METHOD OF RIVETING COMPOSITE STACKS AND DEVICE FOR GROUP RIVETING Russian patent published in 1994 - IPC

FIELD: metal working. SUBSTANCE: holes are made in parts at various stages of their manufacture; diameters of these holes shall not exceed the diameter of rivet shank and shall depend on elastic properties of materials of parts. Rivet with flat head is inserted in holes of parts. Stack is placed on riveting device, fixed with compressive force and point of rivet is formed in two stages. In riveting the parts made of fibrous composite materials with plastic frames and rubberized combined fabrics, use is made of blind axial channel at end of shank; bottom of channel is conical in shape; depth of channel is equal to 1.0 to 1.2 and its diameter is equal to 0.75 to 0.8 of diameter of rivet shank. Rivet is first inserted in hole of lower frame, after which remaining parts are placed on rivet shank. Fixing the stack is effected by compressive force not exceeding 0.95 of elastic deformation limit of part which possesses minimum strength as compared with other parts; points of rivets are formed simultaneously after fitting all rivets. At first stage, hollow portions of rivet shanks are expanded by pulsating force applied radially; at second stage, hollow portion of rivet shank is upset by static force applied axially. Device for group riveting has bed frame which holds upper fixed plate, cradle for mounting the stack to be riveted, movable plate with drive for its motion and with clamp for securing the stack and with riveting mechanism made in form of power plate with riveting punches which is connected with drive made in form of power cylinder. Device is provided with guide plate with self-setting bushes mounted on it; this plate is mounted in between movable plate and power plate. Upper plate is provided with guide bush for rod of power cylinder which has port in side wall and member for axially locking the rod of power cylinder made in form of damper connected with drive and mounted for motion in guide bush port. Areas where punches are mounted in power plate are provided with flexible inserts and each punch has spherical bearing surface with through axial hole which receives spring-loaded rod for orientation of punch relative to rivet linked electrokinematically with control system of power cylinder and is arranged in self-setting bush of drive plate. Power cylinder has two stages at ratio of piston diameters of 4: 5; cylinder housing is secured on power plate, its rod is arranged in guide bush of upper fixed plate and working chambers of stages may be connected with compressed air source through control system either in turn or simultaneously. EFFECT: enhanced efficiency. 5 cl, 8 dwg