JP2022152777A - Liner motion guide device - Google Patents

Abstract

To provide a linear motion guide device having a cap which can block a rail attachment hole of a guide rail without forming a step, capable of facilitating the attachment work of the cap, also capable of preventing the excessive intrusion and sinking of the cap, and thereby, capable of maintaining the traveling accuracy and the stop position accuracy of a slider by suppressing the accumulation of foreign matters such as cut powder and chips on an upper face of the guide rail.SOLUTION: A rail attachment hole 4 of a guide rail 3 of a linear motion guide device 1 comprises a stem accommodation part 4a for accommodating a stem part of a bolt 6, and a counterbored part 4b for accommodating a head part of the bolt 6. A cap 41 for blocking an opening of the rail attachment hole 4 is arranged in the counterbored part 4b of the rail attachment hole 4, a cylinder part 43 of the cap 41 has a cap fixing protrusion 45 which is formed larger than an inside diameter of the counterbored part 4b along its peripheral edge part, and a cap fixing groove 47 which can be engaged with the cap fixing protrusion 45 is formed in an internal peripheral face of the counterbored part 4b.SELECTED DRAWING: Figure 6B

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear guide device used in machine tools, injection molding machines, semiconductor manufacturing equipment, etc., as a linear guide for guiding an object in reciprocating linear motion in its moving direction.

Conventionally, a linear guide device (linear guide device) used in a machine tool or the like generally has a guide rail provided with rail-side rolling grooves on the left and right sides, and the rail-side rolling grooves of the guide rail face each other. It fills the slider with the slider-side rolling groove at the position, the load rolling path composed of the rail-side rolling groove and the slider-side rolling groove, and the rolling element return path provided inside the slider. and a large number of rolling elements that can roll on the rolling path. End caps are attached to both ends of the slider in the axial direction, and direction changing paths for changing the direction of the rolling elements are formed in the end caps. As the rolling elements roll on the rolling path, the slider moves relative to the guide rail along the axial direction. The rolling elements rolling in the rolling path change direction in the end caps and then return to their original positions through rolling element return passages formed in the slider.

A rail mounting hole is formed in the guide rail because the guide rail is attached to a mounting portion of a machine base of a machine tool, a cutting machine, or the like using bolts. The rail mounting hole has a countersunk portion for housing the head of the bolt and a shaft housing portion for housing the shaft of the bolt. The head of the bolt is configured so that it does not protrude from the upper surface of the guide rail when fixed to the surface.

In the linear motion guide device configured in this manner, foreign matter such as cutting dust and chips generated by use of a machine tool or cutting machine tends to accumulate on the upper surface and side surfaces of the guide rail. In particular, on the upper surface of the guide rail, there is a problem that foreign matter tends to accumulate on the head of the bolt sunk in the counterbore. If left unattended, foreign matter accumulated on the bolt head will come into contact with the end cap as the slider moves, damaging the end cap or entering the inside of the slider, resulting in a smooth operation of the rolling elements inside the slider. May impede rolling. As a result, the travel accuracy and stop position accuracy of the slider may be degraded.

Therefore, recently, various linear guide devices having caps for closing the openings of the rail mounting holes have been proposed. For example, Patent Literature 1 discloses a cap having a short cylindrical portion composed of a large diameter portion and a small diameter portion, and a plurality of projections integrally formed along the outer peripheral surface of the large diameter portion at equal intervals. there is The cap is embedded in the counterbore with an O-ring attached to the stepped portion between the large diameter portion and the small diameter portion. At this time, the O-ring is elastically deformed and fixed to the counterbore, and the projection is also scraped off or elastically deformed to be fixed to the counterbore, so that the fixing force to the counterbore can be maintained.

Further, in Patent Document 2, a cylindrical body provided with a slit in the axial direction, a protrusion projecting from the lower part of the cylindrical body to the outer periphery, and a cap lid portion having a partially reduced thickness are provided. and an elastic covering member covering a lid portion of the cap body and having an outer diameter larger than that of the cap body. The cap can be firmly attached by fitting the protrusions on the outer periphery to the inner peripheral surface of the rail mounting hole. In addition, since the body has slits, it not only provides springiness, but also absorbs dimensional differences and facilitates the discharge of air during fitting, thereby facilitating mounting.

Furthermore, Patent Document 3 discloses a cap having an interference portion on the outer peripheral portion, wherein the interference portion is arranged axially below the top surface, and the dimension from the top surface to the interference portion is the chamfered portion of the counterbore. A cap is described that is configured to be greater than or equal to the axial dimension of . According to this structure, when the cap is fitted into the rail mounting hole, the interference portion is scraped off at the boundary between the chamfered portion of the rail mounting hole and the inner diameter surface, so that the shavings are completely separated from the cap. This makes it easier to remove shavings.

JP 2015-105685 A Japanese Utility Model Publication No. 8-7138 Japanese Patent Application Laid-Open No. 2002-227838

By the way, the caps disclosed in the above Patent Documents 1 to 3 are inserted into the rail mounting holes by placing a backing plate on the upper part of the cap and hitting the backing plate little by little with a hammer or the like. The insertion position of the cap is adjusted so that the upper surface of the rail and the upper surface of the rail are substantially flush with each other. However, the method of attaching the cap while adjusting the position in this way has the problem that the attachment takes time and effort. In addition, since the cap is fitted manually, the cap may be inserted deeper than the desired position, or the cap may sink due to aging. As a result, a step is formed between the upper surface of the guide rail and the upper surface of the cap, which causes a problem that foreign matter tends to accumulate on the upper surface of the cap.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a cap capable of closing a rail mounting hole of a guide rail without a step, thereby facilitating the mounting operation of the cap. At the same time, it is possible to prevent excessive insertion and sinking of the cap, thereby suppressing the accumulation of foreign matter such as cutting powder and chips on the upper surface of the guide rail, thereby improving the travel accuracy and stop position accuracy of the slider. To provide a linear motion guide device that can be maintained.

The above objects of the present invention are achieved by the following configurations.
(1) A guide rail having a plurality of rail mounting holes through which bolts can be inserted and attached to a mounting portion using the bolts; and a slider that can move relative to the guide rail, wherein the rail mounting hole of the guide rail includes a shaft receiving portion for receiving the shaft portion of the bolt and a counterbore for receiving the head portion of the bolt. and a countersunk portion of the rail mounting hole is provided with a cap that closes the opening of the rail mounting hole, and the cap includes a cylindrical portion having a smaller diameter than the inner diameter of the countersunk portion and the cylindrical portion. and a disk-shaped cover portion that closes the opening of the rail mounting hole. a cap fixing projection formed to be larger than the inner diameter of the counterbore, and a cap fixing groove engageable with the cap fixing projection is formed on the inner peripheral surface of the counterbore, Linear guide device.
(2) The linear motion guide device according to (1), wherein the cap has guide projections provided along the periphery of the opening end of the cylindrical portion.
(3) The linear guide device according to (1), wherein the cap fixing projection is formed along the peripheral edge of the opening end of the cylindrical portion.
(4) The linear motion guide device according to any one of (1) to (3), wherein the cap has a plurality of slits provided on the peripheral edge of the open end of the cylindrical portion.
(5) The linear motion guide device according to any one of (1) to (4), wherein the lid portion protrudes from the outer peripheral portion toward the central portion.
(6) The guide rail has an adapter mounting hole formed continuously from the shaft accommodating portion, which can be fitted with an adapter having at least the countersunk portion, and the adapter is fitted into the adapter mounting hole. The linear guide device according to any one of (1) to (5), wherein the rail mounting holes are formed by

According to the present invention, there is provided a cap capable of closing the rail mounting hole of the guide rail without a step, the mounting operation of the cap can be facilitated, and excessive insertion and sinking of the cap can be prevented. As a result, it is possible to provide a linear motion guide device capable of suppressing the accumulation of foreign matter such as cutting powder and chips on the upper surface of the guide rail and maintaining the travel accuracy and stop position accuracy of the slider. can.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows 1st Embodiment of the linear guideway which concerns on this invention. FIG. 2 is a schematic top view showing a part of the top surface of the linear guide device shown in FIG. 1 ; FIG. 2 is a schematic front view of the linear guide device shown in FIG. 1 with a part of the front removed; FIG. 2 is a back view of the end cap of the linear guide device shown in FIG. 1; It is a top view of the cap of 1st Embodiment. 5B is a side view of the cap shown in FIG. 5A; FIG. FIG. 4 is a cross-sectional view explaining a rail mounting hole shown in FIG. 3; 6B is a cross-sectional view illustrating bolts and caps attached to the rail attachment holes shown in FIG. 6A; FIG. 6C is an enlarged cross-sectional view of the A portion of FIG. 6B; FIG. FIG. 11 is an enlarged cross-sectional view showing a first modified example of a cap fixing groove; FIG. 11 is an enlarged cross-sectional view showing a second modification of the cap fixing groove; FIG. 5 is a side view of the cap of the second embodiment of the linear guide device according to the present invention; FIG. 9 is a cross-sectional view illustrating a rail mounting hole into which the cap shown in FIG. 8 is fitted; FIG. 11 is a side view illustrating a cap of a linear guide device according to a third embodiment of the present invention; It is a sectional view explaining a rail attachment hole of a 4th embodiment of a linear guideway concerning the present invention.

Hereinafter, each embodiment of a linear guide device according to the present invention will be described in detail based on the drawings.

(First embodiment)
First, a first embodiment of a linear guide device according to the present invention will be described with reference to FIGS. 1 to 7. FIG.

As shown in FIG. 1, the linear motion guide device 1 of this embodiment is mounted so as to straddle a guide rail 3 extending in the axial direction, and is movable relative to the guide rail 3 in the axial direction. and a slider 20 having a substantially C-shaped cross section. In the specification of the present application, the axial direction (also referred to as the front-rear direction) indicates the direction in which the slider 20 moves along the guide rail 3 (vertical direction in FIG. represents the width direction (horizontal direction in FIG. 2) of the slider 20 that is mounted.

The guide rail 3 is made of metal, and two rail-side rolling grooves (rail-side raceway surfaces) 5 are formed along the axial direction of the guide rail 3 on left and right side surfaces 3b thereof. The guide rail 3 has a plurality of rail mounting holes 4 passing through the guide rail 3 in the height direction. A fixing bolt 6 (see FIG. 6B) is inserted, and a cap 41 is fitted in the rail mounting hole 4 to close the opening.

2 to 4, the slider 20 includes a slider body 21 having sleeves 22 on both left and right sides of the guide rail 3, and a pair of end caps attached to one end and the other end of the slider body 21 in the front-rear direction. 31, 31, a plurality of return guides 17 incorporated in these end caps 31, 31, and a pair of side seals 35, 35 for sealing gaps between the guide rail 3 and the end caps 31, 31. Prepare. Two slider-side rolling grooves (slider-side raceway surfaces) 10 facing the rail-side rolling grooves 5 of the guide rail 3 are formed in the sleeve portion 22 of the slider body 21 .

The slider body 21 has a slider side rolling groove 10 and a rolling element return path 28 . The slider-side rolling grooves 10 are formed on the inner side surfaces of both sleeves 22 of the slider body 21 and face the rail-side rolling grooves 5 . A rolling path 24 is formed. The rolling element return path 28 extends through the thick portions of both sleeves 22 in the axial direction of the guide rail 3 . The top surface of the slider body 21 is provided with a plurality of screw holes 33 into which bolts for fixing a driven body such as a table to the slider 20 are screwed.

The end caps 31 are joined to the front and rear ends of the slider body 21, respectively, as shown in FIG. The end cap 31 is, for example, an injection-molded product of a synthetic resin material, and is formed to have a substantially C-shaped cross section like the slider body 21 . In the left and right sleeve portions 30 of the end cap 31, a semi-disk-shaped concave portion 15 is formed in two upper and lower stages on the abutment end surface 31a facing the end surface 21a of the slider body 21, and a semi-disk-shaped upper and lower two stages are formed. A semi-cylindrical groove 16 is formed across the center of the recess 15 . A semi-cylindrical return guide 17 is fitted in the semi-cylindrical recessed groove 16 to form a semi-doughnut-shaped direction change path 29 .

The direction changing path 29 connects the load rolling path 24 and the rolling element return path 28 . is configured. In the rolling element rolling path 27, for example, a plurality of steel balls 34 as rolling elements are loaded. It circulates endlessly while rolling inside 27 .

Further, the end cap 31 is provided with a plurality of mounting screw insertion holes 25 , and guide protrusions 36 are provided on the periphery of the mounting screw insertion holes 25 . Insertion holes (not shown) are also formed at positions facing the guide projections 36 in the slider body 21 , and the guide projections 36 of the end cap 31 are fitted into the insertion holes of the slider body 21 . Therefore, the joining accuracy between the two is ensured. A mounting screw 26 is inserted through the mounting screw insertion hole 25 toward the slider body 21 , and the end cap 31 is fastened to the slider body 21 with the mounting screw 26 . A side seal 35 is fixed to the slider body 21 with a mounting screw 26 while being in contact with the axially outer side of the end cap 31 .

As shown in FIGS. 5A and 5B, the cap 41 is a disk-shaped lid portion connected to a hollow cylindrical portion 43 and an end portion of the cylindrical portion 43 in the axial direction of the cylinder to block the opening of the rail mounting hole 4. 44 and is formed in a bottomed cylindrical shape. The cylindrical portion 43 is provided with an annular cap-fixing projection 45 along the entire circumference of its peripheral edge, and a guiding projection 46 along the peripheral edge of the opening end. In addition, a plurality of slits 43a are provided in the opening end peripheral portion of the cylindrical portion 43. As shown in FIG. Further, in this embodiment, the tip of the cap fixing projection 45 is formed to have an arcuate cross-section. The upper surface of the lid portion 44 is formed in a planar shape orthogonal to the cylindrical axis. The direction of the cylinder axis is the direction of the central axis of the cylinder portion 43, which is the vertical direction in FIG. 5B.

6A to 6C, the rail mounting hole 4 of the guide rail 3 includes a shaft housing portion 4a for housing the shaft portion of the bolt 6, a counterbore portion 4b for housing the head portion of the bolt 6, Prepare. A cap fixing groove 47 engageable with a cap fixing projection 45 is formed along the entire circumference at a predetermined position on the inner peripheral surface of the counterbore portion 4b. Although the cap fixing groove 47 in this embodiment is formed to have a V-shaped cross section, it is not limited to this, and the shape is not limited as long as it is a shape that allows the cap fixing projection 45 to engage with it. For example, when the tip of the cap fixing projection 45 has an arcuate cross-section, the cap fixing groove 47 may have an arcuate cross-section or a rectangular cross-section. Also, the method for processing the cap fixing groove 47 is not particularly limited, but for example, arc cutting (planet processing) using an inner diameter grooving tool such as an end mill can be mentioned. Moreover, the cap fixing grooves 47 may be formed so as to be scattered at predetermined intervals in the circumferential direction along the inner peripheral surface of the counterbore portion 4b.

The outer diameter of the cylindrical portion 43 of the cap 41 is formed smaller than the inner diameter d of the counterbore portion 4b. The outer diameter of the lid portion 44 of the cap 41 is larger than or equal to the inner diameter d of the counterbore portion 4b. Further, the outer diameter of the cap fixing projection 45 is formed to be larger than the inner diameter d of the counterbore portion 4b. Further, the outer diameter of the guiding protrusion 46 is formed larger than the inner diameter d of the counterbore 4b and smaller than the outer diameter of the cap fixing protrusion 45. As shown in FIG.

When fixing the guide rail 3 to the mounting surface 7 , the bolt 6 is inserted into the rail mounting hole 4 and screwed into the mounting surface 7 . As a result, the head of the bolt 6 is locked by the counterbore 4b, and the guide rail 3 is fixed to the mounting surface 7. As shown in FIG. After that, the opening of the rail mounting hole 4 provided in the guide rail 3 is closed by inserting the cap 41 into the rail mounting hole 4 to the position where the cap fixing projection 45 and the cap fixing groove 47 are engaged. .

According to the linear guide device 1 of the present embodiment configured as described above, the cap 41 is inserted into the rail mounting hole 4 until the upper surface of the lid portion 44 of the cap 41 and the upper surface of the guide rail 3 are flush with each other. The cap fixing groove 47 and the cap fixing protrusion 45 are configured to engage with each other when they are inserted. Therefore, in the fitting operation of the cap 41 , the cap 41 can be fixed at the position where the cap fixing projection 45 is engaged with the cap fixing groove 47 . As a result, the opening of the rail mounting hole 4 of the guide rail 3 can be closed with the cap 41 without a step, and the mounting work of the cap 41 can be facilitated. In addition, once the cap fixing protrusion 45 and the cap fixing groove 47 are engaged with each other, they are not easily disengaged. Therefore, the cap 41 may be inserted to a desired depth or more due to changes over time or when the cap 41 is attached. and sinking due to aging can be prevented. Therefore, since there is no step on the upper surface of the guide rail 3, foreign matter such as cutting dust and chips is prevented from accumulating on the upper surface of the guide rail 3 (cap 41), thereby improving the travel accuracy and stopping position of the slider. Accuracy can be maintained.

Further, according to the linear motion guide device 1 of the present embodiment, since the lid portion 44 of the cap 41 is tightly fitted into the rail mounting hole 4, after the cap 41 is mounted in the rail mounting hole 4, It is possible to prevent the cap 41 from coming off.

Further, according to the linear motion guide device 1 of the present embodiment, since the guide protrusions 46 are formed on the periphery of the opening end of the cylindrical portion 43 of the cap 41, when the cap 41 is attached, the cap 41 is positioned in the rail attachment hole 4. It is possible to prevent the cylindrical portion 43 of the cap 41 from being obliquely inserted into the cap 41 and prevent deformation of the cylindrical portion 43 .

Further, according to the linear motion guide device 1 of the present embodiment, since a plurality of slits 43a are provided in the opening end peripheral portion of the cylindrical portion 43 of the cap 41, when the cap 41 is inserted into the rail mounting hole 4, the cylindrical portion 43 is elastically deformed, and the air inside the rail mounting hole 4 is discharged to the outside through the slit 43a. As a result, the cap 41 can be easily attached to the rail mounting hole 4 , and the cap 41 can be prevented from easily coming off due to an increase in the internal pressure of the rail mounting hole 4 . In order to obtain the effect of the slits 43a, it is preferable to provide the slits 43a at three or more locations on the cylindrical portion 43 of the cap 41 at regular intervals. Further, the direction of the slit 43a is not particularly limited, and may be parallel to the cylindrical axial direction of the cylindrical portion 43 or may be inclined with respect to the cylindrical axial direction. It is sufficient if it can contribute to the discharge of air from the

Next, as a first modification of the cap fixing groove, the cap fixing groove 47 may be the cap fixing groove 48 shown in FIG. 7A. The cap fixing groove 48 has a V-shaped cross section, the lower surface of which is perpendicular to the axial direction of the rail mounting hole 4 (vertical direction in FIG. 7A), and the upper surface of which faces downward. It is formed on an inclined surface that expands according to the following. In this case, the cross-sectional shape of the end of the cap fixing projection 45 is preferably formed in a shape following the cap fixing groove 48 . According to this modified example, since the lower side surface forming the cap fixing groove 48 is formed on a plane perpendicular to the axial direction of the rail mounting hole 4 , the cap fixing projection 45 passes through the cap fixing groove 48 . It is possible to further prevent the cap 41 from being inserted to a position beyond the desired depth.

Next, as a second modification of the cap fixing groove, the cap fixing groove 47 may be the cap fixing groove 49 shown in FIG. 7B. The cap fixing groove 49 has a V-shaped cross section, and a projection 49a projecting toward the cap 41 is formed at the bottom of the cap fixing groove 49 . In this case, the cross-sectional shape of the end of the cap fixing protrusion 45 is preferably formed in a shape following the cap fixing groove 49 . According to this modification, since the contact area between the cap fixing projection 45 and the cap fixing groove 49 increases, the fixing force of the cap 41 can be increased, and the cap 41 can reach a desired depth or more. Insertion can be further prevented.

(Second embodiment)
Next, a second embodiment of the linear guide device according to the present invention will be described with reference to FIGS. 8 and 9. FIG. The same or equivalent parts as those of the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof will be omitted or simplified.

In the cap 51 of this embodiment, as shown in FIG. 8, cap fixing projections 45 are provided along the periphery of the opening end of the cylindrical portion 43, and a plurality of slits 43a are formed in the periphery of the opening end of the cylindrical portion 43. is provided. In the present embodiment, as shown in FIG. 9, the cap fixing groove 47 of the rail mounting hole 4 is positioned deeper than that of the first embodiment in accordance with the formation position of the cap fixing projection 45 of the cap 51. is formed in Further, in this embodiment, the cap fixing projection 45 has the same function as the guiding projection 46 of the first embodiment.
Other configurations and effects are the same as those of the first embodiment.

(Third embodiment)
Next, with reference to FIG. 10, a third embodiment of the linear motion guiding device according to the present invention will be described. The same or equivalent parts as those of the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof will be omitted or simplified.

In the cap 61 of the present embodiment, as shown in FIG. 10, the upper surface of the lid portion 44 is formed so as to gently protrude (convex spherical shape) from the outer peripheral portion toward the central portion. According to this embodiment, it is possible to further prevent foreign matter such as cutting powder and chips from accumulating on the upper surface of the cap 61 .
Other configurations and effects are the same as those of the first embodiment.

(Fourth embodiment)
Next, with reference to FIG. 11, a fourth embodiment of the linear guide device according to the present invention will be described. The same or equivalent parts as those of the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof will be omitted or simplified.

As shown in FIG. 11, the guide rail 73 of the present embodiment is formed with a rail-side shaft accommodating portion 74a for accommodating the shaft portion of the bolt 6, and the upper portion of the rail-side shaft accommodating portion 74a is connected to the rail-side shaft accommodating portion 74a. A bottomed cylindrical adapter mounting hole 78 is formed. The columnar adapter 72 fitted into the adapter mounting hole 78 is provided with a counterbore portion 74b and an adapter side shaft housing portion 74c that communicates between the counterbore portion 74b and the rail side shaft housing portion 74a. there is Further, similarly to the first embodiment, a cap fixing groove 77 is formed at a predetermined position on the inner peripheral surface of the counterbore portion 74b. By fitting the adapter 72 into the adapter mounting hole 78, a rail mounting hole 74 including a rail-side shaft housing portion 74a, an adapter-side shaft housing portion 74c, and a countersunk portion 74b is formed.

According to this embodiment, the small adapter 72, which is a separate part from the guide rail 73, is machined with the counterbore portion 74b, the adapter-side shaft accommodating portion 74c, and the cap fixing groove 77, so that the cap is fixed to the guide rail 73. It is not necessary to machine the groove 77 directly. As a result, even a long guide rail 73 that requires a large number of rail mounting holes 74 can be easily processed, and productivity can be improved.
Other configurations and effects are the same as those of the first embodiment.

It should be noted that the present invention is not limited to the examples illustrated in the above embodiments, and can be modified as appropriate without departing from the gist of the present invention.
For example, in each of the above-described embodiments, the case where the present invention is applied to a linear motion guide device using ball-shaped rolling elements was illustrated, but the present invention is not limited to this, and a linear motion guide device using roller-shaped rolling elements is used. The present invention may be applied to a guide device.

REFERENCE SIGNS LIST 1 linear guide device 3 guide rail 4 rail mounting hole 4a shaft accommodating portion 4b counterbore 6 bolt 7 mounting surface 20 slider 21 slider body 31 end cap 34 ball (rolling element)
35 side seal 41 cap 43 cylindrical portion 43a slit 44 lid portion 45 cap fixing projection 46 guide projection 47 cap fixing groove 48 cap fixing groove 49 cap fixing groove 51 cap 61 cap 72 adapter 73 guide rail 74 rail mounting hole 74a rail-side shaft accommodating portion 74b counterbored portion 74c adapter-side shaft accommodating portion 77 cap fixing groove 78 adapter mounting hole

Claims (6)

a guide rail that has a plurality of rail mounting holes through which bolts can be inserted, and that is attached to a mounting portion using the bolts;
A linear motion guide device comprising a slider mounted so as to straddle the guide rail and capable of moving relative to the guide rail in an axial direction,
The rail mounting hole of the guide rail includes a shaft receiving portion that receives the shaft portion of the bolt and a countersunk portion that receives the head portion of the bolt,
The counterbore portion of the rail mounting hole is provided with a cap that closes the opening of the rail mounting hole,
The cap has a cylindrical portion having a smaller diameter than the inner diameter of the countersunk portion, and a disk-shaped lid portion connected to the cylindrical axial end portion of the cylindrical portion and closing the opening of the rail mounting hole. It is formed in a bottomed cylindrical shape,
The cylindrical portion has a cap-fixing projection formed along its peripheral edge portion to be larger than the inner diameter of the countersunk portion,
A linear motion guide device, wherein a cap fixing groove engageable with the cap fixing projection is formed on an inner peripheral surface of the counterbore. 2. The linear motion guide device according to claim 1, wherein said cap has guiding projections provided along the periphery of the opening end of said cylindrical portion. 2. The linear motion guide device according to claim 1, wherein said cap fixing projection is formed along the peripheral edge of the opening end of said cylindrical portion. The linear motion guide device according to any one of claims 1 to 3, wherein said cap has a plurality of slits provided on the peripheral edge of the open end of said cylindrical portion. The linear guide device according to any one of claims 1 to 4, wherein the lid portion protrudes from the outer peripheral portion toward the central portion. The guide rail has an adapter mounting hole which can be fitted with an adapter having at least the countersunk portion and which is continuously formed from the shaft receiving portion,
The linear motion guide device according to any one of claims 1 to 5, wherein said rail mounting hole is configured by fitting said adapter into said adapter mounting hole.

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