In the usual detecting method of initial fracture of tool edge by AE signal, the burst AE signal over a threshold level has been employed for detecting tool fracture in metal cutting. However, it is uneasy to pick up only the AE signal caused by tool fractures among those which are generated from the region near cutting edge. In this study, the orthogonal interrupted cutting has been carried out and some AE parameters ; AE count rate, accumulative count and amplitude distribution ; have been measured in order to obtain the relations between initial fracture of tool edge and AE parameters and to confirm the relations between initial fracture of tool edge and disengage angle. As the result of experiment, it has found out to detectable the initial fracturing state of tool edge by AE parameters. In addition, it is able to keep away the misdetection by the shock of interrupted cutting or chip in this measuring method.
Taking account of the reuse of bolts and nuts, this paper describes a comparison of threaded-fastener loosening characteristics of bolted joint in the elastic region tightening with those in plastic region tightening and the reason for the difference between them. The experiments are carried out by using the threaded-fastener loosening test machine which applies repeated transverse impact-force. The experimental results are as follows ; in the first use of bolts and nuts, the initial loosening in plastic region tightening is larger than that in elastic region tightening, but for the steady loosening the reverse tendency is found. At the reuse in elastic one, both initial and steady loosening are smaller than those in the first use, but in plastic one both loosenings are larger than those in the first use. The above mentioned results can be explained by the measurements of bolt end displacement, impact block displacement and twisting torque in the loosening test.
In-line Fraunhofer holography is useful for measuring the size and spatial distribution of moving or stationary particles in air or a liquid from a few micron to a few hundred micron in diameter. However, the reconstruction processes of the measurement are tedious and take appreciable time, therefore the automatic measuring instrument is needed to have successful results. This paper deals with a fundamental study on the automatic holographic particulate measurements. The results obtained are as follows. (1) CCD line sensor-scanning device is built so that holographic reconstructed images can be stored to computer. (2) Using this device, light intensity distribution in the reconstructed image of wire is observed, and the results agree with theoretical simulations. (3) The index W-value is proposed as a focusing parameters. It is proved to be valid for determining the focal point of reconstructed real image. (4) The diameter and location of the wire can be measured automatically with this system.
A method to measure the motion errors of NC machine tools was studied by using telescoping type double ball bar test. The motion errors during circular interpolation motion were measured by detecting the relative distance between the spindle and the workpiece on the table using elastically connected bar. The motion errors, i. e. relative distance were polarly plotted. Those were obtained at both clockwise and counter clockwise motions in mutually perpendicularly intersecting three planes. The results show that it has sufficient accuracy and conveniency to evaluate the accuracy of NC machine tools. The polar plots of the measured motion errors has a good agreement with the out-of-roundness errors of the circular plate machined by the same condition.
In the first report, a method for calculating the cutting edge profile of hobs was proposed about the case that the value of coordinates and gradients of some points on a gear tooth profile was given. In this report treatments in three special cases which can not be treated by only the method proposed in the 1st report are considered. The first is the case that a discontinuity point exists on the gear tooth profile. The second is the case an incomplete hob tooth profile is obtained because there is a region in which the envelope by the given tooth profile does not exist. The third is the case the value of gradients is unknown and the method to obtain the approximation of gradients is given.
In drilling, the burr is always formed at the inlet and outlet of drilled hole. Various troublesome problems in the automatic machining process are induced often by the burr. Therefore, it is very useful to find out an effectual method for the prevention of the burr in drilling process. Under such a present day situation, the low frequency vibratory drilling was chosen as one of the subjects of our studies, that is, effects of the cutting conditions and the cutting force on the burr shape in this drilling were examined and compared with those in the conventional drilling. From this study, it was found that the application of this method for drilling of aluminum is effective to prevent the burr.
It is well known that the continuous chips cause various troubles in turning of the steel. So the chips should be broken into short segments. In this case, the chip breaker is generally applied very well. However, the commercial chip breaker is difficult to break the continuous chips under the wide cutting condition. The chip breaker for finish turning is different from that for other usual turning. In order to find out a more effective chip breaker configuration than the commercial chip breaker in turning, a new chip breaker is investigated experimentally at a constant cutting speed of 3 m/s. The first chip breaker configuration is classified in negative lead step former. This chip breaker is effective for the low feed and the small depth of cut. The final chip breaker configuration has been developed, combining negative lead step former with positive lead step former. The final chip breaker is effective for a wide set of cutting condition. That is, in turning of SS 41 steel this chip breaker can break the chip into small segment in the following cutting conditions ; the feed rate from 0.05 mm/rev to 0.51 mm/rev and the depth of cut from 0.1 mm to 3.0 mm.
Aiming at trimming and boring of steel material under water pressure, the effect of water pressure affecting the discharge phenomena was investigated by testing underwater single discharge under the hydrostatic pressure of 7.95 MPa. The result indicates that the effect mentioned below is appeared when capacitor charging voltage of 250 V DC is given to between a brass electrode in vibration of 32 Hz and a sample piece of S 45 C by increasing water pressure gradually. (1) Crater diameter of the sample piece becomes somewhat smaller while crater depth becomes deeper than the water level by about 25% at 7.95 MPa. (2) Both crater and upheaval sectional area are increased. Net displacement of the sectional area is slightly increased. On the other hand, no change due to water pressure is found on the wave forms and magnitudes of the discharge gap voltage and discharge current.
In this investigation, electro-chemical discharge grinding of Si3N4 ceramics is studied. This experiment consists of two main parts. One of them is electrochemical discharge experiment on Si3N4 ceramics and the other is combined test of electro-chemical discharge and mechanical grinding with a model wheel. The results obtained are as follows : (1) Removal amount of Si3N4 by electro-chemical discharge depends on kinds of electrolyte and its concentration. (2) To get the electro-chemical discharge phenomena in the electrolyte, it is necessary to give some certain voltage between electrode and electrolyte. Above this threshold voltage, removal amount of ceramics increases with applied voltage and discharge time. (3) Ceramics removal ratio (ratio of actual machined depth to setting depth of a wheel) increases by combining electro-chemical discharge phenomena with mechanical grinding. The combining way of electro-chemical discharge phenomena with mechanical grinding influences on the removal ratio. In this experiment, it is effective to give electro-chemical discharge during mechanical grinding. (4) In this combined grinding, the removal ratio decreases with increasing table speed and also it increases with increasing applied voltage. It is not influenced by wheel depth of cut. These results are explained by electro-chemical discharge frequency. (5) Form error of machined surface decreases by combined electro-chemical discharge phenomena with mechanical grinding.
This paper describes the chatter stability of a boring bar the side faces of which are cut off so as to have a directionality in dynamic characteristics. The chatter stability is analyzed by both the theory of a coupled oscillation and the theory of a regenerative chatter vibration, considering the dynamic cutting force. Furthermore the effect of the directionality on the suppression of the chatter, which is estimated by two theoretical analyses, is verified by some experiments. The results obtained are as follows : (1) Chatter stability limits evaluated by the theory of the regenerative chatter vibration are lower than those by the theory of the coupled oscillation in any condition. (2) Experimental results agree well with the stability limits of the regenerative chatter vibration. Therefore it is clarified that the chatter stability of the boring bar depends on the regenerative chatter theory. (3) It becomes clear that the chatter stability is not sufficiently improved by the side cut boring bar.
The object of this paper is to clarify the mechanism of an electrolytic grinding method in high work feed rate. Therefore, grinding force components and chemical electrolysis were investigated and discussed through the calculation on the basis of experimental results using alloy tool steel SKD 11 and others. Summary of the results are shown below. (1) Grinding force components in this electrolytic grinding method decrease with increasing applied voltage. Their decreasing rate depends on electric current and percent wear flat area. (2) There may be two roughly classified reasons for the decrease in grinding force components by electrolytic action. The first one is the decrease in mechanical removal volume by electrochemical dissolution. The second one which has the most effect is considered to be the loss of mechanical properties on the surface layer of SKD 11 induced by the preferential dissolution of the hardened second phase. This may cause to decrease the chip formation force and the contact pressure between the wear flats on abrasive grains and the workpiece. (3) The effectiveness of this grinding method is appeared in the suppression of the friction force between the wear flats and the workpiece, which increases in proportion to the increase in the wear flat area.
A method for determining the grade in the vitrified wheel in terms of the acoustic emission (AE) is described. Correlations between the grade and the amounts of AE pulses emitted from the specimen surface which is indented with either Vickers' or spherical indenter are investigated. Experiments are performed for eight different wheel structures at room temperature. As for the sphere indentation, a clear correlation between AE total counts and the grade obtained by conventional technique is found, if the small amounts of indentation load is subjected. Though total ringdown counts for the Vickers indentation are widely distributed, reflecting the statistical nature of the fracture process in a microscopically heterogeneous media, mean values should give the appropreate results. While these examples tested are not widely ranged in the grade, they do show availability in applying the AE technology to the determination of the degree of the wheel grade.
When soft polymers are cut by means of a knife blade, cutting surface quality is determined by the following factors. The first is geometrical factor, i. e. the shape and the machining accuracy of the knife-blade. The second is a dynamic factor, i. e. the method of cutting and the behavior of cutting resistance. The last is a metallurgic factor, i. e. the knife-blade material and the heat treatment. In the previous reports, the above-mentioned dynamic factor was dealt with analytically and the theoretical results were confirmed by a series of experimental studies. This paper treats principally the first geometrical factor, and the relationship between the curvature radius of the blade and cutting resistance is analyzed theoretically. It is proved that the theoretical results are well agreed with the experimental results. And, the effect of the blade surface roughness is considered through some experiments. Consequently, it is clear that the cutting method with the blade vibrated sinusoidally is able to decrease cutting resistance.
The sensitivity analysis program is developed to point out the sensitive part of the structure, which is required for improvement of dynamic behaviours using the modal parameters obtained by experimental modal analysis. One method is to compute the necessary amount of structural modification in order to realize the shift of natural frequency specified. The other is to estimate the derivative of natural frequency or amplitude with respect to the structural change. A simple beam as well as a motor bike frame is tested to validate the effectiveness of the sensitivity analysis developed. Also the method is so extended as to take into account two natural frequencies simultaneously for improvement of dynamic behaviours of complex structures.