This work was carried out to develop a precision dual positioning apparatus, consisting of friction drive and piezoelectric actuator. In this apparatus, the piezoelectric actuator, designed for fine positioning, is mounted on top of the friction drive slide, designed for coarse positioning. Individual loops are closed by laser interferometer systems, with 2.5 nm resolution. The friction drive and piezoelectric actuator move together, using a kind of inchworm movement method, which the authors have proposed. The method makes it possible for this positioning system to have an over 100 mm stroke with 2.5 nm resolution and no backlash. In addition, this dual positioning system, using the inchworm movement method, is also valid for assuring a tool's continuous path (CP) control, with nanometer order accuracies, in forming three-dimensional surfaces, using a precision machine (precision lathe).
This paper describes a micro cutting system to cut a uniform and submicrometer deep groove over a whole desk. A micro cutting device consisting of a pair of parallel springs and a piezo-electric actuator has been developed. The device is designed using the finite element method and has a good dynamic response up to 2kHz with a stiffness of 80 N/μm and an infeed resolution of 5nm. A micro cutting system with the device is proposed which can detect the initial contact between the tool and the cutting surface with an accuracy of ±0.1μm. Submicrometer cutting where the depth of cut is set with reference to the initial contact position, was accomplished.
For the purpose of improving the productivity of manufacturing molds and dies, a real time numerical control system has been developed in this study. It can accept the geometrical data of the three dimensional parts and generate tool path for rough cutting, semi-finishing and finishing automatically. In order to realize complete processing of the offset surface generation and the cutter collision check for any type of cutting tool, the Inverse Offset Method is incorporated into the system. The Tool Path Tracking Method developed by a preceding study of the authors is modified slightly to apply the parallel processing and generate tool path using the data of discrete points representing the offset surface. The iterative method is not used in point of each processing of the Inverse Offset Method and the Tool Path Tracking Method, which will be main factor to improve the reliance and enhance the processing speed of the system. Simulated results of tool path and real time cutting tests show that new type CNC controller implemented the function of real time tool path generation is feasible.
The purpose of this study is to construct an expert system for mold polishing using knowledge of skilled machinists and to verify the feasibility of the expert system with experiments. In the first report of this theme, these knowledge have been acquired and analyzed quantitatively. In this expert system, production rule is used to express the knowledges. If the roughnesses and depth of scratches of preworked surface and required one are given, then order of tools to be used and number of each polishing stroke are obtained as solution. Inference engine is forward inference of production rule and the criterion of evaluation is minimum number of total polishing strokes. According to the solution of this expert system, milled surface of S 55 C steel are polished with selected tools and the number of polishing strokes. Consequently, the expert system is confirmed to be useful for determination of polishing process.
In order to realize a new method of powder particle beam machining, a fundamental approach to obtain a dense beam of powder particles was made with an Einzel lens designed from electron optical theories. The mechanism of forming well-focused beam is theoretically analyzed by a graphical method based on the electron optics, so that each of the particle trajectory and density distribution is represented as a function of the optical values and dimension of the lens. The validity of the theoretical analysis was proved by comparing the calculated density distribution with the measured beam spot on target material. Furthermore it became clear that the off-axis trajectories affected by spherical aberration remarkably contribute to the beam-spot formation and that the average beam density in the focused spot can be increased by about thirty times that of non-focused beam.
This paper deals with theoretical and experimental analyses of orthogonal micro cutting process of copper. A method is proposed based on the rigid-plastic FEM (Finite Element Method) to simulate the orthogonal micro cutting process of copper taking into consideration of the roundness of the tool edge. Orthogonal micro cutting experiments of oxygen free copper are carried out within a SEM (Scanning Electron Microscope) employing tools with rounded tool edges. The machinability in the orthogonal micro cutting is discussed from the viewpoints of the chip formation, the cutting forces and the distribution of the stress in the workpiece. Emphasis is given in particular to the effect of the roundness of the tool edge on the micro cutting process of copper.
Up to the present, aluminum alloy reinforced by short fibers of alumina is used as the parts of automobile because this material has wear-resistant. In the future, it is necessary to generate higher precision surface in order to apply to other uses. The purpose of this study is to experimentally generate higher precision surface of this material by means of diamond cutting with an ultra precision lathe. In order to attain the purpose, the first step was to quantitatively estimate surface roughness and defect from three dimensional measurement of the finished surface. After that, the optimum working conditions were selected. The results obtained from this study are as follows : The pore was generated by falling off of fiber, and the swell of matrix around fiber was observed in the finished surface. If tool geometry and another conditions were selected properly, better results were found to be obtained in surface defects, tool wear, and straightness of finished surface.
In precision surface grinding, it is difficult to suppress chatter mark completely, because of unavoidable minute change in surface geometry of grinding wheel caused by wear, fracture and breakdown of abrasive grains and occurrence of minute wheel unbalance resulting from many causes. Moreover, when using horizontal-spindle hydraulic-reciprocating-table type surface grinding machines, the change of hydraulic oil temperature causes the variation of the speed and stroke of the work table and consequently the variation of chatter mark patterns. In this research, firstly, to clarify the implication of the change of chatter mark pattern in machining accuracy, the smoothing action on work surface due to geometrical multiple interference effect of a grinding wheel upon a workpiece has been discussed through numerical simulation. Secondly, to improve the machining accuracy by utilizing this effect, a device for controlling the table speed and stroke has been developed from the standpoint of practical use and its effectiveness has been investigated experimentally.
We study here the effects on grinding ratio, tangential grinding force and surface roughness of emulsion grinding fluid supplied by a MAKITSUKE NOZZLE. As the distribution of the size of oil particles grows, the grinding ability increases. Effects of chlorinated or sulfurized additives are examined. An emulsion grinding fluid containing effective chlorinated and sulfurized additives (MGF-3) is developed. It is clarified that MGF-3 has a high grinding ability and high stock removal rates.
GFRP, because of their superior strength-to-weight and stiffness-to-weight ratio, are used increasingly in high-performance applications. But the users of this material have faced a difficulty to machine them. The major trouble in cutting GFRP is the decreased tool-life, the inferior surface quality and others. The purpose of this study is to clarify the wear characteristic of the tool, to find the suitable cutting condition in trimming GFRP with endmill. The main results obtained are as follows : (1) The shape of cutting tool caused by wear has some variation with type of GFRP. And the tool life is affected considerably by fiber structure in each layer rather than the whole fiber content. (2) Machined surface in cutting GFRP depend on engage angle to fiber direction mainly. (3) Oscillate cutting in which endmill is moved up and down has some effects on improving tool life.
Flow properties and friction characteristics have been measured on various steels : a plain carbon steel, resulphurized steels with different size of MnS particles and leaded resulphurized steel. On the basis of the empirical equations, a simulation analysis has been conducted to examine effects of the free-machining additives on the cutting mechanism. At a relatively low speed of 100 m/min, the leaded resulphurized steel followed by the resulphurized steel with smaller MnS inclusions shows the best machinability, such as decreases in chip thickness, cutting forces and tool temperature, which are diminished with increasing cutting speed. These changes mainly arise from the difference in friction characteristics since the flow properties are almost the same among the four steels. The simulation results are found to be in good accordance with experiments.
This paper describes the effects of laser heating on the electroless plating process. In the experiment, a focused YAG laser beam and a copper electroless plating solution were used. In the analysis, the temperature distribution was calculated by the solution of the heat conduction equation. In the first stage on the laser-induced plating, the rapid heating effect induces the nucleation reaction. In the second stage, the partially heating effect enhances the reduction reaction based on the micro-convection, which depends on the sharp temperature profile.
This paper discusses a new concept of wafer stage system for step and repeat type aligner. High rigidity of stage mechanism and high gain of stage control system are required to improve accuracy and acting time of stage positioning. But as wafer size becomes large and the mass of the stage system increases, it becomes difficult to design stage mechanism of high rigidity. In this study, a new type stage, in which a fine stage is separated from a coarse stage, is proposed to reduce the mass of movable part. An experimental apparatus is made to examine the effect of this philosophy. Positioning is carried out with a closed-loop control system using laser measurement system. The experimental results indicate that this stage system is capable of fine positioning with an error less than 6.4 nm and coarse positioning with an acting time 200 ms for a 15 mm step.
An optical non-contacting displacement sensor is introduced for in-process measurements, three dimensional coordinate measuring machines and robots. In the senor, (1) a ramp-shaped frequency-modulated laser diode is used as a light source, (2) a single-mode fiber coupler and a selfoc lens are used to compose a common-pass interferometer, and (3) the displacement of the work surface is detected from the phase change of heterodyne beat signal. The probe of the sensor is simply the selfoc lens itself whose diameter is only 3mm. The sensor has excellent characteristics; (1) the sensitivity, working range and linearity are almost constant for different surface materials and roughnesses, (2) the working range is 26 mm with a resolution of 20 nm, and (3) it is not crucial whether the work surface is exactly perpendicular to the probe or not.
The measurement errors of a CNC coordinate measuring machine is known to depend on machine adjustment carried out in the final assembling process. The purpose of this study is not only to identify the factors in the adjustment procedure that have large effect on accuracy of measurement, but also thereby to improve the efficiency and the performance of adjustment. Experiment was performed on the direct product of orthogonal arrays L36 and L27 which were assigned adjustment and measurement conditions, respectively. Analyses were carried out from the viewpoints of error magnitude and dispersion. The rigidity of the air bearing of Y axis was found to have the largest effects on the dispersion, but not on the magnitude. The perpendicularity in various planes are found to have the second largest contribution to both the magnitude and the dispersion. Efficiency of the adjustment procedure was improved significantly on the basis of these results.
Reversal method is a well known method for roundness measurement. Although it is simple, it requires the reversion of the workpiece relative to the rotary mechanism. Such a reversion is impossible in some situations, for example, when the axis of the rotary mechanism itself is to be measured. In order to solve this problem, this paper proposes a new method called Improved Reversal Method (IRM), in which the reversion of the workpiece becomes unnecessary. In the IRM, an auxiliary reference (a cylindrical master) is set on a workpiece. The workpiece and the auxiliary reference are rotated and measured simultaneously. The auxiliary reference is then reversed and the measurement is repeated. By processing results of the first and the second measurements, not only roundness errors of the workpiece and the auxiliary reference, but also radial motion errors of the workpiece axis before and after the reversion can also be obtained. The effectiveness of the IRM is demonstrated by experiments in which a measurement reproducibility better than 17nm and repeatability better than 31nm were achieved.
The coordinates deviation of a CMM (three coordinates measuring machine) is estimated as error vectors within 1 μm of uncertainty, by using 2 laser tracking stations. The error vectors were estimated as the differences between coordinates data of the instrument and estimated positions by the least square method. The calibration or correcting method developed through grasping error vectors at overall working area of an instrument shall give a CMM system with computer to decrease measuring errors. The availability of this method was only verified on the plane coordinates, because laser tracking stations with one rotate axis was used for this experiment. It is easy to extend the plane coordinates to three coordinates if laser tracking stations with two axes for the three coordinates system are used.
This study analytically deals with the actuating device like a flexible finger for feeding of thin sheets and handling of minute parts. The actuator is a hooked cantilever, which consists of two bimorph members rigidly connected each other in a series. The members are applied independent excitation voltages. Then the tool attached at free end is able to move two dimensionally, vertical and horizontal directions to a feed plane by deflection of the members in different direction. The present paper discusses on quasi-static behavior of the device. When sum of an attaching angle of fixed end and an angle between axis lines in the combination of two piezo members is closer to 180°, that is, the tool is almost kept in a vertical position, actuating force and displacement of the tool have a maximum, respectively.