Apparatus for tracking a seam

Apparatus for tracking a seam between two ferromagnetic members and controlling a work element to move along a path overlying the seam, the apparatus comprising two first ferrite cores each curved in first planes and each having the faces at the ends thereof lying essentially in a second common plane that is essentially normal to said first planes, said first cores being mounted with first ones of the faces thereof in general alignment along a longitudinal axis in said second plane and adapted in use to overlie the seam between the associated ferromagnetic members with the second ones of the faces thereof equidistantly spaced from said longitudinal axis and from the adjacent surfaces of the associated ferromagnetic members, two second ferrite cores each curved in third planes and each having a first one of the faces at the ends thereof lying essentially in said second common plane and spaced laterally of said longitudinal axis essentially equidistantly with the second one of the faces thereof equidistantly spaced from said longitudinal axis, two first coils respectively wound around said first cores and two second coils respectively wound around said second cores with each of said first coils being connected in series aiding relationship with the one of said second coils disposed on the other side of said longitudinal axis, a signal generator connected to said coils and creating a magnetic flux through said cores and the respective faces thereof and between the respective faces of said first cores and through the seam and the associated ferromagnetic member and between the respective faces of said second cores and through the associated ferromagnetic member, means for comparing the combined permeabilities in the flux paths of each first core and the associated second core with the other first core and its associated second core and generating an error signal indicating a lateral position error of the first cores with respect to the seam between the ferromagnetic members and a phase difference with respect to a reference signal indicating the direction of the lateral position error, said second cores and said second coils compensating for any error signal generated by the tilting of said second common plane with respect to the adjacent surfaces of the associated ferromagnetic members about said longitudinal axis, and means responsive to the error signal and the phase difference for returning said first ones of the faces of the first cores and the work element to positions overlying the seam and until the position error signal and the phase difference are corrected.

Apparatus for tracking a seam between two non-ferromagnetic members and controlling a work element to move along a path overlying the seam, the apparatus comprising two ferrite cores each curved in first planes and each having the faces at the ends thereof lying essentially in a second common plane that is essentially normal to said first planes, said cores being mounted with first ones of the faces thereof equidistantly spaced from a longitudinal axis in said second plane that is adapted in use to overlie the seam between the associated non-ferromagnetic members with the second ones of the faces of said cores equidistantly spaced from said longitudinal axis and from the adjacent surfaces of the associated non-ferromagnetic members, two coils respectively wound around said cores and connected to each other in series relationship, a signal generator connected to said coils and creating a magnetic flux through said cores and the respective faces thereof and through the associated non-ferromagnetic member, means for comparing the resultant flux in the two cores and generating an error signal indicating a lateral position error of the cores with respect to the seam between the non-ferromagnetic members and a phase difference with respect to a reference signal indicating the direction of the lateral position error, and means responsive to the error signal and the phase difference for returning the cores to positions such that the longitudinal axis therebetween and the work element overlie the seam and until the position error signal and the phase difference are corrected.

Apparatus for tracking a seam between two non-ferromagnetic members and controlling a work element to move along a path overlying the seam, the apparatus comprising two first ferrite cores each curved in first planes and each having the faces at the ends thereof lying essentially in a second common plane that is essentially normal to said first plane, said first cores being mounted with first ones of the faces thereof equidistantly spaced from a longitudinal axis in said second plane that is adapted in use to overlie the seam between the associated non-ferromagnetic members with the second ones of the faces of said cores equidistantly spaced from said longitudinal axis and from the adjacent surfaces of the associated non-ferromagnetic members, two second ferrite cores each curved in third planes and each having a first one of the faces at the ends thereof lying essentially in said second common plane and spaced laterally of said longitudinal axis essentially equidistantly with the second one of the faces thereof equidistantly spaced from said longitudinal axis, two first coils respectively wound around said first cores and two second coils respectively wound around said second cores with each of said first coils being connected in series aiding relationship with the one of said second coils disposed on the other side of said longitudinal axis, a signal generator connected to said coils and creating a magnetic flux through said cores and the respective faces thereof and between the respective faces of said first cores and through the seam and the associated non-ferromagnetic member and between the respective faces of said second cores and through the associated non-ferromagnetic member, means for comparing the resultant flux of each first core and the associated second core with the other first core and its associated second core and generating an error signal indicating a lateral position error of the first cores with respect to the seam between the non-ferromagnetic members and a phase difference with respect to a reference signal indicating the direction of the lateral position error, said second cores and said second coils compensating for any error signal generated by the tilting of said second common plane with respect to the adjacent surfaces of the associated non-ferromagnetic members about said longitudinal axis, and means responsive to the error signal and the phase difference for returning the cores to positions such that the longitudinal axis therebetween and the work element overlie the seam and until the position error signal and the phase difference are corrected.

A sensor for use in apparatus for tracking a seam between two work members and controlling a work element to move along a path overlying the seam, the sensor comprising an annular housing open at the bottom and having a free edge therearound disposed in a first plane and adapted to ride upon the adjacent surfaces of the work members defining the seam, an insulating mounting board mounted in said housing and having a first surface disposed toward said first plane and spaced inwardly therefrom and having a second surface disposed away from said first plane and defining a second plane essentially parallel to said first plane, two first ferrite cores mounted on said mounting board and each curved in third planes and each having the faces at the ends thereof lying essentially in said second plane with said third planes essentially normal to said second plane, said first cores being mounted with first ones of the faces thereof essentially equidistantly spaced from a longitudinal axis in said second plane and with the second ones of the faces thereof essentially equidistantly spaced from said longitudinal axis, two second ferrite cores each curved in fourth planes and each having a first one of the faces at the ends thereof lying essentially in said second plane and spaced laterally of said longitudinal axis essentially equidistantly with the second ones of the faces thereof essentially equidistantly spaced from said longitudinal axis, and two first coils respectively wound around the first cores and two second coils respectively wound around said second cores with each of said first coils being connected in series aiding relationship with one of said second coils with the conductors therefor extending outwardly through said housing.