Unstable vibration occurs in the vicinities of the major critical speeds of an asymmetrical shaft system. It also occurs in a wide speed range above the major critical speed of a shaft with a hollow rotor partially filled with liquid. The occurrence of unstable vibrations is a serious problem because the amplitude increases exponentially and the system is destroyed. However, no simple effective means for unstable vibration suppression is known before. Active vibration control is usually complicated and costly. In this paper, we show that the simple method proposed to suppress steady-state vibration utilizing discontinuous spring characteristics is also effective to suppress unstable vibrations. The unstable vibration changes to an almost periodic motion and we can suppress amplitudes to an arbitrary magnitude even in an unstable range. The validity of the proposed method is also verified by experiments.

抄録全体を表示

Recently, in order to increase the performances of rotating machinery, the radial clearance between the rotor and casing has become smaller and smaller. As a result, if the rotor contact with casing, severe self excited vibration may occur in the rotating machinery, so called “Dry-Whip”. Especially, self excited vibration with change of rotating speed (Contact type backward whirling) is able to occur under very small clearance condition. This paper presents an analytical and experimental study of such self excited vibration due to the contact which occurs between rotor and casing system under the finite driving torque. As a result, it is shown that the rotor shows two different vibration behaviors due to some physical conditions of the system (for example, the natural frequency of casing). These behaviors show the following difference. 1. vibration of different phase between rotor and casing (zero or 180 degrees). 2. amplitude of whirling which is larger than clearance or not. 3. frequency of rotor and casing whirling which is higher than natural frequency of casing or not. And then, it is shown the frequency of self excited vibration at steady-state, theoretically. Finally, the effect of physical condition of the system for those phenomena is made clear by parameter study.

抄録全体を表示

A Magnetic Bearing Wheel (MBW) with inclined magnetic poles is under development. This paper deals with the low disturbance control method of MBW based on the disturbance feedback. This control method generates the rotor displacement command that converges synchronous and harmonic components included in the disturbance of MBW to zero. This control system can be stabilized by adding appropriate phase lead as a function of the rotational speed of the rotor to the rotor displacement command. Based on the stability analysis by root loci, a simple adjusting method of the phase lead parameters is proposed. Next, the effectiveness of this control method is verified by the numerical simulation and the experiment. This control system enables the disturbance of MBW to decrease to 0.1 N_rms, /0.045 Nm_rms or less in all rotational speeds up to 6000 rpm.

抄録全体を表示

Exact derivation method of all periodic solutions for zero stiffness, viscous damping free forced vibro-impact systems is proposed in this paper. First, specific initial condition which make solution periodize is determined using pseudo-feedback approach. By means of substitution this initial value into a globalized general solution, global function form of all periodic solutions includes symmetric and asymmetric types can be represented by superposition of periodic stationary solution of base linear system, finite number of weighted summation of periodic functions caused by impact nonlinearity and their constants parts. Two types of invariant relations for quantity of periodic solution are also derived. Finally, numerical simulation calculating typical asymmetric periodic solution is perfomed. The validity of the proposed method is confirmed.

抄録全体を表示

Vibration isolation system using zero-power magnetic suspension is modified. A suspension spring is introduced in parallel with a series connection of a zero-power-controlled magnetic suspension and a normal spring that were used in the previous works. It can reduce the load force that the zero-power magnetic suspension has to bear. A basic configuration of the modified vibration isolation system is shown. It is demonstrated both analytically and experimentally that the modified system maintains infinite stiffness against static direct disturbance even if such a spring is added. The characteristics to dynamic direct disturbances are also studied experimentally.

抄録全体を表示

It is important to reduce the vibrations of an Interior Permanent Magnetic motor that is generally installed in electrical vehicles, fuel cell vehicles, and hybrid electrical vehicles. The purpose of the study here is to build up the reduction methodology of the radial oscillating force that causes the radiation noise from the surface of the motor case by controlling the working currents on IPM moror. The distributed winding IPM motor with 48 teeth on the stator and 4 pairs of poles on the rotor is treated. The relating equation between the radial force towards the stator and three phase alternating currents is provided firstly, utilizing the radial force that results from the Finite Element Analysis of the plane electromagnetic field. Secondly, high order currents are derived from the equation and superposed on the basic currents in order to reduce the radial oscillating force. Finally, the plane electromagnetic field analysis is performed again with the currents including the high order ones and a radial oscillating force reduction of about 20 dB with a torque increase of 2.8% is obtained.

抄録全体を表示

Ball Bearings are critical components in rotational machineries. Although various diagnostic methods have been proposed, most of them are based on passive methods utilizing the signals generated from rotating machineries themselves. Such passive methods usually require continuous measurement and have limited resolution on the damage in certain circumstances. In this paper, a new active diagnostic approach using amplitude modulation of the ultrasonic waves is proposed. By introducing this modulation, we are able to widen the frequency range of the signals. The ultrasonic waves are constantly emitted to the target ball bearing to pick up the damage signals. The signals generated from ball bearings that have strong correlations with the possible damage result in modulation of the carrier waves. Thus, change of signals such as amplitudes and frequencies associated with abnormality of ball bearing can be detected.

抄録全体を表示

Tire is a key to a good performance of road induced noise (road noise). Development of the performance would be more effective by deep consideration with suspension and wheel. Coupled vibration analysis between suspension and tire/wheel has given suggestions to understand and to improve their vibration. This follows the application to tire and wheel for a rumble noise around 160 Hz in this paper. Successful and practical technique is developed for this analysis. It is a modal transformation of analytical degree of freedom (DOF) at their conjunction points. The DOF is reduced from seven hundreds to some tens and finally to two by transfer path analysis (TPA). By referencing results of numerical study, a set of modified tire and wheel is prepared. Its experiments show the improvement of road noise and verified that this approach was useful practically.

抄録全体を表示

This paper discusses the reduction of noise in a cavity from a viewpoint of cluster control. First, cluster filtering that enables the extraction of desired control information out of a set of sound pressure sensor outputs is presented. Cluster actuation classified as the duality of cluster filtering is then proposed, whereby activating only the target cluster among an infinite number of acoustic modes of a cavity. Using both the cluster filtering and actuation, clustered active noise control (C-ANC) is proposed, permitting one to suppress the targeted cluster independently. In contrast to a MIMO system conventional ANC generates, a C-ANC system comprises SISO systems, thereby reducing computation load on control effort significantly. With a view to elucidating the validity as well as potential C-ANC possesses, a rectangular cavity is introduced as a target structure where eight sensors/sound sources are provided for cluster filtering/actuation. It is found that acoustic potential energy of the cavity is grouped into eight clusters due to the cluster filtering, each sub-potential energy being suppressed independently because of the cluster actuation without causing any spillover.

抄録全体を表示

Severe random vibration is easily induced to satellite structure during the flight. Acoustic test at ground is applied to verify the structural design and abnormal function of equipment. An accurate prediction of acoustic induced vibration response of equipment, therefore, is critical for design purposes. Especially for a satellite exterior panel, it has been shown that two subsystem statistical energy analysis model composed of an acoustic chamber and a single panel will simplify the analyses approach and gives a satisfactory result. This paper derives two subsystem SEA model for the prediction of the exterior satellite panel and formulates the damping loss factor equation based on the experiment data. Moreover, the upper bound value of the two subsystem SEA model is presented for further simplification with which response is obtained without structural damping loss factor and radiation coupling loss factor. These two models were validated well by acoustic tests of eleven satellite honeycomb panels.

抄録全体を表示

In this paper, a practical method to design a noise reduction controller is proposed. In this method frequency domain of interest is divided into subbands taking frequency response of noise into account. And on each subband, it is proposed that the controller is tuned based on partial model matching on frequency domain. The proposed method is practical since it requires only input-output data for the tuning process instead of identified mathematical model of the plant. In order to show validity of the method, it was applied to an actual room with a stereo audio system. The experimental result shows that the proposed controller designed succeeded 45% attenuation of multiple peak noise.

抄録全体を表示

The purpose of this paper is to show a way to reduce the influence of an acoustic cavity mode in a cabin about agricultural machinery. The hexahedron chamber, regarded as the tractor cabin, is investigated. In this research, indoor acoustic cavity mode and the influence of the side-branch type resonator, tuned to the frequency of acoustic cavity mode, are measured and analyzed. It is shown that the resonator enables the frequency of acoustic cavity mode to move, so the resonator works like a dynamic absorber. Consequently, the way to control the frequency of an acoustic cavity mode is to add a resonator, which can change corresponding to the excitation frequency. Opening and closing the hole connecting to original chamber and resonator, one can make the frequency of acoustic cavity mode change. Moreover, the acoustic characteristics of the actual tractor cabin are analyzed. Comparing the experimental results about distribution of sound pressure and the effect of the resonator with those by software SYSNOISE, it is shown that the influence of an acoustic cavity mode is also reducible in the actual tractor.

抄録全体を表示

In this paper, we propose a new method for a hammering test by using image and sound signal processing techniques. A method for discriminating a property of an object with the use of generated sound when striking it with a hammer is called a hammering test. However, this method depends on human experience and skills. In addition, if we perform this test over a wide area of objects, it is required to manually record hammering positions one by one. Therefore, this paper proposes a hammering test system consisting of two video cameras that can acquire image and sound signals of a hammering scene. The shape of the object is measured by the image signal processing from the result of 3-D measurement of each hammering position, and the thickness or material of the object is estimated by the sound signal processing in time and frequency domains. The validity of proposed method is shown through experiments.

抄録全体を表示

A new optimization method which can search for the global optimum solution and decrease the number of iterations is described. The feature of the new method include creating orthogonal arrays and changing the level value of design factors for every search step. The performance of the method involved observing the optimization problem of single- and multi-peaked functions for which the global solution was known in advance. The newly developed method is found to be very effective for establishing a global optimum solution to these problems.

抄録全体を表示

This paper proposes a modeling and active suspension control strategies for an elastic vehicle. Vehicles designed with lightweight become flexible and easy to vibrate in nature. Then riding comfort and operating stability of the elastic vehicle are reduced as a result of vibrations and elastic deformations. In order to express vibration and motion of the elastic vehicle stability for control, the Extended Reduced Order Physical Model developed for the flexible multibody dynamics is adapted. For designing the active suspension control system, two kinds of control algorism are used and compared with each other. It is demonstrated through control simulation and experiment that many modes of vibration of a simply scaled body that assume the elastic vehicle are well controlled.

抄録全体を表示

This paper examines the feasibility of Direct Yaw-moment Control (DYC) in the context of lane keeping system. The DYC, which is generated by differential traction force distribution, is designed with consideration of the road image information to assist the driver's steering maneuver for lane keeping task. Consequently, the controller is designed to regulate the lateral deviation based on the lane marker position acquired via CCD camera with on-board image processing system. The effectiveness of the proposed control system was verified by actual driving test with micro electric vehicle equipped with two independent in-wheel-motors for generating DYC.

抄録全体を表示

In this paper a new steering control scheme for tractors and semitrailers combination is developed so that good robust steering stability can be assured. To meet this end, at first, a new method to design an ideal model is proposed. Then, a new robust tracking controller with an integrator is developed. In the closed loop system using the proposed controller it is theoretically shown that robust stability can be easily achieved and robust tracking performance can be easily improved by using only one design parameter. It is also shown by numerical simulations that the proposed controller is effective for tractors and semitrailers combination even if nonlinear formulas of tire slip angles are took into consideration.

抄録全体を表示

This paper covers driver's information processing of forward vehicle following to discuss about control characteristics of driver. Using a neural network system, driver's information processing is simulated by constructing a driver model to reproduce driver's control behavior. The data used to construct the driver model was collected by a driving simulator. At the result, it was found that this model was able to accurately reproduce driver's control behavior. After that, driver's control characteristics were shown by factor analysis method that was used to calculate the contributing rate of inputs for driver's control behavior. The result showed the greater importance of relative information over vehicle information. Finally, major variation of information processing was expressed in some phases of control behavior, and remodeling between these phases showed control characteristics in more detail.

抄録全体を表示

Numerical full vehicle simulations are becoming powerful tools for evaluating motorcycle performance. Among various motorcycles, motocrossers are most easily affected in their motions by rider-operations. We have developed a simulation system including motocrosser motions and rider-operations. The simulations of three accelerating patterns and two typical jumping patterns have been conducted taking the experimentally measured rider-operations as well as soil-tire traction parameters into account. The agreement of simulations and experiments indicates that the simulation system works effectively in analyzing dynamics of motocrosser-rider systems.

抄録全体を表示

It is a very important subject to reduce chest deceleration when frontal crash impact of vehicle occurs. One of the most efficient methods of reducing chest deceleration is to optimize pelvis deceleration of vertical direction. The purpose of this development is to design a new concept of and submarine device, which is more efficient, economical, and no partial injury of human body. This developmental new device can lift up the anti submarine pipe toward pelvis direction by utilizing inertial force, which occurs in frontal crash impact of vehicle instead of using pyrotechnical explosion power that acts by the signal of electronic crash sensor. Through this investigation, we also obtained that it became possible to reduce chest maximum deceleration of horizontal direction by increasing pelvis deceleration of vertical direction in the first period of vehicle crash and by decreasing pelvis deceleration of vertical direction in the middle and the latter period of vehicle crash.

抄録全体を表示

The volar tactile sensations of the blind and the sighted subjects were measured using two tests : static two-point discrimination test (s2PD) and moving two-point discrimination test (m2PD). Twelve blind subjects (age range 19-72 years, mean 36 years; one female; mean Braille reading experience 27 years) and ten sighted subjects (age range 21-24 years, mean 22 years) participated in this study. The volar side of the right hand of subjects was divided into 29 areas each, according to the location of finger joints and the innervation regions of peripheral and peripheral nerves. The s2PD thresholds of blind subjects were significantly shorter than that of sighted subjects at 19 areas on the volar side of hand. However, there was no difference between the m2PD thresholds of blind subjects and sighted subjects at all 29 areas. In addition, the m2PD thresholds of blind subjects were significantly shorter than the s2PD thresholds of them at only two areas. So, blind subjects have superior tactile sensation on the volar side of hand for both static and moving stimuli.

抄録全体を表示

This study investigated how knee flexion angle and tensile direction affect the strength of anterior cruciate ligament (ACL) insertion to tibia using swine femur-ACL-tibia complexs. Four tensile tests at displacement rate of 10 mm/min were performed at flexion angles of 0°, 45°, and 90°on the condition that the tensile direction was along the tibial axias, and at flexion angle of 90° on the condition that the tensile direction was along the femoral axis. The modes of failure and load-displacement curves were measured and compared among all tensile tests. As for the mode of failure, there was a difference between the tensile direction along the tibial axis and along the femoral axis. At flexion angles of 0°, 45°, and 90°on tensile direction along the tibial axis, the ACL failure occurred initially by failure of posterior lateral bundle followed by failure of anterior medial bundle until the complete separation of ACL to tibia, whereas at flexion angle of 90 on tensile direction along the femoral axis, the avulsion fractures suddenly occurred. As for the load-displacement curve, the maximum load at flexion angle of 0° on tensile direction along the tibial axis was significantly larger than that at flexion angle of 90°. The maximum load at flexion angle of 90°on tensile direction along the femoral axis was larger than those at flexion angles of 45° and 90° on tensile direction along the tibial axis. Therefore, the strength of ACL insertion to tibia was affected by both knee flexion angle and tensile direction.

抄録全体を表示

Predicting and estimating attendant's work propelling wheelchairs is need for safe and comfortable design of assisted powered wheelchairs because propelling force determines assist force to drive wheelchairs. We investigate the propelling force against wheelchair's load based on road resistance mainly using a newly produced treadmill analyzing and obtaining suitable propelling motion against loads. The load is created by feedback of belt velocity from detected pushing force along with defined load characteristics. We determine and estimate attendant's force against various load value with the experimental system at one subject on a level and among-8-+8 deg. slopes. We obtained the pushing force and walking velocity with exercising heart ratio, and calculated mechanical power of propelling wheelchair. The result shows that the power is about 30 W in a level. On upward slopes, the power decreases because attendants need energy to climbing themselves. Finally, attendants need proper assist force on road conditions.

抄録全体を表示

This paper describes a novel method to measure the rotation of golf swing form. The sensor employed in the measurement method is a gyro sensor with rotation measuring. Because this sensor is small and light, the suggested method enables us to utilize it easily not only in limited places such as university and company research facilities but also out door. The system developed by using the three dimensional gyro sensors set at the left hand, fore arm, shoulder and waist can catch the three dimensional rotations. The method achieves a difficult measurement of cock and roll motion. This measurement system can analyze the major features of golf swing, which makes it an effective method for suggesting more dieal swing form. The method is developed for golf swing form measurement, but it can applied to baseball, tennis and so on.

抄録全体を表示

A stand alone wearable power assisting suit has been developed, which gives nurses the extra muscle they need to lift their patients and avoid back injuries. In order to put a stand alone power assist suit to practical use, sensing system and the mechanism have been improved. To stabilize the muscle hardness sensing system more, the sensor of the all-in-one design that built the sensor into meshed belt was developed and the sensing characteristic of the muscle sensor were improved. The improvement in the mechanism was advanced so that a movable range of the suit was expanded and the content of the work wearing the suit was expanded. The output torques of the actuators increased by increasing the number of the cuffs inserted into the actuators. According to the equations derived from static body mechanics using the joint angles, the necessary joints torques for maintaining a position were calculated by an embedded microcomputer and the necessary joint torques were combined with the output signals of the muscle sensors to make control signals. An exoskeleton for measurement having the same frame and potentiometers as the power assisting suit was developed. The muscle forces were measured by applying the exoskeleton to the human body and it was proved that the each unit of the suit transmitted assisting torque directly to each joint, and by wearing the suit to the body the weight could be lifted by half or less muscular power, i.e., muscular power became twice or more.

抄録全体を表示

In the previous study, we developed a tactile mouse featuring a fine pin array, the purpose of which is to be effective in virtual reality and tele-existence systems. It features an 8-by-8 array of stimulus pins each measuring 0.3mm in diameter and with a 1.0-or 1.8-mm pin pitch. Since the stimulus pins within the display's pads can be made to protrude above the pad's surface and their motions are controlled by piezoelectric actuators, the operator can feel various combinations of pins protruding according to the surface texture of the virtual object. In order to establish a design method for the tactile displays, we performed a series of psychophysical experiments using the display. By evaluating variation in threshold for discriminating crossed angles of virtual lattice textures under different pin arrays, texture density, and pin strokes, we determined suitable pin pitch, presentable density and ridge height of the virtual texture. It was found that the two-point threshold should be adopted as the pin pitch between pins in the design of the tactile display. The presentable density and ridge height of the virtual textures were N=50 and δ=0.3mm. Finally, we compared the discrimination precision of virtual textures with those of real textures to evaluate the present tactile display's presentation quality. Since the difference threshold for the real texture was 1/3 that of the virtual texture, the present tactile display should be improved with respect to shearing force presentation to simulate relative motion feeling between the finger surface and virtual object surfaces.

抄録全体を表示

This paper proposes a new static elastic model of a hemispherical soft fingertip via a large contact deformation, which is required for handling and manipulation process of an object by means of a robotic hand. This work focuses on the formulation processes of an elastic force and its potential energy caused by the large deformation due to the contact with a planar object. These physical quantities are derived by introducing the infinite number of virtual springs inside the soft fingertip. It is firstly shown that these equations are functions of two variables : the maximum displacement of the hemispherical fingertip and the orientation angle of the object, and the elastic potential energy has a local minimum (LMEE) when the angle takes zero. Finally, we confirm the effectiveness of our elastic model by performing a compression test of the hemispherical soft fingertip.

抄録全体を表示

This paper introduces and describes a new type of wheeled locomotor, a four-steering, four-forked snake-like robot. This wheeled locomotor is a nonholonomic mechanical system, and it consists of four links, three rotational joints and four steering systems. The four links are coupled by the three rotational joints which have the common rotational axis. Each link has a steering system at its middle point. The wheeled locomotor makes undulatory locomotion in which it transforms the rotations of the three joints into its movement by using the four steering systems. Especially, we assume a virtual joint which has identically the same rotational axis as the common one of the three joints. This virtual joint couples the first link and a virtual link which has a virtual axle at its middle point and which has a virtual steering system at its tip. We prove that, by assuming such virtual mechanical elements, it is possible to convert the kinematical equation of the wheeled locomotor into five-chain, single-generator chained form in a mathematical framework, differential geometry. Based on chained form, we derive a path following feedback control method which makes the wheeled locomotor follow a straight line. The validity of the mechanical design of the four-steering, four-forked snake-like robot, the conversion of its kinematical equation into chained form, and the path following feedback control method has been verified by computer simulations.

抄録全体を表示

This paper describes the methods and experiments of rolling an object among the right and the left hands of an industrial robot. Both hands are equipped with tactile sensors, which have functions of acquiring the tactile images and the forces from the sensing elements of it. The flexible handling should be made efficient use of tactile sensors, which use as generation of the reference signals in robot control system. For realizing the flexible handling of an object using the tactile sensings, it is introduced that an object is manipulated by rolling among the right and the left hands of robots. The experiment of rolling an object is carried out by control of dual robot hands based upon two posture parameters and the grasping forces measured from the tactile sensors. The square pillar and the sphere are used as objects.

抄録全体を表示

This paper describes an internal force sensor for a new redundant parallel manipulator. In convensional control methods of a redundant parallel manipulator, optimal torque minimized actuator torque or maximized manipulability by using evaluation function is decided and used. However, these methods have to use a torque controlled actuator. It's torque is small, also it is expensive. So, we proposed a new control method using a conventional geared actuator. In our method, internal forces produced by actuator redundancy was detected by an internal force sensor and controlled to be zero. This force sensor is designed to detect only internal forces loaded the end-effector. We demonstrate about the structure and the principle of the proposed internal force sensor, and experimental result of the internal force sensor when internal and outer forces are loaded it.

抄録全体を表示

Lifted flame would be helped high-intensity combustion system like gas turbine for NO_x reduction and improve the limit of flame's blowing off. While lifted flame has various instabilities, flame control technology is necessary for fame stabilizing. In this paper, a speaker-driven synthetic jet actuator for lifted flame control is proposed, and the active control of the height of lifted flame is performed using this actuator. This type of actuator has the advantage of fitting to existing combustion systems and produces high speed jet. Th performance of the speaker-driven synthetic jet actuator is examined by experiments that reduce the height of lifted flame of a propane diffusion flame. In the active control of the height of lifted flame, the Delayed Feedback Control method considering delay time for a control law is applied. The frequency of synthetic jet is fixed and velocity of jet is changed by the control law. The results show that the synthetic jet can lower the instabilities of lifted flame.

抄録全体を表示

New architectures of manufacturing systems have been proposed aiming at realizing more flexible control structures of manufacturing systems, which can cope with dynamic changes in volume and variety of products, and also with unscheduled disruptions. They are so called as autonomous distributed manufacturing systems, random manufacturing systems, biological manufacturing systems, and holonic manufacturing systems. The objective of the present research is to develop an integrated process planning and scheduling system, which is applicable to the holonic manufacturing systems (HMS). A basic architecture and systematic methods are proposed to determine suitable sequences of machining equipment needed to manufacture the products and suitable production schedules for the machining equipment in the HMS. Procedures are developed to select suitable sequences of machining equipment for individual products, and to determine suitable production schendules of machining equipment based on the process plans of the products.

抄録全体を表示

This research work was conducted to confirm the effectiveness of the checking method specified by ISO 10791-6 and to propose an additional method for identifying the geometric deviations inherent to five-axis machining centers with a universal spindle head. In the simulation, it was assumed that a telescopic ball bar system was used for the measurement of trajectory, which was described by the spherical interpolation movement specified in the clause K6 of the standard. The influence on the trajectories of peculiar ten deviations to five-axis machining centers was investigated. However, two of the ten deviations were only extracted and the other eight deviations have not been extracted, although an observation equation was applied to the identification. Then, an alternative spherical movement based on the clause K6 of the ISO standard was designed. In this method, the ball of the ball bar system of the spindle side was magnetically fixed on a special arm which was mounted on the spindle nose. The observation equation was applied to the measured trajectory, and four deviations were identified. Furthermore, four rests of ten deviations were identified by analyzing the geometrical relations. The exactness of the proposed procedures to identify the deviations inherent to the 5-axis machine was confirmed through the simulations.

抄録全体を表示

The reduction of environmental burdens is required in recent years to mitigate global warming, ozone layer depletion and etc. in manufacturing fields. Hence, prediction system of environmental burden for machining operation has been developed so far. Hence, the evaluation indicator for eco-efficiency of process and operation planning is also proposed with considering the environmental burden, manufacturing time and total number of work piece setup times in this research. Global warming is selected as impact category and the feasibility of the developed system and evaluation indicator for eco-efficiency is demonstrated in this paper.

抄録全体を表示

In order to obtain basic information on the improvement of the surface integrity of the machined surface, the influence of the rake angle of cutting edge and the contact width of flank face on the residual stress of cut surface was examined. The residual stress of the cut surface was measured by the X-ray diffraction method. The results obtained are as follows. The residual stress distribution of cut surface can be divided into three characteristic patterns roughly due to the change in the cutting edge shape. The residual stress of cut surface shifted to the compressive side due to the increase in the negative rake angle and the contact width of flank face. It found that the relative increase of the radial cutting force was strongly involved in the shifting to the compressive side of the residual stress of cut surface and the increase in the depth of residual stress layer.

抄録全体を表示

In connection with the worldwide increase of the environmental consciousness, eco-machining becomes one of the most important subjects in the mechanical production field. Consequently, MQL (Minimal Quantity Lubrication) machining process becomes the practical technology today. However, behavior of the mist particle at the tool-work interface in company with its lubrication and cooling effect in that interface has not been made clear. Indeed, although it is indicated that the mist particles floating in the surrounding are so small that the machining operator can be damaged by the particle, even the density of the mist at the arbitrary point can not be known. In this study, authors tried to develop a simple and small mist density sensing system by means of QCM (Quartz Crystal Microbalance) sensor conventionally used for the smell sensor. The developed system was evaluated by some experiments to check its sensitivity and reliability in the view point of the availability for the practical use. As a result, it was shown that the density of oil mist can be qualitatively obtained by measuring the resonance frequency of the circuit, and that this system is applicable to the actual production fields.

抄録全体を表示

For economical and ecological reasons, great efforts to reduce the use of coolants in cutting processes are being made. Oil film on water droplet cutting-fluid, abbreviating to “OoW”, is one of the ecological methods to supply a minimal amount of lubricant, in which relatively large water particles covered with a thin oil film are sprayed on the machining point. In this paper, to obtain the stable machining performance, firstly, the special nozzle which effectively generates the OoW was developed. Secondly, the relationship between oil film formation on water particle and machining performance were investigated. From the experimental results, it was found that mineral ingredient, especially calcium ion in water, has large influence on oil film formation which is directly related to machining performance. That is, the larger the concentration of calcium ion in water, the smaller the boundary tension between water and oil and, hence, the larger the spreading coefficient of oil over water surface. This knowledge could lead to the method stabilizing cutting performance regardless of water property, in which surface-active agent is preliminarily added to lubricant to reduce boundary tension between water and oil.

抄録全体を表示

The thermal spray processing method can coat the high-melting materials easily and quickly. This research is to establish the thermal spraying process that can increase Anatase Type TiO₂ content in sprayed coatings. TiO₂ photocatalyst film was made by the powder flame spraying method. Anatase type TiO₂ content increase when the Ti powders is supplied with the CO₂ gas and quicken the cooling speed. It is convenient for photocatalyst film that the surface area of sprayed coatings is wide. The photocatalyst effect of sprayed coatings is Acetaldehyde decomposition of 70% for 90 minutes.

抄録全体を表示

The international standard on functional safety, IEC 61508, requires to specify safety integrity levels (SILs), i. e., target failure measures for safety functions of electrical/electronic/programmable electronic safety-related systems (SRSs), taking account of the necessary risk reduction achieved by SRSs. In order to reflect SIL to the risk reduction through designing and operation of the SRS, it is essential that the relationships between a number of systems characteristics involving the SRS and the achieved-risk reduction should be explored. In the present paper, generalized modes of operation are recommended for the proposition that risk reduction ratios and average hazardous event rates should be made use of as target failure measures instead of the conventional ones, i.e., the average probability of failure on demand and dangerous failure rate. Thus, SILs are assigned to SRSs more easily and reasonably.

抄録全体を表示

The vibration/noise of power transmission gears is one of the serious problems for vehicles, e.g. automobiles, and therefore many researches on gear vibration have been reported. Those reports were, however, concluded by the investigation using numerical simulation which needs input data such as gear dimensions and tooth flank modification. Therefore, the characteristics of transmission error of gears are not clarified theoretically. In this report, the general model of tooth mesh of gears is proposed, where quasi-infinite elastic model composed by springs with stiffness peculiar to gears is incorporated. Transmission error of gears is expressed by theoretical equations. This model is true for not only spur and helical gear, but also hypoid gear, bevel gear, and internal gear. This model clarifies that the qualitative characteristics of transmission error of gears are not influenced by the quantity of tooth flank modification, that of stiffness, and torque although the form of tooth flank modification and the distribution of stiffness have effects on them.

抄録全体を表示

The objective of this research is to develop a new lapping process which can efficiently make tooth flanks of hardened steel gears smooth as a mirror. This lapping process is carried out on the trial-made gear lapping machine using a nylon helical gear as a lap. In this paper the lapping process accompanied by vibration of the nylon gear was attempted to improve the tooth roughness and the accuracy of hobbed gears. Micro hardness, micro structure and residual stress on the tooth flank of lapped gears were also examined. As the results, it was found that the vibration of the nylon gear increases the removal rate and reduces more efficiently tooth flank roughness of work gears. And the running noise and the load carrying capacity of lapped gears were investigated. The running noise and the load carrying capacity of lapped gears were improved.

抄録全体を表示

A micro lateral force sensor has been developed. The sensor equipped a traveling table supported by suspensions. The lateral motion of the traveling table was activated by comb actuator. The applied voltage to the comb actuator was controlled to keep the position of the traveling table constant by detecting tunnelling current at a gap between two electrodes that were arranged on the traveling table and the fixed plate, respectively. An AFM (atomic force microscope) was used to apply a lateral force on the traveling table of the sensor. When the probe of a cantilever was pressed against the traveling table and a raster scanning was conducted, the driving voltage of the comb actuator was changed to compensate the friction force between the probe and traveling table. The driving voltage was captured into an external channel of the AFM system and recorded during the scanning. Friction force image of asperity array was obtained from the driving voltage, which was as same as the image obtained from torsion of the cantilever. The force sensitivity of the lateral force sensor was comparable to sensitivity from torsion of the cantilever.

抄録全体を表示

Rotational loosening mechanisms of a bolt were investigated by FEM, under the assumption of a twist at the center of a circular joined structure in which the bolt was set along a certain pitch circle. In this structure, the bolt is loosened by combining the translational and rotational loads. In the case of a large pitch circle in which only loosening rotations occur, the directions of frictional shear forces on the threads were along concentric circles ; however, the instantaneous center was located near the thread surface, and the center was eccentric with the axis of the bolt. If the radius of the pitch circle is set smaller, the instantaneous center moves closer to the center of the bolt, and finally reaches to the same position at the center of the bolt. On the other hand, the directions of frictional shear forces on the threads were calculated theoretically using the inclination and friction on a pressure flank. The results were in good agreement with FE and analysis. By considering these mechanisms, it is estimated that the number of occurrence of loosening in one vibration cycle changes at the border when the diameter value of the pitch circle equals that of the screw threads. If the diameter of the pitch circle becomes smaller than that of the screw threads, the number changes from two to one. With the exception of torsional center-fastened structures, since the pitch circle is very small, loosening of general joined structures will occur twice in one vibration cycle.

抄録全体を表示

By developing various electronic equipments with high performance, the dissipated power of electric chips used in those equipments has been increased. Therefore, it has been important to cool those electronic chips, and a liquid-cooling system has been employed for some electronic equipments. An Electro-Conjugate Fluid (ECF), which is one of functional fluids, has a remarkable property that a jet flow is generated between two electrodes when a high voltage is applied to the electrodes. By the use of this strong jet flow, a pump with simple structure, no noise and no vibration can be developed and a new liquid cooling system by ECF seems to be realized. In this study, to realize the liquid cooling system by ECF, an ECF-pump is proposed, in which four printed circuit boards are layered to make the pump size compact. The proposed pump is fabricated, and experiments are performed to investigate the basic characteristics of the pump. Furthermore, in the liquid cooling system with the proposed pump, experiments to cools a heat source are performed to investigate the possibility of achievement of the liquid cooling system by ECF.

抄録全体を表示

Crack length measurement and crack initiation detection in a fatigue process are extremely important techniques in the researches for the investigation of crack growth characteristics and the fatigue strength evaluation of machine elements. The purpose of this research is to show a simple and high precision method to measure the length of a crack as well as a micro crack using an extremely thin ion sputtered film. A grid pattern ion sputtered film was proposed to measure the crack length for a bending test specimen. Based on the comparisons between the measurement results and that by a microscope, it was clarified that the grid pattern ion sputtered film has a very high measurement precision. This method should be invaluable and practicable for the crack length measurement of insulating materials such as ceramics. Meanwhile, a rectangle ion sputtered film was used on a metal bending specimen, the possibility to apply the film in the crack length measurement of a metal machine element was confirmed by the change of the electric resistance of the film with crack growth.

抄録全体を表示

Axial velocity profile of a steady tube flow was measured using magnetic resonance imaging (MRI). We used aqueous solutions of carboxymethyl cellulose (CMC) containing suspended particles such as glass flake and glass bead at high volume fractions. As a result, a plug-like velocity profile was observed at high shear rate in the tube flow. This velocity profile measured by MRI had a good agreement with that numerically calculated from the viscosity curve of the test fluid. Furthermore the effect of suspended particles on the flow field in the tube flow with abrupt contraction geometry is also examined. We observed a plug flow profile of velocity field for the CMC solution and the bead suspension, but a concave one near the centerline at upstream of the contraction for the concentrated flake suspension. This velocity profile is caused by the shape of the glass flake particle.

抄録全体を表示