Sidewall-matching adaptive control system for welding

In an apparatus for arc welding a joint in a workpiece, the apparatus including arc cross-seam moving means for oscillating an arc electrode laterally across the joint about a predetermined center reference point between a left extreme and a right extreme, the improvement comprising:

• (a) arc parameter measuring means for providing an arc signal having a magnitude related to the distance between the electrode and the surface of the joint as the electrode moves laterally across the joint between said extremes;
• (b) noncontacting means for sensing the lateral profile of the joint by periodically holding the electrode vertically stationary and for providing lateral profile data comprising a plurality of samples of said arc signal;
• (c) memory means for storing said lateral profile data;
• (d) signal processing means for providing an error signal based upon a computed difference between a first portion of said lateral profile data and a second portion of said lateral profile data;
• and
• (e) control means responsive to said error signal for adjusting a welding parameter to reduce said error signal, whereby said computed difference is reduced between said first portion and said second portion of said lateral profile data.

In an apparatus for arc welding a joint in a workpiece including arc cross-seam moving means for oscillating an electrode laterally across the joint about a predetermined center reference point between a left extreme and a right extreme, the improvement comprising:

• (a) arc parameter measuring means for providing an arc signal having a magnitude related to the distance between the electrode and the surface of the joint between said extremes;
• (b) selectively operable electrode vertical moving means for periodically holding the electrode vertically stationary while the electrode moves laterally across the joint;
• (c) first means for accumulating a first plurality of samples of said arc signal during the movement of the electrode laterally in a first direction with respect to said predetermined center reference point towards a sidewall of the joint and while the electrode is held vertically stationary
• (d) second means for accumulating a second plurality of samples of said arc signal during the movement of the electrode laterally in a second direction with respect to said predetermined center reference point towards a sidewall of the joint and while the electrode is held vertically stationary;
• (e) signal processing means for processing said first plurality of samples and said second plurality of samples and for providing a correction signal based on a mathematical function of said first plurality of samples and said second plurality of samples;
• and
• (f) means responsive to said correction signal for adjusting a welding parameter.

In an apparatus for arc welding a joint in a workpiece including arc cross-seam moving means for oscillating an electrode laterally across the joint about a predetermined center reference point between a left extreme and a right extreme, the improvement comprising:

• means for obtaining data representative of the leftward portion of the lateral profile of the joint while the electrode is held vertically stationary and while the electrode is moving laterally in a first direction with respect to said center reference point toward said left extreme;
• means for obtaining data representative of the rightward portion of the lateral profile of the joint while the electrode is held vertically stationary and while the electrode is moving laterally in a second direction opposite said first direction toward said right extreme;
• means for comparing said leftward portion data and said rightward portion data and for generating an error signal;
• and
• control means responsive to said error signal for adjusting a welding parameter.

An adaptive control apparatus for arc welding a joint in a workpiece with an arc welding electrode, comprising:

• (a) means for periodically holding the electrode vertically stationary;
• (b) arc parameter measuring means for providing an arc position signal having a magnitude related to the distance between the electrode and the surface of the joint while the electrode is held vertically stationary;
• (c) arc cross seam moving means for moving the electrode laterally across the joint;
• (d) first averaging means for averaging the magnitude of said position signal during the movement of the electrode laterally in a first direction with respect to a preselected center reference point towards a preselected first extreme of movement, said first averaging means providing a first average;
• (e) second averaging means for averaging the magnitude of said position signal during the movement of the electrode laterally in a second direction with respect to said reference point towards a second preselected extreme of movement, said second averaging means providing a second average;
• (f) means for comparing said first average and said second average and for providing a correction signal related to the difference between said first average and said second average;
• and
• (g) control means responsive to said correction signal for adjusting a welding parameter.

An adaptive control apparatus for arc welding a joint in a workpiece with an arc welding electrode, comprising:

• (a) means for periodically holding the electrode vertically stationary;
• (b) arc parameter measuring means for providing an arc position signal having a magnitude related to the distance between the electrode and the surface of the joint while the electrode is held vertically stationary;
• (c) arc cross seam moving means for moving the electrode laterally across the joint;
• (d) first integrating means for integrating said position signal while the electrode is moving laterally in a first direction with respect to a preselected center reference point towards a first extreme of movement and for providing a first integral;
• (e) second integrating means for integrating said position signal while the electrode is moving laterally in a second direction with respect to said reference point towards a second extreme of movement and for providing a second integral;
• (f) means for comparing said first integral and said second integral and for providing a correction signal related to the difference between said first integral and said second integral;
• and
• (g) control means responsive to said correction signal for adjusting a welding parameter.

An adaptive control apparatus for arc welding a joint in a workpiece with an arc welding electrode, comprising:

• (a) means for periodically holding the electrode vertically stationary;
• (b) arc parameter measuring means for providing an arc position signal having a magnitude related to the distance between the electrode and the surface of the joint while the electrode is held vertically stationary;
• (c) oscillation means for oscillating the electrode laterally across the joint about a center reference point in a first direction and an opposite second direction;
• (d) integrating means for providing an integral signal corresponding to the integral of said arc position signal during a predetermined time period which begins when the electrode is a first predetermined distance from said center reference point;
• (e) comparing means for comparing said integral signal to a reference value, said reference value being related to stored reference data, said comparing means being responsive to provide a reversal signal when said integral signal substantially equals said reference value;
• (f) oscillation reversal means responsive to said reversal signal for causing said oscillation means to cease moving the electrode in said first direction and to begin moving the electrode in said second direction;
• (g) memory means for storing said reference data, said reference data comprising a plurality of arc position signals from a plurality of prior oscillations of the electrode;
• and
• (h) reference value computing means for providing said reference value based on said stored reference data.