Obara Corporation

Teruzo Yamaguchi

Tatsuo Morita

There is provided a method of controlling an electrode pressure application force in an electric gun provided with the electrode at the tip end of a movable arm which is driven by an electric motor comprising steps of setting a limit torque of the electric motor in advance, continuously measuring and storing an arriving position of the electrode at the tip end of the movable arm when the electric motor is driven, calculating an average value of groups of data of the stored arriving position, and continuously controlling to correct the arriving position to average value.

Method of controlling electrode pressure application force in an

There is provided a method of controlling a pressure application resistant welding machine by setting in advance a danger region where a foreign matter is liable to be inserted, of reducing torque of an electric motor to an extent not to injure the foreign matter in the danger region so as to lessen a pressure applied to the foreign matter from the electrode, thereby performing a welding operation with safety and assurance. The method comprising steps of partitioning a moving region of the electrode into a safety region and a danger region, setting a range of the safety region to be substantially the same as a maximum thickness of a workpiece to be welded, setting a range of the danger region to be substantially the same as a thickness of a foreign matter to be inserted between the workpiece and the electrode, permitting a torque of an electric motor to generate a given pressure application force in the electrode in the safety region, permitting the torque of the electric motor in the danger region to be smaller than that in the safety region to an extent not to injure the foreign matter, recognizing the presence of the foreign matter in the danger region in response to an anomalous change of a current value of the electric motor to stop driving of the electric motor, and permitting the electrode to continuously perform a pressure application operation even if the current value of the electric motor is changed in the safety region.

Method of controlling a pressure application resistant welding machine

There is disclosed a welding transformer control apparatus capable of controlling the voltage supplied to the primary winding of the welding transformer. The welding transformer control apparatus comprises a voltage detecting circuit connected to the thyristor for detecting a power voltage and a digital operation unit connected to the voltage detecting circuit via an A/D converter for receiving the digital converted power voltage. The digital operation unit is also connected to a voltage setting unit for receiving a predetermined voltage to be supplied to the primary winding of the welding transformer. The digital operation unit compares the predetermined voltage supplied from the voltage setting unit with the power voltage supplied from the A/D converter and provides a signal to suppress the power voltage under the predetermined voltage. There is also provided a thyristor gate pulse generator connected between the digital operation unit and the thyristor for receiving the signal from the digital operation unit and providing a thyristor gate pulse to the thyristor so that the thyristor can effect striking cnrol, i.e., phase control of the power supplied in the primary winding of the welding transformer whereby the voltage supplied to the primary winding of the welding transformer can be controlled under the desired voltage.

Welding transformer control apparatus

There is disclosed a resistance measuring mechanism in a resistance welding machine for calculating a resistance value in an arbitrary portion of the resistance welding machine. The resistance measuring mechanism comprises means for detecting temperature of an exit through which cold water for cooling a cable flows and the temperature of parts of cables, means for detecting voltage at a secondary or a primary winding of a welding transformer and means for detecting welding current at the secondary or the primary winding of the welding transformer characterized in that resistance value at a measuring temperature is calculated by correcting the resultant detected temperature, voltage, welding current for voltage, welding current at a reference temperature.

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Tokyo, Japan

Teruzo Yamaguchi