A square special-shaped tube calendering die

Abstract

The invention discloses a calendering die for a square special pipe. All relevant parameters of an inlet segment of the calendering die can be quantized. The calendering die comprises a die core which is inlaid and arranged in an inlaying sleeve in a sleeved mode. The die core is provided with a calendering forming hole. The calendering forming hole comprises the inlet segment and a sizing segment. The sizing segment comprises four flat-straight faces and four corner circular arc faces. The distance between each pair of opposite flat-straight faces is L. The curvature radius of all the corner circular arc faces is R1. The length L33 of the sizing segment is 20.6%-24.6% of the thickness L3 of the whole die core. The inlet segment comprises four leading-in arc-shaped curved faces and four inlet corner curved faces. The distance L1 between the vertexes of the outer edge lines of each pair of opposite leading-in arc-shaped curved faces is obtained through the formula showed in the specification, wherein 1.71<=k1<=1.76. The leading lines of the leading-in arc-shaped curved faces are straight lines and coincide with the center line of the calendering forming hole. The generatrixes of the leading-in arc-shaped curved faces are circular arcs. The calendering die is mainly used for drawing a circular steel pipe blank into the square steel pipe.

Description

technical field [0001] The invention relates to a calendering die in the technical field of metal plastic processing, in particular to a calendering die for drawing metal pipes such as round steel pipes into square special-shaped pipes. Background technique [0002] Drawing dies (also known as calendering dies) are important tooling components for cold drawing various metal pipes, and have been widely used in the production process of diameter reduction or / and deformation of metal pipes such as steel pipes. The steel pipe is cold drawn and formed by using a drawing die, which has the characteristics of high material utilization rate, low energy consumption, excellent product performance, high production efficiency and low cost. Drawing dies can be divided into circular drawing dies and special-shaped drawing dies according to the cross-sectional shape of the drawn pipes; according to whether there is a lining mandrel in the drawing process, they can be divided into empty dra...

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Problems solved by technology

[0003] As we all know, if the opening size of the drawing die and the length of the entrance section are set unreasonably, the contact area between the pipe and the die will change accordingly, and the longitudinal and lateral flow of the metal will be unbalanced, resulting in the The quality of the square tube is poor, mainly manifested in its poor straightness (with different degrees of bending), uneven wall thickness, uneven rounded corners, unstable dimensions and uneven surface, and even more defects during the drawing process. Steel pipe breakage and cracking

[0004] At present, there is no uniform design standard for special-shaped tube calendering dies. The opening size and length of the entrance section are set based on experience. For each type of square tube, the design must go through repeated iterations. Only through the process of testing, improving and retesting can an ideal drawing die be obtained, which not only prolongs the processing cycle of the mold, but also increases the production cost

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