Abstract: An apparatus for detecting machining conditions in a machine tool has a magnetic bearing for magnetically supporting a work spindle or a tool spindle. An exciting current detector is provided for detecting an exciting current of an electromagnet of the magnetic bearing. The exciting current corresponds to various machining conditions including the conditions when the machine tool starts operating, the tool contacts the workpiece to follow various unfinished faces, and a machining face condition of the workpiece during machining. The detection signals from the exciting current detector are inputted to a plurality of frequency band pass filters to discriminate the machining conditions. Comparators are provided to compare the output signals from the frequency band pass filters with a predetermined set of reference values, and comparative judgment signals are inputted to a control unit, thereby controlling the machine tool to automatically perform appropriate machining operations.

Abstract: A clamp mechanism for disks is provided with a clamp body having a reference surface for use in fixing a disk thereon, a plurality of claws adapted to press the disk, which is placed on the reference surface of the clamp body, against the same reference surface and fix the same thereon, a plurality of clamp members which have the claws attached thereto, and which are adapted to be moved vertically in the interior of the clamp body, and cams adapted to turn the clamp members in the radial direction of the disk while the clamp members are vertically moved, in such a manner that the claws come toward one another or go farther away from one another. Each of the claws is formed generally to the shape of a fan. Therefore, the clamp portions of the claws which contact the disk, can press about 70-80% of the total area of the circumferential portion of the central hole in the disk.

Abstract: A helium gas compressing apparatus constructed in such as manner that: an oil separator in a high-pressure gas passage is connected to a low-pressure gas passage; and oil return path having first and second branch paths is provided between the high- and low-pressure gas passages; a capillary tube is installed in one of the two branch paths; and an adjustment valve is installed in the other branch path to adjust the pressure difference between the supply gas in the high-pressure gas passage and the return gas in the low-pressure gas passage. Because of this construction, the adjustment valve can be manipulated from outside to make fine adjustments on the pressure difference or change it to a desired value with ease even during operation of the apparatus, thereby adjusting the refrigerating capability of a helium refrigerating machine connected to the apparatus and the power consumption of the helium gas compressing apparatus.

Abstract: The control system is provided in a grinding machine composed of an axially movable rotational shaft having a grinding tool and being supported magnetically by electromagnets. The control system includes a target position modifying controller for modifying or shifting a reference target levitating position of the rotational shaft in a retreating direction away from a workpiece reaches a predetermined amount. The control system further includes a rigidity modifying controller operative during quick feed operation of the rotational shaft for making a rigidity of the rotational shaft lower than that in the grinding operation by adjusting exciting currents of the electromagnets. The control system still further includes a dressing controller operative during dressing of a new grinding tool for detecting that the grinding tool begins to touch a dresser and for judging that the dressing is completed just when an arithmetic value calculated based on the detection reaches a predetermined value.

Abstract: A numerical control device for a grinding machine is equipped with a servo-motor which moves at least one of a spindle and a dresser. The spindle and/or the dresser moves relative to the dresser shaft center direction and the rotor shaft center direction. The numerical control device compensates an amount of servo lag using a target position compensation calculating circuit. A unit time target position is obtained by performing a track calculation at unit times on the basis of the amount of servo lag stored in a storage device. Feedback control of the servo motor is effected by calculating a compensated target position dependent on the unit time target position.

Abstract: A method for controlling an initial position of a magnetically levitated body comprises sensing the position of the levitated body by position sensors and applying exciting currents to electromagnets in response to the sensed position to adjust the position of the body to an initial central position. The sensing step comprises detecting a first limiting position of the body in a first direction and detecting a second limiting position of the body in a second direction opposite the first direction. The applying step comprises calculating a central position from the first and second limiting positions and applying exciting currents to the electromagnets to move the body into the calculated central position. An apparatus for controlling positioning of a magnetically levitated body based on limiting positions is also disclosed.

Abstract: A damper device for a motor having a boss section attached to a rotary shaft of the motor, a mass inertia section rotatably supported by the boss section such that it surrounds the outer periphery of the boss section with a gap left therebetween, a magnetic fluid filling up the gap, and magnets provided in either the boss section or the mass inertia section for preventing leakage of the magnetic fluid. Furthermore, the boss section and the mass section facing each other through the gap are made of materials differing in the coefficient of thermal expansion, even if the magnetic fluid is heated by heating of the motor, an external temperature variation and the like so that its viscosity is decreased, such a decrease in viscosity can be canceled out by a change in gap dimension caused by the difference in expansion between the boss section material and the mass section material differing in the coefficient of thermal expansion.

Abstract: Hard disk testing apparatus and method having a plurality of heads mounted on a carriage capable of moving in the direction of a hard disc at intervals defined by dividing the radius of the hard disc, write circuit for writing a test signal through the heads in the hard disc, read circuit for reading a signal written through the heads, and measuring function for measuring a separation between one head of the heads and another head of the heads provided adjacent to the one head based on a shift distance of the another head shifted to read a signal written by the one head. A separation of the heads is accurately measured without a measuring device, and micro adjustment of positions of the heads based on the measured separation is not required. The possibility of double testing of or failure in testing tracks on the border is eliminated, and thereby disc test is efficiently performed.

Abstract: In a turbomolecular pump, the blade angle of each of rotor blades relative to the plane of a rotor gradually decreases from its base toward its outer most periphery, and the opening ratio and relative blade interval of said rotor blades are made substantially constant from the base of the rotor blade to the outer most periphery of said rotor blade.

Abstract: A hard disk testing apparatus is comprised of a pair of carriages, each provided with a pair of upper and lower heads, and one of the upper and lower heads on either of the carriages is mounted on a micro adjustment carriage. With this structure, the head mounted on the fixed carriage writes a signal, and the head mounted on the carriage equipped with the micro adjustment carriage reads the signal. The structure and operation of the apparatus effectively prevent omission or duplication of testing tracks at the border between a test range of a hard disk covered by one of the pair of carriages and another test range covered by the other carriage.

Abstract: A machining apparatus having a main spindle supported by magnetic bearings which controls machining conditions by controlling electric current values flowing in electromagnets according to predetermined conditions, thereby obtaining an optimum machining condition and thus improving accuracy and machining efficiency. The machining apparatus comprises a spindle having a tool at its one end, electromagnets for radially and axially supporting the spindle by magnetic force without contact to the spindle, position detecting means for detecting radial and axial positions of the spindle, control means responsive to outputs from the position detecting means for controlling current flowing in the electromagnets, current measuring means for measuring current values flowing in at least one of the electromagnets, and machining control means for controlling machining conditions by controlling current values at the electromagnets according to the measured current values.

Abstract: A control system is provided in a grinding machine composed of an axially movable rotational shaft having a grinding tool and being supported magnetically by electromagnets. The control system includes a target position modifying controller for modifying or shifting a reference target levitating position of the rotational shaft in a retreating direction away from a workpiece reaches a predetermined amount. The control system further includes a rigidity modifying controller operative during quick feed operation of the rotational shaft for making a rigidity of the rotational shaft lower than that in the grinding operation by adjusting exciting currents of the electromagnets. The control system still further includes a dressing controller operative during dressing of a new grinding tool for detecting that the grinding tool begins to touch a dresser and for judging that the dressing is completed just when an arithmetic value calculated based on the detection reaches a predetermined value.

Abstract: A grinder with a deflection sensor for controlling the grinding work conditions based on an amount of deflection of a grinding shaft occurring in the normal direction relative to the grinding shaft which is detected by measuring inductance with the deflection sensor. Based on a deflection of the grinding shaft detected during grinding work, the feed of the grinder is controlled, and the sharpness of the grinder is determined based on changes of the detected deflection amount during spark-out, moreover an error in the signal from the deflection detector caused by a thermal change can be compensated, whereby grinding work is carried out under an optimum condition, and the grinding accuracy and efficiency are improved.

Abstract: An internal grinding apparatus having a grinding wheel attached to a spindle rotor radially and axially supported by electromagnetic bearings. Currents applied to the electromagnetic bearings are continuously controlled by a controlling system including a central processing unit during grinding work in order to adjust the longitudinal axis of the spindle rotor. The longitudinal axis of the spindle rotor is inclined and/or shifted at predetermined locations of the grinding wheel in a bore of a workpiece, thereby eliminating tapering of the long bore, and improving the cylindricality and straightness in grinding work.

Abstract: In an internal grinding machine of the type in which a workpiece is supported by three contact points by a fixed shoe and two rolls, the present invention facilitates correct feed and discharge of workpieces one by one without regard to the diameter of a workpiece. This is made possible by furnishing an internal grinding machine with a workpiece guide plate having a V-shape projection at its underside by the side of an upper roll in such a manner that the workpiece guide plate can swing up and down. When a workpiece is fed, the workpiece temporarily pushes up the V-shape projection, then reaches the end of the shoe. And it is pushed downward at the end of the shoe by the end portion of the workpiece guide plate, and is fed into the support space. When a finished workpiece is pushed by the workpiece newly fed in the manner as described above and discharged from the support space, the finished workpiece temporarily pushes up the said V-shape projection and is discharged.

Abstract: A rotary compressor is comprised of a first housing having an intake chamber for receiving therein a fluid of variable pressure, and a second housing having an inner peripheral surface to define a working chamber and an inlet communicating between the working and intake chambers. A rotor is rotatably mounted in the working chamber and has a vane slidably supported in the rotor to maintain contact with the inner peripheral surface of the second housing during the rotation of the rotor to thereby compress the fluid flowing into the working chamber through the inlet. A rotary valve is rotatably disposed between the intake chamber and working chamber for regulating the flow rate of the fluid flowing through the inlet in response to angular displacement of the rotary valve. A piston is slidably disposed in a cylinder provided in the first housing.

Abstract: A gas compressor of the variable volume type having a rotary plate which is rotated to move recesses therein communicating with a compression chamber of a cylinder relative to communication ports formed in a front side block fixed to the one side of the cylinder so that the volume of the compression chamber may be made variable in accordance with the fast or slow running state of the gas compressor. The rotary plate is moved rotatably by means of a self-contained and self-actuated hydraulic cylinder which is driven by oil within the compressor in response to the intake pressure of the compressor's intake chamber.

Abstract: A rotary vane compressor has a cylinder having an oval-shaped compartment in which is rotatably mounted a rotor. Front and rear side blocks close the opposite ends of the cylinder. A plurality of vanes are slidably mounted in slots formed around the rotor and divide the cylinder compartment into expansible working chambers. A gas inlet opening is disposed at the upstream end of each working chamber for admitting a gas to be compressed and a gas outlet opening is disposed at the downstream end of each working chamber for discharging the compressed gas. A source of pressurized lubricant oil is fed to the base of the vane slots to bias the vanes outwardly so that the vane tips slidably engage the inner wall of the cylinder compartment during rotation of the rotor.

Abstract: The present invention provides an inspection apparatus for inspecting an object such as an information storage medium or an information recording/reproducing head under set inspection conditions, which comprises: a sensor for identifying the type of object set for inspection by its size, and automatic inspection condition setting means for automatically setting the inspection conditions for the object to be inspected which are associated with the type identified.

Abstract: Sizing apparatus for an internal grinder having an oscillation motor for oscillating a grinder wheel contacting the inner peripheral surface of an annular work piece, a sizing device to generate sizing signals for measuring the bore of the work piece, a measuring probe connected to the sizing device, a probe position sensor for sensing positions of the measuring probe in an axial direction of the bore of the work piece with reference to a rotation angle of a drive shaft of the oscillation motor, and a sizing signal sampler for sampling sizing signals when positions of the measuring probe are inside the bore of the work piece. The sizing apparatus for an internal grinder is capable of measuring the bore of the work piece during an oscillation machining despite the smallness of the bore and size in the axial direction of the work piece.