JP5506294B2 - Control device for arc welding robot - Google Patents

Description

  The present invention relates to a control device for an arc welding robot that samples and stores actual welding condition values during a welding operation and supports verification of welding conditions, management of welding quality, and the like.

  Conventionally, the taught work program is replayed to perform arc welding work, and during the welding work, at least one of the actual welding condition value and the actual welding voltage value is sampled at predetermined intervals. An arc welding robot that can verify the welding conditions and manage the welding quality by storing them (see, for example, Patent Documents 1 and 2) is known.

  FIG. 7 is a block diagram of a conventional arc welding robot apparatus 50 that samples and stores actual welding condition values at predetermined intervals.

  The manipulator M automatically performs arc welding on the workpiece W, and includes a plurality of arm portions and a wrist portion, and a plurality of servo motors (none of which are shown) for rotationally driving them. ing. The arc welding torch T is attached to the tip portion of the upper arm of the manipulator M, and a welding wire having a diameter of about 1 mm wound around a wire reel (not shown) is used as a taught welding line on the workpiece W. It is for guiding.

  The teach pendant TP teaches the operation conditions of the manipulator M, welding conditions necessary for performing arc welding, and the like as a work program, and also functions as a monitor device that displays sampling data of actual welding condition values. The teach pendant TP includes a display unit for displaying a work program and the like, and a keyboard (all not shown) for inputting welding conditions (welding current value, welding voltage value, welding speed) and the like. An operator uses this teach pendant TP to create a work program or to check sampling data of actual welding condition values.

  The robot controller RC is for causing the manipulator M to control the welding operation, and includes a CPU 51 as a central processing unit, a storage unit 52 for storing work programs, sampled actual welding condition values, and the like, not shown. Various control units and servo drivers are provided. Based on the work program taught by the teach pendant TP, an operation control signal is output from the servo driver to each servo motor of the manipulator M, and the plurality of axes of the manipulator M are driven to rotate.

  The welding power source WP supplies a welding voltage between the arc welding torch T and the workpiece W.

  Hereinafter, the operation relating to the detection of the welding current or the welding voltage will be described. When the activation signal is input to the robot controller RC, an operation control signal is output based on the work program, and the manipulator M moves the arc welding torch T to the welding start position.

  When the arc welding torch T reaches the welding start position, the robot controller RC outputs a welding power source output control signal to the welding power source WP. The welding power source WP outputs a welding current and a welding voltage for performing arc welding.

  By applying a voltage supplied from the welding power source WP between the workpiece W and the arc welding torch T, an arc is generated. When the generation of the arc is confirmed, the arc welding torch T is moved to perform welding on the workpiece W, thereby forming a weld bead. At this time, the welding current is detected by the current detector 54 and the welding voltage is detected by the voltage detector 55 at predetermined intervals. The detected welding current value and / or welding voltage value (hereinafter simply referred to as actual welding condition value) are input to the low-pass filters 56 and 57, respectively, and noise components are removed, and the A / D converters 58 and 59 are used. , Converted into a digital value, and taken into the robot controller RC. The actual welding condition value taken in is subjected to various arithmetic processes by the CPU 51, and the arc state is monitored by various welding abnormality detection algorithms. Further, the actual welding condition value taken in is stored in the storage unit 52.

  In this way, the taught work program is reproduced to execute arc welding work, actual welding condition values are detected at predetermined intervals during the welding work, and stored in the robot controller RC as sampling data.

  Patent Document 1 discloses a control of an arc welding robot that determines whether or not the sampling data deviates from a predetermined allowable range of welding conditions, and can check the sampling data deviating from the allowable range in time series using a teach pendant. An apparatus is disclosed. According to this prior art, it is possible to grasp the tendency of the departure phenomenon and to easily maintain and manage the welding quality.

  Patent Document 2 discloses an arc welding monitor device that can display an operation trajectory (workpiece welding line information) of a robot and the sampling data in association with each other. According to this prior art, if the range of the robot movement trajectory displayed on a monitor device such as a personal computer is designated by an input device such as a mouse, the waveform of the actual welding condition value is changed within that range, so that welding is performed. The unstable part can be identified relatively early. Therefore, the location where the welding conditions including the position and orientation of the robot must be corrected can be grasped, and the welding quality can be improved.

Japanese Patent Laid-Open No. 11-104831 Japanese Patent Laid-Open No. 11-58007

  In the prior art described in Patent Document 1, the actual welding condition values are displayed on the teach pendant in time series, and the sampling data deviating from the allowable range can be easily grasped, but when the actual welding condition values are sampled It is not easy to know what the actual position and orientation of the robot (hereinafter referred to as the sampling position) was.

  In the prior art described in Patent Document 2, since the robot operation trajectory and the actual welding condition value are displayed on the monitor device in association with each other, the actual welding condition value deviates from the allowable range at any part of the robot operation trajectory. I can understand. However, since the robot motion trajectory displayed on the monitor device is reproduced in a virtual space such as a personal computer, the actual robot position and orientation are checked against the actual welding condition values at that time. Can not do it.

  In this way, in the prior art, the actual state of the workpiece at the sampling position where the actual welding condition value deviated from the appropriate range, the position and orientation of the robot, etc., were actually checked against the actual object. Since it was difficult to do so, there was a problem that teaching correction could not be performed at an early stage.

  Therefore, the present invention provides a control apparatus for an arc welding robot that can grasp the state of a workpiece or the position and orientation of a robot, which is the cause when the actual welding condition value deviates from an allowable range, in comparison with the actual object. The purpose is to provide.

In order to achieve the above object, the first invention provides:
The arc welding torch attached to the robot is moved according to the work program taught in advance by the teach pendant to execute the welding work, and during this welding work, at least one of the actual welding current value and the actual welding voltage value is measured. In a control device for an arc welding robot having a data storage unit that samples and stores welding condition values at predetermined intervals,
The data storage unit stores position specifying information for specifying a sampling position of the actual welding condition value together with the actual welding condition value,
A display output unit for displaying the actual welding condition value and the position specifying information as sampling data on the teach pendant;
During the teaching mode after the welding operation is completed, the sampling position is specified based on the position specifying information selected by the teach pendant, the arc welding torch is moved to the specified sampling position, and the welding is performed. A position reproduction unit that reproduces the position and orientation during work ,
The display output unit displays teaching data of the work program on the teach pendant simultaneously with the sampling data,
The position reproduction unit is a control device for an arc welding robot that moves the arc welding torch to the sampling position when the sampling data is selected by a sampling data selection unit provided in the teach pendant. is there.

  According to a second aspect of the invention, the position specifying information includes a work program number for specifying the work program, a welding start step number for starting a welding work, and a sampling number of the actual welding condition value. It is a control apparatus of the arc welding robot as described in invention.

  In a third aspect of the invention, the position reproduction unit calculates a welding start position based on the work program number and the welding work step number, and further moves from the welding start position based on the sampling number and the predetermined period. The control apparatus for an arc welding robot according to the second aspect, wherein the sampling position is specified by calculating a distance.

  4th invention is provided with the judgment part which judges whether the said actual welding condition value has deviated from the predetermined allowable range value, and the said display output part is the said allowance according to the judgment result of the said judgment part. The control apparatus for an arc welding robot according to any one of the first to third inventions, wherein the actual welding condition value and the position specifying information deviating from a range value are displayed.

According to the first invention, in the teaching mode after completion of the welding operation, the sampling position of the actual welding condition value is specified, and the arc welding torch can be moved to the specified sampling position. More specifically, as shown in FIG. 4, the sampling data can be displayed together with the work program on the teach pendant. Furthermore, the sampling data can be displayed in order in the welding progress direction (or the opposite direction), and the welding torch is moved to the sampling position simultaneously with the display. In other words, the position and orientation during the welding operation and the sampling data can be reproduced in an interlocked manner. For example, when the actual welding condition value deviates from the allowable range, the state of the work that is the factor or the robot The position and orientation can be checked against the actual object.

  According to the second invention, the work program number, the welding start step number, and the sampling number are used as the position specifying information for specifying the sampling position. If only the sampling position is specified, it is conceivable to store the position and orientation data at the time of sampling together with the actual welding condition value. However, for example, if the position and orientation data is a 6-axis articulated manipulator, 6 It is necessary to store each axis data for each axis, which may increase the data size. By using the work program number, the welding start step number, and the sampling number as the position specifying information, it is possible to suppress the data size from becoming enormous in addition to the effect exhibited by the first invention.

  According to the third aspect, the welding start position is calculated based on the work program number and the welding work step number, and the sampling position is calculated by calculating the moving distance from the welding start position based on the sampling number and the predetermined cycle. I try to identify. Thus, in addition to the effects produced by the first and second inventions, the sampling position can be calculated by a very simple method.

  According to the fourth invention, it is determined whether or not the actual welding condition value deviates from a predetermined allowable range value, and only the actual welding condition value and position specifying information deviating from the allowable range value are displayed. By doing so, in addition to the effects exhibited by the first to third inventions, it is possible to easily identify the location where the actual welding condition value deviates from the allowable range.

It is a block diagram of the arc welding robot apparatus in the embodiment of the present invention. It is an example of teaching for demonstrating position specific information. It is an example of the data at the time of preserve | saving an actual welding condition value in a robot control apparatus. It is an example of the screen display at the time of displaying sampling data and teaching data of a work program on a teach pendant. It is a flowchart for demonstrating the flow of a process of a position reproduction part. It is an example of a screen display when only sampling data that deviates from a predetermined allowable range is extracted and displayed. It is a block diagram of the conventional arc welding robot apparatus which samples and preserve | saves an actual welding condition value for every predetermined period.

  Embodiments of the present invention will be described based on examples with reference to the drawings.

  FIG. 1 is a block diagram of an arc welding robot apparatus 1 according to the present invention. As shown in the figure, the arc welding robot device 1 is roughly constituted by a manipulator M, a robot control device RC, a teach pendant TP, and a welding power source WP. The manipulator M, teach pendant TP, and welding power source WP are the same as those in FIG. Further, the current detector, voltage detector, low-pass filter, A / D converter, and the like for sampling the actual welding condition values described in FIG. 7 are incorporated in the welding power source WP, and are the same as in the prior art. The sampled actual welding condition value is input to the robot controller RC as a digital value. Hereinafter, a robot controller RC different from FIG. 7 will be described.

  The robot controller RC controls the operation of the manipulator M and gives a control signal to the welding power source WP. The CPU 2, the ROM 3, the RAM 4, the hard disk 5, the TP interface 10, the WP interface 11, the system timer 6, Each unit includes a drive command unit 30 and a servo driver (not shown), which are connected via a bus (not shown).

  The ROM 3 includes a program editing processing unit 7 that edits a work program based on an input from the teach pendant TP and saves it in the work program storage unit 12, a program execution unit 8 that interprets and executes the created work program, and a manipulator Control software for performing various controls, such as an operation control unit 9 for performing M operation control, is provided.

  The ROM 3 further includes a data storage unit 23, a display output unit 22, a position reproduction unit 24, and a determination unit 25. The data storage unit 23 stores, in the sampling data storage unit 13, position specifying information Id for specifying the sampling position together with the actual welding condition value Wd input from the welding power source WP. The display output unit 22 outputs the actual welding condition value Wd and the position specifying information Id as sampling data to the teach pendant TP. The position reproduction unit 24 specifies the sampling position based on the position specifying information Id selected by the teach pendant TP during the teaching mode after the welding operation is completed, and moves the arc welding torch T to the specified sampling position. Then, processing for reproducing the position and orientation during the welding operation is performed. Determination unit 25 determines whether or not actual welding condition value Id deviates from a predetermined allowable range value. Details of the data storage unit 23, the display output unit 22, the position reproduction unit 24, and the determination unit 25 will be described later.

  The RAM 4 is used as a working area for the CPU 2 and temporarily stores data being calculated. The hard disk 5 has a work program storage unit 12 that stores a work program in which the work of the manipulator M is taught, and a sampling data storage unit 13 that stores actual welding condition values Wd and position specifying information Id as sampling data. ing. The system timer 6 measures the current system time, and is referred to when a time stamp such as a work program creation date is given. The WP interface 11 is an interface for connecting and communicating with the welding power source WP.

  The activation box SB is used to input an activation signal for performing a reproduction operation of the taught work program to the robot controller RC.

  When an activation signal is input from the activation box SB, the program execution unit 8 interprets the contents of the work program stored in the work program storage unit 12, and the operation control unit 9 performs operations such as trajectory planning. Based on the above, the drive command unit 30 outputs an operation control signal to each servo motor of the manipulator M. As a result, the plurality of axes of the manipulator M rotate and reach each taught point sequentially.

  Next, details of each part of the data storage unit 23, the display output unit 22, the position reproduction unit 24, and the determination unit 25 will be described by giving teaching examples.

  First, the data storage unit 23 will be described. The data storage unit 23 stores, in the sampling data storage unit 13, position specifying information Id for specifying the sampling position together with the actual welding condition value Wd input from the welding power source WP.

  FIG. 2 is a teaching example for explaining the position specifying information stored by the data storage unit. FIG. 5A shows a plurality of teaching points for performing a welding operation. In FIG. 5A, the work original position Sp is the start position of the work process. The welding start position As is a position where the welding operation is started. The welding end position Ae is a position at which the welding operation is ended. The work end position Ep is the end position of the work process. A portion surrounded by the welding start position As and the welding end position Ae is a work section in which arc welding is performed on the workpiece W, and is hereinafter referred to as a welding section. The sampling position Dn is a position where the welding power source WP samples actual welding conditions. This sampling position is determined according to a predetermined cycle (hereinafter also referred to as a sampling cycle) in the welding power source WP.

  FIG. 5B shows an example of teaching the work program shown in FIG. In FIG. 5B, “work program number” is identification data for identifying a work program, and for example, a 4-digit number is set in advance. The “step number” is a number automatically assigned to the teaching point, and is incremented by 1 every time the teaching point is stored starting from 001. In the teaching example, the work original position Sp shown in FIG. 9A corresponds to step 001, the welding start position As corresponds to step 002, the welding end position Ae corresponds to step 003, and the work end position Ep corresponds to step 004. ing.

  The “move command” is a command for moving the manipulator M to each teaching point. For example, if it is a JOINT command, a PTP operation is performed to the work location, and if it is a LINE command, a linear interpolation operation is performed to the teaching point. The “work command” is a command for causing the manipulator M to execute arc welding, signal input / output with an external device, and the like. For example, if it is an ArcStart command, arc welding is started at the teaching point, and if it is an ArcEnd command, arc welding is ended at the teaching point.

  When the regenerating operation of the work program described above is performed and arc welding is started in the welding section, the welding power source WP samples actual welding conditions at predetermined intervals and outputs the actual welding condition values Wd to the robot controller RC. The data storage unit 23 stores, in the sampling data storage unit 13, position specifying information Id for specifying the sampling position together with the actual welding condition value Wd input from the welding power source WP.

  FIG. 3 is an example of data when actual welding condition values are stored in the robot controller. As shown in the figure, the work program number for identifying the work program as the position specifying information Id for specifying the sampling position Dn together with the actual welding condition value Wd (actual welding current value and / or actual welding voltage value), The welding start step number for starting the welding operation and the sampling number of the actual welding condition value Wd are stored. The sampling number starts from 1 for each welding section and is incremented by 1 for each sampling. If another different welding section exists, the counting starts again from 1. Instead of storing the work program number and the welding start step number, the position and orientation data of the welding start position As shown in FIG. 2 may be stored.

  Next, the display output unit 22 will be described. The display output unit 22 outputs the actual welding condition value Wd and the position specifying information Id as sampling data to the teach pendant TP.

  When the operator performs a predetermined operation in the teaching mode after the welding operation is completed, the display output unit 22 outputs the actual welding condition value Wd and the position specifying information Id to the teach pendant TP. The display output unit 22 may be configured to output and display only the sampling data on the teach pendant TP. However, it is preferable to output and display the teaching data of the work program simultaneously with the sampling data.

  FIG. 4 is an example of a screen display when the sampling data and the teaching data of the work program are simultaneously displayed on the teach pendant TP. In the figure, a program monitor Pm displayed in the upper half of the screen displays teaching data of a reproduced work program. The welding result monitor Wm displayed in the lower half of the screen displays sampling data, and the teaching value, actual welding condition value, sampling number, and the like of each welding condition are displayed.

  The cursor bar Cr is for the operator to select each step of the work program. The next feed button Nb is for advancing and displaying the sampling data displayed on the welding result monitor Wm in the welding progress direction. Conversely, the forward feed button Pb is for returning the sampling data displayed on the welding result monitor Wm to the direction opposite to the welding progress direction and displaying it. The movement button Mb is a button for moving the arc welding torch T to the acquisition position of the sampling data selected and displayed. The out-of-range list button Hb is a button for selecting and displaying only sampling data that deviates from a predetermined allowable range value. The next feed button Nb, the forward feed button Pb, the move button Mb, and the out-of-range list button Hb are software keys that are displayed on the screen and perform predetermined processing when pressed. However, a teach pendant keyboard can be used instead. You may do it.

  In the above, the program monitor Pm and the welding result monitor Wm are output and displayed when the operator performs a predetermined operation in the teaching mode after the welding operation is completed. Instead, the welding result monitor Wm may be automatically output and displayed when the operator operates the program monitor Pm and moves the cursor bar Cr to the step of the welding section.

  Next, the position reproduction unit 24 will be described. The position reproduction unit 24 specifies the sampling position based on the position specifying information Id selected when the movement button Mb is pressed, and moves the arc welding torch T to the specified sampling position to perform the welding operation. Processing for reproducing the position and orientation is performed.

  FIG. 5 is a flowchart for explaining the processing flow of the position reproduction unit 24.

  In step S1 in the figure, the work program number, welding start step number, and sampling number of the sampling data selected and displayed are read out.

  In step S2, the position and orientation data of the welding start position is read from the work program and the welding start step number. If the position / posture data of the welding start position As is stored instead of storing the work program number and the welding start step number, the stored position / posture data is simply replaced with the above processing. It is only necessary to read the data.

  In step S3, the movement elapsed time from the welding start position is calculated based on the sampling number and the sampling period, and the sampling position is specified. For example, if the sampling number is 100 and the sampling period is 50 [msec], the movement elapsed time from the welding start position is 100 × 50 [msec] = 5 [sec]. That is, the position and orientation data at the sampling position can be calculated by calculating the motion trajectory after 5 seconds have elapsed from the welding start position.

  In step S4, the position / posture data of the sampling position is notified to the operation control unit as the movement target position. Through the above steps, the arc welding torch T can be moved to the position of the sampling data selected by the teach pendant.

  In the above description, sampling data is selected by the next feed button Nb or the forward feed button Pb shown in FIG. 4, and the arc welding torch T is moved to the sampling position selected by the movement button Mb. Even if the move button Mb is not pressed, the arc welding torch T may be moved immediately to the sampling position when the sampling data is selected by the next feed button Nb or the forward feed button Pb.

  Next, the determination unit 25 will be described. Determination unit 25 determines whether or not actual welding condition value Wd deviates from a predetermined allowable range value. Then, the display output unit 22 displays only sampling data that deviates from the allowable range value according to the determination result of the determination unit 25.

  When the out-of-range list button Hb described in FIG. 4 is operated, the determination unit 25 refers to all sampling data and compares the actual welding condition value Wd with a predetermined allowable range value. Then, sampling data determined to have deviated is extracted and temporarily stored in the RAM 4. The display output unit 22 outputs and displays the sampling data temporarily stored in the RAM 4 on the teach pendant TP.

  FIG. 6 is an example of a screen display when only sampling data that deviates from a predetermined allowable range is extracted and displayed. As shown in the figure, only sampling data that deviates from the allowable range is displayed. The forward feed button Pb, the next feed button Nb, and the movement button Mb are the same ones given the same reference numerals as those in FIG. That is, when the sampling data is selected with the cursor bar Cr and the move button Mb is pressed, the arc welding torch T can be moved to the position of the selected sampling data. The return button Bb is a button for returning to the screen described with reference to FIG.

  As described above, in the teaching mode after completion of the welding operation, the sampling position of the actual welding condition value is specified, and the arc welding torch can be moved to the specified sampling position. That is, by making it possible to reproduce the position and orientation during welding work later, for example, when the actual welding condition value deviates from the allowable range, the state of the workpiece or the position and orientation of the robot, which is the cause, You can check against

  Further, the work program number, the welding start step number, and the sampling number are used as the position specifying information for specifying the sampling position. If only the sampling position is specified, it is conceivable to store the position and orientation data at the time of sampling together with the actual welding condition value. However, for example, in the case of a 6-axis manipulator, it is necessary to store each axis data for 6 axes as position and orientation data, and there is a possibility that the data size becomes enormous. By using the work program number, the welding start step number, and the sampling number as the position specifying information, it is possible to suppress an enormous increase in data size in addition to the above effects.

  Further, the welding start position is calculated based on the work program number and the welding work step number, and the sampling position is specified by further calculating the moving distance from the welding start position based on the sampling number and a predetermined cycle. . Thus, in addition to the above effects, the sampling position can be calculated by a very simple method.

  Further, by determining whether or not the actual welding condition value deviates from a predetermined allowable range value, only the actual welding condition value and position specifying information deviating from the allowable range value are displayed. In addition to the above effects, the location where the actual welding condition value deviates from the allowable range can be easily identified.

  In addition to the above effects, the point where the actual welding condition value deviates from the allowable range can be identified more easily by displaying the teaching data of the work program on the teach pendant simultaneously with the sampling data. Can do.

Ae Welding end position As Welding start position Bb Return button Cr Cursor bar Dn Sampling position Ep Work end position Hb Out-of-range list button Id Position specifying information M Manipulator Mb Move button Mc Operation control signal Nb Next forward button Pb Forward button Pm Program monitor RC Robot control device SB Start box Sp Work position T Arc welding torch TP Teach pendant W Work Wd Actual welding condition value Wm Welding result monitor WP Welding power source 1 Arc welding robot device 5 Hard disk 6 System timer 7 Program editing processing unit 8 Program execution Unit 9 Operation control unit 10 TP interface 11 WP interface 12 Work program storage unit 13 Sampling data storage unit 22 Display output unit 23 Data storage unit 24 Position reproduction unit 25 Judgment unit 30 Command section 50 arc welding robot system 51 CPU
52 Storage Unit 54 Current Detector 55 Voltage Detector 56 Low Pass Filter 58 Converter

Claims (4)

The arc welding torch attached to the robot is moved according to the work program taught in advance by the teach pendant to execute the welding work, and during this welding work, at least one of the actual welding current value and the actual welding voltage value is measured. In a control device for an arc welding robot having a data storage unit that samples and stores welding condition values at predetermined intervals,
The data storage unit stores position specifying information for specifying a sampling position of the actual welding condition value together with the actual welding condition value,
A display output unit for displaying the actual welding condition value and the position specifying information as sampling data on the teach pendant;
During the teaching mode after the welding operation is completed, the sampling position is specified based on the position specifying information selected by the teach pendant, the arc welding torch is moved to the specified sampling position, and the welding is performed. A position reproduction unit that reproduces the position and orientation during work ,
The display output unit displays teaching data of the work program on the teach pendant simultaneously with the sampling data,
The control apparatus for an arc welding robot, wherein the position reproduction unit moves the arc welding torch to the sampling position when the sampling data is selected by sampling data selection means provided in the teach pendant .   2. The arc welding robot apparatus according to claim 1, wherein the position specifying information includes a work program number for specifying the work program, a welding start step number for starting a welding work, and a sampling number for the actual welding condition value. .   The position reproduction unit calculates a welding start position based on the work program number and the welding operation step number, and further calculates a moving distance from the welding start position based on the sampling number and the predetermined period. The control apparatus for an arc welding robot according to claim 2, wherein the sampling position is specified.   A determination unit configured to determine whether the actual welding condition value deviates from a predetermined allowable range value; and the display output unit deviates from the allowable range value according to a determination result of the determination unit. The control apparatus for an arc welding robot according to any one of claims 1 to 3, wherein the actual welding condition value and the position specifying information are displayed.

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