Because sliding leadscrews used in precision positioning systems are driven by motors directly with higher speed, it becomes necessary to evaluate more accurately their friction losses to estimate the required motor power or heat generation. It has been proved experimentally that the interface between the screw shaft and the nut achieves hydrodynamic condition under higher rotational speed. But the method of calculating the friction has not been established. This study aims at proposing a theoretical formula describing the frictional characteristics of sliding leadscrews under hydrodynamic condition and verify it experimentally. In this report, lead errors of a screw shaft and a nut are measured accurately and discussed to formulate a clearance shape model with respect to the drunkenness error of nut. The infinitely short bearing theory is applied to the shape model so as to derive some dimensionless numbers.

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The theory proposed in the previous report is verified experimentally. The proposed theory is based on the clearance shape model with respect to the drunkenness error of the female thread, and the frictional characteristics of sliding leadscrew are described under hydro dynamic condition by some dimensionless numbers derived from infinitely short bearing theory. To verify the proposed theory, some experiments are performed on several specimens which have different nominal designations. The experimental results are arranged by dimensionless S number and M number, and they are compared to the theoretical results. The experimental results agree with the theoretical results in the range of hydro dynamic condition, so that the propriety of the proposed theory is verified. The proper driving condition is considered based on the theory and the experimental results, and the selection criterion for the proper oil viscosity is shown.

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The purpose of this paper is to improve the accuracy of free height of helical compression springs. A pair of feed rollers generate torsion of wire at feeding of wire. Torsion of wire makes the accuracy of free height of helical compression springs lower at the continuous production. And then, the mechanism that a pair of feed rollers getaerate torsion of wire is analyzed with a geometric approach in order to estimate torsional angle of wire. Moreover, the relationship between torsional angle of wire generated by a pair of feed rollers and free height of helical compression springs is analyzed with a geometric approach. And it is shown experimentally that these analyses are available. As the results of the analysis and the experiments, it is important that the upper roller and the lower one should be set on the position not to generate torsion of wire. Namely, the effect of torsion of wire generated by a pair of feed rollers can be removed on the accuracy of free height of helical compression springs.

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This paper presents analytical study of gear mesh exciting force that causes the vibrations of the helical gear systems and resulting gear noise. In equation of one degree of freedom for rotational vibration, displacement and tooth stiffness are separated into mean and fluctuating components. As the result, mesh exciting force is shown to be a composite of exciting force due to tooth stiffness variation and that due to tooth surface error. Then a simplified method to calculate mesh exciting force is proposed. This method uses tooth stiffness of error free gear in order to eliminate computational effortS. For validation, gears with modified tooth surface are run in the gearbox. The calculated mesh exciting force shows good correlation with the measured acceleration of the gearbox housing, and also shows good correlation with the mesh exciting force identified by shaking test.

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The structure born noise must be studied in order to reduce gear noise in helical gear system. For this purpose some analytical method is required to predict vibration level of the system including gears, shafts and gearbox at the design stage of the system. This paper shows equations of forced vibration in multi degree of freedom system and a way of thinking how to apply general method in vibration analysis. First, a stiffness matrix of gear tooth, which takes account of the static coupling through gear tooth flank, is derived. And then, a set of differential equations, which are parametric excitation type, is established by using this stiffness matrix. By separating tooth stiffness and displacements into mean and fluctuating components, it is shown that these equations can be approximated by non-parametric equations. The approximation accuracy is good for the practical use.

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This paper presents study of the three dimensional bending and shearing deflection for external and internal helical gears. The deflection due to a concentrated load operated at the arbitrary position on the tooth flank is calculated by the three dimensional finite element analysis. Based upon this numerical solution, the approximate influence function that is applicable to arbitrary gear tooth dimension is derived. in order to apply this equation to non-standard designed gears such as addendum shifted gears, concept of equivalent tooth form is introduced. It is confirmed that the tooth deflections by the approximate function satisfactorily agree to that by FEM.

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A thin rim cycloidal gear in contact with pin-type internal gear teeth in a K-H-V-type planetary gear arrangement was chosen as the subject of study. The tooth loads of the thin rim cycloidal gears with gear errors were discussed theoretically using both the gear model composed of two beams and the flexibility influence coefficients. Furthermore, the tooth loads of the cycloidal gear were analyzed using the finite element method in order to assure the theoretical results obtained using the gear model. Consequently the relationships among the face width b, the amount of gear error E, the eccentricity r_e used to show the gear dimension, the applied torque T_o and the tooth load P_k were determined as follows. Each of P_k/(bE) and P_kr_e/T_o can be expressed as a function of bEr_e/T_o.

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A single flank gear-testing machine with two rotary encoders is developed and high precision measurement of transmission errors of gears under load is achieved. The developed measurement system has enough accuracy to investigate transmission errors of helical gears. Besides, two methods of wave removal are proposed and the influence of the accuracy of encoders on the transmission errors is investigated. It is found that the moving average method is effective to remove wariness including pitch errors. Measurement accuracy depends on the number of silts, that is to say the silt pitches, of the encoders by estimating the maximum quantization error. Moreover, absolute transmission errors of spur and helical gears are measured and amplitude changes of transmission errors on the applied load are discussed.

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The high performance of the hourglass worm gearing is well known among all types of worm gearings, especially after the developement of HEDCON^【○!R】 worm gear reducer. Despite its high performance, the difficulty in manufacturing the hob is one of the obstacles of production and it has been one of the themes of study. Worm wheel grinding means not only teeth surface grinding but also teeth generating using the electro deposited diamond wheel which shapes the worm thread. This type of grinding wheel has the possibility of being an easy method for producing the worm wheel.

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Flexible couplings are used to connect the ends of drive and driven shafts subject to one or more kinds of misalignment and reduce the effect of lateral load and bending moment that could transferred between the shafts. Flexible couplings are generally classified into two basic types of couplings: power couplings and servo couplings. Power couplings are designed to transmit torque while often behaving as a shock absorber to smooth fluctuations in load and vibrations. Servo couplings, on the other hand, are designed to respond instantly to rotation of the drive shaft and maintain uniformity of angular velocity and displacement between the drive and driven shafts. The present paper is concerned with transmission errors occurred between drive and driven shafts connected by a flexible coupling in servo system. Conclusions drawn from the present research are summarized in the following. (1) Transmission error of helical beam couplings decreases as its torsional rigidity increases. (2) Transmission errors occurred in helical beam, diaphragm and bellows couplings are approximately proportional to the magnitude of the lateral and angular misalignments. (3) Diaphragm couplings have the most excellent transmission accuracy against the lateral misalignment.

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Rotary bending is able to bend sheets with various bending radii and angles by controlling forming conditions. The effects of applied radial force and rotary angle on bending radius and angle are clarified to realize and a precise rotary bending system. The bending radius is determined by applied force and bending angle is determined by applied radial pressure and rotary angle. The feedback bending system for rotary bending is developed in that the bending conditions are determined by the previous measured value of bend sheets.

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In super-finishing by cubic boron nitride (CBN) stones, it is considered that chips are formed by crossing of grain locus. Thus, crossing angles of grain loci are paid attention to as a important parameter. In this paper, the new method is proposed using average crossing angle of grain loci. On the other hands, chip formation process is classified two types. Therefore, all crossing angles are calculated considering these types of crossing of grain loci. Average crossing angle is defined as the mean value of those. Moreover, the relation between these average crossing angle and cutting performance is investigated in various calculations and experiments. As results, average crossing angle is one of most important parameters to predict the cutting performance on super-finishing using CBN stones.

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This paper elucidates the size effect of ID-blade on its lateral compliance at the inside edge. The obtained results are summarized as follows. (1) The deflection surface of ID-blade by a single-point lateral load acting at the inside edge has a large slope around the loading point especially in the radial direction. (2) The deflection of the larger-sized ID-blade by a single point unit load usually extends wider in the angle having its vertex at the center of ID blade. (3) The compliance of ID blade decreases exponentially with an increase of the tangential stress at the inside edge σ_Iaθ. (4) While the larger-sized ID-blade has the larger compliance, the difference becomes small with an increase of the stress σ_Iaθ. (5) Under the condition that the outside diameter of ID blade is constant, the compliance of ID-blade increases with an increase of the inside diameter. (6) When there being enough difference in size between the inside and outside diameters of ID blade, the effect of the outside diameter on the compliance is small. (7) The compliance of ID-blade is almost inversely proportional to the thickness of D-blade. (8) The compliance of ID-blade increases with a decrease of the radial width of the electroplated diamond layer.

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The results of basic experimental study on cryogenic machining of hard and brittle materials are presented in this paper. In order to understand the basic phenomenon of material deformation and fractue during machining the hard and brittle materials such as a glass and a semiconductor at low temperature, the indentation tests and single point diamond scratching tests have been carried out. The results of tests showed that the crack length and the indentation depth decreases, the hardness and the critical depth of brittle ductile transition increases with the decrease of material temperature for both soda lime glass and single crystal silicon. The optical microscope observations showed that the deformation behavior and cracking patterns at low temperature are different from those at room temperature. From our experiments, we can conclude that the cryogenic machining is advantageous to restrain generation and propagation of cracks during machining the hard and brittle materials.

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FMS, which consists of machining centers (MC) and an automatic transportation system (AGV), is used in many part manufacturing factories to produce various parts with small and changeable lot sizes efficiently. In introducing FMS, it is important to design the optimum system and consider the optimum operation policy in order to yield the maximum production rate. In this paper, we study a job transportation policy in a basic loop type FMS. First, we analyze the optimum job transportation policy which yields the maximum production rate using a Markov decision process. Next, we analyze system parameters (position of MC, MC number, buffer capacity and AGV transportation speed) on the maximum production rate using an imbedded Markov model.

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This paper presents a proposal to improve productivity and provide a more reasonable work area. The method of research is to observe and measure the motion characteristics of a typical sitting worker doing "get and place." The valuation index used in the experiment is obtained by measuring the length of the arms, the motion locus, the motion velocity, the motion time, and the amount of myoelectric discharge. The results lead to an experimental formula expressing the relation between the motion time and the length of the arms. This paper also showed that a work area, which takes into consideration the difference of a physique of the worker, could minimize the scattering of motion time by the worker resulting in a more efficient and reasonable work place.

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Today we live in a highly technological and information-oriented society. Information access, including the Internet, has made noticeable developments and grown on a worldwide level. In such a social background, it is a widely known fact that major changes from the use of manpower dependence type work to VDT work is taking place in major businesses today. This paper describes some design factors for a reasonable working environment which supports a combination of man-machine for VDT work. The method of research notes "fragrance" as one factor to be explored when designing a working environment and considers the influence which this character has on productivity and workload from an experimental approach. The valuation index used in the experiment is obtained by measuring working efficiency and working quality in data input work, mental changes (stability)-recorded by an EEG (electroencephalograph) measurement, and workload degree determined by a survey of subjective symptoms. The results lead to a suitable fragrance sorts on working environment in the VDT work.

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