Method for producing seamless steel pipe with reversible reciprocating periodic time hot rolling technique

Abstract

The invention discloses a method for manufacturing seamless steel pipes by adopting a reversible repeated periodic hot rolling technology. A plurality of frames are arranged along the movement direction of a rolling stock, rollers are arranged on each frame in vertical direction, each cross section of a pass of the rolling mill has identical shape and consists of three arc segments. The method comprises the following processing steps of: penetrating the rolling stock through a mandrel and feeding to a roller, biting the rolling stock by the roller to achieve rolling in forward travel, reversing the roller when the forward-travel rolling finished, accurately reversing the rolling stock by a certain angle, feeding into the pass of the roller to achieve reversible rolling deformation, and repeating the steps by multiple times until achieving the prescribed size. The method can achieve reversible repeated rolling and greatly improve the rolling efficiency, and is particularly suitable for producing extra-thick wall pipes and low-plasticity alloy steel pipes without intermediate reheating, thus saving the energy resource. The generation of pilger bell ends is obviated in the production, thus improving the rolling yield and achieving better economic benefit.

Description

1. Technical field: [0001] The invention relates to a method for manufacturing seamless steel pipes, in particular to a method for manufacturing seamless steel pipes using a reversible reciprocating cycle hot rolling process. 2. Background technology: [0002] Existing periodic hot-rolling mill for seamless steel tubes is a two-roller irreversible rolling mill, and the periodic rolls are engraved with a garden pass with variable cross-section, and there are mainly two main areas on its cross-section---empty rolling area and working area. The empty rolling area is equivalent to the "opening" of the roll. When it is opened, the capillary is turned over 90° and sent into the roll; the working area of ​​the pass is divided into three areas, see Figure 1: they are equivalent to the central angle θ 1 , θ 2 , and θ 3 , where θ 1 Known as the hammer head or front cone area, the radius of the hole pattern is gradually reduced, and it is used to compress the capillary to complete t...

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Problems solved by technology

[0005] a. It is only suitable for the rolling of medium-thick-walled pipes. It is very difficult for the rolling of extra-thick-walled pipes, and it is also very difficult for high-alloy rolling with high deformation resistance.

[0006] b. Since the round hole has a side wall bevel of 25° to 30°, the deformation of the metal is uneven on the circumference of the hole. When the feeding amount is large, it is easy to produce transverse tension on the low plasticity alloy steel. crack

[0007] c. Since the rolling is cyclically fed and rolled, the amount of feeding each time is limited, generally no more than 30mm, so the production efficiency is low

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