VOID-FORMING CORES Russian patent published in 1994 - IPC

FIELD: construction engineering. SUBSTANCE: void-forming cores have flexible cylindrical shell longitudinal through slit to accommodate movable insert. The latter cooperates with hold-down device in the form of U-shaped flexible member rigidly attached by its ends to shell and located above shell slit. Tightener is made in the form of rotary bar with cores which cooperate with tension members in the form of strings secured on shell inner surface. Tension members are located along chord of shell cross-section and laid along shell somewhat displaced from U-shaped flexible members. The latters cooperate with cores of bar which is located in insert. Insert have ports for bar cores and shaped slot for drive handle moved along slit in process of operation. EFFECT: enhanced reliability of operation. 7 dwg