Seamless steel pipe formed by cold rolling and manufacturing method thereof

Abstract

The invention relates to a seamless steel pipe formed by cold rolling and a manufacturing method thereof. The seamless steel pipe is processed and manufactured by carrying out diameter reduction rolling on the outer surface of a seamless steel pipe blank with uniform wall thickness and smooth inner and outer surfaces via at least two rollers in the environment at 5-40 DEG C. The outer diameter and the inner diameter of the rolled pipe blank are compressed and reduced to form a seamless steel pipe with helical grooves formed in the outer surface and convex-concave ripples in the inner surface. A cold rolling forming process is characterized in that rollers of rolling equipment are symmetrically arranged along the axis of the pipe blank; the rollers rotate along self axes and compress the outer diameter of the steel pipe; the inner diameter and the outer diameter of the pipe blank are subjected to plastic deformation; a plurality of spaced protrusions are formed in the outer circle of a middle section and a rear section of each roller; when the outer diameter of the pipe blank is reduced and the appropriate-sized helical grooves are formed in the surface of the pipe blank, the inner diameter of the pipe blank is also reduced and the convex-concave ripples are formed; the seamless steel pipe is further process and manufactured into a grouting connection sleeve of an FRP rib or a steel rib applied to buildings; the seamless steel pipe is low in mechanical cutting processing amount, low in cost and high in performance.

Description

technical field [0001] The invention relates to a method for manufacturing metal seamless pipes, in particular to a cold-rolled seamless steel pipe and a method for manufacturing the same. Background technique [0002] In the field of traditional machinery industry, metal seamless pipes are mainly made by hot rolling, cold rolling and cold drawing processes. The outer diameter of the pipe products is uniform and the surface is smooth. The corrugated pipe is made of a thin-walled high-plastic material metal pipe through rolling on the outer diameter; the steel support pipe is made of a metal pipe with high plasticity that is rolled on the outer surface of the pipe by cold rolling or warm rolling. The thread is used as a force transmission or fixing part; the hollow anchor rod is a part of the surface anchoring and connection, and the inner hole transmits the fluid. However, in the existing industrial products, there is still a lack of special thick-walled seamless steel pipe...

AI Technical Summary

Problems solved by technology

In the existing cold rolling process, for high-strength materials with thick walls such as No. 45 steel pipes, it is difficult to form bulges on the inner wall by pressing grooves on the outside, because the metal in the deep layer near the outer surface when the outer surface is extruded It will flow to both sides. Only when the extrusion die is close to the inner wall of the tube, that is, when a deep groove is extruded, the radial pressure of the mold can be transmitted to the inner wall of the tube and form deformation on the inner wall, while the carbon equivalent is relatively small. High-strength steel has low plasticity. When a deep groove is extruded on the outside, the metal at the bottom of the groove is actually the metal on the outer surface of the pipe, and its tensile deformation is the largest. When the deformation exceeds the plastic limit of the material, it will Cracks visible or invisible to the naked eye are produced, and internal stress is also generated at the deformation. The potential risk caused by internal stress and crack defects is an important problem that hinders the production and processing of grouting sleeves by cold rolling. Therefore, the existing seamless pipe Grouting sleeve processing technology mainly uses materials with low yield point and good plasticity to manufacture sleeves, and only partially rolls the outer surface, resulting in local plastic deformation, while the unrolled metal surface remains original. In the state of size, after the thick-walled seamless steel pipe is rolled by this process, the radial cross-sectional area distributed along the axis is significantly different. The radial cross-sectional area at the rolling groove on the outer surface is the smallest, and the bearing capacity is reduced. The original The bearing capacity of the rough material cannot be fully utilized, resulting in material waste close to the ratio of cross-sectional loss

[0004] With the application and development of high-strength steel bars of 500MPa and above, the yield bearing capacity requirements of high-strength steel bars for grouting sleeves have been significantly increased. The use of materials with low yield points and high plasticity will inevitably increase the wall thickness of the sleeves, which will not only make the outer surface of the grouting sleeves The diameter increases, and the wall thickness increases, so that the cold rolling process requires greater deformation to form the bulge on the inner wall of the tube, and the cold and brittle and micro-crack defects will further increase, and the risk of quality hazards will increase. If it cannot be overcome The high-strength material seamless steel pipe is cold-rolled to form the technical problem of the inner wall protrusion, and the steel sleeve grouting connection technology in the prefabricated concrete structure will be difficult to be widely used and sustainable development due to the problem of high cost

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