Abstract: A control system for resistance welders of the type in which welding current is supplied to a workpiece through a transformer. The system assures weld quality by monitoring the change in resistance across the weld during the welding operation without the need for auxillary leads or separate sensing transducers at or near the workpiece and automatically terminates the welding current when a quality weld is made as determined by weld resistivity characteristics. The system monitors discrete changes in the characteristics of the current in the welding transformer which occur as a result of changes in weld resistance.

Abstract: A control system for resistance welders of the type in which welding current is supplied to a workpiece through a transformer. The system assures weld quality by monitoring the change in resistance across the weld during the welding operation without the need for auxillary leads or separate sensing transducers at or near the workpiece and automatically terminates the welding current when a quality weld is made as determined by resistivity characteristics of the weld. The system monitors discrete changes in the characteristics of the current in the primary of the welding transformer which occur as a result of changes in weld resistance. The system compares the monitored current characteristics of the welding current with a plurality of parameters indicative of a quality weld and terminates the welding current when a selected number of monitored characteristics are within selected parameters.

Abstract: A power supply for electric arc welding, particularly gas tungsten arc welding, is described. The supply operates from conventional, alternating potential, and provides either a direct current or an alternating current with a rectangular wave shape to a load. The supply includes an input transformer, and two current paths, each of which includes an inductor and a controlled rectifier. A control circuit initiates conduction of the rectifiers at appropriate times selected to obtain the desired load current. In preferred embodiments, the control circuit includes differential amplifiers which enable comparison of the output current to a control current, adjustment of the ratio of the currents in the two current paths, and adjustment of the gain and time constant of the control circuit.

Abstract: A method and apparatus for manufacturing a lamp involves preparing a lamp assembly having a base to which is coupled a bulb with external lead-in wires. One of the lead-in wires has an outer end which is drawn out between the bulb and the edge of the base. A potential is applied between a welding electrode of a welding device and the tip of the outer end of the external lead-in wire to weld the lead-in wire to the base. During this applying of potential, a gas flame is interposed between the outer end of the external lead-in wire and the welding electrode.

Abstract: A resistance-type welder employing a pulsed power supply and a pair of opposed electrodes between which a workpiece may be clamped under pressure, includes a microcomputer based control system for allowing precise selection and control of welding sequences such as the duration during which the workpiece is clamped, the duration during which current is supplied to the electrodes and the duration during which the workpiece remains clamped between the electrodes after current flow is terminated. A plurality of switchable input devices allows data corresponding to a plurality of process variables to be input to a random access memory. A central processor enabled by a manually operable control switch produces control signals for operating a control and firing circuit in accordance with programmed instructions and the data stored in the random access memory in order to control each step in a welding cycle for precise time periods.

Abstract: A Robot type resistance welder of very large capacity that enables the electrodes of the welder to be readily adjustable in the welding and retracting strokes and automatically controlled so as to retract when encountering an obstacle - also whereby the degree of retraction of electrodes may be selectively controlled and whereby the vertical elevation of the work plane may be varied during welding in accordance with the contour of the work, such as a curved panel. The respective electrodes of the spot welders have supporting arms which are pivotally interconnected together with an operating air cylinder. An adjustable stop is provided in the air cylinder to adjust the extent of retraction. The entire assembly including the pivotal supporting arms and inter-connected cylinder are provided with an adjustable stop for limiting the pivotal movement of the assembly. Such pivotal movement is cushioned by springs.

Abstract: Stick and stud welding apparatus which utilizes a microprocessor and related RAMs, ROMs and peripheral interface devices to control the welding parameters. The ideal desired weld current and weld cycles in the case of stud welding can be selected depending upon the mode of operation and/or stud conditions. The program for the microprocessor instructs the microprocessor to periodically compare the actual welding current to the ideal current, compute the difference and alter the phase firing time of an SCR bridge to compensate or adjust the welding current to the ideal current. In the case of stud welding mode, the program further instructs the microprocessor to reference the selected number of cycles, compute the total energy delivered across the stud and workpiece gap from actual current, welding terminal voltage and time and enlarge the number of actual weld cycles to a given percentage of that initially selected to provide a total energy input to the stud as selected.

Abstract: An arc welding apparatus includes means for controllingly supplying an output current to an arc-producing electrode, an output current setting unit for controlling the supplying means, means for feeding a filler wire, and means for applying voltage to the filler wire. A first function generator is connected between the output current setting unit and the feeding means for producing an output which is a function of an output current setting and which is delivered to the feeding means to control the rate at which the filler wire is fed. A second function generator is connected between the first function generator and the applying means for producing an output which is a function of the output from the first function generator and which is fed to the applying means to control the voltage applied to the filler wire.

Abstract: A precision key pad controlled controller for a resistance welding machine is provided which may be set to deliver welding power to each of a multiplicity of welding operations on a precisely controlled repeatable basis. The controller incorporates circuitry for assuring that an accurately controlled amount of power is delivered for each welding operation by providing precise phase angle control despite variations in line voltage and line disturbances. The controller is constructed to incorporate selected numbers of steps to be performed automatically in sequence by the controlled welding machine in carrying out a particular welding operation. The duration of each step of the welding machine, the amount of welding power to be delivered, and other parameters are set for each particular welding operation by the key pad, and displayed on an associated alphanumeric display.

Abstract: In a welding apparatus employing a switching element between a power source and a filler wire, a protection circuit operates to discontinue the function of the switching element when a short-circuit is detected between, for example, the filler wire and a welding electrode, so that the switching element is protected from damage due to an overcurrent.

Abstract: The flow of paint in a liquid paint stripe covering the inside of a side-seam weld extending along the top of a horizontally-disposed food can is controlled by applying induction heating to areas of the can on each side of the stripe, whereby a temperature gradient directed upwardly through the can is established to limit downward gravity flow of the paint before it sets, and thereby prevent formation of ridges and bubbles at the edges of the stripe.

Abstract: A spot weld control senses differences in welding current required to produce an optimum weld by determining the time rate of change of resistance during the increasing resistance portion of the weld cycle. The weld control can reduce the welding current if the time rate of resistance change exceeds a maximum value and increase the current if the resistance change is less than a minimum value. The weld current may be terminated when a decrease in resistance from the peak resistance value has reached a predetermined percentage of the peak resistance value or terminated after a predetermined number of current cycles.

Abstract: An improved process is disclosed for splicing metal shafts, in which a pair of shafts (10, 12 or 44, 46) having transverse end surfaces (30, 32 or 54, 56) preferably substantially normal to the axes of the shafts, are positioned coaxially with an insert (34, 48) positioned between and abutted to the end surfaces. The insert is tapered or wedge-shaped at either end to define transverse contact surfaces (18) which abut the end surfaces of the shafts. The angle (.beta.) of the taper on the insert permits insertion of a consumable arc welding electrode (20) into the convergent space defined between the end surfaces of the shafts and the tapered surfaces of the insert and is large enough to allow the arc welding electrode to be positioned at locations not only sufficiently spaced from both the tapered surfaces and the end surfaces but also sufficiently close to the area of abutment between the contact and end surfaces, to ensure proper welding penetration into the base metals.

Abstract: A microwave cooking container comprising a conductive layer to which is bonded a layer of material having high hysteresis loss at microwave frequencies. When subjected to microwave radiation the hysteresis loss material heats to its Curie point where its loss is substantially reduced while the dielectric loss is minimized by being effectively shielded by its proximity to the surface of the conductive layer. The conductive layer may be a metal dish cover whose outer surface supports a plastic bonded ferrite and whose inner surface contacts a food body in a metal dish. The Curie point region of the ferrite is lower than the degradation temperature of the plastic. Overlapping the walls of the dish and cover forms a microwave seal to prevent microwave heating of the dish contents.

Abstract: An induction heating coil for use in a cooking range or the like. The coil is defined by a flat spiral of electrically conducted wire having at least three radially related sections including a radially outermost section having closely spaced turns, a radially innermost section having closely spaced turns, and a radially intermediate section having widely spaced turns. In one form, the intermediate section turns are uniformly widely spaced. In another form, the intermediate section turns are arranged in widely spaced groups. The disclosed configurations provide a substantially uniform power transfer to the element being heated, such as a ferromagnetic utensil.

Abstract: Welding apparatus and a method of producing source of welding current. Use is made of an inverter supplied with direct current from a source to pulse a center-tapped primary winding of a transformer at a frequency in excess of the audio range of frequencies, typically 10 KHz to 20 KHz. A secondary winding of the transformer has output terminals for electrical connection to an electrode and work to be welded. The operation of the inverter is controlled by means of a feedback signal derived from a winding inductively coupled to the transformer.The high operating frequency results in a significant reduction in the mass and dimensions of the welder compared to conventional welders which operate at mains frequencies.

Abstract: A humidity sensitive resistance device, including opposing electrodes (102, 103) formed on an insulating substrate (101), and a humidity sensitive resistance film (104) formed on the surface of the insulating substrate (101) and at least between the opposing electrodes (102, 103). The resistivity of the humidity sensitive resistance film (104) increases with an increase of an ambient relative humidity. The humidity sensitive resistance film (104) comprises a hydrophilic polymer and a conductive powder, and has a zirconium compound unevenly distributed on the side of surface thereof. The surface of the humidity sensitive resistance film (104) is dehydrated by contact with an alkaline solution or by heating.

Abstract: A gas tungsten arc welding torch suitable for robotic welding has an improved built-in optical vision sensor which images the weld puddle and weld region on the face of a fiber optic cable; the image is relayed to a video camera and computer to control the torch motion and weld process. The electric arc is much brighter than the area around the arc it is desired to image. A shaped blocking device on the tungsten electrode, such as a molybdenum sleeve or collet set back so that the arc is undisturbed, prevents the arc from being imaged and eliminates image distortions caused by the presence of the bright arc.

Abstract: A fail-safe voltage reducing circuit for an arc welder. The welding transformer has two primary windings connected in parallel across a power source. After an arc is struck, if the arc is then broken for a predetermined time period, the circuit automatically disconnects one of the primary windings from the power source, thereby reducing the voltage across the welder's output terminals to a safe standby voltage lower than the full open circuit voltage. If the voltage has not been reduced after a second predetermined time period, the fail-safe feature of the circuit automatically disconnects both primary windings from the power source, thereby completely removing all power from the welder.

Abstract: In a thermal print head employing a line of print elements, temperature sensing is effected by means of an elongated temperature sensing device positioned in parallel with the line of elements and in heat-transfer proximity thereto. The sensor may be of thermo-resistive material and is coupled to a control circuit to effect energy control of drive pulses to the print elements.