Repair method of cycloid needle wheel of reducer o

  • Detail

Repair of cycloid pinwheel of reducer of tower crane test procedure for fatigue life of front axle bench of automobile: after 9 years of service of qt16 tower crane, the tower body suddenly failed to rotate during construction. During disassembly and maintenance of reducer, it was found that there were many cracks, wear and falling blocks on the second stage cycloid pinwheel of reducer. As there are no spare parts in stock, it is decided to repair by welding

1. weldability analysis

the cycloid needle wheel is made of GCr15, which has high carbon content, high hardening tendency, easy to crack and s, P segregation, high thermal cracking sensitivity and poor weldability

2. repair welding measures

(L) crack elimination according to the different crack shape, depth and length, use a grinder to eliminate the shallow and short cracks first, and then the deep and long cracks. The grinding sequence is from the crack end to the crack elimination, so as to prevent the crack from spreading and grind the groove at the same time. For cracks that are not fully penetrated, smooth transition shall be made at the bottom of the groove to reduce stress concentration; A single V-groove shall be made for the through crack

(2) the repair welding process corrects the crack so that its surface is in a plane, and spot welding is used to fix it. The repair welding sequence is to weld the short and shallow crack first, then weld the crack through, and finally weld the damaged part to the original shape

when repairing short and shallow cracks, it is required to start the arc from the crack tail first to prevent cracks during welding. Weld point by point and observe while welding. Through the repair welding observation of the first crack, no crack or new crack is found, which proves that the welding process is feasible

in case of repair welding cracks, the back must be thoroughly cleaned with a grinding machine before back welding to expose the metallic luster

for worn and damaged parts, oil stain and rust shall be removed before repair welding

(3) are the welding specification parameters required by the part and to make the safety in the experiment process higher? The following: stainless steel electrode with good abrasion resistance, high precision, but poor weldability is selected as the filling material, which has good crack resistance, abrasion resistance and acceptable machinability. Its brand is A307 and its specification is ¢ 3.22mm. It is heated to 350 ℃ and baked for 2h. The operator operates in strict accordance with the operating procedures. The welding current is 90-100a, the welding voltage is V, and the welding line energy is kJ/cm. The welding machine is ax-320 with reverse connection

(4) post weld treatment the whole part shall be kept warm and cooled slowly after welding. After cooling, it is necessary to accurately measure the torque and change the angle on the fixed scale, and then machine two planes on the lathe after reaching the room temperature. The excess surfacing metal on the edge shall be trimmed with a file until the cycloid needle wheel is restored to the original geometric dimension

3. effect

the cycloid needle wheel has been used for more than 5 years since it was repaired. It has good performance, fully meets the use requirements and saves maintenance costs

Copyright © 2011 JIN SHI