The Research Of Key Technologies On Drilling Break Monitoring For Precision Micro Bit Based On Drilling Force And Swing Angle

Printed Circuit Board(PCB),as the carrier and support for most electronic products and components,is also known as the "mother of electronic products." With the development of technology,PCB has gradually become smaller,high-density and high-integration.This has led to the miniaturization of the drill bit,which raises many new problems for mechanical drilling and bit requirements.Among them,the failure mechanism of the drill bit,especially the research of the broken drill process,will become an important factor restricting the development of the industry.In this paper,the following research and conclusions are made on the protection of the broken micro-drilling drilling:(1)Introduction of drilling type,analysis of cutting and discharging process,and introduction of drilling breaking mechanism of micro-drilling.In this paper,through Kistler high precision micro-force measuring platform,the data signals of the axial force and torque of the common drilling process and the broken drilling operation are observed respectively.By analyzing and comparing the data,it can be concluded that when the micro drill starts to break,the axial force and torque will increase sharply,and the change is very obvious.Therefore,the increase of axial force and torque is the main reason for drilling breakage.(2)Breaking prevention under static conditions: This paper establishes a semi-empirical mechanical model of torque and axial force by semi-empirical formula modeling method,and then determines the parameters in the semi-empirical formula through experiments and least squares method.Considering that the drilling noise will increase the experimental error,the filtering function in the matlab signal processing toolbox is used to remove the high frequency part,and two unknown parameters in the theoretical modeling are obtained.After comparing the error processing analysis data,we can see that although there are errors between the theoretical values and the experimental values,the results are consistent.The conclusion is drawn that the theoretical model is reasonable.(3)Prevention of drill breakage in dynamic work: By building an infrared high-speed photographic platform to observe the bit swing angle of micro-drill in three stages from normal operation to bit breakage,and then by processing and analyzing the swing anglecharacteristics of micro-drill in the process of drill breakage with MATLAB image processing function,the relationship curve between the swing angle and the sequence frame image is obtained.Through curve analysis,the variation law of swing angle curve can be divided into three parts: the law curve of swing angle in drilling,the law curve of stable swing angle and the law curve of swing angle in broken drilling.Through quantitative analysis,it can be found that the swing angle radian value of micro-drill in normal drilling process is within the range of ±0.01.It has certain guiding significance for the protection of micro-drilling breakage.