[in Japanese]

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The interference processing of parametric rational curves and surfaces such as rational Bezier and NURBS is an important technique in CG and CAD/CAM. The geometric Newton method is a basic technique to construct various types of interference algorithms. The conventionally used geometric Newton method is applied to the two-or three-dimentional rational curves and surfaces obtained by the projection of three-or four-dimentional nonrational curves and surfaces. In this approach, if the intersections are at a neighborhood of infinity, it is required to give initial points very close to the true intersections. This paper describes a new geometric Newton method, which is called the homogeneous geometric Newton method, processing the nonrational curves and surfaces before projection, not the rational ones obtained by projection. This homogeneous geometric Newton method can detect the intersections more stably than the conventional method.

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Cam gear is an element of trochoidal gear pair. Generally the tooth pyofile of the cam gear is lead from epicycloid curves, but the accurate profile can not be lead on the flank of tooth without a shift of roller cutter. The value of shift coefficient is varied by gear ratio of roller and cam gear. In this paper, it is proved that a minimum shift coefficient of the trochoidal gear pair is obtained by loci of contact point. In consequence, limits of pressure angle, extents of gear height are shown. And a method of modifying tooth profile is derived.

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Complex structure assembled by many components need to reduce vibration and noise caused by the vibration considering not one part but all part of components. This paper pays attention to structural modification for the noise and the vibration reduction based on transmitted force between components under operating condition. First, frequency response functions of main component, which includes vibration source, and sub-components, which do not include vibration source are measured by modal analysis. Each component is connected at a few points and some sub-components are assumed to cause problem of the noise and the vibration. Second, a location where the transmitted force from the main component to the sub-component decreases is investigated by using mass struc-tural modification, furthermore it is confirmed that this method can reduce not only the vibration but also the noise caused by the vibration.

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The skilled machinist can continuously adjust operations in terms of machining efficiency, machinability and cost. This adjustment is done by means of cutting conditions. In the previous paper, the system was proposed to simulate the machinist's thinking process which set the appropriate cutting conditions based on evaluation of cutting state. The process was constructed by fuzzy integral and hill-climbing. But it had become a serious problem that the try counts on searching of the appropriate cutting conditions using the previous system were nearly four times as many as the skilled machinist's. In this parer, it proposed that the skilled machinist's know-how for improvement of searching efficiency is systematized by neural network. This system which is constructed by introducing the neural network into the previous system is superior to the previous system. By using this system, the cutting conditions which can get the high evaluation is obtained, and the try counts was half as many as the counts using the previous system. The accuracy of the system's output and the improvement of searching efficiency were examined by the experiments under various cutting conditions in turning, and the validity of this system was confirmed.

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The purpose of this study is to obtain a high-precision surface in aluminum alloy reinforced with fibers of carbon. The affections toward formation of surface by the variation of the kind of carbon fiber and the fiber orientation were clarified, and cutting performance of diamond tool were investigated. The results obtained from this study are as follows: In the case of pitch based carbon fiber, the pores were generated by falling-off of fibers and the projections of fibers were formed on finished surface. In the case of mesophase pitch based carbon fiber, the pores were tended to be generated by fracture and falling-off of fibers. The change from the projection to the formation of pore was depended on the angle between the fiber orientation and finished surface. There was a tendency for the projecting rate of fiber to increase at large angle. From X-ray diffraction analysis it may be inferred that tool wear of diamond is mainly abrasive.

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This paper deals with the load distribution and the guiding accuracy of x-table assembled with two cross roller guide units applied for electric spark machine, semi-conductor manufacturing machine, etc. The load distribution formula is derived under the application of vertical and horizontal external load, pitching, rolling and yawing moments. Both theoretical and experimental results are discussed under various load eccentricities. The followings are the reached conclusions. (1) Even if only a vertical load is applied on the midpoint of x-table, the distribution loads on each roller are considerably become one side contact situation at both stroke end positions of the x-table, due to the mechanical motions in accordance with the movements of x-table and cross roller cages. (2) To give a moderate preloading under the large load eccentricity condition for the cross roller guides is effective against the load distribution, rigidity and guiding accuracy. (3) It is made clear that the theoretical results are agreed with the experimental ones, those are the calculated values from the measuring ones by means of six electric micrometer sensors setting up for the two straight edges aligned with the x-table, that is the vertical and horizontal displacement, pitching, rolling and yawing angle, respectively.

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A new building process of three dimensional photofabrication is described which reduces surface roughness of parts. As CAD model is sliced into many thin layers in the three dimensional photofabrication process, smooth surface is converted into steps. Furthermore laser beam faithfully creates models not only their details but also steps. The influence of steps is dominant to the bad impression of the model's surface smoothness compared to its original design, if a gradient or an angle of inclination of surface is low. The proposed new process showed an improvement of surface roughness, especially on the gentler slope.

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The machinability of high strength sintered alloy steel from different powder, partially alloyed and fully alloyed powder, was studied, and improvements of the machinability of the steel with free-machining additives, complex oxide (2CaO-Al₂O₃-SiO₂) and MnS, were tried. The steel tested had a chemical composition of Fe-4Ni-0.5Mo1.5Cu-0.5C and a density of 7.2 g/cm³. Carbide tool P 10 was used for the tests. The machinability of the steel depended on the powder to be sintered. The steel sintered from partially alloyed powder had a better machinability than that from fully alloyed powder. Chipping, however, was often observed on the cutting edge of the tool in machining the former. Since the chipping, the tool life was very unstable. Furthermore large crater wear and flank wear at the depth of cut were also observed under high cutting speeds. Addition of a complex oxide to the steel made the crater wear smaller, but as for the chipping, the oxide had no effect. While MnS in the steel suppressed the chipping, the flank wear became larger on the contrary. Only simultaneous addition of the oxide and MnS into the steel made chipping, flank wear and crater wear smaller.

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A compensation method of measuring probe diameter was presented for discrete points of surface profile data. To evaluate the local asperity tip geometry on surface topography data, the segmental area and volume in a certain assessment area were proposed in contrast to the radius of curvature obtained by a best-fit circle near an asperity summit. It can be seen that these new parameters are sensitive to subtle change in asperity tip geometry in the case of extremely small radius of curvature. Consideration was also given to the correlation between asperity tip geometry and summit height.

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An optical hole-diameter measuring instrument has been developed. The instrument, which consists of two laser diodes, one photo sensitive detector, two condenser lenses and some mirrors, is intended to measure, based on trigonometry, the distances to the hole wall on two sides alternately. The optical, fundamental analysis and experiment showed that it was possible to measure the distances to the object having not only a mirror-like plane surface but also a rough, cylindrical surface such as a drilled one. Using the instrument, which was manufactured on trial, it was found that the width between block gages and the hole diameter of a ring gage could be measured within the accuracy of 10μm and that it was influenced by the position of the measuring probe and the inclination of the measured object. The deviation from the desired values may be attributed to the impropriety of calibration, the misalignment of irradiation of two laser beams and the nonlinearity of optical and electrical elements.

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An accurate and practical system for the measurement of rolling that occurs with the movement of a machine tool unit has been developed. The system consists of a bi-prism, two plane mirrors, and a double-path optical heterodyne laser interferometer. The measurement of rolling with this system is not affected by pitching, yawing, heaving, and swaying. The measurement system was confirmed to have a sensitivity of 0.032μm/arcsec (variation of path length/unit angle of rolling), a resolution of 0.31 arcsec (used in λ/64 measurement system), and 800 mm travel length. In order to investigate the rolling that occurs in a machining centre (680 × 500 × 630 mm), the measurement was carried out in full stroke of each unit in the machining centre. The results show the reliable agreements in replication measurement.

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This paper describes development of a new non-contact 3-D profile sensor which is not influenced very much by inclination angles and edge profiles of 3-D free form surfaces. The proposed 3-D profile sensor called “optical ring image sensor” has two major advantages. First, reflection light from a target surface in optical axis can be detected in all directions using a ring slit. Second, the radius of optical ring image is linearly proportional to the displacement of the surface in optical axis. In this paper, a prototype of optical ring image 3-D profile sensor with unique properties mentioned above is designed and produced. From onmachine measurement using NC machine tool as well as fundamental experiments, this sensor makes it possible to measure the displacement within an accuracy of about ±7μm for the steeply inclined diffuse reflection surface up to ±80° and also about ±10μm even for a nearly specular reflection surface inclined up to ±70°. Therefore, it will be a very useful sensor for 3-D profile measurements of delicated shaped surfaces.

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In the small gripper studied by the authors, a piezoelectric stack actuator is employed because of its suitable size, high resolution and high rigidity, and controlled by electric charge feedback which can make the hysteresis very small. The gripper has an enlargement mechanism consisting of hinges and arms against the small displacement of the actuator. A strain gauge is stuck on the finger as a sensor of the holding force. Thus, a simple and fine force control of the gripper is made possible in the range of 0-40 mN, where a good linearity between the input and the output of the system is obtained and the settling time of the step response is less than 0.19s with a very small overshoot.

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This paper presents one tuning method of servo parameters of single axis servo drive system in NC machine tools. In this method, using computer simulation on mathematical model of feed drive system, servo parameters are tuned as maximizing servo stiffness. As a result, high servo stiffness was achieved than that can be given using standard servo parameters. In experiment, servo stiffness of existing feed drive system of machining center was measured and closely reflected the results of the computer simulation. It was also shown that droops of each axis was reduced in boring.

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Nowadays precise estimation of performance characteristics of a robot is being necessary. An ultrasonic measuring system of 3-D position and orientation of a robot for this purpose has been already proposed, of which principie is a triangulation using distances between transmitters attached to a robot arm and receivers placed around the work space of the robot. An electric spark which works as a non-directional point source of ultrasound is used as a transmitter. In this paper the development of this transmitter is dealt with. By inserting a condenser of a few hundred picofarads to the secondary side of an ignition coil in the electric circuit of the transmitter, the sound pressure of the radiated ultrasonic pulse becomes about ten times as stron3 as the case in which the condenser is not inserted. The directivity of this transmitter was investigated experimentally. An ultrasonic ranging system which uses this transmitter was also developed and causes of the ranging error were discussed.

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A new type of Infrared Radiation Pyrometer using a fused fiber coupler is made, and its characteristics are investigated theoretically and experimentally. This pyrometer can be applied to measure the flush temperature of a small area on ceramics (PSZ) when it is irradiated with CO₂ laser. In this pyrometer, the infrared rays radiated from the object are accepted by an optical fiber, and divided into two parts and transmitted to the two types of infrared detectors by a fused fiber coupler. The temperature is obtained by calculating the ratio of the output voltages from these two detectors. The characteristics of this pyrometer are as follows. It is possible to measure the temperature with controlling the disturbance of the emissivity. When the object has a surface of uniform temperature, the measuring temperature does not depend on the size of the object. In the case when the object has the distribution in temperature, it is possible to estimate the maximum temperature correctly from the experimental results

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To measure the 3-dimensional profiles of objects with free-form surfaces such as in pattern making and die sinking, a new optical noncontact measuring sensor is proposed in this paper. The optical sensor is based on the triangulation method in order to obtain the signal which is proportional to the displacement of the object surface to be measured. In the optical sensor, a linearly polarized laser beam illuminates the surface. The depolarized component of the light scattered from the surface is detected, excepting the specularly reflected light, by using optical components. Therefore, the profiles of diffuse reflection surfaces and metal surfaces can be measured by using the optical sensor. Using the optical sensor, a spherical surface of 4 mm diameter, coated with white paint, can be measured over ±73° in inclination angle and with 3.3 μm in standard deviation from values measured by means of a contact coordinate measuring machine.

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