Showing papers on "Fluid bearing published in 1982"

Thrust bearing assembly for a downhole drill motor

Abstract: A bidirectional thrust bearing assembly is used between a downhole fluid motor and a rock bit for drilling oil wells. The bearing assembly has a stationary housing with radial journal bearing sleeves and a rotatable drive shaft also having radial bearing sleeves. A pair of oppositely facing thrust bearing rings are mounted in the housing. A second pair of thrust bearing rings are mounted on the shaft so as to have faces opposing the bearing faces on the first pair of rings. Belleville springs resiliently bias a pair of the thrust bearing rings apart and carry the thrust load between such rings. Each ring has a plurality of inserts of hard material, preferably polycrystalline diamond, at the bearing surface. Means are provided for circulating drilling fluid from the motor through the thrust bearing faces for forming hydrodynamic fluid bearing films in the bearing interfaces.

Effects of Fluid Inertia and Viscoelasticity on Squeeze-Film Bearing Forces

Abstract: The Reynolds equation of hydrodynamic lubrication is normally used to determine the damping coefficients in the analysis of rotor-dynamic system with squeeze-film dampers. Lubrication theory assumes that the fluid motion is precisely in phase with the bearing surface motion, but at high speeds both inertia and viscoelasticity introduce phase-shifting effects into the fluid motion. As a result, predictions derived from Reynolds' equation can be significantly in error. An earlier series of papers developed a theory to account for the influences of viscoelasticity and inertia in arbitrary oscillatory squeezing flows of small amplitude. The theory is applied here to develop improved expressions for the linear damping coefficients, in terms of the Reynolds and Deborah number. Evaluation of the corrected formulae show that fluid inertia and viscoelasticity have large effects on the coefficients.

Bearing foil stiffener

Abstract: A fluid bearing having a pair of members in relatively rotatable relationship with each other, and a compliant foil bearing disposed between the pair of relatively rotatable members. The compliant foil bearing has a plurality of overlapping integral compliant foil/stiffener elements with one end mounted to one of the rotatable members.

An Influence of Inertia Forces on Stability of Turbulent Journal Bearings

Abstract: It is a purpose of this paper to discuss both turbulence and inertia effects on the static and dynamic characteristics of high speed journal bearings. Because of the difficulty of analysis, infinitely long and short width bearings are dealt with analytically instead of finite width bearings. It is found that the static characteristics such as the Sommerfeld number and the locus of shaft center are affected mainly by turbulence but the dynamic ones such as the spring, damping and acceleration coefficients of lubricant film and the stability of rotors are affected by inertia.

Hydrodynamic lubrication of rough surfaces

Abstract: Using the two-space homogenization method we derive an averaged Reynolds equation that is correct to O ( H 6 > — H 3 > 2 ), where H is the total film thickness and the angle brackets denote a spatial average. Applications of this mean Reynolds equation to a squeeze-film bearing with a sinusoidal or an isotropic surface roughness are discussed.

Fluid bearing assembly

Abstract: An oscillating pneumatodynamic bearing takes the form of a laminated transducer disc (2) co-operating with a flat surface (16) to form a squeeze bearing. A layer (4) of piezoelectric, magnetostrictive or electrostrictive material is laminated with a layer (6) of another material to provide cupping and uncupping of the transducer disc of the bearing when electrically excited by an oscillator (22), so that the transducer disc is able to fly above the bearing surface on a fluid which is usually ambient air compressed by the mechanical oscillation of the transducer disc at an ultrasonic frequency. The disc is connected mechanically to an object to be supported and to its electrical sources of energy at points along the locus (20) of zero or minimal oscillation. This locus is a nodal circle. A tubular bearing of laminated form has interdigitated electrodes.

Machining tool holder for machine tool

Abstract: PURPOSE:To increase the accuracy of rotation of a tool and to prevent the entry of fine dust into the tool holder, to thereby improve the reproductivity of the accuracy of tool position at the time of tool exchange by a method wherein the tool holder itself is directly supported by fluid bearings and high pressure air is supplied to the bearings. CONSTITUTION:The tool holder 2 holding a tool within a housing section 1 fixed to the body of a machine tool and capable of being driven rotatably is supported by fluid bearing sections 3a and 3b. A rotor section 5a is provided in a holder 2 so as to rotate the latter and a stator 5b is provided in the housing section 1, to thereby constitute a motor-driven rotary drive device. The fluid bearing sections 3a and 3b are so formed that high pressure air is supplied to the sections through a supply passage A. For the bearings, a porous material such as ceramics is used. Further, to balance a thrust force applied on the bearings, magnets 4a and 4b are provided so as to prevent the tool holder from slipping out.

Exhaust turbine supercharger

Abstract: PURPOSE:To prevent abrasion of a rotary shaft and air bearings due to frictional contact therebetween, by a method wherein, during the starting of an exhaust turbine, the air bearings, supporting the rotary shaft, are adapted to act as a static pressure type air bearing by dint of a compressed air fed from a compressor. CONSTITUTION:Right after an exhaust turbine 1 starts, on-off valves 13 and 14 of a shunt valve 11 are forced into an opened condition through the spring force of springs 15 and 16, and a conduit 10B connected to an exhaust turbine supercharger 1 is closed by the on-off valve 13. Thereby, all of exhaust gas exhausted from an engine 8 is introduced to a turbine rotor 23 of an exhaust turbine compressor 21 through openings 14a and 13a of the on-off valves 14 and 13 and the exhaust gas flow-out port 30 of a casing 12. The compressed air exhausted from the casing 28 of the vane 23 of the compressor is introduced to air bearings 5 of the exhaust turbine supercharger 1 through conduits 20 and 29, and as a result, the air bearings 5 form a static pressure type air bearings to force a rotary shaft 4 to float away therefrom.

Correcting device for degree of straight of straight travelling table

Abstract: PURPOSE:To perform an easy correction of a travelling table to a high-precise degree of straight, by a method wherein a set value coincides with a displacement through adjustment of a fluid pressure fed to side static pressure fluid bearings mounted in a plural number of spots at both sides of the travelling direction of the travelling table. CONSTITUTION:Two measuring reference blocks 12a and 12b are mounted at one side of a Y-direction, being perpendicular to an X-direction of a travelling table 2 and at a distance in the X-direction. A displacement meter 12a is situated facing and opposite to the measuring reference block 12a and in the proximity of a bearing 6a of two side air bearings 6a and 6b, and a displacement meter 13b is located facing and opposite to the measuring reference block 12b and in the proximity of a side air bearing 6c of side air bearings 6c and 6d. In the two displacement meters 13a and 13b, for example, an electrostatic capacity type non-contact minute displacement meter is employed to detect a minute displacement of an object as a change in electrostatic capacity, and this permits the measurement of a minute displacement of 0.1mum or less.

Read/write head-positioning apparatus for a magnetic recording disk drive unit

Abstract: Head positioning apparatus for a magnetic disk drive unit (10) including a disk pack portion (12) and a head-positioning portion (14), the latter employing a linear magnetic induction motor (22) for accurately positioning an associated head (20) relative to the disk pack portion (12) while permitting efficient assembly of the head-positioning portion (14) due to the arrangement of slide bearing shafts (30, 32) on the outside of the motor (22) and the use of an adjustable lever arm (38) and a bracket (48) at respective ends of the slide bearing shafts (30, 32). Fluid bearings are used throughout, with the disk pack portion (12) employing a fluid thrust bearing (88) in a means for coupling a plurality of disks (80) to an associated drive motor (86) in order to isolate the disks (80) from axial fluctuations of the motor armature (90) along its axis of rotation and prevent damage to the disks.

A Study on Characteristics of Externally Pressurized Gas Thrust Bearings with Surface-restriction Compensation : Continued Report ; Dynamic Bearing Characteristics

Abstract: An externally pressurized gas-lubricated thrust bearing with surface-restriction compensation is analyzed theoretically for the hydrodynamic bearing characteristics such as the dynamic stiffness and the damping coefficient applying two kinds of gas flow models ; one considers an equivalent recessed thrust bearing neglecting the circumferential flow in the bearing clearance, and the other takes into account the effect of the circumferential flow by a simple evaluation of it. The theoretical results are discussed by comparing with the experimental ones. The design criterion of the bearing with the surface-restriction compensation is also discussed from the results of theoretical calculations.

Rotary type positioning mechanism for magnetic disk device

Abstract: PURPOSE:To prevent an evil effect to a servo loop, by loading a radial bearing consisting of a thrust bearing and a fluid bearing between a rotor and a static object of the rotary positioning mechanism of a magnetic disk device that supports an arm in a rotatable way. CONSTITUTION:A thrust bearing 4 is attached at the lower end of a rotor 5; while a main hole 7 is formed within a shaft bearing the rotor 5 to secure the passing of a fluid. Then microholes 8 are drilled toward the outer circumference from the hole 7. The fluid 14 is accelerated by the holes 8 after passing through the hole 7 and jetted toward the rotor 5 at the position of a microgap 11 provided between the rotor 5 and the shaft 6. Thus the rotor 5 floats up to the shaft 6 to form a radial fluid bearing. The floating rotor 5 is pressed toward the lower part of the axial line of the shaft 6 by a spring 12 provided at the upper part of the shaft 6.

Weight measuring device

Abstract: PURPOSE:To improve the accuracy of measurement of the fine quantity change of a >=1kg object by supporting the central fulcrum of the weight beams of a balance with plural static pressure fluid bearings, and installing load meters of high accuracy to the opposite top and bottom of an arbitrary point of one beam. CONSTITUTION:A shaft 1 corresponding to the central fulcrum of a balance is supported by plural static pressure fluid bearings 2, 3, and is kept floated completely by the fluid film of the static pressure fluid supplied through fluid supply holes 4. A V groove 7 is provided to the arbitrary position of one beam 5 of the shaft 1 and an object 9 to be measured is suspended therefrom by means of yarn 8. A balance weight 10 is provided freely movably to the other beam 6, and a load measuring point is provided at an arbitrary point. Load meters 11, 12 are installed to the opposite top and bottom thereof. Further, holding mechanisms 13, 14 for fixing or moving the meter 12 are porovided. Strain gages of 0.1% accuracy and max. 5g capacity are utilized for the meters 11, 12, the ratios between the value to be measured and the levers installed to the meters 11, 12 are set at 10 times, whereby 0.5mg sensitivity is easily obtained.

Support for swing table of cam grinder

Abstract: PURPOSE:To reduce wear of a swing supporting part, maintain the precision for a long peried of time, and to enhance the grinding accuracy by providing the swing supporting part of swing table with perfect fluid lubricated state using a fluid bearing. CONSTITUTION:The spindle 5 extending in the longitudinal direction of a swing table 4 is born by a bearing 5 rotatably and equipped with a master cam 7. A bearing hole 12 is formed in the undersurface of the table 4 at its spindle side and tail stock side and, in this hole 12, the supporting shaft 14 is fitted with a minute clearance through a fluid bearing in such a way as capable of relative rotation. The fluid bearing to provide perfect fluid lubricated state for the fit surfaces of the bearing hole 12 and supporting shaft 14 between is formed divided axially into two parts so that this state covers the whole fit zone, and a throttle 25 is furnished at a communication hole 24 between a bearing pocket 22 and a passage 23.

Scanning system employing a laser beam

Abstract: A scanning system using at least one mirror for scanning material to read (or alternatively to be written upon) with a laser beam is provided. Air under pressure is fed into a hollow shaft and escapes through a turbine on the shaft to rotate the shaft. The shaft is supported by air bearings. The shaft rotates the mirror during scanning. Air pressure escaping from the air bearings is vented to the ambient atmosphere. Two special thrust bearings are provided to improve the stability of the shaft. Each thrust bearing applies a force on the shaft in a direction parallel to the axis of the shaft and opposite to the force applied by the other thrust bearing. Each thrust bearing comprises a cavity in the housing, a flat plate attached to the shaft, and a porous bronze plate between the cavity and the flat plate. The air pressures in the two cavities are separately adjustable to enable the operator to select pressures that provide the system with maximum stability. The air under pressure in each cavity passes through the porous bronze plate associated with the cavity to apply pressure to the flat plate (that is attached to the shaft) associated with the cavity.

Projecting and printing device

Abstract: PURPOSE:To facilitate the precision controlling for the linearity of two guide rails and to prevent the deviation in a mask image by disposing means of compensating the nonlinearity of the one guide member between the one guide and the other guide. CONSTITUTION:The arms 25 fixed by coupling members 24 are supported afloat to guide members 26 by means of air bearings or the like. The pads 31 of the air bearings are connected to high pressure air sources so that high pressure air is flowed out therefrom. More specifically, six pieces of the upper, lower, right and left pads 31 are provided to the arm 25 on the right side, and two pieces of the upper, lower pads 31 are provided. The air bearings on the right side form bearings for restraining in all directions, and the bearings on the right side form bearings for restraining upper and lower directions. The bearings on the left side are made lower in rigidity in both vertical and lateral directions than the bearings on the right side. Thereby, the precision controlling for linearily is made relatively easy.