[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

To support a part decomposition activity in welded part design, a feature based decomposition of a welded part with Iterative Loop generation by Multiple Feature Recognition is proposed and implemented. After finding out all of the concave edges on a part, this method recognizes face-connect feature as Loop, C, L, Y, and i types. And, it generates edge loops or virtual loops from the recognized face-connect features. This loop identifies two candidates of part decomposition based on the extended greedy algorithm. Each loop of a face connect feature generates two face-contact features according to the decomposing directions. Defined face-contact features are of same, contain, across, and through types. This method works iteratively for recognizing all the features on the part. By comparing face-connect features and face-contact features, a welded part as before and after decomposition can be recognized.

View full abstract

The point-in-polygon test is one of the most fundamental geometric tests and appears very frequently in geometric modeling and computer graphics. Many such algorithms dealing with the polygons of the linear edges, have been discussed. However, the algorithms dealing with the polygons including the curve edges are seldom discussed in the literatures. In this paper, by using the 4 x 4 determinant method and a sign correction technique, a parity algorithm dealing with the polygons including the curve edges is proposed, and a complete program for this algorithm is presented. By classifying an area surrounded by a curve edge and its corresponding virtual edge as a plus or minus one, and determining whether the test point is in the area or not, the curve edges can be processed in the same way as the linear edges.

View full abstract

An interpolating G² clothoidal spline curve is derived from nonlinear equation system for interpolation and, boundary conditions by computer algebra system. The curve has the attractive feature for computer aided design that the curvature is piecewise linear function of the arc length and circular arcs and line segments can be considered limiting forms of clothoids. The scheme can describe an algorithm concisely and try various boundary conditions because it can manipulate symbolic expressions as well as numerical data. The scheme is more flexible than the conventional one which determines span by span. Some information is also provided for an alternative method without computer algebra system.

View full abstract

This paper deals with social structured autonomous distribeted manufacturing system that puts together dual defferent productin planning systems and productin system organically. This system, in the case of the ordinary planning phase, limits a combination of production plans by introducting a hierarchical structure into the usual planning procedure in attempt to give priority to the system efficiency. The system also executes the plan solving contradiction by Truth-Maintenace-System in a station-level, so it keeps considering the concrete situation of the level during the production process. In the case of the trouble phase that is impossibile to solve in a single level, the system adopts a cooperative planning system by using a loop structured network in order to avoid the trouble and produces such a plan to execute. These systems are connected by the blackboard which stores domain functions to start themselves, then the system accomplishes the Self-Organization according to the different phases. Finally the evaluation tests carried out in the CNC drill machine's system from the viewpoint of CPU-load in the communication and the precision in the processing.

View full abstract

In order to reduce gear noise, it is important to improve the roughness of the making tooth surface and to give proper tooth trace and profile modification. The gear honing is reasonable in view of this, but an adequate dressing is required to transfer exactly and quickly the shape of dressing gear to gear honing abrasive wheel. Therefore, in the present investigation, a new dressing method is introduced. In the new method, radial and axial feed is given at same time for an abrasive wheel in the form of internal gear. And then idle traverse feed is given. When the feed rate is 10μm/traverse, the error of the tooth is smaller than 10μm and dressing time can be decreased from 13.4minutes to 3.4minutes at the first dressing and from 1.4minutes to 0.7minutes at the regular dressing as compared with before step feed. This is a reason why the dropped out grains are discharged very well and dressing gear form are transferred very exactly and quickly. Running tests of honed gears were conducted. About 4 dB decrease in gear noise is achieved when the accurately dressed abrasive wheel is used.

View full abstract

There are great differences in ground surface integrity and residual stress between CBN and diamond wheels. In our single-grit cutting, the measured cutting forces with CBN and diamond grains were largely different. For further understanding of the difference, friction behavior in cutting is most important characteristic to be solved. So, orthogonal cutting test has been performed to measure friction angle on a carbon steel with CBN, diamond compax, and grain tools. And, the cutting test in SEM was also performed to observe chip formation. There are no differences between friction angles of CBN and diamond tools in ordinary cutting test. However, there is great difference in slow and short distance cutting test. Diamond tools showed significantly small friction angle at about first cutting of 1mm. In the cutting in SEM, the diamond compax and grain tool show a large shear angle and flow type chip, while CBN compax and grain tool show small shear angle with shear type chip. Therefore, diamond tool keeps a small friction coefficient during short cutting distance, and the phenomenon was shown in high speed single grit cutting test.

View full abstract

A deep drawing apparatus, in which piezoelectric actuators are incorporated, is designed and manufactured for ultra thin aluminium alloy sheets. In order to improve limit drawing ratio (LDR), which is the ratio of the maximum diameter of the drawable blank to the punch diameter, actuators are oscillated. By this, cyclic blank-holding pressure is applied to the blank and the blank can be easily drawn without any deffects such as wall breakage and flange wrinkle. (1) LDR is increased from 1.57 to 1.79 with oscillating frequency 200Hz. (2) For reduction in the drawing force, it would be better that the actuators are oscillated throughout the drawing process. (3) Either frequency or amplitude also increases the drawing ratio. (4) It is verified that the oscillation of the actuators contributes to the drastic reduction in coefficient of friction.

View full abstract

In this paper a formulation by which perpendicularity of motion of vertical milling machine is evaluated, is shown. By using it, an estimation method for perpendicularity of motion between X-, Y- and Z- axis based on the master block measuring is proposed. The proposed method has following characteristics : (1) the perpendicularity of motion of X-, Y- and Z- axis is estimated without interference of setting posture of cutting tool, since the geometric error components is derived from driving planes which is calculated by measured points on master block, (2) perpendicularity of motion is estimated without interference of setting errors of master block, since the geometric error components are derived by inner products of normal vectors of driving planes which are independent of coordinate system on machine tools, and (3) since the model of machine tools with geometric errors is constructed of the driving motion and the perpendicularity of motion only, it is more simple to estimate the perpendicularity of motion between X-, Y- and Z- axis.

View full abstract

The solid solution hardening is applied to the qualitative improvement of alumina materials. Titanium oxide is occluded in alumina materials by thermal diffusing addition method of which alumina sample is put into the titanium oxide powder and is heated in electric furnace. By these treatment, when the amount of titanium oxide content in the layer of the alumina oxide material is about 0.8%, the Vickers hardness number of the layer increase maximum two times as much as non-treated one. The white corundum, alumina ceramic cutting tool, alumina ceramic and single crystal Al₂O₃ (white sapphire) are drastically hardened by above methods, the static friability of the abrasive grains is increased and the friction wear of the abrasive grain on rotating cylindrical bearing steel is decreased and the wear of the cutting tool is restricted.

View full abstract

Injection molding has an advantage used in making of complicated 3dimensional products. The ceramics injection molding process is mainly composed of four stages. Namely these are the kneading of mixture, the molding process, the degreasing process and the burning process. Each process has many parameteres. To obtain the optimum condition for getting a consistently high strength of the product, an S/N analysis developed by Dr. Taguchi was adopted. The optimum condition for obtaining high strength and quality of products could be accomplished by setting seven factors and two or three levels for each factor. Bending strength depends on the degreasing rate and sintering temperatures. And hardness in product depends only on the factor of sintering temperature. As the sintering temperature rises, the bending strength and hardness of product increase to high values, which lead to a small pore inside the product. In particular, alumina ceramics characteristic is drastically improved by sintering temperature higher than 1823K.

View full abstract

A magnetic field has a variety of influence on plasma so that it is applied to plasma CVD to control the state of plasma. However, the magnetic fields that have been utilized by conventional plasma CVD are limited to that of smaller than approximately 0.2T. In this study, the superconducting magnet assisted hollow cathode plasma CVD apparatus has been developed to discuss the influence of a high magnetic field of 1T on the plasma for film preparation. The characteristics of discharge were examined under magnetic fields of up to 1T, and synthesis of carbon films was carried out with methane and hydrogen gases. The results obtained are as follows : The substrate temperature rises with increasing a magnetic field that is applied to plasma; Diamond is synthesized at methane concentration of 1.5% when high magnetic field of 1T is applied to plasma.

View full abstract

This paper describes a new machining concept in the squared corner shaping, making use of the cutting characteristics of non-rotational cutting tools and 6-axis control. Though the 5-axis control machining with conventional rotational tools makes it possible to machine sculptured surfaces efficiently and accurately, some problems still exist in the machining. For example, it is impossible to mill workpieces without round corner. This is due to the usage of rotational tools. The 6-axis control machining with a non-rotational tool allows a variety of machining possibilities. In the study, a new 6-axis CAM system for squared corner shaping was developed to remove the remaining of corner radius after rough cutting with rotational tools. The validity of the system is experimentally confirmed.

View full abstract

Diamond turning was carried out along several crystallographic directions on the (111) plane of single-crystal, copper at a depth of cut of 300nm. Subsurface damage was analysed by cross-section transmission electron microscope (TEM) method, and the plastic deformation behaviour in the turning processes examined by Molecular Dynamics (MD) analysis. Cross-section TEM observation revealed the formation of a polycrystalline structure due to fragmentation of the single-crystal structure just beneath the turned surface, and below this, the formation of multiple layers of cell structures elongated in the cutting direction. Furthermore, the crystals in the fragmented region and the cells near the surface rotated in the cutting direction regardless of the crystallographic direction. However, the depth of the subsurface damage, cell size, and the amount of crystal rotation depended strongly upon the crystallographic orientation. MD analysis revealed less damage in the [110] cutting direction, where slip deformation occurs mainly on the (111) plane parallel to the turned surface, than in any other cutting direction. In the case of the [112] cutting direction, slip deformation occurred predominantly towards the interior of the work material, and consequently, deeper damage was caused. The largest amount of crystal rotation occurred in the [112] cutting direction as effective stress release was difficult to achieve due to less slip deformation.

View full abstract

Ceramic balls are expected to become useful for tougher bearings than conventional ones. However, the conventional ball lapping method which uses a couple of flat and V-groove lapping plates, needs so long machining time. In present paper, efficient lapping method of silicon nitride balls has been proposed. In this method, it is designed that V-groove lapping plate is separated into two parts and three plates are able to rotate independently. In this paper the theoretical analysis of the ball motion mechanism for the proposed method is provided. The results obtained are as follows. (1) In the case with separated V-groove lapping plates, the spin angle θ of ball is able to be controlled by changing the revolutionary speeds of flat, outer V-groove and inner V-groove lapping plates. (2) The stock removal rate is increased with spin angle θ, because relative slide distance in the contact surface between ball and lapping plate increase with it.

View full abstract

In a series of studies on the simulation of grinding process, the 1st report made the functions and calculating procedures of the simulation clear, and the 2nd report showed the measuring method of the cutting edge distribution, that is important input parameter for the simulation. The present paper tries to verify the influence of this distribution on the finished surface roughness and the grinding force with the help of the simulation. It is made clear that the surface roughness increased and the grinding force decreased as the extent of the distribution increases. Also, it is ascertained that the standard deviation of the distribution is a useful parameter to evaluate the grinding wheel surface in order to improve the grinding operation. When a same grinding wheel is used during the finish grinding following the rough one, an optimal extent of the distribution is desirable to attain a high-rate grinding.

View full abstract

This study deals with the method of tool path generation for 5-axis control machining using the ball end-mill. The 5-axis control machining has been used for the particular shapes such as impeller, blade, rotor and groove of tire. On the other hand, it becomes known that this machining has a lot of advantages in case of application to the general shapes such as molds and dies. However, most of present CAM systems for 5-axis control machining have limitations of the functions for the tool collision, the workpiece shape and the method of machining. For that reason, there are many cases that users cannot get the desirable CL data. In regard to the above problem, we apply the 3-dimensional C-Space showing the relationship between all tool positions and postures and the existence of tool collision. The method of tool path generation devised in this study enables users to generate CL data reflecting their own machining strategy such as the continuous change of tool posture and the machining condition. The method allows an impeller to be actually milled in good machining condition without tool collision. As a result, the validity of the method is experimentally confirmed.

View full abstract

The measurement system for the 3-dimensional shape of the 360° circumference of the object is developed. The measuring method is the light section method in combination with the image processing technique. The measuring device consists of two or four pairs of CCD cameras and horizontal slit laser projectors. They are placed at vertex of a square facing to the center of the square respectively, and the infrared slit rays are projected onto the measuring object. The CCD camera captures an image of a light section line which appears on the surface of the object, and it is digitized by the computer. Its 3-dimensional position is calculated using the principle of the triangulation. The images obtained by two or four optical systems are composed, so that it is able to obtain a closed section of the object. Furthermore, the optical systems scan the measuring object in vertical direction by two linear actuators, and the 3-dimensional shape of the circumference of the object is reconstructed. The present paper deals with the measurement of several simple shape objects using two and four optical systems. From the measurement results, the relation of the number of the optical system to the measurement accuracy is evaluated.

View full abstract