Abstract: A spot welding apparatus includes a spot welding gun and a welding gun control apparatus. The welding gun control apparatus includes a pressurizing force control part controlling the pressurizing force, a position control part controlling the position of at least one electrode, and a determination part determining whether or not the welding is performed in a normal state. The position control part controls an electrode drive motor so as to hold the electrodes, after the supply of the electric current is started, at positions when the initial pressurizing force is applied before the electric current is supplied. The determination part acquires the pressurizing force and determines whether or not the welding is performed in a normal state based on change tendency in the pressurizing force.

Abstract: An upper electrode assembly for welding fasteners includes a body that supports an electrode that has an aperture. The aperture is configured to receive a movable pin of a lower electrode assembly arranged opposite the upper electrode assembly. The lower electrode assembly supports a fastener in a welding position. The upper electrode assembly includes a position sensor which includes a position sensor member that is arranged in the body and is configured to cooperate with the pin to detect a fastener welding characteristic.

Abstract: A spot welding apparatus includes a stationary frame having a housing formed therein. An upper welding gun is mounted to a length direction of a pressing unit disposed in the housing of the stationary frame. A plurality of lower welding guns are mounted on an outside of the stationary frame and ends of the plurality of lower welding guns selectively face one end of the upper welding gun in a length direction of the lower welding guns by the plurality of lower welding guns. A plurality of actuators are mounted on the outside of the stationary frame. A plurality of link units are disposed between the actuators and the lower welding guns, connect the actuators and the lower welding guns, respectively, and rotate as the actuators are operated.

Abstract: A spot welding system includes a position detection part which detects the position of a movable arm, a first calculation part which calculates the combined spring constant of the movable arm and a fixed arm based on a position when the movable arm is driven by a predetermined drive force and the drive force, a second calculation part which calculates the spring constant of the movable arm based on a position when the movable arm is driven by a predetermined drive force and the drive force, a third calculation part which calculates the spring constant of the fixed arm based on the combined spring constant and the spring constant of the movable arm, and an elastic displacement calculation part which calculates an amount of elastic displacement of the fixed arm based on the spring constant of the fixed arm and a drive force when welding is performed.

Abstract: A spot welding apparatus according to is provided that includes an upper and lower moving unit, an upper welding gun, a left and right moving unit and a lower welding gun. In particular, the upper and lower moving unit includes a slide block that is provided at one side of an arm of a robot to move vertically by actuation of an actuator. The upper welding gun is mounted on the slide block and the left and right moving unit is installed at one side of the upper welding gun to horizontally move the upper welding gun by actuation of the actuator. Additionally, the lower welding gun is mounted to correspond to a lower side of the upper welding gun.

Abstract: An arc welder including an integrated monitor is disclosed. The monitor is capable of monitoring variables during a welding process and weighting the variables accordingly, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Abstract: An arc welder including an integrated monitor is disclosed. The monitor is capable of monitoring variables during a welding process and weighting the variables accordingly, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Abstract: An electric spot welding gun (10) includes: a servo motor (40); a push rod (50) that advances and retracts in response to rotation of a rotor (43) of the servo motor; a drive-side electrode tip (71) that is mounted to a drive-side arm (70) fixed to a leading end of the push rod; and an encoder (60) that detects the rotation angle of the rotor of the servo motor, the position of the electrode tip being offset relative to the push rod, in which the rotor and the encoder are disposed in parallel to each other in an offset plane on which the electrode tip is offset relative to the push rod, at an attitude in which a trailing end (44) of the rotor on a side opposite to a push rod side thereof and an input end (64) of the encoder are facing in the same direction.

Abstract: An arc welding system and methods. The system is capable of monitoring variables during a welding process, according to wave shape states, and weighting the variables accordingly, detecting defects of a weld, diagnosing possible causes of the defects, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Abstract: An equalizing mechanism of a welding apparatus connects an apparatus body and a fixed bracket, and includes a fixed member on the fixed bracket, and a pressure shaft on an apparatus body close to a bottom face of the fixed member. A cutout is at a position facing the fixed member A movable member on the apparatus body accommodates the fixed member. A restrictive member located by side faces of the fixed member and the movable member restricts relative movement thereof to a direction parallel to the pressure shaft. A driven lever is supported by a front portion of the fixed member to abut on an inner front face of the movable member at one end and abut on the pressure shaft at an other end. A spring between a back portion of the fixed member and an inner back face of the movable member presses the two members to move away from each other.

Abstract: An arc welder including an integrated monitor is disclosed. The monitor is capable of monitoring variables during a welding process and weighting the variables accordingly, quantifying overall quality of a weld, obtaining and using data indicative of a good weld, improving production and quality control for an automated welding process, teaching proper welding techniques, identifying cost savings for a welding process, and deriving optimal welding settings to be used as pre-sets for different welding processes or applications.

Abstract: A method for controlling a welding robot having a servo gun with a movable tip and a fixed tip includes the steps of separately contacting a surface of a part with the movable tip to measure a base test point and an at least two additional test points displaced from the base test point. Two non-collinear vectors are calculated from the at least two additional test points. A normal vector is calculated from the two non-collinear vectors. An angle between the original servo gun orientation and the normal vector is determined. An orientation of the servo gun may be corrected, for example, if the angle is within user specified tolerances.

Abstract: A weld gun system for detecting the orientation of a weld nut relative to the metallic component to which it is to be welded prior to welding is disclosed. The system includes a lower electrode having a weld location pin, an upper electrode having a central circular recess formed therein, a fluid supply fluidly connected to the central circular recess of the upper electrode, and a pressure switch also fluidly connected to the central circular recess of the upper electrode. Once the weld nut is captured between the electrodes the fluid flows from the fluid supply into the central circular recess of the upper electrode. If the weld nut is in proper orientation the fluid continues to flow to the pressure switch and the weld occurs. If the weld nut is not in proper orientation the fluid does not flow to the pressure switch but is instead vented from the central circular recess and the weld does not occur.

Abstract: 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.

Abstract: A welding apparatus includes a first electrode tip; a second electrode tip opposing the first electrode tip; and an electrically conductive part which is provided so as to be freely interposed between the second electrode tip and a work and ensures electrical conduction between the second electrode tip and the work when the electrically conductive part is interposed between the second electrode tip and the work, the electrically conductive part including an electrically conductive member one side of which opposes the work with a presence of a void space from the work when the electrically conductive member is interposed between the second electrode tip and the work, and against which the second electrode tip is abutted on another side thereof, and a pair of electrically conductive abutment members which are provided integrally with the electrically conductive member in such a manner as to extend toward the work, and distal ends of which are abutted against the work, a position of abutment of the electrically

Abstract: 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

Abstract: 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 an relative positions and orientations of the welding gun and an workpieces, and a gun motion controller controlling the servo-motor to actuate the electrode pair. The gun motion controller includes a motion commanding section outputting motion commands 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.

Abstract: A method and device for measuring a resistance spot welding electrode tip includes a welding electrode tip monitoring device for monitoring a welding electrode tip, the welding electrode tip monitoring device communicatively connected to a robotic welder equipped with electrode welding tips in a manner to be automatically employed as part of a robotic step with the robotic welder and is equipped with a mechanism for generating characteristic data of the welding electrode tips without having to remove the welding tips from the robotic welder.

Abstract: The present invention provides a production line method of resistance welding comprising the steps of contacting a metal sheet with an electrode having an initial contact surface area at a force provide a pressure to the metal sheet; applying a current though the electrode to the metal sheet; measuring dimensional changes of the electrode; correlating dimensional changes in the electrode to changes in the initial contact surface area; and adjusting the force to compensate for the changes in the initial contact surface area of the electrode to maintain pressure to the metal sheet. The force may be adjusted by stepping the force to maintain pressure to the flaying surface of the metal sheet to be welded. By maintaining the pressure at the faying surface the life cycle of the electrodes may be increased without forming discrepant welds.

Abstract: A spot welding system using a spot welding gun having a servomotor for driving welding tips capable of suppressing variation of pressing force due to influence of heat generated by welding current to obtain an uniform pressing force. A difference between the temperature T detected by a temperature sensor and an initial temperature T0 is multiplied by a coefficient A to obtain a pressing force compensation amount ?. A pressing force d estimated by an observer is subtracted from the compensated command pressing force p? and an obtained difference is multiplied by a constant K2 to obtain a torque command (current command) ? for driving the servomotor to press the objects by the welding tips. Since the commanded pressing force is compensated in accordance with the temperature, a constant and stable pressing force is produced without influence of the temperature variation.

Abstract: The invention relates to a control device for spot welding with a welding electrode pincer (Z), the welding electrodes (E1, E2) of which are connect to a welding current generator (IS) and an electric motor drive (M), with a rotary transducer (RES), the signal of which is used by a control device (MP) to control the welding electrode pincer (Z). The closed state of said pincer holds the objects for welding (B1, B2) together, by means of a pre-set motor current (MAI), whereupon the welding current generator (IS) is activated. The control device (MP) comprises monitoring devices (const, max), to which the rotary transducer signals (RES) and/or a motor current measured signal (I(t)) are constantly supplied. Once a quasi-constant state is recognized, following a close signal for the welding electrode pincer (Z), a corresponding first state is recorded as the closed state and the welding current generator (IS) activated.

Abstract: A method of and device for automatically setting and updating a reference position of a welding tip of a servo spot welding gun to automatically compensate displacement of a distal end of a welding tip by abrasion thereof. A movable welding tip is moved towards a stationary welding tip to press the stationary welding tip until an estimated disturbance load reaches a fist threshold, and then moved in reverse direction away from the stationary welding tip until the disturbance load is reduced to a second threshold. The position of the movable welding tip when the disturbance load is reduced to the second threshold is set and updated as the reference position of an axis of the movable welding tip. The first threshold is set to be greater than a frictional force exerted on the axis of the movable welding tip in the motion towards the stationary welding tip, and the second threshold is set to be equivalent to the frictional force.

Abstract: The present invention relates to a nut positioning pin disposed on a lower electrode for the projection welding of a nut. The present invention increases cooling and positioning accuracy, prevents entrance of sputtering particles, and increases the detecting accuracy. The present invention comprises an electrode holder (2) of a double-tube structure having a cooling water passage, a guide ring (13) for guiding a coupling rod (7) for vertical movement, an air passage (m) for preventing the entrance of sputtering particles, a coupling block (28) and a magnetic shield, which comprises a magnetic member for preventing a magnetic detecting element from being affected by an external magnetic field. The present invention accurately guides cooling water and the coupling rod in the electrode holder and prevents sputtering particles from entering the electrode holder, and prevents a detector from being adversely influenced by an external magnetic field for increased detecting accuracy.

Abstract: Method and apparatus for detecting unacceptable misalignment of welding electrodes. An electrode-alignment station is positioned adjacent a welding station. A robot controls the movement of the electrodes, and occasionally moves the electrodes out of the welding station and into an electrode-alignment station. At the electrode-alignment station, the electrodes are closed on a fixture that transfers electrode-misalignment into movement of a plate that triggers an alarm if the misalignment is greater than a prescribed amount.

Abstract: An adaptable, servo-control system for force/position actuation generally includes an electric linear actuator and a controller. The controller interfaces with the electric linear actuator and with a number of I/O signals that are independent from the electric linear actuator. The controller interface to the independent I/O signals is transparent to the manner in which the I/O signals are produced. Rather the controller simply looks for the status of the I/O that is preferably received into the controller by hard-wiring or field bus I/O messaging such as from a industrial robot or programmable logic controller. The controller utilizes the I/O signals to select a number of parameters to generate a motion profile for closed loop-controlled, position actuation or force actuation of the electric linear actuator.

Abstract: An adaptable, servo-control system for force/position actuation generally includes an electric linear actuator and a controller. The controller interfaces with the electric linear actuator and with a number of I/O signals that are independent from the electric linear actuator. The controller interface to the independent I/O signals is transparent to the manner in which the I/O signals are produced. Rather the controller simply looks for the status of the I/O that is preferably received into the controller by hard-wiring or field bus I/O messaging such as from a industrial robot or programmable logic controller. The controller utilizes the I/O signals to select a number of parameters to generate a motion profile for closed loop-controlled, position actuation or force actuation of the electric linear actuator.

Abstract: A weld tip testing head is presented. An alignment member has an aperture disposed therein and is coupled to a spring element. The spring element is further coupled to a mounting. The aperture is operable to removably receive a weld tip and the alignment member is operable to determine an alignment associated with the weld tip. Computer software is encoded on storage. The computer software is operable to receive the alignment from the alignment member and analyze the alignment with respect to at least one expected alignment value. The computer software is further operable to generate an alarm based on the analysis and generate a fault based on the analysis.

Abstract: A robot controller and a welding timer coupled to each other by a dual-port RAM which is connected to data busses thereof, and Initial reference values of welding parameters are stored into a ROM of welding timer in same sequence as character strings of items. When power is turned on, character strings of items and values of the parameters are stored into a RAM of a robot, and both are displayed on a teaching pendant in same sequence. In teaching pendant, values of welding parameters are arbitrarily changed, and then stored into RAM of robot, and also into a RAM of the welding timer via dual-port RAM. A weld command given from the robot to welding timer via dual-port RAM, welding timer performs a welding process on basis of welding parameters which have been edited by teaching pendant and stored in RAM of the welding timer.

Abstract: A pogo welding apparatus especially for spot welding metal sheets at selected locations spaced away from their edges wherein the sheets are held in a temporary assembly with the selected locations engaged and separate programmable positioners move a primary (pogo) electrode and a backup electrode sequentially against opposite sides of the selected locations to spot weld the sheets at the selected locations in sequence. Various alternative programmable positioners, including robots of varying types, may be used to carry the electrodes. A multi head back-up electrode is adapted for efficient use of the apparatus and method in difficult to reach workpiece locations.

Abstract: The invention relates to a control device for spot welding with a welding electrode pincer (Z), the welding electrodes (E1, E2) of which are connected to a welding current generator (IS) and an electric motor drive (M), with a rotary transducer (RES), the signal of which is used by a control device (MP) to control the welding electrode pincer (Z). The closed state of said pincer holds the objects for welding (B1, B2) together, by means of a pre-set motor current (MAI), whereupon the welding current generator (IS) is activated. The control device (MP) comprises monitoring devices (const, max), to which the rotary transducer signals (RES) and/or a motor current measured signal (I(t)) are constantly supplied. Once a quasi-constant state is recognised, following a close signal for the welding electrode pincer (Z), a corresponding first state is recorded as the closed state and the welding current generator (IS) activated.

Abstract: A weld gun includes internal, external and structural devices that dissipate heat generated at electrode tips without requiring a continuous external source coolant. The internal devices utilize heat pipes within the electrodes to transfer heat to secondary heat removal features. A heat capacity on the weld gun contacts external heat sinks to directly conduct heat away from the weld gun after a completed weld cycle. Alternatively, the heat sink, the heat pipe and the secondary heat removal features are combined structurally on the weld gun arm by forming the arm from a plurality of plates separated by an air gap.

Abstract: An intelligent welding gun is provided with a fixed side sensor in a fixed side portion. The mechanical impedance of the fixed side portion is kept small, which permits the mechanical impedance to be set in a range where the fixed side sensor can effectively detect at least one of a position of a fixed side welding tip and a pressing force imposed on the fixed side welding tip. The fixed side sensor and a moving side sensor constitute a redundant sensor measurement system. Various kinds of methods conducted using the above welding gun include a method of calibrating a sensor (including calibration of a reference point and a gain), a control method of suppressing a welding expulsion, a re-welding feedback control method, a control method of a welding strength, a control method of reducing a clearance between workpieces, a method of correcting a welding robot track, and a method of managing a positional accuracy change at a welding point.

Abstract: A welding assembly is provided for welding a fastener to an object such as a vehicle body panel. The assembly includes a weld gun having first and second electrodes movable relative to one another between an open position and a closed position. The first electrode includes a housing assembly. A pin is received in the housing assembly and is movable when in said closed position between a desired nut position, and upside down nut position, and a no nut position. An optical sensor has a terminal end space from the pin for direction light thereon. The terminal end of the sensor received reflected light from the pin. A sensor control system processes the reflected light into a signal corresponding to one of the desired nut, upside down nut, and no nut positions.

Abstract: A system and method for performing preventative maintenance upon spot welding guns in an automotive vehicle assembly plant is disclosed. The system includes a data collection system, a data analysis system and a database. The system has the ability to monitor parameters of welding guns to predict when a failure of one or more of the guns is likely to occur so that maintenance can be performed on the guns according to the method.

Abstract: A system and method for performing preventative maintenance upon spot welding guns in an automotive vehicle assembly plant is disclosed. The system includes a data collection system, a data analysis system and a database. The system has the ability to monitor parameters of welding guns to predict when a failure of one or more of the guns is likely to occur so that maintenance can be performed on the guns according to the method.

Abstract: A data processing system is provided for determining a minimum flange length for a joint to be welded by resistance spot welding. In particular, the data processing system utilizes data for a preselected weld electrode and a set of joint data representative of a joint to be welded to determine whether a set of corrected tip data or a set of uncorrected tip data is to be used in determining the minimum flange length. A method for calculating the minimum flange length is also provided.

Abstract: A fully programmable servo-pneumatic modular weld gun having closed-loop position and pressure control generally includes a weld gun base module, a pneumatic cylinder with a movable piston having a first welding electrode, a J-shaped gun arm having a first end attached to the base module and a second end having a second welding electrode and a controller for providing closed-loop positioning and pressure control of the first welding electrode. The pneumatic cylinder includes an internal positioning encoder for detecting piston position and transmitting piston position information to the controller to control movement of the piston through a proportional flow control valve and a proportional pressure regulator.

Abstract: A robot control system and method for controlling a robot that performs working on a working path between a specified working start point and a working end point. The robot control system includes an interrupt request signal generating section for generating a signal for requesting change of the working path of the robot, an upper controller for generating an interrupt signal including a specified changed value for changing in real time the working path of the robot in accordance with the interrupt request signal generating section, and a robot controller for controlling in real time the operation of the robot in accordance with the interrupt signal from the upper controller. Thus, the motion of the robot that is working can be changed in real time.

Abstract: A fully programmable servo-pneumatic modular weld gun having closed-loop position and pressure control generally includes a weld gun base module, a pneumatic cylinder with a movable piston having a first welding electrode, a J-shaped gun arm having a first end attached to the base module and a second end having a second welding electrode and a controller for providing closed-loop positioning and pressure control of the first welding electrode. The pneumatic cylinder includes an internal positioning encoder for detecting piston position and transmitting piston position information to the controller to control movement of the piston through a proportional flow control valve and a proportional pressure regulator.

Abstract: Resistance welding machines may include one or more temperature sensors that measure the temperatures of one or more heat generating elements within the welding machine, such as the welding transformer, the welding cable, the welding gun and/or the welding current switching element. These heat generating elements generate heat due to the passage of the welding current and can be damaged if not properly cooled. A processor is provided to receive temperature signals from the temperature sensors(s) and actuate a warning output circuit when the temperature of one or more of the heat generating elements rises to a high temperature warning temperature. This high temperature warning temperature is preferably lower than an upper limit temperature at or above which the heat generating element may be damaged due to overheating.

Abstract: The present invention relates to an improved resistance weld-based gun assembly for use in an electric welding system without a need for plant-provided air and water-cooling circulation systems. In one aspect of the invention, a resistance-based force controller measures the resistance of a secondary circuit of the weld gun, the combined resistance of the secondary circuit in parallel with the circuit formed by the workpieces and opposing electrodes when sandwiched between the electrodes, and calculates the resistance of the workpieces. The measured resistance is compared to a predetermined resistance and the sandwiching force of the electrodes incrementally adjusted until the resistance of the workpieces is acceptable. The invention also relates to a closed loop coolant system having a coolant line, a coolant contained within the coolant line, a heat exchanger, and a mechanical coolant pump. One possible pump comprises an elastic bladder dependent upon the state change of the coolant.

Abstract: This invention relates to methods to control the resistance spotwelding process using an electric servomotor actuator to move the welding electrodes to the work and apply force to them. Measurements of actuator position, servomotor drive voltage, servomotor drive current, voltage across the welding electrodes, welding transformer primary current, welding transformer secondary current and power factor in the primary circuit of the welding transformer are used separately and in combination to determine various conditions such as identify defects in the welding machine, the electric cabling, the welding process and in the weld itself. Depending upon the defect found, the welding parameters are changed to overcome the defect, and/or the need for an additional weld is indicated and/or an error indication is generated.

Abstract: In a resistance welding machine, an arm including one electrode tip, a drive unit including a linear guide for driving another electrode tip corresponding to the one electrode tip, and a welding unit including a welding transformer for passing a secondary current through a gun bracket for supporting the present resistance welding machine on a robot and/or the present resistance welding machine, can be mounted and removed individually as a unit with a common base or a rail main body including the linear guide as the reference thereof.

Abstract: An intelligent welding gun is provided with a fixed side sensor in a fixed side portion. The mechanical impedance of the fixed side portion is kept small, which permits the mechanical impedance to be set in a range where the fixed side sensor can effectively detect at least one of a position of a fixed side welding tip and a pressing force imposed on the fixed side welding tip. The fixed side sensor and a moving side sensor constitute a redundant sensor measurement system. Various kinds of methods conducted using the above welding gun include a method of calibrating a sensor (including calibration of a reference point and a gain), a control method of suppressing a welding expulsion, a re-welding feedback control method, a control method of a welding strength, a control method of reducing a clearance between workpieces, a method of correcting a welding robot track, and a method of managing a positional accuracy change at a welding point.

Abstract: A resistance projection welder for welding first and second work pieces to each other. The first work piece having a body with opposing sides with at least one projection extending from one of the opposing sides and contacting the second work piece to space the body from the second work piece and define an air gap therebetween when the first and second work pieces are properly oriented. First and second electrodes electrically couple with work pieces and apply an electrical current thereto. A source of pressurized air directs a stream of pressurized air toward an interface between the first work piece and one of the second work piece and the first electrode. An air flow sensor detects the flow rate of the air stream directed toward the interface and determines if the work pieces are properly oriented based on the detected air flow rate.

Abstract: A resistor welding machine control method for calculating a temperature distribution at a portion to be welded by using changes in welding current and voltage across two welding electrodes during welding and information on sheet combination sequence at a spot-welding position, and for controlling at least the welding current or pressure applied to the electrodes by using the calculated temperature distribution. The present invention can thus provide a resistor welding machine control method capable of controlling welding quality accurately. Spot-welding position information, wear comparison information and the like are available as other information.

Abstract: A welding method and system for welding a workpiece at weld locations includes a weld controller having control logic and stored data related to weld locations and workpiece dimensions. The weld controller is operable with a displacement sensor for monitoring the displacement between the electrodes of a weld gun. The control logic is programmed to generate a move signal based upon the stored data and the displacement between the electrodes. The weld controller also has stored data related to primary and alternate weld locations. The control logic is programmed to generate a fault signal based upon the stored data and a welding parameter such as the displacement between the electrodes. The weld controller provides a fault signal to the position controller to index the weld gun from a primary weld location to an alternate weld location when a comparison of the welding parameter to stored data related to the primary weld location indicates that the workpiece has been improperly welded.

Abstract: A welding gun has a coordinate system fixed thereto, and a sensor is fixed to the coordinate system. The sensor senses a mobile electrode moved in a position, and a position detector cooperates with the sensor to detect the position of the mobile electrode relative to the welding gun.

Abstract: A method of and apparatus for detecting an abnormal load on a servo gun axis, capable of quickly detecting sticking of a welding tip to an object of welding before movement of a robot, without adversely affecting the object. A load applied to a servomotor for driving a welding tip of a welding gun is detected by an observer. An abnormal load signal is output when the estimated disturbance load deviates from a range defined by a reference &bgr; (&bgr;>0). A determination as to whether or not the estimated disturbance load is larger than the reference value +&bgr; is not made during a period of time from the start of a closing motion of the welding gun until the estimated disturbance load becomes smaller than a set value &agr;. When the welding tip is stuck to a workpiece, a negative estimated disturbance load smaller than −&bgr; is derived and an abnormal load Signal is outputted.

Abstract: A system and method is disclosed for monitoring and controlling a resistance projection welder for welding a projection weld nut to a workpiece. A displacement sensor measures the displacement of a welding electrode of a weld gun in real time during the welding procedure. A computer is coupled to the displacement sensor and determines whether the projection weld nut is correctly loaded between the workpiece and the welding electrode. The computer instructs a programmable logic controller (PLC) to trigger a weld controller to apply power to the welding electrode if the projection weld nut is correctly loaded onto the workpiece. The computer instructs the PLC to inhibit power if it determines the projection weld nut to be inverted, missing, or misaligned in order to allow for the removal and replacement of the projection weld nut.