JP2014108437A - Arc welding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc welding apparatus in which a welded part can be clearly viewed when abnormal conditions occur during arc generation.SOLUTION: An arc welding apparatus includes a welding power source PS that outputs a welding current Iw and a welding voltage Vw, and a protection surface HG mounting a light shielding panel GP for protecting the eye of a welding worker from arc light. The arc welding apparatus newly includes: an abnormal condition determination unit AD that outputs an abnormal condition determination signal Ad by determining abnormal conditions such as a magnetic arc blow and a gas blow from a molten pool during arc generation; and a transmittance control unit GC that changes the light transmittance of the light shielding panel GP, when the abnormal condition determination signal Ad is input. Thereby, when the abnormal conditions occur, the light transmittance of the light shielding panel GP becomes large to light up a welded part, so that the welded part can be viewed clearly. Also, in normal conditions comprising a large portion of a welding period, the light transmittance of the light shielding panel GP is small, so that the burden of the eye is reduced.

Description

  The present invention provides a welding power source that outputs a welding current and a welding voltage for generating an arc between an electrode and a base material, and a protective surface equipped with a light-shielding panel that protects a welding worker's eyes from arc light. The present invention relates to an arc welding apparatus.

  When a welding operator manually performs arc welding, a protective surface equipped with a light shielding panel is used to protect the eyes from arc light. The light-shielding panel is a filter having a reduced light transmittance, and welding can be performed while visually confirming the arc generation portion with this light-shielding panel. Since the intensity of the arc light varies depending on the magnitude of the welding current, a plurality of light shielding panels having different light transmittances are prepared, and the light shielding panels are replaced and used according to the welding current value. Until the arc is ignited, the welded part can hardly be seen by the light-shielding panel, so the protective surface is retracted from the front until the arc ignites, and when the arc is ignited, it is held in front of the eye It is necessary to perform complicated operations.

  The invention of Patent Document 1 detects the generation of arc light by an ultraviolet sensor, and changes the light transmittance of protective glasses (protective surface). That is, when the ultraviolet sensor is not detecting arc light (before the arc is ignited), the light transmittance is increased so that the surroundings can be visually observed. When the ultraviolet sensor detects the arc light, the light transmittance is reduced and darkened, and the arc light is shielded so that the arc generating portion can be visually observed. The light transmittance is changed by a liquid crystal panel. When a voltage higher than the reference is applied to the liquid crystal panel, the light transmittance increases, and when no voltage is applied, the light transmittance is minimized. The light transmittance can be adjusted steplessly according to the voltage value to be applied.

  The invention of Patent Document 2 detects a welding state and changes the light transmittance of a protective shield (light-shielding panel) according to the welding state. That is, the light transmittance is changed in the magnitude of the welding current, in the short-circuit state or the arc generation state, in the case of the positive polarity or negative polarity of the AC arc welding, or in the peak period or base period of the pulse arc welding. . Thereby, the welding state can be clearly observed.

  By the way, various abnormal states occur during arc generation, and the arc generation state may become unstable. As this abnormal state, there are a magnetic blow generation state, a gas ejection state from a molten pool, and the like. When a magnetic blow occurs during the generation of an arc, the arc is greatly deflected and deviates from the weld line, often resulting in a bead failure. Magnetic blowing is particularly likely to occur in consumable electrode type pulse arc welding. Various methods for suppressing the deflection of the arc caused by the magnetic blowing have been proposed, but have not been completely successful (for example, see Patent Document 3). Magnetic blowing occurs in a section where the magnetic field formed when the welding current is energized becomes asymmetric with respect to the arc, so it concentrates on some sections of the welding section such as the welding start part and welding end part. Tend to occur.

  In addition, when a gas jet is generated from the molten pool during the arc generation, the arc is largely deflected by the gas jet and disengages from the weld line, often resulting in a bead failure. Gas ejection is particularly likely to occur in carbon dioxide arc welding. This is because the carbon dioxide gas of the shielding gas is dissolved in the molten pool as carbon monoxide, and this carbon monoxide is heated and evaporated during the arc period and is suddenly ejected as a gas from the molten pool. The gas ejection tends to occur in a concentrated manner in a part of the welding section due to the influence of the welding posture, the shielding state of the shielding gas, and the like.

JP-A-2-159272 Japanese Patent No. 4961428 JP2012-110951

  By the invention of Patent Document 2 described above, the light shielding panel can be changed to a light transmittance suitable for the welded state. However, in the invention of Patent Document 2, even if an abnormal state occurs during arc generation, the light transmittance of the light shielding panel does not change.

  When an abnormal state such as magnetic blowing or gas ejection from the molten pool occurs during arc generation, the welding operator performs a manual operation to prevent any deterioration in welding quality even in the abnormal state. For example, when a magnetic blow occurs during arc generation, the arc deflects and deviates from the weld line, so the welding operator operates the welding torch to correct the arc along the weld line. Even when gas ejection occurs during arc generation, since the arc is deflected and deviates from the weld line, the welding operator operates the welding torch to correct the arc along the weld line. Since the manual operation during this abnormal state is a delicate operation, it is desirable that the welded portion can be clearly observed. Therefore, if the light transmittance of the light-shielding panel during arc generation is increased, the welded portion is visually observed in a bright state during welding, which places a burden on the eyes.

  Therefore, the present invention provides an arc welding method that can visually observe the welded portion more clearly when an abnormal state occurs during arc generation, and can suppress an increase in the burden on the eyes during welding. An object is to provide an apparatus.

In order to solve the above-described problems, the invention of claim 1 includes a welding torch for supplying power to an electrode, a welding power source for outputting a welding current and a welding voltage for generating an arc between the electrode and a base material, and an arc. In an arc welding apparatus provided with a protective surface equipped with a light-shielding panel that protects the welding worker's eyes from light,
An abnormal state determination unit that determines an abnormal state of an arc generation state and outputs an abnormal state determination signal; and a transmittance control unit that changes the light transmittance of the light-shielding panel when the abnormal state determination signal is input;
An arc welding apparatus comprising:

According to a second aspect of the present invention, the abnormal state is a magnetic blown state.
The arc welding apparatus according to claim 1, wherein:

In the invention of claim 3, the abnormal state is a gas ejection state from the molten pool.
The arc welding apparatus according to claim 1, wherein:

  According to the present invention, since the light transmittance of the light shielding panel when the abnormal state determination signal is output is increased, it is brighter than in the normal state where it is not output, and the welded portion can be clearly observed. it can. And in the normal state which occupies most of the welding period, the light transmittance of the light-shielding panel is reduced, so the burden on the eyes is reduced. Welding workers can recognize the occurrence of abnormal conditions such as magnetic blowing and gas ejection from the molten pool because the light-shielding panel becomes brighter during arc generation. It becomes easy to move the welding torch along the welding line.

It is a block diagram of the arc welding apparatus which concerns on Embodiment 1 of this invention. It is a timing chart of each signal of the arc welding apparatus of FIG. It is a block diagram of the arc welding apparatus which concerns on Embodiment 2 of this invention. It is a timing chart of each signal of the arc welding apparatus of FIG.

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

[Embodiment 1]
FIG. 1 is a block diagram of an arc welding apparatus according to Embodiment 1 of the present invention. This figure shows a case where the abnormal state during arc generation is a magnetic blow generation state. This figure shows a case of an arc welding apparatus for consumable electrode type pulse arc welding in which magnetic blow is likely to occur. Hereinafter, each block will be described with reference to FIG.

  The welding power source PS is a welding power source for consumable electrode arc welding having a constant voltage characteristic. When a welding start signal St described later reaches a high level, the welding power source PS outputs a welding current Iw and a welding voltage Vw, and a feeding motor FM. The feed control signal Fc for controlling the rotation of is output. The feed motor FM receives the feed control signal Fc and feeds the welding wire 1. The welding wire 1 as a consumable electrode is fed through the welding torch 4 by the rotation of the feeding roll 5 coupled to the feeding motor FM, and an arc 3 is generated between the base metal 2 and the welding wire 1. A welding current Iw is passed between the welding wire 1 and the base material 2, and a welding voltage Vw is applied.

  The torch switch ST is provided in the welding torch 4 and outputs a welding start signal St that becomes a high level when the welding operator turns on. When the welding start signal St becomes High level, the welding power source PS is activated.

  The welding current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The welding voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The energization determination circuit CD receives the current detection signal Id, and outputs an energization determination signal Cd that becomes a High level when this value is equal to or higher than a predetermined threshold value. The threshold value is set to about 10 A so that it can be determined that the welding current Iw is energized. The energization determination signal Cd is at a high level when the arc 3 is generated.

  The abnormal state determination circuit AD receives the current detection signal Id, the voltage detection signal Vd, and the energization determination signal Cd, and when the energization determination signal Cd is at a high level (arc is being generated), the current detection signal The peak period and the base period are discriminated based on the value of Id, and the magnetic field is detected when the value of the voltage detection signal Vd becomes equal to or higher than the reference value during the base period or the rate of increase of the voltage detection signal Vd becomes equal to or higher than the reference value. The occurrence of blowing is discriminated, and an abnormal state discriminating signal Ad which becomes High level for a predetermined period is output. The reason why the high level is maintained for a predetermined period is that the magnetic blowing often continues for a certain period while repeatedly generating and stopping. The predetermined period is set according to the length of the period during which the magnetic blowing continues and is set to about several seconds. This operation will be described in detail with reference to FIG.

  The transmittance control circuit GC receives the above-described abnormal state determination signal Ad, and when the abnormal state determination signal Ad is at a low level (normal state), the transmittance control signal Gc that becomes a predetermined first transmittance setting value G1. And outputs a transmittance control signal Gc having a predetermined second transmittance setting value G2 when the level is high (abnormal state). G1 <G2. That is, since the light transmittance of the light shielding panel GP in the abnormal state is larger, it becomes brighter than in the normal state, and the welded portion can be visually observed. And in the normal state which occupies most of the welding period, the light transmittance of the light shielding panel GP becomes small, so the burden on the eyes is lightened. The welding operator can recognize the occurrence of the magnetic blow by the light-shielding panel GP becoming bright during the arc generation, and under the clear visual condition, the welding arc of the welding torch so that the deflected arc follows the weld line. It becomes easy to perform the moving operation.

  The protective surface HG is equipped with a light shielding panel GP and protects the eyes of the welding operator from arc light. The light shielding panel GP receives the above-described transmittance control signal Gc, and is controlled to have a light transmittance determined by the transmittance control signal Gc. As the light shielding panel GP, a liquid crystal panel capable of changing the light transmittance in a plurality of stages according to the applied voltage value is used as in the prior art.

  Even if the welding current detection circuit ID, the welding voltage detection circuit VD, the energization determination circuit CD, the abnormal state determination circuit AD, and the transmittance control circuit GC are incorporated in the welding power source PS. good. Further, these circuits may be incorporated in another independent transmittance controller.

  FIG. 2 is a timing chart of each signal of the arc welding apparatus described above with reference to FIG. FIG. 4A shows the time change of the welding current Iw, FIG. 4B shows the time change of the welding voltage Vw, and FIG. 4C shows the time change of the abnormal state determination signal Ad. Hereinafter, a description will be given with reference to FIG.

  Times t1 to t2 indicate peak periods, times t2 to t3 indicate base periods, times t3 to t4 indicate peak periods, times t4 to t5 indicate base periods, and times t5 to t6 indicate peak periods, Times t6 to t7 indicate the base period. Since the value of the welding current Iw is small, the magnetic blowing tends to occur during the base period in which the arc rigidity becomes weak and the deflection becomes easy. In the same figure, it is a case where a magnetic blowing generate | occur | produced during the base period of time t4-t5 and the base period of time t6-t7. Therefore, during the base period from time t2 to time t3, the magnetic blow is in a normal state.

  As shown in FIG. 5A, a peak current Ip greater than or equal to a predetermined critical value is applied during the peak period, and a base current Ib less than the predetermined critical value is applied during the base period. The peak current Ip is about 450 A, and the base current Ib is about 50 A. Therefore, if the threshold value is set to about 200 A, the period during which a current equal to or greater than the threshold value is supplied becomes the peak period, and the period during which a current less than the threshold value is supplied is the base period. As shown in FIG. 5B, a peak voltage Vp corresponding to the arc length is applied during the peak period, and a base voltage Vb corresponding to the arc length is applied during the base period.

  During the base period from time t2 to t3, a substantially constant base voltage Vb is applied, and no magnetic blow is generated. During the base period from the time t4 to the time t5, the base voltage Vb rapidly rises from the time t41 in the middle of the period, and becomes a large voltage value similar to the peak voltage value, and this value is maintained until the time t5. At time t41, a magnetic blow is generated and the arc is greatly deflected. The occurrence of magnetic blow is determined when the base voltage value Vb is equal to or higher than the reference value or the rate of increase of the base voltage value Vb is equal to or higher than the reference value. When the occurrence of magnetic blow is determined at time t41, the abnormal state determination signal Ad changes to a high level as shown in FIG. The high level state is maintained for a predetermined period of about several seconds. Since the pulse period including the peak period and the base period is about 200 Hz, several hundred pulse periods are repeated within a few seconds. Similarly, during the base period from time t6 to t7, the base voltage Vb rapidly rises to a large voltage value at time t61 in the middle of the period.

  In the period before time t41 when the abnormal state determination signal Ad shown in FIG. 10C is at the low level, the first transmittance setting value G1 is set. During the period after time t41 when the abnormal state determination signal Ad is at the high level, the second transmittance setting value is set. G2. As a result, the light transmittance of the light-shielding panel GP is greater in the period in which the magnetic blow occurs after time t41 than in the period in which the magnetic blow before time t41 does not occur. That is, the light-shielding panel GP during the period in which the magnetic blow is generated becomes bright, and the welded portion can be visually observed more clearly.

  This figure illustrates the case where the welding method is consumable electrode type pulse arc welding. In addition, it can be applied to carbon dioxide arc welding, mag welding, MIG welding, AC pulse arc welding, and the like. In the case of direct current arc welding other than pulse arc welding, it is possible to determine the occurrence of magnetic blow by detecting the rapid increase in the welding voltage during arc generation by the above-described determination method.

  According to the first embodiment described above, the abnormality determination unit AD that determines the abnormal state of the arc generation state and outputs the abnormal state determination signal Ad, and the light of the light shielding panel GP when the abnormal state determination signal Ad is input. And a transmittance control unit GC for changing the transmittance. In the present embodiment, since the light transmittance of the light shielding panel GP is increased when the abnormal state determination signal Ad is output, it becomes brighter than in the normal state where it is not output, and the welded portion is visually observed. be able to. And in the normal state which occupies most of the welding period, the light transmittance of the light shielding panel GP becomes small, so the burden on the eyes is lightened. The welding operator can recognize the occurrence of the magnetic blow by the light-shielding panel GP becoming bright during the arc generation, and under the clear visual condition, the welding arc of the welding torch so that the deflected arc follows the weld line. It becomes easy to perform the moving operation.

[Embodiment 2]
The abnormal state during the generation of the arc is the state of magnetic blow generation in the above-described first embodiment, but in the second embodiment, it is a gas ejection state from the molten pool. Hereinafter, description will be given with reference to the drawings.

  FIG. 3 is a block diagram of an arc welding apparatus according to Embodiment 2 of the present invention. This figure shows a case where the abnormal state during arc generation is a gas ejection state from the molten pool. This figure shows a case of an arc welding apparatus for carbon dioxide arc welding in which gas ejection from the molten pool is likely to occur. This figure corresponds to FIG. 1 described above, and the same reference numerals are given to the same blocks, and their explanations are omitted. In the figure, a short circuit determination circuit SD is added, and the abnormal state determination circuit AD of FIG. 1 is replaced with a second abnormal state determination circuit AD2. Hereinafter, these blocks will be described with reference to FIG.

  The short circuit determination circuit SD receives the voltage detection signal Vd as an input, determines the short circuit period based on this value, and outputs a short circuit determination signal Sd that is at a high level during the short circuit period and is at a low level during the arc period.

  The second abnormal state determination circuit AD2 receives the voltage detection signal Vd, the energization determination signal Cd, and the short-circuit determination signal Sd, the energization determination signal Cd is at a high level, and the short-circuit determination signal Sd is at a low level. Occasionally (when an arc is generated), an abnormal state determination signal Ad that becomes high level for a predetermined period by determining gas ejection from the molten pool due to the occurrence of a steep ripple waveform in the voltage detection signal Vd a predetermined number of times. Is output. A method for discriminating a steep ripple waveform will be described in detail with reference to FIG. The predetermined number of times is set to about 2 to 5 times. The reason why the high level is maintained for a predetermined period is that gas ejection often continues for a certain period while repeatedly generating and stopping. The predetermined period is set according to the length of the period during which gas ejection continues, and is set to about several seconds.

  The welding power source PS may include the welding current detection circuit ID, the welding voltage detection circuit VD, the energization determination circuit CD, the short circuit determination circuit SD, the second abnormal state determination circuit AD2, and the transmittance control circuit GC. . Further, these circuits may be incorporated in another independent transmittance controller.

  FIG. 4 is a timing chart of each signal of the arc welding apparatus described above with reference to FIG. FIG. 4A shows the time change of the welding voltage Vw, FIG. 2B shows the time change of the welding current Iw, and FIG. 4C shows the time change of the abnormal state determination signal Ad. Hereinafter, a description will be given with reference to FIG.

  The figure shows waveforms for two cycles of a short circuit period and an arc period. Times t1 to t2 indicate a short circuit period, times t2 to t3 indicate an arc period, times t3 to t4 indicate a short circuit period, and times t4 to t5 indicate an arc period. During the period from time t1 to t3, there is no gas ejection from the molten pool and the welding state is stable, and during the period from time t3 to t5, gas ejection from the molten pool occurs.

  During the short-circuit period from time t1 to t2, the welding voltage Vw becomes a short-circuit voltage value having a small value of several V as shown in FIG. 9A, and the welding current Iw gradually increases as shown in FIG. To increase. During the arc period from the time t2 to the time t3, as shown in FIG. 5A, the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts and converges to a substantially constant value after decreasing with an inclination. Similarly, as shown in FIG. 5B, the welding current Iw also decreases with a slope and then converges to a substantially constant value. During the period from the time t1 to the time t3, since no gas is ejected, the abnormal state determination signal Ad remains at the low level as shown in FIG.

  During the short circuit period from time t3 to t4, it is the same as the short circuit period from time t1 to t2. In the same figure, it is a case where gas ejection from the molten pool has occurred at time t41 during the arc period from time t4. At time t41, as shown in FIG. 4A, a ripple waveform is generated in which the welding voltage Vw increases sharply and decreases sharply. The second steep ripple waveform is generated at time t42, and the third steep ripple waveform is generated at time t43. When it is determined at time t43 that a predetermined number (three times here) of a steep ripple waveform appears in the welding voltage Vw, the abnormal state determination signal Ad changes to the high level as shown in FIG. The high level state is maintained for a predetermined period (several seconds). Since the short circuit and the arc are repeated about 50 times per second, the High level is maintained during the repetition of the short circuit and the arc about 200 times. When a steep ripple waveform of a predetermined number of times or more appears in the welding voltage Vw during the arc period, the arc is deflected due to gas ejection. The predetermined number of times is set to about 2 to 5 times.

  Next, a method for determining a steep ripple waveform superimposed on the welding voltage Vw will be described. In both of the determination methods shown in (1) and (2) below, it is determined that the rate of change in the welding voltage Vw is equal to or greater than a reference value, and it is determined that a steep ripple waveform has occurred once. When the steep ripple waveform is determined a predetermined number of times, the abnormal state determination signal Ad is changed to the high level.

(1) The welding voltage Vw during the arc period is sampled every predetermined cycle (about 100 μs) and detected as a welding voltage digital value. If the welding voltage digital value at the present time is expressed as Vd (n), the welding voltage digital value two times before the current time is Vd (n-2), and the welding voltage digital value one time before is Vd (n-1). ) The absolute value of Vd (n−2) −Vd (n−1) is less than a predetermined threshold value, and the absolute value of Vd (n) −Vd (n−1) is a predetermined reference. If it is equal to or greater than the value, it is determined that a steep ripple waveform has occurred once. The threshold value is about 0.5 V / 100 μs, and the reference value is about 2 V / 100 μs.

(2) A differential value (absolute value) of the welding voltage Vw during the arc period is calculated. When the welding voltage differential value changes from a substantially zero state to a predetermined reference value or more, it is determined that a steep ripple waveform has occurred once.

In the period before time t43 when the abnormal state determination signal Ad shown in FIG. 5C is at the low level, the first transmittance setting value G1 is set. During the period after time t43 when the abnormal state determination signal Ad is at the high level, the second transmittance setting value is set. G2. As a result, the light transmittance of the light-shielding panel GP is larger in the period in which gas is ejected from the molten pool after time t43 than in the period in which gas is not ejected from the molten pool before time t43. . That is, the light-shielding panel GP becomes bright during the period in which gas ejection is occurring, and the welded portion can be visually observed more clearly.

  According to the second embodiment described above, the light transmittance of the light shielding panel GP is increased when the abnormal state determination signal Ad is output. Visible visually. And in the normal state which occupies most of the welding period, the light transmittance of the light shielding panel GP becomes small, so the burden on the eyes is lightened. The welding operator can recognize the occurrence of gas ejection from the molten pool by the light-shielding panel GP becoming bright during the arc generation, so that the deflected arc follows the weld line under a clear visual condition. In addition, it is easy to move the welding torch.

  In the above description, the transmittance control signal Gc is output to the light-shielding panel in a wired manner, but may be communicated wirelessly. In this case, it is necessary to provide a battery for changing the light transmittance of the light shielding panel on the protective surface.

1 Welding wire (electrode)
2 Base material 3 Arc 4 Welding torch 5 Feed roll AD Abnormal state determination circuit Ad Abnormal state determination signal AD2 Second abnormal state determination circuit CD Energization determination circuit Cd Energization determination signal Fc Feed control signal FM Feed motor G1 First transmission Rate setting value G2 Second transmittance setting value GC Transmittance control circuit Gc Transmittance control signal GP Shading panel HG Protective surface Ib Base current ID Welding current detection circuit Id Current detection signal Ip Peak current Iw Welding current PS Welding power supply SD Short circuit discrimination Circuit Sd Short-circuit discrimination signal ST Torch switch St Welding start signal Vb Base voltage VD Welding voltage detection circuit Vd Voltage detection signal Vp Peak voltage Vw Welding voltage

Claims (3)

Protection equipped with a welding torch that supplies power to the electrode, a welding power source that outputs a welding current and a welding voltage that generates an arc between the electrode and the base material, and a light-shielding panel that protects the eyes of the welding operator from arc light In an arc welding apparatus provided with a surface,
An abnormal state determination unit that determines an abnormal state of an arc generation state and outputs an abnormal state determination signal; and a transmittance control unit that changes the light transmittance of the light-shielding panel when the abnormal state determination signal is input;
An arc welding apparatus comprising: The abnormal state is a state where magnetic blowing occurs.
The arc welding apparatus according to claim 1. The abnormal state is a gas ejection state from the molten pool.
The arc welding apparatus according to claim 1.

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