In the previous report, theoretical results upon cutting resistance, and problems with regard to edge radius of the blade were considered through some experiments, in cases in which soft polymers were ordinarily cut. Even though a sharp blade was used, ordinary cutting was subject to considerable difficulty owing to material deformations and deflections when the solid friction acted between the surfaces of the blade and the material. This paper treats the method of vibration cutting which utilizes effective reduction of the solid friction by vibration. Theoretical results of this method such as reduction of cutting resistance and fine cutting without attending with such difficulties are confirmed experimentally by cutting soft polymers with the blade vibrated sinusoidally. Not only the extent of vibration velocity amplitudes but also of critical displacement amplitudes which can probably yield enough vibration effects with respect to the vibration cutting are discussed. And in addition, results utilized as application of this method for practical purposes are described.

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It is tried to use the S 2 type of gear rolling tester at the high rotational speed where the meshing frequency is about 1/2-2 times as large as the natural frequency of a pair of gears. This trial is based on the simplified measuring principle. As a result, it is found that the gear rolling tester can measure the dynamic transmission error of gears with the accuracy enough for practical use. Next, the dynamic transmission error of hobbed gears which have large profile errors is measured under light load condition, and the vibration of gears is studied experimentally. As a result, the following phenomena are observed : the large and irregular vibration skipping several teeth occurs near the resonance speed of gears, and it does not decrease even at the higher rotational speed than the resonance one, the period, where the teeth of gears separate and do not mesh during rotation, reaches 70%-80% of the total rotational period and also do not decrease at the higher rotational speed than the resonance one.

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In the 1st report, two new devices named a swirl type shutter were designed and applied to the vibration measurements by holographic interferometry, in order to remedy the defect of the realtime method. This paper deals with deformation measurements of object, and describes the feature of the methods comparing with the conventional one. These techniques consist of two, one is used for measurement of deforming amount, and the other for measurement of deforming velocity. The methods of measurement using a swirl type shutter have been studied and are of more practical use compared with the real-time one.

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The cooling effect on the wheel-work contact area is expected because the contact area is large in the vertical spindle abrasive machining of steel. The considerations including the cooling effect must be given to the grinding temperature on the contact area. This report experimentally studies the heat transfer coefficient to coolant on the contact area and the influeAces of the heat transfer coefficient and the grinding conditions on the contact area grinding temperature. The main results are as follows. On the contact area, the heat transfer coefficient of 0.5-1.0 cal/cm²·s·°C can be obtained relatively easily in the proper methods of cooling. It is considered that the relatively higher heat transfer coefficient can be obtained because of velocity increase of coolant stream on the contact area by rotating wheel. The cooling effect on the contact area increases with widening contact area and slowing work feed rate as well as increasing heat transfer coefficient. The cooling effect of the order of 50% was obtained in the case of slow feed rate (6-12 m/min) by the proper cooling methods. The grinding temperature on the contact area dose scarcely change with the feed rate as a result of cooling.

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In grinding operation, grain cutting edges as tool are supported elastically by bond, and workpiece to be ground is an elastic-plastic body, so that, at the grain cutting edge-workpiece contact zone, elastic as well as plastic behaviors exist such as elastic displacement of grain cutting edge position, local elastic deformation of grain cutting edge, elastic deformation and recovery of workpiece, and pile up of workpiece material or the side faces of cut groove, and these behaviors affect grinding force, finished surface roughness, residual depth of cut, and so on. The paper describes a simulation of grinding process including the elastic and plastic behaviors, and some discussions are made on the results obtained by the simulation. Taking account of the elastic and plastic behaviors in grinding operation can give a satisfactory explanation to the experimental results of grinding force and ground surface roughness.

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In this paper, the grinding characteristics of reginoid wheels are investigated to know the adequate grinding conditions. Parameters which represent the grinding processes, such as specific grinding energy, grinding rate, etc. are measured for the grinding wheels with various hardnesses. From the experiments, it is indicated that the grinding process can be classified into three states, i. e. glazing, breaking and normal grinding state, by tracing the parameter change with grinding time. Furthermore, it is pointed out that the ratio of the normal grinding pressure to the elastic modulus of grinding wheel is successful for classifying the above mentioned grinding states.

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A theoretical approach is presented to the plane theory of rolling contact with friction. In the present paper, the existence of the stick area is considered, then the boundary conditions of this problem are derived and the analyses of elastic contact of two cylinders are given. When the contact area is constituted by the stick area alone, the boundary value problem results in the Hilbert problem in the theory of functions. If two cylinders have the same material properties, the stress field coincides with one of Hertz contact. If they have not the same material properties, the contact width becomes shorter and the maximum contact pressure becomes higher than those of Hertz contact. Then, the tangential force is not transmitted. In addition, the stress field is discussed on the assumption that two cylinders, having the same matertial properties, constitute the stick and slip areas. In this case, the contact pressure and the contact width coincide with those of Hertz contact. Then, the stick area can exist in the neighborhood of the leading edge and the length of the stick area is determined uniquely by the values of the normal force, the tangential force and the coefficient of friction in the slip area.

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The effects of the external tool vibration on the cutting force and surface roughness are investigated. Using a prototype oscillatory feed cutting unit developed for the experiment, the tool nose is oscillated mechanically in the direction of feed motion of the lathe. The results obtained are as follows. (1) The magnitude of cutting force exhibits a loop during one period of tool oscillation, and when the effective feed is increasing the cutting force is smaller than that of ordinary cutting. But the maximum cutting force is nearly equal to the ordinary cutting force at the nominal feed equal to the maximum effective feed. (2) The surface roughness becomes larger with increasing of the amplitude of tool oscillation and a fraction Z in n/N (=i±Z, i, integer, n, N; numbers of tool oscillation and work rotation). The negative feed is not effective actually to improve the surface roughness, and the suitable condition of breaking chips and improving work surfaces is contrary to each other.

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Self-excited vibration in grinding caused by the regenerative effect of workpiece surface has been investigated by many researchers. In those works, however, the limit of stability has not been given n the form of practical equation. In this papar, a method to obtain the limit of stability by measuring the static grinding force and the frequency of small amplitude in grinding process is proposed. The results obtained are as follows. (1) The stability limit equation is given in a practical form, i. e. as a function of workpiece speed, depth of cut and grinding wheel width. (2) The calculated results of the limit of stability which are obtained by using informations in grinding process agree well with the experimental results.

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A hardware system using a microcomputer, developed for detecting onsets of chatter vibrations in real time and to stop machine tools when chatter occurs, is described, together with the experimental results of the system. Hence the hardware described in this paper is obtained at a low price, the machine tool can be protected from chatter vibrations by a little investment. The detection of the chatter vibration is performed by directly calculating the intervals of the peaks of sound signals in cutting operations, so that the microcomputer, which is not so fast device, can be used in this system. The results of the tests reveal that this system is useful for realtime detection of chatter vibrations and can be applied to the simple control of machine tools in a wide range of cutting conditions.

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The conventional testing methods of tool toughness are transverse rupture test, Charpy impact test, etc. But the results of these testing methods do not represent actual tool toughness in cutting, especially, in intermittent cutting with carbide tool. The objective of this study is to develop a methodology to assess cutting edge toughness simply and reliably. This method is an impact test n which a tool material repeatedly hits the fresh surface of a comparatively soft material corresponding to the material cut so that intermittent cutting can be simulated as close as possible in view of stress situation at the cutting edge and dynamic behaviour. Some feasibility tests have revealed that this method is valid for estimating tool toughness against chipping observed at the initial stage of cutting. The Weibull plot of the relation between cumulative probability of chipping and impact frequency generally becomes linear and the mean impact frequency is affected by the impact frequency energy.

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In the first report, the author had succeeded in recording simultaneously the rotational error of both the worktable and the hob shaft and the cause of both rotational errors was inferred by examining their power spectra. Also, it was ascertained that a qualitative coincidence existed between the tooth profile estimated by the relative rotational error measured and the test result of the tooth profile generated by the machine. In the case of a common hobbing machine, the torsional rigidity of the driving system is not sufficient in its construction. Being considered that this insufficiency of the torsional rigidity may cause the rotational error, the experiment was carried out, by employing the already reported hobbing machine, on the torsional excitation of the hob shaft in not-driving situation and the impulse response was examined by hammering the driving worktable in the counter-rotational direction. By comparison of the torsional dynamic digidity obtained with both rotational errors in the previous report, the rotational erroneous components caused by the insufficiency of this rigidity were revealed. Additionally, the cause of the rotational erroneous component which induced the large error of the tooth profile was investigated.

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A traverse grinding technique with partially circular wheel on the leading part of acting wheel surface is introduced and experimentally analyzed to prove that high efficiency and high accuracy can be obtained in the traverse grinding. In the technique the effective cutting depth of wheel varies in different positions along wheel width on the acting wheel surface. In other words, the effective cutting depth of wheel increases in the leading part of wheel and takes maximum at a point, and decreases gradually down to zero near the junction between the leading circular part and the following straight one on the acting wheel surface. The variation of the effective cutting depth of wheel characterizes the grinding process and leads to better surface finish in the process. High grinding efficiency can also be obtained in the technique without burning or detriment to surface finish, because the interference of wheel to workpiece in the neighborhood of finishing surface is not affected by increasing the setting depth of wheel. Furthermore the wheel wear in the process is remarkably low as compared with that in the conventional process.

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The three-dimensional measuring system was developed and its performance was tested as the first stage to evaluate the three-dimensional characteristics of surface asperities. The measuring device was designed and manufactured to obtain the discrete data of asperity heights sampled at nodes of matrix on a surface. The present system consists of the profilometer of tracer type, the precision table which moves perpendicular to tracing direction of stylus, and the controller which drives the devices automatically. Ground surface (σ=0.4μm) and lapped one (σ=1.1μm) were measured and shown by the perspective pictures and the contour maps. The three-dimensional characteristics of these surfaces can usefully be evaluated by using the present system.

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The aim of this study is to get a tester which can be made easily and has sufficient measuring accuracy for practical use. A conventional tester for external gears is utilized. Tooth profile errors are detected by an electric micrometer and recorded on an X-Y recorder. Internal gears are set on a rotary table and chucked by three pins equipped on the table from the outside of gear blanks. The centering of gears is performed simultaneously in the chucking. Even if an eccentric error of 0.05 or so exists in the centering, its influence on the tooth profile error curve can be neglected by selecting the tooth of internal gears suitably. Influences of the position error of the feeler, the inclination of the top plane of the table, and the deformation of the outside cylinder of gear blanks are examined theoretically and allowable values of these errors are given.

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To examine the machining accuracy and the machining performance of a machine tool, it is necessary to clarify the static, dynamic and thermal behaviour of the attachments of a machine tool. The taper connection, which is one of the typical attachments, is recently becoming the wide use as a part of the automatic tool changer in a numerically controlled machine tool, because it can easily and firmly connect two components each other. There are, however, a few studies on the behaviour of the taper connection as compared with those of other type joints such as bolted, sliding and so on. This paper deals with the stiffness of two types of the taper connection, i. e. the Morse Taper as a self-holding type and the National Taper as a self-releasing type. Experiments were carried out to evaluate the effects of the contact pressure, contact area, applied load, etc., which are important factors in the case of open type joints like a bolted or sliding joint, upon the joint stiffness of the taper connection. As the results, it is observed that these factors have a little effect on the stiffness of the taper connection, and that the deterioration of the joint stiffness is very small when comparing it with that of the equivalent solid model. These noteworthy behaviour may be due to the characteristics of the closed type joints.

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[in Japanese]

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