METHOD OF MOLDING FILTERING SEMI-MASK Russian patent published in 1994 - IPC

FIELD: manufacture of individual means of protecting respiratory organs. SUBSTANCE: object of this method is molding semi-mask with obturator from flat one-piece polygonal blank. This method includes such steps as cutting out flat right-triangle blank from filtering material (ratio of filtering portion width to its length is 0.8 : 1.2 and total length is equal to obturator double width), bending off edges of blank outside throughout its width to extent equal to obturator width, folding blank in two along its lateral axis of symmetry, again folding each half in two with bending it off outward, securing material on smaller sides of thus formed right triangle, turning inside out, folding up blank inner portion along diagonals of four right triangles formed by blank axes of symmetry in such a manner as to form rhomb, bending off smaller legs of paired bent-outside right triangles, positioning these legs under one of obturators, and straightening out blank to impart it three-dimensional shape. EFFECT: saving of filtering material. 7 dwg