A new spreading method for thin strips by cross-rolling was proposed. The method employs a flat platen and an idle tapered roll moving over the material width. The continuous widening of strip width can be virtually realized by the repetition of material feeding in the longitudinal direction and reducing the thickness between the roll and the platen. In this study, 1-mm-thick or 2-mm-thick and 50 mm wide commercial aluminum strips were subjected to the model èxperiment using a φ100 mm two-high experimental rolling mill with a tapered roll and a flat steel platen. Consequently, the lateral spread increases with reduction whereas the longitudinal elongation is negligible. However, the applicable reduction in thickness is limited by the occurrence of edge waves. The reductions are less than 10% for 1-mm-thick strip and 24% for 2-mm-thick strip. In the textures of the as-rolled sheet, the crystal orientations vary in the longitudinal direction. The texture is not similar to that generated by transverse-rolling.
Microforming of controlled cavities over workpiece surfaces is a promising application of metal forming although it is not yet popular. Metallic surfaces can thus have the function of reliable and durable information transmission that can be used, for example, in quality control, recycling and the disposal of industrial parts. However, usually metal forming requires a set of tools that is suitable for producing geometrically fixed parts and has some difficulties adapting to various geometries corresponding to various information to be transmitted. In this paper, numerals and characters are converted into two-dimensional bar code symbols of the Data Matrix and QR Code by a PC software. The symbol images are exported to a PC-controlled dot impact machine and then all the white cells of the symbol are dotted onto a metal sample, for example a polished stainless steel plate, by a cone-shaped dot impact pin. The pitch of dots is fixed at 0.12 mm and the diameters of dots range from 28 to 68 μm depending on the setup of the machine. Dotted marks of even three hundred characters are rapidly decoded by a PC-controlled optical system that supports direct marking and is equipped with a CCD macrolens and a ring light guide. Further miniaturization seems possible owing to the flexibility of the measuring system in terms of cavity size, illumination and optical magnification.
Requirements for the qualities of ironed cans have become increasingly severe. A newly developed both-sided ironing process can iron the inner and outer surfaces at the same time using inner and outer dies. A comparison between the conventional one-sided ironing and both-sided ironing is described with respect to the residual stress distribution of ironed cans. The residual stress distribution in the walls of cylindrical cans prepared by drawing, one-sided ironing, and both-sided ironing was investigated with Crampton's method. The high tensile residual stress of the circumferential direction in deep drawn cans is largely decreased by ironing, and also by both-sided ironing and an increase of the ironing ratio. In both-sided ironing, the residual stress in the ironed cans can easily be controlled by changing the design of the ironing die profiles and either height of the two dies. Notably, as the height of the inner die decreases, the residual stress tends to change from tension to compression.
Fine wires approximately on the order of 0.1 mm in diameter have become popular for mechanical and electrical applications. In general, it is well known that finely drawn wires have high strength while maintaining ductility. It has been determined that a hardened layer of approximately 0.04 mm depth, referred to as the “additional shear strain layer,” is generated beneath the surface layer of fine wires during drawing. By performing tensile tests on fine wires, with and without the additional shear strain layer, the effect of this layer on the strength and ductility of fine wires was investigated. The tensile strength decreased as the surface layer was removed in all the wires. The additional shear strain layer affected the tensile strength of the fine wires markedly.
Micro/nano-imprinting or micro/nano-hot embossing is a target of interest for the industrial production of micro and nano-devices. In fluidic micro electro mechanical system (MEMS) applications, polymer materials have been employed for the fabrication of low-cost products. However, glass is much more suitable for high-temperature applications and adverse chemical environments. Also, in optical MEMS glass is a good candidate material with which to achieve good optical properties. Si or Ni molds, usually employed for polymer forming, can no longer be used for glass forming owing to their poor heat resistance and the difficulty in removing them arising from the cohesion between the mold and glass. Glassy carbon (GC) is therefore a suitable material for high-temperature embossing. In this study, focused ion beam (FIB) machining was employed for the micro/nano-3D structuring of GC materials. The machining features of these materials are summarized as follows; 1) Nanomachining at a 0.5 μm resolution was possible. 2) A smooth surface with a maximum roughness of up to Ra 27 nm was formed after 22 μm depth machining. 3) Implanted Ga ions precipitated at 350°C annealing but disappeared after annealing in vacuum at an a high elevated temperature (1400°C). Finally, a quartz glass embossed structure was successfully fabricated by hot embossing with a high fidelity of 10x10x5 μm, a 0.5 μm line-and-space pattern and a 0.4 μm depth.
Micro-nano-imprinting or hot embossing is a target of interest for the industrial production of micro- and nano-devices from the aspect of low cost. In fluidic micro electromechanical systems (MEMS) applications, polymer materials have been widely employed to fabricating economical products owing to their low cost. However, glasses are much more suitable for higher-temperature applications or under more adverse chemical environments. Moreover, the UV absorption of glass materials is much lower than that of polymers, which is an advantage for bioanalysis. In optical MEMS as well, glasses are good candidate materials with which to achieve good optical properties, such as a high refractive index and a low UV absorption. In our previous study, micro/nano imprinting was developed for glass using glassy carbon (GC) mold prepared by focused ion beam (FIB) machining. The disadvantages of FIB machining are the limited area of etching and long machining time. The typical area in FIB machining is less than 0.25 mm2. This is the reason we tried using GC mold fabricated using dicing machine. Micro-hot-embossed test structures were successfully demonstrated with a high fidelity. These fabricated microstructures can be applied to the fabrication of microchamber arrays used for PCR analysis.
In this paper, we discuss the clearance compensation effect in precision shearing. This effect is based on the hypothesis that an unbalanced clearance is automatically compensated for by punch bending when shearing is performed by a long and thin punch. In this paper, we discuss the compensating mechanism through various experiments and an elastic-plastic finite element method. The following results are obtained. When the clearances of the right and left sides are different, the shearing force and horizontal force acting on both punch sides are slightly different. These forces result in moments that bend the punch. The clearance compensation effect depends on the magnitude and direction of these moments. Namely, the effect is due to not only the horizontal force but also the shearing force. In most cases of double-sided shearing, the existence of the compensation effect was apparent.
Magnesium alloys have the lowest densities among metals in practical use, and have properties such high specific strength, effective electromagnetic interference shielding and high vibration damping ratio. Thus, there are many applications of these materials in automotive and electric parts. However, they have little use as metal-forming products, because of their poor plastic deformability at normal temperatures, and because they are expensive to produce. To promote products manufactured by metal forming, rolling technology is necessary to produce thin sheets that have suitable mechanical properties and surface qualities. For this purpose, the equivalent stress and strain relations are investigated by means of a plane strain compressing test for hot-rolled Mg-alloy AZ31 sheets. These materials are experimentally rolled with or without lubrication under temperatures ranging from 293K to 523K. The rolling force, plastic deformability and surface quality are investigated. Grain structures and their uniformity are also observed. Finally, the effect of friction between the rolls and the deforming material on the uniformity of the grain structure is discussed in this work.
Plastics play a very important role in our lives. However, there are several problems, since they depend strongly on underground resources such as oil. To overcome such problems, we are trying to produce a plastic substitute from bamboo, which is considered to be a promising renewable resource. To make efficient use of the strong fiber structure of bamboo, the raw material was not powdered. To obtain basic data to apply molding methods used on plastics, such as extrusion and injection molding, the flow properties of bamboo were examined using a capillary rheometer. The fluidity improved as the moisture content increased. Oven-dried bamboo showed poor fluidity. However, it was possible to make oven-dried bamboo flow by decomposing its component(s). The qualities of the extruded specimens also depend strongly on the moisture content. The extruded material obtained from oven-dried bamboo was of a matrix state, whereas fiber cells and parenchyma cells were clearly observed in the specimens obtained from air-dried bamboo and bamboo of high moisture content. Transfer molding was performed on bamboo and the result showed the feasibility of using bamboo as a plastic substitute.
A series of experiments was carried out to investigate the influence of hard particles on diamond-like carbon (DLC) coating damage in the strip-ironing process. Three types of commercially available DLC coating were used as die coatings on alloy tool steel SKD11 substrates. Three types of hard particles, namely, sand, SiC and Al2O3, were used. Experiments under dry conditions showed no DLC coating damage after ironing with a dull-finished sheet, but DLC coating damage can be observed at the interface inlet when using a sheet finished with abrasive paper. In the case of aluminum sheet (A1050-H24), severe galling is observed under dry conditions. When using a lubricant with hard particles, no DLC coating damage can be observed in samples with sand or Al2O3 particles, but severe DLC coating damage can be observed in samples with SiC particles. The degree of DLC coating damage becomes greater with a high-tensile-strength steel sheet than with an aluminum sheet. The TiN coating is also destroyed by SiC particles but TiC coating damage is negligible.
To investigate the galling behavior on the macroscale in a square cup drawing of high-tensile-strength steel, a series of experiments was carried out under semidry or dry conditions. Cold alloy tool steel (SKD11) and its improved material (SLD), and austempered ductile iron (ADI) were used as noncoated dies. TiCN (PVD), TiCN (CVD), TiC (CVD) and diamond-like carbon-Si (DLC-Si (DC-PACVD)) coated on SKD11 were used as coated dies. The experiments using noncoated dies showed that macroscale galling can be observed clearly on the dies and drawn cup surface with a few drawing cycles. On the die surface, galling occurs at the bottom of the boundary between the straight and corner, and grows upward with the number of drawing cycles. Galling on the drawn cup starts at the top of the same boundary and grows downward with the number of drawing cycles. In the case of coated dies with the drawing cycle number N = 120, no galling on the macroscale can be observed on the dies and drawn cup surface, but microscale adhesion can be observed on TiCN (PVD) or TiCN (CVD) at the same boundary as noncoated dies. No conspicuous adhesion can be observed on TiC (CVD) or DLC-Si (DC-PACVD) when N reached 1000, but microscale adhesion can be noted on TiC (CVD) and no adhesion can be found on DLC-Si (DC-PACVD).