Abstract: A nut feeding apparatus for feeding a weld nut to an upper electrode of a resistance welding machine, whose size and production cost are reduced, is disclosed. The apparatus comprises a piston rod, a tension rod, a tube, a link mechanism and a nut chuck. When the piston rod is in a most retracting state, an upper surface of the nut chuck becomes substantially flush with a lower portion of an opening of the tube. While the tension rod is at a stop in a most advancing state and when the piston rod further advances, the link mechanism rotates around a rotation axis at a tip of the tension rod, and thereby, the weld nut held by the nut chuck moves to a feeding position of the weld nut in the upper electrode.

Abstract: A resistance spot welder includes: a motor, having a shaft; a cylindrical casing; a hollow guide rod, inserted into the casing, and adapted to be moved linearly for moving a first electrode tip facing a second electrode tip provided at a gun arm; a ball nut, fixed in an inner circumference of the guide rod; a ball screw, fitted through the ball nut; a coupling, including a first fastening portion into which the shaft of the motor is inserted and a second fastening portion into which the ball screw is inserted and which is opposite to the first fastening portion; and a bearing, fitted between an outer circumference of the first fastening portion and an inner circumference of the casing. The guide rod is moved between a first point which is a motor side and a second point which is an electrode tip side. When the guide rod is positioned at the first point, the guide rod accommodates at least a part of the second fastening portion.

Abstract: A resistance spot welder including a first plate, a second plate rotatably connected to the first plate through a shaft and driven on the shaft by an actuator, gun arms removably fixed on and electrically insulated with the first and second plates, and electrode tips confronting each other and fixed on the gun arms.

Abstract: A cable monitoring system, which monitors failure of a plurality of cables connecting a power supply and a welding gun, has voltage detection lines connected to arbitrary two points of each of the cables, an insulating transformer a primary side of which is connected to the voltage detection lines of each cable, and a failure detector connected to a secondary side of the insulating transformer and detecting failure of each cable based on voltage on the secondary side of the insulating transformer for each cable.

Abstract: In a vibration type parts feeding method and a vibration type parts feeding device, welding nuts are put on a parts transportation track arranged in an inner wall of a vibration bowl of a parts feeder to be arranged in turn, and normal positioned welding nuts are sorted and transported from a parts discharging outlet at a top end portion of the track to a desired place. A sorting unit for passing only the normal positioned welding nuts is installed detachably adjacent to the parts discharging outlet of the vibration bowl, and thus, it becomes possible to adapt to sorting upward and downward-positioned welding nuts with various kinds of shapes and dimensions.

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 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: 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: In a resistance spot welder in which an operation of pressurizing an electrode is conducted by an electric servo motor, an amount of thermal expansion due to production of a weld nugget is detected every moment by reading an encoder which is incorporated in the servo motor. When the detected amount of thermal expansion reaches a preset reference value, it is judged that the weld nugget attains a predetermined strength, thereby stopping a current supply. According to this configuration, a predetermined amount of input heat is ensured, so that an excellent welding quality is surely obtained.

Abstract: A motor-driven resistance spot welding machine includes: a drive rod having an electrode tip on an end thereof and making a linear motion; a linear guide for guiding the linear motion of the drive rod, the linear guide including a bearing; and a reduction gear being supported by a gun arm or a gun bracket. The machine also linearly drives the drive rod in an electrode force direction by transmitting an output torque of an electric motor to the reduction gear. In the machine, a rear portion of the drive rod is connected to a swing lever through a link, the swing lever being secured either to an output shaft of the reduction gear or to a main body of the reduction gear, whereby an arcuate motion is transmitted to the swing lever by an output of the electric motor, and is then converted into a linear motion of the drive rod by the link to thereby drive the drive rod so as to apply electrode force.

Abstract: A motor-driven X-type resistance spot welding gun. A servo-controlled motor torque is converted into force to drive gun arms and into electrode force by using a reduction gear without converting rotational output of the motor into rectilinear motion. The two arms are respectively attached to an output shaft of the reduction gear or a case, and the rotational output of the motor can be converted into swing-wise movement to close and open the arms. The electrode tips on the arms nip a workpiece to apply electrode force to the workpiece, and current is passed through the workpiece to perform spot welding. A motor, a reduction gear and the like are assembled on a common base to form a driving unit so that an arm actuator for the X-type resistance spot welding gun is formed. The same driving unit can be used commonly to various X-type gun models. The independent properties of functions of a bracket for attaching the welding gun to a robot are improved.

Abstract: A welding apparatus for welding hard segments to the circumference of a base of a saw blade. The blade base is clamped between two electrodes of a first electrode unit which can rotate. The segment is clamped by conductive fingers of a second electrode unit which is movable toward the first electrode unit. A power clamp presses together the conductive fingers together. The second electrode unit can rock to uniformly press the segment against the circumference of the blade base.

Abstract: A secondary conductor supervising device of a resistance welder control system for supervising short-circuit, disconnection, and/or deterioration of a secondary conductor by means of a current flowing through a resistance welder, which comprises a voltage detecting circuit for detecting a voltage from the secondary conductor, inclusive of a secondary cable, of the resistance welder, a current detecting circuit for detecting a current flowing through the resistance welder, a divider for dividing the output of the voltage detecting circuit by the output of the current detecting circuit, an average computer for averaging the output of the divider over a part or the whole of a welding period, a supervisory level setting unit for setting a resistance value such as of the secondary conductor, and a comparator for comparing the output of the setting unit with the output of the average computer based on the welding period.

Abstract: A spot welding control method is disclosed wherein the welding current and welding time are controlled, in response to changes in the shape of the point of the electrode tip. At each weld point, the lowest value of the varying resistance between the electrode tips is detected in an initial welding period, and each detected lowest value is successively held and stored. At each weld point, a running average of the lowest resistance values is computed, bases on the resistance date of a group of weld points composed of the weld point just completed through a number of preceding weld points, the number of which is preset. The weld conditions are changed from one set of predetermined parameters to another when the computed average reaches the then prevailing threshold limit, following which the threshold is reset. The thresholds are preset depending upon the degree of wear of the electrode tip, whereby welding is continued under newly-selected weld conditions corresponding to the present threshold.

Abstract: A method of controlling constant-current for resistance welding machines comprising the steps of: detecting the welding current flowing into the primary coil or the secondary coil of a welding transformer, applying a first half-wave current having a predetermined first phase control angle, detecting the current value and the current conduction angle at that time, calculating a power factor angle of the resistance welding machine from the detected conduction angle and the phase control angle, calculating a second phase control angle, by which a current value corresponding to a previously set value of the next half-wave of current is obtained, from the calculated power factor angle, the detected conduction angle and the detected of current value, applying the next half-wave current at the second phase control angle through a thyristor circuit to a work to be welded, and repeating the above control operation during an entire welding cycle.

Abstract: A control method of resistance welding for controlling weld conditions, such as welding current and welding time, in response to a change in material of weldments, which comprises the steps of detecting the local lowest value of resistance between electrode tips appearing in an initial welding period, comparing the detected lowest value with a plurality of reference resistance values preset correspondingly to materials of weldments of different sorts and divided into plural classes to determine the material of a weldment under process, and changing the weld conditions, such as welding current and welding time, depending upon the determined material.