When checking the rust cracks of the welding seam on the side plate of the excavator arm, it is necessary to scrape off or polish the surface paint layer and rust of the welding seam. When observing, tap the welding seam with a small hammer, and use a magnifying glass to observe if necessary.

1. Cause of cracks

Reasons for cracks on the side plate of the excavator arm: including bubbles, slag inclusions and tiny cracks in the original weld. When the excavator is overloaded, tiny cracks will occur at the original weld and slowly expand: the welding rod Cracks that do not match the performance of the plate: Due to the large size of the excavator arm, it is difficult to adopt reliable and effective heating and heat preservation measures. During the operation, the vibration and impact are relatively large, and the uneven force at the welding seam causes the welding seam to crack.

2. Repair method

Preparation work before welding: remove oil, paint, rust, etc. from the original weld crack with a hand grinding wheel. Use a gouging machine to cut off the weld crack, plan to the body of the side plate, and remove the hardened area of the base metal that was welded in the past. After planing, use an angle grinding wheel to smooth the incision (the inner interface is ground to form a V-shaped groove), after cleaning and pink inspection, confirm that all cracks have been found and removed.

According to the existing maintenance conditions, choose Φ5mm type E5015 (J507) or E5016 (J506) electrode, bake at 350℃ for 2 hours, and then keep at 100℃ to prevent the electrode from absorbing moisture. 230A. Due to the large thickness of the side plate of the excavator, the welded part should be preheated to 150 ~ 250 ℃ before welding; during the welding process, the segmented, symmetrical and backward method can be used for welding; during the cooling process of the weld, it should be continuously used The hand hammer strikes the weld metal to relieve stress; when welding at the corner of the side plate, in order to avoid arc defects, continuous welding should be performed to improve the stress condition of the joint.

After welding, thoroughly remove the spatter, welding slag and welding flash, and the residual height of the welding seam shall not be greater than 2.5mm. Magnetic particle inspection is carried out on the weld, and defects such as cracks are not allowed.

3. Weld corrosion prevention measures

Thoroughly sand, derust and coat welds with anti-rust paint. At the excavation construction site, for the existing rusted welds, manual rust removal can be selected according to the actual situation. The disadvantage is that the labor intensity of workers is high and the labor cost is high; The main base is mixed with composite materials such as corrosion inhibitor, surface active agent, rust remover, rust inhibitor and film-forming agent to prepare a pickling solution with the functions of rust removal, rust prevention and primer. Rust removal and rust prevention purposes.

In addition, during use, attention should also be paid to keeping the excavator in a clean and dry environment, maintaining good ventilation, and removing corrosive gases and moisture in time.