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, in particular to the study of the mechanical properties of sheet materials to assess their formability, as well as to the use of shaping sheet-forming operations in CAD / CAE-systems for computer modeling and design. Essence: a workpiece is cut from a test sheet material, a dividing grid is applied onto the workpiece, the workpiece is placed in the rigging of the testing machine, a technological padding of the same dimensions is placed under the workpiece, wherein the padding is made from the material whose plasticity index is not lower than the plasticity index of the test workpiece, and the hole in the process padding is made with a diameter that is smaller than the punch diameter, the contacting surfaces of the technological padding and workpiece are degreased and a rosin powder is poured between them, before stretching, between the padding, punch and clamp, directly above the end of the punch, an antifriction liner is placed, its overall dimensions are such, that during the test the technological padding touches the punch surfaces only through this anti-friction liner. On a double-acting test machine with a lower drive and two outer and inner sliders, the pressing of the flanges of the workpiece and technological padding is performed by pressing the tooling while the outer slider is moving upward with the minimum pressing force, to eliminate the folding of the flanges when drawing, and the drawing of the axisymmetric part from the workpiece is carried out with its bottom up, using the technological padding and antifriction liner by the passage of the punch, its forming working edge, executed with a smoothly decreasing curvature, in the tooling matrix when the inner slider moves upwards, during testing, the overall dimensions of the workpiece are gradually increased to the limiting 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, a machine diagram is obtained that shows the dependence of the drawing force and the pressing force alone the drawing direction. Then the ultimate draw ratio is calculated, as well as the relative height of the drawn detail along the largest cavity on the part wall, the maximum drawing force and the 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 build additional points in the limit deformation diagram, and thereby increase the accuracy of the limit deformation diagram and the accuracy of the application of the limit deformation diagram in CAD / CAE systems, reduce the time and improve the design of the manufacturing processes and tooling for sheet metal forming, and also simplification of a choice of sheet material and the equipment for sheet forming of parts.

9 cl, 2 dwg