Study On Preparation Technology And Cutting Performance Of Engine Cylinder Liner By Centrifugal Casting

The cylinder liner is a core part of the engine.Because of the advantages of simple process and high production efficiency,the centrifugal casting process is adopted to produce cylinder liners.In this paper,the cylinder liner produced by centrifugal casting has been used as the research object.According to the present situation,it is necessary to carry out targeted research for the cylinder liners of two different materials.And the study includes the centrifugal casting process of Al-alloy cylinder liners and machinability of gray cast iron cylinder liner.The main contents and achievements of this paper are as follows:1.Apply the centrifugal casting process to the preparation of hypereutectic Al-18% Si alloy cylinder liners.The preparation technology of cylinder liner was studied emphatically,including the smelting process of aluminum alloy and centrifugal casting process.By changing the rotational rate of the centrifugal casting,study the segregation case of primary silicon of Al-18%Si alloy at different acceleration field,material microstructure and hardness.Combined with numerical simulation results,try to get aluminum alloy cylinder liner with excellent casting performance and outstanding mechanical properties.The relevant experimental conclusions are as follows:(1)With the increase of centrifugal speed,the primary Si of the outer layer gradually converges to the inner layer.When the rotational speed reaches 1300 rpm,the inner layer of the casting begins to form the primary silicon rich layer.And the faster rate,the more intense exercise,the collision with each other leads to that the massive primary silicon was fractured.It helps refine the primary silicon.When the rate reaches 1600 rpm,the volume fraction of the primary silicon is the highest,it is 32.47%.The size is also the smallest,about 35?m.(2)Under the experimental conditions,considering the casting performance and mechanical properties of the casting,the centrifugal speed of 1300 rpm,the mold temperature of 300? and the pouring temperature of 720? are the best production process parameters.At this time,it is possible to obtain Al-18 Si alloy cylinder liner with excellent casting performance,and its primary Si is of gradient distribution.The inner surface's hardness of the cylinder liner is 118 HB.2.Study on the cutting performance of gray cast iron cylinder liner.The cutting performance of four sets of gray cast iron cylinder was measured.The influence of graphite and pearlite matrix on mechanical properties and cutting performance of gray cast iron was studied.The purpose of this study was to find out the influence of microstructure on the cutting performance and mechanical properties of gray cast iron.The conclusions are as follows:(1)Under the experimental conditions,the use of calcium silicate aluminum alloy processing,centrifugal speed at 1700 rpm,the cutting performance of the cylinder liner is the best.(2)The effect of pearlite matrix on the cutting performance of gray cast iron is mainly reflected in two aspects: Firstly,the size of the flakes spacing,the greater the spacing between the flakes,the better the cutting performance;Secondly,uniformity of the matrix organization,uneven flakes spacing will aggravate the tool wear,uniform tissue morphology is conducive to cutting.(3)The graphite in gray cast iron is conducive to improving its cutting performance.On the one hand,the presence of graphite will reduce the plastic deformation resistance of the matrix.On the other hand,graphite itself is a good lubricant,not only to lubricate and is conducive to chip breaking.Flake A-type graphite than the dot-like D-type graphite is more conducive to cutting tools,the higher the graphite content,the smaller the size of graphite,the more curved shape,the better cutting performance.(4)At the same time with excellent mechanical properties and cutting performance,the organization conditions of gray cast iron should be: There are fine,curved,disordered and evenly distributed flake graphite structures.Meanwhile,the pearlite matrix has a small and uniform flakes spacing.