 can be handled as coordinate data. For example, in FIGS. 3 to 5, the upper left in the drawing is the coordinate origin, the X coordinate is 0 to 250, and Y is
The coordinates are 0 to -250.

Here, a method of measuring the position of the addition wire 6 by the image processing device 16 will be described. In FIG.
Looking at the pixel data from left to right on the upper scanning line 21a, the boundary A point can be detected because the tungsten electrode 2 is bright and the addition wire 6 is dark. That is, the coordinate value (X coordinate and Y coordinate) of the left end point A of the addition wire 6 can be obtained. Next, the lower scanning line 2
Looking at the pixel data from left to right on 2a,
Since the arc 5 is bright and the addition wire 6 is dark, the boundary B point can be detected. That is, the addition wire 6
(X coordinate and Y coordinate) of the leftmost point B can be obtained. The coordinate values of points A and B are stored, and when the next image is captured, the same operation is performed and the value is compared with the previous value to determine whether or not the addition wire 6 has run out. Can be determined. Further, by comparing the X coordinates of the points A and B, the degree of bending of the addition wire 6 can be detected.

FIG. 4 shows an image when the addition wire 6 that cannot be melted due to insufficient heating amount pierces the bottom of the molten pool 12 and the addition wire 6 oscillates. At the time of normal welding, assuming that an image is captured when the addition wire 6 positioned over the center line of the tungsten electrode 2 and the arc 5 swings to the position shown by the solid line in FIG. 4, the upper scanning line 21b and the lower scanning line 22b Left end A
The coordinate values of the points a and Ba can be obtained, and by comparing these values with the coordinate values of the points A and B, the X coordinate of the points Aa and Ba becomes smaller than that during normal welding. You can see that there is. Therefore, the addition wire 6
Is moved to the left side in the figure. Then, when the same operation is performed when the next image is captured, for example, if it is determined that the addition wire 6 has moved to the right side in the drawing, it is determined that the addition wire 6 has been shaken. Therefore, a command to increase the heating power applied by the wire heating power supply 10 is issued in order to increase the amount of heating of the additional wire 6. As a result, Joule heat increases and the melting speed of the additive wire 6 increases, so that the phenomenon of the additive wire 6 piercing the bottom of the molten pool 12 does not occur, and the deflection is eliminated. That is, since the shortage of the applied power for heating the wire is automatically eliminated, it is possible to maintain the additive wire 6 in a desired molten state without depending on the welder even in high-speed welding. Welding defects such as unmelted wire remaining on the wire can be avoided. However, as disclosed in Japanese Patent Publication No. 28470/1992, the applied power for heating the wire is required to be set to a value within a predetermined range corresponding to the wire feeding speed, and therefore falls within that range. In this way, the applied heating power is increased.

FIG. 5 shows the addition wire 6 inserted into the weld.
7 is an image showing a state in which a bending habit remains. Assuming that the addition wire 6 positioned over the center line of the tungsten electrode 2 and the arc 5 at the time of normal welding is bent as shown in FIG. 5, it is assumed that the addition wire 6 at the left end Ab point of the addition wire 6 determined by the upper scanning line 21c is used. Lower scanning line 2 compared to X coordinate
Since the X coordinate of the left end Bb point obtained in 2c becomes smaller,
The degree of bending of the tip of the addition wire 6 can be seen. Such a bending habit should be corrected by a heat-resistant and abrasion-resistant ceramic guide 11 for guiding the additive wire 6 fed from the contact tip 9 to the welded portion. If the heating power is insufficient, the addition wire 6 may have a bending habit as shown in FIG. Therefore, if the image analysis reveals the degree of bending of the distal end portion of the addition wire 6, a command to increase the heating power applied by the wire heating power supply 10 by an amount corresponding to the degree of bending is sent to the image processing apparatus. 16 is output. Thereby, the contact tip 9
Since the rigidity of the additive wire 6 fed from the welding wire is reduced, the additive wire 6 is
Can be reliably corrected, and welding defects due to the bending of the additive wire 6 can be avoided without depending on the welder.

In the second embodiment shown in FIG.
The wire torch 13 is provided with a wire torch inclining mechanism 17 for changing the insertion position of the addition wire 6 into the welded portion. The wire torch inclining mechanism 17 is driven by a wire torch inclining driver 18 so that the wire torch 13 is moved in the direction of the arrow shown in the figure. By moving the addition wire 6, the insertion position of the addition wire 6 can be controlled to be closer to the arc 5 side or to be farther away. However, the wire torch tilting mechanism 17 may have a configuration in which the wire torch 13 is slid in the horizontal direction in the drawing. Further, the wire torch tilt driver 18 is connected to the image processing device 16 by an electric signal line, and can control the wire torch tilt mechanism 17 by a command from the image processing device 16. In the second embodiment, as in the first embodiment, the state of insertion of the addition wire 6 into the welded portion is monitored by the camera 15, and an image captured by the camera 15 is subjected to image processing. It can be captured in the device 16 and analyzed.

In the second embodiment, when the image processing device 16 captures an image as shown in FIG.
If the applied power by 0 is set to the upper limit within the allowable range, the cause of the shortage of the heating amount that caused the deflection of the additional wire 6 is not the shortage of the applied heating power but the displacement of the insertion position of the additional wire 6. to decide. That is, the fact that the heating power applied to the addition wire 6 is set to the upper limit within the allowable range in consideration of the wire feeding speed means that the heating amount by the wire heating power supply 10 is appropriate and more heating power is applied. Therefore, in this case, the wire torch tilt driver 18 drives the wire torch tilt mechanism 17 by a signal from the image processing device 16, and the insertion position of the additional wire 6 into the welding portion is determined by the arc 5. Control to approach the side. As a result, the amount of heat applied from the arc 5 to the addition wire 6 increases, so that the melting speed of the addition wire 6 increases, and the deflection is eliminated.

In the above embodiment, the hot wire T
Although IG welding is described, it goes without saying that the present invention can be applied to other welding methods employing the hot wire method, and in particular, a remarkable effect in high speed welding such as laser welding combined with the hot wire method. Can be expected.

[0027]

The present invention is embodied in the form described above, and has the following effects.

In the wire heating control method of hot wire welding, the presence / absence of the deflection of the added wire is determined by image processing, and when the deflection is detected, the power applied by the wire heating power supply is increased to increase the amount of heating of the added wire. Since the shortage of the heating power is automatically eliminated, it is possible to maintain the added wire in a desired molten state without depending on the welder even in high-speed welding. In particular, when the present invention is applied to narrow groove welding that requires high welding quality, it is not necessary for a welder to perform monitoring and adjustment over a long period of time, so that the human burden is greatly reduced and welding defects can be easily avoided.

In this wire heating control method, when the deflection of the addition wire is detected and the amount of heating by the wire heating power supply is determined to be appropriate, the addition of the addition wire is performed via a driving mechanism provided in the wire torch. If the insertion position of the wire into the weld is automatically controlled to be closer to the arc side, the lack of heating caused by the displacement of the insertion position of the additive wire will be resolved, and the molten state of the additive wire will be more stable. Can be done.

Further, in the wire heating control method of hot wire welding, in which the degree of bending of the additional wire is determined by image processing, and when the bending is detected, the power applied by the wire heating power source is increased to increase the amount of heating of the additional wire. The guide member provided on the wire torch can reliably correct the bending habit of the additional wire even in high-speed welding, so that welding defects due to the bending of the additional wire can be avoided without depending on the welder.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a hot wire TIG welding apparatus according to a first embodiment.

FIG. 2 is a configuration diagram of a hot wire TIG welding apparatus according to a second embodiment.

FIG. 3 is an image explanatory view showing a state at the time of normal welding of an additive wire inserted into a welding portion.

FIG. 4 is an image explanatory view showing a state in which an additive wire inserted into a welded portion has been shaken.

FIG. 5 is an image explanatory view showing a state in which a bending habit remains in an addition wire inserted into a welded portion.

FIG. 6 is a configuration diagram showing a conventional general hot wire TIG welding apparatus.

FIG. 7 is an explanatory diagram showing a welding defect in which an unmelted wire remains in a weld bead.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding torch 2 Tungsten electrode 3 Base material 5 Arc 6 Addition wire 7 Wire feeding device 8 Conduit 9 Contact chip 10 Wire heating power supply 11 Ceramic guide 12 Melt pool 13 Wire torch 14 Wire reel 15 Camera 16 Image processing device 17 Wire torch tilting mechanism 18 Wire torch tilt driver 21a, 21b, 21c Upper scan line 22a, 22b, 22c Lower scan line 23 Weld bead

Claims (3)

[Claims] 1. A hot wire welding method in which an additional wire for welding supplied from a wire supply device is inserted into a welding portion via a wire torch, and a wire heating power source is connected to the additional wire to generate heat. In a wire heating control method of controlling a heating amount by a heating power supply, a state of insertion of the addition wire into a welded portion is monitored by a camera, and an image captured by the camera is analyzed by an image processing device, whereby the addition is performed. A wire heating control method for hot wire welding, wherein it is determined whether or not a runout has occurred in the wire, and when the runout of the added wire is detected, the heating amount is increased. 2. The method according to claim 1, wherein when the deflection of the additional wire is detected and the amount of heating by the wire heating power supply is determined to be appropriate, the driving mechanism provided on the wire torch is used. Wherein the insertion position of the additive wire into the weld is made closer to the arc side. 3. An additional wire for welding supplied from a wire supply device is inserted into a weld portion while correcting a bending habit by a guide member provided on a wire torch, and a wire heating power source is connected to the additional wire. In a wire heating control method of controlling the amount of heating by the wire heating power source in hot wire welding for generating heat, a state of insertion of the additional wire into a welded portion is monitored by a camera, and an image captured by the camera is processed by an image processing apparatus. Hot wire welding characterized in that it is determined whether or not the additional wire has a bend by analyzing in the above, and when the bend of the additional wire is detected, the heating amount is increased. Wire heating control method.