Forming method of square pipe with high strength, thick walls, small cross sections and double sharp corners

Abstract

The invention discloses a forming method of a square pipe with high strength, thick walls, small cross sections and double sharp corners. The method comprises the steps of determining the width of a longitudinal cutting steel belt of a steel coil and the wall dimensions of the square pipes 1-4 according to the sectional dimensions of the square pipe to be formed; determining cold roll forming passes and the optimal forming angle of each pass; determining the rolling center line of the steel belt; slicing two side ends of the steel belt into angled end faces; implementing cold bending deformation for each edge of the steel belt according to the set forming passes and the forming angle, and welding the two side ends closed at high frequency; and shaping and straightening the top sharp corner and the bottom arc angle of the square pipe welded through matching squeeze rollers. The forming method disclosed by the invention has the beneficial effects that the horizontal projection of pass deformation can be reduced effectively by adopting multi-pass cold roll forming, so that the resilience of the effective angle is reduced, and the stability of the product forming process is ensured; and at the same time, the walls of both ends of the square pipe are formed at symmetrical angles, so that the welding small edge and the lumbar resilience of the product can be reduced effectively.

Description

technical field [0001] The invention relates to the field of cold-bending forming, in particular to a forming method for a high-strength thick-walled small-section double-pointed square tube. Background technique [0002] The sharp-angle square steel pipe produced by the cold-formation process has gradually replaced the traditional tailor-welded angle steel because of its good cross-sectional properties, high production efficiency, and excellent product quality. The successful development and application of sharp-angled square steel pipes and their series of products produced by cold-formation technology has greatly improved the production efficiency of related equipment manufacturers and reduced their production costs. [0003] The sharp-edged square rectangular steel pipes developed and produced in the early stage are mostly products with conventional section size and wall thickness and a sharp corner. With the continuous development of construction machinery, railway vehi...

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Problems solved by technology

[0004] However, the existing manufacturing methods of various sharp-angled pipes are mainly to manufacture square or rectangular pipe products with one sharp corner. There are many deficiencies in the forming method, and the dimensional accuracy of the product is difficult to guarantee; and, the existing single-corner square When the tube forming process is used to manufacture high-strength thick-walled small-section double-pointed square tubes, a series of problems are prone to occur, such as serious springback of the square tube, difficulty in product forming and welding control, product size, cross-section symmetry, flatness and Quality characteristics such as torsion are difficult to guarantee;

For example, Chinese patent CN1079680A discloses a method for manufacturing sharp-angled square tubes. The method adopts a cold-bending direct forming method with a fixed bending radius and a bending center moving inward to produce a sharp-angled square tube with a sharp-angle radius≤7mm; the method’s The disadvantage is that the deformation moment is unbalanced, the twisting moment is large, the forming adjustment operation is difficult, and the geometric shape and dimensional accuracy of the product are difficult to guarantee

Chinese patent CN1358586A discloses a method for manufacturing sharp-edged rectangular steel pipes. The method uses the sharp-edged corner and its diagonal line as the rolling center line, and obtains the final product through eight-pass deformation; the disadvantage of this method is that both sides of the steel strip are The upward deformation angle is not equal, the shape of the sharp corner is asymmetrical, and the forming stability is poor

Chinese patent CN1524637A discloses a method for manufacturing a rectangular steel pipe with a sharp corner. The method takes the diagonal corner of the sharp corner as the base point, and uses the line connecting the point in each pass as the rolling center line, and adopts a unilateral deformation method. It is realized by nine-pass forming, high-frequency welding, extrusion, shaping, and straightening; but the disadvantage of this method is that the stability of high-frequency welding and weld burr planing is insufficient, and the symmetry of the effect of the arc angle is poor. , the dimensional accuracy of the product is difficult to meet the requirements

Chinese patent CN105107866A discloses a method and device for thermal shaping of high-strength sharp-edged rectangular tubes. The method pre-bends high-strength steel plates into pre-formed rectangular tubes with a fillet radius of 4-10 mm, and then uses induction heating rings to Locally heating the corners, extruding a square rectangular tube with four sharp corners, and then performing heat shaping to prepare a square rectangular tube with inner sharp corners or outer sharp corners; but it needs to be heated locally. Reshape the corners of conventional square tube products to achieve sharp corners. The process is complicated, the manufacturing cost is high, and industrial production control is difficult.

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