Applied Mechanics and Materials Vols. 217-219

Abstract: A finite element simulation of convex tablet compaction was present in this paper with Drucker–Prager Cap model of lactose material. The effects of different compression speed on tablet property were analysis. The results show that the maximum stress appears the top and bottom near the die and the mises stress distribution become more uniform with the speed decreased. The density distribution change little with the variation of compression speed and the maximum density locate the top and bottom near the die rim. The compression speeds have little affected on the powder displacement. The research can contribute to save cost for tablet production test through the simulation analyze the tablet property of compression process.

Abstract: As the trend of electronic industry is fast moving towards miniaturization, diversity, high efficiency and high throughput, the devices to be mounted onto a PCB are increasingly densely packed so are the holes needed to keep all elements in place. To effectively and economically generate so many holes of small diameter and high aspect ratio, the drilling process has to be done in a high speed manner and tool life has to be kept as long as possible. This study aimed to improve the tool life and the quality of the obtained holes by applying various hard coatings on the drills. The results showed that tool life could be effectively improved from 2500 hits to around 11000 hits at 155Krpm and 3.5m/min when proper hard coating was applied. It was found that wear of drill was resulted mainly from abrasive wear and adhesion wear. It was also showed in the research that while non-coated drills suffered serious deformation after 500 hits those coated with Al2O3 could finish 11000 hits with very limited wear land on the drills.

Abstract: This paper aims at the research on deformation control technology in truck rack girder. Welded deformation is minished through special welding fixture design and welding process control, thus to improve the size precision of the truck rack girder and ensure the running safety of the vehicle.

Abstract: The cutting tool geometry and cutting parameters have a great impact on cutting force, while cutting force is an important factor which affecting the tool life. High speed cutting experiments have shown that when slight axial depth of cut is adopted, rake angle effect on main cutting force significantly. When cutting aluminum alloy, the roughness of machined surface decrease with increasing tool rake angle. The axial depth of cut does not have a big influence on machined surface ’s roughness.

Abstract: This study aims to fabricate the plano-convex lens by glass molding process using a through-hole WC/Co plate as the mold. The effects of temperature, applied loadand arc chamfer on the surface morphology, curvature, and peak height of plano-convex lenses were investigated. The through-hole mold with arc chamfer favors stress release and avoids cracks and surface mark. A higher temperature favors glass material flowing outwards rather than downwards, which results in the molded lens with a smaller curvature and bigger size.

Abstract: Nowadays, customer has more and more requirements of quick product updating. On the opposition side, casting need a long lead time for tooling prepare and qualify. And a necessary test for casting is need. Whether a new casting design or existing casting product revised will take 16 weeks with tradition process. A new method raised in this text can help solute these problems. It calls Rapid & flexible process loop including CAD, CAE and RP. A better cost and time saving can be achieved via it.

Abstract: During the process of rapid prototyping based on robotic pulse MAG forming, the coefficient of weld reinforcement is crucial to the geometric accuracy and mechanical property of metallic parts. The orthogonal design method, as well as the range analysis and variance analysis, were applied in this article to study the effects of wire feed rate, welding speed, pulse correction and arc length correction on coefficient of weld reinforcement, finding out the factors which were significant to the coefficient of weld reinforcement and optimizing the process parameters. The experimental results show that the order of the significance of parameters is as following: the welding speed, the arc length correction, the wire feed rate, and the pulse correction. Among them, the welding speed and arc length correction have the greatest influence on the coefficient of weld reinforcement, as is 0.025. The optimal process parameters are: arc length correction 8%, welding speed 14mm/s, wire feed rate 7.2m/min and pulse correction 0. At the same time, the coefficient of weld reinforcement is between 2.94 and 3.00, as the degree of confidence is 97.5%.

Abstract: The response of adhesively bonded lap-joint under transverse impact was investigated by means of DYTRAN software. A finite element model was developed based on cohesive failure in the adhesive layer of the joint. It was found that transverse impact results in shear and peel stress concentration in the adhesive due to the considerable deflection of the joint. The stress distribution in the adhesive layer was asymmetric along the overlap length direction. The peel stress varies from tensile to compressive from one side to the other. Two cracks initiated at two sides of the adhesive layer were observed before the failure of the joint.

Abstract: Forging processes have been studied since years. However, recently these studies are gaining in importance because of the increasing emergence of non conventional forging processes such as LIF processes, in order to improve their efficiency and to fit the production requirements. In this work elementary forging processes are studied under plane strain conditions in order to evaluate the combined effect of strain hardening and friction in forces and contact pressure distributions by a FE analysis. For this purpose, different base to height ratios (b/h) of the workpiece have been considered, with different friction conditions. All cases have been solved for both a rigid perfectly plastic material and a strain hardened one. It is observed that the effect of the strain hardening on the forces and contact pressures is higher when the friction conditions become more extreme. The results do not depend on the base to height ratios when frictionless conditions are assumed.

Abstract: The existence of debris in the inter-electrode area in micro-EDM interrupts the machining process. Applying ultrasonic vibration to the machining fluid helps circulate the machining fluid and remove the debris from the gap area, and thus reduce short-circuits and abnormal discharges. In this study, the effect of applying ultrasonic vibration to machining fluid in micro-EDM was experimentally investigated. It was found that a significant increase in the machining speed was realized by applying ultrasonic vibration. Also, with the vibration of the machining fluid, micro-hole drilling with ultra-small discharge energy became possible.