Study On The Modularized Fixture Technology And Several Key Problems In High Speed Machining Process Of Paper Honeycomb Core

NOMEX honeycomb core was widely used in the aerospace industry as the honeycomb core with the sandwich structures for series of merits such as high specific strength, high specific stiffness , which were not shared by the traditional materials. And it was being one of the most necessary materials in the industry. NOMEX honeycomb core should be milled to meet the demand of the assembling process. However, as the honeycomb core can stand much force along the honeycomb axial direction while little in the honeycomb plane, the fixation of NOMEX honeycomb core was based on the bottom lines which could provide little force compared to the solid materials which can be clamped with enough fixing force. As the result, during milling process, sometimes the honeycomb core was pulled up by the tools because of the little fixing force, which leaded to bad machining quality. There were another two problems in the milling process: (1) A great deal of dust was produced which was harm to the machine tool and the workers. (2) The vesicant which was used to felt different honeycomb core was difficult to cut and would damage the tool badly. For the problems in the milling process and fixture process of NOMEX honeycomb core, deep and extensive research was done based on theory analysis, FEM, and experiments.Aimed at the contradiction of the fixation force and milling force, series of regression orthogonal experiments were designed and executed with the normal NOMEX honeycomb core tools. From the experiment data, the influence of the factors which included milling depth, milling breadth, feeding speed, cutting velocity and tool inclinations to the milling force and surface quality was deeply analyzed. The milling model was built up.On the basis of the milling model and analysis of the machined surface quality, one new milling technology was presented to solve the problem of dust produced during the honeycomb milling. Using the technology, grooves were machined first and then the left part of the honeycomb core was cut with a circle slice milling tool. Several experiments were designed to assure its feasibility, and the influence of different cut parameters on cutting force was carefully studied. When it came to the vesicant, the reason that tools was damaged badly was analyzed, a new milling process was found and several experiments were executed to demonstrate it.The coupled analysis of the FEA simulation of the milling process and the experiment data lied in the third part of the paper. Based on the large non-linear FEA software ABAQUS, a plug-in was developed with the python language to create the two kinds of honeycomb core geometry models. The key points around the FEA simulation of the cutting process were discussed and studied. Under several simplifications and hypothesis, the method of building up the right FEA model was described.At last, based on the powerful magnetic field and friction principle, a useful modularized fixture technology was presented. A magnetic FEA model was built up with APDL language to prove the new technology. Coupled with the results of the FEA. mathematical analysis and the experiment data from chapter 2, the modularization fixture was proved to be reliable.