METHOD OF RECONDITIONING CRANE RUNWAY BEAMS WITH FATIGUE CRACKS Russian patent published in 2003 - IPC

FIELD: metallurgy. SUBSTANCE: invention relates to heavy-duty bridge cranes operating in open-hearth and converter plants. According to said method special cover plates are used in process of reconditioning of crane runway beams with fatigue cracks to increase load- bearing capacity of structure. Defective crane runway beam is prepared for reinforcement. For this purpose upper part of intermediate stiffening ribs of beam is cut at one side of beam wall by 1/5-1/6 of their height which corresponds to height of support part of cover plate. Then recess is made pointed to wall for vertical web of cover plate, and cutouts are made in upper part of support ribs of beam of height not less than 100 mm and up to 0.5 of their width. Holes for rivets-bushings, diameter up to 0.9 of design size are made in horizontal and vertical sections of cover plates mating, respectively, with lower surface of upper chord and wall of beam to be reconditions. Then cover plate is arranged along upper chord to rest against upper end face of cut off intermediate stiffening ribs, mating horizontal butt joint section of cover plate with upper chord of crane runway beam from bottom, and vertical butt joint section, with wall. Cover plate is connected to upper chord of crane runway beam by temporary fasteners. Holes, diameter up to 0.9 of design size, are made in upper chord of crane runway beam, coaxially to holes made in cover plate, by means of pyrotechnic plant. Cover plate is braced together with upper chord of beam by bolts driving them into each second hole. Upper part of intermediate stiffening ribs at other side of crane runway beam is cut off similar to that described above, and other cover plate similar to first one is arranged in mirror like manner relative to vertical wall. Mounting and assembling operations recommended for fastening first cover plate are carried out. Similar holes are made in vertical wall of crane runway beam coaxially to holes made in cover plates and then cover plate and beam are braced together by bolts. Vacant holes in braced together members are drilled to diameter of 0.95 of design size. Then holes are reamed to their design diameter and rivets-bushings are freely fitted into prepared holes. Cover plates are connected with crane runway beam. Then holes temporarily occupied by assembly bolts are freed and described cycles are repeated until all fasteners are fitted in all holes. Special technological equipment is mounted on upper and lower platforms. Pyrotechnic plant and drilling machine tool are mounted on each platform. Working members of said equipment are vertically orientated on upper platform and horizontally, on lower platform. EFFECT: possibility of reconditioning of crane runway beams with fatigue cracks in upper zone under rail. 5 dwg