[in Japanese]

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[in Japanese]

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Head alignment equipment for floppy disk drive (FDD) was developed to elevate the quality of FDD. The equipment adjusts the position of upper magnetic head to lower magnetic head relatively with micro meter order accuracy. Prior to the development, the structure of FDD head assembly was improved. To prevent the slip out of upper head in time of screwing, gate shaped plate spring called “hold spring” was added between screws and the fixed part. Size parameters of “hold spring” was decided by combination of finite element method analysis with experiment, and the slip out of the head was decreased to 1/5. The feature of the equipment is a precision movement stage. To avoid the backlash, the stage, is made of 3 axis flexure pivoted levers with displacement reduction mechanism in one body. Owing to these technical settlements, automatic precision alignment of head position was established.

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An external airbag system in which the airbags deploy outside the vehicle before a collision has been developed. The aim of this system is to reduce impact at collision and to avoid secondary aocidents after collision. The key point in this airbag system is “How to decide that a dangerous collision is about to occur.” For this solution, a collision unavoidable region was proposed by taking a vehicle travel trace into account. In the case of frontal and backside collisions, the decision making of airbag triggering is based not only on sensor information but also on the driver's collision avoidance behavior. On the other hand, in the case of encountering collisions, the corresponding unavoidable region was determined from sensing technologies. Simulation results show the effectiveness of the proposed decision making.

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A diamond circular saw blade generates the vibration and the noise when it is rotating at high speed. It is known that the generation of the noise called “whistling noise” causes environmental pollution and reduction of the cutting precision. In this paper, the effects of the frequency and the mode of vibration of the blade on the generation of whistling noise were investigated experimentally and analyzed bx computer simulation, moreover photographing with a stroboscope was performed in order to study the relationship between the whistling noise and the air flow around the blade. According to the observation of the mode of vibration and the air flow around the blade, it was found that the nodal diameter exists every segment part and the vortex of air exists near the slit when the whistling noise is occurring. It was certified that the generation of whistling noise was caused by the vortex of air due to the flexuous vibration of segment part.

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The number of lower limb disabled people has lately been increasing because of traffic accidents and aged society. Most of the lower limb disabled people live daily on wheelchairs. Stairs and steps are considerable obstacles for the people whose living depends upon wheelchairs. Although stair climbable robots have been developed for extreme tasks, they are of large size, heavy weight, and are too forcefull for stairs at home or hospitals. Therefore they are not suitable for welfare purpose at home or hospital. This study aims at the development of stair climbing wheelchair (S.C.W) which offer assistance for the lower limb disabled people. This report describes the legs mechanism of the S.C.W principle for stair climbing and descending movements, and the design of S.C.W prototype

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Piezoelectric XYγ positioning device using impulsive force has capabilities of simple construction, no limitation of traverse length and high resolution. The force that maintains the device to be stationary is only static friction force. Furthermore the motion characteristic is extremely influenced by the conditions of sliding surface. In this paper, the friction control devices were manufactured to improve the motion characteristic of the XYγ positioning device and mounted on the positioning device with three feet of steel ball. These were designed to control the friction force between the each foot and sliding surface individually. As a result, the ratio of movement with three friction control devices to that without one was 1.6 in any directions. The experimental results agreed well with the estimated factor of 1.64. It was demonstrated that the positioning device had capability of a fine positioning less than 0.05μm in translation and 0.6'' in rotation. It was able to rotate around any foot by increasing the friction between the sliding surface and one foot that was to be the rotation axis and removing the friction of the others.

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So far, the researches on SMA (= shape memory alloy) thin film micro actuator for micro machine were reported about the metallurgical aspect, the sputter deposit process and the fabrication of devices with the SMA thin film. However the properties of SMA thin film as servo actuator has not been studied. On the other hand, the several characteristics of bulk SMA wire actuators to control it had been studied. In this paper, based on the same aspect as the bulk SMA wire actuator, the dynamical properties, the mathematical model and control of SMA thin film actuator were investigated experimentally. As the results, the summary is as follows. 1) The mathematical model of output force of SMA thin film actuator is expressed as the nonlinear and continuous function of temperature and strain. 2) The above function is found linearizable. Thus the linear mathematical model was obtained. 3) Tensile force could be controlled by the force sensor feedback system of the SMA thin film actuator.

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This paper proposes a method which represents features in multiple views. The feature is defined as a region which has connected faces by the edges with the same convexity. The model has more than one region corresponding to an individual view. The region is expressed by a similar structure to the half edge data structure, and regions are manipulated by a set of operations which are defined as region Euler operations. The relation of the regions in the same view is represented by a tree structure, and a graph structure which represents the relations between regions in the different views is generated by scanning the common faces which are included in different regions. The range of the influence which the shape change causes on the design and the manufacturing feature is specified, by using the graph and tree of regions. The method of maintaining the correspondence of the region by the feature cancellation is described by using the region Euler operations.

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This paper extends the method for the construction of the intersection graph, which was proposed by the authors for polyhedral solids, to curved solids. In order to be robust against numerical errors, the method exploits the topological connectivity properties of the edge-face intersection points. Furthermore, as a part of the algorithm for the construction of the intersection graph, this paper presents a new method for the computation of the tangent points between an intersection curve and a boundary curve of a surface.

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This paper describes the surface modification of alumina ceramics. Varying the laser fluence, number of pulses and atmosphere, alumina samples were irradiated with an ArF excimer laser. At the fluence of 9J/cm², alumina surface changed smoother and surface porosity reduced in gas atmosphere. While in vacuum smoothing and sealing were not successful. However even in gas atmosphere, more than 500 pulses were required to get smooth surface. From the measurement of removal rate and the observation of luminescence, the reduction in surface porosity and smoothing were caused by redeposition of vaporized alumina. Lower fluence than 9J/cm² made the surface rather rough, and higher fluence caused micro-cracks. In addition, this surface modification method was applied to sealing of an alumina flame spraying film. Similarly surface porosity reduced. The discharge test showed the improvement in sealing of a flame spraying film.

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A hardness test is performed for pure gold using an ultra-micro hardness tester under a test load of 0.02-5.00 gf and a concavity shape is observed using an atomic force microscope. The concavity shape created by two kinds of indenters (Vickers type and triangular pyramid) after unloading is analyzed. The hardness from the width of concavity rim measured by an atomic force microscope is obtained and it is compared with the hardness from the concavity depth under test load and after unloading measured by an ultra-micro hardness tester. The results are as follows : (1) The shape of the permanent concavity rim created under a low test load by an indenter with a small tip radius is similar to that under high load; however, the shape created by an indenter with a large tip radius is different under a load that is lower than 0.1 gf. (2) The hardness from the width of concavity rim using indenters with a tip radius that is smaller than 0.560 μm measured by an atomic force microscope is all the same and is independent of indenter shape or test load. (3) The hardness from the concavity depth is lower than the hardness from the width of concavity rim due primarily to sinking-in phenomena on the surface of pure gold. However both types of hardness have the same value only when a triangular pyramid indenter with the smallest tip radius of 0.100 μm is used.

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In order to develop high efficiency finishing for guide ways of machine tools, hardened and ground die steel SKD61 was lapped by using a robot or a milling machine. Lapping, in general, is carried out on a machined surface to obtain fully flat surface, this means that the machined surface is lapped away completely. In this study, however, the purpose of the lapping is to make a surface having a superior wear characteristics without damage of the geometrical accuracy obtained by grinding. Gray cast iron and a layered soft disk made by a rubber, a sponge and an acrylic resin were used for the lap. It was found that lapping by the robot with gray cast iron lap was difficult because of many scratches and geometrical damage on the lapped surface, while lapping by the milling machine with the iron lap could get a fairly good surface finish without any geometrical damage except some scratches. The best surface finish was obtained by using the layered soft disk lap.

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As the third report of serial studies on welding by high energy beams, penetration mechanisms by carbon dioxide gas laser for aluminum were discussed. Bead-on-plate tests were carried out in various shielding gases, and the cross-sectional shapes of the welds were measured. The fundamental welding characteristics for aluminum by laser beam were estimated in comparison with that by an electron beam and for steels by laser beam. The results obtained are as follows. (1) The chemical reaction between active shielding gas and aluminum is restricted on the molten pool surface, and does not increase beam absorption efficiency in the key hole to form deep penetration. But the chemical compound generated on the surface decreases the threshold beam power to enter fusion of aluminum. (2) Aspect ratio of penetration and melting efficiency for aluminum in O₂ shielding are independent of welding speed, but grow with the increase in laser beam power. (3) The melting efficiency of aluminum welding in O₂ shielding by carbon dioxide gas laser beam with enough high power density attains the theoretical value calculated from a a wedge type volume heat source model, as well as, by an electron beam.

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The aim of this study is to estimate the cutting edges on a grinding wheel surface under various dressing conditions. Therefore, the surface topography of the grinding wheel in the entire periphery is measured in three dimensions using a laser stylus unit on the machine table. At a present report, we investigated positions, numbers and profiles of the cutting edges on the grinding wheel from measurement results under various dressing conditions. As results, it is clear that there are few cutting edges on the outer periphery (depth 3 μn from the maximum height of the cutting edge) of the grinding wheel. In particular, the lead of wheel dressing has influence on the surface of this area. As the dressing leads decrease, the number and the vertical angles of the cutting edges increase.

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In various manufacturing processes, manual tasks by human operators are lately seen through new eyes by virtue of flexible handling ability to a wide range of object. For this ability, the information acquired through their sense organs during operation is considered to play an important role. Conversely, when the operators acquire little sensory information, or when “Sensory Feedback” does not work well, they cannot fully show their ability. In this research, focusing on minute cutting operation with a manual machine tool, a device which translates machining state detected through engineering sensors into human sensory information has been developed and its effectiveness in improvement of operating efficiency, fatigue and tool failure has been investigated ergonomically. The authors call the sensory feedback by using this device “Active Sensory Feedback.” This paper deals with active auditory feedback, active force sensory feedback and combined one. The cutting operations examined are to make a groove on a steel bar with a lathe and to make a small-diameter deep hole on an aluminum block with a milling machine. These are known as difficult and skilled machining operations, because the operators must adjust cutting force delicately so as not to break a cutting tool. So, the cutting force is adopted as the information fed back to the operator through their sensory organs. As the results, active auditory feedback was effective especially for unskilled operators. Active force sensory feedback was also effective, though auditory one was superior to it. But, any active sensory feedback was scarcely effective for very skilled operators, who could make up in the other sense what they lacked in auditory and force senses.

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In the previous report, effects of surface characteristics of case-carburized and hardened steel rollers finished by many surface machining processes upon the surface durability were examined under rolling/sliding conditions using a two rollers contact fatigue testing machine. Consequently, it was clarified that the surface durability of rollers whose surfaces are subjected to processes of shot peening and barrelling after grinding is improved as compared with other processes. The shot peening process induces a compressive residual stress and the barrelling process improves a surface roughness. If the processes of shot peening and barrelling would be applied to a gear with complex configurations, it may be obtained a super high quality gear with the highly load carrying capacity. In the present report, it is actually investigated, in addition to the roller test so as to reconfirm the effects of many processes on the surface durability, whether the processes of shot peening and barrelling can be applied to the tooth surface of the gear like the same as the roller, or not.

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Chatter vibration for irregular tooth pitch end mill has been simulated using time domain cutting simulation based on the regenerative force and dynamic deflection model. The time domain cutting simulation program assumes that the vibration of end mill can be represented by using a lumped-parameter model with two degrees-of-freedom. Furthermore, it treats realistic nonlinearities accounting for the variation of uncut chip thickness, the changing of cutting force direction. In order to get a stability lobe diagram, the results of many time domain cutting simulations are evaluated by the average acceleration of the tool vibration during one rotation. Predicted stability lobes are compared with the results of cutting experiments, and they show that an irregular tooth pitch end mill can lead to an increase of stability. It is difficult to accomplish the quantitative agreement because of the assumptions in the modeling such as the constraint of tool motion and the treatment of process damping. But, the time domain cutting simulation can give the information to find an optimum cutting condition and a chatter free tool configuration.

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A new machining method combining ELID, electrolytic in-process dressing, -grinding and EDM, electric discharge machining, is proposed in order to improve the productivity of precision curved-surfaces such as aspherical mirror. Since the wheel circumference under the ELID-grinding is covered with insulation materials, the electrodes made of graphite or Ag-W compound are inserted around the wheel periphery for EDM. During ELID-grinding, direct current is applied through the electrodes and a workpiece. When Ag-W plates are utilized for the electrodes, active but stable electric discharge have been observed at the grinding point, and grinding forces were successfully diminished in comparison with the conventional ELID-grinding. The roughness of the finished surface, however, deteriorates due to EDM. In order to obtain both machining efficiency and good surface finish, higher table speed is recommended and the down feed must be set slightly larger than the removal rate by EDM.

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A straight wire is not always drawn by the single crystal diamond die, because the hole of die is not composed of isotropic face by the frictional characteristics of the various crystallographic orientations. By means of tilting the die, the wires have the highly inhibitory actions against the bending drawn wire. In these cases, the wires are unified in the distribution of hardness on the skin layer of drawn wire, and the distribution of frictional force ratios on the die hole surface for rubbing by thinner wire. Then, from the diagrams of die holes on the developed chart of diamond crystal sphere represented by the restricted Mercator projection, it is forecasted that the die having the entrance crystal plane on the (100), (110) or (111) plan does not curve the drawn wire. The experimental results by these dies came true as was expected.

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