Advanced Materials Research Vol. 426

Abstract: To simluate the effects of lunar dust environment veritably by using lunar dust effects simulator, a detection and control system based on singlechip microcomputer was developed. In this system, peripheral circuits with stepper motor driver, temperature sensor and rotary transformer were used to collect the signals and control the temperature as well as speed. Stepper motor speed up/down curve, digital convolution filter and error compensation were adhibited for improving the system accuracy. The results showed that this method was simple, reliable and had high control accuracy.

Abstract: Based on image processing, a new method to straighten the electrolysis plate is proposed. This method uses two CCD cameras to grab images of plate edge and the computer extracts the edge and filters the image. With matrix transformation and calculating of the mechanical model, the motion parameters of the straightening device will be acquired. The straightening device straightens the negative plate as the parameters given. This method can make the curved quantity of electrolysis plate from 80mm down to 2mm or less, achieving an ideal straightening effect.

Abstract: Studied the causes of the size effect phenomenon of the process of nano-hardness measurements. First of all, theoretically discussed the impact of the indenter tip radius on the hardness measurement and analysis of its impact trend, after the use of molecular dynamics method on the ends of arc with a radius of 50nm standard three pyramid indenter and the ideal shaped indenter for a different indentation depth under indentation process simulation. Theory and simulation results show that: indenter tip with a circular arc is the important reason for the produce of the nano-hardness size effect phenomenon. In nano-hardness measurements, if the constant load experiments using different ends of the radius of the indenter for testing, then the larger the indenter of the tip radius is, the greater measured hardness value. If using the same indenter, then the smaller test indenter of the indentation depth is, the greater corresponding to the indentation angle, so the measured hardness value greater.

Abstract: Different parameters of Minimum Quantity Lubrication (MQL) system, including air pressure, oil quantity, nozzle position, might have different influences on the cutting force and the cutting temperature. This paper presents an experiment of end-milling titanium alloy with MQL system. The objective of the experiment is to investigate the influences of MQL parameters in milling of Ti-6Al-4V. The results of experiment show that there are different effects on the cutting force and the cutting temperature with different MQL parameters, which will help to select different parameters in the end-milling process of Ti-6Al-4V.

Abstract: When machining multi-frame complex components, more than 90% of the materials would be removed, resulting in severe distortion of the parts due to the weakened rigidity and the release of residual stress. This might also lead to stress concentration and damage of the parts. The effect of material removal from residually stressed billet is simulated using FEA software ANSYS, and the causations of distortion is analyzed. To verify the finite element simulation, a high speed milling test on aluminum alloy 7050T7351 is carried out. The results show that the simulation result is consistent with the experimental one. It included that the original residual stress in the blocks of aero-aluminum component is one of key factors to cause machining distortion.

Abstract: In this paper, SiCp/Al composites were fabricated by spontaneous infiltration technology. The micro-deformation behavior (MDB) of low tress in some silicon carbide particulate reinforced aluminum composites (SiCp/Al composites) was investigated experimentally. The microstructure, micro-deformation of samples was analyzed by OM and WDW-50 respectively. The results show that, in aluminum matrix with incorporating SiCp, the distribution of SiCp was uniform. In the same other conditions, SiCp size of the composite plays an important role on MDB at low stress, and the micro-deformation performance of the SiCp/Al composite increases with decreasing of SiCp size. MDB of composites at low stress deeply depends on the matrix material, and MDB increases with increasing of the matrix strength. It was also found that, the micro-deformation of SiCp/Al composite was negative value in the early stages of low tensile stress, and the phenomenon can be explained by strain relaxation.

Abstract: Research has been done on machinability of two different kinds of free-cutting steels by using coated cutting tool at the condition of different cutting parameters. Orthogonal tests are adopted in order to compare the cutting performance of the two materials. The cutting force, surface roughness, chip morphology and tool wear are investigated, which reveal the influence of Pb and other composition on machinability. The experiment shows that 1215 has more or less better performance than 12L14. It is of great significance for the development of environmental friendly products.

Abstract: TiB2-Ti(C, N)-(Ni, Mo) composite ceramic tool materials were fabricated by the hot-press sintering technology. The effects of the content of Ti(C, N) on the microstructure and mechanical properties were investigated by XRD and SEM observations. It is shown that the grain size of the composites is small, the fracture surface is irregularity, the grain boundaries of TiB2 and Ti(C, N) are connected tightly, and a new crystalline phase of MoNi is formed. A small amount of Ti(C, N) is decomposed into TiN, and the decomposition of Ti(C, N) is intensified as the content of Ti(C, N) is increased during the sintering process. The fracture pattern is the combination of the intergranular mode and transgranular mode. It is found that the flexural strength and fracture toughness of TiB2-Ti(C, N)-(Ni, Mo) composites increase consistently owning to the addition of Ti(C, N), the maximum resultant mechanical properties of TiB2-Ti(C, N)-(Ni, Mo) composites are 1019.53MPa for the flexural strength, 6.89MPa•m1/2 for the fracture toughness and 23.65GPa for Vickers hardness.

Abstract: Using electroplating CBN hard gear-honing-tools with standard involute, the vicinity of the workpiece tooth pitch circle will be a “mid concave” error, the root of the tooth will be a “dig root” error generally. For the formation factors of the error are more complex, it is difficult to calculate errors with an exact analytical method. To this end, by using Pro/E and ANSYS software, the contact analysis of electroplating CBN hard honing process was simulated. The honed tooth surface normal deformation analysis was the important means to determine extent of tooth profile error, through the normal deformation analysis based on simulation results, the location and extent of normal deformation was determined. Practice shows that the location and extent of the normal deformation has been a certain relationship with processing gear tooth profile errors. It is provided a theoretical basis to make the gear-honing tooth surface modification as possible.

Abstract: The globular indexing cam mechanism is a kind of high-speed and high-precision indexing mechanism, widely used in the field of mechanical transmission, which has the character of smooth transmission, high-precision indexing, large transfer torque, wider choice of dynamic and static ratio, simple structure and low cost, etc. In this paper, the working principle and the main movement parameters of globular indexing cam mechanism are analyzed, and the dynamics simulation of this mechanism is done by using ADAMS dynamic simulation software to analyze the influence of size parameters on the transmission performance, which provides reliable theoretical basis for understanding the property and designing the parameter of globular indexing mechanism.