Isolation tables are effective in preventing vibration. If objects on a table move, however, the table starts vibrating at a low frequency, with a large displacement due to the force of the impact. Some equipment on an isolation table cannot be kept at a constant distance from equipment on the ground. To overcome this problem, An active vibration control mechanism based on state feedback control using 4 voice-coil motors was developed. This system could suppress the displacement of the isolation table at 100 μm even if some objects on the table moved.
During debugging logic LSIs, a period to reproduce LSI in order to change the logic design is becoming longer. To reduce the period from several weeks down to one day, an on-chip direct wiring modification system, using the focused ion beam (FIB) milling and the laser CVD, has been developed. This paper describes a precise FIB milling technique for cutting the wirings and making the via holes to the wirings of the LSI. Milling depth control by monitoring the ion induced photo-emissions and the milling strategy to overcome the surface steps of the LSI resulted in the milling depth accuracy of ±0.25μm. The system, consist of the FIB milling described in this paper and the laser CVD, has been applied to the logic modification of the LSIs of Hitachi M880 mainframe computer. Several tens of cuts, vias on an LSI chip were made by FIB, and the several jumper wirings were made by laser CVD. The average yield of modified LSI chips of 91.8% was achieved.
In usual 3D measurement of shape by using stereo image, it is necesary to solve a correspondence problem which requires rather complicated image processing and high computational cost. Recently Ando developed the differential stereo vision system in which depth information can be derived from brightness values of image without solving the exact correspondence problem. However, this method has a weak point of narrow depth range in measurement. In this paper, we propose a method to solve a narrow depth range problem and to improve the accuracy of measurement for this method. Several examples of measurement are presented to demonstrate the effectiveness of the proposed method.
In the first report we tried to apply fringe scanning technique to the grating projection system for shape analysis. But the previous system has a drawback in that the error of measurement increases in proportion to the period of a grating. This error proved to be caused by the intensity profile of a Ronchi grating in the projection optics. In order to improve this defect we propose to use a sinusoidal grating which is printed on a photographic film by modulating the beam from a laser diode. Use of this sinusoidal grating can eliminate errors caused by the Ronchi grating and enlarge the range of measurement with higher accuracy and sensitivity. And also three-dimensional coordinates are calculated absolutely with the origin in the measuring space.
In this research, the authors studied the self-similar fractal dimension of isotropic surface asperities such as lapped surface. As the self-similar fractal, we used the clusters in contour map of three-dimensional asperity profile. Fractal dimension was obtained from the perimeter length and the area of clusters which were computed by means of the newly developed diagonal-method and the mesh counting method. It was made clear that the self-similar fractal dimension was more available to assess the complexity of asperities than the self-affined fractal dimension.
Some new easy-to-use equipment for measuring quantitatively the rheological deformation characteristics of the polishing pads has been developed. The main results, using the measuring equipment, are as follows : (1) With processing time, peripheral side of the polishing pad deforms elastically more than center side, (2) The four-element rheology model showed good agreement with the experimental results, (3) A new parameter α, which is derived from the four-element model and is related to the elastic modulus, was found to be significant for the wafer flatness.
In this investigation, the output signal of the acceleration sensor attached to the axis of the grinding wheel is directly utilized and adaptively pursued by adaptive digital filter (ADF), whose parameters indicate the signal pattern. The grinding forces are dynamically measured, and discussed compared with the index calculated from the ADF parameters. The entire process of the grinding force in Al-Si alloy grinding consists of three stages of tool wear in sequence. The vibration by the accelerator and ADF distinguish these stages clearly. Thus this method is very efficient for monitoring the loading chips.
The “wide bead formation” method has been developed for butt welding of thin steel sheets whose thicknesses are less than 300μm. This method relaxes the precise butting requirement in the practical production lines. The “rippled mode” Nd : YAG laser has been also developed in order to further improve the welding characteristic of thin steel sheets compared with that using CW YAG laser. By applying this laser to the wide bead formation method, less than 150μm thick steel sheets could be butt-welded without any defects.
A spray forming technique, which can produce semi-finished products with high density and rapid solidification structure in a single operation, has been developed recently. This method is called the Osprey process. This process can control size and distribution of carbides and takes lower production cost than powder metallurgy (P/M) process owing to a single operation. In this paper the cutting performance of high-speed steel (HSS) end mill produced by Osprey process was investigated by comparison with conventional ingot metallurgy (I/M) and P/M ones. This Osprey HSS end mill exhibited superior wear resistance to I/M and P/M ones in milling tool steel (SKD 11), but some chippings and fracture appeared at the end cutting edge in milling stainless steel (SUS 304) in small feed rate.
This paper describes the phenomenon of loading on an active surface of a CBN wheel in grinding austenitic stainless steel (SUS304). The influences of bond systems, depths of cut and grinding method (up and/or down cut) on the loading of CBN wheels are examined in detail by measuring the loaded areas, wheel wears and grinding forces. The conclusions are summarized as follows; (1) The loaded area ratio (loaded area / active surface area) on the vitrified bonded CBN wheel is larger than that on the resin bonded CBN wheel, and the mean area per piece of the loading on vitrified bonded CBN wheel is about 7 times as large as that on resin bonded CBN wheel. (2) Decreasing depth of cut results in a decrease in loading. (3) The loading on vitrified bonded CBN wheel develops more rapidly than that on resin bonded CBN wheel. They are found to be dislodged if loaded areas exceed the limit area (about 0.14mm2). (4) The loading of CBN wheels in up cut grinding is less than that in down cut grinding.
Fundamental characteristics of the cutting is studied. The foil is made of steel based amorphous alloy (B : 13%, Si : 9%, Fe : bal.) with 28 μm thickness and 25 mm width. An XY table bearing the foil specimen moves at a constant speed toward X-direction under the plasma jet. Two weights placed on the both sides of cutting line fix the specimen. The nozzle diameter is 0.15 mm and 0.3 mm. The plasma gas is argon. Nitric acid diluted by ethyl alcohol etches the cut specimen to show heat affected region. Three types of dross are observed ; straight line, straight line spotted by spheres and rugged shape. The size of heat affected region ranges from 150 to 664μm on the plasma torch side of the specimen and from 156 to 823μm on the opposite side. Use of smaller arc current, greater plasma gas pressure, greater table speed and smaller nozzle-foil distance reduces the size. Dimensional analysis of four controllable parameters gives several combinations of the parameters. Under the assumption that those combinations are linearly combined, multiple linear regression by least square method shows that the size of heat affected region is well described by the linear combination of H and SQRT (I/ (Pv)) , where H, I, P and υ are nozzle-foil distance, arc current, plasma gas pressure and table speed respectively.
This paper presents a new hierarchical lattice space model and a new coordinate measuring support system with a graphic interface based on the model. The 2.5-dimensional model, named Enhanced Z-map model, has a tree structure of component patches such as a Quadtree model and its depth-ended terminal patches represented in the form of Z-map model as a set of z coordinate value of a point according to an X-Y lattice point. The model structure has a theoretical capability to represent a free-form surface by any fine patch unit. The measuring support system has functions to determine the points to be measured on a designed shape and to make a collision-free measuring path by means of the Inverse Offset method. The system configuration inclusive of a 3-dimensional coordinate measuring machine is illustrated and the procedures of supporting functions are explained too. The experimental results of model handling support the promising efficiency of memory compression and the fast processing speed compared with that in a Z-map model. Through the measuring experiments in primitive shapes, it is concluded that the operability to command instructions is improved with the use of a graphic interface based on the model.
The yield clamping force of the bolt in plastic region tightening depends on the yield condition at the threaded portion under combined load consisted of axial tension and thread torque induced by tightening, namely the interaction curve for the yield. A new estimation method for the interaction curve at the threaded portion based on the flow theory, proposed in the previous report, is superior to the traditional one based on the local yield condition ;however the proposed method has a some estimation error in comparison with the experiment. Experimental results obtained for the combined load on cylindrical test-pieces show that the estimation error is caused by idealizing the thread portion as a smooth cylinder having stress area. For the exact estimation of the interaction curve, it is recommended to idealize the thread portion as a smooth cylinder of minor diameter of thread.
There are many design problems that require the search-based problem solving method. Especially in the case that the design problem is to determine the object's structure, the trial and correction method is valid because the theoretically best algorithm is not discovered. In this paper the authors point out several characteristics of the problem class and propose the Hierarchical Backtrack Algorithm for the problems. To aid building problem solvers using the Hierarchical Backtrack Algorithm, the authors extended the PASCAL language and have developed a language called NODE which enables the automatic backtracking even when the program control moves among several procedures with different abstractions. In the latter part of this paper the design and implementation of NODE is described, and some examples are considered.
The extraction of essential features from adjustment behavior based upon the experience of skilled operators in response to a constantly changing grinding environment constitutes an important requirement with respect to the optimization of grinding conditions. Accordingly, this was attempted by means of a neural network system. The present system was developed with a view to practical utilization in production plants, which requires system characteristics robust with respect to various adverse operating environments. In the present study, a learning method was devised so as to remain effective even in the event that a portion of the learning data is lacking because of uncorrected grinding parameters or erroneous input, and the effectiveness of this method was demonstrated. Furthermore, a method was devised whereby heterogeneous data resulting from modification of specific condition parameters or erroneous input can be automatically detected by the neural network prior to learning, and the efficacy of this method was also demonstrated.
This paper describes the concept, necessity, an algorithm and topological meaning of an extended set operation in a surface-and-solid model. In this model the operations not only between two solids, but also between a solid and a surface or between two surfaces are performed. One of the most important operations in the model is an extended set operation. But the set operation including a surface can not be expressed in the form of Boolean union, difference or intersection. Hence it should not be called a set operation in itself. It is named a divide-and-join operation. It is realized by using terminal circuits, which are the boundaries of 2-dimensional cell complex. Its algorithm associates well with the theory of topology. There are three topological conditions to ensure the divide-and-join operation : (1) dividability of the two shells by an intersectional curve which has no self-intersection, (2) keepability of cell properties for each face and edge, and (3) orientability on the common terminal circuits.
This paper describes a collision avoidance problem using potential function method. The new procedure improved for avoiding obstacles, which is called alternatively searching method from both sides, is proposed. The new potential function shaped like basin, which is defined in this study, is used in the present procedure. The center of the potential function is determined by the new estimative index, that is, ε which is also defined in this study. The availability of the procedure can be proved through the computer simulation of a collision avoidance for a multi-freedom robot manipulator. The stationary problems, which result inherently from the use of potential functions, can be overcome with this procedure.