Applied Mechanics and Materials Vols. 201-202

Abstract: The rolling force will directly have influence on the size of high-neck flange and whether the rolled part will be shaped successfully. Finite element model of closed ring rolling high-neck flange was established, the effect of process parameters on rolling force and its reasons are analyzed. The results show that, the higher feeding speed is, the larger the amplification of rolling force will be, in addition, rolling force will be reduced slightly with the increase of rotational speed of driving roller, and the influence on the rolling force of compressing roller’s feeding speed is much larger than driving roller’s rotational speed.

Abstract: In view of the fracturing occurred at the welded joint of the belt conveyor roller while being in use in a coal mine of Fujian Province, the paper analyses the roller’s structure and stress in the basis of the transmission principle. It explores the reasons of the fracturing problem, and then proposes method to improve the roller’s welding technology. These are the cause of the roller fracturing，which the tension of the belt is great, and the roller itself is not strong enough, and welding process of steel plate is poor, and welding quality is not high. Use CO2 and Ar mixed gas shielded arc welding to do backing weld, then use the welding method of automatic submerged arc welding. Finally the tempering to the welded joint part with the track-type far-infrared heater eliminate the welding residual stress. By actual use, it’s proved that the Welding Process Improvement is feasible, reasonable, reliable and practical.

Abstract: Plume images which captured during the high power disc laser welding contain lots of information that related to the welding quality and stability. The classification of plume images is an important foundation for online monitoring during welding process. Stainless steel 304 was taken as the experiment object for the high power disc laser welding experiments. A high-speed camera was used to capture the ultraviolet band and visible light band plume images in the laser welding process. Image processing techniques were applied to get the characteristic parameters such as the ratio of the absolute value of coordinate difference between the centriod of plume and the welding point, the number of spatter, the average gray level and entropy of a spatter image, and formed a four dimension vector. Then K-nearest neighbor classification method was used to separate the poor welding quality images out from good ones. Welding experimental results confirmed that using K- nearest neighbor classification method to classify the four dimension vector samples which formed by the ratio of absolute value of coordinate difference between the centriod of plume and welding point, number of spatters, average gray level and entropy could obtain a recognition rate that close to the actual welding results.

Abstract: In order to satisfy the demand of increasingly stringent emission regulations and enhance fuel economy and increase dynamic performance of vehicle diesel engine, the working parameters of electronic controlled diesel engine should be changed properly. An electromagnetic actuator controlled system was designed based on DSP56F807. The control strategy of fuzzy-PID and fuzzy control model for electro-magnetic actuator was established. The control effect of fuzzy-PID for electro-magnetic actuator and diesel engine was validated through experiment. Experimental results showed that good static and dynamic control effect can be obtained using fuzzy-PID control method.

Abstract: On the basis of compliant polishing device for aspheric, a new method of bonnet polishing on magneto-rheological of torque servo driver has been proposed. It has introduced the bonnet polishing composition and polishing principle. Polishing tool using the flexible bonnet, it can better adapt to the different curvature change of parts, and the stable polishing force can be get through MRT. Combining the constant torque device on MRF with CNC machine, this embodies high rigidity, higher precision of NC machine and reflects the MRT with adjustable, controllable, rapid response characteristics. The formulae of stress and relative velocity of polishing are deduced, and the material removal rate model has been set up. The experimental results show that this new method of bonnet polishing can provide stable polishing force, and the model is correct, has good prediction ability.

Abstract: Cavity defects of low-pressure lost foam casting (LP-LFC) for magnesium alloy were investigated by using ladder samples and claviform samples.The physical feature of typical cavity defects of LP-LFC for magnesium castings had been tested by optical microscopy and scanning electron microscopy. And the chemical constitution of cavity surface was also tseted by energy spectrometer. The result indicated that the cluster cavity defects were formed with the application of higher vacuum at the metal-mold interface, which caused the liquid-EPS residue in the castings. Some irregular shape cavity defects were caused by slag entrapment or coating slough. These cavity defects could be avoided through reducing pouring temperature, filling velocity and vacuum level, improving the permeability of coating.

Abstract: The mold for cross wedge rolling (CWR) is difficult in making, complicated in adjustment and high in costs. It is extremely meaningful to optimize the parameters for wear reduction to extend the mold life. This paper analyzes the influence of the processing parameters on the mold wear based on orthogonal experimental design method and the computer simulation method, which can optimize the parameters in an efficient and simple way. The results show that the rolling process using optimized technological parameters can greatly extend the mold life of the cross wedge rolling.

Abstract: Laser ablation is a new, very flexible process for micro-fabrication of micro-moulds and other micro-system devices. This process is suitable for machining difficult-to-machine materials, like ceramics, dielectrics, carbide and hardened steel with excellent productivity and surface. The paper presents the investigation on the material removal rate of aluminium 5754 using a nanosecond Nd:YAG laser with a wavelength of 1064 nm.

Abstract: The feature of the gear shaft with Cross wedge rolling technology is high efficiency, low material loss and higher strength of the gear shaft forming. A research model of cross wedge rolling plastic forming adopting tri-dimensional thermal elastic-plastic finite element method is put forward. Forming mold divided into two parts as the wedge-shaped molds and tooth mold is designed. Depending on orthogonal test program, applying Deform-3D to numerical simulate for the gear shaft with cross wedge rolling, the influence of temperature, number of teeth, module and feet rate for gear shaft tooth forming quality is studied. The results are analyzed with the temperature of the workpiece, number of teeth, module and feet rate of the die movement during CWR and the best combination of produce conditions is reached.

Abstract: High-speed injection molding technology refers to the injection speed of rotating screw is about 500mm ~1000mm/s during the injection process. It is extensively used in the fabrication of thin and accurate products, for example, packing containers, CD or DVD disc-based panels, smart cards, optic fiber connecters, etc. In this paper, the advantages of high-speed injection molding technology on cost savings, product quality and productivity are presented firstly. Then the mold characteristics on strength, stiffness, precision, used material, heat treatment, the runner system, the venting system and the ejection system are illustrated. A plastic flowerpot by high-speed injection molding is selected as an example to show the high production efficiency.