Papers by Author: Cheng Yong Wang

Abstract: In this paper, with milling characteristics of high hardness hardened steel, we choice six different coated tools to made cutting experiments on high hardness hardened steel Cr12MoV (HRC65). In this stage, through the analysis of cutting force, cutting temperature, cutting vibration, machined quality and tool wear, we have elected the preferred tool and tool geometry parameters for this processing stage. The results of the study show that: TiAlSiN is the most suitable for Cr12MoV (HRC65), which helps to improve cutting processing productivity, prolong tool life, and enhance processing quality and reduce the processing cost.

Abstract: The thermal conductivity of carbon fiber reinforced polymer(CFRP) and titanium alloy is lower which caused the increasing of drilling temperature and larger tool wear resistance. The low temperature air is aided for the drilling of laminated stack board of CFRP/Ti with double apex angles carbide drill at different feed rate. The drilling force and the quality of hole are analyzed. The results showed that the low temperature air can reduce the tool wear and the thrust force effectively.

Abstract: Abrasive water jet was utilized to polish the 40CrMnMo7 mold steel and BK7 glass in this experiment designed by Taguchi method. The influence of polishing parameters on the polishing quality, their significance order, and the optimum polishing parameters were analyzed and reported. With the experimental data, the mathematic molds of surface roughness of polished workpieces were created by dimensional analysis, and then they were validated by the test experiment.

Abstract: In the PCB micro drilling, because the force signal is tiny, and when the micro-drill drill to a certain degree of multilayer PCB, alternate force signals will not appear obvious, through to the drilling force signal analysis, we can know the drill bit position and the materials to the influence of the drill failure, so the drilling force signals denoise seems extremely important. In the processing of the non-stationary signal, traditional signal processing method has a certain extent of insufficient, using the wavelet packet decomposition signal, the white noise variance and amplitude decrease with the increase of wavelet scales, but the signal variance and amplitude has nothing to do with the wavelet transform. According to the view of the signal energy, first of all, we make the multiscale decomposition of the signal, then, by using some of the wavelet packet that has efficient energy to reconstruct the original signal. Comparing with the traditional threshold denoising ,using this method in the test signal to deal with the noise can effectively eliminate the white noise interference, and has good denoising effects besides the simple calculation.

Abstract: Tool breakage monitoring is crucial to automation fabrication, especially for high-density hole machining, such as PCB (Printed Circuit Board). A tool breakage feature extraction method in PCB micro-hole drilling is presented in this paper. The vibration signal is analyzed by wavelet transform. The decomposed signals energy ratio at each frequency band is computed as monitoring features. The monitoring performance of different features selection is given. The vibration signals are observed to provide the capability in distinguishing micro drill breakage with proper features extraction and classifier design.

Abstract: Abrasive jets can be used for polishing when fine slurry is used. This paper presents a model for the jet formation process, CFD simulations are carried out for the prediction of flow pattern in a nozzle with abrasive suspension slurry jets using the discrete phase model. The CFD model aids in understanding the process because of the difficulties in performing the direct measurement of the jet axial velocity and radial velocity, the model simulates the different pressure premixed slurry pass through the pipeline and the focus tube to the atmosphere. The model is able to predict the orifice efficiency and the cross sectional profiles of the jet velocity after the nozzle, the modeled results are in good agreement with both experimental and analytical data. The simulation model can be useful in studying the overall slurry jet process and for the optimization of the slurry jet parameters.

Abstract: BK7 optical glass is used as the object of study in this paper. The different parameters such as lapping time, load, slurry flow, slurry concentration, abrasive grain sizes, rotating speed effect on surface roughness and material removal volume are studied. Using the way of orthogonal experiments for seeking optimization parameters to gain the smoothness surface and consume the minimum machining time. The empirical formulas of surface roughness and material removal rate are found by orthogonal test.

Abstract: Material fracture character of marble processing by single diamond tools was studied by single diamond indentation experiment and fast milling experiment. The surface morphology and inner cracks were achieved based on double lights transmission of stereomicroscope, marble semitransparent character and SEM technology. Results showed Indentation cracks break crystal or extend along cleavage plane from three directions. The marble indentation fracture progress could be divided into three phases: plastic deformation, fracture deformation and block broken. Material broken types were diverse for different compositions in marble.

Abstract: This paper gives an introduction of the simulation of ultra-high-speed drilling on the copper of printed circuit board (PCB) by using finite element method (FEM). The cutting force, cutting torque and the distribution of cutting temperature are predicted. The value of cutting force is also be compared with the experimental value. The simulation results show that the experimental value of cutting force agrees well with the FEM value and the value of cutting torque is very small in the drilling process , in addition，the maximum temperature of copper comes up to 209 °C in center area and the temperature of copper chip evacuation from the spiral groove ranges from 135°C to 155 °C.

Abstract: Erosion caused by solid particle impact is a very common phenomenon. In many fields such as particle (or slurry) transportation, equipment protection in a dust environment, turbine engineering, etc., prevention of particle erosion is the task. In other applications, it is used as a tool for desirable material removal, surface cleaning, controlled destruction, numerous studies on this subject have been conducted by researchers from many disciplines including physics, material science, mechanics, manufacturing, standardization, etc.. To provide a comprehensive view of the problem of erosion by solid particle impact, a review is conducted based on the literature collected on material subject of erosion by solid particle impact. The reviewed works are limited to ductile material erosion and four categories: erosion mechanism, parametric studies, material removal modeling and simulation modeling.