Magnaflux Corporation

Kenneth W Schroeder

Donald E Lorenzi

Richard C Sabielny

Bruce G Isaacson

Ralph W Gruetzmacher

Magnetizing current supplies are disclosed for supplying current for magnetizing parts in a magnetic particle inspection system, including SCR's connected in circuit with a three-phase voltage step-down transformer to accurately control the duration and magnitude of magnetizing current. In one type of supply, six SCR's are connected between magnetizing apparatus and terminals of three center tapped secondary windings of a three-phase voltage step-down transformer, the SCR's being operable to rectify current and also being connected to a phase control circuit which controls firing times of all SCR's to control the magnitude of the magnetizing current.

Magnetizing current supply for magnetic particle inspection with SCR's

Demagnetizing methods and apparatus are provided in which a pipe, tube, rod, bar or other elongated part to be demagnetized is moved through the coil assembly to which pulses of current are applied to produce magnetic field pulses of alternating polarity and of substantially constant durations and magnitudes with a substantially constant repetition rate, each current pulse being effective to produce by the end thereof a reversal of the magnetic field in all portions of the part positioned within the confines of the coil assembly and immediately adjacent thereto, the part being moved longitudinally through the coil assembly at a velocity sufficiently low as to effect demagnetization of all portions of the part. The duration of each current pulse is at least 50 milliseconds and most preferably on the order of 0.5 seconds and the velocity of movement is preferably less than two feet per second. The coil assembly includes two pairs of coils connected in series-aiding relation with the coils of each pair being spaced axially from each other and being adjacent the coil of the other pair. Bridge rectifier circuits are provided for energization with silicon controlled rectifiers and trigger circuits adjustable for accurate balance.

Demagnetizing methods and apparatus

A magnetic testing device is provided in which a magnetic recording tape or paper is wrapped around the outside of a tubular pressure member of elastomeric material which is disposed between two circular end plates which form pole portions of a yoke having a central core extending between the end plates and having a coil wound thereon with a copper shield being disposed around the outside of the coil. The device is disposed in a pipe or the like and compressed air is supplied to inflate the pressure member and press the magnetic tape paper into intimate contact with the interior surface of the pipe while an AC current is supplied to the coil to apply a magnetic field to the pipe and to record a magnetic field pattern on the magnetic tape or paper.

Magnetic testing device for internal surfaces of pipe using a

The invention relates to a system and method of testing small cylindrical parts wherein a part is journalled for free rotation about a substantially stationary axis with one side of the part being frictionally engaged with a magnetic tape moved longitudinally to rotate the part and to transfer a magnetic flux pattern at the surface of the part to the tape. Important features relate to the provision of engagement means for obtaining non-skid intimate contact between the tape and the part, to the application of a biasing field to the tape at the area of interengagement between the tape and the part and to the manner of supporting the part.

Growing community of inventors

Arlington Heights, IL, United States of America

Kenneth W Schroeder