Roller Structure Or Orientation; Plural Axially Spaced Rows Or Tandem Thrust Patents (Class 384/619)
  • Patent number: 6592265
    Abstract: The invention relates generally to rolling stands (1) for strips and the like, of the type with crossing rolls (10, 11, 12, 13). More specifically, the invention relates to a special bearing (30) which allows the angular adjustment of the crossing rolls (10-13) even under load, that is to say, during rolling. The bearing (30) is interposed between the parts which in the course of the angular adjustment, move relative to one another and onto which the rolling forces are transmitted. According to a preferred embodiment, the bearing of the invention is formed by two rolling-contact thrust bearings superposed eccentrically one above the other.
    Type: Grant
    Filed: December 12, 2000
    Date of Patent: July 15, 2003
    Assignee: SMS Demag Innse SpA
    Inventors: Antonino Rossi, Cesare Maiandi
  • Patent number: 6575631
    Abstract: Into a raceway groove formed between outer and inner races, there are incorporated a plurality of rolling elements of which outside diameters serving as the rolling contact surfaces thereof each has a curvature in the axial direction as well and also each of which has a radius smaller than the radius of the raceway surfaces of the outer and inner races. The rolling elements are arranged in such a manner that the mutually adjoining rolling elements cross each other alternately and also that the outside diameters of the respective rolling elements are always contacted at two points with the raceway surfaces of one race and the raceway surfaces of the other race.
    Type: Grant
    Filed: October 5, 2001
    Date of Patent: June 10, 2003
    Assignee: NSK Ltd.
    Inventors: Yoshio Shoda, Jun Liu, Yukio Sato
  • Publication number: 20030007709
    Abstract: Screw machines having a special internal bearing for the screw shaft, which bearing eliminates the wear of cantilevered screws of single- or multi-shaft screw machines, are described. One or more additional movable bearings, which support the screw shaft and are arranged, spaced from the drive bearing, along the screw shaft, are fitted in the screw machine, the movable bearings having bearing shells of two or more parts and bearing holders of two or more parts.
    Type: Application
    Filed: July 2, 2002
    Publication date: January 9, 2003
    Inventors: Norbert Schweigler, Hartmut Gobel, Thomas-Oliver Neuner
  • Patent number: 6382836
    Abstract: Into a raceway groove 3 formed between outer and inner races 1 and 2, there are incorporated a plurality of rolling elements 5, 5 of which outside diameters 5a serving as the rolling contact surfaces thereof each has a curvature in the axial direction as well and also each of which has a radius smaller than the radius of the raceway surfaces of the outer and inner races. The rolling elements 5 are arranged in such a manner that the mutually adjoining rolling elements 5, 5 cross each other alternately and also that the outside diameters 5a, 5a of the respective rolling elements 5, 5 are always contacted at two points with the raceway surfaces 1a, 1b of one race 1 and the raceway surfaces 2b, 2a of the other race 2.
    Type: Grant
    Filed: May 31, 2000
    Date of Patent: May 7, 2002
    Assignee: NSK, Ltd.
    Inventors: Yoshio Shoda, Jun Liu
  • Patent number: 5984529
    Abstract: Sliding bearings for chocks (11) in back-up rolls (12) under load, the back-up rolls (12) cooperating with the respective working rolls (112) and being able to perform crossed displacement in a four-high rolling mill stand for the hot rolling of sheet and/or large plate, the chocks (11) cooperating on the outside with organs to transmit the load from the rolls to the stationary housing (21) and organs to regulate the gap between the working rolls (112), these organs comprising millscrews, hydraulic capsules (13), spacers, etc.
    Type: Grant
    Filed: June 23, 1997
    Date of Patent: November 16, 1999
    Assignee: Danieli & C. Officine Meccaniche SpA
    Inventors: Fausto Drigani, Cesare Galletti, Giacinto Dal Pan
  • Patent number: 5961221
    Abstract: A cross roller that may rotate at a high speed with high precision is provided. A first conical roller 7 for receiving loads in a first axial direction B and a radial direction and a second conical roller 8 for receiving loads in a second axial direction A and the radial direction are alternatively held by an inner race 3 and an outer race 4. Also, a predetermined space 9 is provided between large end faces 7b and 8b of the first and second conical rollers 7 and 8 and orbital surfaces 4a and 4b of the outer race 4. Then, a seat ring 10 that is elastically deformable is provided in the space 9. By using the conical rollers 7 and 8, a slippage between the orbital surfaces 3a, 3b, 4a and 4b and the rollers 7 and 8 is prevented. Also, the seat ring 10 is elastically deformed so that a suitable pre-pressure is applied to the first and second conical rollers 7 and 8 by its restoring force.
    Type: Grant
    Filed: December 17, 1997
    Date of Patent: October 5, 1999
    Assignee: Namu Co., Ltd.
    Inventor: Ichirou Kamimura
  • Patent number: 5954609
    Abstract: The invention relates to a gear system, particularly an epicyclic gear system, with a basic member (40) with at least one rotatably mounted output member (50), and with an annular running space (1), formed in the bearing region of the output member (50), and with bearing surfaces (40e, 44b, 59a, 59b) for cylinder-like roller members (47, 47'). Some roller members (47) are aligned with respect to the axis of rotation (40a) of the gear system substantially axially, while the other roller members (47') are positioned substantially radially (FIG. 1).
    Type: Grant
    Filed: April 10, 1997
    Date of Patent: September 21, 1999
    Assignee: Spinea s.r.o.
    Inventor: Tibor Fecko
  • Patent number: 5938225
    Abstract: A motorcycle including a frame having a head tube, a fork having a stem positioned within the head tube, and a bearing assembly operatively positioned between the stem and the head tube. The bearing assembly includes a double-row, radial-thrust bearing on one end of the head tube, and a non-thrust radial bearing on the other end of the head tube.
    Type: Grant
    Filed: February 26, 1997
    Date of Patent: August 17, 1999
    Assignee: Harley-Davidson Motor Company
    Inventors: Steven Scheibe, Scott Brooks
  • Patent number: 5811903
    Abstract: A motor comprises a motor rotation shaft, a first thrust bearing which supports one end of the motor rotation shaft and a second thrust bearing which supports the other end of the motor rotation shaft to control positioning in a thrust direction of the motor rotation shaft. The first thrust bearing further comprises a bearing for supporting one end of the motor rotation shaft and is movable in a shaft direction of the motor rotation shaft, a guide member for guiding the movement of the bearing in the shaft direction and a plurality of pre-loaded elements for opposing the force generated by the bearing in the shaft direction. The pre-loaded elements are evenly spaced around the motor shaft.
    Type: Grant
    Filed: September 26, 1996
    Date of Patent: September 22, 1998
    Assignee: Sankyo Seiki Mfg. Co., Ltd.
    Inventors: Toshio Ueno, Fujio Iwashita, Toshio Yamamoto, Shigeru Ozawa
  • Patent number: 5700546
    Abstract: A seal or bearing comprising a combination of a movable member and a stationary member, either one of the movable and stationary members being made of a low thermal expansion coefficient material, and the other being made of a carbon containing material, wherein a sliding surface of the movable or stationary member which is made of the low thermal expansion coefficient material is irradiated with an ion beam consisting essentially of nitrogen ions at the same time as titanium is vacuum-deposited on the sliding surface, thereby forming a thin titanium nitride film on the sliding surface, which provide a seal or bearing which has a reduced coefficient of friction, and which is improved in wear resistance.
    Type: Grant
    Filed: May 30, 1995
    Date of Patent: December 23, 1997
    Assignees: Ebara Corporation, Agency Of Industrial Science and Technology
    Inventors: Kanenaga Fujii, Masato Kiuchi, Hiroshi Nagasaka, Yoshikazu Kimura, Naoki Tsuchiya
  • Patent number: 5676471
    Abstract: Apparatus comprising a lower support structure having an upper surface, a circular lower rail which is mounted on the upper surface of the lower support structure and which is centered on a generally vertical axis, an upper structure having a lower surface, a circular upper rail which is mounted on the lower surface of the upper structure and which is centered on the axis, a plurality of rollers which are located between the upper and lower rails and which support the upper structure for rotation relative to the lower structure about the axis, the rollers being rotatable about respective generally horizontal axes intersecting the vertical axis at a common point, one of the rails including an inwardly facing surface defining a portion of a sphere centered on the point, and each of the rollers including an outwardly facing surface which engages the inwardly facing surface and which defines a portion of a sphere centered on the point.
    Type: Grant
    Filed: September 29, 1995
    Date of Patent: October 14, 1997
    Assignee: Harnischfeger Corporation
    Inventors: Harvey J. Kallenberger, Joseph L. Huffman
  • Patent number: 5667314
    Abstract: A thrust chamber for use in a horizontal hurst apparatus or other pump apparatus is disclosed. The thrust chamber includes a housing, a rotatable shaft mounted within the housing, a first downthrust bearing section connected to the shaft and to the housing, and a second downthrust bearing section also connected to the shaft and the housing. The two downthrust bearing sections are interconnected so that as a downthrust load is placed on the shaft, the first downthrust bearing section receives the load and engages the second downthrust bearing section so as to share the load substantially equally between the first downthrust bearing section and the second downthrust bearing section. Each downthrust bearing section is substantially alike and additional downthrust bearing sections may be added as desired. The thrust chamber further includes an upthrust bearing section, connected to the shaft and the housing.
    Type: Grant
    Filed: December 12, 1995
    Date of Patent: September 16, 1997
    Assignee: Baker Hughes Incorporated
    Inventors: Wojciech A. Limanowka, Robert C. Delong
  • Patent number: 5441350
    Abstract: The structure of the cross roller bearing does not require fixing bolts, rivets or holders for the divided races and can firmly assemble the divided races together. The cross roller bearing includes the inner race having a raceway groove and an engagement surface on its outer circumferential surface and the outer race that fits over the inner race and has a raceway groove and an engagement surface on its inner circumferential surface. The outer race is divided into two axially divided races. A large number of rollers are installed in a raceway formed between the raceway grooves. The engagement surface of the inner race is formed with recessed portions at axially inner portions, and the engagement surfaces of the divided races of the outer race are formed with raised portions that rotatably fit in the recessed portions. Thus, the divided races are assembled onto the inner race so that they are rotatable but axially locked relative to the inner race.
    Type: Grant
    Filed: June 3, 1994
    Date of Patent: August 15, 1995
    Assignee: Nippon Thomson Co., Ltd.
    Inventor: Ryuji Fujita
  • Patent number: 5433536
    Abstract: A thrust bearing assembly includes a bearing housing and a shaft supported therein in a front and rear spherical thrust roller bearings. First and second spring devices are provided to pre-load the front and rear bearings. The bearing pre-load exerted by the first spring device acts on the front bearing in a direction opposed to a working load applied to the front bearing. The first spring device removes the spring force from the front bearing race rings, when exposed to a working load exceeding the load exerted by the first spring device. The first and second spring devices under working load and idle conditions being arranged to provide clearance between the rear bearing outer race and a bearing housing seat for the rear bearing outer race for allowing tilting of the outer race in order to compensate for radial oscillations, thereby avoiding rubbing movement between the outer race ring and the housing.
    Type: Grant
    Filed: May 27, 1994
    Date of Patent: July 18, 1995
    Assignee: Aktiebolaget SKF
    Inventor: Gunnar Bergling
  • Patent number: 5409316
    Abstract: A crossed roller bearing in which the rollers are oriented with their axes of rotation effectively crossed perpendicular to each other can be made from four molded plastic parts which are outer and inner split rings where the outer rings are joined side-by-side and have surfaces extending inwardly from the inner periphery which define a outer V-groove. Sets of rollers are connected at corners of one end face by frangible connections to the inside peripheries of each of the grooves and extend radially inwardly away from the inner periphery. The outer periphery of an inside pair of rings also has faces which form a V-groove opposed to the V-groove of the outer rings, when the inner rings are advanced toward each other and joined inside the outer rings. The ends of the inner rings engage the end faces of the rollers and pivot the rollers, preferably about corners in steps on the faces which form the V-grooves which define fulcrums.
    Type: Grant
    Filed: April 2, 1993
    Date of Patent: April 25, 1995
    Assignee: Precision Handling Devices
    Inventor: Gregory Ferguson
  • Patent number: 5302084
    Abstract: An improved windmill has an approximately vertical center support post. The windmill also has a plurality of wheels, each rotatably mounted on a separate horizontal axis, each axis being radially disposed about the center support post. The windmill also has a horizontal annular ring disposed radially about the center support post. The ring is mounted on the wheels so that the ring can rotate about the center support post. The windmill also includes a plurality of approximately horizontal beams. Each beam is radially disposed about the center support post. A first end of each beam is connected to the center support post and a second end of each beam is connected to the annular ring.
    Type: Grant
    Filed: December 30, 1992
    Date of Patent: April 12, 1994
    Inventor: Wilbert B. Nelson
  • Patent number: 5104239
    Abstract: A bearing and a method for extending the life of such bearing is disclosed. The bearing is shown to include an inner ring having first and second race channels, wherein each race channel defines first and second raceways adapted for contact with loaded rolling elements. An outer ring is shown to have third and fourth race channels, wherein each race channel defines first and second raceways adapted for contact with loaded rolling elements. A plurality of rolling elements are positioned within the race channels and are preferably oriented so that the axis of rotation of rolling elements in the first race channel is uniform and the axis of rotation of rolling elements in the second race channel is uniform. A pair of ports formed in one of the rings, each port intercepting at least one of the race channels, wherein each port has a cross-sectional area sufficient to permit the re-orientation or replacement of the axis of rotation of the rolling elements without having to remove the bearing from its installation.
    Type: Grant
    Filed: March 6, 1991
    Date of Patent: April 14, 1992
    Inventor: John E. Sague
  • Patent number: 5026177
    Abstract: A rolling contact type rotary bearing assembly includes a pair of inner and outer rings and a plurality of rolling members interposed therebetween to provide a relative rotation between the inner and outer rings. An insertion hole is provided in at least one of the inner and outer rings such that the plurality of rolling members may be inserted into the annular path defined between the inner and outer rings. A closure member is also provided to close the insertion hole after insertion of the rolling members into the annular path. The closure member is formed with a lubrication hole so that a lubricant may be provided to the annular path to allow a smooth rolling movement of the rolling members. A lubricant supply hole may also be provided in either of the outer and inner rings in communication with the lubrication hole of the closure member so as to allow to supply a lubricant to the annular path from the exterior.
    Type: Grant
    Filed: July 11, 1989
    Date of Patent: June 25, 1991
    Assignee: Nippon Thompson Co., Ltd.
    Inventor: Ichiro Masuda
  • Patent number: 4974972
    Abstract: A cross roller bearing includes a slotted cage structure that separates and controls tapered rollers as they roll on the bearing races. The cage is a load-bearing structure that is in sliding contact with the larger diameter axial end surface of the rollers, thereby preventing any sliding contact between the bearing races and the axial ends of the rollers. The point of sliding contact between the cage and the rollers may be selected for minimizing friction.
    Type: Grant
    Filed: December 26, 1989
    Date of Patent: December 4, 1990
    Assignee: Lucas Western, Inc.
    Inventors: Robert B. Boosler, Jr., Thurman W. Jessup
  • Patent number: 4973173
    Abstract: A rolling bearing (12) is arranged to support a shaft (10) rotatably in a housing (13). In order to make simple mounting and dismounting of the bearing (12) possible this is first fitted with a loose fit to the shaft (10), whereupon the shaft (10) is caused to expand thus that an interference fit is obtained at the same time as desired preload can be obtained in the bearing (12). The invention is intended to be applied particularly when mounting a drill head to a tunnel drilling machine.
    Type: Grant
    Filed: December 20, 1989
    Date of Patent: November 27, 1990
    Assignee: AB SKF
    Inventor: Gunnar Bergling
  • Patent number: 4961653
    Abstract: A crossed roller bearing assembly includes an outer ring provided with an outer V-shaped guide groove, an inner ring provided with an inner V-shaped guide groove and a plurality of rollers arranged in a guide space defined between the outer and inner V-shaped guide grooves in a rolling contact fashion. An insertion hole is formed in one of the outer and inner rings and the insertion hole preferably has a diameter which is larger than the diameter of the rollers, but smaller than a diagonal length in cross section of the rollers. A plug having a shape which substantially corresponds to the shape of the insertion hole is fitted into the insertion hole after insertion of the rollers. No gap or clearance is defined between the insertion hole and the plug so that the rollers can roll along the guide space smoothly.
    Type: Grant
    Filed: March 29, 1989
    Date of Patent: October 9, 1990
    Assignee: Nippon Thompson Co., Ltd.
    Inventors: Osamu Suzuki, Ichiro Masuda
  • Patent number: 4953992
    Abstract: An industrial robot rotation shaft apparatus according to the invention has a waterproof structure obtained by providing the outer surface of a rotatable support (3) with an integrally formed, peripheral skirt portion (3c). A stationary support (2) is provided with a complementary, projecting collar portion (7b) substantially conforming to the inner surface of the skirt portion. The two complementary elements oppose each other while maintaining a small clearance therebetween. This makes it possible to shut out dust, water droplets and the like which would otherwise penetrate the interior of the robot from outside. As a result, rusting of the internal parts and the motor due to water droplets and debris penetrating the same is prevented.
    Type: Grant
    Filed: April 21, 1988
    Date of Patent: September 4, 1990
    Assignee: Fanuc Ltd.
    Inventors: Nobutoshi Torii, Kazuhisa Otsuka
  • Patent number: 4906113
    Abstract: A slew ring bearing for coupling the superstructure of a large piece of heavy equipment to the base having an inner ring attachable to the underside of the superstructure and an outer ring having gear teeth on its outer cylindrical surface concentric with the inner ring and attachable to a stationary base frame. An upper and lower V-groove are found in an outer cylindrical face of the inner ring. Corresponding upper and lower V-grooves are formed on an inner cylindrical face of the outer ring positioned opposite corresponding upper and lower V-grooves on the inner ring so as to form in combination therewith associated upper and lower roller bearing raceways. A plurality of rolling elements are positioned in the upper and lower raceways so as to permit rotation of the inner ring relative to the outer ring. A plurality of bronze spacers are positioned with one spacer between each pair of rollers.
    Type: Grant
    Filed: July 27, 1988
    Date of Patent: March 6, 1990
    Assignee: Quintette Coal Limited
    Inventor: John E. Sague
  • Patent number: 4896974
    Abstract: A crossed roller rolling contact bearing assembly includes a pair of first and second members which move relative to each other, a guide channel defined between the first and second members and a plurality of rollers provided in the guide channel in a crossed arrangement with a spacer interposed between any two adjacent rollers. The spacer has a generally spherical outer peripheral surface and a pair of recessed, arc-shaped guide surfaces which have generatrix lines extending perpendicular to each other. Becuase of the spherical outer shape of the spacer, a generally wedge-shaped space is defined between the roller and the spacer so that a quantity of lubricant may be reserved therein to keep the guide channel sufficiently lubricated at all times.
    Type: Grant
    Filed: December 22, 1988
    Date of Patent: January 30, 1990
    Assignee: Nippon Thompson Co., Ltd.
    Inventor: Toshiaki Shimizu
  • Patent number: 4853567
    Abstract: A direct drive motor for use with factory automation, wherein the motor is arranged to directly obtain rotary forces without using a final reduction gear. The direct drive motor has an inner stator, an outer rotor disposed outside the inner stator with a slight air gap formed therebetween, a cylindrical rotor hub to which the outer rotor hub is internally fixed and a bearing provided in an inner cylindrical portion of the rotor hub for rotatably supporting the rotor hub.
    Type: Grant
    Filed: February 17, 1988
    Date of Patent: August 1, 1989
    Assignee: Yokogawa Electric Corporation
    Inventors: Yasuhiko Muramatsu, Susumu Ohta, Toshiyuku Takagi, Haruo Higuchi, Mitsuhiro Nikaido
  • Patent number: 4834561
    Abstract: A redundant-race bearing system incorporates a pair of ring-shaped race members. The race members are coaxial and axially spaced apart from one another. Each race member has a radial cross-section that includes a plurality of tracks. These tracks form a confining pattern that enables lateral and axial restraint.
    Type: Grant
    Filed: May 19, 1988
    Date of Patent: May 30, 1989
    Assignee: AEC-Able Engineering Company, Inc.
    Inventors: Max D. Benton, Michael R. Everman
  • Patent number: 4776710
    Abstract: The low friction roller provided by the present invention is featured by the construction, wherein an end plate made of organic or inorganic low friction material is fitted onto each of the opposing end faces of a cylindrical roller body with the use of chemical or mechanical bonding method, thus in operation, the low friction roller member moves along and through a raceway track provided in a roller bearing with minimum friction being generated with not only the track surface but also the contacting surface of roller retainer members provided therefor, so that low friction and smooth circulation of a plurality of roller members in the bearing can be ensured for a prolonged period of time.
    Type: Grant
    Filed: August 7, 1987
    Date of Patent: October 11, 1988
    Assignee: Nippon Thompson Co., Ltd.
    Inventor: Takehiko Hara
  • Patent number: 4761084
    Abstract: A redundant-race bearing system according to this invention incorporates a pair of ring-shaped race members. The race members are coaxial and axially spaced apart from one another. Each race member has a radial cross-section that includes a plurality of tracks. These tracks form a confining pattern that enables lateral and axial restraint.
    Type: Grant
    Filed: June 30, 1987
    Date of Patent: August 2, 1988
    Assignee: AEC-Able Engineering Company, Inc.
    Inventors: Max D. Benton, Michael R. Everman
  • Patent number: 4746232
    Abstract: A bearing in which the cylindrical roll bodies, which follow one another in the circumferential directions, are mutually displaced by a particular crossing angle and, moreover, deviate from the previously normal crossing angle, by about 100 to 130 degrees and preferably by 110 degrees.
    Type: Grant
    Filed: November 7, 1986
    Date of Patent: May 24, 1988
    Inventor: Georg Gugel
  • Patent number: 4606654
    Abstract: A cross roller bearing includes an inner ring, an outer ring and a plurality of generally cylindrically shaped rollers placed in a channel defined between the inner and outer rings as being alternately crossed with any two adjacent rollers having their axes of rotation directed perpendicular to each other. Both of the inner and outer rings are unitary in structure. In one form of the invention, the outer ring is provided with a radial hole extending therethrough radially, through which the rollers may be inserted in the channel defined between the inner and outer rings. An insert is also provided to be fixedly fitted into the radial hole so as to close the radial hole after insertion of the rollers into the channel.
    Type: Grant
    Filed: December 3, 1984
    Date of Patent: August 19, 1986
    Assignee: Nippon Thompson Co., Ltd.
    Inventors: Takashi Yatsu, Tatsuo Mottate
  • Patent number: 4582436
    Abstract: An improved live roller circle for rotatably supporting the upper frame or body of a large excavator on its lower frame or base is provided. It comprises upper and lower annular rails respectively mounted on the upper and lower frames of the machine. A plurality of tapered rollers, arranged in a circle, roll between and in contact with the rails. The rollers are nominally spaced apart by a circular cage to which the rollers are sufficiently loosely connected to allow them to self-align with respect to the rails irrespective of irregularities in the shape of alignment of the cage. A third annular rail extending around the outer circumference of the circle of rollers is also preferably provided.
    Type: Grant
    Filed: August 29, 1983
    Date of Patent: April 15, 1986
    Assignee: Dresser Industries, Inc.
    Inventor: Thomas S. Merron
  • Patent number: 4501454
    Abstract: A series of axially stacked rolling bearing assemblies for transmitting axial thrust load between relative rotating cylinders, such as in a fluid powered downhole motor, is provided with the bearing races of each assembly formed from a bearing material significantly softer than the balls thereof so as to readily wear to a condition wherein the thrust load is generally equally distributed throughout each assembly within the stack.
    Type: Grant
    Filed: October 28, 1983
    Date of Patent: February 26, 1985
    Assignee: Dresser Industries, Inc.
    Inventors: James G. Dennis, Kenneth W. Bramlett, G. C. Jackson, Jr.
  • Patent number: 4493514
    Abstract: A mechanism for distributing axial thrust loads acting on a rotating shaft, ncluding dual thrust bearing assemblies concentrically mounted on the rotating shaft for transmitting axial thrust loads to the thrust load distributing mechanism. The thrust load distributing mechanism includes a stationary support member having at least one fulcrum to provide a reaction force to counterbalance the axial thrust loads acting on the rotating shaft, an annular load lever cooperating with each of the at least one fulcrum, at least two thrust transfer members cooperating with first and second segments on the annular load lever and the dual thrust bearing assemblies, and a force transmitting means.
    Type: Grant
    Filed: March 12, 1984
    Date of Patent: January 15, 1985
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: John W. Henry, IV
  • Patent number: 4479683
    Abstract: The present invention discloses a spacer retainer in a cross roller bearing.
    Type: Grant
    Filed: March 7, 1983
    Date of Patent: October 30, 1984
    Assignee: Toho Seiko Co., Ltd.
    Inventor: Takayoshi Kanamaru