This paper treats the machine parts visual inspection system for surface defects, such as a crack, a pin-hole and other imperfections. The automated inspection system for defects on the three dimensional surface of machine parts has not been reported in the past, due to the complexity of analyses of light reflection data and the difficulty of measuring conditions. The features of defects are analyzed and classified. Also the features of defects can be indicated in terms of membership functions of the fuzzy technique. A new SPOT CHECK algorithm for defects on three dimensional surfaces of the machine parts has been developed. The moving average method, and the statistical treatment of light reflection data from the surfaces of the parts are applied to the SPOT CHECK method which has been developed. It is possible by using the SPOT CHECK method to measure the defects without influencing the measuring conditions, such as the illumination and the positioning of the parts. The neural network system has been developed, the system uses the membership functions of features of defects as the input data, while the kinds of defects as the output data. It is found that the neural network system has rapid convergence characteristics. The experimental verification results for the recognition of the kinds of defects are satisfactory.
It is very important in design problems of automatic production or assembly lines to estimate the fluctuation of daily output which results from the irregular occurrence of trouble and the variance of operational ratio of lines. An analytical method for the variance of operational ratio as the application of analysis for the operational ratio has been presented by previous papers. However, the method needs troublesome computations into practice. In compositions of lines, assembly stations are aligned in various ways, such as series, branched or parallel. Therefore, the method must be simple in calculation. In this report, a simple experimental equation which is given through simulations for production lines with various factors (trouble occurrence ratio, recovery times and buffer capacities) by a digital computer is presented. The presented equation gives appropriate results of variances of operational ratio in automatic production lines. Furthermore, a method to estimate fluctuations of daily products by the presented equation is shown with a numerical example.
This paper discusses a new mechanism for a 3DOF joint which is constructed by a cable-controlled mechanism and an interference drive system. This is equivalent to a parallel mechanism having flexible links. However, it is difficult to drive the mechanism by an ordinary procedure because it has a redundancy of drive-cables given the DOF of the joint. Therefore, in this paper, a transform equation is formulated between the drive system and the joint system, and an effective algorithm is proposed for computation on the tensions of cables based on vector analysis. An experiment for dynamical tracking control of the mechanism as an imaginary walking leg is tried using a computed torque technique. As the result, it is concluded that the cable-controlled mechanism is effective for a 3DOF joint.
A verification of a measurement method of surface profile along a circle with no standard is carried out. For the measurement, spacings between two unknown surfaces located almost in parallel are measured along a circle. One of the surfaces is rotated around the center of the circle and the spacings are measured again. This procedure is repeated many times. From these data, the profiles of two surfaces are calculated with a system of simultaneous linear equations. For the purpose of a verification experiment, a simple surface measuring apparatus is constructed which has 12 electric comparators arranged along a circle. Their zero point positions correspond to one of two surfaces. A random inclination and a random displacement can be given intensionally to the surface to be measured. The surface profiles obtained by different experiments agree well with each other and with the profiles obtained with a 3-dimensional measuring machine.
The Cycloid Ball Reducer has been developed for use.for servo mechanism elements. Motion principle of the reducer has been analyzed, and it becomes clear that there is the optimal value of trochoid factor which affects on pressure angle and radius of curvature. In this report, the fundamental design parameters of Cycloid Ball Reducer are investigated and derived, to adapt external type reducers with trochoidal groove or teeth. The strength of trochoidal groove for this reducer is analyzed using Hertz's theory. It is proved that the strength of reducer is influenced on center distance modification factor, ball diameter factor, ball number and module of this reducer. As the results, one of the design method that is based on theoretical strength, can be shown. Also, this method is able to evaluate the allowable load torque for this reducer.
This paper is intended as a development of new process control method of making high quality of products in machining process Conventional process control methods are for off-line control and cannot be determined optimal control limits according to cutting state in machining process. The proposed method is applicable to on-line process control and determination of optimal control limit according to cutting state of machining process in short time. By introducing new parameter of actual measured geometrical deviation (AMGD), it becomes clear that it can obtain control limit based on geometrical relation. The proposed method is constructed reasoning networks by learning fuzzy neural network and generalize the control limit by fuzzy reasoning. The control limits of geometrical tolerances are shown by simulation.
In an automatic detection system for small particles on patterned wafers, the optical system which eliminates insensitive regions on a linear image sensor has been developed. The real image of wafer is splitted into two parts by the split mirror set on the real image plane of the detection system. The insensitive regions are eliminated by setting the linear image sensors whose pixels are shifted by a halfpixel relatively, on these two real images. The relative displacement between the two real image detected by the sensors is 0.5±0.1 pixel over the view field of 3mm and the shading of images is 23%. The intensity of images with the split mirror becomes twice as much as that with the half mirror.
Shape data input of an industrial art object can be easily performed by using a teaching robot. The objective of this research is to reduce the random errors in the teaching data and to obtain smooth curved lines and surfaces. By this, 3D graphic expression and machining of an industrial art object can be made easy. For characteristic lines, the least square method is used to fit a polynomial expression. For curved surfaces, two parameters (ui, vi) for expressing surface are used, and the teaching data are sorted with respect to these parameters. The least square method is then used to fit polynomial expressions on the curved surfaces. Finally, the fitted polynomial expressions are used to calculate corrected value of teaching data for generating smooth curved lines and surfaces.
For the purpose of fabricating free-form optical elements to an accuracy of 80 nmPV, the CSSP (Canon Super-Smooth Polisher) has been developed. This device finishes workpieces by alternately repeating contour measuring and corrective polishing. In such a system, contour measuring is important because it limits the final accuracy of the workpiece. This paper focuses on the CSSP's on-machine contour measuring method. A contact probe is employed to ensure adaptability to free-form contours with maximum tilt angles of 35 degrees. A unique probe structure is proposed, by which both inclination and motion errors of the probe are simultaneously compensated. The flaw problem is discussed from an experimental point of view. Using a ceramic air slide and a linear motor, the contact force was controlled to a constant of 2 mN, which is much smaller than the force of 260 mN that causes a yield stress on workpieces made of calcium fluoride. The probe's scanning speed of 4 mm/s was achieved by speeding up this force controller. The margin of force error during contour measurement was under 0.2 mN. A coordinate measuring method using fourteen axes interferometers was also proposed for compensation of the major mechanical motion errors of the probe and the tables. The measurement results showed good repeatabilities of 3 nmRMS for a 540 mm line measurement, and 9 nm RMS for a φ 500 mm aspherical surface measurement.
This paper discusses the optimum configuration of illumination system which detects small particles on a patterned specimen by illuminating a laser diode obliquely. A luminous part of laser diode spreads in a line. The real image of luminous part has to be projected with a rotational angle of θ around an optical axis of illumination. The angles of rotation and tilt asked for realizing the above mentioned condition are analyzed theoretically and experimentally. A new optical system with two cylindrical lenses is proposed and analyzed experimentally to reduce the width of illuminated area. Using this new optical system, the width is reduced to 1/2 - 1/3 compared with conventional optical system.
For the ceramic ball bearings in the step of the practical use, for which it is required to build up the data base on the various conditions in the life test, the sample size and testing time are the important problems in the life tests. The staircase method is discussed for these problems. This paper presents the life tests by the staircase method which involves comparison with the basic dynamic load rating by Weibull method, using the two kinds of ceramic ball bearings which differ from each other in the determining mechanisms of life. As the results the basic dynamic load rating by the staircase method is in agreement with that by Weibull method, and the testing time in the staircase method is shorter than that in Weibull method. It appears that the basic dynamic load rating of alumina ball bearings is extremely lower than that of silicon nitride ball bearings.
For monitoring tool wear in machining process, a method of diagnostic impulse excitation was discussed. The dynamic characteristics of the tool vibration, especially, damping ratio of the tool in machining process, will change with the tool wear development. In order to measure the dynamic characteristics of the tool vibration in machining, the diagnostic impulse excitation was applied to the tool in the direction of feed and then the behavior of the tool vibration was measured under some wear conditions. The behavior was analyzed through FFT and the damping ratio of the tool was measured in machining process. The damping ratio was linearly increased with the development of flank wear. The increment of the damping ratio was different in each cutting condition, but it could be uniquely determined by the area of the flank wear. The feed rate did not affect on the increment of the relation between the damping ratio and the flank wear, but the parallel shift of the relation was seen, so that larger feed rate will give the larger damping ratio. The increment of the damping ratio will be caused from the interaction between wear and cut surface. As the vibration energy is consumed in the interaction, the energy consumption mechanism was discussed. And the widely available method to monitor the flank wear was proposed and discussed with the experimental ones.
Adsorption processes of NH3 on Si (001) -2×1 surface have been investigated by the first-principles molecular-dynamics simulations. The total energy calculation shows that NH3 adsorbs molecularly on the cave site with the adsorption energy of 5.89eV and the relaxation of surface Si dimers is crucial in determining the adsorption eitergy. The optimized configuration of the adsorbed NH3 is found at 1.86Å above the topmost Si surface with the N-H bond length of 1.32Å and the H-N-H bond angle of 92.0°.The dissociative adsorption process of NH3 is also studied. The decomposition process of NH3 to form NH2 and H has the activation barrier of at most 0.4 eV. After the decomposition, however, both NH2 and H adsorb to the Si surface dangling bonds without activation barrier. The dissociative adsorption is more stable than the molecular adsorption of NH3; the total energy of the former is 7.37eV, while that of the latter is 5.89eV.
The shape and size of abrasive grains during lapping varies complicately and irregularly. In this study, the aspect ratio of grain size and the fractal dimension of the grain external form were used as shape characteristics of grain in order to evaluate grains with lapping time. The results obtained are summarized as follows : (1) The fractal dimension increases due to microscopic fracture and decreases due to macroscopic fracture or attritious wear. (2) The aspect ratio and the fractal dimension, which are grain shape characteristicsis of the macroscopic shape and the microscopic surface complication of grain respectively, can be used for evaluating grain shape variation during lapping.
In the previous report, a methodology that could predict the limit value of the chatter vibration, of which the main reason was the outer configuration changes of workpiece in lathe-turning, was proposed. On basis of this method, an application system that could predicate the boundary of cutting conditions, for example, the cutting depth, had also been built up. The input information to the system was a series of changing sizes of the workpiece during lathe-turning. The system, however, has no sub-system to measure the size of the work piece in real-time automatically. To overcome this weakness, a sub-system using picture processing techniques by CCD camera was developed in our resent research. This paper is going to report on how this sub-system has been established and the running results of the new system.