Linear guide

Abstract

To provide a linear guide which can suppress noise caused by a ball colliding with a corner part in an end of a slider side raceway groove of a slider body and inhibit deterioration of workability even when an assembly error occurs.SOLUTION: A linear guide 1 includes: a guide rail 3 having a rail side raceway groove 5; a slider body 21 having a slider side raceway groove 23 which forms a load rolling passage 24 with the rail side raceway groove 5 and a rolling element return passage 28; a pair of end caps 30 each having turnaround passages 26 and respectively attached to both axial ends of the slider body 21; and a number of balls 10. A center axis L1 of the turnaround passage 26 connecting the load rolling passage 24 with the rolling element return passage 28 is connected to a center axis L2 of the load rolling passage 24, offset in a direction away from the guide rail 3. Chamfered parts 29 each having a chamfered width W larger than an offset amount Do are respectively provided at corner parts 23a at both ends of the slider side raceway groove 23.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a linear guide, and more particularly to a linear guide that can suppress noise and deterioration of operability caused by balls colliding with corners at the ends of slider-side raceway grooves of a slider body. [Background technology]

[0002] Conventionally, a linear guide (linear guiding device) includes a guide rail extending in the axial direction and a slider mounted on the guide rail so as to be movable relative to the guide rail. The slider moves relative to the guide rail in the axial direction via a plurality of balls (spherical rolling elements) that circulate between the guide rail and a rolling element circulating path (rolling element rolling path) formed in the slider. Such linear guides are widely used in linear motion mechanisms in various production facilities.

[0003] The slider body of the slider has a slider-side raceway groove that forms a loaded rolling path together with the rail-side raceway groove of the guide rail, and a rolling element return path formed approximately parallel to the slider-side raceway groove. A pair of end caps are attached to the axial ends of the slider body to form the slider. The end caps have direction change paths that connect the loaded rolling path and the rolling element return path.

[0004] The direction change path is made up of an outer peripheral wall surface formed on the end cap and an inner peripheral wall surface formed on a return guide incorporated in the end cap, while the load rolling path is made up of a rail-side raceway groove formed in the guide rail and a slider-side raceway groove formed in the slider body.

[0005] It is known that multiple balls that enter and exit the load rolling path from the direction change path of the end cap repeatedly collide with the corners at both ends of the slider-side raceway groove of the slider body, causing problems such as noise and deterioration of operability, and various countermeasures have been proposed.

[0006] For example, in the linear operation ball bearing (linear guide) disclosed in Patent Document 1, the center of curvature of the curved surface (outer peripheral wall surface) of the ball return hole (rolling element return path) at the boundary with the load side raceway (load rolling path) is offset to make the curved surface continuous with the load side raceway (rail side raceway groove).As a result, no steps are created when the balls move between the load side raceway and the ball return hole, and smooth ball rolling is achieved.

[0007] Furthermore, in the linear guide bearing device (linear guide) disclosed in Patent Document 2, the play of the balls at the entrance / exit of the curved track (entrance / exit of the rolling element return path) is made smaller than the play of the balls within the curved track, so that the play of the balls at the entrance / exit of the curved track is reduced. This reduces the number of times the balls collide with surrounding guide members and rails, reduces noise, and improves operability. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Utility Model Application Publication No. 59-103928 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-304045 Summary of the Invention [Problem to be solved by the invention]

[0009] However, while the linear guides in Patent Documents 1 and 2 are both designed to allow balls to smoothly move in and out of the rolling element rolling path, in reality, there is a problem in that it is difficult to manufacture a linear guide with the desired circulation path shape when taking into account the manufacturing tolerances of parts and assembly accuracy.

[0010] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a linear guide that can suppress noise and deterioration of operability caused by balls colliding with corners at the ends of the slider-side track grooves of the slider body, even if an assembly error occurs. [Means for solving the problem]

[0011] The above object of the present invention can be achieved by the following configuration. a guide rail having a rail-side raceway groove formed on a side surface along the longitudinal direction; a slider body of a slider having a slider-side raceway groove that forms a loaded rolling path together with the rail-side raceway groove, and a rolling element return path formed substantially parallel to the slider-side raceway groove, the slider body slidably engaging across the guide rail; a pair of end caps each having a direction change path connecting the load rolling path and the rolling element return path and attached to both axial ends of the slider body; A linear guide including a large number of balls that roll in the load rolling path, the rolling element return path, and the direction changing path, a central axis of the direction change path is offset from a central axis of the loaded rolling path in a direction away from the guide rail, and the corners at both ends of the slider-side raceway groove are chamfered with a chamfer width larger than the amount of the offset. A linear guide characterized by: [Effects of the Invention]

[0012] According to the linear guide of the present invention, even if an assembly error occurs, a linear guide can be provided that can suppress noise generated when the ball hits the corner at the end of the slider-side track groove of the slider body, and deterioration of operability. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a partially cutaway perspective view of a linear guide according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic top view of the linear guide shown in FIG. 1, with a portion of the top surface thereof cut away. [Figure 3] FIG. 3 is a front view of the slider body and the guide rail shown in FIG. 1 as viewed from the end cap side. [Figure 4] FIG. 4 is a front view of the end cap shown in FIG. 1 as viewed from the opposing slider body side. [Figure 5] 5(a) and 5(b) are a front view and a rear view of the return guide incorporated in the end cap, as viewed from the opposing slider body side. [Figure 6] 6 is a front view of the return guide and guide rail incorporated in the end cap shown in FIG. 4, viewed from the opposing slider body side. [Figure 7] 7 is an enlarged cross-sectional view of a main portion of a direction change path and a load rolling path in the linear guide shown in FIG. [Figure 8] FIG. 8 is a projection view of the shape of the direction change path of the end cap and the shape of the guide rail at part A in FIG. 6, projected onto a projection plane perpendicular to the moving direction of the slider. [Figure 9] FIG. 9 is an enlarged cross-sectional view of a main portion of a direction change path and a load rolling path in a conventional linear guide. [Figure 10] FIG. 10 is an enlarged cross-sectional view of a main portion of a direction change path and a load rolling path in a linear guide according to a second embodiment of the present invention. [Figure 11] Figure 11 shows the results of numerical analysis of the trajectory of the ball circulating inside the direction change path. The graph shows the offset of the central axis of the direction change path from the central axis of the loaded rolling path as Do, the play for the ball in the direction change path as Db, and the horizontal axis as 2 × Do / Db, while the vertical axis shows the amount of deviation of the center of the ball from the central axis of the direction change path. DETAILED DESCRIPTION OF THE INVENTION

[0014] A linear guide according to one embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, the vertical direction and width direction of the slider refer to the directions when the slider is assembled to a guide rail arranged with its longitudinal direction horizontal, and the width direction of the slider is the direction perpendicular to the longitudinal direction of the guide rail and the vertical direction of the slider, and is also referred to as the left-right direction (see FIG. 1). The longitudinal direction is also referred to as the axial direction.

[0015] (First embodiment) As shown in FIG. 1, the linear guide 1 according to the first embodiment of the present invention comprises a linear guide rail 3 and a slider 20 having a C-shaped cross section, which is assembled so as to straddle the guide rail 3 and slidably engages with the guide rail 3 via a plurality of balls (spherical rolling elements) not shown.

[0016] The guide rail 3 is made of metal, and on both widthwise sides thereof, two rows on each side are formed with rail-side track grooves 5 extending in the longitudinal direction, for a total of four rows. The guide rail 3 has a plurality of rail mounting holes 4 penetrating the guide rail 3 in the height direction, and rail fixing bolts (not shown) are inserted into these rail mounting holes 4 to fix the guide rail 3 to a mounting surface (not shown).

[0017] As shown in Figures 1 to 3, the slider 20 of this first embodiment comprises a slider body 21 having sleeve portions on both the left and right sides of the guide rail 3, a pair of end caps 30, 30 attached to both ends of the slider body 21 in the front-to-rear direction (axial direction), return guides 40, 40 incorporated into each of these end caps 30, 30, and a pair of side seals 60, 60 that seal the gap between the guide rail 3 and the end caps 30, 30.

[0018] 2 and 4, the slider body 21 has, on both the left and right sides, multiple stages (two stages in the first embodiment) of slider-side raceway grooves 23 and rolling element return paths 28. The slider-side raceway grooves 23 are formed on the inner surfaces of both sleeve portions of the slider body 21 and face the rail-side raceway grooves 5 of the guide rail 3, respectively, and the rail-side raceway grooves 5 and the slider-side raceway grooves 23 form two-stage load rolling paths 24. The rolling element return paths 28 are formed by two holes that penetrate the thick portions of both sleeve portions in the longitudinal direction (axial direction) of the guide rail 3. In addition, the top surface of the slider body 21 is provided with driven body fixing screw insertion holes 25 through which bolts for fixing a driven body such as a table to the slider 20 are inserted.

[0019] 3 and 5, the end cap 30 of the first embodiment is, for example, an injection-molded product made of synthetic resin, and is formed with a C-shaped cross section similar to the slider body 21. The end cap 30 is provided with a plurality of mounting screw insertion holes 34, and the end cap 30, together with the side seal 60, is fastened to the end 21 a of the slider body 21 in the front-rear direction by mounting screws 35 inserted into the mounting screw insertion holes 34.

[0020] In addition, on the left and right sleeve portions 31 of the end cap 30, semi-disk-shaped recesses 36 are formed in two tiers, upper and lower, on the abutment surface 31a side facing the front-to-rear end portion 21a of the slider body 21, and a semi-cylindrical recess 39 is formed at a position crossing the widthwise center of the two tiers of semi-disk-shaped recesses 36.

[0021] As shown in Figures 3 and 6(a) and (b), the return guide 40 is formed into a semi-cylindrical shape by injection molding of resin or metal, or by a 3D printer. Possible resin materials include engineering plastics such as polyacetal (POM), polyamide (PA), and PEEK, which may be reinforced with approximately 2 to 50% glass fiber or carbon fiber. Possible metal materials include austenitic stainless steels such as SUS304 and SUS316, and tool steels such as SKD11. It is also possible to form the return guide 40 by cutting resin or metal materials.

[0022] The semi-cylindrical return guide 40 is attached to the contact surface 31a of the end cap 30 by fitting into the semi-cylindrical recess 39 of the end cap 30 with the cylindrical surface 40b, on which the semi-annular recess 41 is formed in two stages, upper and lower, facing inward. As a result, the semi-cylindrical recess 39 of the return guide 40 and the semi-disk-shaped recess 36 of the end cap 30 define the curved, annular direction change path 26 in two stages, upper and lower, on the contact surface 31a of the end cap 30.

[0023] The direction change path 26 is connected to the two-stage loaded rolling path 24 and the rolling element return path 28 of the slider body 21. The direction change path 26 also has a scooping portion 45 formed in the end cap 30 to guide the balls 10 rolling in the loaded rolling path 24 into the direction change path 26.

[0024] The load rolling path 24, the rolling element return path 28, and the direction change path 26 form a rolling element circulation path 27. A large number of balls (spherical rolling elements) 10 are loaded in the rolling element circulation path 27 so that they can roll freely, and the slider 20 can move relatively along the axial direction on the guide rail 3 via these balls 10 that circulate endlessly while rolling within the rolling element circulation path 27.

[0025] As shown in Figures 3 and 6(a), the opposing surface 40a of the return guide 40, which faces the front-to-rear end 21a of the slider body 21, is recessed with lubricant passage grooves 42 that are each connected to the direction change path 26 via a plurality of (two in this first embodiment) lubricant supply holes 44 arranged in series along the lubricant supply direction (vertical direction).

[0026] A lubricant passage groove 37 extending in the width direction is recessed in the horizontal portion 32 of the end cap 30 on the side of the abutment surface 32a facing the front-rear end of the slider body 21. A lubricant introduction portion 33 is drilled in the center of the lubricant passage groove 37 to introduce lubricant into the end cap 30 from a nipple (not shown). Further, a lubricant passage groove 38 is recessed in the contact surfaces 31 a of the left and right sleeve portions 31 of the end cap 30 , extending from the lubricant passage groove 37 to the lubricant passage groove 42 of the return guide 40 .

[0027] Then, by fixing the end cap 30 to the front-rear end of the slider body 21, a lubricant passage that communicates with the lubricant inlet portion 33 and leads the lubricant to the direction changing path 26 is defined between the lubricant passage grooves 37, 38, and 42 in the end cap 30 and the end face of the slider body 21. The lubricant introduced into the end cap 30 from the nipple passes through the lubricant passage grooves 37 and 38 from the lubricant inlet portion 33 to the lubricant passage groove 42, and is then supplied to the direction changing path 26 via the lubricant supply hole 44.

[0028] In a conventional linear guide 501 having a general configuration in which the central axis L1 of the direction change path 26 coincides with the central axis L2 of the loaded rolling path 24, as shown in FIG. 9, a ball 10 circulating along the outer peripheral wall surface 26a of the direction change path 26 collides with the rail-side raceway groove 5 provided in the guide rail 3 and bounces off as it enters the loaded rolling path 24, as indicated by reference numeral 10a in the figure. The collision position between the ball 10 and the rail-side raceway groove 5 is located before the entrance of the slider-side raceway groove 23, and the ball 10 is not restrained by surrounding objects, leaving ample room for displacement. As a result, the ball 10 deviates from the central axis L2 of the loaded rolling path 24 and collides with corners 23a at both longitudinal ends of the slider-side raceway groove 23 of the slider body 21, as indicated by reference numeral 10b in the figure.

[0029] 7 and 8, in the linear guide 1 according to the first embodiment, the central axis L1 of the direction changing path 26 is connected to the direction changing path 26 so as to be offset in a direction away from the guide rail 3 with respect to the central axis L2 of the load rolling path 24. As a result, the collision position between the ball 10 and the rail-side raceway groove 5 is close to the entrance of the slider-side raceway groove 23. Therefore, the distance between the ball 10 and the entrance of the slider-side raceway groove 23 is narrowed, which makes it possible to suppress positional deviation of the ball 10 from the central axis L2 of the load rolling path 24 due to the bouncing behavior of the ball 10. Therefore, the balls 10 circulating along the outer wall surface 26a of the direction change path 26 smoothly enter the load rolling path 24, and collision between the corners 23a at both longitudinal ends of the slider side track groove 23 of the slider body 21 and the balls 10 can be suppressed.

[0030] Further, the corners 23a at both ends of the slider-side raceway groove 23 in the longitudinal direction are provided with chamfers 29 having a chamfer width W larger than the amount of offset Do. As a result, the cross-sectional area of ​​the connection between the direction change path 26 and the load rolling path 24 is wider than the cross-sectional area within the direction change path 26, and even if an assembly error occurs in the end cap 30 or the return guide 40, the circulation of the balls 10 is less likely to be hindered, and the function of suppressing collision between the corners 23a at both longitudinal ends of the slider-side raceway groove 23 and the balls 10 can be maintained.

[0031] Therefore, according to the linear guide 1 of this first embodiment, the ball 10 entering the load rolling path 24 from within the direction change path 26 is prevented from colliding with the slider body 21, thereby reducing noise and achieving excellent operability. Furthermore, there is no need to extremely narrow the play of the balls 10 within the direction change paths 26, nor is there a need to make the connection between the direction change paths 26 and the load rolling paths 24 tangent to each other. Therefore, even if some assembly error occurs, the function of suppressing collision between the corners 23a at both longitudinal ends of the slider-side raceway groove 23 and the balls 10 can be maintained.

[0032] (Second embodiment) FIG. 10 is an enlarged cross-sectional view of a main portion of the direction change path 26 and the load rolling path 24 in a linear guide 1A according to a second embodiment of the present invention. As shown in Figure 10, in the linear guide 1A according to the second embodiment of the present invention, when the amount of offset of the central axis of the direction change path from the central axis of the load rolling path 24 is Do and the play for the ball 10 in the direction change path 26 is Db, the linear guide 1A is configured to have the relationship "2 x Do / Db > 1".

[0033] In other words, when the relationship is "2×Do / Db=1", the outer peripheral wall surface 26a of the direction change path 26 and the rail-side raceway groove 5 of the loaded rolling path 24 are connected in a tangential relationship, but in the second embodiment, a larger offset amount Do is provided.

[0034] 11 is a graph showing the results of numerical analysis of the trajectory of the ball 10 circulating in the direction change path 26, with the horizontal axis representing "2×Do / Db" and the vertical axis representing the "amount of positional deviation of the center of the ball 10" from the central axis of the direction change path 26 when the ball 10 enters the loaded rolling path 24 from the direction change path 26. This means that the greater this positional deviation, the greater the impact force of the ball 10 against the corners 23a at both longitudinal ends of the slider-side raceway groove 23 of the slider body 21.

[0035] 11, the amount of positional deviation of the center of the ball 10 tends to decrease as the offset amount Do increases, and the amount of positional deviation is particularly small when the relationship "2×Do / Db>1" is satisfied. Therefore, it is clear that the linear guide 1A according to the second embodiment, by having the relationship "2×Do / Db>1," can be expected to have a significant effect of suppressing the impact force of the ball 10 against the corners 23a at both longitudinal ends of the slider-side raceway groove 23 of the slider body 21.

[0036] Therefore, according to the linear guides 1 and 1A according to the first and second embodiments of the present invention, even if an assembly error occurs, it is possible to suppress noise and deterioration of operability that are generated when the balls 10 collide with the corners 23a at both longitudinal ends of the slider-side raceway groove 23 of the slider body 21.

[0037] The present invention is not limited to the above-described embodiments, and can be appropriately modified, improved, etc. Furthermore, the material, shape, size, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention.

[0038] Here, the features of the above-described embodiments of the linear guide according to the present invention will be briefly summarized and listed below in [1] to [2]. [1] A guide rail (3) having a rail-side track groove (5) formed on the side surface along the longitudinal direction; a slider body (21) of a slider (20) having a slider-side raceway groove (23) that forms a loaded rolling path (24) together with the rail-side raceway groove (5) and a rolling element return path (28) formed substantially parallel to the slider-side raceway groove (23), and slidably engaging with the guide rail (3) so as to straddle the guide rail (3); a pair of end caps (30) each having a direction change path (26) connecting the load rolling path (24) and the rolling element return path (28) and attached to both axial ends of the slider body (21); A linear guide including a large number of balls (10) that roll in the load rolling path (24), the rolling element return path (28), and the direction changing path (26), The central axis (L1) of the direction change path (26) is connected to the central axis (L2) of the load rolling path (24) while being offset in a direction away from the guide rail (3), and the corners (23a) at both ends of the slider-side raceway groove (23) are provided with chamfers (29) having a chamfer width (W) larger than the amount of offset (Do). A linear guide (1, 1A) characterized by:

[0039] According to the configuration [1] above, when the balls 10 circulating in the direction change path 26 enter the loaded rolling path 24, it is possible to reduce the force with which the balls 10 collide with the rail-side raceway groove 5 provided in the guide rail 3. This allows the balls 10 circulating along the outer peripheral wall surface 26a of the direction change path 26 to smoothly enter the loaded rolling path 24, and it is possible to suppress collision of the balls 10 with the corners 23a at both longitudinal ends of the slider-side raceway groove 23 of the slider body 21. Furthermore, the cross-sectional area of ​​the connection between the direction change path (26) and the load rolling path (24) is larger than the cross-sectional area within the direction change path (26). Therefore, even if an assembly error occurs in the end cap (30) or the return guide (40), the circulation of the balls (10) is not easily hindered, and the function of suppressing collision between the corners (23a) at both longitudinal ends of the slider-side raceway groove (23) and the balls (10) can be maintained.

[0040] [2] When the play for the ball (10) in the direction change path (26) is Db and the amount of the offset is Do, the relationship is "2 × Do / Db > 1." The linear guide (1A) according to the above [1].

[0041] According to the configuration [2] above, the amount of positional deviation of the center of the ball (10) tends to decrease as the offset amount Do increases, and the smaller this positional deviation, the weaker the impact force of the ball (10) on the corners (23a) at both longitudinal ends of the slider-side track groove (23) of the slider body (21), thereby further suppressing the collision between the corners (23a) of the slider body (21) and the ball (10). [Explanation of symbols]

[0042] 1 Linear guide 3 Guide rails 5 Rail side track groove 10 balls 20 Slider 21 Slider body 23 Slider side raceway groove 24 Load rolling path 26 Turning Point 28 Rolling element return path 29 Chamfering 30 End Cap

Claims

1. a guide rail having a rail-side raceway groove formed on a side surface along the longitudinal direction; a slider body of a slider having a slider-side raceway groove that forms a loaded rolling path together with the rail-side raceway groove, and a rolling element return path formed substantially parallel to the slider-side raceway groove, the slider body slidably engaging across the guide rail; a pair of end caps each having a direction change path connecting the load rolling path and the rolling element return path and attached to both axial ends of the slider body; A linear guide including a large number of balls that roll in the load rolling path, the rolling element return path, and the direction changing path, a central axis of the direction change path is offset from a central axis of the loaded rolling path in a direction away from the guide rail, and the corners at both ends of the slider-side raceway groove are chamfered with a chamfer width larger than the amount of the offset. A linear guide characterized by:

2. When the play for the ball in the direction change path is Db and the amount of the offset is Do, the relationship is "2×Do / Db>1." 2. The linear guide according to claim 1.

Images