Abstract:
The invention relates to a method for producing a tube (2) or tubular pre-product from a solid billet in a rolling mill, comprising at least one roll (5a, 5b) acting from the outside on the solid billet or tubular pre-product and a mandrel (4) carrying a piercing head (3) and engaging from the inside in the tube or tubular pre-product, wherein immediately after the solid billet has been completely pierced by the piercing head a fluidized deoxidation agent and/or an inert gas is supplied to the end of the tube or tubular pre-product facing the roll and is guided through the tube or tubular pre-product into the interior of the tube or tubular pre-product when the mandrel is withdrawn. The invention further relates to a rolling mill for performing the method according to the invention, comprising at least one roll acting from the outside onto the solid billet or tubular pre-product and a mandrel carrying a piercing head and engaging from the inside in the tube or tubular pre-product, wherein a device is provided for feeding and introducing a fluidized deoxidation agent and/or an inert gas to the end of the tube or tubular pre-product facing the at least one roll.
Abstract:
A piercing mandrel for piercing heated round blocks of metal for the production of seamless pipes, having a piercing mandrel nose and a piercing mandrel main body which can be connected to a mandrel bar. The outer diameter of the piercing mandrel nose is formed in a conically tapering manner in the longitudinal direction towards the piercing mandrel main body in order to increase the durability of the piercing mandrel when used for piercing round blocks of metal, in particular higher-alloyed steel materials which are difficult to work, by means of skew rolling providing a qualitative improvement of the inner surface of the pierced round block and reducing tool costs.
Abstract:
A method for producing a plug for use in a piercing rolling mill for producing a seamless steel tube/pipe includes an arc-spraying step of melting iron wires, and spraying molten material thereof onto a surface of a base metal of a plug by use of an arc-spray gun, so as to form a film containing oxide and Fe on the surface of the base metal of the plug. In the arc-spraying step, the surface of the base metal of the plug is divided into plural sections along an axial direction of the plug, and in turn, the arc-spraying is separately carried out in each of the plural sections while an intersection angle between the center line of a spraying stream from the arc-spray gun and the surface of the plug base metal is maintained within a range of 35 degrees to 90 degrees.
Abstract:
A plug includes a front edge portion having a convex curvature; a cylindrical portion having a truly or nearly cylindrical shape; a trunk portion having an outer diameter gradually increasing toward a rear edge thereof; a mandrel joint provided in a rear edge portion of the plug; a lubricant ejection hole running through the trunk portion from the mandrel joint that opens on the surface of the cylindrical portion; and a coating comprising oxides and Fe that is formed on the base metal surface of each of the front edge portion as well as the trunk portion by arc spraying using an iron wire. In this way, the plug can prevent inner surface flaws from occurring in a hollow blank that is deformed by piercing-rolling, and can extend its life without requiring a long time for making it.
Abstract:
The present invention relates to a system and method for rolling a seamless tube. The plant comprises a main rolling mill with adjustable rolls for mandrel-rolling a semi-finished tube. The plant also comprises a fixed-roll extracting/reducing mill positioned downstream of the main rolling mill. The extracting/reducing mill is designed to extract the semi-finished tube from the mandrel and reduce its diameter to a predetermined value close to that desired for the finished tube. Finally, the plant comprises a adjustable-roll sizing mill. The sizing mill is positioned downstream of the extracting/reducing mill. This sizing mill is designed to adjust the radial position of the rolls and define the diameter of the outgoing tube.
Abstract:
A longitudinal, multi-stand rolling mill of the continuous, restrained type for rolling hollow bodies is described, which comprises a main rolling mill (2) and an extracting rolling mill (4) in line and downstream of the main rolling mill, at a distance from the main rolling mill larger than the maximum length of the hollow body and of the spindle, and in which the spindle is extracted at the outlet of the main rolling mill in the gap between said main rolling mill and extracting rolling mill, and is laterally unloaded.
Abstract:
A piercing and rolling plug has a film composed of oxides such as Fe3O4 and FeO and Fe (metal) as being formed on the surface of the base metal by electric arc spraying using an iron wire whose main component is Fe and, owing to this film, a plug excellent in heat-shielding and seizure-preventing effects can be realized and the lifetime of the plug can be prolonged. Further, in regenerating this plug, a film can be re-formed via the steps of shot blasting of the as-used plug in piercing and rolling and electric arc spraying in that order; thus, it is possible to regenerate the plug at low cost and in a short period of time.
Abstract translation:穿孔滚动塞具有由氧化物如Fe 3 O 4和FeO和Fe(金属)构成的膜,其通过使用主要成分为Fe的铁丝通过电弧喷涂形成在母材表面上,并且由于该膜 能够实现优良的隔热防止效果的塞子,延长塞子的使用寿命。 此外,在再生该插头时,可以通过以下步骤重新形成薄膜:依次进行穿孔和滚压以及电弧喷涂中使用的插头的喷丸处理; 因此,可以在低成本和短时间内再生插头。
Abstract:
A rolling mill of rotating expander type for tubular bodies, comprising: working rollers (1, 2) arranged inclined with respect to the rolling axis; a tip (3) fitted on a beam (4), so that the tubular body is pushed in rotation between the rollers and the tip, and subjected to deformation in order to increase the perimeter; a tip-stabilizing system placed behind said tip, about the beam, and integrated in the rolling mill.
Abstract:
A plug has a tip end portion, a taper portion, and a middle portion. The surface of the tip end portion is a spherical surface whose radius of curvature is R1 and length is L1 that is shorter than R1. The outer diameter of the taper portion on the front end side is D1, and the outer diameter on the back end side is D2 that is larger than D1, and the length is L2. The plug satisfies Expression (1), Expression (2) if 0
Abstract:
A method for surface treating a mandrel bar used for hot rolling of high-alloy seamless steel pipe is provided. The method includes heat treating the mandrel bar to develop a scale, and after heat treatment, rolling ordinary steel comprising 8% or less of chromium for at least 50 passes. This achieves a mandrel bar for rolling high-alloy steel possessing both durability and superior resistance to seizure