The chain hub sprocket of the excavator bears a great impact load in the process of operation. When the excavator tilts, the stress state is more unfavorable.In general, when the excavator is running for 350,000 h or so, the chain hub sprokcet sprocket teeth may collapse or break, and the tooth shape wear and tooth broken phenomenon at the joint part of the two halves of the chain hub sprocket is particularly serious.It has been proved by practice that using insert welding to repair the ring gear is simple and quick, and can guarantee the performance of the whole machine.
According to the damage of chain hub sprocket , determine the position of the fixed hole and the damaged section to be replaced, and then cut off the section of teeth to be replaced with gas cutting. Make inserts according to the sprocket parts that need to be repaired, or cut a better section of sprocket teeth from the corresponding part of another old ring gear with the guarantee of pitch, and cut out the groove shape at the junction. determine the position of the insert fixing hole, punch it and fix it in the corresponding part of the chain hub sprocket , and pay attention to ensure the accuracy of the fixing hole position.In order to ensure that the weld has a higher strength and can withstand greater impact and vibration, the diameter of Φ4 mm joint 507 electrode is selected. The electrode should be baked for 1 h at 250 ~ 350 ℃ before use.Ax3500 DC arc welding machine DC reverse welding method, the current is 130 ~ 140 A.
Before welding, preheat the welding surface to about 200 ℃ with 2 large gas welding gun.With the backfire weld, the latter weld can temper the former weld, which is beneficial to eliminate the hardened microstructure produced by the former weld.Because the groove is large, the first weld should be welded slightly thinner to reduce the width of fusion and reduce the carbon content of steel.When applying welding, the electrode tilts forward about 15° and moves forward in a straight line. When closing the arc, attention should be paid to filling the arc pit to avoid producing the arc pit crack.After welding, quickly hammer the weld and both sides with a small pointed hammer to relax the stress until there are dense pitting spots in the weld.Continue to weld when the weld cools about 200 ℃.The welding method of each weld after the first weld is the same as that of the first weld. The electrode can be swung slightly. In order to avoid pores, do not swing too large.After welding, in order to eliminate the hardened tissue and stress, the welding seam and both sides are heated to about 600 ~ 650 ℃ with oxygen acetylene flame, and the heat is kept for 20 min. Then, the welding seam is covered with asbestos, hydrated lime powder or dry sand, and the welding seam is slowly cooled to room temperature.Use polishing wheel to polish the weld, so that the chain hub sprocket repair is completed.
Post time: Jul-16-2021
