2-D software datum named as the 2-D mixed method has been constructed to measure mirror surface profiles. The probe of this method consists of two displacement and two angle sensors. Differential calculation of outputs of these four sensors eliminates pitch, roll and the z-directional translation errors of the scanning stages. An autonomous procedure to estimate and compensate the zero-adjustment error among these four sensors is also proposed. By using this software datum, 2-D profiles of ultra-precision surfaces can be measured absolutely without using any external reference. An experimental probe for realizing the 2-D mixed method has been developed and a mirror surface of 128 mm long and 64 mm wide was measured with the probe. Repeatability of measurements and reproducibility compared with the differential angle method have shown high reliability of the proposed method
This paper presents a method for measuring the wear and tear of cutting edges of diamond blade using an image processing system. The threshold value of brightness is decided by the maximum differential value of the brightness between two adjacent pixels. With the threshold value of brightness, the captured gray scale images are transformed into a binary image, and the profile trace of cutting edges is drawn. With the profile trace, the magnitude of the wear and tear of the cutting edges is discussed.
When machining a spherical surface along a contour line with a ball-end mill at high feed speed, the finished surface roughness is greatly affected by the tilting angle of the tool axis. In order to obtain fine surface roughness, this paper proposes concepts of optimum tilting angle and minimum surface roughness for spherical surface machining. The computer simulation demonstrates that the surface roughness can be dramatically improved by tilting the tool axis with an optimum tilting angle, as compared with machining by employing the normal vector on the surface as the tool axis. Furthermore, a mathematical expression has been established by applying the Powell method squares to calculate the optimum tilting angle and the minimum surface roughness under any machining condition. The effectiveness of the estimation for both optimum tilting angle and the minimum surface roughness is also proved, as the estimating error is small enough to satisfy requirements.
When a thin film on a substrate, or a multilayer thin film is irradiated by an ion beam, surface, interface, and the films undergo extensive changes as a result of ion beam induced mixing phenomena. The aim of this study is to use high energy ion beam mixing at the interface between a multilayer and substrate, and to investigate the parameters which can be used to control the mixing profile and the width of mixing layers. Au (30nm) - C (400nm) -Au (30nm) multilayers were deposited on Si and C substrates. These samples were irradiated by 1.5 and 2.0MeV Ni+ and Ag+ ion beams, and irradiation doses were 5.0 × 1015, 1.0 × 1016, 1.7 × 1016 and 2.0 × 1016ion/cm2. RBS was used to investigate the interfacial mixing profiles. A tandem type accelerator was used for high energy ion irradiation and the RBS measurements. The relation between ballistic effect such as collisional cascade, thermodynamic effect (thermal spike) for high energy ion beam mixing, sputtering effect caused by ion beam irradiation was also investigated. From these results, it is concluded that ion beam mixing caused by atomic migration depends on irradiation dose and energy as well as irradiation ion and substrate constituent atom's chemical properties.
The method of the simulation developed by this study is based on replacing an actual grinding process to a computer program as faithfully as possible, where working model of effective grains, their cutting mechanism, effect of machine rigidity, etc. are taken into account. This paper describes the comparison of the simulated results with the experimental ones in various grinding modes, that is, cylindrical plunge grinding, cylindrical traverse grinding, surface grinding and internal grinding. A CBN wheel is employed in a cylindrical plunge grinding mode, and in other grinding modes an aluminum oxide grain and a green silicon carbide grain wheel are used. Performance of the simulation needs to model cutting edges of grains suitably which are determined by truing-dressing operation, a wheel composition, etc. In any grinding mode the simulated results agree well with the experimental ones. In order to obtain the useful results by the simulation, it is important to input the suitable parameters for the cutting edge wear, standard deviation of cutting edge distribution on wheel and specific grinding force of work material.
This paper treats the construction of expert system for process planning in grinding. The grinding wheels are standardized and the definition of shape elements is simplified. From the rules of tool selection and processing order for each reference surface, the computer program for determination of the order of grinding is executed. In the system, the initial data are input through the data base software on the market, and the solution of the grinding order of a given part is determined for various reference surfaces. The confirmation of the effectiveness of the system is shown by an example.
This paper describes some experiments for breaking a liquid crystal display panel using YAG laser. Popular mechanical cutting of the glass panel using small diamond wheel is not always high quality which brings lower productivity of the panel. Precise breaking of the panel with non-contact method using CO2 laser, is recently conducted enthusiastically. The excellent results, however, have not been obtained. Present experiments focus on high quality breaking of the display panel of STN liquid crystal in which some lenses of different focus are used. Breaking tests are performed in air under an ambient temperature using different size of specimens including the notchted ones. It is found that effective spot size of laser on the surface of specimen increases with the usage of longer focus lens which is related closely to the breaking quality of the glass. The lens with shorter focal length elevates the breaking rate of the glass plate and also improves the breaking quality of it. The experiments show that the rate of breaking is independent upon the size of the plate, but it is dependent on the shape of notch made at edge of the specimen. The choice of optimum condition for the breaking yields less meandering main crack and non-branching cracks which deteriorate the breaking quality of the glass plate.
Shear-mode grinding can effectively be used to remove existing damage in surface ground in brittle-mode. This conclusion stems from observing the actual depth of cut and normal grinding force for each grinding pass as the initis lly damaged surface is being incrementally removed. When the specific grinding energy calculated by those values reaches the asymptotic values, the damaged layer has been re-moved. The total depth of material that must be removed in order that none of the initial damage remains is 6 times the maximum roughness of the initial surface. This result suggests that shear-mode grinding does not propagating subsurfaoe damage left by brittle-mode grinding.
This study has been done for the purpose of understanding the mechanisms by which the grinding wheel topographies are formed. The irregularity of distribution of grain tips over the wheel surface and the complexity of their morphology can be characterized by the fractal dimensions. Therefore, it was investigated how the fractal dimensions correlated with the dressing parameters and the composition and properties of wheels themselves. Based on the experimental data, the models adequate to describe the mechanisms were built by the technique, which is called “group method of data handling”. On the basis of the obtained models, the following conclusions could be drawn. (1) The dressing at bigger depth of cut on the harder-grade and more open wheel results in the increased morphological complexity of grain tips. (2) The finer dressing on the denser wheel results in the decreased irregularity of grain tips distribution.
In order to improve the sound environment in workshop, the quality of machining noise which is produced in honing operation is investigated using Semantic Differential. The noises produced in milling and forging operations are used to compare with the honing sound. The main results obtained are follows. The coordinate of semantic space is derived using factor analysis : its first factor, “powerful” factor; and second factor, “metallic” factor. But it is not easy to find an appropriate index for third factor of “pleasant” in these machining sounds. These three sounds have high loadings on “powerful” factor, and the impression of “powerful” factor increases in the order of honing, forging and milling. Forging and honing sounds have high loadings on “metallic” factor, but the milling sound has low loadings on it. As the sound pressure increases, the impression of “powerful” and “metallic” factors becomes stronger.
The productivity of machining centers is influenced strongly by the quality of NC programs. To investigate the productivity, an NC program simulator has been developed to analyze and evaluate an NC program by decoding its NC codes. With the simulator, even before the actual machining, the tool paths can be displayed and the operational times occupied in the positioning feed motion and cutting feed motion, etc. can be calculated. The effects of the maximum speed and the acceleration of positioning feed on the productivity have been analyzed. Additionally, the influence of feedrate override function to shorten the operational time has been investigated in the conventional and the high speed cutting, respectively. From the results obtained from analyzing three NC programs, it is found that the effectiveness of the override function depends on the relation among the average moving distance, the commanded feedrate and the acceleration of cutting feed. Especially, in the case of the NC program for machining dies or molds, the productivity will be hardly improved using faster feedrate, because the actual feedrate hardly increases as expected due to the tiny moving distances of NC blocks. High speed & high precision function, which is an advanced optional function, is much more effective not only to improve the productivity but also to keep the machining accuracy of high speed cutting.