METHOD FOR SHAPING LONG-DIMENSIONAL PARTS OF DOUBLE-CURVATURE SHELLS HAVING A DOUBLE-CONVEX SLOW SHAPE BY STRETCH FORMING Russian patent published in 2023 - IPC B21D11/20 

FIELD: metal forming.

SUBSTANCE: invention can be used in the manufacture of the outer skin of the aircraft using stretching presses with program control. The press comprises a table with a tight punch, left and right rotary clamping plates with discrete clamping devices and tension cylinders. Clamping devices provide for rectilinear and curvilinear arrangement. At the shaping stages, the sheet blank is wrapped along the shaping outline of the tight punch by raising the table and turning the clamping plates with rectilinearly arranged discrete clamping devices. At the end of the table lifting and clamping plates turning, the sheet blank is stretched in the direction tangentially to the surface of the descent of the shaping outline from both ends of the tight punch. The sheet blank is unloaded by lowering the table to ensure its isometric straightening with an increase in the transverse curvature in the central part and stretching of the side sections by tension cylinders. The clamping devices are installed to ensure their curvilinear arrangement when the tension cylinders are not in operation. The press table is raised to obtain the shape of the shell part and ensure that its corner parts are pressed against the surface of the tight punch. The pressed corner parts are stretched by tension cylinders.

EFFECT: decrease in the non-uniformity of the tensile deformation of the sheet blank and a shell with a minimum thickness variation in one transition.

1 cl, 10 dwg