VOID-FORMING CORES Russian patent published in 1994 - IPC

FIELD: construction engineering. SUBSTANCE: void-forming cores have flexible cylindrical shell with longitudinal through slit to accommodate movable insert. Located inside shell is bar coupled with arms cooperating with tension members secured on shell inner surface in the form of springily plates located along chord of shell cross-section. Void-forming cores are provided with additional arms to hold insert down; arms are hinge-jointed with bar which is rigidly attached to shell inner surface oppositely slit and hinge-joined with main arms. Drive is provided with flexible rods connected with tie rods and accordingly with main and auxiliary arms for their rotation. EFFECT: enhanced reliability of operation. 5 dwg