Research On Characteristics Of Abrasive Suspension Slurry And General Extrusion Grinding Mechanism

With the rapid development of science and technology,higher and higher requirements are put forward for the micro-geometric accuracy and surface roughness of the surface of parts.In the fields of aviation,electronics,computers,automobile manufacturing,etc.,the requirements for machining precision and surface property becomes higher and higher,and the demands for slender hole precision finishing become more and more urgent.At present,some conventional finishing methods have their limitations.Many precision valve parts have special structural characteristics.For example,the aperture ratio of the spray hole of the injector nozzle is large and the flow coefficient and atomization requirements are very high.If a conventional finishing method is used,it is difficult to guarantee the grinding efficiency and grinding quality.The abrasive suspension flow machining technology can not only grind the micro-holes and cavities that are inaccessible,but also polish various complex profiles on the outer surface.In the aspect of flow consistency,the abrasive suspension flow machining has the advantages over conventional finishing methods.However,the current research on the grinding mechanism of abrasive suspension flow machining technology is not enough.The abrasive particles are easy to precipitate in the slurry and are unevenly distributed.The system design has problems such as flow detection is not accurate enough and delay in the control system,which results the grinding effect and quality are not ideal.This paper mainly proposes a new abrasive suspension slurry preparation method,which solves the problem of easy precipitation and uneven distribution of abrasive particles.In the extrusion grinding system,the back pressure is increased,and a new abrasive suspension flow machining method is proposed.Theoretically explored and mastered the rheological characteristics and flow field characteristics of the abrasive suspension slurry,carried out the numerical simulation of the flow field at the spray hole and studied the grinding performance.Firstly,the preparation technology of abrasive suspension slurry and its rheological properties is analyzed.According to the principle of rheology,the rheological model of abrasive suspension slurry is selected as power law model,and the abrasive particle distribution model of the abrasive suspension flow is established.Then,use fluid simulation software to accomplish the creation and meshing of the model with abrasive suspension flow machining.Through computational fluid dynamic simulation,the velocity of abrasive particle was simulated to provide a theoretical basis for abrasive suspension flow machining.The grinding mechanism of abrasive suspension flow is discussed,and the movement mode of the abrasive particles and the mechanical properties and movement characteristics in the slender hole are analyzed.Then,the grinding performance of abrasive suspension flow extrusion grinding was designed.Using self-prepared abrasive suspension slurry,select diameter of abrasive particle,abrasive concentration,grinding pressure(or pressure difference)and viscosity of abrasive suspension slurry and other grinding parameters to study the grinding performance of the injector nozzle.In order to obtain the best combination of grinding parameters for the abrasive suspension flow extrusion grinding,the orthogonal design method was introduced into the abrasive suspension flow extrusion grinding experiment.Take the flow increase rate of injector nozzle,flow dispersion rate and the roundness of the spray hole as the maximum value.Through linear regression analysis of the test results,the order of the influence of each grinding parameter on the grinding performance is obtained.Obtain the best grinding parameters to guide the subsequent mass production of hole-type parts,and provide technical support for the research and development of abrasive suspension flow extrusion grinding tools and the promotion of abrasive suspension flow technology.Finally,the abrasive suspension slurry is added to the outlet of the injector nozzle to form back pressure.Before grinding,the grinding pressure and back pressure are established on both sides of the spray hole.In the main grinding stage,the pressure difference is formed by increasing the grinding pressure.The establishment of back pressure at the outlet of the injector nozzle can not only eliminate the cavitation phenomenon in the spray hole,but also increase the number of effective abrasive particles.Through the experimental comparison under different pack pressure,increasing the back pressure can improve the Reynolds number of abrasive suspension flow in the spray hole,reduce the thickness of boundary layer,which is conducive to the stability of abrasive suspension flow,and improve the flow increase rate and grinding quality of the injector nozzle.