The purpose of this work is to establish a database of fatigue life distribution and a reliability of rolling bearing. Fatigue life test of deep groove ball bearing #6206 lubricated by Lithium grease lubrication is carried out under pure radial loads F_r=9.14, 10.64, 12.13kN. The fatigue life distribution, the basic dynamic load rating and the load life exponent are estimated and discussed from the test results.

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Authors constructed the load distribution theory that had applied the FEM analysis to the carriage and the rail. As a result, the analytical accuracy of Linear Motion Ball Guide has improved dramatically. Next, we improved this theory, reduced an analytical cost, and constructed LMBG System load distribution theory that applied the FEM analysis to the table. In this report, the outline of these theories is described. In addition, the result of calculating the relation between the deformation of the table and the life of Linear Motion Ball Guide System is reported.

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A study on life distribution and reliability for a roller guide with cage type is carried out with the total number of 80 test samples made up of four series and fatigue life distribution functions, such as the log-normal distribution, the two-parameter and the three-parameter Weibull distribution function are used for discussion. The basic dynamic load rating obtained ISO formula is compared with the life test data in relation to the effect of crownings of carriage raceway both end portions. As a result, the best fit for the life test series is obtained by the three-parameter Weibull distribution function introduced a minimum life with Weibull slope m=27/20 and load life exponent p=10/3, followed by the log-normal distribution as second, and the two-parameter Weibull distribution as the third.

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A new positioning device driven by an enlargement mechanism with a PZT drive has been developed to realize positioning the table by submicron meter. In this study, the mechanical principal of a newly developed enlargement mechanism consisting of fluid chamber, a PZT device, and cutting tool stage is reported. The basic performances of the developed mechanism are also evaluated. This developed device demonstrates that the magnitude of enlargement reaches 5.6 times of stroke than the original one of the PZT. The dynamic characteristics show DC to 5 Hz which is enough wide for the frequency response to realize the precise positioning. The positioning stage is controlled by PI control. The positioning accuracy is accurate enough for the precise positioning.

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A redundantly actuated 3 degree of freedom (xyθ) planar parallel link mechanism (PLM) with back-flip motion is proposed. The back-flip means that the end plate of the PLM has working area of 180 degrees or more. It aims at the table mechanism of multi-axes machine tools. In this paper, the condition and the working area to do the back-flip are defined. In addition, singular configuration and stiffness are analyzed by using the kinematics of the PLM. By applying numerical analyses, it has been revealed that the back-flip motion can be achieved stably (not singularity) over the working area excluding the upper limit.

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Vibration isolation is widely conducted for precision machinery in order to reduce errors due to disturbance. This paper newly presents a non-contact type active vibration isolation unit which consists of an air spring, a voice coil motor, and an aerostatic bearing in order to achieve non-contact condition. In addition, the active vibration isolation with a PID controller reduces an influence of direct disturbance force. By using both the non-contact structure and the PID controller, the resonances in ground vibration transmission and direct disturbance transmission can be successfully reduced.

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Recently, high-speed milling has attracted considerable attention for high processing efficiency and lower cut resistance. However, these milling machines using micro end mills generally have some difficulties in installing a small end mill chuck with less than 10mm diameter to a spindle. Therefore, this paper investigates the possibility of machining method that a milling cutter is directly driven by air turbines to achieve higher rotational speeds. In the proposed machining method, the end mill shank is directly supported by aerostatic bearings. In this paper, the proposed machining method was tested by cutting a bronze material with a small end mill at speed of 400,000 rpm. It was consequently found that the proposed machining method has the possibility to achieve higher milling cut speed.

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Recently, high-speed milling using micro milling cutters has attracted attention as the method for achieving high efficiency and high precision machining. However, it is very difficult for conventional bearings to satisfy high-speed milling because of large power consumption. Accordingly, in this paper, water-lubricated bearings for a machining tool were proposed. The proposed bearing is an integrated bearing with thrust and journal bearings for miniaturization and can stably rotate at high speeds. The objective of this paper is to investigate numerically the static characteristics of the thrust bearing and the high-speed stability.

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A porous vacuum chuck has an advantage that the flatness of an object held by this kind of chuck is superior to that by other types of vacuum chucks with vacuum holes or circumferential vacuum grooves. This is because porous material has through holes with micron-meter order diameter over a chuck surface. In addition, it is reported that a surface-restricted layer which has lower permeability than the bulk of the porous material can improve the holding characteristics, especially in the case of holding an object with smaller diameter than a porous chuck diameter. However, forming the surface-restricted layer is somewhat troublesome work. In addition, when a porous chuck is applied to machine tools, cutting fluid infiltrates a porous chuck and a holding force is decreased. Moreover, in cutting materials, a cutter also cuts the chuck surface and,accordingly, an air permeable sheet is usually inserted between an object and a chuck surfaces. Therefore, this paper proposes to use a water-impermeable porous film with 0.3μm diameter holes as the surface restricted layer and the permeable sheet to overcome the above problems. The lateral holding force is clarified experimentally. It was found that a water-impermeable porous film can easily form the surface-restricted layer for vacuum chucks and the lateral holding force is increased by inserting the water-impermeable porous film between the porous chuck and the object.

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The objective of this paper is to design development sliding plain bearings for hermetic screw-compressors. In screw-compressors, ball-bearings are widely used to support thrust-loads and radial-loads. This paper studies, the bearing of the screw-compressor is the question of bearing-life and bearing-noise, as to replace the slid-bearings from the ball-bearings. However, difficulties that as the bearings are forced to be refrigerant by diluted oil into lubricated, whose viscosity is much lower than a pure-lubrication. Also the screw-rotor rotates into both direction, clockwise rotational and counter clockwise rotational, depending on the compressor-cycle conditions. On this paper, the experiments were conducted on the compound of the grooved-thrust-bearings by use of refrigerant-blended lubricant simulation system of real conditions, and the tests results in bi-rotational was presented. Tests were conducted on the thrust-bearing tester driven by a motor in simulated refrigerant cycle. The configurations of the test runner and bearing are shown in Figure1. This configuration of the bearing is named 'The Ribbon-Bearing-type' and is calling. At starting period, injection lubrication is applied to reduce friction-torque. The outer and inner diameters of the bearing are φ80 mm and φ40 mm respectively. Combination grooves, spiral and radial ones, are formed on the runner surface. The depth of the each grooves are 0.1 mm. The inflow type spiral-grooves enhance the generation of hydrodynamic pressure as usual way in clockwise rotation. Radial-grooves at the inner periphery are intended to effectively introduce hydrostatic pressure, generated by screw-compressor. The tests were carried out to obtain the data for bearing performance operating at an actual condition of refrigerant-blended lubricant. Film-thickness, bearing-temperatures and friction-torque were measured. Synthetic-oil was used as the lubricant. The tests were carried using refrigerant-blended-lubricant. Refrigerant-blended-lubricant is blending-ratio of 6wt%, 10wt% and 44wt%. Simulate is the real state of the refrigerator-compressor. Bearing-film thickness, bearing-temperature, and friction-torque were measured to evaluate bearing performance. The operating conditions were 2500rpm rotational speed and 3.8kN bearing-load. At that condition using 44wt% refrigerant-blended-lubricant, frictional-torque was about 16Nm. The potential of the ribbon-type-bearings were well demonstrated.

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A linear-motor-driven table supported by hydrostatic-water bearings had been developed. The table slider is supported by a single-sided recess type bearing and preloaded by attractive force of a linear-motor magnet. Since eccentric excitation force is applied to the table slider due to the change of attractive force according to the magnet track position of the linear-motor, pitching motion of the table occurs. This paper investigates the effect of air volume contained in a water-supply tube on the pitching motion. Larger air volume results in lower natural pitching frequency of the table slider and larger pitching angle. When the natural pitching frequency corresponds to the frequency of the eccentric excitation force during table feed, pitching angle grows by resonation.

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