Study On Flow Field And Convective Heat Transfer Characteristics In Grinding Zone Of Large Spiral Angle Flow Disturbance Groove Wheel

Precision grinding is an important process for forming high quality functional surfaces of high performance alloys,but due to the extremely high specific removal energy and heat generation rate of the grinding process and the high mechanical properties of high performance alloys,the low heat transfer efficiency in the grinding arc of conventional common grinding wheels makes it extremely easy to generate local high temperatures and grinding burns,making it difficult to achieve a high quality and efficient grinding process.From the requirement of enhancing the heat transfer property of the grinding and reducing thermal damage to the machined surface,a fluted grinding wheel with a large spiral angle(β>85°)has unique advantages.The advantage is that the grinding arc has a "well-defined" contact zone and a heat transfer zone,where the energy input during the grinding process is converted into heat in the contact zone of the grinding grain/workpiece and the heat transfer zone has a greater capacity for transport of the grinding fluid.In addition,by creating flow disturbance structures at the bottom of the groove,the flow disturbance structures does not come into contact with the workpiece,but allows the grinding fluid to create a high turbulence heat transfer channel flow field inside the grinding arc driven by the flow disturbance structures,Thus effectively increases the heat transfer property of the grinding.Nevertheless,the heat transfer property of the grinding arc of the large spiral-angle disturbed groove grinding wheel is influenced by various factors,such as the distribution characteristics of the air barrier flow field and return flow field around the grinding wheel,the characteristics of the gas-liquid two-phase flow field in the grinding zone,etc.The elements influencing convective heat transfer coefficient in the heat transfer channel of the grinding zone also need to be investigated in depth.Therefore,this paper builds a simulation model of flow field in the flow field model of grinding zone and convective heat transfer coefficient model of heat transfer thoroughfare for a large spiral angle disturbed groove grinding wheel,and the change of spiral groove arguments and the change of grinding arguments on the flow field in the grinding area were investigated and the distribution of CHTC of grinding fluid in the heat transfer thoroughfare were investigated.In this regard,the following work has been carried out in this paper:(1)Based on the grinding wheel structural parameters and grinding process parameters,a parametrically driven accurate airflow analysis model for the grinding zone of large spiral angle fluted grinding wheels was established to obtain the velocity distribution characteristics of the airflow field in the wedge area,the return flow distribution characteristics,and the distribution characteristics of the airflow field pressure along the distance from characterization along the grinding wheel width direction reveals a complex mechanism of the effect of spiral groove arguments and grinding arguments on the characteristics of the airflow field in the grinding zone.(2)A numerical model of the gas-liquid two-phase flow field in the grinding zone was created on the basis of the airflow field in the grinding zone of a large spiral angle fluted grinding wheel,obtain the grinding fluid flow trajectory and the effective grinding fluid flow rate in the grinding arc zone.In addition,a new type of grinding wheel structure with flow disturbance structures was developed at the bottom of the spiral groove to form a disturbed flow groove,and its influence on the grinding fluid flow state and the effective grinding fluid flow rate was investigated.(3)Based on the gas-liquid two-phase flow field in the grinding arc of a large spiral angle disturbed groove grinding wheel of a large spiral angle disturbed groove grinding wheel,the convective heat transfer coefficient distribution of the grinding fluid acting on the workpiece surface in the heat transfer channel with/without the flow disturbance structures was established,the effect aspect of convective heat transfer coefficient is found,and reveal the effect aspect of the flow disturbance structures on the convective heat transfer characteristics of the grinding fluid in the heat transfer channel.(4)Based on the theoretical study of the flow field and convective heat transfer characteristics in the grinding zone,experiments were conducted to measure the flow field of the air barrier layer and the velocity of the return flow field in the grinding zone under dry grinding conditions,to study the relationship between the grinding wheel structure parameters and grinding process parameters and the velocity of the air flow field,and to further explain the necessity of preparing flow disturbance structures at the bottom of the groove;under wet grinding conditions,the metallographic organization of the inter-slot area of the workpiece cross-section was observed,and the distribution characteristics of the heat-affected layer under different parameters were compared and analyzed.Under the wet grinding conditions,the metallographic organization of the inter-slot region of the workpiece cross-section was observed,and the distribution characteristics of the heat-affected layer generated under different parameters were compared and analyzed to evaluate the heat transfer performance of the grinding wheel,which verified the feasibility and validity of the flow field analysis model and convective heat transfer coefficient distribution model created in this paper.