Research on the Surface Roughness of Mold Material in Spdt
|School||Harbin Institute of Technology|
|Course||Mechanical Manufacturing and Automation|
|Keywords||SPDT surface roughness die material swelling effect relative vibration|
Recently, there is a growing demand for the optics with high quality including spherical aspherical and microstructure optics. An important part of them are replicated through injection molding using precision mold. The surface quality of the mold largely affects the surface quality of the optics. Surface roughness is an important index to character the product’s quality. Therefore, the prediction and control of surface roughness in single point diamond turning (SPDT) was detailedly researched in this thesis on the basis of previous studies. The main research work consists of the following three parts:Firstly, representative prediction models and study methods of surface roughness in SPDT were studied and compared. Through theoretical analysis and experimental research, some deficiencies and issues existing in the previous models were found.Secondly, according to the issues in the previous models, the influence of material and machining parameters on the relative vibration between tool and work-piece was studied. It can be concluded that material feature and spindle speed are main factors to influence the relative tool-workpiece vibration. Moreover, the causes of swelling effect and its influencing factors were analyzed where the effect of cutting parameters and material property on the swelling proportion was paid more attention to. The results indicate that material property and spindle speed are the main factors to affect swelling proportion and the effect of swelling effect on the surface roughness.Finally, on the basis of above conclusions, a new prediction model of surface roughness was presented. Experiments were carried out to verify the prediction model. The experimental results show that the new model is capable of realizing the prediction and control of surface roughness very well and the model has better simulation of the real machining process than the previous one, as the model took into account the material induced vibration and the dynamic change of the machine tool caused by the spindle speed’s change. Towards typical die materials, the mapping relationship was established between machining conditions and surface roughness of work-piece. The model will realize the prediction of surface roughness according to machining conditions and the selection of cutting parameters according to the requirement of surface roughness.