Abstract: A rolling element series is formed with a plurality of spherical rolling elements and four kinds of retainer pieces. The element-to-element thicknesses TA, TB, TC, and TD of the retainer pieces are different: TA>TB>TC>TD.

Abstract: A super finishing is carried out after grinding, so that surface roughness of a ball rolling groove of a screw shaft is made 0.12 &mgr;m or less in an average roughness (Ra). Separators 7 having ball holding surfaces shaped in concave surface are disposed between balls respectively.

Abstract: Between two mutually adjoining load balls 5, there is interposed a retaining piece 10 having two concave surfaces 11 which are respectively opposed to the two adjoining load balls 5. The retaining piece 10 has an outside diameter dimension equal to or more than 0.5 times the outside diameter dimension of the load ball 5. Further, the retaining piece 10 has an outside diameter dimension which, when the retaining piece 10 passes through a screw groove circulation passage and a tube circulation passage, prevents the retaining piece 10 from touching the inner walls of these screw groove circulation passage and tube circulation passage, or has an outside diameter dimension which is equal to or less than 0.9 times the outside diameter dimension of the load ball.

Abstract: A rolling ball separator structure of a linear drive member includes multiple separators mounted between the multiple rolling balls and each having a body and an outer ring structure. Thus, the body may be deformed elastically, thereby preventing the multiple separators from interfering with the return face of the rolling path during the returning process of the rolling balls, and thereby absorbing the gap variation of the uneven force during the returning process of the rolling balls, and the outer ring structure may maintain the relative position of the rolling balls, so that the rolling balls will not collide directly during the returning process.

Abstract: Between two mutually adjoining load balls 5, there is interposed a retaining piece 10 having two concave surfaces 11 which are respectively opposed to the two adjoining load balls 5. The retaining piece 10 has an outside diameter dimension equal to or more than 0.5 times the outside diameter dimension of the load ball 5. Further, the retaining piece 10 has an outside diameter dimension which, when the retaining piece 10 passes through a screw groove circulation passage and a tube circulation passage, prevents the retaining piece 10 from touching the inner walls of these screw groove circulation passage and tube circulation passage, or has an outside diameter dimension which is equal to or less than 0.9 times the outside diameter dimension of the load ball.

Abstract: A linear actuator realizing low generation of dust and low generation of noise and bearing a large axial load is provided. A plurality of spacers 30, - - - , each having at its both ends spherical recessed portions corresponding to curved surfaces of balls 28, - - - , are arranged between the balls 28, - - - of the guide portion of the linear actuator, and the spacers 30, - - - are connected to each other in series by belt-shaped members 31 having flexibility. On the other hand, a plurality of spacers 35, - - - , each having at its both ends spherical recessed portions corresponding to curved surfaces of balls 33, - - - for the screw shaft of a screw portion, are arranged between the balls 33, - - - in a manner separated from each other.

Abstract: An electric power steering apparatus comprises a rack-and-pinion mechanism and a ball screw mechanism. The ball screw mechanism comprises a shaft formed a screw groove and a nut formed a screw groove. A ball-roll path is created spirally by the screw grooves of the shaft and the nut being opposite each other. A plural number of balls are contained into the ball-roll path. A ball-return path is connecting both ends of the ball-roll path so that the balls go through. A circulation path consists of the ball-roll path and the ball-return path, in which the balls move endlessly. A plural number of separators is arranged between the balls respectively in order to prevent balls from contacting each other. A number of the balls is fewer from one ball to three balls than a maximum number of the balls which can be contained into the circulation path.

Abstract: A ball screw comprises a screw shaft, a nut assembled with the screw shaft, a number of balls disposed in the ball rolling passage formed by a ball rolling groove formed to the screw shaft and a loaded ball rolling groove formed to the nut, a number of spacers disposed between the balls in the ball rolling passage, and a circulation member for circulating the balls and spacers in accordance with a relative motion of the nut with respect to the screw shaft. The circulation member is provided with a scoop-up groove for scooping the balls, when contacting the ball rolling in the ball rolling passage, at both side edge portions of the scoop-up groove and is also provided with a spacer scoop-up portion which contacts and scoops the spacer moving in the ball rolling passage without contacting the balls. Such circulation member will be preferably utilized for a motion guide device such as linear motion guide or spline shaft.

Abstract: A ball screw with ball retainer cage equipped between the screw bolt and the nut body is disclosed. The adjacent balls can move without squeezing each other and well protected in the retainer cage from dropping off therefrom when the retainer cage is disintegrated from the screw bolt and the nut body simultaneously. The total length of the ball screw assembly can be shortened to make the assembly compact in size. In addition, the specification of the product can be standardized to facilitate mass production with a reduced cost employing die casting process.

Abstract: The invention provides a ball screw which is little subject to deterioration of operating characteristics and occurrence of wear, torque change, noise, vibration, etc. during operation due to stagnation or competition of balls. A ball screw comprising a screw shaft having a helical thread groove formed on the outer surface thereof and a nut having a thread groove formed on the inner surface thereof corresponding to the thread groove on the screw shaft which engages with the screw shaft with the interposition of a number of balls rollably provided in a helical ball rolling path formed between the two thread grooves, wherein the variation of the total of the gap between said balls during the rolling of the balls is smaller than {fraction (1/20)} of the diameter of the ball.

Abstract: A ball screw (1) as a linear motion device according to the invention has retaining pieces (21) each having two concave surfaces (23) facing adjacent ones of rolling elements (9) respectively. Each of the retaining pieces (21) is disposed between adjacent ones of the rolling elements (9). A carbonitrided layer containing residual austenite of 15-40% by volume is provided in the surface layer of each of the rolling elements (9).

Abstract: In a ball screw, a nut is fitted with the outer periphery of a screw shaft, ball rolling grooves opposed to each other are formed in the screw shaft and the nut The ball rolling grooves cooperate in forming a ball rolling path therebetween. A tube as a return path disposed on the nut for connecting one end portion of the ball rolling path to the other end portion thereof, the ball rolling path and tube cooperate in forming an endless circulation path. A plurality of load balls are disposed within the endless circulation path. The position of the tube cannot be limited to a single specific position. In the ball screw, retaining pieces are respectively inserted between the mutually adjacent ones of the load balls disposed within the endless circulation path.

Abstract: A ball screw having spacers which can assuredly be retained between balls and prevent direct contact between the balls. The ball screw includes a plurality of spacers (1) provided between respective adjacent pairs of balls. The spacers (1) each include a base plate (2) having front and back surfaces, and at least three projections (4, 6) provided on each of the front and back surfaces of the base plate (2). The projections (4) on the front surface are offset from the projections (6) on the back surface. The spacers (1) are each provided perpendicularly to a traveling direction of the balls with the projections (4, 6) on the front and back surfaces resiliently abutting against the balls.

Abstract: A linear motion device includes an inner member and an outer member cooperatively forming a ball circulating path therebetween, a plurality of balls rollably disposed in the ball circulating path, and a plurality of retaining pieces interposed between the balls, wherein the ratio of a ball-to-ball direction force applied to the retaining piece by the balls disposed at the both sides thereof to the elastic displacement of the retaining piece by the force is adjusted to a range of from 0.1 to 10 [N/&mgr;m] from 0.1 to 10 [N/&mgr;m] by predetermining a bore diameter of a through-hole formed at the central portion of the retaining piece to a range of from 35% to 65% of a diameter of the ball.

Abstract: There is provided a rolling element spacer used in a rolling guide device having an endless circulation passage of balls, arranged alternately with many balls in the endless circulation passage, and circulating together with the balls in the endless circulation passage. It has a pair of ball holding seats each of which is formed in a concave spherical face form nearly approximating a spherical face of the ball and sliding-contacts with the ball and, around each ball holding seat, there is formed an annular dropout prevention portion protruding in a ball arranging direction than an edge portion of the ball holding seat and kept in non-contact with respect to the ball seated on the ball holding seat.

Abstract: A screw device having a lubricant applying structure comprises a screw shaft provided with a spiral ball rolling groove, a nut provided with a loaded ball rolling groove having a spiral shape corresponding to the spiral ball rolling groove formed to the screw shaft, a number of balls disposed in a loaded rolling passage formed by the ball rolling groove and the loaded ball groove, a return member provided for the nut and arranged so as to connect one and another end portions of the loaded rolling passage so that the balls rolling the loaded rolling passage circulate, and a lubricant applying portion mounted to the return member so as to apply a lubricant. The lubricant applying portion is arranged inside the return member provided for the nut.

Abstract: A liner motion device has a liner motion element fitted on a shaft and moving straight along the shaft; a plurality of balls which are retained in a rolling element groove formed on the inner side of the liner motion element and roll over between the rolling element groove and the shaft; a separator interposed between the rolling elements; and, a circulating path formed in the liner motion element through which the rolling elements are circulated from one end of the rolling element groove to the other, wherein the separator is a product of a synthetic resin containing a lubricating oil in an amount of 3 to 25% by volume.

Abstract: A linear-motion device has: a linear-motion element fitted on a shaft which moves straight along the shaft; a plurality of balls which are retained in a ball groove formed on the inner side of the linear-motion element and roll over between the ball groove and the shaft; a separator interposed between the balls; and, a circulating path formed in the linear-motion element through which the balls are circulated from one end of the ball groove to the other, which is filled with a grease, wherein the separator is a formed product comprising as a resin component a polybutylene naphthalate-based elastomer formed by a hard segment made of a polybutylene naphthalate and a soft segment made of a polycondensate of 2,6-naphthalanedicarboxylic acid with a polytetramethylene ether glycol.

Abstract: The invention provides a ball screw apparatus which suppresses abrasion and damage by competition of balls, controls spaces between retaining pieces and balls, and prevents retaining pieces from falling, thereby enabling to more improve operating ability. The retaining pieces are positioned between the balls running in a ball rolling path, such that a sum total of the spaces between the retaining pieces and the balls is 50% or less of an outer diameter size of the retaining piece, and at the same time a contact angle between the retaining piece and the ball is 25° or above to 40° or below.

Abstract: The invention is to offer a ball screw apparatus which can suppress retaining pieces from contacting a wall of a ball rolling path or ball circulating path, and suppress the retaining pieces between the balls from falling down, so that such a ball screw apparatus can be offered which enables to more improve low noises, operationability and endurance. The holding piece is rounded at an edge portion opposite to the ball, such that a radius of curvature of the edge portion is defined to be 1 mm or less, and the outer diameter of the retaining piece is determined to range 0.60 times or more to 0.85 times or less of the diameter of the ball.

Abstract: Ball screw with long duration and reduced noisiness, in particular for aerospace and industrial applications, comprising load-bearing balls made of ceramic material alternating, one by one, with spacer balls made of material having low volume mass, no greater than 3 g/cm3, and having a smaller diameter than that of the load-bearing balls.

Abstract: A roller retainer 11 encloses an outer periphery of the roller 9 situated on a diagonal 20 when the roller 9 is viewed from the side surface thereof. Whether the rollers 9 are arranged in a parallel manner or in a cross manner, the roller retainer 11 is able to keep a constant position and thus the disposition of the roller retainer 11 is free from the influence of the direction the roller 9. Also, since the roller retainer 11 restricts a corner portion 9a of the roller 9, the roller 9 is difficult to slip off the roller retainer 11 and thus the roller 9 can be restricted positively, thereby being able to control the skew of the roller 9.

Abstract: A ball screw in a continuously variable speed transmission has an axially immovable pulley half (2) and axially movable pulley half (3) both mounted on a rotary shaft (4). The axially movable pulley half (3) is moved by a ball screw (20) so as to infinitely vary the belt wrapping radius and thus the transmission speed. A nut (22), forming one part of the ball screw (20), is immovably secured in both axial and rotational directions. A screw shaft (21), forming the other part of the ball screw (20), is movable in both axial and rotational directions. The screw shaft 21 is connected to the axially movable pulley half (3). The axially movable pulley half (3) is axially moved by rotating the screw shaft (21).

Abstract: A spacer interposed between two adjacent balls formed into an elaborately designed cylinder like configuration which is able to minimize noise, vibration and frictional loss due to mutual collision and impact of the balls. The spacer is provided with a let through hole therein for further enhancing lubricating and cooling effect.

Abstract: A deflector type ball screw includes a screw shaft having an external thread groove in an outer peripheral surface, a ball nut having an internal thread groove in an inner peripheral surface and a plurality of balls that are rollably housed between the internal thread groove and the external thread groove, and four deflectors fixed to the ball nut. The deflectors function as by-passes linking adjacent internal thread grooves of the ball nut. As a result of the deflectors guiding the balls, the screw groove of the ball nut is divided into four circulation passages.

Abstract: There is provided a rolling element spacer used in a rolling guide device having an endless circulation passage of balls, arranged alternately with many balls in the endless circulation passage, and circulating together with the balls in the endless circulation passage. It has a pair of ball holding seats each of which is formed in a concave spherical face form nearly approximating a spherical face of the ball and sliding-contacts with the ball and, around each ball holding seat, there is formed an annular dropout prevention portion protruding in a ball arranging direction than an edge portion of the ball holding seat and kept in non-contact with respect to the ball seated on the ball holding seat.

Abstract: Between two mutually adjoining load balls 5, there is interposed a retaining piece 10 having two concave surfaces 11 which are respectively opposed to the two adjoining load balls 5. The retaining piece 10 has an outside diameter dimension equal to or more than 0.5 times the outside diameter dimension of the load ball 5. Further, the retaining piece 10 has an outside diameter dimension which, when the retaining piece 10 passes through a screw groove circulation passage and a tube circulation passage, prevents the retaining piece 10 from touching the inner walls of these screw groove circulation passage and tube circulation passage, or has an outside diameter dimension which is equal to or less than 0.9 times the outside diameter dimension of the load ball.

Abstract: The present invention provides rolling element spacers used in a rolling guide unit provided with an endless circulating passage for balls; arranged with plural balls alternately therewith in the endless circulating passage; and circulated with these balls in the endless circulating passage. Each of the rolling element spacers has a pair of retaining seats which the balls contact, and is formed so that, on a ball cutting plane perpendicular to the center of rotation of each ball, each retaining seat and a relative ball contact each other at only the two portions of the retaining seat that are in the vicinity of both ends thereof.

Abstract: A ball screw comprising a screw shaft 1 made of steel and having a thread groove 6 on outer peripheral surface, a ball nut 2 made of steel and having a thread groove 7 opposing the thread groove 6 on inner peripheral surface, a return tube 3 attached on the ball nut 2, and a plurality of balls inserted between the two thread grooves 6 and 7 and in the return tube 3. As the balls, steel balls 4 made of bearing steel and ceramic balls 5 made of silicon nitride are disposed alternately at a given ratio. Diameter Dc of the ceramic ball 5 is set to a value smaller than diameter Ds of the steel ball 4 so that contact stress acted on contact surfaces of the ceramic ball 5 and the two thread grooves 6 and 7 will be equal to contact stress acted on contact surfaces of the steel ball 4 and the two thread grooves 6 and 7.

Abstract: A rolling element series is formed with a plurality of spherical rolling elements and four kinds of retainer pieces. The element-to-element thicknesses TA, TB, TC, and TD of the retainer pieces are different: TA>TB>TC>TD.

Abstract: A nut unit (20) for use in a ball screw drive comprises a sleeve-shaped nut body (10) that is made of an essentially rigid material and that has an axis (A) and an inner circumferential surface (14). A one-piece, channel-shaped, ball-guiding strip material helix (18) is arranged on the inner circumferential surface (14) of the nut body (10). The strip material helix (18) is mounted within a concavely-curved support groove (16) formed in the inner circumferential surface (14) of the nut body (10). The helix (18) has an external convexly-curved profile (46), which is embodied with external profile flank regions (46′) and an external profile crown region (46″). The helix (18) defines, by means of a curved internal profile (48) facing the axis (A), a ball channel with an internal profile base region (48″) and two internal profile flank regions (48′). The outer profile flank regions are essentially rigidly supported by the support profile of the support groove (16).

Abstract: A ball screw device utilizes spacers having concave ball-contacting surfaces with distributed protrusions or dimples. Balls having needle-like recesses may also be used. The spacers are provided in two thicknesses, and the relative numbers of the thinner and thicker spacers are selected in order to ensure retention of the spacers in their proper positions, while providing a small clearance between the balls and spacers to avoid fluctuations or sharp increases in dynamic torque.

Abstract: A ball screw device utilizes spacers having concave ball-contacting surfaces with distributed protrusions or dimples. Balls having needle-like recesses may also be used. The spacers are provided in two thicknesses, and the relative numbers of the thinner and thicker spacers are selected in order to ensure retention of the spacers in their proper positions, while providing a small clearance between the balls and spacers to avoid fluctuations or sharp increases in dynamic torque.

Abstract: The present invention provides a ball screw having spacers which can assuredly be retained between balls and prevent direct contact between the balls. The ball screw includes a plurality of spacers (1) provided between respective adjacent pairs of balls. The spacers (1) each include a base plate (2) having front and back surfaces, and at least three projections (4, 6) provided on each of the front and back surfaces of the base plate (2). The projections (4) on the front surface is offset from the projections (6) on the back surface. The spacers (1) are each provided perpendicularly to a traveling direction of the balls with the projections (4, 6) on the front and back surfaces resiliently abutting against the balls.

Abstract: A ball screw with ball retainer cage equipped between the screw bolt and the nut body is disclosed. The adjacent balls can move without squeezing each other and well protected in the retainer cage from dropping off therefrom when the retainer cage is disintegrated from the screw bolt and the nut body simultaneously. The total length of the ball screw assembly can be shortened to make the assembly compact in size. In addition, the specification of the product can be standardized to facilitate mass production with a reduced cost employing die casting process.

Abstract: There is provided rolling element spacers that are used in a rolling guide device having an endless circulation path of balls and that are arranged to alternate with a multiplicity of balls and circulated in the endless circulation path along with the balls. They are constituted by a disc-shaped inner member having a pair of ball holding seats on which the balls slide in contact therewith and an annular outer member covering an outer circumferential surface of the inner member, and the outer member and inner member are molded from resin materials having different flexural modulo.

Abstract: This invention relates to improvement of a ball screw unit in which a nut member meshes with a screw shaft via a plurality of balls circulating endlessly. The balls are disposed freely rotatably in line at a predetermined interval in a ball arranging member formed in a belt-like shape. If a relative rotation occurs between the nut member and screw shaft, the balls circulate in the infinite circulation path with the ball arranging member. Guide pieces are projected to both sides of the ball arranging member and guide grooves for accommodating each of the guide pieces are formed along the entire circumference of the infinite circulation path. Therefore, the ball arranging member is introduced by the guide grooves and circulates in the infinite circulation path without being fluttered.

Abstract: A rolling-element hold spacer 9 includes a spherical indent 11 which is formed in either side of a rolling element 7 so as to match the curved surface of the rolling element 7; thick hold sections 10a, 10b to be interposed between the rolling elements 7; and thin bent sections 12 for interconnecting only one thick hold section pair 10a, 10b in which the rolling element 7 is to be interposed. The thin bent section 12 is deflected or twisted in a curved portion of a rolling-element circulation path. Further, the rolling-element hold spacers which are adjacent to each other with a single rolling element interposed therebetween mutually perform pivotal movement around the rolling element 7, thereby enabling smooth circulation of the rolling elements 7. Clearance arises between the rolling element 7 and the thick hold sections 10a, 10b as a result of bent of the thin bent section 12. Lubricant enters the clearance, to thereby sufficiently lubricate the rolling elements 7.