Repair method of turntable working face of the hot

Repair method of the working surface of the upper turntable of hoisting machinery

the working surface of the upper turntable of a Puyuan 25t crane (the contact surface connected with the inner ring of the slewing ring by bolts is called the working surface), is a ring with an outer ring diameter of 1286mm and an inner eye diameter of 1040mm. The inner and outer rings of the ring are welded into one with the upper turntable. When lifting heavy objects at one time, 1/3 of the welded junctions of the inner and outer rings of the ring are torn apart, Some of the connecting bolts between the working surface of the turntable and the inner ring of the slewing ring were also cut off

because the working surface of the turntable is 22mm thick, the inner and outer rings are welded into one with the turntable in the form of full welding, and 40 m243 threaded holes are evenly distributed around the ring, and the depth of the threaded holes is all the way to the turntable base plate, with a total depth of 43mm; The 40 threaded holes on the ring are connected to the inner ring of the slewing ring, that is, the inner ring of the slewing ring is connected to the upper part of the crane, and the outer ring also has 40 holes evenly distributed to connect the carrier part

according to the regulations, the slewing bearing must maintain sufficient pre tightening force. The pre tightening degree of bolts should be checked after running for 100h, and then every 500h. Generally, bolts should be replaced after 7 years or 14000h of work

when installing the slewing ring, be sure to use a torque wrench to tighten the bolts according to the specified preload

because its structural performance fully meets the requirements of the experimental specifications, it ignores the inspection of the pretightening force of the slewing bearing bolts. Under the action of external forces, the bolt tension and torsional shear stress exceed the yield limit value of the bolt material, resulting in the breakage of the slewing bearing bolts, and the welded junction of the threaded thread of the bolts and the threaded connection of the working surface of the turntable is also torn

due to the large length, width and height of the turntable of Puyuan 25t crane, the press cannot be used, so the self-made gantry can only be used when calibrating the turntable

after the disassembled turntable is inverted (the working surface of the turntable is upward), it is stably supported on a 6m 0.05m steel plate. According to the length, width and height of the turntable, the gantry required is designed to correct the cracked turntable working surface. The circular ring should be compacted with a hydraulic jack of not less than 50t to ensure that the ring surface and the turntable are flat and have no gap before welding. Thj506 carbon steel welding rod with specification of 4mm is used. The high-tech flow of welding electrical instruments and meters is 140 ~ 160A (ac/dc). Short arc operation is adopted. Bake before welding, keep warm for 1h, and use as you go. The weld crater height is not less than 8mm. In order to prevent the welding deformation between the ring and the turntable, diagonal welding is used during welding

due to the cracking of the working surface, some turntable turnbuckles have been pulled out and cannot be used. After the working surface is welded with the turntable, the broken screw holes are filled with thj5 recycled plastic granulator with a specification of 2.5mm. 02 carbon steel electrode, welding current of 110 ~ 120a (ac/dc) plug welding. During plug welding, the coating must be removed while welding to ensure that there are no pores and sand holes in plug welding

after the threaded hole is welded, process a stabbing sleeve for drilling. Finally, use the slewing ring to locate and centralize the drilling hole on the turntable, and then use the appropriate m243 tap to tap the thread. The thread itself has the characteristic of self-locking. With this repair method, it has been working for 2 years since it was repaired to drive the BDO market, and the turntable operation is still stable and reliable