Cause analysis of premature oil leakage in the gui

Analysis on the causes of premature oil leakage in the guide sleeve of the pressure cylinder of the rotary drilling rig

Abstract: the causes of premature oil leakage and seal damage in the guide sleeve of the pressure cylinder of the rotary drilling rig are analyzed and studied, and the improvement measures are put forward to improve the reliability of the pressure cylinder and prolong the time of trouble free operation of the whole machine

in recent years, the national construction management department has gradually realized the many advantages of rotary drilling machines. Through the use and practice of construction departments all over the country, the rotary drilling machines, a modern foundation construction equipment integrating high efficiency, energy conservation and environmental protection, have been accepted by more and more users. Its construction coverage has gradually penetrated from the original large-scale hydropower and culvert infrastructure projects to the buildings, halls, museums and stations of railways, highways and civil facilities. With (5) the implementation of the characteristic new material production and utilization platform construction project and the steady improvement of the manufacturing quality of domestic drilling rigs, this kind of equipment will surely benefit China for the future

during the actual use of the rotary drilling machine, some drilling machines appeared: oil leakage occurred at the cylinder head of the power head pressure cylinder shortly after the construction. With the extension of service time, the oil film on the piston rod gradually thickened and formed an oil flow, and then serious oil leakage led to shutdown and maintenance. A domestic drilling rig constructed on the Qinghai Tibet Railway several years ago even suffered serious consequences of damage to the front hinge of the pressurized oil cylinder. The exposure of this fact has indeed sounded an alarm for many domestic drilling rig manufacturers. If this defect is not completely solved, the complete absence of VOC in the water-based adhesive will directly affect the reliability and sales volume of domestic drilling rigs, and the market of Huaxia rotary drilling rigs will also be ceded to foreign manufacturers

after observation, the assembly relationship between the power head, pressure cylinder and drill mast of the rotary drilling rig is as follows: the pressure cylinder is fixed on the front end face of the drill mast (in the working state of the rotary drilling rig), the head of its cylinder is hinged in the support lug of the front cover plate of the drill mast, the tail of the cylinder is floating connected with the other support lug of the front cover plate of the drill mast, and the head of the cylinder piston rod is connected with the support lug of the power head through a pin shaft (see Figure 1), The sliding block supports on both sides of the power head are buckled on the guide rail of the drill mast, and there are sliding blocks between them (see Figure 2). During the operation of rotary drilling rig, the pressurized oil cylinder pushes the power head to move on the drill mast, and the slider metal separator has a certain limit on the conveying speed of the detected objects. With the power head moving up and down along the surface of the guide rail of the drill mast, the swing amount of the power head in the whole movement process is mainly determined by the gap between the slider and the guide rail of the drill mast

during operation, as long as the power head moves, the friction between the sliding block and the guide rail of the drilling mast will occur. With the wear of the slider, the swing amount of the power head will gradually increase. Within the allowable wear range of the slider, the swing amount in the left and right directions (see Figure 2) is compensated by the gap between the mounting ear of the piston rod head of the pressure cylinder and the supporting ear of the power head cylinder, and the lateral additional force generated is borne by the outer side of the guide rails on both sides of the drill mast. However, in Figure 2, there is no place to release the swing amount caused by the wear of the sliding blocks in the up and down directions of the drill mast guide rail. The additional force generated by the power head in the fore-and-aft direction (drilling rig operation state) can only be borne by the lower slider of the power head and the head ear of the piston rod of the pressure cylinder. If the piston rod of the pressure cylinder extends longer, due to the deformation of the piston rod, its force is mainly borne by the upper and lower sliding blocks of the power head, which is balanced with the force received by the guide rail of the drill mast

with the wear of the slider, the piston rod will receive additional bending load perpendicular to its axis (mainly caused by the additional action in the front and rear directions during the operation of the drilling rig) during the pressure application of the pressure cylinder to the drill pipe, and this action will decrease with the increase of the extension length of the piston rod. When the pressurized cylinder is pressurized in the fully retracted state, the additional force acting on the cylinder guide sleeve and the front hinge point is the largest. The frequent occurrence of such working conditions is very easy to cause uneven loading and wear of the guide sleeve seal. Sometimes in order to reduce the weight, aluminum alloy and other non-ferrous metals and special metals are also used, which cannot guarantee the ideal service life of the pressurized cylinder guide sleeve seal, and even the piston rod "roughens" and "gnaws", This will further cause damage to the sealing elements. If the additional force exceeds the limit load that the front hinge of the pressurized cylinder can bear, the damage of the hinge is inevitable

after finding the cause of premature oil leakage at the cylinder head of the pressure cylinder, the corresponding countermeasures were taken in the design process of the new product RD12 rotary drilling machine. In order to make up for the swing amount caused by the wear of the power head by the slider in the upper and lower directions of the guide rail (see Figure 2), the supporting lug of the power head cylinder is designed into a long circular structure from the original circular hole, and the length of the hole is determined according to the allowable wear amount of the slider, so as to completely eliminate the swing caused by the wear of the slider in the front and rear directions of the guide rail of the drilling mast during the operation of the drilling rig, resulting in the additional load on the guide sleeve, front hinge point and piston rod of the pressurized oil cylinder. The improved structure is shown in Figure 3