Research On Laser Drilling Technology Of Special-shaped Thin-Wall Ceramic Parts

Structural ceramics with stable physicochemical properties and excellent electrical performance,are widely found applications in irregular cores,electronic packaging and other fields.Because of its properties of high brittleness,hardness and difficulty of machining,laser drilling technology,which has the characteristics of high speed,high precision,non-contact,small thermal effect area has become the preferred choice for small hole processing method of structural ceramics.On the basis of the principle of interaction between laser and material,through the finite element software simulating laser drilling processes of specimen,building the corresponding experimental platform,optimizing the process parameters,the small hole with small taper,less melt,no obvious micro crack and clear structural edge is obtained.1.According to the theoretical calculation of the surface energy density of specimen and the maximum energy required for drilling,the finite element analysis model with different peak power,on the basis of the principle of material phase transformation,the influence of laser peak power on laser drilling process was analyzed.The results indicate that in the case of spot diameter and pulse width unchanged,with the increase of laser peak power,the surface energy density of specimen increases.Phase shift of the material to the gasification by melting,the number of pulses required for drilling is reduced and the processing time is shortened.At the same time,the peak temperature of temperature field and the thermal cycle curve at each point increases.Due to the smaller thermal conductivity,the distribution of temperature field change is not so obvious,which leads to the drastic variation of thermal stress and the brittle fracture of the specimen.2.A laser perforating test platform for special-shaped thin-wall ceramic parts is developed.With the grouping experiments,the relationship between the peak power,the defocusing length and the depth and taper of the hole in the process of laser drilling are established.Combined with theoretical analysis,the influence of various factors on small hole melt and micro crack was researched to optimize the parameters in the drilling process.Finalizing the parameters such as the peak power of 1000W,pulse width 10ms,frequency 50Hz,defocused 0.4mm,the current speed of protective gas(80%Ar+20%air)20L/min got the small hole which meeting the high quality requirements.3.The effect of shaped surface on the interaction between laser beam and material is studied,and the micro hole shape in femtosecond laser machining is also analyzed.The shaped surface affects the absorption of laser energy in the range of laser spot,and the inhomogeneous transformation of the material at the edge or the center of the hole leads to the non-circularity of the hole.Femtosecond laser processed the hole on the ceramic specimens with the best quality.The edge in the axial section of the specimens is clear,with little melting material and no obvious crack.