Dynamic vibration and static deformation are two main factors that affect the machining quality in a long slender shaft turning operation. By simplifying the turning system of a slender shaft into a one-section beam with a clamped-pinned constraint condition, the direct receptance at any arbitrary cutting point is derived. On the basis, the regenerative stability lobes diagram (SLD) for a long slender shaft turing operation is achieved. With the proposed modeling methodology and simulation algorithm, the effect of cutting position on the direct frequency response function (FRF) and the predicated SLD, as well as the effect of the cutting conditions on the predicated SLD are investigated. The predicated direct FRF at the cutting point is validated by hammer tests.
During milling operation, the cutting forces will induce vibrations on both the cutting tool and the workpiece, which will affect the topography of the machined surface. Based on the Z-map representation of the workpiece, an improved model is presented to predicate the 3D surface topography along with the dynamic cutting forces during an end milling operation. A numerical approach is employed to solve the differential equations governing the dynamics of the milling system. The impact of cutting parameters such as the feedrate, the axial depth of cut and the dynamic characteristic of milling system on the surface topography is investigated by simulation. The all above can provide some instructive directions to the manufacturing engineers in determining the optimal cutting conditions of an end milling operation.
As a new-type, high efficient hole-making technology, helical milling is widely used in making holes on composites and composite-metal compounds materials in the aircraft industry. In this paper, the problem of machining path optimization using helical milling is converted to a TSP (Traveling Salesman Problem), a mathematical model is established and solved using ACO (Ant Colony Optimization). Simulation results show that with the application of ACO, the traveling efficiency of helical milling has been increased by 41.1%.
. Based on the dynamic simulation module of CutPro, the dynamic cutting forces and chatter limits for tee slot milling were predicated by setting the geometry of a tee slotting cutter. The chatter stability lobes under a given axial depth of cut are obtained by further programming, which is essential for chatter-free tee slot milling. A methodology of cutting conditions optimization for tee slot milling is presented, in which the minimal cutting time is used as the target function and the stability limits are introduced into the constraint conditions to reflect the vibration characteristics of milling operation. This optimization method has been validated by experimental tests.
In analog electronic systems, characteristic information required for fault prognosis is achieved by test points of a board, so the selection and optimization of test points is an important topic for PHM research of electronic products. Current methods for selection of test points generally rely on functional simulation analysis or testability modeling analysis. Based on this, FMMEA method is introduced to find failure susceptibility components in this paper, moreover, through simulating and calculating the predictability of test points, the final test points are determined. As an example, a board level system is presented to validate this approach.
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