[in Japanese]

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[in Japanese]

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[in Japanese]

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In this paper, rotation accuracy of a cylindrical workpiece held between centers is investigated by experiments and computer simulations in the cases of 60° Type-R center hole and 60° conical center hole. In addition, circularity of a workpiece finished by cylindrical plunge grinding is investigated experimentally. From the results, it is confirmed that in the rotation accuracy and circularity, 60° Type-R center hole is superior to the conventional 60° conical center hole.

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In this report, it is analayzed theoretically that female precision threading of ceramics can be realized by a new precision ultrasonic super position vibration tapping. And this analytical results can be confirmed by the experiments using a newly developed precision ultrasonic super position vibration tapping machine with the electric stepping motor and 28 kHz ultrasonic torsional vibration mode diamond tap (M 5 pitch 0.8 mm). The main results are as follows : (1) It has been verified that precise female screw threading of WA wheel (φ15×5) can be machined by a new ultrasonic super position vibration tapping machine with diamond tap in one stroke and more efficient. (2) Female thread with precise screw thread shape can be machined more efficient and unusual cutting noise and tap failures scarcely occurred of appliance of earthenware and glass of daily use. (3) By this study, it is believed that this new tapping machine has the possibility of precision machining in female screw threading of various kinds of ceramics.

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This paper deals with the thermal deformation of a workpiece, which is expected to affect the ground-surface straightness in cross-feed direction, by means of a finite-element method. Estimated results of the thermal deformation are compared with measured profiles of ground surfaces. Besides, the effect of chamfering at workpiece corners and supplying a grinding fluid on improving the straightness are verified. The main results obtained are as follows : (1) The thermal deformation caused by grinding heat results in the concave profile of a ground surface in crossfeed direction. (2) The measured depths of the concaves ΔZ agree well with the results which are estimated by taking the elastic-plastic property of a workpiece material into consideration. (3) The chamfering on workpiece corners diminishes the value of ΔZ. (4) When the grinding fluid is sufficiently supplied at a grinding point the value of ΔZ is effectively decreased.

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Forming efficiency and grinding ability of metal-bonded, resinoid-bonded and vitrified-bonded diamond wheels for V-profile groove grinding of fine ceramics are experimentally investigated, analyzing initial profile of formed wheels, wheel wear, stock removal, grinding force, number of cutting edges on working wheel surface and so on. Main results obtained are as follows : (1) Initial profile of formed metal-bonded diamond wheel dressed by rotary dresser is better than that dressed by GC stick grindstone, while grinding force in the case of rotary dresser is larger than that of GC stick grindstone. (2) Geometrical error of the V-profile formed on metal-bonded diamond wheel is large and grinding force with this wheel is large, but the rate of change in V-profile is small. (3) V-profile is easily formed on resinoid-bonded and vitrified-bonded diamond wheel and grinding forces with those wheels are small, but the rates of cange in V-profile are large.

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For the purpose of cutting papers and laminated paper sheets cleanly, the best parameters of cutter revolution and cutting velocity were pursued. In the experiment, the revolving knife-edged cutter driven by a motor built in a die set is used. A newly developed electromagnetic micro press is also used for cutting with a speed up to 1. 5 m/s. As the cutting materials, ordinary paper and three kinds of laminated paper sheets are used. Obtained results from the experiments are as follows : by revolving the cutter, the cutting load and penetration depth necessary for perfect separation of the material can be substantially reduced. These effects are caused by the decrease in the so-called effective edge angle with the increase in cutter revolution. High velocity cutting can also reduce the penetration depth. The increasing inertia of the material to be cut and of backing plate is speculated to be a cause of the reduction. Cut surfaces can be remarkably improved by both of the above two effects, i. e., cutter revolution and high velocity.

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This paper deals with a formation mechanism of the chipping on the workpiece end by using a finite element method and an experimental method. In the calculation, cutting force in the contact zone is considered. Therefore, the mechanical stress distribution near the workpiece end are derived. The grinding is carried out to clarify the effect of work speeds and depths of cut on the chipping size. The main results obtained are as follows : (1) The Compressive stress region in front of the cutting point acts an important role to remove the material when wheel is located sufficient distance from the workpiece end. (2) The chipping of the workpiece end is mainly caused by the tensile stress behind the engaging cutting edge. (3) The chipping size is closely related to the grinding forces.

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In this study, stainless steel (SUS316L) coated with titanium nitride ceramics (TiN) is proposed as an orthopedic implant. Effects of surface finishings of the stainless steel on bonding strength of the film are investigated. In order to decide optimum film thickness, the bonding strength test and the wear test are carried out. Then resistance to chemical agents and reactions of the surrounding tissues are studied. Results obtained are as follows; (1) The thinner the TiN film, the stronger the bonding strength. (2) After 10⁷ loading repetitions, any cracks can not be observed on the TiN film. (3) Based on animal experiments, the biocompatibility of the TiN coated stainless steel appeared to be superior to un-coated material. (4) Stainless steel is etched with HCl through pin holes on the TiN film.

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The paper presents an analytical method which enables us to predict the dynamic cutting forces under chatter vibration by using the data of orthogonal, steady cutting test. For small amplitude of the vibration, an instant of the dynamic cutting can be regarded as the steady cutting of an equivalent tool rake angle which depends upon the inclination of the outer modulation of the vibration. When the amplitude exceeds a certain limit, however, the tool-chip contact length does not catch up with the variation of the uncut chip thickness, hence a non-steady chip forming process appears in place of the usual one of the straight shear plane. The slip line theory of plasticity is applied to this transition and the dynamic cutting forces are obtained. Dynamic cutting tests including wave generation, wave removal, and wave combined proved the forces predicted are in good agreement with the experimental results, which clearly show the non-linear variation with the uncut chip thickness.

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An estimation method is proposed for determining the distribution of volume fraction of a phase which is transformed from a matrix phase in the surface layer during grinding. The method utilizes the fact that contribution of diffracted X-rays on a certain layer of the material to the total intensity of diffraction varies with the incident angle of X-rays in the thin film X-ray diffraction technique. The method is applied to analyzing the surface layer of yttria-doped tetragonal zirconia polycrystals (Y-TZP) ground by diamond wheel. It is found that the volume fraction of monoclinic generated by grinding becomes the maximum near the ground surface and decreases gradually in the deeper layer up to a few microns. The maximum volume fraction and the existing depth of the monoclinic become small with decrease in the average grain size of diamond wheels and in work feed speed.

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This paper describes a method of obtaining a surface region of pentagonal and hexagonal shapes which appear around a concave-convex mixed vertex of a polyhedron which represents a basic feature of a surface. Features of the method are i) Final shapes are obtained from Bezier patches, and ii) Dispositions of control points are automatically defined by specific locations of the polyhedron. The element patch is degree two for the pentagonal region and degree three for the hexagonal. And a connecting condition of patches is C¹. At first authors treat roundings and filletings for the pentagonal region around a vertex formed with convex and concave edges. Then five patches of degree two are obtained for such case. Secondly authors derive six patches of degree three for the hexagonal region to show an application of the method which requires higher degree patches. An example of such application is also shown.

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This paper deals with an automatic marking system for large castings and forgings. The developed automatic marking system consists of three subsystems ; that is the 5-directional 3-D object (or form) measuring system to obtain the entire workpiece shape, the automatic matching software to determine the relative position of product model in the measured workpiece model space, and the automatic mark scribing system to scribe marks on the workpiece for indicating the determined position. Satisfactory results have been confirmed by some experimental tests.

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This paper presents a method by which not only the shape but also the depth of defects in a plate is inspected nondestructively. A sandwich structure sample plate which consisted of three layers was made in order to demonstrate the usefulness of the method ; the middle layer is 1 mm in thickness and has six different round and square holes in it, the upper layer is 0.125 mm in thickness and the lower one is 0.254 mm in thickness. The plate is vibration stressed and inspected from both the upper layer side and the lower layer side by ESPI (Electronic Speckle Pattern Interferometry). A defect has two different resonant frequencies f and f' for the both sides. The shape of a defect is decided by ESPI fringe patterns and the depth of it is calculated only by knowing f, f' and the thickness of the plate. The experimental results showed the accuracy of the depth of a defect is 2 × 10^-2 and 1 cm diameter sized defects can be observed in the 15 cm × 15 cm area.

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The feature of W-N (Wildhaber-Novikov) gear is that the engagement of tooth surfaces becomes a contact between concave and convex surfaces, resulting in small relative curvature and high surface durability. However, this gear has a defect that it is very sensitive to the center distance error. So, we developed the tooth profile that causes it to become insensitive to the center distance error without injuring the advantages of the W-N gears. We clarified that the relationship between the change in the center distance and the operating pressure angle differs depending upon the rate of change of radius curvature of the tooth profile, and studied and indicated the tooth profile having what radius curvature is suitable for the W-N type gears.

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The dispersion of tightening force in plastics bolt is discussed, for the two methods of tightening which are usually applied to steel bolt, from the view-point of obtaining the higher precision of tightening force in the bolt. The joints with plastics bolt used here are classified into two types from the standpoint of different combination of materials which take part in sliding friction, that is, TYPE 1 composed of plastics-to-plastics and TYPE 2 plastics-to-steel. Both methods of tightening are also conducted by two ways of manual and power drive and they are compared each other. As the results, main conclusions obtained on the dispersion of tightening force are as follows : (1) The tightening by the turn-of-nut method can reduce the dispersion as compared with the calibrated wrench method. (2) In the turn-of-nut method, lower snugging torque results in higher precision in tightening force. (3) In TYPE 1, the dispersion in manual drive is larger than that in power drive, in case of the calibrated wrench method, while the difference of the dispersion between manual and power drive is negligible in case of the turn-of-nut method. (4) In TYPE 2, the difference of the dispersion between manual and power drive is negligible in both methods of tightening.

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The aim of this paper is to develop bearings which have the followings as their principal features : ultra-precision, non-contact, infinite stiffness and high damping capability. To accomplish these, the authors propose an “Active Air Journal Bearing” (AAJB) capable of precisely controlling the radial axis position. The AAJB utilizes non-contact sensors to detect the radial position of its axis, non-contact actuators (movable air pads driven by PZT actuators) to support and drive the axis, and a controller to regulate the whole system. The paper presents procedure for designing the controller parameters as well as method of analyzing the AAJB stiffness and the positioning characteristics. Some simulated and experimental results show that the AAJB has : (1) an almost infinite static stiffness and an increased damping capability, (2) a bandwidth of more than 1kHz and (3) a positioning accuracy better than 15nm.

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Sound is generated in laser beam machining. In the present paper, relationships between sound and drilling ability are obtained for Q-switched YAG laser. Sound pressure level is high when a hole is being drilled with high speed. From these experimental results, a new controlling system for laser beam drilling is developed ; this is a system for laser switching, automatic beam focusing and refocusing. A hole is drilled to the rear surface of 2mm thick Si₃N₄ plate in 8s ; on the other hand, this plate cannot be drilled to the rear surface even by a bombardment of laser beam longer than 10 minutes without this system.

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A new method of measuring pitch diameter of internal thread is devised, and its measuring principle and procedure are discussed fundamentally. Three balls are attached to a three-point internal micrometer, and each ball is inserted into a thread groove. From the geometrical condition of an equilateral triangle whose every apex is on a helix, a set of simultaneous equations is derived. Solving the equations, a reading of the internal micrometer is transformed into the diameter of the helix from the diameter of a circumscribed circle of the equilateral triangle. Numerical solution of the simultaneous equations can be obtained rather easily, and besides approximate solution is shown. A measuring instrument is manufactured practically, and accuracy of the three ball method is verified. The three ball method gives good agreement with results by a universal measuring microscope within difference of 3 μm.

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