Key Technology Of CFRP And Titanium Alloy Stacks In Drilling

The rapid development and application of advanced materials,aerospace components to the performance and structural strength is greatly optimized.The stacks made of carbon fiber composite material and alloy also rank among the advanced materials.Because of its superposition of material properties,drilling quality is not ideal.In this thesis,the carbon fiber reinforced composites and titanium alloy stack materials are used as drilling objects.Both of them are difficult to drill,and the stacks meet the severe challenges in tool wear and drilling quality.This paper focuses on the key technology of drilling to take experiment researches for the drilling quality requirements and production efficiency optimization.The concrete research contents are as follows:First of all,through the design of orthogonal experimental group,the single carbon fiber reinforced materials drilling experiment were carried out.The influence of process parameters and tool types on drilling quality of carbon fiber composite was discussed by comparing the data from the extreme difference analysis.The critical axial force is deduced from the crack propagation at the exit of the composite material by drilling delamination model,and the relationship between the critical axial force and the outlet quality of the hole with the twist drill and the step drill are compared.Secondly,the stack material was subjected to a drilling experiment.According to single factor variable method analyzed the effect of drilling parameters and stacking sequence and tool coating with drill axial force.And according to the mechanism of tool wear discussed the types of tool wear in drilling stack and the effect of tool wear with the hole appearance.Then,the drilling process was numerically simulated with ABAQUS software using twist drill as an example.The Hashin failure criterion was used to judge the failure of the carbon fiber reinforced composites,and analyzed the change of drilling force and the damage of the hole entrance and exit.Finally,the vibration energy principle of the damper was used to reduce the vibration of the drilling system and assisted the drilling process of the stack material.The hydraulic damper was distributed evenly in the bottom of the fixture to realize the vibration-damping function in the drilling system.In those experiments,the thrust of the drilling was obviously reduced and the quality of the hole was also improved.