A method controlling an arc welding torch of a welding robot

Claim 2

A welding robot controlling system for a welding robot adapted to move the welding torch thereof along a teaching line while causing the free end of the welding torch to perform weaving operation, comprising detecting the welding current or the welding voltage at both ends of the weaving operation, detecting the deviation of the center of weaving motion from the actual weld line on a workpiece and the difference between a set welding current or--welding voltage and the actual welding current or welding voltage, and controlling the basic three shafts or the basic three elements of the robot to correct the locus of the center of weaving motion by means of locus correction signals obtained through the operation of the results of detection.

Claim 3

A welding robot controlling system according to Claim 1, wherein a teaching playback welding robot capable of moving the welding torch thereof between teaching positions by linear interpolation.

Claim 4

A welding robot controlling system for a welding robot adapted to move the welding torch thereof along a teaching line while causing the free end of the welding torch to perform weaving operation, comprising detecting the welding current or the welding voltage at both ends of the weaving operation, detecting the deviation of the center of weaving motion from the actual weld line on a workpiece on the basis of the variation of the detected values, controlling the basic three shafts or the basic three elements of the robot by means of locus correction signals obtained through the operation of the detected values to correct the locus of the center of weaving, and controlling the position of the welding torch so as to make the angles at every moment of the robot wrist, when the center of weaving is projected on a line connecting a starting teaching point and an eading teaching point to perform linear interpolation, become the same with the wrist. angle which. is changed evenly and uniformly between the starting and the ending teaching points within an angular difference between a teaching wrist angle at the starting teaching point and a teaching wrist angle at the ending teaching point.

Claim 5

A welding robot controlling system for a welding robot adapted to move the welding torch thereof along a teaching line while causing the free end of the welding torch to perform weaving operation, comprising detecting the welding current or the welding voltage at both ends of the weaving operation, detecting the deviation of the center of weaving motion from the actual weld line on a workpiece on the basis of the variation of the detected values, controlling the basic three shafts or the basic three elements of the robot by means of locus correction signals obtained through the operation of the detected values to correct the locus of the center of weaving, and controlling the position of the welding torch so as to make the angles at every moment of the robot wrist, when the center of weaving is projected on a line connecting a starting teaching point and an eading teaching point to perform linear interpolation, become the same with the wrist. angle which. is changed evenly and uniformly between the starting and the ending teaching points within an angular difference between a teaching wrist angle at the starting teaching point and a teaching wrist angle at the ending teaching point.

Claim 6

A welding robot controlling system for a welding robot adapted to move the welding torch thereof along a teaching line while causing the free end of the welding torch to perform weaving operation, comprising defining and teaching a monitoring point in addition to teaching points for ordinary welding operation to detect the corner of the workpiece, determining the distance between said monitoring point and the center of weaving through operation, recognizing the present welding position to be a profiling welding block to be presently welded and continuing the weld line tracking operation while said distance-is monotonically decreasing, recognizing the corner of the workpiece and completing the trackning operation in said block when said distance exceeds a predetermined width of variation, and controlling the center of weaving so as to cause the center of weaving to perform profiling welding in the next block on the basis of a line having the position of the welding torch at the completion of tracking operation in the preceding block as a starting point and a point, which is determines by three-dimensionally parallelly shifting a previously taught ending point of the next block by a displacement vector between said starting point and the previously taught ending point of said preceding block, as an ending point.

Claim 7

A welding robot controlling system for a welding robot adapted to move the welding torch thereof along a teaching line while causing the free end of the welding torch to perform weaving operation, comprising defining and teaching a monitoring point in addition to teaching points for ordinary welding operation to detect the corner of the workpiece, determining the distance between said monitoring point and the center of weaving through operation, recognizing the present welding position to be a profiling welding block to be presently welded and continuing the weld line tracking operation while said distance-is monotonically decreasing, recognizing the corner of the workpiece and completing the trackning operation in said block when said distance exceeds a predetermined width of variation, and controlling the center of weaving so as to cause the center of weaving to perform profiling welding in the next block on the basis of a line having the position of the welding torch at the completion of tracking operation in the preceding block as a starting point and a point, which is determines by three-dimensionally parallelly shifting a previously taught ending point of the next block by a displacement vector between said starting point and the previously taught ending point of said preceding block, as an ending point.

Claim 8

A welding robot controlling system comprising making the free end of the welding torch of the robot move following a teaching line and performing weaving operation, detecting the welding current or the welding voltage at both ends of weaving, detecting the deflection of the center of weaving from the actual weld line on the workpiece and the difference between a set welding current or welding voltage and the actual welding current or welding voltage, controlling the basic three shafts or the basic three elements of the robot by locus correction signals produced thraugh the operation of the detected values to correct the locus of the center of weaving, memorizing, in performing welding along a sharp corner such as a rectuangular corner, the position (X n-1 , y n-1 , Z n-1 ) of the center of weaving at the generation of the preceding locus correction signal and the position (x n-1 , yz-, , z n-1 ) of the center of weaving at the completion of locus correction, determining the angle f between the projection of a line ℓ connecting the position (x n y n , z n ) of the center of weaving at the moment of generation of the instant locus correction signal and the position (x n-1 , y n-1 , z n-1 ) of the center of weaving at the generation of the preceding locus correction correction signal, on a plane defined by a previously taught line L1 and a line L2 taught in the next block extending after the line L1, and the line L1, determining the angle η between the projection of a line connecting the position (x n , y n , z' n ) of the center of weaving immediately after the completion of locus correction and the position (x' n-1 , y n-1 , z' n-1 ) of the center of weaving at the completion of the preceding locus correction, on said plane defined by lines L1 and L2, and said line L1, calculating the mean value of'said angles ξ and η before and after every locus correction during the welding operation and memorizing the calculated results sequentially in a FIFO memory circuit, simultaneously recognizing a corner and clearing the contents of said FIFO memory circuit when the mean value memorized in said FIFO memory circuit becomes greater than a value of a function of the welding speed, weaving frequency and the amount of locus correction to . complete the welding operation in the block of the line L1, and shifting the tracking control for tracking the weld line of the next block by decidingsthat the welding operation is to be performed in the next block in which the center of weaving is to move on a line having the position of the free end of the torch at the completion of welding in the preceding block as a starting point and a point determined by three-dimensionally parallelly shifting the previously taught ending point of the block of the line L2 by a displacement vector between said starting point and the previously taught ending point of the line L1 as an ending point.

Claim 9

A welding robot controlling system comprising making the free end of the welding torch of the robot move following a teaching line and performing weaving operation, detecting the welding current or the welding voltage at both ends of weaving, detecting the deflection of the center of weaving from the actual weld line on the workpiece and the difference between a set welding current or welding voltage and the actual welding current or welding voltage, controlling the basic three shafts or the basic three elements of the robot by locus correction signals produced thraugh the operation of the detected values to correct the locus of the center of weaving, memorizing, in performing welding along a sharp corner such as a rectuangular corner, the position (X n-1 , y n-1 , Z n-1 ) of the center of weaving at the generation of the preceding locus correction signal and the position (x n-1 , yz-, , z n-1 ) of the center of weaving at the completion of locus correction, determining the angle f between the projection of a line ℓ connecting the position (x n y n , z n ) of the center of weaving at the moment of generation of the instant locus correction signal and the position (x n-1 , y n-1 , z n-1 ) of the center of weaving at the generation of the preceding locus correction correction signal, on a plane defined by a previously taught line L1 and a line L2 taught in the next block extending after the line L1, and the line L1, determining the angle η between the projection of a line connecting the position (x n , y n , z' n ) of the center of weaving immediately after the completion of locus correction and the position (x' n-1 , y n-1 , z' n-1 ) of the center of weaving at the completion of the preceding locus correction, on said plane defined by lines L1 and L2, and said line L1, calculating the mean value of'said angles ξ and η before and after every locus correction during the welding operation and memorizing the calculated results sequentially in a FIFO memory circuit, simultaneously recognizing a corner and clearing the contents of said FIFO memory circuit when the mean value memorized in said FIFO memory circuit becomes greater than a value of a function of the welding speed, weaving frequency and the amount of locus correction to . complete the welding operation in the block of the line L1, and shifting the tracking control for tracking the weld line of the next block by decidingsthat the welding operation is to be performed in the next block in which the center of weaving is to move on a line having the position of the free end of the torch at the completion of welding in the preceding block as a starting point and a point determined by three-dimensionally parallelly shifting the previously taught ending point of the block of the line L2 by a displacement vector between said starting point and the previously taught ending point of the line L1 as an ending point.

Claim 10

A welding robot controlling system comprising making the free end of the welding torch of the robot move following a teaching line and performing weaving operation, detecting the welding current or the welding voltage at both ends of weaving, detecting the deflection of the center of weaving from the actual weld line on the workpiece and the difference between a set welding current or welding voltage and the actual welding current or welding voltage, controlling the basic three shafts or the basic three elements of the robot by locus correction signals produced through the operation of the detected values to correct the locus of the center of weaving, extremely reducing the welding speed and the welding current comparatively to the normal welding speed and the normal welding current, respectively, and increasing the weaving frequency and the amount of locus correction comparatively to the normal weaving frequency and the normal amount of locus correction, until the welding torch reaches the actual weldline in case the actual weld starting position is deviated from the previously taught welding starting position.

Claim 11

A welding robot controlling system comprising making the free end of the welding torch of the robot move following a teaching line and performing weaving operation, detecting the welding current or the welding voltage at both ends of weaving, detecting the deflection of the center of weaving from the actual weld line on the workpiece and the difference between a set welding current or welding voltage and the actual welding current or welding voltage, controlling the basic three shafts or the basic three elements of the robot by locus correction signals produced through the operation of the detected values to correct the locus of the center of weaving, extremely reducing the welding speed and the welding current comparatively to the normal welding speed and the normal welding current, respectively, and increasing the weaving frequency and the amount of locus correction comparatively to the normal weaving frequency and the normal amount of locus correction, until the welding torch reaches the actual weldline in case the actual weld starting position is deviated from the previously taught welding starting position.

Claim 12

A welding robot controlling system comprising making the free end of the welding torch of the robot move following a teaching line and performing weaving operation, detecting the welding current or the welding voltage at both ends of weaving, detecting the deflection of the center of weaving from the actual weld line on the workpiece and the difference between a set welding current or welding voltage and the actual welding current or weldiug voltage, controlling the basic three shafts or the basic three elements of the robot by locus correction signals produced through the operation of the detected values to correct the locus of the center of weaving,, teaching three points on a line to be subjected to linear interpolation, i.e. in the vicinity of the weld line, and controlling the free end of the welding torch so as to move along one of the surfaces of a triangular cylinder formed by shifting a triangular plane defined by said three teaching points in the direction of the weld line, while performing a weaving operation defined by an amplitude defined by said three teaching points, a desired weaving frequency, a weaving interrupting time at both ends of weaving and a welding speed.

Claim 13

A welding robot controlling system comprising making the free end of the welding torch of the robot move following a teaching line and performing weaving operation, detecting the welding current or the welding voltage at both ends of weaving, detecting the deflection of the center of weaving from the actual weld line on the workpiece and the difference between a set welding current or welding voltage and the actual welding current or weldiug voltage, controlling the basic three shafts or the basic three elements of the robot by locus correction signals produced through the operation of the detected values to correct the locus of the center of weaving,, teaching three points on a line to be subjected to linear interpolation, i.e. in the vicinity of the weld line, and controlling the free end of the welding torch so as to move along one of the surfaces of a triangular cylinder formed by shifting a triangular plane defined by said three teaching points in the direction of the weld line, while performing a weaving operation defined by an amplitude defined by said three teaching points, a desired weaving frequency, a weaving interrupting time at both ends of weaving and a welding speed.

Claim 14

A welding robot controlling system according to Claim 7, wherein three teaching points defining said weaving operation are set in the vicinity of a first weld line which is to be subjected to linear interpolation, and said weaving operation is automatically continued through the three-dimensionally turning and parallelly shifting operation of the plane defined by said three teaching points for the second and the successive weld lines.

Claim 15

A welding robot controlling system comprising making the free end of the welding torch of the robot move following a tecahing line and performing weaving operation, detecting the welding current or the welding voltage at both ends of weaving, detecting the deflection of the center of weaving from the actual weld line on the workpiece and the difference between a. set welding current or welding voltage and the actual welding current or welding voltage, controlling the basic three shafts or the basic three elements of the robot by locus correction signals produced through the operation of the detected values to correct the locus of the center of weaving, and after the completion of the preceding locus correction and before the production of the next locus correction signal, controlling the basic three shafts or the basic three elements of the robot so that the center of weaving moves on a locus determined by three dimensionally parallelly shifting a line connecting two teaching points, which are originally taught for linear interpolation, by its locus correction vector.

Claim 16

A welding robot controlling system comprising making the free end of the welding torch of the robot move following a tecahing line and performing weaving operation, detecting the welding current or the welding voltage at both ends of weaving, detecting the deflection of the center of weaving from the actual weld line on the workpiece and the difference between a. set welding current or welding voltage and the actual welding current or welding voltage, controlling the basic three shafts or the basic three elements of the robot by locus correction signals produced through the operation of the detected values to correct the locus of the center of weaving, and after the completion of the preceding locus correction and before the production of the next locus correction signal, controlling the basic three shafts or the basic three elements of the robot so that the center of weaving moves on a locus determined by three dimensionally parallelly shifting a line connecting two teaching points, which are originally taught for linear interpolation, by its locus correction vector.