JP2006043764A - Consumable electrode arc welding source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the arc starting properties in a consumable electrode arc welding source having a saturable reactor connected to an output of a source main circuit PM in series, and in which an inductance value is increased at the time when the value of the current supplied to a main winding Nm is less than a prescribed one, and the iron cores thereof are made into a saturated state, and the inductance value is made extremely low at the time when the current value is the prescribed one or higher. <P>SOLUTION: In the consumable electrode arc welding source, the saturable reactor WL1 is newly provided with an auxiliary winding Nc, the auxiliary winding Nc is connected with an auxiliary source PC, at the time when an arc is started, an electric current Ic is supplied from the auxiliary source PC to the auxiliary winding Nc, thus the saturable reactor WL1 is made into a saturated state to extremely reduce inductance value, and, when the consumable electrode 1 is made into contact with a base metal 2 by feeding, a hot start current with a high current value is supplied from the source main circuit PM to the consumable electrode 1 through the main winding Nm, thus an arc is started. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a consumable electrode arc welding power source capable of improving arc start performance in a welding power source having a saturable reactor in series with the output of the welding power source.

  FIG. 13 is a diagram showing a general configuration of a consumable electrode arc welding power source. The power supply main circuit PM performs output control by inverter control, chopper control, etc. with an AC commercial power supply (3-phase 200V, etc.) as an input in response to an external start signal St, and an output voltage Vo and welding current suitable for arc welding. While outputting Iw, the feeding speed Fw of the welding wire 1 which is a consumable electrode is controlled. The reactor WL is inserted in series with the output of the power supply main circuit PM to smooth the output voltage Vo and the welding current Iw. The effect | action of this reactor WL is later mentioned in FIG.14 and FIG.15. The output terminal T1 of the welding power source is connected to the welding wire 1 via the power supply tip of the welding torch, the other output terminal T2 is connected to the base material 2, and a welding voltage is connected between the welding wire 1 and the base material 2. Vw is applied. The welding wire 1 is fed at a feeding speed Fw, and an arc 3 is generated between the base metal 2 and welding is performed.

  FIG. 14 is a waveform diagram of a welding current Iw and a welding voltage Vw in pulse arc welding which is one of consumable electrode arc welding. During the peak period Tp from time t1 to t2, a peak current Ip having a large current value for transferring droplets is energized as shown in FIG. 5A, and the peak voltage is applied as shown in FIG. Vp is applied between the welding wire and the base material. During the base period Tb from time t2 to t3, as shown in FIG. 5A, a base current Ib having a small current value for preventing the formation of droplets is applied, and as shown in FIG. The voltage Vb is applied between the welding wire and the base material. The welding is performed by repeating the peak period Tp and the base period Tb as the pulse period Tpb.

  Generally, when the value of the welding current Iw becomes a small current value of less than several tens of A, arc breakage is likely to occur due to a slight fluctuation in arc load. When the arc break occurs, the welding state becomes unstable, so that the welding quality is deteriorated. As described above, since the value of the base current Ib is a small current value of less than several tens of A, an arc break is likely to occur during the base period Tb. As a promising method for preventing this arc break, conventionally, measures have been taken to increase the inductance value L [μH] of the reactor WL. The reason for this is as follows. Immediately before the arc break occurs, the welding current rapidly decreases. This is because the voltage E = L · di / dt is generated in the reactor WL due to the current change di / dt, and this voltage prevents arc breakage. Therefore, if the inductance value L is large, the voltage E is also increased, and arc breakage is less likely to occur.

  On the other hand, in order to achieve a good droplet transfer state (so-called 1 pulse / one droplet transfer state) synchronized with the peak period Tp, the rising and falling speeds of the peak current Ip must be fast. Since the rising speed and the falling speed are substantially proportional to the inductance value L, the inductance value L during the peak period Tp needs to be a small value. Thus, the appropriate value Lb of the inductance value during the base period Tb and the appropriate value Lp of the inductance value during the peak period Tp are greatly different, and Lb> Lp. In other words, the inductance value of the reactor is ideally large when the welding current Iw is a small current value and small when the welding current Iw is a large current value.

  FIG. 15 is a waveform diagram of a welding current Iw and a welding voltage Vw in short-circuit transition welding of CO2 / MAG welding, which is one of consumable electrode arc welding. In short-circuit transfer welding, welding is performed by alternately repeating the short-circuit period Ts from time t1 to t2 and the arc period Ta from time t2 to t3. During the short circuit period Ts, the welding wire and the base material are in a short circuit state, and a gradually increasing short circuit current flows as shown in FIG. 5A, and the welding voltage Vw is as shown in FIG. The value is as low as several volts. During the arc period Ta, an arc is generated between the welding wire and the base metal, and as shown in FIG. 5A, a gradually decreasing arc current is applied, as shown in FIG. In addition, the welding voltage Vw has an arc voltage value of several tens of volts to several tens of volts.

  In FIG. 15A, the current value in the latter half of the arc period Ta may be less than several tens of A, and arc breakage is likely to occur as described above. Therefore, when the welding current Iw is a small current value, it is necessary to increase the inductance value of the reactor. On the other hand, in order to stabilize the welding state, it is necessary to set the current increase rate during the short-circuit period Ts shown in FIG. Therefore, the inductance value needs to be small when the welding current Iw is a large current value.

  As described above, in consumable electrode arc welding such as pulse arc welding and short-circuit transfer welding, it is desirable that the inductance value of the reactor changes in inverse proportion to the value of the welding current. As a reactor having such an inductance value characteristic, there are the following saturable reactors. FIG. 16 is a diagram illustrating an example of the structure of the saturable reactor. A closed loop iron core is formed by the U-shaped iron cores C1 and C2. A thin non-magnetic spacer G is inserted into the contact surface of both iron cores C1 and C2 to provide a gap. The main winding Nm through which welding is energized is formed by winding a conductive wire around the iron core C1 a predetermined number of times. Since the iron core is a closed loop, the iron core is saturated when the current value for energizing the main winding Nm becomes equal to or greater than the predetermined current value It. For this reason, it is called a saturable reactor.

  FIG. 17 is a diagram illustrating a change in inductance value with respect to the current value of the saturable reactor described above. As shown in the figure, with the predetermined current value It = 40A at which the iron core is saturated as a boundary value, the inductance value suddenly becomes a large value below the predetermined current value It, and becomes a very small value above the predetermined current value It. Become. Therefore, since the inductance value of the saturable reactor changes approximately inversely proportional to the current value, arc breakage at a small current is prevented, and the current increase rate is increased at a large current, and the welding state is stabilized. The predetermined current value It can be adjusted by changing the gap length depending on the thickness of the spacer. The characteristic of the inductance value changes depending on the number of turns Nm of the main winding.

  As a method for changing the inductance value in inverse proportion to the current value, the following method has been proposed in addition to the above-described method using the saturable reactor. For example, in the inventions of Patent Documents 1 and 2, by providing a small current reactor and a large current reactor, the inductance value can be switched according to the current value.

Japanese Patent Publication No.59-16870 Japanese Patent Laid-Open No. 11-28567

  FIG. 18 is a timing chart at the time of arc start in the consumable electrode arc welding power source described above with reference to FIG. FIG. 4A shows the start signal St, FIG. 4B shows the feed speed Fw, FIG. 3C shows the welding current Iw, and FIG. 4D shows the time variation of the welding voltage Vw. This figure shows the case where the reactor Wl is the saturable reactor described above. Hereinafter, a description will be given with reference to FIG.

  At time t1, as shown in FIG. 18 (A), when the start signal St becomes High level, as shown in FIG. 18 (B), the feeding speed Fw becomes a low initial feeding speed, and the welding wire becomes the mother wire. It is fed in the material direction. At the same time, as shown in FIG. 3C, output from the power supply main circuit is started and a large value of no-load voltage is applied. The reason for the no-load voltage is that the welding wire has not yet reached the base material, and the welding wire / base material is in an unloaded state. Further, as shown in FIG. 4D, since the welding wire and the base material are in an unloaded state, the welding current Iw is not yet energized.

  When the welding wire comes into contact with the base material at time t2, as shown in FIG. 18C, the welding voltage Vw changes to a low short-circuit voltage value, and as shown in FIG. Start energization. In response to this, the feeding speed Fw is switched to a steady feeding speed as shown in FIG. As shown in FIG. 6C, the value of the welding current Iw is less than the predetermined current value It during the period from time t2 to time t3, so that the inductance value of the saturable reactor becomes a large value. For this reason, the rate of current increase during this period becomes very gradual. When the value of the welding current Iw exceeds the predetermined current value It at time t3, the saturable reactor is saturated and the inductance value becomes a very small value, so that the welding current Iw rises rapidly and is set to a predetermined hot start. The current Ih is energized until time t5 when the predetermined hot start period Th ends. Since an arc is generated at time t4 immediately after the welding current Iw suddenly increases, the welding voltage Vw changes from the short-circuit voltage value to the arc voltage value at time t4 as shown in FIG. After time t5, a steady welding current Iw of pulse arc welding or short-circuit transfer welding is energized.

  As shown in FIG. 18D, since the rate of increase of the welding current Iw during the period from the time t2 when the welding wire contacts the base material to the time t3 is moderate, the short-circuiting period at the start from the time t2 to t4 And the probability of an unfavorable arc start increases. That is, the faster the current increase rate immediately after the welding wire and the base material come into contact with each other, the shorter the short-circuit period at the start, and the higher the probability of a good arc start. If the short-circuit period at the start becomes long, large-scale spatter is generated at the arc start, the bead appearance of the arc start part is deteriorated, and sometimes the arc start fails.

  In the prior art, a method has been proposed in which an inductance value is reduced by short-circuiting a reactor by a contact of an electromagnetic switch when starting an arc. That is, at the time of arc start, the reactor is short-circuited at the contact point to reduce the inductance value, and after the arc start, the contact point is opened to cancel the reactor short-circuit and return to the original inductance value. However, in this method, since the contact point needs to cut off the energization of a welding current of several hundred A, a large capacity electromagnetic switch is required. This increases the cost of the welding power source. Furthermore, since the contact life is shortened because a large current is repeatedly interrupted at each arc start, there is a problem that the service life of the welding power source is also shortened.

  Therefore, the present invention provides a consumable electrode arc welding power source that realizes good arc start performance in a welding power source that uses a saturable reactor as a reactor.

  In order to solve the above-described problems, the first invention comprises a power supply main circuit for supplying a welding current and a welding voltage to a consumable electrode, and a main winding and an iron core connected in series to the output of the power supply main circuit. A reactor, and the reactor has a large inductance value when the current value flowing through the main winding is less than a predetermined current value, and the iron core is saturated when the current value exceeds the predetermined current value. In the consumable electrode arc welding power source which is a saturable reactor having an inductance value, an auxiliary winding is newly provided in the saturable reactor, and an auxiliary power source connected to the auxiliary winding is provided. By supplying current to the auxiliary winding, the saturable reactor is saturated and the inductance value is made very small. When the base material is contacted, a hot start current having a large current value is supplied from the power supply main circuit to the consumable electrode through the main winding to start an arc, and then the current supply from the auxiliary power supply is stopped to stop the power supply main circuit. A consumable electrode arc welding power source characterized in that a steady welding current is passed through the main winding.

  A second invention includes a power supply main circuit for supplying a welding current and a welding voltage to the consumable electrode, and a reactor composed of a main winding and an iron core connected in series to the output of the power supply main circuit. This is a saturable reactor in which the inductance value increases when the current value flowing through the main winding is less than the predetermined current value, and the iron core becomes saturated and becomes a very small inductance value when the current value exceeds the predetermined current value. In a consumable electrode arc welding power source, a series circuit consisting of a resistor and a short-circuit switching element is provided between the output terminals of the consumable electrode arc welding power source, and the short-circuiting switching element is turned on at the time of arc start to short-circuit between the output terminals. And a terminal short-circuit current greater than the predetermined current value from the power supply main circuit through the main winding and the short-circuit switching element. When the consumable electrode comes into contact with the base material by feeding, the short-circuit switching element is turned off and the power supply main circuit is turned off. The current is switched to a hot start current having a large current value, the consumable electrode is energized through the main winding of the saturable reactor to start an arc, and then a steady welding current is energized from the power supply main circuit through the main winding. This is a consumable electrode arc welding power source.

  According to a third aspect of the present invention, there is provided a power supply main circuit for supplying a direct current and a DC voltage, a reactor comprising a main winding and an iron core connected in series to the output of the power supply main circuit, and the reactor energizing the main winding. When the current value to be generated is less than the predetermined current value, the inductance value increases, and when the current value is equal to or higher than the predetermined current value, the iron core is saturated and the saturable reactor has a very small inductance value, and the output of the reactor Polarity switching inverter circuit which is provided in the circuit and forms a full bridge from the opposing first and fourth switching elements and opposing second and third switching elements and supplies an AC output to the consumable electrode In a consumable electrode AC arc welding power source with a resistor and a short circuit switch in parallel with the polarity switching inverter circuit A series circuit composed of elements is provided, and at the time of arc start, the switching element for short-circuiting is turned on, and the four switching elements of the polarity switching inverter circuit are turned off, so that the main winding and the short-circuit from the power supply main circuit are provided. When a short-circuit current greater than or equal to the predetermined current value is passed through the switching element to make the saturable reactor saturated, the inductance value becomes very small, and then when the consumable electrode contacts the base material by feeding, the short-circuit switching The element is turned off and one of two opposing switching elements of the polarity switching inverter circuit is turned on to switch the DC current from the power supply main circuit to a hot start current having a large current value. Start the arc by energizing the consumable electrode through the main winding of the saturable reactor. , Followed by a consumable electrode AC arc welding power source, characterized by passing a DC current of the constant from the main power source circuit is converted into alternating current by the polarity switching inverter circuit.

  According to a fourth aspect of the present invention, there is provided a power source main circuit for supplying a direct current and a DC voltage, a reactor comprising a main winding and an iron core connected in series to the output of the power source main circuit, and the reactor energizing the main winding. When the current value to be generated is less than the predetermined current value, the inductance value increases, and when the current value is equal to or higher than the predetermined current value, the iron core is saturated and the saturable reactor has a very small inductance value, and the output of the reactor Polarity switching inverter circuit which is provided in the circuit and forms a full bridge from the first switching element and the fourth switching element facing each other and the second switching element and the third switching element facing each other and supplies an AC output to the consumable electrode In a consumable electrode AC arc welding power source comprising: a resistor in parallel with the first switching element of the polarity switching inverter circuit And a series circuit comprising a second short-circuit switching element, and at the time of arc start, the short-circuit switching element is turned on and the third switching element of the polarity switching inverter circuit is turned on, and the power supply main circuit From the main winding, the shorting switching element, and the third switching element to pass a short-circuit current greater than the predetermined current value to saturate the saturable reactor, thereby reducing the inductance value to a very low level. When the consumable electrode comes into contact with the base material by feeding, the switching element for short circuit and the third switching element are turned off, and one of two opposing switching elements of the polarity switching inverter circuit is turned on. The DC current from the power supply main circuit is switched to a hot start current with a large current value. The consumable electrode is energized through the main winding of the saturable reactor to start an arc, and then a steady DC current is converted from the power supply main circuit into an AC current by the polarity switching inverter circuit. A consumable electrode AC arc welding power source.

  According to a fifth aspect of the present invention, there is provided a first series circuit comprising a resistor and a second shorting switching element in parallel with the first switching element of the polarity switching inverter circuit, and a resistor and a second in parallel with the fourth switching element. And a second series circuit composed of three short-circuit switching elements, and at the time of arc start, the second short-circuit switching element and the third short-circuit switching element are turned on and the polarity switching inverter circuit The second switching element and the third switching element are turned on, the main winding, the second short-circuit switching element, the third switching element, the second switching element, The saturable reactor is saturated by applying a short-circuit current of the predetermined current value or more through a third short-circuit switching element. When the consumable electrode comes into contact with the base material by feeding and the inductance value is made very small, the second short-circuit switching element, the third short-circuit switching element, the second switching element, and the third And switching one of two opposing switching elements of the polarity switching inverter circuit to an on state to convert the DC current from the power supply main circuit into a hot start current having a large current value. 5. The consumable electrode AC arc welding power source according to claim 4, wherein the consumable electrode is switched to an electric current through the main winding of the saturable reactor to start an arc.

  According to the first aspect of the present invention, the inductance value is made very small by energizing the auxiliary winding current until the welding wire comes into contact with the base material at the time of arc start and saturating the saturable reactor with auxiliary winding. Since the rate of increase in hot start current can be made very fast, good arc start performance can be realized.

  According to the second aspect of the invention, the inductance value is made extremely small by energizing the terminal short-circuit current until the welding wire comes into contact with the base material at the time of arc start, thereby bringing the saturable reactor into a saturated state. Since the rate of increase can be made very fast, good arc start performance can be realized.

  According to the third aspect of the present invention, the inductance value is made extremely small by applying a short-circuit current until the welding wire comes into contact with the base material at the time of arc start of AC arc welding, thereby making the saturable reactor saturated. Since the rate of increase of the start current can be made very fast, good arc start performance can be realized in AC arc welding.

  According to the fourth invention, since the secondary inverter circuit of the AC arc welder uses two power transistors having the same capacity and arranged in the same package, a new short-circuit switching element is provided. 1 can be used as a short-circuit switching element without providing an external resistor, so that a series circuit can be formed simply by providing one resistor externally. Simplification can be realized.

  According to the fifth invention, in the secondary inverter circuit of the fourth invention, two resistors are provided outside to form two series circuits, and an arc for AC arc welding is formed using the two series circuits. Since a short-circuit current is applied before the welding wire contacts the base material at the start, the saturable reactor is saturated and the inductance value is reliably reduced, and good arc start performance can be realized in AC arc welding.

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

[Embodiment 1]
FIG. 1 is a configuration diagram of a consumable electrode arc welding power source according to Embodiment 1 of the present invention. In the figure, the same components as those in FIG. 13 described above are denoted by the same reference numerals, and description thereof is omitted. Hereinafter, components different from those in FIG. 13 will be described.

  The saturable reactor WL1 with auxiliary winding is a saturable reactor in which an auxiliary winding Nc is added in addition to the main winding Nm, and details will be described later with reference to FIG. An auxiliary power supply PC including a constant current power supply CC and an auxiliary power supply switching element TRc is connected to the auxiliary winding Nc. The constant current power source CC supplies the auxiliary winding current Ic having a value at which the saturable reactor WL1 with auxiliary winding is saturated. The auxiliary power supply drive circuit DVC controls on / off of the drive power supply switching element TRc. A timing chart at the time of arc start in FIG.

  FIG. 2 is a diagram showing an example of the structure of the above-described saturable reactor WL1 with auxiliary winding. In the figure, an auxiliary winding Nc is added to the saturable reactor described above with reference to FIG. The welding current Iw is supplied to the main winding Nm, and the auxiliary winding current Ic is supplied to the auxiliary winding Nc. The turns ratio Nm: Nc is about 1: 1 to 1: 5.

  FIG. 3 is a timing chart at the time of arc start in the first embodiment. This figure corresponds to FIG. 18 described above. Hereinafter, a description will be given with reference to FIG.

  At time t1, as shown in FIG. 3A, when the activation signal St becomes High level, as shown in FIG. 3B, the welding wire starts feeding at the initial feeding speed. At the same time, as shown in FIG. 5E, the auxiliary power switching element TRc is turned on, and the auxiliary winding current Ic is supplied from the auxiliary power PC to the auxiliary winding Nc. This current value is such that Ic · Nc> It · Nm and the saturable reactor with auxiliary winding is saturated.

  When the welding wire contacts the base material at time t2, the welding voltage Vw changes from the no-load voltage to the short-circuit voltage as shown in FIG. When it is determined that the welding voltage Vw has become less than the predetermined short-circuit determination voltage value Vt, the supply of the auxiliary winding current Ic is stopped, as shown in FIG. Thus, energization of the hot start current Ih having a large current value is started. At this time, since the saturable reactor with auxiliary winding is in a saturated state due to energization of auxiliary winding current Ic, the rate of increase of the hot start current Ih is very fast. As a result, since an arc is generated at time t3 after a short-circuit, the welding voltage Vw changes from the short-circuit voltage to the arc voltage as shown in FIG. When the hot start period Th ends at time t4, the welding current Iw shifts from the hot start current Ih to a steady welding current of pulse arc welding or short-circuit transfer welding, as shown in FIG.

  As described above, in the first embodiment, the increase rate of the hot start current is obtained by energizing the auxiliary winding current and bringing the saturable reactor with auxiliary winding into saturation before the welding wire contacts the base material. Can be made very fast, and good arc start performance can be realized. As shown in FIG. 3E, the above is a case where the auxiliary winding current Ic is stopped at the time of arc start at time t2, but it may be stopped after a slight delay.

[Embodiment 2]
FIG. 4 is a configuration diagram of a consumable electrode arc welding power source according to Embodiment 2 of the present invention. In the figure, the same components as those in FIG. 13 described above are denoted by the same reference numerals, and description thereof is omitted. The saturable reactor WL shown in the figure is the same as the saturable reactor described above with reference to FIGS. 16 and 17, and is saturated by energization with a current of a predetermined current value It or more. Hereinafter, components different from those in FIG. 13 will be described.

  A series circuit including a resistor Rs and a short-circuit switching element TRs is connected between the output terminals T1 and T2. Then, the short-circuit driving circuit DVS performs on / off control of the short-circuit switching element TRs. When the short-circuit switching element TRs is turned on, the terminal short-circuit current Is is energized.

  FIG. 5 is a timing chart at the time of arc start in the second embodiment. This figure corresponds to FIGS. 18 and 3 described above. Hereinafter, a description will be given with reference to FIG.

  At time t1, as shown in FIG. 5A, when the activation signal St becomes High level, the welding wire starts feeding at the initial feeding speed as shown in FIG. 5B. At the same time, the output from the power supply main circuit PM is started and the short-circuit switching element TRs is turned on, and the terminal short-circuit current Is is conducted through the main winding Nm. This current value is such that Is> It and the saturable reactor becomes saturated. The welding voltage Vw during the period from the time t1 to the time t2 is substantially Is · Rs as shown in FIG. The resistance value of the resistor Rs is selected so that this voltage value is larger than the short-circuit voltage value when the welding wire comes into contact with the base material. This is to determine that the welding wire has contacted the base material.

  When the welding wire contacts the base material at time t2, as shown in FIG. 5C, the welding voltage Vw changes from the above Is · Rs to the short-circuit voltage value. When it is determined that the welding voltage Vw has become less than the predetermined short-circuit determination voltage value Vt, the short-circuit switching element TRs is turned off to stop energization of the terminal short-circuit current Is as shown in FIG. As shown in FIG. 4D, energization of the hot start current Ih having a large current value is started. At this time, since the saturable reactor is in a saturated state due to energization of the terminal short-circuit current Is, the rate of increase of the hot start current Ih is very fast. As a result, since an arc is generated at time t3 after a short-circuit, the welding voltage Vw changes from the short-circuit voltage to the arc voltage as shown in FIG. When the hot start period Th ends at time t4, the welding current Iw shifts from the hot start current Ih to a steady welding current of pulse arc welding or short-circuit transfer welding as shown in FIG.

  As described above, in the second embodiment, the inductance value is extremely reduced by energizing the terminal short-circuit current and bringing the saturable reactor into saturation before the welding wire comes into contact with the base material. Since the rate of increase can be made very fast, good arc start performance can be realized. In the above description, the fact that the welding wire is in contact with the base material is determined by the change in the welding voltage, but it may be determined by the start of energization of the welding current Iw.

[effect]
FIG. 6 is a comparison diagram of good arc start rates showing an example of the effect of the present invention. In the figure, in a pulse MIG welding of an aluminum alloy, a welding wire having a diameter of 1.2 mm was used, and an arc start was repeated 100 times at an average welding current of 80 A, and the ratio of the good arc start was measured. . The prior art is a case where the reactor is a saturable reactor in FIG. 13 described above, and the present invention is the case of the first and second embodiments. Whether the arc start was good or bad was determined to be good if the short-circuit period at the start when the welding wire was in contact with the base metal was less than 4 ms, and not good if it was 4 ms or more. As shown in the figure, the good arc start rate was 64% in the prior art, but was greatly improved to 92% in the present invention.

[Embodiment 3]
FIG. 7 is a configuration diagram of a consumable electrode AC arc welding power source according to Embodiment 3 of the present invention. In the figure, the same components as those in FIG. 13 described above are denoted by the same reference numerals, and description thereof is omitted. The saturable reactor WL shown in the figure is the same as the saturable reactor described above with reference to FIGS. 16 and 17, and is saturated by energization with a current of a predetermined current value It or more. Hereinafter, components different from those in FIG. 13 will be described.

  In FIG. 7, a series circuit composed of a resistor Rs and a short-circuit switching element TRs is provided in parallel with the polarity switching inverter circuit shown below, and the polarity switching inverter circuit (hereinafter referred to as a secondary inverter circuit) includes the saturable reactor. The collector of the first switching element TR1 and the collector of the second switching element TR2 are connected to the output side of WL, and the emitter of the first switching element TR1 and the collector of the second switching element TR2 are connected to the second output terminal T2. Are connected to the emitter of the second switching element TR2 and the collector of the fourth switching element TR4 at the first output terminal, and the third switching element TR3 and the fourth switching element TR4 are connected to the output side of the power supply main circuit. To form a full bridge.

  The DC / AC mode setting circuit MC sets the DC mode or the AC mode. The DC / AC mode setting signal Mc is set to the Low level in the DC mode, and is set to the High level in the AC mode. The polarity switching circuit TM sets the polarity switching frequency and polarity ratio of the secondary inverter circuit to predetermined values and outputs them as a polarity switching signal Tm. The secondary inverter drive circuit SD includes four switching elements facing each other in the secondary inverter circuit and the short-circuit switching element TRs in the series circuit according to the DC / AC mode setting signal Mc and the polarity switching signal Tm. Perform on / off control.

  FIG. 8 is a timing chart when the arc starts with the EP polarity in the AC mode. Hereinafter, a description will be given with reference to FIG.

  At time t1, as shown in FIG. 8A, when the activation signal St becomes High level, as shown in FIG. 8G, the welding wire starts feeding at the initial feeding speed. At the same time, the output from the power supply main circuit PM shown in FIG. 7 is started and the short-circuit driving signal Trs shown in FIG. 7B is set to the High level so that the short-circuit switching element TRs is turned on through the main winding Nm. The short circuit current Is is energized. This current value is such that Is> It and the saturable reactor becomes saturated. The welding voltage Vw during the period from time t1 to t2 is substantially Is · Rs1, as shown in FIG. The resistor Rs is selected so that this voltage value is larger than the short-circuit voltage value when the welding wire comes into contact with the base material. This is to determine that the welding wire has contacted the base material.

  When the welding wire comes into contact with the base material at time t2, as shown in FIG. 8H, the welding voltage Vw changes from the above approximately Is · Rs to the short-circuit voltage value. When it is determined that the welding voltage Vw has become less than the predetermined short-circuit determination voltage value Vt, the short-circuit switching element TRs is turned off to stop energization of the short-circuit current Is shown in FIG. The signal T2 and the third element drive signal T3 are set to the high level, and the second switching element TR2 and the third switching element TR3 are turned on, as shown in FIG. Start energization of Ih. At this time, since the saturable reactor is in a saturated state by energization of the short-circuit current Is, the rate of increase of the hot start current Ih is very fast. As a result, since an arc is generated at time t3 after a short-circuit, the welding voltage Vw changes from the short-circuit voltage to the arc voltage as shown in FIG. When the hot start period Th ends at time t4, the welding current Iw shifts from the hot start current Ih to the welding current of the AC pulsed arc welding with EP polarity as shown in FIG.

[Embodiment 4]
FIG. 9 is a configuration diagram of a consumable electrode AC arc welding power source according to Embodiment 4 of the present invention. In the figure, the same components as those in FIG. 13 described above are denoted by the same reference numerals, and description thereof is omitted.

  The secondary inverter circuit is required to pass a large current of 350 A, for example, and therefore requires a large capacity power transistor. However, large-capacity power transistors are expensive and poorly stocked. As the above countermeasure, a standard power transistor shown in FIG. 19 in which two 200A switching elements are arranged in series in the same package is generally used, and the price is low and the product lineup is good. In the fourth embodiment of the present invention, a secondary inverter circuit is formed using the standard power transistor.

  The secondary inverter circuit according to the fourth embodiment of the present invention uses the standard power transistor, and, as shown in FIG. 9, a first resistor R1 and a first switching element TR1b are provided on the output side of the reactor WL. The series circuit, the collector of the first switching element TR1a, the collector of the second switching element TR2a, and the collector of the second switching element TR2b are connected, and the emitter of the first switching element TR1a and the first switching are connected to the second output terminal T2. The emitter of the element TR1b, the collector of the third switching element TR3a, and the collector of the third switching element TR3b are connected, and the emitter of the second switching element TR2a, the emitter of the second switching element TR2b, and the fourth switching are connected to the first output terminal. The collector of the element TR4a and the fourth switching element The collector of TR4b is connected, and the emitter of the third switching element TR3a, the emitter of the third switching element TR3b, the emitter of the fourth switching element TR4a, and the emitter of the fourth switching element TR4b are connected to the output side of the power supply main circuit. Connect to form a full bridge. The secondary inverter drive circuit SD performs on / off control of the switching elements facing each other of the secondary inverter circuit and the short-circuit switching element TRs of the series circuit.

  FIG. 10 is a timing chart when the arc starts with the EP polarity in the AC mode. Hereinafter, a description will be given with reference to FIG.

  At time t1, as shown in FIG. 10A, when the activation signal St becomes High level, as shown in FIG. 10J, the welding wire starts feeding at the initial feeding speed. At the same time, the output from the power supply main circuit PM shown in FIG. 9 is started, and the second short circuit element drive signal T1b, the third element drive signal T3a, and the third element drive signal T3b shown in FIG. The second short-circuit switching element TR1b, the third switching element TR3a, and the third switching element TR3b are turned on, and the short-circuit current Is flows through the main winding Nm. This current value is such that Is> It and the saturable reactor becomes saturated. The welding voltage Vw during the period from the time t1 to the time t2 is substantially Is · R1, as shown in FIG. The resistance value of the first resistor R1 is selected so that this voltage value is larger than the short-circuit voltage value when the welding wire contacts the base material. This is to determine that the welding wire has contacted the base material.

  When the welding wire comes into contact with the base material at time t2, as shown in FIG. 10 (K), the welding voltage Vw changes from the above approximately Is · Rs to the short-circuit voltage value. When it is determined that the welding voltage Vw is less than the predetermined short-circuit determination voltage value Vt, the second short-circuit switching element TR1b is turned off by setting the second short-circuit element drive signal T1b shown in FIG. And the second element driving signal T2a, the second element driving signal T2b, the third element driving signal T3a, and the third element driving signal T3b are set to the high level, and the second switching element TR2a, the second switching element TR2b, The third switching element TR3a and the third switching element TR3b are turned on to stop energization of the terminal short-circuit current Is shown in FIG. 5M, and as shown in FIG. Energization of the start current Ih is started. At this time, the saturable reactor WL is in a saturated state due to energization of the short-circuit current Is, and therefore the rate of increase of the hot start current Ih is very fast. As a result, since an arc is generated at time t3 after a short-circuit, the welding voltage Vw changes from the short-circuit voltage to the arc voltage as shown in FIG. When the hot start period Th ends at time t4, the welding current Iw shifts from the hot start current Ih to the welding current of the AC pulsed arc welding with EP polarity as shown in FIG.

  From the above, in consumable electrode AC arc welding, the effective current value in the EN polarity is smaller than the effective current value in the EP polarity. Therefore, the secondary-side current that conducts when the polarity of the EN shown in FIG. 9 can be supplied only by the TR1a of the first switching element, and the other TR1b of the first switching element can be used as the second short-circuiting switching element. Therefore, it is not necessary to provide a new short-circuit switching element outside.

[Embodiment 5]
FIG. 11 is a configuration diagram of a consumable electrode arc welding power source according to Embodiment 5 of the present invention. In this figure, the same components as those in FIGS. 9 and 13 described above are denoted by the same reference numerals, and description thereof is omitted.

  A second series circuit is newly provided by adding a second resistor R2 between the emitter of the fourth switching element TR4b of the secondary inverter circuit shown in FIG. 11 and the output of the power supply main circuit. The secondary inverter circuit of the fifth embodiment is formed.

  FIG. 12 is a timing chart when the arc starts with the EP polarity in the AC mode. Hereinafter, a description will be given with reference to FIG.

  At time t1, as shown in FIG. 12A, when the activation signal St becomes High level, as shown in FIG. 12J, the welding wire starts feeding at the initial feeding speed. At the same time, the output from the power supply main circuit PM shown in FIG. 11 is started and the second short-circuit element drive signal T1b, the second element drive signal T2a, the second element drive signal T2b, and the third element drive signal T3a shown in FIG. The third element drive signal T3b and the third short-circuit element drive signal T4b are set to the high level, the second short-circuit switching element TR1b, the second switching element TR2a, the second switching element TR2b, and the third switching element TR3a. The third switching element TR3b and the third short-circuit switching element TR4b are turned on, and the short-circuit current Is flows through the main winding Nm. This current value is such that Is> It and the saturable reactor becomes saturated. The welding voltage Vw during the period from the time t1 to the time t2 is approximately Is · (R1 · R2 / R1 + R2) as shown in FIG. The resistance values of the first resistor Rs1 and the second resistor R2 are selected so that this voltage value is larger than the short-circuit voltage value when the welding wire contacts the base material. This is to determine that the welding wire has contacted the base material.

  When the welding wire comes into contact with the base material at time t2, as shown in FIG. 12K, the welding voltage Vw changes from the above approximately Is · (R1 · R2 / R1 + R2) to the short-circuit voltage value. When it is determined that the welding voltage Vw has become less than the predetermined short-circuit determination voltage value Vt, the second short-circuit switching element TR1b and the third short-circuit switching element TR4b are turned off and the short-circuit shown in FIG. The energization of the current Is is stopped and energization of the hot start current Ih having a large current value is started as shown in FIG. At this time, since the saturable reactor is in a saturated state by energization of the short-circuit current Is, the rate of increase of the hot start current Ih is very fast. As a result, since an arc is generated at time t3 after a short-circuit, the welding voltage Vw changes from the short-circuit voltage to the arc voltage as shown in FIG. When hot start period Th ends at time t4, welding current Iw shifts from hot start current Ih to EP polarity AC pulse arc welding as shown in FIG.

  As described above, as in the fourth embodiment, the effective current value of the EN polarity is smaller than the effective current value of the EP polarity. Therefore, the secondary current shown in FIG. 11 that is conductive in the EN polarity can be supplied by the TR1a and the fourth switching element TR4a of the first switching element, and the TR1b and the fourth switching element of the first switching element. Since TR4b can be used as the second short-circuit switching element and the third short-circuit switching element, it is not necessary to provide two new short-circuit switching elements outside.

  As described above, in the AC arc welding of the third embodiment, the fourth embodiment, and the fifth embodiment, the saturable reactor WL is saturated by supplying a short-circuit current until the welding wire 1 contacts the base material 2. As a result, the inductance value can be made very small and the rate of increase of the hot start current can be made very fast, so that good arc start performance can be realized. In the above description, the fact that the welding wire is in contact with the base material is determined by the change in the welding voltage, but it may be determined by the start of energization of the welding current Iw.

It is a block diagram of the consumable electrode arc welding power supply which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of saturable reactor WL1 with an auxiliary | assistant winding in FIG. It is a timing chart at the time of the arc start in FIG. It is a block diagram of the consumable electrode arc welding power supply which concerns on Embodiment 2 of this invention. It is a timing chart at the time of the arc start in FIG. It is a comparison figure of the favorable arc start rate which shows the effect of the present invention. It is a block diagram of the consumable electrode arc welding power supply which concerns on Embodiment 3 of this invention. It is a timing chart at the time of the arc start in FIG. It is a block diagram of the consumable electrode arc welding power supply which concerns on Embodiment 4 of this invention. It is a timing chart at the time of the arc start in FIG. It is a block diagram of the consumable electrode arc welding power supply which concerns on Embodiment 5 of this invention. It is a timing chart at the time of the arc start in FIG. It is a block diagram of the consumable electrode arc welding power supply of a prior art. It is a current / voltage waveform diagram of pulse arc welding. It is an electric current and voltage waveform figure of short circuit transfer welding. It is a figure which shows the structure of the saturable reactor in a prior art. It is a figure which shows the change of the inductance value with respect to the electric current value of the saturable reactor of FIG. It is a timing chart at the time of the arc start in the prior art which shows a subject. FIG. 7 is a configuration diagram of two power transistors formed in series in the same package used in the fourth and fifth embodiments.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Welding wire 2 Base material 3 Arc C1, C2 Iron core CC Constant current power supply DVC Auxiliary power supply drive circuit DVS Short circuit drive circuit Fw Feeding speed G Spacer Ib Base current Ic Auxiliary winding current Ih Hot start current Ip Peak current Is Terminal short circuit Current (short circuit current)
It Predetermined current value Iw Welding current L, Lb, Lp Inductance value MC DC / AC mode setting circuit Mc DC / AC mode setting signal Nc Auxiliary winding Nm Main winding PC Auxiliary power supply PM Power supply main circuit Rs Resistor R1 First Resistor R2 Second resistor SD Secondary inverter drive circuit St Start signal TM Polarity switching circuit Tm Polarity switching signals T1, T2 Output terminals TR1, 1a, first switching elements TR2, 2a, 2b Second switching element TR3 3a, 3b Third switching element TR4, 4a Fourth switching element TRs Shorting switching element TR1b Second shorting switching element TR4b Third shorting switching element T1, 1a First element driving signal T2, 2a, 2b Second element drive signal T3, 3a, 3b Third element drive signal T4, 4a, 4b 4-element drive signal Trs Short-circuit element drive signal T1b Second short-circuit element drive signal T4b Third short-circuit element drive signal Ta Arc period Tb Base period Th Hot start period Tp Peak period Tpb Pulse period TRc Auxiliary power supply switching element TRs Short-circuit switching Element Ts Short-circuit period Vb Base voltage Vo Output voltage Vp Peak voltage Vt Short-circuit determination voltage value Vw Welding voltage WL Reactor WL Saturable reactor (reactor)
WL1 Saturable reactor with auxiliary winding

Claims (5)

  A power supply main circuit for supplying a welding current and a welding voltage to the consumable electrode, and a reactor comprising a main winding and an iron core connected in series to the output of the power supply main circuit, the reactor energizes the main winding. In a consumable electrode arc welding power source which is a saturable reactor in which an inductance value increases when the current value is less than a predetermined current value and the iron core becomes saturated and becomes a very small inductance value when the current value is equal to or greater than the predetermined current value A new auxiliary winding is provided in the saturable reactor, an auxiliary power source connected to the auxiliary winding is provided, and the current is supplied from the auxiliary power source to the auxiliary winding at the time of arc start. When the saturation value is reduced to a very small value and the consumable electrode comes into contact with the base material by feeding, a large current value is output from the power supply main circuit. A hot start current is applied to the consumable electrode through the main winding to start an arc, and then the current supply from the auxiliary power supply is stopped and a steady welding current is supplied from the power supply main circuit through the main winding. Consumable electrode arc welding power supply.   A power supply main circuit for supplying a welding current and a welding voltage to the consumable electrode, and a reactor comprising a main winding and an iron core connected in series to the output of the power supply main circuit, the reactor energizes the main winding. In a consumable electrode arc welding power source which is a saturable reactor in which an inductance value increases when the current value is less than a predetermined current value and the iron core becomes saturated and becomes a very small inductance value when the current value is equal to or greater than the predetermined current value A series circuit comprising a resistor and a short-circuit switching element is provided between the output terminals of the consumable electrode arc welding power source, the short-circuit switching element is turned on at the time of arc start, and the output terminals are short-circuited. Through the main winding and the short-circuit switching element to pass a terminal short-circuit current of the predetermined current value or more to allow the saturable state. When the reactor is saturated, the inductance value is very small, and when the consumable electrode comes into contact with the base material by feeding, the short-circuit switching element is turned off and the current from the power supply main circuit is changed to a large current value. Switching to a hot start current, the consumable electrode is energized through the main winding of the saturable reactor to start an arc, and then a steady welding current is energized from the power supply main circuit through the main winding. Consumable electrode arc welding power supply.   A power supply main circuit for supplying a DC current and a DC voltage, a reactor composed of a main winding and an iron core connected in series to the output of the power supply main circuit, and the reactor has a current value for supplying current to the main winding of a predetermined current When the value is less than the value, the inductance value increases, and when the current value is equal to or greater than the predetermined current value, the iron core is saturated and becomes a very small inductance value. A consumable electrode comprising a first switching element, a fourth switching element, and a polarity switching inverter circuit that forms a full bridge from the opposing second switching element and third switching element and supplies an AC output to the consumable electrode In an AC arc welding power source, a resistor and a short-circuit switching element are provided in parallel with the polarity switching inverter circuit. In the arc start, the short-circuit switching element is turned on and the four switching elements of the polarity switching inverter circuit are turned off to start the main winding and the short-circuit switching element from the power supply main circuit. Through which the short-circuit current greater than or equal to the predetermined current value is supplied to saturate the saturable reactor so that the inductance value becomes very small. Subsequently, when the consumable electrode contacts the base material by feeding, the short-circuit switching element is turned off. The saturable state is achieved by switching one of the two opposing switching elements of the polarity switching inverter circuit to the ON state and switching the DC current from the power supply main circuit to a hot start current having a large current value. Energize the consumable electrode through the main winding of the reactor to start the arc, and then Source consumable electrode AC arc welding power source, characterized in that the current by converting the DC current of the constant from the main circuit to an alternating current by said polarity switching inverter circuit.   A power supply main circuit for supplying a DC current and a DC voltage, a reactor composed of a main winding and an iron core connected in series to the output of the power supply main circuit, and the reactor has a current value for supplying current to the main winding of a predetermined current When the value is less than the value, the inductance value increases, and when the current value is equal to or greater than the predetermined current value, the iron core is saturated and becomes a very small inductance value. A consumable electrode comprising a first switching element, a fourth switching element, and a polarity switching inverter circuit that forms a full bridge from the opposing second and third switching elements and supplies an AC output to the consumable electrode In an AC arc welding power source, a resistor and a second short circuit are connected in parallel to the first switching element of the polarity switching inverter circuit. A series circuit comprising switching elements is provided, and at the time of an arc start, the switching element for short circuit is turned on and the third switching element of the polarity switching inverter circuit is turned on, and the main winding from the power supply main circuit, A short-circuit current greater than or equal to the predetermined current value is passed through the short-circuit switching element and the third switching element to saturate the saturable reactor so that the inductance value becomes very small. When contacted with the base material, the short-circuit switching element and the third switching element are turned off, and one of two opposing switching elements of the polarity switching inverter circuit is turned on to turn the power supply main circuit on Switch the DC current from the A consumable electrode characterized in that a consumable electrode is energized through the main winding of a reactor to start an arc, and then a steady DC current is converted into an AC current by the polarity switching inverter circuit from the power supply main circuit. AC arc welding power supply. A first series circuit comprising a resistor and a second short-circuit switching element in parallel with the first switching element of the polarity switching inverter circuit, and a resistor and a third short-circuit switching element in parallel with the fourth switching element And the second short-circuit switching element and the third short-circuit switching element are turned on at the time of an arc start, and the second switching element of the polarity switching inverter circuit is provided. The third switching element is turned on, the main winding, the second short-circuit switching element, the third switching element, the second switching element, and the third short-circuit switching element from the power supply main circuit. Through which the saturable reactor is saturated by passing a short-circuit current greater than or equal to the predetermined current value. When the conductance value is made very small and the consumable electrode contacts the base material by feeding, the second short-circuit switching element, the third short-circuit switching element, the second switching element, and the third switching element Is turned off and one of two opposing switching elements of the polarity switching inverter circuit is turned on to switch the direct current from the power supply main circuit to a hot start current having a large current value. The consumable electrode AC arc welding power source according to claim 4, wherein the consumable electrode is energized through the main winding of the saturable reactor to start an arc.

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