A process of plasma spraying combined with machining has been proposed and successfullyemployed to produce alumina coatings of high quality over a plain carbon steel bar. Making useof a clean and active bulk surface which has just been machined is of essence in the proposedclean-cut plasma spraying. Besides, integration of grinding into the spraying, in which thegrinding without coolant is conducted just after spraying, makes a contribution to some extentto raise the bond strength between the coating and the substrate. In order to evaluate thebond strength a scratch test has been performed. When the coated substrate is machined by asharp cutting tool, the scratching force and the damaged area are measured, and a shear bondstrength is estimated. The coating made by the combined method gives higher bond strength andlarger wear resistance as well.
A new type of high-speed laser cutting machine for the apparel industry has been developed. The laser cutting position is controlled by two angles of a rocking mirror, which pivots around two axes. A beam expander consisting of a pair of convex and concave mirrors causes astigmatism. A method of compensating astigmatism using only two spherical mirrors, adjusting mirror inclination angles to improve the focus sharpness, is introduced. Two cases of optical design are presented to demonstrate the usefulness of this method.
The present paper deals with the design and prototype of a new rotary diamond dresser, whose dresser diamond pieces are made of synthetic diamond of a fine prismatic shape and their dressing faces and direction are arranged so as to give the highest resistance for wear with respect to diamond crystalline. This dresser could dress CBN wheels stably to a high shape and sharp cutting edges.
A three-dimensional simulation model of cylindrical plunge-cut grinding was previously devised in order to examine the wheel and workpiece wear mechanisms by means of an analysis of displacement equations in the grinding zone. In this study, the same model was applied to the grinding of sinusoidal-waved work surface. The simulation on form accuracy has been developed from some assumptions and an experimentally obtained relationship between wheel removal and workpiece removal parameters. Thus, an analogy was drawn between the experimental and simulated results. It is evident that a newly developed computer model can fairly accurately simulate the profiles of wheel surface and ground surface for an equilibrium solution. The simulation algorithm seems to give an insight into wear mechanisms and, in particular, suggests that it is important for surface profiles to control rotational speed ratio.
An electro-discharge machining technique (EDM) is now widely used for various kinds of die making. However, the surface yields and the resultant thermally induced cracks, white layer and micro-craters may have a detrimental effect on die life. The present paper deals with a new surface modification method which applies laser beam on the surface of cemented carbide having cracks and micro-craters, and obtains the following results. The heataffected zones of cracks and micro-craters are removed due to isolation of WC based on melting of Co acting as a binder. The abnormal structures consisting of face-centered cubic and close-packed hexagonal structures of the surface machined by EDM are transformed to a hexagonal lattice in stable structure by laser irradiation. Thus, it could be verified that laser irradiation modifies the surface of cemented carbide including the heat-affected zones to a sintered state before machined by EDM.
Tapered end mills are indispensable cutters for machining of inclined surface with conventional type of numerical controlled machine tools, for instance side surface of mold and die. But, the cutter deflection problem of tapered end mills has not been analized. This paper therefore tries to analyze cutter deflection by statical load based on flexural rigidity of cutter and aims at presenting basic data on tool design and improvement of cutting method. The main results are as follows: (1) Flexural rigidity and equivalent diameter of tapered end mill are calculated by cross-sections of the tool. And the model consists of truncated cones is generated in order to calculate a deflection of the tapered end mill. (2) Calculating method of deflection of the center axis of the truncated cones model by statical load are shown. (3) Deflection curve of the cutter axis by statical load on end of the tool is calculated, and obtained following results. (i) In case of 4 teeth, the maximum deflection of the tool for one-half of tapered angle α=2° is smaller than that for α=3°. But the maximum values of tapered end mills are about 35% for α=2° and 29% for a=3°greater than that of assumed square end mills. (ii) In case of 2 teeth, the deflection changes depend on the direction of load, and maximum value is about 1.5 times the minimum value. But the range of fluctuation of deflection decreases about one-half for α=2° and 3° with increase of helix angle from 24° to 45° respectively.
This paper describes the prediction method of the fracture area and fracture probability in failure of a cemented carbide endmill under side cutting operation. The law of deterioration, which was confirmed by a theoretical and experimental examination in a single point tool made of cemented carbide, is applied to an endmill with more compricated shape. The cutting tests are achieved for measuring cutting forces in three directions and a tool failure distribution in the number of cutting load experimentally. The theoretical fracture distribution is predicted using FEM computer simulation, which is formulated using the law of deterioration and cutting forces measured, and the effect of a tool shape and cutting conditions on fracture distribution is shown, compared with the experimental results. Theoretically and experimentally, failure originates at the cutter sweep and the fixed end independently of cutting condition, both fracture probabilities are agree approximately. Only by modifying of applied cutting load, which is measured experimentally, the calculation result agrees with the fracture probability in the number of cutting load, in different kinds of cemented carbide tool materials.
Computer controlled polishing using a small rotating polisher is one of the most suitable methods to generate a very precise aspherical surface. In this study, a new type of polishing head for asymmetric aspherical surface was developed, and the aspherical surface polishing of an off-axis ellipsoidal mirror for synchrotron radiation was examined. The characteristics of this polishing head are as follows : (1) A soft disk type polyurethane polisher was used as the polishing tool, and its rotating axis was controlled to be parallel to the tangent plane of the machining point on the workpiece surface. Therefore the profile of the polishing trace was more uniform and was suitable for precisely generating the required asymmetric aspherical surface. (2) The polishing load was applied in the normal direction at the machining point and was controlled to be constant. In tests, a large fused silica mirror was polished to an off-axis ellipsoidal shape. A form accuracy of ±0.6 μm and a surface roughness of less than 0.5 nm Rrms were obtained.
The purpose of this study is to improve the productivity of the molds and dies for plastic injection by means of developing and utilizing the CAM system which can generate CL data for 5-axis controlled machine tools. In case of machining the molds and dies which have complicated and deep shape in Z-direction, the EDM system is widely used. On the other hand, the 5-axis controlled machine tools are not used effectively even if they have the same machining potential as the EDM system because the CAM system which has the following basic functions for multi-axis machining has not been developed; (1) high speed collision detection between machine tool components and the work material, (2) exact position control to avoid the collision, and (3) high speed and high accurate generation of the tool path for rough cutting, semi-finishing and finishing. In the developed CAM system, the Inverse Offset Method has been used for discerning the cutting area previously where the collision may take place. The new rough cutting method on the basis of the contour line tool path with down cut operation has been developed. The results of the actual machining test show that the developed system has the proper functions of collision detection and position control, and the complicated shape machining with high efficiency is possible.
For controlling geometric deviations of machine parts, the Japanese Industrial Standards define geometric tolerances. In geometric tolerancing, a feature of an actual part is acceptable if it can be contained within a spatial tolerance zone. Geometric tolerances in the standards are only defined for primitive planar and cylindrical features, therefore designers have difficulties in specifying a proper geometric tolerance to a surface feature with complex shape. An extended geometric tolerancing method is proposed in this paper which is applicable to a composite feature with several primitive faces. This method satisfies the "principle of independency" so that it can control geometric deviations of an actual surface feature regardless of its sizes. It is compatible to the current geometric tolerancing practice also. A concept of parameterized features is introduced to represent modifications of a composite surface feature according to its size variations. Features with the correct form, features in the correct orientation, and features in the correct position are defined by using a parameterized feature with variable sizes. A geometric tolerance is formalized as a spatial zone of acceptable deviations measured with respect to such a reference feature with the correct geometry.
This paper introduces new local minimum properties into the C2 interpolating curve, each span of which is determined by 6 or 8 neighboring given points. The marriage between the fairness based on variation problem and the local behavior obtained by degree-elevation or knot-insertion, the opposite-like concepts, of the curve is studied by various minimization conditions independent and dependent of the given set of interpolation points. The results are: (1) Every condition studied improves improper behavior in the previous curve. (2) One of the conditions may generate a curve with smaller value of "energy integral" and curvature plot consisting of fewer monotone pieces than the conventional cubic C2 interpolating curve. (3) Applying a minimization condition to the blending function leads to a new curve in simple yet fairly effective way.
The study is on autonomic high speed measurement of a three dimensional shape by using a non-contact sensor which can continuously and simultaneously detect the normal direction and the position of a measured point. This paper describes the system architecture and a design of the sensor. In order to design the sensor, the principle for detecting a normal direction and a position by reflected light of a beam projected on a measured point is clarified. According to the principle, a structure of the sensor element which has an emitting optical fiber with a graded-index lens and eight receiving optical fibers is determined. Also, computer simulations are performed to make the performance of the sensor element clear. In the simulations, a model-equation which expresses ray-intensity of the projected beam is derived, and reflected light of the beam is modeled by a diffuse component and a specular component. From the simulation-results, it became clear that the sensor element can detect a normal direction in the range from -45.0° to 45.0° and detect a position in the range from 2.7 mm to 6.0 mm for a diffuse surface. For a specular surface, the range of a detected normal direction is restricted from -7.5° to 7.5°.
The paper describes the method to improve thermal deformation of machine tool by making good thermal balance with insulating boards applied to the structure. The usefulness of the method is confirmed by the experiments with a model and by the finite element method. The application of the method to the double column vertical type machining center is successfully made by reducing the thermal deformation about one third compared with the conventional way.
Visual functions for bin picking are realized fast by utilizing a sparse range image. The functions are composed of (1) detection of a necessary part from a lot of parts piled on each other, and (2) measurement of its three dimensional position and orientation. Framework of the vision system is discussed on the assumption that a shape model of the necessary part is given. Method of fast segmentation of a sparse range image is presented for the part's detection. Four kinds of shapes: polyhedra, cylinder, cone and sphere are chosen as important shapes for industrial bin-picking, and for each shape, examination if a segment of a sparse range image is the shape, and measurement of its three dimensional position and orientation are shown. Experiments with a real fast range sensor and a personal computer show that the presented vision system is fast: total process time is less than 1.5 s for multiple piled cylinders.
A study is presented on measurement of axisymmetrical form generated by ultra-precision machining. At first, sectional curves along concentric circles and diameters are measured by a contact type form measuring equipment. Secondly, these sectional curves are combined on cross points by least square method to compensate measuring errors due to tilts and lifts of the specimen. Consequently, the sectional curves can be evaluated based on the identical basic plane. After that, a curved surface is generated by interpolation from sectional curves and is shown as three dimensional display. The effectiveness of this method is revealed by simulation using actual form obtained by Fizeau interferometer.