Asymmetric extrusion die and method for forming billet thereof

Abstract

The invention discloses an asymmetric extrusion die and a blank formation method thereof. The asymmetric extrusion die comprises a male die and a female die; the male die comprises a top plate, a joint plate and an extrusion rod; the female die is of a circular truncated cone-shaped structure externally and is hollow internally, a die cavity is formed inside the female die and is sequentially divided into an extrusion-into section, a first asymmetric extrusion section, a uniform extrusion section, a second asymmetric extrusion section and an extrusion-out section from an extrusion inlet. According to the asymmetric extrusion die and the blank formation method thereof, one sides of blanks are extruded but the other sides of the blanks are not extruded through asymmetric extrusion channels, and therefore uneven shear deformation is generated, and shear deformation facilitates formation of equiaxial small grains of material under the effect of three-dimensional pressure stress; through the asymmetric extrusion effect of two opposite directions, the shapes of the extruded blanks are normal, the material is saved, and the energy consumption is lowered.

Description

Technical field [0001] The invention belongs to the technical field of material extrusion, and specifically relates to an asymmetric extrusion die and a method for forming a blank. Background technique [0002] Equal Channel Angular Extrusion (ECAP) is a new type of extrusion molding method based on severe plastic deformation. When the material passes through the corner of the ECAP die channel, it is subjected to strong shear deformation to refine the material grain and improve the overall performance of the material. purpose. The shape of the ECAP deformed billet when the channel is extruded is not a neat end face, but an uneven end face with an oblique slope. It can be seen that the nature of shear deformation is an uneven deformation, and the shear band structure is also a major feature of ECAP degeneration. Although the research on the preparation of ultra-fine-grained materials by ECAP has gained consensus, there are still some shortcomings, such as complex mold cavities, h...

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Problems solved by technology

Although the research on the preparation of ultra-fine-grained materials by ECAP has been recognized by everyone, there are still some shortcomings, such as complex mold cavity, high processing and manufacturing costs, large mold wear, and high extrusion tonnage requirements.

[0003] The L-shaped, U-shaped, C-shaped, S-shaped corner reciprocating extrusion dies and repeated upsetting proposed in the invention patent applications with Chinese patent publication numbers CN101259493, CN1709605, CN2757953, CN2757954 and CN2768921 respectively Extrusion dies are all extensions of the ECAP method, and there is no substantial industrial innovation

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