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Boom repair of excavators
Jan 14, 2019

When checking the rust crack of the welder side plate weld seam, it is necessary to scrape off or polish the weld surface paint layer, rust, and use a small hammer to lightly strike the weld seam. If necessary, use a magnifying glass to observe. Causes of cracks: Causes of cracks on the side plates of excavator booms: including air bubbles in the original weld itself.


Boom repair of excavators


When checking the rust crack of the welder side plate weld seam, it is necessary to scrape off or polish the weld surface paint layer, rust, and use a small hammer to lightly strike the weld seam. If necessary, use a magnifying glass to observe.


1. Causes of cracks


The cause of the crack on the boom side plate of the excavator: including the original weld itself, there are bubbles, slag inclusions and tiny cracks. When the excavator is overloaded, the original weld will produce tiny cracks and slowly expand: the welding rod Cracks inconsistent with the performance of the plate: Due to the large volume of the boom of the excavator, it is difficult to adopt reliable and effective heating and insulation measures. After the welding, the hardened area of the base material around the weld is not completely removed, resulting in a decrease in weld strength: excavator The vibration impact is large during the operation, and the weld is cracked due to uneven force at the weld.


2. Repair method


Preparation before welding: Remove the oil, paint, rust, etc. from the cracks in the original weld by hand with a grinding wheel. The weld crack is cut by a gouging machine, cut into the body of the side plate, and the hardened area of the base material of the previous welding is removed. After the planing, use the angle grinding wheel to smooth the incision (the inner interface is polished to the V-shaped groove). After cleaning and pink inspection, confirm that the cracks have all been found and cleaned.


According to the existing maintenance conditions, the Φ5mm model is E5015 (J507) or E5016 (J506) electrode, baked at 350 °C for 2h, and then insulated at 100 °C to prevent the electrode from moisture absorption, with the use; welding current 190 ~ 230A. Due to the large thickness of the side plate of the excavator, the welded part should be preheated to 150-250 °C before welding; in the welding process, the welding can be carried out by segmentation, symmetry and retreat; in the process of cooling the weld, it should be used continuously. The hammer is used to strike the weld metal to eliminate the stress. When welding at the corner of the side plate, in order to avoid or cause arcing defects, continuous welding is required to improve the stress at the joint.


After the welding is completed, the spatter, welding slag and welding bead are completely removed, and the weld height must not exceed 2.5 mm. Magnetic powder inspection is performed on the weld, and defects such as cracks are not allowed.


3. Anti-weld corrosion measures


The weld is thoroughly ground, rusted and coated with anti-rust paint. At the excavation construction site, for the existing corroded welds, the manual derusting can be selected according to the actual situation. The disadvantage is that the labor intensity of the workers is large and the labor costs are high; the pickling and derusting methods can also be adopted, that is, the organic acid is used. Mainly based on composite materials such as corrosion inhibitors, surfactants, rust removers, rust inhibitors and film formers, which are prepared into a pickling solution with rust, rust and primer functions. Descaling and rust prevention purposes.


In addition, during use, care should be taken to keep the excavator in a clean and dry environment, keep it well ventilated, and remove aggressive gases and moisture in time.


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