Linear motion guiding device, and manufacturing method thereof

Abstract

To provide a linear motion guiding device capable of securing smooth movement of a ball while mitigating an impact force regardless of behaviors of the ball entering an orbital plane, and a manufacturing method thereof.SOLUTION: In a linear motion guiding device, an orbital plane has an end side orbital plane crossing with a longitudinal end face of a slider body, and an inside orbital plane arranged on a side opposite to the longitudinal end face across the end side orbital plane. The end side orbital plane has: a partial conical orbital plane having a rotary-symmetrical shape with an end side orbital plane center shaft coincident or parallel to a linear part centerline of a rolling passage, and connected to the inside orbital plane; and a curved orbital plane connecting the partial conical orbital plane and the longitudinal end face. On a cross section including the end side orbital plane center shaft, a surface of the partial conical orbital plane has a linear shape, and a surface of the curved orbital plane has an arc shape. On the cross section, a tangent line of the partial conical orbital plane and a tangential line of the curved orbital plane are common at a boundary of the partial conical orbital plane and the curved orbital plane.SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] A linear guide device that linearly guides a guided object while infinitely circulating rolling elements such as rollers and balls inside is an important mechanical element that has a great influence on the motion accuracy of semiconductor manufacturing equipment, ultra-precision machining machines, ultra-precision measuring instruments, and the like.

[0003] The linear guide device includes a guide rail provided with a rail-side rolling element raceway groove, a slider-side rolling element raceway groove provided opposite to the rail-side rolling element raceway groove, and a slider body supported by the guide rail so as to be axially movable through the rolling of a plurality of rolling elements disposed in a rolling passage formed between the slider-side rolling element raceway groove and the rail-side rolling element raceway groove. The linear guide device further includes a rolling element return passage provided in the slider body so as to be substantially parallel to the rolling passage, and a direction conversion passage provided in end caps attached to both ends in the moving direction of the slider body for communicating the rolling passage and the rolling element return passage.

[0004] When the rolling elements of the linear guide device infinitely circulate through the rolling passage, the direction conversion passage, and the rolling element return passage, periodic minute vibrations (hereinafter referred to as rolling element passing vibrations) occur, which greatly affects the motion accuracy of the above-described devices. The rolling element passing vibration occurs when the load on the rolling element rolling in the rolling passage (load region) under the influence of preload or external load is released when the rolling element exits the load region to the rolling element circulation path (unloaded region), or conversely, when a new load is applied when entering the load region from the unloaded region.

[0005] In order to suppress this rolling element passing vibration, inclined surfaces called crowning are provided at both ends of the slider-side rolling element raceway groove forming the rolling passage. By gradually causing load fluctuations associated with the entry and exit of the rolling element into and out of the load region by crowning, the rolling element passing vibration can be reduced.

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

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] By the way, when the ball enters the rolling path, so-called ball eccentricity, in which the center of the ball deviates from the center line of the return path, may become a problem. According to the technique of Patent Document 1, by combining the first crowning and the second crowning, a sufficient amount of drop can be formed in the groove bottom direction (the width direction of the slider) of the crowning to allow the eccentricity of the ball to escape. However, in directions other than the groove bottom direction, especially with respect to the eccentricity of the ball in the direction perpendicular to the groove bottom (the vertical direction of the slider), it is not possible to provide a relief at the end of the slider groove, so there is a risk that the durability will deteriorate due to the ball strongly colliding with the end surface of the slider.

[0009] The present invention has been made in view of the above problems, and an object thereof is to provide a linear guide device and a method for manufacturing the same that can ensure smooth movement of the ball while reducing the impact force regardless of the behavior of the ball entering the raceway surface.

Means for Solving the Problems

[0010] The linear guide device of the present invention is 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 passage formed between the guide rail and the slider, and is a linear guide device comprising: the slider comprises a slider body having an orbital surface facing the orbital groove of the guide rail to form a rolling passage for the rolling elements and a return passage for the rolling elements, and an end cap having a direction-changing passage connecting the return passage and the rolling passage, the orbital surface has an end-side orbital surface intersecting the longitudinal end surface of the slider body and an inner-side orbital surface arranged on the opposite side of the longitudinal end surface with the end-side orbital surface interposed therebetween, the end-side orbital surface has a rotationally symmetric shape with respect to an end-side orbital surface center axis that coincides with or is parallel to the center line of the linear portion of the rolling passage, and has a partial conical orbital surface connected to the inner-side orbital surface and a curved orbital surface connecting the partial conical orbital surface and the longitudinal end surface, in a cross section including the end-side orbital surface center axis, the surface of the partial conical orbital surface is linear and the surface of the curved orbital surface is arc-shaped, in the cross section, a tangent line of the partial conical orbital surface and a tangent line of the curved orbital surface at the boundary between the partial conical orbital surface and the curved orbital surface are common, which is characterized by this.

[0011] A method for manufacturing the linear guide device of the present invention is 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 passage formed between the guide rail and the slider, and is a method for manufacturing a linear guide device comprising: the slider A slider body having a raceway surface that is disposed opposite to the raceway groove of the guide rail and forms a rolling path for the rolling elements, and a return path for the rolling elements; An end cap having a direction-changing path that connects the return path and the rolling path; The raceway surface has an end-side raceway surface that intersects the longitudinal end surface of the slider body, and an inner-side raceway surface that is disposed on the side opposite to 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 straight portion of the rolling path, and includes a partial conical raceway surface that is connected to the inner-side raceway surface, and a curved raceway surface that connects 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 the direction orthogonal to the X direction and the Y direction 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 the first tool in parallel to the Y direction with respect to the slider body; The end-side raceway surface is formed by rotating a second tool around a rotation axis parallel to the center line of the straight portion of the rolling path and moving the second tool in parallel to the X direction with respect to the slider body; In a cross section including the end-side raceway surface center axis, the surface of the partial conical raceway surface is formed in a straight line shape, and the surface of the curved raceway surface is formed in an arc shape; In the cross section, at the boundary between the partial conical raceway surface and the curved raceway surface, the tangent line of the partial conical raceway surface and the tangent line of the curved raceway surface are common.

Advantages of the Invention

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

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

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Figure 22

MODE FOR CARRYING OUT THE INVENTION

[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 FIG. 2 unless otherwise specified. Further, the "longitudinal direction" refers to the longitudinal direction of the guide rail or the 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 in FIG. 1 as viewed from the longitudinal direction of the guide rail, but the end caps are omitted. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, but the retainer 4 and the retainer groove 10Ba are omitted. In FIG. 2, a plane passing through the center in the width direction of the slider body 2A and the longitudinal axis of the guide rail 1 is defined as a vertical center plane CP. A plane passing through the center line O1 of the straight portion of a pair of rolling paths 13A disposed on both sides with the guide rail 1 interposed therebetween and orthogonal to the vertical center plane CP is defined as a horizontal reference plane HP. Also, a plane passing through the center line O1 of the straight portion of the rolling path 13A and orthogonal to the horizontal reference plane HP is defined as a vertical reference plane VP. Although details will be described later, each component configuration will be described using the vertical reference plane VP and the horizontal reference plane HP corresponding to one of the rolling paths 13A.

[0016] A slider 2 having a substantially U-shaped cross section is assembled movably in the longitudinal direction of a guide rail 1 having a substantially rectangular cross section extending linearly. Track grooves 10A, 10A each formed of a concave groove having a substantially quarter-circular cross section are formed along the longitudinal direction at the ridge portions where the left and right side surfaces 1a, 1a in the width direction of the guide rail 1 and the upper surface 1b intersect.

[0017] Also, track grooves 10B, 10B each formed of a concave groove having a substantially semi-circular cross section are formed along the longitudinal direction at substantially the central portions in the vertical direction of the left and right side surfaces 1a, 1a in the width direction of the guide rail 1. Further, at the groove bottom portions of the track grooves 10B, 10B, a retainer groove 10Ba (wire groove) for accommodating a part of the retainer 4 and guiding the retainer 4 when the slider 2 moves is formed along the longitudinal direction between both ends of the movement region of the slider 2 (for example, between both ends in the longitudinal direction of the guide rail 1). The cross-sectional shape of the retainer groove 10Ba is, for example, substantially rectangular.

[0018] Further, the slider 2 is composed of a flat body portion 7 facing the upper surface 1b of the guide rail 1 and two leg portions 6, 6 extending downward from both left and right sides of the body portion 7 and facing the side surface 1a. Since the angle formed by the body portion 7 and the leg portions 6, 6 is substantially a right angle, the cross-sectional shape of the slider 2 is substantially U-shaped. Further, the slider 2 is movably attached to the guide rail 1 in such a manner that the guide rail 1 is sandwiched between both leg portions 6, 6.

[0019] The slider 2 includes a slider main body 2A and end caps 2B, 2B detachably attached to both ends (both ends in the longitudinal direction) of the slider main body 2A. Further, on both ends of the slider 2 (the outer end faces in the longitudinal direction of each end cap 2B), side seals 5, 5 are mounted which are in sliding contact with the outer surfaces (the upper surface 1b and the side surfaces 1a, 1a) of the guide rail 1 and seal the portion facing the longitudinal end face side of the opening of the gap between the guide rail 1 and the slider 2. Under seals 8, 8 are mounted on the lower part of the slider 2 to seal the portion facing the lower surface side of the opening of the gap between the guide rail 1 and the slider 2. These side seals 5, 5 and under seals 8, 8 prevent foreign matter from entering the gap from the outside and prevent lubricant from leaking from the gap to the outside.

[0020] Further, on the corner portions and the substantially central portion in the vertical direction of the inner surfaces of the left and right leg portions 6, 6 of the slider main body 2A, there are formed raceways 11A, 11A, 11B, 11B (hereinafter, these may be collectively referred to by the reference numeral 11) composed of concave grooves having a substantially semicircular cross-sectional shape facing the raceway grooves 10A, 10A, 10B, 10B (hereinafter, these may be collectively referred to by the reference numeral 10) of the guide rail 1. Further, rolling passages 13A, 13A, 13B, 13B (hereinafter, these may be collectively referred to by the reference numeral 13) having a substantially circular cross-section are respectively formed between the raceway grooves 10 of the guide rail 1 and the raceway grooves 11 of the slider 2, and these rolling passages extend in the longitudinal direction.

[0021] A plurality of rolling elements 3 (balls) are loaded in the rolling path 13 so as to be rotatable while being held by a cage 4. Through the rolling of the rolling elements 3 in the rolling path 13, the slider 2 is guided by the guide rail 1 and is movable in the longitudinal direction. The cage 4 is formed of, for example, wire and holds the rolling elements 3 to prevent the rolling elements 3 from dropping off from the slider 2 before being assembled to the guide rail 1.

[0022] Note that the number of raceways 10 and 11 provided in the guide rail 1 and the slider 2 is not limited to two rows on one side, and may be, for example, one row on one side or three or more rows as in the second embodiment described later. Further, the cross-sectional shape of the raceways 10 and 11 may be an arc shape formed of a single arc as described above, or may be a substantially V-shaped (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, 14 may be used as a collective reference for these) which are through holes having a substantially circular cross-sectional shape penetrating in the longitudinal direction parallel to the rolling path 13 at the upper and lower parts of the thick portions of the left and right leg portions 6, 6 of the slider body 2A (see FIGS. 2 and 3).

[0024] The end cap 2B is made of, for example, a molded product of a resin material and has a substantially U-shaped cross-sectional shape similar to the slider body 2A. Further, on both left and right sides of the back surface (contact surface with the slider body 2A) of the end cap 2B, direction-changing paths 15 that are circular in cross-sectional shape and curved in an arc shape are formed in two upper and lower stages (see FIG. 3). When the end cap 2B is attached to the slider body 2A with a fastening member such as a screw, the rolling path 13 and the return passage 14 are connected by the direction-changing path 15. Note that the cross-sectional shape of the direction-changing path 15 is schematically shown in FIG. 3.

[0025] These return passages 14 and the turning passages 15 at both ends constitute a rolling element conveying path 16 that conveys the rolling elements 3 from the end point to the start point of the rolling path 13 and circulates them. The rolling path 13 and the rolling element conveying path 16 constitute a substantially annular circulation path (see Fig. 3). This substantially annular circulation path is formed on both the left and right sides with the guide rail 1 interposed therebetween.

[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 with respect to the guide rail 1 while rolling in the rolling path 13. Then, 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 turning passage 15. The rolling elements 3 that enter the turning passage 15 change their direction and are introduced into the return passage 14, pass through the return passage 14, reach the turning passage 15 on the opposite side, change their direction again here, and return to the start point of the rolling path 13. By the rolling elements 3 repeating such circulation in the circulation path infinitely, the slider 2 moves smoothly along the guide rail 1.

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

[0028] With reference to the drawings, the end shape of the raceway groove 11A will be described. Hereinafter, the raceway groove 11A will be described as the upper raceway groove, and the raceway groove 11B will be described as the lower raceway groove. Also, when simply referring to the first raceway surface, it refers to at least one of the first upper raceway surface and the first lower raceway surface, and when simply referring to the second raceway surface, it refers to at least one of the second upper raceway surface and the second lower raceway surface.

[0029] In FIG. 5, the upper track groove 11A has, starting from the central side of the slider body 2A, a first upper track surface 11Aa, a second upper track surface 11Ab, a third upper track surface 11Ac, and a fourth upper track surface 11Ad that intersects the end face (longitudinal end) 2Aa of the slider body 2A. These four track surfaces are each formed over the entire width direction (substantially a semi - circumference) of the upper track groove 11A. Here, the first upper track surface 11Aa and the second upper track surface 11Ab are referred to as the inner - side track surfaces, and the third upper track surface 11Ac and the fourth upper track surface 11Ad are referred to as the end - side track surfaces. Note that the third upper track surface 11Ac may be referred to as a partial conical track surface, and the fourth upper track surface 11Ad may be referred to as a curved - surface track surface.

[0030] In the upper track groove 11A, with the vertical center line C1 (virtual line) at the groove bottom as a boundary, the part above the vertical center line C1 is called the upper flank, and the part below the vertical center line C1 is called the lower flank. The upper flank and the lower flank are symmetric shapes with respect to the vertical center line C1. The vertical center line C1 and the center line O1 of the straight - line part of the rolling passage 13A are within the horizontal reference plane HP (FIG. 2).

[0031] Note that the dashed lines extending in the circumferential direction in FIG. 5 schematically show the boundaries between the first upper track surface 11Aa and the second upper track surface 11Ab, and between the third upper track surface 11Ac and the fourth upper track surface 11Ad. Since the first upper track surface 11Aa and the second upper track surface 11Ab, and the third upper track surface 11Ac and the fourth upper track surface 11Ad are connected by sharing a tangent line in the longitudinal cross - section, the ridge line is not actually visible. However, here it is shown by a dashed line for easy understanding of the configuration.

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

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

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

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

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

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

[0038] Also, the lower raceway groove 11B shown in FIG. 5 is parallel to the upper raceway groove 11A and has the same shape as the upper raceway groove 11A, so its description is omitted. Further, since the shape of the other end side of the upper raceway groove 11A and the lower raceway groove 11B is also the same as described above, its description is omitted.

[0039] (Operational Effects of the Present Embodiment) FIG. 9 is a schematic diagram showing a side surface similar to FIG. 8 according to the comparative example together with the rolling elements. FIG. 10 is a schematic diagram showing a side surface similar to FIG. 8 according to the present embodiment together with the rolling elements, but since the drop amount of the second upper raceway surface 11Ab is very small, it is not shown here. FIG. 11 is a schematic diagram showing a side surface similar to FIG. 8 according to the present 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, vibration, etc. when passing through the turning path 15 (see FIG. 3) in the end cap 2B, the center of the rolling element 3 may deviate from the center line O1 of the straight portion of the rolling path 13A and enter the rolling path 13A from the turning path 15 in a deviated state. At this time, the deviation amount 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. Since the diameter Da of the rolling element 3 is slightly smaller than the diameter of the rolling path 13A, when the eccentricity e is smaller than 1 / 2 of the diameter difference, the rolling element 3 can smoothly enter the rolling path 13A. However, when the eccentricity e exceeds 1 / 2 of the diameter difference in the vertical direction, as shown in FIG. 9, the rolling element 3 abuts against the edge at the entrance direction of the rolling path 13A, which may cause noise generation and damage to the rolling element 3.

[0041] On the other hand, according to the present embodiment, the fourth upper raceway surface 11Ad having a drop amount d4 is formed at the entrance direction end of the rolling path 13A in the side view shown in FIG. 10. Therefore, even in a state of being eccentric with an eccentricity e exceeding 1 / 2 of the above diameter difference, the rolling element 3 entering from the turning path 15 obliquely abuts against the fourth upper raceway surface 11Ad having an outward convex arc shape and then rolls, and further rolls on the partially conical third upper raceway surface 11Ac and the second upper raceway surface 11Ab, thereby gradually changing the moving direction and being guided by the first upper raceway surface 11Aa. By suppressing the generation of a large contact pressure, the generation of noise and damage to the rolling element 3 can be suppressed, and smooth movement of the rolling element 3 can be ensured.

[0042] Also, in the side view shown in FIG. 11, when the rolling element 3 eccentric with an eccentricity e exceeding 1 / 2 of the above diameter difference enters, the rolling element 3 entering from the turning path 15 has a drop amount d4' and obliquely abuts against the fourth upper raceway surface 11Ad having an outward convex arc shape and then rolls, and further rolls on the partially conical third upper raceway surface 11Ac and the second upper raceway surface 11Ab, thereby gradually changing the moving direction and being guided by the first upper raceway surface 11Aa. Thereby, the impact force on the slider body 2A is alleviated, and the generation of noise and damage to the rolling element 3 can be suppressed.

[0043] The lower track groove 11B also has the same configuration as the upper track groove 11A, and thus exhibits the same effect.

[0044] (Processing Method of the First Upper Track Surface and the Second Upper Track Surface) Next, the processing method of the upper track groove 11A will be described. FIG. 12 is a schematic diagram showing a part of the blank of the slider body 2A viewed from the direction perpendicular to the longitudinal direction and the cutting tool TL1. FIG. 13 is a schematic diagram showing the blank of the slider body 2A viewed from the longitudinal direction and the grinding tool TL2.

[0045] In FIGS. 12 and 13, the longitudinal direction of the slider body 2A is defined as the Y direction, the width direction of the slider body 2A is defined as the X direction, and the vertical direction is defined as the Z direction. The Y direction is parallel to the center line O1 of the straight portion.

[0046] The cutting tool (second tool) TL1 shown in FIG. 12 is an end mill or the like, and has a tapered cutting edge TL1a on its outer periphery. When the cutting tool TL1 is rotated about its center line RO1, the rotational locus of the cutting edge TL1a coincides with the final surface shapes of the third upper track surface 11Ac and the fourth upper track surface 11Ad.

[0047] When machining the third upper track surface 11Ac and the fourth upper track surface 11Ad, first, in the blank of the slider body 2A, a groove similar to the first upper track surface 11Aa is formed by cutting or the like. Then, while keeping the center line RO1 of the cutting tool TL1 parallel to the center line O1 of the straight portion and positioning the blank of the slider body 2A in the Y direction, the cutting tool TL1 is rotated about the center line RO1 and translated in the X direction to a predetermined position (the center line RO1 coincides with the rotational center axis of the rotationally symmetric shape of the final surface shapes of the third upper track surface 11Ac and the fourth upper track surface 11Ad, that is, the position of the end-side track surface center axis). Thereby, the third upper track surface 11Ac and the fourth upper track surface 11Ad can be simultaneously machined and formed in a short time with the overall cutting tool TL1.

[0048] Incidentally, if the inclination angle θ of the third upper raceway surface 11Ac with respect to the center axis of the end-side raceway surface is too large, the amount of material removed from the blank at one time becomes too large, the resistance during processing increases, and the processing becomes difficult. Therefore, for convenience of processing, the inclination angle θ is desirably greater than 0° and not more than 45°. The appropriate range of the inclination angle θ will be described later from the viewpoint of the function and effect of the upper raceway groove 11A.

[0049] Since the rotation locus of the cutting edge TL1a is smoothly connected between the portion corresponding to the third upper raceway surface 11Ac and the portion corresponding to the fourth upper raceway surface 11Ad, in the longitudinal cross-section of the slider body 2A (the cross-section passing through the center axis of the end-side raceway surface), the tangent line of the third upper raceway surface 11Ac at the boundary between the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad and the tangent line of the fourth upper raceway surface 11Ad overlap each other.

[0050] The grinding tool (first tool) TL2 shown in FIG. 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 by a plane passing through the center line RO2 of the grinding tool TL2, the grinding wheel TL2a has an outer peripheral surface having the same semi-circular shape as the upper raceway groove 11A.

[0051] When grinding the first upper raceway surface 11Aa and the second upper raceway surface 11Ab, with the center line RO2 of the grinding tool TL2 aligned in the Z direction, the grinding tool TL2 that rotates around the center line RO2 is applied to the inside of the leg portion 6, and after starting the grinding of the inner surface of the first upper raceway surface 11Aa with the outer peripheral surface of the grinding wheel TL2a, the grinding tool TL2 is moved in the Y direction toward the end face 2Aa. Thereby, the first upper raceway surface 11Aa is linearly formed along the Y direction.

[0052] The crowning formed on the second upper raceway surface 11Ab can be performed by controlling the cutting of the grinding tool TL2. That is, a crowning is formed such that the amount of drop changes when viewed in the cross-section of FIG. 7 but the amount of drop does not appear when viewed in the side view of FIG. 8.

[0053] Specifically, after forming the first upper track surface 11Aa, while aligning the center line RO2 in the Z direction, the grinding tool TL2 is rotated and translated in the Y direction, and at the same time, it is translated outward in the X direction as it approaches the end face 2Aa of the slider body 2A. As a result, a second upper track surface 11Ab having a crowning shape in the cross section of FIG. 7, that is, in the slider width direction, but not having a crowning shape in the side view of FIG. 8, that is, in the slider vertical direction, is formed. Note that, for example, in order to simplify the processing steps, it is not necessary to provide crowning on the second upper track surface 11Ab. In that case, the grinding tool TL2 is not moved in the X direction. In such a case, the inner side track surface is only the first upper track surface 11Aa, and it can also be said that the third upper track surface 11Ac and the first upper track surface 11Aa are in direct contact. Therefore, when the second upper track surface 11Ab does not exist and the third upper track surface 11Ac and the first upper track surface 11Aa are in direct contact, hereinafter, the second upper track surface 11Ab is referred to as the first upper track surface 11Aa.

[0054] According to the present embodiment, the boundary between the second upper track surface 11Ab and the third upper track surface 11Ac does not substantially share their tangents. In other words, in at least one cross section passing through the center line O1 of the straight portion, the tangent of the second upper track surface 11Ab and the tangent of the third upper track surface 11Ac at the boundary between the second upper track surface 11Ab and the third upper track surface 11Ac are different. That is, it allows for the formation of a ridge (edge) at the boundary between the second upper track surface 11Ab and the third upper track surface 11Ac. For this reason, the first upper track surface 11Aa or the second upper track surface 11Ab can be formed in a process different from that of the third upper track surface 11Ac (and the fourth upper track surface 11Ad). The order of processing by the cutting tool TL1 and the grinding tool TL2 is not limited, and either can be performed first.

[0055] As described above, according to the present embodiment, in the longitudinal cross section of the slider body 2A (the cross section passing through the center line O1 of the straight portion), since the boundary between the second upper track surface 11Ab and the third upper track surface 11Ac does not need to substantially share a tangent, after machining the third upper track surface 11Ac, it is not necessary to finish machining the connecting portion with the second upper track surface 11Ab. For this reason, the manufacture of the slider body 2A becomes easy.

[0056] Note that the fact that the second upper raceway surface 11Ab and the third upper raceway surface 11Ac "do not substantially share a tangent line" means that although the boundary between the second upper raceway surface 11Ab and the third upper raceway surface 11Ac is on the ridge line, they do not share a tangent line in most of it. That is, after forming the third upper raceway surface 11Ac, when forming the first upper raceway surface 11Aa or the second upper raceway surface 11Ab, there may be a part where the tangents of each other are partially shared, but this case is also included in the configuration of "not substantially sharing the tangent lines of each other".

[0057] (Regarding the inclination angle θ) FIG. 14 is an enlarged schematic view showing a cross section similar to that of FIG. 7 together with the rolling elements, and shows an example in which the eccentricity of the rolling elements is relatively small. When the rolling element 3 enters the raceway surface, when the eccentricity amount e is relatively small, first, the rolling element 3 collides with the third upper raceway surface 11Ac at point P1. Due to this collision, a collision force F1 acts between the rolling element 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 higher the concern about damage to the collision part.

[0058] Regarding the case where the inclination angle θ of the third upper raceway surface 11Ac is changed, the results of numerically calculating (calculation based on the elastic contact theory) the contact pressure due to the collision are shown in FIG. 15. In this calculation, the ball diameter was 4.7625 mm, the materials of the ball and the slider were steel materials, and the ball speed V (the component parallel to the linear motion direction) at the time of collision was 1 m / s.

[0059] The horizontal axis of FIG. 15 is the inclination angle θ (deg), and the vertical axis of FIG. 15 is the ratio of the contact pressure at each inclination angle when the contact pressure at the inclination angle θ = 30° is used as a reference (ratio = 1). From the results of FIG. 15, it can be seen that when the inclination angle θ is set to 10° or less, the effect of reducing the contact pressure becomes remarkable. That is, the inclination angle θ of the third upper raceway surface 11Ac is preferably 10° or less.

[0060] (Regarding the radius of curvature r) FIG. 16 is an enlarged schematic view showing a cross section similar to that of FIG. 7 together with rolling elements, and shows an example in which the eccentricity of the rolling elements is relatively large. When the rolling element 3 enters the raceway surface, when the eccentricity e is relatively large, the rolling element 3 collides with the fourth upper raceway surface 11Ad at point P2. Due to this collision, a collision force F2 acts between the rolling element 3 and the fourth upper raceway surface 11Ad at point P2, and at the same time, a contact pressure is generated at point P2. Let the radius of curvature of the cross section of the fourth upper raceway surface 11Ad in FIG. 16 be r, and the diameter of the rolling element 3 be Da.

[0061] Regarding the case where the radius of curvature r of the cross section of the fourth upper raceway surface 11Ad is changed, the results of numerically calculating the contact pressure due to the collision (calculation based on the elastic contact theory) are shown in FIG. 17. The calculation conditions are the same as those in FIG. 15.

[0062] The horizontal axis in FIG. 17 is the ratio (r / Da) of the radius of curvature r to the diameter Da of the rolling element, and the vertical axis in FIG. 17 is the ratio of the contact pressure at each arc radius with the contact pressure at r / Da = 0.06 (r = 0.3 mm) as the reference (ratio = 1). From the results in FIG. 17, it can be seen that when the ratio of the radius of curvature r to the diameter Da of the rolling element is 0.2 or more, the effect of reducing the contact pressure becomes remarkable. That is, the cross-sectional radius of curvature r of the fourth upper raceway surface 11Ad is preferably 0.2 times or more the diameter Da of the rolling element.

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

[0064] (Example 1) In this embodiment, as shown in FIG. 18, it has 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, when eccentricity occurs at the time of entry of the rolling element, in order to smoothly guide the rolling element, a sufficient large amount of drop d4 is required. At the same time, in order to avoid damage to the third upper raceway surface 11Ac, as described above, it is necessary to reduce the inclination angle θ of the third upper raceway surface 11Ac. Here, as an example, the inclination angle θ = 10°, the amount of drop d4 = 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.

[0066] (Comparative Example 1) On the other hand, in Comparative Example 1 shown in FIG. 19, it has only the third upper raceway surface 11Ac as the end-side raceway surface and does not have the fourth upper raceway surface 11Ad. Therefore, the third upper raceway surface 11Ac intersects the end face 2Aa.

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

[0068] When the linear motion guide device is in use, the slider 2 receives a load and supports the load by the guide rail 1 via the rolling element 3. At this time, among the slider raceway surfaces, only the inner-side raceway surface can receive the load. That is, when the end-side raceway surface becomes long, the length of the inner-side raceway surface that receives the load becomes short, which may reduce the life of the linear motion guide device.

[0069] (Comparative Example 2) In Comparative Example 2 shown in FIG. 20, it has the same configuration as Comparative Example 1, but the longitudinal length L2 of the third upper raceway surface 11Ac is set to 1.5 mm, the same as in Example 1. With this configuration, the length of the inner-side raceway surface that receives the load can be ensured to be about the same as in Example 1.

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

[0071] On the other hand, according to Example 1 corresponding to the present embodiment, since the end-side raceway surface is composed of the third upper raceway surface 11Ac with a linear cross-section and the fourth upper raceway surface 11Ad with an arc-shaped cross-section, the inclination angle θ can be kept small, maintaining the durability against rolling element collisions while ensuring a sufficient drop amount 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 composed of 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 a linear cross-section.

[0073] In Comparative Example 3, similar 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, since the cross-sections of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad are linear, a ridge line extending in the circumferential direction necessarily occurs at the boundary (point P3) between the two. That is, the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad do not share a tangent line. Since the boundary between the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad becomes an edge, when the rolling element 3 collides with the edge, a very large contact pressure is generated (corresponding to the case where r / Da is very small in FIG. 17). For this reason, the durability during high-speed operation is a concern.

[0075] In contrast, in Example 1 corresponding to this embodiment, in a cross-section including the central 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 surface are smoothly connected so as to share a tangent line with each other. As a result, the formation of a ridge line (edge) at the boundary between the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad is suppressed, and even if the rolling element 3 collides with the boundary, excessive contact pressure does not occur, and the concern about durability degradation is eliminated.

[0076] (Second Embodiment) FIG. 22 is a side view similar to FIG. 8 of the slider body 2A according to the second embodiment. The shape of the upper raceway groove 11A in this embodiment is the same as that in the first embodiment, but the surface roughness of the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad is rougher than the surface roughness of the first upper raceway surface 11Aa. The surface roughness of the second upper raceway surface 11Ab is substantially equal to the surface roughness of the first upper raceway surface 11Aa. The surface roughness can be evaluated by the arithmetic mean roughness Ra or the like. 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 rougher than the arithmetic mean roughness Ra of the first upper raceway surface 11Aa. The same applies to the lower raceway groove 11B. Since the other configurations are the same as those in the first embodiment, duplicate descriptions are omitted.

[0077] When the rolling element enters the raceway surface, the first to collide with is the third upper raceway surface 11Ac or the fourth upper raceway surface 11Ad. If the collision of the rolling element is absorbed by the third upper raceway surface 11Ac or the fourth upper raceway surface 11Ad and sufficiently attenuated, the collision after the second time due to bounce can be mitigated, and an improvement in the durability of the linear motion guide device can be expected. In order to give such attenuation, it is effective to increase the roughness of the third upper raceway surface 11Ac or the fourth upper raceway surface 11Ad so as to easily hold 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 imparting of roughness can be realized by providing irregularities on the cutting edge TL1a of the cutting tool TL1 that machines the third upper raceway surface 11Ac and the fourth upper raceway surface 11Ad. Illustrating the dimensions of these irregularities, the height between the peak and valley is about 5 to 10 μm, and the distance between adjacent peaks is about 0.2 mm. Note that spiral irregularities may be formed by moving the cutting tool TL1 in the Y direction in synchronization with the rotation.

[0079] The present invention is not limited to the above-described embodiment. Combinations of the respective configurations of the embodiment, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, are also contemplated by the present invention and are included in the scope for which protection is sought.

Explanation of Reference Numerals

[0080] 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 passage 14A, 14B Return passage 15 Direction-changing path

Claims

1. 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 rollable along a rolling path formed between the guide rail and the slider, wherein the linear guide device comprises: the slider includes a slider body having an orbital surface disposed opposite to the 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-changing path connecting the return path and the rolling path, the orbital surface has an end-side orbital surface intersecting the longitudinal end surface of the slider body, and an inner-side orbital surface disposed on the opposite side of the longitudinal end surface with the end-side orbital surface interposed therebetween, the end-side orbital surface has a rotationally symmetric shape with respect to an end-side orbital 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 orbital surface connected to the inner-side orbital surface, and a curved orbital surface connecting the partial conical orbital surface and the longitudinal end surface, in a cross section including the end-side orbital surface center axis, the surface of the partial conical orbital surface is linear, and the surface of the curved orbital surface is arcuate, in the cross section, at the boundary between the partial conical orbital surface and the curved orbital surface, the tangent of the partial conical orbital surface and the tangent of the curved orbital surface are common, characterized in that it is a linear guide device.

2. the inner-side orbital surface has a first orbital surface and a second orbital surface connecting the first orbital surface and the partial conical orbital surface, in a cross section including the center line of the linear portion of the rolling path, the second orbital surface is spaced apart from the center line of the linear portion as it approaches the partial conical orbital surface, characterized in that it is the linear guide device according to claim 1.

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

4. the inclination angle θ of the partial conical orbital surface with respect to the end-side orbital surface center axis is 10° or less, characterized in that it is the linear guide device according to claim 1.

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

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 guide rail, A slider arranged to move relative to the guide rail in the longitudinal direction, A method for manufacturing a linear motion guide device including a plurality of rolling elements arranged to roll freely along a rolling passage formed between the guide rail and the slider, The slider is, A slider body having a raceway surface facing the raceway groove of the guide rail to form a rolling passage for the rolling elements, and a return passage for the rolling elements, An end cap having a direction-changing passage connecting the return passage and the rolling passage, 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 straight portion of the rolling passage, 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, When the width direction of the slider body is the X direction, the longitudinal direction of the slider body is the Y direction, and the direction orthogonal to the X direction and the Y direction is the Z direction, A first tool is rotated around a rotation axis parallel to the Z direction and translated in 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 the center line of the straight portion of the rolling passage and translated in 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, the surface of the partial conical raceway surface is formed linearly, and the surface of the curved raceway surface is formed in an arc shape, In the cross section, at the boundary between the partial conical raceway surface and the curved raceway surface, the tangent of the partial conical raceway surface and the tangent of the curved raceway surface are common, A method for manufacturing a linear motion guide device, characterized in that.

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

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