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61L1-3022
YASSIAN or Your's
Common surface defects of bucket teeth in construction machinery and their treatment methods
The following is a systematic summary of common surface defects of bucket teeth in construction machinery and their treatment methods, integrating key technologies in the casting, usage and repair processes:
I. Wear-related defects
Uneven wear at the tooth tip
Feature : The wear depth at the front part of the tooth tip is greater than that at the rear part, forming a "cutting edge depression".
Deal with :
Surfacing repair: Use J507 electrodes (GB/T 5117) for layer-by-layer surfacing, preheat above 100℃, and release stress by interlayer hammering.
Steel plate repair welding: Attach a 30mm thick steel plate to the worn area and fix it by welding at both ends to enhance the wear resistance.
Wear of the furrow in the transition zone of the tooth root
Feature : a groove greater than 2mm deep appears at the fillet of the tooth root.
Deal with :
Laser cladding: After shot peening and cleaning, a tungsten carbide coating is cladding with a hardness of ≥60 HRC.
Fillet regeneration: Grind off the fatigue layer and reprocess the transition arc with R≥0.4m.
(Diagram of the wear morphology and repair of the inserted bucket teeth)
Ii. Casting Defects
Sticky sand
Feature : quartz sand particles adhere to the surface of the casting, with a roughness Ra > 25μm.
Deal with :
Chemical cleaning: Soak in 40% hydrofluoric acid solution for 10 minutes, then rinse with high-pressure water (protective measures required);
Mechanical grinding: Sandblasting with steel shot until Ra≤12.5μm.
Stomata
Feature : Spherical holes with diameters ranging from 1 to 10mm exist on the surface or under the skin.
Prevention :
Optimized pouring: Use the bottom pouring ladle, control the flow rate of molten steel ≤0.5m/s, and avoid entrainment.
Molding sand control: The moisture content of coated sand should be ≤0.3%, and the calcination temperature should be 230±10℃.
(Insert the video of casting defect detection and cleaning operation)
Iii. Use Damage
Cracks and fractures
Feature : Radial cracks appear at the tooth tip or root, with a depth greater than 5mm.
Deal with :
Bevel welding: Make a 60° V-shaped bevel and repair it by argon arc welding with ER307 stainless steel wire.
Structural strengthening: Drill a Φ3mm anti-crack hole at the end of the crack to prevent expansion.
Installation surface deformation
Feature : The contact surface of the tooth seat collapses by more than 0.5mm, causing the bucket teeth to loosen.
Deal with :
Cold straightening: Use a hydraulic jack to apply reverse pressure to the deformed area for correction.
Wear-resistant plate mounting: After milling the base surface flat, weld NM400 wear-resistant steel plates.
(Insert typical damage maps and repair cases)
Iv. Standards for Remanufacturing and Repair
Defect type repairable determination conditions acceptance criteria after repair
The residual rate of worn tooth height is ≥60%, and the hardness of the surfacing layer is ≥55 HRC
The crack length is ≤ 1/3 of the tooth width and does not penetrate. Penetrant testing shows no linear display (ISO 3452)
The diameter of a single pore is ≤3mm and it is not dense, with a porosity of less than 2% (volume ratio).
Key tip :
Reusing techniques for limit washers: After clamping with grooved pliers and hammering to reduce the gap, the service life can be extended by five times.
Prohibited repair scenarios: The fillet R at the tooth root is less than 0.2m or there are reticular cracks in the base material.
Common surface defects of bucket teeth in construction machinery and their treatment methods
The following is a systematic summary of common surface defects of bucket teeth in construction machinery and their treatment methods, integrating key technologies in the casting, usage and repair processes:
I. Wear-related defects
Uneven wear at the tooth tip
Feature : The wear depth at the front part of the tooth tip is greater than that at the rear part, forming a "cutting edge depression".
Deal with :
Surfacing repair: Use J507 electrodes (GB/T 5117) for layer-by-layer surfacing, preheat above 100℃, and release stress by interlayer hammering.
Steel plate repair welding: Attach a 30mm thick steel plate to the worn area and fix it by welding at both ends to enhance the wear resistance.
Wear of the furrow in the transition zone of the tooth root
Feature : a groove greater than 2mm deep appears at the fillet of the tooth root.
Deal with :
Laser cladding: After shot peening and cleaning, a tungsten carbide coating is cladding with a hardness of ≥60 HRC.
Fillet regeneration: Grind off the fatigue layer and reprocess the transition arc with R≥0.4m.
(Diagram of the wear morphology and repair of the inserted bucket teeth)
Ii. Casting Defects
Sticky sand
Feature : quartz sand particles adhere to the surface of the casting, with a roughness Ra > 25μm.
Deal with :
Chemical cleaning: Soak in 40% hydrofluoric acid solution for 10 minutes, then rinse with high-pressure water (protective measures required);
Mechanical grinding: Sandblasting with steel shot until Ra≤12.5μm.
Stomata
Feature : Spherical holes with diameters ranging from 1 to 10mm exist on the surface or under the skin.
Prevention :
Optimized pouring: Use the bottom pouring ladle, control the flow rate of molten steel ≤0.5m/s, and avoid entrainment.
Molding sand control: The moisture content of coated sand should be ≤0.3%, and the calcination temperature should be 230±10℃.
(Insert the video of casting defect detection and cleaning operation)
Iii. Use Damage
Cracks and fractures
Feature : Radial cracks appear at the tooth tip or root, with a depth greater than 5mm.
Deal with :
Bevel welding: Make a 60° V-shaped bevel and repair it by argon arc welding with ER307 stainless steel wire.
Structural strengthening: Drill a Φ3mm anti-crack hole at the end of the crack to prevent expansion.
Installation surface deformation
Feature : The contact surface of the tooth seat collapses by more than 0.5mm, causing the bucket teeth to loosen.
Deal with :
Cold straightening: Use a hydraulic jack to apply reverse pressure to the deformed area for correction.
Wear-resistant plate mounting: After milling the base surface flat, weld NM400 wear-resistant steel plates.
(Insert typical damage maps and repair cases)
Iv. Standards for Remanufacturing and Repair
Defect type repairable determination conditions acceptance criteria after repair
The residual rate of worn tooth height is ≥60%, and the hardness of the surfacing layer is ≥55 HRC
The crack length is ≤ 1/3 of the tooth width and does not penetrate. Penetrant testing shows no linear display (ISO 3452)
The diameter of a single pore is ≤3mm and it is not dense, with a porosity of less than 2% (volume ratio).
Key tip :
Reusing techniques for limit washers: After clamping with grooved pliers and hammering to reduce the gap, the service life can be extended by five times.
Prohibited repair scenarios: The fillet R at the tooth root is less than 0.2m or there are reticular cracks in the base material.
