MANDREL FOR MANUFACTURE OF HOLLOW ITEMS FROM PLASTICS Russian patent published in 2007 - IPC B29C53/82 

FIELD: treatment of materials in plastic state; molding the cavities in long-cut items, spars of helicopter main rotor blades in particular.

SUBSTANCE: proposed mandrel has insertion rod of varying profile and longitudinal sectors forming contour of cavity with insertion rod fasteners having trapezoidal profile; they are locked with wedges at the end of mandrel. Insertion rod is wedge-shaped in form. Fasteners are made on both sides of insertion rod in form of prism combining pair of adjacent sectors by lesser base of trapezoidal profile symmetrically relative to their parting plane and trapezoidal slot on insertion rod embracing the trapezoidal prism; insertion rod may be inserted between pairs of sectors for forming the fastening strength by action of inclined sides of trapezoidal profile of prism and slot locked by wedges at the ends of mandrel. Lateral sides of insertion rod form contour of cavity of item together with longitudinal sectors along entire length of their conjugation.

EFFECT: enhanced longitudinal rigidity of mandrel and strength of sectors.

8 cl, 3 dwg