JP6580438B2 - Exchange information output device - Google Patents

Description

  The present invention relates to an exchange information output device that outputs information related to exchange of an exchange object in a welding torch of a welding robot.

  A power supply tip (welding tip) used in a welding torch of a welding robot is worn due to friction with a welding wire or deformation due to heat during power supply during welding. The worn power supply tip has a change in the shape of the tip, which causes a change in the power supply position and a change in the target position of the wire, which is one of the factors that deteriorate the welding quality. Therefore, it is necessary to periodically replace the power supply chip. However, there is a problem that it is difficult to grasp the appropriate replacement time of the power supply chip. For example, if the power supply tip is replaced at a time that does not affect the welding quality, the replacement time will be too early, and the cost of the power supply tip will increase unnecessarily. On the other hand, if the worn power supply tip is continuously used due to cost reduction, it may cause poor welding.

  As a related technology, when the power supply tip is replaced, the arc tip time, the number of arc starts, and the total wire supply amount, which are consumption factors of the power supply tip, are integrated for each welding end, and when a predetermined threshold value is reached, There is a technique for automatically replacing a power feed chip (see, for example, Patent Document 1).

JP 7-116841 A

  However, in the technique of the above-mentioned Patent Document 1, if the arc-on time, the number of arc starts, and the like increase, the degree of wear of the power supply tip will increase, and replacement is performed using the arc-on time, the number of arc starts, etc. Since the timing is determined, the determination may not be appropriate. For example, when welding with a large degree of wear of the power feed tip is repeated, wear of the power feed tip becomes more intense than when the welding is not performed. It may be later than the replacement time. On the other hand, when welding with a small degree of wear of the power feed tip is performed, the determination of the replacement time may be earlier than the original replacement time. As described above, in the determination of the replacement time described above, there is a problem that it is difficult to replace the power supply tip in a timely manner because the determination is not made by detecting the degree of wear.

  Generally speaking, there has been a desire to be able to replace a replacement object such as a power supply tip used in a welding torch of a welding robot in a timely manner.

  The present invention has been made to solve the above problems, and provides an exchange information output device capable of outputting exchange information, which is information for timely exchange of an exchange object used in a welding torch of a welding robot. The purpose is to do.

In order to achieve the above object, an exchange information output device according to the present invention is acquired by a current voltage acquisition unit that acquires a current and a voltage during welding in a welding robot having a welding torch for each acquisition period, and a current voltage acquisition unit. A representative value calculation unit that calculates a current representative value and a voltage representative value that are representative values for each acquisition period of the current and voltage, and a plurality of latest current representative values and voltage representative values calculated by the representative value calculation unit When the current representative value and the voltage representative value show a negative correlation, an exchange information obtaining unit for obtaining exchange information regarding the exchange of the exchange object in the electrode part of the welding torch, and an output unit for outputting the exchange information , With.
As will be described later, when wear of an object to be replaced begins, the current representative value and the voltage representative value show a negative correlation, so that such a negative correlation is detected by such a configuration. Thus, when the replacement object is worn, replacement information is output. In other words, since the replacement information is output after grasping that the replacement object is worn, more accurate replacement information can be output. Therefore, for example, by exchanging the power supply chip or the like that is the replacement object in accordance with the output of the exchange information, the power supply chip or the like can be replaced in a timely manner.

  In the exchange information output apparatus according to the present invention, the representative value may be an average value or an intermediate value.

In the exchange information output device according to the present invention, the current voltage acquisition unit may acquire a current and a voltage at the time of welding with respect to a predetermined welding location.
With such a configuration, since current and voltage at the same welding location are acquired, more appropriate replacement information can be acquired than when replacement information is acquired using current and voltage at different welding locations. . Moreover, acquisition of more appropriate replacement information can be realized by acquiring the current and voltage at a welding location appropriate for acquiring the relationship between current and voltage.

Further, in the exchange information output device according to the present invention, the exchange information acquisition unit determines that the current representative value and the current representative value are the current representative value when one of the current representative value and voltage representative value is decreased and the other is increased. It may be determined that the voltage representative value shows a negative correlation.
With such a configuration, it is possible to determine whether or not both representative values show a negative correlation by observing the tendency of increase or decrease in the current representative value or voltage representative value.

Further, in the exchange information output device according to the present invention, the exchange information acquisition unit provides exchange information for instructing exchange when at least one of the latest current representative value and voltage representative value is out of a predetermined range. You may get it.
With such a configuration, for example, by exchanging a replacement object such as a power feed tip according to the output of the exchange information, it is possible to avoid poor welding due to continued use of the worn power feed tip or the like. It becomes like this.

In the exchange information output device according to the present invention, the exchange information acquisition unit includes exchange information including a remaining amount of use of the exchange object until at least one of the current representative value and the voltage representative value is out of a predetermined range. May be obtained.
With such a configuration, it is possible to know the remaining usage amount of the replacement object currently in use. As a result, for example, a new replacement object can be prepared in advance.

Further, in the exchange information output device according to the present invention, the exchange information acquisition unit is configured such that the current representative value and the voltage representative value are negative when the correlation coefficient between the latest plurality of current representative values and voltage representative values is negative. You may judge that it shows a correlation.
With such a configuration, it is possible to determine whether or not both representative values show a negative correlation using the latest correlation coefficients of the current representative values and voltage representative values.

In the exchange information output device according to the present invention, the exchange information acquisition unit may acquire exchange information instructing exchange when the correlation coefficient is smaller than a predetermined threshold.
With such a configuration, for example, by exchanging a replacement object such as a power feed tip according to the output of the exchange information, it is possible to avoid poor welding due to continued use of the worn power feed tip or the like. It becomes like this.

Further, in the exchange information output device according to the present invention, the exchange object is a power supply tip, the welding robot has a power supply tip automatic changer, and the output unit may output the exchange information to the automatic changer. Good.
With such a configuration, it becomes possible to automatically replace the power supply chip according to the output of the replacement information.

Further, in the exchange information output device according to the present invention, the exchange information acquisition unit includes the remaining use amount of the exchange object until the correlation coefficient reaches a predetermined threshold using the latest plurality of correlation coefficients. Exchange information may be acquired.
With such a configuration, it becomes possible to know the remaining usage amount of the replacement object currently in use by using the change with time of the correlation coefficient. As a result, for example, a new replacement object can be prepared in advance.

  According to the exchange information output device of the present invention, it is possible to output exchange information that is information for exchanging an exchange object used in a welding torch of a welding robot in a timely manner. As a result, the replacement object can be replaced in a timely manner, and it is possible to avoid an increase in cost due to the replacement of the replacement object being too early and poor welding due to the replacement of the replacement object being too late.

The figure which shows the structure of the welding robot system which has the exchange information output device by Embodiment 1 of this invention. The figure for demonstrating abrasion of the electric power feeding chip | tip in the embodiment The figure which shows the time-dependent change of the current representative value and the voltage representative value in the same embodiment. The figure which shows the time-dependent change of the current representative value and the voltage representative value in the same embodiment. The figure which shows the relationship between the current representative value and voltage representative value in the embodiment The figure which shows the time-dependent change of correlation coefficients, such as a current representative value, in the same embodiment. The flowchart which shows operation | movement of the exchange information output device by the embodiment

  Hereinafter, an exchange information output apparatus according to the present invention will be described using embodiments. Note that, in the following embodiments, the components given the same reference numerals are the same or equivalent, and repetitive description may be omitted. The exchange information output device according to the present embodiment outputs information related to exchange of the exchange object in the electrode part of the welding torch using the correlation between current and voltage during welding.

  FIG. 1 is a diagram showing a configuration of a welding robot system according to the present embodiment. The welding robot system according to the present embodiment includes a robot control device 1, a welding robot 3, a welding machine 4, a wire feeding device 5, and an input / output terminal 6.

  The welding robot 3 has a plurality of arms connected by joints driven by a drive motor via a reduction gear. The drive motor may include an encoder, and the current position of the drive motor may be detected by the encoder. A welding torch 3 a that performs arc welding on the base material (workpiece) 8 is attached to the tip of the welding robot 3. Then, the welding wire is fed from the wire feeding device 5, and an arc is generated by applying a high voltage between the welding wire at the tip of the welding torch 3 a and the base material 8 by the welding machine 4. When the welding wire and the base material 8 are melted by the heat of the arc, welding to the base material 8 is performed. In addition, the structure of the welding robot 3 is already well-known, The detailed description is abbreviate | omitted. In arc welding, shield gas is generally ejected from the welding torch 3a, but the description of the configuration is omitted. Moreover, in this Embodiment, the case where an exchange target object is the electric power feeding tip used with the welding torch 3a is mainly demonstrated. Further, the welding robot 3 may have a power supply tip automatic changer.

  The welding machine 4 includes a welding power source that supplies a high voltage used in welding to the welding torch 3a and the base material 8, a wire feeding control unit that controls feeding of the welding wire by the wire feeding device 5, and the robot control device 1. A welding control unit for controlling the welding power source is provided in accordance with the welding conditions transmitted from. In addition, the structure of the welding machine 4 is already well-known, The detailed description is abbreviate | omitted.

  The input / output terminal 6 is a terminal used for teaching or the like of the welding robot 3 and may pass an operation signal or the like according to the operation of the operator to the robot control device 1. Further, display data may be received from the robot control device 1 and displayed on the display, and selection contents received from the operator in displaying the display data may be passed to the robot control device 1. Note that an operation instruction or the like input from the input / output terminal 6 to the robot control device 1 may be passed to the execution unit 12 via a route (not shown). Further, the input / output terminal 6 may receive settings related to the exchange information output device 2 and perform the settings and the like on the exchange information output device 2 and the like. The setting may be, for example, a setting related to a threshold value described later, a current / voltage acquisition location, or the like. Alternatively, the exchange information output from the exchange information output device 2 may be received and displayed on a display or output from a speaker. The input / output terminal 6 may be a teach pendant, for example.

  Here, before describing the exchange information output device 2, an outline of a method for determining that the power feed tip is worn will be described. When the welding wire passes through the wire insertion hole of the power feed tip or heat during welding, the tip of the power feed tip is worn. Therefore, as shown in FIG. 2A, the protruding length of the welding wire in the worn power supply tip is longer than the protruding length of the welding wire in the new power supply tip. As a result, even when welding is performed under the same welding conditions and in the same position and orientation, welding with a worn power tip reduces the current during welding compared to welding with a new power tip, and voltage Will increase. When the tip of the power feed tip is worn, the diameter of the wire insertion hole of the power feed tip increases at the tip. Therefore, the displacement of the tip of the welding wire in the worn power supply tip is larger than the displacement of the tip of the welding wire in the welding wire in the new power supply tip. When the positional deviation is large, the target of the workpiece becomes large. For example, as shown in FIG. 2 (b), the protruding length of the welding wire in the worn power tip is the welding wire in the new power tip. It may be shorter than the overhang length. As a result, even when welding is performed under the same welding conditions and in the same position / posture, welding using a worn power tip increases current and decreases voltage compared to welding using a new power tip. It will be. Conversely, due to the positional deviation, the protruding length of the welding wire in the worn power supply tip may be longer than the protruding length of the welding wire in the new power supply tip. In that case, as in the case of FIG. 2 (a), even when welding is performed under the same welding conditions and the same position / posture, welding with a worn power tip is different from welding with a new power tip. In comparison, the current decreases and the voltage increases. Thus, when the power feed tip wears, the current decreases and the voltage increases, or vice versa, the current increases and the voltage decreases. That is, it is possible to know that the power feed tip has been worn because the time change between the current and voltage during welding has a negative correlation. In welding using the welding robot 3, since a work program created in advance is normally reproduced repeatedly, at the same welding location of the same work program, the set current and voltage during welding, the position and orientation of the welding torch, The welding speed and the like will be equal, and the current and voltage observed at that location will be substantially equal. Therefore, it is possible to know whether the power supply tip is worn by acquiring the current and voltage of the same welded part and judging whether the temporal transition of both has a negative correlation. Become.

  The robot control device 1 includes a teaching information storage unit 11, an execution unit 12, a servo control unit 13, a welding control unit 14, and an exchange information output device 2. The exchange information output device 2 includes a current voltage acquisition unit 21, a buffer 22, a representative value calculation unit 23, a representative value storage unit 24, an exchange information acquisition unit 25, and an output unit 26.

  The teaching information storage unit 11 stores teaching information. The teaching information may include, for example, information indicating the position of the tip of the manipulator of the welding robot 3, information indicating the position of each drive motor, and the like. It may contain information about. In addition, in the teaching information storage unit 11, information for designating a welding location from which the exchange information output device 2 acquires a current and a voltage during welding may be stored. Information specifying the welding location may be included in the teaching information related to welding, and may be stored in the teaching information storage unit 11 separately from the teaching information. The information specifying the welding location may be input from the input / output terminal 6, for example. The teaching information storage unit 11 can be realized by a predetermined recording medium (for example, a semiconductor memory or a magnetic disk).

  The execution unit 12 controls the position of each drive motor of the welding robot 3 according to the teaching information stored in the teaching information storage unit 11, the operation signal input from the input / output terminal 6, and the like. With this control, the welding torch 3a is moved to a desired position. Specifically, the execution unit 12 may output a position command value, a movement amount, and the like of each drive motor of the welding robot 3 to the servo control unit 13 in accordance with a movement command included in the teaching information. In addition, the execution unit 12 starts and ends welding by the welding machine 4, the output voltage, and feeds the welding wire via the welding control unit 14 according to the teaching information stored in the teaching information storage unit 11. The start and end may be controlled. Further, the execution unit 12 obtains a current or voltage acquisition start instruction when the welding torch 3a enters the welding location in accordance with information specifying the welding location from which the current or voltage during welding is acquired. When the welding torch 3a comes out of the welding location, an instruction to end acquisition of current or voltage may be output to the current / voltage acquisition unit 21.

  The servo control unit 13 receives the position command value and the movement amount of each drive motor of the welding robot 3 from the execution unit 12, receives the current position acquired by the encoder of each drive motor from the welding robot 3, and receives them. By using it, feedback control is performed so that the current position of each drive motor of the welding robot 3 becomes the position indicated by the position command value.

  The welding control unit 14 outputs a current command value and the like to the welding machine 4 according to the welding conditions received from the execution unit 12. Further, in response to an instruction from the execution unit 12, an instruction to start or end the welding wire feeding is output to the welding machine 4.

  The current / voltage acquisition unit 21 acquires a current and a voltage during welding in the welding robot 3 having the welding torch 3a. The current during welding is a current that flows between the welding torch 3a and the base material 8 during welding, and the voltage during welding may be a voltage between the welding torch 3a and the base material 8 during welding. . The current / voltage acquisition unit 21 acquires the current and voltage for each acquisition period. The acquisition period may correspond to, for example, a period during which welding is performed on a predetermined welding location. Specifically, the acquisition period may be a period from when an acquisition start instruction is received from the execution unit 12 until an acquisition end instruction is received. By doing so, the current-voltage acquisition unit 21 acquires the current and voltage at the time of welding to a predetermined welding location. The current / voltage acquisition unit 21 stores the acquired current and voltage in the buffer 22. The current / voltage acquisition unit 21 may store the current and voltage in the buffer 22 in association with the date and time when the current and the like are acquired. The date and time may be acquired from, for example, a calendar unit or a clock unit (not shown).

  In the buffer 22, the current and voltage acquired by the current / voltage acquisition unit 21 are stored. The current and voltage may be deleted after the representative value is calculated by the representative value calculator 23. The storage in the buffer 22 is usually temporary storage in a RAM or the like, but this need not be the case.

  The representative value calculation unit 23 calculates a current representative value and a voltage representative value, which are representative values for each acquisition period of the current and voltage acquired by the current / voltage acquisition unit 21, and accumulates them in the representative value storage unit 24. That is, when the current and voltage corresponding to a certain acquisition period are stored in the buffer 22, the representative value calculation unit 23 reads the current corresponding to the acquisition period from the buffer 22, calculates the current representative value, Alternatively, the voltage representative value may be calculated by reading the voltage corresponding to the acquisition period from the buffer 22. The representative value calculation unit 23 preferably stores the calculated current representative value and the voltage representative value in the representative value storage unit 24 in association with each other. The representative value may be, for example, an average value or a median value (intermediate value). When the current representative value is the average value (median value) of the current, it is preferable that the voltage representative value is also the average value (median value) of the voltage. In addition, when the date and time is associated with the current or the like in the buffer 22, the representative value calculation unit 23 sets the current representative value or the voltage representative value to the date and time corresponding to the current or voltage used in the calculation. You may accumulate | store in the representative value memory | storage part 24 in association.

  The representative value storage unit 24 stores a current representative value and a voltage representative value. By repeating the calculation of the representative current value and the representative voltage value by the representative value calculation unit 23, the representative value storage unit 24 stores a plurality of current representative values and the like. In the representative value storage unit 24, it is preferable that the current representative value and the voltage representative value corresponding to the same acquisition period are stored in pairs. In addition, it is preferable that the representative value storage unit 24 can know the temporal order of the stored current representative value and voltage representative value. The temporal order is a temporal order of current and voltage acquisition periods from which current representative values and voltage representative values are calculated. The storage in the representative value storage unit 24 may be temporary storage in a RAM or the like, or may be long-term storage. The representative value storage unit 24 can be realized by a predetermined recording medium (for example, a semiconductor memory or a magnetic disk).

  When the current representative value and the voltage representative value have a negative correlation with respect to the latest plurality of current representative values and voltage representative values calculated by the representative value calculating unit 23, the exchange information acquisition unit 25 is the electrode of the welding torch. Exchange information relating to the exchange of the exchange object in the department is acquired. In the present embodiment, as described above, a case where the replacement object is a power supply chip will be mainly described. The exchange information may be information instructing exchange of an exchange object, for example. The instruction may be an instruction for a person or an instruction for an automatic switch of a power supply chip. In the former case, the replacement information may be, for example, text information “Please replace the power supply chip”, audio information, audio-video information, or the like. Further, the exchange information that is an instruction to the automatic switch of the power supply chip may be a command instructing replacement of the power supply chip. As such, when the exchange information is information for instructing the exchange of the exchange object, the exchange information acquisition unit 25 may acquire the exchange information by reading the information from a recording medium (not shown). Further, the exchange information may be information including the remaining usage amount of the exchange object, for example. The remaining usage amount may be information indicating a usage period (for example, the remaining one hour) until the replacement target is replaced, and the number of times used (for example, the remaining five times) until the replacement target is replaced. ). The number of times may be, for example, the number of executions of a work program executed by the execution unit 12, or may be the number of times from the start to the end of welding (that is, the number of passes). Other times may be used. As such, when the exchange information is information including the remaining usage amount, the exchange information acquisition unit 25 may acquire the exchange information by calculating the remaining usage amount. Here, as a method for determining whether or not the latest plurality of current representative values and voltage representative values show a negative correlation, (1) a method using time variation of the current representative value and voltage representative value, and (2 ) A method using a correlation coefficient between a current representative value and a voltage representative value will be described. In addition, it can be considered that the determination as to whether or not the latest plurality of representative values show a negative correlation is a determination as to whether or not the replacement object has been worn.

(1) Method using time variation of current representative value and voltage representative value In this case, the exchange information acquisition unit 25 has a plurality of latest current representative values and voltage representative values, one of which has decreased and the other has If it has increased, it is determined that the current representative value and the voltage representative value show a negative correlation. The increase or decrease is an increase or decrease along the time series. That is, the exchange information acquisition unit 25 uses a time series change of the latest plurality of current representative values and a time series change of the latest plurality of voltage representative values, one of which decreases along the time direction, and the other May increase along the time direction, it may be determined that the latest plurality of current representative values and voltage representative values show a negative correlation. Specifically, the exchange information acquisition unit 25 calculates a regression line for each of the latest N current representative values and the latest N voltage representative values, as shown in FIG. When the slope of the regression line is positive and the slope of the other regression line is negative, it is determined that the current representative value and the voltage representative value have a negative correlation. Otherwise, the current representative value It may be determined that the voltage representative value does not show a negative correlation. Note that N is an integer equal to or greater than 2, and the regression line is a regression line related to temporal changes such as current representative values. In FIG. 3, the number of times the current representative value or the like is calculated is used as the time axis (horizontal axis), but the time axis may be, for example, date and time. In addition, the exchange information acquisition unit 25 is a case where the slope of one regression line is a positive value exceeding the first threshold, and the slope of the other regression line is a negative value smaller than the second threshold. , It may be determined that the temporal change of both representative values shows a negative correlation. The first and second threshold values may be determined for each current representative value and voltage representative value. The first threshold value is a positive value, the second threshold value is a negative value, and both threshold values may be stored in a recording medium accessible by the exchange information acquisition unit 25.

  Here, as described above, when it is determined that the current representative value and the voltage representative value indicate a negative correlation, the exchange information acquisition unit 25 acquires the exchange information instructing the exchange of the exchange object. explain. As shown in FIG. 3, the latest current representative value is outside the predetermined range AT1 to AT2, and the latest voltage representative value is outside the predetermined range VT1 to VT2. In such a case, the exchange information acquisition unit 25 may determine that the exchange time has come, acquire the exchange information instructing the exchange to be exchanged, and pass it to the output unit 26. In addition, when the current representative value is within the range of AT1 to AT2 or when the voltage representative value is within the range of VT1 to VT2, it is preferable that these ranges are set so as not to cause welding failure. It is. Further, the exchange information acquisition unit 25 may acquire exchange information instructing replacement to be exchanged when one of the latest current representative value and the latest voltage representative value is out of the range. . In other words, the exchange information acquisition unit 25 may acquire the exchange information instructing the exchange when at least one of the latest current representative value and the latest voltage representative value is out of a predetermined range. Good.

  In addition, as described above, when it is determined that the current representative value and the voltage representative value indicate a negative correlation, the exchange information acquisition unit 25 acquires the exchange information including the remaining usage amount of the exchange object. explain. In this case, it is assumed that the latest N current representative values and voltage representative values are all included in a predetermined range. As shown in FIG. 4, the exchange information acquisition unit 25 obtains the intersection of the upper limit threshold AT2 and the lower limit threshold AT1 of the predetermined range and the regression line for the current representative value, and the time of the intersection The difference from the current time (= C1−C0) is calculated. The difference may be time or number of times. Here, the current time is the time corresponding to the latest current representative value, but this need not be the case. When the horizontal axis is the date and time, for example, the current date and time at the time of calculation may be the current time. Strictly speaking, there are two intersections between the threshold and the regression line, but the exchange information acquisition unit 25 only needs to obtain the intersection in a range larger than the current time. Further, the exchange information acquisition unit 25 performs the same processing for the voltage representative value. As a result, C1-C0, which is an estimation period until the current representative value is outside the predetermined range, and C2-C0, which is an estimation period until the voltage representative value is outside the predetermined range, are obtained. It will be. For example, the exchange information acquisition unit 25 may use the average of both estimation periods as the remaining usage amount of the power supply chip, or may use the shorter period or the longer period as the remaining usage amount of the power supply chip. Then, the exchange information acquisition unit 25 may pass exchange information including the remaining usage amount to the output unit 26. That is, the exchange information acquisition unit 25 acquires exchange information including the remaining usage amount of the exchange object until at least one of the current representative value and the voltage representative value is out of the predetermined range, and outputs it to the output unit 26. You may pass.

  Further, the exchange information acquisition unit 25 may acquire exchange information other than the above description. For example, when it is determined that the current representative value and the voltage representative value show a negative correlation, the exchange information acquisition unit 25 may acquire exchange information indicating that the replacement time of the replacement object is near.

(2) Method of using correlation coefficient of current representative value and voltage representative value In this case, the exchange information acquisition unit 25 determines that the correlation coefficient of the latest plurality of current representative values and voltage representative values is negative. Therefore, it is determined that the current representative value and the voltage representative value show a negative correlation. That is, the exchange information acquisition unit 25 calculates the correlation coefficient for the latest N sets of the current representative value and the voltage representative value, and when the correlation coefficient is negative, the current representative value and the voltage representative value are calculated. And may indicate a negative correlation. N is an integer of 2 or more. For example, when the latest N sets of current representative values and voltage representative values are as shown in FIG. 5, the correlation coefficient is a negative value, and the current representative value and the voltage representative value are negative. It will be judged that a correlation is shown. The exchange information acquisition unit 25 may determine that the current representative value and the voltage representative value indicate a negative correlation when the correlation coefficient is less than 0, and the threshold value TH0 where the correlation coefficient is less than 0. If it is less than the value, it may be determined that the current representative value and the voltage representative value show a negative correlation.

  Here, as described above, when it is determined that the current representative value and the voltage representative value indicate a negative correlation, the exchange information acquisition unit 25 acquires the exchange information instructing the exchange of the exchange object. explain. If the correlation coefficient is smaller than a predetermined threshold TH, the exchange information acquisition unit 25 may determine that the exchange time has come, acquire the exchange information instructing the exchange, and pass it to the output unit 26. The threshold value is a negative value greater than -1. This is because the correlation coefficient takes values from −1 to 1. The threshold value TH may be stored in a recording medium accessible by the exchange information acquisition unit 25. When the correlation coefficient is larger than the threshold value TH, it is preferable to set the threshold value TH so that welding failure does not occur. Further, when the correlation coefficient is equal to the threshold value TH, it may be determined that the replacement time has arrived or not. Normally, threshold value TH <threshold value TH0.

  In addition, as described above, when it is determined that the current representative value and the voltage representative value indicate a negative correlation, the exchange information acquisition unit 25 acquires the exchange information including the remaining usage amount of the exchange object. explain. In this case, it is assumed that the correlation coefficient calculated using the latest N current representative values and voltage representative values is larger than the threshold value TH. When obtaining the remaining usage amount, the exchange information acquisition unit 25 stores the correlation coefficient and the time corresponding to the correlation coefficient in association with each other, every time the correlation coefficient is calculated. . The time corresponding to the correlation coefficient may be, for example, the time corresponding to the latest current representative value used in the calculation of the correlation coefficient. The correlation coefficient and the corresponding time may be stored in the representative value storage unit 24, for example. Then, when the latest correlation coefficient is negative, the exchange information acquisition unit 25 may calculate the remaining usage amount using the latest negative correlation coefficients. Specifically, as shown in FIG. 6, the exchange information acquisition unit 25 calculates a regression line for the latest M negative correlation coefficients, and a time C3 at the intersection of the regression line and the threshold value TH. Is calculated. Then, the exchange information acquisition unit 25 calculates a remaining use amount (= C3-C0) that is a difference between the time of the intersection and the current time, and passes the exchange information including the remaining use amount to the output unit 26. May be. M is an integer of 2 or more. Also here, the current time is the time corresponding to the latest current representative value, but this need not be the case. When the horizontal axis is the date and time, for example, the current date and time at the time of calculation may be the current time.

  Here, the case where it is determined whether or not the latest plurality of representative values show a negative correlation by the methods (1) and (2) has been described. It goes without saying. Further, when the representative current value storage unit 24 does not store N current representative values or voltage representative values, the exchange information acquisition unit 25 uses less than N current representative values or the like to relate to a negative correlation. Processing such as determination may be performed, or the processing may not be performed.

  The output unit 26 outputs the exchange information acquired by the exchange information acquisition unit 25. When the exchange information is a command for the automatic exchange of the power supply chip, the output unit 26 may output the exchange information as the command to the automatic exchange. In addition, when the exchange information is information for instructing a person to exchange the object to be exchanged, that is, when the exchange information is information prompting the exchange of the object to be exchanged, When the amount is included, the output unit 26 may display the exchange information, print it, output it by voice, or send it to a terminal such as an operator.

  In addition, when outputting the exchange information including the used remaining amount, the output unit 26 may output the exchange information including the used remaining amount, for example, only when the used remaining amount is reached. . Specifically, the output unit 26 outputs the replacement information when the remaining usage amount is less than 100 times or less than one hour, and if not, the output information may not be output. For example, if the exchange information acquisition unit 25 acquires only such exchange information, the output unit 26 may output all the exchange information acquired by the exchange information acquisition unit 25.

  Here, the output may be, for example, display on a display device (for example, a liquid crystal display), transmission via a communication line to a predetermined device, printing by a printer, or audio output by a speaker. It may be stored in a recording medium or delivered to another component. When exchange information is stored in a recording medium or delivered to another component, the exchange information that is accumulated or delivered is finally presented to the operator or automatically. It is preferable to be passed to an exchange. The output unit 26 may or may not include a device (for example, a display device or a printer) that performs output. The output unit 26 may be realized by hardware, or may be realized by software such as a driver that drives these devices.

  In addition, although the case where the robot control apparatus 1 has the exchange information output apparatus 2 has been described, this need not be the case. For example, the exchange information output device 2 may exist outside the robot control device 1. In this case, for example, the current / voltage acquisition unit 21 may receive an acquisition start instruction or an acquisition end instruction from the execution unit 12 of the robot control apparatus 1 and may acquire current or voltage using the received instruction. Good.

  Of the teaching information storage unit 11, the buffer 22, and the representative value storage unit 24, any two or more storage units may be realized by the same recording medium or by separate recording media. May be. In the former case, for example, the area storing the teaching information may be the teaching information storage unit 11, and the area storing the current representative value or the voltage representative value may be the representative value storage unit 24.

Next, the operation of the exchange information output device 2 will be described using the flowchart of FIG. In the flowchart, the description of the processing of the robot control device 1 other than the exchange information output device 2 is omitted.
(Step S101) The current-voltage acquisition unit 21 determines whether to acquire a current or a voltage. If it is acquired, the process proceeds to step S102. If not, the process of step S101 is repeated until it is determined that current or the like is acquired. Note that the current voltage acquisition unit 21 may determine to acquire a current or the like when an acquisition start instruction is received from the execution unit 12, for example.

  (Step S <b> 102) The current / voltage acquisition unit 21 acquires current and voltage related to welding and stores them in the buffer 22.

(Step S103) The current / voltage acquisition unit 21 determines whether or not to end the process of acquiring current and the like. If the process is to end, the process proceeds to step S104. If not, the process returns to step S102. Note that the current voltage acquisition unit 21 may determine that the acquisition of the current or the like is to be ended when an acquisition end instruction is received from the execution unit 12, for example.
In step S101, it is determined to acquire current etc., and in step S103, the acquisition of current etc. is continued until it is determined to end the acquisition of current etc. In this case, for example, it is determined in advance. Acquisition of current and the like may be repeated at time intervals.

  (Step S104) The representative value calculation unit 23 calculates a representative value for each of the plurality of currents and the plurality of voltages acquired in step S102, and the representative value storage unit 24 displays the calculated current representative value and voltage representative value. To accumulate.

  (Step S105) The exchange information acquisition unit 25 uses the latest plurality of current representative values and voltage representative values including a newly calculated set of current representative values and voltage representative values, and both representative values are negative. Determine if there is a correlation. For the determination, for example, a temporal change such as a current representative value may be used, or a correlation coefficient such as a current representative value may be used. If both representative values have a negative correlation, the process proceeds to step S106, and if not, the process returns to step S101.

  (Step S106) The exchange information acquisition unit 25 determines whether or not the exchange time for the exchange object has already arrived. For example, the exchange information acquisition unit 25 may perform the determination based on whether or not the latest current representative value or the like is included in a predetermined range, and whether or not the correlation coefficient of the current representative value or the like is smaller than the threshold value TH. You may make that determination. If the replacement time has already arrived, the process proceeds to step S107, and if not, the process proceeds to step S108.

  (Step S <b> 107) The exchange information acquisition unit 25 acquires exchange information for instructing exchange and passes it to the output unit 26.

  (Step S <b> 108) The exchange information acquisition unit 25 calculates the remaining usage amount and passes the exchange information including the remaining usage amount to the output unit 26.

(Step S109) The output unit 26 outputs the exchange information received from the exchange information acquisition unit 25. Then, the process returns to step S101.
In the flowchart of FIG. 7, the case where the processing after step S <b> 105 is performed every time the representative value is calculated has been described, but this need not be the case. For example, the processing after step S105 may be performed at a predetermined timing or at a specific timing such as startup of the robot control apparatus 1.

  Further, in the flowchart of FIG. 7, the case has been described where the replacement information including the remaining amount of use is output every time when it is determined that the replacement time has not come, but this need not be the case. For example, the output of the exchange information including the remaining usage amount may be performed every predetermined period, or may be performed at a specific timing such as start-up of the robot control device 1. In that case, in step S108, the replacement information including the remaining usage amount is accumulated in a recording medium (not shown), and the output unit 26 specifies the predetermined time period or the start-up of the robot control device 1 or the like. At this time, the latest exchange information stored may be read out and output.

  Further, the order of processing in the flowchart of FIG. 7 is an example, and the order of each step may be changed as long as the same result can be obtained. In the flowchart of FIG. 7, the process ends when the power is turned off or the process is terminated.

  Next, the operation of the exchange information acquisition unit 25 according to the present embodiment will be described using a specific example. In this specific example, it is assumed that a specific location in a series of welding processes corresponding to teaching information is set as a location where current and voltage are acquired. And in welding robot 3, the series of welding processes shall be performed repeatedly.

  It is assumed that the execution unit 12 has acquired a preset current or the like when executing a series of welding processes according to the teaching information. Then, the execution unit 12 passes an acquisition start instruction to the current / voltage acquisition unit 21. When receiving the acquisition start instruction, the current / voltage acquisition unit 21 starts acquiring the current and voltage during welding, and accumulates the acquired current and voltage in the buffer 22 (steps S101 to S103). Thereafter, when the welding process proceeds to the end point of the acquisition location such as current, the execution unit 12 passes an acquisition end instruction to the current voltage acquisition unit 21. When receiving the acquisition end instruction, the current / voltage acquisition unit 21 ends the acquisition of the current and voltage during welding, and passes an instruction to calculate the representative value to the representative value calculation unit 23 via a path (not shown) ( Step S103). When receiving the instruction, the representative value calculation unit 23 reads a plurality of currents from the buffer 22 and calculates a current representative value. The representative value calculation unit 23 reads a plurality of voltages from the buffer 22 and calculates a voltage representative value. Then, the representative value calculation unit 23 accumulates both representative values in the representative value storage unit 24 in association with the number of calculation of the representative value at that time, and erases all currents and voltages stored in the buffer 22. At the same time, an instruction to determine whether there is a negative correlation is passed to the exchange information acquisition unit 25 via a route (not shown) (step S104). When receiving the instruction, the exchange information acquisition unit 25 determines whether or not they have a negative correlation using the latest plurality of current representative values and voltage representative values (step S105). In this case, it is assumed that both have no negative correlation. Then, exchange information is not acquired, and acquisition of current and voltage and calculation of current representative value and voltage representative value are repeated until it is determined that there is a negative correlation (steps S101 to S104). .

  Thereafter, the welding process is repeated, and the exchange information acquisition unit 25 determines that the latest plurality of current representative values and voltage representative values have a negative correlation (step S105). Then, the exchange information acquisition unit 25 determines whether or not the exchange time has come (step S106). In this case, it is assumed that the replacement time has not yet arrived. Then, the exchange information acquisition unit 25 acquires the exchange information including the remaining usage amount and passes it to the output unit 26 (step S108). Then, the output unit 26 outputs the exchange information to, for example, the input / output terminal 6 (step S109). In this way, the operator of the welding robot 3 can know the scheduled replacement time of the power feed tip.

  Thereafter, the welding process is further repeated, and it is assumed that the replacement information acquisition unit 25 determines that the replacement time has come (step S106). Then, the exchange information acquisition unit 25 acquires exchange information including an instruction to replace the power supply chip, and passes it to the output unit 26 (step S107). Then, the output unit 26 outputs the exchange information to, for example, the input / output terminal 6 (step S109). In this way, the operator of the welding robot 3 can know that the power supply tip must be replaced. When the power supply chip is replaced according to the output, the operator or the like may input to the replacement information output device 2 via the input / output terminal 6 or the like that the power supply chip has been replaced. Upon receipt of the input, the exchange information output device 2 may erase all the information stored in the buffer 22 and the representative value storage unit 24 and reset the counter for calculating the representative value. In this way, a new determination is started for the replaced power supply chip.

  As described above, according to the exchange information output device 2 according to the present embodiment, it can be determined using the current and voltage that the power feed tip is actually worn. For this reason, for example, it is possible to more accurately determine the replacement timing of the power supply tip than based on the arc-on time, the number of arc starts, the total wire supply amount, and the like. As a result, the replacement information output from the replacement information output device 2 can be used to replace the power supply chip in a timely manner, thereby reducing the cost associated with the replacement of the power supply chip and reducing the worn power supply chip. It is possible to achieve both suppression of welding failure caused by continuing. When exchange information instructing exchange is output, the exchange is performed automatically or manually according to the output of the exchange information, thereby enabling timely exchange. In addition, when replacement information including the remaining usage amount is output, a power supply chip for replacement can be prepared according to the output of the replacement information, and timely replacement is realized according to the remaining usage amount. You can also In addition, by acquiring the current and voltage at the predetermined welding location in the work program, the current and voltage acquired for each acquisition period correspond to welding under the same conditions. As a result, it is possible to make a more appropriate determination whether the determination is performed using the temporal change of the representative value or the determination is performed using the correlation coefficient of the representative value. .

  In the present embodiment, the case where the replacement object is a power supply tip used in welding using a consumable electrode has been described, but this need not be the case. The replacement object may be a non-consumable electrode in welding using a non-consumable electrode. For example, the replacement object may be a TIG electrode used in TIG (Tungsten Inert Gas) welding. Also in the case of the TIG electrode, the distance to the workpiece becomes longer due to wear of the tip. Therefore, in welding using a worn TIG electrode, the current decreases and the voltage increases compared to welding using a new TIG electrode. That is, also in this case, since the time change between the current and the voltage during welding has a negative correlation, the replacement timing of the TIG electrode should be determined in the same manner as in the case of using the above-described consumable electrode. Can do. When the replacement object is a non-consumable electrode such as a TIG electrode, the current increases according to the wear of the electrode and the voltage does not decrease. In the determination using, the exchange information acquisition unit 25 has a negative correlation between the current representative value and the voltage representative value when the latest plurality of current representative values have decreased and the voltage representative value has increased. It is sufficient to determine that In addition, regarding the range for determining whether the latest current representative value or the latest voltage representative value is included, the current representative value may be a range in which only the lower limit is determined, and only the upper limit for the voltage representative value. As long as the range is fixed. When the replacement object is a non-consumable electrode such as a TIG electrode, the welding robot 3 is a welding robot that performs welding using a non-consumable electrode such as TIG welding. In that case, the welding robot 3 may not be provided with the wire feeding device 5, or the wire feeding device 5 may feed the filler wire.

  Moreover, although the said description demonstrated the case where both an electric current and a voltage were acquired in the acquisition period corresponding to the welding location decided beforehand, it may not be so. For example, a current may be acquired in an acquisition period corresponding to a certain welding location, and a voltage may be acquired in an acquisition period corresponding to another welding location. In that case, the acquisition period for acquiring the current and the acquisition period for acquiring the voltage are determined, the current is acquired for each acquisition period, and the voltage is acquired for each acquisition period. become. Note that the processing after the acquisition is performed in the same manner as described above.

  In the above description, the case where the current and voltage are acquired each time the work program is executed has been described, but this need not be the case. For example, current and voltage may be acquired every time the work program is executed a predetermined number of times. More specifically, the current and voltage may be acquired in one acquisition period in a period in which the work program is executed K times. K is an integer of 2 or more. In that case, it can be said that the current and voltage acquisition period is a period corresponding to a predetermined welding location in the work program every predetermined number of times. Further, in one work program, there may be a plurality of current and voltage acquisition periods. In that case, it is preferable to calculate the above-described representative value for each acquisition period in the work program. Specifically, when the period corresponding to the first welding spot in the work program is the first acquisition period and the period corresponding to the second welding spot is the second acquisition period, the first The representative value may be calculated using the current acquired during the acquisition period, and the representative value may be calculated using the current acquired during the second acquisition period. In subsequent exchange information acquisition processing, the representative values of both periods may be used together, or exchange information may be acquired for each of the first and second acquisition periods. In the latter case, for example, the remaining usage amount acquired for the first acquisition period may be different from the remaining usage amount acquired for the second acquisition period. Exchange information including the remaining amount of use (that is, exchange information with an early replacement time) may be output. One acquisition period may include a plurality of periods. Specifically, one acquisition period may include a period corresponding to the first welding spot and a period corresponding to the second welding spot in a certain work program. In that case, one current representative value and voltage representative value are calculated for the current and voltage acquired in both periods. Also, welding may be unstable near the start of welding or near the end of welding, that is, near both ends of the welding path. Therefore, in order to avoid the vicinity of the start of welding or the vicinity of the end of welding, the setting may be performed so that the welding location near the center of the path becomes the current or voltage acquisition period.

  In the above description, the case where the regression line is calculated has been mainly described. However, instead of the regression line, a regression curve may be used. For example, such a regression curve may be used when a curve can be fitted with higher accuracy than a straight line.

  In the above embodiment, each process or each function may be realized by centralized processing by a single device or a single system, or may be distributedly processed by a plurality of devices or a plurality of systems. It may be realized by doing.

  In the above embodiment, the information exchange between the components is performed by one component when, for example, the two components that exchange the information are physically different from each other. It may be performed by outputting information and receiving information by the other component, or when two components that exchange information are physically the same, one component May be performed by moving from the phase of the process corresponding to to the phase of the process corresponding to the other component.

  In the above embodiment, information related to processing executed by each component, for example, information received, acquired, selected, generated, transmitted, or received by each component In addition, information such as threshold values, mathematical formulas, setting values, addresses, etc. used by each component in the processing is temporarily or over a long period of time on a recording medium (not shown) even if not specified in the above description. Also good. Further, the storage of information on the recording medium (not shown) may be performed by each component or a storage unit (not shown). Further, reading of information from the recording medium (not shown) may be performed by each component or a reading unit (not shown).

  In the above embodiment, when information used by each component, for example, information such as a threshold value, an address, and various setting values used by each component may be changed by the user, Even if it is not specified in the description, the user may be able to change the information as appropriate, or may not be so. If the information can be changed by the user, the change is realized by, for example, a not-shown receiving unit that receives a change instruction from the user and a changing unit (not shown) that changes the information in accordance with the change instruction. May be. The change instruction received by the receiving unit (not shown) may be received from an input device, information received via a communication line, or information read from a predetermined recording medium, for example. .

  In the above embodiment, when two or more components included in the exchange information output apparatus 2 have communication devices, input devices, etc., the two or more components have a physically single device. Or may have separate devices.

  In the above embodiment, each component may be configured by dedicated hardware, or a component that can be realized by software may be realized by executing a program. For example, each component can be realized by a program execution unit such as a CPU reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory. At the time of execution, the program execution unit may execute the program while accessing the storage unit or the recording medium. The program may be executed by being downloaded from a server or the like, or may be executed by reading a program recorded on a predetermined recording medium (for example, an optical disk, a magnetic disk, a semiconductor memory, or the like). Good. Further, this program may be used as a program constituting a program product. Further, the computer that executes the program may be singular or plural. That is, centralized processing may be performed, or distributed processing may be performed.

  Further, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these are also included in the scope of the present invention.

  As described above, according to the exchange information output device of the present invention, an effect that the exchange information for exchanging the exchange object in a timely manner can be obtained, which is useful, for example, as an apparatus included in the robot control apparatus.

DESCRIPTION OF SYMBOLS 1 Robot controller 2 Exchange information output device 3 Welding robot 3a Welding torch 4 Welding machine 5 Wire feeding device 6 Input / output terminal 11 Teaching information storage part 12 Execution part 13 Servo control part 14 Welding control part 21 Current voltage acquisition part 22 Buffer 23 representative value calculation unit 24 representative value storage unit 25 exchange information acquisition unit 26 output unit

Claims (7)

A current-voltage acquisition unit that acquires current and voltage during welding in a welding robot having a welding torch for each acquisition period;
A representative value calculation unit that calculates a current representative value and a voltage representative value that are representative values for each of the acquisition periods of the current and voltage acquired by the current voltage acquisition unit;
For the latest plurality of current representative values and voltage representative values calculated by the representative value calculation unit, when the current representative value and the voltage representative value show a negative correlation, the replacement object in the electrode part of the welding torch An exchange information acquisition unit for acquiring exchange information related to the exchange;
An output unit for outputting the exchange information ,
The exchange information acquisition unit has a negative correlation between the current representative value and the voltage representative value when one of the latest plurality of current representative values and voltage representative values is decreasing and the other is increasing. The exchange information output device that judges that Said replacement information acquisition unit, at least one of the latest current representative value and the voltage representative value, when it becomes out of the range predetermined, to obtain an exchange information indicating the exchange, exchange information according to claim 1, wherein Output device. Said replacement information acquisition unit, at least one of the current representative value and the voltage representative value, obtains a replacement information comprising the use remaining capacity of the exchange object until the range that is determined in advance, according to claim 1, wherein Exchange information output device. A current-voltage acquisition unit that acquires current and voltage during welding in a welding robot having a welding torch for each acquisition period;
A representative value calculation unit that calculates a current representative value and a voltage representative value that are representative values for each of the acquisition periods of the current and voltage acquired by the current voltage acquisition unit;
For the latest plurality of current representative values and voltage representative values calculated by the representative value calculation unit, when the current representative value and the voltage representative value show a negative correlation, the replacement object in the electrode part of the welding torch An exchange information acquisition unit for acquiring exchange information related to the exchange;
An output unit for outputting the exchange information,
It said replacement information acquisition unit, when the correlation coefficient of the most recent plurality of typical current and voltage representative value is negative, it is determined that the current representative value and the voltage representative value shows a negative correlation, exchange information Output device. The exchange information output device according to claim 4 , wherein the exchange information acquisition unit acquires exchange information instructing exchange when the correlation coefficient is smaller than a predetermined threshold. The replacement object is a power supply chip,
The welding robot has a power supply tip automatic changer,
The output unit outputs the replacement information to the automatic exchange, exchange information output apparatus according to claim 2 or claim 5, wherein. Said switching information acquiring unit, using the latest multiple correlation coefficients, obtains a replacement information comprising the use remaining capacity of the exchange object until the correlation coefficient is predetermined threshold, claim 4 The exchange information output device described.

Images