Fixture System Of Paper Honeycomb Core Material For High Speed NC Machining

Adhesive materials are often used, in current fixture methods, to fix honeycomb core material in high speed machining process. Proved by practice, these fixing methods cannot achieve the aim to fix honeycomb core material reliably. During development of a type of fighter plane, shaping of paper honeycomb core parts is too difficult to meet design requirements. As the result, some defective parts were transferred to next working procedure. Which is fearful hidden trouble and is harmful to plane quality. In order to improve the quality of paper honeycomb parts, a new fixture method based on magnetic field and friction force is put forward. This new method can effectively reduce manufacturing cost. And the new method is also a green manufacturing method, which has no harm to workers and environment. In this paper, feasibility of the new method was demonstrated using FEM (finite element method) and experiments firstly. Then fixture system were designed and manufactured with electromagnet and permanent magnet respectively. Machining experiments, with new fixture system, show that the preparation for production becomes simpler, tooling precision is greatly improved, and the full processing is no harm to worker.In chapter 1, conception, development and application of composite material are elaborated, firstly. Then deficiencies of currently used fixture methods were analyzed. In order to improve the machining quality of paper honeycomb core components, a new fixture method based on magnetic field and friction principle is put forward. In the end, research content and overall structure of this dissertation are given.In chapter 2, mechanism of friction force generation is expatiated at the beginning. Then contributing factors of friction force, such as friction coefficient, height of iron powder and magnetic induction value of iron powder region, are studied. Granularity of iron powder is decided aiming to get max friction force and meeting requirement for controlling dust flying at the same time. At the end of this chapter, machining force of paper honeycomb is decided by theoretical calculation and experiment mensurating.In chapter 3, formulas expressing how to transfer discontinuous honeycomb material into continuous solid were studied. And according to these formulas, effective mechanical parameters of paper honeycomb material of stab, such as elastic modulus, shear modulus and poisson ratio, were calculated. Then using effective solid model, relationship between deformation of Z direction and height of honeycomb core material was studied under constant machining conditions. At last, method for deciding clamping position based on regular hexagon region partition was presented. And clamping position of stab paper honeycomb core part was decided using this method.In chapter 4, effects of structure parameters, such as span, height, thickness and length of magnetic pole, on magnetic field distribution were qualitatively studied using FEM (finite element method). According to analyzing results, electric-magnetic devicewas designed and manufactured. And magnetic field distribution of the device was tested. At last, effect of additional magnetic field on tool was analyzed.In chapter 5, structure system of special electric-magnetic device, universal electric-magnetic device and universal permanent magnetic device were design and two universal devices were manufactured. Using two universal devices, machining experiments were done and satisfied parts were gotten.Finally, systematical summary is given, and future work is put forward.