Linear guide unit

Abstract

To provide a linear guide unit capable of smoothly sliding a slider for a long period.SOLUTION: A linear guide unit includes: a rail; a slider; and balls as a plurality of rolling elements. An annular passage in which the plurality of rolling elements circulate is formed by the rail and the slider. The annular passage includes: a raceway passage formed of a first raceway groove and a second raceway groove; a first circulation passage formed in the slider and parallel with the raceway passage; and a pair of second circulation passages formed in the slider and connecting the raceway passage to the first circulation passage. The slider includes a metal coil spring positioned so as to extend in a longitudinal direction in the first circulation passage. The coil spring includes: a first area provided in a part in the longitudinal direction; and a second area provided continuously to the first area in the longitudinal direction. The first area is constituted of a compression coil spring, and the second area is constituted of a tension coil spring.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a linear motion guide unit. [Background technology]

[0002] A linear motion rolling guide unit including a slider that includes rolling elements and is slidable in the longitudinal direction of a rail is known (see, for example, Patent Document 1). The linear motion rolling guide unit disclosed in Patent Document 1 includes a return path for returning the rolling elements to the raceway grooves again, and a direction change path for changing the direction of the rolling elements. In the linear motion rolling guide unit disclosed in Patent Document 1, a hollow cylindrical sleeve is fitted into a return hole through which the rolling elements pass. The sleeve is provided with a slit extending in the longitudinal direction, and is elastically deformable. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-72335 Summary of the Invention [Problem to be solved by the invention]

[0004] A linear motion guide unit is required to allow a slider to slide smoothly for a long period of time. Therefore, one of the objects of the present invention is to provide a linear motion guide unit that allows a slider to slide smoothly for a long period of time. [Means for solving the problem]

[0005] A linear motion guide unit according to the present disclosure includes a rail having a pair of first raceway grooves extending parallel to each other in the longitudinal direction, a slider attached to the rail so as to be movable relative to the rail and having a pair of second raceway grooves facing the pair of first raceway grooves, and balls as a plurality of rolling elements. The rail and the slider form an annular path through which the plurality of rolling elements circulate. The annular path includes a raceway path consisting of the first raceway grooves and the second raceway grooves, a first circulation path formed in the slider and parallel to the raceway path, and a pair of second circulation paths formed in the slider and connecting the raceway path and the first circulation path. The slider includes a metallic coil spring arranged to extend in the longitudinal direction within the first circulation path. The coil spring includes a first region provided in a portion of the longitudinal direction and a second region provided continuous with the first region in the longitudinal direction. The first region is formed of a compression coil spring. The second region is formed of a tension coil spring. Effect of the Invention

[0006] According to the linear motion guide unit described above, the slider can slide smoothly for a long period of time. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic perspective view showing a linear motion guide unit in accordance with the first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic side view showing the linear motion guide unit shown in FIG. [Diagram 3] FIG. 3 is a schematic side view showing a part of the linear motion guide unit shown in FIG. [Figure 4] FIG. 4 is a schematic plan view showing a portion of the linear motion guide unit shown in FIG. [Diagram 5] FIG. 5 is a schematic side view of the linear guide unit shown in FIG. 1 with a first end cap, which is one of the end caps described below, removed. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a part of a slider, which will be described later. [Figure 7]FIG. 7 is an enlarged view of the region indicated by VII in FIG. [Figure 8] FIG. 8 is a schematic side view showing a coil spring. [Figure 9] FIG. 9 is a schematic perspective view showing a linear motion guide unit in accordance with the second embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic side view showing the linear motion guide unit shown in FIG. [Figure 11] FIG. 11 is a schematic side view showing a portion of the linear motion guide unit shown in FIG. [Figure 12] FIG. 12 is a schematic side view of the linear motion guide unit shown in FIG. 9 with the first end cap, which is one of the end caps, removed. [Figure 13] FIG. 13 is a schematic cross-sectional view showing a portion of the slider. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Overview of the embodiment] The linear motion guide unit of the present disclosure includes a rail having a pair of first raceway grooves extending parallel to each other in the longitudinal direction, a slider attached to the rail so as to be relatively movable and having a pair of second raceway grooves facing the pair of first raceway grooves, and balls as a plurality of rolling elements. The rail and the slider form an annular path through which the plurality of rolling elements circulate. The annular path includes a raceway path consisting of the first raceway grooves and the second raceway grooves, a first circulation path formed in the slider and parallel to the raceway path, and a pair of second circulation paths formed in the slider and connecting the raceway path and the first circulation path. The slider includes a metallic coil spring arranged to extend in the longitudinal direction within the first circulation path. The coil spring includes a first region provided in a portion of the longitudinal direction and a second region provided in continuity with the first region in the longitudinal direction. The first region is formed of a compression coil spring. The second region is formed of a tension coil spring.

[0009] According to the linear motion guide unit of the present disclosure, the coil spring includes a first region that is provided in a part of the longitudinal direction and is made of a compression coil spring, and a second region that is provided in a longitudinal direction connected to the first region and is made of a tension coil spring. With this configuration, the overall length of the coil spring is made longer than the longitudinal length of the first circulation path in advance, and when the coil spring is arranged in the first circulation path, the coil spring can be accommodated in the first circulation path by compressing it in the longitudinal direction using elastic deformation in the first region. Then, the compression coil spring tries to return to its original shape due to the restoring force of the compression coil spring, and as a result, the coil spring can be arranged over the entire longitudinal area of ​​the first circulation path. Therefore, it is possible to reduce the risk of a gap being generated between the connection part of the first circulation path and the second circulation path and the end of the coil spring in the first circulation path. As a result, it is possible to reduce the risk of contact between the end of the coil spring and the rolling element when the rolling element enters the first circulation path from the second circulation path, and to suppress wear of the end of the coil spring. Also, the resistance when the rolling elements enter the first circulation path can be reduced. Furthermore, by including such a coil spring, it is possible to supply lubricating oil to the rolling elements from the gaps in the coil spring over the entire longitudinal area of ​​the coil spring. Therefore, the supply of lubricating oil to the rolling elements can be performed smoothly. As a result, with this linear motion guide unit, the slider can slide smoothly for a long period of time.

[0010] In the linear motion guide unit, the first region may be fitted into the first circulation path. The diameter of the second region may be smaller than the diameter of the first region. Since the first region is fitted into the first circulation path, when the rolling body moves from the second circulation path to the first circulation path, the step can be reduced and the rolling body can smoothly enter from the second circulation path to the first circulation path. Also, when the rolling body enters the raceway, which is the preload area where the preload is applied, from the second circulation path, which is the direction changing path, the coil spring can be elastically deformed by utilizing the radial gap provided between the inner wall surface of the first circulation path and the second region in the first circulation path, and the frictional resistance generated when the rolling body enters the preload area can be absorbed. That is, for example, when the slider moves downward in the vertical direction, when the rolling body is in a staggered position and the pushing direction is not determined, the frictional resistance can be reduced by the radial elastic deformation of the coil spring in the second region where the gap is provided. Therefore, since there is no need for a force to overcome the large frictional resistance, it is possible to prevent the occurrence of jamming caused by the rolling elements getting caught.

[0011] In the linear motion guide unit, the first region may be provided on one end side in the longitudinal direction. In this way, the first region can be easily formed, particularly when the coil spring is an integrated type, and therefore productivity can be improved.

[0012] In the linear motion guide unit, the coil spring may further include a third region provided on the other end side in the longitudinal direction and fitted into the first circulation path. The diameter of the second region may be smaller than the diameter of the third region. In this way, the coil spring is fitted into the first circulation path at both longitudinal end sides of the coil spring, so that when the rolling elements move from each of the pair of second circulation paths to the first circulation path, the step is reduced and the rolling elements can smoothly enter from the second circulation path to the first circulation path. In addition, since the diameter of the second region is smaller than the diameter of the third region, the occurrence of a jamming state due to the rolling elements getting caught can be suppressed by utilizing the radial elastic deformation of the second region.

[0013] In the linear guide unit, the first region may gradually expand in diameter from a portion connected to the second region toward one end in the longitudinal direction. This prevents a large step from being formed in the portion of the first region connected to the second region, allowing the rolling element to move smoothly. This allows the slider to slide more smoothly.

[0014] In the linear motion guide unit, the inner diameter surface of the first region may be tapered to expand in diameter, which can suppress the formation of a step in the first region and gradually expand the diameter of the first region in the longitudinal direction, allowing the slider to slide more smoothly.

[0015] In the linear motion guide unit, the coil spring may be an integrated type, which allows the rolling elements to move smoothly inside the coil spring in the first circulation path and improves workability during assembly.

[0016] In the linear motion guide unit, the rail may include a first rail side surface and a second rail side surface extending parallel to each other along the longitudinal direction. The slider may be mounted across the rail. One of the first track grooves may be provided on the first rail side surface. The other of the first track grooves may be provided on the second rail side surface. Such a linear motion guide unit is suitable for use in machine tools, assembly devices, conveying machines, etc.

[0017] In the linear motion guide unit, the rail may be a spline shaft having a solid or hollow cylindrical shape. The slider may be hollow cylindrical and disposed on the outer periphery of the rail. A pair of first raceway grooves extending parallel to each other in the longitudinal direction may be provided on the outer diameter surface of the rail. Such a linear motion guide unit can simultaneously receive torque in addition to radial load. Therefore, it can be effectively used when radial load and torque are generated.

[0018] [Specific Example of the Embodiment] Next, an example of a specific embodiment of the linear guide unit of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0019] (Embodiment 1) First, a first embodiment of the present disclosure will be described. FIG. 1 is a schematic perspective view showing a linear guide unit in the first embodiment of the present disclosure. FIG. 2 is a schematic side view showing the linear guide unit shown in FIG. 1. FIG. 2 is a view of the linear guide unit shown in FIG. 1 as viewed in the direction indicated by the arrow Y. FIG. 3 is a schematic side view showing a part of the linear guide unit shown in FIG. 1. FIG. 3 is a view of the linear guide unit shown in FIG. 1 as viewed in the direction indicated by the arrow X. FIG. 4 is a schematic plan view showing a part of the linear guide unit shown in FIG. 1. FIG. 4 is a view of the linear guide unit shown in FIG. 1 as viewed in the opposite direction to the direction indicated by the arrow Z. FIG. 5 is a schematic side view of the linear guide unit shown in FIG. 1 with a first end cap, which is one of the end caps described later, removed. FIG. 5 is also a view as viewed in the direction indicated by the arrow Y, as in FIG. 2. FIG. 6 is a schematic cross-sectional view showing a part of a slider described later. FIG. 7 is an enlarged view of the area indicated by VII in FIG. 6. In FIG. 6 and FIG. 7, a ball described later is illustrated from the viewpoint of facilitating understanding. 1 and the following figures, the X direction indicates the short side direction, which is the width direction, of the linear guide unit, the Y direction indicates the longitudinal direction of the linear guide unit, and the Z direction indicates the thickness direction (height direction) of the linear guide unit. The X direction, Y direction, and Z direction are each perpendicular to each other.

[0020] 1, 2, 3, 4, 5, 6, and 7, linear motion guide unit 10a according to embodiment 1 of the present disclosure includes rail 11a as an axis, slider 21a, and balls 20 as a plurality of rolling elements. Rail 11a extends straight in the Y direction, which is the longitudinal direction. Linear motion guide unit 10a according to embodiment 1 can have a simple configuration by including balls 20 as rolling elements.

[0021] First, the configuration of the rail 11a will be described. The rail 11a includes a rail upper end surface 12a and a rail lower end surface 12b spaced apart in the Z direction, a first rail side surface 13a and a second rail side surface 13b spaced apart in the X direction, and a rail front end surface 14a and a rail rear end surface 14b spaced apart in the Y direction. That is, the rail 11a includes the first rail side surface 13a and the second rail side surface 13b that extend parallel to each other along the longitudinal direction. The rail 11a has a pair of first raceway grooves 15a, 15b that extend parallel to each other along the longitudinal direction. The first raceway groove 15a is provided on the first rail side surface 13a. The first raceway groove 15b is provided on the second rail side surface 13b. The first raceway grooves 15a, 15b are provided on the first rail side surface 13a and the second rail side surface 13b, respectively, so as to recess toward the inner side of the rail 11a and form a semicircular arc-shaped recessed groove. The first rail side surface 13a and the second rail side surface 13b are provided with recesses 16a, 16b that are recessed further inward in the central regions in the Z direction of the first raceway grooves 15a, 15b. A linear motion guide unit 10a including such a rail 11a is suitable for use in machine tools, assembly devices, conveying machines, and the like.

[0022] The rail 11a is provided with a plurality of through holes 17 penetrating in the Z direction from the rail upper end surface 12a to the rail lower end surface 12b. The plurality of through holes 17 are provided at intervals in the Y direction. The through holes 17 are each effectively used when attaching the rail 11a to a predetermined location, for example, when using the linear motion guide unit 10a.

[0023] Next, the configuration of the slider 21a will be described. The slider 21a is attached to the rail 11a so as to be relatively movable. In this embodiment, the slider 21a is slidably mounted across the rail 11a. That is, the slider 21a is attached so as to straddle the rail 11a, and is configured to be movable in the Y direction.

[0024] The slider 21a has a pair of second raceway grooves 18a, 18b facing the pair of first raceway grooves 15a, 15b. The rail 11a and the slider 21a form an annular path 19a in which a plurality of balls 20 circulate. The annular path 19a includes a raceway path 22a formed of the first raceway grooves 15a and the second raceway grooves 18a, a first circulation path 23a formed in the slider 21a and parallel to the raceway path 22a, and a pair of second circulation paths 24a, 25a formed in the slider 21a and connecting the raceway path 22a and the first circulation path 23a. The first circulation path 23a is also called a return path. The pair of second circulation paths 24a, 25a are also called direction change paths. The raceway path 22a is a preload area in which a preload is applied. The first circulation path 23a and the second circulation paths 24a and 25a are unloaded paths on which no load is applied. The annular path including the raceway formed by the first raceway groove 15b and the second raceway groove 18b has the same configuration. The same applies to the following configurations.

[0025] The slider 21a includes a casing 26a and a pair of end caps 27a and 27b. The casing 26a and the end cap 27a are connected by a plurality of screws 38a, 38b, 38c, and 38d. Similarly, the casing 26a and the end cap 27b are connected by a plurality of screws. The casing 26a has four through holes 37a, 37b, 37c, and 37d that penetrate from the upper surface 36a to the lower surface 36b.

[0026] The casing 26a is provided with a first circulation path 23a, and includes second raceway grooves 18a, 18b. The first end cap 27a is disposed on one side of the casing 26a in the longitudinal direction. In this embodiment, the first end cap 27a is disposed on the rail front end face 14a side in the longitudinal direction. The first end cap 27a is provided with one second circulation path 24a. The second end cap 27b is disposed on the other side of the casing 26a in the longitudinal direction. In this embodiment, the second end cap 27b is disposed on the rail rear end face 14b side in the longitudinal direction. The second end cap 27b is provided with the other second circulation path 25a.

[0027] Next, a more detailed configuration of the slider 21a will be described. The slider 21a includes a metallic coil spring 30a arranged to extend in the longitudinal direction in the first circulation path 23a. The slider 21a also includes a metallic coil spring 30b arranged to extend in the longitudinal direction in the first annular path included in the annular path including the raceway formed by the first raceway groove 15b and the second raceway groove 18b. The configuration of the coil spring 30b is similar to that of the coil spring 30a, and therefore a description thereof will be omitted.

[0028] FIG. 8 is a schematic side view showing the coil spring 30a. FIG. 8 shows a state where the coil spring 30a is not disposed in the first circulation path 23a. Referring also to FIG. 8, the coil spring 30a is made of metal. The coil spring 30a is annular, and the ball 20 with a diameter R1 can pass through the inside of the coil spring 30a. The length of the coil spring 30a is configured to be slightly longer than the length of the first circulation path 23a in a free state, that is, in a state where the coil spring 30a is not disposed in the first circulation path 23a. Referring particularly to FIG. 6 and FIG. 8, if the length of the coil spring 30a in the longitudinal direction is length L1 and the length of the first circulation path 23a in the longitudinal direction is length L2, L1>L2.

[0029] The coil spring 30a includes a first region 31a, a second region 32a, and a third region 33a. The first region 31a is provided on one end 34a side in the longitudinal direction of the coil spring 30a. The third region 33a is provided on the other end 34b side in the longitudinal direction. The second region 32a is provided in continuity with the first region 31a in the longitudinal direction. The second region 32a is disposed between the first region 31a and the third region 33a in the longitudinal direction. In this embodiment, the coil spring 30a is composed of the first region 31a, the second region 32a, and the third region 33a.

[0030] The diameter of the second region 32a is smaller than the diameter of the first region 31a. In FIG. 7, the maximum diameter of the first region 31a is illustrated as diameter D1, and the diameter of the second region 32a is illustrated as diameter D2. In this embodiment, the maximum diameter of the first region 31a is the same as the maximum diameter of the third region 33a. The diameter of the second region 32a is smaller than the diameter of the third region 33a. The second region 32a is disposed between the first region 31a and the third region 33a with a gap 29a between them and the inner wall surface 28a of the first circulation path 23a, 23b. The radial dimension of the gap 29a is indicated by a length D3.

[0031] The first region 31a gradually expands in diameter from a portion connected to the second region 32a toward one end 34a in the longitudinal direction. That is, the diameter of the first region 31a gradually increases toward one end 34a, and the maximum diameter is the diameter D1. The inner diameter surface 35a of the first region 31a expands in a tapered manner. The angle θ of the tapered inner diameter surface 35a of the first region 31a with respect to the inner diameter surface 35b of the second region 32a is 40 degrees or less. In this embodiment, the angle θ is 30 degrees. The third region 33a gradually expands in diameter from a portion connected to the second region 32a toward the other end 34b in the longitudinal direction. That is, the diameter of the third region 33a gradually increases toward the other end 34b. The inner diameter surface of the third region 33a expands in a tapered manner similar to the first region 31a. The angle of the inner diameter surface of the tapered third region 33a relative to the inner diameter surface 35b of the second region 32a is 40 degrees or less. In this embodiment, the angle of the inner diameter surface of the third region 33a relative to the inner diameter surface 35b of the second region 32a is 30 degrees, similar to the first region 31a. In this embodiment, the tapered shape of the first region 31a and the tapered shape of the third region 33a are the same. The longitudinal length of the first region 31a and the longitudinal length of the third region 33a are each less than half the diameter R1 of the ball 20. Specifically, for example, when the diameter R1 of the ball is 5 mm (millimeters), the longitudinal length of the first region 31a and the longitudinal length of the third region 33a are each 2 mm.

[0032] Here, the first region 31a is composed of a compression coil spring. That is, the overall length of the coil spring 30a can be shortened by compressing the first region 31a in the longitudinal direction. The second region 32a and the third region 33a are each composed of a tension coil spring. The second region 32a and the third region 33a are each a tightly-fitted spring. The coil spring 30a is an integrated type. The coil spring 30a is manufactured, for example, by preparing a single spring material, winding the spring material around a rod-shaped member so that the spring material is tightly attached to the second region 32a and the third region 33a and the spring material is spaced apart from the first region 31a, and then performing heat treatment or the like.

[0033] The total length of the coil spring 30a is slightly longer than the longitudinal length of the first circulation path 23a as described above. The coil spring 30a is arranged in the first circulation path 23a by compressing the first region 31a. When the compressing force is released in the first circulation path 23a, the compressed first region 31a tries to return to its original shape. As a result, the coil spring 30a is arranged over the entire area of ​​the first circulation path 23a. That is, no gap is generated in the longitudinal direction of the coil spring 30a in the first circulation path 23a.

[0034] According to the linear motion guide unit 10a, the coil spring 30a includes a first region 31a that is provided in a part of the longitudinal direction and is made of a compression coil spring, and a second region 32a that is provided in the longitudinal direction and is connected to the first region 31a and is made of a tension coil spring. With this configuration, the total length of the coil spring 30a is made longer than the longitudinal length of the first circulation path 23a in advance, and when the coil spring 30a is arranged in the first circulation path 23a, the coil spring 30a can be accommodated in the first circulation path 23a by compressing it in the longitudinal direction using the elastic deformation in the first region 31a. Then, the compression coil spring tries to return to its original shape due to the restoring force, and as a result, the coil spring 30a can be arranged over the entire longitudinal area of ​​the first circulation path 23a. Therefore, it is possible to reduce the possibility of a gap occurring between the connection portion of the first circulation path 23a and the second circulation paths 24a, 25a and the ends 34a, 34b of the coil spring 30a in the first circulation path 23a. As a result, when the ball 20 enters the first circulation path 23a from the second circulation paths 24a, 25a, the end 34a, 34b of the coil spring 30a and the ball 20 are in contact with each other, and wear of the end 34a, 34b of the coil spring 30a can be suppressed. In addition, it is possible to reduce the resistance when the ball 20 enters the first circulation path 23a. Furthermore, by including such a coil spring 30a, it is possible to supply lubricating oil to the ball 20 from the gap of the coil spring 30a over the entire area in the longitudinal direction of the coil spring 30a. Therefore, it is possible to smoothly supply lubricating oil to the ball 20. As described above, such linear motion guide unit 10a allows slider 21a to slide smoothly for a long period of time.

[0035] Furthermore, in the linear motion guide unit 10a, the coil spring 30a is made of metal, so that the coil spring 30a can be used to ensure smooth sliding of the slider 21a even in high-temperature operating environments where it is difficult to use resin springs.

[0036] In this embodiment, the first region 31a is fitted into the first circulation path 23a. The diameter of the second region 32a is smaller than the diameter of the first region 31a. Since the first region 31a is fitted into the first circulation path 23a, when the ball 20 moves from the second circulation path 24a to the first circulation path 23a, the step is reduced, and the ball 20 can smoothly enter from the second circulation path 24a to the first circulation path 23a. In addition, when the ball 20 enters the preload area, the coil spring 30a is elastically deformed by utilizing the radial gap 29a provided between the inner wall surface 28a of the first circulation path 23a and the second region 32a in the first circulation path 23a, and the frictional resistance generated when the ball 20 enters the raceway path 22a, which is the preload area where the preload is applied, from the second circulation paths 24a, 25a, which are the direction change paths, can be absorbed. That is, for example, when the slider 21a moves vertically downward, and the ball 20 is in a staggered position and the pushing direction is not fixed, the frictional resistance can be reduced by the radial elastic deformation of the coil spring 30a in the second region 32a where the gap 29a is provided. Therefore, since there is no need for a force to overcome the large frictional resistance, it is possible to suppress the occurrence of a jammed state due to the ball 20 getting caught.

[0037] In this embodiment, the first region 31a is provided on one end 34a side in the longitudinal direction. With this configuration, the first region 31a can be easily formed, particularly when the coil spring 30a is an integrated type. Therefore, the productivity can be improved.

[0038] In this embodiment, the coil spring 30a is provided on the other end 34b side in the longitudinal direction and includes a third region 33a fitted into the first circulation path 23a. The diameter of the second region 32a is smaller than the diameter of the third region 33a. Since the coil spring 30a is fitted into the first circulation path 23a at both ends 34a, 34b in the longitudinal direction of the coil spring 30a, when the ball 20 moves from each of the pair of second circulation paths 24a, 25a to the first circulation path 23a, the step can be reduced and the ball 20 can smoothly enter the first circulation path 23a from the second circulation paths 24a, 25a. In addition, since the diameter of the second region 32a is smaller than the diameter of the third region 33a, the occurrence of a jammed state due to the ball 20 being caught can be suppressed by utilizing the radial elastic deformation of the second region 32a.

[0039] In this embodiment, the first region 31a gradually expands in diameter from the portion connected to the second region 32a toward one end 34a in the longitudinal direction. This prevents a large step from being formed in the portion of the first region 31a connected to the second region 32a, allowing the ball 20 to move smoothly. This allows the slider 1a to slide more smoothly.

[0040] In this embodiment, the inner diameter surface 35a of the first region 31a is tapered to expand in diameter, which suppresses the formation of steps in the first region 31a and allows the first region 31a to gradually expand in diameter in the longitudinal direction, thereby enabling the slider 21a to slide more smoothly.

[0041] In the present embodiment, the coil spring 30a is an integrated type, which allows the ball 20a to move smoothly inside the coil spring 30a in the first circulation path 23a, and improves the workability during assembly.

[0042] (Embodiment 2) Next, another embodiment, the second embodiment, will be described. FIG. 9 is a schematic perspective view showing a linear guide unit in the second embodiment of the present disclosure. FIG. 10 is a schematic side view showing the linear guide unit shown in FIG. 9. FIG. 10 is a view of the linear guide unit shown in FIG. 9 viewed in the direction indicated by the arrow Y. FIG. 11 is a schematic side view showing a part of the linear guide unit shown in FIG. 9. FIG. 11 is a view of the linear guide unit shown in FIG. 9 viewed from the outer diameter side of the rail. FIG. 12 is a schematic side view of the linear guide unit shown in FIG. 9 with the first end cap, which is one of the end caps, removed. FIG. 12 is also a view viewed in the direction indicated by the arrow Y, similar to FIG. 10. FIG. 13 is a schematic cross-sectional view showing a part of the slider. In FIG. 13, a ball is illustrated from the viewpoint of facilitating understanding. The linear guide unit in the second embodiment basically has the same configuration as the first embodiment, and achieves the same effects. However, the linear guide unit in the second embodiment is different from the first embodiment in the configuration of the rail and the slider.

[0043] 9, 10, 11, 12 and 13, linear motion guide unit 10b in embodiment 2 includes rail 11b, slider 21b, and balls 20 as a plurality of rolling elements. Rail 11b extends straight in the Y direction, which is the longitudinal direction. As with linear motion guide unit 10a in embodiment 1, linear motion guide unit 10b in embodiment 2 also includes balls 20 as rolling elements, thereby simplifying the configuration.

[0044] The rail 11b has a pair of first raceway grooves 15c, 15d extending parallel to each other in the longitudinal direction. In this embodiment, the rail 11b is a solid cylindrical spline shaft. A pair of first raceway grooves 15c, 15d extending parallel to each other in the longitudinal direction is provided on the outer diameter surface 13c of the rail 11b. When viewed from the longitudinal direction, the other first raceway groove 15d is provided at a position rotated 180 degrees with the center of the rail 11b as the rotation center axis 12c with respect to the position where one of the first raceway grooves 15c is provided. The rotation center axis 12c is indicated by a dashed line in FIG. 9. The rail 11b may be hollow cylindrical. That is, the spline shaft is solid cylindrical or hollow cylindrical.

[0045] The slider 21b is attached to the rail 11b so as to be movable relative to the rail 11b. In this embodiment, the slider 21b has a hollow cylindrical shape. The slider 21b is disposed on the outer periphery of the rail 11b.

[0046] The rail 11b has a pair of second raceway grooves 18c, 18d facing the pair of first raceway grooves 15c, 15d. The rail 11b and the slider 21b form an annular path 19c in which a plurality of balls 20 circulate. The annular path 19c includes a raceway path 22c formed of the first raceway grooves 15c and the second raceway grooves 18c, a first circulation path 23c formed in the slider 21b and parallel to the raceway path 22c, and a pair of second circulation paths 24c, 25c formed in the slider 21b and connecting the raceway path 22c and the first circulation path 23c. The annular path including the raceway path formed of the first raceway grooves 15d and the second raceway grooves 18d has a similar configuration. The same applies to the following configurations.

[0047] The slider 21b includes a casing 26b and a pair of end caps 27c, 27d. The casing 26b is provided with a first circulation path 23c, and the casing 26b includes second raceway grooves 18c, 18d. The first end cap 27c is disposed on one side of the casing 26b in the longitudinal direction. In this embodiment, the first end cap 27c is disposed on the rail front end face 14c side in the longitudinal direction. The first end cap 27c is provided with one second circulation path 24c. The second end cap 27d is disposed on the other side of the casing 26b in the longitudinal direction. In this embodiment, the second end cap 27d is disposed on the rail rear end face 14d side in the longitudinal direction. The second end cap 27d is provided with the other second circulation path 25c.

[0048] Next, a more detailed configuration of the slider 21b will be described. The slider 21b includes a metallic coil spring 30c arranged to extend in the longitudinal direction in the first circulation path 23c. The slider 21b also includes a metallic coil spring 30d arranged to extend in the longitudinal direction in the first annular path included in the annular path including the raceway formed by the first raceway groove 15d and the second raceway groove 18d. The configuration of the coil spring 30d is similar to that of the coil spring 30c, and therefore a description thereof will be omitted.

[0049] The coil spring 30c is made of metal. The coil spring 30c is annular. The ball 20 having a diameter R1 can pass through the coil spring 30c. The length of the coil spring 30c is configured to be slightly longer than the length of the first circulation path 23c in a free state, that is, in a state where the coil spring 30c is not disposed in the first circulation path 23c.

[0050] The coil spring 30c includes a first region 31c, a second region 32c, and a third region 33c. The first region 31c is provided on one end 34c side in the longitudinal direction of the coil spring 30c. The third region 33c is provided on the other end 34d side in the longitudinal direction. The first region 31c gradually expands in diameter from a portion connected to the second region 32c in the longitudinal direction toward the one end 34c. That is, the diameter of the first region 31c gradually increases toward the one end 34c. The inner diameter surface 35a of the first region 31a expands in a tapered shape. The third region 33c gradually expands in diameter from a portion connected to the second region 32c in the longitudinal direction toward the other end 34d. That is, the diameter of the third region 33c gradually increases toward the other end 34d. The inner diameter surface of the third region 33c is tapered and expands in diameter, similar to the first region 31c.

[0051] The first region 31c is made of a compression coil spring. That is, the overall length of the coil spring 30c can be shortened by compressing the first region 31c in the longitudinal direction. The second region 32c and the third region 33c are each made of a tension coil spring. The second region 32c and the third region 33c are each a contact spring. Other than that, the configuration of the coil spring 30c is the same as the configuration of the coil springs 30a and 30b in the first embodiment, so the description thereof will be omitted.

[0052] Since the linear guide unit 10b includes the coil springs 30c and 30d of the above configuration, the slider 21b can slide smoothly for a long period of time. The linear guide unit 10b can receive torque in addition to radial load. Therefore, it can be effectively used when radial load and torque are generated.

[0053] (Other embodiments) In the above embodiment, the first region is provided on one end side of the coil spring, but this is not limiting, and the first region does not have to be provided at the end, and may be provided, for example, in the center of the coil spring in the longitudinal direction. Also, a plurality of first regions may be provided in the longitudinal direction, and for example, the first region may be provided on both end sides of the coil spring in the longitudinal direction instead of the third region.

[0054] In the above embodiment, the first region is gradually enlarged in diameter from the portion connected to the second region toward one end, but the present invention is not limited to this. The first region may be configured so that the diameter increases stepwise. The inner diameter surface of the first region may not be tapered, but may be arc-shaped so that the diameter increases toward the end. The same applies to the third region. The coil spring may be configured by arranging multiple different types of springs in the longitudinal direction, for example, the first region as a compression coil spring and the second region as a tension coil spring.

[0055] In the above embodiment, the linear motion guide unit has two raceway grooves or two circulating paths, but the number of raceway grooves or two circulating paths is not limited to two and may be other numbers, for example, four or six.

[0056] It should be understood that the embodiments disclosed herein are illustrative in all respects and are not restrictive in any respect. The scope of the present invention is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0057] 10a, 10b linear motion guide unit, 11a, 11b rail, 12a rail upper end surface, 12b rail lower end surface, 12c rotation center shaft, 13a first rail side surface, 13b second rail side surface, 13c outer diameter surface, 14a, 14c rail front end surface, 14b, 14d rail rear end surface, 15a, 15b, 15c, 15d first raceway groove, 16a, 16b recess, 17, 37a, 37b, 37c, 37d through hole, 18a, 18b, 18c, 18d second raceway groove, 19a, 19c annular path, 20 ball, 21a, 21b slider, 22a, 22c raceway, 23a, 23b, 23c first circulation path, 24a, 24c, 25a, 25c Second circulation path, 26a, 26b casing, 27a, 27c end cap (first end cap), 27b, 27d end cap (second end cap), 28a inner wall surface, 29a gap, 30a, 30b, 30c, 30d coil spring, 31a, 31c first region, 32a, 32c second region, 33a, 33c third region, 34a, 34b, 34c, 34d end portion, 35a, 35b inner diameter surface, 36a upper surface, 36b lower surface, 38a, 38b, 38c, 38d screws.

Claims

1. a rail having a pair of first raceway grooves extending parallel to each other in a longitudinal direction; a slider attached to the rail so as to be relatively movable, the slider having a pair of second raceway grooves facing the pair of first raceway grooves, respectively; A plurality of balls as rolling elements, a circular path through which the rolling elements circulate is formed by the rail and the slider, The circular path includes: a raceway formed by the first raceway groove and the second raceway groove; a first circulation path formed within the slider and parallel to the raceway; a pair of second circulation paths formed in the slider and connecting the raceway and the first circulation path; the slider includes a metallic coil spring disposed in the first circulation path so as to extend in the longitudinal direction, The coil spring is A first region provided in a portion of the longitudinal direction; A second region provided adjacent to the first region in the longitudinal direction, The first region is formed of a compression coil spring, The second region is constituted by a tension coil spring.

2. The first region is fitted into the first circulation path, The linear motion guide unit according to claim 1 , wherein a diameter of the second region is smaller than a diameter of the first region.

3. 3. The linear motion guide unit according to claim 1, wherein the first region is provided on one end side in the longitudinal direction.

4. The coil spring further includes a third region provided on the other end side in the longitudinal direction and fitted into the first circulation path, 4. The linear motion guide unit according to claim 3, wherein a diameter of the second region is smaller than a diameter of the third region.

5. 4. The linear motion guide unit according to claim 3, wherein the first region gradually expands in diameter from a portion connected to the second region in the longitudinal direction toward the one end.

6. 6. The linear motion guide unit according to claim 5, wherein an inner diameter surface of said first region is tapered to increase in diameter.

7. 3. The linear motion guide unit according to claim 1, wherein said coil spring is of an integral type.

8. The rail includes a first rail side and a second rail side extending parallel to each other along the longitudinal direction, The slider is mounted across the rail, The first track groove is provided on a side surface of the first rail, 3. The linear motion guide unit according to claim 1, wherein the other of the first raceway grooves is provided on a side surface of the second rail.

9. The rail is a solid or hollow cylindrical splined shaft, the slider is hollow cylindrical and disposed on an outer circumferential side of the rail, 3. The linear motion guide unit according to claim 1, wherein the pair of first raceway grooves extending parallel to each other in the longitudinal direction are provided on an outer diameter surface of the rail.

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