JP2013163222A - Welding apparatus and welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems that a welding apparatus that achieves both low-spatter welding using a conventional technology for constriction detection and alternating-current welding by an identical apparatus is increased in complexity and becomes expensive.SOLUTION: In a welding apparatus capable of reversal of polarity in output terminals, low-spatter welding is achieved by reversing polarities of output terminals at the timing when a constriction detection unit detects a constriction phenomenon and/or detects a short circuit during arcing, to decrease an output current sharply, thereby providing inexpensively a welding apparatus with a simple configuration which achieves both low-spatter welding and alternating-current welding by a single apparatus.

Description

  The present invention relates to a welding apparatus and a welding method for suppressing generation of spatter using a necking detection technique.

  In recent years, there has been a demand for higher quality of welding quality such as spatter generation, bead appearance, and penetration. In particular, reducing spatter generation improves weld quality and prevents spatter from adhering to the jig, thereby improving maintainability and realizing an improved work environment. As a conventional spatter reduction method, a method is known in which the constriction at the tip of a consumable electrode wire is detected at the end of a short circuit, and the short circuit current is reduced to a predetermined current to reduce spatter that occurs when an arc is regenerated (for example, , See Patent Document 1).

  The conventional sputtering reduction method will be described with reference to FIGS. FIG. 8 shows a schematic configuration of a conventional welding apparatus, and FIG. 9 shows a welding current waveform and a timing chart in which generation of spatter is reduced by detection of constriction.

  In FIG. 8, 23 is a welding apparatus, 1 is a rectification part, 2 is a smoothing capacitor, 3 is an inverter part, 4 is a transformer, 6 is a welding output detection part, 7 is a constriction detection part, 8 is an AS determination part, 10 is a timing unit, 11 is an output terminal, 12 is an output terminal, 13 is a current detection unit, 14a is a rectification unit, 15a is a reactor, 17 is an external device, 18 is a control unit, 19a is a resistance unit, 20 is a base material, 21 is a welding torch, 22 is a welding wire, and TR5a is a fifth switching element.

  In FIG. 9, E1 is the time when necking is detected, E5 is the time when the arc is regenerated from the short-circuit state, E6 is the time when the short-circuit is generated from the arc state, and E10 is the fourth predetermined time T4 after the occurrence of E6. At the time, Is5 indicates a predetermined current value.

  In FIG. 8, the electric power fed from the external device 17 to the welding device 23 is converted into a DC voltage by the rectifying unit 1 and the smoothing capacitor 2, and is suitable for welding via the transformer 4 by the inverter driving of the inverter unit 3. It is converted into high-frequency alternating current, rectified by the rectification unit 14a, and output by the reactor 15a via the fifth switching element TR5a controlled by the control unit 18 or the resistance unit 19a connected in parallel to the fifth switching element TR5a. Smoothed and output from the output terminal 11 and the output terminal 12. Outputs from the output terminal 11 and the output terminal 12 are fed from the power feed tip inside the torch 21 to the welding wire 22 that is a consumable electrode, and an arc is generated between the tip of the welding wire 22 and the base material 20.

  Further, the squeezing detection unit 7 which is a squeezing detection means receives the voltage detection signal from the welding output detection unit 6 and calculates a voltage differential value to reach a preset detection level (for example, 0.5 V / ms). If it is detected, a constriction signal is output as a constriction is detected.

  In FIG. 9, the squeezing detection occurs at the time point E1, and the squeezing signal output from the squeezing detection unit 7 becomes a high level. The control unit 18 that receives the constriction signal from the constriction detection unit 7 operates to shut off (turn off) the fifth switching element TR5a. As a result, the welding current does not flow through the fifth switching element TR5a but flows through the resistance portion 19a, and the current rapidly decreases. At the same time, the inverter unit 3 is controlled by an inverter control unit (not shown), thereby reducing the welding current to a fifth predetermined current value Is5 (for example, 50 A).

At the time point E5 when the AS determination unit 8 that performs the AS determination to determine whether the arc state or the short-circuit state is input with the voltage detection signal from the welding output detection unit 6, the control unit 18 performs the fifth switching. The element TR5a is operated to be turned on (on), the current is sharply increased, and the normal arc control is started.

  In this way, by keeping the current value at the time point E5 at which the arc is regenerated, it is possible to suppress the occurrence of sputtering during the reoccurrence of the arc.

  During the arc, the control unit 18 cuts off the fifth switching element TR5a at time E6 in FIG. 9 in which the AS determination unit 8 that performs the AS determination receives the voltage detection signal from the welding output detection unit 6 and determines the short circuit. Operates to turn off. As a result, since the welding current flows through the resistance portion 19a, the output current rapidly decreases.

  In addition, at the time point E10 after the elapse of the fourth predetermined time T4 by the time counting unit 10, the control unit 18 operates to turn on the fifth switching element TR5a, and performs a predetermined short circuit. The process proceeds to opening control, and a predetermined short-circuit current is output to promote opening of the short-circuit.

  The fourth predetermined time T4 is a control interval of several ms called a short-circuit initial control time. By providing this, a short circuit at the initial stage of the short-circuit is ensured, an unexpected micro short-circuit is reduced, The transition of the droplet formed at the tip of the welding wire 22 to the base material 20 can be ensured, the arc can be stabilized, and the occurrence of spatter can be suppressed.

  Next, AC welding will be described. In recent years, AC welding apparatuses have been realized for the purpose of improving the welding quality of thin plate welding. The AC welding device can reverse the polarity of the output terminal, reverse the polarity of the output current, and alternately repeat the reverse polarity welding and the positive polarity welding to control the heat input to the base material 20. This is effective for welding and gap welding (see, for example, Patent Document 2).

  A conventional AC welding method will be described with reference to FIG. FIG. 10 shows a schematic configuration of a welding apparatus 24 capable of AC welding, and the same components as those in FIG. 8 are denoted by the same reference numerals and detailed description thereof is omitted.

  In FIG. 10, 5 is a control unit, TR1 is a first switching element, TR2 is a second switching element, TR3 is a third switching element, and TR4 is a fourth switching element.

  In FIG. 10, the electric power fed from the external device 17 to the welding device 24 is converted into a DC voltage by the rectifying unit 1 and the smoothing capacitor 2, and is suitable for welding via the transformer 4 by driving the inverter of the inverter unit 3. It is converted into high-frequency alternating current, rectified by the rectifier 14a, and output smoothed by the reactor 15a. The first switching element TR1 and the second switching element TR2 are connected in series on the output side, and the third switching element TR3 and the fourth switching element TR4 are connected in series on the output side. These switching elements are controlled by the control unit 5.

  When reverse polarity welding is performed, the control unit 5 conducts (turns on) the first switching element TR1 and the fourth switching element TR4, and shuts off the second switching element TR2 and the third switching element TR3 ( Off). Then, plus is fed to the output terminal 11, minus is fed to the output terminal 12, plus is fed from the feed tip inside the welding torch 21 to the welding wire 22 that is a consumable electrode, and the tip of the welding wire 22 and minus feed are fed. An arc is generated between the formed base material 20 and the base material 20.

  When positive polarity welding is performed, the first switching element TR1 and the fourth switching element TR4 are cut off (off), and the second switching element TR2 and the third switching element TR3 are made conductive (on). . Then, minus is fed to the output terminal 11, plus is fed to the output terminal 12, minus is fed from the feeding tip inside the welding torch 21 to the welding wire 22 that is a consumable electrode, and the tip of the welding wire 22 and plus feeding are fed. An arc is generated between the formed base material 20 and the base material 20.

  As described above, in AC welding, the polarity of the output terminal is reversed to reverse the polarity of the output current, and welding is performed by alternately repeating reverse polarity welding and positive polarity welding.

  Here, in order to perform low sputter welding realized by the welding apparatus 23 having the configuration shown in FIG. 8 and AC welding realized by the welding apparatus 24 having the configuration shown in FIG. 10 with the same welding apparatus, for example, FIG. As shown, it is conceivable to have a configuration in which both are simply combined.

  FIG. 11 is a diagram showing a schematic configuration of a welding apparatus 25 that simply combines a conventional welding apparatus 23 capable of low spatter welding and a conventional welding apparatus 24 capable of alternating current welding. The welding apparatus 25 of FIG. 11 has a configuration of a fifth switching element TR5a for realizing low spatter welding and a configuration of the first switching element TR1 to the fourth switching element TR4 for realizing AC welding. doing.

  In FIG. 11, the control unit 5 conducts (turns on) the first switching element TR1 and the fourth switching element TR4, cuts off (turns off) the second switching element TR2 and the third switching element TR3, and reverses them. Perform polar welding.

  In order to realize low spatter welding, when the constriction is detected, the control unit 18 shuts off / conducts the fifth switching element TR5a, and rapidly reduces the output current to realize low spatter welding.

  In order to realize AC welding, the control unit 18 conducts (turns on) the fifth switching element TR5a. And the control part 5 carries out alternating current operation | movement of 1st switching element TR1 to 4th switching element TR4, and implement | achieves alternating current welding.

  Next, the example of the welding apparatus 26 at the time of employ | adopting a half bridge for the structure which implement | achieves low spatter welding and alternating current welding is shown using FIG. The same components as those in FIGS. 8 and 10 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 12, 15b indicates a reactor, 14a, 14b, 14c, and 14d indicate rectifiers, 19b indicates a resistor, and TR5b indicates a sixth switching element. And similarly to the structure of FIG. 11, low spatter welding and AC welding can be realized by the same welding apparatus.

JP 2006-122912 A JP 58-38664 A

However, in order to perform low spatter welding that can be realized by the configuration shown in FIG. 8 and AC welding that can be realized by the configuration shown in FIG. 10 with one welding apparatus, as shown in FIG. 11 and FIG.
If the configuration of FIG. 10 and the configuration of FIG. 10 are simply combined, there is a problem that the welding apparatus becomes very complicated and expensive.

  An object of the present invention is to provide a welding apparatus capable of performing low spatter welding and AC welding at a low cost with a simple configuration.

In order to solve the above-mentioned problems, a welding apparatus according to the present invention is a welding apparatus capable of reversing the polarity of an output terminal, based on a welding output detection unit that detects a welding output and a detection result of the welding output detection unit. And an arc / short circuit determination unit for determining an arc / short circuit, and the polarity of the output terminal is reversed when the arc / short circuit determination unit detects that the short period has been reached from the arc period.

  In addition to the above, the welding apparatus of the present invention further includes a time measuring unit for measuring time, and detects that the arc / short-circuit determining unit has changed from the arc period to the short-circuit period to perform polarity reversal of the output terminal. When the second predetermined time elapses, the polarity of the output terminal is reversed again.

  In addition to the above, the welding apparatus of the present invention further includes an output current determination unit that determines that the output current has reached a predetermined value or less based on the detection result of the welding output detection unit. The output terminal is detected again when the output current determination unit determines that the output current has reached a third predetermined value or less after detecting that the arc period has become a short-circuit period and inverting the polarity of the output terminal. Polarity inversion.

  In addition to the above, the welding apparatus of the present invention has an output current detected by the welding output detection unit at the time when the arc / short-circuit determination unit detects that the arc period has changed to the short-circuit period to a fourth predetermined value or more. In this case, the polarity of the output terminal is not reversed even if the arc / short-circuit determination unit detects a short circuit during the arc period.

  In addition to the above, the welding apparatus of the present invention, in addition to the above, a rectification unit that rectifies the input power, an inverter unit that converts the output of the rectification unit into alternating current, a transformer that transforms the output of the inverter unit, A first switching element and a second switching element connected in series to the output side of the transformer; a third switching element and a fourth switching element connected in series to the output side of the transformer; A control unit that controls the operation of the fourth switching element from one switching element, and when the control unit performs reverse polarity output, the control unit controls the first switching element and the fourth switching element. When conducting a welding output by cutting off the second switching element and the third switching element and performing a positive output, the first switching element and the front Blocks the fourth switching element, and performs welding output by conduction and the second switching element and the third switching element.

  In addition to the above, the welding apparatus of the present invention, in addition to the above, a rectification unit that rectifies the input power, an inverter unit that converts the output of the rectification unit into alternating current, a transformer that transforms the output of the inverter unit, A first switching element and a second switching element connected in series to the output side of the transformer; and a control unit that controls operations of the first switching element and the second switching element. The unit conducts the first switching element when performing reverse polarity output, interrupts the second switching element to perform welding output, and performs positive output when performing the first output. The switching element is cut off and the second switching element is conducted to perform welding output.

  Further, the welding method of the present invention is a welding method for performing welding using a welding apparatus capable of reversing the polarity of the output terminal, the step of detecting the welding output, and the arc period based on the detection result of the welding output Or a short-circuit period, and a step of reversing the polarity of the output terminal when it is detected that the short-circuit period has been reached from the arc period.

  As described above, the welding apparatus of the present invention is a welding apparatus capable of reversing the polarity of the output terminal, and detects the welding output and detects the welding output, and immediately before opening the short circuit based on the detection result of the welding output detecting part. A squeezing detection unit that detects the squeezing phenomenon, and when the squeezing detection unit detects the squeezing phenomenon, the polarity of the output terminal is reversed to reduce the welding current and perform low spatter welding. It can be realized at low cost.

The figure which shows schematic structure of the welding apparatus in embodiment of this invention. The figure which shows schematic structure of the welding apparatus in embodiment of this invention. The figure which shows the time change of the welding current in Embodiment 1 of this invention, an arc / short circuit signal, a constriction signal, and the drive signal of a switching element. The figure which shows schematic structure of the welding apparatus in Embodiment 2 of this invention. The figure which shows the time change of the welding current in Embodiment 2 of this invention, an arc / short circuit signal, a constriction signal, and the drive signal of a switching element. The figure which shows the time change of the welding current in Embodiment 3 of this invention, an arc / short circuit signal, a constriction signal, and the drive signal of a switching element. The figure which shows the time change of the welding current in Embodiment 4 of this invention, an arc / short circuit signal, a constriction signal, and the drive signal of a switching element. The figure which shows schematic structure of the conventional welding apparatus The figure which shows the time change of the welding current in a conventional welding apparatus, an arc / short circuit signal, a constriction signal, and the drive signal of a switching element. The figure which shows schematic structure of the conventional welding apparatus The figure which shows schematic structure of the conventional welding apparatus The figure which shows schematic structure of the conventional welding apparatus

(Embodiment 1)
This embodiment will be described with reference to FIGS. 1 and 2 are diagrams showing a schematic configuration of a welding apparatus in the present embodiment. FIG. 1 shows a configuration using a full bridge, and FIG. 2 shows a configuration using a half bridge. The operation of the welding apparatus shown in FIGS. 1 and 2 will be described with reference to FIG. FIG. 3 is a diagram illustrating temporal changes in the welding current, the arc / short-circuit signal, the constriction signal, and the driving signal of the switching element.

  Hereinafter, a consumable electrode type arc welding apparatus that performs welding by repeating short-circuiting and arcing will be described.

  1 and 2, 1 is a rectifying unit, 2 is a smoothing capacitor, 3 is an inverter unit, 4 is a transformer, 5 is a control unit, 6 is a welding output detection unit, 7 is a constriction detection unit, 8 Is an AS determination unit, 10 is a timing unit, 11 is an output terminal, 12 is an output terminal, 13 is a current detection unit, 14a, 14b, 14c and 14d are rectification units, 15a and 15b are reactors, 17 is an external device, 20 is The base metal, 21 is a welding torch, 22 is a welding wire, TR1 is a first switching element, TR2 is a second switching element, TR3 is a third switching element, and TR4 is a fourth switching element.

In FIG. 3, E1 is a time point when the necking is detected, E2 is a time point when the first predetermined period T1 has elapsed from the time point E1, E4 is a time point when the output current reaches the first predetermined current value Is1, and E5 is short-circuited. When the arc is regenerated from the state, E6 is when the short circuit occurs, E7 is when the second predetermined period T2 has elapsed from time E6, E9 is when the output current reaches the second predetermined current value Is2, E10 indicates the time when the third predetermined period T3 has elapsed from the time point E6, T1 is the first predetermined period, T2 is the second predetermined period, T3 is the third predetermined period, and Is1 is the first predetermined period. Current value,
Is2 indicates a second predetermined current value, Is3 indicates a third predetermined current value, and Is4 indicates a fourth predetermined current value.

In FIG. 1, which is a welding device 27 using a full bridge, a commercial power input (200 V) fed from an external device 17 such as a switchboard is a smoothing circuit composed of a rectifying unit 1 composed of a diode or the like and an electrolytic capacitor. It is converted into a DC voltage by the capacitor 2. Then, an IGBT (Insulated Gate Bipolar Transistor) and a MOSFET (Metal-Oxide Semiconductor Fielder) driven by a PWM (Pulse Wide Modulation) operation or a phase shift operation.
By the inverter drive of the inverter part 3 comprised by Effect Transistor etc., it converts into the high frequency alternating current suitable for welding via the transformer 4. FIG. Then, the current is rectified by a rectification unit 14a composed of a diode or the like, and output smoothed by the reactor 15a.

  The output smoothed by the reactor 15a is output from the first switching element TR1 constituting the full bridge via the fourth switching element TR4. The first switching element TR1 to the fourth switching element TR4 are composed of IGBTs, MOSFETs or the like. The first switching element TR1 and the second switching element TR2 are connected in series on the output side, and the third switching element TR3 and the fourth switching element TR4 are connected in series on the output side. The first switching element TR1 to the fourth switching element TR4 are controlled by a control unit 5 including a CPU (Central Processing Unit) and a driver.

  When reverse polarity welding is performed, the control unit 5 conducts (turns on) the first switching element TR1 and the fourth switching element TR4, and shuts off the second switching element TR2 and the third switching element TR3 ( Off), a positive power is supplied to the output terminal 11, and a negative power is supplied to the output terminal 12. Then, plus is fed to the welding wire 22 which is a consumable electrode through a feeding tip (not shown) provided inside the welding torch 21, and an arc is generated between the tip of the welding wire 22 and the negatively fed base material 20. Welding is generated.

  Here, reverse polarity welding refers to a case where the moving direction of electrons in the arc plasma is the direction from the base material 20 to the welding wire 22, the welding wire 22 is positive, and the base material 20 is negative. Positive polarity welding refers to a case where the moving direction of electrons in the arc plasma is the direction from the welding wire 22 to the base material 20, and the welding wire 22 is normally negative and the base material 20 is positive. .

  The welding output detection part 6 detects the welding output voltage output from the output terminal 11 and the output terminal 12, and detects the welding current output detected by the current detection part 13 comprised by CT (Current Transformer) etc.

  A squeezing detection unit 7 including a CPU, which is a squeezing detection means, receives a voltage detection signal from the welding output detection unit 6 and calculates a voltage differential value, and sets a preset detection level (for example, 0. 0). 5V / ms), a constriction signal is output as a constriction is detected.

  An AS determination unit 8 composed of a CPU or the like that performs AS (Arc / Short) determination uses a voltage detection signal from the welding output detection unit 6 as an input, and a detection level ( For example, when the voltage reaches 15V), the AS signal is set to arc determination (High level). Further, when a preset detection level (for example, 10 V) lower than the arc detection level is reached during the arc determination, the AS signal is set as a short circuit determination (Low level).

When the squeezing detection occurs at the time point E1 shown in FIG. 3, the squeezing signal output from the squeezing detection unit 7 becomes a high level. Upon receiving the squeezing signal from the squeezing detection unit 7, the control unit 5 reverses the polarity of the welding output so that the driving signal is a driving signal from the first switching element TR1 to the fourth switching element TR4 shown in FIG. TR1, drive signal TR2, drive signal TR3, and drive signal TR4 are output, the first switching element TR1 and the fourth switching element TR4 are cut off (off), and the second switching element TR2 and the third switching element TR3 are output. Is connected (turned on), minus is fed to the output terminal 11, and plus is fed to the output terminal 12.

  As a result, the polarity of the welding current is reversed, the polarity is changed from the reverse polarity to the positive polarity, and the welding current viewed from the reverse polarity side is rapidly reduced. At the same time, the inverter unit 3 is controlled by an inverter control unit (not shown), and the welding current is controlled to be a third predetermined current value Is3 (for example, −50 A when viewed from the reverse polarity side).

  In FIG. 3, when the drive signals TR1 to TR4 are at a high level, the switching elements TR1 to TR4 are turned on (turned on).

  In this way, when the constriction of the short-circuit open straight line is detected, the polarity of the output of the welding device 27 is reversed to rapidly reduce the welding current, thereby reducing spatter during transition from the short circuit to the arc.

  As shown in FIG. 3, from the time point E <b> 1 when the constriction is detected, the time measuring unit 10 configured by a timer or the like counts time, and at a time point E <b> 2 when a preset first predetermined period T <b> 1 elapses, the control unit 5. Outputs the driving signal TR1, the driving signal TR2, the driving signal TR3, and the driving signal TR4, and the first switching element TR1 and the fourth switching element TR4 are made conductive (turned on) in order to reverse the polarity again. The switching element TR2 and the third switching element TR3 are cut off (off), and a positive power is supplied to the output terminal 11, and a negative power is supplied to the output terminal 12.

  As a result, the welding current shifts from positive polarity to reverse polarity. At the same time, the inverter unit 3 is controlled so that the welding current becomes a first predetermined current value Is1 (for example, 50 A when viewed from the reverse polarity side).

  In FIG. 3, the arc is not regenerated at the time point E4 when the output current reaches the first predetermined current value Is1, and in this case, the welding output is set to the first predetermined current value Is1 until the arc is regenerated. Control. At the time point E5 when the arc is regenerated from the short-circuit state, the AS determination unit 8 determines that the arc has occurred, and controls the inverter unit 3 by an inverter control unit (not shown) that receives the signal from the AS determination unit 8. Transition to predetermined arc control.

  As described above, by keeping the absolute value of the first predetermined current value Is1 low at the time point E5 when the arc is regenerated, the occurrence of spatter during the arc reoccurrence can be suppressed.

  Further, by shortening the first predetermined period T1 (for example, 100 us or less), the first switching element TR1 to the fourth switching element TR4 are reversed with sufficient time until the time point E5 when the arc is regenerated. It is possible to switch to the polarity side, and to prevent an arc period from occurring during switching, and at the time point E5, stable reverse polarity output can be performed, and at the time of arc regeneration at the time point E5 Arc breakage can be prevented.

In general, in order for the first switching element TR1 to the fourth switching element TR4 to perform switching completely, several us to several tens of us are required. And when switching is not perfect, the output of the inverter part 3 cannot fully be transmitted to the output terminal 11 or the output terminal 12. FIG. Therefore, when a large output is required during switching, the output power may be insufficient, causing arc interruption.

  In the above, an example in which the polarity of the output terminal 11 and the output terminal 12 is reversed and the welding current is suddenly reduced to suppress spatter when the constriction at the end of the short circuit is detected has been described. An example will be described in which the polarity of the output terminal 11 and the output terminal 12 is reversed when the occurrence of the short circuit is detected and the welding current at the initial stage of the short circuit is suddenly reduced to suppress spatter when the arc state is changed to the short circuit state.

  In FIG. 3, at the time point E6 when the short circuit occurs from the arc, the AS determination unit 8 determines the short circuit and outputs an AS signal indicating that the short circuit has occurred. The control unit 5 that has received the AS signal indicating the short circuit from the AS determination unit 8 outputs the drive signal TR1, the drive signal TR2, the drive signal TR3, and the drive signal TR4 in order to reverse the polarity, and the first switching element TR1 and the first switching element TR1. 4 switching element TR4 is cut off (off), second switching element TR2 and third switching element TR3 are made conductive (on), minus is fed to output terminal 11, and plus is fed to output terminal 12. .

  As a result, the polarity of the welding current is reversed and the polarity changes from reverse polarity to positive polarity, and the welding current viewed from the reverse polarity side decreases rapidly. At the same time, the inverter unit 3 is controlled to control the welding current to a predetermined current value Is4 (for example, −50 A when viewed from the reverse polarity side).

  As shown in FIG. 3, the time counting unit 10 counts time from the time point E6 at which the short circuit determination is made, and the control unit 5 reverses the polarity at the time point E7 when a second predetermined period T2 is set in advance. The drive signal TR1, the drive signal TR2, the drive signal TR3, and the drive signal TR4 are output, the first switching element TR1 and the fourth switching element TR4 are turned on, and the second switching element TR2 and the third switching element are switched on. The element TR3 is shut off (off), plus is supplied to the output terminal 11, and minus is supplied to the output terminal 12.

  As a result, the welding current shifts to the reverse polarity. At the same time, the inverter unit 3 is controlled, the welding current is controlled to a second predetermined current value Is2 (for example, 50 A), and the welding output is set to the second predetermined current value Is2 during the third predetermined period T3. Control, at a time point E10 after the elapse of the third predetermined period T3, the process shifts to a predetermined short circuit opening control, outputs a predetermined short circuit current, and promotes the opening of the short circuit.

  After the occurrence of a short circuit at the time point E6, the welding current is rapidly reduced, and a short circuit at the initial stage of the short circuit is ensured by providing a control period of a third predetermined period T3 called a short circuit initial control time so that the current is low. The transfer of the droplets to the base metal can be ensured, the arc can be stabilized, and the occurrence of spatter can be suppressed.

  In the above, an example of direct current welding for performing reverse polarity output has been described. However, in the configuration of FIG. 1, when alternating current welding is performed, the control unit 5 performs the first switching element TR1 to the fourth switching element TR4. It is possible to realize this by controlling the switching operation to alternately repeat the positive polarity and the reverse polarity.

As described above, the output current can be rapidly reduced by reversing the polarity of the output terminal 11 and the output terminal 12 when the constriction occurs. And generation | occurrence | production of a sputter | spatter can be suppressed by keeping the absolute value of the electric current value at the time of arc reproduction | regeneration low. Further, the output current can be rapidly reduced by reversing the polarity of the output terminal 11 and the output terminal 12 when a short circuit occurs. And it is possible to ensure the short circuit at the initial stage of the short circuit, stabilize the arc, and suppress the occurrence of sputtering. Thus, a welding apparatus capable of performing low spatter DC welding and AC welding can be realized. Then, as in the prior art, by controlling the switching from the first switching element TR1 to the fourth switching element TR4 without providing a resistor and a switching element provided in parallel with the resistor in order to rapidly reduce the current, The current can be rapidly decreased, and the rapid decrease of the current can be realized at low cost.

  In the present embodiment, an example in which welding is performed with reverse polarity as normal has been described, but similar control can be performed and similar effects can be obtained even when welding is performed with normality as normal.

  In FIG. 3 of the present embodiment, an example in which the configuration of the full bridge shown in FIG. 1 is used as the configuration for realizing the polarity inversion of the output is shown, but the configuration for realizing the AC output as shown in FIG. Alternatively, a half-bridge configuration may be used. With regard to polarity inversion, for example, from the state where the first switching element TR1 is turned on and the second switching element TR2 is turned off, the first switching element TR1 is turned off and the second switching element TR2 is turned on. Thus, the polarity can be reversed.

  In the present embodiment, as shown in FIG. 1, the first switching element TR1 to the fourth switching element TR4 are singly arranged. However, as a countermeasure against current capacity and heat, the switching element It is good also as a structure which has arranged two or more in parallel.

  In addition, when the short circuit current at the time point E1 when the squeezing detection shown in FIG. 3 occurs exceeds a third current threshold I3 (for example, 400 A) (not shown), or when the short circuit shown in FIG. When the current exceeds a third current threshold I3 (not shown) (for example, 400 A), the polarity inversion operation may be invalidated, and the output current is reduced by controlling the inverter unit 3 and the output current The polarity reversal processing may be performed when the current becomes the third current threshold I3 (for example, 400 A) or less.

  By performing such control, it becomes possible to protect the peripheral elements from being damaged by the surge voltage generated when the polarity of the first switching element TR1 to the fourth switching element TR4 is reversed.

  Here, the third current threshold I3 affects the surge voltage generated at the time of polarity reversal. The surge voltage tends to decrease as the third current threshold I3 is lower. However, in order to obtain the effect of the present embodiment, it is necessary to perform polarity reversal at the time when the constriction is detected. Therefore, it is necessary to set the third current threshold I3 to a value as high as possible. The allowable surge voltage value is affected by the reliability rating, switching speed, and peripheral snubber circuit configuration of the IGBTs and MOSFETs constituting the first switching element TR1 to the fourth switching element TR4. Taking these into account, the third current threshold I3 can be obtained experimentally, for example.

  The third current threshold I3 may be a fixed value (for example, 400 A), or the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the set current of the welding current. It is good also as a function calculated | required based on at least one.

  In the present embodiment, the example in which the first switching element TR1 to the fourth switching element TR4 are simultaneously inverted has been described. However, before and after the polarity is inverted, the semiconductor element has a short time (for example, 50 us). For the purpose of surge protection and arc break countermeasures, the first switching element TR1 and the second switching element TR2 are simultaneously turned on (turned on) or simultaneously cut off (off), or the third switching element TR3 and the fourth switching element are turned off. TR4 may be simultaneously turned on (on) or simultaneously cut off (off).

Further, the first predetermined period T1, the second predetermined period T2, the third predetermined period T3, the first predetermined current value Is1, the second predetermined current value Is2, and the third predetermined current value Is3 shown in FIG. The optimum value of the fourth predetermined current value Is4 can be determined by experiments or the like according to the welding object, welding conditions, and the like.

  The first predetermined period T1 may be a fixed value (for example, 100 us), or may be a function of the welding current at the time point E1 when the constriction detecting unit 7 detects the constriction (for example, set to 100 us when detecting at 150 A). The function may be obtained from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the set current of the welding current.

  Further, the second predetermined period T2 may be a fixed value (for example, 200 us), or may be a function of the welding current at the time point E6 when the AS determination unit 8 detects a short circuit (for example, set to 200 us when detected at 200 A). The function may be obtained from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the set current of the welding current.

  The third predetermined period T3 may be a fixed value (for example, 1500 us), or may be a function of the welding current at the time point E6 when the AS determination unit 8 detects a short circuit (for example, set to 1500 us when detected at 200 A). The function may be obtained from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the set current of the welding current.

  Note that the first predetermined current value Is1 may be a fixed value (for example, 50 A), and a function of the welding current at the time point E1 when the squeezing detection unit 7 detects squeezing (for example, set to 50 A when detected at 250 A). Alternatively, it may be a function obtained from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the welding current setting current.

  The second predetermined current value Is2 may be a fixed value (for example, 50 A), and is set to a function of the welding current at the time point E6 when the AS determination unit 8 detects a short circuit (for example, 50 A when detected at 200 A). Or a function obtained from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire projection length, the shield gas to be supplied, and the set current of the welding current.

  The third predetermined current value Is3 may be a fixed value (for example, −50 A as viewed from the reverse polarity side), and is detected by a function of the welding current (for example, 250 A) at the time point E1 when the necking detection unit 7 detects the necking. In this case, it may be set to −50 A as viewed from the reverse polarity side), and from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the welding current It may be a function to be obtained.

  The fourth predetermined current value Is4 may be a fixed value (for example, −50 A as viewed from the reverse polarity side), and is a function of the welding current (for example, detected at 200 A) when the AS determination unit 8 detects a short circuit. In this case, it may be set to −50 A as viewed from the reverse polarity side), and from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the welding current It may be a function to be obtained.

  Note that the predetermined current value Is1 and the predetermined current value Is3 may have a relationship of Is3 = −Is1.

Further, the predetermined current value Is2 and the predetermined current value Is4 may have a relationship of Is4 = −Is2.

(Embodiment 2)
In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. The main difference from the first embodiment is that an output current determination unit 9 is provided, and the polarity is reversed, but the polarity is reversed again in a period of reverse polarity without the current having a positive polarity. Is a point.

  The welding apparatus of this Embodiment is demonstrated using FIG. 4 and FIG. FIG. 4 is a diagram showing a schematic configuration of the welding apparatus 29 according to the present embodiment. In FIG. 4, reference numeral 9 denotes an output current determination unit that determines the magnitude of the output current detected by the welding output detection unit 6. FIG. 5 is a diagram illustrating temporal changes in the welding current, the arc / short-circuit signal, the constriction signal, and the driving signal of the switching element. In FIG. 5, I1 is the first current threshold, I2 is the second current threshold, E3 is the time when the output current reaches the first current threshold I1, and E8 is the output current reaches the second current threshold I2. Indicates the time.

  When the squeezing detection occurs at the time point E1 in FIG. 5, the squeezing signal output from the squeezing detection unit 7 becomes a high level. Upon receiving the squeezing signal from the squeezing detection unit 7, the control unit 5 outputs a drive signal TR1, a drive signal TR2, a drive signal TR3, and a drive signal TR4 to invert the polarity, and the first switching element TR1 and the fourth switch The switching element TR4 is cut off (off), the second switching element TR2 and the third switching element TR3 are made conductive (on), minus is fed to the output terminal 11, and plus is fed to the output terminal 12. As a result, the polarity of the welding current is reversed, and the welding current viewed from the reverse polarity side decreases rapidly in an attempt to shift from reverse polarity to positive polarity.

  As shown in FIG. 5, the output current determination unit 9 configured by a CPU or the like that receives a current detection signal from the welding output detection unit 6 suddenly decreases from the time point E <b> 1 when the constriction is detected. It is determined that the first current threshold value I1 to be set (for example, 75 A in reverse polarity) has been reached. At the time point E3 when the output current reaches the first current threshold I1, the control unit 5 inverts the polarities of the output terminal 11 and the output terminal 12, so that the drive signal TR1, the drive signal TR2, the drive signal TR3, and the drive signal TR4 are reversed. Is output, the first switching element TR1 and the fourth switching element TR4 are made conductive (ON), the second switching element TR2 and the third switching element TR3 are interrupted (OFF), and a plus is applied to the output terminal 11. Power is supplied, and minus is supplied to the output terminal 12. As a result, the welding current shifts to the reverse polarity.

  In the present embodiment, after the polarity of the output terminal 11 and the output terminal 12 is reversed at the time point E1 when the constriction is detected, the time point E3 at which the output current becomes the first current threshold value I1 before shifting from the reverse polarity to the positive polarity. Then, the polarity of the output terminal is reversed again. The slope at which the output current sharply decreases after the polarity reversal of the output terminal is affected by the state of the impedance of the welding path such as the welding torch 21 and the base material 20 and the reactor 15a.

  Therefore, after the polarity of the output terminal is reversed, it takes a certain time (several hundreds of us or less) until the polarity of the output current is actually reversed. The time from the polarity reversal of the output terminal to the next polarity reversal is required. In the case of shortening (for example, 50 us), the welding current may not reach 0 A and the output current may not reverse in polarity as in the present embodiment shown in FIG.

At the time point E3 when the output current reaches the first current threshold value I1, the polarity is reversed, and at the same time, the inverter unit 3 is controlled to control the welding current to the first predetermined current value Is1 (for example, 50 A). In FIG. 5, arc regeneration is not performed at the time point E4 when the output current reaches the first predetermined current value Is1, and in this case, the welding output is constant at the first predetermined current value Is1 until the arc is regenerated. To control the current.

  Further, at the time point E5 when the arc is regenerated from the short-circuit state, the AS determination unit 8 determines the arc and shifts to a predetermined arc control. In this way, by keeping the absolute value of the first predetermined current value Is1 at the time point E5 when the arc is regenerated, the occurrence of sputtering during the reoccurrence of the arc can be suppressed.

  Next, control in the initial stage of a short circuit from the arc state to the short circuit state will be described.

  In FIG. 5, at the time point E6 when a short circuit occurs during the arc period, the AS determination unit 8 determines that a short circuit has occurred. The control unit 5 that has received the AS signal that is the short circuit determination from the AS determination unit 8 outputs the drive signal TR1, the drive signal TR2, the drive signal TR3, and the drive signal TR4 to invert the polarity, and the first switching element TR1. And the fourth switching element TR4 are cut off (off), the second switching element TR2 and the third switching element TR3 are made conductive (on), minus is fed to the output terminal 11, and plus is given to the output terminal 12. Supply power.

  As a result, the welding current reverses in polarity and tries to shift from reverse polarity to positive polarity, and the welding current as seen from the reverse polarity side rapidly decreases.

  As shown in FIG. 5, from the time point E6 when the short-circuit occurs and the current suddenly starts to decrease, the output current determination unit 9 starts the second current threshold I2 (for example, 75A with reverse polarity) in which the output current is preset. It is determined that has been reached.

  At the time point E8 when the output current reaches the second current threshold value I2, the control unit 5 outputs the drive signal TR1, the drive signal TR2, the drive signal TR3, and the drive signal TR4 to invert the polarity, and the first switching is performed. The element TR1 and the fourth switching element TR4 are made conductive (ON), the second switching element TR2 and the third switching element TR3 are cut off (OFF), positive is supplied to the output terminal 11, and negative is applied to the output terminal 12. Power.

  As a result, the welding current shifts from positive polarity to reverse polarity. At the same time, the inverter unit 3 is controlled so that the welding current becomes a second predetermined current value Is2 (for example, 50 A). During the third predetermined period T3, the current is controlled to the second predetermined current value Is2, and at a time point E10 after the elapse of the third predetermined period T3, the control proceeds to the predetermined short-circuit opening control and the predetermined short-circuit current is set. Output and promote the opening of short circuit. After the occurrence of a short circuit at time E6, the welding current is sharply reduced, and a control section of the third predetermined period T3 is provided to ensure a short circuit at the initial stage of the short circuit and to ensure the transfer of droplets to the base material 20 The arc can be stabilized and the occurrence of spatter can be suppressed.

  In addition, as described with reference to FIG. 1 in the first embodiment, in order to perform AC welding, in FIG. 5, the control unit 5 changes the first switching element TR1 to the fourth switching element TR4. This can be realized by controlling the positive polarity / reverse polarity alternately.

  As described above, by reversing the polarity of the output terminal when constriction occurs, the current can be rapidly reduced, and the occurrence of spatter can be suppressed by keeping the absolute value of the current value during arc regeneration low. By reversing the polarity of the output terminal when a short circuit occurs, the current can be drastically reduced, the short circuit at the initial stage of the short circuit can be ensured, the arc can be stabilized, and the occurrence of spatter can be suppressed. A welding apparatus capable of AC welding can be realized at low cost.

  Note that the optimum values of the first current threshold value I1 and the second current threshold value I2 may be determined by experiments or the like according to the welding object, welding conditions, and the like.

  Note that the first current threshold I1 may be a fixed value (for example, 75A), as a function of the welding current at the time point E1 when the squeezing detection unit 7 detects squeezing (for example, set to 75A when detected at 250A). Alternatively, it may be a function obtained from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the set current of the welding current.

  The second current threshold I2 may be a fixed value (for example, 75 A), or may be a function of the welding current at the time point E6 when the AS determination unit 8 detects a short circuit (for example, set to 75 A when detected at 200 A). The function may be obtained from at least one of the wire diameter of the consumable electrode wire to be fed, the wire type, the wire protrusion length, the shield gas to be supplied, and the set current of the welding current.

  Note that, when the squeezing detection unit 7 detects the squeezing, the time when the polarity of the output terminal is reversed after the squeezing is detected, and the time when the polarity of the output terminal is reversed again, as shown in FIG. Counts the time, E2 when a first predetermined period T1 is set in advance, and, as shown in FIG. 5, the current detection signal from the welding output detector 6 is input and output from the time point E1 when the squeezing is detected. It may be a point in time when either one of the time point E3 when the current determination unit 9 determines that the output current has reached a preset first current threshold value I1 (for example, 75 A in reverse polarity), or It may be a time point when both the time point E2 and the time point E3 occur, that is, a time point that occurs later at the time points E2 and E3.

  In addition, from the time E6 when the polarity of the output terminal is reversed when the AS determination unit 8 detects a short circuit during the arc period, the time when the polarity of the output terminal is reversed again is as shown in FIG. From the time point E7 when the time counting unit 10 counts the time and the preset second predetermined period T2 elapses, and the current from the welding output detection unit 6 from the time point E6 when the short circuit occurs as shown in FIG. One of the time points E8 occurs when the detection signal is input and the output current determination unit 9 determines that the output current has reached a preset second current threshold value I2 (for example, 75 A in reverse polarity). It may be a time point, or may be a time point when both time point E7 and time point E8 occur, that is, a time point that occurs later at time point E7 and time point E8.

(Embodiment 3)
In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The main difference from the first embodiment is that the polarity is reversed again when a short circuit is detected from the arc state after the constriction is detected and the polarity is reversed.

  The welding apparatus according to the present embodiment will be described with reference to FIGS. 1, 3, 5, and 6. FIG. 6 is a diagram showing temporal changes in the welding current, the arc / short-circuit signal, the constriction signal, and the driving signal of the switching element.

  When the squeezing detection occurs at the time point E1 in FIG. 6, the squeezing signal output from the squeezing detection unit 7 becomes a high level. The control unit 5 that receives the squeezing signal from the squeezing detection unit 7 outputs a driving signal TR1, a driving signal TR2, a driving signal TR3, and a driving signal TR4 in order to invert the polarity. The switching element TR4 is cut off (off), the second switching element TR2 and the third switching element TR3 are made conductive (on), minus is fed to the output terminal 11, and plus is fed to the output terminal 12.

  As a result, the polarity of the welding current is reversed and the polarity changes from reverse polarity to positive polarity, and the welding current viewed from the reverse polarity side decreases rapidly. At the same time, the inverter unit 3 is controlled to control the welding current to a third predetermined current value Is3 (for example, −50 A when viewed from the reverse polarity side).

  Then, the AS determination unit 8 sets the AS signal to (High) at the time point E5 when the arc determination is determined, and the control unit 5 that has received the AS signal inverts the polarity, and thus the drive signal TR1, the drive signal TR2, and the drive signal TR3. The drive signal TR4 is output, the first switching element TR1 and the fourth switching element TR4 are turned on (on), the second switching element TR2 and the third switching element TR3 are shut off (off), and output. The terminal 11 is fed with plus and the output terminal 12 is fed with minus.

  As a result, the welding current shifts to the reverse polarity. At the same time, it shifts to predetermined arc control.

  As described above, by keeping the absolute value of the third predetermined current value Is3 at the time point E5, which is the time point at which the arc is regenerated, the occurrence of sputtering at the time of arc reoccurrence can be suppressed.

  In addition, from the time point E1 when the polarity of the output terminal is reversed when the necking detection unit 7 detects the necking, the time point when the polarity of the output terminal is reversed again, as shown in FIG. Counts the time, E2 when a first predetermined period T1 is set in advance, and, as shown in FIG. 5, the current detection signal from the welding output detector 6 is input and output from the time point E1 when the squeezing is detected. From the time point E3 when the current determination unit 9 determines that the output current has reached a preset first current threshold value I1 (for example, 75A with reverse polarity), and from the time point E1 when the constriction is detected as shown in FIG. Of the time point E5 at which the arc is determined, either the time point E2 or the time point E5 may be generated, or the time point E3 or the time point E5 may be generated.

  As described above, in the present embodiment, by reversing the polarity at the time point E5, which is the reoccurrence time of the arc, even when the arc is instantaneously regenerated after detecting the constriction, the reverse polarity state can be maintained. No construction problems occur. That is, when the arc period is changed from the short-circuit period, the arc state is not reversed without reversing the polarity, and the polarity is always reversed when the arc period is changed from the short-circuit period.

(Embodiment 4)
In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The main difference from the first embodiment is that positive polarity welding is performed during a short circuit, reverse polarity is reversed when constriction is detected during short circuit, reverse polarity welding is performed during arcing, and the arc period ends. When a short circuit is detected, the polarity is reversed and positive polarity welding is performed.

  The operation of the welding apparatus shown in FIG. 1 will be described with reference to FIG. FIG. 7 is a diagram showing temporal changes in the welding current, the arc / short-circuit signal, the constriction signal, and the driving signal of the switching element.

  As shown in FIG. 7, at the time point E6 when a short circuit occurs in the arc, the control unit 5 shuts off (turns off) the first switching element TR1 and the fourth switching element TR4, and the second switching element TR2 The third switching element TR3 is turned on (on), minus is fed to the output terminal 11, plus is fed to the output terminal 12, and positive output is performed.

  When the squeezing detection occurs at the time point E1 in FIG. 7, the squeezing signal output from the squeezing detection unit 7 becomes a high level. The control unit 5 receiving the squeezing signal from the squeezing detection unit 7 outputs the drive signal TR1, the drive signal TR2, the drive signal TR3, and the drive signal TR4 in order to reverse the polarity, and the first switching element TR1 and the fourth switch The switching element TR4 is made conductive (ON), the second switching element TR2 and the third switching element TR3 are cut off (OFF), plus is fed to the output terminal 11, and minus is fed to the output terminal 12.

  As a result, the welding current as seen from the positive polarity side decreases rapidly, and the welding current shifts to the reverse polarity. At the same time, the inverter unit 3 is controlled to control the welding current to the first predetermined current value Is1 (for example, 50 A when viewed from the reverse polarity side).

  In FIG. 7, the arc is not regenerated at the time point E4 when the output current reaches the first predetermined current value Is1, and in this case, the welding output is kept constant at the first predetermined current value Is1 until the arc is regenerated. To control the current.

  At time E5 when the arc is regenerated from the short-circuit state, the AS determination unit 8 determines the arc and shifts to predetermined arc control. As described above, by keeping the absolute value of the first predetermined current value Is1 at the time point E5, which is the time point at which the arc is regenerated, the occurrence of sputtering at the time of arc reoccurrence can be suppressed.

  In FIG. 7, at the time point E <b> 6 when a short circuit occurs during the arc period, the AS determination unit 8 determines a short circuit, and the control unit 5 that receives the AS signal that is the short circuit determination from the AS determination unit 8 reverses the polarity. , Drive signal TR1, drive signal TR2, drive signal TR3, and drive signal TR4 are output, the first switching element TR1 and the fourth switching element TR4 are cut off (off), and the second switching element TR2 and the third switching element TR4 are output. The switching element TR3 is made conductive (turned on), negative power is supplied to the output terminal 11, and positive power is supplied to the output terminal 12.

  As a result, the polarity of the welding current is reversed and the polarity changes from reverse polarity to positive polarity, and the welding current viewed from the reverse polarity side decreases rapidly. At the same time, the inverter unit 3 is controlled to control the welding current to a fourth predetermined current value Is4 (for example, −50 A when viewed from the reverse polarity side). During the period of the third predetermined period T3, the welding output is controlled at a constant current to the fourth predetermined current value Is4, and at a time point E10 after the elapse of the third predetermined period T3, the process proceeds to a predetermined short-circuit opening control. A predetermined short-circuit current is output to promote opening of the short-circuit.

  After the occurrence of a short circuit at time point E6, the welding current is rapidly reduced, and a control section of a third predetermined period T3 called a short circuit initial control time is provided to ensure a short circuit at the initial stage of the short circuit, and the base material of the droplet As a result, the arc can be stabilized and the occurrence of spatter can be suppressed.

  As described above, when the constriction occurs, the current can be drastically reduced by reversing the polarity of the output terminal, and the generation of spatter can be suppressed by keeping the absolute value of the current value during arc regeneration low. Inverting the polarity of the output terminal at the time of occurrence can reduce the current rapidly, ensure the short circuit at the beginning of the short circuit, stabilize the arc and suppress spatter generation Possible welding equipment can be realized at low cost.

  In addition, according to the present embodiment, the number of polarity inversions is reduced compared to other embodiments, and the burden on the switching element is reduced. Further, the switching loss is reduced by reducing the number of times of switching, a margin can be taken in the operating temperature, and the cost can be reduced by improving the reliability and simplifying the cooling device.

  In addition, since the possibility of polarity reversal at extremely short time intervals is reduced, a stable semiconductor on state can be maintained at all times, and the risk of arc breakage is reduced, thereby realizing stable welding.

  In this embodiment, an example in which welding is performed with reverse polarity during the arc has been described, but the same effect can be obtained by performing similar control even when welding is performed with positive polarity during the arc. .

  As described above, the welding apparatus of the present invention can provide a welding apparatus capable of performing low spatter welding and AC welding at low cost, and can perform spattering of automobiles, shipbuilding, bridges, etc. that perform consumable electrode arc welding construction. It has wide applicability in industries where generation and weldability of thin plates are a problem.

E1 time (when necking detection occurs)
E2 time point (time point T1 has passed since time point E1)
E3 time (when the output current reaches I1)
Time point E4 (when the output current reaches Is1)
Time point E5 (when the arc is regenerated from the short-circuit state)
E6 time (when a short circuit occurs)
E7 time (when T2 has passed since time E6)
E8 time (when the output current reaches I2)
E9 time (when the output current reaches Is2)
E10 time point (when T3 has passed since time point E6)
T1 First predetermined period T2 Second predetermined period T3 Third predetermined period T4 Fourth predetermined time I1 First current threshold I2 Second current threshold I3 Third current threshold Is1 First predetermined current value Is2 2nd predetermined current value Is3 3rd predetermined current value Is4 4th predetermined current value Is5 5th predetermined current value 1 Rectification part 2 Smoothing capacitor 3 Inverter part 4 Transformer 5 Control part 6 Welding output detection part 7 Neck detection Unit 8 AS determination unit 9 Output current determination unit 10 Timekeeping unit 11 Output terminal 12 Output terminal 13 Current detection unit 14a, 14b, 14c, 14d Rectification unit 15a, 15b Reactor 17 External device 18 Control unit 19a, 19b Resistance unit 20 Base material 21 Welding torch 22 Welding wire 23, 24, 25, 26, 27, 28, 29 Welding device TR1 First switching element TR2 Second Switching element TR3 third switching element TR4 fourth switching element TR5a fifth switching element TR5b sixth switching element

Claims (7)

A welding device capable of reversing the polarity of the output terminal,
A welding output detector for detecting the welding output;
An arc / short-circuit determining unit that determines an arc / short-circuit based on a detection result of the welding output detection unit;
A welding apparatus that performs polarity reversal of the output terminal when the arc / short-circuit determination unit detects that a short-circuit period is reached from an arc period. It has a timekeeping part that keeps time,
2. The polarity inversion of the output terminal is performed again when a second predetermined time elapses after the arc / short-circuit determination unit detects that the short-circuit period is changed from the arc period and performs polarity inversion of the output terminal. Welding equipment. An output current determination unit that determines that the output current has reached a predetermined value or less based on the detection result of the welding output detection unit;
The output current determination unit determines that the output current has reached a third predetermined value or less after detecting that the arc / short circuit determination unit has changed from the arc period to the short circuit period and performing polarity reversal of the output terminal. The welding apparatus according to claim 1, wherein the polarity of the output terminal is reversed again at the time. When the output current detected by the welding output detection unit at the time when the arc / short-circuit determination unit detects that the short-circuit period is changed from the arc period is greater than or equal to a fourth predetermined value, the arc / short-circuit determination unit The welding apparatus according to any one of claims 1 to 4, wherein the polarity of the output terminal is not reversed even if a short circuit is detected. A rectifier that rectifies the input power;
An inverter that converts the output of the rectifier to alternating current;
A transformer for transforming the output of the inverter unit;
A first switching element and a second switching element connected in series to the output side of the transformer;
A third switching element and a fourth switching element connected in series to the output side of the transformer;
A controller that controls the operation of the fourth switching element from the first switching element,
The controller is
When performing reverse polarity output, conducting the first switching element and the fourth switching element, cutting off the second switching element and the third switching element, and performing welding output,
When performing positive output,
Shutting off the first switching element and the fourth switching element;
The welding apparatus according to any one of claims 1 to 4, wherein the second switching element and the third switching element are electrically connected to perform welding output. A rectifier that rectifies the input power;
An inverter that converts the output of the rectifier to alternating current;
A transformer for transforming the output of the inverter unit;
A first switching element and a second switching element connected in series to the output side of the transformer;
A controller that controls the operation of the first switching element and the second switching element;
The controller is
When performing reverse polarity output, conducting the first switching element, cutting off the second switching element and performing welding output,
When performing positive output,
The welding apparatus according to any one of claims 1 to 4, wherein the first switching element is cut off and the second switching element is conducted to perform welding output. A welding method for performing welding using a welding apparatus capable of reversing the polarity of an output terminal,
Detecting a welding output;
Determining whether it is an arc period or a short-circuit period based on the detection result of the welding output;
And a step of reversing the polarity of the output terminal when it is detected that the short period has been reached from the arc period.

Images