Method for removing defects from slabs and blooms of steel and other metals

Claim 1

A method of heat treating a slab of metal to remove defects therefrom which comprises the steps of forming at least one electric arc from an annular electrode extending to the slab in a path substantially perpendicular to a surface of the slab, utilizing a magnetic field to cause the arc path to describe substantially annular repetitive rotative movements about a substantially unchanged axis while maintaining the arc path substantially perpendicular ro the surface of the slab, moving the slab in a substantially linear path at a predetermined speed, said linear path being substantially perpendicular to the arc path whereby successive rotations of the arc spot on the slab as the arc rotates are displaced from each other by an amount which is a function of the rate of arc movement and a function of the rate of slab movement, the rates of movement being chosen with respect to each other whereby at least a substantially rectangular portion of the slab surface is substantially uniformly heated by the arc spot directly thereon.

Claim 2

A method of heat treating a slab of metal to remove defects therefrom which comprises the steps of forming at least one electric arc from an annular electrode extending to the slab in a path substantially perpendicular to a surface of the slab, utilizing a magnetic field to cause the arc path to describe substantially annular repetitive rotative movements about a substantially unchanged axis while maintaining the arc path substantially perpendicular ro the surface of the slab, moving the slab in a substantially linear path at a predetermined speed, said linear path being substantially perpendicular to the arc path whereby successive rotations of the arc spot on the slab as the arc rotates are displaced from each other by an amount which is a function of the rate of arc movement and a function of the rate of slab movement, the rates of movement being chosen with respect to each other whereby at least a substantially rectangular portion of the slab surface is substantially uniformly heated by the arc spot directly thereon.

Claim 7

A method for removing defects from a slab of metal having at least one substantially flat surface comprising the steps of moving the slab in a predetermined linear path at a predetermined speed, mounting an annular electrode at a predetermined position along the path of travel of the slab having an annular fluid-cooled arcing surface and with the arcing surface of the electrode spaced from and substantially parallel to the adjacent flat surface of the slab, creating a potential difference between the electrode and the slab whereby an arc is formed between the slab and the arcing surface of the electrode, said arc extending in a direction substantially parallel to the axis of the electrode and substantially perpendicular to said flat surface of the slab, generating a magnetic field within the electrode with at least a strong component extending substantially radially in a transverse direction across the arcing surface and exerting a force on the arc which causes the arc between electrode and slab surface to move in substantially repetitive annular paths on the arcing surface and to take similar repetitive arc paths on the slab surface as the slab moves, which last-named paths extend a predetermined portion or all of the transverse distance across the slab surface, the arc paths on the slab surface being displaced from each other a distance which is a function of the speed of arc rotation and a function of the speed of slab movement, the rate of movement of the slab and the rate of movement of the arc being selected with respect to each other whereby substantially every point on the slab surface within said transverse distance has an arc spot thereto as the slab moves in said linear path with a resulting increase in heating efficiency and more uniform heating of the slab to a substaNtially constant depth beneath the slab surface.

Claim 8

A method for removing defects from a slab of metal having at least one substantially flat surface comprising the steps of moving the slab in a predetermined linear path at a predetermined speed, mounting an annular electrode at a predetermined position along the path of travel of the slab having an annular fluid-cooled arcing surface and with the arcing surface of the electrode spaced from and substantially parallel to the adjacent flat surface of the slab, creating a potential difference between the electrode and the slab whereby an arc is formed between the slab and the arcing surface of the electrode, said arc extending in a direction substantially parallel to the axis of the electrode and substantially perpendicular to said flat surface of the slab, generating a magnetic field within the electrode with at least a strong component extending substantially radially in a transverse direction across the arcing surface and exerting a force on the arc which causes the arc between electrode and slab surface to move in substantially repetitive annular paths on the arcing surface and to take similar repetitive arc paths on the slab surface as the slab moves, which last-named paths extend a predetermined portion or all of the transverse distance across the slab surface, the arc paths on the slab surface being displaced from each other a distance which is a function of the speed of arc rotation and a function of the speed of slab movement, the rate of movement of the slab and the rate of movement of the arc being selected with respect to each other whereby substantially every point on the slab surface within said transverse distance has an arc spot thereto as the slab moves in said linear path with a resulting increase in heating efficiency and more uniform heating of the slab to a substaNtially constant depth beneath the slab surface.

Claim 9

A method for removing defects from a slab of metal having at least three substantially flat surfaces comprising the steps of moving the slab in a predetermined linear path at a predetermined speed, mounting at least three annular electrodes at predetermined positions along the path of travel of the slab, each electrode having an annular fluid-cooled arcing surface and with the arcing surface of each electrode spaced from and substantially parallel to an adjacent and different flat surface of the slab, creating potential differences between all of the electrodes and the slab whereby arcs are formed between the slab and the arcing surfaces of all of the electrodes, each arc extending in a direction substantially parallel to the axis of the electrode to which it takes place and substantially perpendicular to the flat slab surface to which it takes place, generating a magnetic field within each electrode with at least a strong component extending substantially radially in a transverse direction across the arcing surface of the electrode and exerting a force on the arc from the electrode which causes the arc to move in substantially repetitive annular paths on the arcing surface of the electrode and to take similar repetitive arc paths on the adjacent slab surface to which the arc takes place as the slab moves, each repetitive arc path on a slab surface extending a predetermined portion or all of the transverse distance across the last-named slab surface, the repetitive arc paths on a slab surface being displaced from each other a distance which is a function of the speed of arc rotation and a function of the speed of slab movement, the rates of movement of the arcs and the rate of movement of the slab being selected with respect to each other whereby substantially every point on each slab surface within the transverse distance covered by the arc path on that surface has an arc spot thereto as the slab moves in said linear path with resulting increases in heating efficiency and more uniform heating of the slab to substantially constant depths beneath all of the slab surfaces.

Claim 10

A method for removing defects from a slab of metal having at least three substantially flat surfaces comprising the steps of moving the slab in a predetermined linear path at a predetermined speed, mounting at least three annular electrodes at predetermined positions along the path of travel of the slab, each electrode having an annular fluid-cooled arcing surface and with the arcing surface of each electrode spaced from and substantially parallel to an adjacent and different flat surface of the slab, creating potential differences between all of the electrodes and the slab whereby arcs are formed between the slab and the arcing surfaces of all of the electrodes, each arc extending in a direction substantially parallel to the axis of the electrode to which it takes place and substantially perpendicular to the flat slab surface to which it takes place, generating a magnetic field within each electrode with at least a strong component extending substantially radially in a transverse direction across the arcing surface of the electrode and exerting a force on the arc from the electrode which causes the arc to move in substantially repetitive annular paths on the arcing surface of the electrode and to take similar repetitive arc paths on the adjacent slab surface to which the arc takes place as the slab moves, each repetitive arc path on a slab surface extending a predetermined portion or all of the transverse distance across the last-named slab surface, the repetitive arc paths on a slab surface being displaced from each other a distance which is a function of the speed of arc rotation and a function of the speed of slab movement, the rates of movement of the arcs and the rate of movement of the slab being selected with respect to each other whereby substantially every point on each slab surface within the transverse distance covered by the arc path on that surface has an arc spot thereto as the slab moves in said linear path with resulting increases in heating efficiency and more uniform heating of the slab to substantially constant depths beneath all of the slab surfaces.

Claim 11

The method of heat treating a substantially rectangular slab of metal to remove defects therefrom which comprises the steps of moving the slab in a first direction along a predetermined path, mounting at least two annular electrodes at predetermined positions along the path of travel of the slab, each electrode having an annular fluid-cooled arcing surface and with the arcing surface of each electrode spaced from and substantially parallel to an adjacent and different flat surface of the slab, the two electrodes being so mounted with respect to each other that their arcing surfaces are substantially parallel respectively to two slab surfaces which make substantially a 90* angle with respect to each other, creating potential differences between both of the two electrodes and the slab whereby arcs are formed between the slab and the arcing surfaces of both of the electrodes, each arc extending in a direction substantially parallel to the axis of the electrode to which it takes place and substantially perpendicular to the flat slab surface to which it takes place, generating a magnetic field within each electrode with at least a strong component extending substantially radially in a transverse direction across the arcing surface of the electrode and exerting a force on the arc form the electrode which causes the arc to move in substantially repetitive annular paths on the arcing surface of the electrode and to take similar repetitive arc paths on the adjacent slab surface to which the arc takes place as the slab moves, each repetitive arc path on a slab surface extending a predetermined portion or all of the transverse distance across the last-named slab surface, the arc paths on a slab surface being displaced from each other a distance which is a function of the speed of arc rotation and a function of the speed of slab movement, the rates of movement of the arcs and the rate of movement of the slab being selected with respect to each other whereby substantially every point on the slab surfaces within the transverse distances of arc movement has an arc spot thereto as the slab moves in said first direction with a resulting increase in heating efficiency and more uniform heating of the slab to a substantially constant depth beneath the slab surface, turning the slab over whereby the two surfaces thereof not previously having arcs thereto are each adjacent the arcing surface of one of the two electrodes, and causing the slab to move in the opposite direction at a predetermined speed while maintaining arcs to said last-named two surfaces which move at predetermined speeds selected in accordance with the last-named speed of slab movement so that arc spots occur on the two last-named slab surfaces at substantially every point thereon within the lateral distances of movement of the arcs.

Claim 12

The method of heat treating a substantially rectangular slab of metal to remove defects therefrom which comprises the steps of moving the slab in a first direction along a predetermined path, mounting at least two annular electrodes at predetermined positions along the path of travel of the slab, each electrode having an annular fluid-cooled arcing surface and with the arcing surface of each electrode spaced from and substantially parallel to an adjacent and different flat surface of the slab, the two electrodes being so mounted with respect to each other that their arcing surfaces are substantially parallel respectively to two slab surfaces which make substantially a 90* angle with respect to each other, creating potential differences between both of the two electrodes and the slab whereby arcs are formed between the slab and the arcing surfaces of both of the electrodes, each arc extending in a direction substantially parallel to the axis of the electrode to which it takes place and substantially perpendicular to the flat slab surface to which it takes place, generating a magnetic field within each electrode with at least a strong component extending substantially radially in a transverse direction across the arcing surface of the electrode and exerting a force on the arc form the electrode which causes the arc to move in substantially repetitive annular paths on the arcing surface of the electrode and to take similar repetitive arc paths on the adjacent slab surface to which the arc takes place as the slab moves, each repetitive arc path on a slab surface extending a predetermined portion or all of the transverse distance across the last-named slab surface, the arc paths on a slab surface being displaced from each other a distance which is a function of the speed of arc rotation and a function of the speed of slab movement, the rates of movement of the arcs and the rate of movement of the slab being selected with respect to each other whereby substantially every point on the slab surfaces within the transverse distances of arc movement has an arc spot thereto as the slab moves in said first direction with a resulting increase in heating efficiency and more uniform heating of the slab to a substantially constant depth beneath the slab surface, turning the slab over whereby the two surfaces thereof not previously having arcs thereto are each adjacent the arcing surface of one of the two electrodes, and causing the slab to move in the opposite direction at a predetermined speed while maintaining arcs to said last-named two surfaces which move at predetermined speeds selected in accordance with the last-named speed of slab movement so that arc spots occur on the two last-named slab surfaces at substantially every point thereon within the lateral distances of movement of the arcs.

Claim 14

A method of heat treating a slab of metal to remove defects therefrom comprising the steps of forming an electric arc from a fluid-cooled annular electrode arcing surface to at least one surface of the slab, generating a magnetic field which causes the arc to move substantially continuously in repetitive generally annular paths over the arcing surface, moving the slab along a predetermined path past the electrode while causing the arc to periodically traverse a recurring generally annular path along a strip of the surface of the slab, the speed of arc movement and the speed of slab movement being selected with respect to each other whereby an arc spot occurs at substantially every point on said surface within the dimensions of said strip with increased heating efficiency and more uniformity in the depth to which the slab is heated to a predetermined temperature, and quickly cooling successive portions of the surface of the slab after said portions have been heated by the electric arc.

Claim 15

A method of heat treating a slab of metal to remove defects therefrom comprising the steps of forming an electric arc from a fluid-cooled annular electrode arcing surface to at least one surface of the slab, generating a magnetic field which causes the arc to move substantially continuously in repetitive generally annular paths over the arcing surface, moving the slab along a predetermined path past the electrode while causing the arc to periodically traverse a recurring generally annular path along a strip of the surface of the slab, the speed of arc movement and the speed of slab movement being selected with respect to each other whereby an arc spot occurs at substantially every point on said surface within the dimensions of said strip with increased heating efficiency and more uniformity in the depth to which the slab is heated to a predetermined temperature, and quickly cooling successive portions of the surface of the slab after said portions have been heated by the electric arc.

Claim 16

A method of heat treating a multisurface slab of metal to remove defects therefrom which comprises the steps of forming an electric arc from a fluid-cooled annular electrode to at least one surface of the slab, generating a magnetic field which causes the arc to move substantially continuously in generally repetitive paths over the arcing surface, moving the slab along a predetermined path past the electrode whereby the moving arc describes paths on the slab surface similar to the paths on the arcing surface of the electrode, the speed of movement of the slab and the speed of movement of the arc being selected with respect to each other whereby substantially every point within the lateral dimension of the arc paths on the slab surface has an arc spot formed thereon with improved heating efficiency and more uniform heating of the slab, providing an inert gas atmosphere at the instant portion of the slab surface being melted as the slab moves in said path, and quickly cooling successive portions of said slab surface after said portions have been heated by the electric arc.

Claim 17

A method of heat treating a multisurface slab of metal to remove defects therefrom which comprises the steps of forming an electric arc from a fluid-cooled annular electrode to at least one surface of the slab, generating a magnetic field which causes the arc to move substantially continuously in generally repetitive paths over the arcing surface, moving the slab along a predetermined path past the electrode whereby the moving arc describes paths on the slab surface similar to the paths on the arcing surface of the electrode, the speed of movement of the slab and the speed of movement of the arc being selected with respect to each other whereby substantially every point within the lateral dimension of the arc paths on the slab surface has an arc spot formed thereon with improved heating efficiency and more uniform heating of the slab, providing an inert gas atmosphere at the instant portion of the slab surface being melted as the slab moves in said path, and quickly cooling successive portions of said slab surface after said portions have been heated by the electric arc.