Multi-probe flux leakage testing apparatus producing bipolar signals from the largest simultaneously occurring signals of each polarity

Claim 2

Multi-probe flux leakage testing apparatus for detecting flaws in an object relatively moving with respect to the probes which comprises a. means for producing a steady state magnetic field in said object in the test region thereof, b. a plurality of spaced leakage-flux probes for producing respective signal outputs having positive and negative excursions corresponding to flaws passing thereby in said test region, c. means for rectifying and combining the positive portions of the signals from said probes and rectifying and combining the negative portions of the signals from said probes to yield positive and negative signals corresponding to the largest signal of each polarity simultaneously occurring in said probes, d. adding means for adding said largest positive and negative signals to yield bipolar signals having corresponding positive and negative excursions, e. and circuit means responsive to said bipolar signals for indicating flaws in a said object.

Claim 3

Apparatus according to claim 1 in which said probes each include a magnetic core having spaced legs and a coil encircling the core for producing said signal outputs.

Claim 4

Apparatus according to claim 1 in which said circuit means includes a pair of channels supplied with said bipolar signals, said channels including respective bandpass filters for selecting different frequency ranges of said bipolar signals.

Claim 5

Apparatus according to claim 1 in which said means for separately rectifying and combining includes a plurality of amplifiers for amplifying the outputs of said probes respectively, respective pairs of oppositely poled rectifiers supplied with the outputs of respective amplifiers, and a pair of connections respectively connecting the outputs of similarly poled rectifiers of said pairs of rectifiers, said pair of connections supplying respective positive and negative excursions of the amplified flaw signals to said adding means.

Claim 6

Apparatus acCording to claim 4 in which said rectifiers are diodes.

Claim 7

Multi-probe flux leakage testing apparatus for detecting flaws in an object relatively moving with respect to the probes which comprises a. means for producing a steady state magnetic field in said object in the test region thereof, b. a plurality of spaced leakage-flux probes for producing respective signal outputs having positive and negative excursions corresponding to flaws passing thereby in said test region, c. said probes each including a magnetic core having spaced legs and a coil encircling the core for producing said signal outputs, d. a plurality of amplifiers connected to said coils respectively, e. respective pairs of oppositely poled diodes supplied with the outputs of respective amplifiers, f. a pair of connections respectively connecting the outputs of similarly poled diodes of said pairs of diodes to yield respective positive and negative signals corresponding to the largest signals of each polarity simultaneously supplied to said diodes, g. adding means supplied from said pair of connections for adding said largest positive and negative signals to yield bipolar signals having corresponding positive and negative excursions, h. and circuit means responsive to said bipolar signals for indicating flaws in a said object.

Claim 8

Multi-probe flux leakage testing apparatus for detecting flaws in an object relatively moving with respect to the probes which comprises a. means for producing a steady state magnetic field in said object in the test region thereof, b. a plurality of spaced leakage-flux probes for producing respective signal outputs having positive and negative excursions corresponding to flaws passing thereby in said test region, c. said probes each including a magnetic core having spaced legs and a coil encircling the core for producing said signal outputs, d. a plurality of amplifiers connected to said coils respectively, e. respective pairs of oppositely poled diodes supplied with the outputs of respective amplifiers, f. a pair of connections respectively connecting the outputs of similarly poled diodes of said pairs of diodes to yield respective positive and negative signals corresponding to the largest signals of each polarity simultaneously supplied to said diodes, g. adding means supplied from said pair of connections for adding said largest positive and negative signals to yield bipolar signals having corresponding positive and negative excursions, h. and circuit means responsive to said bipolar signals for indicating flaws in a said object.

Claim 9

Apparatus according to claim 6 in which said circuit means includes a pair of channels including respective bandpass filters for selecting different frequency ranges of the bipolar signals.

Claim 10

Multi-probe flux leakage testing apparatus for detecting flaws in an object including mounting means carrying a rotating head through which said object is fed, said apparatus comprising a. a magnet mounted on said rotating head for producing a steady state magnetic field transverse of an object passing therethrough, b. a plurality of leakage flux probes mounted on said rotating head for producing respective signal outputs having positive and negative excursions corresponding to flaws passing thereby, c. said probes being spaced to simultaneously scan different portions of an object passing through the head, d. means mounted on said rotating head for rectifying and combining the positive portions of the signals from said probes and rectifying and combining the negative portions of the signals from said probes to yield respective positive and negative signals corresponding to the largest signal of each polarity simultaneously occurring in said probes, e. adding means mounted on said rotating head for adding said largest positive and negative signals to yield bipolar signals having corresponding positive and negative excursions, f. rotary means for supplying the output of said adding means to a connection on said mounting means, g. and circuit means supplied with signals from said connection for indicating flaws in a said object.

Claim 11

Multi-probe flux leakage testing apparatus for detecting flaws in an object including mounting means carrying a rotating head through which said object is fed, said apparatus comprising a. a magnet mounted on said rotating head for producing a steady state magnetic field transverse of an object passing therethrough, b. a plurality of leakage flux probes mounted on said rotating head for producing respective signal outputs having positive and negative excursions corresponding to flaws passing thereby, c. said probes being spaced to simultaneously scan different portions of an object passing through the head, d. means mounted on said rotating head for rectifying and combining the positive portions of the signals from said probes and rectifying and combining the negative portions of the signals from said probes to yield respective positive and negative signals corresponding to the largest signal of each polarity simultaneously occurring in said probes, e. adding means mounted on said rotating head for adding said largest positive and negative signals to yield bipolar signals having corresponding positive and negative excursions, f. rotary means for supplying the output of said adding means to a connection on said mounting means, g. and circuit means supplied with signals from said connection for indicating flaws in a said object.

Claim 12

Apparatus according to claim 8 in which said probes each include a magnetic core having two circumferentially spaced legs and a coil encircling the core for producing said signal outputs, and said means for separately rectifying and combining includes a plurality of amplifiers for amplifying the outputs of said probes respectively, respective pairs of oppositely poled rectifiers supplied with the outputs of respective amplifiers, and a pair of connections respectively connecting the outputs of similarly poled rectifiers of said pairs of rectifiers, said pair of connections supplying respective positive and negative excursions of the amplified flaw signals to said adding means.

Claim 13

Apparatus according to claim 9 in which said circuit means includes a pair of channels including respective bandpass filters for selecting different frequency ranges of the bipolar signals.

Claim 14

Multi-probe flux leakage testing apparatus for detecting flaws in an object including mounting means carrying a rotating head through which said object is fed, said apparatus comprising a. a magnet mounted on said rotating head for producing a steady state magnetic field transverse of an object passing therethrough, b. a plurality of leakage-flux probes mounted on said rotating head and spaced to simultaneously scan different portions of said object as it passes through the head, c. said probes each including a magnetic core having two circumferentially spaced legs and a coil encircling the core for producing signal outputs having positive and negative excursions corresponding to flaws passing thereby, d. a pair of collector rings mounted on said rotating head for supplying positive and negative DC voltages to said rotating head, e. means on said rotating head for producing a virtual ground from said voltages, f. said probe coils having respective one ends thereof connected to said virtual ground, g. a plurality of amplifiers on said rotating head connected to the other ends of said probe coils, respectively, and supplied with said DC voltages to produce output signals corresponding to flaw signals from said probes, h. respective pairs of oppositely poled diodes on said rotating head connected to the outputs of respective amplifiers, i. a pair of connections on said rotating head respectively connecting the outputs of similarly poled diodes to yield respective positive and negative signals corresponding to the largest signals of each polarity simultaneously supplied thereto, j. adding means on said rotating head supplied from said pair of connections for adding said largest positive and negative signals to yield bipolar signals having corresponding positive and negative excursions, k. an output collector ring mounted on said rotating head for supplying the output of said adding means to a connection on said mounting means, l. and circuit means supplied with signals from said connection for indicating flaws in a said object.

Claim 15

Multi-probe flux leakage testing apparatus for detecting flaws in an object including mounting means carrying a rotating head through which said object is fed, said apparatus comprising a. a magnet mounted on said rotating head for producing a steady state magnetic field transverse of an object passing therethrough, b. a plurality of leakage-flux probes mounted on said rotating head and spaced to simultaneously scan different portions of said object as it passes through the head, c. said probes each including a magnetic core having two circumferentially spaced legs and a coil encircling the core for producing signal outputs having positive and negative excursions corresponding to flaws passing thereby, d. a pair of collector rings mounted on said rotating head for supplying positive and negative DC voltages to said rotating head, e. means on said rotating head for producing a virtual ground from said voltages, f. said probe coils having respective one ends thereof connected to said virtual ground, g. a plurality of amplifiers on said rotating head connected to the other ends of said probe coils, respectively, and supplied with said DC voltages to produce output signals corresponding to flaw signals from said probes, h. respective pairs of oppositely poled diodes on said rotating head connected to the outputs of respective amplifiers, i. a pair of connections on said rotating head respectively connecting the outputs of similarly poled diodes to yield respective positive and negative signals corresponding to the largest signals of each polarity simultaneously supplied thereto, j. adding means on said rotating head supplied from said pair of connections for adding said largest positive and negative signals to yield bipolar signals having corresponding positive and negative excursions, k. an output collector ring mounted on said rotating head for supplying the output of said adding means to a connection on said mounting means, l. and circuit means supplied with signals from said connection for indicating flaws in a said object.

Claim 16

Apparatus according to claim 11 in which said circuit means includes a pair of channels including respective bandpass filters for selecting different frequency ranges of the bipolar signals.