Fu Jianzhong

Tool-path planning based on iso-scallop for plunge milling in pocket walls manufacture

Because of its high axial rigidity and metal removal rate, plunge milling is employed for pocket walls roughing in aircraft framework manufacturing and dies-and-molds industry. A new method of tool-path planning for plunge milling based on constant scallop height is presented in this paper to determine the proper interval between two adjacent CC (cutter contact) points. The objective is to keep the scallop height constant across the machined surface such that the number of CL (cutter location) points are minimized, while keeping machined surface within given error. The mathematical model is experimentally validated by computer simulation test. Results indicate that iso-scallop machining achieves the specified machining accuracy with fewer CL points than existing tool path generation approaches. In a word, the proposed method offers an efficient solution for plunge milling tool path scheduling on pocket walls.

AXIS-BASED LOOK-AHEAD INTERPOLATOR FOR MACHINING OF SURFACES REPRESENTED BY NURBS CURVES

The dynamics influence on each axis doing high speed machining is significant but always ignored in most of the interpolators. The proposed Axis-based Look-ahead NURBS Interpolator (ALANI) strictly confines the component acceleration and jerk on each axis according to the servo system and cutting status, so that the acceleration and jerk on axes are kept under the limit in order to avoid immoderate vibrations and shocks. Chord error is also confined during interpolating. ALANI may trace back and recalculate previous data while encountering dangerous points. The recalculation algorithm is composed of acceleration decreasing algorithm (ADA) and synchronously decreasing algorithm (SDA), which are able to choose secure feed rate as well as to attain high efficiency. The simulation and experiment are presented in this paper.

Demolding Defects and the Design of Demolding Device in Micro Hot Embossing Process

The defects caused by auto/manual demolding are studied to get better imprint quality in micro hot embossing process. Finite element method(FEM)is used to simulate the demolding process of high aspect ratio microstructures.The results show that the stress concentration mainly occurs at the bottom of microstructures when the auto demolding device is used.The maximum demolding stress is generated during the initial stage and the defects are mainly necking and root fracture.Great stress concentration will be caused by concentration little demolding direction deviation in manual demolding,and that stress concentration will reach the maximum in the late stage of the demolding process.190 MPa stress can be caused due to 5°direction deviation,then the demolding defects are mainly microstracture topping and root fracture.So an auto demolding device is needed when fabricating high aspect ratio structures.A new pneumatic demolding device is designed to overcome the warp distortion of polymer substrate caused by the traditional demolding system.Successful fabricating of microstructures with an aspect ratio of 3.3 verifies the improvement of the demolding device.

Thrust ripple optimization and experiment for a permanent magnet linear synchronous motor

Thrust ripple such as end force, slot force and normal force are key factors that affect the properties of permanent magnet linear synchronous motors (PMLSM). According to different mechanics and analytical models, end force resulting from open magnetic circuit of PMLSM was greatly decreased by optimizing the length of the PMLSM mover. Slot force caused by slot effect was greatly reduced by using fraction slot structure, and normal force was calculated through the finite element method (FEM). After thrust ripple was calculated, its uniform formula was obtained through Fourier series nonlinear regression. An experimental system was set up to measure thrust ripple, and experiment results demonstrated that experimental force ripple was quite in line with that calculated by the fitting formula. The optimal theory and analysis method is effective, and the obtained formula can be utilized to compensate thrust ripple in practical applications and improve the motion performance of PMLSM.

Research on remote intelligent fault-diagnosis of CNC lathe based on bayesian networks

Considering the development of smart machine tools and internet-based manufacturing and in order to manage the manufacturing process more efficiently, a unit of remote intelligent fault-diagnosis based on Bayesian Networks (BN) was designed and software based on internet was realized as well as the case study concerning CNC lathe. It is a compensation of machine tools self-detection whose major job is to find the fault of hardware and programming. The case study proved the reliability and advantages of the intelligent model based on BN.