Method for Determining Dimensions of Hollow Casting Slab for Extrusion Forming of Large-diameter Thick-walled Pipe

Abstract

The invention discloses a method for confirming the size of hollow casting blank for extrusion moulding of a large-caliber thick-walled tube, and belongs to the field of machining design for large-caliber thick-walled seamless steel pipes. The method is characterized by comprising the following steps: (1) confirming the extrusion ratio lambda according to the outer diameter D, the inner diameter d, the wall thickness B and the axial length H of a large caliber thick-walled tube forge piece; (2) obtaining the outer diameter D0 and the inner diameter d0 of the hollow casting blank according to the steel pipe extrusion deformation relationship that d0 is equal to d as well as the extrusion ratio definition shown in the description; (3) respectively obtaining the wall thickness B0 and the height H0 of the hollow casting blank according to the hollow casting blank size geometrical relationship that D0 equals to the sum of d0 and 2B0 as well as the principle that the size of a to-be-extruded blank is equal to that of an extruded large caliber thick-walled tube forge piece. The method has the advantages that the only size of the hollow blank can be quickly and precisely confirmed, so that the design efficiency is improved and the production period is shortened; the extrusion deformation amount in the length direction is reasonably distributed, so that the structure property and the quality of a product section are guaranteed.

Description

Technical field [0001] The invention belongs to the design field of processing and forming of large-diameter thick-walled seamless steel pipes, and particularly relates to a method for determining the size of a hollow casting blank for extrusion-forming of a large-diameter thick-walled pipe. Background technique [0002] At present, the commonly used production method of large-diameter thick-walled seamless steel pipes for key basic components used in supercritical, ultra-supercritical thermal power nuclear power units and petrochemical industries is extrusion forming. Application number: 201310025199.9, the name "Method for producing large-diameter thick-walled seamless steel pipes by casting-extrusion composite forming" is directly extruded by smelting and casting hollow billets, which is different from the previous extrusion forming process based on forging billets (smelting-casting Compared with ingot-removing head-heating-upsetting-punching-heating-extrusion), it has the adv...

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Problems solved by technology

However, the size of the blank used in the above forming method is currently based on the size of the given large-diameter thick-walled steel pipe, the extrusion ratio is selected according to experience, and the required volume is determined strictly based on the principle of constant volume before and after extrusion deformation. The size of the blank, the disadvantage is that the design cycle is long, and it will cause unreasonable extrusion deformation of the steel pipe forging billet or casting billet

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