Hydraulic machinery: Causes and analysis of hydraulic hammer piston damage
1、 Main forms of damage:
1. Scratch on working surface
2. Break
3. Working end depression
4. Cracks occur around the depression at the working end
5. Working end cracking
2、 Cause of damage:
1. Causes of scratch on working surface
A. Low surface hardness
B. Impurities mixed in hydraulic oil
C. The clearance of drill rod guide sleeve (upper and lower bushings) is too large, and the guide sleeve fails. During the operation of the drill rod, the axis tilts. When the piston strikes the drill rod, it receives an inclined reaction force, which can decompose an axial force and a radial force. The radial force can push the piston to one side, the original clearance disappears, the oil film is damaged, and dry friction is formed between the oil cylinder and the piston surface, resulting in scratches on the piston surface.
2. Break
The piston material produces cracks during forging or heat treatment. Under the action of alternating stress, the cracks expand until they break.
3. The working surface is concave, and cracks and cracks occur around the concave.
A. Carburized low-alloy steel piston is the internal cause of impact end face depression, crack and crack. Through a large number of investigations, we found that carburized low-alloy steel piston fails due to impact depression, crack and crack.
B. The hardness difference between the hit part of the piston and the hit part of the drill rod should be appropriate. Through years of practice and technical exchange with domestic and foreign suppliers, we found that they should have a more appropriate hardness and the difference should be appropriate.