Sensors that detect the mechanical quantity are shifting from the bulk type to the MEMS type for the miniaturization, the cost reduction, and high reliability.1)∼4) Regarding the acceleration sensor, the resistance type and the capacitance type made by the MEMS technology have been commercialized. However, the sensitivity is still a weak point to those sensors. It is considered that there is an advantage of sensitivity in the resonance type because the mechanical resonance is used. In this study, we clarified the relation between sensitivity and the size concerning the newly designed resonance type acceleration sensor by the numerical simulation. Next we evaluated the sensor characteristics with the 20-times enlarged model. As a conclusion, it was confirmed that the resonance type had a potential for realizing the high sensitivity micro acceleration sensor.
A novel device that enables fixing small objects at a specified point on a silicon substrate was developed. It will be useful if cell or other small objects can be fixed in a row on a chip and drug dosage to the each object can be controlled. By arranging objects in a row, observation will become easy and quick. In this study, patterned through chip porous Si areas were made using photolithographic patterning and anodized porous silicon. Permeability of air and water through the porous layer was measured. It was demonstrated that a polystyrene bead dispersed in pure water was fixed on a through chip porous area of 7μm×7μm by vacuum suction.
This paper deals with the improvement for Zero positioning error of machine tool element under room temperature change. During operation the temperature at fifteen positions of the hollow ball-screw is measured and input into the personal computer by the optical telemeter system. Based upon the temperature distribution of ball-screw, the present position of ball-screw nut obtained from CNC controller and the information of initial positioning error, the compensating quantity for Zero positioning error is calculated. The compensating quantity is fed from the PC to CNC controller, and the origin shift of machine coordinate is immediately executed. These measurement and control are repeatedly executed during operation, and the real-time compensation is realized. Only once the measurement of initial positioning error is needed. It is clarified that the positioning error of -8.4∼+1.5μm is realized under room temperature change of 16.5∼26.5°C during 23.5hr operation.
In the 1st part of this investigation, a cutting model taking account of the condition of side-curl of the chip proposed in previous paper has been extended to milling process in which both cutting edges of the sphere and cylindrical portions engage with the workpiece. Geometric quantities such as contact region between the cutting edge and the workpiece surface, undeformed chip thickness along the cutting edge and area of cutting cross-section in upward or downward milling of inclined surface has been analyzed. In this paper, the cutting forces and chip formation in above upward or downward milling for various inclined surfaces are predicted by using the cutting model and energy method. Three components of the cutting force are measured by a piezo-electric type dynamometer and compared with those obtained through theoretical prediction. The predicted results are good agreement with the experimental results. From the comparison of chip form described by using the predicted value of chip flow angle and radius of side-curl of the chip and chip form obtained experimentally for various inclined surfaces, it is shown that transition of the chip form with inclination angle of the warkpiece surface can be analytically obtained.
High pressure micro jet is often used for single-substrate cleaning processing of electronic devices, but its cleaning mechanism has not been fully clarified yet. In this study, while sizes and velocity of fine cleaning liquid droplets sprayed out of the high pressure micro jet system are measured using Shadow Doppler Particle Analyzer, experiments are carried out to see cleaning efficiency for true spherical particles of polystyrene latex stuck on glass substrates. As a result, it is found that cleaning efficiency of high pressure micro jet system is highly correlative with velocity of cleaning liquid particles, where radiant flow by collision of cleaning particles has a profound effect.
In this paper, the MQL turning of two types of ferrous metals: chromium-molybdenum steel SCM440H and pearlite malleable cast iron FCMP: is dealt with. The appropriate generating system of oil mist is constructed and the specified turning tool with oil hole is used. In order to verify the cooling effect of MQL, the tool temperature at the flank face is measured using a newly assembled fiber-coupled two-color pyrometer. In this new technique, a sensing fiber is inserted into a small hole that extends to the outer surface of the tubelike workpiece and it rotates with the workpiece. The thermal radiation accepted by a sensing fiber is noncontactly transmitted to the other fixed fiber and led to the two-color detectors. As for cutting force in turning of SCM440H, MQL is more effective in low cutting speed below 100 m/min. The tool temperature in MQL turning is approximately 100°C lower than that in dry turning over the wide range of 30∼300 m/min. In the case of FCMP, the tool temperature in dry turning at a cutting speed of 600 m/min reaches as much as about 1040°C, but it drops 920°C in MQL turning.
A pneumatic servo bearing actuator for ultraprecise positioning consisting of a servo amplifier, a pneumatic servo valve and an aerostatic bearing is proposed as a new actuator construction in this study. As the first step of the study, this report presents a system representation of the actuator on the concept of lumped-parameter bearing model and four-terminal circuit theory, where the input parameters are the pressure controlled by a servo valve and the mass flow into the bearing clearance, while the output ones are the load capacity of the bearing (thrust force of the actuator) and the bearing gap (displacement of the actuator). Fundamental characteristics of the actuator - rated thrust force, stiffness, damping coefficient and dynamic response - are presented through the system representation, and its potential to realize an ultraprecise positioning is comprehensively discussed.
Micro drilling is required in order to produce nozzles for fiber, fuel and so on. This paper deals with cavitation effects when applying ultrasonic vibration on machining fluid in micro through-hole drilling. In addition, burr and tool life are investigated when micro-drilling on SUS304 under various feed speeds. The obtained results are as follows. Cavitation occurs in a blister generated by machining fluid at the exit hole in through-hole drilling. The burr height in cavitation assisted drilling is smaller than that in conventional one and increases with the drilling number. The tool life in through-hole drilling is same as in blind hole one under various feed speeds and is the longest at a feed speed of 200mm/min. The effect of cavitation on the burr removal was investigated using B4C powder and was observed at the early drilling holes.
Homogeneous nonequilibrium low temperature plasma was generated under atmospheric pressure by high voltage pulsed power (1 kV, 20 kHz) excitation of He gas or mixture of He and O2 gases. Using this cold plasma, ZnO thin films were fabricated on glass substrate exposed to air by feeding Zn-MOPD into the plasma with He carrier gas. Dependence of O2 gas flow rate on optical transmittance of the ZnO films and resistivity were investigated. In addition, crystallinity and microstructure of the films was studied by XRD measurement and FE-SEM observation.
Self-excited vibration of a film caused by air flow is analyzed to realize an electric power generator which has a flat shape and is driven by wind energy. First, the concept of the generator is explained and generation of the self-excited vibration is verified through experiments. Second, an approximate calculation method of the self-excited vibration of the electrode film is contrived and the effect of the input air pressure, film tension, boundary pressure on the vibration frequency and easiness of vibration generation are clarified. Also the calculated results are compared with experimental ones to verify the validity of the analysis.
Backlash of reduction gear produces troubles in the case of positioning of robots and NC machine tools. It sometimes causes deterioration of positioning accuracy and self-excited vibration. In our first report, a basic simulation model of backlash model was proposed and conditions of twin motor pinion and output gear was analyzed. Experimental results of servo stiffness improvement and 1 pulse positioning accuracy were reported. In this study, a new control method is proposed which is based on simulation analysis by Matlab/simulink. At first one axis simulation model is developed and it is expanded to twin motor control model. The benefit of the new control method is certified by experiment.
Image reconstruction characteristics of the surface plasmon (SP) holography, which is composed of silver film supporting the SP propagation and hologram layer diffracting the SP wave, are investigated. From the viewpoint of the dependence on the SP hologram structures, a silver relief deposited on a dielectric hologram and a dielectric hologram placed on flat silver film are experimentally demonstrated and compared. The reconstructed image by silver relief hologram shows extremely high diffraction efficiency under He-Ne laser excitation even though the modulation depth of hologram is quite shallow. In white light reconstruction, it is found that the appropriate design of the structure makes it possible to control the color selectivity and also realize efficient white color reconstruction. The differences in the reconstruction properties are discussed in terms of the structural aspect of SP holography and SP excitation mechanisms.
A new theoretical formulation for re-entrant flow shop scheduling problem is derived to plan an optimum production schedule by mixed integer programming. Flow time, which is an index of the evaluation of the planned schedule, is minimized to decrease amount of work-in-process. Cycle time, which is another important index, is determined by the total load time on a bottleneck machine to manufacture the products at the highest productivity. Both objective function and constraint conditions are described in linear expressions and a general optimization tool is adopted to solve the formulated scheduling problems. Another objective function is also introduced in order to shorten the time for the optimization. Computational scheduling results obtained by the optimization are evaluated and discussed in the present paper.
This paper addresses a countermeasure against the transmission of the floor vibration for electron microscopy. According to the rocking mode formed with the frame and the rubber on the floor, the vibration over 40Hz was increased horizontally at the vibration isolators on top of the frame. In addition, the vertical vibration over 40Hz on the floor showed different phase at each foot of the frames that cause the inclination of the frame. This inclination also caused the horizontal vibration at the isolators even if the frame had been rigidly fixed to the floor. In this paper, we used these two causes to offset the horizontal vibration each other. Thin layers of the viscoelastic material that have high damping coefficient were set under the frame, which restrict the inclination of the frame at the eigenmode. By tuning the natural frequency of this mode slightly lower than the frequency of the inclined floor vibration, the horizontal vibration at the top of the frame was offset. Moreover, the tuned thin layer structure increased the damping coefficient of the twisting mode of the frame and decreased the vibrations in much higher frequency over 400Hz excited by acoustic noise. These tuned thin layer structure helped to avoid the amplification of the vibration above 40Hz and to decrease the fluctuation on STEM image. This tuned thin layer structure has already applied to the electron microscopes on the market.