JP2012245564A - Monitoring device and monitoring method for welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably detect the condition of droplets during arc welding on line in real time.SOLUTION: A device for monitoring droplets 7 during arc welding comprises a droplet detector 10 for detecting the droplet 7 moving from the area beneath a welding wire 4 to the outside of the area. The droplet detector 10 is composed to irradiate the top 4a side of the welding wire 4 with a detecting light and to determine that the droplet 7 moves from the area beneath the welding wire 4 to the outside of the area on the basis of the blocking state of the detecting light by the droplet 7.

Description

  The present invention relates to a welding monitoring apparatus and a welding monitoring method for monitoring the state of arc welding.

In arc welding, as arc discharge occurs between a welding wire and a base material that is a material to be welded, droplets are formed at the tip of the welding wire. The droplet formed at the tip of the welding wire is detached from the tip of the welding wire and transferred to the molten pool of the base material (droplet transfer).
When transferring droplets, it is only necessary that the droplets that have melted from the tip of the welding wire smoothly transfer to the molten pool of the base material.For example, arc discharge is interrupted, or the droplet is other than the region directly under the welding wire If it jumps out, the welding quality may be reduced.

For this reason, several techniques have been developed to monitor the state of droplet transfer or to correct the droplet transfer during welding.
For example, Patent Document 1 discloses a droplet detachment detection unit that detects detachment of a droplet from a welding wire tip in arc welding using carbon dioxide alone or a mixed gas containing carbon dioxide as a main component as a shielding gas, A first pulse for releasing the droplet and a second pulse for shaping the droplet are alternately generated and output to the welding power source, and immediately after the droplet is detected, the current value of the first pulse A waveform generator that switches to a predetermined value lower than the current value at the time of detection, wherein the waveform generator is configured to detect the droplet in the peak period, falling slope period, or base period of the first pulse. When no separation is detected, a third pulse having a pulse shape having a pulse peak current or a pulse width different from that of the second pulse after the end of the base period of the first pulse. Welding control apparatus generates and modifies the droplet transfer regularity of displacement by output to the welding power source is disclosed. That is, in Patent Document 1, by controlling the pulse waveform, even if the regularity of droplet transfer is lost, it can be immediately restored.

  Patent Document 2 discloses a welding state in which a welding power source is electrically connected between a consumable electrode wire and a material to be welded, and the welding state is monitored in consumable electrode gas shielded arc welding in which arc welding is performed in a shielding gas atmosphere. A monitoring device that changes the waveform corresponding to the waveform change of the welding state signal consisting of welding voltage, welding current or welding voltage that occurs during droplet transfer from the tip of the consumable electrode wire to the molten pool Welding provided with a droplet transition detection unit that outputs a signal and a droplet transition state detection unit that outputs a droplet transition state signal including signal number information of the waveform change signal output during the droplet transition A state monitoring device is disclosed.

JP 2009-233728 A JP 2001-321842 A

In the techniques of Patent Document 1 and Patent Document 2, although droplet transfer can be detected indirectly by detecting the welding voltage and welding current during arc welding, which droplets are actually detected during arc welding. In reality, it is difficult to detect whether or not it is in such a state directly and in real time.
Further, as a technique for directly detecting the state of the droplet during arc welding, as shown in FIG. 6 of Patent Document 2, the state of the droplet can be imaged and observed with a high-speed camera or the like. Conceivable. However, it is very difficult to adopt a droplet transfer monitoring technique using a high-speed camera in-line (actual welding process).

  In view of the problems, the present invention provides a welding monitoring device and a welding monitoring method that can easily and reliably detect the state of a droplet during welding.

In order to achieve the above object, the present invention takes the following technical means.
That is, the technical means for solving the problems in the present invention is a welding monitoring device that monitors droplets during arc welding, and detects droplets that move outside the region from the region directly under the welding wire during arc welding. The droplet detection means irradiates the detection light toward the tip end side of the welding wire, and the droplet detects the droplet based on the detection light blocking state by the droplet. It is configured to determine that the region has moved from the region immediately below the welding wire to the outside of the region.

The droplet detection means includes a distance detection sensor that irradiates spot light as the detection light, and the distance detection sensor detects the droplet when the detection distance is changed by the irradiation detection light being blocked by the droplet. It is preferable to detect movement.
It is preferable that a plurality of the distance detection sensors are arranged on the side of the welding wire and around the welding wire.

Preferably, the droplet detection means includes a blocking detection sensor that emits line light as the detection light, and the blocking detection sensor detects movement of the droplet based on a blocking state of the irradiated line light.
It is preferable that the said interruption | blocking detection sensor is arrange | positioned at the width direction both sides of a welding wire so that the said detection light may pass between the front-end | tip part and base material of a welding wire.

  Another technical means for solving the problems in the present invention is a welding monitoring method for monitoring droplets during arc welding. In arc welding, a detection light is irradiated toward the tip of the welding wire and irradiated. On the basis of the state in which the detected light is blocked by the droplet, it is determined that the droplet has moved from the region immediately below the welding wire to the outside of the region.

  According to the present invention, the state of the droplet can be reliably detected in real time in-line during welding.

1 is an overall view of a welding apparatus that performs arc welding. It is a state figure of the droplet during arc welding. 1A and 1B show a welding monitoring apparatus according to a first embodiment, in which FIG. 1A is a front view showing the periphery of a welding wire, FIG. 1B is a plan view of the periphery of the welding wire, and FIG. It is a top view (modification) of the circumference of a wire. It is a figure which shows the 1st welding monitoring apparatus which concerns on 2nd Embodiment. It is a figure which shows the 2nd welding monitoring apparatus which concerns on 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 shows a welding apparatus provided with a welding monitoring apparatus according to the present invention.
The welding apparatus 1 has a welding torch 3 for welding a base material 2 (material to be welded). The welding torch 3 can feed a welding wire 4 (consumable electrode) for arc welding toward the base material 2. In the case of this embodiment, the welding torch 3 is attached to the tip of the vertical 6-axis articulated robot 5, and each joint is rotated or rotated by a control signal from the robot controller, so that the position of the welding torch 3 is free. Instead of this, arc welding of the base material 2 can be performed.

Now, when arc welding is performed, as shown in FIG. 2A, as arc discharge occurs between the welding wire 4 and the base material 2, the droplets 7 are formed on the distal end portion 4 a of the welding wire 4. It is formed. The droplet 7 grows gradually and begins to narrow at the base, moves away from the tip portion 4a of the welding wire 4 and moves to a molten pool formed in a region A (directly below region) immediately below the tip portion 4a of the welding wire 4. .
However, as shown in FIG. 2B, when the enlarged droplet 7 moves away from the region A immediately below and moves to the outer region B (outer region) that is not directly below the region A, the quality of the welding deteriorates. There is a possibility (in the figure, coarsening). In other words, if the enlarged droplets 7 move to the outer region away from the molten pool instead of the molten pool, the quality deteriorates. In particular, FIG. 2C and FIG.
), When the droplet 7 enlarged during arc welding breaks off from the tip 4a of the welding wire 4 and flies to the outer region B, the strength after welding decreases or the melted liquid that has detached. It is not preferable because the droplet 7 remains on the base material 2 (in the figure, breakage of the break arc, re-ignition).

Therefore, in the present invention, during welding, the transition from the good welding state shown in FIG. 2A to the poor welding state shown in FIGS. 2A to 2D can be detected. In other words, the welding apparatus 1 is provided with a welding monitoring device that monitors the droplet 7 so that it can be quickly detected that the droplet 7 has moved from the region A directly below the tip end 4a of the welding wire 4 to the outer region B. It is said.
Hereinafter, the welding monitoring apparatus will be described in detail.

  As shown in FIG. 3A, the welding monitoring apparatus includes droplet detection means 10 that can detect the droplet 7 moving from the region A directly below to the outer region B with detection light. The droplet detection means 10 assumes that welding is in a good state when the droplet 7 stays in the region A immediately below and the detection light is not blocked, and the droplet 7 moves from the region A directly below to the outer region B. When the detection light applied to the outer region B is blocked, it is detected that the welding is poor.

Specifically, the droplet detection means 10 irradiates spot detection light, detects a distance to a detection target, and reflects the detection light emitted from the distance detection sensor 11 to give a predetermined value. And a reflection mirror 12 directed toward the detection target. In the case of this embodiment, the distance detection sensor 11 is configured by a laser distance meter that irradiates infrared laser spot light.
As shown in FIGS. 3A and 3B, a plurality of distance detection sensors 11 are arranged at equal intervals around the welding wire 4 on the side of the welding wire 4. In the case of FIG. 3A, three distance detection sensors 11 are arranged around the welding wire 4 so that the opening angle θ between the distance detection sensors 11 is 120 °. Each distance detection sensor 11 is stored in the case 13 so that its optical axis faces the base material 2 side, and this case 13 is attached to the outer peripheral surface of the welding torch 3.

Further, a window 14 through which the detection light passes is formed on the lower surface of the case 13 at a position close to the welding wire 4 protruding from the welding torch 3. The window 14 is preferably provided with a protective glass for dust prevention and protection.
Note that the number of the distance detection sensors 11 is not limited to three, and may be any number. For example, as shown in FIG. 3C, the distance around the welding wire 4 is set so that each opening angle θ is 90 °. Four distance detection sensors 11 may be arranged in the same.

  The reflection mirror 12 guides the detection target by reflecting the detection light emitted from the distance detection sensor 11. In the present embodiment, two reflecting mirrors 12 a and 12 b are provided in one case 13. The first reflection mirror 12a is disposed on the front surface of the distance detection sensor 11, reflects the detection light emitted from the distance detection sensor 11 toward the inner side (side closer to the welding torch 3), and the second reflection mirror. Reference numeral 12 b is arranged in the vicinity of the welding torch 3 so that the detection light travels outside the case 13 along the welding wire 4. Specifically, the two reflection mirrors 12a and 12b are arranged so that the detection light emitted from the distance detection sensor 11 is emitted to the boundary between the region A and the outer region B on the base material 2. An angle is set.

In the droplet detection means 10 having the above configuration, when the detection light is irradiated from the distance detection sensor 11, the detection light passes through the window 14 while being reflected by the reflection mirror 12, and is applied to the welding wire 4 at the side of the welding wire 4. Along the lower side, the outer region B (the boundary between the immediately lower region A and the outer region B) is irradiated.
In this droplet detection means 10, the optical path distance from the distance detection sensor 11 to the base material 2 is detected by the detection light emitted from the distance detection sensor 11, but during arc welding, FIG. As shown in FIG. 2 (d), when the droplet 7 leaves from the region A immediately below the outer region B, the detection light does not reach the base material 2 and is blocked by the droplet 7. Under this condition, the optical path distance is shortened and the output of the distance detection sensor 11 is changed, so that it can be seen that the detection light is blocked by the droplet 7. Thus, based on the blocking state of the detection light, it is determined that the droplet 7 has moved from the region A directly below and has entered the outer region B, in other words, a poor welding state.

When the droplet detection means 10 detects that the droplet 7 has moved from the region A directly below to the outer region B, it outputs a detection signal indicating that the droplet 7 has moved to the outer region B to the robot controller or another controller. To do. Based on this detection signal, the welding operation by the robot may be stopped, or the welding conditions (welding voltage, welding current) may be changed. Even if the welding operation is not stopped, the welded portion that has output this detection signal may be inspected in a focused manner in the subsequent welding inspection.

However, in the present invention, it is only necessary to detect that the droplet 7 has moved from the distal end portion 4a of the welding wire 4 to the side (outer region B) of the welding wire 4 during welding. The processing after the movement to the outer region B is not particularly limited.
As described above, by using the present invention, the welding voltage and welding current during welding as in the prior art can be achieved simply by irradiating the detection light on the tip 4a side of the welding wire 4 and in the vicinity of the welding wire 4. It is possible to easily and reliably detect the state of the droplet 7 without measuring or imaging the droplet 7 with a high-speed camera and performing complicated image processing, and it is easy to apply in-line. It will be a thing.
[Second Embodiment]
Next, a second embodiment of the welding monitoring apparatus will be described.

In the first embodiment described above, the detection light is spot light, and the droplet detection means 10 configured to proceed downward along the side of the welding wire 4 from above the base material 2 is employed.
On the other hand, in the second embodiment, after detecting light as line light instead of spot light, droplet detection is performed so that the line light is irradiated substantially horizontally on the base material 2 and passes through the tip 4a of the welding wire 4. The means 10 is comprised.

As shown in FIG. 4A, the droplet detection means 10 of the second embodiment irradiates infrared laser line light L as detection light, and detects whether the detection light is blocked or not. have.
The blocking detection sensor 15 includes a plurality of irradiation units 16 that irradiate the line light L, and a plurality of light receiving units 17 that are arranged on the side facing each irradiation unit 16 and receive the line light L from the irradiation unit 16. I have. Specifically, each irradiation unit 16 is arranged in two upper and lower stages, and each light receiving unit 17 is arranged in two upper and lower stages on the opposite side of the upper and lower irradiation units 16. Each irradiation part 16 is provided on one end side in the width direction of the base material 2 with the welding wire 4 interposed therebetween, and each light receiving part 17 is provided on the other end side in the width direction of the base material 2. In addition, it is preferable to set arrangement | positioning of the irradiation part 16 or the light-receiving part 17 so that the irradiated detection light may be in the state along a welding plan line.

  In order to detect the state of the droplet by the droplet detection means 10 as described above, as shown in FIG. 4B, for example, the line lights L1 and L2 (detection light) irradiated from the upper and lower irradiation units 16 are used. The width is set to be substantially the same as the width of the region A immediately below, and the arrangement of the upper and lower irradiation units 16 is set so that the upper and lower detection lights L1 and L2 pass between the welding wire 4 and the base material 2. By doing so, in the normal welding state as shown in FIG. 4B, both the upper detection light L1 and the lower detection light L2 are blocked, and the cutoff detection sensor 15 is in the cutoff state. Judge. However, as shown in FIG. 4C, if the droplet 7 is moved from the region A directly below to the outer region B, the upper detection light L1 is blocked, but the lower detection light L2 is Non-blocking occurs, and the output of the blocking detection sensor 15 changes. In this way, when the upper (one) detection light L1 is blocked and the lower (other) detection light L2 is not blocked, the blocking detection sensor 15 is in a state where the droplet 7 has entered the outer region B. It is judged that the welding is poor.

  Now, in the interruption detection sensor 15 shown in FIG. 4, the upper and lower detection lights L1 and L2 are used to detect the state of the droplet, but as shown in FIG. 5A, one detection light L3 is used. Thus, the state of the droplet may be detected. Specifically, the interruption detection sensor 15 has one irradiating unit 16 that irradiates the line light L3 and one light receiving unit 17 that is disposed on the side facing the irradiating unit 16 and receives the line light L3. . The irradiation unit 16 is disposed on one end side in the width direction of the base material 2 with the welding wire 4 interposed therebetween as described above, and the light receiving unit 17 is disposed on the other end side in the width direction of the base material 2.

In order to detect the state of the droplet by the droplet detection means 10 as described above, as shown in FIG. 5B, for example, the width of the line light L3 irradiated from the irradiation unit 16 is set to the width of the region A directly below. The arrangement of the irradiation unit 16 is set so that the irradiated detection light L3 passes between the welding wire 4 and the base material 2. By doing so, if it is a normal welding state as shown in FIG.5 (b), the detection light L3 will be interrupted | blocked and the interruption | blocking detection sensor 15 will be judged as an interruption | blocking state. However, as shown in FIG. 5 (c), if the droplet 7 is moved from the region A directly below to the outer region B, the detection light L3 is not blocked and the output of the block detection sensor 15 is changed. The detection sensor 15 determines that the penetrating state. When the shutoff detection sensor 15 detects that it is in the penetrating state, it can be determined that the droplet 7 has entered the outer region B or a poor welding state.
That is, unlike the case shown in FIG. 4, the droplet detection means 10 shown in FIG. 5 detects that the welding state is good when the droplet 7 stays in the region A immediately below and the detection light L3 is blocked. When 7 moves from the region A directly below to the outer region B and the detection light L3 applied to the outer region B is not blocked, it is detected that the welding is in a poor state.

When the detection light is blocked, it is determined that the welding state is normal. However, the time interval at which the droplets are blocked is detected based on the output signal of the blocking detection sensor 15, for example, time When the interval is constant, it may be determined as a normal welding state, and when the time interval changes irregularly, it may be determined as a poor welding state.
As described above, even in the droplet detection means 10 of the second embodiment, the detection light is irradiated to the vicinity of the welding wire 4 on the distal end portion 4a side of the welding wire 4 and welding is performed as in the related art. It is possible to easily and reliably detect the state of the droplet 7 without measuring the welding voltage or welding current, or performing complicated image processing by imaging the droplet 7 with a high-speed camera. Application to is also easy.

  In the present embodiment, instead of irradiating the region A directly with line light as described above, the detection light L can be passed through the outer region B in contact with the edge of the region A immediately below. . In this case, for example, in the normal welding state as shown in FIG. 5B, the detection light L is not blocked, and the blocking detection sensor 15 determines that it is in the penetrating state. However, as shown in FIG. 5C, if the droplet 7 has moved from the region A directly below to the outer region B, the detection light is blocked and the block detection sensor 15 determines that the block is in the block state. In this case, when the interruption detection sensor 15 detects that it is in the interruption state, it can be determined that the droplet 7 has entered the outer region B, that is, a poor welding state.

Since other configurations of the second embodiment are substantially the same as those of the first embodiment, detailed description thereof is omitted.
In the embodiment disclosed herein, matters that are not explicitly disclosed, such as operating conditions and operating conditions, various parameters, dimensions, weights, volumes, and the like of the constituents, depart from the scope normally practiced by those skilled in the art. Instead, a matter that can be easily assumed by a person skilled in the art is employed.

DESCRIPTION OF SYMBOLS 1 Welding apparatus 2 Base material 3 Welding torch 4 Welding wire 5 Vertical 6-axis articulated robot 7 Droplet 10 Droplet detection means 11 Distance detection sensor 12 Reflection mirror 13 Case 14 Window 15 Blocking detection sensor 16 Irradiation part 17 Light-receiving part A Immediately below Area B Outside area

Claims (6)

In a welding monitoring device that monitors droplets during arc welding,
Equipped with droplet detection means for detecting droplets moving outside the region from the region directly under the welding wire during arc welding;
The droplet detection means irradiates the detection light toward the distal end side of the welding wire and, based on the detection light blocking state by the droplet, the droplet drops from the region directly below the welding wire to the outside of the region. It is comprised so that it may determine with having moved, The welding monitoring apparatus characterized by the above-mentioned. The droplet detection means includes a distance detection sensor that irradiates spot light as the detection light,
The welding monitoring apparatus according to claim 1, wherein the distance detection sensor detects movement of a droplet when the detected detection light is blocked by the droplet and the detection distance changes.   The welding monitoring apparatus according to claim 2, wherein a plurality of the distance detection sensors are arranged on the side of the welding wire and around the welding wire. The droplet detection means includes a blocking detection sensor that emits line light as the detection light,
The welding monitoring apparatus according to claim 1, wherein the blocking detection sensor detects the movement of the droplet based on a blocking state of the irradiated line light.   5. The welding according to claim 4, wherein the blocking detection sensors are arranged on both sides in the width direction of the welding wire so that the detection light passes between the tip of the welding wire and the base material. Monitoring device. In a welding monitoring method for monitoring droplets during arc welding,
Irradiate detection light toward the tip of the welding wire during arc welding,
A welding monitoring method, characterized in that, based on a state in which the irradiated detection light is blocked by a droplet, it is determined that the droplet has moved from the region immediately below the welding wire to the outside of the region.

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