Type 1 LTM1180 auto crane after long-term use, the rotary gear reducer rotating pinion bearing parts in fever, sound, oil and other conditions. Inspection found that the slewing reducer bearing wear faults, the bearing outer ring fall off.

The slewing reducer shell for cast steel material, poor weldability, welding is easy to produce white the organization, porosity and crack. Two type of bearings bearing hole assembly in 3524 and 3526 respectively, two hole accuracy is high, its diameter (215 + 0.01) mm, respectively (260 + 0.01) mm.

When crane slewing bearing hole absorb a certain amount of impact vibration, so request a hole material hardness is moderate, and have a certain impact and vibration resistance. Here are three repair methods of the bearing.

1. The welding junction method

Repair by welding junction process is as follows: first, the rotary gear reducer shell after clean, with boring boring hole, then a hole diameter appropriate increase. Shell into a second, preheat the oven to 400 ℃ or so, and then heated to a hole red state (about 900 ~ 900 ℃); Again, with copper alloy electrode surfacing to predetermined thickness, add the oven (temperature about 250 ℃), slow cooling, heat treatment or use infrared heater; Finally, the overlaying welding good hole finishing to design size.

Advantages are: using the bearing hole after the restoration of the better resistance to impact and vibration resistance, quality is stable, with a long cycle use. The downside is welding repair process complex, long cycle, high cost, easy to wear and tear and loss of skin after repair.

2. Set set of method

Set set of repair process is as follows: first, clean the bearing hole clean, reoccupy boring boring hole, with a seat hole more 8 ~ 10 mm; Second, car manufacturing cast steel set set, after the outside diameter of the boring set set of a hole for cooperate; Finally, the set of installed to increase after a hole, and finishing to design size.

Methods by using this scheme the method is simple, low cost, short time to repair. The downside is the set of the clearance between the shaft and the demand is higher. If the set set of inner hole and bearing clearance is too small, easy to make bearing heating; If the set set of inner hole and bearing clearance is big, easy to make the bearing slide.

3. Partial replacement method

Local change method to repair process is as follows: first, to surveying and mapping of slewing reducer bearing parts, and use high strength material processing a new bearing; Second, the bearing seat with lathe turning away from the rotary gear reducer shell, and are produced with the new production of bearing seat connection interface and thread; Again, the new production of bearing seat through the screw thread and gear reducer shell, and a filling reducer shell with welding method of reinforcement, and the welding interface area; Finally, the new bearing hole finishing to design size.

Comprehensive analysis thinks, although former two repair methods have many advantages, but does not apply to the repair of the bearing, slewing reducer shell therefore decided to adopt the local repair slewing reducer shell replacement method. Processing speed reducer and the material selection of the bearing high manganese steel, common high manganese steel such as mn18cr3 Mn13, 40 and 50 mn18cr4. The raw material is not very high hardness, but its good plasticity and toughness, hardness can reach HBW500 after processing.

The partial replacement method is adopted to the rotary gear reducer bearing seat after repair, refitted commissioning, the working rotary gear reducer is normal.