JP5557680B2 - Spacer, motion guide device incorporating the spacer, and screw device - Google Patents

Description

  The present invention relates to a motion guide device that guides movement of a movable body such as a table relative to a fixed body such as a bed, and a screw device that rotates a screw shaft to obtain a linear motion of a nut.

  The motion guide device includes a track member attached to a fixed body such as a bed and a moving member attached to a movable body such as a table. The moving member moves linearly or curvedly along the track member. A rolling member rolling part extending in the longitudinal direction is formed on the race member. The track member includes a loaded rolling element rolling part facing the rolling element rolling part of the moving member, an unloaded return path parallel to the loaded rolling element rolling part, an end of the loaded rolling element rolling part, and an unloaded return. An infinite circulation path including a U-shaped direction change path that connects the ends of the path is formed. A plurality of rolling elements are arranged in the infinite circulation path. When the moving member moves relative to the track member, the plurality of rolling elements roll and move between the rolling element rolling portion of the track member and the load rolling element rolling portion of the moving member. Due to the rolling motion of the rolling elements, the moving member moves linearly or curvilinearly along the track member with minimum frictional resistance.

  The screw device has a spiral rolling element rolling groove on the outer peripheral surface of the screw shaft and a loaded rolling element rolling groove on the inner peripheral surface of the nut, and a plurality of rolling elements are interposed therebetween. is there. When the screw shaft is rotated relative to the nut, the nut linearly moves in the axial direction of the screw shaft. When the screw shaft is rotated relative to the nut, the plurality of rolling elements roll and move between the rolling element rolling groove of the screw shaft and the load rolling element rolling groove of the nut. The screw shaft can be rotated with the minimum frictional resistance by the rolling motion of the rolling elements.

  By the way, in the motion guide device and the screw device, when the rolling elements before and after the traveling direction are in contact with each other, when the rolling elements roll, a slip occurs at a contact portion between the rolling elements, and the rolling elements Incurs premature wear. In order to prevent contact between the rolling elements, a spacer is interposed between the rolling elements. The plurality of spacers may be connected in series by a band (band type retainer) or may be separated from each other (separate type spacer).

  In particular, when a separate type spacer is incorporated in the endless circulation path, a circumferential clearance (a clearance in the traveling direction of the rolling elements) occurs somewhere in the endless circulation path. In order to prevent circumferential clearance, elastic elastic spacers are interposed between the balls (see Patent Document 1). This elastic spacer includes a cylindrical outer frame portion that forms the outer shape of the spacer, and a plurality of claw portions that extend from the outer frame portion toward the center thereof in a tongue-like shape and come into contact with the rolling elements and can be elastically deformed. Yes. In the infinite circulation path, the spacer has an elastic force to try to pull the balls apart. Since the force balances as a whole in the infinite circulation path, the circumferential clearance can be eliminated.

Japanese Unexamined Patent Publication No. 2006-282838

  However, the invention described in Patent Document 1 has a problem that stress tends to concentrate on the base of the bent nail part of the spacer, and the base of the nail part is fatigued. Fatigue at the base of the nail portion deteriorates the durability of the spacer, and consequently reduces the reliability of the spacer.

  Then, an object of this invention is to provide the spacer which can improve the durability and reliability of a spacer, the movement guide apparatus incorporating this spacer, and a screw apparatus.

A first aspect of the present invention is a motion guide device in which a plurality of rolling elements are interposed between a raceway member and a moving member that moves along the raceway member, or between a screw shaft and a nut. It is a spacer that is incorporated in a screw device that interposes a plurality of rolling elements so as to be capable of rolling motion, and is arranged between the rolling elements so as to prevent contact between the rolling elements, the spacer having a disk as a basic shape, A main body formed in a continuous wave shape having crests and troughs alternately in the circumferential direction, and a peripheral edge formed so as to border the periphery of the main body, and the spacer The peak portion is curved so as to approach one of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer, and the valley portion of the spacer is adjacent to the pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer. Approaching the other of the rolling elements Curved to make contact with the one of the pair of rolling elements the mountain portion adjacent the periphery of the spacer in contact with the other of the pair of rolling elements the valleys of the peripheral edge of the spacer adjacent It is a spacer.

Another aspect of the present invention includes a raceway member having a rolling element rolling part, a moving member having a load rolling element rolling part facing the rolling element rolling part, and the rolling element rolling part of the raceway member. And a plurality of rolling elements arranged so as to be capable of rolling motion, and a plurality of spacers arranged between the rolling elements so as to prevent contact between the rolling elements, and The spacer has a disk-shaped basic shape, and a main body formed in a continuous wave shape having a crest and a valley alternately in the circumferential direction, and the periphery of the main body. A peripheral edge formed so as to be edged, and the peak portion of the spacer is curved so as to approach one of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer. The trough goes to the outer peripheral side of the spacer Therefore, curved so as to approach the other of the pair of rolling elements adjacent contact with one of the pair of rolling elements the mountain portion adjacent the periphery of the spacer, the valley of the periphery of the spacer Is a motion guide device that contacts the other of a pair of adjacent rolling elements.

Still another aspect of the present invention is a screw shaft having a spiral rolling element rolling groove, a nut having a load rolling element rolling groove facing the rolling element rolling groove, and the rolling element of the screw shaft. A plurality of rolling elements arranged so as to be capable of rolling motion between a rolling groove and the loaded rolling element rolling groove of the nut, and a plurality of rolling elements arranged between the rolling elements so as to prevent contact between the rolling elements. A spacer including a main body formed in a continuous wave shape having a disk as a basic shape and alternately having crests and troughs in the circumferential direction, and the periphery of the main body A peripheral portion formed so as to border the spacer, and the crest portion of the spacer is curved so as to approach one of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer. The valley portion of the According, curved so as to approach the other of the pair of rolling elements adjacent contact with one of the pair of rolling elements the crests of the peripheral edge of the spacer adjacent said valleys of said peripheral portion of said spacer The screw device is in contact with the other of a pair of adjacent rolling elements.

  The crests and troughs at the peripheral edge of the spacer are elastically deformed, and an elastic force is generated to separate the pair of adjacent rolling elements across the spacer, so that the rolling elements can be evenly aligned and stable. You can give guidance. Here, when the peaks and valleys of the spacer are elastically deformed, the stress is distributed throughout the spacer. Since the concentration of local stress is alleviated, the durability and reliability of the spacer can be improved.

The perspective view (partial cross section is included) of the motion guide apparatus (linear guide) in 1st embodiment of this invention Sectional view perpendicular to the longitudinal direction of the track member of the linear guide Cross section of the linear guide endless circuit The figure which shows the spacer pinched | interposed between balls ((a) in the figure shows a plan view, (b) in the figure shows a front view, (c) in the figure shows a side view, (d) in the figure) (Shows rear view) Perspective view of spacer Detailed view of spacer ((a) in the figure shows a front view, and (b) and (c) in the figure show sectional views) The figure which shows the other example of a spacer ((a) in a figure shows a front view, (b) in a figure shows a side view, (c) in a figure shows sectional drawing)) The perspective view (including a partial cross section) of the screw device of the second embodiment of the present invention The figure which shows the analysis conditions of FEM ((a) in a figure shows a FEM model figure, (b) in the figure shows how to give a boundary condition) The figure which shows the result of FEM analysis ((a) in the figure shows the amount of deformation of the spacer, (b) shows the equivalent stress generated in the spacer) Graph showing the relationship between indentation and maximum equivalent stress

  FIG.1 and FIG.2 shows the linear guide as a motion guide apparatus in 1st embodiment of this invention. FIG. 1 shows a perspective view (including a partial cross-sectional view) of the linear guide, and FIG. 2 shows a cross-sectional view orthogonal to the longitudinal direction of the track member of the linear guide.

  The linear guide includes a track rail 1 as a track member extending linearly or curvedly, and a moving block 2 as a moving member provided on the track rail 1 through a plurality of balls 3 as rolling elements. It has.

  The track rail 1 of this embodiment has a substantially square cross section and extends elongated. In the track rail 1, bolt through holes 1 b for attaching the lower surface of the track rail 1 to a fixed part such as a bed are formed penetrating from the upper surface to the lower surface. Ball rolling grooves 1 a as rolling element rolling portions extending along the longitudinal direction are formed on the left and right side surfaces and the upper surface of the track rail 1. In this embodiment, a protrusion 11 is formed at the end of the upper surface of the track rail 1 in the width direction, and a total of four ball rolling grooves 1 a are formed above and below the protrusion 11. The cross-sectional shape of the ball rolling groove 1a is formed into a circular arc groove shape made up of a single arc or a Gothic arch groove shape made up of two arcs. The ball 3 contacts the ball rolling groove 1a at one point or two points.

  The moving block 2 has an infinite circulation including a load ball rolling groove 2a as a load rolling element rolling portion facing the ball rolling groove 1a of the track rail 1 and an infinite circulation path including the load ball rolling groove. The road includes a loaded ball rolling groove, a no-load return path extending parallel to the loaded ball rolling groove, and a direction changing path connected to the end of the loaded ball rolling groove and the end of the unloaded return path. .

  The moving block 2 includes a moving block main body 4 in which a load ball rolling groove is formed, and a pair of end plates 5 as lid members attached to both ends of the moving block main body 4 in the moving direction. As shown in FIG. 2, the moving block body 4 includes a central portion 4 a that faces the upper surface of the track rail 1, and a side wall portion 4 b that extends downward from the left and right sides of the central portion 4 a and faces the left and right side surfaces of the track rail 1. . Four load ball rolling grooves 2a facing the ball rolling groove 1a of the track rail 1 are formed on the lower surface of the central portion 4a of the moving block body 4 and the inner surface of the side wall portion 4b. The cross-sectional shape of the loaded ball rolling groove 2a is formed into a circular arc groove shape made up of a single arc or a Gothic arch groove shape made up of two arcs. The ball 3 contacts the load ball rolling groove 2a at one point or two points.

  As shown in FIG. 1, on the upper surface of the moving block 2, a mounting screw 2b for processing the moving block to a mating part such as a table is processed. An end face seal 6 that prevents foreign substances such as dust from entering the moving block 2 is attached to the end face of the moving block 2 in the moving direction. A side seal 12 is attached to the lower surface of the side wall portion 4b of the moving block 2 to prevent foreign substances from entering from the lower side. Ball holding plates 13 and 12 that prevent the balls 3 from falling off when the moving block 2 is removed from the track rail 1 are attached to the lower surface of the central portion 4a and the lower surface of the side wall portion 4b of the moving block 2. Further, a nipple 9 for supplying a lubricant such as grease or lubricating oil to the endless circulation path is attached to the moving block 2.

  As shown in FIG. 2, a load ball rolling path P <b> 1 extending in the longitudinal direction of the track rail 1 is formed between the ball rolling groove 1 a of the track rail 1 and the load ball rolling groove 2 a of the moving block 2. An unloaded return path P2 is also formed in the moving block 2, and the unloaded return path P2 extends in parallel with the loaded ball rolling path P1.

  As shown in FIG. 3, the no-load return path constituting portion 7 and the inner peripheral guide portion 8 are formed in the moving block main body 4 by, for example, insert molding of the moving block main body 4 or incorporation of resin-molded parts. The An unloaded return path P2 extending in parallel with the loaded ball rolling groove 2a is formed in the unloaded return path configuration unit 7. The inner peripheral guide portion 8 is formed with the inner peripheral side of the direction change path P3. An outer peripheral guide portion that is the outer peripheral side of the direction change path P <b> 3 is formed in the end plate 5. By attaching the end plate 5 to the moving block body 4, a U-shaped direction change path P3 is formed. The direction change path P3 connects the loaded ball rolling path P1 and the no-load return path P2. A circuit-like infinite circulation path is formed by the loaded ball rolling path P1, the no-load return path P2, and the direction changing path P3.

  A plurality of balls 3 are arranged in a circuit-like infinite circulation path. The plurality of balls 3 roll while moving on the load ball rolling path P1. The ball 3 rolled to one end of the loaded ball rolling path P1 passes through the U-shaped direction changing path P3 and then enters the unloaded return path P2. The ball that has passed through the unloaded return path P2 passes through the opposite direction changing path P3 and then enters the loaded ball rolling path P1 again.

  A plurality of spacers 16 and 26 are sandwiched between the plurality of balls 3. The number of spacers 16 and 26 is equal to the number of balls 3. The plurality of spacers 16 and 26 are not connected by a band and are separated from each other.

  4 to 6 show the spacer 16 according to the first embodiment of the present invention. 4 shows a spacer 16 sandwiched between a pair of adjacent balls 3, FIG. 5 shows a perspective view of the single spacer 16, and FIG. 6 shows a front view and a cross-sectional view of the single spacer. As shown in FIGS. 5 and 6, the spacer 16 has a disk as a basic shape, and is bent into a wave shape so that the peripheral edge portion 17 alternately has a crest portion 17 a and a trough portion 17 b. In this embodiment, three ridges 17a are formed at equal intervals in the circumferential direction (with an interval of 120 degrees), and three valley portions 17b are spaced at equal intervals in the circumferential direction (at intervals of 120 degrees). Formed). The number of peaks 17a and valleys 17b may be three or more, and the number is not limited. For example, the peripheral edge portion 17 may be formed so as to border the periphery of the main body portion 18 of the spacer 16 and may be thicker than the main body portion 18 so that the tip of the peripheral edge portion 17 has a circular arc shape. According to this, even if the position where the peripheral part 17 contacts the ball 3 changes, the peripheral part 17 and the ball 3 can be brought into point contact. However, the peripheral portion 17 may have the same thickness as the main body portion 18. The peripheral edge portion 17 is formed in a wave shape continuous in the circumferential direction and is not divided by a slit or the like. The spacer 16 is manufactured by resin injection molding.

  On the inner side of the peripheral portion 17, a main body portion 18 is formed that is thinner than the peripheral portion 17 and has a substantially constant thickness. Similar to the peripheral portion 17, the main body portion 18 is bent into a wave shape so that a crest portion 18 a and a trough portion 18 b having the same phase as the peripheral portion are formed in the circumferential direction. The peaks 18a and 17a of the main body 18 and the peripheral edge 17 are curved so as to approach one 3-1 (see FIG. 4C) of a pair of adjacent balls 3 as going to the outer peripheral side of the spacer 16. The valley portions 18b and 17b of the main body portion 18 and the peripheral edge portion 17 are curved so as to approach the other ball 3-2 (see FIG. 4C) as going to the outer peripheral side of the spacer 16. In the cross section including the main body 18 and the crests 18a and 17a and the troughs 18b and 17b of the peripheral part 17 (see FIG. 6C), the main body part 18 and the peripheral part 17 are curved in an S shape. The ridge lines 19a (see FIG. 4B) of the peak portions 18a and 17a of the main body portion 18 and the peripheral edge portion 17 extend radially from the central through hole 21 of the spacer 16. Similarly, the ridge line 19b of the valley portions 18b and 17b extends radially from the central through hole 21 of the spacer 16.

  As shown in FIG. 4B, the outer shape of the spacer 16 is formed in a circular shape when viewed from the traveling direction of the ball 3 and the spacer 16. The outer shape of the spacer 16 may be equal to or smaller than the diameter of the ball 3. In other words, when the spacer 16 is sandwiched between the balls 3, the outer shape of the spacer 16 may be smaller than the diameter of the ball 3 in a state where the spacer 16 expands in the circumferential direction. A through-hole 21 that penetrates the main body portion in the thickness direction is formed in the center of the main body portion 18. The center line of the through hole 21 is located on a line connecting the centers of a pair of adjacent balls 3-1 and 3-2 (see FIG. 4C). A flat ring-shaped annular portion 22 is formed on the inner peripheral side of the main body portion 18 around the through hole 21 (see FIG. 6). The annular portion 22 is formed in a tapered shape whose thickness decreases toward the center. The annular portion 22 is not limited to be flat, and may be curved along the curvature of the ball 3. The main body 18 is bent into a wave shape outside the annular portion 22. When the spacer 16 is cut along a cross section including the center line of the through hole 21, the main body 18 extends in a curved manner from the annular portion 22 toward the peripheral portion 17 (see FIG. 6C).

  As shown in FIG. 4C, when the spacer 16 is sandwiched between a pair of adjacent balls 3, the three crests 17a of the peripheral edge 17 of the spacer 16 come into contact with one of the pair of balls 3-1, and the spacer Three valley portions 17b of 16 peripheral edge portions 17 are in contact with the other 3-2 of the pair of balls. Since the cross-sectional shape of the peripheral edge portion 17 of the spacer 16 is formed in an arc shape, the contact between the peripheral edge portion 17 and the ball 3 is the contact between the bent elongated cylinder and the sphere. When the elastic deformation of the peripheral edge 17 of the spacer 16 and the ball 3 is not taken into consideration, the peripheral edge 17 of the spacer 16 and the ball 3 are in point contact. The peak portion 17a of the peripheral edge portion 17 of the spacer 16 and the one ball 3-1 are in point contact at a total of three points. The three contact points CP1 (see FIG. 4B) are arranged at equal intervals of 120 degrees in the circumferential direction of the spacer 16 when viewed from the traveling direction of the spacer 16 and the ball 3. Similarly, the valley portion 17b of the peripheral edge portion 17 of the spacer 16 and the other ball 3-2 are in point contact at three points in total, and the three contact points CP2 (see FIG. 4D) are the spacer 16 and the ball 3 As seen from the direction of travel of the spacers, the spacers 16 are arranged at equal intervals of 120 degrees in the circumferential direction. The contact point CP1 between the peak portion 17a of the spacer 16 and the ball 3-1 and the contact point CP2 between the valley portion 17b of the spacer 16 and the ball 3-2 as viewed from the traveling direction of the spacer 16 and the ball 3 are It appears alternately every 60 degrees in the circumferential direction. The main body 18 of the spacer 16 and the ball 3 are not in contact with each other, and there is a gap between them.

  When the spacer 16 is sandwiched between the pair of balls 3, the spacer 16 is slightly contracted in the traveling direction. When the spacer 16 is contracted, the crests 17a and the troughs 17b that are alternately formed in the circumferential direction are elastically deformed so as to approach a flat plate shape. Since the spacer 16 is made of an elastic body such as resin, the spacer 16 is elastic to try to separate the adjacent balls 3 from each other by trying to restore the bent crests 17a and troughs 17b to the original wave shape. Force is generated. Thereby, the some ball | bowl 3 is aligned uniformly and can perform stable guidance. At this time, stress is generated inside the spacer 16. According to the present embodiment, the stress generated in the spacer 16 is distributed throughout. Since the local stress concentration of the spacer 16 is relieved, the durability and reliability of the spacer 16 can be improved. The stress generated in the spacer 16 is analyzed in examples described later.

  As described above, the spacer 16 attempts to pull the balls 3 apart from each other with a certain elastic force in the endless circulation path. This elastic force of the spacer 16 is balanced as a whole in the endless circulation path, thereby preventing a circumferential clearance that causes the balls 3 to be misaligned. Of course, even if the spacer 16 swells, the swelling of the spacer 16 is absorbed by the elastic deformation of the peaks 17a and valleys 17b. Further, various processing errors, molding errors, assembly errors, disturbance of load distribution due to the action of moments depending on use conditions, misalignment of each ball 3 due to, and the like are absorbed by elastic deformation of the peak portions 17a and valley portions 17b. . As a result, a stable distance between the balls 3 is always maintained, and the function as the motion guide device can be constantly exerted stably at a high level.

  Further, since the spacer 16 is in contact with the ball 3 in a very small area, a stable and low rolling resistance is obtained, and the wear of the spacer 16 is also extremely reduced. Even if an unexpected force acts on the balls 3 and the balls 3 approach each other, the elastic deformation of the peaks 17a and the valleys 17b absorbs the approach between the balls 3, and the thickness of the main body of the spacer 16 is increased. Therefore, problems such as breakage of the spacer 16 can be avoided.

  The portion of the spacer 16 that is in contact with the actual ball 3 is preferably as small as possible in view of the basic functional aspects of the rolling motion such as rolling resistance, wear, and heat generation. If the ball 3 is supported at three points, the position is stabilized. Therefore, it is desirable that the peak portion 17a and the valley portion 17b are in point contact with the ball at three points. However, if wear is more worrisome under adverse environmental conditions, the number of peaks 17a and valleys 17b may be extra 4, 5, 6. In that case, contact is made at three places at first, and the remaining peak portions 17a and valley portions 17b start to work due to the progress of wear and the like, and finally, it is supported by all peak portions 17a and valley portions 17b. Good.

  When viewed from the traveling direction of the spacer 16 and the ball 3, the outer shape of the spacer 16 is formed in a circular shape, and the spacer 16 is a continuous body in the circumferential direction. Therefore, when the spacer 16 circulates in the infinite circuit, the spacer 16 The spacer 16 smoothly circulates through the infinite circuit without being caught by the joint of the infinite circuit.

  A through hole 21 is formed in the spacer 16 so as to penetrate in the traveling direction of the spacer 16. When the lubricant passes through the through-hole 21, the lubricant on both sides in the traveling direction of the spacer 16 can be moved back and forth. Since the peripheral edge portion 17 and the main body portion 18 of the spacer 16 are bent in a wave shape in the circumferential direction, there is a space between the spacer 16 and the ball 3 that can hold the lubricant. Since the peaks 17a and valleys 17b of the spacer 16 and the balls are in point contact, the scraping of the lubricant is reduced.

  FIG. 7 shows another example of the spacer. In the figure, (a) is a front view, (b) is a side view, and (c) is a cross-sectional view. The spacer 26 in this example is also formed in a wave shape having a peripheral portion alternately having a crest portion 27a and a trough portion 27b in the circumferential direction. The spacer 26 has three peak portions 27a that contact one ball 3-1 of a pair of adjacent balls 3, and at least three valley portions 27b that contact the other ball 3-2. The spacer 26 and one ball 3-1 are in point contact at a total of three points CP1, and the spacer 26 and the other ball 3-1 are also in point contact at a total of three points CP2. A through hole 29 is formed in the center of the spacer 26 so as to penetrate the spacer 26 and the ball 3 in the traveling direction.

  The spacer 26 of this example is different from the spacer 16 of the above embodiment in the following points. As shown in FIG. 7A, the spacer 26 is formed by bending a disk into a wave shape, and the front shape of the spacer 26 is closer to a hexagonal shape than the circular shape. As shown in FIG. 7C, the spacer 26 is formed to have a constant thickness throughout (the peripheral portion 17 is formed to be thicker than the main body portion 18 as in the spacer 16, or The portion 22 is not formed thinner than the main body portion). In the cross section including the center of the through hole 29, the spacer 26 is curved in an S shape (the flat annular portion 22 is not formed like the spacer 16). As shown in this example, the spacers 16 and 26 may be variously modified without changing the gist of the present invention.

  FIG. 8 shows a screw device in which the spacers 16 and 26 of the present invention are incorporated. The screw device includes a screw shaft 31 in which a spiral ball rolling groove 31a is formed on the outer peripheral surface, and a nut in which a spiral load ball rolling groove 32a facing the ball rolling groove 31a is formed on the inner peripheral surface. 32.

  The screw shaft 31 is formed by cutting and grinding or rolling a spiral ball rolling groove 31a having a predetermined lead on the outer peripheral surface of a steel bar such as carbon steel, chrome steel, or stainless steel. . The number of strips of the ball rolling groove 31a is variously set such as one strip, two strips, and three strips. The cross section of the ball rolling groove 31a has a circular arc groove shape composed of a single arc or a Gothic arch groove shape formed by combining two arcs.

  The nut 32 is formed by forming a spiral load ball rolling groove 32a having a predetermined lead on a cylindrical inner peripheral surface of carbon steel, chrome steel, stainless steel or the like by cutting and grinding or rolling. is there. The nut 32 includes a nut body 35 in which a load ball rolling groove 32 a is processed on an inner peripheral surface, and a pair of end caps 38 as lid members provided at both ends of the nut body 35. A flange 34 for attaching the nut 32 to the mating part is formed at the end of the outer periphery of the nut body 35 in the axial direction. The load ball rolling groove 32 a of the nut body 35 faces the ball rolling groove 31 a of the screw shaft 31. In the nut body 35, a ball return path 32b penetrating in the axial direction of the nut body 35 is opened to circulate the ball 33. The end cap 38 is opened with a direction changing path for picking up the ball 33 rolling on the ball rolling groove 31a of the screw shaft 31 and guiding it to the ball return path 32b. There are a plurality of infinite circulation paths composed of a load ball rolling path, a direction switching path, and a ball return path 32b between the ball rolling groove 31a of the screw shaft 31 and the load ball rolling groove 32a of the nut body 35. Balls 33 are arranged and accommodated.

  When the screw shaft 31 is rotated, the nut 32 fitted to the screw shaft 31 via the ball 33 moves in the axial direction. At the same time, the ball 33 circulates through the infinite circuit. The ball 33 rolling on the load ball rolling path rolls up to one end of the load ball rolling path, and then scoops up into the direction changing path of the end cap 38, passes through the ball return path 32b, and then from the opposite end cap 38. It is returned to the other end of the original load ball rolling path.

  Spacers 16 and 26 for preventing contact between the balls 33 are interposed between the balls 33. As the spacers 16 and 26, the spacers 16 and 26 of the above embodiment are used.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not change the summary of this invention. For example, in the above embodiment, the linear guide in which the moving block moves linearly has been described. However, the present invention can also be applied to a curved motion guide device in which the moving block moves in a curved manner. Furthermore, the present invention can also be applied to a ball spline composed of a track shaft as a track member and an outer cylinder surrounding the track shaft as a moving member. Furthermore, the present invention can also be applied to a rotary bearing composed of an outer ring as a race member and an inner ring as a moving member.

  The plurality of spacers may be connected in series by a band. The contact positions of the ridges and valleys on the peripheral edge of the spacer and the ball are not limited to the vicinity of the outer periphery of the spacer, and they may contact at a position that is 1/2 or more of the spacer radius. If there is a space through which the lubricant can pass outside the spacer, it is not necessary to make a through hole in the center of the spacer. The main body portion of the spacer may be formed in a flat plate shape, and only the peripheral portion of the spacer may be formed in a wave shape.

  When the spacer 16 of this embodiment is sandwiched between the pair of balls 3 and the spacer 16 is elastically deformed by bringing the pair of balls 3 close to each other, the stress distribution generated in the spacer 16 is analyzed by FEM.

FIG. 9 shows the analysis conditions. As shown in FIG. 9A, an FEM model in which the spacer 16 of this embodiment is sandwiched between a pair of balls 3 is used. As shown in FIG. 9B, as boundary conditions, the displacement of the lower ball 3-2 in the xyz direction was constrained, and the displacement of the upper ball 3-1 in the xy direction was constrained. Then, the position of the upper ball 3-1 in the z direction was changed by a ball pressing amount δz. Under this boundary condition, the distribution of the equivalent stress generated in the spacer 16 was analyzed. Table 1 shows the material property values of the spacer 16 and the ball 3 used in the FEM analysis.

  FIG. 10A shows the amount of displacement of each part of the spacer 16 when the push-in amount is sequentially changed to 0.05 mm, 0.10 mm, 0.20 mm, and 0.30 mm. As the push-in amount increased to 0.10 mm and 0.20 mm, the displacement amount of each part of the spacer 16 also increased. However, the amount of displacement of a part of the spacer 16 did not increase locally, and the amount of displacement increased substantially uniformly over the entire peak portion 17a and valley portion 17b of the spacer 16. Even if the pushing amount is 0.30 mm, this tendency is not changed, but the increase in the displacement amount in the vicinity of the peaks 17a and valleys 17b of the spacer 16 is conspicuous.

  FIG. 10B shows the equivalent stress of each part of the spacer 16 when the pressing amount is sequentially changed to 0.05 mm, 0.10 mm, 0.20 mm, and 0.30 mm. As the push-in amount increased to 0.10 mm and 0.20 mm, the equivalent stress at each part of the spacer 16 also increased. However, the equivalent stress of a part of the spacer 16 did not partially increase, and the equivalent stress increased substantially uniformly over the entire peak portion 17a and valley portion 17b of the spacer 16. Even when the push-in amount was 0.30 mm, this tendency was not changed. The equivalent stress in the vicinity of the peaks 17a and troughs 17b of the spacer 16 did not partially increase. As a result of the analysis of the equivalent stress, it was found that the stress is distributed throughout the spacer 16 and the local stress concentration is alleviated.

  FIG. 11 is a graph showing the relationship between the indentation amount and the maximum equivalent stress generated in the spacer 16. As the push-in amount increases from 0.0 mm to 0.20 mm, the maximum equivalent stress gradually increases from 0 MPa to about 400 MPa. When the indentation amount exceeded 0.20 mm, the maximum equivalent stress did not increase and maintained a substantially constant value at 400 MPa.

DESCRIPTION OF SYMBOLS 1 ... Track rail (track member), 1a ... Ball rolling groove (rolling element rolling part), 2 ... Moving block (moving member), 2a ... Loaded ball rolling groove (load rolling element rolling part), 3 ... Ball (rolling element), 16, 26 spacer, 17 peripheral edge, 17a, 27a ... mountain, 17b, 27b ... valley, 18 ... main body, 18a ... main body, 18b ... main body valley Part, 21, 29 ... through hole, 31 ... screw shaft, 31a ... ball rolling groove (rolling element rolling groove), 32 ... nut, 32a ... loaded ball rolling groove (load rolling element rolling groove), 33 ... Ball (rolling element)

Claims (5)

A motion guide device in which a plurality of rolling elements are interposed between a raceway member and a moving member that moves along the raceway member, or a plurality of rolling elements that are capable of rolling motion between a screw shaft and a nut. A spacer that is incorporated in the interposed screw device and is arranged between the rolling elements so as to prevent contact between the rolling elements,
The spacer has a disk as a basic shape, and a main body portion formed in a continuous wave shape having alternately crests and troughs in the circumferential direction, and a peripheral edge formed so as to border the periphery of the main body portion And comprising
The peak portion of the spacer is curved so as to approach one of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer,
The valley portion of the spacer is curved so as to approach the other of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer,
The spacer in which the crest portion of the peripheral portion of the spacer contacts one of a pair of adjacent rolling elements, and the trough portion of the peripheral portion of the spacer contacts the other of the adjacent pair of rolling elements. A plurality of the peak portions of the spacer are provided, and each peak portion is in point contact with the one rolling element,
The spacer according to claim 1, wherein a plurality of the valley portions of the spacer are provided, and each valley portion makes point contact with the other rolling element. The crests of the spacer are provided with three or more at equal intervals in the circumferential direction when viewed from the moving direction of the rolling elements and the spacer,
3. The spacer according to claim 1, wherein three or more of the valley portions of the spacer are provided at equal intervals in the circumferential direction when viewed from the moving direction of the rolling elements and the spacer. A track member having a rolling element rolling part, a moving member having a loaded rolling element rolling part facing the rolling element rolling part, the rolling element rolling part of the track member, and the load rolling of the moving member In a motion guide device comprising a plurality of rolling elements arranged so as to be capable of rolling motion with a moving body rolling part, and a plurality of spacers arranged between the rolling elements so as to prevent contact between the rolling elements,
The spacer has a disk as a basic shape, and a main body portion formed in a continuous wave shape having alternately crests and troughs in the circumferential direction, and a peripheral edge formed so as to border the periphery of the main body portion And comprising
The peak portion of the spacer is curved so as to approach one of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer,
The valley portion of the spacer is curved so as to approach the other of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer,
The motion guide device in which the crest portion of the peripheral portion of the spacer contacts one of a pair of adjacent rolling elements, and the trough portion of the peripheral portion of the spacer contacts the other of the adjacent pair of rolling elements. A screw shaft having a spiral rolling element rolling groove, a nut having a load rolling element rolling groove facing the rolling element rolling groove, the rolling element rolling groove of the screw shaft, and the load of the nut In a screw device comprising: a plurality of rolling elements arranged so as to be capable of rolling between the rolling element rolling grooves; and a plurality of spacers arranged between the rolling elements so as to prevent contact between the rolling elements.
The spacer has a disk as a basic shape, and a main body portion formed in a continuous wave shape having alternately crests and troughs in the circumferential direction, and a peripheral edge formed so as to border the periphery of the main body portion And comprising
The peak portion of the spacer is curved so as to approach one of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer,
The valley portion of the spacer is curved so as to approach the other of a pair of adjacent rolling elements as it goes to the outer peripheral side of the spacer,
The screw device in which the crest portion of the peripheral portion of the spacer contacts one of a pair of adjacent rolling elements, and the trough portion of the peripheral portion of the spacer contacts the other of the adjacent pair of rolling elements.