Device for detecting cracks in steel slabs leaving continuous casting

Claim 1

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of sensors employing eddy currents, which comprise an induction coil which is supplied with A.C. voltage and means for detecting variations in said voltage which indicate the presence of a crack, wherein said device comprises two crack detection units which are disposed on either side of the passage of the slabs, each unit comprising one vertical sensor which is maintained above the upper face of the slab, in the vicinity of an edge thereof, and a plurality of horizontal sensors which are located at different levels and which are maintained in the vicinity of a lateral face of the slab, two descaling and cooling units which are located on either side of the passage of the slabs, upstream of said detection units, and each descaling and cooling unit is mounted on a mobile frame which is displaced transversely with respect to the slab by a jack, and which bears one or more vertical axis rollers which are maintained applied against the side of the slab, descaling nozzles which project against the lateral face and against a band on the edge of the upper face of the slab jets of water at very high pressure, of the order of 150 bars, and cooling nozzles which spray the lateral face and the edge of the upper face of the slab.

Claim 2

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of sensors employing eddy currents, which comprise an induction coil which is supplied with A.C. voltage and means for detecting variations in said voltage which indicate the presence of a crack, wherein said device comprises two crack detection units which are disposed on either side of the passage of the slabs, each unit comprising one vertical sensor which is maintained above the upper face of the slab, in the vicinity of an edge thereof, and a plurality of horizontal sensors which are located at different levels and which are maintained in the vicinity of a lateral face of the slab, two descaling and cooling units which are located on either side of the passage of the slabs, upstream of said detection units, and each descaling and cooling unit is mounted on a mobile frame which is displaced transversely with respect to the slab by a jack, and which bears one or more vertical axis rollers which are maintained applied against the side of the slab, descaling nozzles which project against the lateral face and against a band on the edge of the upper face of the slab jets of water at very high pressure, of the order of 150 bars, and cooling nozzles which spray the lateral face and the edge of the upper face of the slab.

Claim 5

A device for detecting cracks in steel slabs leaving a continuous casting installation, which slabs have variable sizes and vertical side faces, by means of eddy-current sensors wherein said device comprises two crack detection units disposed on either side of the passage of the slabs and each crack detection unit comprises a mobile frame bearing one vertical sensor which is applied against the upper face of the slab, in the vicinity of an edge thereof, and a plurality of horizontal sensors which are applied against a side face of the slab, said mobile frame being equipped with horizontal-axis and vertical-axis casters, and said device further comprises means for displacing said mobile frame laterally and vertically with respect to the slab, and to maintain both said horizontal-axis casters applied against the upper face of the slab and said vertical-axis casters applied against a side face of the slab.

Claim 6

A device for detecting cracks in steel slabs leaving a continuous casting installation, which slabs have variable sizes and vertical side faces, by means of eddy-current sensors wherein said device comprises two crack detection units disposed on either side of the passage of the slabs and each crack detection unit comprises a mobile frame bearing one vertical sensor which is applied against the upper face of the slab, in the vicinity of an edge thereof, and a plurality of horizontal sensors which are applied against a side face of the slab, said mobile frame being equipped with horizontal-axis and vertical-axis casters, and said device further comprises means for displacing said mobile frame laterally and vertically with respect to the slab, and to maintain both said horizontal-axis casters applied against the upper face of the slab and said vertical-axis casters applied against a side face of the slab.

Claim 7

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors, wherein said device comprises an axially mobile cylindrical casting having a ceramic bottom, a hollow cylindrical body and a cap which is fixed to the front end of said body and which is equipped with rollers whose rotation axes are perpendicular to the longitudinal axis of the slab and which are mounted on supports which slide parallel to the axis of said cylindrical body and said cap comprises locking screws for blocking said supports and adjusting the projection of said rollers with respect to the outer face of said cap, each sensor comprising an induction coil disposed coaxially inside the axially mobile cylindrical casing.

Claim 8

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors, wherein said device comprises an axially mobile cylindrical casting having a ceramic bottom, a hollow cylindrical body and a cap which is fixed to the front end of said body and which is equipped with rollers whose rotation axes are perpendicular to the longitudinal axis of the slab and which are mounted on supports which slide parallel to the axis of said cylindrical body and said cap comprises locking screws for blocking said supports and adjusting the projection of said rollers with respect to the outer face of said cap, each sensor comprising an induction coil disposed coaxially inside the axially mobile cylindrical casing.

Claim 9

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors, wherein said device comprises an axially mobile cylindrical casing guided axially by one or more ball bushes and pushed forwardly by a piston which moves with clearance in an axial bore and which is subjected to a forward thrust which is due to the loss of pressure produced by a leakage of air around said piston and equipped rollers applied against the surface of the slab with a weak, constant thrust, each sensor comprising an induction coil disposed coaxially inside the axially mobile cylindrical casing.

Claim 10

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors, wherein said device comprises an axially mobile cylindrical casing guided axially by one or more ball bushes and pushed forwardly by a piston which moves with clearance in an axial bore and which is subjected to a forward thrust which is due to the loss of pressure produced by a leakage of air around said piston and equipped rollers applied against the surface of the slab with a weak, constant thrust, each sensor comprising an induction coil disposed coaxially inside the axially mobile cylindrical casing.

Claim 14

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors wherein said device comprises two crack detection units disposed on either side of the passage of the slabs and each crack detection unit comprises a mobile frame which is equipped with vertical-axis casters and means for displacing said frame laterally with respect to the slab and to maintain said casters applied against a side of the slab, wherein said mobile frame is supported by two parallel arms forming a parallelogram articulated, respectively, on said mobile frame by vertical-axis articulations and on a fixed frame by other vertical axis articulations and one of said arms is actuated by means of a double-acting jack to displace said mobile frame laterally with respect to the slab and wherein one of said arms comprises a telescopic device which allows a slight variation in length of said arm and a limited rotation of said frame, and it further comprises a displacement sensor which detects a variation in length of said arm exceeding a limiting value and which automatically controls said jack.

Claim 15

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors wherein said device comprises two crack detection units disposed on either side of the passage of the slabs and each crack detection unit comprises a mobile frame which is equipped with vertical-axis casters and means for displacing said frame laterally with respect to the slab and to maintain said casters applied against a side of the slab, wherein said mobile frame is supported by two parallel arms forming a parallelogram articulated, respectively, on said mobile frame by vertical-axis articulations and on a fixed frame by other vertical axis articulations and one of said arms is actuated by means of a double-acting jack to displace said mobile frame laterally with respect to the slab and wherein one of said arms comprises a telescopic device which allows a slight variation in length of said arm and a limited rotation of said frame, and it further comprises a displacement sensor which detects a variation in length of said arm exceeding a limiting value and which automatically controls said jack.

Claim 16

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors wherein said device comprises two crack detection units and two descaling units disposed on either side of the passage of the slabs and the descaling unit and the crack detection unit located on the same side of the slabs are mounted on the same carriage which is displaced along an axis of the slab wherein each crack detection unit comprises a mobile frame which is borne by an arm connected to said carriage by a vertical-axis articulation which articulation comprises an oscillating jack which drives said arm in rotation to dispose it parallel to the side of the slab in work position wherein said mobile frame comprises a lower plate, an upper plate and three columns which connect said plates and said mobile frame is connected to said arm by one of the three columns which comprises a flat portion on which abuts a roller which is disposed at the end of a finger which slides in a radial bore in said arm and which is pushed by an elastic member and which further comprises a threaded stopper making it possible to adjust the pre-stress of the elastic member, which stopper comprises an axial threaded bore in which penetrates a rod fast with said finger and in which a screw, serving as an adjustable stop for said rod, is disposed.

Claim 17

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors wherein said device comprises two crack detection units and two descaling units disposed on either side of the passage of the slabs and the descaling unit and the crack detection unit located on the same side of the slabs are mounted on the same carriage which is displaced along an axis of the slab wherein each crack detection unit comprises a mobile frame which is borne by an arm connected to said carriage by a vertical-axis articulation which articulation comprises an oscillating jack which drives said arm in rotation to dispose it parallel to the side of the slab in work position wherein said mobile frame comprises a lower plate, an upper plate and three columns which connect said plates and said mobile frame is connected to said arm by one of the three columns which comprises a flat portion on which abuts a roller which is disposed at the end of a finger which slides in a radial bore in said arm and which is pushed by an elastic member and which further comprises a threaded stopper making it possible to adjust the pre-stress of the elastic member, which stopper comprises an axial threaded bore in which penetrates a rod fast with said finger and in which a screw, serving as an adjustable stop for said rod, is disposed.

Claim 18

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors wherein said device comprises two crack detection units disposed on either side of the passage of the slabs and each crack detection unit comprises a mobile frame which is equipped with vertical-axis casters and means for displacing said frame laterally with respect to the slab and to maintain said casters applied against a side of the slab wherein said mobile frame comprises guide columns and each detection unit comprises a detection head which slides vertically along said columns and which bears said sensors and is equipped with rollers of transverse horizontal axis which are maintained applied against the upper face of the slab by the weight of the sliding head, and each detection unit further comprises a vertical single-action jack which lifts said sliding head at the end of a cycle wherein said sliding head further comprises a chamber having a vertical front face closed by a plate which bears three rings which are disposed in a triangle and which each defines a bore and said sliding head comprises three horizontal sensors each placed inside a horizontal mobile cylindrical casing which casing comprises a hollow cylindrical body and a cap fixed to the front end of said body and each cap is engaged with clearance in one of said three bores and said chamber is supplied with compressed air at low pressure which escapes through said clearances.

Claim 19

A device for detecting cracks in steel slabs leaving a continuous casting installation by means of eddy-current sensors wherein said device comprises two crack detection units disposed on either side of the passage of the slabs and each crack detection unit comprises a mobile frame which is equipped with vertical-axis casters and means for displacing said frame laterally with respect to the slab and to maintain said casters applied against a side of the slab wherein said mobile frame comprises guide columns and each detection unit comprises a detection head which slides vertically along said columns and which bears said sensors and is equipped with rollers of transverse horizontal axis which are maintained applied against the upper face of the slab by the weight of the sliding head, and each detection unit further comprises a vertical single-action jack which lifts said sliding head at the end of a cycle wherein said sliding head further comprises a chamber having a vertical front face closed by a plate which bears three rings which are disposed in a triangle and which each defines a bore and said sliding head comprises three horizontal sensors each placed inside a horizontal mobile cylindrical casing which casing comprises a hollow cylindrical body and a cap fixed to the front end of said body and each cap is engaged with clearance in one of said three bores and said chamber is supplied with compressed air at low pressure which escapes through said clearances.