Advanced Materials Research Vols. 154-155

Abstract: In this paper the clamping forces of the HSK-E50 toolholder-spindle interface was first analysed and found the FEM analysis model. Then calculated the stress distribution of toolholder-spindle interface respectively effects by the spindle speed, interference and pull in force and finally find out how this three factors influence the connection characteristics of HSK-E50. The research results provide the designer a theoretical basis for designing and applying HSK tool system of the high speed spindle.

Abstract: Research in polymer gel is very popular recently, for instance, polyacrylamide (PAM). PAM gels are well-known for their highly water-absorbent properties. They are usually used as thickeners, suspending agents, soil erosion control reagents etc. In this study we investigated effects of the pH value of PAM solution and the charge density of PAM on morphologies of PAM films. Morphologies of PAM films adsorbed onto the glass surface were obtained with an atomic force microscope (AFM). The experimental results indicated that morphologies of PAM films might vary strongly with acidities of PAM solutions. The base-treated PAM formed tassel-like patterns, the acid-treated PAM existed as grains of various sizes, and the as-received PAM had uniform small ball-like shape. A film flow model was used to explain the experimental results.

Abstract: As a non-homogenous force stresses during incremental forming, sheet metal easily tended to instability, and some defects, such as deposition, wrinkle and fracture, would appear. If the vibration technique was combined the incremental forming process, its deformation mechanism would be different from that of the old process, and sheet metal deformation quality was also risen. Then some mechanical equations were built by force analyzed on element in local contact zone of die head forcing down. According to reasonable hypothesis and simplified, the equations were solved. Some stress-time curves of the element were obtained by given process parameters, vibrational parameters and time parameters. It is shown from analysis that stress variety of the element is closely related to amplitude, frequency and forming angle, effect of sheet metal vibration incremental forming with high frequency vibration is more superior than that of with low frequency vibration; only when vibrational parameters are reasonably matching technical parameters, the effective vibration incremental forming can be obtained.

Abstract: For bloom casting, typical quality defects such as midway crack usually occur upon improper cooling control during non-steady casting conditions specially for the production specialty steels,. A key measure to eliminate the defects formation has been presented by the adoption of more sophisticated secondary cooling strategies to balance the surface reheating due to casting speed fluctuation. With the consideration of the complex casting conditions and the characteristics of bloom casters, a dynamic control model for the secondary cooling has been developed in the paper to obtain a reasonable temperature profile and solidification progress for the bloom casting process, which is based on a slice residence time method combined with a multi-level control strategy. The feedback system, based on the difference between the calculated surface temperatures and the predetermined or measured surface temperatures, has been integrated into two-dimensional thermal model. The interlocking protection system between level-1 and level-2 is included in the model together with the data diagnosis and processing. Furthermore, the control model also offers technological interface for the introduction of new steel grades in production and the related modification to the secondary cooling parameters. It is shown from online application that the dynamic control system of secondary cooling for bloom casting is robust during operation and adaptable to any change of real casting conditions. Sound quality bloom castings according to acid etched tests have been obtained from the caster accordingly.

Abstract: Adopted the method of vacuum sintering liquid-solid phase reaction to prepare metal-ceramic coating, focused on the microstructure, phase composition and performance of the coating, which was prepared by two kinds of binding phase materials. The results showed that: the coating, obtained by reaction sintering of cobalt-boron alloy and self-molten Fe-based alloy composite binding phase, had compact structure. WC hard phase of the coating didn’t have phenomena of burning loss, decarbonization, agglomeration and growth. WC phase was completely circle-molten by γ-Co primary solid solution and γ-(Co, Fe, Ni) supersaturated solid solution. Newly generated granular and lath-shape hard phase evenly dispersed in binding phase, which increased the wear resistance of the coating substantially. The relative abrasion of ceramic-metal coating prepared by composite binding phase was nearly 50% lower than the one prepared by Fe-based binding phase.

Abstract: Cold rolling precision forming process of spline is one of the high-efficiency, precision and non-chip forming advanced manufacturing technologies. It has the characteristics such as high forming efficiency, energy-saving, low material consumption and better forming properties of components. The principle and the force of involute spline cold rolling precision forming process were analyzed. Forming experiments of involute spline cold rolling were carried out, and the microhardness map of the tooth outline was gained. The rule of the metal flow in the deforming area and the forming mechanics of the microstructure were analyzed. The influence of plastic deformation on the forming properties was also conducted. Experimental results showed that dramatic plastic deformation has taken place on the upper surface of the workpiece during the cold rolling process of spline, while the influence on the inner materials were very small. The grains were distributed as a flow line pattern along the tooth profile, and the grains in the plastic deformation zone presented a fine and long fibrous state. The hardness on the section of the tooth outline is regularly distributed. Compared with the spline components obtained from conventional cutting method, the hardness of the spline was greatly increased, therefore, comprehensive mechanical property such as wear resistance and impact resistance were largely improved. Precision measuring and hardness testing of the tooth outline section showed that the components obtained by the experiments were free of defects, and the application requirement can be satisfied.

Abstract: The soft abrasive flow machining was proposed for solving the problems of difficult contact finishing in course of mould manufacturing. It could reach the specular level and control turbulence abrasive flow. Based on the topological structure transformation of LSM, a two- dimensional model of the two-phase flow is established. This mechanics model with the SIMPLE (semi-implicit method for pressure-linked equations) algorithm incorporated is used to simulate the movement of the turbulent flow by using of k-ε model. The computed results show that this 2D model can preferably simulate the movement of the two-phase flow, and the characteristic parameters of abrasive two-phase flow are derived.

Abstract: The unloading spring-back of tubes during its manufacturing process shows a strong nonlinearity, which greatly influences the precision of parts. In this paper, the strain distribution of bending tubes was analyzed based on the elasto-plasticity theory, and the theoretical equation for spring-back of tubes was derived. The numerical simulation model for cold tube-bending process was developed with prediction error of 9% compared with experimental results, indicating high reliability of the model. The 12Cr1MoV and 20G tubes were used to analyze the effects of bending angle, bending radius and bending speed on the spring-back of tubes. The prediction equation of spring-back was built, which shows that the spring-back tendency was in accordance with theoretical analysis results. The simulated results show that the spring-back angle is linearly proportional to the bending angle within a certain range. In addition, it is proportional to the relative bending radius and the bending speed.

Abstract: In order to produce new generation monolayer brazing CBN(cubic boron nitride) grinding wheels, an active filler alloys(Ag-Cu-Ti) were tested in vacuum furnace. The results show that Ag-Cu-Ti alloy exhibits good wetting and bonding toward as CBN grits. SEMEDS microanalyses have shown that during brazing Ti in Ag-Cu-Ti alloy segregated preferentially to the surface of the CBN to form a Ti-rich reaction produce. X-ray diffraction reveals that the wetting and bonding behaviour on CBN surface by Ag-Cu-Ti alloy melt is realized through TiN and TiB2 which is produced by interaction between Ti atoms of Ag-Cu-Ti alloy and N or B atoms of CBN surface.