Method for manufacturing steel pipe
A manufacturing method and technology of steel pipes, applied in the field of steel pipe manufacturing, can solve problems such as rising manufacturing costs and deterioration of toughness
Active Publication Date: 2015-01-07
JFE STEEL CORP
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Problems solved by technology
[0007] However, the technology of Patent Document 1 needs to heat the steel pipe, so corresponding heating equipment is required, resulting in an increase in production cost.
In addition, there is also a problem that the excellent properties such as strength, toughness, and weldability formed in the material steel plate by using accelerated cooling (accelerated cooling) and other technologies are deteriorated due to the heating of the steel pipe.
Method used
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Embodiment
[0041] Prepare 7 sheets of material steel plates with a plate width W of 3713mm (plate thickness of 25.4mm, tensile strength of 745MPa~757MPa), and use a metal mold with a radius of curvature of 380mm to the two width ends of the steel plate (width L: 215mm) Range) bend the end portion so that the bending angle after unloading (bent angle; refer to Fig. 1(b)) is 16.9°, and then use an upper metal mold with a radius of curvature of 380mm to apply the end bend to the steel plate After three-point bending is performed to form a cylindrical shape, the butt portion is welded to form a tube blank, and then a pipe expanding device is inserted into the inside of the tube blank, and the tube expanding device has the radius of curvature of the surface abutting the inner surface of the tube blank A plurality of expansion tools of 580 mm are used to produce a steel pipe with an expansion rate (=100×(diameter after expansion-diameter before expansion) / diameter before expansion) of 1%. In ad...
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Abstract
In this method for manufacturing a steel pipe, a steel sheet, the edges of which have been bent, is subjected to three-point bending a plurality of times in a widthwise direction so as to form said steel sheet into a cylinder, and after abutting parts are welded together so as to produce a pipe blank (1), a pipe expander provided with a plurality of pieces of expansion hardware (2) is inserted into the pipe blank and the pipe blank is expanded. By expanding the pipe blank with the expansion hardware (2) placed up against each section (9) of the pipe blank that was not deformed by the three-point bending, steel pipes with excellent dimensional precision can be manufactured with high yield. Letting N represent the number of pieces of expansion hardware, the three-point bending is preferably performed aN-1 times (a being an integer, e.g. 1, 2, etc.).
Description
Technical field [0001] The present invention relates to a method for manufacturing large-diameter and thick-walled steel pipes such as line pipes. Background technique [0002] In large-diameter and thick-walled steel pipes used for line pipes, etc., so-called UOE steel pipes are widely used, namely, a U-shaped steel plate that is a material having a predetermined width, length, and plate thickness by press bending (press bending), After further press forming into an O shape, the butt joint is welded to form a steel pipe, and then pipe expanding is performed to increase the diameter of the steel pipe to improve roundness. However, in the above-mentioned UOE steel pipe manufacturing method, in the process of press forming the steel plate into a U-shape or O-shape, a large press force is required, so a large-scale Press machine. [0003] Therefore, a method of manufacturing large-diameter and thick-walled steel pipes has been developed to reduce the pressing force. For example, th...
Claims
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IPC IPC(8): B21D5/01B21D39/20
CPCB21D5/015B21D39/20B21C37/0815
Inventor 堀江正之安原勇
Owner JFE STEEL CORP