| Carbon fiber reinforced composites(CFRP)is concerned for its light weight,high modulus,excellent specific strength and many other advantages.Its application scope has expanded from aerospace to the present automobile manufacture,sports goods,electronic products and so on.However,the study on the preparation of CFRP is mainly focused on the conventional holes with a diameter of 5mm or more.There are few studies on the micro hole machining of 3mm and below 3mm.And a few of people work on the process parameters and the mechanism of small hole machining.Therefore,it is necessary to develope the theoretical and experimental research on the cutting force and process parameters of the small hole machining of CFRP.The main contents of the paper are divided into the following sections:(1)Through studying the micro morphology and surface roughness of the hole wall,the mechanism of the small hole machining of CFRP was analyzed.On this basis,by studying the relationship between the ratio of undeformed chip thickness to cutting edge radius and the specific cutting force,the size effect of the composite material in the process of small hole and micro hole drilling was discussed.(2)The effect of process parameters on the small hole machining of carbon fiber reinforced composite was studied.First,the relationship between axial force,torque,spindle speed and feed rate was mainly discussed.From the qualitative and quantitative point of view,the degree of correlation between them was explained,and we got the empirical formula of axial force and torque.Also,the influence of process parameters on the quality of the hole was studied.We researched mainly from the two aspects of the export of the burr and the inlet aperture.It was concluded that the inlet aperture was closely related to the process parameters,and the influence of process parameters on the exit burr is not significant.(3)The effect of tool wear on the hole quality in the process of small hole drilling of carbon fiber composites was studied.By measuring the VC value of the flank wear of the drill bit in the machining process,the tool wear curve was drawn.The results accorded with the tool wear curve.At the same time,the influence of tool wear on the aperture and outlet burr of the small hole was analyzed.With the increase of tool wear,the aperture error increased.Simultaneously,with the increase of the number of holes,the number of exit burr was increased and the quality of holes became worse.(4)The process parameter optimization of the small hole drilling of carbon fiber composite material was carried out.By determining the axial force and torque empirical formula as a constraint function,and the relationship between the burr area and torque,optimization of the target with the maximization of the material removal rate was prepared.Finally,we got the results.The optimal spindle speed is 8000r/min,and the feed rate is 82.99mm/min. |
