A laser light scattering technique was investigated for application to non-contact roughness measurement. Roughness parameters were evaluated from the distribution of scattered light intensity by using the principle of optical Fourier transformation. This technique coincided closely with the stylus method in the range of 0.004-0.02μmRrms (0.02-0.1μmRz). Air blowing eliminates the effects of residual cutting fluid on the surface to be measured. This technique can be easily applied to on-machine measurements due to low vibration disturbance, convenient measuring distance, and simple instrumentation.
A modified stylus instrument for measuring the grinding wheel surface topography is developed and applications for a cluster of vitrified bonded wheel with aluminum oxide grain and a cluster of metal bonded diamond wheel are described. The measuring instrumentbasically consists of conventional profilometer of stylus type and precision pulse stage moving perpendicular to the scanning direction of the stylus, and is automatically controlled by 16-bit micro computer. Recorded profiles are combined within the micro computer and graphically displayed on color CRT, and moreover transmitted to host machine(ACOS1000) to form contour map. Analysing of the contour maps gives valuable informations such as three-dimensional distribution density and shape of grain cutting edges, worn area of abrasive grains, and protrusion heights of abrasive particle from matrix.
The Head Crash process during Contact Start and Stop (CS/S) operations was investigated to increase the recording density of disk storages by reducing the head flying height reliably. Friction force between head and disk, acoustic emission (AE) signal and read-out signal from head were measured during CS/S operations. Sliding surfaces were also observed. Coated disks without lubricant were used. The results of experiments are as follows. (1) Before head crash, it is found that the head take-off height decreases and the friction force between head and disk gradually increases as a results of disk asperity wear. (2) At the moment of Head Crash, it is found that wear scar appears on the disk surface, that the friction force and the AE signal increase suddenly, and that read-out signal decreases. (3) The observation of sliding surfaces through sapphire head and the increase of the friction force at the moment of head crash show that the Head Crash is triggered by the intrusion of a wear particle into the head-to-disk interface. From above, a model of head crash process during CS/S operation is derived.
A vertical X-Y stage has been developed for X-ray lithography, using synchrotron orbital radiation. Horizontally and vertically moving stages are guided by linear ball bearings and driven by D.C.motors. Stage weight is counterbalanced by a counter-weight in the back of the stage frame. Stage positionings are carried out by a closed loop control with laser interferometers. The following results have been obtained. (1) Step response varies, depending on the step distance, even if a servo loop gain is fixed to a constant value. That is, a closer destination makes the response more stable than a more distant destination. It has been confirmed by the analysis that the phenomenon is caused by the friction forces at the ball screws and guide bearings. (2) Less than ±0.03 μm positioning error and less than 1 second moving time for a 25 mm step motion have been achieved by the control system, in which the servo loop gain is increased to large values as the stage approaches the destination.
This paper describes a new method for the evaluation of geometrical deviations of the workpieces in three dimensional coordinates measurements. In this method three fundamental geometrical quantities are proposed to express the geometrical conditions, and the geometrical deviations are evaluated by the unbiased standard deviation of the measured coordinate values for these three geometrical quantities. The tolerances specified on the drawings for the workpieces are checked by introducing the new criterion to combine the tolerance and the evaluation factors of the proposed method. The sufficient number of the measuring points on the workpiece required for the processing can also be determined by monitoring the accuracy of the workpiece.
This paper presents the influence of the machining conditions : the machining time, the ion (argon) energy, the ion current density and the beam angle on the surface roughness and on the machining depth for the high chromium-high carbon steel (SKD 1). Also, the characteristic of roughness is discussed from the measurement of the surface asperities by a scanning electron microscopy and the analysis of chromium by an electron probe micro analysis. In addition, as the method to obtain a good surface roughness, Floating Method which applies the positive charge to the workpiece is tested. The results obtained are as follows : (1) The machining depth increases linearly with the time, but the surface roughness is not changed significantly at the initial stage of the machining (up to about 0.03 μm depth) and at the subsequent stage the surface roughness increases with the time. (2) The smaller the ion energy and ion current density, the lower the surface roughness becomes. And as the ion current density decreases, the surface roughness becomes independent from the ion energy. (3) Although the maximum machining depth is found at about 50 degress of the beam angle, the minimum surface roughness is found at about 70 degrees. (4) By Floating Method, the size of the workpiece can be controlled with a high level of accuracy without a change of the surface roughness. (5) The surface roughness of cromium-carbide in SKD 1 decreases only slightly.
CO2 laser was used to induce localized thermo-chemical etching of ZrO2, Al2O3 and Si3N4 in CF4gas, and the etching characteristics were investigated. The etching rate obtained in CF4 gas was several times greater than the one obtained in air. The etched hole was not accompained by surface cracks and melted materials, and the crystal grain was observed on the etched surface.
The CBN wheel has been noted for its advantageous properties of long life expectancy and exceptional grinding efficiency and accuracy. In this paper, the authors look at the CBN wheel from the viewpoint of the quality of workpieces processed by the CBN wheel to compare the work surface integrity and fatigue strength obtained by the CBN wheel with those by a conventional SA wheel. The CBN wheel can improve the quality and strength of work materials. This suggests the significant possibilities of the CBN wheel for reducing the size and improving the efficiency of products, if it replaces the conventional wheels; namely, the processing by the CBN wheel even has an impact on product design.
This paper describes the method to estimate the texture of engineering surface. First of all, the indexes which discriminate between the isotropic surface and the anisotropic surface are derived from the second and the fourth order surface spectral moments. The following two are clarified by using the indexes mentioned above.(1) The points and regions which discriminate between the isotropic surface and the anisotropic surface are determined by calculating the Mahalanobis' generalized square distance. (2) The engineering surface is divided into three regions, that is the isotropic, the quasiisotropic and the anisotropic surfaces, respectively. Moreover, two indexes which discriminate between the isotropic surface and the quasiisotropic surface are derived. It is also shown that these indexes can be calculated simply and rapidly by using three variables, that is, the mean number of peaks, the mean number of zero crossings and the centre-line average height. For example, in applications, the texture of the surface of dull-finished cold rolling steel strip is analyzed.
Several experiments were run to compare steel shot with glass shot on the characteristics of shot peened surface and surface layer. Shot peening was performed on steel (0.45%C) by an air blasting machine. The results obtained from experiments are as follows : diameter of dent, surface roughness, hardness distribution, half width and surface residual stress produced by steel shot are from 5 to 70% more than by glass shot. The maximum hardness and the depth of work hardened layer by steel shot are from 4.4 to 8.7% and from 20 to 30% more than by glass shot respectively. Surface residual stress by glass shot is from -260 to -390 MPa and by steel shot is from -350 to -420 MPa.
This paper describes a new plane magnetic abrasive finishing apparatus using a stationary type electromagnet and its finishing performance, in which a plane workpiece fixed on the repose table is machined by a high speed rotating magnetic pole moving in two dimensional directions. From the experimental results, it is found that 14 μm in machined depth of SK 4 hardened steel (HRC 63) is obtained and 10 μmRmax in surface roughness is improved to 0.3 μmRmax.
Grinding process of V-profile groove with a formed wheel is experimentally investigated, analyzing initial profile of formed wheel, wheel wear, stock removal, number of cutting edges on working wheel surface, bonding strength of a cutting edge and so on. Main results obtained in this paper are as follows : (1) Initial profile of formed wheel is different from ideal one at tip zone of V-profile. (2) The number of cutting edges increases with increasing depth from wheel surface, increasing distance from the center of wheel width and larger formed angle of wheel. (3) The bonding strength of a cutting edge increases with an increase of formed angle of wheel. (4) The ratio of wheel wear to grinding length is decided only by real cutting depth and is not affected by grinding length and different positions along wheel width. (5) The generated groove angle as compared with formed angle of wheel becomes larger with an increase of grinding length because of wheel wear.
This paper deals with the geometric error of bottom surface in end milling that depends upon the relative displacements of an end mill to a work. The results are as follows. (1) It is shown that the presented procedures are able to calculate shape errors of bottom surface machined by 4 edged square end mill. (2) Errors of bottom surface exist negative (negative means over cut) in both up and down milling. (3) The results of this analysis are almost coincident to the experimental values in the condition of 5 mm radial depth of cut. (4) In case of 10 mm radial depth of cut, both shape of errors only show a similar tendency. It is considered that inclination angles at end edge become 1.7 to 1.8 times larger than calculated values in end milling. (5) Under the experimental conditions, a returned edge cuts again about one half of bottom surface during each quarter of a revolution in down milling, but this phenomena do not occur in up milling.
The curvature of steel thin workpiece in one-pass surface grinding has been studied, using WA, CBN, and diamond wheels. The grinding experiments were conducted about annealed and hardened S50C steels, whose size was 1.5 mm thickness and 100 mm length, at depths of cut to 30 μm. Grinding force, as well as residual stress, was measured to interpret the results of curvature. A SEM micrographic study of grinding affected zone was performed.Thus, the difference in curvature or affected layer for the WA, CBN, and diamond wheels was evident. The superabrasive wheels especially diamond wheel, tend to cause a convex curvature, and a major reason for the inclination to convex curvature is considered a plastically deformed layer.
Zirconia ceramics stabilized with 3 mol% Y2O3 consist of fine tetragonal particles and they have become of major interest in view of high mechanical strength as compared with the other engineering ceramics. However, the crystal form and the mechanical properties of the said ceramics are greatly changed by the amount of Y2O3. In this paper, test pieces of 2, 2.6, 3, 4, 6 mol% Y2O3 zirconia ceramics are ground by diamond grinding wheel in order to investigate the relation between mechanical properties and grinding force which represents grindability. According to the test results, chip generation for 2-4 mol% Y2O3 zirconia ceramics is induced by plastic deformation but for 6 mol% Y2O3 by brittle fracture.
This method has been developed to handle the object of unknown weight or unknown surface condition with the most suitable grasping force, by which an object could be grasped in no slip condition nor over grasping force condition. The gripper adapted for this method is constructed by parallel two fingers : one finger is composed of vibrating roller and receiving roller, and another is constructed only by pressing roller. The vibrating roller drives the object by vibrating force and the receiving roller detects the follow-up motion of the object. The slip phenomenon is evaluated by comparing the waveform of receiving roller with that of vibrating roller, and this phenomenon is characterized by the frequency of controlled vibration and grasping force. With this gripper so arranged as mentioned above, the most suitable grasping force can be obtained through the observation of slip phenomena. By the result of experiments, it has been cleared that this method was applicable to real purposes. In the case of grasping objects that surface material is acrylic resin with surface roughness less 1 S, polyurethane rubber with hardness of HS 80-HS 90 is most effective as roller material.
The modal synthesis method for mass, stiffness or damping structural modification is so extended as to take into consideration of non-linear elements. First the experimental modal analysis is used to characterize the non-linear elements, like rubber mounts, engine mounts, etc. with respect to the frequency of external force but also to the acceleration level. Then a new method of structural modification developed can predict when the original structure is modified by non-linear elements. In addition to numerical examples, the method is applied to an actual simple structure.
This report describes how to create an offset surface between any tool shapes and machining surface to a necessary level of accuracy in 3 axis machine tool. It is able to consider that the machining surface is constituted by many elements, which are cutting points. An offset surface between the tool shape and an element is able to define as a reversed tool shape with Z-direction. Accordingly, the offset surface of the machining surface may be regarded as an envelope which is obtained by set operation of offset surfaces for those elements. In order to execute these set operations by computer, a spatial array is employed as a memorizing area of the offset surface. And also in order to save memory capacity, a quad-tree data structure is employed.
This paper describes a study on the SCARA robot motion control algorism. Robot motion is under the influence of many factors, such as inertia of arms, stiffness of robot structure, friction at joints, etc. These factors cause the error of robot motion from the input path. If we want to improve the error and make precise robot motion it is necessary to take those factors into account. In this paper, a dynamic model of the SCARA robot is introduced to the robot control algorism and the softwared servo system is employed to control the DC motor which actuates the SCARA robot arms. The robot control system is constructed as hierarchy structure based on micro computers. The dynamic calculation is executed on 16 bit computer, and the DC motor control is executed by 8 bit micro computer. As a result, the improvement of the accuracy of CP (Continuous Path) control is accomplished, and it is certified the effect of the control algorism by the experimental results in this paper.
This paper describes the concepts and the applications of the design system which is developed to carry out optimal design for the high-intensity ultrasonic system. The design system consists of an optimizing program based on a simultaneous search plan and data bases in which data sets, vibration analysis programs by the finite element method, and other programs are included. The optimal value satisfied with design specifications is determined by means of the optimizing program. In this paper, the design of a solid horn that is one in several components of the high-intensity ultrasonic system is presented for an example of applications of the design system. The solid horn with a large diameter that has been produced in the rule of trial and error up to now is developed in a short time by the generative approach in the design system. The success in the applications confirms the practicality of the design system.