Magnetic particle flaw detector including shield means to protect previously tested surfaces

Claim 2

Apparatus for stray field magnetic testing of elongated ferromagnetic parts for defects, comprising: a conveyor for moving the parts longitudinally without rotation thereof along a definite path; a first test station located along said path including, a first pair of elongated magnetizing means, each having an elongated magnetizing surface arranged with the long dimension thereof generally parallel to the path of movement and having a width substantially less than the corresponding dimension of the parts being tested for directing magnetic flux onto transversely spaced lower portions of the parts as they move therepast, means for dispensing a magnetic powder material onto the upper surface portions of the parts in the regions thereof being fluxed; a second test station located along the path of movement and spaced from said first station including, a second pair of such elongated magnetizing means for directing magnetic flux onto the upper portions of the parts as they move therepast, means for spraying a magnetic powder material generally horizontally onto the lower portions of the parts, and shield means located in said second test station to prevent the sprayed magnEtic powder material from coming into contact with upper portions of the parts to which magnetic powder material had been applied in the first station.

Claim 3

Apparatus as in claim 1, in which said shield means comprise first and second non-magnetic shielding plates mounted with a respective edge of each in slightly spaced relation to opposite sides of said parts.

Claim 4

Apparatus as in claim 1, in which said magnetic powder material comprises a magnetic powder emulsion, and further means are provided for heating the parts prior to entry into said stations.

Claim 5

Apparatus as in claim 1, in which said magnetic powder material is heated before being applied to the parts.

Claim 6

Apparatus as in claim 1, in which the magnetic powder material includes an adhesive for increasing cohesion of magnetic powder particles to one another and adhesion of the magnetic powder material to the parts.

Claim 7

Apparatus as in claim 1, in which the first and second pairs of elongated magnetizing means each include a yokelike construction, the legs of which form the elongated magnetizing means.

Claim 8

Apparatus for defect testing of elongated ferromagnetic workpieces having four or more longitudinally extending side surfaces separated by corresponding edges, comprising: means for conveying the workpiece along a straight path substantially parallel to the side edges while maintaining one of said side edges vertically upright; a first pair of magnetizing means each having an elongated flat magnetizing surface of width substantially less than that of the workpiece, said magnetizing surfaces being disposed in closely spaced relation to a respective pair of immediately adjacent workpiece lower side surfaces; spray means located above said first magnetizing means and downwardly directed onto the workpiece vertically upright edge for spraying a magnetic powder emulsion thereon; a second pair of magnetizing means spaced along the line of movement from said first means and having a respective pair of magnetizing surfaces disposed slightly spaced from the adjacent side surfaces at each side of the vertically upright workpiece edge; further spray means for dispensing pressurized magnetic powder emulsion horizontally onto the workpiece lower portions as the workpiece is being magnetically fluxed by said second magnetizing means; and shield means for preventing magnetic powder emulsion from said further spray means from being deposited onto the workpiece upper portions.

Claim 9

Apparatus for defect testing of elongated ferromagnetic workpieces having four or more longitudinally extending side surfaces separated by corresponding edges, comprising: means for conveying the workpiece along a straight path substantially parallel to the side edges while maintaining one of said side edges vertically upright; a first pair of magnetizing means each having an elongated flat magnetizing surface of width substantially less than that of the workpiece, said magnetizing surfaces being disposed in closely spaced relation to a respective pair of immediately adjacent workpiece lower side surfaces; spray means located above said first magnetizing means and downwardly directed onto the workpiece vertically upright edge for spraying a magnetic powder emulsion thereon; a second pair of magnetizing means spaced along the line of movement from said first means and having a respective pair of magnetizing surfaces disposed slightly spaced from the adjacent side surfaces at each side of the vertically upright workpiece edge; further spray means for dispensing pressurized magnetic powder emulsion horizontally onto the workpiece lower portions as the workpiece is being magnetically fluxed by said second magnetizing means; and shield means for preventing magnetic powder emulsion from said further spray means from being deposited onto the workpiece upper portions.