Reverse molding necked-in transferring drill rocker end upsetting method

Abstract

The invention relates to a method for thickening the tube end of a drill stem through reverse molding and diameter reducing and transferring. The method adopts a multi-pass inner and outer thickening process. When one certain thickening pass begins to adopt inner and outer thickening, the length of an outer thickening transition section is 130 mm; the inner thickening occurs in initial quantity; a change point of an inner thickening transition section is consistent with an outer thickening change point of a first pass; after two thickening passes, firstly, the thickening part of the tube end is subjected to flattening; secondly, a diameter reducing mould is used for carrying out diameter reducing on the flattened tube end; after the diameter reducing, a control ring of an inner thickening conical surface is formed in the smallest diameter part of the inner thickening transition conical surface; and when the subsequent thickening pass is used for thickening for upset forging, the control ring of the inner thickening conical surface and the outer wall of a punch are fully contacted to ensure the molded inner transition conical surface is not influenced by upset forging and produces deformation. The method changes the inner thickening conical surface regular, stable, flat and smooth under the strict control condition, evenly distributes the stress of the thickening transition part of the tube end of the drill stem, makes a stress change gradient more smooth, and substantially reduces piercing probability caused by stress concentration in the use of the drill stem.

Description

technical field [0001] The invention relates to a pipe end thickening technology for drilling pipes, oil pipes and casings used in petroleum and natural gas drilling, in particular to a method for thickening pipe ends of drill pipes by reverse forming and reducing diameter transfer. Background technique [0002] Drill pipe is the main component of oil and gas drilling tools. Drill pipe is composed of pipe body and threaded joints. The connection method between the threaded joint and the pipe body is friction welding. In order to improve the bearing capacity at the welding diameter, it is generally necessary to thicken the two ends of the pipe body before welding, which can improve the stress distribution of the welded part of the drill pipe during work, achieve a smooth transition, and improve the working and operation of the drill pipe. Use performance. At present, my country's drill pipe production is mainly based on the American API SPEC 5D standard, which requires inte...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a method for thickening the pipe end of the drill pipe with reverse forming reducing diameter transfer. The shrinkage fluctuation causes the technical problem of the mechanism of stacking and pits in the inner thickening transition section. It can make the inner thickening cone surface become regular, stable, smooth and smooth under strict control conditions, and the disappearance of the inner thickening cone surface is round. The radius of curvature of the arc (R) increases, the minimum length of the inner thickening transition section (Miu) increases to 130mm, the stress distribution of the thickened transition part of the drill pipe end is more uniform, the stress gradient is more gentle, and the stress of the drill pipe during use The probability of concentration causing piercing is greatly reduced

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