WO2015186474A1

WO2015186474A1 - Arc start control method for consumable electrode type arc welding, and welding device

Info

Publication number: WO2015186474A1
Application number: PCT/JP2015/063496
Authority: WO
Inventors: 昇吾中司; 英市佐藤; 敦史福永
Original assignee: 株式会社神戸製鋼所
Priority date: 2014-06-06
Filing date: 2015-05-11
Publication date: 2015-12-10
Also published as: CN106413966B; CN106413966A; KR101960151B1; JP6320851B2; JP2015229187A; KR20160147056A

Abstract

The purpose of the present invention is to suppress wire fusion and spatter formation associated with the wire fusion during the arc start period. The present invention provides an arc start control method for consumable electrode type arc welding, wherein a welding wire is fed, at a first time point (t1), toward an object to be welded, the fed welding wire makes contact with the object to be welded so that a welding current (I) flows through the welding wire and the object to be welded, and an arc is generated by the welding current (I) in order to start welding. In this method, an initial welding current (Ia) is supplied as the welding current (I) when the welding wire has come into contact, at a second time point (t2), with the object to be welded, and a steady-state welding current (Ir) which is higher than the initial welding current (Ia) is supplied as the welding current (I) after a predetermined set time period (T) has elapsed from the start of the supply of the initial welding current (Ia).

Description

Arc start control method and welding apparatus for consumable electrode arc welding

The present invention relates to an arc start control method and welding apparatus for consumable electrode arc welding.

For example, in gas shielded arc welding using a consumable electrode type, when starting a welding operation, a short-circuit current is caused to flow by bringing both electrodes into contact with each other while a voltage is applied between the welding wire and the workpiece. The arc is started by fusing the welding wire with an electric current and generating an arc between them.

As a prior art described in the publication, when the welding wire comes into contact with the work piece, the welding wire is stopped and a predetermined large initial short-circuit current is supplied from the welding power source, and welding is performed by applying the initial short-circuit current. In the arc start control method in which the tip of the wire is melted and an arc is generated, and the welding wire is fed at a predetermined steady feeding speed at the time of the arc and a steady welding current is energized. When the arc is generated by melting the tip of the welding wire by energizing the short-circuit current, a predetermined burnup suppression period is provided, and the welding wire feed is stopped during the burnup suppression period. There is one that energizes a small current burnup suppression current and energizes a steady welding current after the completion of the burnup suppression period (see Patent Document 1).

In addition, as a prior art described in other publications, the maximum value of the load current is suppressed to 400 A or less and the short-circuit occurrence interval is set to 50 msec or less in the initial period from the arc start until the load current is stabilized and reaches a steady state. There is one that performs initial control (see Patent Document 2).

Furthermore, as a prior art described in other publications, when welding is started, an initial arc is generated by bringing a welding wire fed from a welding torch into contact with an object to be welded and energizing an initial current, and then separating the welding wire. There is an arc start control method of consumable electrode arc welding in which a transition to a steady arc is made after the start of the current, and an initial current rises with a slope (see Patent Document 3).

Furthermore, as a prior art described in other publications, during the arc start period, the welding voltage is continuously controlled so as to synchronize the change between the wire feeding speed and the welding voltage, and further the welding voltage associated with the wire feeding speed. Is applied for a predetermined length of time (see Patent Document 4).

Also, as a prior art described in other publications, there is an arc start control method for a welding robot that detects a welding current at the time of arc start and moves a welding torch attached to the welding robot based on the detection result. In this prior art, when the welding current does not continuously flow for a predetermined time, the movement of the welding torch in the welding line direction by the operation of the welding robot remains stopped. On the other hand, when the welding current flows continuously for a predetermined time, movement of the welding torch in the welding line direction by the operation of the welding robot is started (see Patent Document 5).

JP 2004-25265 A JP 2008-12580 A JP 2008-149361 A JP 2009-101370 A JP 2010-172953 A

During the arc start period, if the welding current flows too much in the welding wire immediately after the arc is generated until it shifts to a steady state, the welding wire becomes red hot, and the welding wire melts accordingly. A phenomenon called fusing occurs. When such wire fusing occurs, spatter due to arc breakage, scattering around the fusing welding wire, and the like occur.

An object of the present invention is to suppress wire fusing during the arc start period and the occurrence of spatter accompanying the wire fusing.

The present invention feeds the welding wire toward the workpiece, and when the fed welding wire comes into contact with the workpiece, a welding current is passed through the welding wire and the workpiece, In an arc start control method for consumable electrode arc welding in which welding is started by generating an arc with a welding current, an initial welding current is supplied as the welding current when the welding wire comes into contact with the workpiece. And a step of supplying a steady welding current larger than the initial welding current as the welding current after a predetermined set period has elapsed after the supply of the initial welding current is started. It is said.
In this arc start control method for consumable electrode arc welding, the initial welding current is selected from a range of 100 (A) to 300 (A), and the steady welding current is 350 (A). ) And 550 (A) or less.
Further, the setting period may be selected from a range of 25 (msec) or more and less than 700 (msec).
Furthermore, it can be characterized by having a step of providing a rising slope between the step of supplying the initial welding current and the step of supplying the steady welding current.
Furthermore, in the step of providing the rising slope, the rising slope can be set to 1500 (A / 100 msec) or less.
From another point of view, the welding apparatus according to the present invention includes a power supply unit that supplies a welding current to a workpiece via a welding wire, and the welding wire that is fed toward the workpiece. When the workpiece is contacted, an initial welding current is supplied from the power supply unit as the welding current, and after a predetermined set period has elapsed since the start of the supply of the initial welding current, A current control unit that supplies a steady welding current larger than the initial welding current from the power supply unit.
In this welding apparatus, a control device that controls welding work on the workpiece, a determination unit that detects that the initial welding current has flowed through the welding wire and the workpiece, and a power source that drives the power source unit A drive unit, wherein the control unit determines that the initial welding current has flowed through the welding wire and the workpiece by the determination unit, and further, after the predetermined set time has elapsed, A current setting signal for supplying the steady welding current from the power supply unit to the drive unit may be output.

According to the present invention, it is possible to suppress the occurrence of wire fusing during the arc start period and the occurrence of spatter accompanying the wire fusing.

It is a figure showing a schematic structure of a welding system concerning an embodiment of the invention. It is a figure for demonstrating the structure of the power supply control means provided in the welding system. It is a flowchart for demonstrating the procedure of the arc start in the welding system of this Embodiment. It is a timing chart for demonstrating an example of the procedure of the arc start in the welding system of this Embodiment. It is a timing chart for demonstrating the modification of the procedure of the arc start in the welding system of this Embodiment. It is a figure for demonstrating the other structural example of the power supply control means provided in the welding system.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a schematic configuration of a welding system 1 according to an embodiment of the present invention. The welding system 1 performs welding of the workpiece 200 by a carbon dioxide arc welding method using carbon dioxide gas as a shielding gas among consumable electrode type (melting electrode type) gas shielded arc welding methods.

A welding system 1 as an example of a welding apparatus includes a welding torch 10 that welds a workpiece 200 using a welding wire 100, and a robot arm 20 that holds the welding torch 10 and sets the position and orientation of the welding torch 10. The wire feeding device 30 that feeds the welding wire 100 to the welding torch 10, the shield gas supply device 40 that feeds the shielding gas (here, carbon dioxide gas) to the welding torch 10, and the welding wire 100 via the welding torch 10. And a power supply device 50 for controlling the welding current, the feeding speed, the welding speed, and the like.

Further, the welding system 1 includes a robot control device 60 for controlling the robot arm 20 as an example of a control device for controlling a welding operation to the workpiece 200 by the welding torch 10 and the robot arm 20. The robot controller 60 controls the movement and the speed (welding speed) of the welding torch 10 (welding wire 100) provided in the robot arm 20. The robot control device 60 and the power supply device 50 can be configured to transmit and receive data and control signals.

The welding wire 100 used in the welding system 1 may be either a solid wire not containing flux or a flux-cored wire containing flux.
Further, the welding current used in the welding system 1 may be either direct current or alternating current.

FIG. 2 is a diagram for explaining the configuration of the power supply control means provided in the welding system 1 shown in FIG.
A power supply device 50 as a power supply control unit includes a switch 51 that receives an instruction to start welding by an operator, a welding current setting unit 52 that sets a welding current to be supplied to the welding wire 100, and welding using the wire feeding device 30. A feed rate setting unit 53 that sets the feed rate of the wire 100 and a welding current that converts a set value of the welding current set by the welding current setting unit 52 into a set value of the feed rate in the feed rate setting unit 53 / Feed speed conversion unit 54. Further, the power supply device 50 drives the power supply unit 55 based on the setting by the power supply unit 55 that supplies a welding current between the welding torch 10 (welding wire 100) and the workpiece 200 and the welding current setting unit 52. A power supply drive unit 56 and a welding current detection unit 57 that detects a welding current flowing from the welding torch 10 to the workpiece 200 via the welding wire 100 are provided. Furthermore, the power supply device 50 determines that the welding current has flowed based on the detection result of the welding current by the welding current detection unit 57, and outputs a determination result (current detection result). An energization determination unit 59 that determines that the welding current has flowed for a predetermined time based on the determination result by the unit 58 and outputs the determination result (energization determination result) is provided. In the present embodiment, the welding current setting unit 52 has a function as a current control unit.

Next, an arc start procedure in the welding method using the welding system 1 of the present embodiment will be described.
FIG. 3 is a flowchart for explaining an arc start procedure in welding system 1 of the present embodiment. FIG. 4 is a timing chart for explaining an example of an arc start procedure in the welding system 1 of the present embodiment.

4 shows the welding start signal S input from the switch 51 to the welding current setting unit 52, the feeding speed setting unit 53, and the power source driving unit 56, and the feeding speed setting unit 53 is connected to the wire feeding device 30. The feeding speed setting signal F to be output, the actual feeding speed V of the welding wire 100 that the wire feeding device 30 feeds based on the feeding speed setting signal F, and the welding current setting unit 52 determines the welding current / Welding current setting signal C output to feeding speed conversion unit 54 and power supply driving unit 56, welding current I actually flowing to welding wire 100 based on welding current setting signal C, and welding current I by welding current detection unit 57 On the basis of the current detection signal D output from the current determination unit 58 to the feed speed setting unit 53 and the energization determination unit 59 based on the detection of the current and the output of the current detection signal D from the current determination unit 58, the energization determination unit 59 is welded. Current It shows the relationship between the current judgment signal J to be output to the tough 52. Here, the welding start signal S, the current detection signal D, and the energization determination signal J can take two states of low level (L) and high level (H), respectively.

In the initial state before the arc start, the welding start signal S, the current detection signal D, and the energization determination signal J are set to “L”, the feeding speed setting signal F and the welding current setting signal C are set to “0”, respectively. It is assumed that it is set. As a result, the feeding speed V and the welding current I are also assumed to be “0”. Furthermore, in the initial state before the arc start, the tip of the welding wire 100 held by the welding torch 10 is arranged at a position away from the workpiece 200 by a predetermined distance.

Now, the procedure of the process at the arc start will be described with reference to FIG.
First, it is identified whether the welding start signal S input from the switch 51 is “L” or “H” (step 10). If the welding start signal S is “L” in step 10 (NO), the process returns to step 10 and the process is continued.

On the other hand, when the welding start signal S is “H” in Step 10 (YES), the welding current setting unit 52 changes the welding current setting signal C from “0” to “initial welding current setting value Ca” ( Step 20). Further, the feeding speed setting unit 53 changes the feeding speed setting signal F from “0” to “starting feeding speed setting value Fi” (step 30).

Next, it is determined whether the current detection signal D input from the current determination unit 58 is “L” or “H” (step 40). If the current detection signal D is “L” in step 40 (NO), the process returns to step 40 and the process is continued.

On the other hand, when the current detection signal D is “H” in step 40 (YES), the feed speed setting unit 53 changes the feed speed setting signal F from “start feed speed setting value Fi” to “initial feed”. Change to “feed speed set value Fa” (step 50).

Subsequently, it is identified whether the energization determination signal J input from the energization determination unit 59 is “L” or “H” (step 60). When the energization determination signal J is “L” in step 60 (NO), the process returns to step 60 and the process is continued.

On the other hand, when the energization determination signal J is “H” in step 60 (YES), the welding current setting unit 52 changes the welding current setting signal C from “initial welding current setting value Ca” to “steady welding current setting value Cr”. (Step 70). Further, the feeding speed setting unit 53 changes the feeding speed setting signal F from “initial feeding speed setting value Fa” to “steady feeding speed setting value Fr” (step 80).
Thereby, the arc start is completed.

Here, the arc start procedure described above will be specifically described with reference to the timing chart shown in FIG.

When the switch 51 is switched from “off” to “on” at the first time t1, the welding start signal S is changed from “L” to “H” (YES in step 10). As the welding start signal S is changed from “L” to “H”, the welding current setting unit 52 changes the welding current setting signal C from “0” to “initial welding current setting value Ca”. 20: 0 <Ca), and the feeding speed setting unit 53 changes the feeding speed setting signal F from “0” to “starting feeding speed setting value Fi” (step 30: 0 <Fi).

At the first time t1, the welding current setting signal C is set to the initial welding current setting value Ca. Accordingly, the power supply unit 55 applies a welding voltage corresponding to the initial welding current set value Ca between the welding wire 100 and the workpiece 200. However, at this time, feeding of the welding wire 100 has just started, and the tip of the welding wire 100 has not reached the workpiece 200. Therefore, at this time, the welding current I is maintained at “0”, and the current detection signal D and the energization determination signal J also remain “L”.

Also, at the first time t1, the feeding speed setting signal F is set to the starting feeding speed setting value Fi, whereby the wire feeding device 30 starts feeding the welding wire 100. However, since the feed speed V does not immediately reach the start feed speed Vi according to the start feed speed set value Fi from 0, it takes time to accelerate, so there is a slight delay (lag). Along with this, the starting feed speed Vi is reached.

Next, when the tip of the welding wire 100 reaches (contacts) the workpiece 200 at the second time t2 when the time has elapsed from the first time t1, according to the initial welding current set value Ca. The initial welding current Ia begins to flow as the welding current I through the welding wire 100 and the workpiece 200 by the set welding voltage. Further, as the initial welding current Ia flows through the welding wire 100, the tip side of the welding wire 100 is melted, and an arc (not shown) is generated between the welding wire 100 and the workpiece 200.

That the welding current I (initial welding current Ia) has started to flow in this way is detected by the welding current detection unit 57 and the detection result is output to the current determination unit 58. Receiving this, the current determination unit 58 changes the output current detection signal D from “L” to “H” (YES in Step 40). As the current detection signal D is changed from “L” to “H”, the feeding speed setting unit 53 changes the feeding speed setting signal F from “starting feeding speed setting value Fi” to “initial feeding”. Change to “speed set value Fa” (step 50: Fi <Fa).

At the second time t2, the feeding speed setting signal F is set to the initial feeding speed setting value Fa, whereby the wire feeding device 30 starts changing the feeding speed V of the welding wire 100. However, the feed speed V does not immediately reach the initial feed speed Va corresponding to the initial feed speed set value Fa from the start feed speed Vi, but takes some time for acceleration. The initial feeding speed Va is reached with a lag).

Also, as the current detection signal D is changed from “L” to “H” at the second time t2, the energization determination unit 59 starts measuring time.

After that, when reaching the third time t3 after the preset time T has elapsed from the second time t2, the energization determination unit 59 changes the energization determination signal J to be output from “L” to “H”. Change (YES in step 60). As the energization determination signal J is changed from “L” to “H”, the welding current setting unit 52 changes the welding current setting signal C from “initial welding current setting value Ca” to “steady welding current setting value Cr”. (Step 70: Ca <Cr), and the feeding speed setting unit 53 changes the feeding speed setting signal F from “initial feeding speed setting value Fa” to “steady feeding speed setting value Fr”. (Step 80: Fa <Fr).

At the third time t3, the welding current setting signal C is set to the steady welding current set value Cr, so that the welding current I flowing through the welding wire 100 shifts from the initial welding current Ia to the steady welding current Ir (Ia < Ir).

Further, at the third time t3, the wire feeding device 30 starts changing the feeding speed V of the welding wire 100 by setting the feeding speed setting signal F to the steady feeding speed setting value Fr. However, the feed speed V does not immediately reach the steady feed speed Vr corresponding to the steady feed speed set value Fr from the initial feed speed Va, but takes some time for acceleration. ) To reach the steady feeding speed Vr.
Thereby, the arc start is completed.

In the example shown in FIG. 4, at the third time t3, the welding current setting signal C is instantaneously switched from the initial welding current setting value Ca to the steady welding current setting value Cr, whereby the welding current I is changed to the initial welding current Ia. To the steady welding current Ir. However, the method for switching the welding current I from the initial welding current Ia to the steady welding current Ir is not limited to this.

FIG. 5 is a timing chart for explaining a modification of the arc start procedure in the welding system 1 of the present embodiment.
As shown in FIG. 5, at a third time t3, a slope setting value Cs is provided in the welding current setting signal C when the welding current setting signal C is switched from the initial welding current setting value Ca to the steady welding current setting value Cr. The steady welding current set value Cr may be reached at a fourth time t4 when a predetermined time has elapsed from the third time t3. In this case, the welding current I that is the initial welding current Ia at the third time t3 gradually increases at the rising slope Is from the third time t3 to the fourth time t4, and is steady at the fourth time t4. The welding current Ir is reached. Further, in this example, the inclination setting value Cs is set in the feeding speed setting signal F along with the setting of the inclination setting value Cs in the welding current setting signal C. The rising slope Vs is also set for the speed V.

In the welding system 1 of the present embodiment, when the work piece 200 and the welding wire 100 are in contact with each other, an initial welding current Ia smaller than the steady welding current Ir is supplied as the welding current I, and the initial welding current Ia is set in advance. After flowing for a predetermined set period T, the initial welding current Ia is switched to the target steady welding current Ir.
As a result, it is possible to suppress the fusing (wire fusing) of the welding wire 100 caused by the welding current I immediately after the arc start and the increase in spatter accompanying the wire fusing.

Further, in the example shown in FIG. 5 in the welding system 1 of the present embodiment, the rising slope Is is provided when switching from the initial welding current Ia to the steady welding current Ir.
At the time of switching from the initial welding current Ia to the steady welding current Ir, the amount of current supplied to the welding wire 100 temporarily increases. Accordingly, at the time of switching, the red heat of the welding wire 100 increases, so that the welding wire 100 is easily softened and wire fusing is likely to occur.
For this reason, the steep red heat of the welding wire 100 can be suppressed by providing the rising slope Is. As a result, particularly when the steady welding current Ir is set to be high, it is possible to suppress wire fusing and burnback associated therewith, and to suppress an increase in spatter.

Here, the characteristics of various conditions in the arc start control method of gas shielded arc welding using the welding system 1 of the present embodiment will be described.

<Initial welding current Ia>
The period during which the initial welding current Ia flows is provided to stabilize the arc before reaching the steady welding current Ir. The smaller the welding current I, the smaller the Joule heat generated in the welding wire 100 and the more stable droplet transfer, so no lower limit is defined. However, if the welding current I exceeds 350 (A), the Joule heat generated in the welding wire 100 is increased, wire breakage is likely to occur, and the droplet transfer is also a globule transfer welding in which the droplet immediately below the wire becomes large. As a result, wire fusing is likely to occur and sputtering is likely to increase. Therefore, the initial welding current Ia is preferably 300 (A) or less. In addition, since the arc is most stable in the range where the welding current I is 100 (A) to 250 (A) in the short-circuit transition, the more preferable range of the initial welding current Ia is 100 (A) to 250 ( A). The initial welding current Ia does not include 0 (A).

<Steady welding current Ir>
The frequency of wire fusing changes depending on the value of the steady welding current Ir transferred from the initial welding current Ia, and the higher the steady welding current Ir, the more likely the wire fusing due to the red heat effect occurs. Here, in the case where the steady welding current Ir is less than 350 (A), since red heat hardly occurs, the effect of the present invention hardly appears. On the other hand, when the steady welding current Ir exceeds 600 (A), welding is not stable. Therefore, the range of the steady welding current Ir is defined as 350 (A) to 600 (A). Further, in order to perform stable welding, it is more preferable that the current is 350 (A) to 550 (A).

<Set period T>
When the set period T is set to 20 (msec) or longer, the arc is stabilized while the initial welding current Ia is flowing, and therefore wire fusing at the time of transition from the initial welding current Ia to the steady welding current Ir is further suppressed. It becomes possible. Therefore, the set period T is preferably 20 (msec) or more, and more preferably 50 msec or more, since the arc is more stable. However, even if the setting period T through which the initial welding current Ia flows is excessively long, the efficiency is reduced. Therefore, the setting period T is preferably less than 700 (msec).

<Rising slope Is>
When there is a difference between the steady welding current Ir and the initial welding current Ia, the welding wire 100 is easily red-hot, and the larger the current difference between the two is, the easier the welding wire 100 is softened by red heat. Along with this, wire fusing is likely to occur when the initial welding current Ia is shifted to the steady welding current Ir. It is preferable to provide the slope Is. By giving such a rising inclination Is, steep red heat of the wire can be suppressed, and therefore, it is more preferable to provide an inclination of 50 (A / 100 msec) or more.
Note that the rising slope Is does not have to be a linear and continuous value (linear function of time) as shown in FIG. 5, and may be a curve or a step.

In the above description, the setting of the welding speed at the arc start was not specifically described. However, in order to match the welding amount at the bead start end, control may be performed to change the welding speed between the period in which the initial welding current Ia is supplied and the period in which the steady welding current Ir is supplied. For example, the welding speed during the period when the initial welding current Ia is supplied is set to be equal to or lower than the welding speed (the welding speed under this condition) during the period when the steady welding current Ir is supplied. This makes it possible to match the welding amount between the period in which the initial welding current Ia is supplied and the period in which the steady welding current Ir is supplied, and the bead shape of the start portion is stabilized.

As an example, when the steady feeding speed Vr is 20 (mpm) and the initial feeding speed Va is 10 (mpm), the welding speed during the period in which the steady welding current Ir is supplied (the welding speed under this condition) is 0. When it is 0.6 (mpm), the welding speed during the period in which the initial welding current Ia is supplied is controlled to 0.3 (mpm).

In the above description, the steady welding current Ir is controlled to a constant value. However, the present invention is not limited to this, and it may be a pulse current that repeatedly applies a peak current to the base current at a certain frequency. Absent.

Next, another configuration example of the welding system 1 in the present embodiment will be described.
In the configuration example shown in FIG. 2, the arc start control according to the present embodiment is realized by the function provided in the power supply device 50. On the other hand, the robot control device 60 may be configured to bear a part of the function for realizing the arc start control according to the present embodiment.

FIG. 6 is a diagram for explaining another configuration example of the power supply control means provided in the welding system 1 according to the embodiment of the present invention.
In the configuration example illustrated in FIG. 6, the switch 51, the welding current setting unit 52, and the energization determination unit 59 provided in the power supply device 50 in the configuration example illustrated in FIG. 2 are provided in the robot control device 60. In addition, the power supply device 50 includes a power supply device interface unit 501 for sending and receiving various signals to and from the robot control device 60. The robot control device 60 sends and receives various signals to and from the power supply device 50. A control device interface unit 601 is provided.

Here, the functions of the switch 51, the welding current setting unit 52, and the energization determining unit 59 provided in the robot control device 60 shown in FIG. 6 are the same as those provided in the power supply device 50 shown in FIG. Therefore, detailed description thereof is omitted here. In the example shown in FIG. 6, the welding start signal S, the welding current setting signal C, and the current detection signal D are exchanged between the power supply device 50 and the robot control device 60.

Note that the functions of the welding current setting unit 52 and the feeding speed setting unit 53 in the present embodiment can be realized by an analog circuit or a digital circuit. Here, when the welding current setting unit 52 and the feed rate setting unit 53 are realized by a digital circuit, for example, a program describing the output procedure of each control signal at each timing described with reference to FIGS. Is stored in a memory provided in the welding current setting unit 52 or the feeding speed setting unit 53, the function of the present embodiment can be implemented. And each function is implement | achieved when CPU provided in the welding current setting part 52 and the feeding speed setting part 53 runs the program stored in memory.

Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

<Arc break investigation>
The inventor uses the welding system 1 shown in FIG. 1 and sets the welding wire 100 type, the diameter of the welding wire 100, the initial welding current Ia and the steady welding current Ir supplied to the welding wire 100, and the set period as welding conditions. Experiments for welding the workpiece 200 with different T and rising slope Is were performed, and the occurrence of arc breakage at the time of arc start was evaluated.

In this experiment, as the type (wire type) of the welding wire 100, a solid wire not containing flux and a flux-cored wire containing flux were used.
In this experiment, the welding wire 100 having a diameter of φ1.2 (mm) and φ1.4 (mm) was used.
Further, in this experiment, carbon dioxide gas (100% CO ₂ ) was used as the shielding gas.
Furthermore, in this experiment, a steel plate defined by JIS G3106 SM490A was used as the workpiece 200 to be welded.

In this experiment, the initial welding current Ia was selected from the range of 100 (A) to 550 (A).
Furthermore, in this experiment, the steady welding current Ir was selected from the range of 250 (A) or more and 550 (A) or less.
Furthermore, in this experiment, the set period T was selected from the range of 0 (mesc) to 800 (msec).
In this experiment, the rising slope Is was selected from the range of no slope to 1500 (A / 100 msec) or less.

In this experiment, for each condition, welding with a weld length of 10 cm was performed 30 times each by bead-on-plate downward welding, and the number of arc breaks that occurred in 30 times was counted, and the arc breakage rate (arc breakage rate) Frequency / 30 times × 100%). When the arc break occurrence rate is 0%, the evaluation is “Good”, and when the arc break occurrence rate is 20% or less, the evaluation is “Good”, and the arc break occurrence rate is 20%. An evaluation of “x” was given as the result of being unacceptable.

Tables 1 to 17 shown below show the relationship between the 336 welding conditions (No. 1 to No. 336) used in this experiment and the obtained evaluation results. In Tables 1 to 17, the solid wire is represented as “Solid”, and the flux-cored wire is represented as “Cored”.

Here, No. 1-No. Reference numeral 50 (Tables 1 to 5) shows comparative examples of the present invention, and the rest show examples of the present invention.

First, Tables 1 to 4 will be described.
Table 1 shows a case where a φ1.2 solid wire is used as the welding wire 100 and the initial welding current Ia and the steady welding current Ir, which are the conventional arc start method, have the same magnitude (Ia = Ir). The magnitudes of the initial welding current Ia and the steady welding current Ir at this time were 250 (A) to 500 (A).

Table 2 shows a case where a flux-cored wire of φ1.2 is used as the welding wire 100 and the initial welding current Ia and the steady welding current Ir, which are conventional arc start methods, have the same magnitude (Ia = Ir). Yes. The magnitudes of the initial welding current Ia and the steady welding current Ir at this time were 250 (A) to 500 (A).

Further, Table 3 shows a case where a solid wire of φ1.4 is used as the welding wire 100 and the initial welding current Ia and the steady welding current Ir, which are conventional arc start methods, have the same magnitude (Ia = Ir). . The initial welding current Ia and the steady welding current Ir at this time were 250 (A) to 550 (A).

Furthermore, Table 4 shows a case where a φ1.4 flux cored wire is used as the welding wire 100 and the initial welding current Ia and the steady welding current Ir, which are the conventional arc start method, have the same magnitude (Ia = Ir). ing. The initial welding current Ia and the steady welding current Ir at this time were 250 (A) to 550 (A).

Thus, in Table 1 and Table 2, the wire type of the same wire diameter is different, but in Table 1 and Table 3, the wire diameter of the same wire type is different. Further, Table 2 and Table 4 have different wire diameters with the same wire type, and Tables 3 and 4 have different wire types with the same wire diameter. In Tables 1 to 4, in the conventional arc start method, since the initial welding current Ia and the steady welding current Ir have the same magnitude, the set period T is inevitably set to “0” and the rising slope Is. Becomes “none”.

Next, Table 5 will be described.
Table 5 shows a case where a solid wire of φ1.2 is used as the welding wire 100 and the initial welding current Ia is smaller than the steady welding current Ir (Ia <Ir). At this time, the magnitude of the steady welding current Ir was 500 (A), and the magnitude of the initial welding current Ia was 100 (A).

Thus, although the wire type and the wire diameter are the same in Table 1 and Table 5, the magnitude relationship between the initial welding current Ia and the steady welding current Ir is different. In Table 5, the set period T was set to 700 (msec) to 800 (msec), and the rising slope Is was set to 1500 (A / 100 msec).

Next, Tables 6 to 8 will be described.
Table 6 shows that a φ1.2 solid wire is used as the welding wire 100, the initial welding current Ia is smaller than the steady welding current Ir (Ia <Ir), and the initial welding current Ia is fixed to 100 (A). Shows the case. The magnitude of the steady welding current Ir at this time was 350 (A) to 500 (A).

Table 7 also shows that a φ1.2 solid wire is used as the welding wire 100, the initial welding current Ia is smaller than the steady welding current Ir (Ia <Ir), and the initial welding current Ia is 200 (A). The case of fixing is shown. The magnitude of the steady welding current Ir at this time was 350 (A) to 500 (A).

Further, Table 8 uses a φ1.2 solid wire as the welding wire 100, reduces the initial welding current Ia compared to the steady welding current Ir (Ia <Ir), and sets the initial welding current Ia to 300 (A). The case of fixing is shown. The magnitude of the steady welding current Ir at this time was 350 (A) to 500 (A).

Thus, in Table 1 and Tables 6 to 8, the wire type and the wire diameter are the same, but the magnitude relationship between the initial welding current Ia and the steady welding current Ir is different. In Tables 6 to 8, the wire type and the wire diameter are the same, but the magnitude of the initial welding current Ia is different. In Table 6, the set period T was set to 0 (msec) to 650 (msec), and the rising slope Is was set to 150 (A / 100 msec) to 1500 (A / 100 msec). In Table 7, the set period T is set to 0 (msec) to 350 (msec), and the rising slope Is is set to 100 (A / 100 msec) to 1000 (A / 100 msec). Further, in Table 8, the setting period T is set to 0 (msec) to 250 (msec), and the rising slope Is is set to 50 (A / 100 msec) to 1000 (A / 100 msec).

Subsequently, Tables 9 to 11 will be described.
Table 9 uses a flux-cored wire of φ1.2 as the welding wire 100, reduces the initial welding current Ia compared to the steady welding current Ir (Ia <Ir), and fixes the initial welding current Ia to 100 (A). Shows the case. The magnitude of the steady welding current Ir at this time was 350 (A) to 500 (A).

Table 10 shows that a flux-cored wire having a diameter of φ1.2 is used as the welding wire 100, the initial welding current Ia is made smaller than the steady welding current Ir (Ia <Ir), and the initial welding current Ia is 200 (A). The case where it fixes to is shown. The magnitude of the steady welding current Ir at this time was 350 (A) to 500 (A).

Further, Table 11 shows that a flux-cored wire of φ1.2 is used as the welding wire 100, the initial welding current Ia is made smaller than the steady welding current Ir (Ia <Ir), and the initial welding current Ia is 300 (A). The case where it fixes to is shown. The magnitude of the steady welding current Ir at this time was 350 (A) to 500 (A).

Thus, although the wire type and the wire diameter are the same in Table 2 and Tables 9 to 11, the magnitude relationship between the initial welding current Ia and the steady welding current Ir is different. Tables 6 to 8 and Tables 9 to 11 have the same wire diameter but different wire types. Further, in Tables 9 to 11, although the wire type and the wire diameter are the same, the magnitude of the initial welding current Ia is different. In Table 9, the set period T was set to 0 (msec) to 250 (msec), and the rising slope Is was set to 50 (A / 100 msec) to 1500 (A / 100 msec). In Table 10, the set period T is set to 0 (msec) to 325 (msec), and the rising slope Is is set to 100 (A / 100 msec) to 1500 (A / 100 msec). Further, in Table 11, the set period T is set to 0 (msec) to 175 (msec), and the rising slope Is is set to 50 (A / 100 msec) to 1500 (A / 100 msec).

Next, Table 12 to Table 14 will be described.
Table 12 uses a φ1.4 solid wire as the welding wire 100, reduces the initial welding current Ia compared to the steady welding current Ir (Ia <Ir), and fixes the initial welding current Ia to 100 (A). Shows the case. The magnitude of the steady welding current Ir at this time was 400 (A) to 550 (A).

Table 13 shows that a solid wire of φ1.4 is used as the welding wire 100, the initial welding current Ia is made smaller than the steady welding current Ir (Ia <Ir), and the initial welding current Ia is 200 (A). The case of fixing is shown. The magnitude of the steady welding current Ir at this time was 400 (A) to 550 (A).

Further, Table 14 shows that a solid wire of φ1.4 is used as the welding wire 100, the initial welding current Ia is made smaller than the steady welding current Ir (Ia <Ir), and the initial welding current Ia is set to 300 (A). The case of fixing is shown. The magnitude of the steady welding current Ir at this time was 400 (A) to 550 (A).

Thus, in Table 3 and Tables 12 to 14, the wire type and the wire diameter are the same, but the magnitude relationship between the initial welding current Ia and the steady welding current Ir is different. In Tables 6 to 8 and Tables 12 to 14, the wire diameters of the same wire types are different. Further, in Tables 12 to 14, the wire type and the wire diameter are the same, but the magnitude of the initial welding current Ia is different. In Table 12, the set period T is set to 0 (msec) to 275 (msec), and the rising slope Is is set to 250 (A / 100 msec) to 1500 (A / 100 msec). In Table 13, the set period T is set to 0 (msec) to 225 (msec), and the rising slope Is is set to 200 (A / 100 msec) to 1500 (A / 100 msec). Further, in Table 14, the set period T is set to 0 (msec) to 225 (msec), and the rising slope Is is set to 200 (A / 100 msec) to 1500 (A / 100 msec).

Finally, Tables 15 to 17 will be described.
Table 15 uses a φ1.4 flux-cored wire as the welding wire 100, reduces the initial welding current Ia compared to the steady welding current Ir (Ia <Ir), and fixes the initial welding current Ia to 100 (A). Shows the case. The magnitude of the steady welding current Ir at this time was 400 (A) to 550 (A).

Table 16 also shows that a φ1.4 flux cored wire is used as the welding wire 100, the initial welding current Ia is made smaller than the steady welding current Ir (Ia <Ir), and the initial welding current Ia is 200 (A). The case where it fixes to is shown. The magnitude of the steady welding current Ir at this time was 400 (A) to 550 (A).

Further, Table 17 shows that a φ1.4 flux cored wire is used as the welding wire 100, the initial welding current Ia is made smaller than the steady welding current Ir (Ia <Ir), and the initial welding current Ia is 300 (A). The case where it fixes to is shown. The magnitude of the steady welding current Ir at this time was 400 (A) to 550 (A).

Thus, although the wire type and the wire diameter are the same in Table 4 and Tables 15 to 17, the magnitude relationship between the initial welding current Ia and the steady welding current Ir is different. Tables 9 to 11 and Tables 15 to 17 have the same wire type but different wire diameters. Further, in Tables 15 to 17, although the wire type and the wire diameter are the same, the magnitude of the initial welding current Ia is different. In Table 15, the setting period T is set to 0 (msec) to 175 (msec), and the rising slope Is is set to 250 (A / 100 msec) to 1500 (A / 100 msec). In Table 16, the set period T is set to 0 (msec) to 125 (msec), and the rising slope Is is set to 250 (A / 100 msec) to 1500 (A / 100 msec). Further, in Table 17, the set period T is set to 0 (msec) to 200 (msec), and the rising slope Is is set to 150 (A / 100 msec) to 1500 (A / 100 msec).

Next, the results will be described.
As is apparent from Tables 1 to 4, conditions under which the steady welding current Ir is relatively small (Ir ≦ 300 (A) when the wire diameter is φ1.2, Ir ≦ 325 when the wire diameter is φ1.4 ( In A)), the arc breakage occurrence rate at the arc start decreases (improves). However, this range is outside the scope of the subject according to the present invention. On the other hand, under conditions where the steady welding current Ir is relatively large (Ir ≧ 325 (A) when the wire diameter is φ1.2, Ir ≧ 350 (A) when the wire diameter is φ1.4), the arc at the arc start Cutting rate increases (deteriorates).

As can be seen from Table 5, even when the initial welding current Ia is smaller than the steady welding current Ir, the occurrence rate of arc breakage at the arc start increases (deteriorates) under a relatively long set period T. To do.

As is clear from Tables 6 to 8, the arc break occurrence rate at the arc start decreases (improves) under all conditions.

As is clear from Tables 9 to 11, the arc break occurrence rate at the arc start decreases (improves) under all conditions.

As is clear from Tables 12 to 14, the arc break occurrence rate at the arc start decreases (improves) under all conditions.

As is clear from Tables 15 to 17, the arc break occurrence rate at the arc start decreases (improves) under all conditions.

<Flying matter survey>
The inventor uses the welding system 1 shown in FIG. 1 and sets the welding wire 100 type, the diameter of the welding wire 100, the initial welding current Ia and the steady welding current Ir supplied to the welding wire 100, and the set period as welding conditions. Experiments for welding the workpiece 200 with different T and rising slopes Is were performed, and the state of occurrence of scattered objects at the time of arc start was evaluated. Here, the scattered matter refers to a spatter generated from the start to the end of welding, a wire piece of the welding wire 100 scattered at the time of wire fusing, or the like.

In this experiment, a solid wire containing no flux was used as the type (wire type) of the welding wire 100.
In this experiment, the diameter of the welding wire 100 was φ1.2 mm.
Further, in this experiment, carbon dioxide gas (100% CO ₂ ) was used as the shielding gas.
Furthermore, in this experiment, a steel plate defined by JIS G3106 SM490A was used as the workpiece 200 to be welded.

In this experiment, the initial welding current Ia was selected from the range of 250 (A) to 500 (A).
Further, in this experiment, the steady welding current Ir was selected from the range of 350 (A) to 500 (A).
Furthermore, in this experiment, the set period T was selected from the range of 0 (mesc) to 50 (msec).
In this experiment, the rising slope Is was selected from the range of no slope to 200 (A / 100 msec) or less.

In this experiment, for each condition, welding with a weld length of 10 cm was performed 30 times each by bead-on-plate downward welding, and the number of scattered objects of φ0.72 mm or more generated in 30 times was counted, and the steady welding current Ir The rate of decrease was obtained when the conventional arc start method with the same size was used. Those with a reduction rate of 80% or more were rated as “Good”, those with a reduction rate of 30% or more were evaluated as “Good”, and the reduction rate was less than 30%. And was evaluated as “x”.

Table 18 and Table 19 below show the relationship between the eight welding conditions (No. 337 to No. 344) used in this experiment and the obtained evaluation results. In addition, No. shown in Table 18 The welding conditions of 337 to N0.340 are No. 1 shown in Table 1. 5, no. 7, no. 9, no. 11 corresponds to each. In addition, No. The reduction rate of 341 is No. 337 based on the result of No. 337 and shown in Table 19. The reduction rate of 342 is No. shown in Table 18. 338 based on the result of No. 338 and shown in Table 19. The reduction rate of 343 is No. shown in Table 18. 339 based on the result of No. 339. The reduction rate of 344 is No. shown in Table 18. Based on 340 results.

Next, the results will be described.
As apparent from Table 18 and Table 19, by setting the initial welding current Ia to be smaller than the steady welding current Ir and providing the rising slope Is in the transition from the initial welding current Ia to the steady welding current Ir, the arc It can be seen that the amount of scattered matter during the start is reduced. Further, it can be seen that when the difference between the steady welding current Ir and the initial welding current Ia is large, the reduction rate of the scattered matter becomes larger.

DESCRIPTION OF SYMBOLS 1 ... Welding system, 10 ... Welding torch, 20 ... Robot arm, 30 ... Wire feeding apparatus, 40 ... Shield gas supply apparatus, 50 ... Power supply apparatus, 51 ... Switch, 52 ... Welding current setting part, 53 ... Feeding speed Setting unit 54 ... Welding current / feed speed conversion unit 55 ... Power source unit 56 ... Power source drive unit 57 ... Welding current detection unit 58 ... Current determination unit 59 ... Energization determination unit 60 ... Robot controller 100 ... welding wire, 200 ... workpiece

Claims

The welding wire is fed toward the workpiece, and when the fed welding wire comes into contact with the workpiece, a welding current is passed between the welding wire and the workpiece, and the welding current is In the arc start control method of consumable electrode arc welding that starts welding by generating an arc,
Supplying an initial welding current as the welding current when the welding wire and the workpiece are in contact with each other;
A consumable electrode comprising a step of supplying a steady welding current larger than the initial welding current as the welding current after a predetermined set period has elapsed after the supply of the initial welding current has started. Arc start control method for type arc welding.
The initial welding current is selected from a range of 100 (A) or more and 300 (A) or less,
The arc start control method for consumable electrode arc welding according to claim 1, wherein the steady welding current is selected from a range of 350 (A) to 550 (A).
3. The arc start control method for consumable electrode arc welding according to claim 1, wherein the set period is selected from a range of 25 (msec) or more and less than 700 (msec).
2. The arc start control method for consumable electrode arc welding according to claim 1, further comprising a step of providing a rising slope between the step of supplying the initial welding current and the step of supplying the steady welding current.
5. The arc start control method for consumable electrode arc welding according to claim 4, wherein in the step of providing the rising slope, the rising slope is set to 1500 (A / 100 msec) or less.
A power supply for supplying a welding current to the workpiece via a welding wire;
When the welding wire fed toward the workpiece is in contact with the workpiece, an initial welding current is supplied as the welding current from the power supply unit, and the supply of the initial welding current is started. And a current control unit that supplies a steady welding current larger than the initial welding current as the welding current from the power supply unit after a predetermined set period has elapsed.
A control device for controlling welding work on the workpiece;
A determination unit for detecting that the initial welding current flows through the welding wire and the workpiece;
A power supply drive unit for driving the power supply unit,
The control device determines that the initial welding current has flowed through the welding wire and the work piece by the determination unit and, further, after a predetermined set time has elapsed, the power supply unit with respect to the power supply unit The welding apparatus according to claim 6, wherein a current setting signal for supplying the steady welding current is output.