METHOD FOR BLANKING BELT, WIDE COIL OR STRIP AT SMALL QUANTITY OF SCRAP (VARIANTS) Russian patent published in 2007 - IPC B21D28/06 

FIELD: processes and equipment for sheet forming.

SUBSTANCE: method is used for blanking from sheet material such as belt, wide coil or strip successively one after another at predetermined pitch set by means of feeding device of equipment blanks by means of punch and die of blanking die set mounted in said equipment. Blanks are blanked without lateral bridges between two adjacent blanks and also without bridges between blanks and edges of belt by means of cylindrical punch with tapered face having cross section in the form of circle with chord and with diameter exceeding width of belt. Difference between nominal size of punch diameter at taking into account lower limit fluctuation and nominal size of belt width at taking into account upper limit fluctuation exceeds nominal thickness of sheet material. In variants of invention chord of circle of cross section of punch may be equal to, less or more than length values of pieces cut by punch along two edges of belt during blanking process. Stroke of feeding sheet material or blanking die set is equal to or more than nominal length of blank in allowance field of feeding device. In other variant of method according to invention cylindrical punch used for blanking has cross section in the form of circle whose diameter exceeds width of belt. Difference between nominal diameter of punch at taking into account lower limit fluctuation and nominal width of belt at taking into account upper limit fluctuation exceeds nominal thickness of sheet material. Feed stroke of belt or blanking die set is less than diameter of punch while taking into account lower limit fluctuation in allowance field of feeding device of equipment. Next and previous circles of punch contour in plan view are mutually overlapped by such value that acute angle between tangent lines to next and previous circles in their crossing point exceeds 1°. In next variant of method according to invention punch with cross section in the form of closed or non-closed regular or irregular polygon is used. Size of said punch in direction normal to belt sides exceeds width of blank and in direction along belt exceeds length of blank. Minimum acute angle between punch side in cross section and side of belt exceeds 1°. Difference between nominal width of punch at taking into account lower limit fluctuation in direction normal to belt sides and nominal width of belt at taking into account upper limit fluctuation exceeds nominal thickness of belt. Difference between nominal length of punch at taking into account lower limit fluctuation and nominal length of blank at taking into account upper limit fluctuation also exceeds nominal thickness of belt. Feed stroke of sheet material or blanking die set is equal to or more than nominal length of blank in allowance field of feeding device of equipment.

EFFECT: reduced consumption of sheet material, improved accuracy of blanks and strength of blanking die set.

5 cl, 7 dwg