Repeatedly extruding upsetting die and method for preparing block ultrafine-grained material

Abstract

The invention discloses a repeatedly extruding upsetting die and method for preparing a block ultrafine-grained material, and belongs to the technical field of metal plastic machining. The repeatedlyextruding upsetting die includes an upper extrusion head, a lower extrusion head, a female die body, a female die body prestress ring, a base plate, an upper flattening male die body and a lower flattening male die body. The upper extrusion head and the lower extrusion head are placed in a female die body passage, a trapezoidal groove is formed in the upper end of the lower extrusion head, a sametrapezoidal groove is formed in the lower end of the upper extrusion head, and a workpiece is located between the upper extrusion head and the lower extrusion head. The method for preparing the blockultrafine-grained material by adopting the device comprises the steps that the upper extrusion head moves downwards, the workpiece is pressed into the grooves of the upper extrusion head and the lowerextrusion head, the two extrusion heads are removed, the upper flattening male die body and the lower flattening male die body are replaced, and the workpiece is pressed back to the original shape. The material structure can be refined by repeating the processes. The repeatedly extruding upsetting die is simple in structure, convenient to machine and easy to operate, can be realized on conventional pressure machining equipment, and can obtain uniform deformation in the material, and is applicable to a wide range of materials.

Description

technical field [0001] The invention relates to the technical field of metal plastic processing, in particular to a repeated extrusion die and method for preparing bulk ultrafine-grained materials. Background technique [0002] Ultra-fine-grained materials generally refer to materials whose grain size is submicron (100nm~1000nm) or nano-sized (<100nm). Due to the refinement of the structure, the proportion of grain boundaries increases, so that ultra-fine-grained materials show good strength. , wear resistance, fatigue resistance, low temperature or high strain rate superplasticity, good physical, chemical and biological properties, etc., can fully tap the potential of materials, and has important applications in aerospace, national defense, machinery, biomedical and other fields Application prospect. [0003] Severe plastic deformation technology (SPD) is an effective method to achieve ultra-fine material structure. Its main feature is to gradually accumulate sufficient...

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Problems solved by technology

However, in this method, the side surfaces of the solid and hollow indenters must be parallel to the axis of the indenter. When the material flows through the corner between the lower end surface and the side surface of the indenter, severe shear concentration is likely to occur, and it is difficult for the material to deform at room temperature. It is used for hot extrusion of magnesium alloy, and it is easy to form an "inverted triangle" deformation dead zone at the lower end of the solid indenter

[0005] Further searches found that the Chinese invention patent authorization number CN102766832B invented a bidirectional repeated extrusion strengthening method for magnesium alloy blocks, which repeatedly extruded and deformed the workpiece from two directions, but this method required special repeated extrusion equipment, and The extrusion head and the extrusion ring move in reverse all the time, which requires high equipment

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