JP4867390B2 - Consumable electrode arc welding apparatus and method - Google Patents

Description

  The present invention relates to a consumable electrode type arc welding apparatus and method that repeats a short circuit state and an arc state at the tip of a welding wire.

In conventional short-circuit transfer type arc welding, there is a method of detecting and controlling the arc generation period. For example, in Patent Document 1, the length of each arc generation period is detected, the output voltage of the welding power source in the arc generation period is reduced in proportion to the detected length of the arc generation period, and the welding current in each arc generation period is calculated. Increase or decrease.
In addition, in short-circuit transfer type arc welding, there are the following Patent Documents 2 to 4 and the like that use an arc welding machine having a current interruption mechanism.

JP-A-11-285821 JP-A-5-318128 JP 2004-249331 A JP 2002-273569 A

However, the conventional consumable electrode type arc welding power source cannot sufficiently reduce welding spatter (metal fine particles melted and liquefied due to high temperature) generated during welding.
Spattering of welding often occurs when the tip of the consumable electrode is scattered in the air. For this reason, if the melted portion of the tip of the consumable electrode can be sufficiently transferred into the molten pool, the occurrence of sputtering can be suppressed.
A welding power source with a current interruption mechanism in the conventional arc welding method is effective in promoting the transition of the consumable electrode tip to the molten pool by reducing the current at the moment when the tip of the consumable electrode contacts the molten pool. It is. However, since the amount of the melted portion at the tip of the consumable electrode varies depending on the welding state, the melted portion at the tip of the consumable electrode is removed from the molten pool at a current interruption time of a certain period as in the conventional arc welding method. It cannot be fully migrated into. If the current interruption time is short, the transition to the molten pool is not sufficient and sputtering occurs. If the current interruption time is long, the tip of the consumable electrode that is not melted during the arc generation period rushes into the molten pool, the state of the molten pool becomes unstable, and also causes spattering.
On the other hand, measuring the arc generation period is one means of knowing the welding state. In the conventional arc welding method, control is performed to reduce the arc current as the arc generation period becomes longer. This control is effective in causing the short circuit to occur periodically, but does not have the effect of suppressing the spatter that occurs because the tip of the consumable electrode cannot move to the molten pool.
The present invention has been made in view of such problems, and by sufficiently transferring the melted portion of the tip of the consumable electrode formed during the arc period into the molten pool, spatter scattered in the air can be obtained. It is an object of the present invention to provide a consumable electrode arc welding apparatus and method for suppressing the same.

In order to solve the above problem, an invention according to claim 1 relates to a consumable electrode type arc welding apparatus, and includes a first rectifier circuit that rectifies an alternating current into a direct current and an output side of the first rectifier circuit. an inverter circuit that converts the high frequency AC output of said first rectifier circuit is connected, the output from the secondary coil output voltage conversion to the two connected by the inverter circuit to the output side of the inverter circuit An insulation transformer, a second rectifier circuit connected to the secondary side first coil to rectify the output of the insulation transformer to make a direct current, and an output side of the second rectifier circuit and a weld that holds the wire A first reactor connected between the first torch and smoothing the output of the second rectifier circuit to give to the welding torch; the first reactor and the welding torch; and the first reactor. Output A current interrupt device for cutting off the flow, and arc welding main circuit composed of,
An arc welding sub-circuit that is connected between the secondary second coil and the welding torch and rectifies the output of the insulation transformer by a third rectifier circuit and then applies the output to the welding torch via a second reactor; ,
A control circuit for controlling the inverter circuit and the current interrupt mechanism based on an input command;
A consumable electrode type arc welding apparatus that temporarily interrupts the current output from the first reactor by the current interrupt mechanism when the tip of the wire shifts from an arc state to a short circuit state during arc welding,
The control circuit calculates the current interruption time length TY by the current interruption mechanism using the following equation using the length TA of the arc generation period immediately before the transition to the short circuit.
TY = TA x α + β
(Here, α is a proportional coefficient of the arc period TA and is a positive real number. Β is a constant and a real number.)

According to a second aspect of the present invention, in the consumable electrode arc welding apparatus according to the first aspect, when the calculated length TY of the current interruption time exceeds a predetermined maximum value, the TY is set to the maximum value. When the calculated current interruption time length TY is less than 0, the TY is set to 0.
According to a third aspect of the present invention, in the consumable electrode type arc welding apparatus according to the second aspect, the maximum value is a command welding current value, a command welding voltage value, a wire material, a wire diameter inputted to the control circuit. The method is characterized in that at least one of the types of shielding gas is determined as a parameter.
The invention according to claim 4 is the consumable electrode type arc welding apparatus according to claim 1, wherein the proportional coefficient α and constant β of the arc period TA are a command welding current value and a command welding voltage value input to the control circuit. In this case, at least one of a wire material, a wire diameter, and a shielding gas type is determined as a parameter.
According to a fifth aspect of the present invention, a first rectifier circuit that rectifies an alternating current into a direct current, and is connected to an output side of the first rectifier circuit to convert an output of the first rectifier circuit into a high-frequency alternating current. an inverter circuit which includes an insulating transformer for outputting the secondary coil output by voltage conversion of two of the inverter circuit is connected to the output side of the inverter circuit, connected to the secondary side first coil An output of the second rectifier circuit connected between a second rectifier circuit that rectifies the output of the isolation transformer to make a direct current, and an output side of the second rectifier circuit and a welding torch holding a wire. A first reactor for smoothing and giving to the welding torch, and a current blocking mechanism arranged between the first reactor and the welding torch and blocking a current output from the first reactor. Arc welder And the road,
An arc welding sub-circuit that is connected between the secondary second coil and the welding torch and rectifies the output of the insulation transformer by a third rectifier circuit and then applies the output to the welding torch via a second reactor; ,
A control circuit for controlling the inverter circuit and the current interrupt mechanism based on an input command;
A consumable electrode type arc welding apparatus that temporarily interrupts the current output from the first reactor by the current interrupt mechanism when the tip of the wire shifts from an arc state to a short circuit state during arc welding,
The control circuit is characterized in that as the input command welding voltage increases, the current interruption time by the current interruption mechanism is lengthened.
The invention according to claim 6 rectifies an alternating current into a direct current, converts the direct current into a high frequency alternating current, converts the high frequency alternating current into a low voltage, and further rectifies the direct current into a large direct current. Is provided to a welding torch that holds the wire by smoothing, and provided with a current interruption mechanism that interrupts the DC large current given to the welding torch,
Furthermore, a part of the voltage-converted high-frequency alternating current is given to the welding torch in parallel with the direct current large current,
A consumable electrode arc welding method that temporarily interrupts the DC large current by the current interrupt mechanism when the tip of the wire transitions from an arc state to a short circuit state during arc welding,
The length TY of the current interruption time by the current interruption mechanism is calculated by the following equation using the length TA of the arc generation period immediately before the short circuit transition.
TY = TA x α + β
(Here, α is a proportional coefficient of the arc period TA and is a positive real number. Β is a constant and a real number.)
The invention according to claim 7 rectifies an alternating current into a direct current, converts the direct current into a high frequency alternating current, converts the high frequency alternating current into a low voltage, and further rectifies the direct current into a large direct current. Is provided to a welding torch that holds the wire by smoothing, and provided with a current interruption mechanism that interrupts the DC large current given to the welding torch,
Furthermore, a part of the voltage-converted high-frequency alternating current is given to the welding torch in parallel with the direct current large current,
A consumable electrode arc welding method that temporarily interrupts the DC large current by the current interrupt mechanism when the tip of the wire transitions from an arc state to a short circuit state during arc welding,
As the command welding voltage increases, the current interruption time by the current interruption mechanism is lengthened.

With the above configuration, the melted part of the tip of the consumable electrode formed during the arc period is sufficiently transferred into the molten pool, so that spatter scattered in the air can be suppressed, and the transition to the molten pool is achieved. Since it can be performed most smoothly when the current is interrupted by the current interrupting mechanism, the sputter can be suppressed by changing the current interrupting time by the amount of the melted portion of the consumable electrode tip.
Further, according to the present invention, attention is paid to the fact that the amount of the melted portion at the tip of the consumable electrode changes depending on the arc period or changes depending on the command voltage, and this is utilized for control.
Further, according to the present invention, the amount of the melted portion of the consumable electrode is predicted based on the arc period or the command voltage, and the current interruption time corresponding to the amount of the melted portion of the consumable electrode is set, whereby the consumable electrode Since the transition of the melted portion to the molten pool can be sufficiently promoted, spattering of consumable electrode arc welding can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a consumable electrode arc welding apparatus of the present invention.
The current of the commercial AC power source 1 is converted into DC by the first rectifier circuit 2. The output of the first rectifier circuit 2 is converted into a high frequency of 20 to 200 [KHz] by the inverter circuit 3. The output of the inverter circuit 3 is converted into a voltage suitable for welding by the insulation transformer 4, converted into direct current by the second rectifier circuit 5, then passed through the first direct current reactor 6, and the arc welded portion (in the drawing) Arc current is generated in the welding torch 7 and the welding torch 7 of the workpiece 8).
A current interruption mechanism 9 is provided between the second rectifier circuit 5 and the welding torch 7 (between the first DC reactor 6 and the welding torch 7 in FIG. 1). The current interrupting mechanism 9 functions to interrupt the welding current flowing through the first DC reactor 6 according to an instruction from the control circuit 17. As the first DC reactor 6, one having an inductance of 20 [μH] or less is applied for pulse welding.
The above is the arc welding main circuit.
Further, the arc welding apparatus of the present invention has an arc welding sub-circuit 10 in parallel with the second rectifier circuit 5. In the arc welding subcircuit 10, an alternating current having a voltage suitable for welding obtained from the second coil on the secondary side of the insulating transformer 4 passes through the current control circuit 11 and is converted into a direct current by the third rectifier circuit 12. After that, it is output through the second DC reactor 13 to supply current to the arc welded part.
The current control circuit 11 is configured by a switching semiconductor element, and controls the current flowing through the second DC reactor 13 by turning on / off the switching semiconductor with a signal from the control circuit 17. Moreover, what has the inductance of 100-2000 [micro-H] is applied to the 2nd DC reactor 13. FIG.
The arc welding apparatus shown in FIG. 1 is used in combination with an industrial robot or the like (not shown) in this embodiment. At that time, the welding torch 7 constituting the arc welding portion is attached to the tip portion of the robot, and takes various positions and postures as the robot moves. The arc welding apparatus and the robot controller perform welding work in cooperation while communicating with each other.

FIG. 2 is a block diagram in the control circuit 17 of the arc welding apparatus of the present invention.
The host CPU 25 receives a voltage command 30, a current command 31, and a welding method number 32 from an external device such as a robot controller.
Welding method numbers include the type of shielding gas (CO ₂ , MAG, MIG, etc.), wire material (iron, stainless steel, aluminum, etc.), and wire diameter (φ1.2, φ1.0, φ0.9). , Etc.) is a number uniquely assigned in advance for each combination of conditions.
In addition, a number may be individually assigned to each condition such as the type of shielding gas, the material of the wire, the diameter of the wire, and the welding method may be designated by a combination of these numbers.
Various welding conditions corresponding to the designated number are stored in the database memory 26 in advance, and the upper CPU 25 reads out the welding conditions corresponding to the designated number from the database memory 26 and performs digital processing as a lower CPU. Data is exchanged with the signal processor 18.
The digital signal processor 18 takes in the current feedback 14 and the voltage feedback 15 shown in FIG. 1 and outputs a command to the inverter circuit 3 while judging the short-circuit state and arc state of welding, and controls the arc welding current and arc welding voltage. I do. Further, the digital signal processor 18 controls the current interruption mechanism 9.

FIG. 3 is a diagram showing a waveform (a) of a welding current with respect to time and a waveform (b) of a welding voltage by the arc welding apparatus of the present invention. In the consumable electrode type arc welding, a welding wire is sent to a workpiece, the workpiece and the welding wire are short-circuited, and after the short-circuit period, the short-circuit is released to shift to the arc, and arc welding is performed during the arc period TA. Thereafter, a short-circuit period in which the workpiece and the welding wire are short-circuited continues. At this time, the current interrupting mechanism 9 operates to interrupt the current from the first DC reactor 6 for the time TY.
According to the present invention, the time during which the current interrupting mechanism 9 is working, that is, the current interrupting time TY is not fixed, but is made variable based on the arc generation period TA immediately before the current interrupting. Is the relationship between the length TY of the current interruption time and the length TA of the arc generation period immediately before the transition to the short circuit,
TY = TA × α + β (1)
(Α is a proportional coefficient of the arc period TA and is a positive real number. Β is a constant and a real number).
In this calculation, the calculation unit 21 in the digital signal processor 18 calculates the above formula, and controls the current interrupt mechanism 9 based on the calculation result.
As described above, the arc period TA used for calculation of the current interruption time TY in the equation (1) is the same as that of the immediately preceding arc period. That is, in FIG. 3, the arc period TA in FIG. 3 is used to calculate the right current interruption time TY, but the immediately preceding arc period not shown in FIG. 3 is used to calculate the left current interruption time TY.
Further, the proportionality coefficient α and constant β in the equation (1) are the welding voltage (voltage command 30) and welding current value (current command 31) commanded from a robot controller or the like, and the welding method number 32 (shield gas). Type, wire material, or wire diameter).
Further, the maximum value of the current interruption time TY is also determined in advance, and when the value of the current interruption time TY calculated by the equation (1) exceeds the maximum value, the command to the current interruption mechanism 9 is set to the maximum value. Limited. This maximum value varies depending on the commanded welding voltage (voltage command 30) and welding current value (current command 31), the type of shield gas, the material of the wire, and the diameter of the wire.
On the other hand, β may be a negative value, and when the value of TY calculated by Equation (1) is less than 0 at that time, 0 is used for TY.
Furthermore, when the value of the current feedback 14, that is, the arc welding current is smaller than a predetermined value, the calculation unit 21 performs a calculation to exclude the period from the arc period TA.
As described above, the digital signal processor 18 outputs a command to the inverter circuit 3 in parallel with outputting a command to the current interrupt mechanism 9, and as a result, a welding current and welding voltage waveform as shown in FIG. 3 is realized. To do.

In the second embodiment of the present invention, in the arc welding apparatus shown in FIGS. 1 and 2, the current interruption mechanism 9 is controlled based on the following equation (2).
TB is a real number, and the real number TB is a function (time) obtained by subtracting a value preset in the database memory 26 from the value of the voltage command 30.
TY = TB × a + b (2)
(Here, a is a proportional coefficient and is a positive real number. B is a constant and a real number.)
If this difference is less than 0, 0 is used for TB. This processing is performed by the host CPU 25 and the digital signal processor 18 in FIG. As apparent from the equation (2), when the voltage command 30 is large, the current cutoff time TY is long, and when the voltage command 30 is small, TY is short.
Further, as in the first embodiment, the proportionality coefficient a and the constant b in Expression (2) are the welding voltage (voltage command 30) and welding current value (current command 31) commanded from the robot controller or the like, the type of shield gas, Varies with wire material and wire diameter.
Further, the maximum value of the current interruption time TY is also determined in advance, and when the value of TY calculated by the equation (2) exceeds the maximum value, the command to the current interruption mechanism 9 is limited to the maximum value. . This maximum value varies depending on the commanded welding voltage (voltage command 30) and welding current value (current command 31), the type of shield gas, the material of the wire, and the diameter of the wire.
On the other hand, b may be a negative value. When the value of TY calculated by Equation (2) is less than 0 at that time, 0 is used for TY.

  In this embodiment, arc welding using a robot is taken as an example. However, the present invention is not limited to this, and it is obvious that the present invention can be widely applied to consumable electrode arc welding.

It is a block diagram of the arc welding apparatus which shows the Example of this invention. It is a block diagram of a control circuit of the present invention. It is a figure which shows the welding current waveform and welding voltage waveform by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commercial alternating current power supply 2 1st rectifier circuit 3 Inverter circuit 4 Insulation transformer 5 2nd rectifier circuit 6 1st DC reactor 7 Welding torch 8 Work piece 9 Current interruption mechanism 10 Arc welding subcircuit 11 Current control circuit 12 3rd Rectifier circuit 13 Second DC reactor 14 Current feedback 15 Voltage feedback 17 Control circuit 18 Digital signal processor 19, 20 A / D converter 21 Operation unit 22 Memory 23 Driver command generation unit 24 Inverter drive driver 25 Host CPU
26 Database memory 30 Voltage command 31 Current command 32 Welding method number

Claims (7)

A first rectifier circuit that rectifies an alternating current into a direct current, an inverter circuit that is connected to an output side of the first rectifier circuit and converts the output of the first rectifier circuit into a high-frequency alternating current; and the inverter circuit and a transformer that outputs from the two secondary coils are connected to the output side by voltage conversion of the output of the inverter circuit of the rectified output of the isolation transformer is connected to the secondary side first coil And connected between the second rectifier circuit for making a direct current and the output side of the second rectifier circuit and the welding torch holding the wire to smooth the output of the second rectifier circuit and give it to the welding torch. An arc welding main circuit comprising: a first reactor; and a current interrupting mechanism that is disposed between the first reactor and the welding torch and that interrupts a current output from the first reactor;
An arc welding sub-circuit that is connected between the secondary second coil and the welding torch and rectifies the output of the insulation transformer by a third rectifier circuit and then applies the output to the welding torch via a second reactor; ,
A control circuit for controlling the inverter circuit and the current interrupt mechanism based on an input command;
A consumable electrode type arc welding apparatus that temporarily interrupts the current output from the first reactor by the current interrupt mechanism when the tip of the wire shifts from an arc state to a short circuit state during arc welding,
The consumable electrode arc welding apparatus, wherein the control circuit calculates a current interruption time length TY by the current interruption mechanism by using the following expression TA using a length TA of an arc generation period immediately before a short circuit transition.
TY = TA x α + β
(Here, α is a proportional coefficient of the arc period TA and is a positive real number. Β is a constant and a real number.) When the calculated length TY of the current interruption time exceeds a predetermined maximum value, the TY is limited to the maximum value,
2. The consumable electrode arc welding apparatus according to claim 1, wherein when the calculated current interruption time length TY is less than 0, the TY is set to 0. 3.   The maximum value is determined using at least one of a command welding current value, a command welding voltage value, a wire material, a wire diameter, and a shielding gas type input to the control circuit as parameters. The consumable electrode type arc welding apparatus according to claim 2.   The proportional coefficient α and constant β of the arc period TA have at least one of a command welding current value, a command welding voltage value, a wire material, a wire diameter, and a shielding gas type input to the control circuit as parameters. 2. The consumable electrode arc welding apparatus according to claim 1, wherein the arc welding apparatus is determined. A first rectifier circuit that rectifies an alternating current into a direct current, an inverter circuit that is connected to an output side of the first rectifier circuit and converts the output of the first rectifier circuit into a high-frequency alternating current; and the inverter circuit and a transformer that outputs from the two secondary coils are connected to the output side by voltage conversion of the output of the inverter circuit of the rectified output of the isolation transformer is connected to the secondary side first coil And connected between the second rectifier circuit for making a direct current and the output side of the second rectifier circuit and the welding torch holding the wire to smooth the output of the second rectifier circuit and give it to the welding torch. An arc welding main circuit comprising: a first reactor; and a current interrupting mechanism that is disposed between the first reactor and the welding torch and that interrupts a current output from the first reactor;
An arc welding sub-circuit that is connected between the secondary second coil and the welding torch and rectifies the output of the insulation transformer by a third rectifier circuit and then applies the output to the welding torch via a second reactor; ,
A control circuit for controlling the inverter circuit and the current interrupt mechanism based on an input command;
A consumable electrode type arc welding apparatus that temporarily interrupts the current output from the first reactor by the current interrupt mechanism when the tip of the wire shifts from an arc state to a short circuit state during arc welding,
The consumable electrode type arc welding apparatus, wherein the control circuit extends a current interruption time by the current interruption mechanism as an input command welding voltage increases. AC current is rectified to direct current, the direct current is converted to high frequency alternating current, the high frequency alternating current is converted to low voltage, and further rectified to direct current high current, the direct current large current is smoothed and the wire is held. Provided to the welding torch, and provided with a current interruption mechanism that interrupts the DC large current given to the welding torch,
Furthermore, a part of the voltage-converted high-frequency alternating current is given to the welding torch in parallel with the direct current large current,
A consumable electrode arc welding method that temporarily interrupts the DC large current by the current interrupt mechanism when the tip of the wire transitions from an arc state to a short circuit state during arc welding,
A consumable electrode type arc welding method, wherein the length TY of the current interruption time by the current interruption mechanism is calculated by the following equation using the length TA of the arc generation period immediately before the transition to the short circuit.
TY = TA x α + β
(Here, α is a proportional coefficient of the arc period TA and is a positive real number. Β is a constant and a real number.) AC current is rectified to direct current, the direct current is converted to high frequency alternating current, the high frequency alternating current is converted to low voltage, and further rectified to direct current high current, the direct current large current is smoothed and the wire is held. Provided to the welding torch, and provided with a current interruption mechanism that interrupts the DC large current given to the welding torch,
Furthermore, a part of the voltage-converted high-frequency alternating current is given to the welding torch in parallel with the direct current large current,
A consumable electrode arc welding method that temporarily interrupts the DC large current by the current interrupt mechanism when the tip of the wire transitions from an arc state to a short circuit state during arc welding,
A consumable electrode type arc welding method characterized in that as the command welding voltage increases, the current interruption time by the current interruption mechanism is lengthened.

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