Linear guide bearing apparatus

A linear guide bearing apparatus has a guide rail including a first raceway groove; a movable element including a second raceway groove and a rolling element return groove connected continuously with the second raceway groove through curved grooves respectively formed in the two end portions of the second raceway groove, the movable element being movably fitted with the guide rail; a plurality of rolling elements loaded in a circulation passage including the first raceway groove, the second raceway groove, the curved grooves, and the rolling element return groove for moving the movable element along the guide rail; and, an under-seal disposed in the movable element for sealing a space between the guide rail and the movable element, wherein the under-seal includes a sliding contact portion elastically contacted with the guide rail to thereby receive an upward-going force from the guide rail.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a linear guide bearing apparatus which is used as a linear guide in a machine tool and industrial machines.

2. Description of the Related Art

As a linear guide bearing apparatus which is used as a linear guide in a machine tool and industrial machines, there is conventionally known a guide bearing apparatus which includes a guide rail, a slider serving as a movable element, and a plurality of balls serving as rolling elements.

In the conventional guide bearing apparatus, the guide rail extending in the axial direction of the apparatus includes two first raceway grooves respectively formed in the two side walls thereof. The slider includes not only two second raceway grooves disposed opposed to the first raceway grooves of the guide rail but also ball return grooves respectively connected continuously with the second raceway grooves through their associated curved grooves respectively formed in the two end portions of each of the second raceway grooves. The slider includes a slider main body and a pair of end caps respectively to be connected to the two end portions of the slider main body; and, the second raceway grooves and ball return grooves are respectively formed in the slider main body, while the curved grooves are respectively formed in the end caps. This slider can be disposed by fitting the guide rail with the slider from the upward direction thereof in such a manner that the slider can be moved freely. The plurality of balls are used to move the slider along the guide rail, while the balls are disposed in a circulation passage which is composed of the first raceway grooves, second raceway grooves, curved grooves and ball return grooves.

In the linear guide bearing apparatus, in order to prevent dust from entering the circulation passage, there are disposed long-and-narrow-plate-shaped under-seals for sealing the two side walls of the guide rail and the two inner walls of the movable element. These under-seals are mounted on the lower wall of the slider along the axial direction of the guide bearing apparatus.

As a mounting structure for mounting the under-seals, there is conventionally known a mounting structure in which under-seal support grooves are formed in the end caps and the two end portions of the under-seals are respectively inserted into the under-seal support grooves.

However, in the above conventional mounting structure, in case where the two end portions of the under-seals are respectively inserted into the under-seal support grooves to thereby support the under-seals, the long-and-narrow-plate-shaped under-seals receive downward-going forces due to their own weights and the longitudinal-direction middle portions thereof are thereby flexed, which raises a fear that a poor sealing condition can occur.

SUMMARY OF THE INVENTION

The present invention aims at eliminating the drawbacks found in the above-mentioned conventional linear guide bearing apparatus. Accordingly, it is an object of the invention to provide a linear guide bearing apparatus which can reduce the flexion of the under-seals due to their own weights.

In attaining the above object, according to the invention according to a first aspect, there is provided a linear guide bearing apparatus having a guide rail including a first raceway groove and extending in an axial direction of the linear guide bearing apparatus a movable element including a second raceway groove opposed to the first raceway groove and a rolling element return groove connected continuously with the second raceway groove through curved grooves respectively formed in the two end portions of the second raceway groove, the movable element being movably fitted with the guide rail, a plurality of rolling elements loaded in a circulation passage including the first raceway groove, the second raceway groove, the curved grooves, and the rolling element return groove for moving the movable element along the guide rail and, an under-seal disposed in the movable element for sealing a space between the guide rail and the movable element, wherein the under-seal includes a sliding contact portion elastically contacted with the guide rail to thereby receive an upward-going force from the guide rail.

According to the present linear guide bearing apparatus, since the under-seal includes a sliding contact portion which can be elastically contacted with the guide rail to thereby receive an upward-going force from the guide rail, the downward-going flexion of the guide rail due to its own weight can be restricted due to the upward-going force given to the guide rail by the sliding contact portion of the under-seal.

Preferably, as in the invention according to a second aspect, in the guide rail, a groove portion may be formed in the guide rail, the sliding contact portion being contacted with the groove portion.

Also, as in the invention according to a third aspect, two end portions of the under-seal in the longitudinal-direction thereof may be supported on the movable element. In this case, as in the invention according to a fourth aspect, at least one portion of a middle portion of the under-seal in the longitudinal-direction thereof may be supported on the movable element.

Further, as in the invention according to a fifth aspect, preferably, the under-seal may be formed of a single material.

Still further, as in the invention according to a sixth aspect, preferably, the under-seal may be formed of a single material obtained from a molding with the section shape being uniform in the longitudinal direction thereof. In this case, a previously manufactured molding can be cut to a required length when it is used.

Moreover, as in the invention according to a seventh aspect, the under-seal may include a lip which extends in the same direction as the sliding contact portion and may be slidingly contacted with the guide rail.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, description will be given below of a first embodiment of a linear guide bearing apparatus according to the invention with reference toFIGS. 1to4.

The present linear guide bearing apparatus1includes a guide rail10, a slider20serving as a movable element, balls30serving as rolling elements, and under-seals40.

The guide rail10, which extends in the axial direction thereof, is made of steel having a long-and-narrow shape; and, in the width-direction two side portions thereof, for example, in the two side walls10athereof, there are formed first raceway grooves12along the axial direction thereof.

The slider20includes a slider main body21and a pair of end caps25respectively connected to the longitudinal-direction two end portions of the slider main body21. The slider main body21and end caps25respectively include sleeve portions22,26on the two side portions thereof, while they are respectively formed so as to have a substantially u-shaped section.

In the inner walls22aof the two sleeve portions22of the slider main body21, there are formed second raceway grooves23which are respectively opposed to their associated first raceway grooves12of the guide rail10. Also, in the interior portions of the two sleeve portions22, there are formed ball return grooves24formed of holes which penetrate through the sleeve portions22. The pair of end caps25are respectively moldings formed of synthetic resin or the like and, in the end caps25, there are respectively formed curved grooves (not shown) which are connected continuously with the longitudinal-direction two end portions of their associated second raceway grooves. Thus, the ball return grooves24are connected continuously with the second raceway grooves23through the curved grooves. In a circulation passage C which is composed of the first raceway grooves12, second raceway grooves23, curved grooves and ball return grooves24, there are disposed a plurality of balls30which are made of steel or the like. By the way, in one of the pair of end caps25, there is formed a grease nipple mounting hole (not shown). Also, in the drawings, reference character29designates a reinforcing plate.

The lower end portions of the inner walls22aof the slider main body21, as shown inFIG. 3, are formed as inclined walls22bwhich respectively extend fine and long in the axial direction of the slider main body21. Also, in the lower end portions of the end caps25as well, there are formed inclined walls26awhich are substantially parallel to the inclined walls22bof the slider main body21.

On the lower side of the sleeve portion26of each of the end caps25, there is integrally disposed a projecting portion27which projects downwardly of the lower wall22cof each of the sleeve portions22of the slider main body21; and, in the projecting portion27, there is formed an under-seal support groove27a. The under-seal support groove27ais formed in the extension of the wall surface of the inclined wall22band can be fitted with the support portion40bof an under-seal40(which will be discussed later).

In the lower portion of the side wall10aof the guide rail10, there is integrally formed an inward-facing projecting portion11. This projecting portion11includes an inclined surface11awhich extends fine and long in such a manner that it is opposed to and parallel to the inclined wall22bof the slider main body21. By the way, inFIG. 3, only one-side side wall10ais shown; however, the other-side side wall10ais also formed similarly.

Each under-seal40is disposed along the inclined wall22bof the slider main body21and is used to seal a space between the side wall10aof the guide rail10and the inner wall22aof the slider main body21so as to prevent dust from entering between them. This under-seal40, as shown inFIG. 3, includes a sliding contact portion40ato be contacted with the inclined surface11aof the side wall10aof the guide rail10, and a support portion40bwhich can be inserted into the under-seal support groove27ato be supported thereby; and, the under-seal40has a substantially corner-like section.

Also, the under-seal40, as shown inFIG. 4, is formed of a molding34the section shape of which is uniform in the longitudinal direction thereof; and, the molding34may be cut to a required length when it is used. As the molding34, there can be used an extruded molding, a drawn molding, or an injected molding. By the way, since the under-seal40is supported in such a manner that the two end portions thereof are inserted into the under-seal support grooves27a, in the present embodiment, the molding34is cut to a length slightly longer than the length of the slider main body21to thereby provide the under-seal40. The molding34is formed of a single material having elasticity such as rubber or elastomer.

The present linear guide bearing apparatus1is assembled in the following manner. That is, while loading a plurality of balls30into the circulation passage C, the two end caps25are respectively connected to the two end portions of the slider main body21. The two end portions of the under-seals40are respectively inserted into the under-seal support grooves27aof the end caps25. Due to this, with the two end portions thereof supported, the under-seals40are disposed on the lower wall21cof the slider main body21in the axial direction of the slider main body21. The thus-structured slider20is fitted onto the guide rail10from the upward direction in such a manner that the slider20can be moved.

In case where the slider20is fitted with the guide rail10, the leading end portions of the sliding contact portions40aof the under-seals40are respectively elastically contacted with the inclined walls22bformed in the projecting portions11of the guide rail10. This can seal a space between the side wall10aof the guide rail10and the inner wall22aof the slider main body21.

In this case, the sliding contact portion40aof the under-seal40is contacted with the inclined surface11aof the guide rail10from the obliquely upward direction. Therefore, to the sliding contact portion40awhich extends over the entire length of the under-seal40, there is applied an obliquely-upward-going force as a reactive action from the inclined surface11aof the guide rail10. This upward-going force received from the guide rail10can restrict the longitudinal-direction middle portion of the under-seal40from being flexed due to its own weight.

As described above, in the present linear guide bearing apparatus1, the under-seal40includes the sliding contact portion40awhich can be elastically contacted with the guide rail10to receive the upward-going force from the guide rail10. This can reduce the flexing of the under-seal40due to its own weight and can seal well a space between the side wall10aof the guide rail10and the inner wall22aof the slider main body21.

Also, in the present linear guide bearing apparatus1, since the two end portions of the under-seal40are formed so as to be supported by the slider20, the number of supporting portions is small, which can facilitate the installation of the under-seal40.

Further, because the under-seal40is formed of a single material, when compared with a seal material which is formed in such a manner that rubber is molded and bonded to a core bar, the under-seal40can be manufactured at a low cost and also it can be treated easily when it is scrapped.

Moreover, the under-seal40is formed of a single material obtained from a molding the section shape of which is uniform in the longitudinal direction thereof. Therefore, since a previously manufactured molding is cut to a required length as the need arises, the under-seal40can be manufactured at a low cost.

Now, description will be given below of a second embodiment of a linear guide bearing apparatus according to the invention with reference to FIG.5.

In the present embodiment, an under-seal41, as shown inFIG. 5, includes a sliding contact portion41ato be contacted with the side wall10aof the guide rail10, and a support portion41bto be supported by an under-seal support groove27a. The support portion41bis curved from the inclined wall22bof the slider main body21along the lower wall22c, and is inserted into the under-seal support groove27ato be supported thereby. The under-seal support groove27ais formed to have such a shape that allows the under-seal support groove27ato be fitted with the support portion41b.

Also, as shown inFIG. 5, in the side wall10aof the guide rail10, specifically, in the portion of the side wall10athat can be contacted with the leading end portion of the sliding contact portion41aof the under-seal41, there is formed a groove portion13athe section of which has a substantially semicircular shape. This groove portion13amay be worked simultaneously when the first raceway groove12is worked, or may be worked when the guide rail10is worked by drawing, or may be separately worked by cutting or by metal forming. By the way, in the present embodiment, although the projecting portion11of the guide rail10is omitted, the remaining portions of the present invention are the same in structure as those used in the previously described first embodiment. Therefore, the same parts are given like designations and thus the detailed description thereof is omitted here.

In the present linear guide bearing apparatus1, the sliding contact portion41aof the under-seal41is elastically contacted with the curved surface of the lower portion of the groove portion13aformed in the side wall10aof the guide rail10from the obliquely upward direction. For this reason, the sliding contact portion41aof the under-seal41is given an obliquely-upward-going force from the groove portion13aof the guide rail10as a reactive action. Thus, in the present embodiment as well, there can be obtained a similar effect to the first embodiment.

Also, in the present embodiment, since the sliding contact portion41aof the under-seal41is formed so as to be contacted with the groove portion13a, it is possible to omit the projecting portion11having the inclined surface11athat is employed in the first embodiment. Therefore, in the present embodiment, the maximum width of the guide rail10can be reduced by an amount equivalent to the width of the projecting portion11over the maximum width of the guide rail10according to the first embodiment, thereby being able to reduce the manufacturing cost of the guide rail10accordingly.

By the way, in the present embodiment, the groove portion13a, which is formed in the side wall10aof the guide rail10, is formed so as to have a substantially semicircular shape; however, the section shape of the groove portion13ais not limited to a substantially semicircular shape. For example, as shown inFIGS. 6A and 6B, there can also be employed another groove portion such as a groove portion13bhaving a substantially triangular shape or a groove portion13chaving a substantially trapezoidal shape, provided that the shape of the groove portion is able to apply an obliquely-upward-going force to the sliding contact portion41aas a reactive action.

Now, description will be given below of a third embodiment of a linear guide bearing apparatus according to the invention with reference to FIG.7.

In the present embodiment, an under-seal42, as shown inFIG. 7, includes a sliding contact portion42ato be contacted with the side wall10aof the guide rail10, and a support portion42bto be supported by an under-seal support groove27a. The support portion42bis curved from the inclined wall22bof the slider main body21along the lower wall22c, and is inserted into the under-seal support groove27ato be supported thereby. The under-seal support groove27ais formed to have such a shape that allows the under-seal support groove27ato be fitted with the support portion42b.

Also, the under-seal42further includes a lip42cwhich extends upwardly of the sliding contact portion42ain the same direction of the sliding contact portion42aand also which can be slidingly contacted with the side wall10aof the guide rail10. By the way, in the present embodiment, the groove portion14is formed so as to have a substantially-triangular-shaped section; however, the section shape of the groove portion14may also be a substantially trapezoidal shape (see FIG.5and FIG.6B). Also, although the projecting portion11of the guide rail10is omitted, the remaining portions of the present invention are the same in structure as those used in the previously described first embodiment. Therefore, the same parts are given like designations and thus the detailed description thereof is omitted here.

In the present embodiment, due to provision of the lip42cin the under-seal42, when compared with the first embodiment, the sealing property between the side wall10aof the guide rail10and the inner wall22aof the slider main body21can be enhanced further.

Now, description will be given below of a fourth embodiment of a linear guide bearing apparatus according to the invention with reference to FIG.8.

In the present embodiment, an under-seal43, as shown inFIG. 8, includes a sliding contact portion43ato be contacted with the side wall10aof the guide rail10, and a support portion43bto be supported by an under-seal support groove27a. The support portion43bis formed so as to be substantially parallel to the lower wall22cof the slider main body21, while the sliding contact portion43ais inclined downwardly toward the groove portion15of the guide rail10. By the way, the inclined wall26aof the end cap25is omitted.

The under-seal support groove27ais formed so as to have a shape which allows the under-seal support groove27ato be fitted with the support portion43b. The section of the groove portion15of the guide rail10has a substantially trapezoidal shape having two inclined surfaces respectively formed on the upper and lower sides thereof, while the leading end portion of the sliding contact portion43ais slidingly contacted with the lower-side inclined surface of the groove portion15.

Also, the under-seal43includes a lip43cwhich extends upwardly of the sliding contact portion43ain the same direction of the sliding contact portion43aand also which can be slidingly contacted with upper-side inclined surface of the groove portion15of the guide rail10. That is, the lip43cis inclined upwardly toward the groove portion15side of the guide rail10. By the way, in the present embodiment, the section shape of the groove portion15is formed as a substantially trapezoidal shape; however, it is also possible to employ another shape, provided it has, on the upper and lower sides thereof, two inclined surfaces which can be slidingly contacted with the lip43cand sliding contact portion43a. For example, the section shape of the groove portion15may also be a substantially semicircular shape or a substantially triangular shape (see FIG.5and FIG.6A)). Also, although the projecting portion11of the guide rail10is omitted, the remaining portions of the present invention are the same in structure as those used in the previously described first embodiment. Therefore, the same parts are given like designations and thus the detailed description thereof is omitted here.

In the present embodiment, similarly to the third embodiment, due to provision of the lip43c, the sealing property between the side wall10aof the guide rail10and the inner wall22aof the slider main body21can be enhanced.

By the way, in the above-mentioned third and fourth embodiments, in the under-seals42,43, there are disposed the lips42c,43cone each; however, a plurality of lips42c,43cmay be disposed in the respective under-seals42,43.

Now, description will be given below of a fifth embodiment of a linear guide bearing apparatus according to the invention with reference to FIG.9.

In the present embodiment, in the longitudinal-direction middle portions of the under-seal43and the lower wall22cof the slider main body21, for example, in the central portions of the under-seal43and the lower wall22c, there are formed rivet receive holes (not shown). And, when mounting the under-seal43, the two end portions of the under-seal43are inserted into the under-seal support grooves27aof the end caps25and, at the same time, the longitudinal-direction central portion thereof is fixed by a support part serving as support means such as a rivet. By the way, the support means for fixing the longitudinal-direction middle portion of the under-seal43is not limited to the rivet35but the longitudinal-direction middle portion of the under-seal43may also be supported on the slider using a screw or an adhesive. Also, in the present embodiment, the under-seal43is supported at a portion of the longitudinal-direction central portion thereof; however, the number of the supporting portions of the under-seal43may be one or two or more. Further, the remaining portions of the present invention are the same in structure as those used in the previously described first embodiment. Therefore, the same parts are given like designations and thus the detailed description thereof is omitted here.

In the present embodiment, since the given portions of the longitudinal-direction middle portion of the under-seal43are supported on the slider main body21, even in case where the slider main body21. That is, the under-seal43is long, the flexing of the under-seal43due to its own weight can be prevented to thereby provide a good sealing condition between the guide rail and movable body.

By the way, in the above-illustrated first to fifth embodiments, the under-seals40-44are respectively formed of a single material. However, as the under-seals40-44, there may also be employed an under-seal which can be obtained by molding and bonding rubber or the like onto a core bar made of a metal plate. In this case, the strength of the under-seals40-44can be enhanced.

Also, in the above-illustrated first to fifth embodiments, the sliding contact surface of the guide rail10, with which the sliding contact portions40a-44aof the under-seals40-44can be elastically contacted, is not limited to the inclined surface11aor groove portions13a,13b,13c,14,15. Preferably, the sliding contact surface may be a surface which is inclined or curved in a direction to support the sliding contact portions40a-44afrom the lower side thereof.

Further, in the above-illustrated first to fifth embodiments, the longitudinal-direction two end portions of the sliding contact portions40a-44aof the under-seals40-44are inserted into the under-seal support grooves27aformed in the end caps25to thereby support them on the slider20. However, support of the two end portions of the under-seals40-44is not limited to this; for example, they may also be supported on the slider20using a rivet, a screw, or an adhesive.

According to the linear guide bearing apparatus of the invention, the flexing of the under-seal due to its own weight can be restricted to thereby be able to enhance the sealing property between the guide rail and movable body.