An interference effect of a grating interferometer consisting of three transmission gratings in tandem irradiated incoherently is analysed theoretically by consideration of optical transfer function (OTF). The system OTF has been calculated by varying the normalized image distance, the ratio of grating period to slit width and the ratio of image distance to object distance. Several calculations have been carried out to find the good conditions for a grating atom interferometer. It is revealed that when the ratio of grating period to slit width increases, the value of OTF increases. Moreover, the ratio of image distance to object distance has no influence on the magnitude of OTF, but the length of the interferometer depends on the ratio. The image intensity has been calculated by Fourier series expantion. The results show that image with high contrast is formed if the period of object grating is double of that of pupil grating. The OTF theory has turned out to be useful for designing a grating interferometer.
To couple optical devices such as optical fibers or planar waveguides efficiently, the authors have proposed a new method of optical-axis alignment for coupling fibers by using the reflectivity difference between the core and cladding, without measuring the transmitted optical power. In this report, they have described the principle of their method and show, by experiments using single-mode optical fibers, that one single-mode fiber can be coupled to another single-mode fiber. The experimental results have shown the feasibility of their method that their method can be used to couple cleaved single-mode fibers and to couple fibers with slant ends, and to align two couplings in parallel. The resulting optical power was shown to be sufficient to initiate fine-alignment.
This paper presents an optimum condition to obtain the root-mean-square slope of the profile Δq, and an application method of Gaussian low-pass digital filter to eliminate high-frequency noises. The main conclusions are as follows. (1) The range of convolution integral is 0.9 times cut-off wavelength λs and the space of data is λs/12. (2) It is appropriate that Δq is calculated by means of the seven-point method of numerical difference according to Lagrange's interpolation. (3) We make clear the effect of fluctuation of sampling interval on Δq. (4) The low-pass filter affects little the roughness parameters in the direction of profile height but largely those in the direction of profile length.
A new optical measuring method which can be applied to in-process measurement of micro-machined surface profile with an accuracy of submicrometer order is proposed. The principle of measurement is based on the optical Fourier transform and phase retrieval method. The phase information is retrieved by applying logarithmic Hilbert transform and Fourier series expansion to two Fraunhofer diffraction intensities, which are related to square of the modulus of Fourier transform of object field, with and without an exponential filter at the object plane. In order to verify the validity of the proposed method, first, computer simulations of reconstruction of the fine groove models are performed. Second, the inverse scattering phase measuring system consisting of Fourier transform optical arrangement with an exponential filter is developed. And the measurements of the fine triangular groove with the pitch of 4.75μ m and the height of 0.2μ m which is fabricated by ultra precision diamond turning are carried out. It is found that the proposed measurement method is effective for reconstructing the profile of a submicrometer size workpiece without scanning probe and stylus.
In coordinate metrology and vectorial tolerancing, associated features (Gaussian substitute features) are normally calculated from measured data sets of CMM (Coordinate Measuring Machine). Then, the associated features are compared with the nominal features which are indicated on the drawings. The associated features are calculated using least squares method and expressed without geometrical deviations. The novel data processing method for geometrical form with geometrical deviations has been developed. In the method, every geometrical form can be processed with its geometrical deviation which is calculated from the measured data set using Gaussian (least squares) method as a standard variations σ. Using the method, the geometrical deviations of 2-D geometrical features can be calculated. This directly implies that these values and these calculations can be used for the evaluations of measurement uncertainties and a computational tolerancing.
This paper describes autonomous operation planning system that can plan the cutting operations rapidly with genetic algorithm. An operation that has two processes, a rough process and a finish one, is examined to determine cutting conditions with evaluating machining cost and tardiness time. Adaptive prediction in the planning allows us to estimate machining cost and processing time with predicting cutting force, tool wear, and surface roughness. Penalty for tardiness, then, can be estimated using the processing time. The optimum combination of cutting conditions in two processes can be searched in the following way : (1) For giving initial conditions in the optimization, genetic algorithm finds the optimum cutting conditions independently in each process. (2) Initial conditions are set, around the conditions found to start the search near the optimum conditions for all process. (3) Genetic algorithm finds the optimum conditions to minimize machining cost including the penalty. It is, then, shown that the planning with genetic algorithm can give us the optimum cutting operation rapidly according to cycle time.
A proper characterization of the topography of grinding wheel surfaces is very important for understanding grinding performances. The wheel topography which is comprised of the spatial distribution of abrasive grains over the wheel surface and their morphology suggests a fractal structure. Then fractal geometry which can produce a numerical description of an indescribably rugged surface was applied to characterize such a geometrical structure. It has quantitatively been evidenced by measured fractal dimensions that both the complexity of morphology of cutting edges and the irregularity of their distribution increase through dressing process. However, it has been indicated that the complexity of cutting edge's morphology decreases by wheel wears, such as attritious wear and grain fracture.
A new biochemical removal process of biodegradable plastics has been developed. Plastics have many advantages compared with the metals on specific strength, specific weight, high corrosion resistance and so on, thereby a number of products are made from plastics. Plastic products and parts have spread all over the world, however, home and industrial plastic waste cannot be degraded at all. Hence, disposals of the plastic waste have recently become an annoying problem in order to maintain clean environment of the earth. Some biodegradable plastics have been developed corresponding to demands of waste-free plastic products. Biodegradable plastics can be degraded by microorganism or enzyme by means of cutting down the molecular chains. From machining point of view, this degradation appears to be a kind of microremoval process at molecular chain size, biodegradable plastics therefore can be biochemically micromachined by microorganisms or enzyme. This paper deals with biochemical machining of biodegradable plastics using enzyme. Biochemical machining experimental results showed that Biopol pellets and plates could be biochemically machined by mold, filamentous fungus. Temperature and pH effects on the removal rates have been determined.
Atomic-level cutting process is simulated by using a combined molecular dynamics (MD) method and rigidplastic finite element method (RPFEM). The algorithm for combining the MD and RPFEM is developed based on the displacement of atoms and rigid-plastic body. MD solutioin of the atomic displacements and the nodal displacements obtained by RPFEM analysis are combined in the vicinity of the tool edge, so that atomic-level cutting process is simulated. The transition process in the beginning of the cutting of a single crystal copper due to the diamond tool advancement is simulated. In this calculation, the atomic behavior in the shear zone near the tool edge and the plastic flow of the chip can be simultaneously analyzed. The proposed MD-RPFEM hybrid simulation is considered to be effective to analyze the atomic-order cutting process.
Axial hole deviation in deep hole drilling results in degradation of the quality and a decrease in the yield rate of products. The new laser-guided BTA tool has been developed to prevent the hole deviation. The tool can bore deeper holes than 500 mm with high accuracies. The tool was guided by an argon laser and piezoelectric translators for detecting and changing its attitude, respectively. Two kinds of experiments were carried out to examine the performance of this tool in detail and to determine its practical application, using a duralumin (A2017-T4) workpiece with a prebored 108 mm diameter hole. The first experiment was to examine whether the tool can be precisely manipulated by a computer. The second was to examine whether the tool can be guided toward the target. The target was located in front of the tool and moved from side to side, perpendicular to the rotational axis of a spindle. The experiment was performed with a rotating tool-stationary workpiece system. Rotational speed was 270 rpm and feed was 0.125 mm/rev. Tool diameter was 110 mm. The results show that the tool can turn its course to correct hole deviation.
In many manufacturing systems, the role of skilled operators has been reduced down together with the progress of automatization technology. In some industries, however, the superiority of the manual operation to fully-automated system is reappraised recently. It is difficult to eliminate manual operations entirely from all manufacturing processes, because sophisticated sensitivity of human operators is indispensable in some kind of process. In this case, the characteristics of the sensitivity should be investigated in detail for utilizing it efficiently. In this research. the authors aim at clarification of manual machine tool operation from the viewpoint of human engineering. Particularly, minute grooving operation with a lathe. in which operational accuracy and speed are dependent upon the perception of the operator, is discussed in the present paper. Firstly, an experimental apparatus “virtual lathe” is newly developed so that analyses may be done under simplified conditions. By using it, the operator gets cutting force, motion of cutting tool, cutting sound, etc. through his own perceptive organs as if he uses an actual machine. Applying the apparatus to the minute grooving, secondly, the skill learning process of six testees is investigated. Obtained conclusions are summarized as follows : The similarity between actual operation and virtual lathe operation is confirmed. The force sensory feedback is effective in improvement of learning speed. The skill acquired relevant to operating accuracy is difficult to lose compared with that relevant to operating speed.
Machining condition of a material is usually determined by considering its classification and hardness. To choose optimal condition, it is necessary to take its chemical composition into account. Chemical components have big influences to machinability of a material. However, correlation between chemical composition and machinability is not clear. The objective of this research is to establish a method for estimating machinability of a material and for choosing optimal machining conditions on the basis of chemical composition and mechanical properties. This article describes the results of multiple regression analysis on samples of die-steel and super alloy, in which machinability is used as a criterion variable and chemical components and hardness are used as explanatory variables. By the analyses of groups of samples, classified by the differences of chemical composition, 2 or 3 chemical components and hardness have been proved to have definite correlation with machinability. Availability of FFS (Fuzzy Filtered Synapse) network in the estimation of machinability is also examined.
An optical telemetering system which measures the temperature of rotating spindle is proposed. The system uses an optical data transmission technique to realize high-speed precise telemetering, which is free from noises due to a slip ring and an electric magnetic field. Moreover, it can measure the temperatures at different eight positions and the data, which are the measuring channel number and the temperature measured at the channel, are transmitted with only two pairs of infrared LED and photo-diode under arbitrary rotational spindle speed by using an asynchronous serial data transmission. An experimental system is made and several fundamental characteristics are examined. The time required for the data transmission is 48 μs a channel. It is experimentally confirmed that the accuracy in temperature measurement is ±0.2°C.
The machining damage done to the surface of ceramics by superfinishing is investigated experimentally. The bending strength of the ceramics finished is measured. The influence of the grain size and the finishing conditions on the bending strength is investigated. The work materials used are alumina Al2O3 sintered under atmospheric pressure and Mn-Zn ferrite sintered under HIP. The results are as follows. Superfinishing is very effective in removing the machining damage and improving the bending strength of the ground ceramic. Using a finer grain under lower stone pressure makes it possible to remove the work material as chips by plastic deformation and decrease the machining damage on the surface. It is estimated that the bending strength is influenced by the median cracks which are formed under the bottom of the groove by active grains. It is possible to increase the bending strength, using the stone under the condition of glazing.
When machining a workpiece with a ball-end mill at high feed speed, the finished surface roughness is greatly affected by the tilting angle of the tool axis. In order to obtain fine surface roughness, this paper proposes concepts of optimum and critical tilting 'angles for unidirectional and bidirectional feed machining, respectively. The computer simulation demonstrates that the surface roughness can be dramatically improved by tilting the tool axis with an optimum tilting angle in the unidirectional feed machining and with a critical tilting angle in the bidirectional feed machining, as compared with the traditional three-axis machining. Furthermore, the surface roughness can also be improved by employing the unidirectional feed machining comprising with the bidirectional feed. To estimate desirable tilting angle under any machining condition, a neural network is used for learning the relationship between the machining conditions and the tilting angles. The effectiveness of the network for both optimum and critical tilting angles is also proved.
In a nitride ceramic thin film, the fabrication of AIN and ZrN thin films was attempted by an Ar ion beam sputtering method. The ZrN thin film was fabricated by sputtering a Zr target in a nitrogen atmosphere, while the Al and nitrogen reaction required the bombardment of nitrogen ions. Fabrication for both was based on the reaction between nitrogen and Al or Zr atoms. Accordingly, clarifying the difference in reactions between nitrogen and Al or Zr required a theoretical analysis by an ab initio molecular orbital method. An ab initio molecular orbital method was used to analyze the reaction of nitrogen molecules to Al atoms or to Zr atoms. According to the method, the bond order of nitrogen atoms may decrease when they are approached by Zr atoms, while the bond order may change little when the nitrogen atoms are approached by Al atoms. The results of calculations indicated that nitrogen molecules react to Zr atoms more actively than to Al atoms.