Research On Excitation Element In Fixture System Of Paper Honeycomb Core Material For High-speed NC Machining

Paper honeycomb core material is now widely used in airplane industry, because of its excellent mechanical property. But traditional methods in our country cannot fix this kind of part reliably, in high speed machining process, which is an obstacle of using this material. In order to solve this problem, Prof. Ke Yinglin in Zhejiang University invented a reliable method in 2001, based on the magnetic field and friction force, to fix the paper honeycomb core material during machining. This method is a national patent (patent number: ZLO1135679.0). In contrast with the old method, this new method can obviously reduce manufacturing cost while increasing precision and efficiency. And the new method is also a green manufacturing method, which has no harm to workers and environment. By experiment, theoretical calculation and FEM(finite element method) simulation, this paper studies at the magnetic field and mechanical model of this new fixture system deeply, based on the former research.By now, permanent-magnet fixture system is applied to clamp paper honeycomb core part successfully, which has good effect on the procedure. However, it also has some shortcoming, such as difficulty in assemblage. For solving these problems, electromagnetic fixture element is demonstrated, which is a new choice. In addition, theoretical calculation and FEM using in this paper can be regard as supplement of experiment-dominating research method.Magnetic density is the key point of the new method, because it's is the primary cause of the friction on honeycomb. The magnetic conductivity of the honeycomb core material filled with iron powder must be measured before magnetic calculation. Up to now, scholars, both in our country and in foreign country, have some research on the mixture of ferromagnetic powder, nonconductor and bond, but lacking research on the honeycomb with iron powder. The sectional magnetic conductivity can be achieved by experiment, while the axial one can be estimated by theory. Appling these parameters to calculation, magnetic field can be got both by theoretical calculation and FEM simulation. And then, a curve composed of three segments is fitted to describe the magnetic density in iron powder region.Magnetic density is prepared by now. It is necessary to calculate magnetic force, and compare the max breakout friction caused by this force with the dead load of iron powder. The friction is bigger than the dead load, which means the iron can be "adsorbed" by the honeycomb core material. Afterward, an equivalent material is defined, the elastic ration, Poisson ratio and shear modulus of which is the same as honeycomb and density as honeycomb filled with iron powder. The cutting force applied to the material in the forms of concentrated force. Using FEM method, the biggest local deformation in z direction can be achieved. If the deformation is within the allowable tolerance, the fixing method can fix honeycomb core material reliably.Finally, this paper finds the relations between the fixing force and kinds of related parameters and does optimization of these parameters to minimize material volume and cost.