Key Engineering Materials Vols. 364-366

Abstract: High speed machining is very popular and widely used in industry recently, and it has been accepted as a key technology for die and mold steel manufacturing because it has much advantage as compared with conventional machining such as low cutting resistance, low cutting heat generation and high production rate, etc. The finite element method is utilized in this study to simulate the processes of chip formation during high speed machining of SKD11 die steel workpiece step by step from an incipient of tool-workpiece engagement to a steady state of chip formation. The effects of different combinations of cutting conditions such as cutting velocity, feed rate, rake angle and nose radius of the tool on the curly types of chip formation are investigated thoroughly for establishing the related skill for high speed machining or for predicting the chip morphology in advance.

Abstract: This study discusses the high speed turning of the hardened mold steel by ceramic cutting tools. From the experiments, we can understand the tool wear condition, tool failure mode and the surface roughness variation of the workpiece. In order to understand the tool wear and surface roughness characteristics during the high speed turning process of the hardened mold steel by ceramic cutting tools, the polynomial network was used to construct the tool wear and surface roughness prediction model. The polynomial network is constituted of several function nodes; these function nodes can be self-organizing into the optimal network structures according to the predicted square error (PSE) criteria. It is shown that the polynomial network can correctly correlate the input variables (cutting speed, feed rate and cutting time) with the output variables (tool wear and surface roughness). Based on the tool wear and surface roughness prediction model constructed, the wear amount of the ceramic cutting tools and the surface roughness of the workpiece can be predicted with reasonable accuracy if the turning conditions are given and it is also consistent with the experimental results very well. The manufacturing engineers can then , according to the prediction results, execute the process planning, decide the manufacturing process and the tool change time, thus preventing the cutting tool from being over-worn or failing when it is in use.

Abstract: With the wide application of composite materials in aeronautics industry, the repairing technology of the composite materials has become a much discussed research topic in material science. Adopting the laser speckle photography technology, this paper focuses on the influence of light-cured repairing to the stiffness of composite materials, and the feasibility of light-cured repairing technology with experiment has been prove in the paper. The research results show that light-cured repairing technology has no evident influence on the stiffness of composite materials and therefore this technology is applicable to fast-repairing of damaged composite materials. This research is of great significance to the application of future researching of composite materials.

Abstract: Different materials coated on milling tools (tungsten carbide) such as TiCN, TiAlN, TiN and DLC are integrated in this study for the analysis of cutting performance such as tool wear, surface roughness and noise induced in high-speed machining of mold steels such as NAK80 and SKD61 under different combinations of cutting conditions. The study attempts to find out the advantages and adaptabilities in various coating materials being suitable for which cutting circumferences with specific performance request. High-speed milling experiments of NAK80 and SKD61 mold steels with four materials coating tools were carried out in the laboratory. The tool wear was measured through the toolmaker’s microscope and the roughness of the machined surface was measured by the roughness measuring instruments after each surface layer was removed from the workpiece in the experiment. Besides, the noise-mediator was used to detect cutting noise during each surface layer workpiece removing of high-speed milling process, and the curl chips removed from the workpiece were also collected for the result verifications. Good surface quality and small amount of tool wear can be achieved under the cutting conditions of high-speed revolutions, small feed rate and small depth of cut for four materials coating tools. From the observations of the annealing temperature from the removed chips and the analysis of the cutting noise levels, TiAlN material coating tool has the better tool life and it is suitable for rougher high-speed machining, while DLC material coating tool only has a good surface roughness in shallow cut and hence it is not suitable for high-speed machining of mold steel with excellent cutting performance request.

Abstract: AflatoxinB1 was extracted from rice contaminated artificially with Aspergillus flavus by using methanol-water (50:50 v/v). As for experiment group, sodium chloride was added into the extracted solution of AfB1, the excitation wavelength of 365 nm under the fluorescence mode, and the emission spectrum peak at 440nm were observed. To study the detoxification of AflatoxinB1 in several alkaline solutions, the solution of alkaline with difference concentration was added into the solution of AfB1 respectively. The results showed that all of three alkaline solutions could decrease the 440nm emission spectrum peak of solution of AfB1 in varying degrees, the effect to decrease emission spectrum peak of AfB1 was very obvious in sodium hypochlorite (NaClO), and sodium hydroxide (NaOH) took second place, whereas in ammonia (NH3·H2O), the effect was the weakest among three alkaline solutions. Moreover, the effects were different in the same alkaline solutions with different concentration, as hydrochloric acid (HCl) in low concentration was added to this complex AfB1 alkaline solutions, detoxification efficacy of AfB1 were found to be obviously increased. It was concluded that the detoxification of AflatoxinB1 may be affected by alkaline solutions according to their concentration and be degraded greatly by acid addition.

Abstract: Based on the proposed 4PUS-1RPU parallel mechanism a 5-axis Parallel Kinematic Machine (PKM) scheme has been developed and the dynamic characteristics of the PKM have been investigated in detail. To avoid the intensive computation caused by finite element analysis in the research, two typical metamodeling techniques of Response Surface Methodology (RSM) and its artificial neural network enhanced technique were employed as the robust design approaches. Comparing the results obtained from the direct RSM the modeling accuracy by the artificial neural network enhanced RSM can be improved.

Abstract: Based on the CROSSBAR network (CN) and the BANYAN network (BN), two new rearrangeable nonblocking constructions of extended BANYAN network (EBN) are proposed for implementing 8×8 optical matrix switch. The interconnection characteristics of these two types of rearrangeable nonblocking EBN were studied, and the logic program for driving switching units was provided. The calculated insertion loss was 3.3 dB for 8×8 optical matrix switch. Silica waveguide 8×8 matrix optical switch was designed and fabricated according to the calculated results. The silica waveguide propagation loss of 0.1dB/cm and waveguide-fiber coupling loss of 0.5dB/point were measured. With the fabricated 8×8 matrix optical switch, optical insertion loss of 4.6 dB, cross-talk of -38 dB, polarization dependent loss of 0.4 dB, averaged switching power of 1.6 W, and switching time of 1 ms were achieved. A basic agreement between experimental results and theoretical calculated values was achieved.

Abstract: Methods on the measurement of progressive addition lenses (PALs) are summarized. Principles and characteristics of several comparatively promising kinds of methods based on Computer-aided Focimeters, optical sampling (Hartmann Testing, Ronchi Inspecting etc.) and Moiré Deflection Technology (MDT) are described. Corresponding typical arrangements of the measurement devices used in these methods are provided too. After being compared with each other in their features, their respective advantages and application limitations are analyzed. Also, the new development tendencies of these methods are discussed. Based on foregoing comparison and analysis, key problems and difficulties on the measurement of progressive addition lenses are put forward. In the end, the future of the inspection of progressive addition lenses is proposed.

Abstract: The characteristics of Progressive addition lens (PAL) are described in this paper. Theoretical analysis of advantages of Interior PAL is put forward, and the measurement results of Interior PAL are given. Theoretical and measurement results are consistent by comparing Interior PAL and Exterior PAL. Then the working procedures of freeform CNC machine of making Interior PAL are introduced concisely. Also, the experiments were carried out to analyzing the processing results in turning and polishing. From the results, it is explicit that the lens’ form accuracy is controlled in turning and lens’ better surface finish can be obtained in polishing. The factors affecting surface roughness are discussed explicitely based on experiment. The effects of lens material and cutting speed on surface roughness in turning were investigated. The experimental data show that better surface finish can be obtained by using lens material with higher rigidity and using higher cutting speed. Polishing time and pressure influence surface roughness signally in polishing. The reasonable ranges of polishing parameters which could bring about better surface finish are obtained in the experiment. The ranges of polishing time and polishing pressure are 50s—100s and 0.3bar—0.6bar (1bar=0.1MPa) respectively.

Abstract: A novel light guide plate (LGP) with sub-micron gratings (SMGs) on its upper surface is proposed to control the illumination angle and its initial structure of LGP is given. The periods of SMGs are 0.651μm, 0.516μm and 0.433μm for the LED light sources transmit out vertically with the incidence angle 45º under the total internal reflection condition. The transmission efficiencies vary between 2% and 43% when the depth of grooves of SMGs changes between 0.05 μm and 0.9 μm by using rigorous coupled-wave theory (RCWT). The results show that the LGP utilizing the characteristics of the SMGs can control the transmission angle and get homogeneous output.