Abstract: An improved welding apparatus having an electric motor driven electrode carriage assembly, is disclosed. The carriage assembly is capable of carrying the electrode either towards or away from a workpiece depending upon the direction of rotation of the electric motor. An electric switch and a control unit is operatively associated with the electrode carriage assembly for the switch to be tripped when the electrode in its movement toward the workpiece physically contacts the workpiece. Tripping of the switch sends an appropriate signal to the control unit to reverse rotation of the electric motor for a predetermined time period whereby the electrode is carried to a predetermined distance from the workpiece.

Abstract: An arc welding apparatus is disclosed wherein an electrode carriage is mounted to occupy two positions relative to a lead screw-threaded sleeve assembly which carries the electrode carriage toward or away from a workpiece. Direction of lineal movement of the lead screw-threaded sleeve assembly is determined by the direction of rotation of a motor which rotates the lead screw. The electrode carriage is moved from its first position relative to the lead screw-threaded sleeve assembly to its second position substantially simultaneously with the contact of the electrode with the workpiece. An electric switch is operatively associated with the electrode carriage to be tripped when the electrode carriage moves from the first position to the second position. Tripping of the switch causes a control unit to reverse rotation of the motor for a predetermined time whereby the electrode is carried to be a predetermined distance from the workpiece.

Abstract: A method of welding metal articles along a joint using a non-overhanging torch, for example so called butt welds in a vertical or upright position, of the kind which uses a pulsed arc with gaseous protection and a cored wire electrode, is characterized by use of the following combination:(a) the "pulsed" arc is of the constant frequency pulse type with transfer of molten material at each pulse, without setting up any short circuit, viz. of the "spray arc" kind and (b) the cored wire electrode is of the basic kind.

Abstract: A pulse arc welding machine including a wire electrode, a wire feeding unit for feeding the wire electrode to a base material, a base current source for supplying a base current between the wire electrode and the base material, a pulse current source for supplying a pulse current superposed on the base current, a detector for detecting the arc discharge voltage between the wire electrode and the base material, and a controller. The controller compares a detected output value from the detector with a preset reference value to thereby control the amount of heat applied to the wire electrode wherein the arc voltage between the wire electrode and the base material is maintained substantially at a value determined by the reference value.

Abstract: A method and device for automatically controlling welding conditions for use in an arc welding machine, wherein an ignition or turn-on phase of a thyristor is controlled by an output of a first potentiometer to which a fixed voltage is applied. A voltage difference between the movable terminals of the first and a second potentiometer which are coupled in parallel, is detected by a differential amplifier which outputs a signal corresponding to the difference to a motor. The motor turns the movable terminals of the second and a third potentiometer which are operated synchronously, so that the detected difference may be zero. The output of the third potentiometer to which a fixed reference voltage is applied, is stored in a memory in a recording mode.

Abstract: In a two electrode welding method wherein welding is carried out by means of arcs struck between two electrodes and a parent metal, the two electrodes being located in side-by-side, spaced-apart relation in a direction in which the welding surface advances and movable relative to the parent metal, a portion of the parent metal is preheated by the arc struck between the leading electrode and the parent metal, and a preheated portion is melted by the heat of the arc struck between the trailing electrode and the parent metal when the former has moved to a position above the preheated portion of the latter to provide a deposited metal. The method has particular utility in applications where metal of high heat conductivity, such as copper, is welded.

Abstract: In a three phase welding power supply, the three phase power is connected to a welding arc by a power control circuit having three conducting paths for straight polarity current and three conducting paths for reverse polarity current. The power control circuit comprises a three phase bridge rectifier circuit having eight bridge arms each including a silicon controlled rectifier with the bridge circuit being connected between the three phase power source and the welding arc which is in turn connected to the three phase power supply neutral. An inductor is connected across the direct current terminals of the bridge circuit so that arc current flows in one direction through the inductor regardless of the polarity of the arc current. The conducting paths are selectively activated at non-zero voltage points to conduct repetitive sequences of independent numbers of straight polarity half cycles of arc current followed by independent numbers of reverse polarity half cycles of arc current to the welding arc.

Abstract: In accordance with the method, the arc supplying current is modulated if necessary for generating an acoustical signal. The acoustical signal generated by the arc is detected and its amplitude which, in practice, is a direct function of the actual length of the arc, is compared to a reference amplitude corresponding to the desired length of the electrical arc, in order to determine the algebraic value of their difference. This algebraic value is used for monitoring at least one element of the machine between which the arc forms, and moving this element proportionally to the so-determined algebraic value in order to increase or reduce the actual length of the arc and to bring this length back to the desired length.

Abstract: In a method for welding a lead wire or bonding wire from a microcircuit chip mounted on a lead frame to a lead frame finger, the lead frame finger is preheated prior to any substantial electrical or thermal coupling between the lead frame finger and chip. Intense but controlled energy is applied to the lead frame finger at levels which might otherwise damage the IC chip. In one embodiment the lead frame finger is preheated to a temperature below the melting point of the metal comprising the lead frame. Enhanced bonding is thereafter effected by thermocompression bonding etc. In another embodiment the preheating step comprises melting a portion of the surface of the lead frame finger, forming a molten pool or puddle in the surface. Bonding of the lead wire is effected by immersing a section of the wire in the molten pool or puddle. In order to preheat the lead frame finger a controlled pulse train is delivered for arc discharge at the bonding location.

Abstract: In an automatic arc-welding method, which comprises: continuously moving a carriage along the longitudinal direction of a groove formed between the objects of welding; reciprocally moving in the width direction of the groove a welding electrode directed substantially vertically to said groove through a welding torch fitted to said carriage, following the groove face of said groove; producing an arc between the top of said electrode and said groove; moving said torch vertically up and down so that the value (E.sub.v) of the arc voltage or arc current agrees with a previously set value (E.sub.o); on the other hand, continuously detecting a vertical position of said torch as a value of voltage (e.sub.Y) indicated by a potentiometer; reversing the direction of movement of said torch in the width direction of said groove at the moment when said value of voltage (e.sub.

Abstract: A method and system for determining weld quality in resistance welding in such a manner that acceptance or unacceptance is determined by comparing with their respective reference values the electrode voltage, the electrode current time, the number of electrode voltage pulse signals in excess of the reference value, and the integral of difference between the electrode voltage in excess of a base voltage and the base voltage, independently or simultaneously, in addition to the comparison of the electrode resistance with its reference value. The relatively low-priced system according to the present invention can determine weld quality accurately even when the electrode tips are deformed or crushed so as to form other current path areas.

Abstract: A method and apparatus for detecting the point of contact between a workpiece of electrically conductive material in a machine and an electrically conductive element movable relative to and insulated from the workpiece, such as the electrode of an electrical discharge machine, wherein in a time-varying signal, in particular sinusoidal, of predetermined amplitude and frequency is applied to the workpiece, a signal is derived from the conductive element or electrode resulting from the flow of current through the gap between the workpiece and conductive element in response to the applied signal, and the applied and derived signals are compared as to amplitude and phase angle. An indication of the comparison is provided with the result that the combination of an amplitude difference and a phase difference between the applied and derived signals indicates the status of the contact gap, respectively, between the workpiece and conductive element or electrode.

Abstract: A method for controlling selected switching between preset welding schedules in a MIG welding operation, in response to operation from a single control switch having only on and off signal selections.

Abstract: A pulse arc welding machine in which, when any one of the material and diameter of a consumable wire electrode or the shielding gas used is varied, a peak current value and pulse width of a pulse current applied between a consumable wire electrode and a base material being welded as well as a wire feeding speed required for optimum welding conditions are automatically adjusted. The welding machine includes a consumable wire electrode, a wire feeding unit for the wire electrode, a base current source, and a pulse current source for supplying a pulse current superposed on the base current. A sensor detects the arc discharge voltage between the consumable electrode and the base material being welded. The quantity of heat applied to the electrode is corrected by comparing an output detection signal produced by the sensor with a preset arc voltage and then producing a pulse width instruction signal in response to the difference signal for setting the pulse width of the pulse current.

Abstract: A method and apparatus for controlling the travel speed of automatic welding machines uses a rotatable member which is engaged with the workpiece as the workpiece is moved relative to the welding head. The rotatable member advantageously includes one or more apertures on one side of which light is directed and the opposite side of which light pulses are received during rotation of the member and these pulses are used as an indication of the speed of the welding machine. In the preferred apparatus a separate frictional member is frictionally engaged with the workpiece and moved by the movement of the workpiece relative to the welding head and through suitable gearing drives the rotatable member having the aperture.

Abstract: In the electrical discharge machining of the surface of a recess in a workpiece electrode to a shape corresponding to that of a tool electrode, the electrodes are relatively displaced, during a finishing phase of machining, along an axis of penetration and simultaneously in a plane perpendicular to the axis of penetration with a cyclic translational movement whose amplitude increases with the penetration of the tool in the workpiece. This provides a virtual 3-dimensional dilatation of the tool as it advances, and enables control of the sparking in both the frontal and lateral parts of the machining zone, such that the shape of the machined portion is an image of the tool shape. The cyclic translational movements can be obtained with an eccentric member whose eccentricity relative to a shaft is controlled by limiting axial movement of the shaft at a position corresponding to a predetermined penetration.

Abstract: A pulse arc welding machine in which the repetition frequency of the pulse currect is unaffected by the frequency of the power source and the mean value of the pulse current applied can be accurately controlled over a broad range while the arcing is maintained stable. A pulse peak current supplying circuit is connected in series with an arcing region formed between a consumable wire electrode and a material to be welded between the output terminals of a standard direct current source while a base current supplying circuit is connected in parallel with the pulse peak current supplying circuit. The pulse peak current supplying circuit and the base current supplying circuit are both composed of a switching element such as a transistor coupled in series with an inductive element. Diodes are provided for suppressing high voltage transients in the circuit.

Abstract: In the electrical discharge machining of the surface of a recess in a workpiece electrode to a shape corresponding to that of a tool electrode, a method whereby the electrodes are relatively displaced, during a finishing phase of machining, along an axis of penetration and simultaneously in a plane perpendicular to the axis of penetration with a cyclic translational movement whose amplitude increases with the penetration of the tool in the workpiece. This provides a virtual 3-dimensional dilatation of the tool as it advances, and enables control of the sparking in both the frontal and lateral parts of the machining zone such that the shape of the machined portion is an image of the tool shape. The cyclic translational movements can be obtained with an eccentric member whose eccentricity relative to a shaft is controlled by limiting axial movement of the shaft at a position corresponding to a predetermined penetration.

Abstract: In the electrical discharge machining of the surface of a recess in a workpiece electrode to a shape corresponding to that of a tool electrode, the electrodes are relatively displaced, during a finishing phase of machining, along an axis of penetration and simultaneously in a plane perpendicular to the axis of penetration with a cyclic translational movement whose amplitude increases with the penetration of the tool in the workpiece. This provides a virtual 3-dimensional dilatation of the tool as it advances, and enables control of the sparking in both the frontal and lateral parts of the machining zone, such that the shape of the machined .[.position.]. .Iadd.portion .Iaddend.is an image of the tool shape. The cyclic translational movements can be obtained with an eccentric member whose eccentricity relative to a shaft is controlled by limiting axial movement of the shaft at a position corresponding to a predetermined penetration.

Abstract: An a.c. operated arc welding current supply unit comprises a frequency converter of the series capacitor type and operating with a half period which is substantially less than the average duration of the current and voltage transients caused by short circuits through droplets of weld material during welding. The frequency converter is connected to welding electrodes through a transformer in series with a rectifier to provide direct current for the welding electrodes, and the frequency converter is associated with a control device for controlling the operating frequency of the converter in a manner such that it is substantially inversely proportional to the square of the input voltage of the current supply unit, thereby maintaining the power output of said unit substantially unchanged irrespective of changes in load caused by the welding operation and irrespective of variations in said input voltage.