METHOD TO PRODUCE HOLLOW PIECES Russian patent published in 1994 - IPC

FIELD: construction. SUBSTANCE: first by bending they produce U-shaped section trough with lines of bending that are in parallel to one of blank sides. Trough is situated in closed volume and draw its corner areas and bend its peripherals areas. Corner areas of rectangular form blank are rounded by radius, equaled to height of piece and with its located on line of bending center. Beam of plastic metal, for example, from lead or flexible material is inserted in produced trough. Drawing of corner areas and bending of peripherals areas are carried out by turning of corner areas around axes, passing through centers of roundings of corner areas of blank. In the case they provide pouring out of produced excess of plastic metal into additional cavity and reaction butt selection of trough perimeter. EFFECT: method is used to produce hollow case type pieces of construction materials. 3 cl, 4 dwg