What is the reason for abnormal fracture of shank adapter?
The shank adapter is a key part of the hydraulic rock drill for transmitting rotary and impact energy. It bears the complex loads transmitted by the impact piston and rotary motor of the rock drill during operation. The typical failure of the shank adapter is usually abnormal fracture. Generally, its working time is less than 10 shifts, and the shank adapter breaks at the root or thread of the thread.
Failure analysis of abnormal fracture of the shank adapter
Usage and maintenance issues
(1) The impact generated during the operation of the rock drill causes the connecting bolts between the rock drill and the mounting plate to loosen, causing the rock drill to swing during operation.
(2) The shank adapter guide sleeve is not replaced in time after the inner hole wear exceeds the standard, resulting in excessive gap between the rock drill and the guide sleeve, causing the front end of the shank adapter to shake during the operation of the rock drill.
(3) The rock drill is not lubricated sufficiently, so that the shank adapter cannot be effectively lubricated and cooled during rock drilling, the shank adapter temperature is too high, and the strength is reduced.
(4) The propulsion pressure of the rock drill does not match the impact pressure, causing the rock drill to produce empty strikes, and the shank adapter bears a large unnecessary impact load.
(5) The rock drill is not properly installed on the propulsion beam, so that the center line of the shank adapter is not coaxial with the center of the front and middle drill support holes, causing the shank adapter to be subjected to additional radial force.
Preventive measures for abnormal fracture of the shank adapter
(1) Before starting each shift, check the air lubricating oil spraying of the machine head and observe whether the oil film on the shank adapter is uniform. Drilling can only be started after it meets the lubrication requirements.
(2) Check the connection between the rock drill mounting bolts and the rock drill mounting seat every 40 impact hours of work. The bolt torque should be normal, the center of the shank adapter should be coaxial with the center of the front and middle drill support holes, and the rock drill empty propulsion pressure should be less than 3 MPa.
(3) During the drilling process, adjust the propulsion pressure in time according to the rock conditions. Reduce the propulsion pressure when the rock hardness is high and increase the propulsion pressure when the hardness is low to avoid empty drilling of the rock drill.
(4) Check the inner diameter of the shank adapter guide sleeve regularly and replace the shank adapter guide sleeve every 800 impact hours of work to avoid the shank adapter from swinging due to excessive wear of the guide sleeve inner diameter.
