Papers by Author: Ding Hua Zhang

Abstract: A unified oblique cutting force model for flat end mills is developed. In this model, the cutting force is bridged among cutter geometry, material properties and cutting parameters. The cutter angles, material parameters and cutting parameters are the only inputs so that the model is applicable for different cutter-workpiece combinations and cutting parameters. The parameters in the model are solved by the geometric relations, applying Maximum Shear Stress Principle and Stabler’s chip flow rule. The material parameters are identified in a new method with orthogonal milling tests. The simulation results of the proposed model are in good agreement with experiments.

Abstract: To solve the precision manufacturing of thin-walled irregular-shaped workpiece, the MR fluids flexible fixture was designed and the simulation of device with compression structure was carried out to obtain performance parameters of device for optimizing the device. Then, some experimental test was implemented to verify the feasibility of device. The simulation and experimental results show that the current and coil turns have a great influence on magnetic field, and the shear stress of MR fluids are related with magnetic field and external compression force. The experimental results are in good agreement with simulation ones.

Abstract: An experimental study was conducted to determine cutting parameters of high-speed milling of Ti-17 according to their effects on residual stresses. First, three groups of single factor experiments were carried out to reveal the effects of cutting parameters on residual stresses. Then sensitivity models were established to evaluate the influence degrees of cutting parameters on residual stresses. After that, three criteria were proposed to determine cutting parameters from experimental parameter ranges. In the experiments, the cutting parameter ranges are recommended as [371.8, 406.8] m/min, [0.363, 0.412] mm and [0, 0.018] mm/z for cutting speed, cutting depth and feed per tooth, respectively.

Abstract: In the three dimensional reconstruction of cone-beam CT, a fast reconstruction method based on the smallest three dimensional convex hull was proposed for actual scan data. First, according to the definition of the minimum three dimensional convex hull, the minimum three dimensional convex hull of the detected object was obtained in the actual scan using a segmentation algorithm based on the projected images, and then with the Z-line data first algorithm, the image reconstruction area was limited to the minimum three dimensional convex hull to enhance the cone-beam CT reconstruction speed by reducing the redundant computing. The experimental results show that this method can effectively reduce the memory consumption, and significantly improve the reconstruction speed and reduce the noise surrounding the object imaging area.

Abstract: The system of collaboration between design and manufacturing is proposed in order to meet the precision forging manufacturing. The configuration of the system and functions are studied and analyzed in detail. The system integration mode based on PDM (Product Data Management) is put forward. Application systems around the process of collaboration between design and manufacturing can be integrated seamlessly by integration mode. And two key enable technologies are analyzed in detail. Model association method based on WAVE technology is used to implement design of precision forged die. The work model and data structure based on the collaboration system is studied. Finally, an application engineering system is developed and a case study is given to demonstrate the above ideas in the environment of aero-engine manufacturing enterprise.

Abstract: In order to provide experimental evidence for optimizing high-speed milling parameters and controlling surface integrity, the effects of cooling conditions, tool rake angle and milling parameters on machined surface residual stresses were investigated in high-speed milling titanium alloy TC11. The residual stresses were measured by XStress3000 X-ray stress analyzer, and three points were tested on each workpiece surface, then take average. The milling parameters were optimized based on fatigue performance. The results show that the emulsion cooling get the highest surface residual compressive stress and the dry cutting get the lowest residual compressive stress. With the increasing of cutting tool rake angle, surface residual compressive stresses increase. The most effect on the residual stresses of surface is milling width, next are feed per tooth and milling depth, and the last is milling speed. In the experimental range, the optimized high-speed milling parameters are: vc=377m/min, fz=0.03mm/z, ap=0.2mm, ae=7.5mm.

Abstract: To study of the temperature generating mechanism of Titanium Alloy Ti - 6Al - 4V in high speed, and the influence rule of the milling process parameters for milling temperatures, A temperature simulation model of the milling process was found with AdvantEdge, the relationship between the high speed milling parameters and the milling temperature of Titanium Alloy Ti - 6Al - 4V was discussed by the finite element simulation, and the milling process temperature was measured by the half artificially thermocouple methods. The result show that the highest temperature are reached at close to the tool tip in the rack face, the feed per tooth have significant effect on the milling temperature, while cutting depth and milling width have little effect. The milling temperature increase with the feed per tooth increasing，the highest temperature increase with the spindle speed increasing.

Abstract: Multidisciplinary design and simulation is a very effective process to balance the different discipline design requirements and gain the optimal design result. The paper proposes a master model approach in order to maintain the model associativity and consistency in multidisciplinary design and simulation for compressor blisk. The research presents a master model-centered model structure, which is composed of master model, context model and application model. In the proposed master model-based multidisciplinary design and simulation process, master model is the kernel model and shared by each discipline. In addition, there is an associative relationship among these models. Then, the paper studies the modeling method for the master model of blisk and the model mapping and associativity maintaining method for multidisciplinary design and simulation. A series of computation results demonstrate the performance of the proposed approach.

Abstract: The wide application on fields of designing and NC programming based on 3D model of part not only provide the supporting for applying 3D based process planning, but also raise the challenge for the design capability of 3D based process planning. The 3D based process is not just replacing 3D process drawing with 3D model, it is concerned with schemas of designing, managing information applying of process. This paper presents a novel architecture of modeling process information in 3D scene, the 3D based architecture proposed manages process information on the base of geometries and serial changes, which reflect machining operations applied to part, of geometry of part from raw material to final part and comprises such three sub-modules as manufacturing features, 3D model based processes and manufacturing resources. A methodology is exploited aiming at reducing overload of 3D modeling for process planner and keeping the consistency among 3D working procedure models when inevitable process change occurred, then a related algorithm is detailed in which the process decision information retrieved from the technician is transformed automatically to geometrical information to generate 3D working procedure model. Several typical applying of 3D based process consisting of Recognition and analysis of technology dimension chain based on 3D serial model, NC programming for CMM and analysis of feasibility of process are discussed and a prototype is demonstrated to verifying validity of the architecture and the methodology.

Abstract: The main factors of impacting Cone-Beam Computed Tomography (CBCT) image quality and their causes were studied, and an integrated method of enhancing CBCT image quality was proposed according to the Digital Radiography (DR) imaging model. First, the original polychromatic X-ray was filtered into quasi-monochromatic X-ray by the filter plate of copper-tungsten alloy, in order to improve the quality of the original projection images. Then, the integrated artifact corrections for projection images were processed on the order of dark field correction, gain non-uniformity correction, scatter correction and beam hardening correction, to avoid the one-sidedness of only correcting a certain kind of artifact. Experimental results show that the method can almost eliminate the main artifacts of CBCT system and improve image clarity and signal to noise ratio.