Bend forming method of large-angle pipeline with high precision, large pipe diameter and small bending diameter ratio

Abstract

The invention discloses a bend forming method of a large-angle pipeline with high precision, a large pipe diameter and a small bending diameter ratio, and belongs to the technical field of machining. Metal or alloy materials with the low melting temperature are machined to be a core rod, the core rod is assembled into an inner hole of the large pipeline to be bent, the large pipeline and the core rod are simultaneously bent through bend forming, pipe blank which is subjected to bend forming is heated to be at the temperature higher than the melting temperature of the alloy core rod, at a certain temperature below the AC1 temperature of a bent pipe material (or the heating temperature at which the performance of the pipe blank material can not drop obviously), a core rod material in the bent pipe is molten and flows out, and the large bent pipe with the bent section ovality being small, the inner hole surface being smooth and the inner arc being capable of not wrinkling is acquired. The bent pipe low-melting-point core rod technology is suitable for the bend forming of the large-angle pipeline which is high in forming precision requirement, thick in wall, large in pipe diameter and small in bending diameter ratio.

Description

technical field [0001] The invention relates to a bending forming method of a high-precision, large-diameter and small-bending-diameter-ratio large-angle pipe, which belongs to the technical field of mechanical processing. Background technique [0002] High-strength, large-diameter, thick-walled steel elbows are important components of industrial equipment, especially in petrochemical and nuclear power fields. Existing pipe bending processes mainly include: press bending, push bending, winding bending, etc. The tube blanks bent by these bending process schemes inevitably have large ellipticity and thinning of wall thickness. There is a large two-way compressive stress in the area, so wrinkling in the unstable area often occurs, and even local cracking occurs. In order to solve the defects of excessive ellipticity and local instability, in the above-mentioned bending process, ordinary cylindrical mandrels, spoon-shaped mandrels, hinged mandrels, flexible shaft mandrels, etc....

AI Technical Summary

Problems solved by technology

In order to solve the defects of excessive ellipticity and local instability, in the above-mentioned bending process, ordinary cylindrical mandrels, spoon-shaped mandrels, hinged mandrels, flexible shaft mandrels, etc. are generally used, and these methods can be used to varying degrees. Solve the problem of excessive ellipticity, but also bring other disadvantages such as: scratches on the inner surface of the tube blank, difficulty in removing the mandrel, high manufacturing cost, etc.

For steel elbows with small inner hole size, high ovality and inner surface finish, a large number of tests have shown that only mandrels made of homogeneous, continuous, and tensile-resistant materials can meet the aforementioned requirements. The manufacture is difficult and costly

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