METHOD FOR TESTING SHEET MATERIALS TO AXISYMMETRICAL DRAWING

FIELD: technological processes.SUBSTANCE: invention relates to sheet stamping, in particular to the sheet materials mechanical properties study for their formability evaluation, as well as to the use of shaping sheet-forming operations in CAD/CAE-systems for computer modeling and design. Essence: cutting the circular workpiece from the tested sheet material. Applying the dividing grid onto the workpiece. Placing the workpiece into the testing machine tooling. Before stretching between the workpiece and the punch and the clamp, directly above the punch end, placing the antifriction gasket from film with such overall dimensions that during the testing workpiece touches the punch and clamp surfaces only through this antifriction gasket. On the double-acting testing machine with bottom drive and two outer and inner sliders workpiece flange pressing is performed by the tooling clamping with the outer slider upward stroke with minimum pressing force. Axisymmetric part drawing from the workpiece is performed with the bottom upwards using the antifriction gasket on the punch stroke, by its end, made flat with the undercut, with a radially rounded edge in the tooling matrix with the inner slider upward stroke. When carrying out tests, the overall dimensions of the blank are gradually increased to the maximum dimensions, at exceeding of which the drawing by the passage of the punch in the matrix leads to the detachment of the bottom of the part from the wall. Producing the machine diagram for the drawing force and the pressing force dependence along the drawing stroke. Calculating the limiting coefficient of drawing, elongated part relative height along the largest cavity on the part wall, maximum drawing force and minimum pressing force, near the dangerous section of the part with the minimum thickness from the change in the dividing grid, deformations are determined and the values of these strains are plotted on the limit deformation diagram.EFFECT: technical result: the ability to construct additional points in the limit deformation diagram (LDD), and thereby increase the LDD accuracy and the LDD application accuracy in CAD/CAE-systems, reduces the time and improves the quality of the technological processes and tooling design for sheet punching, saves the sheet material by reducing the percentage of rejects during the technological processes adjustment, and also simplifies the sheet material and equipment selection for sheet stamping parts, for example, of cars