Linear motion guide and method for manufacturing same

Abstract

In this linear motion guide, a raceway surface has: an end-side raceway surface intersecting a longitudinal-direction end surface of a slider body; and an inner raceway surface disposed on the opposite side of the end-side raceway surface to the longitudinal-direction end surface. The end-side raceway surface has a rotationally symmetrical shape with respect to an end-side raceway surface central axis that coincides or is parallel with a linear-portion center line of a rolling passage, and has: a partially conical raceway surface connected to the inner raceway surface; and a curved raceway surface connecting the partially conical raceway surface and the longitudinal-direction end surface. In a cross section including the end-side raceway surface central axis, the surface of the partially conical raceway surface has a linear shape and the surface of the curved raceway surface has an arc shape. In the cross-section, the tangent of the partially conical raceway surface and the tangent of the curved raceway surface are the same at the boundary between the partially conical raceway surface and the curved raceway surface.

Description

Linear guide device and manufacturing method thereof

[0001] The present invention relates to a linear guide device and a manufacturing method thereof.

[0002] Linear guide devices, which guide objects linearly while allowing rolling elements such as rollers and balls to circulate endlessly inside, are one of the important machine elements that have a significant impact on the motion accuracy of semiconductor manufacturing equipment, ultra-precision processing machines, ultra-precision measuring instruments, etc.

[0003] The linear motion guide device comprises a guide rail provided with rail-side rolling element raceway grooves, a slider body provided with slider-side rolling element raceway grooves facing the rail-side rolling element raceway grooves, and supported by the guide rail so as to be movable in the axial direction via the rolling of a plurality of rolling elements disposed in a rolling passage formed between the slider-side rolling element raceway grooves and the rail-side rolling element raceway grooves. The linear motion guide device further comprises a rolling element return passage provided in the slider body so as to be substantially parallel to the rolling passage, and direction change passages provided in end caps attached to both ends of the slider body in the moving direction, for communicating the rolling passage and the rolling element return passage.

[0004] When the rolling elements of a linear motion guiding device circulate endlessly through the rolling passage, direction change passage, and rolling element return passage, periodic micro-vibrations (hereinafter referred to as rolling element passing vibrations) occur, which greatly affect the motion accuracy of the aforementioned equipment. Rolling element passing vibrations occur when a rolling element, which is rolling in the rolling passage (loaded area) while being loaded by preload or external load, releases the load as it leaves the loaded area and enters the rolling element circulation path (unloaded area), or conversely, when it takes on a new load as it enters the loaded area from the unloaded area.

[0005] To suppress this rolling element passing vibration, inclined surfaces called crownings are provided at both ends of the slider-side rolling element raceway grooves that form the rolling passage. The crownings allow the load fluctuations that accompany the rolling elements entering and leaving the load zone to occur gradually, thereby reducing the rolling element passing vibration.

[0006] Patent Document 1 discloses a linear guide bearing comprising: a first crowning having a curved surface shape, inclined portions provided at both ends of the slider-side rolling element raceway groove, formed with a large radius of curvature so that the slope continues from the slider-side rolling element raceway groove and becomes gentler; a second crowning adjacent to the first crowning, extending toward the inner peripheral surface of the direction change path, having a steeper slope than the first crowning and a shorter axial length than the first crowning; and an inclined surface provided between the second crowning and the end face of the slider body, which is more inclined than the first crowning and second crowning.

[0007] Japanese Patent Application Publication No. 2008-133837

[0008] However, when a ball enters a rolling path, the center of the ball may be misaligned with the center line of the return path, which can cause a problem of so-called ball eccentricity. According to the technology of Patent Document 1, by combining a first crowning and a second crowning, a sufficient drop can be formed in the groove bottom direction (slider width direction) where the crowning is formed to relieve the eccentricity of the ball. However, since no relief can be provided at the slider groove end for ball eccentricity in directions other than the groove bottom direction, particularly in directions perpendicular to the groove bottom (up and down direction of the slider), there is a risk that the ball will collide strongly with the end face of the slider, which may deteriorate durability.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a linear guide device and a manufacturing method thereof that can ensure smooth ball movement while mitigating impact forces regardless of the behavior of the ball entering the track surface.

[0010] a slider body having a raceway surface disposed opposite to a raceway groove of the guide rail to form a rolling path for the rolling elements, and a return path for the rolling elements; and an end cap having a direction change path connecting the return path and the rolling path; and the raceway surface has an end-side raceway surface intersecting a longitudinal end face of the slider body, and an inner-side raceway surface disposed on the opposite side of the longitudinal end face with the end-side raceway surface in between, and the end-side raceway surface has a shape that is rotationally symmetrical with respect to a central axis of the end-side raceway surface that coincides with or is parallel to a center line of a straight portion of the rolling path, and has a partial conical raceway surface connected to the inner-side raceway surface, and a curved raceway surface connecting the partial conical raceway surface and the longitudinal end face, In a cross section including the center axis of the end-side raceway surface, the surface of the partial conical raceway surface is linear, and the surface of the curved raceway surface is arcuate, and in the cross section, a tangent to the partial conical raceway surface and a tangent to the curved raceway surface at a boundary between the partial conical raceway surface and the curved raceway surface are common.

[0011] a slider body having a raceway surface disposed opposite to a raceway groove of the guide rail to form a rolling path for the rolling elements, and a return path for the rolling elements; and an end cap having a direction change path connecting the return path and the rolling path; and the raceway surface has an end-side raceway surface intersecting a longitudinal end face of the slider body, and an inner-side raceway surface disposed on the opposite side of the longitudinal end face with the end-side raceway surface intervening therebetween, the end-side raceway surface having a shape rotationally symmetrical with respect to a central axis of the end-side raceway surface that coincides with or is parallel to a center line of a straight portion of the rolling path, and the end-side raceway surface has a partial conical raceway surface connected to the inner-side raceway surface, and a curved raceway surface connecting the partial conical raceway surface and the longitudinal end face, When the width direction of the slider body is defined as the X direction, the longitudinal direction of the slider body is defined as the Y direction, and the direction perpendicular to the X and Y directions is defined as the Z direction, the inner side raceway surface is formed by rotating a first tool around a rotation axis parallel to the Z direction and moving it in parallel to the Y direction relative to the slider body, and the end side raceway surface is formed by rotating a second tool around a rotation axis parallel to a center line of the straight portion of the rolling path and moving it in parallel to the X direction relative to the slider body, and in a cross section including the center axis of the end side raceway surface, the surface of the partial conical raceway surface is formed linearly, and the surface of the curved raceway surface is formed arcuately, and in the cross section, a tangent to the partial conical raceway surface and a tangent to the curved raceway surface at a boundary between the partial conical raceway surface and the curved raceway surface are common.

[0012] According to the present invention, it is possible to provide a linear guide device and a manufacturing method thereof that can ensure smooth ball movement while mitigating impact forces regardless of the behavior of the ball entering the raceway surface.

[0013] FIG. 1 is a perspective view showing a linear guide device according to a first embodiment of the present invention. FIG. 2 is a front view of the slider body of the linear guide device of FIG. 1, viewed from the longitudinal direction of the guide rail. FIG. 3 is a cross-sectional view taken along III-III in FIG. 2. FIG. 4 is a perspective view showing an end of the slider body. FIG. 5 is a cross-sectional view taken along V-V in FIG. 4, showing an enlarged view of a portion of the slider body. FIG. 6 is a view of the slider body of FIG. 5, viewed in the direction of arrow VI. FIG. 7 is a cross-sectional view taken along VII-VII in FIG. 6. FIG. 8 is a side view taken along VIII-VIII in FIG. 6. FIG. 9 is a schematic diagram showing a side surface similar to FIG. 8 according to a comparative example, together with rolling elements. FIG. 10 is a schematic diagram showing a side surface similar to FIG. 8 according to this embodiment, together with rolling elements. FIG. 11 is a schematic diagram showing a side surface similar to FIG. 8 according to this embodiment, together with rolling elements. FIG. 12 is a schematic diagram showing a part of a blank for the slider body, viewed from a direction perpendicular to the longitudinal direction, and a cutting tool. FIG. 13 is a schematic diagram showing a blank of a slider body and a grinding tool as viewed from the longitudinal direction. FIG. 14 is an enlarged schematic diagram showing a cross section similar to FIG. 7 together with rolling elements. FIG. 15 is a diagram showing the results of a numerical calculation (calculation based on elastic contact theory) of the contact pressure due to a collision when the inclination angle of the third upper raceway surface is changed. FIG. 16 is an enlarged schematic diagram showing a cross section similar to FIG. 7 together with rolling elements. FIG. 17 is a diagram showing the results of a numerical calculation (calculation based on elastic contact theory) of the contact pressure due to a collision when the radius of curvature of the cross section of the fourth upper raceway surface is changed. FIG. 18 is a cross-sectional view similar to FIG. 7 showing an enlarged end of Example 1 corresponding to this embodiment. FIG. 19 is a cross-sectional view similar to FIG. 7 showing an enlarged end of Comparative Example 1. FIG. 20 is a cross-sectional view similar to FIG. 7 showing an enlarged end of Comparative Example 2. FIG. 21 is a cross-sectional view similar to FIG. 7 showing an enlarged end of Comparative Example 3. FIG. 22 is a side view similar to FIG. 8 of a slider body according to the second embodiment.

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification, terms indicating directions (upward, downward, etc.) refer to the respective directions in Figure 2 unless otherwise specified. Furthermore, the term "longitudinal direction" refers to the longitudinal direction of the guide rail or slider.

[0015] First Embodiment FIG. 1 is a perspective view showing a linear guide device according to a first embodiment of the present invention. FIG. 2 is a front view of the slider body of the linear guide device of FIG. 1 as viewed from the longitudinal direction of the guide rail, with the end caps omitted. FIG. 3 is a cross-sectional view taken along III-III in FIG. 2, with the cage 4 and cage groove 10Ba omitted. In FIG. 2, a plane passing through the widthwise center of the slider body 2A and the longitudinal axis of the guide rail 1 is defined as a vertical center plane CP, and a plane perpendicular to the vertical center plane CP and passing through the center lines O1 of the linear portions of a pair of rolling paths 13A arranged on both sides of the guide rail 1 is defined as a horizontal reference plane HP. Furthermore, a plane passing through the center lines O1 of the linear portions of the rolling paths 13A and perpendicular to the horizontal reference plane HP is defined as a vertical reference plane VP. Details will be described later, but the configuration of each part will be explained using the vertical reference plane VP and horizontal reference plane HP corresponding to one of the rolling paths 13A.

[0016] A slider 2 having a substantially U-shaped cross section is mounted along a linearly extending guide rail 1 having a substantially rectangular cross section so as to be movable in the longitudinal direction of the guide rail 1. At the ridge where both left and right side surfaces 1a, 1a in the width direction of the guide rail 1 intersect with the top surface 1b, track grooves 10A, 10A consisting of recessed grooves having a cross section shaped like a quarter of a circle are formed along the longitudinal direction.

[0017] Furthermore, raceway grooves 10B, 10B each consisting of a recessed groove having a substantially semicircular cross section are formed along the longitudinal direction at approximately the center in the vertical direction of both left and right widthwise side surfaces 1a, 1a of the guide rail 1. Furthermore, at the groove bottoms of the raceway grooves 10B, 10B, a cage groove 10Ba (wire groove) that accommodates a part of the cage 4 and guides the cage 4 during movement of the slider 2 is formed along the longitudinal direction between both ends of the movement area of ​​the slider 2 (for example, between both ends in the longitudinal direction of the guide rail 1). The cross section of the cage groove 10Ba is, for example, substantially rectangular.

[0018] The slider 2 is made up of a flat body 7 facing the upper surface 1b of the guide rail 1 and two legs 6, 6 extending downward from both the left and right sides of the body 7 and facing the side surface 1a, and the angle between the body 7 and the legs 6, 6 is approximately right angles, so that the cross section of the slider 2 is approximately U-shaped. Furthermore, the slider 2 is attached movably relative to the guide rail 1, with the guide rail 1 sandwiched between the legs 6, 6.

[0019] The slider 2 comprises a slider body 2A and end caps 2B, 2B detachably attached to both ends (longitudinal ends) of the slider body 2A. Furthermore, side seals 5, 5 are attached to both ends of the slider 2 (longitudinal outer end surfaces of each end cap 2B) and slide against the outer surfaces (upper surface 1b and side surfaces 1a, 1a) of the guide rail 1 to seal the portions of the opening of the gap between the guide rail 1 and the slider 2 that face the longitudinal end surfaces, and under seals 8, 8 are attached to the bottom of the slider 2 to seal the portions of the opening of the gap between the guide rail 1 and the slider 2 that face the underside of the slider 2. These side seals 5, 5 and under seals 8, 8 prevent foreign matter from entering the gap from the outside and lubricant from leaking from the gap to the outside.

[0020] Furthermore, raceway grooves 11A, 11A, 11B, 11B (hereinafter, these may be collectively referred to as 11) consisting of recessed grooves with a substantially semicircular cross section that face raceway grooves 10A, 10A, 10B, 10B (hereinafter, these may be collectively referred to as 10) of the guide rail 1 are formed at the corners and approximately the center in the vertical direction of the inner surfaces of both the left and right legs 6, 6 of the slider body 2A. Furthermore, rolling paths 13A, 13A, 13B, 13B (hereinafter, these may be collectively referred to as 13) with a substantially circular cross section are formed between the raceway groove 10 of the guide rail 1 and the raceway groove 11 of the slider 2, and these rolling paths extend in the longitudinal direction.

[0021] A plurality of rolling elements 3 (balls) are loaded in the rolling passage 13 so as to be able to roll freely while being held by a cage 4, and the slider 2 is guided by the guide rail 1 and is able to move in the longitudinal direction via the rolling of the rolling elements 3 in the rolling passage 13. The cage 4 is formed of, for example, a wire, and holds the rolling elements 3 to prevent them from falling off the slider 2 before it is assembled to the guide rail 1.

[0022] The number of raceway grooves 10, 11 provided on the guide rail 1 and the slider 2 is not limited to two rows on one side, but may be one row on one side as in a second embodiment described later, or three or more rows. The cross-sectional shape of the raceway grooves 10, 11 may be an arc shape consisting of a single arc as described above, but may also be a substantially V-shape (Gothic arc-shaped groove) formed by combining two arcs with different centers of curvature.

[0023] Furthermore, the slider 2 is provided with return passages 14A, 14A, 14B, 14B (hereinafter, the reference numeral 14 may be used to refer to these collectively) which are through-holes with a substantially circular cross section that run parallel to the rolling passage 13 and penetrate the slider 2 in the longitudinal direction at the upper and lower parts of the thick portions of the left and right legs 6, 6 of the slider body 2A (see Figures 2 and 3).

[0024] The end cap 2B is made of, for example, a molded product of a resin material and has a generally U-shaped cross section similar to the slider body 2A. Furthermore, on both the left and right sides of the back surface of the end cap 2B (the surface that abuts against the slider body 2A), two arc-shaped, circular cross-sectional direction change paths 15 are formed (upper and lower) (see FIG. 3). When the end cap 2B is attached to the slider body 2A with fastening members such as screws, the direction change paths 15 connect the rolling path 13 and the return path 14. The cross-sectional shape of the direction change paths 15 is shown schematically in FIG. 3.

[0025] The return path 14 and the direction change paths 15 at both ends constitute a rolling element transport path 16 that transports and circulates the rolling elements 3 from the end point of the rolling path 13 to the start point, and the rolling path 13 and the rolling element transport path 16 constitute a substantially circular circulation path (see Figure 3). This substantially circular circulation path is formed on both the left and right sides of the guide rail 1.

[0026] When the slider 2 moves longitudinally along the guide rail 1, the rolling elements 3 loaded in the rolling path 13 move in the same direction as the slider 2 relative to the guide rail 1 while rolling within the rolling path 13. When the rolling elements 3 reach the end point of the rolling path 13, they are scooped up from the rolling path 13 and sent to the direction change path 15. Having entered the direction change path 15, the rolling elements 3 change direction and are introduced into the return path 14, and pass through the return path 14 to reach the opposite direction change path 15, where they change direction again and return to the start point of the rolling path 13. The rolling elements 3 repeat this circulation within the circulation path indefinitely, allowing the slider 2 to move smoothly along the guide rail 1.

[0027] Fig. 4 is a perspective view showing the end of the slider body 2A. Fig. 5 is an enlarged cross-sectional view taken along line V-V in Fig. 4. Fig. 6 is a view of the slider body 2A in Fig. 5 as seen in the direction of arrow VI. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6. Fig. 8 is a side view taken along line VIII-VIII in Fig. 6.

[0028] The shape of the end of the raceway groove 11A will be described with reference to the drawings. Hereinafter, the raceway groove 11A will be described as an upper raceway groove, and the raceway groove 11B will be described as a lower raceway groove. Furthermore, the term "first raceway surface" refers to at least one of the first upper raceway surface and the first lower raceway surface, and the term "second raceway surface" refers to at least one of the second upper raceway surface and the second lower raceway surface.

[0029] 5, the upper raceway groove 11A has, from the center of the slider body 2A, a first upper raceway surface 11Aa, a second upper raceway surface 11Ab, a third upper raceway surface 11Ac, and a fourth upper raceway surface 11Ad that intersects with the end face (longitudinal end) 2Aa of the slider body 2A. These four raceway surfaces are each formed over the entire width direction (approximately half the circumference) of the upper raceway groove 11A. Here, the first upper raceway surface 11Aa and the second upper raceway surface 11Ab are referred to as inner raceway surfaces, and the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad are referred to as end raceway surfaces. The third upper raceway surface 11Ac is sometimes referred to as a partial conical raceway surface, and the fourth upper raceway surface 11Ad is sometimes referred to as a curved raceway surface.

[0030] In the upper raceway groove 11A, the vertical centerline C1 (an imaginary line) at the groove bottom is the boundary. The part above the vertical centerline C1 is called the upper flank, and the part below the vertical centerline C1 is called the lower flank. The upper and lower flanks are symmetrical with respect to the vertical centerline C1. The vertical centerline C1 and the centerline O1 of the straight portion of the rolling path 13A are within the horizontal reference plane HP (FIG. 2).

[0031] 5 , the dashed lines extending in the circumferential direction schematically indicate the boundary between the first upper raceway surface 11Aa and the second upper raceway surface 11Ab, and the boundary between the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad. The first upper raceway surface 11Aa and the second upper raceway surface 11Ab, and the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad are connected by sharing a tangent line in the longitudinal cross section, so that in reality, no ridge lines are visible. However, these are shown here as dashed lines to facilitate understanding of the configuration.

[0032] The first upper raceway surface 11Aa has a uniform cross section perpendicular to the longitudinal direction. The center line of the cylindrical space formed by the first upper raceway surface 11Aa and the raceway groove 10A of the guide rail 1 is set as the center line O1 of the straight portion of the rolling path 13A. In contrast, the second upper raceway surface 11Ab, the third upper raceway surface 11Ac, and the fourth upper raceway surface 11Ad are formed so that their cross sections perpendicular to the longitudinal direction are partially different.

[0033] In the cross section (within the horizontal reference plane HP) of Fig. 7, the second upper raceway surface 11Ab has a crowning shape with a drop amount d2 that separates from the straight-line portion center line O1 toward the end face 2Aa, but in a side view as shown in Fig. 8, it does not have a crowning shape (it is equidistant from the straight-line portion center line O1). The drop amount is defined as the maximum distance between each raceway surface and the first upper raceway surface 11Aa in a cross section passing through the straight-line portion center line O1 (a cross section passing through the upper raceway groove 11A).

[0034] In the cross section (within the horizontal reference plane HP) of Fig. 7, the third upper raceway surface 11Ac has a crowning shape with a drop amount d3 that moves away from the end-side raceway surface central axis that coincides with or is parallel to the straight-line portion center line O1 as it approaches the end face 2Aa, and in the side view of Fig. 8, it has a crowning shape with a drop amount d3' that moves away from the end-side raceway surface central axis that coincides with or is parallel to the straight-line portion center line O1 as it approaches the end face 2Aa. In the cross section passing through the end-side raceway surface central axis, the surface of the third upper raceway surface 11Ac is linear, and its inclination angle (the angle of inclination relative to the end-side raceway surface central axis) is θ.

[0035] In the cross section (within the horizontal reference plane HP) of Fig. 7, the fourth upper raceway surface 11Ad has a crowning shape with a drop amount d4 that moves away from the center axis of the end-side raceway surface toward the end face 2Aa, and in the side view of Fig. 8, it has a crowning shape with a drop amount d4' that moves away from the center axis of the end-side raceway surface toward the end face 2Aa. In the cross section passing through the center axis of the end-side raceway surface, it is preferable that the surface of the fourth upper raceway surface 11Ad has an outwardly convex arc shape. Here, d2<d3<d4 and d3'<d4'.

[0036] 7 and 8, the second upper raceway surface 11Ab starts at a position distance L1 from the end face 2Aa of the slider body 2A and terminates at a position distance L2 from the end face 2Aa. The third upper raceway surface 11Ac starts at a position distance L2 from the end face 2Aa of the slider body 2A and terminates at a position distance L3 from the end face 2Aa. The fourth upper raceway surface 11Ad starts at a position distance L3 from the end face 2Aa of the slider body 2A and terminates at the end face 2Aa. Here, it is preferable that L1 > L2 > L3 hold.

[0037] In this embodiment, the surfaces of the third and fourth upper raceway surfaces 11Ac and 11Ad have rotationally symmetric shapes with a central axis that coincides with or is parallel to the straight portion center line O1. Here, the central axis that coincides with or is parallel to the straight portion center line O1 is referred to as the end-side raceway surface central axis. The end-side raceway surface central axis is preferably located within the horizontal reference plane HP. Therefore, the drop amount d3 is approximately equal to the drop amount d3', and the drop amount d4 is approximately equal to the drop amount d4'.

[0038] 5 is parallel to the upper raceway groove 11A and has a similar shape to the upper raceway groove 11A, so its description will be omitted. Furthermore, the shapes of the other ends of the upper raceway groove 11A and the lower raceway groove 11B are also similar to those described above, so their description will be omitted.

[0039] (Action and effect of this embodiment) Fig. 9 is a schematic diagram showing a side surface similar to Fig. 8 according to a comparative example, together with the rolling elements. Fig. 10 is a schematic diagram showing a side surface similar to Fig. 8 according to this embodiment, together with the rolling elements, but the amount of drop of the second upper raceway surface 11Ab is small, so it is not shown here. Fig. 11 is a schematic diagram showing a side surface similar to Fig. 8 according to this embodiment, together with the rolling elements. Here, the rolling passage 13A will be described as an example, but the same applies to the rolling passage 13B.

[0040] For example, due to the influence of centrifugal force or vibration when passing through the direction change path 15 (see FIG. 3 ) in the end cap 2B, the center of the rolling element 3 may be misaligned with the center line O1 of the straight portion of the rolling path 13A when it enters the rolling path 13A from the direction change path 15. In this case, the amount of misalignment between the center of the rolling element 3 and the center line O1 of the straight portion of the rolling path 13A is defined as the eccentricity e. Because the diameter Da of the rolling element 3 is slightly smaller than the diameter of the rolling path 13A, if the eccentricity e is smaller than half the diameter difference, the rolling element 3 can smoothly enter the rolling path 13A. However, if the eccentricity e exceeds half the diameter difference in the vertical direction, the rolling element 3 may collide with the edge of the rolling path 13A in the entry direction, as shown in FIG. 9 , which may result in noise generation or damage to the rolling element 3.

[0041] In contrast, according to this embodiment, a fourth upper raceway surface 11Ad having a drop amount d4 on the side surface shown in Figure 10 is formed at the approach end of the rolling passage 13A. Therefore, even in a state where the rolling element 3 is eccentric with an eccentricity amount e exceeding half of the diameter difference, the rolling element 3 entering from the direction change path 15 obliquely contacts the outwardly convex arc-shaped fourth upper raceway surface 11Ad, rolls, and then rolls on the partially conical third upper raceway surface 11Ac and second upper raceway surface 11Ab, gradually changing its direction of movement and being guided to the first upper raceway surface 11Aa. This suppresses the generation of large contact pressure, thereby suppressing noise generation and damage to the rolling element 3 and ensuring smooth movement of the rolling element 3.

[0042] 11, when an eccentric rolling element 3 with an eccentricity e exceeding half the diameter difference approaches, the rolling element 3 approaching from the direction change path 15 obliquely contacts the fourth upper raceway surface 11Ad, which has a drop d4' and an outwardly convex arc shape, and then rolls, and by further rolling on the partially conical third upper raceway surface 11Ac and second upper raceway surface 11Ab, the direction of movement is gradually changed and the rolling element 3 is guided to the first upper raceway surface 11Aa. This reduces the impact force on the slider body 2A, making it possible to suppress noise generation and damage to the rolling element 3.

[0043] The lower raceway groove 11B has the same configuration as the upper raceway groove 11A, and therefore exerts the same effects.

[0044] (Method for machining the first upper raceway surface and the second upper raceway surface) Next, a method for machining the upper raceway groove 11A will be described. Fig. 12 is a schematic diagram showing a part of the blank of the slider body 2A as viewed from a direction perpendicular to the longitudinal direction and a cutting tool TL1. Fig. 13 is a schematic diagram showing the blank of the slider body 2A as viewed from the longitudinal direction and a grinding tool TL2.

[0045] 12 and 13, the longitudinal direction of the slider body 2A is the Y direction, the width direction of the slider body 2A is the X direction, and the up-down direction is the Z direction. The Y direction is parallel to the center line O1 of the straight portion.

[0046] 12 is an end mill or the like, and has a tapered cutting blade TL1a on its outer periphery. When the cutting tool TL1 is rotated about its center line RO1, the rotation trajectory of the cutting blade TL1a coincides with the final surface shapes of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad.

[0047] When cutting the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad, a groove similar to the first upper raceway surface 11Aa is first formed in a blank for the slider body 2A by cutting or the like. Then, the center line RO1 of the cutting tool TL1 is held parallel to the center line O1 of the straight portion and positioned in the Y direction relative to the blank for the slider body 2A. Then, while rotating the cutting tool TL1 around the center line RO1, the cutting tool TL1 is translated in the X direction to a predetermined position (where the center line RO1 coincides with the rotation center axis of the rotationally symmetric shape that forms the final surface shape of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad, i.e., the position of the center axis of the end-side raceway surface). This allows the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad to be machined simultaneously in a short time using the forming cutting tool TL1.

[0048] If the inclination angle θ of the third upper raceway surface 11Ac relative to the center axis of the end-side raceway surface is too large, too much material is removed from the blank at one time, increasing resistance during processing and making processing difficult. Therefore, for processing convenience, the inclination angle θ is preferably greater than 0° and not greater than 45°. From the perspective of the effect of the upper raceway groove 11A, the appropriate range of the inclination angle θ will be described later.

[0049] The rotational trajectory of the machining blade TL1a smoothly connects the portion corresponding to the third upper track surface 11Ac and the portion corresponding to the fourth upper track surface 11Ad, so that in a longitudinal cross section of the slider body 2A (a cross section passing through the center axis of the end side track surface), the tangent to the third upper track surface 11Ac at the boundary between the third upper track surface 11Ac and the fourth upper track surface 11Ad and the tangent to the fourth upper track surface 11Ad overlap each other.

[0050] 13 includes an annular grinding wheel TL2a and a cylindrical portion TL2b that holds the grinding wheel TL2a. When the grinding tool TL2 is cut along a plane passing through the center line RO2 of the grinding tool TL2, the grinding wheel TL2a has the same semicircular outer circumferential surface as the upper raceway groove 11A.

[0051] When grinding the first upper raceway surface 11Aa and the second upper raceway surface 11Ab, the grinding tool TL2 rotating about the center line RO2 is brought into contact with the inside of the leg portion 6 while aligning the center line RO2 of the grinding tool TL2 in the Z direction, and grinding of the inner surface of the first upper raceway surface 11Aa is started with the outer peripheral surface of the grindstone TL2a, after which the grinding tool TL2 is moved in the Y direction toward the end face 2Aa. As a result, the first upper raceway surface 11Aa is formed linearly along the Y direction.

[0052] The crowning formed on the second upper raceway surface 11Ab can be achieved by controlling the cutting depth of the grinding tool TL2. In other words, the crowning is formed so that the drop amount changes when viewed in the cross section of Fig. 7 but does not appear when viewed from the side of Fig. 8.

[0053] Specifically, after forming the first upper raceway surface 11Aa, the grinding tool TL2 is rotated and translated in the Y direction while keeping the center line RO2 aligned in the Z direction. At the same time, as it approaches the end face 2Aa of the slider body 2A, it is translated outward in the X direction. This forms the second upper raceway surface 11Ab, which has a crowning shape in the cross section of FIG. 7 , i.e., in the slider width direction, but does not have a crowning shape in the side view of FIG. 8 , i.e., in the slider vertical direction. Note that, for example, to simplify the processing process, the second upper raceway surface 11Ab may not be crowned. In this case, the grinding tool TL2 is not moved in the X direction. In this case, the only inner raceway surface is the first upper raceway surface 11Aa, and it can also be said that the third upper raceway surface 11Ac and the first upper raceway surface 11Aa are in direct contact with each other. Therefore, when the second upper raceway surface 11Ab does not exist and the third upper raceway surface 11Ac and the first upper raceway surface 11Aa are in direct contact with each other, the second upper raceway surface 11Ab will hereinafter be referred to as the first upper raceway surface 11Aa.

[0054] According to this embodiment, the boundary between the second upper raceway surface 11Ab and the third upper raceway surface 11Ac does not substantially share a tangent. In other words, in at least one cross section passing through the straight portion center line O1, the tangent to the second upper raceway surface 11Ab and the tangent to the third upper raceway surface 11Ac at the boundary between the second upper raceway surface 11Ab and the third upper raceway surface 11Ac are different. That is, a ridgeline (edge) is permitted to be formed at the boundary between the second upper raceway surface 11Ab and the third upper raceway surface 11Ac. Therefore, the first upper raceway surface 11Aa or the second upper raceway surface 11Ab can be formed in a separate process from the process for forming the third upper raceway surface 11Ac (and the fourth upper raceway surface 11Ad). The order of machining the cutting tool TL1 and the grinding tool TL2 is not limited, and either can be performed first.

[0055] As described above, according to this embodiment, in the longitudinal cross section of the slider body 2A (the cross section passing through the center line O1 of the straight portion), the boundary between the second upper raceway surface 11Ab and the third upper raceway surface 11Ac does not need to substantially share a tangent line, so after machining the third upper raceway surface 11Ac, there is no need to finish-machine the connecting portion with the second upper raceway surface 11Ab, which makes it easier to manufacture the slider body 2A.

[0056] The second upper orbital surface 11Ab and the third upper orbital surface 11Ac "do not substantially share a tangent" means that the boundary between the second upper orbital surface 11Ab and the third upper orbital surface 11Ac is on a ridgeline, but they do not share a tangent over most of that ridgeline. In other words, when the first upper orbital surface 11Aa or the second upper orbital surface 11Ab is formed after the third upper orbital surface 11Ac is formed, there may be a portion where they share a tangent, but this case is also included in the configuration where they "do not substantially share a tangent."

[0057] (Regarding the inclination angle θ) Figure 14 is an enlarged schematic diagram showing a cross section similar to that of Figure 7 together with the rolling elements, illustrating an example in which the eccentricity of the rolling elements is relatively small. When the eccentricity e is relatively small when the rolling elements 3 enter the raceway surface, the rolling elements 3 first collide with the third upper raceway surface 11Ac at point P1. This collision causes a collision force F1 to act between the rolling elements 3 and the third upper raceway surface 11Ac at point P1, and at the same time, a contact pressure is generated at point P1. The greater the contact pressure, the greater the risk of damage to the collision area.

[0058] 15 shows the results of a numerical calculation (calculation based on elastic contact theory) of the contact pressure due to a collision when the inclination angle θ of the third upper raceway surface 11Ac is changed. In this calculation, the ball diameter was 4.7625 mm, the ball and slider were made of steel, and the ball velocity V (component parallel to the linear motion direction) at the time of collision was 1 m / s.

[0059] The horizontal axis of Fig. 15 represents the inclination angle θ (deg), and the vertical axis of Fig. 15 represents the ratio of contact pressure at each inclination angle, with the contact pressure at an inclination angle θ of 30° being used as the reference (ratio = 1). The results of Fig. 15 show that when the inclination angle θ is set to 10° or less, the effect of reducing contact pressure becomes significant. In other words, it is preferable that the inclination angle θ of the third upper raceway surface 11Ac be 10° or less.

[0060] (Regarding the radius of curvature r) Figure 16 is an enlarged schematic diagram showing a cross section similar to that of Figure 7 together with the rolling elements, illustrating an example in which the eccentricity of the rolling elements is relatively large. When the rolling elements 3 enter the raceway surface, if the eccentricity e is relatively large, the rolling elements 3 collide with the fourth upper raceway surface 11Ad at point P2. This collision causes a collision force F2 to act between the rolling elements 3 and the fourth upper raceway surface 11Ad at point P2, and at the same time, contact pressure is generated at point P2. The radius of curvature of the cross section of the fourth upper raceway surface 11Ad in Figure 16 is defined as r, and the diameter of the rolling elements 3 is defined as Da.

[0061] 17 shows the results of a numerical calculation (calculation based on elastic contact theory) of the contact pressure due to a collision when the radius of curvature r of the cross section of the fourth upper raceway surface 11Ad is changed. The calculation conditions are the same as those in FIG. 15.

[0062] The horizontal axis of Fig. 17 represents the ratio (r / Da) of the radius of curvature r to the rolling element diameter Da, and the vertical axis of Fig. 17 represents the ratio of contact pressure at each arc radius, with the contact pressure at r / Da = 0.06 (r = 0.3 mm) as the reference (ratio = 1). The results of Fig. 17 show that when the ratio of the radius of curvature r to the rolling element diameter Da is 0.2 or more, the effect of reducing contact pressure becomes significant. In other words, the cross-sectional radius of curvature r of the fourth upper raceway surface 11Ad is preferably 0.2 or more times the rolling element diameter Da.

[0063] (Regarding the amount of fall) FIG. 18 is a cross-sectional view similar to FIG. 7 showing an enlarged view of the end of Example 1, which corresponds to this embodiment; FIG. 19 is a cross-sectional view similar to FIG. 7 showing an enlarged view of the end of Comparative Example 1; FIG. 20 is a cross-sectional view similar to FIG. 7 showing an enlarged view of the end of Comparative Example 2; and FIG. 21 is a cross-sectional view similar to FIG. 7 showing an enlarged view of the end of Comparative Example 3.

[0064] (Example 1) In this embodiment, as shown in FIG. 18 , there is provided a third upper raceway surface 11Ac having a linear cross section and a fourth upper raceway surface 11Ad having an arc-shaped cross section, and the fourth upper raceway surface 11Ad has a crowning shape with a drop amount d4.

[0065] Here, if eccentricity occurs when the rolling element enters, a sufficiently large drop d4 is required to smoothly guide the rolling element. At the same time, to avoid damage to the third upper raceway surface 11Ac, as described above, the inclination angle θ of the third upper raceway surface 11Ac must be small. Here, as an example, the inclination angle θ is set to 10°, the drop d4 is set to 0.4 mm, and the longitudinal length L2 of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad is set to 1.5 mm.

[0066] 19, only the third upper raceway surface 11Ac is provided as the end-side raceway surface, and the fourth upper raceway surface 11Ad is not provided. Therefore, the third upper raceway surface 11Ac intersects with the end face 2Aa.

[0067] According to Comparative Example 1, when an attempt is made to reduce the inclination angle θ of the third upper raceway surface 11Ac while ensuring a sufficient drop amount d4, the longitudinal length L2 of the third upper raceway surface 11Ac becomes longer. Specifically, when an attempt is made to ensure the inclination angle θ of the third upper raceway surface 11Ac = 10° and the drop amount d4 = 0.4 mm, as in Example 1, the longitudinal length L2 of the third upper raceway surface 11Ac becomes 2.4 mm, which is longer than that of Example 1.

[0068] When the linear guide device is in use, the slider 2 receives a load, which is supported by the guide rail 1 via the rolling elements 3. At this time, of the slider raceway surfaces, only the inner raceway surface can receive the load. In other words, if the end-side raceway surface is longer, the length of the inner raceway surface that receives the load becomes shorter, which may shorten the life of the linear guide device.

[0069] 20 has a similar configuration to that of Comparative Example 1, but the longitudinal length L2 of the third upper raceway surface 11Ac is set to 1.5 mm, the same as that of Example 1. With this configuration, the length of the inner raceway surface that receives the load can be ensured to be approximately the same as that of Example 1.

[0070] However, when the inclination angle θ of the third upper raceway surface 11Ac is set to 10° as in Example 1, the drop amount d4 in Comparative Example 2 is 0.25 mm, which is smaller than the drop amount d4 of 0.4 mm in Example 1. In other words, the allowable eccentricity amount e of the rolling elements is reduced, making it difficult to ensure smooth entry of the rolling elements.

[0071] In contrast, in Example 1 corresponding to this embodiment, the end-side raceway surface is composed of the third upper raceway surface 11Ac having a linear cross section and the fourth upper raceway surface 11Ad having an arc-shaped cross section, so that the inclination angle θ is kept small, durability against collision with rolling elements is maintained, and a sufficient drop amount is ensured to maintain smooth operation of the slider.

[0072] (Comparative Example 3) On the other hand, in Comparative Example 3 shown in FIG. 21 , similar to Example 1, the end-side raceway surface is configured by the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad, but both the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad have linear cross sections.

[0073] In Comparative Example 3, similarly to Example 1, the inclination angle θ of the third upper raceway surface 11Ac is 10°, the drop amount d4 of the fourth upper raceway surface 11Ad is 0.4 mm, and the longitudinal length L2 of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad is 1.5 mm.

[0074] In Comparative Example 3, because the cross sections of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad are linear, a ridgeline extending in the circumferential direction inevitably occurs at the boundary between them (point P3). That is, the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad do not share a tangent. Because the boundary between the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad forms an edge, when the rolling element 3 collides with the edge, an extremely large contact pressure is generated (corresponding to the case where r / Da is very small in FIG. 17 ). This raises concerns about durability during high-speed operation.

[0075] In contrast, in Example 1 corresponding to this embodiment, in a cross section including the center axis of the end-side raceway surface, the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad of the end-side raceway surfaces are smoothly connected so as to share a tangent to each other, which prevents the formation of a ridge (edge) at the boundary between the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad, prevents excessive contact pressure from occurring even when the rolling element 3 collides with the boundary, and eliminates concerns about reduced durability.

[0076] Second Embodiment Figure 22 is a side view similar to Figure 8 of a slider body 2A according to a second embodiment. The shape of the upper raceway groove 11A in this embodiment is the same as in the first embodiment, but the surface roughness of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad is coarser than that of the first upper raceway surface 11Aa. The surface roughness of the second upper raceway surface 11Ab is substantially equal to that of the first upper raceway surface 11Aa. The surface roughness can be evaluated by the arithmetic mean roughness Ra, etc. For example, the arithmetic mean roughness Ra of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad is preferably 50% or more coarser than that of the first upper raceway surface 11Aa. The same is true for the lower raceway groove 11B. Other configurations are the same as in the first embodiment, so repeated explanations will be omitted.

[0077] When a rolling element enters a raceway surface, it first collides with the third upper raceway surface 11Ac or the fourth upper raceway surface 11Ad. If the third upper raceway surface 11Ac or the fourth upper raceway surface 11Ad can absorb the collision of the rolling element and sufficiently damp it, it is possible to mitigate subsequent collisions due to bounding, and improve the durability of the linear motion guiding device. To provide such damping, it is effective to increase the roughness of the third upper raceway surface 11Ac or the fourth upper raceway surface 11Ad so that it is easier to retain a lubricant such as grease.

[0078] In this embodiment, concentric irregularities are provided on the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad to increase the roughness. Such roughness can be achieved by providing irregularities on the machining blade TL1a of the cutting tool TL1 that processes the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad. For example, the dimensions of these irregularities are a peak-to-valley height of approximately 5 to 10 μm, and a distance between adjacent peaks of approximately 0.2 mm. It should be noted that spiral irregularities may also be formed by moving the cutting tool TL1 in the Y direction in synchronization with its rotation.

[0079] The present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0080] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0081] This application is based on a Japanese patent application (Patent Application No. 2024-007502) filed on January 22, 2024, the contents of which are incorporated herein by reference.

[0082] REFERENCE SIGNS LIST 1 guide rail 2 slider 2A slider body 2B end cap 3 rolling element 4 cage 10A, 10B raceway groove 11A, 11A raceway groove 13A, 13B rolling path 14A, 14B return path 15 direction change path

Claims

1. A linear guide device comprising a guide rail, a slider arranged to move relative to the guide rail in the longitudinal direction, and a plurality of rolling elements arranged to roll freely along a rolling path formed between the guide rail and the slider, wherein the slider includes a slider body having a raceway surface facing the raceway groove of the guide rail to form the rolling path of the rolling elements and a return path for the rolling elements, and an end cap having a direction-changing path connecting the return path and the rolling path, the raceway surface has an end-side raceway surface intersecting the longitudinal end surface of the slider body and an inner-side raceway surface arranged on the opposite side of the longitudinal end surface with the end-side raceway surface interposed therebetween, the end-side raceway surface has a rotationally symmetric shape with respect to an end-side raceway surface center axis that coincides with or is parallel to the center line of the linear portion of the rolling path, and includes a partial conical raceway surface connected to the inner-side raceway surface and a curved raceway surface connecting the partial conical raceway surface and the longitudinal end surface, in a cross section including the end-side raceway surface center axis, the surface of the partial conical raceway surface is linear and the surface of the curved raceway surface is arcuate, and at the boundary between the partial conical raceway surface and the curved raceway surface in the cross section, the tangent of the partial conical raceway surface and the tangent of the curved raceway surface are common.

2. The linear guide device according to claim 1, wherein the inner-side raceway surface has a first raceway surface and a second raceway surface connecting the first raceway surface and the partial conical raceway surface, and in a cross section including the center line of the linear portion of the rolling path, the second raceway surface moves away from the center line of the linear portion as it approaches the partial conical raceway surface.

3. The linear guide device according to claim 1, wherein in at least one cross section including the center line of the linear portion of the rolling path, the tangent of the inner-side raceway surface and the tangent of the end-side raceway surface at the boundary between the inner-side raceway surface and the end-side raceway surface are different.

4. The linear guide device according to claim 1, wherein the inclination angle θ of the partial conical raceway surface with respect to the end-side raceway surface center axis is 10° or less.

5. The linear guide device according to claim 1, wherein in a cross section including the end-side raceway surface center axis, the radius of curvature r of the curved raceway surface is 0.2 times or more the diameter Da of the rolling element.

6. The surface roughness of the end-side raceway surface is rougher than that of the inner-side raceway surface, the linear motion guide device according to claim 1, characterized in that.

7. A method of manufacturing a linear motion guide device including a guide rail, a slider arranged to move relative to the guide rail in the longitudinal direction, and a plurality of rolling elements arranged to be freely rotatable along a rolling path formed between the guide rail and the slider, wherein the slider includes a raceway surface facing a raceway groove of the guide rail to form a rolling path for the rolling elements, and a slider body having a return path for the rolling elements, and an end cap having a direction-changing path connecting the return path and the rolling path, the raceway surface having an end-side raceway surface intersecting a longitudinal end surface of the slider body, and an inner-side raceway surface arranged on the opposite side of the longitudinal end surface with the end-side raceway surface interposed therebetween, the end-side raceway surface having a rotationally symmetric shape with respect to an end-side raceway surface center axis that coincides with or is parallel to a center line of a straight portion of the rolling path, and including a partial conical raceway surface connected to the inner-side raceway surface, and a curved raceway surface connecting the partial conical raceway surface and the longitudinal end surface, when the width direction of the slider body is defined as the X direction, the longitudinal direction of the slider body is defined as the Y direction, and a direction orthogonal to the X direction and the Y direction is defined as the Z direction, a first tool is rotated around a rotation axis parallel to the Z direction and moved parallel to the Y direction with respect to the slider body to form the inner-side raceway surface, a second tool is rotated around a rotation axis parallel to a center line of a straight portion of the rolling path and moved parallel to the X direction with respect to the slider body to form the end-side raceway surface, in a cross section including the end-side raceway surface center axis, a surface of the partial conical raceway surface is formed linearly, a surface of the curved raceway surface is formed in an arc shape, and in the cross section, a tangent line of the partial conical raceway surface and a tangent line of the curved raceway surface at a boundary between the partial conical raceway surface and the curved raceway surface are common, a method of manufacturing a linear motion guide device, characterized in that.

8. While moving the first tool in the Y direction, moving it in the X direction, the method of manufacturing a linear motion guide device according to claim 7, characterized in that.

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