Oil leakage occurs at the joint surface of the oil separation pipe and the hydraulic cylinder in the hydraulic system. Because of the more oil loss per leak and leakage, the downtime is longer, which seriously affects the normal production operation of the vertical roller mill. Therefore, this paper mainly deals with the causes of seal failure and damage, and analyzes the causes and proposes solutions.
In the connecting pipeline between the hydraulic cylinder and the accumulator, in order to realize the quick buffering effect of the accumulator on the hydraulic cylinder, a larger diameter pipe joint is designed in an appropriate place. One end of the oil separation pipe is connected with a high-pressure hose, and the other end is welded with a flange. The flange and the hydraulic cylinder flange are bolted, and the two flanges are sealed by an end O-ring. In the initial stage of oil leakage, it is first suspected that the quality of the O-ring is poor and the O-ring installation is not standardized. After adopting the measures of replacing the high-quality imported sealing ring and improving the installation process, the vertical roller mill was normally operated for several days, and the O-ring was damaged again. Therefore, we need to further analyze other reasons for the problem.
The high-pressure hose connecting the hydraulic cylinder and the fixed oil pipe will generate a large external tension of the pipeline under the action of a high pressure of the hydraulic system (usually about 12 MPa). When the hydraulic cylinder is working, it is slightly oscillated around the lower pin shaft. Under the tension of the above pipeline tension, the end face sealing form at the joint surface of the oil distribution pipe flange and the hydraulic cylinder flange is easy to fail and cause oil leakage. At the same time, the vertical grinding vibration causes the impact, which causes the two flange connecting bolts to loosen. If it is loosened, it will not be tightened in time, which also increases the chance of leaking hydraulic oil outward.
Add a flanged joint with an axial seal. The specific technical measures are as follows:
(1) Firstly, expand the inner hole of the flange and the flange end of the hydraulic cylinder. The diameter of the flange is the same as the inner diameter of the oil distribution pipe. When expanding the hole, it is necessary to ensure that the enlarged inner hole reaches a certain cylindricity and verticality. Then, a flange joint is welded in the flange cavity, and the small end portion of the flange joint is provided with an axial seal groove matched with the size of the O-ring, and the outer diameter of the small end is the same as the inner diameter of the hydraulic cylinder flange, which ensures The two joint surfaces can be tightly compacted, and the outer diameter of the large end is 1~3 mm smaller than the inner diameter of the newly reamed hole of the flange 1 so as to be fitted into the flange joint. Flange pipe is easy to use, and ordinary steel pipe can be used.
(2) To ensure a good sealing effect of the axial seal of the flanged joint, in addition to the requirement that the inner bore of the flange 1 expands to meet certain cylindricity and verticality requirements, is there a better set of installation process? . Because the welding of the flanged joint and the flange 1 needs to be completed on site, the coaxiality of the flanged joint and the hydraulic cylinder flange is difficult to ensure, so we designed a special welding positioning tool to complete the installation work. The positioning tool limits five degrees of freedom according to the six-point positioning principle, and there is no limit to the degree of freedom of rotation in the axial direction. The positioning tool can be made of ordinary steel plate, and has a through hole with a triangular spline key groove shape at the center, and four circular holes at the edge, and the shape, the position size and the four fastenings on the flange 1 are used. The round holes are identical.
After the test, the improved hydraulic pipeline has no oil leakage, the vertical roller mill has a good running effect, and the double seal structure effectively adapts to the complicated working environment.