Advanced Materials Research Vols. 472-475

Abstract: Based on the experiment of grinding cemented carbides end mill blade flute with diamond wheels, the effect of the viscosity of total-synthesis cutting oil on grinding process is studied under different feeding speeds and different cut depths. The results of the experiment have shown that grinding with the total-synthesis cutting oil of low viscosity can reduce the grinding force, improve the surface quality of workpiece, and reduce the wear of grinding wheels under the same grinding conditions. As the feeding speed and cut depth increase, maximum undeformed chip thickness of grinding is increased and grinding force gets higher, that leads to the worse surface quality of workpiece and the increased wear of grinding wheels.

Abstract: Surface defects detection is an important application of machine vision. In this paper, an online surface defects detection system of step-axis is studied based on image recognition. To ensure the real-time property, a fast axial surface defects inspection method is put forward, including improved median filtering to reduce noise, gray variation for fast judgment, the maximum variance method (OTSU) to select threshold automatically, contour features for feature extraction, mathematical morphology to detect defect targets, and finally, support vector machine (SVM) to classify and recognize the surface defects of ladder shaft. Experimental results show that the system can detect surface defects of the step-axis in 0.5s, which can meet the real-time requirements.

Abstract: Nowadays composite materials are used in many industrial areas. The main application of these is the aircraft industry. Problematic points with machining of composite materials are tool wear, tool life, delamination and temperature during machining of polymer composite materials. Paper focuses on investigation of delamination at drilling of glass fibre reinforced composites. Experiments were planned on the base so called design of experiment - DOE. We observed the evolution of delamination at investigations, when we combined 4 different variables (vc, fz, tool, cooling system). We investigated the evolution of force relations, torques, dimensional and shape accuracy, considering on delamination. We processed results statistically, for processing we used software MINITAB and MATLAB. We summarized results in tables and graphs.

Abstract: The technology of power ultrasonic vibration honing was used for the brittle hard sintered Nd-Fe-B materials in this paper. The feasibility and correctness of machining process was analyzed through experiments. Compared normal process result with orthogonal experiments, it was better to use power ultrasonic vibration honing to obtain parts with less surface roughness and higher material removal rate, and also the optimal processing parameters can be conduct. Therefore, the power ultrasonic vibration honing can be used to improve workpiece surface quality, as well as processing efficiency, precision, which is an effective method for precise machining of sintered Nd-Fe-B materials.

Abstract: To improve accuracy of computer visual inspection in keyboard automatic assembly line, a new two-stage camera calibration method was presented. 2D circle array was used as calibration plate, and centers of the circles were taken as feature points. And feature point coordinates were extracted without human interference. The proposed camera calibration method was divided into two stages. First, lens distortion was neglected, internal and external parameters of the camera were obtained by modified camera calibration toolbox for MATLAB. Then, lens distortion was taken into account, and improved genetic algorithm (GA) was adopted to optimize camera parameters gotten in the first stage. Experiment results indicate the proposed method is feasible, and can meet with requirements of the given application.

Abstract: Grinding strengthening and hardening can change and improve the ground surface integrity directly by the composite process of thermal load and mechanical force during process. The thickness and distribution of strengthening layer in ground surface makes the key role to measure the surface integrity of workpiece. The hardness and size of strengthening layer can influence the fatigue strength working life of the workpiece significantly. Based on the grinding strengthening test of 45 steel specimens, the strengthened layer microstructure, thickness and surface hardness were analyzed. This study illustrates the mechanism of grinding strengthened layer formation and also provides the theoretical basis for grinding strengthening and hardening layer quality control and grinding strengthening process making properly under small depth of cut conditions.

Abstract: The pretreatment process is quenching and normalizing, respectively. Influence of different original structures on tensile strength and hardness is investigated. The experimental results show that the as quenched 35CrMo steel by zero time holding quenching obtains fine lath martensite structure and has higher tensile strength and hardness. The mechanical properties of the as quenched 35CrMo steel is better than that of the as normalized 35CrMo steel. The effect of original structure on the mechanical properties of 35CrMo steel is prominent when the zero time holding quenching temperature is lower, but it decreases with the quenching temperature increasing. The austenite inverse transformation zero time holding quenched at low temperature can improve the mechanical properties of 35CrMo steel.

Abstract: The drainpipe cleaning robot is designed to replace the labour power to clean the municipal sewers automatically. Its main mechanical composition is the mobile carrier, cleaning tool, slide correction device, and cable following delivery and retraction mechanism, driven respectively by a stepper motor equipped with a photoelectrical encoder. Aimed at the unexpected and complex circumstances within the drainage pipeline and the undefined load, two new kinds of fuzzy control algorithms were presented to adjust the stepout of the carrier-driving motor resulting from the overload and the cable following delivery and retraction so as to ensure the stable and reliable operation. The design and simulation of the fuzzy controller were conducted by means of MATLAB and Simulink. The simulation results show that the expected control effect has been obtained because of the introduction of fuzzy control, and the control system has good robustness and anti-interference ability, which means that the fuzzy algorithms are feasible and effective.

Abstract: The validity of tool materials rapid selection based on initial wear for milling 300M steel were investigated under different cutting speed condition. Wear experiments of three tool materials selected from 17 tools suggested by the tool makers were conducted at three levels of cutting speed: low speed (100.5m/min), medium speed (150.7 m/min) and high speed (201.0m/min).Wear curves of the three tool materials are obtained through the above wear experiments. The relationship between tool performance and initial wear is analysed based on the obtained wear curves.

Abstract: In the cylinder of a sleeveless engine, molten iron-based alloy is directly sprayed onto the aluminum engine block instead of the previously used cast iron cylinder liner. However, a thermal spraying cylinder liner exhibits poor machining performance during the finish boring process because of severe tool wear. This research investigates the finish boring performance of a thermal spraying cylinder liner to clarify the root cause of tool wear. The results show that mechanical wear is a dominant effect.