Advanced Materials Research Vol. 500

Abstract: To solve the conflict between OSs real time property and NC systems open and universal property [, a compiled-typed NC system is advanced based on analysis and research of the structure of modern NC systems. This kind of system can diminish the affection of the real-time OSs respond precision to machining with high speed and high precision and improve the frequency of interpolation sampling and respond precision. Motion control experiment and parametric curve direct interpolation experiment are finished by bonnet polishing machine tool with compiled-typed NC prototype system, proving that working principle of compiled-typed NC system is correct and validity.

Abstract: The compiled-typed NC system compiles NC program into object codes and sends them to slave computers. The object codes generated is a large amount of data. To ensure the data transmission fast and real-time, USB communication is adopted and researched in this paper. The design of USB driver program and communication program in the upper computer and slave computers is mainly introduced.

Abstract: The reconfigurable flexible process-equipment developed for machining complex shape and size changes in the scope of large thin-walled parts usually consists of dozens or even hundreds of positioning/support units. During the control process, each unit communicates with the host computer to get control commands and simultaneously feedback internal state information. For large complex system composed of many subsystems, the traditional cable connection based on field bus technology is high control costs and the complexity of the control circuit is hard to build and manage. To solve this problem, this paper puts forward a new way of wireless communication with the cable network technology and drive positioning/support unit in order. This paper focuses on the overall structure of the proposed system, host computer control system, lower computer control system and wireless communication module as well as the implementation hardware circuits and software algorithm. In addition, some solutions of related issues are discussed. The research shows that the proposed system has high stability and reliability, and it provides an effective way to the control and communication of complex system which fully meets the requirements of reconfigurable flexible process-equipment.

Abstract: The thin-walled complex parts reverse engineering is very different from conventional parts or the parts have some simple surface reverse engineering. There are some features. For example, it may have a lot of surface, structure complex, and it is difficulty that scanning point cloud data. Through this thesis, we put a stent by pedal as a thin-walled complex part, introduced some technology about it reverse engineering.

Abstract: A Monte Carlo Potts model for the sintering process of two-phase nanocomposite ceramic tool materials is proposed. The grain growth, pore diffusion and vacancy annihilation at grain boundaries are simulated in the model. Simulation results are presented and discussed. It is found that pore and nanophase can pin the ceramic matrix and decrease the growth rate of matrix grain during the microstructure evolution. The addition of nanoparticles is not only beneficial to the refinement of ceramic matrix grain and the formation of intra/intergranular-type microstructure but also advantageous to the densification of ceramic materials.

Abstract: Based on the theoretical study on the tip stress intensity factor (SIF) of the crack normal to and dwelling on the interface, using the finite element software ANSYS, the SIFs of the double interface cracks normal to and dwelling on the interface in cladding material structure are studied by changing the crack spacing, the crack length, the cladding thickness ratio, the load and the crack location. The results show that, the crack SIFs become larger with the increase of the crack spacing, the crack length and the load, they become smaller with the increase of the coating thickness ratio, that the SIF of the crack close to the boundary becomes smaller with the increase of the distance between the crack and the boundary, and that the SIF of the crack in the middle of the interface becomes larger with the decrease of the crack distance.

Abstract: A modified three-dimensional Monte Carlo (MC) model in presence of pores and impurities for three-phase nanocomposite ceramic tool materials is successfully established in this paper. Pore migration by surface diffusion is incorporated into the MC model and it is applied to observe and scientific quantitative characterization of three dimensional microstructure evolution and densification process. Some modifications are applied to the simulation algorithm to improve the computing efficiency. The influence of pores on the particle and impurity loaded grain boundaries is simulated and investigated for the study of grain growth kinetics. The relationship between porosity and density is also analyzed. The results indicate that the higher the porosity is, the lower the density will be.

Abstract: The new Monte Carlo Potts model that couples with fabrication parameters and considers pores and additives has been developed in order to simulate the fabrication of single-phase ceramics tool materials. The microstructure evolution for single-phase Al₂O₃ ceramic tool materials is simulated with the different technology parameters. At the same time, the single-phase Al₂O₃ ceramic tool materials are fabricated with the corresponding technology parameters. The errors of grain size between the simulated and the experimental is 12.1 and18.2%.

Abstract: In high speed metal cutting momentum would be large and the strain rate can be exceedingly high, the viscosity of material must take into account in studying the chip deformation. Model the high speed machining as fluid flow is much better than as solid. A laminar flow method is applied in this paper to analyze the velocity distribution, the pressure distribution, the temperature distribution and the strain rate distribution of high speed metal cutting. Analytical results showed that a speed stagnation point is located at some distance from the tool tip on the tool rake face, on which the maximum value of the pressure occurs, with zero speed; its location influences the life of the tool and the quality of the finished surface. The value of the pressure decrease along the rake face and reaches zero at some point away from the tool tip, which is the point of separation of the chip from the tool; The value of strain rate get a rapid increase from the tool tip to the free surface corner then decreased outwards.

Abstract: This work aims to investigate parameterized modeling and a different mode of loading with finite element analysis for flat end mill. A loading mode is chosen according to the cutting force model of overall end mills. Normal and shear stresses which calculate from the cutting force experiments are loaded on the rack face of flat end mill. The stress distribution of end mill in high-speed cutting is obtained by finite element analysis. It is shown that the maximum stress is located at major flank face near the tool tip, rather than the nose of tool and the chisel edge. It shows the tool breakage mechanism in the local region. In the end, we compared the finite element analysis results with the experiment ones. It indicates that the analysis results agree well with the experimental data. Therefore, the proposed loading mode is available.