JP2017030047A - Welding monitoring device and welding robot system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that there is the possibility of causing inferior quality in a tail end part of a welding bead, when welding release operation is automatically executed.SOLUTION: A welding monitoring device comprises a detection unit for detecting a first frequency of exceeding a first threshold value in a measured value of a welding current in a predetermined period when finishing arc-welding or a second frequency of being less than a second threshold value in a measured value of a welding voltage in the predetermined period when finishing the arc-welding.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a welding monitoring apparatus and a welding robot system.

  In arc welding, at the end of arc welding, the welding electrode and the molten pool are short-circuited due to the vibration of the molten pool, etc., and the molten pool is solidified in a state where the welding electrode and the molten pool are short-circuited. May weld to bead. When the welding electrode is welded to the weld bead, a method (welding release processing) is known in which a current is passed through the welding electrode to release the short-circuited state between the welding electrode and the weld bead (for example, Patent Document 1, Patent Document 1). 2).

  Such a short-circuit between the welding electrode and the welding bead is, for example, when a welding bead dent called a crater occurs at a welding end portion, when performing welding to fill the crater, or after welding, This is likely to occur when a ball of an appropriate size is formed at the tip of the slag and the slag at the tip of the welding electrode is removed.

JP 2005-305485 A JP 2011-136372 A

  By the way, in the inventions described in Patent Documents 1 and 2, when a short-circuit state between the welding electrode and the weld bead is detected, a series of welding release operations described in advance in the work program are performed. However, since the welding release operation is automatically performed, there is a possibility that a quality defect has occurred at the end portion of the welding beat.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a welding monitoring apparatus and a welding robot system capable of detecting a quality defect at the end portion of a welding beat.

  The welding monitoring device of the present invention is the first number of times when the measured value of the welding current in a predetermined period at the end of arc welding exceeds the first threshold, or the welding voltage in the predetermined period at the end of arc welding. There is provided a detection unit for detecting a second number of times that the measured value falls below the second threshold.

  A welding robot system according to the present invention includes a moving device having a welding torch and an arm for moving the welding torch, a power supply device for supplying electric power to the welding torch, a welding current flowing between the welding torch and the workpiece, and welding. And a measuring device that measures at least one of the welding voltages between the torch and the workpiece. The welding robot system further includes a first number of times that a measured value of the welding current in a predetermined period at the end of arc welding exceeds a first threshold, or a welding voltage in a predetermined period at the end of arc welding. Is provided with a detection device that detects the second number of times that the measured value falls below the second threshold.

  In the welding monitoring apparatus and welding robot system of the present invention, the number of times welding has occurred in a predetermined period at the end of arc welding is detected. Here, since the number of times of welding has a correlation with the quality of the end portion of the welding beat, the quality of the end portion of the welding beat can be estimated by detecting the number of times of welding.

  According to the welding monitoring apparatus and the welding robot system of the present invention, since the number of times welding has occurred in a predetermined period at the end of arc welding is detected, it is possible to detect a quality defect at the end portion of the welding beat. .

It is a figure showing an example of schematic structure of the welding robot system provided with the welding monitoring device concerning one embodiment of the present invention. It is a figure showing an example of the functional block 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 figure showing an example of the functional block of the monitoring part of FIG. 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. (A) It is a figure showing an example of the measured value of the wire feeding speed at the time of completion | finish of arc welding. (B) It is a figure showing an example of the measured value of the welding voltage at the time of completion | finish of arc welding. (C) It is a figure showing an example of the measured value of the welding current in the end of arc welding. (A) It is a figure showing an example of the measured value of the wire feeding speed at the time of completion | finish of arc welding. (B) It is a figure showing an example of the measured value of the welding voltage at the time of completion | finish of arc welding. (C) It is a figure showing an example of the measured value of the welding current in the end of arc welding. (A) It is a figure showing an example of the measured value of the wire feeding speed at the time of completion | finish of arc welding. (B) It is a figure showing an example of the measured value of the welding voltage at the time of completion | finish of arc welding. (C) It is a figure showing an example of the measured value of the welding current in the end of arc welding. (A) It is a figure showing an example of the measured value of the wire feeding speed at the time of completion | finish of arc welding. (B) It is a figure showing an example of the measured value of the welding voltage at the time of completion | finish of arc welding. (C) It is a figure showing an example of the measured value of the welding current in the end of arc welding. (A) It is a figure showing an example of the measured value of the wire feeding speed at the time of completion | finish of arc welding. (B) It is a figure showing an example of the measured value of the welding voltage at the time of completion | finish of arc welding. (C) It is a figure showing an example of the measured value of the welding current in the end of arc welding.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The following description is one specific example of the present invention, and the present invention is not limited to the following embodiment. Further, the present invention is not limited to the arrangement, dimensions, dimensional ratios, and the like of the components shown in the drawings.

<1. Embodiment>
[Constitution]
FIG. 1 shows an example of a schematic configuration of a welding robot system 1 according to an embodiment of the present invention. FIG. 2 shows an example of functional blocks of the welding robot system 1 of FIG. 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 device including the robot control device 20 and the teach pendant 30 corresponds to a specific example of the “welding monitoring device” of the present invention. The manipulator 10 corresponds to a specific example of the “moving device” of the present invention. The robot control device 20 corresponds to a specific example of the “detection device” of the present invention. The welding machine 40 corresponds to a specific example of “power supply device” and “measurement device” of the present invention. The robot controller 20 and the teach pendant 30 may be configured integrally with each other, or may be configured separately from each other as illustrated 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. The cables L5 and L6 are power cables for supplying a high welding voltage Vs between a welding electrode 15 described later and the workpiece W. 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 outputs the detected current position of each arm 12A (hereinafter referred to as “position information Pf”) to the robot control device 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 electrode 15 as a filler material is exposed at the tip of the welding torch 13. The welding electrode 15 is a welding wire that is a consumable electrode. The welding torch 13 performs arc welding on the workpiece W by generating an arc between the tip of the welding electrode 15 and the workpiece W and melting the welding electrode 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 voltage Vs supplied from the cable L4 to the welding electrode 15.

  The wire feeder 14 supplies the welding electrode 15 to the welding torch 13. The wire feeding device 14 has, for example, a pair of rolls (not shown) configured to hold and supply the welding electrode 15 and a motor (not shown) that rotationally drives one of the rolls. ing. The pair of rolls are configured to sandwich the welding electrode 15 and pull the welding electrode 15 from a wire reel (not shown) by a 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 (wire feeding speed Vf) of the welding electrode 15. The motor may generate and output some signal instead of the pulse.

  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 controller 20 is also configured to monitor welding. 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 “detection unit”, “determination unit”, and “transfer unit” of the present invention. The storage unit 24 corresponds to a specific example of “storage device” 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 stores one or a plurality of work programs 22B in which a procedure for welding work of the manipulator 10 is taught, a welding monitoring program 22C for monitoring welding, and a setting file 22D in which various setting values are described. doing. One or a plurality of work programs 22B, a welding monitoring 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 welding monitoring program 22C, the threshold value Vth of the welding voltage Vs, and the threshold value Ith of the welding current Is will be described in detail later.

  The storage unit 24 further stores a threshold file 22E and a recovery table 22F used for welding monitoring. The threshold file 22E and the recovery table 22F are stored in, for example, a hard disk. In the threshold file 22E, for example, a threshold Ith of the welding current Is and a threshold Vth of the welding voltage Vs are described. The threshold value Ith of the welding current Is corresponds to a specific example of the “first threshold value” of the present invention. The threshold value Vth of the welding voltage Vs corresponds to a specific example of the “second threshold value” of the present invention. In the recovery table 22F, for example, the recovery information Ir is described according to the number of welding release times Nd. The welding release number Nd corresponds to a specific example of “first number” and “second number” of the present invention. The recovery information Ir corresponds to a specific example of “operation of the arc welding robot system” of the present invention. The number of welding release times Nd corresponds to the number of weldings that occurred in a predetermined period ΔT at the end of arc welding. The number of welding release times Nd includes, for example, the number of welding release times Nd1 and the number of welding release times Nd2. The number of welding release times Nd1 is obtained based on the measured value of the welding current Is. The number of welding release times Nd2 is obtained based on the measured value of the welding voltage Vs. The recovery information Ir is information relating to the operation of the arc welding robot system 1 after a predetermined period ΔT at the end of arc welding has elapsed. For example, the names of various operations of the arc welding robot system 1 and the arc welding robot And an instruction set corresponding to various operations of the system 1.

  Further, the storage unit 24 can store various data generated by executing the welding monitoring program 22C. Examples of files including such data include a measurement file 22G and a history file 22H. In the measurement file 22G, measurement values of various physical quantities are described. The measured values of various physical quantities include instantaneous values and moving average values. The various physical quantities include, for example, a welding current Is, a welding voltage Vs, a wire feeding speed Vf, and a welding speed Vw. The instantaneous value is obtained by measuring at the sampling frequency. The moving average value is, for example, an average value of a plurality of instantaneous values included in a certain period (so-called simple moving average value). The sampling frequency is a value that can sufficiently determine the presence or absence of welding from one of the measured values of the welding current Is and the welding voltage Vs. In the history file 22H, monitoring information Dm including the number Nd of welding release and the recovery information Ir is described. These files are stored in, for example, a RAM (Random Access Memory).

  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 Om described in the work program 22B and the position information from the encoder of the manipulator 10. The movement command Om may include, for example, a movement start command, a movement stop command, a work route (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 the monitoring information from the control unit 21 to the teach pendant 30. The monitoring information includes, for example, the respective measured values of the welding current Is and the welding voltage Vs, the measured value of the wire feed speed Vf, the presence / absence of welding, the number Nd of welding release, the step of the work program 22B when welding occurs, A welding generation position (or a welding generation section) or the like may be included.

  The communication unit 23 is configured to transmit a welding command Ow from the control unit 21 to the welding machine 40. The welding command Ow includes, 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, a wire feed start command, a wire feed stop command, and a wire. A setting value of the feeding 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 22G 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. Various measurement values may include, for example, respective measurement values of the welding current Is, the welding voltage Vs, and the wire feed speed Vf. 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, the welding control unit 213 starts monitoring based on the welding monitoring program 22C (monitoring start notification) in accordance with monitor information (for example, arc occurrence notification) input from the welding machine 40 via the communication unit 23. Is supposed to generate. Moreover, the welding control part 213 produces | generates the notification (monitoring completion notification) which complete | finishes the monitoring based on the welding monitoring program 22C according to the welding distance Wp, for example. The welding distance Wp is derived by, for example, welding speed Vw × arc time At. The welding control unit 213 derives the welding distance Wp using the welding speed Vw input from the servo control unit 22 and the time (arc time) after receiving the arc generation notification.

  The control unit 21 has a monitoring unit 214 that executes the welding monitoring program 22C in accordance with the monitoring start notification from the welding control unit 213 (see FIG. 2). For example, as shown in FIG. 4, the monitoring unit 214 includes a detection unit 214a, a determination unit 214b, and a transfer unit 214c. FIG. 4 illustrates an example of functional blocks of the monitoring unit 214.

  The detection unit 214a reads out from the measurement file 22G at least one measurement value of the welding current Is and the welding voltage Vs in a predetermined period ΔT at the end of arc welding. The detection unit 214a reads the measurement value of the wire feeding speed Vf from the measurement file 22G as necessary. The detection unit 214a further reads out at least one threshold value (at least one of Ith and Vth) of the welding current Is and the welding voltage Vs from the threshold file 22F. The detection unit 214a detects the number of times that the measured value crosses a predetermined threshold value from a predetermined direction (number of times of welding release Nd). For example, the detection unit 214a detects the number of times that the measured value of the welding current Is exceeds the threshold value Ith (the number of times of welding release Nd1). The detection unit 214a detects, for example, the number of times that the measured value of the welding voltage Vs falls below the threshold value Vth (the number of times of welding release Nd2). The detecting unit 214a further detects the presence / absence of welding, the step of the work program 22B at the time of occurrence of welding, and the position of welding occurrence (or a welding occurrence section). The detection unit 214a outputs the welding release number Nd (the welding release number Nd1 or the welding release number Nd2) to the determination unit 214b and the transfer unit 214c. The detection unit 214a further outputs to the transfer unit 214c the presence / absence of welding, the step of the work program 22B at the time of welding occurrence, the welding position (or welding zone), and the measurement value read from the measurement file 22G. It has become.

  The determination unit 214b determines the operation of the arc welding robot system 1 after a predetermined period ΔT has elapsed based on the number of welding releases Nd (the number of welding releases Nd1 or the number of welding releases Nd2) detected by the detection unit 214a. It is like that. For example, the determination unit 214b acquires the recovery information Ir corresponding to the number of welding release times Nd (the number of welding release times Nd1 or the number of welding release times Nd2) from the recovery table 22F, and issues a command based on the acquired recovery information Ir to the servo control unit 22. And it outputs to the welding machine 40. The determination unit 214b outputs information (recovery information Ir) related to the operation determined by the determination unit 214b to the transfer unit 214c.

  The transfer unit 214c generates monitoring information Dm based on information input from the detection unit 214a and information input from the detection unit 214a. The monitoring information Dm includes at least welding release times Nd (welding release times Nd1 or welding release times Nd2) detected by the detection unit 214a and information (recovery information Ir) related to the operation determined by the determination unit 214b. It is out. The transfer unit 214c is configured to output the monitoring information Dm to the teach pendant 30. Further, the transfer unit 214c stores the monitoring information Dm in the history file 22H.

(Teach pendant 30)
FIG. 5 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 corresponds to a specific example of “notification unit” of the present invention.

  The display unit 32 displays video based on the video signal. When the display unit 32 acquires a video signal for displaying the monitoring information Dm from the communication unit 34, the display unit 32 performs display (notification) based on the monitoring information Dm. For example, the display unit 32 displays (notifies) the number of times of welding release Nd (the number of times of welding release Nd1 or the number of times of release of welding Nd2) included in the monitoring information Dm.

  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, when the control unit 31 acquires the monitoring information Dm from the communication unit 34, the control unit 31 generates a video signal for displaying the acquired monitoring information Dm. Yes.

(Welder 40)
FIG. 6 illustrates an example of a schematic configuration of the welding machine 40. The welding machine 40 controls the welding current Is, the welding voltage Vs, the wire feed speed Vf, and the like based on the control by the robot control device 20, thereby forming an arc between the tip of the welding electrode 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 outputs the measured value of the wire feed speed Vf 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 and the welding voltage Vs at a predetermined sampling frequency in accordance with the control program 46A and the welding command from the robot controller 20, and measures the welding current Is and the welding voltage Vs, respectively. Values (various measurement values) are output to the control unit 41. 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]
Next, the operation of the welding robot system 1 will be described.

  First, in the teach pendant 30, the user selects, for example, a reproduction mode, and further selects a teaching program 35A. Then, the control unit 31 of the teach pendant 30 generates a work command including an activation 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 an activation 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 welding monitoring program 22C. Based on the contents read from the work program 22B and the welding monitoring program 22C and the various setting values read from the setting file 22D of the storage unit 24, the control unit 21 issues a command notification corresponding to the instructions described in these programs. Generate. The control unit 21 outputs a movement command Om and a welding command Ow according to the content of the generated command notification.

  The control unit 21 outputs the generated welding command Ow to the welding machine 40 via the communication unit 23. The welding command Ow 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 the welding command Ow 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 according to the welding command Ow, and transmits the wire. Arc welding is started by setting the wire feed speed Vf to the feeder 14. 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, at a preset time interval, the control unit 41 calculates a moving average value of various measurement values during that time interval, and outputs it to the robot control device 20 via the communication unit 42.

  The control unit 21 further outputs the generated movement command Om to the manipulator 10 via the communication unit 23. When the movement command Om is input from the robot controller 20, the manipulator 10 displaces each arm 12A according to the input movement command Om, and consequently moves the welding torch 13 up and down, front and rear, and right and left. 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 22G of the storage unit 24. The control unit 21 derives the welding speed Vw and the position information Pf based on the position information acquired from the encoder, and stores it in the measurement file 22G of the storage unit 24. The control unit 21 determines the end of the welding section WS based on the position information Pf, and stores the number for identifying the welding section WS in the measurement file 22G of the storage unit 24 when the welding section WS ends.

  At the end of arc welding (end of the welding section WS), the control unit 21 has an appropriate size for welding for filling the crater generated in the welding end portion and the tip of the welding electrode 15 as necessary. Various processes, such as forming a ball of Sano, are performed.

  Next, the operation after the end of arc welding (end of welding section WS) will be described. FIG. 7 shows various measured values in waveform after time T1 when arc welding (welding section WS) is completed. FIG. 7A shows an example of a measured value of the wire feed speed Vf at the end of arc welding. FIG. 7B shows an example of a measured value of the welding voltage Vs at the end of arc welding. FIG. 7C shows an example of a measured value of the welding current Is at the end of arc welding.

  The control unit 21 outputs a control signal for stopping the motor of the wire feeding device 14 to the welding machine 40 at the end of arc welding (end of the welding section WS). Then, the welding machine 40 outputs a command to stop the rotation of the motor to the motor of the wire feeder 14 at time T1. However, the motor of the wire feeder 14 rotates while decelerating for a while due to inertia, and finally stops.

  The control unit 21 outputs a control signal for stopping the supply of the welding current Is and the welding voltage Vs to the welding machine 40 when the motor of the wire feeding device 14 is stopped. Then, the welding machine 40 stops supplying the welding current Is and the welding voltage Vs at time T2. Thereby, the arc disappears completely.

  The control unit 21 outputs a control signal for restarting the supply of the welding current Is and the welding voltage Vs to the welding machine 40 after a predetermined period has elapsed after the arc has completely disappeared. At this time, the control unit 21 requests the welding machine 40 to supply the welding current Is and the welding voltage Vs for confirmation of welding. Then, the welding machine 40 outputs the welding current Is and welding voltage Vs for welding confirmation during a predetermined period ΔT from time T3 to time T4. The welding voltage Vs for confirming welding is a voltage value higher than the threshold value Vth. The welding current Is for confirmation of welding has a voltage value higher than the threshold value Ith. However, when no welding occurs at all during the period ΔT, the welding current Is does not flow, so the measured value of the welding current Is during the period ΔT is almost zero.

  FIG. 8 shows various measured values as waveforms when the welding is released after time T1 when the arc welding (welding section WS) is completed. FIG. 8A shows an example of a measured value of the wire feed speed Vf at the end of arc welding. FIG. 8B shows an example of a measured value of the welding voltage Vs at the end of arc welding. FIG. 8C shows an example of a measured value of the welding current Is at the end of arc welding.

  Similarly to FIG. 7 described above, the control unit 21 requests the welding machine 40 to output the welding current Is and welding voltage Vs for confirmation of welding for a predetermined period ΔT. Then, the welding machine 40 starts outputting the welding current Is and the welding voltage Vs for confirmation of welding from time T3. Thereafter, it is assumed that welding is released once during a predetermined period ΔT. At this time, due to welding, the tip of the welding electrode 15 and the workpiece W are short-circuited, the welding voltage Vs falls below the threshold value Vth, and the welding current Is exceeds the threshold value Ith. However, the welding is immediately released, and the welding voltage Vs exceeds the threshold value Vth again, and the welding current Is falls below the threshold value Ith. The control unit 21 detects that the welding voltage Vs has fallen below the threshold value Vth only once, or that the welding current Is has exceeded the threshold value Ith only once. The control unit 21 acquires the recovery information Ir corresponding to the welding release count Nd from the recovery table 22F, and instructs the welding machine 40 and the servo control unit 2 to perform an operation based on the acquired recovery information Ir. At this time, when the recovery information Ir when the number of times of welding release Nd = 1 is, for example, “no recovery”, the control unit 21 sends the welding current Is and The stop of output of the welding voltage Vs is continuously instructed, and the servo controller 2 is instructed to stop.

  FIG. 9 shows waveforms of various measured values when welding release occurs after time T1 when arc welding (welding section WS) is completed. FIG. 9A shows an example of a measured value of the wire feed speed Vf at the end of arc welding. FIG. 9B shows an example of a measured value of the welding voltage Vs at the end of arc welding. FIG. 9C shows an example of a measured value of the welding current Is at the end of arc welding.

  Similarly to FIG. 8 described above, the control unit 21 requests the welding machine 40 to output the welding current Is and welding voltage Vs for confirmation of welding for a predetermined period ΔT. Then, the welding machine 40 starts outputting the welding current Is and the welding voltage Vs for confirmation of welding from time T3. After that, it is assumed that welding is released twice during a predetermined period ΔT. At this time, the control unit 21 detects that the welding voltage Vs has fallen below the threshold value Vth twice or that the welding current Is has exceeded the threshold value Ith only twice. The control unit 21 acquires the recovery information Ir corresponding to the number of welding releases Nd from the recovery table 22F, and performs an operation based on the acquired recovery information Ir at time T5 after a predetermined period ΔT has elapsed. The servo controller 2 is instructed. At this time, when the recovery information Ir when the number of welding release times Nd = 2 is, for example, “repair of the end portion”, the control unit 21 sends a weld bead to the servo control unit 2. In this case, the welding torch 13 is returned to a position slightly before the end portion, and the welding torch 13 is instructed to move from the place to the end portion, and the welding torch 13 returns to a predetermined position for the welding machine 40. At the same timing, the output of the welding current Is and the welding voltage Vs is restarted, and an instruction to perform arc welding up to the end portion is given.

  As shown in FIG. 10, when the predetermined period ΔT has passed without releasing the welding generated during the predetermined period ΔT, the welding torch 13 cannot move from the welded position. . At this time, the control unit 21 delays the above-described time T5, and instructs the welding machine 40 to release the welding at time T6 between time T4 and time T5. Specifically, the control unit 21 instructs the welding machine 40 to output the rated voltage at time T6. Then, since the welding machine 40 outputs the welding voltage Vs of a rated voltage, welding is cancelled | released. At this time, the control unit 21 also adds the welding release at time T6 to the welding release count Nd. Thereby, the control part 21 can acquire more suitable recovery information Ir from the recovery table 22F.

  Further, as shown in FIG. 11, when the state where the welding is not released continues for a predetermined period, the control unit 21 extends the predetermined period ΔT and at time T7 within the predetermined period ΔT, An instruction to cancel welding may be given to the welding machine 40.

[effect]
Next, the effect of the welding robot system 1 will be described.

  Conventionally, when a short-circuit state between the welding electrode and the welding bead is detected, a series of welding release operations described in advance in the work program are performed. However, since the welding release operation is automatically performed, there is a possibility that a quality defect has occurred at the end portion of the welding beat.

  On the other hand, in the welding robot system 1, the number of times of welding release (the number of welding release times Nd) is detected in a predetermined period ΔT at the end of arc welding. Here, since the welding release frequency Nd has a correlation with the quality of the welding beat end portion, the quality of the welding beat end portion can be estimated by detecting the welding release frequency Nd. Therefore, the welding robot system 1 can detect a quality defect at the end portion of the welding beat. As a result, it is possible to prevent a defective product from flowing into the subsequent process. Further, by detecting the number of welding release times Nd, the user can grasp that a delay corresponding to the number of welding release times Nd has occurred.

  In welding robot system 1, the operation of arc welding robot system 1 after a predetermined period ΔT has elapsed is determined based on the detected number of welding releases Nd. Thereby, the quality defect of the terminal part of a welding beat can be repaired. Further, in the welding robot system 1, the detected number of welding releases Nd and the determined operation (for example, repair operation) of the arc welding robot system 1 are stored in the history file 22 </ b> H of the storage unit 24. Thus, by analyzing the history file 22H, the teaching method of the welding section WS where welding is likely to occur is examined, and the arc start process in the welding section WS next to the welding section WS where welding has occurred is examined. Can be.

<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.

  In the above embodiment, the display unit 32 of the teach pendant 30 is exemplified as the “notification unit” of the present invention, but other notification methods such as a warning lamp may be used.

  In the above embodiment, the storage unit 24 of the robot control device 20 is exemplified as the “storage device” of the present invention. However, the storage unit 24 is built in an information processing device such as a server connected to the welding robot system 1 via a network. A storage device may be used.

  DESCRIPTION OF SYMBOLS 1 ... Welding robot system, 10 ... Manipulator, 11 ... Base member, 12 ... Articulated arm part, 12A ... Arm, 13 ... Welding torch, 14 ... Welding electrode, 15 ... Work table, 20 ... Robot controller, 21 ... Control , 22 ... servo control unit, 22A ... control program, 22B ... work program, 22C ... welding monitoring program, 22D ... setting file, 22E ... threshold file, 22F ... measurement file, 22G ... history file, 23 ... communication unit, 30 ... teach pendant, 31 ... control unit, 32 ... display unit, 33 ... input unit, 34 ... communication unit, 35 ... storage unit, 35A ... teaching program, 40 ... welding machine, 41 ... control unit, 42 ... communication unit, 43 ... Welding control unit, 44 ... Welding power supply, 45 ... Current / voltage measurement unit, 46 ... Storage unit, 46A ... Control program, 211 ... Analysis unit ... execution unit, 213 ... welding control unit, 214 ... monitoring unit, At ... arc time, Dm ... monitoring information, Ir ... recovery information, Is ... welding current, Ith ... threshold voltage, L1 to L6 ... cable, Nd ... welding release Number of times, Om ... movement command, Ow ... welding command, Vth ... threshold voltage, Vf ... wire feed speed, Vs ... welding voltage, WS ... welding section, W ... work, [Delta] T ... period, T1-T7 ... time.

Claims (5)

The first number of times that the measured value of the welding current in the predetermined period at the end of arc welding exceeds the first threshold, or the measured value of the welding voltage in the predetermined period at the end of arc welding is the second. A welding monitoring apparatus including a detection unit that detects a second number of times that falls below a threshold. The apparatus according to claim 1, further comprising a determination unit that determines an operation of the arc welding robot system after the predetermined period has elapsed based on the first number or the second number detected by the detection unit. The welding monitoring apparatus described. The welding according to claim 2, further comprising: a transfer unit that transfers the information related to the first number of times or the second number of times detected by the detection unit and the operation determined by the determination unit to a storage device. Monitoring device. The welding monitoring apparatus according to any one of claims 1 to 3, further comprising a notification unit that performs notification based on the first number or the second number of times detected by the detection unit. A moving device having a welding torch and an arm for moving the welding torch;
A power supply for supplying power to the welding torch;
A measuring device for measuring at least one of a welding current flowing between the welding torch and the workpiece and a welding voltage between the welding torch and the workpiece;
The first number of times that the measured value of the welding current in the predetermined period at the end of arc welding exceeds the first threshold, or the measured value of the welding voltage in the predetermined period at the end of arc welding is the second. A welding robot system comprising: a detection device that detects a second number of times that falls below a threshold value.

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