We claim:
1. A protection system for gantry cranes having a projecting cantilever boom suspended from girder support crossbeams which are part of the crane superstructure which is supported by a crane mainframe, said system comprising
a pair of variable range laser guns suspended from said superstructure and positioned on opposite sides of said boom and laterally spaced therefrom and disposed slightly below said boom, said laser guns having a reflective range setting proximate to the distance from said laser guns to the outboard end of said boom and being aimed parallel to the longitudinal axis of said boom, and
means responsive to a reflection of laser beams emanating from said laser guns for actuating a crane translational motion speed alteration and alerting operators of said crane to said beam reflection.
2. The protection system of claim 1 wherein said responsive means actuates an automatic crane traverse speed slowdown.
3. The protection system of claim 1 wherein said laser guns are spaced laterally from the sides of said boom a pre-selected distance whereby actuation of said system by a beam reflection in turn actuates a crane translational motion shutdown which permits said crane to halt translational motion in said pre-selected distance.
4. A method of protection for gantry cranes having a projecting cantilever boom suspended the crane superstructure, the steps comprising
locating distance ranging laser beam generators proximate to said crane superstructure,
aiming said lasers outboard therefrom below and parallel to the sides of said boom,
mounting a photodetector proximate to said laser beam generators,
exciting said lasers when said boom is lowered,
actuating a responsive means if a laser beam is reflected to said photo detectors, and
slowing any lateral movement of said crane if said responsive means indicates a possible collision of said boom with a mechanical interfering object.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A stud welding device, comprising:
a stud welding power supply having a welding power output;
a stud welding power controller communicatively coupled to the stud welding power supply; and
a workpiece sensor communicatively coupled to the stud welding power controller, wherein the stud welding power controller is responsive to a signal from the workpiece sensor indicative of a position of a stud in general proximity or engagement with a workpiece, wherein the workpiece sensor, or the stud welding power controller, or a combination thereof, is configured to apply an open circuit test voltage of substantially less than a welding voltage to the stud and to measure a feedback parameter.
2. The stud welding device of claim 1, wherein the stud welding power controller is configured to enable a welding power level or range in response to a first state of the signal, and the stud welding power controller is configured to disable or prevent the welding power level or range in response to a second state of the signal.
3. The stud welding device of claim 1, comprising an automatic stud welding gun positioning device, a factory automation system configured to position the stud welding gun on a workpiece, a weld cable, a control cable, a workpiece, or any combination thereof.
4. The stud welding device of claim 1, wherein the stud welding power supply is a DC power supply comprising a transformer with a primary side and a secondary side, and wherein the workpiece sensor comprises a voltage sensor connected to the primary side of the transformer.
5. The stud welding device of claim 1, wherein the stud welding power controller is configured to trigger a 2 second or less pulse of welding current through the welding power output at least partially in response to a state of the signal from the workpiece sensor.
6. The stud welding device of claim 1, wherein the stud welding power controller is configured to respond to a state of the signal from the workpiece sensor by, at least in part, preventing the stud welding power supply from conducting a welding current through the welding power output.
7. The stud welding device of claim 1, wherein the signal from the workpiece sensor is indicative of electrical contact between the stud and the workpiece.
8. The stud welding device of claim 1, wherein the workpiece sensor comprises a low voltage power source connected to the welding power output and a voltage sensor connected to the welding power output.
9. The stud welding device of claim 8, wherein the low voltage power source has an open circuit voltage of less than 35 volts when energized, and wherein the signal from the workpiece sensor is at least based on a voltage of the stud measured by the voltage sensor.
10. A welding device, comprising:
stud welding controller responsive to a signal indicative of generally no contact between a welding stud and a workpiece, wherein the stud welding controller is configured to respond to the signal by at least substantially reducing, disabling, or preventing a welding output from a welding power supply; and
a workpiece sensor configured to transmit the signal indicative of generally no contact, the workpiece sensor comprising a capacitance sensor, an eddy current sensor, a metal detector, a contact sensor, or a combination thereof.
11. The welding device of claim 10, wherein the stud welding controller is configured to disregard the signal for at least a stud welding duration after the welding power supply provides the welding output.
12. The welding device of claim 10, wherein the stud welding controller is configured to respond to a signal indicative of contact or no contact by transmitting a stud-lifting control signal, triggering a pulse of normal welding current, and transmitting a stud-plunging control signal.
13. The welding device of claim 10, comprising:
a welding power supply having a welding current lead;
wherein the workpiece sensor comprises:
a low voltage DC power source coupled to the welding current lead, wherein the low voltage DC power source has an open circuit voltage of less than 30 volts when energized; and
a voltage sensor electrically coupled to the welding current lead and communicatively coupled to the stud welding controller, wherein the signal indicative of generally no contact is a signal from the voltage sensor indicating that a voltage of the lead is greater than a threshold voltage.
14. A method, comprising: providing a stud welding power control unit with a stand-by open circuit voltage less than a welding voltage
when energized, wherein providing the stud welding power control unit comprises providing a stud welding power control unit with a stand-by open circuit voltage less than 35 volts when energized.
15. A method, comprising: providing a stud welding power control unit with a stand-by open circuit voltage less than a welding voltage
when energized, wherein providing the stud welding power control unit comprises providing a stud welding power control unit with a stand-by test current of less than 100 milliamps.