It is well known that mounting conditions of machine tools affect their dynamic behavior as well as their level and static stability. Small-sized surface grinding machines are installed on the concrete floor through mounting elements and jackscrews supplied from machine builders. By the way, in horizontal spindle-reciprocating table type surface grinding machines, rocking mode vibrations are excited by the shock of the table reversal. Chatter marks due to the rocking mode vibrations are often generated on finished surface. In the present paper, special mounting elements with damping are developed for practical use. Machine weight is supported by jackscrews. Damping effect is given by compression of rubber sheets in mounting elements through inner screws in jackscrews. By applying the special mounting elements to an existing surface grinding machine, damping effects of rocking mode vibrations are investigated experimentally. By using the special mounting elements with damping, rocking mode vibrations due to the shock of the table reversal are decreased 33%. By using the special mounting elements, relative receptances between grinding wheel and work table are decreased 11%. Tuning fork mode vibrations also are decreased a little.
As for application of a diamond film for a cutting tool, diamond coating cutting tool has been proposed; however the coating cutting tool has the significant problem that the bonding force between the diamond film and the substrate is not sufficient and the diamond film peels off in the cutting. In this paper, the fabrication and the performance of a cutting tool using a thin diamond plate obtained by arc discharge plasma jet CVD has been described. Since the surface of the diamond plate prepared by the method is very rough with many grow-up crystals, the surface was planed and the cutting edge was shaped by YAG laser. Then a cutting tool was fabricated by brazing the diamond plate with tungsten carbide chip and evaluated in cutting Al-12% Si alloy. It is found that the chipping occurs at the gaps introduced at the grain boundaries which exist on the cutting edge according to the increase of cutting distance, but in the serial part of the crystal, any chipping is not observed and good wear resistance is proved. This shows that the cutting tool with good crystallinity without gaps is able to apply to the cutting for Al-12% Si alloy.
In this paper, as an element of thought models in design, the replacement operation using Prolog which is obtained through observation of design processes is discussed. The operation replaces some parts of knowledge about a machine with adaptable parts of knowledge about another machine, and generates knowledge about a new machine. Each knowledge has a common, fixed form, so the operation pays no attentions to the knowledge form. Therefore inference is driven only by the contents of knowledge. To supplement the operation, association and categorization modules based on the object-oriented method are installed. The former handles mutual associative relations of knowledge, and the latter does abstract relations. To confirm the rightness of the operation, a gearbox with one input rod and two output rod parallel to the input and another gearbox with one input rod and one output rod vertical to the input are applied. As a result, a new gearbox with one input rod and two output rods of one vertical and one parallel to the input rod is automatically inferred.
This paper describes a method for systematic checking of global dimension errors, such as deficiency and redundancy of dimensions, input-errors in dimension figures and symbols, etc. The logic for finding dimensional errors is written by using the Pascal language. Checking for deficiency and redundancy of global dimensions has been performed applying Graph Theory.
A mechanical product is an assembly of a number of parts. The positions and orientations of those parts are determined by their contacting relations. Since it is inevitable for real part's shapes to take some geometrical errors, it is an important design problem to evaluate how these geometrical errors cause what deviations in parts' positions and orientations in the assembly. This paper describes a method to calculate the contact state of plane figures, which represent part's shapes specifically with some geometrical errors. The contact state is defined as a state with globally minimum energy of a part placed in a potential field. Simulated annealing method is applied to search this globally minimum state. After the introduction of basic mathematical formulations of the problem, fundamental algorithms and implementation issues are discussed. Some simple examples are also given to show that the method can calculate a variety of contact states of parts.
The 1st report mainly presented an algorithm for applying the 4×4 Determinant Method to geometric interference problems involving parametric rational cubic Bezier curve segments. This paper describes convergence properties of determinants used in a curve subdivision process. The convergence rate of each determinant is theoretically derived. The result is that the convergence rates of determinants containing one control point as its element have order 0, those containing two have order 1, those containing three have order 3 and those containing four have order 6. The rates of convergence depend on the number of control points that are elements of a determinant, and are independent of the order of the determinant. This result is applied to find the convergence rates of geometric quantities related to a curve segment. Since geometric quantities are calculated only from determinants, the convergence rates of geometric quantities are easily derived from those of determinants.
The goal of this study is to produce a high Tc superconductive film with a wide area using the productive plasma spraying technique. As the first step of this study, the possibility of recovering the superconductive crystal and its related characteristics which has been destroyed during the plasma spraying operation is discussed. The well known superconductive powder of Bi2Sr2CaCu2Ox was used as the raw material. More specifically, the powder was first plasma sprayed onto a stainless steel substrate and followed by a CO2 laser beam irradiation together with the oxygen gas flow intended to remodify the crystal structure of the film. The resultant film was first checked with respect to its crystalline condition through the SEM observation and X-ray diffraction analysis, and then followed by the measurement of its superconductive critical temperatures of Tc (on) and Tc (end). The results showed that the laser post-treatment can recover the superconductive crystal on the plasma sprayed film and can provide a critical temperature of 62K (Tc (end)) on the film.
A problem in the grinding with a small diametric wheel by a machining center (MC) is the decrease of wheel speed. In order to solve the problem, an accelerating unit which increases the wheel speed by the traction drive mechanism is developed. In this paper, a side-cut grinding is performed with a vitrified bonded CBN wheel using the accelerating unit, and the machining error is investigated experimentally and theoretically. Main conclusions are as follows : (1) The machining error can be inferred from the model. (2) The wheel deflections by using the accelerating unit are consisted of the revolving and rotating deflections, and the latter is removed by the truing operation. (3) The increase of wheel speed by the accelerating unit has a significant effect on the increase of machining accuracy.
This paper deals with an acoustic emission signal analysis for identifying the transition from ductile to brittle groove formation in scratching fine ceramics. A series of scratching tests of representative fine ceramics with a conical diamond indenter have been conducted to investigate the characteristics of the acoustic emission signals generated in different scratching modes. Main results obtained in this paper are as follows : (1) The scratching process may be classified into following three types ; 1) ductile scratching mode in which no cracking is observed, 2) brittle scratching mode I in which the brittle cracks occur and 3) brittle scratching mode II in which extensive cracking and chipping along the grooves occur. (2) When the scratching process changes from ductile to brittle mode with an increase of scratching load, a sudden increasing in AE event count rate takes places. Therefore, the identifying of ductile/ brittle transition in scratching may be performed by using this phenomenon. (3) The AE signals generated during ductile scratching have the frequency components lower than 0.35MHz, while the AE signals during brittle scratching have high frequency components between 0.4-0.9MHz as well as the frequency components lower than 0.35MHz. Consequently, the ductile/brittle transition in scratching may be identified by recognizing the pattern of the power spectra of AE signals.
This paper deals with microcutting mechanism of an amorphous metal. Amorphous metal is isotropic and homogeneous, so that it is considered to be a simulation material in order to elucidate essential mechanism of cutting. In cutting of amorphous metal, characteristic chips which exhibit typical lamellar slip structure are formed. The purpose of this paper is to elucidate the mechanism of lamellar slip structure formation from theoretical and experimental points of view. The process of lamellar slip formation in Fe-base amorphous metal cutting is simulated by applying the rigid-plastic FEM (Finite Element Method) with considering adiabatic deformation and local temperature increase. The experiment of chip formation process is done by means of insitu SEM (Scanning Electron Microscope) observation. In the FEM analysis, local slip is generated periodically, and lamellar slip structure is formed. The simulated chip morphology including lamellar slip angle and spacing of lamellar slip and the calculated average value of specific cutting force are in good agreement with the experimental results.
Following a proposal of the new convex spherical finishing method using lip type tool, this paper describes the relation between the position errors and the accuracy of the spherical shapes on end of small diameter glass rods. The position errors between the glass rod and the lip type tool axis bring two kinds of effects upon the shapes on them. The position error caused by parallel slide of the glass rod axis toward the lip type tool axis on the plane including the both axes changes only the value of spherical radius, and its rate depends on the top angle of the tool. On the other hand, the position error caused by normal slide of the glass rod axis to the plane deforms the spherical shapes to the aspherical shapes. The expressions of these aspherical shapes are formulated, and the correlative equations between the position error values and the counts of interference fringes of these shapes are also made out. The experiments are performed for optical small diameter glass rod works (φ2.0×L110mm) using lip type grinding tool filled up with 7μm diamonds. The experimental results are that when the position error value ΔZ is 2.5μm toward the normal direction, the spherical shape deforms to aspherical shape having an apical umbilical point at a center of the surface of revolution, and about four peaces of interference fringe appear. Both of them are almost in agreement with the calculated results on the experiments.
Nowadays numerous industrial robots are increasingly applied to complicated and precise operations such as assembly. So precise estimation of performance characteristics of a robot, such as positioning accuracy, orientating accuracy, path accuracy and soon, is being necessary for both users and manufacturers of robots. However it is difficult to measure the position and orientation of a robot moving in wide 3-D (three dimensional) space without contact, in real time and with high accuracy. In this paper a system using ultrasonic waves is proposed. The principle is a triangulation using distances between transmitters attached to a robot arm and receivers placed around the work space of the robot. An electric spark which works as a non-directional point source of ultrasound is used as a transmitter. This system is simple and economical compared with that using laser beams or LED. Moreover the accuracy is good because it measures distances directly from the time-of-flight of an ultrasonic pulse. In this first report the principle and a trial manufacture are dealt with.
Structure function of engineering surface irregularities is classified by Fractal dimension to the three phases which are waviriess, surface roughness and smaller irregularities than surface roughness. This report presents that surface roughness has Fractal-like property and that smaller irregularities than roughness are made of simple form asperities which do not have any irregularities on their slopes. Furthermore it is made clear that this smallest irregularities are Fractal-like elements of surface roughness.
This study deals with reducing of transmissive vibration force by the interference method. The improved mechanism of the machine is constituted as two degrees of freedom vibration system. Assuming to eliminate a coupling spring, natural frequencies of two mass-spring systems are tuned to the same value each other. Vibrations of two bodies in the mechanical system are always held out of phase independently of exciting frequency. Then a fundamental resonance disappears and the secondary resonance becomes the only resonance, because the system is divided into a pair of mass-spring system by a node in the coupling spring to be regarded as a common fixed end. The new type vibratory feeder for automatic parts assembly system has developed as one of application of the vibration reduction method.
The surface profile is obtained by projecting grating pattern on the object surface and observing the deformed pattern at the direction different from the projection. Phase-shifting technique is generally used for measuring height distribution at all the picture elements over the object image. In this method, if the slope of the object surface is so steep that the phase change between any adjacent pixels is larger than, the integer fringe orders become ambiguous and the profile cannot be determined. In this paper, a new method for measuring steep slopes is proposed and verified by experiments. In the method, two gratings with different effective pitches P1 and P2 are projected on the object. By subtracting the two calculated heights for the two pitches, the integer fringe orders are obtained. Simulations clarified the effect of intensity quantization on the counting error of fringe order.
A study is presented of a high precision measuring method of flat form errors by combining two-orientation method and radial shift method, when a laser interferometer is applied. The method can remove the measuring errors due to the form errors of the reference surface. In the two-orientation method, two sets of data measured before and after a rotation of the specimen are translated from orthogonal array into polar coordinates expressions. Then the differences between the two are Fourier transformed and the true form errors along the concentric circles are determined by phase operation. In the radial shift method, the differences between two sets of data measured before and after a radial shift are calculated along the radius. Then the true radial straightness errors are determined through polynomial approximation and least square method. Finally the true flat form errors can be obtained by combining both results. It has been ascertained by experiments that the measuring errors are within several nanometers which is comparable with the repeatability of the interferometer.
In this paper, the generation behaviour of the exciting force in impulse response testing is observed theoretically and experimentally taking the dynamic characteristics of mechanical structures into consideration. And influences of structural parameters such as mass, damping, and stiffness on the exciting force are made clear. And then the effective control method of the hammer velocity is proposed from the viewpoint of the practical transient excitation. The following results are found. The maximum force, the duration, and the impulse of the exciting force are mainly influenced by the stiffness and the mass of vibratory systems, and the system damping has smaller effects on them. The impulse is affected mostly by the structural stiffness and the mass, and it is enlarged by the increase in the stiffness and reduced by the decrease in the mass. The hammer velocity is the most important and effective factor in controlling the impulse, and the impulse can be kept constant by adjusting it without change of other hammer parameters. By applying the Hertz's contact theory in the excitation process, it is proved that the analysis proposed can be effective for considering the setup parameters of exciting conditions with no reliances on sensuous and empirical knowledge of experimenters.
Fault diagnostic technique of the industrial robot will be greatly needed in the various automatic systems. When the robot moves irregularly, it must be generally done that the movement of robot should be stopped as soon as possible as one of the safety factor. In this study, one fault diagnostic technique of robot motion is proposed to resolve the above mentioned problem. It is the proposed technique in this study that the small vibration of robot arm that is caused by the operation of robot is always been monitoring and the decision whether the robot moves regularly or irregularly is done statistically compared with the regular small vibration of robot arm. Due to the experimental results of fault diagnosis of robot motion, it is found that χ2 inference technique about the amplitude distribution of small vibration is good fault diagnostic technique of robot motion.