A new combination machining method of ELID-grinding & EDM was lately proposed by the authors. As the results, grinding forces were successfully diminished in comparison with the conventional ELID-grinding. The finished surface, however, severely deteriorated due to EDM using a DC power-source, and a loss of electrodes could not be ignored. In this paper, the DC power-source is replaced by a DC-pulse power-source in order to improve the surface roughness. As the results, both the surface roughness and the loss of the electrodes are successfully reduced. The maximum downfeed, in which a stable combination machining can be performed, increases with the applied voltage for EDM. Workpiece removal rate shows the peak value at a certain table speed under the constant combination machining condition. The finishing process through the combination machining to ELID-grinding is also discussed, and the most efficient process is proposed.
This papre describes the electrode characteristics of TiO2 electrode manufactured by the flame spraying. The thermal spraying flame of the high temperature hits the substrate at the flame spraying, and the oxidizing zone of the high resistivity rate forms on the surface. Therefore, the electrode characteristics decrease remarkably by the voltage drop. To prevent the oxidizing zone being formed, nitride processed the substrate by PVD method and the direct nitriding method. As a result, it was clarified that the electrode characteristics improve by the nitride processing.
Spindles used in machine tools, especially machining centers, must operate at high speeds with high stiffness and low temperature rise in order to achieve improvements in productivity and accuracy of the machine. Usually, preloaded angular contact ball bearings are used to satisfy the requirements of low temperature rise and high stiffness. However, there are opposing effects that can result from preloading. Increasing the preload on the bearings to obtain high stiffness causes high temperature rise, which is not suitable for high-speed operations. On the other hand, high preload is necessary to ensure high stiffness when heavy cutting load, low speed conditions are required. This paper introduces the effects of preload control technology by fixed position on temperature rise and stiffness. High-speed operating tests and cutting tests using spindles equipped with preload control units were conducted. The results confirmed that lower preload reduces bearing temperature rise and higher preload improves the cutting surface roughness. Considering these characteristics, an optimum preload control program is proposed to satisfy both low temperature rise and high stiffness.
This paper describes the characteristic and the mechanism of the abrasive wear of the super abrasive grinding wheel. The characteristics have been obtained on the lapping equipment by the wear experiment, using the sticks of resinoid diamond stones equal to the composition of abrasive grain layer in the super abrasive grinding wheel. The following results are obtained: the rapid abrasive wear of diamond grinding stone occurs at the pressure above the abrasive grain holding force because of ploughing the bond by the diamond grain, on the other hand, the matrix abrasion occurs slowly at the pressure below it. The influence of the grain size and concentration on the abrasive wear are clarified also. In the selection of the truing, dressing and grinding condition, the experimental results will be useful.
This paper illustrates an integrated design procedure for quantifying the manufacturing parameters of the porous superfinishing stone which complies with the specified cutting performance. The outline is as follows. After a stone hardness and a preliminary drawing of stone topography which can be produced by the computer graphics called "fractional Brownian motion" are assumed, the cutting performance is estimated from mathematical models. Such analysis reveals whether the topography and hardness of the stone are optimal or not. If the design fails, these steps are iterated. To find an optimized solution, genetic algorithms have been applied to the iterative design process. The developed GA-based design tool is called SUSDIN (Superfinishing Stone Design Inventor), and has proved fit for practical use as the result of experiments.
Laser collimation of a Li atomic beam has been studied to create an intense collimated atomic beam. The gain of Li atomic intensity in the beam has been measured as functions of laser collimation parameters, such as laser-atom interaction length, laser-frequency detuning and laser power density. The Li intensity gain depends non-linearly on the laser-atom interaction length due to the longitudinal velocity distribution of the thermal Li beam (550°C). In the high laser power regime, the dependence of the Li intensity gain on the laser power and detuning disagrees with the theoretical prediction of the scattering force. These findings are explained by considering the saturation broadening of the Li absorption line. By optimizing the laser collimation parameters, 3.2-fold increase of the atomic intensity is attained for the collimated Li beam with the transverse velocity spread of±5m/s.
This paper deals with the precision glass molding of micro fresnel lens with some micro grooves. Fresnel lenses are useful for the next generation type of optical devices because of its thin structure and excellent optical characteristics. In the conventional machining method, the lens materials were restricted to plastics, because the cutting tool was a single crystal diamond and the molding die material was restricted to a soft metal such as copper or electroless deposited nickel-phosphorous (Ni-P) alloy. In this paper, feasibility study of micro fresnel glass lens was carried out. In the glass molding experiments, the WC (tungsten carbide) molding dies of fresnel shape were used and the dies were ground by using the proposed grinding method with vertically controlled grinding spindle and the disk type wheel of knife edged shape. Then micro glass fresnel lenses were pressed in trial and the optimum press load and press temperature were studied experimentally. The experimental results show that a form accuracy of about 0.3 μm P-V and a smooth surface were obtained and it is clarified that this proposed molding method is useful.
In a magnetic field assisted internal finishing process using an abrasive slurry circulation system, magnetic particles are driven by magnetic force in a helical path along the inner surface of the tube, propelling the abrasive slurry and thereby removing material. The dynamic behavior of the magnetic particles must control, therefore, the roughness and lay of the surface and material removal. It was found that the geometrical and magnetic properties of the particles remarkably affect the configuration of the magnetic particles and their dynamic motion at the finishing area. This modifies the abrasive contacting mechanism against the surface and alters the finished surface characteristics, either uniform micro-scratches in the direction of the abrasive motion or multi-directional marks of aggressive abrasive contact. These characteristics must directly affect the surface quality of the tubes used for safety and sanitary technology applications. This paper characterizes the behavior of the magnetic particles in view of their geometrical and magnetic properties and the effects of these properties on the finishing characteristics. The finishing experiments also demonstrate that controlling the geometrical and magnetic properties of the particles is of use in extending the feasibility of the process.
Cutting force as well as cutting energy is essential to be reduced in the "one tool milling process" for complicated shaped dies and molds made of hardened steel using only a small ball end mill, in stead of the conventional sequential milling process from rough endmilling to fine one using various end mills. In the present paper, cutting force components and cutting energy are measured to analyze in high-spindlespeed, high-feed rate milling of hardened steel using ball end mills of lmm in radius. The following results were obtained: (1) Three components of dynamic cutting force can be measured individually on a unidirectional sensing load cell at a spindle speed up to 4.5×104min-1. (2) The maximum value of each component of dynamic cutting force significantly decreases with increase of either spindle speed or feed rate. (3) Effective value of axial cutting force component increases along with feed rate. (4) Specific energy evaluated from spindle power consumption is good correspondent to that from monitored cutting force. These results are significantly favorable characteristics in realizing more high productivity on the high-spindle-speed milling using only a small ball end mill.
This paper reports the study on manufacturing technology of a brushless DC motor for saving energy with high efficiency. This motor has a joint-lapped core which is able to warp for the reverse freely. First, the joint-lapped core is formed with the high-speed press machine by cylindrical shape. In coil winding, the joint-lapped core is warped for the reverse by bending the joints and wound the coil under the condition of the alignment. After winding, the joint-lapped core is bent as a similar conventional circular stator. This manufacturing method brings the coil of the high density by using the thick magnet wire and the stator of a high degree of a right circle. As a result, it can be realized the efficiency of 96% of the motors in the compression machine for the air conditioner.
Until now, the criteria to evaluate the processing technique have been mainly lying in the aspects of cost, accuracy, quality, efficiency and stability. With the criterion on environmental contamination added in, the realization of the environmental harmony type of processing technique is becoming an important topic. As the first step of this research, this paper aims to find out the fundamental guideline in developing a harmless grinding wheel, which may be used in the mirror grinding of the silicon. Harmless materials for human being were selected as the constituent materials. Sodium alginate was used as the bonding agent and barium sulfate was used as the abrasive grain. The performance of the wheel was investigated by the grinding of the 8-inch silicon wafer. In dry grinding, a stable mirror surface with around 10nm roughness (Ry) was obtained, and the processing strain was very small, furthermore, small acicular silicon was observed in the grinding chips. However, toxic SO3 was detected in the gas arising in the grinding process. By this new method, the grinding wheel that basically met the conventional was prototyped experimentally. The mechanochemical reaction, which is usually difficult to be proved, can be easily confirmed by the happening of noxious gas. It also clarified that although the grinding wheel was made of harmless material, noxious material happened from mechanochemical reaction.
A method automatically tuning the parameters in a digital controller is proposed for a DC servomotor. In this method, the system parameters are identified and the controller parameters are then tuned every sampling period. The features of the proposed method are summarized as follows: (1) The structure of controller is similar to the conventional one. (2) An approximate discrete-time model is introduced to simplify controller design and system identification. (3) Arbitrary closed-loop poles can be prescribed in advance for tuning. The zeros depending on the identified system-parameters and the tuned controller-parameters are not introduced. (4) For the case of using the difference of the angular position measured by an encoder instead of the real angular velocity, the influence on the control system is clarified. (5) The identification method is modified for this case. (6) The approximate discrete-time model is guaranteed to be valid in the control and identification. In order to illustrate the effectiveness of the nronosed method, experimental results are given.
This paper describes a tracking control for plural hand-eye systems with respect to multiple objects. In case that hand-eye systems attempt to realize tracking control in regard to multiple objects simultaneously, there is a situation that it is desirable one of these hand-eye systems changes its target object. For example, if the hand-eye system continues to track the same target object, collision with the other hand-eye system may happen. To avoid such a collision, the optimal selection of the target object for each hand-eye system is required. To address the above issue, this paper proposes an approach for tracking control of multiple objects in plural hand-eye systems. In proposed approach a virtual image plane is introduced so as to take into account kinematics relation with respect to each camera and target. And on the plane the visual tracking controller is constructed by using weight with regard to target objects. This paper also applies the proposed approach to tracking control in two planar manipulator and numerical simulations and experiments show the efficiency.
This paper presents a new differential laser auto-collimation method that can remove the influence of zero point difference.Surface profile measurement methods that detect the second differential of a surface, such as the 3-point method and differential laser auto-collimation(DLAC), are effected by the zero point difference of the sensors. We have developed a zefo point compensation method for DLAC with a simple mechanism that required only the rotation of one polarized beam splitter. TwoDLAC systems with zero point compensation were made. Measurement range and accuracy of the first system as an inclination of a measured surface were 30' and ±5" in the worst case, respectively. Those of the second system were 10' and ±3". The comparison between the measured results obtained by the proposed method and those obtained by another method that used sampled data of one beam and the pitching data of an auto-collimator showed the usefulness of this zero point compensation.
Following the measurement principle and algorithm described in 1st report, an experimental measurement system for aluminum hollow cylinder was presented. Firstly the measuring range and resolution of the optical unit were demonstrated. Then the roundness profiles for the sample cylinders were derived by utilizing correction factors for the intended band of undulation per revolution. The measured results by the developed system were in good agreement with those by commercial measuring instruments. It was concluded that the rotational error as well as roundness error of cylindrical machine parts could be successfully measured by the developed system. This system is applicable to the roundness measurement at workshop level.
The purposes of this study are to understand the relation between brightness uniformity of LCDs and its cell gap deviation caused by flatness of their substrates and to propose a flatness criterion of substrates considering human sensibility to the uniformity. Examinations are performed using periodic linear deviations in brightness uniformity on LCD cell samples. Result of psychophysical test shows that human sensibility to the linear defects depends on a cross gradient for the brightness signal projection to a linear direction. Therefore linear defects in uniformity can be evaluated by the gradient value. To demonstrate correlation between the deviation to brightness uniformity of LCDs and the cell gap deviation caused by flatness deviations of their substrates, some cross sections on LCD cell samples are tested. Brightness deviations are measured by image processing technique and cell gap deviations are calculated from measured surface profiles of their front and rear substrates that were pieces of the cells. Strong similarity between both deviations is observed. From this result it becomes clear that periodic linear deviations to the brightness uniformity on LCDs can come from surface corrugation of substrates caused by glass surface or coated layers. Then flatness of substrates can be evaluated according to the human sensibility to the brightness uniformity of LCDs by using gradient value of surface profiles and allowable limits of substrate corrugation can be determined by this experimental process in the same cell production condition.
A new position detecting method, which uses a 2-D angle grid and a 2-D angle sensor, is proposed. The angle grid has a 2-D sinusoidal angular pattern on the surface. The relative displacements between the angle grid and the angle sensor in the X- and Y- directions can be detected from the output of the angle sensor. Because of the angle independency in the X- and Y- directions, it is possible to detect the X- and Y-directional positions from the 2-D angle sensor outputs. Furthermore, use of an optical scanning angle sensor, which scans a beam spot on the angle grid, can reduce the effect of the form error of the angle grid. Rolling and pitching can also be detected by using this method. In this paper, a scanning 2-D angle sensor is designed and manufactured. Experimental results of position detection are reported.
The interference processing of curves and surfaces is an important technique in CAD/CAM applications. The lack of the stability in the interference processing is due to numerical errors caused by floating point arithmetic and the approximate computations. In the interference processing, the geometric Newton-Raphson method is generally used for approximations, because the solutions of high degree polynomial equations cannot be exactly computed. Most geometric algorithms, such as Boolean set operation algorithms, modify the topological data structure according to the existence of the solutions of polynomial equations. The number of solutions of algebraic equations can be exactly counted with Sturm's theorem and exact arithmetic. In this paper, a stable interference method for curves and surfaces using Sturm's theorem and exact arithmetic is proposed. The proposed approach can exactly evaluate the existence of intersection points in curve/surface intersection.
This paper describes a robust and efficient method for interference calculation between polyhedral solids. The method treats geometrical elements as incident each other when their intersection is ambiguous because of numerical errors. After the incident information is generated as topological constraints from minimal geometrical judgements, it is modified to hold consistent relations and utilized to generate a topological structure of an output solid. A cluster, which is a set of coincident intersection points, is deduced from the constraints for points, and a local structure at the intersection is determined symbolically with the face sequence around the cluster. Further, high-precision arithmetic is used partially not to cause larger errors than the tolerance. Using these algorithms, consistent results are shown to be always obtained efficiently.
An analytical model was presented to explain the experimental results of ejection force for injection mold with smooth surface. The model is based on the adhesion theory that the meniscus force is principal component of the ejection force . The meniscus force between core and molded specimen was formulated with surface roughness of two surfaces in contact and liquid film thickness. In the range of Ra < 0.2 μm, the calculated meniscus forces become extraordinarily large and are in good agreement with experimental results. In addition, some ploughing marks are found on the molded specimens for larger values of core surface roughness. Through this experimental and analytical investigation, it was made clear that the meniscus force is main cause of the ejection force for smoother core surface and the resistance force of ploughing for the rougher core surface.
Because of manufacturing process outsourcing, transfer of design knowledge and manufacturing skill in manufacturing industry become very difficult. In order to support knowledge and skill transfer, a new concept of design system, Knowledge Driven Digital Design (KDDD) system, is proposed in this paper. KDDD is a mechanical design system for telecommunication equipment, which is composed of knowledge database and knowledge engine. As a first step, product models, which are generated by production process and design knowledge, are defined. Then, by classifying design knowledge, three kinds of knowledge layers are shown as cases, manuals and formulas. Also three kinds of knowledge engines are proposed respectively as a framework of KDDD. Based on the framework, development of KDDD is investigated by using 3D-CAD and intranet.