Rolling guide device

Abstract

The present invention provides a rolling guide device that allows for appropriate setting of the number and material of spacer balls to be inserted, thereby suppressing competition between rolling elements in the unloaded rolling path and achieving excellent operability. [Solution] The linear guide device (rolling guide device) 10 includes a guide rail 1, a slider 2 assembled to the guide rail 1, and a plurality of rolling elements that are rotatably filled into rolling element tracks 23a, 23b, which consist of load rolling elements 22a, 22b and unload rolling elements 21a, 21b. The plurality of rolling elements are composed of a plurality of steel balls 6 and a plurality of spacer balls 16 that are smaller than the load balls and have elasticity, and there is always at least one spacer ball in each unload rolling element, and the total spring constant of all spacer balls present in each unload rolling element is 3.4 (N / mm) or less.

Description

Technical Field

[0001] The present invention relates to a rolling guide device that is used in measuring machines, machine tools, etc., and guides an object that reciprocates in its moving direction.

Background Art

[0002] A linear guide as a rolling guide device generally includes a guide rail provided with rail-side rolling grooves on its left and right side surfaces, a slider provided with slider-side rolling grooves at positions facing the rail-side rolling grooves of the guide rail, a load rolling path formed by the rail-side rolling grooves and the slider-side rolling grooves, and a large number of rolling elements filled in a rolling element return path provided inside the slider, and capable of rolling in these rolling paths. End caps are attached to both axial ends of the slider, and a direction-changing path for changing the direction of the rolling elements is formed inside the end caps. Then, the rolling elements roll in a rolling path composed of an unloaded rolling path consisting of the rolling element return path and the direction-changing path and the above load rolling path, so that the slider moves relative to the guide rail along the axial direction. The rolling elements rolling in the rolling path return to their original positions through the rolling element return path formed inside the slider after changing their directions inside the end caps.

[0003] In such a linear guide, in the load rolling path, the moving directions of the surfaces of adjacent rolling elements are opposite to each other, so the smooth operation of the slider may be hindered by the frictional force generated at the contact portions between the rolling elements. In addition, the unloaded rolling path is formed larger than the diameter of the rolling elements, and the rolling elements in the unloaded rolling path move by being pushed by the rolling elements in the load rolling path. Similar to the load rolling path, competition occurs among the rolling elements, and the operability of the slider deteriorates. Therefore, in order to improve the operability of the rolling guide device, there is disclosed a device in which spacers of various materials are arranged between adjacent rolling elements.

[0004] For example, Patent Document 1 describes a rolling guide device in which a solid lubricating film is formed over at least a portion of the area of ​​an infinite circulation path (rolling path), and spacer balls that are softer than the rolling elements and have a diameter less than or equal to the diameter of the rolling elements are installed between the rolling elements.

[0005] Furthermore, Patent Document 2 proposes a linear rolling guide unit in which the rolling elements are composed of ceramic balls and, for example, urethane balls. In the above linear rolling guide unit, it is preferable to arrange the ceramic balls and urethane balls alternately to prevent damage caused by the ceramic balls rubbing against each other. In addition, since the rolling elements are lighter than steel rolling elements, the responsiveness to high-speed motion is improved, the noise from mutual interference is reduced, and noise is reduced.

[0006] Furthermore, Patent Document 3 discloses a rolling guide device in which the rolling elements are composed of a plurality of first rolling elements and a plurality of second rolling elements (elastic balls) made of an elastic material, and at least one second rolling element is always positioned in the circulation path (unloaded rolling path). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2008-232267 [Patent Document 2] Japanese Patent Application Publication No. 8-61364 [Patent Document 3] International Publication No. 2016 / 190147 [Overview of the project] [Problems that the invention aims to solve]

[0008] By the way, in the rolling guide device described in Patent Document 1 above, the diameter of the spacer ball is said to be less than or equal to the diameter of the rolling element, but the optimal spacer ball diameter has not been selected, and if it becomes too small, the spacer ball may come out of the groove when the slider is removed from the guide rail, and assembly will also become difficult. Furthermore, in the linear rolling guide unit described in Patent Document 2, in order to prevent damage and noise, the number of ceramic balls must be reduced to the same number as the number of urethane balls, which shortens the lifespan. Also, because the number of ceramic balls is small, the overall rigidity of the rolling elements decreases, and the resistance to load in the load rolling path decreases.

[0009] Furthermore, in the rolling guide device described in Patent Document 3, elastic balls are used to mitigate the competition between balls in the unloaded rolling path through their elastic deformation, thereby improving the operability of the slider. However, since the operability of elastic balls varies greatly depending on their material, it is necessary to appropriately select the number and material of the elastic balls.

[0010] The present invention has been made in view of the aforementioned problems, and its objective is to provide a rolling guide device that can appropriately set the number and material of the spacer balls to be inserted, and that can achieve excellent operability by suppressing competition between rolling elements in the unloaded rolling path. [Means for solving the problem]

[0011] The above objective of the present invention is achieved by the following configuration. (1) A first member having a first raceway groove on its side surface, A second member is assembled to the first member and has a second raceway groove facing the first raceway groove, The rolling element track comprises a load-loaded rolling path formed by the first and second raceway grooves, and an unloaded rolling path provided on the second member that connects one end and the other end of the load-loaded rolling path, and a plurality of rolling elements that are filled in such a manner that they can roll freely. A rolling guide device in which one of a first member and a second member relatively moves with respect to the other by rolling of the rolling elements, The plurality of rolling elements are composed of a plurality of load balls and a plurality of spacer balls that are smaller than the load balls and have elasticity, At least one of the spacer balls always exists in the no-load rolling path, A rolling guide device in which the total spring constant of all the spacer balls present in the no-load rolling path is 3.4 (N / mm) or less.

Advantages of the Invention

[0012] According to the present invention, since the load balls and the plurality of spacer balls that are smaller than the load balls and have elasticity are filled in the rolling element rolling path and the total spring constant of all the spacer balls present in the no-load rolling path is defined, the number and material of the spacer balls to be inserted can be appropriately set, and by suppressing the competition of the rolling elements in the no-load rolling path, it is possible to provide a rolling guide device capable of obtaining excellent operability.

Brief Description of the Drawings

[0013] [Figure 1] It is a perspective view showing a rolling guide device according to an embodiment of the present invention with a part of the rolling element rolling path broken. [Figure 2] It is a cross-sectional view schematically showing the rolling guide device shown in FIG. 1. [Figure 3] It is a view schematically showing the III-III cross-section in FIG. 2, where (a) represents before movement and (b) represents after movement. [Figure 4] It is a schematic diagram for explaining the arrangement of two elastic spacer balls in the rolling guide device. [Figure 5] It is a schematic diagram for explaining another arrangement of two elastic spacer balls in the rolling guide device. [Figure 6] It is a schematic diagram for explaining the arrangement of three elastic spacer balls in the rolling guide device. [Figure 7]It is a schematic diagram for explaining the arrangement of six elastic spacer balls in a rolling guide device. [Figure 8] In Test Example 1, it is a graph showing the dynamic frictional force generated when the slider is reciprocated. [Figure 9] In Test Example 2, it is a graph showing the dynamic frictional force generated when the slider is reciprocated. [Figure 10] In Test Example 3, it is a graph showing the dynamic frictional force generated when the slider is reciprocated. [Figure 11] In Test Example 4, it is a graph showing the dynamic frictional force generated when the slider is reciprocated. [Figure 12] In Test Example 5, it is a graph showing the dynamic frictional force generated when the slider is reciprocated. [Figure 13] It is a graph showing the relationship between the load and the deformation amount of the elastic spacer ball for each type of elastic spacer ball. [Figure 14] It is a graph showing the relationship between the number of elastic spacer balls and the number of friction increase times for each type of elastic spacer ball.

Mode for Carrying Out the Invention

[0014] Hereinafter, the rolling guide device according to the present invention will be described in detail based on the drawings. Note that the present invention is not limited to the embodiments described below, and can be appropriately changed without departing from the gist of the present invention.

[0015] First, referring to FIGS. 1 and 2, the rolling guide device according to the embodiment of the present invention will be described. In this embodiment, a linear guide device is exemplified as the rolling guide device.

[0016] The linear guide device (rolling guide device) 10 comprises a metal guide rail (first member) 1 extending in one direction, and a slider (second member) 2 with a substantially U-shaped cross-section that is assembled to straddle the guide rail 1 and is movable in the axial direction relative to the guide rail 1. In this specification, the front-rear direction refers to the direction in which the slider 2 moves along the guide rail 1, and the left-right direction refers to the width direction of the slider 2 attached to the guide rail 1.

[0017] On the left and right sides of the guide rail 1, two upper and lower track grooves (first track grooves) 3a and 3b extending in the axial direction are formed, and a narrow groove 8 is further formed in the lower track groove 3b. The slider 2 comprises a slider body 9 having sleeves 4 on both the left and right sides of the guide rail 1, and a pair of end caps 5 attached to one end and the other end of the slider body 9 in the front-rear direction.

[0018] On the inner surface of the sleeve portion 4 of the slider body 9, two upper and lower track grooves (second track grooves) 7a and 7b are formed on both the left and right sides, opposite to the track grooves 3a and 3b of the guide rail 1. The opposing track grooves 3a and 7a constitute the upper load rolling path 22a, and the track grooves 3b and 7b constitute the lower load rolling path 22b.

[0019] Slider 2 is provided with an upper unloaded rolling path 21a that connects one end and the other end of the upper loaded rolling path 22a, and the upper loaded rolling path 22a and the upper unloaded rolling path 21a constitute the upper rolling element rolling path 23a. Slider 2 is further provided with a lower unloaded rolling path 21b that connects one end and the other end of the lower loaded rolling path 22b, and the lower loaded rolling path 22b and the lower unloaded rolling path 21b constitute the lower rolling element rolling path 23b.

[0020] Furthermore, on the inside of the slider body 9, an upper retainer 25 extending in the front-rear direction of the slider body 9 is mounted on the surface facing the upper surface of the guide rail 1. The retainer 25 is provided with a retaining groove 25a facing the upper load rolling path 22a. Furthermore, a lower retainer 26 extending in the front-to-back direction of the slider body 9 is attached to the inner surface of the sleeve portion 4 of the slider body 9 at a position that fits into the narrow groove 8.

[0021] The end caps 5 are fixed to the front and rear ends of the slider body 9 by bolts 12. The end caps 5 are, for example, injection-molded products of synthetic resin material and are formed in a roughly U-shape in cross-section, similar to the slider body 9. The end cap 5, together with the return guide (not shown), constitutes the direction change path among the unloaded rolling paths 21a and 21b.

[0022] Inside the slider 2, there are a total of four rolling element tracks 23a and 23b, which are filled with multiple steel balls (load-bearing balls) 6 and multiple elastic spacer balls 16 that can roll freely. Hereinafter, the elastic spacer balls will simply be referred to as spacer balls or elastic spacer balls. The spacer balls 16 are smaller than the steel balls 6, for example, 95% of the diameter of the steel balls 6.

[0023] The upper retainer 25 holds the steel balls 6 and spacer balls 16 located in the upper load rolling path 22a by retaining grooves 25a, and the lower retainer 26 holds the steel balls 6 and spacer balls 16 located in the lower load rolling path 22b. In other words, the retainers 25 and 26 are designed to prevent the steel balls 6 and spacer balls 16 from falling from the upper rolling element rolling path 23a and the lower rolling element rolling path 23b when the slider 2 is removed from the guide rail 1. These multiple steel balls 6 and spacer balls 16 then continuously circulate within the rolling element rolling paths 23a and 23b as the guide rail 1 and the slider 2 move relative to each other.

[0024] In this embodiment, the number and material of the spacer balls 16 are determined in order to prevent a decrease in operability due to the steel balls 6 competing with each other in the unloaded rolling path. First, the decrease in operability caused by the competition of the steel balls 6 will be explained in detail below with reference to Figure 3. Figure 3 shows the lower rolling element rolling path 23b of the linear guide device 10 shown in Figures 1 and 2.

[0025] The rolling element track 23b is assumed to be filled only with steel balls 6 as rolling elements. The unloaded rolling element track 21b is a path for achieving infinite circulation of the steel balls 6, and is formed to be larger than the diameter of the steel balls 6, consisting of a combination of straight and curved sections. The loaded rolling element track 22b is sandwiched between the track groove 3b of the guide rail and the track groove 7b of the slider, and is a path in which the steel balls 6 are subjected to preload and external loads. In such a rolling element track 23b, the amount of movement changes between the steel balls 6 entering the unloaded rolling element track 21b from the loaded rolling element track 22b (inlet rolling element) and the steel balls 6 exiting the loaded rolling element track 22b from the unloaded rolling element track 21b (outlet rolling element). Hereinafter, this change in the amount of movement will be referred to as the change in the amount of movement in and out.

[0026] The steel balls 6 located within the loaded rolling path 22b rotate and revolve due to the movement of the slider 2. The steel balls 6 located within the unloaded rolling path 21b are pushed and moved by the steel balls 6 in the loaded rolling path 22b. Figures 3(a) and 3(b) show the same rolling element rolling path 23b, but the position of the reference steel ball 6a is slightly shifted before and after the slider 2 moves in the direction indicated by the arrow in the figure. As described above, the steel balls 6 within the unloaded rolling path 21b are pushed and moved, so they are arranged without gaps. At this time, the number of steel balls 6 present within the unloaded rolling path 21b differs slightly depending on the position of the reference steel ball 6a. For example, in Figure 3(a), there are 10.42 steel balls 6 in the unloaded rolling path 21b, and in Figure 3(b), there are 10.4 steel balls 6. As the slider moves in the direction indicated by the arrow, the number of steel balls 6 that can exist in the unloaded rolling path 21b decreases, causing a change in the amount of movement in and out, and preventing the steel balls 6 in the loaded rolling path 22b from moving at a constant speed. As a result, the steel balls 6 become temporarily less able to rotate, and the apparent frictional force between the slider 2 and the guide rail 1 increases momentarily.

[0027] Therefore, in this embodiment, elastic spacer balls 16 are placed in the unloaded rolling paths 21a and 21b to prevent this instantaneous change in frictional force. If only steel balls 6, which are almost rigid, are used, even a slight difference in the number of steel balls 6 that can be present in the unloaded rolling paths 21a and 21b will interfere with the movement of the steel balls 6 present in the loaded rolling paths 22a and 22b. However, by placing elastic spacer balls 16 in the unloaded rolling paths 21a and 21b, this slight change in the amount of movement in and out can be absorbed by the elasticity of the spacer balls 16, and thus does not interfere with the movement of the steel balls 6 in the loaded rolling paths 22a and 22b. Accordingly, it is necessary to always have at least one spacer ball 16 in the unloaded rolling paths 21a and 21b.

[0028] The number and arrangement of elastic spacer balls in the rolling guide device will be explained using Figures 4 to 7. For simplicity, Figures 4 to 7 show a rolling element rolling path 23 composed of a loaded rolling path 22 and an unloaded rolling path 21 having the same inner diameter as the loaded rolling path 22. In the first embodiment shown in Figure 4, the rolling element track 23 is filled with a plurality of steel balls 6 and two elastic spacer balls 16, with the spacer balls 16 arranged at approximately equal intervals between the steel balls 6. In this case, there are always 1 to 2 spacer balls 16 in the unloaded rolling track 21, and changes in the amount of spacer balls entering and leaving can be absorbed elastically, thus enabling smooth operation.

[0029] On the other hand, in the example shown in Figure 5, similar to the first embodiment described above, two elastic spacer balls 16 are inserted into the rolling element track 23, but both are located within the loaded rolling track 22. When the steel balls 6 and spacer balls 16 are arranged in this manner, there is a period in which there are no spacer balls 16 in the unloaded rolling track 21, and during this period, the elasticity of the spacer balls 16 makes it impossible to absorb changes in the amount of balls moving in and out.

[0030] Therefore, as described above, it is preferable that the spacer balls 16 be arranged at approximately equal intervals between the steel balls 6. However, even if they are not at approximately equal intervals, the design can be made such that the spacer balls 16 are always located within the unloaded rolling path 21, taking into consideration the lengths of the loaded rolling path 22 and the unloaded rolling path 21 and the diameter of the steel balls 6. In other words, when there are two spacer balls 16, the length of the load rolling path 22 is L (mm), and the diameter of the spacer ball 16 is D. W When (mm), (L / D W By arranging (-1) or more steel balls 6 between the spacer balls 16, at least one spacer ball 16 is always present in the unloaded rolling path 21.

[0031] In the second embodiment shown in Figure 6, the rolling element track 23 is filled with multiple steel balls 6 and three elastic spacer balls 16, with the spacer balls 16 arranged at approximately equal intervals between the steel balls 6. In this case, there are always 2 to 3 spacer balls 16 in the unloaded rolling track 21, which reduces the effect of changing the amount of movement in and out compared to the first embodiment, and enables smoother operation. Note that, in relation to the total length of the rolling track 23, the number of steel balls arranged may be less than described above in some sections, but even in this case, there will be one or more spacer balls in the unloaded rolling track 21.

[0032] In the third embodiment shown in Figure 7, the rolling element track 23 is filled with a plurality of steel balls 6 and six elastic spacer balls 16, with the spacer balls 16 arranged at approximately equal intervals between the steel balls 6. In this case, there are always 4 to 5 spacer balls 16 in the unloaded rolling track 21, which provides a greater effect in reducing changes in the amount of spacer balls entering and leaving the track compared to the first and second embodiments. Furthermore, since spacer balls 16 are always present in the curved sections (direction change sections) of the unloaded rolling track 21, even better operability can be obtained. In this invention, "approximately equal spacing" means that the number of steel balls 6 between adjacent spacer balls 16 is n, n+1, or n+2 (where n is any integer).

[0033] However, even if spacer balls 16 are arranged as shown in the first to third embodiments above, depending on the material of the spacer balls 16, it may not be possible to completely absorb changes in the amount of movement in and out. Therefore, in this embodiment, the total spring constant of all spacer balls 16 present in the unloaded rolling paths 21a and 21b is defined, and the number and material of the spacer balls 16 are determined so as to fall within this defined range. Specifically, the total spring constant of all spacer balls 16 present in the unloaded rolling paths 21a and 21b is set to 3.4 (N / mm) or less. This suppresses the generation of frictional force due to changes in the amount of movement in and out, and allows for excellent operability.

[0034] Here, the spring constant k (N / mm) of a single spacer ball can be calculated by measuring the elastic amount (deformation) x (mm) of the spacer ball when it is placed between two steel balls and the steel balls are brought closer together by a force F (N), and then using the following formula (1). k = F / x ... (1) And the total spring constant K of all the spacer balls 16 present in the unloaded rolling path 21 TOT This can be calculated by the following formula (2), where n is the number of spacer balls 16 in the unloaded rolling path 21. 1 / K TOT =1 / k+1 / k+···+1 / k=n / k···(2) In other words, if you insert several identical elastic spacers, K TOT =k / n. As the number of n increases, the value of K when there are n+1 elements increases. TOT The change will be small.

[0035] In this invention, the number of spacer balls 16 is two or more, but if the number of spacer balls 16 becomes too large, the overall load capacity of the rolling element will decrease, so it is preferable that the number of spacer balls 16 be less than the number of steel balls 6.

[0036] Furthermore, the diameter of the spacer ball 16 must be smaller than that of the steel ball 6. If the diameter of the spacer ball 16 is greater than or equal to the diameter of the steel ball 6, it will create resistance when the spacer ball 16 moves from the unloaded rolling path 21 to the loaded rolling path 22, significantly degrading the operability. Also, generally, elastic bodies increase in diameter due to swelling and thermal expansion, so the diameter of the spacer ball 16 should be set not to be greater than that of the steel ball (loaded ball) 6, taking swelling and thermal expansion into consideration, so that it can move without resistance.

[0037] On the other hand, as shown in Figures 1 and 2, the linear guide device 10 is held by retainers 25 and 26 to prevent the steel balls 6 and spacer balls 16 from falling from the rolling element tracks 23a and 23b when the slider 2 is removed from the guide rail 1. The spacer balls 16 are elastic and have a smaller diameter than the steel balls 6, but if the diameter is made too small, it becomes difficult to hold the spacer balls 16 with the retainers 25 and 26, and as a result the assembly work becomes complicated. Therefore, in the present invention, in order to improve the retention of the spacer balls 16 and to facilitate the assembly work, it is preferable that the diameter of the spacer balls 16 be 90% or more of the diameter of the steel balls (load balls).

[0038] In this embodiment, the material of the spacer ball 16 is not particularly limited as long as it is elastic, but a softer material will provide better operability. Therefore, considering elasticity and durability, it is preferable that the spacer ball 16 be made of one of the following materials: synthetic rubber (acrylic rubber, nitrile rubber, etc.), resin (polyacetal, etc.), and thermoplastic elastomer. Alternatively, a spacer ball 16 with elasticity can be used by modifying its shape.

[0039] In the above embodiment, a steel ball 6 was used as the load ball, but the load ball is not limited to metal and may be made of ceramic or the like. Also, in the above embodiment, a linear guide device was given as an example of a rolling guide device, but the present invention can also be applied to a ball screw. [Examples]

[0040] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0041] Using a linear guide system (manufactured by NSK Ltd.: NH25AN, steel ball diameter: 4.7625 mm, number of steel balls: approximately 30 per row), the type and number of elastic spacer balls inserted in place of the steel balls were varied to observe the change in kinetic friction force during slider movement. Specifically, the kinetic friction force (N) during one reciprocal movement of the slider was measured, and the number of occurrences of instantaneous changes in kinetic friction force (friction increase) was observed. An instantaneous change in kinetic friction force was defined as a change of 25% or more from the average value at a position where there was no increase in friction. In the linear guide device, the sliders and guide rails were all identical, with only the material and number of elastic spacer balls being varied. Furthermore, to more clearly demonstrate the effect of the spacer balls, dust seals were removed, and sliders with poor operating characteristics were used due to the shape of the groove ends of the load rolling path. The lubricating oil had a kinematic viscosity of 68 mmHg. 2 A slider with a speed of 1 m / min and a stroke of 500 mm was used.

[0042] Figure 8 shows the operating characteristics of Test Example 1, in which only steel balls were used as rolling elements (number of elastic spacer balls: 0). Figures 9 to 11 show the measurement results of the operating characteristics of Test Examples 2 to 4, in which elastic spacer balls made of thermoplastic elastomer with a spring constant of 20 (N / mm). Figure 9 shows Test Example 2, in which there were 4 elastic spacer balls (2 to 3 in the unloaded rolling path), Figure 10 shows Test Example 3, in which there were 8 elastic spacer balls (4 to 5 in the unloaded rolling path), and Figure 11 shows Test Example 4, in which there were 10 elastic spacer balls (6 in the unloaded rolling path).

[0043] As shown in Figures 8 to 11, in Test Example 1, numerous friction increases were measured in a short period. On the other hand, in Test Examples 2 to 4, the number of friction increases was reduced compared to Test Example 1, which used only steel balls. In a linear guide device, approximately 40% of the total length of the rolling element track (loaded track and unloaded track) is the loaded track, i.e., the region where the rolling elements are sandwiched in the grooves and subjected to external load, and the remaining region is the unloaded track. In Test Examples 2 to 4, since the elastic spacer balls are arranged at approximately equal intervals, approximately 60% of the rolling elements filling the rolling element track are present in the unloaded track. Therefore, Test Examples 2 to 4 are examples in which at least one elastic spacer ball is present in the unloaded track, indicating that the competition between rolling elements in the unloaded track was absorbed by the spacer ball. Furthermore, as the number of elastic spacer balls increased, the number of friction increases decreased. In Test Example 4, where there were 10 elastic spacer balls, the number of friction increases became zero, and the operating characteristics were significantly improved.

[0044] Figure 12 shows the results of measuring the operating characteristics of Test Example 5, which uses an elastic spacer ball made of nitrile rubber (NBR: acrylonitrile-butadiene rubber) with a hardness of 70 and a spring constant of 3.3. In Test Example 5, two elastic spacer balls were used. Because nitrile rubber is softer than elastomer, the presence of only one elastic spacer ball in the unloaded rolling path resulted in zero friction increase, and the operating characteristics were significantly improved.

[0045] Figure 13 shows the deformation of elastic spacer balls made of thermoplastic elastomer (elastomer balls) and elastic spacer balls made of nitrile rubber (rubber balls) when a load is applied. Figure 14 shows the results of measuring the operating characteristics by changing the number of each elastic spacer ball. The number of friction increases shown in Figure 14 is the average value obtained by measuring the number of times the friction increase occurs when the slider is moved back and forth once, and performing this over three back and forth movements.

[0046] As shown in Figure 13, the rubber ball deformed approximately six times more than the elastomer ball under the same load. Furthermore, as shown in Figure 14, when two rubber balls were used, the total spring constant of the rubber balls present in the unloaded rolling path was always 3.4 (N / mm) or less, resulting in zero friction rises and excellent operating characteristics of the linear guide device. Furthermore, even when using elastomer balls with a high spring constant, the number of friction rises was significantly reduced as the number of inserted balls increased. By using 10 elastomer balls, the total spring constant of the elastomer balls present in the unloaded rolling path was always 3.4 (N / mm) or less, resulting in excellent operating characteristics.

[0047] Thus, when the number of spacer balls to be inserted is determined, an appropriate material can be selected so that the total spring constant is 3.4 (N / mm) or less. When the material is determined, an appropriate number can be selected so that the total spring constant is 3.4 (N / mm) or less. Therefore, a rolling guide device with excellent operability can be obtained under any conditions.

[0048] Generally, in linear guide devices, deterioration of operating characteristics is primarily caused by the change in the amount of ball movement described above. In all of the above test examples 1 to 5, sliders manufactured with specifications that result in poor operating characteristics were used. Therefore, by using sliders that are normally used, better operating characteristics than those in test examples 1 to 5 can be obtained. In other words, if the total deformation amount of the elastic spacer balls present in the unloaded rolling path is 0.3 mm or more at 1 N, good operating characteristics can be obtained even when applied to various linear guide devices.

[0049] As described above, the following matters are disclosed in this specification: (1) A first member having a first raceway groove on its side surface, A second member is assembled to the first member and has a second raceway groove facing the first raceway groove, The rolling element track comprises a load-loaded rolling path formed by the first and second raceway grooves, and an unloaded rolling path provided on the second member that connects one end and the other end of the load-loaded rolling path, and a plurality of rolling elements that are filled in such a manner that they can roll freely. A rolling guide device in which one of the first member and the second member moves relative to the other as the rolling element rolls, The aforementioned plurality of rolling elements are composed of a plurality of load balls and a plurality of spacer balls that are smaller than the load balls and have elasticity. At least one of the spacer balls is always present in the unloaded rolling path. A rolling guide device in which the total spring constant of all spacer balls present in the unloaded rolling path is 3.4 (N / mm) or less. This structure allows for appropriate setting of the number and material of the spacer balls to be inserted, and by suppressing competition between rolling elements in the unloaded rolling path, excellent operability can be achieved.

[0050] (2) The rolling guide device according to (1), wherein the spacer ball is made of one selected from synthetic rubber, resin, and thermoplastic elastomer. With this configuration, the spacer ball can be made to have both elasticity and durability. (3) The rolling guide device according to (1) or (2), wherein the diameter of the spacer ball is 90% or more of the diameter of the load ball. This structure makes the assembly of the slider easier. (4) The rolling guide device according to any one of items (1) to (3), wherein the number of spacer balls is less than the number of load balls. This configuration helps to suppress the reduction in the overall load capacity of the rolling elements. (5) The rolling guide device according to any one of items (1) to (4), wherein the plurality of spacer balls are arranged at approximately equal intervals between the load balls. With this configuration, the probability of spacer balls always being placed in curved sections within the unloaded rolling path increases. As a result, the spacer balls can absorb changes in the amount of movement in and out of the curved sections, thereby improving operability. [Explanation of symbols]

[0051] 1 Guide rail (first component) 2. Slider (second component) 3a, 3b Track grooves (first track grooves) 4 Sleeves 5 End caps 6,6a Steel ball (loaded ball) 7a, 7b Track grooves (second track grooves) 9. Slider body 10. Linear guide device (rolling guide device) 16 Spacer Balls 21,21a,21b No-load rolling path 22,22a,22b Load rolling path 23,23a,23b Rolling element rolling path 25,26 Cage

Claims

1. A first member having a first raceway groove on its side, A second member is assembled to the first member and has a second raceway groove facing the first raceway groove, The rolling element track comprises a load-loaded rolling path formed by the first and second raceway grooves, and an unloaded rolling path provided on the second member that connects one end and the other end of the load-loaded rolling path, and a plurality of rolling elements that are filled in such a manner that they can roll freely. A rolling guide device in which one of the first member and the second member moves relative to the other as the rolling element rolls, The aforementioned plurality of rolling elements are composed of a plurality of load balls and a plurality of spacer balls that are smaller than the load balls and have elasticity. At least one of the spacer balls is always present in the unloaded rolling path. A rolling guide device in which the total spring constant of all spacer balls present in the unloaded rolling path is 3.4 (N / mm) or less.

2. The rolling guide device according to claim 1, wherein the spacer ball is made of one selected from synthetic rubber, resin, and thermoplastic elastomer.

3. The rolling guide device according to claim 1, wherein the diameter of the spacer ball is 90% or more of the diameter of the load ball.

4. The rolling guide device according to claim 1, wherein the number of spacer balls is less than the number of load balls.

5. The rolling guide device according to claim 1, wherein the plurality of spacer balls are arranged at substantially equal intervals between the load balls.

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