Applied Mechanics and Materials Vols. 34-35

Abstract: In continuous hot dip galvanizing, serving parts working in the molten zinc, such as sink roll, sleeves, etc. tend towards degradation and failure due to corrosion and wear. In this paper, corrosive wear performance of several materials, such as boronized，H13，Co-based alloy and Fe-based alloy coupled with Si3N4 is evaluated with the aid of a self-made test machine of block-column sliding wear. Moreover, the corrosive wear mechanism is analyzed. It has been found that these materials suffered not only considerable wear, but also the corrosion of molten zinc. For boronized layer, the wear is the main reason to cause the failure of work parts under the act of the corrosive wear. For H13, the interaction between corrosion and wear plays a very important role on its failure. For those alloys with bad corrosion resistance such as Co-based alloy and Fe-based alloy, both corrosion of solid solution and wear of intermetallic compound act on their failure at the same time. However, the rate of wear shows no obvious relation to the hardness although wear performance is important. The failure greatly lies on the ratio of the hardness of corrosion products to matrix.

Abstract: A spectral absorption of the ferrous ion in fluxing was investigated in this paper due to the significant effect of ferrous ion on the quality of hot-dip galvanizing production. Based on analysis of spectrophotometry, an automatic detection equipment of ferrous ions is developed according to its special characteristics. On-line measuring of ferrous ion in fluxing of the hot-dip galvanizing is realized by the micro-pump and the equipment. Results show that the lowest limit to be detected is 0.1 g/L, measuring errors are less than 0.05 g/L, the linear equations of the absorption and concentration of the ferrous ions shows a good correlation coefficient which is 0.99995 when the ferrous ions concentration is between 0.1g/L and 10g/L in fluxing.

Abstract: Cryogenic minimum quantity lubrication (CMQL) is a kind of green cooling/lubrication technique, which consists of the application of a small amount of lubricant (6-100 ml/h), delivered in a refrigerated compressed gas stream to the cutting zone. This paper experimentally investigates the effect of CMQL on cutting temperature and tool wear in high-speed end milling of titanium alloys. Comparative experiments were conducted under different cooling/lubrication conditions, i.e. dry milling, refrigerated air cutting, and CMQL. The refrigerated gas equipment was manufactured based on composite refrigeration method to provide the refrigerated air. The experimental results show that application of CMQL resulted in drastic reduction in cutting temperature and tool wear especially when machining titanium alloys at a high cutting speed.

Abstract: This paper resolves spatial RSSR mechanism in D-H coordinates to obtain its position equations. By extending Roberts-Chebyschev Theorem, it is demonstrated mathematically that RSSR mechanism possesses the same character as planer four-bar linkages in generating cognates. Considering strict requirements of spherical hinges in manufacture and assembly, this paper then addresses substitution methods of spherical hinge in RSSR mechanism, including constraining DOF of spherical pair by specific structural dimensions and replacing high pair by combinations of low pairs, while taking examples of sphere 4R mechanism, spatial orthogonal crank-rocker mechanism and spatial 6R mechanism in dobby machine. Physical kinematic simulation is done in the environment of MSC.ADAMS to validate the feasibility of spherical hinge replacement, providing guidance and reference to future design of complex spatial mechanisms.

Abstract: In order to explore the cutting rule of hard-to-machine material austenitic stainless steel and to optimize cutting parameters, multiple sets of parameters of austenitic stainless steel cutting were schemed out by using uniform design method. Test cutting researches of cutting forces, surface roughness and cutting efficiency with these parameters were conducted under the condition of dry cutting. On this basis, multi-objective optimization model of cutting force and surface roughness applied to austenitic stainless steel had been set up by multiple regression analysis. Variance analysis showed that these formulas have highly significant linear relationship. Verification test is done under the optimal cutting parameters, and the results of cutting forces and surface roughness are in good agreement with the calculated. Turning efficiency is improved by 23.4%, compared with the actual cutting parameters of past production.

Abstract: When designing motorcycle engine, engine cylinder head abnormal noise is common, and difficult to eliminate due to thermal expansion and contraction of the aluminum alloy cylinder head. In this study, on the basis of dynamic change with the performance of 157FMI engine in hot and cold, the reasons for engine cylinder head abnormal noise are analysed, and valve plunger with variable length is applied to minimize the valve clearance, and to make the valve clearance of engine in cold and hot zero, and thus the noise problem of cylinder head with 157FMI engine in hot is completely eliminated.

Abstract: The positioning system with high acceleration and high precision determines the speed and quality of bonding, which is the core component in a wire bonder, and influences the cost and reliability of the chip. The mode characteristics of the high acceleration and high precision positioning system were analyzed using ABAQUS. The results show that the system has different vibration characteristics in different resonance mode, and also has the features of mode denseness and complicated vibration mode.

Abstract: In order to investigate the effect of splicing shape and splicing interval length of reinforced fabric on the mechanical performance for manufacturing composite parts in complicated shape with laminated 2D glass fiber woven fabric. On the basis of [0º/45º/90º/90º/0º] S ply sequence, six kinds of laminated performs with different splicing interval lengths which were 4mm, 8mm, 12mm respectively and two different splicing shape which were ladder splicing (LS) and double vertical line splicing (DLS), and a kind of laminated perform with continuous laminates (CL) of 2D glass fiber woven fabric were made. By means of RTM molding technology, the technological parameters of RTM processing were designed as follows: injection temperature was 25°C, injection duration time was 180min and injection pressure was 0.4MPa, the epoxy resin based 2D glass fiber woven fabric RTM laminated specimen were prepared. According to the GB/T 1447-2005 and GB/T 1449-2005standard test method, the tensile and flexural properties of the 2D glass fiber woven fabric laminated RTM specimen were tested. It was found that the tensile fracture position were all near the splicing line, the main reason of which was the concentration of tensile stress. The tensile and flexural test results show that the difference of the splicing shape and the splicing interval length will generate a significant effect on the mechanical performance of the laminate. All above experimental results could provide fundamental data to the optimal design complex structure laminated composite parts.

Abstract: Analyzed vibrating screen’s dynamic characteristics of determinate structure and statically indeterminate structure, calculate natural frequency, natural vibration mode and dynamic response based on finite element technology. The results show that the vibrating screen’s structural strength is increased and the natural frequency of bending and twisting deformation is improved by means of the adoption of statically indeterminate structure. The natural frequency is far from work frequency which means the structure can avoid resonance effectively. Statically indeterminate structure provides a big structure intensity and stiffness to meet vibrating screen’s needs in the design process.

Abstract: This research paper presents an experimental investigation on the tensile strength loss rate of glass fiber reinforced 2D woven fabric with ladder splicing laminate composites. On the basis of three kinds of ply sequence, two series of laminates with different plies numbers were prepared through RTM molding technology, including ladder splicing(LS) laminates and continuous laminates (CL). And the RTM technological parameters of RTM processing were designed as follows: injection temperature was room temperature, injection duration time was 180min and injection pressure was 0.5MPa, the epoxy resin based 2D glass fiber woven fabric RTM laminated specimen were prepared. According to the GB/T 1447-2005 standard test method, the tensile tests of the 2D glass fiber woven fabric laminates were carried out. Results show that the tensile strength loss rate of ladder splicing laminates is 11.05%, 9.37%, 7.78% while the number of plies is 8, 10, 12 respectively. In other words, the tensile strength loss rate is reduced with the plies number increasing. In addition, because of the concentration of tensile stress, all fractures of ladder splicing laminates occur at the site of splicing line.