[in Japanese]

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[in Japanese]

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The purpose of this paper is to describe a simple non-contact displacement sensor by means of optical method. Scattered light from rough work surface is separated into two light spots by passing through two apertures. The spots are detected with two photo-electric devices shifted by its radius of detecting area to the aperture axis. Intensity ratio, ρ=(I_b- I_a) (I_b+I_a), is proportional to the displacement of work surface. The displacement sensor with this principle has been developed. The sensor is 70 mm in height and 54 mm in diameter. The sensor consists of two photodiodes, two quartz glass bars, one LED as a light sorce and one condensing lens. It is effective for many kinds of work materials having the surface roughness of more than 1 μm R_z, The sensor measures 8 mm of range and the resolution for 5 mm range is approximately 2 μm with ±2 μm repeatability. The sensor also measures the tilted work surface displacement up to 6 degree from the optical axis.

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Cylindrical traverse grinding is often used for grinding slender workpieces with high accuracy. However, vibrations such as self-excited chatter frequently occur because of the low rigidity of the workpiece, and restrict finishing accuracy, productivity and wheel life. This paper presents a newly developed active rest for precision cylindrical traverse grinding. The vibration of the workpiece can be reduced by applying an additive viscous damping force from an electromagnetic rest without any contact between the rest and the workpiece. The active rest also controls the static deformation of the workpiece so as to realize a constant wheel depth of cut along the workpiece axis. First, the construction and mechanism of the active rest is presented, and its control is theoretically discussed. Then the effects on the suppression of vibrations are experimentally verified.

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Dependence of initial permeability of Mn-Zn ferrite single crystals on crystallographic orientation was studied theoretically and experimentally. The crystallographic anisotropy of initial permeability of Mn-Zn ferrite single crystals has been believed because of the previous experimental results and magnetocrystalline anisotropy. The permeability of the single crystal was theoretically derived by the use of the magnetocrystalline anisotropy energy on both mechanisms of the domain wall displacement and rotation magnetization, respectively. When the magnetic domain structure in the crystal is formed so that the spontaneous magnetization directs each easy direction at random, it is proved theoretically that there is no crystallograhic dependence of the initial permeability of Mn-Zn ferrite single crystals without stress. This independence was proved by measuring the permeability of Mn-Zn ferrite single crystal specimens having little composition segregation without stress. The permeability spectra and permeability-temperature relation of the crystal specimens was also measured. The crystallographic dependence which has been shown can be considered to be due to the composition segregation and residual stresses of the tested materials.

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A low power CO₂ laser was used to perform localized etching on Si₃N₄ coated with an aqueous KOH solution, and the etching characteristics were investigated. The laser power density is less then 10 kW/cm², and Si₃N₄ cannot be etched only by laser irradiation. However, coating with an aqueous KOH solution, the surface can be etched by laser irradiation. The etching process is not accompanied by melting but by oxidation. The etching rate depends on the laser power density and the concentration of the KOH solution. The etched area is restricted to the laser irradiated area. The etched hole diameter depends on the laser power density, and it is possible to form an etched hole whose diameter is less than the one of the laser beam.

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The cutting-off ability of diamond abrasive wire is experimentally studied. The wire has one layer of diamond abrasives around the core steel, so the cutting-off ability of the wire is continuously decreased due to falling off and wear of abrasive grains, and no recovering of the initial cutting-off ability is reached. It may be generally said that simple cutting-off ability of the wire is low compared with that of cutting wheel. But the wire can even cut off ceramics well while most abrasive grains keep sharp edges. And it is experimentally confirmed that ; machining without coolant shows much lower cutting ability than that with coolant ; ratio of tangential force to normal force is decided by material of workpiece and wear of abrasive wire, while it is slightly depended on wire running speed ; wire tension and normal force. The ratio evidently affected with material ductility, for example 0.5 for alumina-ceramic, 0.54-0.55 for glass, 0.68-0.74 for brass and 0.8-0.87 for aluminum without apparent wire wear. The machining characteristics of diamond abrasive wire are simply represented by the ratios of cutting-off area to unit grinding forces and unit wire running length.

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Several experiments were run to study the influences of work size on the residual stress induced by shot peening. Shot peening was performed for steel (0.45%C) and influences were discussed on the surface residual stress, arc height and half width. The results are as follows : (1) Residual stress on the peened surface shows the size effect for the work thickness, and the critical thickness is 5 times to the depth of work hardened layer produced by shot peening for annealed steel. (2) The size of specimen does not affect on the surface residual stress for the square form. (3) The surface residual stress shows anisotropy for the rectangular specimen and the value on the longitudinal is lower than that on the latitudinal. (4) The more the kinetic energy of a shot, the more the anisotropy. (5) The maximum difference from anisotropy of surface residual stress was 77% and 88 MPa in this experiment.

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In cylindrical traverse grinding, static and dynamic characteristics of grinding operating system change with longitudinal grinding position. And regenerative effect in grinding process is complicated, too. For the above reasons, chatter vibration in cylindrical traverse grinding is influenced in complexity. In this research, a development of chatter vibration in traverse grinding has been investigated experimentally and theoretically. Introducting the extended regenerative theory, this phenomenon is discussed in the range of transient with the characteristics roots of grinding system. It was found that the theoretical results were similar to the experimental results, which chatter phenomenon differed with each traverse grinding position.

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As vitrified bonded grinding wheels have the advantage of high porosity and high rigidity, vitrified bonded diamond wheel has been said to be useful for ceramic material grinding. However resin bonded diamond wheels have been mainly used in this field. It may be chiefly due to the poor thermal stability of diamond in comparison with other abrasives. This paper proposes a making method of vitrified bonded diamond grinding wheel and experimentally deals with influences of producing conditions on the mechanical properties and the structures. In this study borosilicate glass which has relatively low thermal expansion coefficient and low softening temperature is selected as a bonding material. White fused alumina grains are used as diamond concentration controller. Using zirconia grains instead of diamonds, producing test is also carried out. Results obtained are as follows : (1) In order to get optimum producting conditions of diamond wheel it is not always correct to use other grains instead of diamond grains. (2) Hydrogen is suitable as firing atmosphere. (3) On cold press process 3 type structures are obtained and the structures mainly depend on bond content and firing temperature. (4) On hot press process 2 type structures are obtained depend on bond content.

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This paper describes the development of an automatic polishing machine for a free form surface with the help of a robot. The robot is installed with a magnetically pressed polishing tool which has been newly developed. This tool utilizes the magnetic field created by a small magnet within the hollow space of a ferromagnetic grinding wheel to apply holding pressure over the surface to be polished. Therefore, the need for high stiffness arm structure to exert polishing pressure is eliminated. Besides this, the robot provides easy control, because the tool possesses considerable flexibility that enables the grinding wheel to follow the curved surface independent of the robot arm whose vibration or positioning error does influence the movement path of the abrasive wheel. The cup shaped grinding wheel has three humps on the abrasive end to provide contact at three points on the free form surface, and hence, the wheel rotates smoothly around the axis and generates a polished surface required. In this paper the characteristics of the tool are investigated, and the robot control method to get a smooth surface is discussed.

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The knowledge of the hobbing forces is very useful to the design of hobbing machines, the analysis of vibrations and the decision of optimum cutting conditions for the improvement of the accuracy of hobbed gears, etc. This paper shows the measuring system of the three components of the hobbing force. In this paper, specially shaped workpieces having the width of one pitch tooth space are used in order to investigate the hobbing force of each hob tooth in detail. From the forces measured on the workpiece, the tangential, radial and thrust components on each tooth of the hob and workpiece can be obtained. As a result, the magnitude and nature of the three components of hobbing forces in various hobbing processes are clarified.

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The purpose of this study is to make clear how to occur the involute tooth profile errors in finish roll forming process. There are two type errors after rolling profiles. One is the concave on the generating pitch circle and the other is pressure angle error on the driven side. It is considered that the concave error caused on varying the number of contact teeth on the line of action of driven and follower side. In the roll forming process it is observed that each pair of teeth would have contact earlier than the ideal kinematic beginning of contact, and have also contact later than the kinematic end. In practice the actual length of line of contact becomes more longer than the ideal kinematic length. A model of the actual contact under the applied die loading force are derived, and the calculated profiles are in good agreement with the after rolling profiles.

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This paper describes a newly developed lathe for machining numerious non-circular profile article with high accuracy and high efficiency. In general, the machining of non-circular profile articles, such as camshafts and rotary engines, has conventionally been carried out by means of a copying lathe. This method sets upper bounds to machining speed owing to mechanical factors. In order to machine a non-circular profile object by a lathe with high efficiency, a lathe has been developed whose the cutting tool is positioned in-phase with the rotation of the spindle by the use of an electro-hydraulic servo-mechanism controlled numerically. When the speed of the spindle is increased to improve machining efficiency, the positioning of the cutting tool tends to become out of phase with the rotation owing to the delay caused in the servo-system. The inverse transfer function compensation, which is a kind of feed-forward control, has been applied to the system in order to overcome the problem of the delay. And application of this compensation has enabled improvement in positioning accuracy of ±0.5 mm to ±0.1 mm at a spindle rotation of 180 rpm. This result and some examples of the products machined by the developed lathe are shown in the paper.

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This paper deals with the development of the integrated manufacturing system by input of the drawing of a turning part into personal computer which produces its NC program automatically and transfers it to the NC lathe. This system is called DREAMS which stands for “drawing recognizable automatic manufacturing system”. The integrated CAD/CAM without any human assistance is proved to be possible even for turning parts. Also new recognition method is proposed.

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The design process is highly sophisticated because the design mechanism is still unclear. In order to realize a CAD system, a design model and its operation must be established. A boundary factor model (BFM) has been developed to describe the design model. However, a strategy to manage the BFM is still insufficient for establishment of a practical CAD system. This is because the control process in the BFM are not well-formulated. This paper reports on a way to control the BFM. Firstly, the BFM is reformulated into a Petri net. The reformulation shows that the BFM can be regarded as an event-driven system. Design control equations for the BFM are introduced from this reformulation. The control equations provide the BFM with algorithm for design analysis and design control. An atempt to a design experiment for development of an advanced CAD system gives quite a few of directions to a design automation.

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Investigation is performed on basic concepts of online-measurement control system. Molding experiment including online-measurement and computer simulation on forecasting and controlling system in a plastic molding process are carried out. Online-measurement control system in this process is discussed. Simulation shows possibility of reducing product error by forecasting and controlling the process using online-measurement values on plural products. It is also necessary to arrange the controlling system depending on process variation.

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This paper presents how to make a solid model of the fillet volume for rounding corners such as vertices or edges. In order to be able to handle the fillet volume in CSG representation for geometric modeling, Sweep Operation is applied to generate the fillet volume. The outline is described below : 2-D Fillet Pattern, Spine, Sweep Axis and the object which is constructed by cubic primitive solids, are given. Then the fillet pattern, defined on a sectional plane which is normal to the spine, is swept along the sweep axis. Swept Volume consists of a set of space points which are inside or on the fillet patterns from start to end of sweep. Fillet Volume is generated as a result of swept volume, and can be added to the object for modeling of final shape with corner rounding. The algorithm of this work has been implemented in the CAD/CAM system TIPS-1. According to experimental results, it is clear that the work is effective for geometric modeling of an object being constructed by cubic primitive solids and fillet volume.

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The necessity is verified analytically and experimentally of the two-dimensional vibration analysis for the high-intensity ultrasonic system with a large diameter. By the joint use of the modal analysis with the finite element method, the two-dimensional vibration analysis program is made so as to be able to deal with the vibrational and piezoelectric behaviours of a body. On the basis of the respective results analyzed and measured by means of the program and the time-average holography, the followings are obtained : (1) The analyzed values coincide with the measured values. (2) The ultrasonic system with a large diameter must be analyzed by the two-dimensional vibration analysis method. (3) The program can be applied to analysis and design of the ultrasonic system.

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When the difference of pressures between inlet cylinder chamber and exhaust one is small and also the sliding velocity of piston becomes considerably small, the stick-slip motion is generated. Under some assumptions, the approximated practical equations of motion of pneumatic cylinder is obtained. The period of stick-slip motion and the displacement of piston during one period of stick-slip motion are also obtained by approximated equations. Analytical results show that the period of stick-slip motion and the displacement of piston are affected by the position of piston, orifice area of speed controller, pressure of air supply and so on. For example, in the case of meter-out circuit, the period of stick-slip motion and the displacement of stick-slip motion increase as the volume of exhaust cylinder increases. On the contrary, in meter-in circuit, both period and displacement decrease as the volume of exhaust cylinder increases. In either case, the period and the displacement decrease as the pressure of air supply increases. But the influences of load on the period and the displacement are quite small. These results are shown in various diagrams. The theoretical results agree well with the experimental studies.

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This paper describes an investigation on the behavior of bolted joints tightened in plastic region based on the numerical analysis by use of the flow theory of plasticity. A thread part of a bolt is idealized as a smooth cylinder. The change of axial tension, torque and stress distribution are discussed for two kinds of loading paths, namely the initial tightening and the subsequent axial loading processes. In the analysis, the torque and the axial tension are applied proportionally in the initial tightening up to a certain value of the elongation of a bolt, and the subsequent external axial load is imposed to the bolt keeping the torsional angle constant. The numerical simulation can duplicate the characteristic change of torque and axial tension observed in experiment that the torque decreases rapidly with increasing external axial load. The tensile stress distribution, which had a peak at the center of the cross section of a bolt in the external loading process with decreasing shear stress.

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In transverse impact self-loosening tests for threaded fasteners, rolling contact condition and flexible tension-type load cell have been used instead of metal-to-metal contact condition and relatively rigid clamped parts, respectively. So it is required to consider the effects of abovementioned differences between test and practice in order to utilize the results from conventional tests in mechanical design. This paper aims to clarify the effects of contact condition and of rigidity of clamped parts (or load cell). The testing machine is developed in which contact plane with rolling contact condition and tension-type load cell can be easily replaced by metal-to-metal contact condition and newly developed rigid compression-type load cell, respectively. Averaged preload loss per cycle in steady-state region is selected as an index to evaluate the self-loosening characteristic. The following results are obtained in this study : (1) The critical impact energy at the self-loosening limit is considerably dependent on the contact condition. (2) If the data are arranged by maximum displacement of the plate subjected to impact, the self-loosening characteristics are hardly affected by testing conditions.

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