CFRP (Carbon Fiber Reinforced Plastic) is a composite material with strong anisotropy. Direction of carbon fibers influences tool life and surface integrity, machining accuracy. In this study, side milling tests are carried out with coolant and uncoated cemented carbide end mill. Cutting force, cutting temperature, surface integrity and tool wear are examined and the influences of using coolant and carbon fiber direction are analyzed. Under wet condition, the occurrence of burrs is suppressed and the surface integrity improves. It is also found that there is no significant difference on tool wear between dry condition and wet condition. Tool wear milled the layer that carbon fiber direction is perpendicular to feed direction is almost equal to the layer that carbon fiber direction is parallel to feed direction. The cutting temperature on wet condition is lower than that on dry condition. Carbon fiber direction and coolant change magnitude of cutting force. The condition that carbon fiber direction is perpendicular to feed direction on down milling presents the lower cutting forces.

View full abstract

Nano-machining requires precise positioning of a tool on a work piece when the tool is exchanged during the machining. But the usual positioning accuracy is 1μm or less. In this report we propose a method to detect the relative position of a tool and a work piece by 10 nm order repeatability. For this positioning, low voltage is supplied between the tool and the work piece, and the contact position of the tool and the work piece is detected from the current variation between them. The voltage and the current is restricted at the level of Scanning Tunneling Microscope (STM). This method has a possibility that the positioning process is done without contact of them, because the detected current is the tunnel current. Experimental results by the fundamental test show that the repeatability of positioning is less than 20nm.

View full abstract

This present study proposes a process to fabricate micro/nano-mechanical structure for MEMS application using transfer-print. Au thin-film is transferred from a h-PDMS stamp to a micro-structured SU-8 substrate, which have an array of 50-μm-width micro-ridges and micro-grooves. The transferred Au thin-film, of which the thickness is less than 100nm, is formed into the micro-beam across the micro-ridges of substrate. The deposition process of thin-film and the surface morphology of h-PDMS stamp are also investigated to clarify appropriate surface properties for transfer print. Vapor-deposited Au thin-film can be easily released from the hydrophobic stamp. Multi-layered thin-films of Au/Ni/Cu and Au/Al/Cu are prepared on the stamp and also processed on the micro-structured substrate by transfer-print. The transferred multi-layer thin-films are also formed into an array of micro-beams with 100nm thickness. Their production yield and from accuracy can be improved due to modified surface and mechanical strength of multi-layered thin-film as compared with that of monolayer thin-film.

View full abstract

Laser joining between two non-alkali aluminoborosilicate glass sheets was conducted using vanadate glass frit, which had lower melting point (m. p.) than substrates, as an insert material. In order to investigate the optimal joining conditions, the laser power and scanning speed were varied using circular and elliptical shaped laser beams in the joint experiment. Experimental results showed that the excess power irradiation produced a lot of babbles in the joint area, and insufficient power caused a rapid detachment just after joining. However, these defects were suppressed by elliptical beam irradiation. High-speed camera observations suggested that the elliptical beam irradiation contributed to the slower cooling of molten insert glass compared to the case of circular beam irradiation. Numerical calculation of temperature distribution around laser irradiated area was also carried out using finite difference method. Calculated results showed that the melting time in the case of elliptical beam was 2.5 times longer than that of circular beam. Therefore, the elliptical beam is more applicable to the sealing between two glass substrates.

View full abstract

A new configuration for rotating gyros using magnetic suspension is proposed and fabricated. Gyro is one of inertial sensors and a measuring instrument for angular velocity. The magnetically suspended gyro (MSG) was proposed in which a disk-type rotor is connected to a synchronous motor through a fluid bearing and the motor is fixed to the holder; the holder is suspended by magnetic force without any mechanical contact to achieve high-accuracy measurement. According to this concept, a six-degree-of-freedom (6-DOF) active MSG was developed. However, the MSG had to consume power for compensating the gravitational force acting on the holder by magnetic force. In addition, the miniaturization of the MSG was difficult because four pairs of electromagnets were arranged on the opposite sides of the holder. To solve these problems, a novel gyro with hybrid suspension is designed and fabricated. In this gyro, only two rotational motions of the holder are controlled by four electromagnets while the other 4-DOF motions of the holder are constrained by cross springs and a gimbal. Such configuration is suitable for reducing power consumption and also for miniaturization. This paper shows the basic concepts and measurement principles of the rotary gyro with hybrid suspension. The performance of the gyro is evaluated through the measurement of two-axis angular velocities. It is found from the measured frequency characteristics and the succeeding analysis that imperfect derivatives used in the estimation cause an interaction between the two-axis estimations. Two ways to cope with this problem are also presented.

View full abstract

This paper introduces a reliable 3D position and pose recognition method for complicated scenes including randomly stacked objects. The proposed method achieves a reliable recognition by using a small number of effective features selected by evaluating performance of discrimination. The performance of discrimination is evaluated by two abilities. One is the stability of features, the other is separability of false features. For evaluating performance of discrimination, features are extracted from synthesized 3D scenes that are generated by using physics-based simulator and the 3D Computer Graphics (3D-CG) techniques. An object model's features that have high performance of discrimination in the feature space are selected by using synthesized 3D scenes' features, and selected features are used for the matching process. Experimental results using real scenes including randomly stacked objects show that the proposed method's recognition success rate is from 81.7% to 93.9% higher than that of the Vector Pair Matching (VPM) method.

View full abstract

For realizing efficient CAE process, dimension-driven deformation of the FEM mesh models is required. In this paper, we propose a dimension-driven deformation of tetrahedral mesh models of mechanical parts. At first, in order to extract dimensions of the mesh models, a new surface segmentation method of tetrahedral mesh models is proposed. In our segmentation method, planar, cylindrical, conical, spherical, and torus surfaces are sequentially extracted by region-growing based on principal directions, normal vectors, and surface fittings. Secondly, a dimension-driven mesh deformation method in which vertices of the mesh models are moved using a space embedding method and the surface information obtained from the segmentation results is proposed. Our mesh deformation method can change parameters of form features of the mesh models such as radius of the fillet, angle of the chamfer, and so on. Finally, Phased Optimal Delaunay Triangulation (ODT) smoothing which improves element shape qualities from the boundary to the inside of the mesh model is extended. The extended Phased ODT smoothing can improve the surface mesh of the conical, spherical, and torus surface using local 2D parameter spaces.

View full abstract

Reduction of calculation time of tool path generation for complex 3D models is an important issue in development of CAM applications. In this study, cutting point dependent progressive mesh is applied for the models which are represented by meshes. This method maintaines history of simplification of the 3D model with hierarchical structure. 3D model can be refined and simplified by using the cutting point dependent progressive mesh. Therefore, the tool path is safely generated by reducing the number of meshes appropriately. Moreover, calculation time can be reduced. In this paper, a tool path is generated by using cutting point dependent progressive mesh, and the calculation time and the result of tool path generation are evaluated. As a result, calculation time of tool path generation was reduced by use of cutting point dependent progressive mesh. And, it is confirmed that the while result of collision check is same before simplification by upping level of detail.

View full abstract