JP5133079B2 - Welding robot - Google Patents

Description

  The present invention relates to a welding robot, and more particularly, to a welding robot capable of managing a wire feed amount.

  As shown in FIG. 7, in the field of arc welding in which the wire W is fed from the wire reel 100 or the pail pack to the welding torch 110 and the wire is melted with electric energy to perform welding, a wire feeding device 120 is disposed therebetween. The wire W is pulled out from the wire reel 100 or the pail pack and sent to the welding torch 110 for welding. The wire feeding device 120 is equipped with one or two sets of driving rolls (a pair of rolls called a feeding roll and a pressure roll form one pair each). There is a part where the wire is sandwiched between rolls and pulled out by the friction force.

By the way, the following is likely to occur in robot welding.
(1) In a welding method in which high-speed welding or high-speed / low-speed switching is performed, a feeding command to the feeding motor 130 of the wire feeding device changes rapidly, and the load on the feeding motor 130 increases. There is a change in the wire feed speed command for the motor 130.

(2) When the wire W is fed, there is a change in the feeding path friction load in which the wire W is scraped by friction, and the load increases due to accumulation of cutting powder in the feeding path.
(3) In the case of the wire reel 100 on which the wire W is mounted, the load on the feeding motor 130 is large because the wire remaining amount is large and heavy at first. However, welding reduces the remaining amount of the wire W and feeds it. There is a change in the remaining wire amount that the load on the motor 130 is lightened.

  (4) The feeding path changes depending on the operation of the robot, and depending on the welding location, the feeding path may draw a sharp curve, and the feeding load due to the friction generated in this curve increases. There is a change in the route.

When these conditions occur, the load of the feeding motor fluctuates, and this phenomenon is also affected by the stability of the wire feeding speed, and finally the welding quality is affected.
Usually, in order to solve these problems, a wire feeding device using a servo motor with an encoder is used.

As a result, the feeding motor of the wire feeding device 120 is provided with an encoder, the wire feeding amount is measured using pulses fed back from the encoder, and the speed during feeding is monitored. Can be monitored as a load of the feed system. For example, in the welding wire feeding resistance monitoring device of Patent Document 1, the feeding resistance of the welding wire feeding path is measured from the torque information of the servo motor of the wire feeding means, and the feeding resistance is managed. Therefore, preventive maintenance is performed before welding quality is affected. Further, in the consumable electrode arc welding apparatus of Patent Document 2, the wire feeding device is provided with a rotation speed measuring device that detects the motor rotation speed and a current detector that detects the motor current, and the motor load fluctuations and the feeding load are detected. The maintenance time due to the feeding load is judged by estimating the fluctuation. In Patent Document 3, a detection device that detects the wire feeding speed in the middle of the wire feeding path and a comparator that compares the detected feeding speed with a reference value are provided, and an output signal of the comparator is provided. Discloses a welding wire feed control device for stopping a wire feed motor. Further, in the second embodiment of Patent Document 3, the wire feeding is performed according to the comparison result between the wire feeding speed of the motor of the wire feeding device and the wire feeding speed at the upstream position of the wire feeding device. The motor of the device is stopped.
JP 2001-293574 A JP 2002-292466 A JP-A-57-184581

However, even if this servo motor type feeding device is used, it cannot be said to be sufficient to solve these problems for the following reasons.
(1) Even if a servo motor is used, if the load fluctuates and exceeds the friction force of the feed roll / pressure roll, the wire slips.

as a result,
(A) Since the motor rotates, but the wire is not actually sent, an error occurs between the feed amount measured by the encoder feedback of the servo motor and the actually fed wire feed amount.

  (B) Although the motor rotates without fluctuation by encoder feedback control, the feeding speed of the wire sent to the welding torch greatly fluctuates, which adversely affects the welding quality.

  (C) When the wire slips at the roll portion, the load on the motor becomes lighter and the motor current value decreases. For this reason, although the load on the feeding system increases and the wire slips, the feeding system load is erroneously measured, and the wire feeding load cannot be estimated correctly (see Patent Document 2). If).

  In addition, a play portion of the wire may occur in the wire feeding path between the wire feeding device and the welding torch. This play is caused by bending the wire in the gap inside the feeding path, and the wire feeding amount pushed out by the wire feeding device is the same as the wire feeding amount pushed out from the tip of the welding torch. Means not. In particular, in the case of robot welding, the posture of the robot may change, and the feeding path may move greatly, and the fluctuation of the wire may increase at this play portion. As a result, the speed of the wire sent to the welding torch greatly fluctuates and the target position shifts, which affects the welding quality. Thus, on the downstream side of the wire feeder, the amount of wire that is actually fed to the welding torch affects the welding quality.

  Note that Patent Document 1 does not measure the wire feeding speed between the wire feeding unit and the welding torch. Therefore, in Patent Document 1, even if the slip of the wire in the wire feeding unit can be measured, The movement of the wire (for example, the wire feed amount) at a position between the wire feed unit and the welding torch separated from the wire feed unit is not managed. For this reason, welding quality is affected by the movement of the wire between the wire feeding means and the welding torch. Also in Patent Document 2, although the motor load fluctuation and the feeding load fluctuation in the wire feeding device are obtained, the movement of the wire at the position between the wire feeding means and the welding torch which is separated from the wire feeding means ( For example, the wire feed amount) is not managed. For this reason, the welding quality is affected by the movement of the wire between the wire feeding device and the welding torch. In Patent Document 3, the wire feeding speed in the wire feeding device is detected, and the movement of the wire at a position between the wire feeding means and the welding torch separated from the wire feeding means ( For example, the wire feed amount) is not managed. For this reason, there are the same problems as in Patent Documents 1 and 2.

  The object of the present invention is to compare the wire feed amount in the wire feed means with the wire feed amount at the downstream side position of the wire feed device between the wire feed means and the welding torch, and thereby the downstream of the wire feed device. An object of the present invention is to provide a welding robot that can detect an abnormality in feeding of a wire fed to a welding torch on the side and prevent occurrence of a malfunction due to wire feeding.

In order to solve the above-described problems, the invention according to claim 1 is directed to a welding robot including a wire feeding unit that feeds a wire to a welding torch located on the downstream side. A first wire feed amount detecting means for detecting an amount (hereinafter referred to as a first wire feed amount), and a wire feed amount (hereinafter referred to as a second wire feed amount) at a downstream position between the wire feed means and the welding torch. A second wire feed amount detecting means for detecting the wire feed amount), the first wire feed amount and the second wire feed amount are compared, and the wire feed means feeds based on the comparison result. A feeding abnormality judging means for judging a feeding abnormality , wherein the feeding abnormality judging means judges whether or not a difference between the first wire feeding amount and the second wire feeding amount satisfies a first allowable condition; If the first permissible condition is not satisfied, it is determined that the feeding is abnormal If the first permissible condition is satisfied, the welding condition is changed to the second wire feed amount, and the first permissible condition storage means stores the first permissible condition that varies depending on the type of the wire. And an input means for specifying a wire to be used for welding, and the feeding abnormality determination means reads out a first allowable condition according to the specified type of wire from the first allowable condition storage means, The gist of the present invention is a welding robot that is used for determining a feeding abnormality .

According to a second aspect of the present invention, in the first aspect of the invention, the feeding abnormality determination unit includes a change amount appropriateness determination unit that determines whether or not the change amount of the welding condition satisfies a second allowable condition related to the change amount. The change amount appropriateness determining means permits welding under the welding condition with the change amount when the change amount satisfies the second allowable condition, and does not satisfy the second allowable condition. It is characterized by determining that the feeding is abnormal.

The invention of claim 3 comprises, in claim 2 , a second permissible condition storage means for storing a second permissible condition that varies depending on the type of the wire, and an input means for specifying a wire used for welding, The change amount appropriateness determining means reads out the second allowable condition corresponding to the specified type of wire from the second allowable condition storage means and uses it for determining the feeding abnormality.

According to a fourth aspect of the present invention, there is provided the wire feeding means according to any one of the first to third aspects, wherein the welding torch is attached via a support portion provided on a wrist portion of a manipulator of a welding robot. However, the second wire feeding amount detection means is provided on the basis of the measurement means for detecting the feeding amount of the wire and the measurement result of the measurement means. And a calculating means for calculating a supply amount, wherein the measuring means is provided in the support portion.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the wire loading amount storage means for storing the wire loading amount of the wire fed to the welding torch, and the second wire feeding. Wire remaining amount calculating means for calculating the remaining amount of the loaded wire based on the supply amount and the wire loading amount, and determining whether or not to issue a warning regarding the remaining wire amount based on the magnitude of the remaining wire amount It is characterized by comprising warning determination means for performing

The invention of claim 6 is characterized in that, in claim 5 , the warning determination means performs a welding prohibition process when it is determined that there is no remaining wire.

  According to the first aspect of the present invention, the first wire feeding amount in the wire feeding means is compared with the second wire feeding amount in the downstream position of the wire feeding device between the wire feeding means and the welding torch. Thus, it is possible to detect an abnormality in the feeding of the wire fed to the welding torch on the downstream side of the wire feeding device, and to prevent the occurrence of defects due to the wire feeding.

  For example, when the wire feed means drive source (for example, a motor) rotates but the wire is not actually fed, the feed amount (first wire feed amount) measured by the encoder feedback of the servo motor is actually When an error occurs between the wire feed amount (second wire feed amount) fed to the wire, this state can be determined as a wire feed abnormality. In addition, if the feed speed of the wire sent to the welding torch fluctuates greatly even though the drive source (for example, a motor) rotates without fluctuation by encoder feedback control, the welding quality will be adversely affected. However, according to the invention of claim 1, it can be determined as a wire feeding abnormality also in this case. Furthermore, it is possible to predict the wear time of the wire feeding system and to predict the maintenance time of the welding tip, liner tube, and the like.

Also, if the feed abnormality determination means determines an abnormality, it is possible to obtain the upper climate result, when the feeding abnormality determination means determines that satisfies the first permissive second wire feeding It can be welded under welding conditions according to the quantity.

Further , since the feeding abnormality determining means reads the first allowable condition according to the specified wire type from the storage means and uses it for the feeding abnormality determination, the first allowable condition is automatically set according to the wire type. Conditions can be set, and the setting can be relieved.

According to the invention of claim 2 , when the change amount of the welding condition satisfies the second permissible condition, the change amount appropriateness determining means permits welding under the welding condition with the change amount, and performs a new welding. If the welding can be automatically performed under the conditions and the second allowable condition is not satisfied, it is determined that the feeding is abnormal. Therefore, the effect of claim 1 can be achieved.

According to the invention of claim 3 , the change amount appropriateness determining means reads out the second allowable condition according to the specified wire type from the second allowable condition storage means and uses it for the feeding abnormality determination. The second permissible condition can be automatically set according to the type of the item, and the setting can be relieved.

According to the invention of claim 4 , the wire feeding means is integrally provided on the support portion provided on the wrist portion of the manipulator, and the measuring means constituting the second wire feed amount detecting means is provided on the support portion. Therefore, the welding robot can be downsized.

According to the fifth aspect of the present invention, since the warning determination means makes a warning determination on the remaining amount of wire based on the amount of remaining wire, refilling of the wire can be urged when the remaining amount of wire decreases.

According to the sixth aspect of the present invention, the warning determination means performs the welding prohibition process when it is determined that there is no remaining wire, so that the wire welding by the robot can be automatically prohibited.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1A is a system diagram of a welding robot that is an articulated robot, and FIG. 1B is an electrical block diagram of the system. FIG. 2A is a schematic view of the vicinity of the wrist of the manipulator of the welding robot.

  A welding torch 13 is attached to the tip of a wrist portion 12 provided at the end of a manipulator 11 composed of a plurality of arms via a support portion 12a. The welding wire W wound around the wire reel 14 is inserted into the conduit pipe 15 and fed to the welding torch 13 by a wire feeding device 16 as wire feeding means attached to the shoulder portion of the manipulator 11.

  The wire W is guided by the conduit pipe 15 from the wire reel 14 to the wire feeding device 16, and is guided and fed by the one-wire power cable 18 from the wire feeding device 16 to the welding torch 13. Then, electric power is supplied from the welding machine 17 to the welding torch 13 via the one-wire power cable 18. In addition, a command signal is input from the teach pendant 19 to the robot control device 10, and a signal from the robot control device 10 is input to the manipulator 11 to rotate the six axes including the first to sixth axes of the manipulator 11. Thus, the tip position of the welding torch 13 is controlled.

Next, the electrical configuration of the welding robot will be described with reference to FIG.
Although not shown, the robot control apparatus 10 includes a system control unit 10a including a CPU, a work program storage unit 10b for storing a robot work program, a motion control unit 10c for controlling the manipulator 11, a welding control unit 10d, a welding machine 17, and the like. A welding power source interface 10e for communication is provided. The work program storage unit is configured by a storage device that can be written and read, such as a hard disk.

  Teaching data input via the teach pendant 19 is stored in a storage unit (not shown) by the system control unit 10a. The teach pendant 19 includes a display device, a key, a push button, and the like, and the teach pendant 19 corresponds to an input unit.

  The welding machine 17 controls the control device interface 17a that communicates with the welding power supply interface 10e of the robot control device 10, the RAM 17b that stores the initial value of the wire length input from the teach pendant 19, welding conditions, and the like, and the power amplifier 20. The welding condition control unit 17c is provided. Here, the initial value of the wire length is the length of the wire when it is loaded on the wire reel 14, that is, the wire loading amount. The power amplifier 20 is controlled by a welding condition control unit 17c including a CPU and supplies a welding current to the welding torch 13. The RAM 17b has a backup function so that data is not lost even when the power is turned off. The RAM 17b corresponds to a wire loading amount storage unit. The welding machine 17 has a built-in wire feed control device 30. The welding condition control unit 17c of the welding machine 17 outputs a feed command value to the wire feed control device 30, and the wire feed control device 30 performs a motor 22 of the wire feed device 16 described later based on this feed command value. Rotation control.

  The wire feeding device 16 includes a drive roll 24 and a pressure roll 26, and the pressure roll 26 is constantly urged toward the drive roll 24 by a spring (not shown) so that the wire W is sandwiched between both rolls, and the frictional force causes the wire The wire reel 14 is pulled out with the W interposed therebetween. The drive roll 24 is rotationally driven by a motor 22 as a drive source.

  The motor 22 is composed of a servomotor with an encoder. The wire feed control device 30 measures the wire feed amount using the pulse fed back from the encoder and monitors the speed at the time of feed, and detects the motor current of the motor 22. Monitor the load on the delivery system. As shown in FIG. 2A, the wire measuring device 40 includes a measuring unit 42 as measuring means and an arithmetic unit 44 as calculating means. The wire measuring device 40 corresponds to a second wire feed amount detecting means. The measurement unit 42 is provided on the support portion 12 a that supports the welding torch 13. That is, the measurement unit 42 is provided in the vicinity of the welding torch 13 so as to be located downstream of the wire feeding device 16 and upstream of the welding torch 13. The measurement unit 42 is preferably provided as close to the welding torch 13 as possible.

  The measuring unit 42 as the measuring means includes a pair of pressure rolls 42a and 42b. The pressure rolls 42a and 42b are preferably made of a light metal so as not to cause a load on the feeding system, and the encoder itself is preferably one having little inertia. The pressure roll 42a is provided with an encoder, and generates a pulse from the encoder by rotating. Both rolls are biased toward each other by a spring (not shown) so as to sandwich the wire W, rotate when the wire W is fed, and output pulses from the encoder, which are sent to the arithmetic unit 44.

  The arithmetic unit 44 is provided outside the welding machine 17. The arithmetic unit 44 counts the actual wire feed amount (based on the encoder pulse counter 44a that counts pulses from the encoder (not shown) of the pressure roll 42a and the count (integrated value) counted by the encoder pulse counter 44a. That is, a calculation unit 44b that converts the distance) is provided. Further, the arithmetic unit 44 sends the actual wire feed amount (hereinafter, the actual wire feed amount is referred to as the second wire feed amount) calculated by the calculation unit 44b at every predetermined cycle via the transmission / reception unit 44c. It is made to transmit to the supply control apparatus 30 with the same period as the calculation period of the calculating part 44b. The arithmetic unit 44 has a built-in backup function of the encoder pulse counter 44a when the power is turned off, so that the second wire feed amount data is stored even when the power is turned off. The wire feed control device 30 is input from the second wire feed amount (distance) obtained from the computation unit 44 and an encoder (not shown) attached to the motor 22 at the same cycle as the computation cycle of the computation unit 44b. The pulse and the load (motor current) of the feeding system are transmitted to the welding condition control unit 17c.

(Operation of the embodiment)
Next, a control program executed by the welding condition control unit 17c of the welding machine 17 will be described with reference to the flowchart of FIG. In this flowchart, normally, S10 to S22 are repeatedly performed by looping.

  The welding condition control unit 17c counts pulses from the encoder of the motor 22 in S10, and adds this count value to the integrated value obtained in the past loop processing. The integrated value is stored and read out in the RAM 17b having a backup function.

  In S12, the welding condition control unit 17c converts the distance that the driving roll 24 of the wire feeding device 16 has rotated up to this time based on the integrated value newly obtained in S10, and this distance is converted to the first wire. Amount of feed. The first wire feeding amount is a wire feeding amount that is assumed that the driving roll 24 has fed the wire W without slipping.

The welding condition control unit 17c that calculates, that is, detects, the first wire feed amount corresponds to first wire feed amount detection means.
In S14, the welding condition control unit 17c subtracts the second wire feed amount from the initial value of the wire length. And the welding condition control part 17c determines whether the value (subtraction value) obtained by this subtraction is less than a residual amount threshold value. If the subtraction value is smaller than the remaining amount threshold value, the welding condition control unit 17c transmits a warning signal indicating that the remaining wire amount is low to the robot control device 10 via the control device interface 17a in S26. The welding condition control unit 17c corresponds to a warning determination unit. As described above, by accurately managing the amount of wire used and notifying before the wire W runs out, it is possible to prevent a system stoppage during the process. The robot control device 10 receives this and outputs a warning that the remaining amount of wire is low to a display device of the teach pendant 19 or a warning device (not shown) provided in the robot control device 10 to prompt the operator to make up the wires. In addition, the system control unit 10a of the robot control device 10 records the transmitted content as an abnormality in the feeding system in a storage device (not shown).

  In S14, when the subtraction value becomes 0 or a negative value, the welding condition control unit 17c determines that there is no remaining wire, and in S28, the welding condition control unit 17c determines that the remaining wire amount is 0. A warning signal and a welding prohibition signal are transmitted to the robot controller 10 through the controller interface 17a. The robot control device 10 receives this, stops the control by the motion control unit 10c and the welding control unit 10d, compensates for the wire, and prohibits the welding operation until the feeding amount is reset. Therefore, if it is determined in S14 that there is no remaining wire, a welding prohibition process is performed in S28. In addition, the system control unit 10a of the robot control device 10 records the transmitted content as an abnormality in the feeding system in a storage device (not shown).

  In this way, by monitoring the wire feed amount, it is possible to notify the wire replacement time when the remaining wire amount is low, and when it is determined that the remaining wire amount is 0 or less, the welding operation is performed. Stop, that is, prohibit welding. Note that the contents stored in the RAM 17b are backed up in the welding machine 17 even when the power is turned off, and various data such as integrated values are stored even when the welding machine 17 is turned off.

  In S14, when the wire remaining amount exceeds the remaining amount threshold value, the welding condition control unit 17c determines “NO” here, and proceeds to S16. The welding condition control unit 17c corresponds to a wire remaining amount calculating unit.

  In S <b> 16, the welding condition control unit 17 c calculates a comparison difference ΔL between the first wire feed amount and the second wire feed amount acquired from the arithmetic unit 44. This comparison difference ΔL corresponds to a loss in the feeding path. This loss occurs, for example, due to slippage on the drive roll 24 or play in the feed path.

  In S18, the welding condition control unit 17c determines whether or not the comparison difference ΔL is within the first threshold L1 <ΔL <second threshold L2 (setting range). This setting range corresponds to the first allowable condition, and the first threshold value L1 and the second threshold value L2 are input in advance by the teach pendant 19 and stored in the RAM 17b. Here, the RAM 17b corresponds to a first allowable condition storage unit. The first threshold value L1 and the second threshold value L2 are input to the robot control device 10 from the teach pendant 19 as a plurality of sets corresponding to the types of the wires W having different diameters and materials. When the wire W to be used is specifically input via the teach pendant 19, the threshold value of the set corresponding to the specified wire W is automatically selected and used for the determination in S18. In this way, when setting various items of the welding robot, the items to be set can be minimized, and the operator is freed from the troublesome setting.

In S18, the welding condition control unit 17c proceeds to S20 if the comparison difference ΔL is within the first threshold L1 <ΔL <second threshold L2 (setting range), and otherwise proceeds to S30.
In S20, the welding condition control unit 17c changes to a welding condition suitable for the second wire feeding amount. The welding conditions here are, for example, a welding current and a welding voltage. In S22, the welding condition control unit 17c determines whether or not the amount of change in the welding conditions is within the set range. The setting range of S22 corresponds to the second allowable condition. The welding condition control unit 17c corresponds to a change amount appropriateness determining means.

  For example, in the case of the welding current change amount ΔA, it is determined whether or not the change amount ΔA satisfies the third threshold value A1 <ΔA <the fourth threshold value A2. Alternatively, in the case of the change amount ΔV of the welding voltage, it is determined whether or not the change amount ΔV is the fifth threshold value V1 <ΔV <the sixth threshold value V2. Here, the setting range of S22 is input in advance by the teach pendant 19 and stored in the RAM 17b. Here, the RAM 17b corresponds to a second allowable condition storage unit. Specifically, the third threshold value A1, the fourth threshold value A2, the fifth threshold value V1, and the sixth threshold value V2 are a plurality of sets corresponding to the types of the wires W having different diameters and materials. Input to the robot controller 10. When the wire W to be used is specifically input via the teach pendant 19, the threshold value of the set corresponding to the specified wire W is automatically selected and used for the determination in S22. In this way, when setting various items of the welding robot, the items to be set can be minimized, and the operator is freed from the troublesome setting.

  If the change amount is within the set range in S22, the welding condition control unit 17c returns to S10 and controls the power amplifier 20 according to the change amount. In S22, when the welding condition control unit 17c determines that the change amount is not within the set range, in S24, the robot control device 10 issues a warning prompting maintenance of the wire W feeding path via the control device interface 17a. Send to. The robot control device 10 receives this and outputs the warning to a display device of the teach pendant 19 or a warning device (not shown) provided in the robot control device 10 to urge the operator to maintain the wire W feeding path. In addition, the system control unit 10a of the robot control device 10 records the transmitted content as an abnormality in the feeding system in a storage device (not shown). As a result, the comparison difference ΔL is within the set range, but the amount of change in the welding conditions is outside the set range. It encourages maintenance.

In S22, even if the comparison difference ΔL is within the set range in S18, since the change amount of the welding condition is outside the set range, it is determined as a result that the feeding system is abnormal as a result.
In S18, the welding condition control unit 17c determines that the comparison difference ΔL is outside the first threshold value L1 <ΔL <second threshold value L2 (setting range), and when the process proceeds to S30, the welding condition control unit 17c It is determined whether it is within the setting range. This motor load is determined based on the load (motor current) of the feed system transmitted by the wire feed control device 30. The setting range regarding the load of the feeding system is stored in the RAM 17b in advance.

  If the welding condition control unit 17c determines in S30 that the motor load is within the set range, the process proceeds to S24, and if it is determined that the motor load is out of the set range, the process proceeds to S32. In S32, the welding condition control unit 17c determines that an abnormality that requires urgent operation has occurred, and notifies the robot controller 10 of an emergency stop to the robot controller 10 via the controller interface 17a. A warning signal and a stop signal are transmitted. The robot control device 10 receives this and outputs a warning to the effect of an emergency stop to a warning device (not shown) provided in the display device of the teach pendant 19 or the robot control device 10, and the motion control unit 10c and the welding control unit 10d. Stops the control by and prohibits welding work. In addition, the system control unit 10a of the robot control device 10 records the transmitted content as an abnormality in the feeding system in a storage device (not shown).

The welding robot configured as described above can cope with the following cases, for example.
1) In the case of an abnormality requiring a suddenness such as slipping or buckling of the wire, a sudden comparison difference ΔL and a motor load increase. That is, generally, when the rotation of the motor 22 is started, the motor load increases rapidly, but it can be determined that slipping or buckling occurs by simultaneously monitoring the motor load and the wire feed amount. Welding abnormalities due to poor feeding and wire buckling can be prevented in advance.

  2) In the case of a warning caused by slipping of the wire or play in the feeding path, which is presumed to be caused by the posture of the robot. When a comparison difference ΔL or an increase in motor load occurs during the posture of a specific robot, it is possible to take measures such as improving the work program to change the posture of the robot.

  3) Information requiring maintenance such as replacement of the conduit pipe 15 in the feeding route. For example, when no welding abnormality has occurred, but the feeding load increases and slippage within the allowable range occurs regularly. If this information is followed, welding abnormalities due to poor feeding can be prevented in advance.

Now, according to this embodiment, there are the following features.
(1) The welding robot of the present embodiment includes a welding condition control unit 17c (first wire feed amount detection means) that detects a first wire feed amount of a wire feed device 16 (wire feed means), a wire A wire measuring device 40 (second wire feed amount detecting means) for detecting a second wire feed amount at a position on the downstream side between the feeding device 16 and the welding torch 13 is provided. Further, the welding condition control unit 17c of the welding robot compares the first wire feeding amount and the second wire feeding amount as feeding abnormality determining means, and the feeding abnormality of the wire feeding device 16 based on the comparison result. Determine.

  As a result, the welding robot of the present embodiment detects an abnormality in feeding of the wire W fed to the welding torch 13 on the downstream side of the wire feeding device 16, and solves a problem related to welding quality caused by the wire feeding. Occurrence can be prevented.

  For example, when the motor 22 of the wire feeder 16 rotates but the wire W is not actually fed, the first wire feed amount measured by the encoder feedback of the motor 22 is the second wire feed actually fed. If an error occurs between the feed amount and the feed amount, this state can be determined as a wire feed abnormality. In addition, if the feeding speed of the wire W sent to the welding torch 13 fluctuates greatly even though the motor 22 rotates without fluctuation by encoder feedback control, the welding quality will be adversely affected. In this case as well, the embodiment can be determined as a wire feeding abnormality.

  Thus, the quality of welding can be managed by managing the wire feed amount actually fed. Furthermore, the increase in the feeding resistance accompanying the exhaustion of the wire feeding path makes it possible to accurately detect in advance and take preventive measures before the increase in the change in the wire speed becomes serious. By doing so, the welding quality can be maintained. Further, according to the present embodiment, it is possible to detect in advance a trouble in the feeding system that takes time to recover, such as buckling of the wire W, and it is possible to reduce the system stop time of the welding robot.

  (2) In the welding robot according to the present embodiment, the welding condition control unit 17c serving as the feeding abnormality determination means has a comparison difference ΔL between the first wire feeding amount and the second wire feeding amount that is equal to the first threshold L1 <. If ΔL <second threshold L2 (setting range) is not satisfied, it is determined that the feeding is abnormal, and if it is satisfied, the welding current and welding voltage (welding conditions) are changed according to the second wire feeding amount. As a result, when the welding condition control unit 17c determines that the feeding is abnormal, the effect of the above (1) can be achieved. When it is not determined that the feeding is abnormal, the welding current according to the second wire feeding amount and Can be welded at welding voltage (welding conditions).

  (3) In the welding robot of the present embodiment, the RAM 17b (first allowable condition storage means) that stores the first threshold value L1 and the second threshold value L2 that are different first allowable conditions depending on the type of the wire W, and welding. A teach pendant 19 (input means) for specifying a wire to be used is provided. Further, the welding condition control unit 17c (feeding abnormality determining means) reads the first threshold value L1 and the second threshold value L2 (first allowable condition) corresponding to the specified wire type from the RAM 17b, and determines the feeding abnormality. Used for. As a result, the welding condition control unit 17c reads out the first threshold value L1 and the second threshold value L2 corresponding to the specified type of the wire W from the RAM 17b and uses them for feeding abnormality determination. Thus, the first threshold value L1 and the second threshold value L2 (first permissible condition) can be automatically set, and the setting troublesomeness can be released.

  (4) In the present embodiment, the welding condition control unit 17c determines whether or not the change amounts ΔA and ΔV of the welding condition satisfy the second allowable condition (A1 <ΔA <A2, V1 <ΔV <V2). It functions as a change amount appropriateness determining means for determining. When the change amount of the welding voltage and welding current satisfies the second allowable condition (A1 <ΔA <A2, V1 <ΔV <V2), the welding condition control unit 17c performs welding under the welding condition with the change amount. If the second permissible condition is not satisfied, it is determined that the feeding is abnormal. As a result, in the present embodiment, the effect (1) can be easily realized.

  (5) The welding robot of the present embodiment includes a RAM 17b (second allowable condition storage means) that stores different second allowable conditions depending on the type of the wire W, and a teach pendant 19 that specifies the wire W used for welding ( Input means). And the welding condition control part 17c (change amount appropriateness determination means) reads the 2nd permissible condition according to the kind of specified wire W from RAM17b, and uses it for feeding abnormality determination. As a result, the second permissible condition can be automatically set according to the type of the wire W, and it can be released from the troublesome setting.

  (6) The welding robot of the present embodiment is based on the RAM 17b (wire loading amount storage means) that stores the wire loading amount of the wire W fed to the welding torch 13, the second wire feeding amount, and the wire loading amount. And calculating the remaining amount of the loaded wire (wire remaining amount calculating means). Moreover, the welding condition control part 17c performs warning determination regarding a wire remaining amount based on the magnitude of the wire remaining amount as a warning determination unit. As a result, according to the present embodiment, since the welding condition control unit 17c makes a warning determination about the remaining wire amount based on the remaining wire amount, refilling of the wire can be promoted when the remaining wire amount is low. .

(7) The welding robot of the present embodiment can automatically prohibit wire welding by the robot when the welding condition control unit 17c determines that there is no remaining wire.
In addition, you may change embodiment of this invention as follows.

  In S12 of the embodiment, instead of the pulse count value, the distance that the driving roll 24 has rotated from the feed command value output to the wire feed control device 30 by the welding condition control unit 17c of the welding machine 17 (that is, The first wire feed amount) may be converted.

○ Instead of the wire reel 14 of the above embodiment, a pail pack may be used.
In the embodiment, each abnormality, warning, and information performed in S24, S26, S28, and S32 may be recorded in a storage unit (not shown) provided in the robot control device.

  As shown in FIG. 2 (b), the measurement unit 42 is provided on the support portion 12a so as to be positioned on the upstream side of the welding torch 13 as in the above embodiment, and the wire feeding device 16 as a wire feeding means. May be provided integrally with the support portion 12 a on the upstream side of the measurement unit 42. Other configurations are the same as those in the above embodiment. If it does in this way, in order to reduce size and weight, it can be realized in the welding torch 13 integrated with the feeding device, and the welding robot can be miniaturized.

  In the embodiment, the welder 17 may be provided with a network interface that can exchange information with the outside, for example, a host computer system. In this way, the warning signal and the abnormal signal that is the stop signal in the above embodiment can be output to the host computer system, and the wire feeding and the like can be managed.

  A wire speed measurement waveform based on the output of the encoder provided in the motor 22 and the output of the encoder provided in the pressure roll 42a is generated and recorded in a storage device (not shown) of the robot control device 10, and the teach pendant 19 Or you may make it display on the personal computer which communicated with the robot control apparatus 10. FIG. In this case, the speed measurement waveform is preferably displayed simultaneously with the welding current / voltage waveform and the motor torque waveform.

  ○ In recent years, a push-pull type wire feeding system using a wire feeding auxiliary device is often adopted, so by embodying a push-pull type wire feeding system, It can also be used as a guideline for adjusting the feeding force. Further, as described above, the wire speed measurement waveform is stored in the robot control device, and when a new wire reel or pail pack is loaded, it is possible to predict the timing for changing the feeding force of the wire feeding assist device. .

  ○ Conventionally, there is a technology called RS control that uses a welding torch-integrated feeding device to retract the wire once at the start of welding and increase the success rate of the welding start. An integrated feeding device was required. If the present invention is embodied, the wire feed command value output from the welding machine 17 becomes more accurate by monitoring the actual wire feed amount. And RS control by the combination of an inexpensive welding torch and a push type feeding device mounted on the robot shoulder can be realized.

  In the case of robot welding, as described above, in the wire feeding path between the wire feeding device and the welding torch, there is a variation in the play portion of the wire, so it is desirable to add the measuring unit 42 in the vicinity of the welding torch. However, in a system in which the fluctuation of the play portion of the wire is small between the wire feeding device 16 and the welding torch 13, it is effective to attach the measurement unit 42 to the shoulder portion of the manipulator 11 or in the vicinity of the wire feeding device 16. .

In the embodiment, the arithmetic unit 44 is provided outside the welding machine 17, but the arithmetic unit 44 may be built in the welding machine 17 as shown in FIG.
In the above embodiment, the wire feed control device 30 is built in the welding machine 17, but the wire feed control device 30 is provided outside the welder 17 and communicates between the wire feed control device 30 and the welder 17. It may have a function.

  ○ Also, as shown in FIG. 5B, a wire feed control device 30 is provided outside the welding machine 17 to provide a communication function between the wire feed control device 30 and the welder 17 so that the wire feed An arithmetic unit 44 may be built in the control device 30.

  As shown in FIG. 6A, the arithmetic unit 44 and the robot controller 10 are communicated to transmit data from the arithmetic unit 44 to the robot controller 10, and are sent to the welding machine 17 via the robot controller 10. The data may be transmitted.

  As shown in FIG. 6B, the arithmetic unit 44 is built in the robot control apparatus 10, data is sent from the arithmetic unit 44 to the robot control apparatus 10, and the data is sent to the welding machine 17 via the robot control apparatus 10. May be sent.

(A) is a system diagram of a welding robot according to an embodiment of the present invention, (b) is an electrical block diagram of the system. (A) is the schematic of the wrist part vicinity of the manipulator of the welding robot of embodiment, (b) is the schematic figure of the wrist part vicinity of the manipulator of the welding robot of other embodiment. The flowchart which the wire feed control apparatus of embodiment performs. The electric block diagram of the system of other embodiment. (A), (b) is an electrical block diagram of a system. (A), (b) is an electrical block diagram of a system. The electric block diagram of the conventional welding robot.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Robot control apparatus, 12 ... Wrist part, 13 ... Welding torch, 14 ... Wire reel, 16 ... Wire feeder (wire feeding means), 17 ... Welding machine, 17b ... RAM (1st permissible condition storage means, Second allowable condition storage means, wire loading amount storage means),
17c ... Welding condition control section (first wire feed amount detection means, feed abnormality judgment means, change amount appropriateness judgment means, wire remaining amount calculation means, warning judgment means), 19 ... teach pendant (input means), 20 ... Power amplifier, 22 ... motor (drive source), 24 ... feed roll, 26 ... pressure roll, 40 ... wire measurement device (second wire feed amount detection means), 42 ... measurement unit (measurement means), 44 ... Arithmetic unit (calculation means).

Claims (6)

In a welding robot provided with a wire feeding means for feeding a wire to a welding torch located on the downstream side,
First wire feed amount detecting means for detecting a wire feed amount (hereinafter referred to as a first wire feed amount) of the wire feed means;
A second wire feed amount detecting means for detecting a wire feed amount (hereinafter referred to as a second wire feed amount) at a downstream position between the wire feed means and the welding torch;
Comparing the first wire feeding amount and the second wire feeding amount, the feeding abnormality determining means for judging the feeding abnormality of the wire feeding means based on the comparison result ,
The feeding abnormality determining means determines whether or not a difference between the first wire feeding amount and the second wire feeding amount satisfies the first permissible condition. If it is determined that the supply is abnormal and the first allowable condition is satisfied, the welding condition is changed according to the second wire feed amount.
First allowable condition storage means for storing different first allowable conditions depending on the type of the wire;
An input means for specifying a wire to be used for welding,
The welding robot according to claim 1, wherein the feeding abnormality determining means reads out a first allowable condition according to the specified wire type from the first allowable condition storage means and uses it for determining a feeding abnormality .   The feeding abnormality determination means includes a change amount appropriateness determination means for determining whether or not the change amount of the welding condition satisfies a second allowable condition regarding the change amount,
  When the change amount satisfies the second allowable condition, the change amount appropriateness determining means permits welding under the welding condition with the change amount, and when the change amount does not satisfy the second allowable condition, The welding robot according to claim 1, wherein it is determined that the supply is abnormal.   Second permissible condition storage means for storing a second permissible condition that differs depending on the type of the wire;
  An input means for specifying a wire to be used for welding,
  3. The change amount appropriateness determining means reads out a second allowable condition according to the specified wire type from the second allowable condition storage means and uses it for determining a feeding abnormality. The welding robot described.   The welding torch is attached via a support portion provided on a wrist portion of a manipulator of a welding robot,
  The wire feeding means is provided integrally with the support;
  The second wire feed amount detecting means is
  A measuring means for detecting the wire feed amount; and a computing means for computing the second wire feed amount based on the measurement result of the measuring means;
  The welding robot according to any one of claims 1 to 3, wherein the measuring means is provided in the support portion.   Wire loading amount storage means for storing the wire loading amount of the wire fed to the welding torch;
  Wire remaining amount calculating means for calculating the remaining amount of the loaded wire based on the second wire feeding amount and the wire loading amount;
  5. The apparatus according to claim 1, further comprising a warning determination unit configured to determine whether or not to issue a warning regarding the remaining amount of wire based on the amount of remaining wire. Welding robot.   The welding robot according to claim 5, wherein the warning determination unit performs a welding prohibition process when it is determined that there is no remaining wire.

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