Motion guidance device

Abstract

In a motion guidance device in which two rows of balls are arranged in a staggered pattern along a circulation path, the present invention provides a motion guidance device that allows for miniaturization of the carriage and improvement of the durability of the retainer. [Solution] A retainer 71 is provided in which two rows of balls 6 are arranged in a staggered pattern in a circulation path including a rolling path C1, a return path C2, and a turn path C3. When viewed from a direction perpendicular to the plane containing the rolling path C1 and the return path C2 (see Figure 7(a)), at the ends of the turn path C3 on the rolling path C1 side and the end on the return path C2 side, the first turn path 21 for the first row of balls is positioned outside the second turn path 22 for the second row of balls, and at the top of the turn path C3, the first turn path 21 is positioned inside the second turn path 22. The retainer 71 comprises a center band 72 between the two rows of balls 6 and two side bands 73 outside the two rows of balls 6. When viewed along the length of the retainer 71, the two rows of balls 6 are spaced apart.

Description

Technical Field

[0001] The present invention relates to a motion guiding device in which two rows of balls are arranged in a staggered pattern in a circulation path.

Background Art

[0002] There is known a motion guiding device that guides a movable body such as a table to perform linear or curvilinear motion with respect to a base. The motion guiding device includes a guide rail and a carriage that moves relative to the guide rail. A plurality of balls are interposed between the guide rail and the carriage so as to be capable of rolling. The balls circulate in a circulation path including a rolling path between the guide rail and the carriage, a return path of the carriage, and a turning path of the carriage.

[0003] A motion guiding device in which two rows of balls are arranged in a staggered pattern in a circulation path has been proposed (see Patent Document 1). According to this motion guiding device, the number of effective balls can be increased, and since the two rows of balls alternately enter and exit the rolling path, the waving (ball passing vibration) of the carriage can be reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional motion guiding device, there is a problem that the carriage tends to be large-sized. If the outer dimensions of the carriage do not conform to the ISO dimensions, it cannot be replaced with other motion guiding devices that conform to the ISO dimensions.

[0006] Also, when two rows of balls arranged in a staggered pattern are held by a retainer, the elastic deformation of the retainer is forced in the turning path, so there is a problem with the durability of the retainer.

[0007] The present invention has been made in view of the above problems, and aims to provide a motion guidance device in which two rows of balls are arranged in a staggered pattern in a circulation path, which can reduce the size of the carriage and improve the durability of the retainer. [Means for solving the problem]

[0008] To solve the above problems, one aspect of the present invention provides a motion guide device comprising a guide rail having a rolling portion, and a carriage having a rolling portion facing the rolling portion, a return path, and a turn path, wherein at least one retainer is provided in a circulation path including the rolling path, the return path, and the turn path between the rolling portion of the guide rail and the rolling portion of the carriage, and two rows of balls are arranged in a staggered pattern, and when viewed from a direction perpendicular to the plane including the rolling path and the return path, the first turn path for the first row of balls is positioned outside the second turn path for the second row of balls at the rolling path side end and the return path side end of the turn path, and the first turn path is positioned inside the second turn path at the top of the turn path, and the retainer comprises a center band between the two rows of balls and two side bands outside the two rows of balls, and the two rows of balls are separated when viewed in the longitudinal direction of the retainer. [Effects of the Invention]

[0009] According to the present invention, by forming the turn path in the shape described above, the degree of freedom in the layout of the rolling path and return path connected to the turn path can be increased. As a result, the carriage can be made smaller. In addition, by using a three-band configuration (center band and two side bands), two rows of balls can be held, and since the two rows of balls are spaced apart when viewed from the length direction of the retainer, the width of the center band can be secured and its strength increased. As a result, the durability of the retainer can be improved. [Brief explanation of the drawing]

[0010] [Figure 1]This is a perspective view (including a partial cross-sectional view) of a motion guidance device according to an embodiment of the present invention. [Figure 2] This is a right-angle cross-sectional view of the guide rail of a motion guidance device according to an embodiment of the present invention. [Figure 3] Figure 3(a) is an enlarged cross-sectional view of the rolling path, Figure 3(b) is an enlarged cross-sectional view of the return path, and Figure 3(c) is an enlarged cross-sectional view of the top of the turn path. [Figure 4] This is a perspective view of the inner plate. [Figure 5] This is a perspective view of the end plate. [Figure 6] Figure 6(a) is a perspective view of the turn path in the upper left of Figure 2, and Figure 6(b) shows the trajectories of the first and second balls as seen from the same direction as in Figure 6(a). [Figure 7] Figure 7(a) is a plan view of the turnaway as seen from the direction of arrow A in Figure 6(a), Figure 7(b) is a front view of the turnaway, and Figure 7(c) is a side view of the turnaway. [Figure 8] Figures 8(a), 8(b), and 8(c) show the trajectories of the first and second balls, viewed from the same direction as in Figures 7(a), 8(b), and 8(c). [Figure 9] This diagram illustrates how the trajectories of the first and second balls are formed. [Figure 10] This is a perspective view of a retainer with two rows of balls arranged in a staggered pattern. [Figure 11] Figure 11(a) is a side view of the retainer, and Figure 11(b) is a bottom view of the retainer. [Figure 12] Figure 12(a) is an enlarged view of a portion of Figure 11(a), and Figure 12(b) is an enlarged view of a portion of Figure 11(b). [Figure 13] Figure 13(a) is a front view of the retainer, and Figure 13(b) is a cross-sectional view of Figure 11(a). [Figure 14] This diagram shows an example where five retainers are installed in the circulation path. [Figure 15] This diagram shows an example where two rows of spacer balls are arranged in a staggered pattern on the front and rear retainers in the direction of travel. [Modes for carrying out the invention]

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

[0012] In the following description, for the sake of convenience of explanation, the direction when viewing the motion guiding device arranged on the horizontal plane from the relative movement direction of the carriage, that is, the up and down, left and right, front and back in FIGS. 1 and 2, will be used to describe the configuration of the motion guiding device. Of course, the arrangement of the motion guiding device is not limited to this.

[0013] As shown in FIG. 1, the motion guiding device includes a guide rail 1 and a carriage 2 that can move relative to the guide rail 1. The motion guiding device is used to guide the linear or curvilinear motion of a movable body such as a table. The guide rail 1 is attached to a base or the like not shown. The carriage 2 is attached to a movable body such as a table not shown.

[0014] On the upper part of the guide rail 1, two ridges 11 protruding in the left and right directions are formed. Two rolling parts 12 are formed on each ridge 11 in the up and down directions. Each rolling part 12 has two parallel rolling grooves 1a. Two rows of balls 6 roll in these two rolling grooves 1a. Each rolling groove 1a is a circular arc groove with a cross-section, for example, a single circular arc. The guide rail 1 has mounting holes 1b for attaching the guide rail 1 to a base or the like.

[0015] On the upper and lower sides of both the left and right sides of the carriage 2, for example, four circulation paths 7 for circulating the balls 6 are provided. In FIG. 1, two circulation paths 7 on the right side are shown. Each circulation path 7 includes a linear rolling path C1 between the rolling part 12 of the guide rail 1 and the rolling part 13 of the carriage 2, a return path C2 parallel to the rolling path C1, and a substantially U-shaped turn path C3 connected to the rolling path C1 and the return path C2. The return path C2 and the turn path C3 are provided on the carriage 2.

[0016] At least one, for example, three or more, preferably four or more retainers 71 in which two rows of balls 6 are arranged staggeredly are provided in the circulation path 7. In the rolling path C1, two rows of balls 6 roll while receiving a load. The retainer 71 moves together with the two rows of balls 6. In the turn path C3 and the return path C2, the retainer 71 moves while being pushed by the subsequent retainer 71.

[0017] The carriage 2 includes a carriage body 3, inner plates 4 attached to both end faces of the carriage body 3, and end plates 5 attached to cover the inner plates 4 on both end faces of the carriage body 3. The carriage body 3 is provided with a rolling part 13 and a return path C2. The inner plates 4 and the end plates 5 are provided with a turn path C3.

[0018] As shown in the cross-sectional view of FIG. 2, the carriage body 3 is substantially U-shaped and has a central part 3a facing the upper surface of the guide rail 1 and left and right sleeve parts 3b facing the left and right side surfaces of the guide rail 1. Rolling parts 13 facing the rolling part 12 of the guide rail 1 are formed above and below the left and right sleeve parts 3b.

[0019] As shown in the enlarged cross-sectional view of the rolling path C1 in Figure 3(a), the rolling section 13 has two parallel rolling grooves 3c on which two rows of balls 6 roll. Each rolling groove 3c is a circular arc groove with a cross-section of, for example, a single circular arc. The rolling path C1 is formed between the rolling section 13 of the carriage body 3 and the rolling section 12 of the guide rail 1. The rolling path C1 comprises a first rolling path 21 for the first row of balls 6 and a second rolling path 22 for the second row of balls 6. Viewed from the longitudinal direction of the rolling path C1, the second row of balls 6 is separated. The sign θ in Figure 2 is the contact angle representing the direction in which the two rows of balls 6 are subjected to load. The contact angle θ is set to, for example, 30 to 60°.

[0020] As shown in Figure 2, through holes 14 are formed parallel to the rolling parts at the top and bottom of the left and right sleeve portions 3b of the carriage body 3. A pipe 8 is inserted into the through holes 14. A return path C2 is formed inside the pipe 8. The upper return path C2 is positioned below the contact angle line N1 of the upper ball 6. The lower return path C2 is positioned above the contact angle line N2 of the lower ball 6.

[0021] As shown in the enlarged cross-sectional view of the return passage C2 in Figure 3(b), the return passage C2 comprises a first return passage 21 for the first row of balls 6 and a second return passage 22 for the second row of balls 6. There is a gap between the first return passage 21 and the balls 6, and a gap between the second return passage 22 and the balls 6. A groove 10 is formed in the return passage C2 into which the side band 73 of the retainer 71 fits.

[0022] As shown in Figure 4, the inner plate 4 is roughly U-shaped and has a central portion 4a facing the upper surface of the guide rail 1 and left and right sleeve portions 4b facing the left and right sides of the guide rail 1. R-piece portions 31 that are roughly semi-cylindrical are provided above and below the left and right sleeve portions 4b of the inner plate 4. Two inner turn grooves 31a that constitute the inner circumference of the turn path C3 are formed on the outer circumference of the R-piece portion 31.

[0023] In Figure 4, reference numeral 31d indicates the end of the inner circumferential turn groove 31a on the return path C2 side. Reference numeral 31c indicates the end of the inner circumferential turn groove 31a on the rolling path C1 side. Reference numeral 31b indicates the transition portion of the guide rail 1 facing the rolling portion 12.

[0024] As shown in Figure 5, the end plate 5 is also roughly U-shaped and has a central portion 5a facing the upper surface of the guide rail 1 and left and right sleeve portions 5b facing the left and right sides of the guide rail 1. Recesses 32 into which the R piece portion 31 is fitted are formed on the upper and lower parts of the left and right sleeve portions 5b of the end plate 5. Two outer peripheral turn grooves 32a that constitute the outer peripheral side of the turn path C3 are formed in the recesses 32. The end plate 5 and the inner plate 4 are fixed to the carriage body 3, for example, by screws. Through holes 37 and 38 for screws are formed in the end plate 5 and the inner plate 4.

[0025] As shown in the enlarged cross-sectional view of the top of the turn path C3 in Figure 3(c), the inner plate 4 has two inner circumferential turn grooves 31a. The end plate 5 has two outer circumferential turn grooves 32a. The inner plate 4 and the end plate 5 have grooves 30 into which the retainer's side band fits. The turn path C3 includes a first turn path 21 for the first row of balls 6 and a second turn path 22 for the second row of balls 6. There is a gap between the first turn path 21 and the balls 6, and a gap between the second turn path 22 and the balls 6.

[0026] The shape of the turn path C3 is described below. Figure 6(a) shows a perspective view of the turn path C3 in the upper left of Figure 2. Reference numeral 1 denotes the guide rail, reference numeral 4 denotes the inner plate, and reference numeral C3 denotes the turn path. As described above, the turn path C3 comprises a first turn path 21 for the first row of balls 6 and a second turn path 22 for the second row of balls 6.

[0027] Figure 6(b) shows the trajectory of the center of the first row of balls 6 (first ball trajectory 41) and the trajectory of the center of the second row of balls 6 (second ball trajectory 42), viewed from the same direction as in Figure 6(a). The first ball trajectory 41 and the second ball trajectory 42 are three-dimensional curves.

[0028] Figure 7(a) shows a plan view of the turn path C3 as seen from direction A perpendicular to plane P (plane P containing the centers of the turn path C1 and the return path C2 shown in Figure 2), which includes the turning path C1 and the return path C2. Figure 7(b) shows a front view of the turn path C3. Figure 7(c) shows a side view of the turn path C3 as seen from the direction in which the turning path C1 and the return path C2 overlap. Figures 8(a), (b), and (c) show the first ball trajectory 41 and the second ball trajectory 42 as seen from the same direction as in Figures 7(a), (b), and (c).

[0029] As shown in Figure 8(a), when viewed from direction A perpendicular to the plane P containing the rolling path C1 and the return path C2, the first ball trajectory 41 is positioned outside the second ball trajectory 42 at the end Q1 on the rolling path C1 side and the end Q2 on the return path C2 side of the turn path C3. In other words, the distance L1 between the points Q1 and Q2 is greater for the first ball trajectory 41 than for the second ball trajectory 42. Also, at the top Q3 of the turn path C3, the first ball trajectory 41 is positioned inside the second ball trajectory 42. In other words, the projection distance L2 of the top Q3 is smaller for the first ball trajectory 41 than for the second ball trajectory 42.

[0030] As shown in Figure 8(b), in a front view of the turn path C3, the first ball trajectory 41 and the second ball trajectory 42 curve upwards. As shown in Figure 8(c), in a side view, the first ball trajectory 41 and the second ball trajectory 42 of the turn path C3 curve downwards. The symbol Q3 indicates the top of the turn path C3.

[0031] As shown in Figures 9(a) and 9(b), the first ball trajectory 41 and the second ball trajectory 42 are formed, for example, by bending a rectangular virtual plate VP. As shown in Figure 9(a), the length M1 of the short sides 61a and 61b of the virtual plate VP is set to the distance M1 between the first ball trajectory 41 and the second ball trajectory 42, and the length M2 of the long sides 62a and 62b is set to the circumference of the first ball trajectory 41 and the second ball trajectory 42. Then, as shown in Figure 9(b), when this virtual plate VP is curved into a U-shape and the short sides 61a and 61b of the virtual plate VP are twisted to match the opening angles of the ends Q1 and Q2 of the turn path C3, the shape of the long side 62a of the virtual plate VP is the shape of the first ball trajectory 41, and the shape of the long side 62b of the virtual plate VP is the shape of the second ball trajectory 42.

[0032] The retainer 71 is described below. As shown in Figure 10, the retainer 71 has two rows of balls 6 arranged in a staggered pattern. The first row of balls 6 is arranged at a constant pitch, and the second row of balls 6 is also arranged at a constant pitch. The ball pitch of the first row of balls 6 and the second row of balls 6 are offset by 1 / 2. The number of balls 6 in the first row is not particularly limited, for example, 5 to 30. The number of balls 6 in the second row is not particularly limited, for example, 5 to 30. The retainer 71 is manufactured by injection molding of resin. The retainer 71 is flexible so that it can move along the circulation path 7.

[0033] The retainer 71 comprises a center band 72 between two rows of balls 6 and two side bands 73 outside the two rows of balls. The center band 72 and the side bands 73 are of the same thickness. As shown in Figure 11(a), the center band 72 and the two side bands 73 are positioned below the center of the balls 6. As shown in the bottom view of the retainer 71 in Figure 11(b), the center band 72 and the two side bands 73 of the retainer 71 have substantially circular first ball housing sections 74 formed at a constant pitch for housing the first row of balls 6, and substantially circular second ball housing sections 75 formed at a constant pitch for housing the second row of balls 6.

[0034] The retainer 71 has a first intermediate spacer 76 integrally formed between adjacent balls 6 in the first row, and a second intermediate spacer 77 integrally formed between adjacent balls 6 in the second row. The first intermediate spacer 76 is substantially cylindrical in shape. The first intermediate spacer 76 has a spherical recess 76a that contacts the adjacent ball 6. The second intermediate spacer 77 is also substantially cylindrical in shape. The second intermediate spacer 77 has a spherical recess 77a that contacts the adjacent ball 6. Flat surfaces 76b and 77b are formed at the lower parts of the first intermediate spacer 76 and the second intermediate spacer 77 to avoid interference with the inner circumference of the circulation path 7.

[0035] At both ends of the retainer 71 in the longitudinal direction, a first end spacer 78 is integrally formed to contact the ball 6 at the end of the first row, and a second end spacer 79 is integrally formed to contact the ball 6 at the end of the second row. The first end spacer 78 is a disc shape and thinner than the first intermediate spacer 76. The first end spacer 78 has a spherical recess 78a that contacts the ball 6 at the end of the first row. The second end spacer 79 is a substantially disc shape and thinner than the second intermediate spacer 77. The second end spacer 79 has a spherical recess 79a that contacts the ball 6 at the end of the second row.

[0036] As shown in Figures 11(a) and 12(a), when the retainer 71 is positioned horizontally, the first end spacer 78 and the second end spacer 79 are positioned below the first intermediate spacer 76 and the second intermediate spacer 77 (in other words, on the inner circumference side of the circulation path 7).

[0037] As shown in Figures 11(b) and 12(b), both ends of the retainer 71 in the longitudinal direction are formed in a stepped shape. Inclined portions 72a are formed at both ends of the center band 72 in the longitudinal direction to connect the first end spacer 78 and the second end spacer 79. The inclination angle α of the inclined portion 72a is, for example, 20° to 40°.

[0038] As shown in Figure 13(a), the two rows of balls 6 are spaced apart when viewed along the length of the retainer 71. The end faces 78b and 79b of the first end spacer 78 and the second end spacer 79 are formed flat. The spacer balls 81 are in contact with these end faces 78b and 79b. Chamfers are formed on the upper parts 78c and 79c of the first end spacer 78 and the second end spacer 79.

[0039] As shown in Figure 14, the circulation path 7 is provided with 3 or more, preferably 4 or more, and more preferably 4 to 6 retainers 71. Figure 14 shows 5 retainers 71. Between the front and rear retainers 71 in the direction of travel, spacer balls 81 not held by the retainers 71 are arranged. As shown in Figure 15, the retainer 71 has two rows of balls 6 arranged in a staggered pattern, and the two spacer balls 81 are also arranged in a staggered pattern. One of the two spacer balls 81 is in contact with the first end spacer 78 of the front and rear retainers 71, and the other is in contact with the second end spacer 79 of the front and rear retainers 71.

[0040] The effects of the motion guidance device of this embodiment will be explained below.

[0041] By forming the turn path C3 in the three-dimensional shape described above, the degree of freedom in the layout of the rolling path C1 and return path C2 connected to the turn path C3 can be increased. For example, as shown in Figure 2, the upper return path C2 can be positioned below the contact angle line N1 of the upper two rows of balls 6, and the lower return path C2 can be positioned above the contact angle line N2 of the lower two rows of balls 6. This makes it possible to miniaturize the carriage 2.

[0042] By using three bands for the retainer (a center band 72 and two side bands 73), it is possible to hold two rows of balls 6, and since the two rows of balls 6 are spaced apart when viewed from the length direction of the retainer 71, the width of the center band 72 can be ensured. As shown in Figure 11(b), for example, if gate positions 76c and 77c for injection molding are placed at every other first intermediate spacer 76 and every other second intermediate spacer 77, a weld line will be formed on the center band 72, but by ensuring the width of the center band 72, a reduction in strength due to the weld line can be prevented. Therefore, the durability of the retainer 71 can be improved.

[0043] By arranging two spacer balls 81 in a staggered pattern between adjacent retainers 71 in the direction of travel, the bending of the ends of the retainers 71 in the turn path C3 can be mitigated, thereby improving the durability of the retainers 71.

[0044] Since the end faces 78b and 79b of the first end spacer 78 and the second end spacer 79 of the retainer 71 are formed flat, the bending of the end of the retainer 71 can be further reduced.

[0045] Since four or more retainers 71 are provided in the circulation path 7, the length of each retainer 71 can be shortened, improving the durability of the retainers 71 as they move through the complex three-dimensional shape of the turn path C3. If the number of retainers 71 exceeds seven, it becomes time-consuming to incorporate the retainers 71 into the circulation path 7, so it is preferable to have four to six retainers 71.

[0046] With the retainer 71 positioned horizontally, the first end spacer 78 and the second end spacer 79 are positioned lower than the first intermediate spacer 76 and the second intermediate spacer 77, thereby preventing the first end spacer 78 and the second end spacer 79 from contacting the outer circumference of the turn path C3.

[0047] With the retainer 71 positioned horizontally, the center band 72 and the two side bands 73 are positioned below the centers of the first row of balls 6 and the second row of balls 6, thereby improving the bending strength of the retainer 71 and the holding strength of the balls 6. [Explanation of symbols]

[0048] 1…Guide rail, 2…Carriage, 6…Ball, 7…Circulation path, 12…Rolling part of guide rail, 13…Rolling part of carriage, C1…Rolling path, C2…Return path, C3…Turn path, P…Plane containing the rolling path and return path, A…Direction perpendicular to the plane containing the rolling path and return path, Q1…End of turn path on the rolling path side, Q2…End of turn path on the return path side, Q3…Top of turn path, 21…First turn path for the first row of balls, 22…Second turn path for the second row of balls, 71…Retainer, 72…Center band, 73…Side band, 76…First intermediate spacer between the first row of balls, 77…Second intermediate spacer between the second row of balls, 78…First end spacer, 79…Second end spacer, 81…Spacer ball

Claims

1. A guide rail having a rolling part, The carriage comprises a rolling section facing the aforementioned rolling section, a return path, and a turn path, A retainer is provided in which two rows of balls are arranged in a staggered pattern in a circulation path including a rolling path between the rolling part of the guide rail and the rolling part of the carriage, a return path, and a turn path. Viewed from a direction perpendicular to the plane containing the rolling path and the return path, at the rolling path side end and the return path side end of the turn path, the first turn path for the first row of balls is positioned outside the second turn path for the second row of balls, and at the top of the turn path, the first turn path is positioned inside the second turn path. The retainer comprises a center band between two rows of balls and two side bands outside the two rows of balls. A motion guide device in which the two rows of balls are spaced apart when viewed from the longitudinal direction of the retainer.

2. The motion guide device according to claim 1, characterized in that two spacer balls not held by the retainers are arranged in a staggered pattern between adjacent retainers in the front and rear directions of travel.

3. The motion guide device according to claim 2, characterized in that the end faces of the first end spacer and the second end spacer, which are arranged at the longitudinal ends of the retainer, are formed flat.

4. The motion guidance device according to claim 1 or 2, characterized in that four or more retainers are provided in the circulation path.

5. The motion guide device according to claim 1 or 2, characterized in that, when the retainer is positioned on a horizontal plane, the first end spacer and the second end spacer, which are positioned at the longitudinal ends of the retainer, are positioned below the first intermediate spacer between the balls in the first row and the second intermediate spacer between the balls in the second row.

6. The motion guide device according to claim 1 or 2, characterized in that, when the retainer is positioned on a horizontal plane, the center band and the two side bands are positioned below the center of the first row of balls and the center of the second row of balls.

7. The motion guidance device according to claim 1 or 2, characterized in that at least one retainer is provided in each of the four circulation paths.

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