TWI689369B - Arc welding quality determination system - Google Patents

Abstract

An arc welding quality determination system includes a setting section and a determining section. The setting section sets an upper limit and a lower limit for a first time. The upper limit is derived based on a maximum value. The maximum value is derived from a predetermined population, and corresponds to one of the first time and a plurality of times that include the first time. The lower limit is derived based on a minimum value. The minimum value is derived from the predetermined population, and corresponds to one of the first time and the plurality of times. The determining section determines non-failure of welding on condition that a measurement value obtained upon the welding falls within a range from the upper limit to the lower limit, and determine failure of the welding on condition that the measurement value falls outside the range.

Description

Arc welding quality judgment system

The invention relates to an arc welding quality judgment system.

At the production site where welding robots are used, as one of the main factors hindering stable production, poor welding can be cited. One type of insufficient weld bead formation may be caused by, for example, the following reasons. For example, even if the welding conditions are set in advance so as to form an appropriate bead shape for the workpiece to be constructed, the length of the workpiece may fluctuate due to the positional deviation of the workpiece during actual construction. In this case, the welding current fluctuates along with the fluctuation of the protruding length, and as a result, insufficient formation of the weld bead may occur. In addition, for example, the wear of the contact piece that supplies power to the welding wire may cause a power shortage due to the wear of the contact piece. In this case, the welding current is reduced due to insufficient power supply, and as a result, insufficient weld bead formation may occur. In addition, for example, in the wire feeder, clogging of welding wire chips may occur. In this case, the arc interruption occurs due to poor wire feeding, and as a result, a weld bead formation defect such as a weld bead gap may occur.

Therefore, techniques for reducing welding defects and techniques for more accurately detecting welding defects have been developed in the past. As a technique for more accurately detecting welding defects, for example, the following Patent Document 1 is proposed. Patent Document 1 proposes a technique for determining that a welding defect has occurred if the moving average value of the actual welding current or welding voltage during arc welding exceeds a predetermined range.

[Prior Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 7-2275

However, in the invention described in the above-mentioned Patent Document 1, since the threshold value is a fixed value based on the welding conditions (welding current, welding voltage, etc.) at the time of stability, the state at the time of instability (for example, welding start, welding At the end or when the welding conditions are deliberately changed, etc.), there is a problem that the welding failure cannot be determined.

Therefore, it is desirable to provide an arc welding quality determination system that can determine welding defects even in welding other than stable time.

A first arc welding quality judgment system according to an embodiment of the present invention includes: a setting unit that uses a plurality of measured values obtained when welding is repeatedly performed under common welding condition settings as a parent group. At the first time, the upper limit of the first time is set according to the maximum value of the first time or the plurality of times including the first time, and the first time is set according to the minimum value of the first time or the plurality of times including the first time The lower limit; and the determination section, when the measured value obtained during welding under the above welding condition setting is within the range of the upper limit and the lower limit, it is determined that there is no welding defect, and when the measured value is outside the range , It is determined that there is welding failure.

A second arc welding quality judgment system according to an embodiment of the present invention includes: a setting unit that uses a plurality of measured values obtained when welding is repeatedly performed under common welding condition settings as a parent group, in the parent group, for each At the first moment, the upper limit and the lower limit of the first moment are set according to the standard deviation of the first moment or a plurality of moments including the first moment; and The fixed part determines that there is no welding defect when the measured value obtained during welding under the above welding conditions is within the range of the upper limit and the lower limit, and when the measured value is outside the range, it is determined that there is welding defect .

In the first and second arc welding quality judgment systems according to an embodiment of the present invention, a threshold for judging welding failure is set based on statistical values obtained from a parent group including a plurality of measured values in the past. Therefore, the threshold for determining welding failure becomes a value reflecting the stability of welding.

According to the first and second arc welding quality determination systems according to an embodiment of the present invention, since the threshold for determining welding failure becomes a value reflecting welding stability, welding failure can be determined even in welding other than stable.

1: Welding robot system

10: Manipulator

11: Basic components

12: Multi-joint arm

12A: Arm

13: Welding torch

14: Wire feeder

15: Workbench

20: Robot control device

21: Control Department

22: Servo control department

22A: Control program

22B: Operating program

22C‧‧‧Arc welding quality judgment program

22D‧‧‧Setting file

22E‧‧‧Measurement file

22F‧‧‧threshold file

23‧‧‧ Ministry of Communications

30‧‧‧Teaching device

31‧‧‧Control Department

32‧‧‧Display

33‧‧‧ Input

34‧‧‧Ministry of Communications

35‧‧‧Storage Department

35A‧‧‧Instruction program

40‧‧‧Welding machine

41‧‧‧Control Department

42‧‧‧Communications Department

43‧‧‧Welding Control Department

44‧‧‧Welding power supply

45‧‧‧ current Voltage measurement department

46‧‧‧Storage Department

46A‧‧‧Control program

110‧‧‧ base material

120‧‧‧Weld pass

211‧‧‧Analysis Department

212‧‧‧ Executive Department

213‧‧‧Welding Control Department

214‧‧‧Track Recording Department

215‧‧‧ Setting Department

216‧‧‧Judgment Department

At‧‧‧Arc starting time

fp‧‧‧Pulse frequency

Is‧‧‧welding current

L1~L6‧‧‧Cable

Ld‧‧‧Wire feeding load

Os‧‧‧Set start command

Oh‧‧‧decision start instruction

P _upper (x)‧‧‧ Upper limit

P _lower (x)‧‧‧lower limit

Pmax(x)‧‧‧Max

Pmin(x)‧‧‧Min

P ₁ , P _N , Px‧‧‧ measured value

tx-1,tx,tx+1‧‧‧

Vf‧‧‧Wire feeding speed

Vs‧‧‧welding voltage

Vw‧‧‧ welding speed

WS‧‧‧Welding interval

W‧‧‧Workpiece

△fs‧‧‧Sampling frequency

△t‧‧‧sampling period

△T‧‧‧ unit time

FIG. 1 is a diagram showing an example of a schematic structure of a welding robot system provided with an arc welding quality determination system according to an embodiment of the present invention.

[Fig. 2] Fig. 2 is a diagram showing an example of functional blocks of the learning mode of the welding robot system of Fig. 1.

[Fig. 3] A diagram showing an example of a schematic structure of the robot control device of Fig. 1.

[Fig. 4A] Fig. 4A is a perspective view showing an example of the state of arc welding using the welding robot system of Fig. 1.

4B is a diagram showing an example of the relationship between each track m, unit time ΔT, and setting start command when the welding section of FIG. 4A is divided into a plurality of tracks.

[Fig. 5] A diagram showing an example of a method of setting a threshold.

6 is a diagram showing an example of a method of setting a threshold.

7 is a diagram showing an example of a method of setting a threshold.

[Fig. 8] A diagram showing an example of a method of setting a threshold.

[Fig. 9] A diagram showing an example of a schematic structure of the teaching device of Fig. 1.

[Fig. 10] A diagram showing an example of a schematic structure of the welding machine of Fig. 1.

[Fig. 11] Fig. 11 is a diagram showing an example of function blocks in the abnormality determination mode of the welding robot system of Fig. 1.

FIG. 12 is a diagram showing an example of graphic display on the display surface of the teaching device of FIG. 11.

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

[structure]

FIG. 1 shows an example of a schematic structure of a welding robot system 1 provided with 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. 1. The welding robot system 1 has two modes: a learning mode and an abnormality determination mode.

The welding robot system 1 initially performs a plurality of arc welding (N times) under the same setting conditions in the learning mode to grasp the characteristics of the arc. The welding robot system 1 then switches from the learning mode to the abnormality determination mode, and performs arc welding under the same setting conditions as in the learning mode, by performing the arc characteristic obtained in the learning mode and the arc characteristic obtained in the abnormality determination mode In contrast, to determine the state of the weld bead formed. Furthermore, the setting conditions refer to the setting conditions when forming the weld bead.

That is, the "learning mode" means: by performing arc welding multiple times under the same setting conditions as the setting conditions when forming the weld bead in the abnormality determination mode, the determination is made In the abnormality determination mode, the state of the predetermined determination criterion in the state of the weld bead formed. In addition, the “abnormality determination mode” refers to a mode for determining the state of the weld bead formed in the abnormality determination mode using predetermined determination criteria acquired in the learning mode. In the following, the structure related to the learning mode will be described first, and then the structure related to the abnormality determination mode will be described.

[Structure of Learning Mode]

The welding robot system 1 performs arc welding on the workpiece W by a multi-joint robot controlled by a program. The welding robot system 1 includes a manipulator 10, a robot control device 20, a teaching device 30, and a welding machine 40. The system composed of the robot control device 20, the teaching device 30, and the welding machine 40 corresponds to a specific example of the "arc welding quality judgment system" of the present invention. Furthermore, the robot control device 20 and the teaching device 30 may be integrally formed with each other, or may be separately formed as shown in FIG. 1.

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 used for communication between the robot controller 20 and the manipulator 10, and is connected to the robot controller 20 and the manipulator 10. The cable L2 is a communication cable used for communication between the robot control device 20 and the teaching device 30, and is connected to the robot control device 20 and the teaching device 30. The cable L3 is a communication cable used for communication between the robot controller 20 and the welding machine 40, and is connected to the robot controller 20 and the welding machine 40. The cable L4 is a communication cable used for communication between the welding machine 40 and the wire feeder 14 described later, and is connected to the welding machine 40 and the wire feeder 14. The cables L5 and L6 are power cables for supplying a high-voltage welding voltage Vs between the welding wire 16 and the workpiece W described later. The cable L5 is connected to the welding machine 40 and the workbench 15 described later, and the cable L6 is connected to the welding machine 40 and the welding gun 13 described later.

(Manipulator 10)

The manipulator 10 performs arc welding on the workpiece W by the control of the robot control device 20, the teaching device 30, and the welding machine 40. The manipulator 10 includes a base member 11 fixed on the floor or the like, a multi-joint arm 12 provided on the base member 11, a welding gun 13 connected to the front end of the multi-joint arm 12, a multi-joint arm 12 fixed on the The wire feeder 14 and the workbench 15.

The multi-joint arm portion 12 includes, for example, plural arms 12A, and one or plural joint shafts (not shown) that rotatably connect the two arms 12A to each other. The multi-joint arm portion 12 further includes, for example, one drive motor (not shown) provided on each arm 12A and driving the corresponding arm 12A, connected to each drive motor, and detecting the current position of each arm 12A Encoder (not shown). Each drive motor is driven by a control signal input from the robot control device 20 through the cable L1. By driving each driving motor in this way, each arm 12A is displaced, and as a result, the welding gun 13 moves up, down, left, and right. The encoder outputs the detected current position of each arm 12A (hereinafter referred to as “position information”) to the robot control device 20 through the cable L1.

One end (front end) of the multi-joint arm 12 is connected to the welding gun 13, and the other end of the multi-joint arm 12 is connected to the base member 11. At the tip of the soldering gun 13, a solder wire 16 as solder is exposed. The welding gun 13 generates an arc between the tip of the welding wire 16 and the workpiece W, and melts the welding wire 16 and the workpiece W by the heat of the arc to perform arc welding on the workpiece W. The welding gun 13 has a contact piece (not shown) electrically connected to the cable L4. The contact piece is configured to supply the welding voltage Vs supplied from the cable L4 to the welding wire 16.

The wire feeder 14 supplies the welding wire 16 to the welding gun 13. The wire feeder 14 includes, for example, a pair of rollers (not shown) configured to hold and transfer the welding wire 16 and a motor (not shown) that rotationally drives one of the rollers. A pair of rollers are configured to hold the welding wire 16 and use the above The frictional force generated by the rotational drive of the motor pulls the welding wire 16 out of the wire reel (not shown). The above-mentioned motor is composed of, for example, a servo motor with an encoder. The motor is driven by a control signal input from the welding machine 40 through the cable L4. The motor is configured, for example, to output the pulse fed back from the encoder to the welding machine 40 through the cable L4. This pulse can be applied to the calculation of the transmission speed (wire feed speed Vf) of the welding wire 16. Furthermore, the motor can also generate some kind of signal output 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 applied to the calculation of the transmission load (wire feed load Ld) of the welding wire 16.

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 also be a positioner for maintaining an optimal welding gun posture to the workpiece W. When the workbench 15 is the above-mentioned positioner, the robot controller 20 drives and controls the axis of the positioner. The working table 15 is configured to be connected to the welding machine 40 via a cable L5, and electrically connect the work W provided on the working table 15 and the cable L5 to each other.

(Robot control device 20)

FIG. 3 shows an example of a schematic structure of the robot control device 20. The robot control device 20 controls the multi-joint arm 12 and the welding machine 40 in accordance with instructions from the teaching device 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 16 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. Hereinafter, the storage unit 24, the servo control unit 22, the communication unit 23, and the control unit 21 will be described in this order. The control unit 21 corresponds to a specific example of the “setting unit” and the “determination unit” of the present invention.

The storage unit 24 can store various programs and various data files. Storage 24 There is a control program 22A for controlling the operation of the multi-joint arm 12. The control program 22A is stored in a ROM (read only memory), for example. The storage unit 24 further stores one or more operation programs 22B that teach the steps of the welding operation of the manipulator 10, an arc welding quality determination program 22C that determines the quality of the weld bead, and a setting file 22D in which various settings are written. One or a plurality of operation programs 22B, an arc welding quality judgment program 22C and a setting file 22D are stored in the hard disk, for example. The setting file 22D describes, for example, respective setting values of the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the welding speed Vw. The arc welding quality judgment program 22C will be described in detail later. The steps of the welding operation described in one or a plurality of operation programs 22B, and various setting values described in the setting file 22D correspond to a specific example of the “welding conditions” of the present invention.

The storage section 24 may further store various data generated by executing the arc welding quality judgment program 22C. As a file containing such data, for example, a measurement file 22E and a threshold file 22F can be cited. In the measurement file 22E, the measured values of various physical quantities are described. Here, although the measured value may be an instantaneous value, in view of the ease of setting the threshold, the moving average value is preferable. Various physical quantities include, for example, welding current Is, welding voltage Vs, wire feed speed Vf, welding speed Vw, and short-circuit frequency fs. In addition, the short-circuit frequency fs is the number of short-circuits between the welding wire 16 and the workpiece W per second during welding. In the measurement file 22E, there are described measurement values of various physical quantities obtained by measurement with the sampling frequency Δfs. In the threshold file 22F, for example, an _upper limit value P _upper (x) and a lower limit value P _lower (x) generated by a setting unit 215 described later are described. These files are stored in RAM (Random Access Memory), for example. The upper limit P _upper (x) and the lower limit 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 the position of the encoder from the manipulator 10 based on the movement command described in the operation program 22B Set the information to control each drive motor of the manipulator 10. The movement command may include, for example, a movement start command, a movement stop command, a work path (indicating point), a welding gun posture, and the like. Furthermore, the servo control unit 22 derives (measures) the position information Pf of the tip of the welding gun 13 and the welding speed Vw based on the position information of the encoder from 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 teaching device 30 via the cable L2 and communicates with the welding machine 40 via the cable L3. The communication unit 23 receives the work instruction from the teaching device 30 and outputs it to the control unit 21. The operation command may include, for example, the number of the operation program 22B selected by the operator.

The communication unit 23 transmits the welding command from the control unit 21 to the welding machine 40. The welding command may include, for example, a start command of arc welding, an end command of arc welding, a set value of welding current Is, a set value of welding voltage Vs, a start command of wire feed, a stop command of wire feed, and a wire feed speed Vf Set value, etc. The communication unit 23 receives the monitoring information (such as various measured values or notification information) from the welding machine 40 and stores it in the measurement file 22E of the storage unit 24. The communication unit 23 further outputs notification information from the welding machine 40 to the control unit 21 as necessary. The various measured values include, for example, the measured values of the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the short-circuit frequency fs. The notification information may include, for example, an arc occurrence notification.

The control unit 21 includes an analysis unit 211 (refer to FIG. 2) that reads the operation program 22B and the arc welding quality judgment program 22C based on the operation command input from the teaching device 30 and analyzes the content. The analysis unit 211 generates command notifications corresponding to the instructions described in these programs based on the results of the analysis by the analysis unit 211. The control unit 21 includes an execution unit 212 (see FIG. 2) that outputs a movement command and a welding command based on the content of the command notification generated by the analysis unit 211.

The control unit 21 has a welding command generated by the execution unit 212 and is output to the welding control unit 213 of the welding machine 40 via the communication unit 23 (see FIG. 2 ). For example, if the welding control unit 213 generates a welding command in the execution unit 212, it generates a notification to start track recording at the tip of the welding gun 13 (track recording start notification). In addition, the welding control unit 213 generates, for example, a notification of ending track recording at the tip of the welding gun 13 (notification of track recording) based on the movement distance Δdist (=welding distance Wp) of the tip of the welding gun 13. The moving distance Δdist is derived from the track recording unit 214 (see FIG. 2) described later.

The control unit 21 includes a track recording unit 214 (see FIG. 2) that starts track recording at the tip of the welding gun 13 in accordance with the track recording start notification from the welding control unit 213. The trajectory recording unit 214 records the position information Pf of the tip of the welding gun 13 in the welding interval WS per unit time ΔT, and calculates and records the movement distance Δdist of the tip of the welding gun 13 per unit time ΔT. The moving distance Δdist is obtained, for example, by obtaining the difference between the latest position information Pf and the position information Pf before the unit time ΔT. In addition, the track recording unit 214 may derive the moving distance Δdist (=welding distance Wp) by “welding speed Vw×arc start time At”. The arc starting time At corresponds to the time after receiving the notification of the occurrence of the arc.

m

M)時，各個軌道m與單位時間△T的關係之一例。在圖4A中，表示：作為工件W，2片母材110以互相正交的方式，2張母材110的端部彼此互相接觸。在圖4A中，例示有所謂邊角焊的狀況。再者，焊接機器人系統1的用途不限定於邊角焊，可以用於其他方式的焊接。 Here, the welding section WS, the unit time ΔT, and the track m will be described. FIG. 4A shows an example of the state of arc welding using the welding robot system 1. Fig. 4B shows that the welding interval WS is divided into plural (M) tracks m(1

m

M), an example of the relationship between each track m and unit time ΔT. FIG. 4A shows that as the workpiece W, the two base materials 110 are orthogonal to each other, and the ends of the two base materials 110 are in contact with each other. In FIG. 4A, the situation of so-called fillet welding is exemplified. Furthermore, the use of the welding robot system 1 is not limited to fillet welding, and can be used for welding in other ways.

The welding section WS represents the section of the welding line from the start of arc welding to the end of arc welding. The weld bead 120 is formed in all or part of the welding interval WS. The welding section WS is divided into M tracks m, and the time required for the tip of the welding gun 13 to move on each track m is the unit time ΔT. After receiving the N-th track recording end notification from the welding control unit 213, the track recording unit 214 outputs a setting start instruction Os. Furthermore, the sampling period Δt in FIG. 4B is the reciprocal of the sampling frequency Δfs.

The control unit 21 includes a setting unit 215 (refer to FIG. 2) for setting according to the setting start command Os. The setting unit 215 corresponds to a specific example of the “setting unit” of the present invention. After receiving the setting start instruction Os, the setting unit 215 obtains a plurality of (N) measured values P ₁ to P _{N of the} specific physical quantity from the measurement file 22E of the storage unit 24 as the parent group. The specific physical quantity is, for example, a physical quantity preset by the user, and is, for example, at least one of welding current Is, welding voltage Vs, wire feed speed Vf, welding speed Vw, and short-circuit frequency fs.

The control unit 21 may detect the measured value Px(i) (measured value at the start) which is the closest to the welding start position or the welding start included in the acquired measured values P ₁ to P _N. In this case, the control unit 21 may set the _upper limit value P _upper of the time tx specified by the sampling period Δt using the time of the start measurement value detected for each measurement value P ₁ to P _N as a starting point (x) and P _lower (x). The control unit 21 may also detect, from the welding start position or the welding start time stored in the measurement file 22E stored in the storage unit 24, the welding start position or the welding start time included in each acquired measurement value P ₁ to P _N , for example. The most recent measured value Px(i) (measured value at the beginning). The control unit 21 may, for example, detect the measurement closest to the welding start position or the welding start included in the acquired measurement values P ₁ to P _N based on the characteristics of the time change of the acquired measurement values P ₁ to P _N Value Px(i) (measured value at the beginning).

i

N)作為母集團時，在該母集團中，於每個以採樣周期△t規定的時刻tx(1

x

X)，根據時刻tx的N個測量值Px(1)~Px(N)之最大值Pmax(x)，設定時刻tx之上限值P_upper(x)。設定部215如圖5所示，使用式(1)設定P_upper(x)。在式(1)中，P_upper(x)用時刻tx的N個測量值Px(1)~Px(N)之最大值Pmax(x)加上常數K(K

0)的值表示。 The setting unit 215 sets N measurement values P ₁ to P _N (1 of the specific physical quantity obtained from the measurement file 22E of the storage unit 24 (1

i

N) as the parent group, in the parent group, at each time tx(1

x

X), based on the N measured values Px(1)~Px(N) maximum value Pmax(x) at time tx, set the _upper limit P _upper (x) at time tx. As shown in FIG. 5, the setting unit 215 sets P _upper (x) using equation (1). In equation (1), P _upper (x) uses the maximum value Pmax(x) of N measured values Px(1)~Px(N) at time tx plus a constant K(K

The value 0) indicates.

In addition, the setting unit 215 may set P _upper (x) using, for example, the following formula. In the following formula, P _upper (x) uses the maximum value Pmax(x) of the N measured values Px(1)~Px(N) at the time tx plus a constant K, and the N measured values Px(t) representing each time tx 1) A value of L times the absolute value (|△μx|) of the differential value of the average value μx in the function of the average value μx of Px(N) μx.

P _upper (x)=Pmax(x)+K+L|△μx|

△μx=(μx-μx-1)/(tx-tx-1)

0)的值表示。 The setting unit 215 further sets the _lower limit P _lower at the time tx based on the N measured values Px(1) to Px(N) minimum values Pmin(x) at the time tx in the above parent group (x). As shown in FIG. 5, the setting unit 215 sets P _lower (x) using equation (2). In equation (2), P _lower (x) uses the minimum value Pmin(x) of the N measured values Px(1)~Px(N) at time tx minus the constant K(K

The value 0) indicates.

In addition, the setting unit 215 may also set P _lower (x) using the following formula, for example. In the following formula, P _lower (x) is represented by the value of the minimum value Pmin(x) of the N measured values Px(1)~Px(N) at time tx minus the constants K and L|△μx|.

P _lower (x)=Pmin(x)-KL|△μx|

1)的值設定為時刻tx之上限值P_upper(x)。 The setting unit 215 may set the _upper limit P _upper (x at the time tx based on the standard deviation σx of the N measured values Px(1) to Px(N) at the time tx in the parent group at each time tx ). As shown in FIG. 6, the setting unit 215 may set the upper limit value P _upper (x) using equation (3). Specifically, the setting unit 215 may add the average value μx of the N measurement values Px(1) to Px(N) at the time tx to the N measurements at the time tx in the parent group at each time tx Value Px(1)~K times the standard deviation σx of Px(N) (K

The value of 1) is set to the _upper limit P _upper (x) at time tx.

1)的值設定為時刻tx之下限值P_lower(x)。 The setting unit 215 may further set the _lower limit value P _lower ( _{t lower} (p _lower () at the time tx based on the standard deviation σx of the N measured values Px(1) to Px(N) at the time tx at each time tx x). As shown in FIG. 6, the setting unit 215 may set the lower limit value P _lower (x) using equation (4). Specifically, the setting unit 215 may subtract the N measurements at the time tx from the average μx of the N measured values Px(1) to Px(N) at the time tx in the above parent group at each time tx Value Px(1)~K times the standard deviation σx of Px(N) (K

The value of 1) is set to the _lower limit P _lower (x) at time tx.

2)測量值Pz(1)~Pz(NY)之最大值Pmax(x)，設定時刻tx之上限值P_upper(x)。此時，設定部215亦可以在上述母集團中，於每個時刻tx，根據包含時刻tx及其前後的時刻tx-1、tx+1的3個以上的時刻的NY個(Y

3)測量值Pz(1)~Pz(NY)之最大值Pmax(x)，設定時刻tx之上限值P_upper(x)。設定部215亦可以如圖7所示，使用式(5)設定P_upper(x)。在式(5)中，P_upper(x)用時刻tx-1、tx、tx+1的3N 個測量值Pz(1)~Pz(3N)之最大值Pmax(x)加上常數K(K

0)的值表示。3N個測量值Pz(1)~Pz(3N)係N個測量值Px-1(1)~Px-1(N)、N個測量值Px(1)~Px(N)和N個測量值Px+1(1)~Px+1(N)。 The setting unit 215 may, in the above parent group, at each time tx, based on a plurality of NY (Y

2) The maximum value Pmax(x) of the measured value Pz(1)~Pz(NY) and the _upper limit P _upper (x) of the set time tx. At this time, the setting unit 215 may, in the above parent group, at each time tx, according to NY (Y of three or more times including the time tx and the time tx-1 and tx+1 before and after it)

3) The maximum value Pmax(x) of the measured value Pz(1)~Pz(NY) and the _upper limit P _upper (x) of the set time tx. As shown in FIG. 7, the setting unit 215 may set P _upper (x) using equation (5). In equation (5), P _upper (x) uses the maximum value Pmax(x) of 3N measured values Pz(1)~Pz(3N) at times tx-1, tx, tx+1 plus the constant K(K

The value 0) indicates. 3N measured values Pz(1)~Pz(3N) are N measured values Px-1(1)~Px-1(N), N measured values Px(1)~Px(N) and N measured values Px+1(1)~Px+1(N).

2)測量值Pz(1)~Pz(NY)之最小值Pmin(x)，設定時刻tx之下限值P_lower(x)。此時，設定部215亦可以在上述母集團中，於每個時刻tx，根據包含時刻tx及其前後的時刻tx-1、tx+1的3個以上的時刻的NY個(Y

3)測量值Pz(1)~Pz(NY)之最小值Pmin(x)，設定時刻tx之下限值P_lower(x)。設定部215亦可以如圖7所示，使用式(6)設定P_lower(x)。在式(6)中，P_lower(x)用時刻tx-1、tx、tx+1的3N個測量值Pz(1)~Pz(3N)之最小值Pmin(x)減去常數K(K

0)的值表示。 The setting unit 215 may further, in each of the above parent groups, at each time tx, based on a plurality of NY (Y

2) The minimum value Pmin(x) of the measured value Pz(1)~Pz(NY) and the _lower limit P _lower (x) at the set time tx. At this time, the setting unit 215 may, in the above parent group, at each time tx, according to NY (Y of three or more times including the time tx and the time tx-1 and tx+1 before and after it)

3) The minimum value Pmin(x) of the measured value Pz(1)~Pz(NY) and the _lower limit P _lower (x) at the set time tx. As shown in FIG. 7, the setting unit 215 may set P _lower (x) using equation (6). In equation (6), P _lower (x) subtracts the constant K(K

The value 0) indicates.

2)測量值Pz(1)~Pz(NY)的標準差σx，設定時刻tx之上限值P_upper(x)。此時，設定部215亦可以在上述母集團中，於每個時刻tx，根據包含時刻tx及其前後的時刻tx-1、tx+1的3個以上的時刻的NY個(Y

3)測量值Pz(1)~Pz(NY)之最大值Pmax(x)，設定時刻tx之上限值P_upper(x)。設定部215亦可以如圖8所示，使用式(7)設定上限值P_upper(x)。在式(7)中，P_upper(x)用時刻tx的N個測量值Px(1)~Px(N)的平均值μx加上時刻tx-1、tx、tx+1的3N個測量值Pz(1)~Pz(NY)的標準差σx的K倍(K

1)的值表示。 The setting unit 215 may, in the above parent group, at each time tx, based on a plurality of NY (Y

2) The standard deviation σx of the measured values Pz(1)~Pz(NY), the _upper limit P _upper (x) at the set time tx. At this time, the setting unit 215 may, in the above parent group, at each time tx, according to NY (Y of three or more times including the time tx and the time tx-1 and tx+1 before and after it)

3) The maximum value Pmax(x) of the measured value Pz(1)~Pz(NY) and the _upper limit P _upper (x) of the set time tx. As shown in FIG. 8, the setting unit 215 may set the upper limit value P _upper (x) using equation (7). In equation (7), P _upper (x) uses the N measured values at the time tx Px(1)~Px(N) average μx plus 3N measured values at the time tx-1, tx, tx+1 Pz(1)~K times the standard deviation σx of Pz(NY) (K

1) The value indicated.

2)測量值Pz(1)~Pz(NY)的標準差σx，設定時刻tx之下限值P_lower(x)。此時，設定部215亦可以在上述母集團中，於每個時刻tx，根據包含時刻tx及其前後的時刻tx-1、tx+1的3個以上的時刻的NY個(Y

3)測量值Pz(1)~Pz(NY)的標準差σx，設定時刻tx之下限值P_lower(x)。設定部215亦可以如圖8所示，使用式(8)設定下限值P_lower(x)。在式(8)中，P_lower(x)用時刻tx的N個測量值Px(1)~Px(N)的平均值μx減去時刻tx-1、tx、tx+1的3N個測量值Pz(1)~Pz(NY)的標準差σx的K倍(K

1)的值表示。 The setting unit 215 may further, in the above parent group, at each time tx, based on NY (Y

2) The standard deviation σx of the measured values Pz(1)~Pz(NY) sets the _lower limit P _lower (x) at the time tx. At this time, the setting unit 215 may, in the above parent group, at each time tx, according to NY (Y of three or more times including the time tx and the time tx-1 and tx+1 before and after it)

3) The standard deviation σx of the measured values Pz(1)~Pz(NY) sets the _lower limit P _lower (x) at the time tx. As shown in FIG. 8, the setting unit 215 may set the lower limit value P _lower (x) using equation (8). In equation (8), P _lower (x) uses the average value of N measured values at time tx Px(1)~Px(N) μx minus 3N measured values at time tx-1, tx, tx+1 Pz(1)~K times the standard deviation σx of Pz(NY) (K

1) The value indicated.

The setting unit 215 stores the _upper limit value P _upper (x) and the lower limit value P _lower (x) derived in the manner described above in the threshold file 22F of the storage unit 24. Thereafter, the setting unit 215 ends the execution of the threshold value analysis in accordance with the setting start instruction Os.

(Teaching device 30)

FIG. 9 shows an example of a schematic structure of the teaching device 30. The teaching device 30 is a device in which the operator instructs the operation of the manipulator 10. The teaching device 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 animation based on the animation signal. The display unit 32 includes a display panel having a display surface that displays animation, and a drive unit that drives the display panel based on the animation signal. The input unit 33 accepts instructions from the operator. The input unit 33 has, for example, a plurality of keys, and generates an input signal corresponding to the operation of each key, and outputs it to the control unit 31. The communication unit 34 communicates with the robot control device 20 via the cable L2. The communication unit 34 transmits the work instruction from the control unit 31 to the robot control device 20. The storage unit 35 stores an instruction program 35A that can perform various indications and operation instructions in various modes. The instruction program 35A is stored in the ROM, for example.

The control unit 31 generates an animation signal and outputs it to the display unit 32, and generates a work instruction as necessary and outputs it to the communication unit 34. The control unit 31 generates an animation signal according to the read instruction program 35A, or generates a work command as necessary. For example, when the input signal input from the input unit 33 is the selection signal of the playback mode in which the processing operation is performed, the control unit 31 generates one or more operation programs 22B for displaying stored in the storage unit 24 according to the instruction program 35A The animated signal of the list. In addition, for example, when the playback mode is selected, when one operation program 22B to be played is selected, the control unit 31 generates an operation command including the number of the operation program 22B to be played according to the instruction program 35A. Furthermore, for example, when the playback mode is selected, when the learning mode or the abnormality determination mode is selected, the control unit 31 generates an operation command including a start command for the learning mode or the abnormality determination mode according to the instruction program 35A.

(Welding machine 40)

FIG. 10 shows an example of a schematic structure of the welding machine 40. The welding machine 40 generates an arc between the tip of the welding wire 16 and the workpiece W by precisely controlling the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the like according to the control by the robot control device 20. Welding machine 40 has: a control unit 41, a communication unit 42, a welding control unit 43, a welding power supply 44, current. The voltage measurement unit 45 and the storage unit 46.

The storage unit 46 stores a control program 46A that controls the operations of the welding control unit 43 and the welding power source 44. The control program 46A is stored in the ROM, for example. The control unit 41 controls each part of the welding machine 40, and controls the 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 will follow the current. The monitoring information acquired by the voltage measurement unit 45 (for example, notification information such as various measured values or notification of arc occurrence) is output to the communication unit 42. The communication unit 42 receives the welding command from the robot control device 20 and outputs it to the control unit 41. The communication unit 42 sends monitoring information (for example, various measured values or notification information) from the control unit 41 to the robot control device. Set 20 output.

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

The welding power supply 44 has, for example, a digital inverter circuit. The inverter control circuit performs precise welding current waveform control on a commercial power supply (eg, three-phase 200V) input from the outside in a fast response manner. That is, the welding power source 44 supplies a high-voltage welding voltage Vs between the welding torch 13 and the workpiece W through 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 the welding command from the robot control device 20. The welding command from the robot control device 20 may include, for example, an arc welding start command, an arc welding end command, a setting value of the welding current Is, a setting value of the welding voltage Vs, and the like.

Current. The voltage measuring section 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. Current. The voltage measuring section 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 control device 20, and separates the welding current Is, the welding voltage Vs and the short-circuit frequency fs The measured values (various measured values) are output to the control unit 41. Current. The voltage measuring section 45 measures the number of pulses per second (pulse frequency fp) during welding as required, and controls Section 41 output. Current. The voltage measuring unit 45 further determines the presence or absence of arcing from the measured values of the welding current Is and the welding voltage Vs. Current. When an arc occurs, the voltage measurement unit 45 generates an arc occurrence notification and outputs it to the control unit 41.

[Operation steps of learning mode]

Next, the operation steps of the learning mode will be described. In the following, after the accumulation of the implementation history is described, the threshold generation will be described.

(Accumulation of implementation history)

First, the accumulation of the implementation history of the learning mode will be described. In the teaching device 30, for example, the user selects the playback mode, and then further selects the learning mode. Then, the control unit 31 of the teaching device 30 generates a work command including the start command of the learning mode according to the instruction program 35A, and outputs it to the robot control device 20. When the operation command including the start command of the learning mode is input from the teaching device 30, the control unit 21 of the robot control device 20 reads out the operation program 22B and the arc welding quality judgment program 22C. The control unit 21 generates command notifications corresponding to the instructions written in these programs based on the contents read from the work program 22B and the arc welding quality judgment program 22C and the various setting values read from the setting file 22D of the storage unit 24. The control unit 21 outputs a movement command and a welding command based on the content of the generated command notification.

The control unit 21 outputs the generated welding command to the welding machine 40 through the communication unit 23. The welding command includes, for example, welding start commands, welding current Is, welding voltage Vs, and setting values of the wire feed speed Vf. If a welding command is input from the robot control device 20, the control unit 41 of the welding machine 40 reads out the control program 46A, sets the welding current Is and the welding voltage Vs according to the welding command, and sets the wire feed speed Vf to the wire feed device 14. This starts arc welding. At this time, the current. The voltage measuring section 45 samples various physical quantities and separates various objects obtained by sampling The measured value of the quantity is output to the control unit 41. Also, current. When detecting the occurrence of an arc, the voltage measurement unit 45 outputs an arc occurrence notification to the control unit 41. Control unit 41 through the communication unit 42, will be from the current. The monitoring information acquired by the voltage measurement unit 45 (for example, various measurement values or notification information such as an arc occurrence notification) is output to the robot control device 20. The control unit 41 calculates, for example, a moving average of various measured values during that period after a predetermined time interval (for example, a minimum of about 10 ms) has elapsed, and outputs it to the robot control device 20 through the communication unit 42.

The control unit 21 further outputs the generated movement command to the manipulator 10 through the communication unit 23. When the manipulator 10 inputs a movement command from the robot control device 20, each arm 12A is displaced according to the input movement command, and as a result, the welding gun 13 moves up, down, 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 save 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, and when the welding section WS ends, stores the number identifying the welding section WS in the measurement file 22E of the storage unit 24.

(Threshold generation)

i

N)作為母集團時，在該母集團中，於每個時刻tx(1

x

X)，根據時刻tx的N個測量值Px(1)~Px(N)之最大值Pmax(x)，設定時刻tx之上限值P_upper(x)。控制部21進一步在上述母集團中，於每個時刻tx，根據時刻tx的N個測量值Px(1)~Px(N)之最小值Pmin(x)，設定時刻tx之下限值P_lower(x)。控制部21例如藉由上述具體方法，設定時刻tx之上限值P_upper(x)和下限值P_lower(x)。 Next, the threshold generation of the learning pattern will be described. When detecting that the number of ending times of the welding interval WS reaches a predetermined number of times (N times), the control unit 21 acquires a plurality of (N) measured values P ₁ to a specific physical quantity of the parent group from the measurement file 22E of the storage unit 24 P _N. The control unit 21 determines the N measured values P ₁ to P _N (1 of the specific physical quantity obtained from the measurement file 22E of the storage unit 24 (1

i

N) as a parent group, in the parent group, at each time tx(1

x

X), based on the N measured values Px(1)~Px(N) maximum value Pmax(x) at time tx, set the _upper limit P _upper (x) at time tx. The control unit 21 further sets the _lower limit value P _lower at time tx based on the N measured values Px(1) to Px(N) minimum value Pmin(x) at time tx in the above parent group at each time tx (x). 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 above-described specific method, for example.

Furthermore, the control unit 21 may set the upper limit value P of the time tx based on the standard deviation σx of the N measured values Px(1) to Px(N) at the time tx in the parent group at each time tx _upper (x). The control unit 21 may further set the _lower limit P _lower (at the _lower limit of the time tx based on the standard deviation σx of the N measured values Px(1) to Px(N) at the time tx in the above parent group at each time tx x). At this time, the control unit 21 may set the _upper limit P _upper (x) and the lower limit P _lower (x) of the time tx by the above-described specific method, for example.

2)的測量值Pz(1)~Pz(NY)之最大值Pmax(x)，設定時刻tx之上限值P_upper(x)。控制部21亦可以進一步在上述母集團中，於每個時刻tx，根據包含時刻tx的複數個時刻的NY個(Y

2)的測量值Pz(1)~Pz(NY)之最小值Pmin(x)，設定時刻tx之下限值P_lower(x)。此時，控制部21例如亦可以藉由上述具體方法，設定時刻tx之上限值P_upper(x)和下限值P_lower(x)。 In addition, the control unit 21 may, in the above parent group, at each time tx, based on a plurality of NY (Y

2) The maximum value Pmax(x) of the measured value Pz(1)~Pz(NY) is the _upper limit P _upper (x) at the set time tx. The control unit 21 may further include, in each of the above parent groups, at each time tx, based on NY (Y

2) The minimum value Pmin(x) of the measured value Pz(1)~Pz(NY), and the _lower limit P _lower (x) at the set time tx. At this time, the control unit 21 may set the _upper limit P _upper (x) and the lower limit P _lower (x) of the time tx by the above-described specific method, for example.

2)的測量值Pz(1)~Pz(NY)的標準差σx，設定時刻tx之上限值P_upper(x)。控制部21亦可以進一步在 上述母集團中，於每個時刻tx，根據包含時刻tx的複數個時刻的NY個(Y

2)的測量值Pz(1)~Pz(NY)的標準差σx，設定時刻tx之下限值P_lower(x)。此時，控制部21例如亦可以藉由上述具體方法，設定時刻tx之上限值P_upper(x)和下限值P_lower(x)。 In addition, the control unit 21 may, in the above parent group, at each time tx, based on a plurality of NY (Y

2) The standard deviation σx of the measured values Pz(1)~Pz(NY) sets the _upper limit P _upper (x) at the time tx. The control unit 21 may further include, in each of the above parent groups, at each time tx, based on NY (Y

2) The standard deviation σx of the measured values Pz(1)~Pz(NY) sets the _lower limit P _lower (x) at the time tx. At this time, the control unit 21 may set the _upper limit P _upper (x) and the lower limit P _lower (x) of the time tx by the above-described specific method, for example.

The control unit 21 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 24. In this way, the learning mode is executed.

[Structure of abnormal judgment mode]

Next, the structure of the abnormality determination mode will be described.

FIG. 11 shows an example of function blocks in the abnormality determination mode of the welding robot system 1. In the abnormality determination mode, the welding robot system 1 includes a determination unit 216 instead of the setting unit 215 in the learning mode. The determination unit 216 corresponds to a specific example of the "determination unit" of the present invention. Therefore, in the following, the content different from the learning mode is mainly explained, and the same content as the learning mode is appropriately omitted.

When the track recording unit 214 receives the track recording end notification from the welding control unit 213 in the abnormality determination mode, it outputs a determination start command Oh. The control unit 21 includes a determination unit 216 (see FIG. 11) that performs abnormality determination according to the determination start instruction Oh. 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 instruction Oh, the measurement value P _N+1 obtained when welding under the same welding condition setting as the welding condition setting of the learning mode is at the upper limit P _upper (x) and the lower limit When the value P _lower (x) is within the range, it is determined that there is no welding defect; when the measured value P _N+1 is outside the above range, it is determined that there is welding defect.

The determination unit 216 may determine that there is a welding defect when a predetermined number of measurement values Px(N+1) included in the measurement value P _N+1 is 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 outside the above range exceeds a predetermined number.

The determination unit 216 may also determine that the measured value Px(N+1) is outside the above-mentioned range after determining that the measured value Px(N+1) is outside the above-mentioned range and after a predetermined time (the threshold exceeds the allowable time), It is judged that there is welding defect. Here, the determination unit 216 may derive the threshold value exceeding the allowable time from the preset distance and the welding speed Vw.

The determination unit 216 may issue an instruction to the robot control device 20 to stop welding immediately when it is determined that the welding is defective. In addition, the determination unit 216 may issue an instruction to the robot control device 20 to notify the welding failure when it is determined that the welding is defective.

FIG. 12 shows an example of graphic display on the display surface of the teaching device 30. The display unit 32 compares the relationship between the measured value P _N+1 and the welding distance Wp, and the upper limit value P _upper (x) and the lower limit value P _lowpr (x ) Graphic display together. 12 shows that: over a range above the upper limit P _upper (x) and the lower limit value P _lower (x) than the arc stability limit P _upper (x) and the lower limit value P _lower (x arc welding start ) Is wider.

[Quality Judgment]

Next, the arc welding quality determination procedure of the welding robot system 1 will be described with reference to FIG. 11.

First, the robot controller 20 (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 outputs these measured values to the control unit 21. The control unit 21 acquires the welding current Is and welding power from the welding machine 40 Measured values of pressure Vs, wire feed speed Vf and short-circuit frequency fs.

In addition, the control unit 21 issues a movement command to the servo control unit 22. Then, the servo control unit 22 controls the operation of the manipulator 10 according to the instruction from the control unit 21, and samples the position information of the encoder from the manipulator 10, and derives (measures) the welding gun from the position information obtained by the sampling 13 Position information Pf at the front end and welding speed Vw. The servo control unit 22 outputs the derived position information Pf and welding speed Vw to the control unit 21. The control unit 21 obtains the measured values of the position information Pf and the welding speed Vw from the servo control unit 22.

Next, the control unit 21 determines whether the elapsed period from the start of measurement (or the start of recalculation) to the current period exceeds the period required for calculation of the moving average (calculated period). The calculation period is, for example, at least about 10 μs. The control unit 21 calculates the moving average of the welding current Is, the welding voltage Vs, the wire feed speed Vf, the short-circuit frequency fs, and the welding speed Vw when the elapsed period exceeds the calculation period.

Next, the control unit 21 determines whether the calculated moving average is within the range of the upper limit P _upper (x) and the lower limit P _lower (x). When the calculated moving average value is within the above range, the control unit 21 determines that there is no welding defect. When the calculated moving average is outside the above range, the control unit 21 determines that there is a welding defect, and ends the quality determination.

In addition, the control unit 21 may continue the quality determination while continuing the welding operation to the end without completing the quality determination (that is, without stopping the welding operation) when it is determined that there is a welding defect. In addition, the control unit 21 may start to determine whether the calculated moving average value is within the above range at the start of welding, or may start to determine whether the calculated moving average value is within the above range after welding is completed.

[effect]

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

In the past, technologies for reducing welding defects and technologies for more accurately detecting welding defects have been developed. As a technique for more accurately detecting welding defects, for example, Patent Document 1 is proposed. Patent Document 1 proposes a technique for determining that a welding defect has occurred if the moving average value of the actual welding current or welding voltage during arc welding exceeds a predetermined range. However, in the invention described in Patent Document 1, since the threshold value is a fixed value based on the welding conditions (welding current, welding voltage, etc.) at the time of stability, the state at the time of instability (for example, when welding starts and when welding ends) Time or when the welding conditions are deliberately changed, etc.), there is a problem that the welding failure cannot be determined.

On the other hand, in the present embodiment, according to statistics from the group consisting of a plurality of past measured values P ₁ ~ P _N of the parent group obtained, poor welding set for determining the threshold value (upper limit value P _upper (x) and The lower limit P _lower (x)). With this, the thresholds (upper limit value P _upper (x) and lower limit value P _lower (x)) for determining welding failure are values obtained from the accumulation of stable welding results performed in the past. As a result, even in the welding state other than the stable state, since the threshold value obtained in the same welding state in the past is used, it is possible to determine the welding defect.

2)測量值Pz(1)~Pz(NY)之最大值Pmax(x)和最小值Pmin(x)，設定時刻tx之上限值P_upper(x)和下限值P_lower(x)的情況下， 即使在穩定時以外的焊接狀態，亦能夠以少的計算量來進行精度較高的焊接不良的判定。 In this embodiment, in the above parent group, at each time tx, it is set based on the maximum value Pmax(x) and the minimum value Pmin(x) of the N measured values Px(1) to Px(N) at the time tx In the case of the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx, the welding defect can be determined with a small amount of calculation even in a welding state other than the stable time. In addition, in this embodiment, in the above parent group, at each time tx, based on NY (Y

2) The maximum value Pmax(x) and minimum value Pmin(x) of the measured value Pz(1)~Pz(NY), the _upper limit P _upper (x) and the lower limit P _lower (x) of the set time tx In this case, even in a welding state other than when it is stable, it is possible to determine welding defects with high accuracy with a small amount of calculation.

2)測量值Pz(1)~Pz(NY)的標準差σ x，設定時刻tx之上限值P_upper(x)和下限值P_lower(x)的情況下，即使在穩定時以外的焊接狀態，亦能夠進行精度更高的焊接不良的判定。 In this embodiment, in the above parent group, at each time tx, based on the N measured values Px(1) to Px(N) standard deviation σ x at time tx, the upper limit P _upper ( In the case of x) and the lower limit P _lower (x), it is possible to determine welding defects with high accuracy even in a welding state other than the stable state. In addition, in this embodiment, in the above parent group, at each time tx, based on NY (Y

2) The standard deviation σ x of the measured values Pz(1)~Pz(NY), when the _upper limit P _upper (x) and the lower limit P _lower (x) of the set time tx are set, even when they are not stable In the welding state, it is possible to determine welding defects with higher accuracy.

1)的值設定為時刻tx之上限值P_upper(x)，並且將時刻tx的平均值μ x減去時刻tx或包含時刻tx的複數個時刻的標準差σ x的K倍(K

1)的值設定為時刻tx之下限值P_lower(x)的情況下，即使在穩定時以外的焊接狀態，亦能夠進行精度高的焊接不良的判定。 In the present embodiment, in the above parent group, at each time tx, the average value μ x of the time tx is added to the time tx or K times the standard deviation σ x of the plurality of times including the time tx (K

The value of 1) is set to the _upper limit P _upper (x) of the time tx, and the average value μ x of the time tx minus the time tx or K times (K times (K

When the value of 1) is set to the _lower limit P _lower (x) at time tx, it is possible to determine welding defects with high accuracy even in a welding state other than the stable time.

In the present embodiment, the measured value Px(i) (measured value at the start) which is the closest to the welding start position or the welding start time among the acquired measured values P ₁ to P _N is detected, and the When the measured value at the beginning of each measured value P ₁ ~P _N is detected as a starting point, when the _upper limit P _upper (x) and the lower limit P _lower (x) of the time tx are set, the cause can be reduced Misjudgment of deviation at the start of welding.

In the present embodiment, as a measurement value for determining welding failure, the 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, so that the welding failure can be determined even in a welding state other than stable. Furthermore, in the present embodiment, because a measuring section 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 section is used for welding failure Determination, it is possible to determine the welding failure even in the welding state other than the stable time.

In this embodiment, since the relationship between the measured value Px(i) and the welding distance Wp, and the upper limit value P _upper (x) and the lower limit value P _lower (x) are graphically displayed on the display unit 32, even if In the welding state other than the stable time, the user can intuitively confirm the result of the welding defect determination.

<2. Modifications>

Hereinafter, a modification of the welding robot system 1 of the above-described embodiment will be described. In addition, in the following, constituent elements common to the above-mentioned embodiment are given the same symbols as those of the above-mentioned embodiment. In addition, the main components that are different from the above-mentioned embodiment are mainly described, and the description of the components common to the above-mentioned embodiment is appropriately omitted.

[Modification A]

x

X)，設定了上限值P_upper(x)和下限值P_lower(x)。但是，在上述實施方式中，亦可以於每個以不同於採樣周期△t的周期規定的時刻tx(1

x

X)，設定上限值P_upper(x)和下限值P_lower(x)。 In the above embodiment, at each time tx(1

x

X), the upper limit P _upper (x) and the lower limit P _lower (x) are set. However, in the above-described embodiment, each time tx(1

x

X), set the upper limit P _upper (x) and the lower limit P _lower (x).

[Modification B]

In the above embodiment, in the setting file 22D, for example, the welding current Is, welding The setting values of the connection voltage Vs, the wire feed speed Vf and the welding speed Vw. However, in the above-described embodiment and its modification, the setting file 22D may further describe the setting values of the wire feed load Ld and the pulse frequency fp. At this time, in the measurement file 22E, the measured values of the wire feed load Ld and the pulse frequency fp are described. The wire feed load Ld is a physical quantity calculated from the motor current of the wire feed device 14. The pulse frequency fp is the number of pulses per second during welding by the pulse welding method. In this modification B, since the wire feed load Ld or the pulse frequency fp is used as a measurement value for determining welding failure, the welding failure can be determined even in a welding state other than the stable state. In addition, in the present modification B, since a measuring section for measuring the wire feed load Ld or the pulse frequency fp is provided, and the value measured by the measuring section is used for the determination of welding failure, the welding is not performed even when it is stable. In the state, it is possible to determine the welding defect.

[Variant C]

In the above embodiment, the threshold file 22F is stored in the storage unit 24 of the robot control device 20. However, in the above-described embodiment and its modification, the threshold file 22F may be stored in a storage unit such as another hard disk connected to the robot controller 20 via a network. However, in this case, the robot control device 20 stores the threshold file 22F in a storage unit such as another hard disk connected via the network, or reads the threshold file from the storage unit such as another hard disk connected via the network 22F.

[Modification D]

In the above-described embodiment, the control unit 21 generates the _upper limit value P _upper (x) and the lower limit value P _lower (x) at the time tx when the detection frequency of the end of the welding section WS reaches a predetermined number (N times). . However, in the above-described embodiment and its modification, the user may issue the upper limit value P of the generation time tx to the robot control device 20 (control unit 21) when the number of times the welding section WS ends reaches a predetermined number (N times) The indication of _upper (x) and lower limit P _lower (x).

This application claims priority based on the Japanese Patent Application 2015-164131 filed with the Japan Patent Office on August 21, 2015, and is incorporated by reference with reference to the entire contents of the case.

Those with ordinary knowledge in the technical field can think of various modifications, combinations, sub-combinations and changes based on design requirements and other factors, but they should be included in the scope of the additional patent application and their equivalents.

Claims (9)

An arc welding quality judging system, comprising: a setting unit that uses a plurality of first measured values obtained when welding is repeated under common welding condition settings as a parent group, in the parent group, each first At the time, the upper limit value of the first time is set according to the maximum value of the first time or the plurality of times including the first time, and the minimum value is set based on the minimum value of the first time or the plurality of times including the first time The lower limit at the first time; and the determination unit, when the second measurement value obtained during welding under the welding condition setting is within the range of the upper limit and the lower limit, it is determined that there is no welding defect, and the When the aforementioned measured value is outside the aforementioned range, it is determined that the welding is defective. An arc welding quality judging system, comprising: a setting unit that uses a plurality of first measured values obtained when welding is repeated under common welding condition settings as a parent group, in the parent group, each first At the time, the upper limit and the lower limit of the first time are set according to the standard deviation of the first time or a plurality of times including the first time; and the determination unit obtains the second value obtained by welding under the welding condition setting When the measured value is within the range of the upper limit and the lower limit, it is determined that there is no welding defect, and when the measured value is outside the range, it is determined that there is welding defect. The arc welding quality determination system as described in item 2 of the patent application scope, wherein the setting unit adds the average value of the first time to the first time or The value including the positive integer multiple of the standard deviation of the plural times at the first time is set as the upper limit at the first time, In the parent group, at each first time, the setting unit subtracts the average value of the first time or a positive integer multiple of the standard deviation of the first time or a plurality of times including the first time , Set to the lower limit value at the first moment. The arc welding quality judgment system as described in item 1 of the patent application range, wherein the plurality of first measured values are welding current, welding voltage, wire feed speed, welding speed, wire feed load, short circuit frequency or pulse frequency. The arc welding quality judgment system as described in item 2 of the patent application range, wherein the plurality of the first measured values are welding current, welding voltage, wire feed speed, welding speed, wire feed load, short circuit frequency or pulse frequency. The arc welding quality judgment system according to item 4 of the patent application scope, further comprising measuring the welding current, the welding voltage, the wire feed speed, the welding speed, the wire feed load, the short circuit frequency or the pulse frequency Measurement department. The arc welding quality judgment system according to item 5 of the patent application scope, further comprising measuring the welding current, the welding voltage, the wire feed speed, the welding speed, the wire feed load, the short circuit frequency or the pulse frequency Measurement department. The arc welding quality determination system according to item 1 of the patent application scope further includes a display unit that graphically displays the relationship between the second measured value and the welding distance, and the upper limit value and the lower limit value. The arc welding quality determination system according to item 2 of the patent application scope further includes a display unit that graphically displays the relationship between the second measured value and the welding distance, and the upper limit value and the lower limit value.

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