Method and apparatus for elongating metal tubes by means of a mandrel mill
AssigneeSumitomo Metal Industries, Ltd.
InventorChihiro Hayashi
Life of this patent
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Abstract
In a method of elongating a metal tube by means of a mandrel mill, a tapered mandrel bar is inserted into a hollow piece and the feeding speed of the mandrel bar is controlled so as to change the length by which the mandrel bar projects beyond the delivery end of the final stand of the mandrel mill at the point of time when the leading end of the hollow shell is gripped by the rolls in the final stand. As a result, the wall thickness of the hollow shell is altered to permit the rolling of hollow shells of many sizes with different wall thicknesses using a single mandrel bar.
Claims18
A method of elongating a metal tube by way of a mandrel mill having a series of rolling stands provided with rolls, including a final rolling stand having a delivery end, to produce a hollow shell, comprising inserting a tapered mandrel bar into a hollow piece, rolling the hollow piece through the rolling stands, and controlling a feeding speed of the mandrel bar to control a length by which the mandrel bar projects beyond the delivery end of the final rolling stand at a point in time when a leading end of the hollow piece is gripped by the rolls in the final rolling stand so that a wall thickness of the hollow piece is altered to permit the production of hollow shells of a plurality of sizes with different wall thicknesses using a single mandrel bar.
A method of elongating a metal tube by way of a mandrel mill having a series of rolling stands provided with rolls, including a final rolling stand having a delivery end, to produce a hollow shell, comprising inserting a tapered mandrel bar into a hollow piece, rolling the hollow piece through the rolling stands, controlling a feeding speed of the mandrel bar to control a length by which the mandrel bar projects beyond the delivery end of the final rolling stand at a point in time when a leading end of the hollow piece is gripped by the rolls in the final rolling stand, and ceasing the feed of the mandrel bar at a point in time when the leading end of the hollow piece is gripped by the rolls in the final rolling stand so that a wall thickness of the hollow piece is altered to permit the production of hollow shells of a plurality of sizes with different wall thicknesses using a single mandrel bar.
A method of elongating a metal tube by way of a mandrel mill having a series of rolling stands provided with rolls, including a final rolling stand which has a delivery end, to produce a hollow shell, comprising inserting a tapered mandrel bar into a hollow piece, rolling the hollow piece through the rolling stands, controlling a feeding speed of the mandrel bar to control a length by which the mandrel bar projects beyond the delivery end of the final rolling stand at a point in time when a leading end of the hollow piece is gripped by the rolls in the final rolling stand, and controlling an opening between the rolls in each stand to compensate for an amount of taper of the tapered mandrel bar in accordance with the length by which the mandrel bar projects beyond the delivery end of the final rolling stand at the point in time when the leading end of the hollow piece is gripped by the rolls in the final rolling stand so that a wall thickness of the hollow piece is altered to permit the production of hollow shells of a plurality of sizes with different wall thicknesses using a single mandrel bar.
A system for elongating a metal tube comprising a mandrel mill that includes a series of rolling stands each provided with rolls for rolling a hollow piece to produce a hollow shell, a tapered mandrel bar positionable in an interior of the hollow shell, and a controller for controlling a feeding speed of the tapered mandrel bar to thereby permit production of hollow shells of a plurality of sizes with different wall thicknesses using a single mandrel bar.
Dependencies are inferred from the claim text.