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US 3,941,184 AGranted
Apparatus for manufacturing seamless metal tubular products
AssigneeNone recorded
InventorJohn W. Kelso
Life of this patent
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AssigneeNone recorded
InventorJohn W. Kelso
Estimating the term…
Seamless tubular products made of metal, particularly steel, by the apparatus and method are manufactured by casting molten metal into a round, downwardly converging mold cavity having a coaxial removable cooled core of substantially uniform diameter throughout and which is less than the cavity's minimum diameter, the metal solidifying initially where it contacts the cavity wall and the core with solidification proceeding upwardly with incidental possible formation of pipe in the upper portion of the casting. Prior to the resulting casting cooling below a forging temperature, the core is removed and replaced by a mandrel having a flaring portion and which is pressed into the casting under pressure forging the casting radially outwardly and upwardly against the mold cavity wall with consequent closing and welding of any pipe. This forging may be done while the metal within the initially solidified skin portions remains molten so that undesired segregations are also forced upwardly to the top of the resulting billet. After removal of the mandrel, this forged billet, now having a relatively thick flaring wall, is placed in a rotary tube rolling mill having a mandrel providing a converging portion fitting the flared interior of the billet, the mill then rolling the billet into a seamless tubular product. Conventional rotary tube rolling mills have conical rolling rolls, and the casting mold cavity and forging mandrel may be made with conical shapes so that the billet produced fits the mill rolls, permitting the use of a conventional tube rolling mill altered substantially only by appropriate design of the mill's mandrel and its guide shoes.
An apparatus for making a billet for a seamless tube rotary rolling mill, comprising a plurality of open-topped molds, upstanding cores removably mounted in said molds, a metal casting station, a core removing station, a forging station including a mandrel shaped to enter core holes formed by removal of said cores in castings in said molds, a mold stripping station, and means for successively moving each of said molds passed said stations, said molds having casting cavity side walls each in the form of an inverted frustrum of a cone and stools forming their cavity bottoms and in which holes are formed and in which said cores are fitted to mount the cores, said mold moving means supporting said stools and providing clearance therebelow for downward movement of said cores, and a hammer mounted above said molds at said core removing station for hammering said cores downwardly through castings formed in said mold cavities, said cores being tubular, and including nozzles inserted in the tops of said cores of said molds, means for moving each of said nozzles with each of said molds, means for automatically inserting said nozzles in said cores of said molds leaving said casting station one after another, means for automatically removing said nozzles from said cores as said molds approach said core removing station and means for supplying said nozzles with water while inserted in said cores.
The apparatus of claim 3 having means for locking said cores against downward movement through said holes while said molds approach said casting station and for unlocking said cores after they are held by said castings and prior to actuation of said hammer at said core removing station.
The apparatus of claim 3 in which said mold moving means includes buggies having wheels and on which said molds and stools are carried, and having a ram at said core removing station and an actuator for moving said ram supportingly against the bottom of each buggy during actuation of said hammer to relieve said wheels from the hammer stress.
Apparatus for forming a hollow conical billet suitable for forming into a seamless tubular hollow, comprising a cylindrical metal mold, the inside profile of said metal mold being in the form of an inverted right truncated cone of approximately 60.degree. included angle, said metal mold being placed with axis perpendicular on a flat circular metal stool with the smaller circular opening of said metal mold in contact with the upper plane surface of said stool, said stool having a cylindrical hole extending through its body, the axis of said hole coinciding with the axis of said metal mold, the diameter of said hole in said stool being not greater than six inches less than the inside diameter of said smaller opening of said inside profile of said metal mold in contact with said metal stool, said hole having inserted in it a slidably fitting hollow metal core, said metal core being cylindrical in form in the portion in contact with and extending through said hole in said stool, but slightly conical in profile in the portion extending upward from said stool to a height not less than twelve inches above the top surface of said metal mold, the taper on diameter of said conical section being not less than three quarters of an inch per linear foot on diameter taken parallel to the axis of said metal core, said metal core having an inside cylindrical hollow extending through its length, said cylindrical hollow terminating on the upper circular plane end of said metal core in a bevel, the assembly of metal stool, metal mold and hollow metal core being placed on the plane top surface of a horizontal top member of a buggy, said metal horizontal top member of said buggy being provided with a cylindrical hole extending through said horizontal top member of said buggy, the diameter of said hole being such that it provides a sliding fit with said cylindrical portion of said hollow metal core, said cylindrical portion of said metal core is flush with the bottom plane surface of said horizontal top member of said buggy, said cylindrical portion of said metal core having a shoulder machined around its outer circumference at a point located at a distance upward from the bottom of said cylindrical portion of said metal core approximately equal to one half the thickness of said horizontal top member of said buggy, said horizontal top member of said buggy being provided with a horizontal hole machined radially edgewise in said top member of said buggy approximately one half way between said top and bottom plane surfaces of said horizontal member in exact register with said shoulder on said cylindrical section of said hollow metal core, said hole containing a slidably fitting rod that can be mechanically thrust into said groove of rectangular cross section machined into said cylindrical section of said hollow metal core, said hollow metal core being in position in said assembly of metal mold, metal stool and buggy, said metal rod also capable of being mechanically withdrawn from contact with said shoulder, the effect of said withdrawal of said rod being to release said hollow metal core from said metal mold.
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
The axes of the rollers being arranged essentially diagonally to the axis of the work, e.g. "cross" tube-rolling ; Diescher mills, Stiefel disc…:…
With separating, localizing, or eliminating of as-cast defects from a metal casting [e.g., anti-pipe]: compressing ingot while still partially molten
Plural diverse manufacturing apparatus including means for metal shaping or assembling: casting and working
Rolling of metal
Term ended 2 Mar 1993 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
The manufacture of seamless steel tubes when involving the use of a rotary rolling mill, is well known.
From the casting of molten steel to the production of the ultimate product, all details involved are described by "The Making, Shaping and Treating of Steel", 7th Edition, published and copyrighted 1957 by the U.S. Steel Corporation, particularly by Chapters 20, 25 and 41 of this text. In its entirety, this text is hereby incorporated as a part of the present specification.
Conventionally a huge investment in equipment and labor is required to provide a rotary rolling mill with a hollow or tubular billet for the mill to roll into a tube of specified wall thickness and length. An ingot must be cast and its top extensively cropped to remove pipe and segregations; the ingot must be reheated and rolled into a billet which must be reheated and pierced by a piercing mill. These have been minimum requirements to obtain a billet suitable for rotary rolling. The billet produced has a thick wall which in the rotary rolling mill is thinned and normally expanded to a larger diameter.
FIG. 1 is a sectional view of the cast billet if cooling were allowed to proceed to complete solidification.
FIG. 2 is a sectional view of the cast billet after partial cooling and pressing.
FIG. 3 is a cross section of mold and cast billet showing progressive structural changes on cooling and the profile after pressing in the mold.
My invention has the following advantages over conventional practice:
1. It makes it possible to obtain a sound, pipe-free billet by top pouring and pressing without the yield loss necessitated by cropping off the portion of the billet containing pipe and blow holes normally associated with top pouring.
2. It eliminates the conventional blooming and bar mills normally required between ingot and billet.