JPH0985441A - Automatic arc welding controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically control welding quality such as strength and appearance against the disturbance during welding caused by teaching accuracy or the like. SOLUTION: The substitution characteristics for welding conditions concerning welding quality are determined by sampling or arithmetic operation (S5 ); on the basis of the operation, the welding conditions in electric voltage and current are automatically controlled in real time (S8 , S9 , S7 ). For example, in the case of securing a leg and penetration depth, computing is done on a theoretical wire feeding speed MRC required to secure the leg, and a command parameter is increased/decreased for the welding current, which is also a parameter for the wire feeding speed so that the detected wire feeding speed MRa may be made equal to the MRC. Then, in the case where such welding current is dropped so as not to secure the normal penetration depth, an estimated equation is used for the penetration depth using voltage, current and speed as variables, calculating the present penetration depth and, if it is not more than the normal penetration depth, the command parameter is increased in order to increase the welding current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic controller for consumable electrode type arc welding using a shield gas.

[0002]

2. Description of the Related Art In automatic arc welding, even if optimum welding conditions (current, voltage, speed) are set, in actual welding,
Conditions change due to many on-site disturbances, leading to adverse effects such as deterioration of welding strength and bead appearance. Therefore, it is important to understand the disturbance in automatic welding and to know how it affects the welding quality and manage it.

FIG. 8 is a summary of disturbances that occur during actual welding. From this figure, the disturbance is caused by the variation in the distance between the tip base materials (distance between the tip of the tip in the torch and the base material) due to poor teaching accuracy, deformation of the base material, and bending of the wire and flexible conduit tube. It is divided into fluctuations in wire feeding resistance. The former variation in the distance between the tip base materials causes the welding current to increase / decrease in inverse proportion as shown in FIG. 9, and as a result, the voltage-current balance is lost. If the welding current increases or decreases, the welding strength is greatly affected, leading to fluctuations in leg length and penetration depth, and if the voltage balance with respect to the current is lost, the bead appearance is greatly affected. , Weld holes such as blow holes tend to occur. The latter variation of the wire feeding resistance causes a knocking phenomenon of the wire and slipping of the feeding roller, which may disturb the wire feeding speed and lead to fluctuations in the leg length and frequent spattering.

[0004]

On the other hand, in the conventional quality control at the time of welding, as shown in FIG. 10, the current and voltage of the welding power source are measured, and if it is out of the allowable range, the welding power source is switched on. The command value of is corrected, the welding is stopped and the setting is performed again, and the fluctuation of current and voltage which is the result after the occurrence of disturbance is detected and dealt with. It is impossible.

Further, it is considered that the distance between the tip base materials and the variation of the wire feeding resistance are measured and the balance between the current and the voltage of the welding power source is controlled according to the results. Since it balances the current and welding voltage, it is redundantly related to all welding quality items such as leg length, penetration depth, bead appearance, etc.
It is difficult to establish an automatic control algorithm because there is no standard for how much the command value should be quantified as the balance of current and voltage with respect to the fluctuation amount of the disturbance.

The present invention has been made in view of the above-mentioned problems of the prior art. The substitute characteristic relating to welding quality is calculated or sampled in real time and feedback control of the balance of current and voltage is performed to quickly respond to disturbance. The problem to be solved is to stabilize the welding quality.

[0007]

SUMMARY OF THE INVENTION The gist of the invention of claim 1 which has solved the above-mentioned problems is (a) a specification input means for inputting a basic specification, and (b) a basic specification input to the specification input means. The initial condition setting means for setting the welding conditions by calculation, (c) the arithmetic expression memory in which each arithmetic expression used for the calculation of the initial condition setting means is stored, and (d) the initial condition setting means. And a condition file for storing welding conditions, and (e) a substitute characteristic relating to welding quality is obtained by calculation or sampling by the calculation formula in the calculation formula memory, and is set by the initial condition setting means based on the substitute characteristic. Condition automatic management correction means for correcting the current command parameter and the voltage command parameter of the welding condition, and (f) sending the teaching data and a signal indicating the welding speed to the robot. In addition, an automatic arc welding management device is configured from robot control means for instructing the condition automatic management correction means to send the current command parameter and voltage command parameter corrected by the condition automatic management correction means to the welding power source. , Is to correct the welding conditions that fluctuate according to the disturbance in real time by recognizing the substitute characteristics related to the welding quality.

The substitute characteristics relating to the welding quality are as shown in the following table. The condition automatic management correction means in the aspect of claim 2 is
Calculate the theoretical wire feed speed required to secure the specified leg length,
For comparing the theoretical wire feed rate and the detected wire feed rate sampled during welding, and for instructing the current output from the welding power source so that the detected wire feed rate is substantially equal to the theoretical wire feed rate. By increasing / decreasing the current command signal, the leg length is guaranteed in real time as the wire feeding speed is a substitute characteristic related to securing the leg length.

The condition automatic control correction means in claim 3 uses an equation for estimating the penetration depth including current, voltage and speed as variables, and the detected values of the respective variables sampled during welding are used as the equation for estimation. When the substitution result becomes smaller than the preset specified penetration depth, the current command signal is increased to secure the penetration depth by using the estimation formula of the penetration depth as a substitute characteristic.

The condition automatic control correcting means according to claim 4 reduces the command parameter of the welding current output from the welding power source so that the detected wire feeding speed is substantially equal to the theoretical wire feeding speed while the estimation is being performed. When the result of substituting into the formula becomes smaller than the specified penetration depth, while the specified penetration is restored, the command parameter of the welding current output from the welding power source is increased to secure a constant leg length and the specified penetration. Depth is secured complementarily.

According to the fifth aspect of the present invention, the condition automatic control correction means commands the voltage output from the welding power source so that the number of short-circuiting phenomena in which the tip of the wire being welded contacts the base metal is a preset number. By increasing or decreasing the welding voltage command signal, the number of short circuits is used as a substitute characteristic related to the bead appearance to prevent spatter and blowholes.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The automatic arc welding control system of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, the equipment for realizing the automatic control method of the present arc welding is based on an articulated robot 2 holding a welding torch (hereinafter abbreviated torch) 1 and welding power output of output terminals 3a, 3b. And a welding power source 3 for outputting a welding current and a welding voltage to the tip 16 of the torch, and command signals i, v for instructing the welding power source current I and voltage V to the welding power source 3 to send an arc. A welding controller 4 for automatically controlling welding, a robot controller 5 for controlling the articulated robot 2 based on teaching data TD including a signal indicating a welding speed, and a wire 7 as a consumable electrode filled in a drum 6 are provided. It comprises a wire feeder 8 for feeding the torch 1 and a jig 9 on which a welded article is placed.

The wire feeding device 8 assembled to the articulated robot 2 includes a bending straightener 11 and an encoder 1.
2. A pair of feeding rollers 13a, 13 holding the wire 7 therebetween.
b, a rotary actuator 14 that drives the rollers 13a and 13b, and a torch cable 1a that guides the wire 7 to the torch 1, and the wire 7 is projected from the tip 16 in the nozzle portion 15 of the torch 1.
Then, the rotary actuator 14 is controlled by the drive signal of the feed speed proportional to the magnitude (average value) of the command signal i from the welding controller 4 to feed out the wire 7, and the detection wire feed at that time is fed. The feed rate MR _a is sent from the encoder 12 to the welding controller 4.

The welding controller 4, which automatically sets the welding conditions (current, voltage and speed) and automatically corrects the welding conditions against disturbance, is shown in FIG. 2 which conceptually shows the hardware. As described above, basic specifications such as the joint shape, posture, leg length, distance between chip base materials and plate thickness, welding speed or welding cross-section area other than fillet welding, if necessary, can be set for each N joints in one product. To the specification input means 41, the initial condition setting means 42 for setting the welding conditions by calculation from the basic specifications input to the specification input means 41, and the respective arithmetic expressions used for the calculation of the initial condition setting means 42. Of the welding conditions set by the initial condition setting means 42, the condition memory 45 storing the welding condition set by the initial condition setting means, and the welding condition set by the initial condition setting means 42. Condition automatic management correcting means 44 for the flow command parameter P _I and the initial voltage command parameter P _V were corrected in accordance with the substitute characteristic related to weld quality modified current command parameter P _I 'and modified voltage command parameter P _V' It is composed mainly of.

The correction current command parameter P _I ′ and the correction voltage command parameter P _V ′ in digital signal form are D
The / A converter converts the analog current command signal i and the voltage command signal v into the welding power source 3, and commands the current and voltage to be derived from the output terminals 3a and 3b. In addition, the welding controller 4 includes
Detection welding current I _a of the current and voltage outputs from the welding power source 3 (when pulse welding is the average current of the pulse current) and the detection welding voltage V _a is adapted to be sampled.

Here, the initial current command parameter P _I
And the relationship between the modified current command parameter P _I ′ and the welding current I and the relationship between the initial voltage command parameter P _V and the modified voltage command parameter P _V ′ and the welding voltage V are as follows:
The relationship is set by correcting the characteristics of. That is, the current command parameters P _I and P _I ′ and the voltage command parameters P _V and P _V ′ are set so that the welding current and the welding voltage calculated in the welding controller 4 are output even if the welding power source changes. It is corrected every time.

On the other hand, the robot controller 5 is an electronic control device having a teaching data memory for each joint, and in actual welding, the robot controller 5
Reads the data in each memory in order and reads the articulated robot 2
Each of the axes is driven and a condition calling signal 5a is sent to the welding controller 4 every time one memory is read out to access the condition file 45. As a result, the welding conditions (P _I , P _{I) for} each joint are synchronized with the teaching data TD.
_V , I, V and welding speed WS) are read.

The set of each arithmetic expression stored in the arithmetic expression memory 43 is obtained in advance by experiments. An arc ON / OFF signal, which means start and stop of main welding, is sent to the welding controller 4 by the robot controller 5. Next, how the automatic control of the main arc welding is performed with the above-described configuration will be described with reference to the flowcharts of FIGS.

As shown in FIG. 3, the overall configuration is a preparation process including step S ₁ [basic specification input] and step S ₂ [automatic setting of optimum welding conditions], and step S ₄ [main welding start] and subsequent steps. The control process is performed by the specification input unit 41 and the initial condition setting unit 42.
The control loop is a process performed by the condition automatic management correction means 44. However, between the preparation process and the control loop,
Welded joints are inserted determines whether the step S ₃ there is a gap (between the ski) to, if the gap is present the flow proceeds to step S ₁₇ [automatic management of the gap portion]. The automatic management when there is this gap and step S ₁ and step S ₂ are not directly related to the present invention, so the description thereof will be omitted. However, in the automatic setting of the optimum welding conditions in step S ₂ , in the case of pulse welding, Welding conditions, welding conditions when performing spray transfer type welding even in MAG welding, and welding conditions when performing short circuiting transfer type welding in MAG welding are set separately.

Now, from the robot controller 5 the arc
When the ON signal is output, the welding control
La 4 is step S_Four[Welding parameter sampling] ~
Step S₁₄[Arc OFF signal input? ] Control loop
Execute In the above welding parameter sampling,
Outgoing wire feeding speed MR_a, Detected welding current I_a, Detection welding
Voltage V_aAnd the number of detection short circuits S_a(Control interval hit
The number of short circuits (including decimals less than 1)
You. Here, the number of detected short circuits S _aIs the detected welding voltage V
_aControl that (voltage at short circuit) drops below a specified threshold value
The number of times per interval.

[0021] or the control loop performs the welding of step S ₇ is determined in step S ₆ of determining when basic specifications input [current constant control or] [current constant control], the step S
₈ [leg constant control] and Step S ₉ [penetration depth ensures control] branches to or complementarily performed welding. Welding with constant current control gives priority to keeping the current constant and keeps the penetration depth constant.It is suitable for welding thin plates and not only secures the welding strength, but also eliminates the loss due to the increase in welding current. Prevent occurrence.

Welding in which the constant leg length control and the control for ensuring the specified penetration depth are complementarily performed means that even if the current fluctuations, in particular, decrease during the constant leg length control by giving priority to the constant wire feeding speed. When it is below a certain value, the welding current is increased to secure the specified penetration depth, which is suitable for welding thick plates. The specified penetration depth value is set when entering the basic specifications. Further, the welding controller 4 executes step S ₁₀ [short-circuit count / arc length constant control] in the case of pulse welding while controlling the above current, and determines step S ₁₁ [with spray] in the case of mag welding. After that, step S ₁₂ [spray transfer type control] or step S ₁₃ [short circuit transfer type control] is executed.

The short-circuit count / arc length constant control in the case of the above-mentioned pulse welding means that the detected short-circuit count _Sa is substantially equal to the short-circuit count set at the time of inputting the basic specifications (specifically, the lower limit value S ₁
And within the range of the upper limit S ₂ ), the voltage is controlled so as to be stable, and the spatter generation amount is suppressed and
The arc length is kept to a minimum (constant) to prevent undercuts and blow holes from occurring.

The spray transfer type control in the case of the MAG welding is a function of always holding the optimum voltage for spray transfer type welding (called spraying voltage) set by calculation in the initial condition setting means 42, and the detected welding voltage V _The voltage is controlled so that a is almost equal to the spraying voltage, and the optimum bead appearance is maintained. The short-circuit transfer type control in the case of the above-mentioned mag welding is a function of always holding the optimum voltage of the short-circuit transfer type welding set by calculation in the initial condition setting means 42, and the detected welding voltage V _a is the short-circuit transfer type optimum voltage. The voltage is controlled so as to be almost equal, and the optimum bead appearance is maintained.

[0025] Note that steps S ₁₅ [EXT operation] and step S ₁₆ [Display (warning)] which are processed in parallel with the control loop, when it calculates the distance between the chip base material, too if this distance is short If it is too long, a warning is given, but the distance between the chip base materials obtained in this process is used for control in the case of mag welding. Next, each processing of FIG. 3 will be described in more detail. 4, if the determination in step S ₂₁ is to perform the current constant control performs PI control in the step S ₂₃ to S ₂₅ corresponding to the step S ₇ [current constant control]. In this PI control, the difference ΔI (proportional term) between the initial set current I ₀ and the detected welding current I _a is obtained in step S ₂₃ , and subsequently, the time required for the change of the welding current until the difference ΔI becomes substantially zero. T _i (integral term) is calculated by integrating ΔI with time (step S ₂₄ ), and further, initial current command parameter P _I
The correction current command parameter P _I ′ is calculated by adjusting the correction amount by ΔI and T _i (step S ₂₅ ). Here, the coefficient K ₁₇₉ is a proportional term constant, and K ₁₈₀ is an integral term constant. The corrected current command parameter P thus obtained
_I 'step S ₂₇ [P _I' → D / A converter] → Step S ₂₈ [P _I analog signal output (to the welding power source) of '] processing through to step S ₁₄ [arc OFF signal input of the determination? ] To proceed. If the welding is not completed in step S ₁₄ , the welding power source 3 outputs a current based on the current command signal i corresponding to the modified current command parameter P _I ′.

When the steps S ₂₁ → S _{23 to} S ₂₇ are executed to change the distance between the tip base materials and the welding current increases or decreases, the initial current command parameter P _I is corrected according to the increase or decrease. Corrected to the current command parameter P _I ′,
Since the control for keeping the current constant functions, the increase in the penetration depth into the base material can be suppressed in advance, and the occurrence of dropout can be prevented.

By the way, if the determination in step S ₂₁ is to perform the welding of the leg length constant (& defined penetration depth ensured) is
First the process proceeds to step S ₃₈ [calculation of the penetration depth], detecting the welding current I _a, calculates-penetration depth P than estimation equation representing the relationship between the detection welding voltage V _a and welding speed WS and penetration depth P To do. Penetration depth P which is calculated from the estimated equation is compared with the step S ₃₉ [P <K _32] defines the penetration depth K ₃₂ by, when the penetration depth P less than the specified penetration depth K ₃₂ Is corrected by increasing the command parameter P _{I of the} current output from the welding power source 3 which has the highest contribution compared to the voltage and speed (step S ₄₀ ), and the calculated penetration depth P is the specified penetration depth K. When it is ₃₂ or more, the output (voltage) of the encoder 12 detected in step S ₅ is converted into the actual wire feeding speed to obtain the detected wire feeding speed MR _a (step S
₂₈ ) and the following step S ₂₉ [MR _a > MR _C ] → S ₃₀ [n
≧ 1] → S ₃₂ [MR _a <MR _C ] Judgment Wire feed rate MR _a and theoretical wire feed rate MR _C (calculated from relational expression of leg length L and welding speed WS when basic specifications are input) )
Is compared with the value multiplied by the coefficient K ₃₃ , and if MR _a is smaller than MR _C , step S ₃₁ [Wire feeding resistance is large. Please review the delivery system. ] Warning is displayed and the value n of the counter of the specified penetration depth control is zero,
The leg length constant control for keeping the wire feeding speed constant is performed by obtaining the corrected current command parameter P _I ′ by the PI control of steps S _{35 to} S ₃₇ .

Further, the value n of the number of times counter is 1 or more.
When step S₃₂[MR_a<MR_C] Judgment
U. This step S₃₂Event (MR_a<MR_C) Is true
Step S₃₃[P_I'= P_I+ ΔP_I] ON
-Execute OFF control to set the initial current command parameter P_I
To ΔP_ICorrected current command parameter P increased by_I′
On the contrary, the event (MR_a≧ MR_C) Is true, the
Up S₃₄[P_I'= P _I-ΔP_I] Run the initial current
Command parameter P_IΔP_IModified current finger reduced only
Command parameter P_I′ Is obtained and the value n of the frequency counter is zero
A constant leg length control that maintains a constant wire feed rate
Do your best.

[0029] Thus, if the defined penetration depth ensures control in has been performed once, ON-OF to increase or decrease the [Delta] P _I with a reduced its control slope as wire feed speed constant control
The reason for performing the F control is performed in wire feed speed constant control PI control after satisfy the penetration depth by increasing the P _I, occur sharp reduction in the wire feed rate, smooth Because it does not control.

The corrected current command parameter P _I ′ calculated in the above-described manner is the same as in the case of the constant current control, and it is judged in step S ₁₄ [arc-OFF signal input] through the processing of steps S ₂₆ → S _27. ? ] To proceed. Thus, in the main welding controller 4, the constant leg length and the provision of the specified penetration depth always act as a pair function, and even if the distance between the tip base materials changes or the wire feeding resistance changes, the leg length and the penetration depth also change. Sato will be secured.

[0031] Then the case of setting a pulse welding operation basic specification input pulse Yes (Y) next determines in step S ₄₂ [pulses Yes] in FIG. 5, step S ₄₃ [arc length a
Calculation of]] and the subsequent processing (step S _{10 in} FIG.
(Corresponding to arc length constant control))). This arc length a
Is the distance between the tip base metals EXT, the welding voltage V, the peak current I _a of the pulse welding current, the base current I _b, and the average current I.
It can be calculated by an arithmetic expression with _av as a parameter.

The obtained calculated arc length a is compared with the maximum allowable arc length a _o in the following step S ₄₄ [a _O ≤a]. If the calculated arc length a is larger than the maximum allowable arc length a _o ,
In step S ₄₇ [P _V ′ = P _V −K ₁₄₆ ], the operation proceeds to step S ₅₀ [P _V ′ → D / A conversion], and in the subsequent step S ₅₁ [P _V ′ analog signal output], The welding power source 3 is commanded by the voltage command signal v based on the corrected voltage command parameter P _V ′.

Next, if the operation arc length a maximum allowable arc length a _o is smaller than in step S _44, step S ₄₅ [S
_a ≦ S ₁ ], the detected short circuit frequency S _a obtained at the time of sampling is compared with the lower limit value S ₁ of the short circuit frequency. When the number of detected short circuits S _a is less than or equal to the lower limit value S _{1 of the} number of short circuits,
The calculation of step S ₄₈ [P _V ′ = P _V −ΔP _V ] is performed, and the process proceeds to step S ₅₀ [P _V ′ → D / A conversion]. As a result, when the number of short circuits decreases below the lower limit S ₁ , the correction voltage command parameter P _V ′ is decreased (the relationship between the number of short circuits and the arc length (arc voltage) is inversely proportional) and the number of short circuits is increased. .

If the calculated arc length a is smaller than the maximum allowable arc length a _{o and} the judgment in step S ₄₅ is "the detected short circuit number S _a is larger than the lower limit number S _{1 of} short circuit numbers", step S _{46 is executed.} Proceed to [S _a ≤ S ₂ ] and compare the detected short circuit count S _a with the upper limit S ₂ of the short circuit count. When the detected number of short circuits S _a is larger than the upper limit value S _{2 of the} number of short circuits, the calculation of step S ₄₉ [P _V ′ = P _V + ΔP _V ] is performed and step S ₅₀ [P _V ′ → D / A conversion ] To proceed. As a result, when the number of short circuits is larger than the upper limit value S ₂ , the correction voltage command parameter P _V ′ is increased and the number of short circuits is reduced.

Furthermore, if the determination of step S ₄₆ is "detected number of short circuits S _a is an upper limit values S ₁ following short number", the flow proceeds to step S ₁₄ without performing the correction of the initial voltage command parameters. In this way, the amount of spatter generated in pulse welding can be suppressed, the arc length can be kept to a minimum, and the occurrence of undercuts, blowholes, etc. can be prevented. Next, if MAG welding is set when the basic specifications are entered, the judgment in step _S42 [with pulse] in FIG. 5 is MAG welding (N).
Then, the process proceeds to the flowchart of FIG.

[0036] In Figure 6 further determines whether to perform a short circuiting transfer type welding or performing spray transfer type welding by step S _11. The result of this judgment is set at the time of inputting the basic specifications. If spray transfer type welding is to be performed, step S
₅₂ [EXT = f (MR _a , I _a )] and subsequent PI control is performed. When short-circuit transfer type welding is to be performed, the process proceeds to PI control after step S ₅₇ .

The calculation of each PI control of the spray transfer type welding and the short circuit transfer type welding is the same as the calculation for the constant current control and the constant leg length control. In the spray transfer type welding, the spraying voltage V _SC is short-circuited. In the case of transitional welding, the correction voltage command parameter P _V ′ is calculated so that the detected welding voltage V _a is approximately equal to the optimum voltage V _C that is the number of times of short circuit that has been initialized. Incidentally, Step S ₅₂ of spray transfer type welding operation expression _{EXT = f (MR a, I} a) determine the distance between the tip base member by, step S ₅₃ is V _SC = f
(I _a , EXT) to set the spraying voltage, step ₅₄
Is a proportional term ΔV = V _SC −V _a , and step S ₅₅ is an integral term T.
_{i +} = ∫ΔVdt is obtained, and step S ₅₆ [P _V ′
= P _V + K ₁₆₆ · ΔV + K ₁₆₇ · T _{i +} ], the corrected voltage command parameter P _V ′ is calculated. Further, in the case of short-circuit transfer type welding, step _S57 is for calculating the distance between the tip base materials, and step _S58 is the step S of the short-circuit transfer type optimum voltage V _C.
59 is the proportional term V _C −V _a , and step S ₆₀ is the integral term T
Step S ₆₁ of _{i +} is the calculation of the correction voltage command parameter P _V ′.

Next, as shown in FIG. 7, the function of displaying (warning) the distance between the tip base metals provided in the main welding controller 4 is, as shown in FIG. 7, first, in step S ₆₂ [EXT = f (MR _a ,
I _a )] to calculate EXT. The arithmetic expression used in this step S ₆₂ is obtained by an experiment for each of the remaining two relational expressions with each one of EXT, MR and I being constant. When the distance between the chip base materials is obtained, step S
₆₃ [EXTo-K ₁₄₃ <EXT <EXTo + K ₁₄₄ It is determined whether or not it is within the allowable variation range (EXTo-K _{143 to} EXTo + K ₁₄₄ ), and if it is within the variation range, it is determined by step S ₆₄ . The value is displayed on the screen of the welding controller 4. If it is out of the variation range in step S ₆₃ , the process proceeds to step S ₆₅ , and if the calculated EXT is smaller than EXT _O −K _{143, the} distance between the chip base materials is set to the initial set value EX in step S ₆₆ .
If the calculated tip base metal distance EXT is equal to or larger than EXT _O -K ₁₄₃ , a warning is given that the distance is too short than T _{o, and} in step S _{67 the} chip base metal distance is set to the initial set value EX.
Warning that than T _o too long.

Therefore, by issuing a warning to the operator when the distance between the chip base materials becomes abnormal as described above, the operator reviews the robot teaching and reduces the variation in the distance between the chip base materials after the teaching is corrected. The stability of each control for the above-mentioned welding quality control is achieved. In addition, the welding controller described in the above-described embodiment, the command parameter P every time the welding of one joint is completed, that is, every time the arc OFF signal is detected.
_I and P _V are returned to the initial setting values.

Further, ΔP _{I in} FIG. 4 Δ in FIG.
P _V is the amount of increase / decrease correction of the current / voltage command parameters Pi, Pv. Further, in the above-described embodiment, the constant leg length control and the control of the specified penetration depth are disclosed complementarily, but the present invention is applicable even when these are performed independently.

[0041]

As described above, according to the present invention, the quality control during welding is automatically performed, and both the strength and the appearance are excellent regardless of the influence of disturbance such as teaching accuracy and the thickness of the base material. Welding can be performed. Particularly, according to the aspect of claim 2, by controlling the wire feeding speed, the guarantee of strength by securing the leg length is achieved.

According to the third aspect of the invention, the penetration depth can be guaranteed by using the penetration depth estimation formula, and the occurrence of a situation where the penetration depth is below the specified penetration depth can be reliably prevented. it can. According to the aspect of claim 4, by complementarily performing the control according to the aspects of claim 1 and claim 2, the leg length is ensured by the constant control of the wire feeding speed, and the penetration depth estimation formula is used. By ensuring the prescribed penetration depth by means of the above, the strength in welding thick plates can be guaranteed.

According to the fifth aspect, regardless of pulse welding or mag welding, generation of spatter, blowholes, undercuts, etc. can be suppressed and a good bead appearance can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the entire equipment embodying the present invention.

FIG. 2 is a conceptual diagram of FIG. 1 when the welding controller is represented by hardware.

FIG. 3 is a flowchart illustrating an entire arc welding automatic control system according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a specific example of the constant current control of FIG. 3 and the complementary control of constant leg length and ensuring a specified penetration depth.

FIG. 5 is a flowchart showing a voltage control program according to the present invention in the case of pulse welding.

FIG. 6 is a flowchart showing a program for voltage control according to the present invention in the case of mag welding.

FIG. 7 is a flowchart showing a calculation display program of a distance between tip base materials provided in the present welding controller.

FIG. 8 is an explanatory diagram summarizing disturbances in arc welding.

FIG. 9 is a graph showing a relationship between a distance between tip base materials and a welding current in arc welding.

FIG. 10 is a flowchart illustrating conventional welding quality control.

[Explanation of symbols]

1 is a welding torch, 2 is a robot, 3 is a welding power source, 4 is a welding controller, 12 is an encoder, 14 is a rotary actuator, 44 is a condition automatic management correction means, EXT is a distance between chip base materials, I is a welding current and V Is a welding voltage, I _a is a detected welding current, V _a is a detected welding voltage, MR is a wire feeding speed, MR _a is a detected wire feeding speed, MR _C is a theoretical wire feeding speed, WS is a welding speed, and i is A current command signal, v is a voltage command signal, and the same elements in each figure are denoted by common reference numerals. The constants used in FIGS. 4 to 7 are: I: actual current (welding current) I ₀ : initial setting current S: short circuit count S 1: upper limit of short circuit count S 2: lower limit value of short circuit count M _RC : theory wire feed rate L _o: the arc length of the maximum value K _32: defined penetration depth K _33: wire feed rate fluctuation tolerance K _34: addition amount of current of penetration control K _143: inter-chip matrix Distance variation (-) K ₁₄₄ : Distance variation between chip base materials (+) K ₁₄₅ : Wire feed speed variation and start time of distance variation between chip base materials K ₁₄₆ : Rising voltage of arc length control Gradient K ₁₅₅ : Proportional term constant for constant wire feed rate PI control K ₁₅₆ : Integral term constant for constant wire feed rate PI control K ₁₇₉ : Proportional term constant for constant current PI control K ₁₈₀ : Integral term for constant current PI control It is a constant.

Claims (5)

[Claims] 1. Welding is performed by outputting a current and voltage from a welding power source to a wire through a tip of the tip of the welding torch, activating the robot holding the welding torch while melting the wire by the teaching data according to teaching data. An automatic control device for arc welding to be performed, comprising a specification input means for inputting basic specifications, an initial condition setting means for calculating welding conditions from the basic specifications input to the specification input means, and the initial conditions. An arithmetic expression memory in which each arithmetic expression used for the arithmetic operation of the setting means is stored, a condition file for storing the welding conditions set by the initial condition setting means, and a substitute characteristic related to welding quality are stored in the arithmetic expression memory. The current command parameter and the electric current of the welding condition set by the above-mentioned initial condition setting means based on the substitute characteristic are obtained by calculation using an arithmetic expression or sampling. A condition automatic management correction means for correcting the command parameter and a signal indicating the teaching data and the welding speed are sent to the robot, and the current command parameter and voltage command parameter corrected by the condition automatic management correction means are supplied to the welding power source. Automatic control apparatus for arc welding, comprising: robot control means for instructing the condition automatic management correction means to send to the condition. 2. The condition automatic control correction means calculates a theoretical wire feed speed required to secure a designated leg length, and compares the theoretical wire feed speed with a detected wire feed speed sampled during welding. 2. The automatic arc welding control apparatus according to claim 1, wherein the command parameter of the welding current output from the welding power source is increased or decreased so that the detected wire feeding speed becomes substantially equal to the theoretical wire feeding speed. 3. The condition automatic control correction means uses an estimation formula of penetration depth including current, voltage and speed as variables, and substitutes detection values of the respective variables sampled during welding into the estimation formula. The automatic arc welding control device according to claim 1, wherein the command parameter of the welding current output from the welding power source is increased when the result is smaller than a preset specified penetration depth. 4. The condition automatic management correction means uses the estimation formula while decreasing the command parameter of the welding current output from the welding power source so that the detected wire feeding speed becomes substantially equal to the theoretical wire feeding speed. The command parameter of the welding current output from the welding power source is increased while the result of substitution becomes smaller than the specified penetration depth while recovering the specified penetration depth or higher. Automatic control device for arc welding. 5. The condition automatic management correction means sets a command parameter of a voltage output from the welding power source so that the number of short-circuiting phenomena in which the tip of the wire during welding comes into contact with the base metal is a preset number of times. The automatic control device for arc welding according to claim 1, wherein the automatic control device is increased or decreased.