Patent application number | Description | Published |
20080308533 | SPOT WELDING SYSTEM AND METHOD FOR ADJUSTING WELDING-GUN CLOSING SPEED - A spot welding system including a welding gun with an electrode pair actuated by a servo-motor, a robot carrying the welding gun or objective workpieces and operating to change the relative positions and orientations of the welding gun and the workpieces, and a gun motion controller controlling the servo-motor to actuate the electrode pair to open or close. The gun motion controller includes a motion commanding section outputting a motion command to the servo-motor in accordance with a speed set-value designating a closing speed of the electrode pair, and a set-value adjusting section automatically adjusting the speed set-value to an appropriate value. The set-value adjusting section includes a force-data obtaining section obtaining force data representing, in a time-series manner, the pressurizing force generated in the electrode pair when the servo-motor actuates the electrode pair to close in accordance with the motion command, and an appropriate-value computing section determining the appropriate value of the speed set-value based on pre-convergence transient data in the force data. | 12-18-2008 |
20090001056 | POSITIONING METHOD OF SPOT WELDING ROBOT - A positioning method of spot welding robot having: (A) moving a welding gun with a separation between an opposition electrode tip and a movable electrode tip kept open and larger than a preset plate thickness of a work piece so as to position the opposition electrode tip and the movable electrode tip on both sides of the work piece in a plate-thickness direction of the work piece, respectively, and temporarily positioning the opposition electrode tip at a stand-by position; (B) moving the movable electrode tip in a direction approaching toward the opposition electrode tip, monitoring the current value of the servo motor driving the movable electrode tip, and when the current value exceeds a prescribed value, determining that a distal end of the movable electrode tip has been brought into contact with the work piece, stopping a movement of the movable electrode tip and measuring an open separation of two opposing tips between the movable electrode tip and the opposition electrode tip that has been temporarily positioned at the stand-by position; and (C) determining the difference value by subtracting the preset value for the work piece from the open separation of two opposing tips, and moving the opposition electrode tip in the direction approaching toward the movable electrode tip from the stand-by position to the position of a spot welding point to finally position the opposition electrode tip, by using the difference value as the amount of movement of the opposition electrode tip. | 01-01-2009 |
20090007693 | METHOD OF DETERMINING DETERIORATION OF PRESSURIZING PERFORMANCE OF SPOT WELDING GUN - A method of determining deterioration of pressurizing performance of a spot welding, the method having: obtaining reference data that reflect a dynamic state of a servo motor in a case where a movable side electrode tip is operated normally and a wok piece is pressurized by a specified pressurizing force; performing data processing on the reference data to extract a reference characteristic value; obtaining diagnostic data that reflect a dynamic state of the servo motor in a case where a operational state of the movable side electrode tip changes and the work piece is no longer pressurized by a specified pressurizing force; performing data processing on the diagnostic data to extract a diagnostic characteristic value; and determining deterioration of pressurizing performance of the spot welding gun based on the reference characteristic value and the diagnostic characteristic value. | 01-08-2009 |
20110089146 | METHOD OF DETECTION OF WELDING WORKPIECE POSITION USING MOVABLE ELECTRODE - A spot welding system including spot welding gun having a movable electrode driven by a servo motor, a counter electrode arranged facing it and with a multiarticulated robot, holding one of the welding workpiece and spot welding gun which moves welding workpiece and spot welding gun relative to each other and thereby make the movable electrode and the welding workpiece approach each other from a separated state or vice-versa, monitoring the current or torque of the servo motor, and detecting the surface position of the welding workpiece from the position of the movable electrode and the position of the multiarticulated robot when the trend of the current or torque changes. The precision of detection of the surface position of the welding workpiece by a movable electrode in a spot welding system can now be improved without lengthening the time required for detection of the surface position of the welding workpiece. | 04-21-2011 |
20110120978 | SPOT WELDING SYSTEM - A spot welding system including a spot welding gun having a pair of electrodes disposed opposite to each other, and a servo motor for allowing the pair of electrodes to approach each other and separate from each other; a robot for movably holding either a spot welding gun or a workpiece so that a workpiece is disposed between the pair of electrodes of the spot welding gun; a physical quantity detection section for detecting a physical quantity correlative to torque or velocity of the servo motor; a position detection section for detecting positions of the pair of electrodes; a mode switching section for switching, by a switching command, an operation mode of the spot welding system between a spot welding mode for spot-welding the workpiece and a position correction mode for correcting a spot welding position of the workpiece; and a processing section for performing a spot welding process in the spot welding mode and a position correction process in the position correction mode. | 05-26-2011 |
20110180516 | POSITION DETECTION DEVICE AND A POSITION DETECTION METHOD FOR A WORKPIECE TO BE WELDED - A position detection device for a workpiece to be welded including a spot welding gun having a pair of electrodes adapted to be disposed opposite each other across the workpiece; a robot for holding either one of the spot welding gun and the workpiece in a manner movable relate to each other; a servo motor for allowing the pair of electrodes to approach the workpiece and separate from the workpiece; a physical quantity detection section for detecting a physical quantity correlative to a torque of the servo motor when the servo motor allows one of the pair of electrodes to approach a surface of the workpiece so that the one of the pair of electrodes abuts against the surface of the workpiece; a position detection section for detecting positions of the pair of electrodes; a storage section for storing the physical quantity detected by the physical quantity detection section and a value detected by the position detection section; and a computation section for calculating a contact start time at which the one of the pair of electrodes comes into contact with the surface of the workpiece based on time-series data of the physical quantity stored in the storage section, and computing a position of the workpiece at the contact start time based on the value detected by the position detection section stored in the storage section. | 07-28-2011 |
20110240605 | SPOT WELDING SYSTEM AND DRESSING DETERMINATION METHOD - A spot welding system including a welding gun with an openable/closable electrode pair; and a dressing determination device determining a quality of a shaping process applied to an electrode of the electrode pair. The dressing determination device includes a visual sensor obtaining an image of the electrode, identifying a base and a tip of the electrode on the image and measuring a distance between the base and the tip on the image, by image processing; a visual sensor control section allowing the visual sensor to measure the distance immediately before and after the shaping process is performed; a cut amount calculation section calculating a difference between the distances measured by the visual sensor immediately before and after the shaping process is performed, as a cut amount of the electrode; and a cut amount judgment section judging whether the calculated cut amount is within a predetermined acceptable range. | 10-06-2011 |
20120074112 | ARC WELDING METHOD REDUCING OCCURRENCES OF SPATTER AT TIME OF ARC START - An arc welding method which makes a welding torch or welding object which is supported by a robot move and performs arc welding using a welding start point on the welding object as a start point, which method includes a step of feeding a weld wire to the welding start point, a step of stopping the feed of the weld wire after a tip of the weld wire contacts the welding object, a step of supplying a pre-arc welding power in a range where no arc is generated to input heat to the weld wire and the welding object, a step of supplying an arc generating welding power which causes generation of an arc while retracting the weld wire, and a step of supplying main welding power to perform main welding and which method reduces occurrences of spatter at the time of arc start. | 03-29-2012 |