Research On Interface Thermal Properties Of CFRP/Ti Stacks During Drilling

With the deepening of exploration in aerospace territory,the increasingly stringent conditions during application put forward higher requirements for the material properties required for the manufacturing of corresponding equipment.The laminated structural materials of carbon fiber reinforced plastics(CFRP)and metal alloy have both advantages of the two types of materials in the performance.They have higher mechanical properties and better adaptability to complex environments.Therefore,they are often used in the manufacturing process of aerospace and other fields.Among this kind of material,the laminated materials of CFRP and titanium alloy(Ti)are widely used.However,the two types of materials contained in CFRP / Ti stacks are both difficult to process.A large amount of heat generated in the drilling process will lead to serious thermal damage to the material,which is particularly serious at the interface between the two types of materials.In order to explore the processing scheme to minimize the influence of drilling heat of CFRP / Ti stacks on the processing quality,the drilling heat characteristics of CFRP / Ti stacks are researched in this subject.Firstly,the heat distribution at the material interface and the thermal damage caused by heat during the drilling process of CFRP / Ti stacks were observed.The temperature distribution at the interface during drilling was researched by theoretical research and experimental research.The method of the arrangement of temperature measuring thermocouples in subsequent experiments was proposed.Through the observation and analysis of the form of machining damage,the basis of the judging methods of material damage by interface temperature was put forward,and the relationship between the highest interface temperature in the drilling process and the thermal damage of the material was established.Then,the effects of processing parameters and ultrasonic vibration assistance on the temperature at the material interface during drilling CFRP / Ti stacks were researched.The influence of feed rate and spindle speed on the maximum interface temperature in the drilling process and the causes of the phenomenon were analyzed.Subsequently,a combination parameter drilling scheme,which is suitable for different machining characteristics of two types of materials was proposed.A comparative test of ultrasonic vibration with different amplitudes under the same machining parameters was designed to evaluate the improvement effect of combination parameter machining and ultrasonic machining on interfacial thermal accumulation.The main effects of processing parameters,parameter conversion positions and ultrasonic assisted processing parameters on the interface temperature of drilling CFRP / Ti stacks were obtained.Finally,to explore the causes of the above phenomena,the direct causes of heat accumulation at the drilling interface of CFRP / Ti stacks were obtained.By designing drilling tests under different specimen thicknesses,the thermal effects of various factors on the drilling process were amplified,and the change process of interface temperature was divided in few stages.At the same time,through the analysis of the cuttings produced in drilling process,the effect of drilling cuttings on changing the interfacial heat distribution was researched,and the influence of different types of cuttings on the interfacial heat accumulation was obtained.