Abstract:
Stick and stud welding apparatus which utilizes a microprocessor (30) and related, RAMs (32) ROMs (33) and peripheral interface devices (3 1, 32, 35) 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. In the stud mode, the pilot arc current and cycles may likewise be selected and controlled. Such parameters as pilot arc current, pilot arc cycles, main welding current, main welding current cycles, total energy, welding terminal voltage and error occurrence are displayed visually by means of lights (28) and/or written printout (29).
Abstract:
Welding apparatus including a welding gun for holding a stud to be welded to a workpiece and a source of welding energy including a capacitor together with current control means for discharging the capacitor across the stud and workpiece to effect the weld where the current control means includes a gating rectifier between the capacitive power supply and the stud and workpiece and a bleed resistor across the capacitive power supply and a cathode of the gating rectifier and parallel to the stud and workpiece to control dV/dt between the anode and cathode of the gating rectifier.
Abstract:
A temperature-compensating circuit which employs a voltage divider across a battery to be charged which has a thermistor in one leg thereof and a capacitor across the opposite leg thereof. The capacitor, on reaching a predetermined charge, supplies a gating pulse through a unijunction transistor to a silicon controlled rectifier which operates a relay for discontinuing charging of the battery. A relay in the discharge circuit of the welding apparatus senses welding current and breaks the current flow through the silicon-controlled rectifier to deenergize the relay and reset the circuit for recharging of the battery following partial discharge thereof. A capacitor in parallel with the relay maintains the relay energized a predetermined time to prevent recharging of the battery until the welding cycle is completed.
Abstract:
Apparatus and method for welding hollow studs (spuds) over a hole in a workpiece which includes the use of a hollow arc shield disposed within the hollow spud and having one end thereof projecting into the hole in the workpiece to provide alignment for the spud over the hole and to maintain the hole free of molten metal during the welding operation. The spud preferably includes a chamfer in the weldable end thereof. The chuck for retaining the spud includes a second chuck therein for retaining one end of the internal arc shield and serves both as a retainer for the arc shield and as a stop member for the spud.
Abstract:
Coordinator for coordinating the operation of a stud welding controller, a stud welding gun and mechanism for automatically feeding studs to a welding gun including circuit means for overriding the welding cycle initiating signal whenever the welding gun is not in the welding position and for completing a circuit for initiating automatic stud feeding whenever the welding gun is in other than its welding position. A manually operable stud feeding circuit is included. An AND gate is employed in the automatic stud feeding circuit to prevent stud feeding until both a stud welding cycle initiating signal and a stud feeding signal are received. The welding cycle initiating circuit and the manually operable stud feeding circuit include memory circuits which maintain the signals from the circuits for a predetermined period of time determined by a preset timer which is initiated by passage of a signal through the AND gate and which resets the memory circuits upon timing out.
Abstract:
Stick and stud welding apparatus which utilizes a microprocessor (30) and related, RAMs (32) ROMs (33) and peripheral interface devices (3 1, 32, 35) 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. In the stud mode, the pilot arc current and cycles may likewise be selected and controlled. Such parameters as pilot arc current, pilot arc cycles, main welding current, main welding current cycles, total energy, welding terminal voltage and error occurrence are displayed visually by means of lights (28) and/or written printout (29).
Abstract:
Apparatus and methods for replacing or repairing missing or damaged abrasion resistant wearbars utilized in high velocity cyclone boilers. A retrofit wearbar having an aperture therein is utilized in conjunction with an end weldable stud wherein the wearbar and stud are placed in position over a damaged wearbar or against the boiler tube in the case of a missing wearbar and the stud end welding technique utilized to fuse the wearbar and stud in place with the damaged wearbar or boiler tube in the case of a missing wearbar in situ. An arc shield is utilized which has a projection from the weld fillet cavity thereof which cooperates in conjunction with the aperture of the retrofit wearbar to provide alignment of the stud in the wearbar and prevent shorting of the stud to the wearbar during the welding cycle.