Electrically-assisted tooth-shaped rolling process and device for preparing gradient ultrafine-grained sheet

An electrically-assisted tooth-shaped rolling process for preparing a gradient ultrafine-grained sheet, comprising the following steps:

• S1, polishing a surface of a raw sheet to obtain a polished sheet;
• and then cutting the polished sheet to form a prefabricated sheet with a preset target shape;
• S2, fixedly placing the prefabricated sheet in a forming groove (2) with a shape matched with the preset target shape of the prefabricated sheet;
• setting current parameters of a pulse power generator;
• and connecting the prefabricated sheet with a power output terminal of the pulse power generator (9);
• S3, connecting a rib-forming pressure roller (503) with another power output terminal of the pulse power generator (9), the rib-forming pressure roller (503) being located above the prefabricated sheet and having convex-concave textures on a cylindrical surface thereof;
• driving, by a pressurizing device, the rib-forming pressure roller (503) to move downward until the cylindrical surface of the rib-forming pressure roller (503) is in contact with an end of a surface of the prefabricated sheet, to apply a first preset pressing force onto the prefabricated sheet;
• S4, driving, by a horizontal displacement device, the forming groove (2) and the prefabricated sheet to move horizontally, thereby causing the rib-forming pressure roller (503) to roll relative to the surface of the prefabricated sheet until the rib-forming pressure roller (503) disengages from another end of the surface of the prefabricated sheet;
• wherein, in a relative rolling process between the rib-forming pressure roller (503) and the prefabricated sheet, pressing ribs on the cylindrical surface of the rib-forming pressure roller (503) sequentially contact with different positions on the surface of the prefabricated sheet, and local heating is caused at the different positions on the surface of the prefabricated sheet due to passage of current;
• and after the relative rolling process between the rib-forming pressure roller (503) and the prefabricated sheet is completed, concave-convex textures are formed on the surface of the prefabricated sheet to thereby obtain a first loading step formed sheet with the concave-convex textures on a surface thereof;
• S5, connecting a rib-flatting pressure roller (504) with the another power output terminal of the pulse power generator (9), rib-flatting pressure roller (504) being located above the first loading step formed sheet and having a smooth cylindrical surface;
• and driving, by the pressurizing device, the rib-flatting pressure roller (504) to move downward until the smooth cylindrical surface of the rib-flatting pressure roller (504) is in contact with an end of the surface of the first loading step formed sheet, to apply a second preset pressing force onto the first loading step formed sheet;
• S6, driving, by the horizontal displacement device, the forming groove (2) and the first loading step formed sheet to move horizontally, thereby causing the rib-flatting pressure roller (504) to roll relative to the surface of the first loading step formed sheet until the rib-flatting pressure roller (504) disengages from another end of the first loading step formed sheet;
• wherein, in a relative rolling process between the rib-flatting pressure roller (504) and the first loading step formed sheet, the smooth cylindrical surface of the rib-flatting pressure roller (504) sequentially contacts with convex parts at different positions on the surface of the first loading step formed sheet, and local heating is caused at the different positions on the surface of the first loading step formed sheet due to passage of current;
• and after the relative rolling process between the rib-flatting pressure roller (504) and the first loading step formed sheet is completed, the concave-convex textures on the surface of the first loading step formed sheet are restored to a plane shape to thereby obtain a second loading step formed sheet;
• S7, driving, by the pressurizing device, a straightening pressure roller (505) with a smooth cylindrical surface and located above the second loading step formed sheet to move downward until the smooth cylindrical surface of the straightening pressure roller (505) is in contact with an end of a surface of the second loading step formed sheet, to apply a third preset pressing force onto the second loading step formed sheet;
• S8, driving, by the horizontal displacement device, the forming groove (2) and the second loading step formed sheet to move horizontally, thereby causing the straightening pressure roller (505) to roll relative to the surface of the second loading step formed sheet until the straightening pressure roller (505) disengages from another end of the second loading step formed sheet;
• and performing, by the smooth cylindrical surface of the straightening pressure roller (505), cold straightening on the surface of the second loading step formed sheet to adjust a flatness of the surface of the second loading step formed sheet;
• S9, repeating step S3 to step S8 for a preset number of cycles to complete a multi-pass rolling forming process so as to obtain the gradient ultrafine-grained sheet;
• and
• S10, turning off the pulse power generator (9), resetting the pressurizing device and the horizontal displacement device, and removing the gradient ultrafine-grained sheet from the forming groove (2).