METHOD FOR TESTING SHEET MATERIALS TO AXIOSYMMETRICAL DRAWING Russian patent published in 2018 - IPC G01N3/28 

FIELD: metal processing.

SUBSTANCE: invention relates to sheet-metal forming, and, in particular, to the study of the mechanical properties of sheet materials to assess their formability, and also to the use of sheet-forming operations in CAD / CAE-systems in computer simulation and design. Essence: a circular blank is cut from the test sheet material and a dividing grid is applied to the blank. Then the blank is placed in the rigging of a double-acting test machine with a lower drive and two sliders, external and internal. Pressing of the flange of the blank is performed to eliminate the folding of the flange during drawing by pressing the tool when the outer slider moves upwards with a minimum clamping force. Drawing of an axisymmetric part from the blank is carried out with a bottom upwards by the passage of the punch, its end, made flat with an undercut, with a radially rounded edge, in the tooling matrix when the inner slider moves upward. 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. Then a machine diagram is obtained that shows the dependence of the drawing force and the pressing force alone the drawing direction, the ultimate draw ratio is calculated, the relative height of the drawn detail along the largest depression on the wall of the part, the maximum drawing force and the minimum clamping force, in the vicinity of the dangerous section, the parts with the minimum thickness from the change in the dividing grid the deformations are determined and the values ​​of these deformations are plotted on the limit deformation diagram.

EFFECT: technical result: the ability to construct additional points in the limit deformation diagram, and thereby increase the accuracy of the limit deformation and the accuracy of the application of the limit deformation in CAD / CAE-systems, reduction of time and improvement of design quality of technological processes and equipment for sheet forming, saving sheet material, as well as simplifying the choice of sheet material and equipment for sheet forming of parts.

1 cl, 2 dwg