Advanced Materials Research Vols. 1061-1062

Abstract: The as-cast grate bar structure used in sintering trolley is primarily comprised of austenite and eutectic (eutectic austenite and eutectic carbide).The austenite is dendrite, while the carbides are reticular and chrysanthemum-like. The failed grate bar structure primarily consists of ferrite, carbide, martensite and residual austenite; cavity shrinkage and shrinkage porosity exist in the structure, and the fracture exhibits typical cleavage fracture characteristics. The primary means of failure are abrasion and fracture. The secondary carbides precipitated in the sample (quenching (1050°C+2.5h)+ tempering (390°C+2.5h)) and the other one (quenching (1050°C+2.5h)+ tempering (420°C+2.5h) ) are dispersed and refined. Compared with the as-cast one, their relative abrasion resistance performances respectively are 0.8645 and 0.8752.The values of hardness and impact toughness of the samples heat-treated are greater than those of the as-cast grate bar. The optimum heat treatment process is as follows: quenching (1050°C,2.5h) + tempering (390°C~420°C,2.5h)

Abstract: The prototype can be produced from RP(Rapid Prototyping) technology directly by 3D data model, by dispersing and accumulating layer by layer principle, so the new product development cycle can be shortened greatly. RT (Rapid Tooling) technology is a new method and technology for rapid manufacturing mold, which is developed from RP technology. In this research, a rotary switch prototype was produced by laser stereolithography (SL) technology. Using the prototype as master pattern , a injection mold was made by metal casting method , using the composite composed of epoxy resin E51, aluminum powder, quartz powder , graphite and others, the manufacturing process was described in detail, and the ABS samples were successfully obtained through trial production in the injection molding machine.

Abstract: The gating system of an injection mold for car bumper was studied. A design optimization scheme is proposed to optimize both the number and locations of the gates by analyzing the filling process, in order to reduce the part war page and weld line, numerical simulation of injection mold filling process is combined with the design optimization method to find the optimum number of gates and their locations to achieve balanced f low and less weld lines while satisfying the limit of injection pressure. Moldflow software was applied to make analysis and comparison of various gating system in terms of their filling time, injection pressure and clamp force, weld line and distribution of air traps, and an optimized gating system was obtained. The result shows that this method can effectively reduce costs, shorten development cycle and improve the efficiency of molding design.

Abstract: The effect of dual adhesives to form multi-layer on the stress distributed in adhesively bonded single lap aluminum joint was investigated using elasto-plastic finite element method (FEM). The results from the numerical simulation showed that the values of the peak stress along the bondline are influenced evidently when there is a multi-layer formed by a middle layer with higher elastic modulus adhesive and two layers with lower elastic modulus adhesive.

Abstract: At present, the finite element method (FEM) is used to predict the residual stress distribution of the welding structure. A long computational time is required for the multi-pass welding structure with complex shapes. Therefore, it is necessary to develop time-effective finite element model and computational approaches. In this study, the suitable finite element model is developed to perform the thermal and mechanical analyses for obtaining residual stress data of the tube-plate welding structure with T-shaped sections. The results of the finite element analyses show that the residual stress distribution and radial, hoop and axial direction stress distribution of the welding structure.

Abstract: Nowadays, demand for automated Gas metal arc welding (GMAW) is growing and consequently need for intelligent systems is increased to ensure the accuracy of the procedure. To date, welding pool geometry has been the most used factor in quality assessment of intelligent welding systems. But, it has recently been found that Mahalanobis Distance (MD) not only can be used for this purpose but also is more efficient. In the present paper, Artificial Neural Networks (ANN) has been used for prediction of MD parameter. However, advantages and disadvantages of other methods have been discussed. The Levenberg–Marquardt algorithm was found to be the most effective algorithm for GMAW process. It is known that the number of neurons plays an important role in optimal network design. In this work, using trial and error method, it has been found that 30 is the optimal number of neurons. The model has been investigated with different number of layers in Multilayer Perceptron (MLP) architecture and has been shown that for the aim of this work the optimal result is obtained when using MLP with one layer. Robustness of the system has been evaluated by adding noise into the input data and studying the effect of the noise in prediction capability of the network. The experiments for this study were conducted in an automated GMAW setup that was integrated with data acquisition system and prepared in a laboratory for welding of steel plate with 12 mm in thickness. The accuracy of the network was evaluated by Root Mean Squared (RMS) error between the measured and the estimated values. The low error value (about 0.008) reflects the good accuracy of the model. Also the comparison of the predicted results by ANN and the test data set showed very good agreement that reveals the predictive power of the model. Therefore, the ANN model offered in here for GMA welding process can be used effectively for prediction goals.

Abstract: The research of recycling Ti-6Al-4V alloy industry scrap is conducting by hydrogenation and hydride sintering process. The Ti-6Al-4V alloy scrap was submitted to a activation treatment under vacuum atmosphere and hydrogenation process under pure H₂ gas, the hydrogenated product was attained. Sintering process used hydrogenated titanium alloy powder as a feedstock material. The oxygen content of raw scrap, hydrogenated Ti-6Al-4V alloy powder and as-sintered Ti-6Al-4V alloy was 0.107%, 0.256% and 0.117%, respectively. Compression and Vickers hardness tests were conducted on the as-received and as-sintered Ti-6Al-4V alloy to evaluate their mechanical properties.

Abstract: Compared with conventional push drilling, helical milling (orbital drilling) shows great advantages in aeronautical hard-machining materials hole making. However, helical milling of titanium alloy and carbon fiber reinforced plastic (CFRP) under dry cut condition still faces challenges such as burr of titanium alloy hole exit and CFRP hole delamination. In order to solve these problems, an innovative helical milling tool with distributed multi-point front cutting edge is designed based on the chip-splitting mechanism and tool movement feature. The description of cutting edge movement track and simulation of chip shape is used to analyze different functions of front and peripheral cutting edges, the chip-splitting result and the specialized tool's service life. The helical milling experiments are aimed to test the performance of the specialized tool compared with that of traditional end mill. Results show that the specialized tool can machine titanium hole free of burr and CFRP hole without delamination under dry cut condition. The specialized tool has a longer service life with its machining capacity amounting to 80 titanium holes and 65 CFRP holes..

Abstract: The submitted paper deals with examining the influence of technology head shift speed, abrasive kind and granularity on AWJ technology head vibration generation during manufacturing process of hard-to-machine material Hardox 500 of various thickness. The aim of the paper is to point at an early diagnostics and elimination of unwanted sources of vibration being generated on a technology head due to technological and technical parametre changes and a following design of optimal technological parametres for AWJ technology cutting.

Abstract: The following paper analyses effects of pressure values of a high pressure pump on technology head vibrations origin at hydroabrasive erosion in production process. The aim is to focus onto one of possible sources of undesirable vibrations which can be subsequently influencing the cutting surface quality.