Weld head position control system

Claim 2

In a control system for positioning a probe relative to a metallic workpiece to maintain the spacing between the probe and the workpiece within a predetermined range defined by first and second limits, an electric slide drive motor having one winding which when energized causes said probe to move toward Said workpiece and another winding which when energized causes said probe to move away from said workpiece, proximity sensing means including said probe for providing an output signal having a magnitude inversely proportional to the spacing between the probe and said workpiece, threshold detector means responsive to an output signal at a first level provided whenever the probe to workpiece spacing reaches said first limit to energize said one winding to cause said probe to move toward said workpiece, and thereafter to deenergize said one winding when the output signal increases to a second higher level when the probe to workpiece spacing is within said predetermined range said threshhold detector means being responsive to an output signal at a fourth level, which is higher than said second level, provided whenever the probe to workpiece spacing reaches said second limit to energize said another winding to cause said probe to move away from said workpiece, and thereafter to deenergize said another winding when said output signal decreases to a third level, which is higher than said first level, when the probe to workpiece spacing is within said predetermined range.

Claim 3

A control system as defined in claim 1, wherein said probe comprises a differential transformer having an input coil, two output coils coaxially disposed on opposite sides of said input coil and electrically connected together in polarity opposition to provide a probe output voltage, and a magnetic permeable core extending through the center of said coils and positioned for lowest null probe output voltage.

Claim 4

A control system as defined in claim 2, wherein said probe further comprises a copper null adjusting band disposed about said input coil and positioned axially to produce the lowest possible null probe output voltage.

Claim 5

A control system as defined in claim 2, wherein said proximity sensing means comprises an oscillator for energizing said input coil and an amplifier for amplifying said probe output voltage.

Claim 6

A control system as defined in claim 1, wherein said threshhold detector means comprises a pair of Schmidt triggers connected in parallel to the output of said proximity sensing means, one of said Schmidt triggers being energized by an output signal at said first level and being deenergized by an output signal at said second level, and the other of said Schmidt triggers being energized by an output signal at said fourth level and being deenergized by an output signal at said third level.

Claim 7

In a control system for positioning a probe relative to a metallic workpiece to maintain the spacing between the probe and the workpiece within a predetermined range defined by first and second limits, an electric slide drive motor having a first winding which when energized causes said probe to move toward said workpiece and a second winding which when energized causes said probe to move away from said workpiece, proximity sensing means including said probe for providing an output signal related in amplitude to the spacing between the probe and the workpiece, first switching means enabled whenever the amplitude of said output signal reaches a first level when the probe to workpiece spacing reaches said first limit to energize one of said windings, said first switching means being disabled to deenergize said first winding when the amplitude of said output signal reaches a second level which corresponds to a probe to workpiece spacing within said predetermined range, and second switching means enabled whenever the amplitude of said output signal reaches a fourth level when probe to workpiece spacing reaches said second limit to energize the other one of said windings, said second switching means being disabled to deenergize said other winding when the amplitude of said output signal reaches a third level which corresponds to a probe to workpiece spacing within said predetermined range, said first and third levels and said fourth and second levels being selected to prevent said first and second windinGs from being energized simultaneously.

Claim 8

In a control system for positioning a probe relative to a metallic workpiece to maintain the spacing between the probe and the workpiece within a predetermined range defined by first and second limits, an electric slide drive motor having a first winding which when energized causes said probe to move toward said workpiece and a second winding which when energized causes said probe to move away from said workpiece, proximity sensing means including said probe for providing an output signal related in amplitude to the spacing between the probe and the workpiece, first switching means enabled whenever the amplitude of said output signal reaches a first level when the probe to workpiece spacing reaches said first limit to energize one of said windings, said first switching means being disabled to deenergize said first winding when the amplitude of said output signal reaches a second level which corresponds to a probe to workpiece spacing within said predetermined range, and second switching means enabled whenever the amplitude of said output signal reaches a fourth level when probe to workpiece spacing reaches said second limit to energize the other one of said windings, said second switching means being disabled to deenergize said other winding when the amplitude of said output signal reaches a third level which corresponds to a probe to workpiece spacing within said predetermined range, said first and third levels and said fourth and second levels being selected to prevent said first and second windinGs from being energized simultaneously.

Claim 9

In a control system for positioning a probe relative to a metallic workpiece to maintain the spacing between the probe and the workpiece within a predetermined range defined by first and second limits, an electric slide drive motor having a first winding which when energized causes said probe to move toward said workpiece and a second winding which when energized causes said probe to move away from said workpiece, proximity sensing means including said probe for providing an output signal related in amplitude to the spacing between the probe and the workpiece, said probe including a differential transformer having an input coil connected to oscillator means for energizing said input coil and a pair of output coils electrically connected together in polarity opposition to normally provide a null output signal whenever the probe to workpiece spacing is approximately at the middle of said predetermined range and to provide an output signal of a first polarity whenever the probe to workpiece spacing increases toward one of said limits and an output signal of a second polarity whenever the probe to workpiece spacing decreases toward the other of said limits, and means responsive to the output signals provided by said proximity sensing means to selectively energize said first and second windings to maintain the probe to workpiece spacing within said predetermined range.

Claim 10

In a control system for positioning a probe relative to a metallic workpiece to maintain the spacing between the probe and the workpiece within a predetermined range defined by first and second limits, an electric slide drive motor having a first winding which when energized causes said probe to move toward said workpiece and a second winding which when energized causes said probe to move away from said workpiece, proximity sensing means including said probe for providing an output signal related in amplitude to the spacing between the probe and the workpiece, said probe including a differential transformer having an input coil connected to oscillator means for energizing said input coil and a pair of output coils electrically connected together in polarity opposition to normally provide a null output signal whenever the probe to workpiece spacing is approximately at the middle of said predetermined range and to provide an output signal of a first polarity whenever the probe to workpiece spacing increases toward one of said limits and an output signal of a second polarity whenever the probe to workpiece spacing decreases toward the other of said limits, and means responsive to the output signals provided by said proximity sensing means to selectively energize said first and second windings to maintain the probe to workpiece spacing within said predetermined range.