工作機械の高速化について,その背景と関連技術の現状を概観した.高速化は工作機械の高度化,差別化の重要な柱の一つであり,今後における関連技術の進展が期待される.

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Al₂O₃/TiCを対象として,LAEの特徴,加工の機構とその特性,そして微細加工への応用について検討し,次の結果を得た.
(1) LAEはレーザの熱とエッチング液の化学反応を利用した複合加工技術で,その加工面は溶融物やクラックの存在しない粒子状の粗面になるという特徴がある.
(2) LAEの基本的な加工機構は,レーザの熱で化学的に活性な溶融物を生成し,この溶融物とKOHが反応してエッチングされることにより,加工が進む.
(3) LAEの加工速度はレーザパワー,ビーム走査速度,KOH濃度に依存する.また加工溝の断面形状はビームの発振条件によって変化する.微細加工には(Qスイッチ+シングル)ビームが最適である.

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Al₂0₃/TiCを対象として,LAEの特徴,加工の機構とその特性,そして微細加工への応用について検討し,次の結果を得た.
(1) LAEはレーザの熱とエッチング液の化学反応を利用した複合加工技術で,その加工面は溶融物やクラックの存在しない粒子状の粗面になるという特徴がある.
(2) LAEの基本的な加工機構は,レーザの熱で化学的に活性な溶融物を生成し,この溶融物とKOHが反応してエッチングされることにより,加工が進む.
(3) LAEの加工速度はレーザパワー,ビーム走査速度,KOH濃度に依存する.また加工溝の断面形状はビームの発振条件によって変化する.微細加工には(Qスイッチ+シングル)ビームが最適である.

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The major subject of this study is to evaluate the strength reliability of ceramics for mechanical component applications based on fracture mechanics. This paper describes fatigue crack growth characteristics of PSZ (partially stabilized Zirconia) at roomtemperature in cyclic three point bending test. Extensive crack growth was observed prior to the final fracture during cyclic loading and it was confirmed that PSZ exhibits a linear relationship on logarithmic scale between the fatigue crack growth rate and the stress intensity factor range. Statistical characteristics of the crack growth rate parameters and fatigue fracture toughness value were also discussed by goodness-of-fit test for Weibull, normal, and Type I extreme value distribution functions, and these variables were found to fit Weibull distribution best.

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This paper proposes a method for making wire tools. It has been known that wire tools are used for lapping, EDM, etc. But their removal rate is very low. Then a wire tool is developed to which 10μm diamond grains are adhered by nickel plating. φ0.2mm nude wire, copper wire or piano wire, is wound from the first drum to the second one at a given speed. On the way it is plated nickel in the grains pool and diamond grains are taken in the niekel layer. By this method the number of adhered-grains can be increased. The followings are obtained. The higher the current density is, the more the number of adhered-grains are. But when it is too high, either the wire tools surface becomes rough or cracks occur on the nickel layer. The higher wirevelocity is, the less the number of adhered-grains are. When it is too high, diamond grains aren't taken in the nickel layer. On 2.27-4.55A/dm² and 7.24-18.1mm/min, the expected wire tools can be obtained.

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The outer-blade slicing parallels the cut-off grinding and the creep-feed grinding in configuration. But it quite differs from them in that a very thin cutting blade is used, which undergoes an elastic deformation. From this viewpoint experimental studies have been carried out using GC grit blades 0.5mm thick and the following results are obtained. (1) An upward grinding force occurs in up-cut slicing process, which may be due to side face grinding following the elastic deformation of blade. (2) The upward grinding force has a usual sensitivity for grinding conditions. (3) Attritious wear predominates in the wheel wear under a small v/V ratio, while bond fracture does under a large v/V ratio. (4) The grinding performance of cutting edges on the side face has an important influence on chipping of the workpiece.

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In this paper it is attempted to estimate quantitatively how the microscopic embrittlement action of free-machining additives, such as void formation and void coalescence around MnS particles, brings about the macroscopic free-machining effects. This consists of determination of stress-strain curve of resulfurized steel based on the behaviour around particles and evaluation of free-machining effects by FEM cutting simulations of both of resulfurized and plain carbon steels according to the stress-strain curves obtained above. In ordes to obtain the stressstrain curve, loaded-unloaded stress fields around the single particle or the coalesced two particles, which were calculated separately with FEM, are inserted into the matrix sheared and stressed up to a given strain with an assumption that the calculated stress fields around the particles closely resemble to those in real resulfurized steel. The bulk shear stress was then obtained as the mean value of the inserted stress fields over the specimen. The stress-strain curve obtained is in good agreement with experimental result. In spite of the same friction characteristic on the rake face used in the FEM cutting simulation for both plain carbon and resulfurized steels, a higher shear angle, a lower cutting force, and a smaller tool-chip contact length were obtained for the resulfurized steel. It is thus confirmed that the embrittlement action of free-machining additives is one of significant factors in the improvement of machinability.

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To analyse the dynamic strain distribution of a substructure in detail and with accurate, a combined method is proposed such that the substructure is modeled by the finite elements and the remaining structure is expressed by the experimental model strain analysis using strain gages. The constraint method is used to solve the dynamic strain distribution of the substructure described in the finite elements against the boundary forces determined by the measured dynamic strains. Using numerical examples with beam elements and two dimensional triangle elements, this proposed method can analyse the dynamic strain distribution with satisfactory accuracy. Then an actual beam and an L-shape pipe are tested to show the effectiveness of the method.

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For generating NC machining commands automatically, it is important to handle computer models such as geometrical shape data and product data including engineering specifications for the mechanical part to be manufactured.Based on this concept, we proposed a product model especially designed for machining applications. We developed a system which generates NC commands for rough machining automatically by using product model. Through machining experiments with these generated NC commands, we confirmed the effectiveness of our product model.

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After discussing that mix flexibility can be achieved by having either extra machine capacity or machine redundancy capable of performing different operations, this paper formulates a mix flexibility planning problem as a 0-1 mixed integer program with two levels. The first level gives a minimal cost solution meeting all possible combinations of production rates of different parts to be processed. The second level seeks for a cheaper solution at the sacrifice of losing mix flexibility.

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The investigation is concerned with the construction of the decision support system on the manufacturing condition of the grinding wheel. The system with the grinding data file, the materials cost file and the grinding wheel quality file can derive the trial manufacturing condition of the wheel which exhibits the desirable grinding characteristic on the basis of minimal materials cost. It is confirmed by the experimental estimate of the trial wheel that the procedure for the decision-making about the manufacturing condition is particularly appropriate.

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The use of leaf springs has found wide application in measuring and scientific instruments. The advantages of the leaf spring mechanisms are as follow: (1) Provide movement without friction or backlash so that high accuracy and good repeatability can be obtained. (2) Simple and low costs, and no lubrication is required. This paper deals with new mechanisms using leaf springs. The parallel movement devices are consisted of a pair of parallel leaf springs having identical length, width and thickness. In these movement devices, the displacement in perpen-dicular direction is increased when the upper member was moved lateral with respect to the bottom member, or increased resistance to any vertical loads, which may be imposed on the mechanism. It was achieved by using original compound leaf spring movement mechanism. In the mechanism, the displacement in perpendicular direction was 0.8μm while the track was 10mm long. A new rotary mechanism was also considered. In the mechanism, the disadvantageous displacement was within 2μm and movement of the axis of rotation was within 5μm where the radius was 92.5 R while the rotation was 6.2 degree.

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One of the significant problems in designing a magnetic bearing control system is that there are gyroscopic couplings between two rotational motions of the suspended rotor. Because of these couplings the optimal regulator system related to the rotational motions needs antisymmetric cross feedback compensation in addition to usual displacement and velocity feedbacks of individual motion. It has been shown that the optimal regulator system has better transient response characteristics than the independently controlled system, that is to say, the system with no cross feedback compensation which is obtained as a result of disregard of gyroscopic effects in the process of designing the control system. In view of applications of magnetic bearings it is important to investigate the dynamic behaviour of the system disturbed by external forces besides the transient natural motion. This paper shows an analytical method to study forced motions of the gyroscopic coupled systems when static or sinusoidal varying forces are applied to the rotor and clarifies differences between the optimal regulator system and the independently controlled system. Experimental tests are carried out to verify the theoretical results.

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The possibility of a hydrostatically supported spindle having small radial runout not exceeding 0.01μm is examined. The new mechanism compensating the radial motion error is proposed. The mechanism consists of two micropositioning devices called closed looped differential hydrostatic actuator, and their operating directions are at right angle each other. The micropositioning device, having a stiffness of the order of 10⁴N/μm, controls the radial motion of a spindle within 0.001μm. The experimentation shows that the resolution is within 0.001μm, the bandwidth of the control system is about 90Hz, and the interference between the two positioning devices is negligible small. The radial motion error may be compensated by the proposed mechanism.

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Active balls in ball screws should be taken sliding motions, which are called "wedge sliding", in the normal direction to helicoid of ball center, because lead angles of shaft and nut raceways are not the same respectively. Ball slip may also be produced in the rolling direction of active balls, because they contact each other with some slip. It is well known that these slips will significantly affect the friction and wear characteristics and also the rolling fatigue lives of ball screws. The ball motion in the ball screws must be therefore investigated in order to make clear these characteristics. In this paper, the authors carried out some experiment using a magnetized ball and wound coil on the nut in order to measure the ball slip ratio in the rolling direction of active balls. The results are summarized as follows: (1) Active balls in the ball screw make complicated motion with sliding and spinning and their rotating periods vary widely. (2) Rapid spinning occurs more frequently in the back driving of the ball screw than the normal driving. (3) The slip ratio of ball revolution in the ball screw is about 1% at the shaft speed range of 60-600rpm. (4) The slip ratio of ball rotation increases as the shaft speed increases in the normal driving. The slip ratio of the back driving remarkably differs from the normal one in relation to the shaft speed.

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When the light passes through the magnetic fluid film in the magnetic field, double refraction occurs along with polarizing of the light. Therefore, by controlling the intensity of the magnetic field, it is possible to give arbitrary polarization to the transmitted light. The phase difference due to this phenomenon can be measured by means of heterodyne with a transverse Zeeman laser. This difference is observed to exceed 180 deg. in some cases and the response of the phase shift to the variation of magnetism attains to 5kHz, where the switching interval is less than 0.4ms. One applicative attempt is performed to realize an element for dividing the incident light in two directions with the intensity ratio of 98 to 2.

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This paper proposes dressing performance of a new sintered composite of iron powder electrolytic and oxide abrasive. Under constant dressing condition good dressing performance is observed in the composition of stick that contain 40% aluminum oxide abrasive (MA 220), 0.5% carbon and 59.5% electrolytic iron powder, or 30% aluminum oxide and electrolytic iron powder in balance. The consumption of dressing stick in service is nearly about 1/12 that of WA stick commonly used and grinding force is markedly decreased in stable state even just after dressing treatment.

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The elastic grinding wheels with a resistant wear properties are used for mirror abrasive processing of metal molds. And also, the passage efficiency of machining fluids are very high. Keeping our eye on these points, we experimented with use of a binder (PVA+Phenol resin) of elastic grinding wheel for the filter material of the machining fluid for ultra-precision processing. Our experiment produced the following conclusions. (1) PVA and phenol resin functioned sufficiently as filter material for filtration can be achieved at a lower filtration cost compared with the conventional filter material of the cartridge-filter type. (2) We were able to manufacture the filter material whose mean pore diameter was 0.05-200μm, with a porosity of 65-94%, filter drag of 0.5-80mm/Aq and a resistant compressive strength of 50 kgf/cm². (3) The filtration machine has a machining fluid concentration of 0.5ppm, filtering efficiency of 99.99%, mean particle diameter of the impurity materials of 0.1pm and a filtrating rate of 5 l/min. (4) Filtration can be performed with both water-soluble type and straight-oil type, but there is a difference in the filtrating rate. (5) The processing accuracies and performance of ultra-precision processing by filtration are not improved to any great extent, but life of machining fluid is increased greatly and stable processing accuracy and performance are able to be obtained.

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