Laser Rheology Processing is the process which can produce near net shape parts by irradiating laser onto string shape material which is composed of powder and liquid binder and extruded onto the table or part processed before. Liquid binder is evaporated instantly after laser is irradiated. This report deals with the fundamental research on thermal phenomena in process. It is found that in case of Fe powder the surface layer of the processed part is oxidized under the atmosphere and most heat is hindered to flow through it. So it is recommended that the process is done without the existence of O₂. It is also found that the process is better done in a little lower range of temperature from the melting point of the powder material.

View full abstract

This paper deal with the characteristics of acoustic emission (AE) signal which generated by friction and wear. The experiments carried out changed the finishing method of plate specimens for produce a typical wear mode. As experimental results, the correlation was observed between the friction and wear phenomena and the amplitude of AE signal or the AE frequency spectrum. The summary of results is shown below. In the abrasive wear mode, wear rate is relatively high, but the AE count rate and the amplitude of AE signal are small. In the adhesive wear mode, wear rate is small, but the amplitude of AE signal is larger. In the abrasive wear and adhesive wear mode, AE signal in the 1-1.5MHz frequency spectrum band was observed.

View full abstract

This paper describes experimental studies on three dimensional cutting by sidewise movement of cutting edge (called drift cutting). Drift cutting is very similar to oblique cutting in respect of geometrical relations between work material and cutting tool. Comparison between these two cutting methods shows smaller cutting resistance and better surface finish in drift cutting. The reason is that small amount of lubricant such as absorbed molecules or cutting fluid on the tool face may be brought into tool-chip interface by sidewise movement of cutting edge. Shapes of chips in drift cutting sometimes show triangular crosssection because of difference of friction at each point on the tool face. Frictional force caused by the sidewise movement of cutting edge promotes the deformation of chips.

View full abstract

This paper deals with a formation mechanism of the entrance burr by using an experimental method and a finite element method. The relation between burr size and grinding condition, -such as work speed, depth of cut, grinding direction, number of grinding passes and edge angle, -is investigated. In the calculation, grinding temperature and cutting force for a cutting point are considered. Therefore, the mechanical and thermal strain distribution and plastic deformation near the workpiece end are derived. The main results obtained are as follows : (1) The entrance burr has a burr-root thickness of 40-60μm and a burr height of 3-5μm. The entrance burr is smaller than exit burr in size. (2) Deformation of the corner shape is produced mainly by the grinding force. (3) The grinding temperature causes a plastic deformation on a workpiece-surface layer, however it is not enough to produce an entrance burr.

View full abstract

The finishing pressure has an important effect on the removal rate in the process of Magnetic Float Polishing. In this paper the pressure was measured using a dynamometer and the relationship between the pressure and the finishing characteristics was analyzed. The results were summarized as follows. (1) The magnetic field lowered the transient high pressure at the beginning of the polishing, and kept the finishing pressure constant during all polishing time. (2) The finishing pressure influenced to the finishing characteristics strongly, and the characteristics were elevated by the higher pressure. (3) The changes of the finishing characteristics under the conditions of the parameters such as the volumetric concentration ratio of abrasives, the vertical polishing position, the grain size and the work speed could be explained by the changes of the strength of magnetic field gradient or the volume of effective abrasives under the workpiece.

View full abstract

Cooling and lubricating actions of two components mixture type grinding fluids, which contain machine oil and surface active agent, have quantitatively been measured as the cooling and lubricating moduli. Experimental grinding results are compared with grinding results predicted by the model of multipliable effects for cooling and lubricating actions of grinding fluids. Main conclusions are as follows : (1) For two components mixture type grinding fluids, cooling action decreases and lubricating action increases as mixture concentrations increase. (2) The multipliable effects model can quantitatively predict the variations of normal and tangential grinding forces and workpiece surface temperature. (3) This model can accurately predict the optimum mixture concentrations for minimum grinding results of grinding forces and workpiece surface temperature.

View full abstract

Residual stress and bent deformation induced by diamond grinding of thin plate are studied on yttria-doped tetragonal zirconia polycrystals (Y-TZP). It is focussed to clarify the stresses and the deformations of the plates of various thicknesses by relating them with grinding conditions, and to confirm the role of phase transformation from tetragonal to monoclinic in Y-TZP on the stress and the deformation. The plates were ground with a machine of reciprocatory table type and their residual stress and bent deformation were measured with an X-ray stress analyzer and a profile tester, respectively. A model of partial expansion due to the phase transformation under the ground surface in Y-TZP was treated to calculate the stress and the deformation. The stresses and the deformations between measured and calculated were compared. The results are as follow. (1) The residual stress is compressive under the ground surface and becomes slightly smaller with decrease in the thickness of the plate. (2) The bent deformation shows parabola being convex on the ground surface and becomes very large with decrease in the thickness of the plate. (3) Change in work speed affects the residual stress and the bent deformation more largely than change in wheel depth of cut does. (4) The residual stresses induced by the phase transformation are distinguished from those by another causes.

View full abstract

Short tool life and inferior surface quality are usually considered as the major problems in cutting FRP (Fibre Reinforced Plastic). Up to this time, most of the research on cutting of FRP put their emphases mainly on the mechanism of tool wear and improvement of tool life. The purpose of this study is to find out a way with which the quality of machined surface in cutting GFRP (Glass Fibre Reinforced Plastic) can be improved. In this study, three patterns of machined surface and four typical fracture models of glass fibre in cutting GFRP, which depend on fibre angle and cutting conditions, have been investigated. Though to change tool geometry has some effect on improving quality of machined surface, the most effective way to obtain smooth machined surface regardless of fibre angle is to make undeformed chip thickness thinner. This leads to the conclusion that milling is the best way to ensure both surface quality and productivity. The cutting conditions of milling to satisfy this requirement are also indicated.

View full abstract

Several useful functions for injection mold design are prepared for the system. In this paper, one of the most important functions, i. e., the function of automatic generation of cavity and core is discussed and the newly developed algorithm for the function is presented. And also, some examples which are gotten by the actually developed software are shown. The automatic generation of cavity and core is done using the user-defined geometric data such as product shape, blank shape, parting surfaces and shut-off surfaces.

View full abstract

The paper describes a method for recognition of an overall shape of a polyhedral object. The method utilizes multiple stereoscopic image pairs of the object which consist of conventional half-tone images representing different views of the object. For saving processing time, necessary images are selected automatically and dynamically by use of a geometrical assumption on objects and calculation on images. Through preprocessings, geometrical features, such as vertices, connected edges and surfaces, are extracted from the original images, and described by graphs including their connective relations. An approach utilizing the following three constraints is proposed for solving correspondence problems : (1) geometrical constraints on vertices, (2) topological relations of connected edges, and (3) those between corresponding surfaces. By applying stereoscopic calculations to each pair of images, three dimensional locations of vertices which are involved in the respective field of view can be obtained. Then an overall shape of the object can be reconstructed by identifying common features emerging in different pairs and merging them into a descriptive graph of the overall shape of the object. Experimental results are shown to insist effectiveness of the method.

View full abstract

In previous paper, geometric models including cell complex chains (object models), and abstract cell complex chains (formal data models) were proposed as a base for unification of different models in CAE databases. In this paper, their basic operations are defined theoretically. The basic operations of the geometric models are organized by dividing into operations on figures (subsets in an Euclidean space), on cell complexes, on cell complex chains, and mappings between them. The basic operations of abstract cell complex chains are defined by formalizing the restricted operations of cell complex chains. The relationship between these mathematical models (geometric models and formal data models), physical entities and internal models in CAE systems are discussed, and an implementation method of systems based on these mathematical models is described.

View full abstract

This paper describes the representative polygon and polyhedron which have been introduced in order to aid the visual comprehension of a free-form curve or surface, mathematically expressed by parametric polynomials. The polyhedron is more close to the surface than any other analogues such as the characteristic polyhedron of Bézier method, because each of its faces and the surface are always intersecting or tangential. In case of bi-cubic surface, mostly utilized, it has simple correlation with surface. Therefore it can be applied for various purposes. Some applications are described relating the determination of tangent vector's length and twist vector whose decision is difficult by conventional method.

View full abstract

In order to obtain the modal parameters with enough accuracy based on measured frequency response functions, it is very important to determine the number of modes within the frequency range of interest. None of the conventional methods provide useful information to do this. The paper describes a new iterative method to extract the modal parameters with high accuracy in automatic way, where the enhanced frequency response functions are calculated from initially determined modal parameters and used to re-calculate the parameters. A numerical model is used to demonstrate how to improve the accuracy of modal parameters and finally the method is applied to actual structures with satisfactory results.

View full abstract

A movement with two leaf springs can be modified to one with four leaf springs by replacing the each of midpoints of upper and lower springs, respectively, with reinforcing plate. Even so, the ideal point whose displacement remains unchanged sticks on the midpoint of the reinforcing plate, regardless of the loading position. The above is undisturbed by dimensional errors as far as the symmetry of the movement is kept. The dimensional errors, however, bring the constant error rate of displacement at the ideal point, resulting in the error of mass to be measured by a balance using the movement. Authors discussed in this paper the influences of the dimensional errors in length and thickness of the four leaf springs on the error rate of displacement. Followings are clarified theoretically, experimentally and by FEM ; (1) Around 3/4 and 3/8 of the rate of dimensional error in thickness and length, respectively, contribute to the error rate of displacement. (2) The error rates of displacement are proportional to the difference between the dimensional errors in thickness of two springs, and are proportional to the difference between those in length of outside (or inside) of the two springs.

View full abstract

We have two types of the bilateral servo mechanisms utilized to force reaction type manipulater. The simple symmetry type has the larger transfer deviation. The force feedback type with the smaller transfer deviation needs troublesome force sensing devices. This paper describes the simple compensation method of transfer deviation on the symmetry-type. We found that the transfer deviation of the torque decreases by means of subtracting output of tachometer generator through PD circuit from the driving input of the opposite motor. The system is unstable when the gain constants in compensation circuits are over the limits, which are decided to equivalent mechanical inertia moment and viscous damping factor. The transfer deviation of the compensated symmetry type system is near to that of the force feedback system.

View full abstract

A six degrees-of-freedom (DOF) mechanism is introduced to drive an object (or a table) precisely in directions of x, y and z-axes and around them; three rectangular linear motions and three rotary ones. In the mechanism, the object is driven by six linear actuators surrounding it. Positions and orientations of the actuators are theoretically discussed, which gives the same dynamic characteristics to the six motions and eliminates interferences between the dynamic motions as well as the static ones. As a result of the discussion, a new type six DOF mechanism is designed. Then an experimental mechanism is introduced in which a 70×70×70mm³ cube object is driven by six PZT actuators. Some static and dynamic experiments prove that the mechanism has the designed characteristics.

View full abstract

In this paper, the impact strengths of the commercially supplied Polyvinylchloride (PVC) bolt and Polycarbonate (PC) bolt are clarified and these strengths are compared with static strengths of them. For PC bolt which maintains ductile rupture under impact tensile load as well as static tensile load, the proof stress under impact load is newly proposed. As the result, the following conclusions are obtained : (1) Although the rupture mode of PVC bolt is ductile under static tensile load, it changes into brittle under impact tensile load and consequently, the rupture energy extremely decreases as compared with that in static tensile load. (2) PC bolt maintains ductile rupture under impact load and its rupture energy is comparable to that under static load. (3) For the PC bolt, if the maximum stress under impact load is below the “Impact Proof Stress” proposed here, the failure of the bolt does not occurred.

View full abstract