The orthogonal cutting test was carried out on two structural steels, namely Fe-0.5%C-0.2%Si-0.8%Mn-0.1%Cr containing 0.16%Pb or non-Pb. The chip formation was transferred from shear type to flow type and the cutting force was reduced by the addition of Pb. The lead observed in the shear zone of the chip exhibited a thin string-like morphology, suggesting the ductile and very deformable characteristic of Pb. Those results indicate the major cause of the flow type chip formation. The shear angle can be maintained in the Pb-added steel because of the deformation concentrated on lead particles at the primary shear zone. In the case of low cutting speed conditions, the effect of Pb on machinability mainly reduces shear force in the primary shear zone. As for the lower friction coefficient between tool and chip, the effect of decreasing the cutting force is small.
Lapping technique has been usually applied to achieve high flatness to large plates that are used to manufacture liquid crystal displays of televisions and computers. The lapping simulation to calculate the surface generation process for various tool and workpiece profiles barely has been studied. On the other hand, the polishing simulation based on the gap theory was developed and it was clarified that the simulated results agreed well with experimental results. This paper describes the concept to apply the polishing simulation to lapping and the hypothesis to treat a rigid tool as an elastic body. The experimental results during a transitional period when lapping area expands from the local part to the whole surface were compared with the simulated results calculated using the gap theory. It was demonstrated that the relative elastic coefficient decreases with lapping time and converges to a constant value. The convergent value becomes large with the slope of the tool, but the grain size has no effect. The correlation exists between the relative elastic coefficient and the contact ratio of the workpiece with the tool. However, the relative elastic coefficient cannot be unambiguously determined by the contact ratio, and the slope of the tool or the gap gradient should be introduced to the simulation parameter.
At first, a possibility of application of the parallel link mechanism for semiconductor manufacturing field has been researched and discussed, then it was decided to make efforts in the parallel multi-linked stage development for EPL(Electron-beam Projection Lithography). Magnetic devices, for instance, electromagnetic linear motor, voice coil motor and electrostatic actuator have been typically utilized for higher response and finer accuracy of positioning in lithography tools, however the stage in EPL might be hopefully driven by non-magnetic device such as piezo actuator because of prevention of beam deflection. At the first phase, 4-degree stage composed of a 6-dof(degree of freedom) parallel link system was manufactured and verified in advance, then we confirmed desired static and dynamic performance after installing the stage into the production tool. At the second phase, 6-degree stage which had an ability of 6dof stroke control was produced experimentally, after that it had been evaluated at the viewpoint of reduction of coupling between axes. Better positioning accuracy and de-coupling by using link compensation, compared with 4-degree stage was finally acquired.
Contouring controller design has been widely studied thus far because of its effectiveness for machine tool control. However, plant modeling errors and disturbances such as nonlinear frictions and cutting forces are little considered in existent designs. This paper presents a new contouring controller design that is robust to these unknown factors. First, a contouring controller design based on a coordinate transformation and reference signal adjustment, which has been developed by the authors, is explained. This design enables to adjust control performance of the contour error and the other error component independently to enhance the effectiveness of the contouring control. Next, assuming that upper bounds of plant modeling error and disturbance magnitudes are known, we extend this design to have robustness with respect to plant modeling errors and disturbances. Because unnecessary large values of these magnitudes deteriorate control performance, we further design an estimator of these upper bounds in real time. Comparative experiments demonstrate the effectiveness of the proposed design.
3+2-axis control milling is effectively performed on 5-axis controlled machine tools. However, it is difficult to determine the effective tool posture automatically. In this study, a fast method to detect material removal volume is proposed for tool posture decision. In the proposed method, workpiece, product and tooling shapes are modeled based on the voxel representation for calculating the discrete cross correlation function. The offset surface is generated on the boundary of the existence of the similarity between the product and tooling shapes. Tooling swept area is calculated as the convolution of the tooling shape. Consequently, the material removal volume and the unmachined volume are quickly obtained and can be simply evaluated. Moreover, the range of tool postures to calculate the material removal volume is limited by effectively using the feature of voxel models. Material removal volume is calculated at only the obtained candidates of the effective tool posture. In order to verify the usefulness of the proposed method, several case studies are conducted. It is confirmed that relatively large volume becomes machinable at the tool posture decided by using the proposed method.
The polisher has large influence on the polishing characteristics of the aluminum type of magnetic disk substrate. The optimum polisher manufacturing technique acts on the important role to the products of the magnetic disk substrate. In the report, from the point of view, the influence of the buffing process in polisher manufacturing on polishing characteristics of the aluminum magnetic disk substrate in the rough finishing process is examined. The suede type of polisher is manufactured by changing the mesh size of sand paper used in buffing process and changing the buffing removal amount. The polisher surface roughness becomes larger for coarser sand paper. The polished substrate surface roughness becomes rougher for rougher polisher surface. The open pore size on the polisher surface becomes larger as the buffing removal amount increases. The substrate removal rate and the decreasing rate edge of roll-up type of roll-off height become smaller for the polisher of larger open pore size, respectively.
Although flash-lamp pumped pulsed laser has the good performances of high energy and high peak power, the pulse repetitions are considerably low. Therefore, it is only applied to a limited extent. In this report, the light energy by using a semiconductor pumped pulse laser with ability of the high repetitions was transmitted to the wheel using an optical multi mode fiber with the large core diameter (200 μm) and irradiated to the surface on the thermoplastic resin bonded diamond wheel. As a result, we succeeded in restoring the retentivity of thermoplastic resin for grains by effect of laser-thermal and laser-ablation processing, and confirmed a finding of the columnar structure with potential, which might be created the new polishing tools, in the wheel surface.
The inclusion of the application of the double ball bar (DBB) measurement to the accuracy calibration of five-axis machine tools into the revision of ISO standards is currently under the discussion. This paper presents the modified DBB measurement device, referred to as “DBB5” in our study, where master balls are supported from the 45°direction to the spindle axis. It can perform all the circular tests on XY, YZ, and ZX planes without changing the setup. This paper first presents the classification of motion error components of a five-aixs machine tool into location and component errors. Experimental application examples of the DBB5 to the calibration of location and component errors assciated with rotary axes on a five-axis machine tool are then presented.
We developed computer-controlled figuring system having controllability of removal depth with nanometer level accuracy and spatial resolution close to 0.1 mm. In the system, Elastic Emission Machining (EEM) using nozzle type head and Microstitching Interferometry (MSI) are employed as a machining method and a figure measurement method. In EEM, the very small stationary machining spots are obtained, selecting small circle nozzle aperture of a 0.15 mm diameter. In this study we demonstrated computer controlled figuring, focusing on removal of high frequency figurer error, in the course of the fabrication of hard X-ray focusing mirror. Figure accuracy of 0. 2nm (RMS) is achieved at cross-sectional line profile with a length of 90nm. The fabricated X-ray mirror is evaluated at 1km-long beamline of SPring-8. Low background noise around main peak in the focused beam and improvement of image quality in the diverging beam are observed.
Steer-by-wire system (SBW), which is expected to improve passive and active safety for vehicle, has been discussed. Fault-tolerant capability of SBW is similarly required to a fly-by-wire of airplane because failures of SBW have a possibility to cause lack of steering function of the vehicle. Redundancy and diversity of steering function tend to require high cost, and it can postpone commercialization of SBW. This paper describes a diversified architecture for SBW fault-tolerance and its management that is integrated with pre-installed ESC and DTD. Effectiveness of the architecture and the management is investigated by a driving simulator experiment. This study shows a possibility to achieve reliability without excessive redundancy or additional diversity of the steering function.
In this paper, we propose a design method to create new surface material measures with irregular surface topographies for the calibration of surface texture measuring instruments having various measurement principles. We also propose the verification system for the surface measuring instruments using those surface material measures. Basic design factors of the surface material measures for three-dimensional (3D) surface roughness measurement are also discussed to create the software gauge data with irregular surface topographies. The software gauge data with 3D irregular topographies based on the non-causal 2D auto-regressive model are utilized to design the surface material measures. The proposed procedure can create surface structures of surface material measures with periodical irregular surface topographies and specified roughness parameter values. The proposed method has capability to create surface material measures with variable roughness parameters for arbitrary evaluation area.
This study aims at developing an intra-firm prediction market system for obtaining not only a point estimate but also a continuous forecast distribution of the demand quantity of a certain product in a future time period based on the collective knowledge of the firm's sales people. The system uses the variable-interval prediction security (VIPS) as the prediction security to be traded in the market, and possesses a computerized market maker which evaluates each unit of VIPS with a Gaussian price density and updates the price density function, or the forecast distribution, intermittently every time a certain condition is met according to the transactions in the market. In earlier work, a market maker with a simple weighted average updating logic has been found to be vulnerable to arbitrage. Thus, this paper refines the market maker by introducing the inventory-based updating logic and book value constraint in order to fix the vulnerability. How the market maker functions and on what parameters its performance mainly depends are studied through agent-based simulation.
In the triple dexel model, object shape is represented by 3 groups of axis aligned segments named x-axis dexels, y-axis dexels, and z-axis dexels. Triple dexel model is known as compact and precise representation compared with other discrete solid representation schemes. Based on the triple dexel representation, a new 5-axis milling simulation system is developed. Differently from prior systems, this system uses GPU technology for accelerating 3 important processing steps in the milling simulation, which are (1) cutter swept volume generation, (2) subtraction of the swept volume from the workpiece solid model, and (3) update of the workpiece picture for achieving smooth animation of the milling process. An experimental system is implemented and some computational experiments are performed. Our system can realize a simulation of a complex 5-axis milling process in a few minutes. The animation speed is generally more than 100 frames per second.