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Excavator slewing bearing repair method

10-12, 2022 / in Bearing Knowledge / by LDB
During the operation of the excavator, the rotating ring gear bears a large impact load. When the excavator is inclined, the stress state is even more unfavorable. Generally, when the excavator runs for about 350,000 hours, the teeth of the rotating ring gear may be crushed or broken. Practice has proved that the use of insert welding to repair the rotary ring gear is not only simple and fast, but also ensures the performance of the whole machine.

1. Preparation before welding

Excavator slewing bearing

(1) According to the damage of the ring gear, determine the position of the fixing hole and the damaged segment to be replaced, and then cut off the segment of the tooth to be replaced with gas cutting.

(2) According to the part of the ring gear that needs to be repaired, process the insert, or from the corresponding part of another old ring gear, under the condition of ensuring the pitch, cut out a relatively intact gear tooth, and cut out the butt joint. Bevel shape.

(3) Determine the position of the fixing hole of the insert, and punch it to fix it on the corresponding part of the ring gear. Pay attention to the accuracy of the position of the fixing hole.

(4) In order to ensure that the welding seam has high strength and can withstand large shocks and vibrations, a junction 507 electrode with a diameter of Φ4 mm is selected.

(5) Using AX3500 DC arc welding machine DC reverse welding, the current is 130 ~ 140 A.

2. Welding process

Excavator slewing bearing

(1) Preheat before welding, use 2 large gas welding torches to heat the welding surface to about 200 ℃.

(2) Using the tempering bead method, the latter weld has a tempering effect on the former weld, which is beneficial to eliminate the hardened structure produced by the former weld.

(3) Due to the large groove, when welding the first weld, it should be welded slightly thinner to reduce the melting width and reduce the carbon content of the steel. When welding, the electrode should be inclined forward by about 15° and move straight forward. When closing the arc, pay attention to filling the arc crater to avoid arc crater cracks. After welding, quickly hammer the weld and both sides with a pointed hammer to relax the stress until the weld appears densely covered with pits. Continue welding when the weld is cooled to about 200 °C.

(4) The welding method of each weld after the first weld is the same as the first one, and the electrode can be slightly swayed. In order to avoid pores, do not swing too much.

(5) In order to eliminate the hardened structure and stress after welding, heat the weld and both sides to about 600-650 °C with an oxyacetylene flame, keep the temperature for 20 minutes, and then cover the weld with asbestos, slaked lime powder or dry sand to make it Cool slowly to room temperature.

(6) Grind and trim the weld with a polishing grinding wheel, and the repair of the ring gear is completed.

In summary, this is the whole introduction of the repair method of the excavator slewing bearing. If you have any questions during the actual repair process, you can contact us at any time.
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