Research On Drill Hole Defect And Optimization Of Tool Design Of Carbon Fiber Reinforced Polymer Composites

Nowadays, CFRP which is a kind of advanced composite materials is widelyused in military and civilian fields. It has excellent mechanical properties.Because CFRP is composed of fiber and resin, it has the characteristics ofanisotropy, resulting in a lot of new problems in its second processing, especiallydrilling holes processing. There will be lamination, which is a kind of specialmachining defects. In addition, there are still Burr defects and tear defects. Andbecause of poor thermal conductivity and high hardness characteristics, it alsoappears a phenomenon of short tool life. These problems have become theimportant factor which restrict CFRP high efficiency and high quality processing.Aiming at these problems and basing on the in-depth study of cuttingmechanism, this text analyses force variation in different tool cutting process. Bymeans of test and analysis, it studies on the change rule of cutting force indifferent cutting parameters. It carries out to study the effect of different cuttingparameters and different cutting parameters on delamination flaw, and thencontrasting and analysing of layered detection results, optimizing cuttingparameters. This paper mainly studies the following aspects:First, the binary cutting mechanism of unidirectional CFRP is studied. Byanalysing the cutting process, we can get that the different angles between thefiber direction and the cutting direction have impact on cutting deformation andchip formation. The cutting mechanism is studied from the angle of theory. Itanalyses the distribution of cutting force during different bit cutting CFRP andchanges of cutting forces in different stages. According to the characteristics ofthe traditional drilling cutting method, it analyzes the main types of holes defect. Then, by experiment analysis method, it establishes the regression model ofaxial force and gets the empirical formulae of two yuan of the axial force.According to the lamination defect, it designs the generalized double angle drill,which is trial-produced cooperation with Santak, and then analyzes the designconcept. The experiment scheming about the effect of tool parameters and cuttingparameters on delamination flaw is designed. And the CFRP drilling test is donecooperation with AVIC Hafei.Secondly, it detects the CFRP plate by C scanning microscope. Drillingholes entrance surface between the layers of stratified is the oval, depth layeredis circular. Then it establishes Stereo hierarchical model of boreholedelamination flaw. It analyses the influence between laminated layer of the maindirectional stiffness and elliptical delamination at the entrance of the hole.In the end, the layered detection results are analyzed. Using range analysismethod, it explores the influence of tool parameters on the layer by layerdelamination flaw. Further, it could optimize the cutting tool geometry. And byusing of Origin it draws Variation curve of each layer defect size and the toolparameters, directly perceived through the senses analysing the law of effects andvariation. By MATLAB it draws change law of the effects of cutting parameterson delamination defect. And by using the method of multivariate nonlinearregression analysis, it gets the relation formula about the effects of spindle speed,feed rate and drilling CFPR each layer delamination size at the entrance and exit.