The excavator receives a large impact load during the operation of the rotating ring gear. When the excavator is tilted, the force state is more unlucky. Usually, when the excavator is operated for 350,000 hours, the rotating ring gear teeth may be crushed or broken, and the toothed wear and broken teeth of the two half ring gear joints are particularly severe. Practice has proved that the selection of the excavator gear fitting insert welding and correction of the rotating ring gear is both concise and convenient, and can ensure the function of the whole machine.

1, pre-weld preparation

(1) According to the damage of the ring gear, determine the orientation of the fixed hole and the damaged segment that needs to be replaced, and then cut a piece of the tooth to be replaced with gas.

(2) According to the requirements of the ring gear part, the manufacturing of the insert, or from the corresponding part of another old ring gear, in the case of ensuring the pitch, cut out a relatively inferior gear teeth, and cut the gas at the butt joint Groove shape.

(3) Determine the orientation of the fixing hole of the insert, and fix it to the corresponding part of the ring gear. It is necessary to ensure the accuracy of the orientation of the fixed hole.

(4) In order to ensure the high strength of the weld and to accept large impact and vibration, the knot 507 electrode with a diameter of Φ4 mm is selected. The electrode should be baked at 250-350 °C for 1 h before application.

(5) The AX3500 DC arc welding machine is used for DC reverse welding, and the current is 130-140 A.

2, welding technology

(1) Preheating before welding, use 2 large gas welding guns to heat the welding surface to 200 °C.

(2) The tempering weld bead method is adopted, and the latter weld has a tempering effect on the previous weld, which is beneficial to eliminate the hardened structure of the previous weld.

(3) Due to the large groove, when welding the first weld, it should be welded slightly to reduce the melting width and reduce the carbon content of the steel. When welding, the welding rod is inclined by 15° forward, and it travels in a straight line. When collecting the arc, it is necessary to pay attention to fill the arc pit to avoid cracking of the arc pit. After welding, use a pointed hammer to hammer the weld and both ends, and relax the stress until the weld is full of pitting. Continue welding when the weld is to be cooled at 200 °C.

(4) After the first weld, the welding method of each weld is the same as that of the first pass. The welding rod can be slightly swayed. In order to avoid the occurrence of blowholes, do not swing too much.

(5) After welding, in order to eliminate the hardened structure and stress, the weld and the two ends are heated to 600-650 °C with oxyacetylene flame, and kept for 20 min, then cover the weld with asbestos, slaked lime powder or dry sand to make it slow. Cool to room temperature.

(6) Polish the weld with a polishing wheel, and the ring gear is finished.

3, the conclusion

The segmented insert technology is used to modify the ring gear, the technology is simple, the technical requirements are lower, the correction time is short, and the ring gear is modified to have high quality. The ring gear modified with the old inserts has a life expectancy of 1/3 of the new ring gear life, and the ring gear modified with the newly machined inserts has the same life expectancy and new ring gear life. This method can be used to repeat the insert on the ring gear, which has significant economic benefits.

Article from: Excavator gear accessories  www.boomiexim.com