After the compressor stopped and replaced the three-stage inlet air valve, it was put into operation for less than 2 hours. There was an abnormal noise in one section of the cylinder, and the main engine current increased from 135A to 140A. The noise in the cylinder became louder, and at the same time, the vibration of the first section of the cylinder intensified. After the compressor stopped and replaced the three-stage inlet air valve, it was put into operation for less than 2 hours. There was an abnormal noise in one section of the cylinder, and the main engine current increased from 135A to 140A. The noise in the cylinder became louder, and at the same time, the vibration of the first section of the cylinder intensified. Upon inspection of the piston, it was found that the PTFE support ring was misaligned, forming a 30 degree angle with the center of the piston; Among the three piston rings (made of JT20-40B material), one broke and the other two were all trapped in the ring groove as dead rings; The piston ring groove is filled with melted aluminum sheets, and there are also some melted aluminum sheets in the support ring groove; The upper part of the front half piston has significant wear, with a depth of 6mm when viewed from the end face, and a fan-shaped distribution of about 200mm along the axial direction before terminating. Due to the wear of the piston body located directly above the piston and having no impact on axial balance, only the cylinder depression area is deburred; The front half of the piston end face is rough machined on the C650 lathe, with a feed rate of about 1mm, mainly to solve the deformation of the edge area caused by high temperature and restore the axial balance of the piston body. The rib is perpendicular to the sliding surface, which is conducive to scraping oil and creating a very thin oil film on the sliding surface. When the piston rod returns, the oil film is fully recovered due to the angular effect of the sliding ring, preventing lubricating oil from reaching the cylinder and achieving oil-free lubrication. On the other hand, the extremely thin oil film on the low-pressure side of the packing has a high viscosity, making it difficult to enter the high-pressure cylinder end and providing auxiliary sealing performance.

Oil free lubrication compressors require packing seals to have certain elastic-plastic, followability, chemical stability, impermeability, self-lubricating, and high temperature resistance to ensure sealing. Therefore, the design of packing seals is crucial for achieving oil-free lubrication. Secondly, remove the bypass valve, control air pipe, pressure reducing valve, and suction valve of the original air compressor and plug them with plugs. Connect the original main air pipe to the lower part of the main engine of the screw air compressor. Finally, add a pipe and ball valve to the modified main air duct (i.e. the lower part of the load reduction valve), with its outlet placed on the left side of the dry drilling rig, so that when operating the air compressor dry, first open the ball valve, then push the load reduction push rod, and close the ball valve when the air pressure rises. This also facilitates future observation of oil carried by the wind.