Motion guide device

Abstract

To provide a motion guide device capable of preventing a ball on one ball passage part from passing a ball on the other ball passage part in a return path and / or a turn path of the motion guide device.SOLUTION: A return path C2 and / or a turn path has two ball passage parts 21, 22 neighboring each other where two-row balls 6 are arranged in a zigzag manner. The two ball passage parts 21, 22 are formed so as to prevent the ball 6 in one ball passage part 21 to transfer into the other ball passage part 22, and to cause the ball 6 in one ball passage part 21 and the ball 6 in the other ball passage part 22 to overlap each other even if one separates from the other in view from the moving direction of the two-row balls 6.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a motion guide device that guides the linear motion of a movable body. [Background technology]

[0002] The motion guide device includes a track member and a carriage that is mounted on the track member via a number of balls to enable linear motion (straight-line motion or curved motion). The track member is attached to a fixed body such as a base. The carriage is attached to a movable body such as a table. The linear motion of the movable body relative to the fixed body is guided by the motion guide device.

[0003] The track member is formed with a rolling portion along which the balls roll. The carriage is also formed with a rolling portion along which the balls roll. The carriage is provided with a circulation path for circulating the balls. The circulation path includes a rolling path between the rolling portion of the track member and the rolling portion of the carriage, and a turn path and a return path provided in the carriage. When the carriage makes linear motion along the track member, the balls roll on the rolling path and circulate in the circulation path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-343556 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to reduce waving (reducing vibration caused by ball passage) in a motion guide device, two rows of balls are sometimes arranged in a staggered pattern in the circulation path. By having the two rows of balls alternately enter and exit the rolling path, it is possible to reduce waving.

[0006] If the two rows of balls are held by a retainer band, the two rows of balls can be arranged in a staggered pattern. However, if the two rows of balls are not held by a retainer band, the two rows of balls cannot be arranged in a staggered pattern. This causes a problem that, in the return path and / or turning path, of two adjacent ball passing sections, the balls in one ball passing section overtake the balls in the other ball passing section, making it difficult to obtain a motion guide device with smooth movement. This is because, in conventional motion guide devices, the radius of each of the two ball passing sections is set to about 55% of the ball diameter, allowing the balls to move freely within the gaps around them.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a motion guide device that can prevent a ball in one ball passing section from overtaking a ball in another ball passing section on the return path and / or turning path of the motion guide device. [Means for solving the problem]

[0008] In order to solve the above problems, one aspect of the present invention is a motion guide device comprising: a track member having a rolling part; a carriage having a rolling part opposite to the rolling part, a return path, and a turning path; and two rows of balls arranged in a circulation path including the rolling path between the rolling part of the track member and the rolling part of the carriage, the return path, and the turning path, wherein the two rows of balls are not held by a retainer band, the return path and / or the turning path have two adjacent ball passing parts in which the two rows of balls are arranged in a staggered manner, and the two ball passing parts are formed so as to prevent balls in one ball passing part from transferring to the other ball passing part, and so that the balls in one ball passing part and the balls in the other ball passing part overlap even if they are separated when viewed in the direction of travel of the two rows of balls. Effect of the Invention

[0009] According to the present invention, a ball in one ball passing section can be prevented from overtaking a ball in the other ball passing section on the return path and / or the turning path of the motion guide device. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view (including a partial cross-sectional view) of a motion guide device according to one embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view of the motion guide device of the present embodiment perpendicular to the relative movement direction of the carriage. FIG. [Diagram 3] FIG. 3(a) is an enlarged view of the return path of this embodiment, and FIG. 3(b) is an enlarged view of the return path of a comparative example. [Figure 4] FIG. 4(a) is a perspective view of a first half pipe of this embodiment, and FIG. 4(b) is a perspective view of a second half pipe of this embodiment. [Diagram 5] FIG. 5(a) is an enlarged view of the first modified example of the return path, and FIG. 5(b) is an enlarged view of the second modified example of the return path. [Figure 6] FIG. 6(a) is an enlarged view of the third modified example of the return path, and FIG. 6(b) is an enlarged view of the fourth modified example of the return path. [Figure 7] FIG. 7(a) is a perspective view of an inner plate of this embodiment, and FIG. 7(b) is a perspective view of an end plate of this embodiment. [Figure 8] FIG. 2 is a cross-sectional view of a turning road according to the present embodiment. [Figure 9] FIG. 9(a) is a diagram showing the turning path of this embodiment as viewed from the relative movement direction of the carriage, and FIG. 9(b) is a diagram showing the turning path of a comparative example. [Figure 10] 10(a) and (b) are schematic diagrams for explaining why the staggered arrangement is destroyed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a motion guide device according to an embodiment of the present invention will be described with reference to the accompanying drawings. However, the motion guide device according to the present invention can be embodied in various forms and is not limited to the embodiments described in this specification. The present embodiment is provided with the intention of enabling a person skilled in the art to fully understand the invention by fully disclosing the specification.

[0012] Fig. 1 is a perspective view of a motion guide device according to one embodiment of the present invention. Fig. 2 is a cross-sectional view of the motion guide device perpendicular to the relative movement direction of the carriage 2. In the following explanation, for convenience of explanation, the configuration of the motion guide device will be explained using the directions when the motion guide device arranged on a horizontal plane is viewed from the relative movement direction of the carriage 2, that is, the up / down, left / right, and front / back in Figs. 1 and 2. Of course, the arrangement of the motion guide device is not limited to this.

[0013] As shown in FIG. 1, the motion guide device includes a track member 1 and a carriage 2. The track member 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 can move linearly along the track member 1. A large number of balls 6 are interposed between the track member 1 and the carriage 2. The carriage 2 is provided with a circulation path 7 for circulating the large number of balls 6. There are, for example, four circulation paths 7 in total, which are provided on the left and right, top and bottom of the carriage 2 (see FIG. 2). Each circulation path 7 includes a rolling path C1 between the rolling part 12 of the track member 1 and the rolling part 13 of the carriage 2, a return path C2 and a turn path C3 provided on the carriage 2. Two rows of balls 6 are arranged in the circulation path 7. The two rows of balls 6 are not held by a retainer band. In the rolling path C1, the two rows of balls 6 roll while receiving a load. On the return path C2 and the turn path C3, the balls 6 in the two rows move while being pushed by the following balls 6.

[0014] The track member 1 is rail-shaped. The track member 1 has, for example, four rolling portions 12 formed thereon. On the left and right sides of the upper part of the track member 1, ridges 11 are formed protruding in the left-right direction. The rolling portions 12 are formed above and below the ridges 11 so as to sandwich the ridges 11. The rolling portions 12 have two rolling grooves 1a in which two rows of balls 6 roll. The rolling grooves 1a are circular arc grooves whose cross section is, for example, a single circular arc. The track member 1 has mounting holes 1b for mounting the track member 1 to a base or the like.

[0015] The carriage 2 includes a carriage body 3, an inner plate 4 attached to both end surfaces of the carriage body 3, and an end plate 5 attached to both end surfaces of the carriage body 3 so as to cover the inner plate 4. A return path C2 is provided in the carriage body 3. A U-shaped return path C3 is formed between the inner plate 4 and the end plate 5.

[0016] 2, the carriage body 3 has a central portion 3a facing the upper surface of the track member 1, and left and right sleeve portions 3b facing the side surfaces of the track member 1. The sleeve portions 3b of the carriage body 3 are formed with rolling portions 13 facing the rolling portions 12 of the track member 1. The rolling portion 13 has two rolling grooves 3c in which two rows of balls 6 roll. The rolling groove 3c is, for example, a circular arc groove whose cross section is a single arc.

[0017] A linear rolling path C1 is formed between the rolling part 13 of the carriage body 3 and the rolling part 12 of the track member 1. Two rows of balls 6 are arranged in a staggered manner in the rolling path C1. The two rows of balls 6 overlap when viewed from the direction of travel. In the rolling path C1, the balls 6 roll while receiving a load.

[0018] Through holes 14 are formed parallel to the rolling path C1 above and below the left and right sleeves 3b of the carriage body 3. The first half pipe 8 and the second half pipe 9 are inserted into the through holes 14. The return path C2 is formed between the first half pipe 8 and the second half pipe 9. The return path C2 is linear and parallel to the rolling path C1.

[0019] FIG. 3(a) shows an enlarged view of the return path C2 of this embodiment. FIG. 3(b) shows an enlarged view of the return path C2' of the comparative example. As shown in FIG. 3(a), two rows of balls 6 are arranged in a staggered pattern in two adjacent ball passing sections 21, 22 of the return path C2 of this embodiment. The ball passing sections 21, 22 are formed so as to prevent the ball 6 of one ball passing section 21 from transferring to the other ball passing section 22, and so as to overlap the ball 6 of one ball passing section 21 and the ball 6 of the other ball passing section 22 even if they are separated from each other, as viewed from the traveling direction of the two rows of balls 6. That is, as shown in FIG. 3(a), the balls 6 are formed so as to overlap each other even if they are separated from each other in the row direction and the direction perpendicular to the row.

[0020] The ball passing portions 21 and 22 are gourd-shaped with a depression in the center in the row direction, and have arc portions 21a, 21b, 22a, and 22b based on two overlapping circles. The arc portions 21a and 21b are located on one circle, and the arc portions 22a and 22b are located on the other circle. The radius R of the arc portions 21a, 21b, 22a, and 22b is set to 54% to 56% Da. Here, Da is the diameter of the ball 6.

[0021] The ball passing portions 21, 22 have limiting portions 21c, 22c (hereinafter referred to as side walls 21c, 22c) that limit the separation of the balls 6 from each other. The distance L between the side walls 21c, 22c is set to less than 2Da. The side walls 21c, 22c are flat. The side walls 21c, 22c are parallel to each other. The side walls 21c, 22c are formed only on the first half pipe 8.

[0022] FIG. 3(b) shows an enlarged view of the return path C2' of the comparative example. In the return path C2' of the comparative example, two rows of balls 6' are arranged in a staggered pattern in two adjacent ball passing sections 21', 22' of the return path C2'. The ball passing sections 21', 22' are gourd-shaped with a recessed center in the row direction, and have arc sections 21a', 21b', 22a', 22b' based on two overlapping circles. The radius of the arc sections 21a', 21b', 22a', 22b' is set to 55% Da. In the comparative example, since the side walls 21c, 22c do not exist, when the balls 6' move away from each other, they do not overlap each other. If they do not overlap, the balls 6' of one ball passing section 21' will overtake the balls 6' of the other ball passing section 22', and the staggered arrangement will be destroyed.

[0023] FIG. 4(a) shows a perspective view of the first half pipe 8. The first half pipe 8 has arcuate portions 21a, 22a. A protruding portion 8a that protrudes toward the second half pipe 9 is formed at the circumferential end of the first half pipe 8. The protruding portion 8a abuts against the second half pipe 9. Side walls 21c, 22c are formed on the inner surface of the protruding portion 8a. Positioning protrusions 8b that protrude in the axial direction are formed on both axial end faces of the first half pipe 8. The positioning protrusions 8b fit into recesses in the inner plate 4, thereby positioning the first half pipe 8 on the inner plate 4.

[0024] As shown in Fig. 4(b), arc portions 21b and 22b are formed on the second half pipe 9. Positioning protrusions 9a are formed on both axial end surfaces of the second half pipe 9. The second half pipe 9 is positioned on the end plate 5 by fitting the positioning protrusions 9a into recesses 29 (see Fig. 7(b)) of the end plate 5.

[0025] Fig. 5(a) shows another example (variation 1) of the return path C2. In this example, grooves 23 filled with lubricant are formed at the bottoms of the arcuate portions 21a, 21b, 22a, and 22b of the ball passing portions 21 and 22. The other configurations are the same as those of the return path C2 shown in Fig. 3(a), so the same reference numerals are used and the description thereof is omitted.

[0026] Fig. 5(b) shows yet another example (variation 2) of the return path C2. In this example, the radius of the arcuate portions 21a, 21b, 22a, and 22b of the ball passage portions 21 and 22 is set to 51.5% to 53.5% Da. The other configurations are the same as those of the return path C2 shown in Fig. 3(a), so the same reference numerals are used and the description thereof is omitted.

[0027] 6(a) shows yet another example (Modification 3) of the return path C2. In this example, the side walls 21c, 22c are not provided, and the ball passage parts 21, 22 have only the arcuate parts 21a, 21b, 22a, 22b. The radius of the arcuate parts 21a, 21b, 22a, 22b is set to 51.5% to 53.5% Da. The mating surface 24 of the first half pipe 8 and the second half pipe 9 is disposed on the center line of the two balls 6.

[0028] 6(b) shows yet another example (Modification 4) of the return path C2. In this example, the side walls 21c and 22c are not provided, and the ball passage portions 21 and 22 only have the arcuate portions 21a, 21b, 22a and 22b. The radius of the arcuate portions 21a, 21b, 22a and 22b is set to 51.5% to 53.5% Da. The first half pipe 8 and the second half pipe 9 are separated from each other.

[0029] In these modified examples 1 to 4, the ball passing portions 21, 22 are formed so as to prevent the ball 6 in one ball passing portion 21 from transferring to the other ball passing portion 22, and so as to overlap the ball 6 in one ball passing portion 21 and the ball 6 in the other ball passing portion 22 even if they are separated, when viewed from the direction of travel of the two rows of balls 6.

[0030] 7(a) shows a perspective view of the inner plate 4. The inner plate 4 has a central portion 4a facing the upper surface of the track member 1, and a pair of left and right sleeve portions 4b facing the side surfaces of the track member 1. Above and below the left and right sleeve portions 4b of the inner plate 4, R piece portions 31 having a roughly semi-cylindrical shape are formed.

[0031] FIG. 7(b) shows a perspective view of the end plate 5. The end plate 5 has a central portion 5a facing the upper surface of the track member 1, and a pair of left and right sleeve portions 5b facing the side surfaces of the track member 1. Recesses 32 into which the R piece portion 31 fits are formed above and below the left and right sleeve portions 5b of the end plate 5. A substantially U-shaped turning path C3 is formed between the R piece portion 31 of the inner plate 4 and the recesses 32 of the end plate 5, which are combined with each other. The inner plate 4 and the end plate 5 are attached to the carriage body 3 by screws. Through holes 37 and 38 for screws are formed in the inner plate 4 and the end plate 5.

[0032] 8 shows a cross-sectional view of the turning path C3. Reference numeral 4 denotes an inner plate, and reference numeral 5 denotes an end plate. The turning path C3 has two adjacent ball passing portions 21, 22 in which two rows of balls 6 are arranged in a staggered pattern. The cross-sectional shapes of the ball passing portions 21, 22 of the turning path C3 are substantially the same as the cross-sectional shapes of the ball passing portions 21, 22 of the returning path C2. The ball passing portions 21, 22 are formed so as to prevent the balls 6 of one ball passing portion 21 from transferring onto the other ball passing portion 22, and so as to overlap the balls 6 of one ball passing portion 21 and the balls 6 of the other ball passing portion 22 even if they are separated, as viewed from the traveling direction of the two rows of balls 6.

[0033] In a cross section perpendicular to the traveling direction of the two rows of balls 6, the ball passing portions 21, 22 are gourd-shaped with a recessed center in the row direction, and have arc portions 21a, 21b, 22a, 22b based on two overlapping circles. The radius of the arc portions 21a, 21b, 22a, 22b is set to 54% to 56% Da. The arc portions 21a, 22a are formed on the outer periphery of the R piece portion 31 of the inner plate 4 (see FIG. 7(a)). The arc portions 21b, 22b are formed in the recesses 32 of the end plate 5 (see FIG. 7(b)).

[0034] The ball passing portions 21 and 22 have flat side walls 21c and 22c that limit the separation of the balls 6. The distance between the side walls 21c and 22c is set to be less than 2Da. The side walls 21c and 22c are formed only on the end plates 5.

[0035] Fig. 9(a) shows the turning path C3 as seen from the relative movement direction of the carriage 2. In Fig. 9(a), the end plate 5 has been removed to show the ball 6 in the turning path C3. Reference numeral 1 denotes a rail, and reference numeral 4 denotes an inner plate.

[0036] In this embodiment, on the turning path C3, the balls 6 in one ball passing portion 21 and the balls 6 in the other ball passing portion 22 always overlap. This makes it possible to prevent the balls 6 in one ball passing portion 21 from overtaking the balls 6 in the other ball passing portion 22, thereby maintaining the staggered arrangement of the balls 6. The same is true on the return path C2.

[0037] The balls 6 in the unloaded area (turn path C3 and return path C2) move forward by being pushed by the balls 6 coming out of the loaded area (rolling path C1). By maintaining the staggered arrangement as described above, in the turn path C3 and return path C2, the balls 6 in the ball passing portion 21 come into contact with the balls 6 before and after the same ball passing portion 21, and are pushed by the balls 6 in the same ball passing portion 21. The same is true for the ball passing portion 22. This enables smooth force transmission between the balls 6.

[0038] 9(b) shows a comparative example in which the staggered arrangement is broken. When the staggered arrangement is broken, the ball 6a of the ball passing portion 21 pushes the ball 6b of the adjacent ball passing portion 22, and the ball 6c of the further ball passing portion 22 pushes the ball 6d of the adjacent ball passing portion 21. This reduces the efficiency of force transmission, and the ball 6 cannot move smoothly.

[0039] Figures 10(a) and 10(b) are schematic diagrams for explaining the cause of the collapse of the staggered arrangement. As shown in Figure 10(a), if the balls 6 in one ball passing section 21 and the balls 6 in the other ball passing section 22 do not overlap when viewed from the moving direction of the two rows of balls 6, for example, the balls 6 in the ball passing section 21 shown with diagonal lines in Figure 10(a) can move leftward in the figure relative to the balls 6 in the ball passing section 22. The balls 6 in the ball passing section 21 can overtake the balls 6 in the ball passing section 22. This causes the collapse of the staggered arrangement as shown in Figure 10(b). The effects of the motion guide device of this embodiment will be described below.

[0040] Since the balls 6 overlap each other on the return path C2 and the turn path C3, it is possible to prevent the ball 6 in one ball passing portion 21 from overtaking the ball 6 in the other ball passing portion 22. Therefore, it is possible to maintain the staggered arrangement of the balls 6 on the return path C2 and the turn path C3.

[0041] The ball passing parts 21, 22 are provided with flat side walls 21c, 22c for restricting the balls 6 from moving apart, and the distance between the side walls 21c, 22c is set to less than 2Da, so that the balls 6 can overlap each other while having some leeway in their movement.

[0042] Since the ball passing portions 21 and 22 have the arcuate portions 21a, 21b, 22a and 22b with radii of 54% to 56% Da, the ball 6 can have some leeway in its movement.

[0043] Since the ball passing portions 21, 22 have the arcuate portions 21a, 21b, 22a, 22b with radii of 51.5% to 53.5% Da, the balls 6 can overlap each other without providing the side walls 21c, 22c.

[0044] Since the side walls 21c, 22c are formed only on the first half pipe 8, the ball 6 can be prevented from contacting the joint between the first half pipe 8 and the second half pipe 9.

[0045] Since the side walls 21c, 22c are formed only on the end plate 5, the ball 6 can be prevented from contacting the joint between the inner plate 4 and the end plate 5.

[0046] It should be noted that the present invention is not limited to the above-described embodiment, and can be embodied in other embodiments without departing from the spirit and scope of the present invention.

[0047] For example, in the above embodiment, the balls are arranged to overlap on the return path and the turn path, but the balls may be arranged to overlap on either the return path or the turn path.

[0048] The side wall may be formed only on the second half pipe, or the side wall may be formed only on the inner plate. [Explanation of symbols]

[0049] 1...track member, 2...carriage, 4...inner plate, 5...end plate, 6...ball, 7...circulation path, 8...first half pipe, 9...second half pipe, 12...rolling portion of track member, 13...rolling portion of carriage, 21, 22...ball passing portion, 21a, 21b, 22a, 22b...arc portion, 21c, 22c...side wall (restriction portion), C1...rolling path, C2...return path, C3...turn path, L...distance between side walls, R...radius of arc portion

Claims

1. A raceway member having a rolling portion; a carriage having a rolling portion opposite to the rolling portion, a return path, and a turning path; a rolling path between the rolling portion of the track member and the rolling portion of the carriage, a return path, and a circulating path including the turn path; The two rows of balls are not retained by a retainer band; the return path and / or the turn path has two adjacent ball passing portions in which the two rows of balls are arranged in a staggered manner, The two ball passing sections are formed so as to prevent a ball from one ball passing section from transferring onto the other ball passing section, and so as to overlap even if a ball from one ball passing section and a ball from the other ball passing section are separated from each other as viewed from the traveling direction of the two rows of balls.

2. The two ball passing portions each have a limiting portion that limits separation between a ball in one ball passing portion and a ball in the other ball passing portion, The motion guide device according to claim 1 , wherein the distance between the limiting portions is set to less than 2Da. where Da is the ball diameter.

3. the two ball passing portions have arc portions based on two circles which overlap each other in a cross section perpendicular to the traveling direction of the two rows of balls, 3. The motion guide device according to claim 2, wherein the radius of the arc portion is set to 54% to 56% Da. where Da is the ball diameter.

4. the two ball passing portions have arc portions based on two circles which overlap each other in a cross section perpendicular to the traveling direction of the two rows of balls, 3. The motion guide device according to claim 1, wherein the radius of the arc portion is set to 51.5% to 53.5% Da. where Da is the ball diameter.

5. The return path is formed between the first half pipe and the second half pipe, 4. The motion guide device according to claim 2, wherein the limiting portion is formed only on the first half pipe or only on the second half pipe.

6. The turning path is formed between an inner plate and an end plate, 4. The motion guide device according to claim 2, wherein the limiting portion is formed only on the end plate or only on the inner plate.

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