Advanced Materials Research Vols. 189-193

Abstract: The drawing properties of the modified PA 6 (MPA) fiber specimens prepared at varying drawing temperature were systematically investigated, wherein the MPA resins were prepared by reactive extrusion of PA 6 with the compatibilizer precursor (CP). At any fixed drawing temperature, the achievable draw ratio (Dra) values of MPA as-spun fiber specimens increase initially with increasing CP contents, and then approach a maximum value, as their CP contents are close to the 5 wt% optimum value. The maximum D_ra values obtained for MPA as-spun fiber specimens prepared at the optimum CP content reach another maximum as their drawing temperatures approach the optimum drawing temperature at 120 °C. The tenacity and birefringence values of PA 6 and MPA fiber specimens improve consistently as their draw ratios increase. Similar to those found for their achievable drawing properties, the ultimate tenacity and birefringence values of MPA fiber specimens approach a maximum value, as their CP contents and drawing temperatures approach the 5 wt% and 120 °C optimum values, respectively. Investigations including Fourier transform infrared, melt shear viscosity, gel content, thermal and wide angle X-ray diffraction experiments were performed on the MPA resin and/or fiber specimens to clarify the optimum CP content and possible deformation mechanisms accounting for the interesting drawing and ultimate tensile properties found for the MPA fiber specimens prepared in this study.

Abstract: This research takes Eucalyptus grandis×E.urophylla timber as materials, making them drying with five kinds of schemes. Five experimental schemes are taken as follows: natural air drying, solar energy with storing heat, solar energy without storing heat, solar energy with electric heating during the day, solar energy during the day and electric heating during the night. Experiments have found that: in normal sunny weather conditions, the temperature of solar drying completely satisfies eucalyptus wood drying demand. Energy saving ratio is above 60%; In weaker solar radiation intensity conditions, drying needs to use auxiliary power. Energy saving ratio is about 47.1%. The period of Solar drying is 3/4~1/3 shorter than that of natural air drying. Dry defects were obviously reduced. It has the good prospects for development.

Abstract: Instead of 2D expanding diagram method, this paper presents a new regenerating method for cutter location paths of using smaller tools to produce cylindrical cams. According to the expected motions, cams are put to use in various applications in mechanism. For a cylindrical cam, the roller follower operates in a groove cut on the periphery of an end mill with the diameter same as the roller. By using the conventional method, full-sized cutting tools, will restrict the flexibility of choosing cutting tools for wide roller guide. The manufacture of cylindrical cams is complicate and precise work that depends on the generating method and types of machine tools employed. Since the guiding curve cannot be offset exactly along the cylindrical surface, this leads to some approximating problems. Though the tool-paths generation by using the same size tools as rollers is applied in practice, the study of NC program by unequal tools is not available to meet high precision requirement. This proposed 3D offset-based generating method can regenerate tool-paths for standard cutting tools instead of larger ones and implemented on computerized CAM system. Examples with wider grooves are demonstrated to prove its effectiveness.

Abstract: In this research, high efficiency machining tool path design of die cavities were developed using CAD/CAM and plunge roughing technology. The algorithms of cutting tool path design for ideal and non-ideal rouging area were proposed to improve the material removal rate (MRR). The proposed tool path design methods are based on the minimum numbers of rectangular or triangular patterns to cover the roughing areas. The cutting results of the traditional Z-plane and the plunge roughing were compared to show the improvement of the cutting efficiency with the proposed methods. Design of experiments (DOE) method was adopted to optimize the tool path designs and cutting conditions. Cutting experiments were carried out to verify the proposed cutting path design methods. The better material removal rate was obtained using the proposed plunge roughing method compared to the traditional Z-plane roughing. Both of the cutting simulations and the cutting experiments also showed the cutting efficiency of plunge roughing is increased with increase of cutting depth. The proposed hybrid tool path design method can further improve the cutting efficiency of plunge roughing process.

Abstract: The objective of this study was to utilize Taguchi methods to optimize surface roughness, tool wear and power required to perform the machining operation in turning metal matrix composites (MMC). The cutting parameters are analyzed under varying cutting speed, feed rates and cutting time. The settings of turning parameters were determined by using Taguchi’s experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA) are employed to find the optimal levels and to analyze the effect of the turning parameters. Confirmation tests with the optimal levels of machining parameters are carried out in order to illustrate the effectiveness of Taguchi optimization method. The results show that the Taguchi method is suitable to solve the stated problem with minimum number of trials.

Abstract: Orthogonal cutting experiments of hardened AISI1045 steel(45HRC) are performed to investigate the influence of cutting conditions on adiabatic shear which occurs in the process of chip formation of many materials. It is found that the cutting speed, cutting depth and rake angle all have influence on adiabatic shear and there is a critical cutting speed at which the adiabatic shear appears. By metallurgical observation, the critical cutting speed under different cutting depths and rake angles are given. A model based on linear pertubation analysis is used to predict the adiabatic shear critical cutting conditions of hardened AISI 1045 steel. The comparison of prediction results and that of expriments shows that this prediction model is valid.

Abstract: This paper depicts the types and functions of cutting fluid, compared functions, advantages and disadvantages with several other cutting fluids. According to the characteristics of BTA deep-hole machining and cutting fluid requirements, some of cutting fluids were chose to do the drilling test. In order to satisfy the lubrication and cooling effect of the cutter, the oil-in-water type cutting fluid which through a comparative analysis of the experiment was used in the deep-hole machining, in the meanwhile, it can reduce the economic costs and environmental pollution.

Abstract: The traditional cast-type method of BTA deep-hole drilling(such as BTA or DF) has cutting fluid consumption of the existence of large, high production costs, pollution of the environment and endangering the health of the operator and other problems. In this paper, the MQL technology (minimum lubrication technology) is applied to the method of BTA deep-hole machining (ie, near-dry deep-hole processing), we also analyzed the function and effect of MQL machining cutting fluid. Through the near-dry deep-hole drilling experiment, we find that a water-soluble cutting fluid has good atomization effect and the processing system also has fine effect of cooling and chip evacuation. We proposed mixed-use oil and the low-temperature cold spray methods to improve the tool lubrication and cooling effect for some great issues such as tool wear.

Abstract: This experiment has taken a research on the conductivity changes of 7075 aluminum alloy after being extruded and two-step aging treatment,and has done a analysis on the theory and rules of the impact on conductivity performance under the two-step aging treatment.Compared to cast aluminum alloy and extruded aluminum alloy without two-step aging process,the experiment showed that extruded alloy with two-step aging treatment has the highest conductivity about 44% IACS, 33.3% more than under casting condition and 22.2% more than only being extruded.

Abstract: To compare the effects of different machining parameters on force in milling T10 hardened steel, the features of theoretical forces in up and down milling were analysised, and comparative experiments of milling force were made, whose results showed that the maximum component force in down and up milling was in the direction of radial cutting depth and feed respectively, moreover the maximum force in down milling was significantly greater than in up milling. Further orthogonal experiments of up milling and variance analysis were done, and it was found that the effects of rake angle, velocity, feed, axial cutting depth on milling force were significant at levels of α=0.05~0.0025. This study indicates that selecting milling parameters of up milling, high speed, low feed and axial cutting depth be better. This conclusion can be used as reference in designing milling scheme.