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Study On Mechanical Properties Of Oil-free Lubricating Friction Pair Of Reciprocating Compressor

Posted on:2020-03-05Degree:MasterType:Thesis
Country:ChinaCandidate:R DingFull Text:PDF
GTID:2392330572472081Subject:Mechanical engineering
Abstract/Summary:PDF Full Text Request
The piston ring is made of self-lubricating material,which is a key component of oil-free lubricating compressor.Its working stability will directly affect a series of indexes such as reliability and emission of compressor.The piston ring filled with self-lubricating material has many disadvantages,such as large mechanical load deformation,small thermal conductivity and large linear expansion coefficient,which bring many difficulties in the installation process of piston ring.The side clearance is too small,the piston ring will be stuck in the ring groove after thermal expansion;the side clearance is too large,the piston ring will be impacted by the ring groove.The back clearance is too small,the piston ring is easy to contact with the bottom of ring groove;the back clearance is too large,this would permit air to enter,the sealing performance of piston ring will be broken.Therefore,research on the reasonable mounting clearance of piston ring is helpful to improve the service life of piston ring and the performance of compressor.In this paper,the piston ring of oil-free lubricating compressor is taken as the research object,and the simulation model is established by using the ANSYS software.Firstly,the finite element simulation of piston ring under the gas pressure is carried out,the effect of gas pressure on piston ring clearance is studied.Secondly,the finite element simulation of the piston ring under the temperature load is carried out,and the temperature field distribution,thermal stress and thermal strain cloud diagram of piston ring are analyzed,the effect of temperature load on piston ring clearance is studied.Thirdly,the gas pressure and the temperature field are respectively loaded on the boundary of the piston ring in the form of a "pressure load" and a "thermal load" to perform iterative calculation,and the thermal mechanical coupling analysis of the piston ring is realized.in the coupling field,the piston ring is simulated and calculated by using the ANSYS secondary development tool—The APDL parametric language.the reasonable installation clearance of the piston ring is predicted,and the prediction result and the existing empirical formula are compared,and the rationality of the empirical formula is verified.The results show that:1)Under gas pressure,the axial maximum deformation of piston ring is 0.0206mm,the radial maximum deformation is 0.0112mm,and the circumferential maximum deformation is 1.185 mm.The above results are quite disparity from the installation clearance given in the empirical formula,which indicates that the gas pressure has little effect on the mounting clearance of piston rings.2)Under temperature load,the maximum axial deformation of piston ring is 0.208 mm,the maximum radial displacement is 0.172 mm,and the maximum circumferential deformation is 6.52 mm,The above results are close to the installation clearance given in the previous empirical formula,indicating that temperature is the main factor affecting the mounting clearance of piston ring.3)Under the coupling field,the axial deformation of piston ring has a certain linear relationship with the height of piston ring,and the proportional coefficient is about 2.6%to 3%.The radial deformation of piston ring has a certain linear relationship with the thickness of piston ring,and the proportional coefficient is about 1.4%to 1.7%.The circumferential deformation has a certain linear relationship with the outer diameter of piston ring,and the proportional coefficient is about 2.9%to 3.4%.For the selection of side clearance,the range of piston ring side clearance is predicted to be(2.6-3)%b(b is axial height of piston ring).This result is close to the existing empirical formula,which verifies the rationality of the empirical formula.For the selection of the back clearance,there is no empirical formula at present.In this paper,it is predicted that the back clearance range of piston ring is(1.4-1.7)%c(c is the radial thickness of piston ring).For the selection of the opening clearance of the open piston ring,the range of the opening clearance is predicted to be(2.8-3.2)%D(D is the outer diameter of the piston ring).This result is basically in agreement with the empirical formula,and the rationality of the empirical formula is verified.The above results provide a theoretical basis for the selection of piston ring mounting clearance.It would be of guiding significance to the design of piston ring.
Keywords/Search Tags:oil-free lubricating compressor, piston ring, clearance, finite element, coupling analysis
PDF Full Text Request
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