JP2017039160A - Arc-welding quality judging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that judgment of defective welding cannot be performed in non-steady state (such as, upon welding initiation, upon welding completion or upon intentional change of welding conditions) in the conventional technique in which quality judgement of arc-welding is performed based on whether welding electric current or welding voltage exceeds a preset threshold.SOLUTION: An arc-welding quality judging system includes a setting part which sets an upper limit value at a first time based on the maximum value at the first time or at a plurality of times containing the first time at every first time, and sets a lower limit value at the first time based on the minimum value at the first time or at the plurality of times containing the first time, in a prescribed population. The arc-welding quality judging system further includes a judgment part which, when a measurement value obtained upon welding exists between the upper limit value and the lower limit value, judges that there is no defective welding and, when the measurement value exists outside the range, judges that there is a defective welding.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an arc welding quality judgment system.

  In a production site using a welding robot, one of the main factors hindering stable production is welding failure. Inadequate bead formation, which is one of the welding defects, can occur due to the following factors, for example. For example, even if the welding conditions are set in advance so as to obtain an appropriate bead shape for the workpiece to be constructed, the protrusion length may vary due to the displacement of the workpiece during actual construction. In this case, the welding current fluctuates with fluctuations in the protruding length, and as a result, insufficient bead formation may occur. In addition, for example, a contact tip that supplies power to the welding wire may be worn, and insufficient power supply may occur with the wear of the contact tip. In this case, the welding current decreases due to insufficient power supply, and as a result, insufficient bead formation may occur. Further, for example, the welding wire shavings may be clogged in the wire feeding device. In this case, arc breakage due to defective wire feeding may occur, and as a result, defective bead formation such as weld bead chipping may occur.

  For this reason, techniques for reducing welding defects themselves and techniques for more accurately detecting welding defects have been developed. As a technique for detecting a welding defect more accurately, for example, the following Patent Document 1 has been proposed. Patent Document 1 proposes a technique for determining that a welding failure has occurred when a moving average value of an actual welding current or welding voltage during arc welding deviates from a preset range.

Japanese Patent Publication No. 7-2275

  However, in the invention described in Patent Document 1, since the threshold value is a constant value based on the welding conditions (welding current, welding voltage, etc.) at the time of steady state, a state that is not steady state (for example, start of welding) There is a problem that it is not possible to determine the welding failure at the time, at the end of welding, or when the welding conditions are changed intentionally.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an arc welding quality determination system capable of determining a welding failure even during welding other than during normal operation. .

  In the first arc welding quality determination system of the present invention, when a plurality of measurement values obtained when welding is repeatedly performed under a common welding condition setting, the first is used in the population. For each time, an upper limit value at the first time is set based on the first time or the maximum value at a plurality of times including the first time, and at the first time or a plurality of times including the first time. A setting unit for setting a lower limit value at the first time based on the minimum value is provided. The first arc welding quality determination system further determines that there is no welding failure when the measured value obtained during welding under the above welding condition setting is in the range between the upper limit value and the lower limit value, and the measured value is out of range. When it exists in, it has the determination part which determines with a welding defect.

In the second arc welding quality determination system of the present invention, when a plurality of measurement values obtained when welding is repeatedly performed under a common welding condition setting,
For each first time, a setting unit is provided that sets an upper limit value and a lower limit value at the first time based on the standard deviation at the first time or a plurality of times including the first time. The second arc welding quality determination system further determines that there is no welding failure when the measured value obtained during welding under the above welding condition setting is in the range between the upper limit value and the lower limit value, and the measured value is out of range. When it exists in, it has the determination part which determines with a welding defect.

  In the first and second arc welding quality determination systems of the present invention, a threshold value used for determining a welding failure is set based on a statistical value obtained from a population including a plurality of past measurement values. . Thereby, the threshold value used for determination of poor welding becomes a value reflecting the stability of welding.

  According to the first and second arc welding quality determination systems of the present invention, the threshold used for determining the welding failure is a value that reflects the stability of the welding. Even so, it is possible to determine poor welding.

It is a figure showing an example of schematic structure of the welding robot system provided with the arc welding quality judgment system concerning one embodiment of the present invention. It is a figure showing an example of the functional block in the learning mode of the welding robot system of FIG. It is a figure showing an example of schematic structure of the robot control apparatus of FIG. It is a perspective view showing an example of the mode of arc welding using the welding robot system of FIG. It is a figure showing an example of each relationship of each track | orbit m, unit time (DELTA) T, and a setting start command when the welding area of FIG. 4A is divided into a some track | orbit. It is a figure showing an example of the setting method of a threshold value. It is a figure showing an example of the setting method of a threshold value. It is a figure showing an example of the setting method of a threshold value. It is a figure showing an example of the setting method of a threshold value. It is a figure showing an example of schematic structure of the teach pendant of FIG. It is a figure showing an example of schematic structure of the welding machine of FIG. It is a figure showing an example of the functional block in the abnormality determination mode of the welding robot system of FIG. It is a figure showing an example of the graphic display in the display surface of the teach pendant of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[Constitution]
FIG. 1 shows an example of a schematic configuration of a welding robot system 1 including an arc welding quality determination system according to an embodiment of the present invention. FIG. 2 shows an example of functional blocks in the learning mode of the welding robot system 1 of FIG. The welding robot system 1 has two modes: a learning mode and an abnormality determination mode.

  The welding robot system 1 first captures arc characteristics by performing arc welding a plurality of times (N times) under the same setting conditions in the learning mode. The welding robot system 1 then switches from the learning mode to the abnormality determination mode, performs arc welding under the same setting conditions as in the learning mode, and obtains the arc characteristics obtained in the learning mode and the abnormality determination mode. The state of the formed weld bead is determined by comparing the characteristics of the arc. The setting condition refers to the setting condition when forming the weld bead.

  In other words, the “learning mode” is the state of the weld bead formed in the abnormality determination mode by performing arc welding a plurality of times under the same setting conditions as those for forming the weld bead in the abnormality determination mode. This is a mode for creating a predetermined determination criterion when determining the above. The “abnormality determination mode” refers to a mode for determining the state of a weld bead formed in the abnormality determination mode using a predetermined determination criterion acquired in the learning mode. In the following, the configuration related to the learning mode will be described first, and then the configuration related to the abnormality determination mode will be described.

[Configuration in learning mode]
The welding robot system 1 performs arc welding on a workpiece W by a program-controlled articulated robot. The welding robot system 1 includes a manipulator 10, a robot controller 20, a teach pendant 30, and a welder 40. A system including the robot controller 20, the teach pendant 30, and the welder 40 corresponds to a specific example of the “arc welding quality determination system” of the present invention. The robot control device 20 and the teach pendant 30 may be configured integrally with each other, or may be configured separately from each other as shown in FIG.

  The welding robot system 1 includes, for example, cables L1 to L6 that connect the robot control device 20 and various devices to each other. The cable L1 is a communication cable for communicating between the robot control device 20 and the manipulator 10, and is connected to the robot control device 20 and the manipulator 10. The cable L2 is a communication cable for communicating between the robot control device 20 and the teach pendant 30, and is connected to the robot control device 20 and the teach pendant 30. The cable L3 is a communication cable for communicating between the robot control device 20 and the welding machine 40, and is connected to the robot control device 20 and the welding machine 40. The cable L4 is a communication cable for communicating between the welding machine 40 and a wire feeding device 14 described later, and is connected to the welding machine 40 and the wire feeding device 14. Cables L5 and L6 are power cables for supplying a high welding voltage Vs between a welding wire 15 and a workpiece W, which will be described later. The cable L5 is connected to the welding machine 40 and a worktable 15 described later, and the cable L6 is connected to the welding machine 40 and a welding torch 13 described later.

(Manipulator 10)
The manipulator 10 performs arc welding on the workpiece W under the control of the robot control device 20, the teach pendant 30 and the welding machine 40. The manipulator 10 includes a base member 11 fixed to a floor or the like, a multi-joint arm portion 12 provided on the base member 11, a welding torch 13 connected to the tip of the multi-joint arm portion 12, and a multi-joint arm portion. The wire feeder 14 fixed to 12 grade | etc., And the work table 15 are provided.

  The multi-joint arm unit 12 includes, for example, a plurality of arms 12A and one or a plurality of joint shafts (not shown) that rotatably connect the two arms 12A. The articulated arm unit 12 is further provided, for example, one for each arm 12A, and is connected to a plurality of drive motors (not shown) that drive the corresponding arm 12A and each of the drive motors. And an encoder (not shown) for detecting the current position. Each drive motor is driven by a control signal input from the robot controller 20 via the cable L1. By driving each drive motor in this way, each arm 12A is displaced, and as a result, the welding torch 13 moves up and down, front and rear, and right and left. The encoder is configured to output the detected current position of each arm 12A (hereinafter referred to as “position information”) to the robot controller 20 via the cable L1.

  One end (tip) of the articulated arm portion 12 is connected to the welding torch 13, and the other end of the articulated arm portion 12 is connected to the base member 11. A welding wire 15 as a filler material is exposed at the tip of the welding torch 13. The welding torch 13 performs arc welding on the workpiece W by generating an arc between the tip of the welding wire 15 and the workpiece W and melting the welding wire 15 and the workpiece W with the heat of the arc. is there. The welding torch 13 has a contact tip (not shown) electrically connected to the cable L4. The contact tip is configured to supply the welding wire 15 with the welding voltage Vs supplied from the cable L4.

  The wire feeder 14 supplies the welding wire 15 to the welding torch 13. The wire feeder 14 has, for example, a pair of rolls (not shown) configured to hold the welding wire 15 and be capable of feeding, and a motor (not shown) that rotationally drives one of the rolls. ing. The pair of rolls are configured to sandwich the welding wire 15 and pull the welding wire 15 from a wire reel (not shown) by frictional force generated by rotational driving by the motor. The said motor is comprised by the servomotor with an encoder, for example. The motor is driven by a control signal input from the welding machine 40 via the cable L4. The motor is configured to output, for example, a pulse fed back from the encoder to the welding machine 40 via the cable L4. This pulse can be suitably used for calculating the feeding speed of the welding wire 15 (wire feeding speed Vf). The motor may generate and output some signal instead of the pulse. The wire feeder 14 further includes, for example, an ammeter (not shown) that measures the drive current flowing through the motor. The drive current measured by this ammeter can be suitably used for calculating the feed load (wire feed load Ld) of the welding wire 15.

  The work table 15 is fixed to a floor or the like, and is used as a pedestal on which the work W is installed. The work table 15 may be a positioner for optimally maintaining the torch posture with respect to the workpiece W. When the work table 15 is the above-described positioner, the axis of the positioner is driven and controlled by the robot control device 20. The work table 15 is connected to the welding machine 40 via a cable L5, and is configured to electrically connect the workpiece W and the cable L5 installed on the work table 15.

(Robot controller 20)
FIG. 3 illustrates an example of a schematic configuration of the robot control device 20. The robot control device 20 controls the articulated arm unit 12 and the welding machine 40 in accordance with instructions from the teach pendant 30. The robot control device 20 further determines the quality of the weld bead formed by generating an arc between the tip of the welding wire 15 and the workpiece W. The robot control device 20 includes a control unit 21, a servo control unit 22, a communication unit 23, and a storage unit 24. Below, it demonstrates in order of the memory | storage part 24, the servo control part 22, the communication part 23, and the control part 21. FIG. The control unit 21 corresponds to a specific example of “setting unit” and “determination unit” of the present invention.

  The storage unit 24 can store various programs and various data files. The storage unit 24 stores a control program 22 </ b> A that controls the operation of the articulated arm 12. The control program 22A is stored, for example, in a ROM (read only memory). The storage unit 24 further includes one or a plurality of work programs 22B in which a welding work procedure of the manipulator 10 is taught, an arc welding quality judgment program 22C for judging the quality of the weld bead, and settings in which various set values are described. The file 22D is stored. One or a plurality of work programs 22B, an arc welding quality determination program 22C, and a setting file 22D are stored in, for example, a hard disk. In the setting file 22D, for example, set values of the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the welding speed Vw are described. The arc welding quality judgment program 22C will be described in detail later. The welding work procedure described in the one or more work programs 22B and various setting values described in the setting file 22D correspond to a specific example of “welding conditions” of the present invention.

Furthermore, the storage unit 24 can store various data generated by executing the arc welding quality determination program 22C. Examples of files including such data include a measurement file 22E and a threshold file 22F. In the measurement file 22E, measurement values of various physical quantities are described. Here, the measured value may be an instantaneous value, but is preferably a moving average value from the viewpoint of ease of setting a threshold value. The various physical quantities include, for example, a welding current Is, a welding voltage Vs, a wire feeding speed Vf, a welding speed Vw, and a short circuit frequency fs. The short-circuit frequency fs is the number of times that the welding wire 15 and the workpiece W are short-circuited per second during welding. In the measurement file 22E, measurement values of various physical quantities obtained by measuring at the sampling frequency Δfs are described. In the threshold file 22F, for example, an upper limit value P _upper (x) and a lower limit value P _lower (x) generated by the setting unit 215 described later are described. These files are stored in, for example, a RAM (Random Access Memory). The upper limit value P _upper (x) and the lower limit value P _lower (x) will be described in detail later.

  The servo control unit 22 controls each drive motor of the manipulator 10. The servo control unit 22 controls each drive motor of the manipulator 10 based on the movement command described in the work program 22B and the position information from the encoder of the manipulator 10. The movement command may include, for example, a movement start command, a movement stop command, a work path (teaching point), a torch posture, and the like. In addition, the servo control unit 22 derives (measures) the position information Pf and the welding speed Vw of the tip of the welding torch 13 based on the position information from the encoder of the manipulator 10. The servo control unit 22 outputs the position information Pf and the welding speed Vw to the control unit 21.

  The communication unit 23 communicates with the teach pendant 30 via the cable L2, or communicates with the welding machine 40 via the cable L3. The communication unit 23 receives a work command from the teach pendant 30 and outputs it to the control unit 21. The work command may include, for example, the number of the work program 22B selected by the worker.

  The communication unit 23 is configured to transmit a welding command from the control unit 21 to the welding machine 40. The welding command includes, for example, an arc welding start command, an arc welding end command, a set value of the welding current Is, a set value of the welding voltage Vs, a wire feed start command, a wire feed stop command, and a wire feed. A set value of the feed speed Vf can be included. The communication unit 23 receives monitor information (for example, various measurement values or notification information) from the welding machine 40 and stores it in the measurement file control unit 21 of the storage unit 22. Furthermore, the communication part 23 outputs the notification information from the welding machine 40 to the control part 21 as needed. The various measurement values may include, for example, measurement values of the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the short-circuit frequency fs. The notification information can include, for example, an arc occurrence notification.

  The control unit 21 has an analysis unit 211 that reads out the work program 22B and the arc welding quality determination program 22C based on the work command input from the teach pendant 30 and analyzes the contents (see FIG. 2). The analysis unit 211 is configured to generate a command notification corresponding to the instructions described in these programs based on the analysis result of the analysis unit 211. The control unit 21 includes an execution unit 212 that outputs a movement command and a welding command in accordance with the content of the command notification generated by the analysis unit 211 (see FIG. 2).

  The control part 21 has the welding control part 213 which outputs the welding command produced | generated by the execution part 212 to the welding machine 40 via the communication part 23 (refer FIG. 2). For example, when a welding command is generated by the execution unit 212, the welding control unit 213 generates a notification (track recording start notification) for starting track recording at the tip of the welding torch 13. Further, for example, the welding control unit 213 generates a notification (trajectory recording end notification) for ending the track recording at the tip of the welding torch 13 according to the moving distance Δdist (= welding distance Wp) of the tip of the welding torch 13. It has become. The movement distance Δdist is derived by a trajectory recording unit 214 (see FIG. 2) described later.

  The control unit 21 has a track recording unit 214 that starts track recording of the tip of the welding torch 13 in accordance with the track recording start notification from the welding control unit 213 (see FIG. 2). The track recording unit 214 records the position information Pf of the tip of the welding torch 13 in the welding section WS every unit time ΔT, and calculates and records the movement distance Δdist of the tip of the welding torch 13 every unit time ΔT. It has become. The movement distance Δdist is obtained, for example, by taking the difference between the latest position information Pf and the position information Pf before the unit time ΔT. The track recording unit 214 may derive the movement distance Δdist (= welding distance Wp) from the welding speed Vw × the arc time At. The arc time At corresponds to the time after receiving the arc occurrence notification.

  Here, the welding section WS, the unit time ΔT, and the trajectory m will be described. FIG. 4A shows an example of arc welding using the welding robot system 1. FIG. 4B shows an example of the relationship between each track m and unit time ΔT when the welding section WS is divided into a plurality (M) of tracks m (1 ≦ m ≦ M). FIG. 4A shows the workpiece W in which the ends of the two base materials 110 are in contact with each other so that the two base materials 110 are orthogonal to each other. FIG. 4A illustrates a so-called fillet welding state. Note that the welding robot system 1 is not limited to fillet welding, but can be used for other types of welding.

  The welding section WS indicates a section of the weld line from the start of arc welding to the end of arc welding. The weld bead 120 is formed in the whole or a part of the welding section WS. The welding section WS is divided into M tracks m, and the time required for the tip of the welding torch 13 to move on each track m is a unit time ΔT. When the track recording unit 214 receives the Nth track recording end notification from the welding control unit 213, the track recording unit 214 outputs a setting start command Os. Note that the sampling period Δt in FIG. 4B is the reciprocal of the sampling frequency Δfs.

The control unit 21 includes a setting unit 215 that performs setting in accordance with a setting start command Os (see FIG. 2). The setting unit 215 corresponds to a specific example of “setting unit” of the present invention. Upon receiving the setting start command Os, the setting unit 215 acquires a plurality of (N) measured values P _{1 to} P _N of a specific physical quantity from the measurement file 22E of the storage unit 24 as a population. Yes. The specific physical quantity is, for example, a physical quantity preset by the user, and is, for example, at least one of a welding current Is, a welding voltage Vs, a wire feed speed Vf, a welding speed Vw, and a short-circuit frequency fs.

The control unit 21 may detect the measurement value Px (i) (starting measurement value) that is the closest to the welding start position or welding start included in the acquired measurement values P _{1 to} P _N. In this case, the control unit 21 starts from the time of the start measurement value detected for each of the measurement values P _{1 to} P _N , and the _upper limit value P _upper (x) and the lower limit value at the time tx defined by the sampling period Δt. P _lower (x) may be set. The control unit 21, for example, based on the welding start position or welding start time stored in the measurement file 22E of the storage unit 24, includes the acquired measurement values P _{1 to} P _N at the welding start position or welding start time. The closest measured value Px (i) (starting measured value) may be detected. The control unit 21 includes, for example, based on the characteristics of the time variation of the measured values P ₁ to P _N acquired are included in each measurement value P ₁ to P _N acquired closest measured at the start welding start position or welding The value Px (i) (starting measurement value) may be detected.

When the N measurement values P _{1 to} P _N (1 ≦ i ≦ N) of a specific physical quantity acquired from the measurement file 22E in the storage unit 24 are set as a population, the setting unit 215 performs sampling in the population. For each time tx (1 ≦ x ≦ X) defined by the period Δt, the upper limit at time tx is based on the maximum value Pmax (x) of N measurement values Px (1) to Px (N) at time tx. A value P _upper (x) is set. For example, as illustrated in FIG. 5, the setting unit 215 sets P _upper (x) using Expression (1). In equation (1), P _upper (x) is a value obtained by adding a constant K (K ≧ 0) to the maximum value Pmax (x) of N measurement values Px (1) to Px (N) at time tx. expressed.

Note that the setting unit 215 may set P _upper (x) using the following equation, for example. In the following equation, P _upper (x) is a maximum value Pmax (x) of N measurement values Px (1) to Px (N) at time tx, a constant K, and N measurements at each time tx. It is represented by a value obtained by adding L times the absolute value (| Δμx |) of the differential Δμx of the average value μx in the function representing the average value μx of the values Px (1) to Px (N).
P _upper (x) = Pmax (x) + K + L | Δμx |
Δμx = (μx−μx−1) / (tx−tx−1)

The setting unit 215 further sets a lower limit value at the time tx based on the minimum value Pmin (x) of the N measurement values Px (1) to Px (N) at the time tx for each time tx in the population. P _lower (x) is set. For example, as illustrated in FIG. 5, the setting unit 215 sets P _lower (x) using Expression (2). In Expression (2), P _lower (x) is a value obtained by subtracting a constant K (K ≧ 0) from the minimum value Pmin (x) of N measurement values Px (1) to Px (N) at time tx. expressed.

Note that the setting unit 215 may set P _lower (x) using the following equation, for example. In the following expression, P _lower (x) is obtained by subtracting a constant K and L | Δμx | from the maximum value Pmax (x) of N measurement values Px (1) to Px (N) at time tx. Represented by value.
P _lower (x) = Pmax (x) −K−L | Δμx |

The setting unit 215 sets the _upper limit value P _upper (x) at the time tx based on the standard deviation σx of the N measurement values Px (1) to Px (N) at the time tx for each time tx in the population. May be set. For example, as illustrated in FIG. 6, the setting unit 215 may set an upper limit value P _upper (x) using Expression (3). Specifically, the setting unit 215 sets the N measurements at the time tx to the average value μx of the N measurement values Px (1) to Px (N) at the time tx for each time tx in the population. A value obtained by adding K times (K ≧ 1) the standard deviation σx of the values Px (1) to Px (N) may be set to the _upper limit value P _upper (x) at time tx.

Further, the setting unit 215 further sets the _lower limit value P _lower (at the time tx) based on the standard deviation σx of the N measurement values Px (1) to Px (N) at the time tx in the population at each time tx. x) may be set. For example, as illustrated in FIG. 6, the setting unit 215 may set the lower limit value P _lower (x) using Expression (4). Specifically, the setting unit 215 performs N measurements at time tx from the average value μx of N measurement values Px (1) to Px (N) at time tx for each time tx in the population. A value obtained by subtracting K times (K ≧ 1) the standard deviation σx of the values Px (1) to Px (N) may be set as the _lower limit value P _lower (x) at time tx.

The setting unit 215 sets the maximum value Pmax (x) of NY (Y ≧ 2) measured values Pz (1) to Pz (NY) at a plurality of times including the time tx in the population. Based on this, an upper limit value P _upper (x) at time tx may be set. At this time, the setting unit 215 performs NY (Y ≧ 3) measurement values Pz (3) at three or more times including the time tx and the times tx−1 and tx + 1 before and after the time tx in the population. The upper limit value P _upper (x) at time tx may be set based on the maximum value Pmax (x) of 1) to Pz (NY). For example, as illustrated in FIG. 7, the setting unit 215 may set P _upper (x) using Expression (5). In Expression (5), P _upper (x) is a constant K (K ≧ 0) to the maximum value Pmax (x) of 3N measurement values Pz (1) to Pz (3N) at times tx−1, tx, and tx + 1. ) Is added. The 3N measurement values Pz (1) to Pz (3N) are N measurement values P _x-1 (1) to P _x-1 (N) and N measurement values P _x (1) to P _x. (N) and N measurement values P _{x + 1} (1) to P _{x + 1} (N).

In addition, the setting unit 215 further includes, for each time tx, the NY (Y ≧ 2) measured values Pz (1) to Pz (NY) minimum values Pmin (x) at a plurality of times including the time tx. ), The lower limit value P _lower (x) at time tx may be set. At this time, the setting unit 215 performs NY (Y ≧ 3) measurement values Pz (3) at three or more times including the time tx and the times tx−1 and tx + 1 before and after the time tx in the population. The lower limit value P _lower (x) at time tx may be set based on the minimum value Pmin (x) of 1) to Pz (NY). For example, as illustrated in FIG. 7, the setting unit 215 may set P _lower (x) using Expression (6). In Expression (6), P _lower (x) is a constant K (K ≧ 0) from the minimum value Pmin (x) of 3N measurement values Pz (1) to Pz (3N) at times tx−1, tx, and tx + 1. ) Minus the value.

Based on the standard deviation σx of NY (Y ≧ 2) measured values Pz (1) to Pz (NY) at a plurality of times including the time tx in the population, the setting unit 215 An upper limit value P _upper (x) at time tx may be set. At this time, the setting unit 215 performs NY (Y ≧ 3) measurement values Pz (3) at three or more times including the time tx and the times tx−1 and tx + 1 before and after the time tx in the population. The upper limit value P _upper (x) at time tx may be set based on the maximum value Pmax (x) of 1) to Pz (NY). For example, as illustrated in FIG. 8, the setting unit 215 may set an upper limit value P _upper (x) using Expression (7). In equation (7), P _upper (x) is an average value μx of N measurement values Px (1) to Px (N) at time tx, and 3N measurement values at time tx−1, tx, tx + 1. It is represented by a value obtained by adding K times (K ≧ 1) of the standard deviation σx of Pz (1) to Pz (NY).

Further, the setting unit 215 is based on the standard deviation σx of NY (Y ≧ 2) measured values Pz (1) to Pz (NY) at a plurality of times including the time tx in the population. Thus, the lower limit value P _lower (x) at time tx may be set. At this time, the setting unit 215 performs NY (Y ≧ 3) measurement values Pz (3) at three or more times including the time tx and the times tx−1 and tx + 1 before and after the time tx in the population. The lower limit value P _lower (x) at time tx may be set based on the standard deviation σx of 1) to Pz (NY). For example, as illustrated in FIG. 8, the setting unit 215 may set the lower limit value P _lower (x) using Expression (8). In Expression (8), P _lower (x) is 3N measurement values at time tx−1, tx, tx + 1 from the average value μx of N measurement values Px (1) to Px (N) at time tx. It is represented by a value obtained by subtracting K times (K ≧ 1) the standard deviation σx of Pz (1) to Pz (NY).

The setting unit 215 stores the upper limit value P _upper (x) and the lower limit value P _lower (x) derived as described above in the threshold file 22F of the storage unit 22. Thereafter, the setting unit 215 ends the threshold analysis in accordance with the setting start command Os.

(Teach pendant 30)
FIG. 9 illustrates an example of a schematic configuration of the teach pendant 30. The teach pendant 30 is for an operator to teach the operation of the manipulator 10. The teach pendant 30 includes, for example, a control unit 31, a display unit 32, an input unit 33, a communication unit 34, and a storage unit 35.

  The display unit 32 displays video based on the video signal. The display unit 32 includes a display panel having a display surface for displaying video and a drive unit for driving the display panel based on the video signal. The input unit 33 receives teaching from an operator. The input unit 33 has, for example, a plurality of keys, generates an input signal in response to an operation of each key, and outputs the input signal to the control unit 31. The communication unit 34 communicates with the robot control device 20 via the cable L2. The communication unit 34 is configured to transmit a work command from the control unit 31 to the robot control device 20. The storage unit 35 stores a teaching program 35A that enables various displays and work instructions in various modes. The teaching program 35A is stored in, for example, a ROM.

  The control unit 31 generates a video signal, outputs the video signal to the display unit 32, generates a work command as necessary, and outputs the work command to the communication unit 34. The control unit 31 generates a video signal in accordance with the read teaching program 35A, and generates a work command as necessary. For example, when the input signal input from the input unit 33 is a selection signal for a reproduction mode for performing a machining operation, the control unit 31 stores one or more stored in the storage unit 24 according to the teaching program 35A. A video signal for displaying a list of work programs 22B is generated. Furthermore, for example, when the reproduction mode is selected and one work program 22B to be reproduced is selected, the control unit 31 issues a work command including the number of the work program 22B to be reproduced according to the teaching program 35A. It is designed to generate. Further, for example, when the playback mode is selected and the learning mode or the abnormality determination mode is selected, the control unit 31 performs an operation including an instruction to start the learning mode or the abnormality determination mode according to the teaching program 35A. Directives are generated.

(Welder 40)
FIG. 10 illustrates an example of a schematic configuration of the welding machine 40. The welding machine 40 precisely controls the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the like based on the control by the robot controller 20, so that an arc is formed between the tip of the welding wire 15 and the workpiece W. Is generated. The welding machine 40 includes a control unit 41, a communication unit 42, a welding control unit 43, a welding power source 44, a current / voltage measurement unit 45, and a storage unit 46.

  The storage unit 46 stores a control program 46 </ b> A for controlling operations of the welding control unit 43 and the welding power source 44. The control program 46A is stored in ROM, for example. The control unit 41 controls each part of the welding machine 40 and controls operations of the welding control unit 43 and the welding power source 44 in accordance with the read control program 46A. The control unit 41 outputs monitor information (for example, various measurement values or notification information such as an arc occurrence notification) acquired from the current / voltage measurement unit 45 to the communication unit 42. The communication unit 42 receives a welding command from the robot control device 20 and outputs it to the control unit 41. The communication unit 42 outputs monitor information (for example, various measurement values or notification information) from the control unit 41 to the robot control device 20.

  The welding control unit 43 controls the operation of the wire feeding device 14 in accordance with an instruction from the control unit 41 based on the control program 46A and a welding command from the robot control device 20. The welding command from the robot controller 20 may include, for example, a wire feed start command, a wire feed stop command, and a set value of the wire feed speed Vf. Further, the welding control unit 43 measures the wire feeding speed Vf based on a pulse (or some signal in place of the above pulse) output from the motor of the wire feeding device 14. The welding control unit 43 measures the wire feeding load Ld based on the measured value of the drive current output from the ammeter of the wire feeding device 14. The welding control unit 43 outputs the measured values of the wire feeding speed Vf and the wire feeding load Ld to the control unit 41.

  The welding power source 44 has, for example, a digital inverter circuit, and performs a precise welding current waveform control with a high-speed response to a commercial power source (for example, three-phase 200 V) input from the outside by an inverter control circuit. . That is, the welding power source 44 supplies a high welding voltage Vs between the welding torch 13 and the workpiece W via the cables L5 and L6. The welding power source 44 controls the welding current Is and the welding voltage Vs in accordance with the control program 46A and a welding command from the robot controller 20. The welding command from the robot controller 20 may include, for example, an arc welding start command, an arc welding end command, a set value of the welding current Is, a set value of the welding voltage Vs, and the like.

  The current / voltage measuring unit 45 measures the welding current Is flowing between the welding torch 13 and the workpiece W and the welding voltage Vs between the welding torch 13 and the workpiece W. The current / voltage measuring unit 45 measures the welding current Is, the welding voltage Vs, and the short-circuit frequency fs at the sampling frequency Δfs according to the control program 46A and the welding command from the robot controller 20, and the welding current Is and the welding voltage Vs. The measurement values (various measurement values) of the short-circuit frequency fs are output to the control unit 41. The current / voltage measuring unit 45 measures the number of pulses per second (pulse frequency fp) during welding and outputs it to the control unit 41 as necessary. The current / voltage measuring unit 45 further determines whether or not arcing has occurred from the measured values of the welding current Is and the welding voltage Vs. The current / voltage measuring unit 45 generates an arc generation notification and outputs it to the control unit 41 when an arc occurs.

[Operation procedure in learning mode]
Next, an operation procedure in the learning mode will be described. In the following, the threshold generation will be described after the execution history accumulation has been described.

(Execution history accumulation)
First, the execution history accumulation in the learning mode will be described. In the teach pendant 30, the user selects, for example, a playback mode, and further selects a learning mode. Then, the control unit 31 of the teach pendant 30 generates a work command including a learning mode start command according to the teaching program 35 </ b> A and outputs the work command to the robot control device 20. When a work command including a learning mode start command is input from the teach pendant 30, the control unit 21 of the robot control device 20 reads the work program 22B and the arc welding quality determination program 22C. Based on the contents read from the work program 22B and the arc welding quality determination program 22C and the various setting values read from the setting file 22D of the storage unit 24, the control unit 21 commands corresponding to the instructions described in these programs. Generate a notification. The control unit 21 outputs a movement command and a welding command according to the content of the generated command notification.

  The control unit 21 outputs the generated welding command to the welding machine 40 via the communication unit 23. The welding command includes, for example, a welding start command and set values of a welding current Is, a welding voltage Vs, and a wire feed speed Vf. When a welding command is input from the robot controller 20, the control unit 41 of the welding machine 40 reads the control program 46A, sets the welding current Is and the welding voltage Vs in accordance with the welding command, and the wire feeding device. By setting the wire feed speed Vf to 14, arc welding is started. At this time, the current / voltage measurement unit 45 samples various physical quantities, and outputs measured values of various physical quantities obtained by the sampling to the control unit 41. Further, the current / voltage measuring unit 45 outputs an arc generation notification to the control unit 41 when the generation of the arc is detected. The control unit 41 outputs monitor information (for example, various measurement values or notification information such as an arc occurrence notification) acquired from the current / voltage measurement unit 45 to the robot control device 20 via the communication unit 42. For example, when a predetermined time interval (for example, about 10 ms minimum) is reached, the control unit 41 calculates a moving average value of various measurement values during that time, and outputs it to the robot control device 20 via the communication unit 42. .

  The control unit 21 further outputs the generated movement command to the manipulator 10 via the communication unit 23. When a movement command is input from the robot control device 20, the manipulator 10 displaces each arm 12 </ b> A according to the input movement command, and consequently moves the welding torch 13 up, down, front, back, left, and right. At this time, the control unit 21 acquires position information from the encoder.

  The control unit 21 stores various measurement values acquired from the welding machine 40 in the measurement file 22E of the storage unit 24. At this time, the control unit 21 may derive the welding start position or the welding start time based on the welding start command acquired from the welding machine 40 and store it in the measurement file 22E of the storage unit 24. The control unit 21 derives the welding speed Vw based on the position information Pf acquired from the encoder, and stores it in the measurement file 22E of the storage unit 24. The control unit 21 determines the end of the welding section WS based on the position information Pf acquired from the encoder. When the welding section WS is ended, a number for identifying the welding section WS is measured in the measurement file 22E of the storage unit 24. To store.

(Threshold generation)
Next, threshold value generation in the learning mode will be described. When the control unit 21 detects that the number of end times of the welding section WS has reached a predetermined number (N times), the control unit 21 determines a plurality of (N) measured values P _{1 to} P _N of a specific physical quantity, It acquires from the measurement file 22E of the memory | storage part 24 as a population. When the N measurement values P _{1 to} P _N (1 ≦ i ≦ N) of a specific physical quantity acquired from the measurement file 22E of the storage unit 24 are used as a population, the control unit 21 sets the time in the population. For each tx (1 ≦ x ≦ X), an upper limit value P _upper (x) at time tx is calculated based on a maximum value Pmax (x) of N measurement values Px (1) to Px (N) at time tx. Set. Further, the analysis unit 215 further sets a lower limit value at the time tx based on the minimum value Pmin (x) of the N measurement values Px (1) to Px (N) at the time tx for each time tx in the population. P _lower (x) is set. For example, the control unit 21 sets the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx by the specific method described above.

Note that the analysis unit 215 determines the _upper limit value P _upper (tupper time tx) at the time tx based on the standard deviation σx of the N measured values Px (1) to Px (N) at the time tx for each time tx in the population. x) may be set. Further, the analysis unit 215 further sets the _lower limit value P _lower (at the time tx) based on the standard deviation σx of the N measurement values Px (1) to Px (N) at the time tx for each time tx in the population. x) may be set. At this time, the control unit 21 may set the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx, for example, by the specific method described above.

In addition, the analysis unit 215 has a maximum value Pmax (x) of NY (Y ≧ 2) measured values Pz (1) to Pz (NY) at a plurality of times including the time tx in the population. ) May be set to an _upper limit value P _upper (x) at time tx. Further, the analysis unit 215 further includes, for each time tx, the NY (Y ≧ 2) measured values Pz (1) to Pz (NY) minimum values Pmin (x) at a plurality of times including the time tx in the population. ), A lower limit value P _lower (x) at time tx may be set. At this time, the control unit 21 may set the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx, for example, by the specific method described above.

Moreover, the analysis unit 215 is based on the standard deviation σx of NY (Y ≧ 2) measured values Pz (1) to Pz (NY) at a plurality of times including the time tx in the population. Thus, an upper limit value P _upper (x) at time tx may be set. Further, the analysis unit 215 is based on the standard deviation σx of NY (Y ≧ 2) measured values Pz (1) to Pz (NY) at a plurality of times including the time tx in the population. Thus, the lower limit value P _lower (x) at time tx may be set. At this time, the control unit 21 may set the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx, for example, by the specific method described above.

The analysis unit 215 stores the upper limit value P _upper (x) and the lower limit value P _lower (x) derived as described above in the threshold file 22F of the storage unit 22. In this way, the learning mode is executed.

[Configuration in error judgment mode]
Next, the configuration in the abnormality determination mode will be described.

  FIG. 11 illustrates an example of functional blocks in the abnormality determination mode of the welding robot system 1. The welding robot system 1 includes a determination unit 216 instead of the setting unit 215 in the learning mode in the abnormality determination mode. The determination unit 216 corresponds to a specific example of the “determination unit” of the present invention. Therefore, in the following, contents different from the learning mode will be mainly described, and contents common to the learning mode will be omitted as appropriate.

When the track recording unit 214 receives the track recording end notification from the welding control unit 213 in the abnormality determination mode, the track recording unit 214 outputs a determination start command Oh. The control unit 21 includes a determination unit 216 that performs abnormality determination according to the determination start command Oh (see FIG. 11). The determination unit 216 corresponds to a specific example of the “determination unit” of the present invention. When the determination unit 216 receives the determination start command Oh, the measured value P _{N + 1} obtained during welding under the same welding condition setting as that in the learning mode is the upper limit value P _upper (x) and the lower limit value P. When it is in the range of _lower (x), it is determined that there is no welding defect, and when the measured value P _{N + 1} is outside the above range, it is determined that there is a welding defect.

The determination unit 216 may determine that there is a welding failure when a predetermined number of measurement values Px (N + 1) included in the measurement value P _{N + 1} are outside the above range. That is, the determination unit 216 may determine that there is a welding defect when the number of times that the measured value Px (N + 1) is determined to be outside the above range exceeds a predetermined number.

  The determination unit 216 determines that the measured value Px (N + 1) is out of the above range even after a predetermined time (threshold deviation allowable time) has elapsed since it was determined that the measured value Px (N + 1) is out of the above range. Sometimes, it may be determined that there is a welding defect. Here, the determination unit 216 may derive the threshold deviation allowable time from the preset distance and the welding speed Vw.

  If the determination unit 216 determines that there is a welding failure, the determination unit 216 may instruct the robot control device 20 to immediately stop welding. In addition, when the determination unit 216 determines that there is a welding failure, the determination unit 216 may instruct the robot control device 20 to notify that there is a welding failure.

FIG. 12 shows an example of graphic display on the display surface of the teach pendant 30. Based on the video signal for displaying the monitoring information, the display unit 32 shows the relationship between the measured value P _{N + 1} and the welding distance Wp, for example, as shown in FIG. 12, an upper limit value P _upper (x). The lower limit value P _lower (x) is displayed as a graphic. From Figure 12, at the start arc welding, the range of the upper limit value P _upper (x) and lower limit value P _lower (x) is, in the arc stability during, the upper limit value P _upper (x) and the lower limit value P _lower of (x) It can be seen that it is slightly wider than the range.

[Quality judgment]
Next, an arc welding quality determination procedure in the welding robot system 1 will be described with reference to FIG. FIG. 12 shows an example of an arc welding quality determination procedure.

  First, the robot control device 20 (the control unit 21) outputs a welding command to the welding machine 40. Then, the welding machine 40 starts welding in accordance with an instruction from the control unit 21, samples the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the short-circuit frequency fs, and these measured values are controlled by the control unit. To 21. The control unit 21 acquires measured values of the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the short-circuit frequency fs from the welding machine 40.

  The control unit 21 also gives a movement command to the servo control unit 22. Then, the servo control unit 22 controls the operation of the manipulator 10 according to an instruction from the control unit 21, samples the position information from the encoder of the manipulator 10, and uses the position information obtained by the sampling to determine the tip of the welding torch 13. Position information Pf and welding speed Vw are derived (measured). The servo control unit 22 outputs the derived position information Pf and the welding speed Vw to the control unit 21. The control unit 21 acquires the measurement values of the position information Pf and the welding speed Vw from the control unit 21.

  Next, the control unit 21 determines whether or not the elapsed period from the start of measurement (or the start of recalculation) to the present exceeds the period (calculation period) necessary for calculating the moving average value. The calculation period is, for example, at least about 10 μs. When the elapsed period exceeds the calculation period, the control unit 21 calculates a moving average value of the welding current Is, the welding voltage Vs, the wire feeding speed Vf, the short-circuit frequency fs, and the welding speed Vw.

Next, the control unit 21 determines whether or not the calculated moving average value is in the range between the _upper limit value P _upper (x) and the lower limit value P _lower (x). The control unit 21 determines that there is no welding failure when the calculated moving average value is within the above range. When the calculated moving average value is outside the above range, the control unit 21 determines that there is a welding failure and ends the quality determination.

  When the control unit 21 determines that there is a welding defect, the control unit 21 does not end the quality determination (that is, does not stop the welding operation) and continues the quality determination while performing the welding operation to the end. Good. Further, the control unit 21 may start the determination as to whether or not the calculated moving average value is within the above range from the time when welding is started or after the end of welding.

[effect]
Next, the effect of the arc welding quality determination system in the welding robot system 1 will be described.

  Conventionally, techniques for reducing welding defects themselves and techniques for detecting welding defects more accurately have been developed. For example, Patent Literature 1 has been proposed as a technique for more accurately detecting poor welding. Patent Document 1 proposes a technique for determining that a welding failure has occurred when a moving average value of an actual welding current or welding voltage during arc welding deviates from a preset range. However, in the invention described in Patent Document 1, since the threshold value is a constant value based on the welding conditions (welding current, welding voltage, etc.) at the time of steady state, it is not in a steady state (for example, at the start of welding) Or at the end of welding, or when the welding conditions are changed intentionally).

On the other hand, in this embodiment, based on a statistical value obtained from a population including a plurality of past measurement values P _{1 to} P _N , a threshold (upper limit value P _upper (x ) And a lower limit value P _lower (x)) are set. As a result, the threshold values (upper limit value P _upper (x) and lower limit value P _lower (x)) used for the determination of poor welding are values obtained from accumulation of stable welding results performed in the past. As a result, even if the welding state is other than the steady state, the threshold value obtained under the same welding state in the past is used, so that it is possible to determine the welding failure.

In the present embodiment, in the population, for each time tx, based on the maximum value Pmax (x) and the minimum value Pmin (x) of N measurement values Px (1) to Px (N) at time tx. When the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx are set, the welding failure is determined with a small amount of calculation even in a welding state other than the steady state. Can do. In the present embodiment, in the population, for each time tx, NY (Y ≧ 2) measured values Pz (1) to Pz (NY) maximum values Pmax () at a plurality of times including time tx. x) When the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx are set based on the minimum value Pmin (x), even in a welding state other than the steady state, Therefore, it is possible to determine a welding defect with relatively little accuracy and with relatively high accuracy.

In the present embodiment, the _upper limit value P _upper (x _upper (x) at the time tx is determined based on the standard deviation σx of the N measurement values Px (1) to Px (N) at the time tx for each time tx in the population. ) And the lower limit value P _lower (x) are set, it is possible to accurately determine the welding failure even in the welding state other than the steady state. Further, in the present embodiment, in the population, for each time tx, the standard deviation σx of NY (Y ≧ 2) measured values Pz (1) to Pz (NY) at a plurality of times including the time tx. Based on this, when the upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx are set, the welding failure is more accurately determined even in the welding state other than the steady state. be able to.

In the present embodiment, for each time tx, the average value μx at time tx plus K times standard deviation σx at a plurality of times including time tx (K ≧ 1) in the above population. Is set to the _upper limit value P _upper (x), and a value obtained by subtracting K times (K ≧ 1) the standard deviation σx at a plurality of times including the time tx or the time tx from the average value μx at the time tx, When the lower limit value P _lower (x) at the time tx is set, it is possible to accurately determine the welding failure even in the welding state other than the steady state.

In the present embodiment, the closest measured value Px (i) (starting measured value) included in the acquired measured values P _{1 to} P _N is detected, and the measured values P ₁ to P N are detected. When the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx are set starting from the time of the start measurement value detected for each _PN , the welding start time varies. It is possible to reduce the erroneous determination caused.

  In the present embodiment, the welding current Is, the welding voltage Vs, the wire feed speed Vf, the welding speed Vw, or the short-circuit frequency fs are used as the measurement values used for determining the welding failure. Even in the state, it is possible to determine a welding failure. In the present embodiment, a measuring unit that measures the welding current Is, the welding voltage Vs, the wire feed speed Vf, the welding speed Vw, or the short-circuit frequency fs is provided, and the value measured by the measuring unit is Since it is used for determination of poor welding, it is possible to determine poor welding even in a welding state other than the steady state.

In the present embodiment, the relationship between the measured value Px (i) and the welding distance Wp is graphically displayed on the display unit 32 together with the _upper limit value P _upper (x) and the lower limit value P _lower (x). Even in this welding state, the user can intuitively confirm the determination result of poor welding.

<2. Modification>
Below, the modification of the welding robot system 1 of the said embodiment is demonstrated. In the following, components that are the same as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment. In addition, the description of the components different from the above embodiment will be mainly given, and the description of the components common to the above embodiments will be omitted as appropriate.

[Modification A]
In the above embodiment, the upper limit value P _upper (x) and the lower limit value P _lower (x) are set for each time tx (1 ≦ x ≦ X) defined by the sampling period Δt. However, in the above embodiment, the upper limit value P _upper (x) and the lower limit value P _lower (x) are set for each time tx (1 ≦ x ≦ X) defined by a cycle different from the sampling cycle Δt. Also good.

[Modification B]
In the above-described embodiment, for example, the setting values of the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the welding speed Vw are described in the setting file 22D. However, in the above-described embodiment and its modification, the setting file 22D may further describe the set values of the wire feed load Ld and the pulse frequency fp described above. At this time, the measurement values of the wire feeding load Ld and the pulse frequency fp are described in the measurement file 22E. The wire feeding load Ld is a physical quantity calculated from the motor current of the wire feeding device 14. The pulse frequency fp is the number of pulses per second during welding by the pulse welding method. In the present modification B, since the wire feed load Ld or the pulse frequency fp is used as the measurement value used for determining the welding failure, it is possible to determine the welding failure even in a welding state other than the steady state. . Moreover, in this modification B, the measurement part which measures the wire feed load Ld or the pulse frequency fp is provided, and since the value measured by the measurement part is used for determination of welding failure, it is other than the time of a steady state Even in this welding state, it is possible to determine a welding failure.

[Modification C]
In the above embodiment, the threshold file 22 </ b> F is stored in the storage unit 22 of the robot control device 20. However, in the above-described embodiment and modifications thereof, the threshold file 22F may be stored in a storage unit such as another hard disk connected to the robot control device 20 via a network, for example. However, in this case, the robot controller 20 stores the threshold file 22F in a storage unit such as another hard disk connected via a network, or the threshold file 22F from within a storage unit such as another hard disk connected via a network. Is read out.

[Modification D]
In the above embodiment, when the control unit 21 detects that the number of end of the welding section WS has reached a predetermined number (N times), the _upper limit value P _upper (x) and the lower limit value P _lower (x at time tx). ) Was generated. However, in the above-described embodiment and its modification, when the number of end of the welding section WS reaches a predetermined number (N times), the user gives a time tx to the robot control device 20 (control unit 21). The generation of the upper limit value P _upper (x) and the lower limit value P _lower (x) may be instructed.

DESCRIPTION OF SYMBOLS 1 ... Welding robot system, 10 ... Manipulator, 11 ... Base member, 12 ... Articulated arm part, 12A ... Arm, 13 ... Welding torch, 14 ... Welding wire, 15 ... Work table, 20 ... Robot controller, 21 ... Control Part 22 ... servo control part 22A ... control program 22B ... work program 22C ... arc welding quality determination program 22D ... setting file 22E ... measurement file 22F ... threshold file 23 ... communication part 30 ... teach pendant , 31 ... control section, 32 ... display section, 33 ... input section, 34 ... communication section, 35 ... storage section, 35A ... teaching program, 40 ... welding machine, 41 ... control section, 42 ... communication section, 43 ... welding control , 44 ... Welding power source, 45 ... Current / voltage measurement unit, 46 ... Storage unit, 46A ... Control program, 110 ... Base material, 120 ... Welding bee , 211 ... analyzing unit, 212 ... execution unit, 213 ... welding control unit, 214 ... track recording unit, 215 ... setting unit, 216 ... determination unit, At ... arc time, fp ... pulse frequency, Is ... welding current, L1 L6 ... Cable, Ld ... Wire feed load, Os ... Setting start command, Oh ... Determination start command, P _upper (x) ... Upper limit value, P _lower (x) ... Lower limit value, P _max (x) ... Maximum value, P _min (x): minimum value, P ₁ , P _i , P _N , Px (i-1), Px (i), Px (i + 1) ... measured value, Sn: number of short circuits, tx-1, tx, tx + 1 ... Time, Vf ... Wire feed speed, Vs ... Welding voltage, WS ... Welding section, W ... Workpiece, Δf ... Sampling frequency, Δt ... Sampling cycle, ΔT ... Unit time.

Claims (7)

When a plurality of measurement values obtained when welding is repeatedly performed under a common welding condition setting is used as a population, the first time or the first time in the population at each first time. An upper limit value at the first time is set based on a maximum value at a plurality of times including one time, and the first value is set based on a minimum value at a plurality of times including the first time or the first time. A setting unit for setting a lower limit value at the time of 1;
When the measured value obtained during welding under the welding condition setting is in the range between the upper limit value and the lower limit value, it is determined that there is no welding failure, and when the measured value is out of the range, there is a welding failure. An arc welding quality judgment system comprising: a judgment unit for judging. When a plurality of measurement values obtained when welding is repeatedly performed under a common welding condition setting is used as a population, the first time or the first time in the population at each first time. A setting unit configured to set an upper limit value and a lower limit value at the first time based on standard deviations at a plurality of times including one time;
When the measured value obtained during welding under the welding condition setting is in the range between the upper limit value and the lower limit value, it is determined that there is no welding failure, and when the measured value is out of the range, there is a welding failure. An arc welding quality judgment system comprising: a judgment unit for judging. In the population, for each of the first times, the setting unit has a positive value of a standard deviation at a plurality of times including the first time or the first time to an average value at the first time. A value obtained by adding an integer multiple is set as the upper limit value at the first time,
In the population, for each of the first times, the setting unit is configured to obtain a positive standard deviation at a plurality of times including the first time or the first time from an average value at the first time. The arc welding quality determination system according to claim 2, wherein a value obtained by subtracting an integer multiple is set as a lower limit value at the first time. The setting unit detects a start measurement value closest to the welding start position or welding start included in each measurement value, and starts the measurement value detected for each measurement value as a starting point. The arc welding quality determination system according to any one of claims 1 to 3, wherein the lower limit value is set. The plurality of measurement values are welding current, welding voltage, wire feeding speed, welding speed, wire feeding load, short-circuit frequency, or pulse frequency. Arc welding quality judgment system. The arc welding according to claim 5, further comprising a measuring unit that measures the welding current, the welding voltage, the wire feeding speed, the welding speed, the wire feeding load, the short-circuit frequency, or the pulse frequency. Quality judgment system. The arc welding quality determination system according to any one of claims 1 to 6, further comprising a display unit that graphically displays the relationship between the measured value and the welding distance together with the upper limit value and the lower limit value.

Images