A method for ultra-fine grain rolling of large-size aluminum alloy rods with reverse-cone helical rolls

Abstract

The invention relates to a reverse cone spiral roller ultra-fine grain rolling method of a large-size aluminum alloy bar, and relates to the field of mechanical processing. The method includes the following steps that a rolling tool is designed, wherein roll design and guide plate design are specifically included, and rollers are arranged to be double curved surface type circular-table-shaped spiral rollers; a deformation zone is constructed, wherein the curved surfaces of two guide plates are oppositely arranged, the two rollers are placed between the guide plates, and an area defined by thetwo guide plates and the two rollers is the deformation zone; an equal-ovality deformation zone is constructed, wherein the ovality in the deformation zone remains unchanged; and a rolling feeding mode is selected, wherein a reverse rolling mode is adopted. According to the reverse cone spiral roller ultra-fine grain rolling method of the large-size aluminum alloy bar, the double curved surface type circular-table-shaped spiral rollers and the curved surface guide plates are designed, the equal-ovality deformation zone is constructed, and acute plastic deformation is generated on the premise that the heart Mannesmann effect is significantly suppressed.

Description

technical field [0001] The invention relates to the field of mechanical processing, in particular to an ultra-fine-grain rolling method of a large-size aluminum alloy bar with a reverse-cone helical roll. Background technique [0002] Ultrafine crystal / nanocrystalline materials and their preparation technology are one of the research hotspots in the field of material science. Research in this direction embodies people's efforts to continuously improve the strength and toughness of polycrystalline materials through continuous refinement of grains. Among them, the research results of severe plastic deformation (Severe Plastic Deformation, referred to as SPD) technology are eye-catching. [0003] At present, the mainstream SPD process includes five methods: high pressure torsion (HPT), equal channel angular extrusion (ECAP), cumulative stack rolling (ARB), multidirectional forging (MF) and torsion extrusion (TE), among which: [0004] (1) High-pressure torsional deformation: ...

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Problems solved by technology

[0015] (1) During the ECAP deformation process, the blank is in full contact with the mold, and the friction force is large, so the forming load is large, the finished product size is small, and the material utilization rate is low, the production efficiency is low, and it is difficult to realize the preparation of large-scale ultra-fine-grained materials required by industrialization

[0016] (2) The forming load of HPT is huge. The existing forming equipment generally does not have the loading capacity of more than tens of GPa for industrialized large-scale products, and is only suitable for the forming of ultra-thin products such as films. Usually, the blank before deformation is Φ10~15×1~ 10mm cylinder

[0017] (3) The ARB process is limited by the volume of the deformation zone and the uniformity of deformation, and the thickness of the deformation zone is only mm level

At the same time, since the prepared ultrafine grains are elongated grains in the shape of cakes, their mechanical properties are worse than those of three-dimensional equiaxed grains.

Therefore, limited by the loading capacity and uneven deformation, ARB can only prepare ultra-thin sheets

[0018] (4) Due to the serious deformation inhomogeneity of MF and TE, the grain size is uneven, the stability of the grain structure is poor, and the performance is reduced, and it is also impossible to prepare large-size forgings

[0019] (5) There are the following problems in the helical conical roll equidistant rolling method (application number 201810172516.2) of large-size aluminum alloy ultra-fine-grained rods: 1) The shape of the roll in the original technology is a single tapered roll, and the billet enters the roll. , due to the gradual increase of the diameter of the roll, the speed of the contact area between the roll and the billet will gradually increase, which will lead to an increase in the deformation speed difference between the core and the edge of the billet, thereby aggravating the deformation unevenness

[0021] A comprehensive analysis shows that the aluminum alloy ultra-fine grain technology mentioned in existing patents or papers can only produce small-sized ultra-fine grain materials due to the volume limit of the deformation zone, and it is difficult to produce large-scale industrial-grade overall ultra-fine grains (Φ60~ Φ500mm) material

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