This report confirmed the influence of the anti-wear additive on grease base oil viscosity. When the grease of low base oil viscosity is used for lubricating the linear motion rolling bearing, rolling fatigue life shortens. This fact is not shown in the rating life equation of the linear motion rolling bearing. Meanwhile, the fact is reported that MoDTC(Molybdenum Dialkyldithiocarbamate), one sort of the anti-wear additive, is effective with the bearing supporting rotary motion is reported, and many examples are in practical use. However, MoDTC hastens rolling fatigue life in the linear motion rolling bearing. The Nanoindenter hardness is associated with traveled distance in the linear motion rolling bearing. The anti-wear additive, reducing the hardness of the steel ball, shortens rolling fatigue life of the linear motion rolling bearing. The change of the steel ball hardness cannot be measured by the microVickers hardness. In addition, the change of color of a steel ball in linear motion rolling bearing is caused by the oxidation film. The change of color of the steel ball does not adversely affect rolling fatigue life.
Recently, in accordance with the technical development and miniaturization of information equipments, the demand of optic elements with high precision and miniaturization is increased. The mold is used in the manufacture of the optic elements. However, it is a problem of the occurrence of severe tool wear because hard materials including cemented carbide and ceramics are used as the material of molds. To solve this problem, cutting point swivel machining by using the diamond tool with special chamfer was proposed, which has the ability to suppress tool wear and to realize ultraprecision machining. The effectiveness was verified by the microgrooving experiment of SiC. The study aims at applying the cutting point swivel machining to the machining of curved microgroove and curved surface. As a result, it is confirmed that microgrooves with arbitrary curvature can be machined with high precision. Besides, it is specially found that the method enables to obtain good roughness in both feed and pick feed direction in the plane machining and to create a curved surface with good surface quality.
Thin films of fullerene derivative were prepared by an electrospray deposition (ESD) method using six types of fullerene derivatives (a series of [6,6]-Phenyl-C61-butyric acid ester and adducts of C60 with indene). The optimized conditions for fabricated thin films were investigated by ESD process using 1.0 mg/mL diluted solutions of the fullerene derivatives : the spray diameter as a function of the supply rate by changing the applied voltages. In all the cases, the spray diameters increased with increasing applied voltage reaching the maximum diameter (Dmax) at the voltage (VDmax) and decreasing for higher voltage. The scanning electron microscope observation of the successfully fabricated thin films showed the imbricated structure formed by the stacking of fullerene derivative sheets. The atomic force microscope image revealed that the highest density of imbricated structure was obtained at VDmax, and the root-mean-square roughness of the film surface decreased sharply reaching at the voltage. These findings suggest that the ESD method is expected to be effective to prepare a fullerene derivative thin film for the production of organic devices.
Square end mills of a small diameter are often used in micro end milling for making rectangular micro grooves. However, they are inevitably very flexible during milling, and it brings about poor machined accuracy on workpieces. In this paper, “groove warp” on a workpiece is discussed experimentally according to analyze the high frequency cutting force measured during tool-width milling with square end mills of 0.1mm in diameter. As a result, it is made clear that the resultant cutting force compels to deflect cutting edges even when they are situated at a rotating angle θ=0 or 180 deg., where position accuracy of both side walls are decided respectively, although the depth of cut on each cutting edge is negligible small. Therefore, the tool axis is deviated during transient milling from a contact start to the feed inside a tool radius, and the tool gets starting elastic recovery in the distance inside a tool radius from the end face of a workpiece. Therefore, the larger normal cutting force increases, the poorer groove accuracy deteriorates.
This study proposes a new estimation method for tool posture in 3+2 axis control machining process. The proposed method focuses on two different properties of workpiece surface, machinable area and minimum shank length. Distribution of these properties on workpiece surface is determined by the tool posture, workpiece shape, and shape of cutting tool. In planning process of 3+2 axis control machining, CAM and CAPP operators often determine combination of tool posture and tooling conditions through trial and error. In such planning process, fast visualization method of these properties on workpiece surface is strongly required to realize CAM and CAPP systems with an interactive interface. Then, this study proposes fast estimation method to visualize both the machinable area and distribution of the minimum shank length as a color image for each tool posture candidate. In order to reduce calculation time of the proposed methods, graphics devices known as Graphics Processing Unit (GPU) is introduced. In the proposed algorithm to adapt several features on GPU hardware, offset shape of workpiece surface is generated from depth information in rendering 3D-CG. Furthermore, unmachinable area is estimated by inverse-offset operation and shadow mapping function in 3D-CG techniques. In the visualization phase of required shank length on workpiece surface, a color image is generated from the depth information. Then, the color image is projected on workpiece shape with the texture projection technique. Because almost calculation processes can be executed inside of GPU hardware, the developed prototype system can visualize both the unmachinable area and distribution of minimum shank length within several dozen milliseconds for each tool posture candidate.