[in Japanese]

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This paper presents a new high speed positioning servomechanism in order to machine an article with a noncircular profile. In the non-circular machining by a lathe, the positioning servomechanism of a cutting tool is necessary, and, in order to operate it with high efficiency, this positioning servomechanism must have the enough force to overwhelm cutting resistance and have a good responsiveness. Previously an electrohydraulic servomechanism was applied to the cutting tool positioning mechanism and the high efficient noncircular machining was realized. But there were some problems, such as the maintenance of oil, a noise, and so on in this mechanism. And so a new high speed and high power positioning servomechanism was developed. This new servomechanism is actuated by electromagnetic attractive force in the same as a support mechanism by an active magnetic bearing. Usual mechanical springs were incorporated into the fundamental servomechanism by the electromagnetic attractive force to achieve the high responsiveness on the lower electric power, and the new servomechanism was developed to make the high responsiveness on practical electric power possible.

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This paper describes the structure and motion characteristics of a newly developed electrostatic actuator. The actuator consists of two electrodes with insulating plates which are stacked in a structure of double helicoid. This structure enables the two electrodes in each layer to be positioned in a short distance with keeping large displacement of the actuator. Therefore, the actuator achieves large output power and displacement. Experimental results reveal that the actuator has a fall of output power caused by charge of the insulating plates. However, the fall can be suppressed by driving the actuator with turning the pole of electrodes each time. A molluscan actuator is finally introduced which features flexibility, another structural peculiarity of the developed actuator.

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The “free-pallet” index conveyor system has been developed by the authors. This paper deals with one-axis toothed belt conveyor used as positioning mechanism in the system. A prototype of one-axis conveyor system has been developed to investigate positioning capability. To construct a flexible system which can easily change stroke, duration, velocity, and acceleration for different purposes, the conveyor is driven by a DC servo motor and controlled by a personal computer. Motion control using cam curves is applied to realize high accuracy and high speed conveying. Positioning accuracy, velocity characteristics, and residual vibration of the conveyor are also tested by experiments, and the results show that the developed conveyor system is effective as the positioning mechanism in the free-pallet index conveyor system.

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Recently an industrial multi-link robot is expected to be applied to precision machining. However, the multi-link robot manipulators are highly coupled non-linear systems and their equations of motions are hardly identified. Therefore it has been thought that precision machining using a multi-link robot is impossible. In this paper, a new type of precision machining robot in proposed. This robot consists of a multi-link robot and the machining unit for micro-positioning. The control system of this robot is modelled as the singular perturbed system and is applied to the position control and electric discharge machining (EDM) control.

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This paper describes a software design of an inexpensive automatic image processing system. In order to avoid the use of a threshold operation, center ordinates of strip images of objects are assessed by means of the weighted mean. Further, to decrease an influence of the chip surface roughness (2-3μm) on accuracies of measured values, coefficients of a standard line, utilized to calculate the wear depths, are determined by the moving average method. Thus, the system detects the maximum crater wear depth with ±1μm accuracy and represents a morphology of the chip wear. The processing time of the system is about 2 minutes per wear.

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This paper presents a non-contact system for measuring tooth profiles of a gear. The system has two optical probes for triggering and measuring profiles. When the sampling is performed, the measuring probe moves in radial direction of the test gear. And it detects the surface displacement for each tooth. It took 42 seconds to measure all tooth profiles of the gear. Each of the tooth surface had 60 sampling points. When the rotation speed of the gear was lower than 1.7 s/round, repetition error was about 2.5 μm. And when the rotation speed was higher than this, error became large.

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In the 1st and 2nd reports, a nanometer level positioning accuracy could be obtained on the one-dimensional table unit driven by a lead screw (a sliding screw or a ball screw) with position feedback system. To carry the table (15.7 kg) into the ±10 nm range from the target position, it took a long settling time of one second due to the residual vibration caused by the rapid acceleration of the table. In this report, the effect of the three positioning steps is presented to obtain the nanometer level position accuracy and to reduce the settling time. These three steps are ; (1) Coarse positioning by an Anti Residual Vibration (ARV) system to eliminate the residual vibration, (2) A semi-fine positioning by a Pulse Width Control (PWC) and (3) Fine positioning at the small table-moving range where the nonlinear elastic characteristic of rolling elements appears in the ball screw and table ball guide ways. As a result, the nm positioning accuracy and the shorter settling time of 300-400 ms can be obtained at the same time.

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This paper describes a theory and application of a manifold-based hierarchical non-manifold model. A local restoration function, which restores only the areas concerning with a specified part in the reverse sequence of the operations, is desirable to cope with design changes. It is realized on a manifold-based hierarchical non-manifold model, which is implemented into a computer system with a “dead shell method.” A boundary edge created by a set-operation or filleting, and its adjacent face has a relation to an edge of a dead shell, which is a “lost” or hidden shell created by operations. A “live shell” and “dead shells” comprise a hierarchical non-manifold as a whole. This method has been proved to be useful in practical use.

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By applying the accurate experimental method proposed in the 1st report, the natural frequencies and acoustic mode shapes of a component of pipe structure can be measured. The rest of the structure is modeled with acoustic Finite Element and the Acoustic Building Block Approach (ABBA) can predict the total acoustic characteristics of the pipe structure based on those experimental and analytical data. Further a muffler component with very complex structure, which is very difficult to be modeled analytically, is tested and again ABBA can be successfully apllied to predict the total acoustic characteristics.

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Small sized batch jobs with large product diversification require intelligent machine tools to optimize cutting conditions by adapting operation planning to the machining environments, e.g., the combinations of cutting tool, work material, and machine tool. In this paper, autonomous operation planning, which optimizes machining operations for each machine tool using adaptive prediction of machining processes, is proposed. In adaptive prediction, the machining processes are predicted and optimized more accurately with adapting parameters of governing equations used for analytical prediction, and/or parameters of neural networks through learning of machining results. Adaptive prediction enables us to predict dimensional accuracy with machining point, and to predict surface roughness with machining time. In an operation planning considering tool wear and surface roughness, machining operation is optimized to minimize machining cost by flank wear predicted with analytical approach based on metal cutting theory and by surface roughness predicted with neural network.

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A diamond core drill has been well carried out in the ceramics drilling. In this investigation, a vertical type machining center (MC) was used in the coring of alumina ceramics with a metal bonded diamond core drill. To clarify the mechanism of coring, the influences of coring conditions on the coring force, grinding ratio, successive zone of coring were studied. At the wheel infeed speed of 5.2 mm/min, and the wheel revolution of 3 000 rpm, the best grinding ratio was obtained. But, from a viewpoint of coring speed, the wheel infeed speed at 37 mm/min was best, in the coring depth was small.

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Nowadays the machine tools have become multi-functional with the development in their speed and accuracy, for example, machining center can be used for grinding. Meanwhile, the deviation-detecting type on-the-machine measuring method has been developed for measuring the machined error of a workpiece on the machine efficiently and precisely. Therefore, it is possible to do roughing, measuring and finishing on a machine without replacing the workpiece. An amended machining system has been studied, in which the machining error of rough grinding is measured by on-the-machine measuring and then dimensional and profile errors are amended by changing the program of finish grinding.

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The analytical method for prediction the mechanical state of the machined surface with FEM was proposed. The flow type chip formation process at low velocity was simulated. As flow type chip formation process is one of the large deformation problems, geometrical nonlinearity and relaxation of over constraint of incompressibility were introduced into the finite formation. A special geometrical separation method of work material at the front of tool edge was also proposed instead of fracture stress criterion and the availability of the method was discussed. Through the simulation, the residual stress and strain distributions within the machined sublayer were analytically calculated. The distortion of work after released from chucking system, caused by rearrangement of residual stress distribution, was also obtained. These analytical results were compared and discussed with the experimental one.

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A three-dimensional chip formation mechanism in oblique cutting is analyzed by applying the rigid-plastic FEM (Finite Element Method). By developing a three-dimensional model of the work material, the plastic deformation field in oblique cutting is continuously analyzed for the transition process from the beginning of the cutting until the steady state. Three-dimensional transition process of the chip formation for a carbon steel (S 45 C) are simulated. In the simulation, the chip flows considerably inclining along the tool rake face due to the inclination angle. The transition behavior of three components of cutting force and variations in the cutting forces in association with tool inclination angle are also simulated. The simulation results are compared with in-situ scanning electron microscope observation of cutting experiments in terms of chip geometry and cutting forces, and good correlations between them are found.

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When the values of coordinates and gradients at some points on a work tooth profile are given, a rack and a hob tooth profile corresponding to the work can be usually get analytically. However, it may be possible that the rack or the hob tooth profile cannot be get because the conditional equation has no root. This is the first interference problem. It may be also possible that the rack or the hob tooth profile makes a loop and intersects itself. This is the second interference problem. In this report, these interferences are discussed and the method to find out the interference is proposed.

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In order to generate an aspherical surface most precisely, computer controlled polishing using a small rotating polisher is one of the most suitable methods. In this study, a new type of polishing head was developed and its aspherical surface polishing properties were tested. The characteristics of this polishing head are as follows : (1) A soft spherical polyurethane polisher was used as the polishing tool, and its rotating axis was controlled to be always at 45 degrees from the tangent line of the machining point on the workpiece surface. Therefore the profile of the polishing trace was more uniform and was suitable for precisely generating the required aspherical surface. (2) The polishing load was applied from the normal direction of the machining point and was controlled to be constant. In tests, spherical BK7 glass was polished to an aspherical shape. A form accuracy of 0.1 μm P-V (±0.05 μm) and surface roughness of less than 0.01 μm Rmax were obtained.

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Burr in drilling operations has been a serious problem especially in the area of factory automation and high technology. In order to prevent burr in drilling operations ultrasonic or low frequency vibration has been applied in the direction of drill feed. In this study in order to enhance the effect of oscillation in drilling operations newly developed “radial peripheral lip drill” has been applied as well as the standard type of drill. With the radial peripheral lip drill the radial lip at the corner of drill edge is able to obliquely cut and sharply slice the stock at the hole exit, which would become burr, by the aid of oscillatory motions in the direction of drill feed. Low frequency vibration is as highly effective in preventing burr as ultrasonic vibration except that the former is effective only with the radial peripheral lip drill.

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