In a present laser interferometer system it is necessary to adjust the alignment between a laser source and a laser interferometer. The laser source is a heat source to be a disturbance in a precise length measurement, while the laser interferometer itself is large and its setting lacks flexibility. This study is performed in order to solve the practical disadvantage mentioned above, in which the small laser interferometer is linked to the laser source with an optical fiber so as to give full play to the flexibility in the case of the precise length measurement. The results of this study are shown as follows. (1) The influence of the disturbance mixing into the optical fiber can be cancelled by making differential interference signals by means of an electronic instrument. As a result, the resolution of the interferometer becomes high and the length measurement stable. (2) A small laser interferometer with an optical fiber has been developed with 10mm in measurable length and 0.05μm in resolution as a kind of contact type indicator. The length measurement error of the present interferometer is 0.13μm in 10mm. Another non-contact type laser interferometer has also been developed for vacuum.
This paper describes the development of arc discharge plasma jet chemical vapor deposition (CVD) apparatus for the high rate synthesis of diamond. Methane and hydrogen are used as source gases. In terms of generating a stabilized plasma jet, gas flow routes of the source gases are discussed. When both methane and hydrogen are supplied from cathode nozzle, the electric discharge power varies a lot from set value, and the plasma jet becomes unstable. When methane is used as an atmospheric gas and is poured into the reaction chamber, however, the stabilized plasma jet is obtained. The methane is mixed into the plasma jet, the plasma jet is sprayed onto a cool-down substrate, and a diamond film is deposited on the substrate surface. By means of this methane atmosphere technique, a diamondfilm is depositedon a molybdenum substrate at the growth rate of 930 μm/h. The crystallinity of the diamond film measures well by means of X-ray diffraction and Raman spectroscopy.
An integrated freeform shape design and manufacturing system in which collision-free tool paths can be generated directly from the designed shape has been developed. The system employs a new surface patch representation method which has shape control points and a method of connecting surface patches even if their boundaries are symmetrical along a common boundary. This system runs on an engineering workstation and has a menu-driven human interface. With this system, designers are able to represent aesthetically pleasing shapes in the computer with greater precision than previously and display them on a color graphic terminal using a variety of new display techniques so that the designed shapes can be thoroughly examined. These features together with the system's automatic tool path generation reduce leadtime by 80%, compared with conventional procedures. A camera handle designed and manufactured using this system is shown.
An optics is described through which an elliptical beam emitted from a laser diode can be shaped into a circular spot with a small diameter of 2μm. The focused beam is utilized to produce such fine patterns as gratings with ruling up to 40 lines per mm. And also for practical applications, printing and marking of characters on papers and plastics sheets can be realized with high quality on account of high power density of the focused beam.
In the 1st report, it has been shown that a newly developed piezoelectric-driven turntable moved by the “inchworm” function is capable of positioning accuracy with less than 4.8×10-7 rad (0.1 arcsec) for a range of π/2. And it also has the following advantages ; (1) operable in a vacuum environment, (2) non-magnetic material construction, (3) small heat generation, (4) compactness. However, there were some problems for practical use, such as the reliability of the piezoelectric actuator and wear of the clamping parts. In the present report, it has been shown that the developed piezoelectric-driven turntable can be used continuously for a long period of time, over 2 000 hrs, by improving the piezoelectric actuator and by appropriate clamp clearance selection.
This paper focuses on the control of systems with unknown dynamics and deals with a class of systems described by (d/dt) x=ƒ (x, t) +h (x, t) +B (x, t) u+d (t) where h (x, t) and d (t) are unknown dynamics and unexpected disturbances, respectively. Under the assumption of accesibility to all the state variables and their derivatives, Time Delay Control (TDC) has been proposed in our previous paper, based on model reference design approach. This paper first proposes the extended TDC scheme based on trajectory following design approach. The control system's stability, structure and trajectory following property is then discussed for linear-timeinvariant and single-input-single-output systems. Finally, the control performance is evaluated through experiments using a two degree-of-freedom, direct-drive robot manipulator. The theoretical and experimental results indicate that this control method shows excellent robustness properties to unknown dynamics and disturbances based on a very simple control algorithm using time delay.
Described in this paper is a ruling machine for linear scales that is controlled by a laser interferometer with simple and inexpensive electronic systems. A He-Ne two-mode laser is used as a light source of the interferometer, and the stabilization of the wavelength depends on the comparison of the light intensities of the operating longitudinal modes. Fringes produced by the interferometer are changed to a train of electric pulses that measure the displacement of the moving carriage of the interferometer with the unit of one tenth of the wavelength. The pulse train is, after passing through a gate, fed to an electronic counter which operates a flash lamp. At the gate, the periodic elimination of the pulses is done to cancel the accumulation of the errors of the pulse spaces. The interval of elimination is calculated by a computer using the measured values of atmospheric temperature and pressure, and scale blank temperature. The light from the flash lamp is thrown on a slit and the reduced image of the slit is focused on a photographic plate which is mounted on the moving carriage. The accuracy of linear scales of 200mm long made by this ruling machine is found to be better than ±0.3 μm.
This paper describes a closed loop driving method of stepping motors by using sensed back electromotive forces (emfs). It has been known that performance of stepping motors can be improved apparently by closed loop driving method. Since one of the most important advantages of stepping motors is their low cost, the necessity of encoder to detect the position of rotor prevents wide applications of the closed loop driving method. As to PM (Permanent Magnet) stepping motors including synchronous motor origin type, back emfs generated in their stator coils give us information about velocity and position of the rotors. To do the closed loop control drive without encoder, the authors developed a new method of sensing the back emfs. In this method, the back emfs can be detected by using sensing coils which are wound around the poles of stator and a pair of small transformers which are connected in series to the sensing coils. Experimental results show that the waveforms of the sensed back emfs are good enough to perform the closed loop control drive. Fundamental study of closed loop control drive is also presented.
It is important to improve the serviceability of a coordinate measuring machine from both aspects of the hardware and the software. The influence of the software on the measurement accuracy has been almost ignored. Nowadays the testing construction is quite well explored, then special attention is paid to the software. With the coordinate measuring machine, the measured points are obtained as a set of points in area. The coordinates of measured points consist of the original feature and the deviation caused by misalignment, i. e. translated deviation and angular deviation. To evaluate the form deviation accurately, it is required to best-fit the measured feature to the ideal feature. This paper gives a new method of best-fitting. This method is done to fit the datum of measured feature to that of ideal feature. It is so easy to apply to the curved surface as same as to the curved line. The method suggested in this paper is useful to introduce into the commercial coordinate measuring machine.
In the laminating process, automatic profile control of extruded film thickness in crossdirection is required for better productivity and product uniformity. The thickness profile is determined by the gap pattern of the die-lip heated at 350°C. Conventionally the correction of the gap is made by manual adjustment of the individual die bolts equipped in the side of the die. In this paper, a new method, which utilizes the mechanical elastic deformation of the lip by a pneumatic pressure control, is proposed with its construction and characteristic. Two bellows, which pressure is controlled with electro-pneumatic converter, are constructed in each zone of the die as actuators. As a result, the resolution of deformation 1.0 μm and the response time 0.4 s are obtained in heated condition. Additionally, a decoupling method for the model is proposed, in order to compensate the interactive deformation characteristic which is caused by continuum construction of the lip. Consequently, decoupling accuracy of 1% per full span and 0.6-1.0 μm resolution of deformation are obtained.
Several kinds of cam motion curves are been utilized for the high speed positioning or the contour tracing. In order to realize the same performance by servo motors, the bang-bang control or the optimum control methods are used for the positioning. This paper describes a method to obtain the same as the cam motion by applying the inverse to DC motor driving system. We clarified the conditions to be able to obtain the motor motion equivalent to the practical dwell-rise-dwell cam motion curve with continuous velocity and acceleration characteristics at start and final points. And it was assured that the velocity feedback for the motor driving system reduces the effect of deviation of the real motor parameters for the setting values of the inverse. For the motor with an inertia load, the eqivalent motor output can be obtained by use of the inverse of the system with the time constant including the load.
Properties of amorphous carbon films synthesized from methane by RF plasma CVD of capacitive coupling type are researched. The carbon films are produced under influence of sheath voltage up to 1100 V occurred on the surface of electrode connected with an RF generator. Electron diffraction, Raman spectrum, IR absorption spectrometry and XPS are employed to characterize the films. The films are transparent in the region of infrared and their refractive indexes are about 2.5 in the near infrared region. The films are amorphous state containing hydrogen. The values of optical gaps calculated from absorption spectrum of 185-2000 nm are 0.5-1.8 eV. With increasing the sheath voltage, the hydrogen contents and the optical gaps decrease and the hardness of the films increase from 300 HV to 2500 HV. It is supposed that the hard film synthesized at high sheath voltage probably has a fundamentally random network structure consisting of olefin sp2 bonding mainly, sp3 bonding and aromatic sp2 bonding in small amounts.
This paper deals with the suppresion of a jumping motion of a workpiece in the heavy duty centerless grinding of multi-diameter shafts. The geometrical accuracy, such as a roundness or straightness, of the multi-diameter shaft tends to be worse than that of the uniform diameter shaft in centerless grinding. It was appeared both analytically and experimentally that the deterioration of the accuracy was caused by the jumping motion of the workpiece which was affected by an upward friction force from the regulating wheel during centerless grinding. The analysis also specifies a stable grinding condition and makes it possible to improve the accuracy in heavy duty centerless grinding for multi-diameter shafts.
In laser processing, laser beam is converted to have an adequate energy distribution for a processing purpose. This paper describes in both calculation and experiment what energy distributions have been obtained by kaleidoscopes of rectangular pipes. Calculated without respect to interference, the ratio of longer side to length of kaleidoscopes which convert a single-mode laser beam into that of even energy distribution had a certain tendency. The calculation with respect to interference indicated that the influence of interference on energy distribution becomes intense as kaleidoscope length increases. The influence of interference on energy distribution depends on kaleidoscope length. The same kind of calculation was done for multi-mode laser beam. It had the same tendency as that for the single-mode. In experiment, acrylic burn patterns have been made by square and rectangular kaleidoscopes to verify the conversion of single-mode beam into an even energy distribution. The experimental result has been in accordance with the calculation with regard to interference.
The present paper studies the feasibility of a new method for polishing sintered silicon nitride to make a damage-and scratch-free surface. The method contains development of a polishing disk, on which the workpiece is polished under a dry condition. The polishing disk is a composite consisting of an oxide abrasive and a thermoplastic resin. Various polishing disks and polishing conditions were examined to find the optimum condition. The results may be summarized as follows : (1) Sintered Si3N4 can be polished accurately and efficiently by means of the polishing disk, especially Cr2O3 (chromium oxide) -AN (acrylonitrile) polishing disk. The rate of material removed reaches 22 μm/km·MPa (32 μm/h) and a surface roughness of 4 nmRmax can be easily obtained. (2) Surface analyses of the polished surfaces by ESCA and SIMS indicate that a certain reaction layer is formed on the Si3N4 surface during the polishing process as a result of some mechanochemical reaction between Si3N4 and Cr2O3. The efficiency of the present method is due to the fact that the polishing disk can supply the abrasives which are mechanochemically reactive on the Si3N4, into the polished surface very continuously, efficiently and uniformly.
This study clarifies the cause of waviness which is formed on the surface of superabrasive wheels after dressed or trued by a kelly driven rotary diamond dresser and shows how to dress superabrasive wheels in order to obtain preferable accuracy and sharpness. The findings include : (1) The waviness formed on the surface of superabrasive wheels causes from the cyclic variation of supporting force due to the direction change of kelly driving points. (2) Making either (the dresser radius) / (the kelly drive radius), or dressing force small, preferable dressing accuracy can be obtained. (3) The proposed method can bring such a better result as to keep the after-dressed grinding force sufficiently small.
The sharpness of cutting edge plays very important role in the performance of cutting tool, especially in precision cutting operation with single-crystalline diamond tool. Though various methods of evaluating the sharpness of cutting edge have been developed in these several decades, the measuring with the accuracy of the order of micron or less could be obtained only by the direct observation of tool through SEM, which is not convenient for practical machining operation. In this study, a relatively simple method with reasonable accuracy is proposed for evaluating cutting edge sharpness : Cutting edge is pressed against a thin wire of soft metal at right angle, and the indentation transcribed on the wire is observed. Two ways of sharpness evaluation can be used : The one is to measure the minimum load required to make a recognizable indentation, and the other is to reproduce the cutting edge cross-section from the contour of the indentation. The cutting edge with the chamfered width of about 0.1 μm can be discriminated by this method.
In previous paper a new technique for measuring protrusion height of abrasive grain was proposed to estimate the grinding performance of diamond wheel. This paper describes the truing mechanism of bond matrix type wheel focusing on lapping effect, removal of bonding material around cutting edge by isolated grains torn off from GC cup-truer, in a metal bonded diamond wheel truing. The main results obtained are as follows : (1) Lapping effect plays an important role in truing process, therefore the truing as well as dressing can be performed in the same apparatus at the same time by using the GC cup-truer. (2) The truing ratio can reach its peak value through the control of the flow of grinding fluid against outflow of isolated grains. (3) The mean protrusion height depends only on the truing conditions after an enough truing and dressing operation. (4) An increase in size of isolated GC grains promotes the lapping effect in truing process and results in the growth of the truing ratio and the mean protrusion height.