JP2017094380A - Arc-welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc-welding device that can feed a welding wire at faster average feeding speed while periodically repeating forward feeding and backward feeding alternately.SOLUTION: Wire feeding means 5 includes: a first wire feeding portion 50A that imparts driving force toward both of a forward feeding direction and a backward feeding direction to a welding wire 1; a second feeding portion 50B, positioned closer to the backward feeding direction than the first wire feeding portion 50A, which imparts driving force toward the forward direction to the welding wire 1; and a curve-state amount detecting portion 553 that detects a curve-state amount of the wire according to a difference between average feeding speed of the first wire feeding portion 50A and average feeding speed of the second wire feeding portion 50B, between the first wire feeding portion 50A and the second wire feeding portion 50B. Control means changes the feeding speed of at least either one of the first wire feeding portion 50A and the second wire feeding portion 50B on the basis of a detected result by the curve state amount detecting portion 553.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an arc welding apparatus.

  In general consumable electrode arc welding, a welding wire that is a consumable electrode is fed at a constant speed, and an arc is generated between the welding wire and a base material to perform welding. In the consumable electrode type arc welding, the welding wire and the base material are often in a welding state in which a short circuit period and an arc period are alternately repeated.

  In order to further improve the welding quality, a method has been proposed in which welding is performed by periodically repeating forward feeding and reverse feeding of a welding wire (see, for example, Patent Document 1).

  In consumable electrode arc welding in which forward feeding and reverse feeding are periodically repeated, when welding is performed with a higher average welding current, it is desirable to switch between normal feeding and reverse feeding earlier. As a measure to meet such a demand, there is a configuration including two wire feeding units. One wire feeding section feeds the welding wire in the normal feeding direction at an average feeding speed. The other wire feeding unit feeds the welding wire alternately in the forward feeding direction and the backward feeding direction. However, if an unintended error occurs in the average feeding speed of these two wire feeding sections, there is a concern that the welding wire may be unreasonably loosened or stretched between these wire feeding sections.

Japanese Patent No. 52012266

  The present invention has been conceived under the circumstances described above, and is capable of feeding a welding wire at a faster average feed speed while periodically repeating forward feed and reverse feed. It is an object of the present invention to provide an arc welding apparatus.

  An arc welding apparatus provided by the present invention includes welding power output means for outputting welding power to a path including a welding wire and a material to be welded, a normal feed direction that is a direction toward the material to be welded, and the material to be welded. A wire feeding means for feeding the welding wire in a reverse feeding direction which is a separating direction; and a short circuit step in which the welding wire is short-circuited to the welding target material, and between the welding wire and the welding target material. Control means for controlling the welding power output means and the wire feeding means so as to cause a plurality of unit welding processes having an arc process in which an arc is generated, and the wire feeding means comprises: A first wire feeding unit that applies a driving force toward both the forward feeding direction and the reverse feeding direction to the welding wire; and the first wire feeding unit is positioned in the backward feeding direction relative to the first wire feeding unit. And between the 1st wire feeding part and the 2nd wire feeding part, the 1st wire between the 2nd wire feeding part which gives the driving force which goes to the above-mentioned feeding direction to the above-mentioned feeding wire A bending state amount detecting unit for detecting a bending state amount of the wire in accordance with a difference between an average feeding speed of the feeding unit and an average feeding speed of the second wire feeding unit, and the control means includes Based on the detection result of the bending state quantity detection unit, the feeding speed of at least one of the first wire feeding unit and the second wire feeding unit is changed.

  In a preferred embodiment of the present invention, the control means changes the feeding speed of the first wire feeding unit based on the detection result of the bending state quantity detection unit.

  In a preferred embodiment of the present invention, the wire feeding means is located between the first wire feeding portion and the second wire feeding portion, and the welding wire is an arch formed of one circular arc. A bending allowance space that allows the bend to be bent in a shape, and the bending state amount detection unit includes a swinging member that swings according to a bending state amount of the welding wire in the bending allowance space, A swing state amount detection sensor for detecting the swing state amount.

  In a preferred embodiment of the present invention, the control means takes the maximum normal feed speed at which the feed speed of the welding wire is the maximum speed in the normal feed direction in the arc process by the wire feed means. After setting a transition period until the maximum reverse feed speed that is the maximum speed in the reverse feed direction is set in the short-circuit step, and when the forward feed direction is positive and the reverse feed direction is negative, the average The first half region of the transition where the acceleration is negative, the second half region of the transition which is set after the first half region of the transition and the average acceleration is negative, and the absolute value of the average acceleration which is set between the first half region of the transition and the second half region of the transition. The transition period includes a transition relaxation region whose value is smaller than the absolute value of the average acceleration in any of the first half region and the second half region of the transition.

  In a preferred embodiment of the present invention, the transition relaxation region has a positive feed speed of the welding wire.

  In a preferred embodiment of the present invention, a short-circuit detection unit that detects occurrence of a short-circuit is provided, and the control unit receives the short-circuit occurrence signal from the short-circuit detection unit, and the wire feeding unit causes the transition mitigation. Transition from the area to the latter half of the transition area.

  In a preferred embodiment of the present invention, the control means makes the feeding speed constant by the wire feeding means in the transition relaxation region.

  In a preferred embodiment of the present invention, the control means sets the transition relaxation region in all the unit welding processes.

  According to the present invention, the bending state amount of the welding wire is detected by the bending state amount detection unit. Accordingly, it is possible to detect that an excessive difference has occurred between the average feeding speed of the first wire feeding unit and the average feeding speed of the second wire feeding unit. Then, the feeding state of the wire feeding means is adjusted according to the amount of bending state of the welding wire. Therefore, the welding wire can be fed at a higher average feed speed while alternately repeating the forward feed direction and the reverse feed direction.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a block diagram which shows the arc welding apparatus based on 1st Embodiment of this invention. It is a schematic block diagram which shows the arc welding apparatus of FIG. It is sectional drawing which shows the buffer part of the arc welding apparatus of FIG. It is a timing chart which shows an example of the arc welding method using the arc welding apparatus of FIG. It is a graph which shows an example of the relationship between the bending state quantity signal and feed speed correction signal in the arc welding apparatus of FIG. It is a block diagram which shows the arc welding apparatus based on 2nd Embodiment of this invention. It is a block diagram which shows the arc welding apparatus based on 3rd Embodiment of this invention. It is a timing chart which shows an example of the arc welding method using the arc welding apparatus of FIG.

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

  FIG. 1 is a block diagram showing an arc welding apparatus based on the first embodiment of the present invention. Hereinafter, each block will be described with reference to FIG. The arc welding apparatus A1 of the present embodiment includes a power supply main circuit PM, an output voltage detection circuit ED, a voltage detection circuit VD, an output voltage setting circuit ER, a voltage error amplification circuit EV, a short circuit determination circuit SD, a drive circuit DV, and a welding start circuit. ST, maximum forward feed speed setting circuit FH, maximum reverse feed speed setting circuit FL, average feed speed setting circuit FAR, first feed speed setting circuit FR, second feed speed setting circuit FR2, first feed control circuit FC, a second feed control circuit FC2 and a feed speed correction circuit VC are provided, and a welding torch 4 and a wire feed means 5 are provided. As shown in FIG. 2, the arc welding apparatus A1 may include a robot RB for moving the welding torch 4 along a desired path, for example.

  In this embodiment, the output voltage setting circuit ER, the voltage error amplification circuit EV, the short circuit determination circuit SD, the drive circuit DV, the welding start circuit ST, the maximum forward feed speed setting circuit FH, the maximum reverse feed speed setting circuit FL, the average feed The feed speed setting circuit FAR, the first feed speed setting circuit FR, the second feed speed setting circuit FR2, and the feed speed correction circuit VC constitute the control means referred to in the present invention.

  The power supply main circuit PM receives a commercial power supply (not shown) such as a three-phase 200V, performs output control by inverter control or the like according to a drive signal Dv described later, and outputs an output voltage E. Although not shown, the power supply main circuit PM is driven by a primary rectifier that rectifies commercial power, a smoothing capacitor that smoothes the rectified direct current, and the drive signal Dv that converts the smoothed direct current to high-frequency alternating current. An inverter circuit, a high-frequency transformer that steps down the high-frequency alternating current to a voltage value suitable for welding, and a secondary rectifier that rectifies the stepped-down high-frequency alternating current into direct current. The power supply main circuit PM corresponds to an example of the welding power output means referred to in the present invention.

  In addition, in the arc welding apparatus which concerns on this invention, what is necessary is just a structure provided with the component which has a function which each should fulfill | perform as a welding electric power output means and a control means. For example, components that function as welding power output means and control means may be integrated into one unit. Alternatively, a plurality of components that function as control means may be separately provided in different units.

  The reactor WL smoothes the output voltage E. The inductance value of the reactor WL is, for example, 200 μH.

  The wire feeding means 5 is a means for feeding the welding wire 1 to the welding torch 4. As shown in FIGS. 1 and 2, the wire feeding means 5 includes a first wire feeding unit 50A, a second wire feeding unit 50B, and a buffer unit 55.

  The first wire feeding unit 50A feeds the welding wire 1 in the forward feed direction and the reverse feed direction. The first wire feeding unit 50A of the present embodiment includes a first feeding motor 51A and a first feeding roller 52A. The first wire feeding unit 50A is provided in the relatively normal feeding direction. Specifically, the first feeding roller 52A is provided at a position adjacent to the welding torch 4, for example. The first feeding roller 52A is driven by the first feeding motor 51A.

  The second wire feeding unit 50B feeds the welding wire 1 only in the normal feeding direction. The second wire feeding unit 50B of the present embodiment includes a second feeding motor 51B and a second feeding roller 52B. The second wire feeding unit 50B is provided in the reverse feeding direction with respect to the first wire feeding unit 50A. Specifically, the second feeding roller 52B is provided, for example, at a position close to the wire reel 10. It has been. The wire reel 10 is obtained by winding a welding wire 1 having a predetermined length.

  The wire feeding means 5 configured as described above is constructed as a so-called push-pull type wire feeding means using the first wire feeding unit 50A and the second wire feeding unit 50B.

  The buffer unit 55 is provided between the first wire feeding unit 50A and the second wire feeding unit 50B in the feeding path of the welding wire 1, and the average feeding speed of the first wire feeding unit 50A. And the welding wire 1 is allowed to be curved according to the difference between the average feeding speed of the second wire feeding unit 50B. Before and after the buffer unit 55, for example, a first tube 6A and a second tube 6B are provided. The first tube 6 </ b> A constitutes a feeding path for the welding wire 1 between the first wire feeding unit 50 </ b> A and the buffer unit 55. The second tube 6B constitutes a feeding path of the welding wire 1 between the second wire feeding unit 50B and the buffer unit 55.

  FIG. 3 is a cross-sectional view showing the buffer portion 55 in a plane including the feeding path of the welding wire 1. As shown in the figure, the buffer unit 55 of the present embodiment includes a case 551, a bending allowable space 552, and a bending state amount detection unit 553.

  The case 551 is an external appearance of the buffer portion 55, and is a hollow structural member having an arc-shaped space. Case 551 is made of, for example, an insulating material. An internal space of the case 551 is a bending allowable space 552. The bending allowable space 552 is a space through which the welding wire 1 passes and has an arc shape. In the present embodiment, the bending allowable space 552 has an arc shape with a central angle of about 90 degrees.

  The bending state amount detection unit 553 detects the bending state amount of the welding wire 1 in the bending allowable space 552 and outputs the detection result as a signal. As long as the bending state quantity of the welding wire 1 can be detected, the specific configuration of the bending state quantity detection unit 553 is not particularly limited, and the mechanical principle, the electrical principle, the optical principle, the magnetic principle, or these It is only necessary that the bending state quantity of the welding wire 1 can be detected by combining the above principles.

  In the illustrated example, the bending state amount detection unit 553 includes a swinging member 554 and a swinging state amount detection sensor 555. The swing member 554 is connected to the swing state amount detection sensor 555 so as to be swingable, and is a member that swings according to the bending state of the welding wire 1. The swing state amount detection sensor 555 is a sensor that detects the swing amount of the swing member 554, and is, for example, a rotary encoder. A detection signal from the swing state amount detection sensor 555 is output as a bending state amount detection signal Wc from the bending state amount detection unit 553. The bending state amount detection signal Wc includes the bending state amount of the welding wire 1 as information. For example, the bending state amount detection signal Wc is generated from the path set by the occurrence of bending of the welding wire 1 (on the side where the swinging member 554 swings clockwise in FIG. 3 includes information on how much the rocking member 554 is bent counterclockwise in FIG. 3 (hereinafter referred to as a negative side).

  The output voltage setting circuit ER outputs a predetermined output voltage setting signal Er. The output voltage detection circuit ED detects the output voltage E and smoothes it, and outputs an output voltage detection signal Ed.

  The voltage error amplifier circuit EV receives the output voltage setting signal Er and the output voltage detection signal Ed. The voltage error amplification circuit EV amplifies an error between the output voltage setting signal Er and the output voltage detection signal Ed, and outputs a voltage error amplification signal Ev. The voltage error amplifier circuit EV is a circuit that controls the power supply main circuit PM at a constant voltage.

  The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The short circuit determination circuit SD receives the voltage detection signal Vd and outputs a short circuit determination signal Sd. When the value of the voltage detection signal Vd is less than the short-circuit determination value (for example, about 10 V), the short-circuit determination circuit SD determines that the short-circuit period (short-circuit process), and sets the short-circuit determination signal Sd to High level. When the value is greater than or equal to the value, it is determined that the arc period (arc process) is in progress, and the short circuit determination signal Sd is set to the Low level.

  The welding start circuit ST outputs a welding start signal St. The welding start circuit ST sets the welding start signal St to a high level when starting the welding power source. The specific configuration of the welding start circuit ST is not particularly limited. For example, the start switch of the welding torch 4, one circuit constituting the control means referred to in the present invention, or one circuit constituting the control device of the robot RB or the like corresponds. To do.

  The drive circuit DV receives the voltage error amplification signal Ev and the welding start signal St and outputs a drive signal Dv. When the welding start signal St is at a high level (welding start), the drive circuit DV outputs a drive signal Dv for performing PWM modulation control based on the voltage error amplification signal Ev. The drive signal Dv drives the inverter circuit in the power supply main circuit PM.

  The feeding speed correction circuit VC receives the bending state amount detection signal Wc and outputs a feeding speed correction signal Vc. The feeding speed correction circuit VC is a signal for adjusting the feeding state of the wire feeding means 5 based on information included in the bending state amount detection signal Wc. In the present embodiment, the feed speed correction circuit VC performs a correction amount calculation process for increasing or decelerating the feed speed of the first feed motor 51A, and then outputs the result as a feed speed correction signal Vc. To do.

  The average feed speed setting circuit FAR outputs a predetermined average feed speed setting signal Far.

  The maximum forward feed speed setting circuit FH outputs a maximum forward feed speed setting signal Fh for defining the maximum speed in the forward feed direction of the feed speed Fw. For example, the maximum normal feed speed setting signal Fh indicates a speed corresponding to the difference between the maximum speed in the normal feed direction of the feed speed Fw and the average speed by the average feed speed setting signal Far.

  The maximum reverse speed setting circuit FL outputs a maximum reverse speed setting signal Fl for defining the maximum speed in the reverse direction of the feed speed Fw. For example, the maximum reverse feed speed setting signal Fl indicates a speed corresponding to the difference between the maximum speed in the reverse feed direction of the feed speed Fw and the average speed by the average feed speed setting signal Far.

  The first feed speed setting circuit FR receives the average feed speed setting signal Far, the maximum forward feed speed setting signal Fh, the maximum reverse feed speed setting signal Fl, and the feed speed correction signal Vc, and inputs the first feed speed setting signal FR. The signal Fr is output. The drive waveform of the first feed motor 51A set by the first feed speed setting signal Fr is not particularly limited. In the present embodiment, as will be described later with reference to FIG. 2, the first feed speed setting signal Fr is a trapezoidal wave that drives the first feed motor 51A disposed on the pull side alternately forward and backward. The basic waveform command signal is used.

  The second feed speed setting circuit FR2 receives the average feed speed setting signal Far and outputs a second feed speed setting signal Fr2. The drive waveform of the second feed motor 51B set by the second feed speed setting signal Fr2 is not particularly limited. In this embodiment, as will be described later with reference to FIG. 2, the second feed speed setting signal Fr2 indicates the second feed motor 51B arranged on the push side by the average feed speed setting signal Far. The command signal is driven at a rotational speed corresponding to the average speed.

  The first feed control circuit FC receives the first feed speed setting signal Fr and outputs the first feed control signal Fc to the first feed motor 51A. The first feed control signal Fc rotates the first feed motor 51A so that the welding wire 1 can be fed at a speed instructed by the first feed speed setting signal Fr.

  The second feed control circuit FC2 receives the second feed speed setting signal Fr2 and outputs the second feed control signal Fc2 to the second feed motor 51B. The second feed control signal Fc2 rotates the second feed motor 51B so that the welding wire 1 can be fed at a speed instructed by the second feed speed setting signal Fr2.

  The feed speed Fw at which the welding wire 1 is actually fed from the welding torch 4 is the result of applying the driving force by the first feeding motor 51A and the driving force by the second feeding motor 51B to the welding wire 1. As the resulting speed.

  FIG. 4 is a timing chart showing an arc welding method using the arc welding apparatus A1. The figure (a) shows the time change of the feeding speed Fw, the figure (b) shows the time change of the welding current Iw, the figure (c) shows the time change of the welding voltage Vw, FIG. 4D shows the change over time of the short circuit determination signal Sd. Below, the arc welding method of this embodiment is demonstrated.

  The feed speed Fw shown in FIG. 5A is the first feed speed setting signal Fr output from the first feed speed setting circuit FR and the second feed speed setting circuit FR2 output from the first feed speed setting circuit FR in FIG. 2 is determined by the feed speed setting signal Fr2. In the present embodiment, the second feed speed setting signal Fr2 from the second feed speed setting circuit FR2 sets the welding wire 1 according to the average feed speed setting signal Far from the average feed speed setting circuit FAR. The second feeding motor 51B is driven so that feeding is performed at a constant speed corresponding to the average speed. On the other hand, the first feed speed setting signal Fr from the first feed speed setting circuit FR includes a maximum forward feed speed setting signal Fh, a maximum reverse feed speed setting signal Fl, an average feed speed setting signal Far, and a feed speed correction. According to the signal Vc, the first feeding motor 51A is driven so that the welding wire 1 is fed at a speed having a waveform similar to a trapezoidal wave. As a result, the feeding speed Fw has a waveform similar to a trapezoidal wave shifted to the forward feeding side by the value of the average feeding speed setting signal Far. In the present embodiment, the amplitude on the forward side by the maximum forward feed speed setting signal Fh and the amplitude on the reverse side by the maximum reverse feed speed setting signal Fl are the same magnitude.

  Here, when viewing the waveform of the feeding speed Fw with 0 as the reference line, the forward feeding period and the reverse feeding period are alternately set as shown in FIG. From time t2 to time t7 is a normal transmission period, and from time t7 to time t12 is a reverse transmission period. Further, as will be described later, time t1 to time t6 is an arc period, and time t6 to time t11 is a short circuit period. One arc period and one short-circuit period that are continuous with each other constitute one unit welding process. In the arc welding method of the present embodiment, a plurality of unit welding processes are repeatedly performed.

  The timing chart of the figure shows an arc welding method using the arc welding apparatus A1 during a so-called steady welding period. An unsteady welding period may be set before and after this steady welding period. For example, an arc start period for smoothly generating an arc may be set before the steady welding period. Alternatively, a welding end period for appropriately terminating welding may be set after the steady welding period.

  Immediately before time t1, the feeding speed Fw is the maximum reverse feeding speed Fwl, which is a short-circuited state. At time t1, the short circuit state is released and arc 3 is generated. In response to this, the welding voltage Vw rapidly increases to an arc voltage value of several tens of volts as shown in FIG. 10C, and as shown in FIG. ). As shown in FIG. 5B, the welding current Iw gradually decreases thereafter. When the short-circuit determination signal Sd is set to the Low level, the first feed speed setting circuit FR sets the normal feed maximum feed speed Fwh set by the maximum forward feed speed setting signal Fh from the maximum forward feed speed setting circuit FH. The first feed speed setting signal Fr is output so as to accelerate the feed speed Fw. In the present embodiment, the second feed speed setting circuit FR2 generates a constant driving force for feeding the welding wire 1 at the average feed speed Fwa according to an instruction of the average feed speed setting signal Far. In addition, the second feeding motor 51B is controlled.

  Next, at time t2, the feeding speed Fw becomes 0, and the normal feeding period starts. Then, at time t3, the feeding speed Fw reaches the normal feeding maximum feeding speed Fwh.

  Next, at time t6, the welding wire 1 is short-circuited to the base material 2 by feeding the welding wire 1 in the normal feeding direction, and the arc period is shifted to the short-circuit period. In response to this, the welding voltage Vw rapidly decreases to a short circuit voltage value of several V as shown in FIG. 8C, and the short circuit determination signal Sd is at a high level (short circuit) as shown in FIG. To change. As shown in FIG. 5B, the welding current Iw gradually increases thereafter. When the short circuit determination signal Sd is set to the High level at time t6, the first feed speed setting circuit FR passes through time t7 when the feed speed Fw becomes 0, and then reaches time t8 when the reverse feed maximum feed speed Fwl is reached. Until the first feed speed setting signal Fr is changed.

  When the feed speed Fw becomes the maximum reverse feed speed Fwl at time t8, the first feed speed setting circuit FR first sets the reverse feed maximum feed speed Fwl by the maximum reverse feed speed setting signal Fl. A feed speed setting signal Fr is output.

  Thereafter, while the short-circuit period started at time t6 continues, after time t8, the feeding speed Fw is maintained at the maximum reverse feeding speed Fwl. When the short-circuit period shifts to the arc period at time t11, the same control as from time t1 to time 8 is performed from time t11 to time t18. By repeating this control periodically, arc welding in which a short circuit period and an arc period occur alternately is realized.

  While the arc welding method described above is being executed, the welding wire 1 is fed while being allowed to be bent in the bending allowable space 552 of the buffer portion 55 as shown in FIG. When the average feeding speed of the first wire feeding unit 50A and the average feeding speed of the second wire feeding unit 50B are maintained at substantially the same speed, the welding wire 1 is indicated by a solid line in the figure. Routed.

  However, in this arc welding method, a push-pull type feeding mode using the first wire feeding unit 50A and the second wire feeding unit 50B based on the short circuit state and the arc state of the welding wire 1 is adopted. ing. For this reason, there is a possibility that a difference may occur between the average feeding speed of the first wire feeding unit 50A and the average feeding speed of the second wire feeding unit 50B. The bending state quantity of the welding wire 1 changes according to this difference.

  For example, when the average feed speed of the first wire feed section 50A is slower than the average feed speed of the second wire feed section 50B, the welding wire 1 is curved outward (positive side) in the figure. At this time, the swing member 554 swings clockwise in the drawing. On the other hand, when the average feed speed of the first wire feed section 50A is faster than the average feed speed of the second wire feed section 50B, the welding wire 1 is curved inward (negative side) in the drawing. At this time, the swing member 554 swings counterclockwise in the drawing. By quantitatively detecting the swinging amount of the swinging member 554 by the swinging state amount detection sensor 555, the bending state amount of the welding wire 1 is quantitatively detected. This bending state amount is output as a bending state amount detection signal Wc from the bending state amount detection unit 553 (swing state amount detection sensor 555), and is input to the feed speed correction circuit VC.

  FIG. 5 is a graph for explaining the setting of the feed speed correction signal Vc in the feed speed correction circuit VC, and shows the relationship between the bending state amount detection signal Wc and the feed speed correction signal Vc. The horizontal axis represents the bending state amount of the welding wire 1 included in the bending state amount detection signal Wc, and the vertical axis represents the first feeding to the first feeding speed setting circuit FR included in the feeding speed correction signal Vc. This is a correction amount of the set speed of the motor 51A.

  In the illustrated example, for example, an allowable bending amount Wc1 is set. Whereas the second wire feeding unit 50B feeds the welding wire 1 at a substantially constant feeding speed, the first wire feeding unit 50A feeds in the forward and reverse directions. And repeat. For this reason, the feeding speed of the first wire feeding unit 50A and the feeding speed of the second wire feeding unit 50B are instantaneously different from each other. However, when the feed speed varies between the maximum normal feed speed Fwh and the maximum reverse feed speed Fwl assumed in the assumed cycle, the bending state amount of the welding wire 1 is within a predetermined range. Fits in. When the bending state amount included in the bending state amount detection signal Wc is within this predetermined range, the feeding speed correction circuit VC does not need to correct the feeding speed. Therefore, when the bending state amount included in the bending state amount detection signal Wc is equal to or less than the allowable bending amount Wc1, which is a predetermined bending state amount, the correction amount included in the feed speed correction signal Vc is set to zero.

  If the bending state amount included in the bending state amount detection signal Wc exceeds the allowable bending amount Wc1 on the positive side, it means that the welding wire 1 is excessively bent on the positive side. Therefore, the feeding speed correction circuit VC corrects the feeding speed correction signal Vc so as to increase the speed of the first wire feeding section 50A (shift the speed in the forward feeding direction side) in order to reduce the curvature. Set the amount. On the other hand, if the bending state amount included in the bending state amount detection signal Wc exceeds the allowable bending amount Wc1 on the negative side, it means that the welding wire 1 is excessively bent on the negative side. Therefore, the feed rate correction circuit VC corrects the feed rate correction signal Vc so as to decelerate the first wire feed unit 50A (shift the speed toward the reverse feed direction) in order to reduce this curvature. Set. In the illustrated example, the magnitude of the correction amount by the feeding speed correction signal Vc is set to be larger according to the increase in the bending state amount included in the bending state amount detection signal Wc. Is not limited at all.

  The first feed speed setting circuit FR has a feed speed correction signal Vc for the feed speed determined by the maximum forward feed speed setting signal Fh, the maximum reverse feed speed setting signal Fl and the average feed speed setting signal Far. The feeding speed is corrected by the correction amount commanded by. The corrected feeding speed is output to the first feeding control circuit FC as the first feeding speed setting signal Fr, and the first feeding motor 51A is driven at the corrected feeding speed.

  An example of each numerical value in the arc welding method of this embodiment is shown below. The time for one unit welding process is usually 8 ms to 20 ms, and in this embodiment, for example, about 10 ms. The time of one short-circuit period is normally 2 ms to 10 ms, and in the present embodiment, it is about 4 ms, for example. The time of one arc period is usually 3 ms to 15 ms, and is about 6 ms, for example, in the present embodiment. The normal feed maximum feed speed Fwh is normally 30 m / min to 100 m / min, and is, for example, about 80 m / min in the present embodiment. The reverse feed maximum feed speed Fwl is normally −30 m / min to −100 m / min, and is, for example, about −70 m / min in the present embodiment. The average feed speed Fwa is normally 1 m / min to 15 m / min, and is, for example, about 10 m / min in the present embodiment. The average welding current, which is a time average value of the welding current Iw, is usually 30 A to 350 A, and is about 250 A in this embodiment, for example.

  Next, the operation of the arc welding apparatus A1 will be described.

  According to the present embodiment, the bending state amount detection unit 553 detects the bending state amount of the welding wire 1 in the buffer unit 55. Thereby, it is possible to detect that an excessive difference has occurred between the average feeding speed of the first wire feeding unit 50A and the average feeding speed of the second wire feeding unit 50B. Then, the feeding state of the wire feeding means 5 is adjusted according to the amount of bending state of the welding wire 1. Therefore, it is possible to feed the welding wire 1 at a higher average feed speed while alternately repeating the forward feed direction and the reverse feed direction. Increasing the average feed speed is preferable for performing arc welding with a larger average welding current.

  In the present embodiment, the feeding speed correction signal Vc is set based on the bending state quantity of the welding wire 1, and the feeding speed of the first wire feeding unit 50A is corrected by the feeding speed correction signal Vc. The first wire feeding unit 50A repeats forward feeding and reverse feeding, and the feeding speed is changed more frequently than the second wire feeding unit 50B. By correcting the feeding speed of the first wire feeding unit 50A, the bending state amount of the welding wire 1 can be corrected to an appropriate size more quickly.

  In this embodiment, the bending state amount of the welding wire 1 in the bending allowable space 552 is replaced with the swinging amount of the swinging member 554, and this swinging amount is detected by the swinging state amount detection sensor 555. In order to replace the bending state amount of the welding wire 1 with the swinging amount of the swinging member 554, it is only necessary to bring the swinging swinging member 554 into contact with the welding wire 1 in the bending allowable space 552. For example, when detecting the difference between the average feeding speed of the first wire feeding unit 50A and the average feeding speed of the second wire feeding unit 50B depending on the tension state of the welding wire 1, feeding of the welding wire 1 is hindered. There is a concern that the welding wire 1 may be loaded with a possible force. However, according to the present embodiment, almost no force is applied from the bending state amount detection unit 553 in the feeding direction of the welding wire 1. This is suitable for smooth feeding of the welding wire 1.

  6 to 8 show other embodiments of the present invention. In these drawings, the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment.

  FIG. 6 is a block diagram showing an arc welding apparatus based on the second embodiment of the present invention. In the arc welding apparatus A2 of the present embodiment, the feed speed correction signal Vc from the feed speed correction circuit VC is input to the second feed speed setting circuit FR2. The second feed speed setting circuit FR2 outputs a second feed speed setting signal Fr2 including the corrected feed speed based on the average feed speed setting signal Far and the feed speed correction signal Vc. Thereby, the feeding speed of the second wire feeding unit 50B is corrected, and the bending state amount of the welding wire 1 is corrected. In the case of this embodiment, the relationship between the bending state amount detection signal Wc and the feeding speed correction signal Vc shown in FIG. 5 is, for example, the value of the feeding speed correction signal Vc corresponding to the same bending state amount detection signal Wc. However, the relationship between FIG. 5 and FIG. 5 is reversed.

  Even in such an embodiment, the welding wire 1 can be fed at a higher average feeding speed while alternately repeating the forward feeding direction and the backward feeding direction.

  FIG. 7 is a block diagram showing an arc welding apparatus according to the third embodiment of the present invention. The arc welding apparatus A3 of the present embodiment includes a pre-transition half acceleration setting circuit FA1, a transition relaxation acceleration setting circuit FA2, and a transition latter half acceleration setting circuit FA3. Further, the feed speed correction signal Vc from the feed speed correction circuit VC may be input to either the first feed speed setting circuit FR or the second feed speed setting circuit FR2, and in the illustrated example, The first feed speed setting circuit FR is input.

  In this embodiment, the output voltage setting circuit ER, the voltage error amplification circuit EV, the short circuit determination circuit SD, the drive circuit DV, the welding start circuit ST, the maximum forward feed speed setting circuit FH, the maximum reverse feed speed setting circuit FL, the first half of the transition Acceleration setting circuit FA1, transition relaxation acceleration setting circuit FA2, transition latter half acceleration setting circuit FA3, average feed speed setting circuit FAR, first feed speed setting circuit FR, second feed speed setting circuit FR2, feed speed correction circuit The VC constitutes the control means referred to in the present invention.

  The pre-transition half acceleration setting circuit FA1 outputs a pre-transition half acceleration setting signal Fa1 for defining the acceleration of the feeding speed Fw in the pre-transition half region in the transition period described later. The transition relaxation acceleration setting circuit FA2 outputs a transition relaxation acceleration setting signal Fa2 for defining the acceleration of the feeding speed Fw in the transition relaxation region in the transition period described later. The transition latter half acceleration setting circuit FA3 outputs a transition latter half acceleration setting signal Fa3 for defining the acceleration of the feed speed Fw in the transition latter half region in the transition period described later.

  The first feed speed setting circuit FR includes a short circuit determination signal Sd, a maximum forward feed speed setting signal Fh, a maximum reverse feed speed setting signal Fl, a transition early acceleration setting signal Fa1, a transition relaxation acceleration setting signal Fa2, and a transition latter half acceleration setting. The signal Fa3, the average feed speed setting signal Far, and the feed speed correction signal Vc are input.

  FIG. 8 is a timing chart showing an arc welding method using the arc welding apparatus A3.

  In the same figure, from time t1 to time t4, welding control similar to the welding control in the arc welding method using the arc welding apparatus A1 described above is performed. At time t4, the first feed speed setting circuit FR starts a transition period. From time t4 to time t5, the first feed speed setting circuit FR decelerates the feed speed Fw with acceleration according to the first half-acceleration setting signal Fa1. From time t4 to time t5 corresponds to the first half region of transition referred to in the present invention. In the first half region of the transition, the acceleration of the feed speed Fw is a negative value when the forward feed direction is positive and the reverse feed direction is negative. The first feed speed setting circuit FR continues the first half of the transition until time t5 when the feed speed Fw becomes a speed that has been preliminarily set.

  Next, from time t5 to time t6, the first feed speed setting circuit FR controls the feed speed Fw with the acceleration by the transition relaxation acceleration setting signal Fa2. From time t5 to time t6 corresponds to the transition relaxation region in the present invention. The absolute value of the acceleration of the feeding speed Fw in the transition relaxation region is smaller than the absolute value of the acceleration in the first half region of the transition. In the present embodiment, according to the transition relaxation acceleration setting signal Fa2, the acceleration of the transition relaxation region is set to 0, and the feeding speed Fw is constant. In addition, the feeding speed Fw in the transition relaxation region is the normal feeding direction, and is larger than the average feeding speed Fwa in the illustrated example.

  Next, at time t6, the welding wire 1 is short-circuited to the base material 2 by feeding the welding wire 1 in the normal feeding direction, and the arc period is shifted to the short-circuit period. In response to this, the welding voltage Vw rapidly decreases to a short circuit voltage value of several V as shown in FIG. 8C, and the short circuit determination signal Sd is at a high level (short circuit) as shown in FIG. To change. As shown in FIG. 5B, the welding current Iw gradually increases thereafter. When the short circuit determination signal Sd is set to the High level at time t6, the first feed speed setting circuit FR shifts to the transition latter half region referred to in the present invention. In the second half of the transition region, the first feed speed setting circuit FR decelerates the feed speed Fw with the acceleration according to the latter half transition acceleration setting signal Fa3. In the latter half of the transition region, the acceleration of the feeding speed Fw is a negative value, and the absolute value thereof is larger than the absolute value of the acceleration in the transition relaxation region described above. The first feeding speed setting circuit FR continues the latter half of the transition until time t8 when the feeding speed Fw becomes zero and after time t8 when the feeding speed Fw becomes the maximum feeding speed Fwl.

  After time t8, until the time t11, welding control similar to the arc welding method using the arc welding apparatus A1 described above is performed. And from time t11 to time t18 including time t14 and time t15, the welding control from time t1 to time t8 described above is executed.

An example of each numerical value in the arc welding method of this embodiment is shown below. The time for one unit welding process is usually 8 ms to 20 ms, and in this embodiment, for example, about 10 ms. The time of one short-circuit period is normally 2 ms to 10 ms, and in the present embodiment, it is about 4 ms, for example. The time of one arc period is usually 3 ms to 15 ms, and is about 6 ms, for example, in the present embodiment. The normal feed maximum feed speed Fwh is normally 30 m / min to 100 m / min, and is, for example, about 80 m / min in the present embodiment. The reverse feed maximum feed speed Fwl is normally −30 m / min to −100 m / min, and is, for example, about −70 m / min in the present embodiment. The average feed speed Fwa is normally 1 m / min to 15 m / min, and is, for example, about 10 m / min in the present embodiment. The wire feeding acceleration in the first half of the transition is normally −2 × 10 ⁶ m / min ² to −15 × 10 ⁶ m / min ² . In the present embodiment, the acceleration is, for example, about −6 × 10 ⁶ m / min ² , which is an acceleration in which a speed change of 100 m / min occurs in 1 ms. The wire feeding acceleration in the second half of the transition is normally −2 × 10 ⁶ m / min ² to −15 × 10 ⁶ m / min ² . In the present embodiment, the acceleration is, for example, about −6 × 10 ⁶ m / min ² , which is an acceleration in which a speed change of 100 m / min occurs in 1 ms. The feeding speed in the transition relaxation region is normally 0 m / min to 50 m / min, and is about 30 m / min in the present embodiment, for example. Further, the wire feeding acceleration in the transition relaxation region is normally −30% to 30%, preferably −10% to 10%, of the wire feeding acceleration in the first half region or the second half region of the transition. Is about 5%, for example. Moreover, the average welding current which is the time average value of the welding current Iw is usually 30 A to 350 A, and in the present embodiment, it is about 250 A, for example.

  Also according to this embodiment, the welding wire 1 can be fed at a faster average feeding speed while alternately repeating the forward feeding direction and the reverse feeding direction. According to this embodiment, after taking the normal feed maximum feed speed Fwh in the arc period, the transition is made to the transition relaxation region through the first half transition region before the short circuit period starts. By passing through the first half region of the transition, the feeding speed Fw is decelerated from the normal feeding maximum feeding speed Fwh. However, if the acceleration by the first transition acceleration setting signal Fa1 in the first transition region is maintained, the feeding speed Fw may reach the maximum reverse feeding speed Fwl before a short circuit occurs. In the present embodiment, the transition is made to the transition relaxation region after the first half region of the transition and before the start of the short-circuit period. The acceleration by the transition relaxation acceleration setting signal Fa2 in the transition relaxation region has an absolute value smaller than the acceleration in the first half region of the transition. That is, a state where the feeding speed Fw is decelerated from the normal feeding maximum feeding speed Fwh through the first half region of the transition is maintained for a longer time. When a short circuit occurs, the first feed speed setting circuit FR shifts to the transition latter half region. That is, using the occurrence of a short circuit as a trigger, the feeding speed of the welding wire 1 is promptly turned to the maximum reverse feeding speed Fwl.

  By setting the first half region, the transition relaxation region, and the second half region of the transition, the maximum forward feed speed Fwh is set to a higher speed, and the reverse feed maximum feed speed Fwl from the time when a short circuit occurs (time t6). It is possible to shorten the time required until the time point (time t8). Increasing the maximum normal feed speed Fwh is advantageous for increasing the average feed speed Fwa. As the average feed speed Fwa increases, the average welding current, which is the average value of the welding current Iw, can be increased. Further, increasing the average feed speed Fwa means that the absolute value of the acceleration of the feed speed Fw is increased. In such a case, the load on the first feeding motor 51A and the second feeding motor 51B increases. In the present embodiment, by providing the transition relaxation region, it is possible to particularly reduce the load caused by the acceleration / deceleration of the first feeding motor 51A.

  The feeding speed Fw in the transition relaxation region is a positive value. For this reason, in the transition relaxation region, the welding wire 1 is fed in the forward feeding direction at a speed lower than the forward feed maximum feeding speed Fwh. Therefore, it can be avoided that the welding wire 1 is unfairly separated from the base material 2 until the short circuit occurs (time t6), and the short circuit is not appropriately generated.

  In the transition relaxation region, by setting the acceleration by the transition relaxation acceleration setting signal Fa2 to 0, the feeding speed Fw is maintained at a constant speed. At the time of occurrence of a short circuit, a significant change occurs in the welding voltage Vw and the welding current Iw. Such a configuration in which a relatively unstable state is reached at a constant feed rate Fw is advantageous in causing a short circuit in a more stable state and at an intended timing.

  The arc welding apparatus according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the arc welding apparatus according to the present invention can be varied in design in various ways.

A1 to A3: Arc welding apparatus 1: Welding wire 2: Base material 3: Arc 4: Welding torch 5: Wire feeding means 6A: First tube 6B: Second tube 10: Wire reel 50A: First wire feeding unit 50B: 2nd wire feed part 51A: 1st feed motor 51B: 2nd feed motor 52A: 1st feed roller 52B: 2nd feed roller 55: Buffer part 551: Case 552: Curve tolerance space 553: Bending state quantity detection unit 554: swinging member 555: swinging state quantity detection sensor DV: drive circuit Dv: drive signal E: output voltage ED: output voltage detection circuit ER: output voltage setting circuit EV: voltage error amplification circuit Ed: Output voltage detection signal Er: Output voltage setting signal Ev: Voltage error amplification signal FA1: Transition pre-half acceleration setting circuit FA2: Transition relaxation acceleration setting circuit FA3: After transition Acceleration setting circuit FAR: Average feed speed setting circuit FC: First feed control circuit FC2: Second feed control circuit FH: Maximum forward feed speed setting circuit FL: Maximum reverse feed speed setting circuit FR: First feed speed Setting circuit FR2: Second feed speed setting circuit Fa1: Pre-transition half acceleration setting signal Fa2: Transition relaxation acceleration setting signal Fa3: Late transition acceleration setting signal Far: Average feed speed setting signal Fc: First feed control signal Fc2: Second feed control signal Fh: Maximum forward feed speed setting signal Fl: Maximum reverse feed speed setup signal Fr: First feed speed setup signal Fr2: Second feed speed setup signal Fw: Feed speed Fwa: Average feed Speed Fwh: Maximum forward feed speed Fwl: Maximum reverse feed speed Iw: Welding current PM: Power supply main circuit RB: Robot SD: Short circuit determination circuit ST: Welding start circuit Sd: Short circuit determination signal St : Welding start signal VC: Feeding speed correction circuit VD: Voltage detection circuit Vc: Feeding speed correction signal Vd: Voltage detection signal Vw: Welding voltage WL: Reactor Wc: Bending state quantity detection signal Wc1: Allowable bending quantity

Claims (3)

Welding power output means for outputting welding power to a path including a welding wire and a material to be welded;
Wire feeding means for feeding the welding wire in a forward feeding direction that is a direction toward the welding target material and a reverse feeding direction that is a direction away from the welding target material;
Each of the plurality of unit welding processes includes a short-circuit process in which the welding wire is short-circuited with the welding target material and an arc process in which an arc is generated between the welding wire and the welding target material. Control means for controlling the welding power output means and the wire feeding means,
The wire feeding means includes a first wire feeding unit that applies a driving force toward both the forward feeding direction and the reverse feeding direction to the welding wire, and the first wire feeding unit is more than the first wire feeding unit. A second wire feeding unit that is positioned in the reverse feeding direction and applies a driving force toward the welding direction to the welding wire; and the first wire feeding unit and the second wire feeding unit. A bending state amount detection unit for detecting a bending state amount of the welding wire according to a difference between an average feeding speed of the first wire feeding unit and an average feeding speed of the second wire feeding unit, Including
The said control means is an arc welding apparatus which changes the feeding speed of at least any one of a said 1st wire feeding part and a said 2nd wire feeding part based on the detection result of the said bending state quantity detection part.   The arc welding apparatus according to claim 1, wherein the control unit changes a feeding speed of the first wire feeding unit based on a detection result of the bending state quantity detection unit. The wire feeding means is located between the first wire feeding portion and the second wire feeding portion, and allows the bending of the welding wire to be curved in an arch shape composed of one arc. Including space,
The bending state amount detection unit includes a swinging member that swings according to a bending state amount of the welding wire in the bending allowable space, and a swinging state amount detection sensor that detects a swinging state amount of the swinging member. The arc welding apparatus according to claim 1, comprising:

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