This paper describes a method to measure the parallelism of a large thin plate (whose thickness within 2 mm, length 200 mm, and width 70 mm) using a pair of oblique incident interferometers, employing two holographic gratings, as a beamsplitter and a recombiner, This method has the following advantages.
(1) As the reflectance of the surface is enhanced in comparision with that for normal incidence, the non-optical surfaces which have low reflectance can be examined by this method.
(2) The foreshortened view of the surface allows large areas to be examined using relatively small aperture wavefronts.
(3) The fringe interval in the interferograms is independent of the illuminating wavelength, representing one half of the diffraction grating periodicity, and 5 pm in this experiment.
Many different parallel surfaces have been examined, including optical parallel and parallel unworked ones of various metals.

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A method has been developed to identify spring stiffness and damping coefficient at a joint interface (by interactive use of theoretical simulation and experiment) which could be generally applied to practical slideways and bolted joints. This paper describes the procedure of this method and shows the results. This identification method uses the experimental models not containing the influences of elements other than the joint under study and the computer simulation identifying the equivalent values of the joint interface itself. The identified equivalent spring stiffness and damping coefficient per unit area of joint interface show the significant change for the magnitude of the mean contact pressure. The effects of the magnitude of the mean contact pressure on the equivalent values are completely different in the shear and normal direction of the interface respectively. The significant values were derived with respect to the kind of oil on the contact surfaces of the joint. It has been confirmed that the values of the equivalent spring stiffness and damping coefficient which depend on the magnitude of the mean contact pressure can be applied to general joints which have the same property of contact surface but differing in shape and contact area.

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The contact mechanism between spheres and rough plates is theoretically analysed for the mixed contacts that the contacting asperities are deformed elastically and plastically according to their displacements being less and greater than a critical displacement, respectively. Analyses are also carried out for the contacts in which all the contacting asperities make elastic deformation and plastic deformation respectively, regardless of the displacement of their asperities. The analyses lead to the results that some differences in the analytical results arise from the mixed, elastic and plastic contacts. To confirm the analytical results experimental investigations are carried out pressing a steel ball against rough plates under various loads. To observe the clear indentations made on rough plates, a technique coating a rough plate with an evaporated carbon film in vacuum and a lump black film is successfully used. The approaches between a ball and rough plates are also measured under various loads using the differential transformers. Little difference is found between the analytical results and the experimental ones.

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The composite material made from the Shirasu Balloons (hollow glass micro sphere produced from acidic volcanic ejecta) and aluminum alloys is a new industrial material, the porosity of which is extremely large, i. e., about 50%, the specific weight is very light, i. e., about 1. 4, and the heat insulation is fine. This paper describes the machinability of the composites comparing with that of the matrix metal, Al-12%Si alloy. In this turning, the tools used are a high speed steel tool SKH 4 and a carbide tool K 10, the cutting speeds varied from 50 to 400 m/min. Results obtained are; (1) For dry cutting, to obtain good finished surface of the composites is difficult. The use of cutting fluids is useful. (2) The cutting temperatures of the composites are much higher than those of the matrix metal for cutting speeds over 200 m/min. (3) The tool wears for cutting composites are larger compared with for the matrix only. (4) For dry cutting, if the machining of the composites are performed, by using more suitable tools, on a suitable cutting condition, those troubles mentioned above will be solved.

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In order to investigate the generation and propagation of pressure wave by spark discharge in liquid systematically, the voltage across the electrode gap and the discharge current are measured with an accuracy required in the above-mentioned analysis as the first step. Using the results, the resistance of the electrode gap and the electrical energy supplied to spark channel are discussed. The kinds of liquid used in the experiment are tap water, O. 1% and 1. 0% NaCl solutions. The results obtained are as follows :
(1) Regardless of the kinds of liquid used, the resistance of the electrode gap decreases abruptly from the intrinsic resistance of the liquid to O.1-0.3 ohms after the breakdown of the liquid. After that, it varies with the cyclic variation of the discharge current. Also it has a tendency to increase with an increase of the electrode gap distance in all kinds of liquids.
(2) Regardless of the kinds of liquid used, as the first minimum value increases in the cyclic variation of the resistance after the breakdown of the liquid, the electrical energy of a first-wave in the electric power wave becomes larger and the electrical energy supplied to spark channel is centered at the first-wave in the electric power wave.

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This article describes new methods to measure the tooth profile of the axial section of a worm accurately to a high degree with a ball shaped or a disk shaped probe. When the probe is moved along the tooth flank keeping its center on the axial plane of the worm, the trace of the center does not represent the tooth profile to be determined. In this paper, three methods of determining the tooth profile from the measured trace are presented.
(1) A method based on the nominal tooth profile.
(2) A method using the tooth profile approximated by a polynomial curve of degree 6.
(3) A simplified method using an approximate formula.
It is proved concerning two types of worm that the measured profile which is obtained by using one of these methods agrees with the other two.

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Characteristics of vibration has been analyzed with a model of lumped system for a tool used in ultrasonic vibration cutting. The analysis shows that the amplitude of the tool vibration during cutting declines not always constantly but catastrophically with increase of cutting force at some conditions because of existing unstable phenomena in the vibration. For lower cutting speed the catastrophical attenuation of the vibration is more drastically, but higher amplitude is maintained before then. The analysis is applicable enough by taking into account the fact that the cutting force changes in practice depending upon the cutting phenomena at each condition.

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Lapping parameters in a reciprocation lapping were investigated about their influences on the surface generation process of upper and lower workpieces. Relations were revealed between the parameters and characteristic constants used in a linear differential equation which described the process. Simulated and experimental results show that (1) the process is fastened by increasing the lapping load and by applying proper stroke of the reciprocation, (2) the deviation from the tendency for the upper and lower workpieces to fit each other is affected by the distance between a pivot axis and a lapping surface and the frequency to supply newly abrasives and (3) the deviation caused by each parameter in (2) can be distinguished by the posture of the upper workpiece through the process.

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Two new methods of vibration measurements by holographic interferometry are proposed; one based on the stroboscopic method is used for measurement of periodic oscillations, and the other based on the time-average one is used for measurement of damped oscillations. The essential feature of the method is to use a swirl type shutter which is revolving just in front of the hologram plate. The variation of vibration is observed by the device, as well as the real-time method. The present methods have many advantages as follows : (1) Since the information is recorded and stored in a hologram as three dimensional images, evaluation is simply a matter of reconstructing the images with a laser beam focused on the area of interest. (2) The reconstructed images are hardly influenced by environmental disturbances during the observations. (3) The distortion of photographic emulsion which occurs by a developing process has little influence on images and fringes because the object is recorded by the double exposure and time-average one in our methods. (4) The procedure is simpler than that by the real-time method.

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This paper describes an optimal design method for positioning control using a dc servomotor. The positioning control system, using velocity and position feed back data, sometimes becomes unstable due to mechanical resonance of the shaft connecting motor with detector. An appropriate cutoff in high frequency of velocity is effective not only for stabilizing system but also for high transient response. Namely, it causes a 30 percent decrease in settling time for step input and 1.3 to 3 times increase in stability criteria. Finally, the procedure for optimal design is described.

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A quantification of the sensuous sharpness and mechanical sharpness of kitchen knives is investigated and the followings are revealed.
(1) The sharpness based on a man's sensibility can be quantified by the method of paired comparison based on the sensuous sharpness evaluated by cutting sweet potatoes.
(2) A significant correlationship is recognized between the sharpness measured by the new sharpness testing device and determined that by the above described sensibility. Therefore, the sharpness measured by the sharpness testing device almost agrees with the sensuous sharpness.
(3) There are two criteria for men to judge the sharpness of any given kitchen knife-one is the initial resistance force to be felt at the time when the kitchen knife is applied to the material to be cut and the other is the resistance force to be felt in cutting through the material.
(4) The mechanical characteristics of the knives that affect the sharpness are the angle of cutting edge, the non-uniformity of thickness and the surface roughness of the cutting edge.

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Some experiments of cutting are carried out by using various shapes of pyramidal tools, modeling cutting by a grain in face grinding. The work is made of Plasticine whose similarity with heated steel is claimed. Some results are obtained which agree with results for steel by using a single grain as follows :
(1) Whatever shapes of pyramidal tools are used, the change of the grinding force depends upon neither the height nor the area of the clearance face.
(2) The changes of the grinding forces by using conical tools and triangular pyramidal tools are quite alike, but those by using hemispherical tools differ from them in tendency.
(3) The ratios of the tangential force to the normal force in cutting by hemispherical tools and conical tools are the same and the one by triangular pyramidal tools is smaller than those.
(4) The change of the grinding force with respect to the area of cut doesn't depend on the direction of the face of triangular pyramidal tools.
(5) The grinding force is inclined to increase slighty as the cutting speed increases.

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This paper deals with problems of in-process measurement for Geometrical Adaptive Control (GAC) in turning. It is generally said that errors of a measuring instrument should be at least five times smaller than the required tolerance in the actual environment on a machine tool. In use a measuring instrument should be capable of withstanding vibration and temperature change and must operate in the presence of coolant, cutting fluid, smoke and so on. Before actual use of a new measuring apparatus developed by the author, various measures are taken against those disturbances and satisfactory results are obtained through several experiments. In this paper, the influence of surface roughness, vibration, time lag of measurement and curvature of a machined surface are discussed and measures against these effects are experimentally investigated.

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In order to clarify the self-loosening mechanism of threaded joints which are subjected to ultrasonic vibration in the axial direction, the separating phenomena between the bearing surfaces are investigated experimentally and theoretically. The obtained conclusions are as follows : (1) The theoretical values of the amplitude on the assumption that the bearing surface may begin to separate when the amplitude of vibrational stress on the surfaces reaches the mean compressive stress by tightening force approximately agree with the experimental ones. Then the above-mentioned value, which is called “Critical Amplitude at the Separation between Bearing Surfaces”, is proposed as a criterion of self-loosening of threaded joints. (2) The separation between bearing surfaces is affected by lubricating condition. The critical amplitude with silicone grease is larger than that with machine oil or without lubricant in the range of this experimental conditions.

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