When inspecting the welding seam of the excavator arm side plate for corrosion and cracks, it is necessary to scrape off or polish the paint layer and rust on the surface 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 in the side plate of the excavator arm: including bubbles, slag inclusions and micro-cracks in the original weld itself. When the excavator is overloaded, micro-cracks will occur in the original weld and slowly expand: Welding rods during welding Cracks caused by inconsistency with the performance of the plate: Due to the large size of the excavator arm, it is difficult to adopt reliable and effective heating and insulation measures. The hardened area of the base material around the weld cannot be completely removed after welding, resulting in a decrease in the strength of the weld: Excavator During the operation, the vibration and impact are large, and the uneven stress on the weld seam causes the weld seam to crack.
2. Fix
Preparation work before welding: Use a hand grinding wheel to remove oil, paint, rust, etc. from the original weld cracks. Use a gouging machine to cut away the cracks in the welding seam to the body of the side plate, and clean the hardened area of the base metal that was previously welded. After planing, use an angle grinding wheel to smooth the incision (the inner interface is grinded to create a V-shaped groove). After cleaning and pink inspection, confirm that all cracks have been found and removed.
According to the existing maintenance conditions, select the Φ5mm model E5015 (J507) or E5016 (J506) electrode, bake it at 350℃ for 2 hours, and then insulate it at 100℃ to prevent the electrode from absorbing moisture. It can be taken as needed; the welding current is 190~ 230A. Due to the large thickness of the excavator side plate, the welded part should be preheated to 150~250℃ before welding; during the welding process, segmented, symmetrical, and backward methods can be used for welding; during the cooling process of the weld seam, welding should be continued Use a hand hammer to tap the weld metal to eliminate stress; when welding at the corners of the side plates, in order to avoid arc defects, welding should be performed continuously to improve the stress condition of the connection.
After welding, thoroughly remove spatter, welding slag, weld flash, etc., and the weld reinforcement shall not be greater than 2.5mm. Magnetic particle inspection is performed on the welds, and defects such as cracks are not allowed.
3． Measures to prevent weld corrosion
Thoroughly sand the welds, remove rust and apply anti-rust paint. At the excavation construction site, for existing rusted welds, manual rust removal can be selected based on the actual conditions of the excavation. The disadvantage is that the labor intensity of workers is high and the labor cost is high. Pickling can also be used to remove rust, that is, using organic acids as the method. The main base material is mixed with composite materials such as corrosion inhibitors, surfactants, rust removers, anti-rust agents and film-forming agents to prepare a pickling solution with rust removal, anti-rust and primer functions. Through cleaning, it can achieve 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 eliminating corrosive gases and moisture in a timely manner.