Motion guide device

Abstract

Provided is a motion guide device that makes it possible to improve the durability of a cap member. On each of the right and left sides of a motion guide device (10), at least two circulation paths are provided to the upper and lower parts. Balls (3) which have moved on a rolling path are each sandwiched between a wall surface (12a) of a turning circulation groove (12) of a cap member (5) and a rolling groove (1a) of a rail (1). In a cross sectional view of the motion guide device (10) perpendicular to the rail, balls (3) on an upper rolling groove (1a) of the rail (1) are turned in an obliquely downward direction (A1), and / or balls (3) on a lower rolling groove (1a) of the rail (1) are turned in an obliquely upward direction (A2).

Description

Movement guide device

[0001] The present invention relates to a motion guide device in which a plurality of balls are interposed between a rail and a carriage so as to be capable of rolling motion.

[0002] The motion guide device includes a rail with a rolling groove and a carriage with a rolling groove, a return path, and a turning path (see Patent Document 1). A plurality of balls are arranged in a circulation path including the rolling path, the return path, and the turning path between the rolling groove of the rail and the rolling groove of the carriage.

[0003] The carriage includes a carriage body in which a rolling groove is formed, and a cover member in which a turn circulation groove of the turning path is formed. The cover member is also called an end plate, an end cap, or the like.

[0004] In a conventional motion guide device, as shown in Figure 9, the ball 103 moving along the rolling path hits the ball scooping portion 112a of the turning circulation groove 112 of the cover member 105, and when viewed in a cross section of the motion guide device perpendicular to the rail, the ball 103 on the rolling groove of the rail is turned in the contact angle direction 111 or in directions A1 and A2 slightly tilted from the contact angle direction 111.

[0005] Japanese Patent Application Laid-Open No. 2022-154793

[0006] However, in conventional motion guide devices, the ball scooping portion 112a of the cover member 105, which hits the ball 103 as it moves along the rolling path, has a thin edge, and as the speed and acceleration of the ball 103 increase, the stress generated in the ball scooping portion 112a increases, resulting in the problem of the ball scooping portion 112a being damaged early.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a motion guide device that can improve the durability of a cover member.

[0008] In order to solve the above problems, one aspect of the present invention is a motion guide device comprising: a rail having a rolling groove; a carriage having a rolling groove, a return path, and a turning path; and a plurality of balls arranged in a circulation path including the rolling path between the rolling groove of the rail and the rolling groove of the carriage, the return path, and the turning path, wherein the carriage comprises a carriage body in which the rolling groove is formed, and a cover member in which a turn circulation groove of the turning path is formed, and wherein at least two circulation paths are provided above and below on each of the left and right sides of the motion guide device, wherein balls that have moved along the rolling paths are sandwiched between the wall surface of the turn circulation groove of the cover member and the rolling groove of the rail, and when viewed in a cross section of the motion guide device perpendicular to the rail, the balls on the upper rolling groove of the rail turn diagonally downward and / or the balls on the lower rolling groove of the rail turn diagonally upward.

[0009] In order to solve the above problems, another aspect of the present invention comprises a rail having a rolling groove, a carriage having a rolling groove, a return path, and a turning path, and a plurality of balls arranged in a circulation path including the rolling path between the rolling groove of the rail and the rolling groove of the carriage, the return path, and the turning path, wherein the carriage comprises a carriage body in which the rolling groove is formed, and a cover member in which a turn circulation groove of the turning path is formed, and in this motion guide device in which at least two circulation paths are provided above and below on each of the left and right sides of the motion guide device, balls that have moved along the rolling path are sandwiched between the wall surface of the turn circulation groove of the cover member and the rolling groove of the rail, and in a cross section of the motion guide device perpendicular to the rail, the turn circulation groove on the upper side of the cover member is curved convex downward, and / or the turn circulation groove on the lower side of the cover member is curved convex upward.

[0010] According to the present invention, the ball scooping portion of the cover member, which the ball that moves along the rolling path hits, can be made thicker, allowing for surface contact between the ball and the ball scooping portion. This reduces the stress generated in the ball scooping portion, improving the repeated durability of the cover member. Furthermore, according to the present invention, the overall height of the motion guide device can be kept low.

[0011] 5(a) is a perspective view of the motion guide device of one embodiment of the present invention. FIG. 5(b) is a cross-sectional view perpendicular to the rail of the motion guide device of this embodiment. FIG. 5(c) is a cross-sectional view perpendicular to the rail of the motion guide device of this embodiment. FIG. 5(a) is a perspective view of the R piece part attached to the lid member. FIG. 5(c) is a front view of the R piece part. FIG. 5(a) is a perspective view of the R piece part seen from the carriage body side, FIG. 5(b) is a perspective view of the R piece part seen from the lid member side, and FIG. 5(c) is a front view of the R piece part. FIG. 5(c) is a cross-sectional view perpendicular to the rail showing the state in which a ball that has moved along the rolling path is sandwiched between the wall surface of the turn circulation groove of the lid member and the rolling groove of the rail. FIG. 5(c) is a perspective view of the motion guide device of a conventional embodiment.

[0012] The motion guide device of the present invention will be described below with reference to the accompanying drawings. However, the motion guide device of the present invention can be embodied in various forms and is not limited to the embodiments described herein. The present embodiments are provided with the intention that those skilled in the art will be able to fully understand the invention by fully disclosing the specification.

[0013] 1 shows a perspective view of a motion guide device 10 according to one embodiment of the present invention. The motion guide device 10 according to this embodiment relates to a small-sized motion guide device known as a miniature guide, but is not limited to this.

[0014] The motion guide device 10 includes a rail 1 and a carriage 2. The rail 1 is attached to a base or the like (not shown). The carriage 2 is attached to a table or the like (not shown). The carriage 2 is guided by the rail 1 and is movable relative to the rail 1.

[0015] For ease of explanation, the configuration of the motion guide device 10 will be described below using the directions when the motion guide device 10 placed on a horizontal plane is viewed from the length direction of the rail 1, that is, the up / down, left / right, and front / back directions in Figures 1 and 2. Of course, the placement of the motion guide device 10 is not limited to this.

[0016] As shown in FIG. 1 , the rail 1 has a rolling groove 1a. The carriage 2 has a rolling groove 4a, a return path C3, and a turning path C2. A plurality of balls 3 are arranged on a circulation path 7 including the rolling path C1, the return path C3, and the turning path C2 between the rolling groove 1a of the rail 1 and the rolling groove 4a of the carriage 2. The rolling path C1 and the return path C3 are linear. The turning path C2 is approximately U-shaped. Two circulation paths 7 are provided, one above the other and one below the other, on the left and right sides of the motion guide device 10.

[0017] The upper surface of the rail 1 is formed with a mounting hole 1b for mounting the rail 1 to a base or the like. Two rolling grooves 1a, one above the other, are formed on each of the left and right side surfaces of the rail 1. Each rolling groove 1a is a circular arc groove. Alternatively, each rolling groove 1a may be a Gothic arch groove.

[0018] The carriage 2 includes a carriage body 4 in which a rolling groove 4a is formed, a pair of cover members 5 in which a turn circulation groove on the outer periphery of the turning path C2 is formed, and a pair of R-piece portions 8 (see FIG. 4) incorporated into each of the pair of cover members 5 and in which a turn circulation groove on the inner periphery of the turning path C2 is formed. The cover members 5 are attached to both ends of the carriage body 4.

[0019] Figure 2 shows a cross section perpendicular to the rail of the motion guide device 10. The left half of Figure 2 shows a cross section taken along line IIL-IIL in Figure 1 (a front view of the carriage body 4), and the right half of Figure 2 shows a cross section taken along line IIR-IIR in Figure 1 (a front view of the cover member 5).

[0020] As shown in the left half of Figure 2, the carriage body 4 has a center section 4-1 facing the upper surface of the rail 1, and a pair of left and right sleeve sections 4-2 facing the side surfaces of the rail 1. Mounting holes 4b are formed in the upper surface of the carriage body 4 for attaching the carriage 2 to a table or the like. Two upper and lower rolling grooves 4a are formed in each of the left and right sleeve sections 4-2 of the carriage body 4, along which the balls 3 roll. Each rolling groove 4a is a circular arc groove. Each rolling groove 4a may also be a Gothic arch groove.

[0021] 2, reference numeral 11 indicates the contact angle direction of the ball 3, and reference numeral θ° indicates the contact angle. The contact angle θ° is not particularly limited, but is set to, for example, 40° to 60°. A return path C3 is formed in each of the left and right sleeve portions 4-2 of the carriage body 4, parallel to the rolling groove 4a.

[0022] 2 and 3, the cover member 5 has a central portion 5-1 facing the upper surface of the rail 1, and a pair of left and right sleeve portions 5-2 facing the left and right side surfaces of the rail 1. The central portion 5-1 of the cover member 5 is formed with a through-hole 5a (see FIG. 3) through which a fastening member such as a screw passes to attach the cover member 5 to the carriage body 4. The carriage body 4 is formed with a screw hole 4c (see FIG. 2) into which the fastening member screws.

[0023] Two upper and lower turn circulation grooves 12 of the turn path C2 are formed in each of the left and right sleeve portions 5-2 of the cover member 5. These turn circulation grooves 12 form the outer periphery of the turn path C2. The cross-sectional shape of the turn circulation groove 12 is not particularly limited, and may be a Gothic arch groove, for example. The cross-sectional shape of the turn circulation groove 12 may also be a circular arc groove. The inner periphery of the turn path C2 is formed by an R-piece portion 8, which will be described later.

[0024] As shown in FIG. 4 , a recess 5d is formed in each of the left and right sleeves 5-2 of the cover member 5. A roughly semi-cylindrical R-piece portion 8 is provided in this recess 5d as a component of the inner periphery of the turn path. As shown in FIGS. 5( a) and 5(b) , two upper and lower turn circulation grooves 13 of the turn path C2 are formed on the outer periphery of the R-piece portion 8. The turn circulation grooves 13 of the R-piece portion 8 constitute the inner periphery of the turn path C2. The cross-sectional shape of the turn circulation grooves 13 is not particularly limited, and may be, for example, a Gothic arch groove. The cross-sectional shape of the turn circulation groove 13 may also be a circular arc groove. An inner plate (not shown) may be provided on the end surface of the carriage body 4, and the R-piece portion 8 may be formed on the inner plate.

[0025] As shown in Figure 6(a), the ball 3 that has moved along the rolling path C1 is sandwiched between the wall surface 12a of the turn circulation groove 12 of the cover member 5 and the rolling groove 1a of the rail 1. The hatching in Figure 6(a) indicates the end surface of the cover member 5 on the carriage body 4 side. In the cross section of the motion guide device 10 shown in Figure 6(a) perpendicular to the rail, the wall surface 12a of the turn circulation groove 12 of the cover member 5 and the rolling groove 1a of the rail 1 turn the sandwiched ball 3 in the turn trajectory direction A. This turn trajectory direction A is the same as the tangent direction at the start point of the turn circulation groove 12.

[0026] Here, the more the turning track direction A is tilted from the contact angle direction 11 of the ball 3 (see FIG. 2), the further the ball scooping portion 13 (osculating ellipse) of the cover member 5, which the ball 3 hits as it moves along the rolling path C1, can be moved away from the edge 12b of the turning circulation groove 12, as shown in FIG. 7. Therefore, the ball scooping portion 13 can be made thicker, and the contact between the ball scooping portion 13 and the ball 3 can be made to be surface contact. The ball 3 turns without hitting the edge 12b of the turning circulation groove 12. Symbol L is the distance from the edge 5b to the ball scooping portion 13, and symbol 14 is the osculating ellipse between the rolling groove 1a of the rail 1 and the ball 3.

[0027] In order to tilt the turning track direction A significantly from the contact angle direction 11 of the ball 3, as shown in the right half of Figure 2, in a cross section of the motion guide device 10 perpendicular to the rail, the ball 3 on the rolling groove 1a on the upper side of the rail 1 is turned in the turning track direction A1 diagonally downward, and the ball 3 on the rolling groove 1a on the lower side of the rail 1 is turned in the turning track direction A2 diagonally upward.

[0028] As shown in FIG. 6( a), in a cross section of the motion guide device 10 perpendicular to the rail, a sandwiching angle γ° defined by a contact point P1 (the center of the ball scooping portion 13 in FIG. 7) between the wall surface 12a of the turn circulation groove 12 of the cover member 5 and the ball 3, a contact point P2 (the center of the osculating ellipse 14 in FIG. 7) between the rolling groove 1a of the rail 1 and the ball 3, and the center O of the ball 3 is set to be less than 180°. A reaction force F1 acts on the ball 3 from the wall surface 12a of the turn circulation groove 12 of the cover member 5, and a reaction force F2 acts on the ball 3 from the rolling groove 1a of the rail 1. By setting the sandwiching angle γ to be less than 180°, the resultant force of the two reaction forces F1 and F2 can be directed toward the turn track direction A, allowing the ball 3 to move smoothly in the turn track direction A.

[0029] As shown in Figure 6(b), in a cross section perpendicular to the rail of the motion guide device 10, the turning trajectory angle α°, determined by the horizontal line H and the turning trajectory direction A of the ball 3 on the rolling groove 1a of the rail 1, is set as follows: 0°<α°<90°-θ°-β° Here, θ° is the contact angle, and β° is the angle of the effective range of the rolling groove 1a of the rail 1, which is the angle between the contact angle direction 11 and a line 15 connecting the symbol e and the center O of the ball 3. e is the end of the effective range of the rolling groove 1a of the rail 1. The cross-sectional shape of the rolling groove 1a of the rail 1 changes from concave to convex at e.

[0030] By making the turn trajectory angle α° greater than 0°, the ball 3 on the upper rolling groove 1a of the rail 1 can be turned in the diagonally downward turn trajectory direction A1, and the ball 3 on the lower rolling groove 1a of the rail 1 can be turned in the diagonally upward turn trajectory direction A2. By making the turn trajectory angle α° smaller than 90°-θ°-β°, the ball 3 can be turned in the turn trajectory directions A1 and A2 without interfering with the end e of the effective range of the rolling groove 1a of the rail 1. If the turn trajectory angle α° is greater than 90°-θ°-β°, the ball 3 cannot get over the end e of the effective range of the rolling groove 1a of the rail 1.

[0031] 8(a) to 8(d), the ball 3 that has turned in the turn trajectory direction A turns along the upper and lower turn circulation grooves 12. In a plan view of the motion guide device 10, the upper and lower turn circulation grooves 12 are formed in a substantially U-shape, so the upper and lower balls 3 turn while moving toward the back side of the paper of FIGS.

[0032] As shown in the right half of Figure 2, in a cross section perpendicular to the rail of the motion guide device 10, the upper turn circulation groove 12 is curved convexly downward, and the lower turn circulation groove 12 is curved convexly upward. If the upper and lower balls 3 are made to turn linearly in the turn track directions A1 and A2, the upper and lower turn circulation grooves 12 will interfere with each other. By curving the upper turn circulation groove 12 convexly downward and the lower turn circulation groove 12 convexly upward, it is possible to prevent the upper and lower turn circulation grooves 12 from interfering with each other.

[0033] In a cross section of the motion guide device 10 perpendicular to the rail, the turn circulation groove 12 of the cover member 5 is curved, for example, an arc shape with a radius R. The shape of the turn circulation groove 12 is not particularly limited, and may be a shape combining straight lines and curves, or a shape combining multiple arcs with different radii. However, in order to smoothly move the ball 3, it is desirable that the turn circulation groove 12 has a shape that is continuous in the tangential direction. The dashed line in Figure 2 indicates the center line of the turn path C2.

[0034] As shown in Figure 5(c), the turn circulation groove 13 of the R-piece portion 8 is formed in a shape corresponding to the turn circulation groove 12 of the cover member 5. That is, when viewed from the front of the R-piece portion 8, the turn circulation groove 13 of the R-piece portion 8 is curved, for example, an arc shape with a radius R. The shape of the turn circulation groove 13 is not particularly limited and may be a shape combining straight lines and curves, or a shape combining multiple arcs with different radii. However, in order to smoothly move the ball 3, it is desirable that the turn circulation groove 13 have a shape that is continuous in the tangential direction. The dashed line in Figure 5(c) indicates the center line of the turn path C2.

[0035] The effects of the motion guide device 10 of this embodiment will be described below.

[0036] The balls 3 that have moved along the rolling path C1 are sandwiched between the wall surface 12a of the turning circulation groove 12 of the cover member 5 and the rolling groove 1a of the rail 1, and in a cross section of the motion guide device 10 perpendicular to the rail, the balls 3 on the upper rolling groove 1a of the rail 1 are turned diagonally downward, and the balls 3 on the lower rolling groove 1a of the rail 1 are turned diagonally upward, so that the ball scooping portion 13 of the cover member 5 can be made thick, and the balls 3 can come into surface contact with the ball scooping portion 13. In addition, the overall height of the motion guide device 10 can be kept low.

[0037] In a cross section of the motion guide device 10 perpendicular to the rail, the sandwiching angle γ° of the ball 3 is set to less than 180°, so that the ball 3 can be turned smoothly in the turning track direction A.

[0038] In a cross-sectional view of the motion guide device 10 perpendicular to the rail, the turning track angle α° determined by the horizontal line H and the turning track direction A is set to 0°<α°<90°-θ°-β°, so that the ball 3 can be turned in the turning track direction A without interfering with the end e of the effective range of the rolling groove 1a of the rail 1.

[0039] In a cross section perpendicular to the rail of the motion guide device 10, the turn circulation groove 12 on the upper side of the cover member 5 is curved convexly downward, and the turn circulation groove 12 on the lower side of the cover member 5 is curved convexly upward, so that even if the upper and lower balls 3 are turned in the turn track direction A, the upper and lower turn circulation grooves 12 can be prevented from interfering with each other.

[0040] Furthermore, the ball 3 moving along the rolling path C1 is sandwiched between the wall surface 12a of the turn circulation groove 12 of the cover member 5 and the rolling groove 1a of the rail 1, and in a cross section of the motion guide device 10 perpendicular to the rail, the turn circulation groove 12 on the upper side of the cover member 5 is curved convexly downward and the turn circulation groove 12 on the lower side of the cover member 5 is curved convexly upward, so that the turn trajectory direction A of the upper and lower balls 3 can be significantly tilted from the contact angle direction 11 of the ball 3. This allows the ball scooping portion 13 of the cover member 5 to be thick, allowing the ball 3 and the ball scooping portion 13 to come into surface contact. Furthermore, the overall height of the motion guide device 10 can be kept low.

[0041] The present invention is not limited to the above-described embodiment, and can be embodied in other embodiments without departing from the spirit of the present invention.

[0042] In the above embodiment, the ball on the rolling groove on the upper side of the rail is turned diagonally downward, and the ball on the rolling groove on the lower side of the rail is turned diagonally upward, but the ball on the rolling groove on the upper side of the rail may be turned diagonally downward, or the ball on the rolling groove on the lower side of the rail may be turned diagonally upward.

[0043] In the above embodiment, the turn circulation groove on the upper side of the cover member is curved convexly downward, and the turn circulation groove on the lower side of the cover member is curved convexly upward, but the turn circulation groove on the upper side of the cover member may be curved convexly downward, or the turn circulation groove on the lower side of the cover member may be curved convexly upward.

[0044] In the above embodiment, two circulation paths, one above the other, are provided on each of the left and right sides of the motion guide device, but three or more circulation paths, one above the other, may be provided on each of the left and right sides of the motion guide device.

[0045] In the above embodiment, the ball contact structure is a DF contact structure, but the ball contact structure may also be a DB contact structure. A DF contact structure is a structure configured so that the intersection of the contact angle line of the upper ball and the contact angle line of the lower ball intersects on the inside of the rail, while a DB contact structure is a structure configured so that the intersection intersects on the outside of the rail. The contact angle line is a line connecting the contact point between the ball and the rolling groove of the rail and the contact point between the ball and the rolling groove of the rail.

[0046] In the above embodiment, an outer block type motion guide device in which a carriage with a U-shaped cross section straddles a rail has been described, but an inner block type motion guide device in which a carriage is incorporated into a rail with a U-shaped cross section may also be used.

[0047] This specification is based on Japanese Patent Application No. 2023-164688, filed September 27, 2023, the entire contents of which are incorporated herein by reference.

[0048] 1...rail, 1a...rolling groove, 2...carriage, 3...ball, 4...carriage body, 4a...rolling groove, 5...lid member, 7...circulation path, 10...motion guide device, 12...turn circulation groove, 12a...wall surface of turn circulation groove, A...turn track direction, A1...diagonally downward direction, A2...diagonally upward direction, C1...rolling path, C2...turn path, C3...return path, α°...turn track angle, γ°...ball clamping angle

Claims

1. A motion guiding device comprising: a rail having a rolling groove; a carriage having a rolling groove, a return path, and a turning path; and a plurality of balls arranged in a circulation path including the rolling path between the rolling groove of the rail and the rolling groove of the carriage, the return path, and the turning path, wherein the carriage comprises a carriage body in which the rolling groove is formed, and a cover member in which a turn circulation groove of the turning path is formed, wherein at least two circulation paths are provided above and below each of the left and right sides of the motion guiding device, the balls that have moved along the rolling paths are sandwiched between the wall surface of the turn circulation groove of the cover member and the rolling groove of the rail, and when viewed in a cross section perpendicular to the rail of the motion guiding device, the balls on the upper rolling groove of the rail turn diagonally downward and / or the balls on the lower rolling groove of the rail turn diagonally upward.

2. The motion guide device as described in claim 1, characterized in that, when viewed in a cross section perpendicular to the rail of the motion guide device, the ball clamping angle determined by the contact point between the wall surface of the turn circulation groove of the cover member and the ball, the contact point between the rolling groove of the rail and the ball, and the center of the ball is set to less than 180°.

3. The motion guide device according to claim 1 or 2, characterized in that, in a perpendicular cross section of the rail of said motion guide device, the turning track angle α° determined by the horizontal line and the turning track direction of the ball on the rolling groove of said rail is set as follows: 0°<α°<90°-θ°-β°, where θ° is the contact angle and β° is the angle of the effective range of the rolling groove of said rail.

4. A motion guide device as described in claim 1 or 2, characterized in that, when viewed in a cross-sectional view perpendicular to the rail of the motion guide device, the turn circulation groove on the upper side of the cover member is curved convexly downward, and / or the turn circulation groove on the lower side of the cover member is curved convexly upward.

5. A motion guiding device comprising: a rail having a rolling groove; a carriage having a rolling groove, a return path and a turning path; and a plurality of balls arranged in a circulation path including a rolling path between the rolling groove of the rail and the rolling groove of the carriage, the return path and the turning path, wherein the carriage comprises a carriage body in which the rolling groove is formed, and a cover member in which a turn circulation groove of the turning path is formed, wherein at least two circulation paths are provided above and below each of the left and right sides of the motion guiding device, wherein a ball that has moved along the rolling path is sandwiched between a wall surface of the turn circulation groove of the cover member and the rolling groove of the rail, and when viewed in a cross section perpendicular to the rail of the motion guiding device, the turn circulation groove on the upper side of the cover member is curved convex downward and / or the turn circulation groove on the lower side of the cover member is curved convex upward.

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