US20070212248A1 - Production method for fluid dynamic pressure sintered bearing - Google Patents

Production method for fluid dynamic pressure sintered bearing Download PDF

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Publication number
US20070212248A1
US20070212248A1 US11/709,802 US70980207A US2007212248A1 US 20070212248 A1 US20070212248 A1 US 20070212248A1 US 70980207 A US70980207 A US 70980207A US 2007212248 A1 US2007212248 A1 US 2007212248A1
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US
United States
Prior art keywords
bearing
sintered bearing
dynamic pressure
fluid dynamic
barreling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US11/709,802
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English (en)
Inventor
Katsutoshi Nii
Zenzo Ishijima
Takahiro Jinushi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Resonac Corp
Original Assignee
Hitachi Powdered Metals Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Powdered Metals Co Ltd filed Critical Hitachi Powdered Metals Co Ltd
Assigned to HITACHI POWDERED METALS CO., LTD. reassignment HITACHI POWDERED METALS CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ISHIJIMA, ZENZO, JINUSHI, TAKAHIRO, NII, KATSUTOSHI
Publication of US20070212248A1 publication Critical patent/US20070212248A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • B22F3/26—Impregnating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • B22F5/106—Tube or ring forms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/20—Sliding surface consisting mainly of plastics
    • F16C33/201—Composition of the plastic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

  • the present invention relates to a production method for a fluid dynamic pressure bearing composed of a sintered compact.
  • the present invention relates to a production method for a fluid dynamic pressure sintered bearing which is desirably used for compact driving motors of various information devices, for example, the driving motors being driving sources of disc drive devices (which read and write information from and to a magnetic disc or an optical disc such a CD or a DVD) or polygon motors of laser printers.
  • Grooves for generating a fluid dynamic pressure are formed on bearing surfaces (an inner peripheral surface and an end surface) on which the shaft slides, so that the generated fluid dynamic pressure can be effectively obtained.
  • the grooves may be herringbone grooves or spiral grooves (see Japanese Unexamined Patent Application Publication No. 2003-262217).
  • the fluid dynamic pressure sintered bearing has pores.
  • a fluid dynamic pressure sintered bearing for compact motors has a porosity of about 15 vol %.
  • lubricating oil infiltrates the pores of the bearing, the pressure of oil film is decreased, so that effects of fluid dynamic pressure are decreased.
  • the sealing of at least the pores on the bearing surface is desirable and the decrease of fluid dynamic pressure is thereby prevented.
  • the sealing uses mechanical impacting (for example, shot blasting or sand blasting) or infiltration of suitable resin into pores (see Japanese Unexamined Patent Application Publication No. Hei 11-62948).
  • an object of the present invention is to provide a production method for a fluid dynamic pressure sintered bearing, which can prevent change of the bearing in size after repressing and thereby can improve size precision of the bearing, thereby improving rotational performances of high speed and high precision and bearing properties of low noise.
  • a production method for a fluid dynamic pressure sintered bearing includes: preparing a sintered bearing having a porosity of 8 to 20 vol % as a material; and controlling at least one of an overall length, an outer diameter, and an inner diameter of the sintered bearing by repressing the sintered bearing.
  • the production method further includes: forming grooves for generating a fluid dynamic pressure on a bearing surface of the sintered bearing by performing repressing and plastic working on the sintered bearing; and sealing pores exposed on the bearing surface by infiltrating a resin into at least the pores; and barreling entire surface of the sintered bearing by magnetic barreling or electromagnetic barreling.
  • the fluid dynamic pressure sintered bearing is obtained as follows. That is, both the size control of the whole sintered bearing and the formation of the grooves on the bearing surface are performed by the repressing. Next, the pores exposed on the bearing surface are sealed by the resin infiltration. Finally, the sintered bearing is subjected to the magnetic barreling or the electromagnetic barreling. Thus, the fluid dynamic pressure sintered bearing is obtained in the above process order.
  • the sealing of the pores is first performed by the resin infiltration, in comparison with a case sealing is performed by mechanical impacting (for example, shot blasting), deformation of the grooves, the inner peripheral surface supporting the shaft, and the like can be prevented, and decrease in the fluid dynamic pressure can be prevented by the sufficiently sealing of the pores.
  • the resin remaining on the surface of the sintered bearing after water washing of resin causes decrease in size precision.
  • the resin remaining on the surface is removed by the barreling, so that size precision of the sintered bearing can be secured. Since the resin infiltration is performed after the all repressing, adhesion of the resin to the male die for the repressing can be prevented, so that deterioration of size precision, which may be caused by the adhesion, can be prevented.
  • the sintered bearing is simply composed of sintered compact having the unsealed pores, the spring back after the repressing of the sintered bearing and the ejection of the sintered bearing from the die is maintained to be small and the transfer properties of the fluid dynamic pressure grooves onto the sintered bearing are maintained to be good.
  • the barreling of the present invention is limited to magnetic barreling or electromagnetic barreling.
  • these barreling in a barrel (vessel) having a spatial magnetic field generated therein, works are agitated together with plural fine media, and the media give impacts to the works, so that a fine burr and irregularity existing on surfaces of the works are removed and the surfaces of the works are thereby flat and smooth.
  • these barreling are typical methods which are desirably used for final finishing of works having complex shapes.
  • these barreling can give impact effects of the media to the inner peripheral surface of the bearing without damaging the shapes of the fluid dynamic pressure grooves formed on the bearing.
  • the resin which remains on the surface after the cleaning of the bearing in the above manner, is removed, so that the bearing surface becomes clean.
  • the remaining pores are closed by plastic flow due to the impacts of media, thereby being completely sealed.
  • a resin coating layer can be formed on the entire surface which includes the inner peripheral surface.
  • the resin coating layer can be composed of a fluororesin and have a thickness of 5 ⁇ m or less. Since the entire surface is oil-repellent to the lubricating oil by the resin coating, even when the pores remain inside the bearing, the infiltration of the lubricating oil into the bearing can be prevented, so that fluid dynamic pressure effects can be more improved.
  • both the size control of the whole sintered bearing and the formation of the fluid dynamic pressure grooves on the bearing surface are performed by the repressing.
  • the pores are sealed by the resin infiltration, and the sintered bearing is subjected to the magnetic barreling or the electromagnetic barreling.
  • FIG. 1 is a longitudinal cross sectional view showing a fluid dynamic pressure sintered bearing produced by a production method of an embodiment according to the present invention.
  • FIG. 2 is a plan view showing the fluid dynamic pressure bearing shown in FIG. 1 .
  • FIG. 3 is a cross sectional view showing the fluid dynamic pressure bearing shown in FIG. 1 .
  • FIG. 4 is a diagram showing a process order of the production method of the embodiment.
  • FIG. 1 is a longitudinal cross sectional view showing a fluid dynamic pressure sintered bearing 1 (hereinafter simply referred to “bearing”).
  • the bearing 1 is cylindrical and is produced by a production method of the embodiment according to the present invention.
  • FIG. 2 is a plan view showing the bearing 1 shown in FIG. 1 .
  • FIG. 3 is a cross sectional view showing the bearing 1 shown in FIG. 1 .
  • the bearing 1 is a compact bearing which is desirably used for spindle motors of magnetic record disc drive devices.
  • the bearing 1 has an outer diameter of about 5 to 6 mm and an inner diameter (that is, a diameter of shaft hole 11 ) of about 2 to 3 mm.
  • the bearing 1 is composed of a sintered compact obtained by sintering a green compact formed by compacting a raw metal powder.
  • the bearing 1 has a porosity of 8 to 20 vol %. In practical use of the bearing 1 , lubricating oil infiltrates pores of the bearing, so that an oil-impregnated sintered bearing is obtained.
  • the bearing 1 rotatably supports a shaft (denoted by reference numeral 2 shown in FIG. 3 ) which is inserted into the shaft hole 11 of the bearing 1 .
  • the shaft 2 has a shaft body, which is inserted into the shaft hole 11 , and a flange which is formed on the shaft body.
  • the shaft body 2 is inserted into the shaft hole 11 from the upside, and the flange faces an upper surface of the bearing 1 .
  • a radial load of the shaft 2 is supported by an inner peripheral surface 13 of the bearing 1
  • a thrust load of the shaft 2 is supported by an upper surface 12 of the bearing 1 .
  • spiral grooves 14 are formed at equal intervals in one circumferential direction.
  • the spiral grooves 14 extend so as to inwardly curve toward a rotation direction R of the shaft 2 .
  • the spiral grooves 14 are shown by using hatched lines so as to be distinguished from the upper surface 12 . End portions on peripheral sides of the spiral grooves 14 open to a peripheral surface. End portions on inner peripheral sides of the spiral grooves 14 do not open to an inner peripheral surface 13 of the shaft hole 11 so as to close.
  • the number of the spiral grooves 14 is about 10 (for example, 12 in FIG. 2 ).
  • the maximum depth of the spiral groove 14 is about 10 to 20 ⁇ m.
  • plural separation grooves 15 are formed at equal intervals in a circumferential direction on the inner peripheral surface 13 of the shaft hole 11 of the bearing 1 .
  • the separation grooves 15 are semi-circular arcs in cross section, and straightly extend from one end surface of the bearing 1 to the other end surface thereof in an axial direction.
  • Eccentric grooves 16 are formed between the respective separation grooves 15 of the inner peripheral surface 13 . Centers of the eccentric grooves 16 are eccentric with respect to an axial center P of the outer diameter of the bearing 1 .
  • the eccentric grooves 16 are inwardly biased toward one rotation direction of the shaft 2 shown by an arrow R.
  • the number of the separation grooves 15 is 5, and the number of the eccentric grooves 16 is 5. These numbers are desirably 3 to 6.
  • a small gap between the inner surfaces of the eccentric grooves 16 and a peripheral circumferential surface of the shaft 2 is wedge-shaped in cross section so as to be gradually narrower and smaller in the rotation direction of the shaft 2 .
  • the separation groove 15 has a width corresponding to an angle ? of 8 to 20 degrees in the circumferential direction having the axial center P as a center as shown in FIG. 3 .
  • the separation groove 15 has a maximum depth of about 0.10 mm.
  • a bearing gap of radial side is formed between the inner peripheral surface 13 of the bearing 1 and the peripheral surface of the shaft body of the shaft 2 inserted into the shaft hole 11 .
  • a bearing gap of thrust side is formed between the upper end surface 12 of the bearing 1 and the flange of the shaft 2 .
  • Lubricating oil is supplied into the bearing gaps.
  • the bearing gap of radial side has a width of about 1 to 3 ⁇ m
  • the bearing gap of thrust side has a width of about 5 to 10 ⁇ m.
  • the lubricating oil is exuded to the respective spiral grooves 14 formed on the upper end surface 12 of the bearing 1 , and is held therein.
  • One portion of the lubricating oil held therein is moved from the respective spiral grooves 14 by the rotation of the shaft 2 , so that an oil film thereof is formed between the upper end surface 11 and the flange.
  • the lubricating oil held in each spiral groove 14 flows from the peripheral side of each spiral groove 14 to the inner peripheral side thereof, so that a thrust fluid dynamic pressure is generated and it is highest at an end portion on the inner peripheral side thereof.
  • the flange receives the thrust fluid dynamic pressure, so that the shaft 2 is floated by small amount. As a result, the thrust load of the shaft 2 is supported with high stiffness in a well-balanced manner.
  • FIG. 4 is a diagram showing a process order of the production method.
  • a raw powder of a metal powder is compacted, so that a green compact, which has a near net shape corresponding to the bearing 1 , is obtained.
  • the green compact is provided in a sintering furnace and is sintered therein, so that a sintering compact having a porosity of 8 to 20 vol % is obtained as a material.
  • the obtained sintered bearing is set in a die having a predetermined shape and it is repressed therein, so that an outer diameter, an inner diameter, and axial direction length (height) of the sintered bearing are controlled with a required size precision.
  • a core having protrusions corresponding to the above spiral grooves 14 spiral grooves 14 are transferred and formed on one end surface (the above upper end surface 12 ) of the sintered bearing which has the controlled size.
  • separation grooves 15 and eccentric grooves 16 are transferred and formed on an inner peripheral surface 13 of the sintered bearing.
  • the sintered bearing which has the spiral grooves 14 formed on the other end surface and the separation grooves 15 and the eccentric grooves 16 formed on the inner peripheral surface 13 is immersed in a resin solution in vacuum condition. Next, the sintered bearing is opened to the air. A resin solution is infiltrated into pores of the sintered bearing by pressure difference between vacuum and the air. An anaerobic adhesive which is mainly composed of polyglycol dimethacrylate is desirably used as the resin for the infiltration. The resin is cured by heating after being infiltrated into the sintered bearing. Since the infiltrated resin is adhered so as to cover the entire surface of the sintered bearing, the resin on the entire surface including the inner peripheral surface 13 is removed by water washing before the resin is cured.
  • the sintered bearing of which the pores are sealed by the resin infiltration, is subjected to magnetic barreling or electromagnetic barreling.
  • Fine stainless pin having a diameter of about 0.5 mm is desirably used as media for the barreling.
  • Many media give impacts to the surface of the sintered bearing by the magnetic barreling or the electromagnetic barreling.
  • the entire surface of the sintered bearing which includes the end surface having the spiral grooves 14 formed thereon and the inner peripheral surface 13 having the separation grooves 15 and eccentric grooves 16 formed thereon, is subjected to barreling by the media.
  • the resin which is adhered to the surface of the sintered bearing and cannot be removed by the water washing, is completely removed, and the surface thereof becomes clean.
  • the infiltrated resin is the anaerobic adhesive
  • the volume of the resin expands in the curing by the heating, and the resin is exuded to the surface of the sintered bearing, so that the small amount of the resin may remain on the surface of the sintered bearing.
  • the pores are filled with the resin and the sintered bearing is cooled to room temperature after the curing, the store of the resin contracts, so that the small amount of the pores remains.
  • the surface of the sintered bearing is subjected to the barreling, so that the remaining resin is removed or the remaining pores are closed by plastic flow due to the impacts of media and completely sealed.
  • the entire surface of the sintered bearing, which was subjected to the barreling, is covered with a resin by the following coating method, so that a resin coating layer is formed thereon.
  • the sintered bearing is immersed in a resin solution for coating or a resin resolution for coating is sprayed onto the entire surface of the sintered bearing.
  • a material of the resin may be acrylic one or epoxy one.
  • the material of the resin is desirably composed of fluororesin which is quick-drying and is superior in oil repellency.
  • the coating layer has a thickness of 5 ⁇ m or less, and desirably has a thickness of about 1 ⁇ m.
  • the size control of the whole sintered bearing is performed by the repressing.
  • the formation of the spiral grooves 14 on the upper surface 12 and the formation of the separation grooves 15 and the eccentric grooves 16 on the inner peripheral surface 13 are performed by the repressing.
  • the sealing of the pores by the resin infiltration, the barreling (magnetic barreling or electromagnetic barreling), and the resin coating are performed in this process order.
  • the fluid dynamic pressure sintered bearing is obtained.
  • the sintered bearing Since in the repressing, the sintered bearing is simply composed of sintered compact having the unsealed pores, the spring back after the repressing of the sintered bearing and the ejection of the sintered bearing from the die is maintained to be small, and the transfer properties of the fluid dynamic pressure grooves onto the sintered bearing are maintained to be good. Since the sintered bearing is subjected to the barreling after the resin infiltration and the entire surface of the sintered bearing is polished, the resin remaining on the surface or the pores remaining thereon are removed by the barreling, so that the size precision can be maintained. Due to these, in the obtained fluid dynamic pressure sintered bearing, the pores can be sufficiently sealed and the decrease of fluid dynamic pressure can be prevented. In addition, since the size precision can be improved, bearing performances (for example, rotational performance of high speed and high precision, and low noise) can be improved.
  • the resin coating layer can be formed to be good.
  • a Fe—Cu based metal material is often used therefor from a view point of the time of initial running-in and the strength, but this material easily rusts in the air.
  • the resin coating layer is formed on the surface of the sintered bearing, the water repellent effects can be improved, and the rusting can be effectively prevented.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Sliding-Contact Bearings (AREA)
US11/709,802 2006-03-02 2007-02-23 Production method for fluid dynamic pressure sintered bearing Abandoned US20070212248A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2006-055685 2006-03-02
JP2006055685A JP2007232113A (ja) 2006-03-02 2006-03-02 焼結動圧軸受の製造方法

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US20070212248A1 true US20070212248A1 (en) 2007-09-13

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US11/709,802 Abandoned US20070212248A1 (en) 2006-03-02 2007-02-23 Production method for fluid dynamic pressure sintered bearing

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JP (1) JP2007232113A (ja)
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110175360A1 (en) * 2008-08-26 2011-07-21 Seabased Ab Wave-power unit
EP3096026A4 (en) * 2013-12-11 2017-09-27 NTN Corporation Fluid dynamic bearing device and motor provided therewith
US10099287B2 (en) * 2014-11-28 2018-10-16 Ntn Corporation Dynamic pressure bearing and method for manufacturing same
US10125819B2 (en) 2012-07-26 2018-11-13 Ntn Corporation Sintered bearing
CN113555998A (zh) * 2021-07-29 2021-10-26 中国船舶重工集团公司第七0七研究所 一种带污染过滤装置的动压气浮轴承结构

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5352978B2 (ja) * 2007-09-11 2013-11-27 株式会社ダイヤメット 焼結軸受の製造方法
FR3027074B1 (fr) 2014-10-14 2016-12-09 Snecma Procede de fabrication d'un palier fluide hydrostatique alveole

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110175360A1 (en) * 2008-08-26 2011-07-21 Seabased Ab Wave-power unit
US8664789B2 (en) 2008-08-26 2014-03-04 Seabased Ab Wave-power unit
US10125819B2 (en) 2012-07-26 2018-11-13 Ntn Corporation Sintered bearing
EP3096026A4 (en) * 2013-12-11 2017-09-27 NTN Corporation Fluid dynamic bearing device and motor provided therewith
US10099287B2 (en) * 2014-11-28 2018-10-16 Ntn Corporation Dynamic pressure bearing and method for manufacturing same
CN113555998A (zh) * 2021-07-29 2021-10-26 中国船舶重工集团公司第七0七研究所 一种带污染过滤装置的动压气浮轴承结构

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CN101029658A (zh) 2007-09-05
JP2007232113A (ja) 2007-09-13

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AS Assignment

Owner name: HITACHI POWDERED METALS CO., LTD., JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:NII, KATSUTOSHI;ISHIJIMA, ZENZO;JINUSHI, TAKAHIRO;REEL/FRAME:019201/0644

Effective date: 20070404

STCB Information on status: application discontinuation

Free format text: EXPRESSLY ABANDONED -- DURING EXAMINATION