JP5160961B2 - Feed control method for consumable electrode arc welding - Google Patents

Description

  The present invention relates to a feed control method for consumable electrode arc welding that can stabilize a welding state regardless of which feed motor is used from among a plurality of feed motors having different transient responsiveness.

  FIG. 6 is a general configuration diagram of a consumable electrode arc welding apparatus using a robot. Hereinafter, each component will be described with reference to FIG.

The teach pendant TP is connected to the robot controller RC and teaches the operation trajectory of the robot RM and sets welding conditions. The robot controller RC outputs an operation control signal Mc for controlling the operation of the robot RM to a plurality of servo motors (not shown) provided in the robot RM, and outputs a welding condition signal Wc to the welding power source PS. . The welding condition signal Wc includes at least a welding start signal St, a feed speed setting signal Fr, and a welding voltage setting signal Vr. A feed motor WM and a welding torch 4 are mounted on the robot RM.

  The welding power source PS receives the above welding condition signal Wc and outputs a welding voltage Vw and a welding current Iw for generating the arc 3, and a feed control signal Fc for controlling the feed motor WM. Is output. The welding wire 1 is fed through the welding torch 4 at the feeding speed Fw (cm / min) by the feeding motor WM, and an arc 3 is generated between the welding wire 1 and the base material 2. In the following description, when it is described as a feeding motor, it is used to include the entire feeding mechanism such as the motor itself, a speed reducer, and a feeding roll.

  FIG. 7 is a timing chart of sequence control from the start to the end of welding when arc welding is performed using the above-described welding apparatus. (A) shows the welding start signal St, (B) shows the feeding speed Fw of the welding wire, (C) shows the welding current Iw, and (D) shows the welding voltage Vw. Indicates. Hereinafter, a description will be given with reference to FIG.

[When welding starts]
At time t1, when the welding start signal St is at a high level (welding start) as shown in FIG. 9A, the welding wire is slowed down at a value close to the minimum speed as shown in FIG. Feeding at the feeding speed Fi is started. At the same time, since the output of the welding power source is also started, as shown in FIG. 4D, the welding voltage Vw that is the maximum no-load voltage value is applied between the welding wire and the base material. In this state, since the welding wire and the base material are separated from each other and are in a no-load state, the welding current Iw is not energized as shown in FIG.

  When the tip of the welding wire reaches the base material by the slow-down feeding at time t2, the welding current Iw has a hot start current value Ih larger than the steady welding current value as shown in FIG. Energize. This hot start current Ih is energized during a predetermined hot start period Th until time t3. At time t2, the welding voltage Vw becomes a hot start voltage value larger than the steady welding voltage value Vt, as shown in FIG. Furthermore, at time t2, as shown in FIG. 5B, the feeding speed Fw starts increasing with a slope due to a transient response, and converges to the steady feeding speed Ft at time t4. Although this slope increases in a curvilinear manner, it is described as a straight line in order to simplify the description. The rate of change of the slope is a value determined by the transient response of the feed motor WM. Therefore, the rate of change of the slope varies greatly depending on the type of the feed motor WM. For example, a direct current motor generally used as a feed motor has a low transient response, so the rate of change is small. A recently used servo motor has a fast transient response, so the rate of change is low. Becomes bigger.

  At time t3, as shown in FIG. 3C, the welding current Iw is energized by the steady welding current value It since the hot start period Th ends. This steady welding current value It is a value determined by the steady feeding speed Ft. In response to this, as shown in FIG. 4D, the welding voltage Vw changes from the hot start voltage value to the steady welding voltage value Vt. This value is determined by the welding voltage setting signal Vr included in the welding condition signal Wc described above with reference to FIG.

  At time t4, as shown in FIG. 5B, when the transient response of the feeding speed Fw is completed, the steady feeding speed Ft is obtained. The steady feeding speed Ft is a value determined by the feeding speed setting signal Fr included in the welding condition signal Wc described above with reference to FIG. The period from time t2 to t4 will be referred to as a transition period Tk. The reason why the hot start current Ih is energized is that when the welding wire tip contacts the base material, the hot start current Ih having a large current value is energized to rapidly melt the welding wire tip and instantaneously generate an arc. It is for generating. In order to smoothly shift from the instantaneous arc generation to the steady arc, it is important that the value of the hot start current Ih and the value of the hot start period Th are appropriate. In particular, in order to smoothly shift from a short arc length of an instantaneous arc to an appropriate arc length of a steady arc, a balance between the welding wire melting speed and the feeding speed is important. The melting speed is determined by the hot start current value Ih, and the feeding speed is determined by the feeding speed Fw during the transition period Tk. Therefore, the length of time between the hot start period Th and the transition period Tk is important. The hot start period Th needs to be set to an appropriate value shorter than the transient period Tk. For this reason, when the transition period Tk changes, the appropriate value of the hot start period Th also changes.

[Normal welding period]
The period from time t4 to t5 is a steady welding period. During this period, as shown in FIG. 5B, the feed speed Fw becomes the steady feed speed Ft, and the weld current Iw becomes the steady welding current value It as shown in FIG. As shown in (D), the welding voltage Vw becomes a steady welding voltage value Vt, and stable welding is performed.

[At the end of welding]
At time t5, when the welding start signal St becomes low level (welding end) as shown in FIG. 9A, the feed motor WM is controlled to stop as shown in FIG. The feed speed Fw decelerates with a slope during the transient period Tk (time t5 to t6) due to inertia. At time t5, as shown in FIG. 4D, application of the welding voltage Vw is delayed until time t8. This period from time t5 to t8 is called an anti-stick period Ta. At time t5, as shown in FIG. 5C, the welding current Iw changes to the anti-stick current value Ia because the feeding speed Fw is decelerated. At time t5, the welding voltage Vw changes to an appropriate anti-stick voltage value Va as shown in FIG. This anti-stick voltage value Va is set so as to match the rate of change of deceleration in the transition period Tk of the feeding speed. If this value is too large, the arc length during the transition period Tk becomes long and welding to the power feed tip occurs. On the other hand, if this value is too small, the arc length becomes short, and many spatters are generated due to a large number of short circuits with the base material. Therefore, in order to set the arc length to an appropriate value, it is necessary to set the antistick voltage value Va to an appropriate value.

  At time t6, as shown in FIG. 5B, the transition period Tk of the feeding speed Fw ends and feeding stops. At this time, as shown in FIG. 3C, the energization continues with the welding current Iw being the anti-stick current value Ia. For this reason, the arc length gradually increases during the period from time t6 to t7, and the arc cannot be maintained at time t7, and the arc disappears. During the period from time t6 to time t7, as shown in FIG. 4D, the welding voltage Vw gradually increases as the arc length increases, and reaches the maximum no-load voltage value at time t7. It is important that the distance between the tip of the welding wire and the base material when the arc disappears at time t7 is an appropriate value. If this distance is longer than the appropriate value, the spherical particle diameter formed at the tip of the welding wire becomes large, and the next arc start property is deteriorated. On the other hand, if the distance is short, the particle diameter at the tip of the welding wire is small, so that the slag of the insulator is likely to adhere, and the next arc start property is also deteriorated.

  At time t7, the welding current Iw ends energization as shown in FIG. On the other hand, as shown in FIG. 4D, the welding voltage Vw becomes a no-load voltage value, and the application of the no-load voltage continues until time t8 when the antistick period Ta ends. If the anti-stick period Ta is set shorter than time 7, the tip of the welding wire has an appropriate distance and welding cannot be completed, and welding (stick) to the base material occurs. . On the contrary, if the anti-stick period Ta is long, the useless time becomes long and the tact time becomes long.

  As described above, the following points are important in order to improve the welding quality at the start and end of welding. That is, at the start of welding, it is necessary to set the hot start current value Ih and the hot start period Th to appropriate values according to the transition period Tk when the feed speed is changed determined by the feed motor WM. Similarly, at the end of welding, it is necessary to set the anti-stick voltage value Va and the anti-stick period Ta to appropriate values according to the transition period Tk when the feed speed of the feed motor WM changes. The above-described sequence control at the start and end of welding is merely an example, and various sequence controls are used. However, also in these sequence controls, setting of control parameters according to the transient response of the feed motor WM is important for obtaining good welding quality.

  By the way, Patent Document 1 discloses controlling the slope at the time of stopping feeding by controlling the current of the feeding motor at the end of welding. In this method, when the type of the feed motor changes, the motor drive circuit also changes. Therefore, a special motor drive circuit is required for each feed motor in order to employ the technique of Patent Document 1.

JP 2002-283052 A

  In the welding apparatus described above with reference to FIG. 6, many types of feed motors WM have recently been used. For example, high welding welding may be performed using a feed motor having a maximum feed speed that is higher than that of a feed motor using a conventional DC motor. Further, in order to improve the feedability of the welding wire, a push / pull feed motor may be used. In addition, by mounting a feed motor using a small servo motor on the wrist shaft of the robot RM, it is possible to precisely control the forward and backward feed of the welding wire. In this way, various feed motors WM are being used.

  If the type of the feed motor WM is different, the transient response when the feed speed is changed is different, and the length of the transient period Tk in FIG. 7 described above is also different. For this reason, when the type of the feed motor WM is replaced with a different type, the control parameters such as the hot start current value Ih, the hot start period Th, the antistick voltage value Va, and the antistick period Ta are left as they are. The welding quality at the start and end of welding deteriorates. In order to solve this, the control parameter may be changed to an appropriate value for each type of the feeding motor WM. However, since there are many types of the feed motors WM, selecting an appropriate value for the control parameter for each feed motor WM requires an enormous experiment. Also, if the welding power source models are different, the sequence control at the start and end of welding is different, so the number of combinations of the welding power source and the feed motor WM is very large, and each of these combinations. In order to select an appropriate value for the control parameter, an enormous amount of experimentation is required.

  Therefore, in the present invention, a feed control method for consumable electrode arc welding that can obtain a good welding quality at the start and end of welding even if the type of feed motor is different, without performing an enormous experiment. The purpose is to provide.

In order to solve the above-described problem, the first invention selects one of a plurality of feed motors having different transient responsiveness , feeds the welding wire by the selected feed motor, In the feed control method of consumable electrode arc welding in which an arc is generated between the welding wire and the base material to perform welding,
Controlling the selected feed motor to change with a slope of a predetermined reference change rate when the feed speed is accelerated and decelerated during welding;
The reference change rate is set to the same value as the change rate of the feed speed in the feed motor having the slowest transient response among the plurality of feed motors or a value smaller than the change rate of the feed speed.
This is a feed control method for consumable electrode arc welding.

When performing the feed control method of the consumable electrode arc welding described in the first invention using the robot welding apparatus provided with the teach pendant, the second invention sets the reference change rate by the teach pendant.
This is a feed control method for consumable electrode arc welding.

  According to the present invention, when the feed speed changes during welding, the feed motor is controlled so as to change with a slope having a predetermined reference change rate, regardless of the type of the feed motor. Good welding quality can be obtained without changing control parameters in sequence control at the start and end of welding. Furthermore, since the control parameter may remain the same value regardless of the feed motor, there is no need for an enormous experiment for optimizing the control parameter for each type of feed motor.

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

[Embodiment 1]
Hereinafter, the case where there are three types of feed motors, the first to third feed motors, will be described. Among these three, the first feed motor has the fastest transient response when the feed speed is changed, the second feed motor is in the middle, and the third feed is the slowest. Suppose that it is a feed motor. FIG. 1 is a diagram showing the transient response of these three feeding motors. FIG. 4A shows the feed speed setting signal Fr, FIG. 2B shows the feed speed AFw of the first feed motor, and FIG. 4C shows the feed speed BFw of the second feed motor. FIG. 4D shows the feed speed CFw of the third feed motor. This figure shows the transient responsiveness of the three feeding motors when the feeding speed setting signal Fr changes stepwise at time t1. Hereinafter, a description will be given with reference to FIG.

  When the feed speed setting signal Fr rises stepwise from Fr1 to Fr2 at time t1, as shown in FIG. 5A, the feed of the first feed motor is performed as shown in FIG. The speed AFw increases from Fw1 with a slope and converges to Fw2 at time t2. Although this rising characteristic originally rises in a curved line shape, it is simplified and represented as a straight line here. Therefore, this slope indicates the time constant in the transient response. Also, as shown in FIG. 10C, the feed speed BFw of the second feed motor converges to Fw2 at time t3, and as shown in FIG. 10D, the feed speed of the third feed motor. CFw converges to Fw2 at time t4. As described above, the transition period is different for each feeding motor.

  FIG. 2 is a diagram illustrating the principle of the feed control method according to the first embodiment of the present invention. The figure corresponds to FIG. 1 described above, and the signals in FIGS. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 5A, when the value of the feed speed setting signal Fr is changed from Fr1 to Fr2 at time t1, it is generated so as to change with a slope, and converges to Fr2 at time t4. Like that. The rate of change (slope) in the slope is set to the same value as the rate of change of the third feed motor shown in FIG. That is, the rate of change of the feed speed setting signal Fr is set to the rate of change of the third feed motor having the constant transient response. In this way, the first feed motor converges to Fw2 at time t4 as shown in FIG. 5B, and the second feed motor also changes to Fw2 at time t4 as shown in FIG. The third feeding motor converges to Fw2 at time t4 as shown in FIG. That is, the transient response of all the feeding motors can be made apparently the same. For this reason, even if the types of feed motors are different, it is not necessary to change control parameters in sequence control at the start of welding and at the end of welding.

  FIG. 3 is a block diagram of a welding power source PS for carrying out the feed control method for consumable electrode arc welding according to Embodiment 1 of the present invention. The overall structure of the welding apparatus is the same as that shown in FIG. Hereinafter, each block will be described with reference to FIG.

  The power supply main circuit PM receives a commercial power supply (not shown) such as three-phase 200 V, performs output control such as inverter control in accordance with a drive signal Dv described later, and generates a welding voltage Vw and a welding current for generating the arc 3. Iw is output. Although not shown, the power supply main circuit PM has a primary rectifier that rectifies commercial power, a capacitor that smoothes the rectified direct current, an inverter circuit that converts the smoothed direct current into high frequency alternating current according to the drive signal Dv, and high frequency alternating current It consists of a high-frequency transformer that steps down to a voltage value suitable for arc welding, a secondary rectifier that rectifies the stepped-down high-frequency alternating current, and a reactor that smoothes the rectified direct current.

  The welding wire 1 is fed through the welding torch 4 by a feeding roll 5 coupled to a feeding motor WM, and an arc 3 is generated between the base metal 2 and the welding wire 1.

  The voltage detection circuit VD detects the welding voltage Vw and outputs a voltage detection signal Vd. The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The current energization determination circuit CD receives the current detection signal Id and, when this value is equal to or greater than a predetermined current determination value, determines that the welding current Iw is energized and becomes a high level current energization determination signal. Cd is output.

  The interface circuit IF receives a welding condition signal Wc from the robot controller RC and outputs a welding start signal St, a welding voltage setting signal Vr, and a feed speed setting signal Fr included in this signal. The start-up circuit ON receives this welding start signal St and outputs an start-up signal On with an off-delay for a predetermined anti-stick period, and also outputs an anti-stick period signal Ta that is at a high level during the anti-stick period. To do.

  The hot start current setting circuit IHR outputs a predetermined hot start current setting signal Ihr. The current error amplification circuit EI amplifies an error between the hot start current setting signal Ihr and the current detection signal Id, and outputs a current error amplification signal Ei. The anti-stick voltage setting circuit VAR outputs a predetermined anti-stick voltage setting signal Var. The voltage control setting circuit VCR receives the welding voltage setting signal Vr, the anti-stick voltage setting signal Var and the anti-stick period signal Ta, and when the anti-stick period signal Ta is at the low level, the welding voltage setting signal Vr. Is output as the voltage control setting signal Vcr, and when the level is High, the anti-stick voltage setting signal Var is output as the voltage control setting signal Vcr. The voltage error amplification circuit EV amplifies an error between the voltage control setting signal Vcr and the voltage detection signal Vd, and outputs a voltage error amplification signal Ev.

  The hot start period timer circuit TH receives the current energization determination signal Cd as described above, and outputs a hot start period signal Th that becomes a High level only for a predetermined hot start period after the signal changes to a High level. The external characteristic switching circuit SW receives the current error amplification signal Ei, the voltage error amplification signal Ev and the hot start period signal Th, and inputs the current error amplification signal when the hot start period signal Th is at a high level. Ei is output as an error amplification signal Ea, and when the level is Low, the voltage error amplification signal Ev is output as an error amplification signal Ea. The drive circuit DV receives the error amplification signal Ea and the activation signal On, and when the activation signal On is at a high level, performs a pulse width modulation control based on the error amplification signal Ea and outputs the drive signal Dv. . As a result, when the welding start signal St becomes high level, the constant voltage characteristic is obtained and the output of the welding voltage Vw is started. When the welding current Iw starts energization, constant current characteristics are obtained, and the hot start current Ih is energized during the hot start period Th. When this period ends, constant voltage characteristics are obtained, and the welding voltage Vw becomes a value determined by the welding voltage setting signal Vr. When the welding start signal St changes to the Low level, the welding voltage Vw becomes a value determined by the antistick voltage setting signal Var from this time point to the antistick period.

The feed rate control setting circuit FCR receives the welding start signal St, the current application determination signal Cd, and the feed rate setting signal Fr as inputs, and when the welding start signal St becomes a high level, a slow-down is set in advance. The feed speed setting value becomes a value determined by the feed speed setting signal Fr when the current energization determination signal Cd becomes High level, and becomes 0 when the welding start signal St becomes Low level. Fcr is output. The reference change rate setting circuit SR sets a change rate that is substantially the same value as that of the plurality of feed motors that have a low transient response when the feed speed changes, and sets a reference change rate setting signal. Sr is output. The feed speed slope circuit FSR receives the feed speed control setting signal Fcr and the change rate setting signal Sr as input, and is determined by the change rate setting signal Sr when the feed speed control setting signal Fcr changes. A feed speed slope signal Fsr is output so as to change with a slope at the rate of change. The feed control circuit FC inputs the feed speed slope signal Fsr and outputs a feed control signal Fc for feeding the welding wire 1 at a feed speed corresponding to this value to the feed motor WM.

  FIG. 4 is a timing chart of each signal in the welding power source PS described above with reference to FIG. 3 for describing the feed control method for consumable electrode arc welding according to Embodiment 1 of the present invention. (A) shows the welding start signal St, (B) shows the feeding speed Fw, (C) shows the welding current Iw, (D) shows the welding voltage Vw, FIG. 4E shows the start signal On, FIG. 4F shows the feed speed control setting signal Fcr, and FIG. 4G shows the feed speed slope signal Fsr. In the figure, the feed motor WM may be any of the first to third feed motors. Further, this figure corresponds to FIG. 7 described above, and basically the timing charts of the respective signals in the same figure (A) to (D) are the same. Therefore, the following description will be focused on the points different from FIG.

[When welding starts]
At time t1, as shown in FIG. 6A, when the welding start signal St becomes high level, the start signal On becomes high level as shown in FIG. As shown, the output of the welding voltage Vw is started and becomes a no-load voltage. At the same time, as shown in FIG. 5F, the feed speed control setting signal Fcr becomes a slow-down feed speed setting value. In response to this, as shown in FIG. 5G, the feed speed slope signal Fsr rises at a predetermined reference change rate and becomes a slow-down feed speed set value. At this time, since the slow-down feed speed setting value is the minimum speed, the slope period is short. As shown in FIG. 5B, the feeding speed Fw becomes the slow-down feeding speed Fi.

  When the tip of the welding wire reaches the base material at time t2, the welding current Iw is energized to a hot start current value Ih as shown in FIG. This hot start current Ih is energized for a predetermined hot start period Th at times t2 to t3. At the same time, the feed speed control setting signal Fcr becomes a steady feed speed setting value determined by the feed speed setting signal Fr as shown in FIG. 5F, and the feed speed is set as shown in FIG. The slope signal Fsr rises at the reference change rate and converges to the steady feed speed setting value at time t4. In response to this, as shown in FIG. 5B, the feeding speed Fw rises with a slope of the reference change rate and converges to the steady feeding speed Ft at time t4. Thus, since the hot start period Th at the times t2 to t3 and the transition period Tk at the times t2 to t4 are in an appropriate relationship, good arc start performance can be obtained. The proper relationship between these two values can be maintained even if the type of the feed motor changes.

[Normal welding period]
The period from time t4 to t5 is a steady welding period. That is, as shown in FIG. 5B, the feeding speed Fw becomes a steady feeding speed Ft, and as shown in FIG. 5C, the welding current Iw becomes a steady welding current value It. As shown in D), the welding voltage Vw becomes the steady welding voltage value Vt.

[At the end of welding]
At time t5, when the welding start signal St changes to a low level as shown in FIG. 5A, the activation signal On is set to a predetermined anti-stick period Ta until time t8 as shown in FIG. Delayed to a low level. Therefore, the output of the welding power source continues until time t8. As shown in FIG. 4D, the welding voltage Vw becomes a predetermined anti-stick voltage value Va. Further, as shown in FIG. 5F, the feed speed control setting signal Fcr becomes zero. Then, as shown in FIG. 5G, the feed speed slope signal Fsr falls with a slope of the reference change rate and becomes 0 at time t6. As a result, as shown in FIG. 5B, the feeding speed Fw decreases from the steady feeding speed Ft at the reference change rate and becomes zero at time t6. Further, as shown in FIG. 5C, the welding current Iw changes from the steady welding current value It to the antistick current value Ia.

  Since the feeding of the welding wire is stopped at time t6, the arc length gradually increases, and the arc disappears at time t7. During the period from time t6 to time t7, as shown in FIG. 4D, the welding voltage Vw increases in proportion to the arc length, and reaches a no-load voltage value at time t7. The application of this no-load voltage continues until time t8. Further, as shown in FIG. 5C, the welding current Iw is energized until time t7. Thus, since the relationship between the transition period Tk from time t5 to t6 and the antistick period Ta from time t5 to t8 can be made appropriate, the welding quality at the end of welding is improved. Even if the feed motor type changes, the relationship between the two values is maintained properly.

[Embodiment 2]
FIG. 5 is a diagram illustrating the principle of the feed control method according to the second embodiment of the present invention. FIG. 4A shows the feed speed setting signal Fr, FIG. 2B shows the feed speed AFw of the first feed motor, and FIG. 4C shows the feed speed BFw of the second feed motor. FIG. 4D shows the feed speed CFw of the third feed motor. This figure corresponds to FIG. 2 described above. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 2A, when the value of the feed speed setting signal Fr is changed from Fr1 to Fr2 at time t1, it is generated so as to change with a slope, and at time t5 (see FIG. 2). It converges to Fr2 at a time later than time t4). The rate of change (slope) in the slope is set to a predetermined value that is smaller than the rate of change of the third feed motor shown in FIG. That is, the rate of change of the feed rate setting signal Fr is set to a value smaller than the rate of change of the third feed motor having the constant transient response. As a result, the first feed motor converges to Fw2 at time t5 as shown in FIG. 5B, and the second feed motor also changes to Fw2 at time t5 as shown in FIG. As shown in FIG. 4D, the third feeding motor converges to Fw2 at time t5. That is, the transient response of all the feeding motors can be made apparently the same. For this reason, even if the types of feed motors are different, it is not necessary to change control parameters in sequence control at the start of welding and at the end of welding.

  A welding apparatus for carrying out the second embodiment described above is the same as that of the first embodiment. However, in FIG. 3 described above, the value of the reference change rate setting signal Sr output by the reference change rate setting circuit SR has the most transient response when the feed speed changes among the plurality of feed motors used. It is set to a value smaller than the rate of change of the slow one. The timing chart of Embodiment 2 is the same as FIG. 4 mentioned above.

  In the first and second embodiments described above, the reference change rate setting signal Sr shown in FIG. 3 may be set from the teach pendant TP connected to the robot controller RC. In FIG. 3, a feed speed control setting circuit FCR, a feed speed slope circuit FSR, and a reference change rate setting circuit SR may be provided in the robot controller RC. In this case, the feeding speed slope signal Fsr is input to the welding power source PS. The above-described sequence control at the start and end of welding is an example, and the first and second embodiments can be applied to other sequence controls.

  According to the first and second embodiments, when the feed speed changes during welding, the feed motor is controlled so as to change with a slope having a predetermined reference change rate. Regardless of the type, good welding quality can be obtained without changing control parameters in sequence control at the start and end of welding. Furthermore, since the control parameter may remain the same value regardless of the feed motor, there is no need for an enormous experiment for optimizing the control parameter for each type of feed motor.

It is a figure which shows the transient characteristic which three types of feed motors which concern on Embodiment 1 of this invention have. It is a figure which shows the principle of the feed control method which concerns on Embodiment 1 of this invention. It is a block diagram of the welding power supply for implementing the feed control method which concerns on Embodiment 1 of this invention. It is a timing chart of each signal in the welding power supply of FIG. It is a figure which shows the principle of the feed control method which concerns on Embodiment 2 of this invention. It is a block diagram of the consumable electrode arc welding apparatus using the welding robot in a prior art. It is a timing chart which shows the feed control method in a prior art.

Explanation of symbols

1 Welding wire
2 Base material
3 arc
4 Welding torch
5 Feeding roll
AFw 1st feed motor feed speed
BFw Feeding speed of second feeding motor
CD Current conduction discrimination circuit
Cd Current conduction determination signal
CFw Third feed motor feed speed
DV drive circuit
Dv drive signal
Ea Error amplification signal
EI current error amplifier circuit
Ei Current error amplification signal
EV voltage error amplifier circuit
Ev Voltage error amplification signal
FC feed control circuit
Fc feed control signal
FCR feed speed control setting circuit
Fcr Feeding speed control setting signal
Fi slow-down feeding speed
Fr Feeding speed setting signal
FSR feeding speed slope circuit
Fsr Feed speed slope signal
Ft steady feeding speed
Fw Feeding speed
Ia Anti-stick current value ID Current detection circuit
Id Current detection signal
IF interface circuit
Ih Hot start current
IHR hot start current setting circuit
Ihr Hot start current setting signal
It steady welding current value
Iw welding current
Mc operation control signal
ON start circuit
On activation signal
PM power supply main circuit PS welding power supply
RC robot controller
RM robot
SR reference change rate setting circuit
Sr Reference change rate setting signal
St welding start signal
SW External characteristic switching circuit
Ta Anti-stick period (signal)
TH Hot start period timer circuit
Th Hot start period (signal)
Tk transition period
TP teach pendant
Va Anti-stick voltage value
VAR anti-stick voltage setting circuit
Var Anti-stick voltage setting signal
VCR voltage control setting circuit
Vcr Voltage control setting signal
VD voltage detection circuit
Vd Voltage detection signal
Vr Welding voltage setting signal
Vt steady welding voltage value
Vw welding voltage
Wc Welding condition signal
WM feed motor

Claims (2)

One of a plurality of feed motors having different transient responsiveness is selected, the welding wire is fed by the selected feed motor, and an arc is generated between the welding wire and the base material to perform welding. In the feed control method for consumable electrode arc welding,
Controlling the selected feed motor to change with a slope of a predetermined reference change rate when the feed speed is accelerated and decelerated during welding;
The reference change rate is set to the same value as the change rate of the feed speed in the feed motor having the slowest transient response among the plurality of feed motors or a value smaller than the change rate of the feed speed.
A feed control method for consumable electrode arc welding. When performing the feed control method of consumable electrode arc welding according to claim 1 using a robot welding apparatus equipped with a teach pendant, the reference change rate is set by the teach pendant.
A feed control method for consumable electrode arc welding.

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