In the present paper, the life tests of 24 ball screws assembled with 66 nylon spacer balls and that of 19 ball screws which differ from the 1st and 2nd reports in the raceway hardness are carried out. Based on the results of these life tests, the influence of use of spacer ball and the raceway hardness on the fatigue life are discussed. The results may be summarized as follows :(1) The basic dynamic load rating of ball screw assembled with the spacer balls is 10% greater than that filled up with the active balls, because the spacer balls reduce the slips between the active balls and raceways. (2) The 66 nylon spacer balls are durable enough for practical usage. (3) The basic dynamic load rating of the ball screws of HRC 56.3 in the raceway hardness of screw shaft is decrease by 20% compared with that of HRC 61. (4) It becomes clear that the fatigue lives of ball screw are considerably influenced by the raceway hardness compared with those of ball bearings from the empirical formula derived in this report.

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A shearing interference microscope has high image stability even under vibration. This paper proposes a measurement method of RMS roughness and autocorrelation function of super smooth surfaces using shearing interference microscopic images. It makes use of the fact that, when the shearing length is extended widely in comparison to the autocorrelation length of the rough surface, the shearing interference image comes in close relationship with the RMS roughness of the measuring surface. Herein are shown a principle and a theory as well as a result of measurements of super smooth surfaces of 2 nm-10 nm RMS roughness.

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This paper deals with a study of cutting power requirement in "Chatter Machining", a newly developed manufacturing method for producing fine short metal fibers. The relations between required cutting power and manufacturing conditions are experimentally investigated using a digital power meter. The results reveal that the cutting power is proportional to the chatter frequency of the tool and also to the square of the equivalent fiber diameter, and the amount of cutting power is found to be smaller than that of conventional cutting in the region of fiber formation. Further, it is confirmed that the specific cutting resistance derived from cutting power shows reasonable values as per the estimated value for conventional cutting.

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Machinability of difficult-to-cut materials has been a great concern to manufacturing engineers since demands for new materials in the aerospace and nuclear industries are more and more increasing. The purpose of this study is to develop a hot machining to improve machinability of high hardness materials. A plasma arc is used for heating materials cut. The surface just after being heated is removed as a chip by tungsten carbide tools. The turning experiments of high hardness steels with aid of plasma arc heating show not only the decrease in cutting forces but also the following effectiveness : (1) The application of the plasma hot machining to the condition, under which a built-up edge (BUE) appears in turning 0.46%C steel, makes the BUE disappeared, bringing less flank wear. (2) In the case of 18%Mn steel cutting, deep groove wear on the end-cutting edge diminishes, and roughness of the machined surface is improved by the prevention from chatter. (3) Although the chilled cast iron has high hardness of above HB=350, the plasma hot machining makes it possible to cut it with tungsten carbide tools having less chipping and flank wear.

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A new ceramic coating technique is developed, in which focused cw CO₂ laser beam over 1 kW can be irradiated on the peripheral surface of a rotating ceramic ring in vacuum. Main results obtained from fundamental experiments are as follows : (1) Firm and homogeneous ceramic films can be formed in a vacuum about 1.3 × 10^-2 Pa. (2) The coated films have an amorphous structure and the compositions are often different from those of the mother materials. (3) Hardnesses of the films are not lower than those of the mother materials. Especially very hard BN film of Knoop hardness over 39.2 GPa can be formed by evaporating the soft sintered hBN with high deposition rate over 0.2 μm/min. (4) Ceramic coated Mo specimens show high wear-resistance in sliding experiments compared with the metal Mo itself.(5) Ceramic films coated on Mo substrates are effectively applicable to an absorbent plate against very high power CO₂ laser.

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A new type of air permeable mold which can be applied to the various manufacturing fields, has been developed. The mold is made by a mixture of mullite powder, iron powder and ethyl silicate and then sintering it in an air atmosphere at around 900°C for a few hours. The mold has a porosity between 20-30 vol%, as well as an adequate permeability to air. The sintered layer of the mold is found to consist of the ceramic powder being firmly bonded by the oxidized iron powder. Furthermore, a compressive strength of 100 MPa at the maximum is obtained although there are many pores within the layer. The dimensional change of the mold can be suppressed to a value smaller than 0.2% linear expansion, though it is manufactured by sintering process. In addition to the above mentioned features of the mold, a fine complicatedshaped surface of the mold can be manufactured very easily by casting the mixture on to the master model. In this paper, the production procedure and characteristics of the mold are described, as well as the application to the vacuum forming of plastic sheet as one of several usages of the mold. In addition to the advantage that the proposed mold can eliminate drilling holes for air evacuation, it gives a good forming capability of fine-complicated shape due to uniform evacuation through the well distributed fine pores in the mold.

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The formation of burrs in face milling of plain carbon steel (S 45 C normalized to 179 HB) is investigated in connection with cutting conditions. Two types of burrs are observed. One is named a primary burr, which has the height nearly proportional to depth of cut. Another is a secondary burr, which is smaller than the primary burr because of separation of a tip of the burr during the burr formation process. Large depths of cut and small tool disengagement angles lead to the secondary burr formation, and cutting under these conditions can be one of methods for minimizing burrs. Although the component of cutting forces in the normal direction to the edge is thought to produce burrs, the measurement of cutting forces at the tool disengagement indicates that the component in the feed direction plays an important role in the secondary burr formation.

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Electron beam drilling is done by sequent removal of molten material. Quantitative measurement of molten layer produced in materials has not been carried out. In the present paper, the temperature rises due to electron penetration into materials are obtained and are compared with those due to a surface heat source. The temperature rise distribution must be obtained from the solution involving electron penetration during a short heating time ; however, for a long heating time, it can be obtained from the solution for a surface heat source. The molten layer remaining at the hole bottom in iron is measured. The layer thickness does not hold constant ; it increases and decreases intermittently. This fact indicates that some quantity of molten layer is required for producing a hole by the ejection of molten metal. The critical quantity depends on the kind of metals.

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Structures and strength of welded joints of ductile irons have been experimentally investigated which were electron-beam welded using Ni insert plates of 0.2 to 0.5 mm in thickness and then annealed for 1h at various temperatures from 823 to 1 123K. Acicular martensitic structures and high carbon martensitic structures were observed in the bond and around the spheroidal graphites in the heat affected zone, respectively. After annealing at higher temperature than 973 K, these martensites were completely disappeared and fine cementite and graphite particles were precipitated in both bead and bond zones. The hardness in the bond decreased to similar values in the bead and base metal zones by annealing at higher temperature than 923 K. The tensile strength of welded joints in which Ni plates of 0.30 to 0.35 mm thick had been inserted were almost recovered to the strength of base metal by annealing. Fine blowholes which were observed in the bead did not affect the tensile strength of annealed specimens. Charpy impact values of as-welded specimens were less than 20 J/cm², while the values of annealed ones were kept at more than 60 J/cm².

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ぜい性材料の加工面及びその近傍に発生する欠陥群を,等周期等長平行き裂群として仮定し,加工面に仕上加工を行った場合の部材強度の変化を,有限要素法により応力拡大係数を求めて検討した.結果を以下に示す.
(1)等周期等長平行表面き裂群においては,一軸引張りの方向に1列にき裂が並ぶ場合にも,一様引張荷重下でき裂が直交している場合にも,き裂深さが分布周期の約20%より大きいときには,応力拡大係数は,き裂深さの変化には無関係に一定だった.したがって,材料の破壊じん性が常に一定とすると,そのような条件下で,部材強度は一定になると考えられた.そして,そのようなき裂群を有する部材の表面層を加工損傷の少ない加工法で除去する場合には,除去深さが一定の値になるまで,部材強度は一定で,その深さ以上の表面層除去を行った場合に初めて,強度が回復することが示された.
(2)部材表面近傍に,等周期等長平行内部き裂群がある場合,き裂の分布周期が短いほど,き裂が部材表面により接近するまで,表面側のき裂端の応力拡大係数は一定値を示し増加はみられなかった.そして,分布周期がき裂長さ以下になると,内部き裂の表面側の先端が進展して表面にまで達し,表面き裂群になった場合の応力拡大係数は,内部き裂の安定域での値とほぼ一致した.
今回の研究により,加工欠陥と部材強度の関係について,特徴的な傾向が得られたので,今後はセラミックを対象材料に,放電,研削,レーザ等の加工に,この結果を適用して実験を行う予定である.

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This paper describes the new methods of fine finishing by electro discharge machining (EDM). In order to realize mirror-like surface or glossy surface to the work by EDM, it is necessary to control the pulse current to be small appropriately. With the conventional technology in this field, the attainment of pulse control is very difficult, especially in the case of machining to the work surface which has large scale of area, because of gap storage capacitance between the electrode and the work surface, even if not so much power supply. The present study is an attempt to break through the difficulty pointed above. Multi-divided electrode methods are newly tried. The roughness of 0.5 μmR_max has been achieved to the work with the area of 100 cm² by 100 divided electrode. And the glossy surface with 2 μmR_max has also been achieved to the 275 cm² work by resistor (silicon) electrode method which can be considered as an extention of multi-divided electrode.

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This paper aims to realize a vision system for robots which handle mechanical parts for assembly at production lines. The process to recognize mechanical parts consists of two portions. One is the off-line process as preceding process to recognize parts efficiently, the other is the on-line process to recognize parts by real time. In the off-line process, geometric models are made for mechanical parts and the characteristic of reflection of their surfaces are evaluated by experiments. The characteristic of reflection are represented by a reflection function. The reflection function used in this paper is based on Phong's equation and it is modified simpler to make the process easy. By using this knowlege, positions of highlight regions at various postures are estimated to make recognition algorithm of the on-line process. Highlight regions as features to recognize objects have following merits : (1) The process to extract them is easy and takes a short time. (2) Shapes of them don't change very much even if the postures of objects are changed. The recognition in the on-line process are made by matching extracted highlight regions with the estimated ones from parts model. By using this method positions and postures of mechanical parts put at random are identified precisely for a short time by slantwise fixed TV camera.

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A model-based off-line programming system of the robot operations is developed for industrial use. Environment modelling system based on the solid modelling system GEOMAP-III, is developed as a tool for maintaining the information of the working environment of the robot, such as robot itself, parts to be assembled, obstacles, etc., and other necessary information for the robotic tasks. A high-level assembly description language which describes assembly process in terms of the operations on the parts to be assembled instead of motion of the robot itself, is designed. By utilizing the information of the environment model, the system generates information of the robot motion from this high-level description, simulating the changes in the environment. Feasibility checks of the generated robot motion, detection of collisions between the robot and obstacles, calculation of necessary grasping force, are performed in the process and the results are displayed to the operator for easy debugging of the program. Preparation for sensory interactive robot motion in the run-time system, is also considered. As examples, some assembly operations are programmed by the system with high-level language.

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The retrofitting techniques of an unnumerically controlled machine tool to NC machine tool is necessary to reconstruct a superannuated machine or to construct a special purpose machinery. The aim of the present study is to retrofit a lathe to NC lathe with an interactive programming system through a hand-made circuit. The achievement in this study are follows : (1) The problems which arise to retrofit a lathe to NC lathe are classified into each group, and the means of solving the individual problems are shown. (2) Accuracy testing and cutting performance are investigated in the retrofit NC lathe, it is confirmed that the NC lathe is a match for the NC lathe placed on the market. (3) Addition of an interactive programming system by means of personal computer enables one to easily provide NC programming and to immediately modify, edit and manage it. (4) It is verified that a feed control makes the cutting time shorter.

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