JP2011112069A - Motion guide device and roller screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motion guide device and a roller screw capable of preventing outbreaks of skew even if there is an inclination error in a fitting surface and an offset load is applied. <P>SOLUTION: This motion guide device includes: a track member 1; a moving member 2 having a plurality of load roller rolling surfaces 2d facing a plurality of roller rolling surfaces 1b and a plurality of non-load return passages 8 extending in parallel with the plurality of load roller rolling surfaces 2d and a plurality of direction change-over passages 6 connecting the plurality of load roller rolling surfaces 2d and the plurality of non-load return passage 8 to each other; and a plurality of rollers 3 arranged in a plurality of roller circulation passages. In at least one roller circulation passage of the plurality of roller circulation passages, a plurality of rollers 3 in two line or more are arranged per roller circulation passage. When the moving member 2 is moved in the longitudinal direction of the track member 1 relative to the track member 1, two lines or more of the plurality of rollers 3 circulate in the roller circulation passage by rolling between the roller rolling surface 1b of the track member 1 and the load roller rolling surface 2d of the moving member 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a motion guide device that guides a linear motion of a moving body such as a table of a machine tool, and more particularly to a motion guide device having a large rated load using a roller as a rolling element.

  The present invention also relates to a screw device in which a rolling element is interposed between a screw shaft and a nut, and more particularly to a roller screw using a roller as the rolling element.

  The motion guide device using a roller as a rolling element has an advantage that a rated load (rigidity) can be increased and a moving body such as a table can be moved with high accuracy compared to the case where a ball is used. For this reason, it is suitable for applications such as precision machine tools, heavy cutting machines, semiconductor / liquid crystal manufacturing apparatuses, etc., and in recent years, the demand has increased dramatically.

  Generally, this type of motion guide device includes a track member attached to a base, a moving member attached to a table, and a plurality of rollers interposed between the track member and the moving member as rolling elements so as to allow rolling motion. . The moving member includes a pair of U connecting the loaded roller rolling surface facing the roller rolling surface of the raceway member, an unloaded return path parallel to the loaded roller rolling surface, and the loaded roller rolling surface and the unloaded return path. A character-shaped direction change path is formed. Along with the relative movement of the moving member with respect to the track member, the roller circulates in a roller circulation path composed of a loaded roller rolling surface, a no-load return path, and a pair of direction changing paths. When a roller is used as the rolling element, the contact area with the rolling surface can be made larger than that of the ball, so that the load that can be applied can be increased.

  While the ball can roll in all directions, the moving direction of the roller is limited to one direction. In order to smoothly roll the roller between the track member and the moving member, the rotation axis of the roller must be orthogonal to the traveling direction of the roller. However, the parallelism between the roller rolling surface of the track member and the roller rolling surface of the moving member may not be maintained due to a processing error in manufacturing the motion guide device, an installation error during use, an offset load, and the like. In this case, a phenomenon called skew in which the rotation shaft of the roller tilts from a normal state may occur. When the skew occurs, the roller cannot smoothly roll and move.

  In the motion guide device, the roller is unloaded in the unloaded return path and is loaded in the loaded roller rolling path. When an unbalanced load is received or when there is an installation error, the unloaded roller must enter the loaded roller rolling path with an incorrect parallelism in the unloaded return path, which causes skew.

  The applicant, as a motion guide device capable of achieving both rigidity and skew prevention, pays attention to the ratio of the diameter and length of the roller as a rolling element, and the diameter of the roller is D and the length of the roller in the rotation axis direction is L. Then, by setting 1.5 <L / D <3, the motion guide can improve the rigidity and prevent the occurrence of skew compared to the motion guide device of the ball type of the same model number. An apparatus has been proposed (Patent Document 1).

JP 2002-310151 A

  In recent years, there is a demand for increasing the rated load of the motion guide device while maintaining the accuracy of the mounting surface of the base and the table equivalent to the motion guide device using a conventional ball. In other words, there is a demand for a motion guide device that can absorb and allow for an inclination error and an offset load on a mounting surface even though it is a motion guide device using a roller. There is also a demand for increasing the rated load of a roller screw while maintaining the accuracy of attaching a nut or screw shaft to that of a conventional ball screw.

  However, when there is an inclination error or an offset load on the mounting surface, the roller is likely to be skewed, and it is difficult to smoothly roll the roller.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a motion guide device and a roller screw that are less likely to cause skew even when there is an inclination error of the mounting surface, an offset load, or the like.

  One aspect of the present invention includes a raceway member having a plurality of roller rolling surfaces extending in a longitudinal direction, a plurality of load roller rolling surfaces facing the plurality of roller rolling surfaces, and the plurality of load rollers. A plurality of unloaded return paths extending in parallel with the rolling surface; a plurality of moving members having a plurality of direction changing paths connecting the plurality of loaded roller rolling surfaces to the plurality of unloaded return paths; And a plurality of rollers arranged in a plurality of roller circulation paths composed of a plurality of roller unrolling surfaces, a plurality of unloaded return paths, and a plurality of direction change paths, In at least one roller circulation path of the path, a plurality of rollers of two or more rows per line are arranged, and when the moving member is moved relative to the track member in the longitudinal direction of the track member, A plurality of rollers in a row or more are A motion guide device for rolling movement between the loaded roller rolling surface of the member of the roller rolling surface and said moving member.

  Another aspect of the present invention has a screw shaft having a spiral roller rolling surface on the outer peripheral surface, and a spiral load roller rolling surface facing the roller rolling surface of the screw shaft on the inner peripheral surface. A circulating member having a no-load return path for connecting one end and the other end of the nut and the spiral loaded roller rolling surface; the loaded roller rolling surface of the nut; and the unloaded returning of the circulating member A plurality of rollers arranged in a roller circulation path composed of a path, and at least one roller circulation path of the plurality of roller circulation paths has a plurality of rollers arranged in two or more rows per stripe, When the nut is rotated relative to the screw shaft, the plurality of rollers in two or more rows roll between a roller rolling surface of the screw shaft and a load roller rolling surface of the nut. It is a roller screw.

  If the difference between the maximum value and the minimum value of the stress distribution acting on the roller from the rolling surface increases, the difference in the amount of elastic deformation of the roller increases and the roller is likely to be skewed. By making the rollers in double rows, the variation in the stress distribution acting on the rollers in each row can be reduced, so that the occurrence of skew can be prevented. The rated load of the roller is determined by the length of the contact portion of the roller (length in the axial direction). Even if the arrangement is double, if the contact part length is made approximately the same, the rated load does not decrease so much.

1 is an exploded perspective view of a linear motion guide device according to an embodiment of the present invention. Sectional view of the motion guide device The figure which shows the direction change path formed in an end plate Detailed view of the roller interposed between the roller rolling surface and the loaded roller rolling surface (only the end abutting wall) Detailed view of the roller interposed between the roller rolling surface and the loaded roller rolling surface (only the central abutment wall) Detailed view of the roller interposed between the roller rolling surface and the loaded roller rolling surface (end abutting wall + center abutting wall) Diagram showing moment load acting on moving block The figure which compared the stress distribution which generate | occur | produces on a roller ((a) in a figure shows a single row roller, (b) in a figure shows a double row roller) Schematic showing the roller tilted at a skew angle θ The figure which shows the retainer holding two rows of rollers ((a) in the figure shows a perspective view, (b) in the figure shows a plan view, and (c) in the figure shows a side view) The figure which shows the other example of a retainer ((a) in a figure shows a top view, (b) shows a side view in a figure) Plan view showing still another example of retainer Plan view showing still another example of retainer Partial perspective view of end plate Perspective view of internal / external direction change path component Perspective view of inner direction change path component The figure which shows the surface pressure distribution which generate | occur | produces when the load Q acts on a roller Schematic diagram of Type A, Type B, and Type C rollers Graph showing the contact pressure acting on the contact part when the roller contact part length is changed Graph showing the relationship between L / D of roller and surface pressures σmax and σmin A graph showing the relationship between the roller L / D and the surface pressure ratio σmax / σmin The perspective view of the roller screw in one Embodiment of this invention Nut perspective view Sectional view showing two rows of rollers between the roller rolling surface and the loaded roller rolling surface The perspective view which shows the positional relationship of a circulation member and a screw shaft. Sectional view showing track rail of motion guide device of DF structure

  Hereinafter, based on an accompanying drawing, a movement guide device of one embodiment of the present invention is explained in detail. FIG. 1 is an exploded perspective view of the motion guide device, and FIG. 2 is a cross-sectional view orthogonal to the longitudinal direction of the track rail.

  The motion guide device includes a track rail 1 as a track member extending linearly in the longitudinal direction, and a moving block 2 as a moving member that is assembled to the track rail 1 through a number of rollers 3 so as to be movable in the longitudinal direction. It has.

  As shown in FIG. 2, the track rail 1 has a substantially quadrangular cross section, and V-shaped recesses 1a are formed on the left and right side surfaces thereof. In a state where the bottom surface of the track rail 1 is disposed on a horizontal plane (the state shown in FIG. 2), roller rolling surfaces 1b are formed on the upper and lower wall surfaces inclined by the dent 1a. On the left and right side surfaces of the track rail 1, a total of four roller rolling surfaces 1 b are formed on the upper and lower sides. Each roller rolling surface 1b is formed in a planar manner and extends elongated along the longitudinal direction of the track rail 1. The plane including the upper roller rolling surface 1b and the plane including the lower roller rolling surface 1b intersect at an angle of approximately 90 degrees. By arranging the four roller rolling surfaces 1b in such a manner, a vertical load (radial load, reverse radial load), a horizontal load, and a moment load acting on the moving block 2 can be applied. The track rail 1 is made of metal, and the roller rolling surface 1b is ground.

  As shown in FIG. 1, the moving block 2 is composed of four load roller rolling surfaces 2d opposed to the four roller rolling surfaces 1b of the track rail 1, and four strips parallel to the four load roller rolling surfaces 2d. Direction change path constituting member 5, in which a direction change path connecting the moving block main body 4 in which the no-load return path 8 is formed, the four load roller rolling surfaces 2d and the four no-load return paths 8 respectively is formed. 24, 30 are provided. The direction change path constituting members 5, 24, and 30 are composed of the end plate 5, the inner direction change path constituting member 30, and the inner and outer direction change path constituting member 24. Two direction change paths are formed on each of the left and right side walls of the moving block 2. The two direction changing paths cross three-dimensionally at the end of the moving block 2 in the moving direction. The end plate 5 is formed with an outer peripheral side of an outer direction change path that intersects three-dimensionally. The inner direction change path constituting member 30 is formed with the inner peripheral side of the inner direction change path. The inner and outer direction change path constituting member 24 is formed with an outer peripheral side of the inner direction change path and an inner peripheral side of the outer direction change path. The end plate 5 is attached to the end surface of the moving block body 4 in the moving direction. The inner direction change path constituting member 30 and the inner / outer direction change path constituting member 24 are incorporated in the end plate 5.

  The moving block main body 4 includes a central portion 2 a that faces the upper surface of the track rail 1 and side wall portions 2 b that extend downward from the left and right sides of the central portion 2 a and face the left and right side surfaces of the track rail 1. On the side wall 2b of the moving block main body 4, a V-shaped protruding portion 2c is formed which has a shape matched with a recess 1a provided on the side surface of the track rail 1. Two load roller rolling surfaces 2d corresponding to the roller rolling surface 1b are formed on both side surfaces of the protruding portion 2c. As shown in FIG. 2, the load roller rolling surface 2d on the upper side of the protrusion 2c is parallel to the roller rolling surface 1b on the upper side of the track rail 1, and the load roller rolling surface on the lower side of the protrusion 2c. 2d is parallel to the lower roller rolling surface 1b. The plane including the upper load roller rolling surface 2d and the plane including the lower load roller rolling surface 2d intersect at an angle of approximately 90 degrees.

  Four circuit-like roller circulation paths are formed by the four loaded roller rolling surfaces 2d of the moving block 2, the four unloaded return paths 8, and the four direction change paths. In each roller circulation path, a plurality of rollers 3 in two rows per line are arranged. The plurality of rollers 3 in two rows are held by a retainer 10 as a single resin cage. The plurality of rollers 3 in two rows are parallel to each other in the axial direction. A slight gap is formed in the axial direction of the roller 3 between the plurality of rollers 3a in each row.

  As shown in the cross-sectional view of FIG. 2, two rows of a plurality of rollers 3 are interposed between the roller rolling surface 1 b of the track rail 1 and the load roller rolling surface 2 d of the moving block body 4. The plurality of rollers 3 in two rows receive a compressive load between the roller rolling surface 1b and the load roller rolling surface 2d. When the moving block body 4 moves relative to the track rail 1, a plurality of rollers 3 in two rows are loaded on the load roller rolling path 7 (between the roller rolling surface and the load roller rolling surface 2d). Roll while exercising. As shown in FIG. 3, the roller 3 that has rolled to one end of the load roller rolling surface 2 d of the moving block body 4 is scooped up into the end plate 5 to form a U-shaped direction change path 6 (inner direction change path 6. -1 and the outer direction change path 6-2), and then enters the no-load return path 8. The load roller rolling surface 2 d of the moving block body 4 is provided in two upper and lower strips on each of the left and right side walls 2 b of the moving block body 4. The no-load return path 8 is provided on each of the left and right side wall portions 2b of the moving block main body 4 in two directions. The inner direction change path 6-1 connects the upper load roller rolling surface 2d and the lower no-load return path 8 and the outer direction change path 6-2 connects the lower load roller rolling surface 2d and the upper load roller rolling surface 2d. Connect the no-load return path 8.

  In the direction change path 6 and the no-load return path 8, there is a gap around the roller 3, and the roller 3 is in an unloaded state. For this reason, the roller 3 moves while being pushed by the subsequent roller 3. The roller 3 that has passed through the no-load return path 8 passes through the opposite direction change path 6 and then enters the loaded roller rolling path 7 again. A circuit-like roller circulation path is formed by the loaded roller rolling path 7, the direction changing path 6 and the no-load return path 8.

  FIG. 4 shows a detailed view of the roller 3 interposed between the roller rolling surface 1b and the load roller rolling surface 2d. A cylindrical roller is used as the roller 3. The side surface (outer peripheral surface) of the roller 3 is not crowned and is formed completely straight. The roller rolling surface 1b and the load roller rolling surface 2d are also not crowned and are completely straight in the cross-sectional view. The end surface of the roller 3 is formed into a flat surface, and an arcuate chamfer is applied to a corner that is a connection portion between the end surface and the side surface of the roller 3. In the roller 3, the outer peripheral surface of the roller excluding chamfering is in contact with the roller rolling surface 1b and the load roller rolling surface 2d.

  In the conventional motion guide device, in order to prevent skew, the roller itself, the roller rolling surface and the load roller rolling surface are crowned. However, since three-dimensional machining is required to perform crowning, new problems such as machining errors and variations are added to the rollers and rolling surfaces. By using a cylindrical roller with no crowning for the roller 3 and forming the cross sections of the rolling surfaces 1b and 2d straight, it is not necessary to perform three-dimensional processing, and the roller 3 and the rolling surfaces 1b and 2d It can be manufactured stably and with high accuracy, and the number of processing steps can be reduced. Here, when the diameter of the roller 3 is D and the length (distance from the end face to the end face) is L, L / D ≦ 1 is set. The reason why the ratio of the rollers 3 is set in this way will be described later. The end surface of the roller 3 may be formed in a part of a spherical surface. In this case, the length of the roller 3 is the entire length of the roller 3 including the spherical surface.

  A pair of metal end abutting walls 31 that can come into contact with the outermost end surfaces 3b of the plurality of rollers 3 in two rows are formed at both ends in the width direction of the load roller rolling surface 2d. The end portion abutting wall 31 is integral with the load roller rolling surface 2d and extends in the longitudinal direction of the load roller rolling surface 2d. No abutting wall is provided between the rollers 3a in each row. The holding members 11 and 13 incorporated in the movable block main body 4 can also come into contact with the outer end surface 3 b of the roller 3.

  FIG. 5 shows another example of the abutting wall. In this example, the load roller rolling surface 2d of the moving block body 4 has a metal center abutting wall 32 that can contact the opposing end surfaces 3c of the plurality of rollers 3 in two rows between the rows. It is formed. The center abutting wall 32 is integral with the load roller rolling surface 2d and extends in the longitudinal direction along the load roller rolling surface 2d. In this example, the end abutting walls 31 (see FIG. 4) are not formed at both ends in the width direction of the load roller rolling surface 2d.

  FIG. 6 shows an example in which the end butting wall 31 and the center butting wall 32 are formed on the load roller rolling surface 2d. The load roller rolling surface 2d of the moving block body 4 has a pair of metal end abutting walls 31 that can contact the outermost end surfaces 3b of the plurality of rollers 3 in two rows at both ends in the width direction. Are formed, and between the rollers 3a in each row, a metal center abutting wall 32 that can contact the opposing end surfaces 3c of the plurality of rollers 3 in two rows is formed. The plurality of rollers 3 a in each row are sandwiched between the center abutting wall 32 and the end abutting wall 31.

FIG. 8 is a comparison of the stress distribution generated in the roller between the conventional one-row roller and the two-row roller of the present invention. When there is an attachment error of the motion guide device (for example, the parallelism of the two track rails 1 is out of order) or when a moment load acts on the motion block 2 of the motion guide device (see FIG. 7), the motion block The loaded roller rolling surface 2 d of the main body 4 is inclined with respect to the roller rolling surface 1 b of the track rail 1. At that time, a stress distribution as shown in FIG. If the difference between the stress σ ₁ at one end of the roller and the stress σ ₂ at the other end is large, the amount of elastic deformation also differs. The more the difference in the amount of elastic deformation, the easier the skew occurs. 8 rollers 3 by double row of (b), the it is possible to reduce the difference in stress in sigma ₁ - [sigma] ₂ from σ _{1 '-σ 2'} or σ _{3 '-σ 4'} . Since the difference in the stress distribution of the rollers 3 per row can be reduced, it is difficult for skew to occur. In particular, when a roller with L / D ≦ 1 is used, the shape of the roller 3 itself is also less likely to cause skew, so that skew is less likely to occur. The relationship between the L / D of the roller 3 and the skew will be described later.

  The rated load of the motion guide device is determined by the contact length between the roller 3 and the roller rolling surface 1b (or the loaded roller rolling surface 2d). Even if the rollers 3 are double-rowed, if A + A = 2A, which is the sum of the lengths of the rollers 3, is substantially equal to the length B of the single-row rollers R, the rated load of the motion guide device can be kept from dropping.

  As shown in FIGS. 4 to 6, it is possible to form the abutting walls 31 and 32 that are in contact with the end surface of the roller 3 by forming the rollers 3 in a double row. In order to roll the roller 3 along a normal path, it is necessary to correct both ends of the roller 3 with the abutting walls 31 and 32 and correct the skewed roller 3. However, in the conventional general motion guide device, the abutting walls 31 and 32 are not formed. One reason is that if the abutting walls 31 and 32 are formed, it is difficult to grind the load roller rolling surface 2d. However, if the length L of the roller 3 is larger than that, when the roller 3 is skewed, the roller 3 pushes the abutting walls 31 and 32 with a strong force while rubbing against the abutting walls 31 and 32. This is because the abutting walls 31 and 32 are deformed or the roller 3 is locked (causes problems such as galling or seizure). As shown in FIG. 9, when the roller 3 is inclined by the skew angle θ with respect to the traveling direction, the amount by which the end surface of the roller 3 deforms the abutting walls 31 and 32 is given by l / 2 · tan θ. If this value is large, the force with which the roller 3 pushes against the abutting walls 31 and 32 also becomes large, causing the above-mentioned problems. By reducing the length L of the roller 3 by forming a double row, the force with which the roller 3 pushes the abutting wall is also reduced, so that the strength of the abutting walls 31 and 32 can be ensured.

  As shown in FIG. 6, it is ideal that the abutting walls 31 and 32 can come into contact with both end faces of the roller 3. This is because the roller 3 can be rolled along a regular path. However, since the roller 3 is held at a predetermined position by the retainer 10, the retainer 10 prevents the roller 3 entering the loaded roller rolling surface 2 d from the no-load return path 8 from being caught on the abutting walls 31 and 32. To do. For this reason, as shown in FIGS. 4 and 5, only one of the abutting walls 31 and 32 may be provided, and only one of the abutting walls 31 and 32 may be in contact with the roller 3.

  FIG. 10 shows a state in which the plurality of rollers 3 are held by the retainer 10. The plurality of rollers 3 in two rows are held by a single resin retainer 10. The retainer 10 is interposed between a plurality of rollers 3a in each row, and a plurality of spacers 10a for preventing the rollers 3a from contacting each other, and a plurality of spacers at the outermost ends of the plurality of rollers 3 in two rows A pair of flexible belts 10b that connect 10a and a flexible central belt 10c that connects a plurality of spacers between a plurality of rollers 3a in each row. The length of each of the plurality of spacers 10a is substantially equal to the length of the roller 3, and curved concave portions corresponding to the roller 3 are formed at both ends in the traveling direction. The pair of belts 10b project outward from the end face of the roller 3 in the axial direction, and are guided by guide grooves formed in the roller circulation path (see FIG. 4). As shown in the plan view of FIG. 10B and the side view of FIG. 10C, the pitch P and phase of the plurality of rollers 3a in each row are the same between the two rows.

  By holding the plurality of rollers 3 in two rows on the retainer 10, the alignment guidance of the rollers 3 can be performed. Further, the roller 3 is in a state of being freely movable in the axial direction and the traveling direction by utilizing the stretchability of the retainer 10. For this reason, even if a skew occurs in one roller 3, it is difficult for the skew to be transmitted to other rollers 3. Furthermore, even if a roller advance / delay (movement amount difference) occurs between the rollers 3a in each row, it is slight. Even if a plurality of rollers 3 in two rows are held by one retainer 10, the advance and delay of the rollers 3a in each row can be absorbed by the amount of elastic deformation of the retainers 10.

  FIG. 11 shows another example of the retainer 10. In this example, the pitch P of the plurality of rollers 3a in each row is the same between the two rows, and the phase of the plurality of rollers 3a in each row is shifted by ½ of the pitch. Since the configuration of the plurality of spacers 10a, the pair of flexible belts 10b, and the central belt 10c is the same as that of the retainer 10 shown in FIG. 10, the same reference numerals are given and description thereof is omitted. By arranging a plurality of rollers 3 in two rows in a staggered manner as in this example, the rollers 3 can be smoothly circulated.

  FIG. 12 shows still another example of the retainer 10. In this example, the opposite end surfaces of the plurality of rollers 3a in each row are brought into contact, and the two rows of rollers 3 are held by the retainer 10 in a state where the two rows of rollers are regarded as one row of rollers. . The retainer 10 has a pair of flexible spacers connecting a plurality of spacers 10a interposed in the row direction of the plurality of rollers 3 in two rows and a plurality of spacers 10a at the outermost ends of the plurality of rollers 3 in two rows. Belt 10b.

  FIG. 13 shows still another example of the retainer. In this example, the plurality of rollers 3 in two rows are held by two retainers 10 corresponding to the number of rows in a state of being spaced apart in the row direction. Each retainer 10 is interposed between a plurality of rollers 3a in the row direction of each row, and includes a plurality of spacers 10a for preventing the rollers 3a from contacting each other, and an end portion in the axial direction of the plurality of rollers 3a in each row. And a flexible belt 10b that connects the plurality of spacers 10a. According to this example, since the retainers 10 are separated from each other, the plurality of rollers 3a in each row are not affected by the plurality of rollers 3a in other rows. For this reason, even if skew occurs in one row of rollers 3a, it is possible to prevent the other row of rollers 3a from being affected.

  As shown in FIG. 1, long holding members 11, 12, and 13 are attached to both side edges of the load roller rolling surface 2 d of the moving block body 4. The resin holding members 11, 12, 13 guide the retainer 10 so that the roller 3 can be prevented from falling off the loaded roller rolling surface 2d when the moving block 2 is removed from the track rail 1. A guide groove is formed. In a state where the bottom surface of the track rail 1 is disposed on a horizontal plane (the state shown in FIG. 1), the first holding member 11 guides the lower side of the retainer 10 that moves on the lower roller rolling surface 2d (FIG. 2). reference). The second holding member 12 guides the upper side of the retainer 10 that moves on the lower roller rolling surface 2d and guides the lower side of the retainer 10 that moves on the upper roller rolling surface 2d. The third holding member 13 guides the upper side of the retainer 10 that moves on the upper roller rolling surface 2d.

  The side wall 2b of the moving block body 4 has a through hole 14 extending in parallel with a predetermined distance from the upper and lower two load roller rolling surfaces 2d. A no-load return path constituting member 15 constituting the no-load return path 8 is inserted into the through hole 14. The no-load return path constituting member 15 is composed of a pair of pipe halves obtained by dividing an elongated pipe-shaped member into two along the axial direction. A no-load return path 8 is formed in the no-load return path constituting member 15 and a guide groove for guiding the belt 10b of the retainer 10 is formed. Both ends of the no-load return path constituting member 15 are supported by the end plate 5.

  FIG. 14 shows a perspective view of the end plate 5. The end plate 5 has the same cross-sectional shape as the movable block body 4 and includes a horizontal portion 5a and a side wall portion 5b (see FIG. 1). In the side wall part 5b, the outer peripheral side 18 of the outer direction change path with a deep depth and the outer peripheral side 19 of the inner direction change path with a shallow depth are formed so as to intersect three-dimensionally. The outer peripheral side 18 of the outer direction change path and the outer peripheral side 19 of the inner direction change path are orthogonal to each other. The outer peripheral side 19 of the inner direction change path formed shallowly is divided at the center by the outer peripheral side 18 of the outer direction change path formed deep. In addition, a guide portion 18 a that guides the outer peripheral side of the retainer 10 that passes through the outer direction change path is formed on the outer peripheral side 18 of the outer direction change path of the end plate 5. On the end face of the end plate 5, a positioning convex portion 20 for positioning the end plate 5 with respect to the movable block main body 4 is formed, and positioning concave portions 21, 22, 23 for positioning the holding members 11, 12, 13 are formed. Is formed.

  FIG. 15 shows the inward / outward direction change path constituting member 24 incorporated in the end plate 5. The entire inner / outer direction change path constituting member 24 is formed in a shape like a side groove. The inner / outer direction change path constituting member 24 is fitted on the outer peripheral side 18 of the direction change path formed in the end plate 5. An inner peripheral side 25 of the outer direction change path is formed on the outer side of the inner / outer direction change path constituting member 24, and an inner direction change together with the outer peripheral side 19 of the inner direction change path formed on the end plate 5 on the inner side. An outer peripheral side 26 of the inner direction change path constituting the outer peripheral side of the road is formed. An outer direction change path is configured by the outer peripheral side 18 of the outer direction change path formed in the end plate 5 and the inner peripheral side 25 of the outer direction change path formed in the inner / outer direction change path constituting member 24. Further, when the inner / outer direction change path constituting member 24 is fitted into the end plate, the inner direction formed in the inner / outer direction change path constituting member 24 in the divided portion of the outer peripheral side 19 of the inner direction change path formed in the end plate 5. The outer peripheral side 26 of the diverting path is fitted, whereby the entire outer peripheral side of the inner direction changing path is formed. Further, the inner / outer direction change path constituting member 24 is formed with a guide portion 25a for guiding the inner circumference side of the retainer 10 passing through the outer direction change path along the inner circumference side 25 of the outer direction change path.

  FIG. 16 shows the inner direction change path constituting member 30 constituting the inner peripheral side of the inner direction change path. The inner direction change path constituting member 30 is formed in a semi-cylindrical shape, and an inner peripheral side 30a of the inner direction change path is formed on the outer peripheral surface thereof. After the inner / outer direction change path constituting member 24 is fitted into the end plate 5, the inner direction change path constituting member 30 is fitted into the end plate 5. On both sides of the inner peripheral side 30a of the inner direction change path, guide portions 30b for guiding the inner peripheral side of the retainer 10 passing through the inner direction change path are formed.

  The significance of setting the roller to L / D ≦ 1 is as follows. Using the model shown in FIG. 17, the surface pressure acting on the contact portion of the roller 3 when the load Q is applied to the roller 3 was analyzed.

Ｑ：荷重、Ｄａ：ローラの直径、ｌ：ローラの長さ、１／ｍ＝０．３：ポアソン比である。 The load acting on the roller 3 was calculated from the following equation.

Q: load, Da: roller diameter, l: roller length, 1 / m = 0.3: Poisson's ratio.

  As shown in FIG. 17, when a load Q is applied to the roller 3, the surface pressure σmax acting on the end portion of the roller 3 becomes higher than the surface pressure σmin acting on the center portion of the roller 3. As the surface pressure ratio σmax / σmin increases, the difference between the amount of elastic deformation at the central portion of the roller 3 in the axial direction and the amount of elastic deformation at the end increases, and skew tends to occur.

  Next, as shown in FIG. 18, the surface pressure of the contact portion was analyzed by increasing the length L in the axial direction of the roller 3 in order of Type A → Type B → Type C and changing the value of L / D. The results are shown in Table 1.

  Since it was found that the surface pressure ratio σmax / σmin changes when the value of L / D changes, the surface pressure acting on the contact portion was calculated by further changing the contact portion length of the roller 3 in various ways. The result is shown in FIG. From the calculation results, the relationship between L / D and the surface pressures σmax and σmin is summarized in a graph. 20 shows the relationship between L / D and the surface pressures σmax and σmin, and FIG. 21 shows the relationship between L / D and the surface pressure ratio σmax / σmin. As shown in FIG. 21, when L / D is 1 or less, it is found that the surface pressure ratio σmax / σmin rapidly decreases and the σmin difference of the surface pressure σmax also decreases. A decrease in σmax / σmin means that skew is less likely to occur. It can be seen that by setting L / D to 1 or less, the roller is naturally less likely to cause skew. It can be seen that when L / D is 0.5 or less, skew is less likely to occur.

  FIG. 22 shows a perspective view of a roller screw in one embodiment of the present invention. The roller screw includes a screw shaft 51 having a spiral roller rolling surface 51a formed on the outer peripheral surface, and a nut having a spiral load roller rolling surface 52a facing the roller rolling surface 51a on the inner peripheral surface. 52.

  The screw shaft 51 is formed by cutting and grinding or rolling a spiral roller rolling surface 51a having a predetermined lead on the outer peripheral surface of a steel bar such as carbon steel, chrome steel, or stainless steel. . The roller rolling surface 51a has a V-shaped cross section and an opening angle of about 90 degrees (see FIG. 24). In this embodiment, two roller rolling surfaces 51 a are formed on the outer peripheral surface of the screw shaft 51. A plurality of rollers 54 are arranged in parallel on each of the two roller rolling surfaces 51a (an arrangement in which the axes of the plurality of rollers are parallel). Of course, the number of roller screws is appropriately determined depending on the application of the roller screw, such as one, two or three.

  FIG. 23 shows a perspective view of the nut 52. The nut 52 is formed by cutting and grinding or rolling a spiral load roller rolling surface 52a having a predetermined lead on the inner peripheral surface of a cylinder such as carbon steel, chrome steel, or stainless steel. is there. The load roller rolling surface 52a has a V-shaped cross section and an opening angle of about 90 degrees. A flange 52b for attaching the nut 52 to the mating part is formed at the end of the outer periphery of the nut 52 in the axial direction.

  FIG. 24 shows two rows of rollers 54 sandwiched between the roller rolling surface 51 a of the screw shaft 51 and the load roller rolling surface 52 a of the nut 52. The two rows of rollers 54 have a cylindrical shape and are stacked so that the axes 54b coincide with each other. The shape of the two rows of rollers 54 viewed from the side is close to a square. The roller 54 includes a cylindrical side surface 54c, a pair of end surfaces 54a, and a chamfered portion 54d formed between the side surface 54c and the end surface 54a. The side surfaces 54 c of the two rows of rollers 54 are in contact with the roller rolling surface 51 a of the screw shaft 51 and the load roller rolling surface 52 a of the nut 52.

  FIG. 25 shows the positional relationship between the circulation member 53 attached to the nut 52 and the screw shaft 51. Two sets of circulation members 53 are provided to circulate the rollers 54 that move on the two roller rolling surfaces 51a. The circulation member 53 includes a circulation pipe 58 that is inserted into a through-hole extending in the axial direction of the nut 52, and a pair of direction change path constituting members 62 that are attached to end portions in the axial direction of the circulation pipe 58. The circulation member 53 is formed with a no-load return passage that connects one end and the other end of the load roller rolling path. The no-load return passage is formed in the circulation pipe 58, and extends straightly in parallel with the center line of the nut 52, and is connected to both ends of the straight passage and is a curve formed in the pair of direction change path constituent members 62. And a pair of direction change paths. The roller 54 that has rolled to one end of the load roller rolling path is guided into the direction changing path of the circulation member 53, passes through the straight path, and then returned to the other end of the load roller rolling path from the remaining direction changing path.

  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 motion guide device of the above-described embodiment, V-shaped dents are formed on the left and right side surfaces of the track rail, V-shaped protrusions protruding into the dent are formed on the moving block, and the track rail A motion guide device having a so-called DB structure in which a roller rolling path is formed on a pair of upper and lower wall surfaces of a recess is shown. However, in the present invention, as shown in FIG. 26, V-shaped protrusions 61 are formed on the left and right side surfaces of the track rail 1, and the V-shaped recess corresponding to the V-shaped protrusion is formed on the moving block. Can be applied to a so-called DF structure motion guide device in which the roller rolling surfaces 63 are formed on the pair of upper and lower wall surfaces of the protruding portion 61 of the track rail 1.

  Further, three or four rows of rollers can be arranged per one line of the roller circulation path. You may use the crowning roller which gave the crown to the roller, and you may make the cross section of a rolling surface into a crowning rolling surface.

  Furthermore, in the said embodiment, although the movement guide apparatus in which a moving block moves linearly was demonstrated, this invention can also be applied also to the curved motion guide apparatus which guides a roller spline and curved movement.

  Furthermore, in the above embodiment, when the moving block is removed from the track rail, the retainer holds the plurality of rollers so that they do not fall off, but if the rollers can be held at regular intervals in the roller circulation path, When the moving block is removed from the track rail, a plurality of rollers may be dropped from the retainer.

DESCRIPTION OF SYMBOLS 1 ... Track rail (track member), 1b ... Roller rolling surface, 2d ... Load roller rolling surface, 2 ... Moving block (moving member), 3 ... Roller, 3a ... Roller of each row, 3b ... Multiple of two rows The outermost end surface of the rollers of the two rollers, 3c... The opposite end surfaces of the two rows of rollers, 6-1... Outer direction change path (direction change path), 6-2. DESCRIPTION OF SYMBOLS ... Rolling roller rolling path, 8 ... No load return path, 10 ... Retainer (cage), 10a ... Spacer, 10b ... Belt, 31 ... End part abutting wall, 32 ... Center part abutting wall, 51 ... Screw shaft, 51a ... Roller rolling surface, 52 ... Nut, 52a ... Load roller rolling surface, 53 ... Circulating member, 54 ... Two rows of plural rollers

Claims (10)

A track member having a plurality of roller rolling surfaces extending in the longitudinal direction;
A plurality of loaded roller rolling surfaces facing the plurality of roller rolling surfaces, a plurality of unloaded return paths extending in parallel with the plurality of loaded roller rolling surfaces, and the plurality of loaded roller rolling A moving member having a plurality of direction change paths connecting the surface and the plurality of unloaded return paths;
A plurality of rollers arranged in a plurality of roller circulation paths composed of the plurality of load roller rolling surfaces, the plurality of no-load return paths and the plurality of direction change paths,
In at least one roller circulation path of the plurality of roller circulation paths, a plurality of rollers in two or more rows per line are arranged,
When the moving member is moved relative to the track member in the longitudinal direction of the track member, the plurality of rollers of the two or more rows move between the roller rolling surface of the track member and the load roller rolling of the moving member. A motion guidance device that rolls between the running surface.   2. The motion guide device according to claim 1, wherein when the diameter of the roller is D and the length is L, each of the plurality of rollers satisfies L / D ≦ 1.   At least one of the roller rolling surface of the track member and the load roller rolling surface of the moving member is a pair capable of contacting the outermost end surfaces of the plurality of rollers in two or more rows at both ends in the width direction. The motion guide device according to claim 1, wherein a metal end abutting wall is formed.   At least one of the roller rolling surface of the track member and the load roller rolling surface of the moving member is a metal center that can contact the opposing end surfaces of the two or more rows between the rows. The motion guide apparatus according to claim 1, wherein a part abutting wall is formed.   At least one of the roller rolling surface of the track member and the load roller rolling surface of the moving member is a pair capable of contacting the outermost end surfaces of the plurality of rollers in two or more rows at both ends in the width direction. Metal end abutting walls are formed, and between each row, a metal center abutting wall capable of contacting the opposing end surfaces of the two or more rollers is formed. The motion guide apparatus according to claim 1, wherein: The plurality of rollers of two or more rows are held at a certain interval in the row direction in a single resin cage,
The single retainer is interposed between a plurality of rollers in each row, and includes a plurality of spacers that prevent the rollers from contacting each other, and an outermost end of the plurality of rollers in the two or more rows. The motion guide apparatus according to claim 1, further comprising: a flexible belt that connects the plurality of spacers. The plurality of rollers of the two or more rows are held in a state in which a certain distance is provided in the row direction in a number of resin cages according to the number of rows,
Each retainer is interposed between a plurality of rollers in each row, and connects the plurality of spacers at the axial ends of the plurality of rollers in each row and prevents the rollers from contacting each other. The motion guide device according to claim 1, further comprising a flexible belt.   The motion guide device according to any one of claims 1 to 7, wherein a plurality of rollers in each row have the same pitch and phase between two or more rows. The pitch of the plurality of rollers in each row is the same between two or more rows,
The motion guide device according to any one of claims 1 to 7, wherein phases of a plurality of rollers in each row are shifted by 1 / n of the pitch between two or more rows. Where n is the number of columns. A screw shaft having a spiral roller rolling surface on the outer peripheral surface;
A nut having a spiral loaded roller rolling surface facing the roller rolling surface of the screw shaft on the inner peripheral surface;
A circulating member having a no-load return path that connects one end and the other end of the spiral rolling roller rolling surface;
A plurality of rollers arranged in a roller circulation path composed of the loaded roller rolling surface of the nut and the no-load return path;
In at least one roller circulation path of the plurality of roller circulation paths, a plurality of rollers in two or more rows per line are arranged,
When the nut is rotated relative to the screw shaft, the plurality of rollers in two or more rows roll between a roller rolling surface of the screw shaft and a load roller rolling surface of the nut. Roller screw.

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