[in Japanese]

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This paper describes design strategies and experimental results of the clean room robot which has airborne particle emission levels well within Class 1. Recently, there has been an increasing demand for clean room robots in the fields of semiconductor manufacturing, biotechnology, medical supplies, and so on. And a lot of SCARA type or Cartesian coordinates type clean room robots are developed for practical robots. These conventional robots perform a linear motion by a prismatic joint ; they have a defect in the structure for high degrees of cleanliness. Therefore, these robots utilize a linear-motion-cover such as a bellows and negative pressure by vacuum suction within the arm. To solve this problem, the proposed robot has a four axes pseudo-SCARA configuration with four revolute joints using a parallelogram arm mechanism ; cleanliness Class 1 is achieved by utilization magnetic fluid seals for all revolute joints without vacuum suction. Furthermore, a 32 bit high performance controller is used for reducing the effective current of the motors and a finite element method is used for reducing the moment of inertia while keeping the stiffness of the arm high. As a result, maximum speed 6 m/s and cycle time 0.98 second are achieved.

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It was reported in the previous paper that the dynamic cutting state with variable undeformed chip thickness could be predicted by using the data of orthogonal, steady cutting and the slip line solution proposed. Inasmach as the predicting method, however, is unable to apply to general materials cut which do not conform with the Lee-Shaffer's shear angle equation, the method is improved in the present paper by replacing the slip line field with an upper bound model with velocity discontinuity and developing an energy method to determine the model. Dynamic cutting tests including wave generation, wave removal and wave combined proved the cutting forces and chip formation predicted are in good agreement with the experimental results in a variety of materials cut.

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Complete tool collision checking and high speed machining will reduce polishing process of die-making. This paper describes a new method of numerical controller to realize such machining of sculptured surfaces. The two key technologies are proposed. One is tool projecting and dividing method, which decides tool positions by projecting the tool to the objective surfaces, and divides the projected area of the surfaces into a mesh and putting down the tool on the mesh at the given XY coordinates. The mesh is constructed of two-dimensional ring buffer in order to represest the tool motion. The other is application of parallel processing to machining of sculptured surfaces. Possibility of the realtime interpolation is discussed from the result of development of 32 bit multi-processor. As the results this paper concludes that the proposed method will be able to realize realtime machining with tool collision checking by parallel processing of the newest microprocessors.

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This paper describes a thermal deformation compensation of machine tools by piezo-electric element. We made the machine model in which the piezo-electric element is joined in the machine construction parts, in order to compensate the influence on cutting accuracy, which is caused by the thermal deformation of machine tools. By measuring the surface temperature at specific place of the machine model, the difference of temperature gradient is obtained ; the relative displacement is predicted in cutting area ; the compensation system of thermal deformation is constructed by loading the proper voltage on the piezo-electric element. Those are proved by the experiment. As the result, by measuring the surface temperature at two specific places of the machine model, experimental equation to predict relative displacement can be yielded, where is used by compensation coefficient decided by the machine shape and the material characteristics. On the other hand, by giving the pre-load to piezo-electric element for added actuator, the hysteresis ignores because the voltage is loaded only in compensating. By predicting the relative displacement in cutting area by this experimental equation, it is shown to be able to compensate the thermal deformation.

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This paper describes a fundamental concept of friction from atomistic aspect and the calculation of frictional force based on the proposed concept in an elastic contact condition. Assuming that interatomic bonds arise at the interface between the solid surfaces in elastic contact, friction is understood by the behavior of the interfacial atoms. The chemical bonds also arise at the interface between two solid surfaces in contact, and the exchange of bonds is induced at the time of relative displacements. Therefore, the frictional energy is a released interatomic strain energy at the time of exchange of bonds. Thus the frictional energy and force of fcc metals can be calculated based on the proposed concept in an elastic contact condition. The results of calculation may be summarized as follows. Assuming that the contact area is constant, the frictional force is not influenced by contact pressure in an elastic contact condition. Assuming also that interatomic potential is Morse potential, frictional force is dependent on the lattice orientation, but independent on sliding direction. In the case of fcc metals, the values of frictional force is strongly correlated with those of critical shear stress.

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Measurement of temporal deformation on an asperity model of surface roughness subjected to pressure by flat punch is performed and the deformation behavior is discussed. The method is based on the minute and continuous observation of the deformation of the asperity by multiple aperture holographic interferometry, which repeats of holographic double exposures through small apertures of a mask placed in front of single holographic plate. Industrial aluminum is selected as the material of thespecimens. The shape of the asperity is cone type and the asperity angle is 120°, 154°and 171°.

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The spring rate of hydroformed bellows were generally calculated by shell theory solution or energy solution. In both cases, the calculation model of the bellows will be simplified and the thickness of the bellows convolutions will be assumed as a uniform thickness plate. And the calculation solutions were often different from the experimental spring rates. Since the sectional thickness of hydroformed bellows is different at outer side of bellows or inner side of bellows, a finite element method was applied to get the spring rate of the bellows in this paper. The calculated spring rates were almost same as those of experimental data. The calculated spring rates indicate the ratio of OD thickness and ID thickness is very delicate to the spring rate values. Therefore, this paper proposes that the finite element method will be effective to estimate the accurate spring rate of bellows, because the ratio of OD thickness and ID thickness can be reflected in the calculation easily.

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This paper deals with a method of generation of parametric cubic spline surface representing free-form surface defined by contour curves. The method comprises four steps. The first step makes spline curves approximating contour curves. The second step sets the target value of partial second derivatives of the spline surface to be generated at all knot or mesh points, interpolating the shape of contour curves. At the third step, the characteristic vectors at the knot points are so decided that the difference of the actual partial second derivatives and their targets is minimized. The last step computes the final shape of the surface, utilizing twist vectors at the corner points whose obtaining method is also described. Examples show the accuracy of generation.

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This paper presents an automatic shape modification method using surface constraints on CSG (constructive solid geometry). In this method, surface constraints are classified into two categories : explicit constraints which belong to spatial relations between CSG primitives and implicit constraints which belong to individual geometric characteristics of each primitive class. The geometric database is composed of two kinds of trees, i. e. a CSG tree and a set of trees representing the explicit surface constraints. The CSG tree and the constraint trees are linked to each other. The shape modification is performed automatically by tracing the trees. A prototyping has proved the algorithm is easy to handle and efficient to execute.

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This paper presents a vibration analysis method of a parallel linkage robot by treating vibration components separately, one from the motion of the linkage mechanism and the other from the linkage driving systems. The main results obtained are as follows : (1) In the parallel linkage mechanism, which has two degrees of freedom, coupled vibration occurs in both linkages and the natural frequency of the linkage mechanism varies with the coefficient of dynamic coupling. (2) The vibration of the end effector, which occurs during the motion of the parallel linkage robot, consists of two types of vibration. One type of vibration occurs when the linkages are accelerated or decelerated, and the other type occurs when the link driving forces induce vibration due to disturbances in the linkage driving systems. (3) It is possible to examine both the transient and the forced vibrations using this vibration analysis method.

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The forming sequence design is automated by a rule-based system with a rucursive function call as an algorithmic framework. Products with cylindrical elements are assumed. A suitable range of an initial billet diameter is determined. A total of 23 forming operations are defined. Only qualitative constraints of the forming operations are represented by rules which recursively generate qualitatively feasible intermediate products through a conflict resolusion strategy. The qualitative constraints are analyzed into 12 basic conditions. Left-hand sides of the rules are represented accordingly. Each of the qualitatively feasible intermediate products is checked, immediately after its generation, by quantitative constraints of the relevant operation. The management and validation of knowledge are facilitated by this separation of the constraints. Forming sequences generated are consistent with those obtained by the expert.

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The tooth profile which is insensitive to the center distance error, without sacrificing the advantages of the W-N gears, is developed. The authors clarified that the relationship between the change in the center distance and the operating pressure angle differs depending on the rate of change of the radius curvature of the tooth profile, and studied and indicated the tooth profile whose radius curvature is suitable for the W-N type gears. Then a formula to calculate the gap between the tooth surfaces of gears which are meshing was derived, and investigated how the gap between the tooth surfaces differs according to the different tooth profile. It is very important to take into account the affects of the expansion of the contact area caused by an elastic deformation on each tooth surface when a force is applied to the surfaces in mesh. Also a study was made to determine the tooth profile which is most ideal and suitable for the W-N gear.

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Under theoretical considerations on measurement of microdifferential pressure the pressure gage suitable for measuring small pressure variation with good accuracy has been developed. The gage is composed of two pressure chambers separated by a phosphor bronze membrane and differential transformer to detect electrically membrane deflection produced by differential pressure variations. The each chamber has large volumetric capacity enough to eliminate bubble effect generated in the chamber. The obtained sensitivity of the gage is about 0.499 V/mmH₂O/V for pressure range of from 0 to 1 mmH₂O, which enables us to measure even slight pressure change produced by liquid flowing through duct with good accuracy.

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The tightening of bolted joints is of vital importance to many engineers in the mechnical industry. The impact-wrenching is known as one of the most practical methods for the tightening of bolted joints, but few studies about the hammering impact have been made. This study investigated the percussive point of the spanner which gives an impact to tighten bolted joints to obtain the effective tightening force. Author found the precise formula to obtain the effective tightening force which acts on the bolted joints by impacts. The formula is r = K√M_s/M_h, where r is the distance between the percussive point and the rotatory axis of the spanner, K is the radius of gyration, M_h is the mass of the hammer, and M_s is the mass of the spanner. The experimental results agree well with the theoretical values.

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Generating mechanism of the stick motion, which occurs on the motion error during circular interpolation motion for NC machine tools, has been studied The motion errors including the stick motion were measured by Double Ball Bar test. Then simultaneously feedback values of the servo motor, the encoder, the linear scale were measured to compare the relationships between them, and the stick motion is generated due to the time lag at servo motor reversing, where lost motion is due to the elastic deformation of ball-screw driving system. A feed-forward control method was developed to compensate the stick motion error.

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A new type of holographic interferometer, called hologram interferometer, for testing and measuring optical surface configuration is proposed. The interferometer mainly consists of a laser source, a microscope objective and a collimating lens to get a collimated beam, a hologram which serves both as an objective lens and a half mirror in a Twyman-Green type interferometer and a flat reference surface mirror. The optical inhomogeneity of hologram glass substrate is automatically compensated. Experimentally measured cofiguration error of a commercial spherical mirror whose diameter was 35 mm and radius of curvature was 200 mm were λ/10 in peak to valley and λ/50 in rms where λ was 0.632 8 μm. These values were the same as those obtained by using a commercial Fizeau type interferometer.

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The Cycloid Ball Reducer is a newly developed element for servo mechanisms. In the previous report, the construction and the principle of the mechanism were mentioned. In this report several factors to affect the design of the mechanism are analyzed ; such as, radius of curvature, pressure angle. By the analysis it was known that there is an optimal value of trochoid factor which affects on radius of curvature and pressure angle.

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