Device for motion guidance

Abstract

A motion guidance device comprising: a guide rail (1) with a rolling surface (11) for rolling elements (3) extending along its longitudinal direction; a movable block (2) mounted on the guide rail (1) by interposing a large number of rolling elements (3) and providing an endless travel path for the rolling elements (3), the movable block (2) being freely movable along the guide rail (1); a pair of first sealing elements (4) mounted on both end faces of the movable block (2) in one direction of movement of the same and coming into sliding contact with a surface of the guide rail (1), thus closing a gap between the guide rail (1) and the movable block (2); and a second sealing element provided along the rolling surface (11) of the guide rail (1) and coming into sliding contact with the surface of the guide rail (1).so that the gap between the running rail (1) and the movable block (2) is closed, wherein the second sealing element (5) comprises: a mounting base (51) which is locked to the movable block (2); and a sealing section (52) that is firmly connected to the mounting surface (51) along the rolling surface (11) of the guide rail (1), wherein the sealing section (52) comprises a sealing lip section (52b) that comes into sliding contact with the surface of the guide rail (1), the sealing section (52) having both longitudinally extending ends that come into close contact with the pair of first sealing elements (4) in a state in which the pair of first sealing elements (4) is attached to the movable block (2), wherein the sealing section (52) further comprises a pair of extended sealing sections (52a) that project in a longitudinal direction of the mounting surface (51) from both longitudinal ends of the mounting surface (51),and wherein the pair of extended sealing sections (52a) is compressed in a state in which the pair of first sealing elements (4) is attached to the movable block (2), wherein the sealing section (52) is formed in one piece with the pair of extended sealing sections (52a), and wherein the sealing section (52) further comprises an extended end section (52c) which is configured to cover an end section of the mounting substrate (51) from the longitudinal direction of the mounting substrate (51).

Description

Technical FieldThe present invention relates to a motion guide device in which a movable block is mounted on a running rail by interposing a large number of continuously revolving rolling elements such as balls and rollers, thereby enabling a free reciprocating motion of an object mounted on the movable block along the running rail.Background of the TechniqueAs the above-mentioned motion guide device, a motion guide device is known, which includes a running rail having a rolling surface for balls formed along its longitudinal direction, and a movable block mounted on the running rail by interposing the balls rolling on the running surface and having an endless circulation path for the balls. The movable block includes a main body of the block and a pair of lid members. The main body of the block has a load rolling surface facing the rolling surface of the track rail to form a load ball track for the balls, and a ball return hole for circulating the balls. The pair of lid members are fixed to both front and rear end surfaces of the main body of the block. The balls circulate through the endless circulation path for the balls provided in the movable block, and therefore the movable block can continuously move along the longitudinal direction of the running rail.In the motion guidance device arranged as described above, foreign bodies such as chips of a workpiece or waste may adhere to the running rail depending on the application environment. When these foreign matters enter the movable block moving along the running rail, flaws may be generated in a rolling surface of the running rail, a load rolling surface of the movable block, or balls, or abrasion of these members may be enhanced. As a result, the accuracy of movement of the movable block in the movement guidance device may be impaired early.For these reasons, generally, a pair of end seals are mounted on the movable block at both ends in the moving direction thereof. Each of the end seals includes a seal lip portion that comes into sliding contact with the surface of the running rail, and when the movable block moves along the running rail, the seal lip portion wipes the foreign matters adhering to the running rail from the surface of the running rail, thereby preventing the foreign matters from entering the movable block.Further, in view of preventing entry of foreign matters into the load ball track for the balls, in particular, within the movable block, generally, a pair of inner seals are mounted on the movable block at positions facing the top of the track rail, while a pair of side seals are mounted on the movable block at positions facing the side surfaces of the track rail. Each of the inner seals and the side seals includes a seal lip portion provided along the longitudinal direction of the movable block, and the seal lip portion comes into sliding contact with the surface of the running rail in a similar manner to the end seal.The pair of end seals are fastened with fastening screws to both end surfaces of the movable block in the direction of movement thereof, that is, the outer side surfaces of the lid members, while the inner seal and the side seal are fastened to the movable block in a state in which both longitudinal ends thereof are held by the pair of lid members. Further, as disclosed in Patent Literature 1, as another means for fixing the inner seal and the side seal to the movable block, it is known to form recessed portions in the pair of end seals to fix them to the movable block, and insert the inner seal and the side seal through the recessed portions to thereby hold the inner seal and the side seal between the pair of end seals.Further relevant prior art is disclosed in the following document: US 6 113 272 A.Citation ListPatent Literature[PTL 1] JP 2006-170279 ADISCLOSURE OF THE INVENTIONProblem to be Solved by the InventionHowever, in the fastener disclosed in Patent Literature 1, which supports both the longitudinal ends of the inner seal and the side seal by the pair of the end seals, respectively, there is a tolerance in processing in each of the main body of the block, the lid member, the inner seal, and the side seal, and a gap may be formed between the end seal and the inner seal or between the end seal and the side seal. This is because the length of the inner seal or the side seal does not correspond to the distance between the outer side surfaces of the pair of lid members fixed to the main body of the block. This problem may occur even in the fasteners in which both ends of the inner seal and the side seal are supported by the pair of the lid members, respectively.In the motion guide device of this type, the running rail is fixed to a fixing portion such as a bed by means of fixing screws in most cases, thus the running rail has fixing screw insertion holes formed continuously therein. In the motion guidance device of the related art to be used in an environment having a large amount of foreign matter, the following measures have been taken to prevent the entry of the foreign matter into the movable block through the insertion holes. That is, caps are inserted into the insertion holes of the slide rail so that the surface of the slide rail with which the end seals come into sliding contact becomes a smooth surface without steps.However, even when the caps are inserted into the insertion holes, a slight step or a gap is naturally generated at a boundary between the cap and the insertion hole, and fine foreign matters that may accumulate in this step or gap may not be wiped by the end seal located on the front side in the traveling direction of the movable block, but may possibly get under the end seal. The foreign matters that have passed under the end seal as described above adhere to the inside of the end seal that is located on the back side in the traveling direction of the movable block, with the result that the fine foreign matters that have passed under the pair of end seals accumulate between these end seals.When the motion guidance device is continuously used in this state, the foreign matters gradually accumulate on the inside of the end seal. Finally, there is a great risk that the foreign bodies accumulated on the end seal will enter the load ball path through a gap formed between the end seal and the inner seal or between the end seal and the lateral seal. As a result, flaws may be generated in the rolling surface of the track rail, the load rolling surface of the movable block, or the balls, or the abrasion of these members may be enhanced. As a result, the accuracy of movement of the movable block with respect to the running rail may be impaired early. Such entry of foreign matters through the gap generated between the end seal and the inner seal or the side seal therefore also occurs due to the deterioration of the state of the end seal caused by the long use of the motion guide device.Means for Solving the ProblemsThe present invention has been made in view of the above problem, and has an object to provide a motion guidance device capable of stopping formation of a gap between an end seal and an inner seal or between the end seal and a side seal fixed to a movable block, and preventing foreign matter from entering a load ball path through the gap, so as to prevent abrasion or damage on a rolling surface of a running rail, a load rolling surface of the movable block, or a ball itself, and achieving smooth movement of the movable block with respect to the running rail.To solve the above problem, a motion guidance device having the features of claim 1 is provided. A further advantageous embodiment is defined in dependent claim 2. The moving direction device includes: a running rail having a rolling surface for rolling elements formed along a longitudinal direction thereof; a movable block mounted on the running rail by interposing a large number of the rolling elements and having an endless circulation path for the rolling elements, the movable block being freely movable along the running rail; a pair of first seal members mounted on both end surfaces of the movable block in a moving direction thereof and coming into sliding contact with a surface of the running rail so as to close a gap between the running rail and the movable block; and a second seal member provided along the rolling surface of the running rail and coming into sliding contact with the surface of the running rail so as to close the gap between the running rail and the movable block.Further, the second sealing member includes: a mounting base locked to the movable block; and a sealing portion fixedly connected to the mounting base along the rolling surface of the running rail. The seal portion includes a seal lip portion that comes into sliding contact with the surface of the track rail. The seal portion has two elongated ends that come into close contact with the pair of first seal members in a state where the pair of first seal members are fixed to the movable block. The sealing portion further includes a pair of elongated sealing portions protruding from both longitudinal ends of the mounting base in a longitudinal direction of the mounting base. Moreover, the pair of the elongated seal portions are compressed in a state where the pair of the first seal members are fixed to the movable block.Effects of the InventionIn the motion guidance device to which the present invention is applied as described above, when the pair of first seal members are fixed to the movable block, the extended seal portions provided at both ends of the seal portion of the second seal member are compressed by the first seal member, and the both ends of the seal portion of the second seal member are brought into close contact with the first seal member. Therefore, no gap is formed between the second seal member and the first seal member, and unlike the motion guide device of the related art, foreign matter is prevented from entering the endless circulation path of the movable block through a gap between the second seal member and the first seal member. Moreover, smooth movement of the movable block with respect to the running rail can be achieved.Brief Description of the DrawingsFIG. 1 is a perspective view illustrating an example of a motion guidance device to which the present invention is applied. FIG. 2 is a front view illustrating a surface of a lid member illustrated in FIG. 1 and abutting a main body of the block. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. 2. FIG. 4 is a front view illustrating an end seal integrated with the motion guidance device to which the present invention is applied. FIG. 5 is a cross-sectional view taken along the line V - V of FIG. 4. FIG. 6 is a cross-section illustrating an inner seal and the end seal in the state of being mounted to a movable block. FIG. 7 is a plan view illustrating an inner seal integrated in the motion guidance device to which the present invention is applied. FIG. 8 is a view seen from the arrow A of FIG. 7. FIG. 9 is a perspective view illustrating a connection part between the end seal and a side seal. FIG. 10 is a schematic view illustrating a connection part between the end seal and the inner seal in a motion guide device of the related art. FIG. 11 is a schematic view illustrating a connection part between the end seal and the inner seal in the motion guidance device to which the present invention is applied. FIG. 12 is a front cross-sectional view illustrating a lubricating oil supply device that can be applied to the motion guidance device illustrated in FIG. 1. FIG. 13 is a schematic view illustrating a connection part between the lubricating oil supply device illustrated in FIG. 12 and a lid member and the end seal of the movable block.MODE FOR CARRYING OUT THE INVENTIONNow, an example of a motion guide device to which the present invention has been applied will be described in detail with reference to the accompanying drawings.Fig. 1 illustrates the motion guidance device to which the present invention is applied. The motion guide device includes a linear-shaped running rail 1 serving as a running rail, a movable block 2 serving as a movable member mounted on the running rail 1 by interposing balls 3 serving as rolling elements and enclosing an endless circulation path for the balls 3 therein, end seals 4 serving as a pair of first seal members fixed to both ends of the movable block 2 in the direction of movement thereof, and an inner seal 5 serving as a second seal member for sealing the endless circulation path for the balls 3 in the movable block 2 from outside the motion guide device. When the balls 3 rotate in the endless circulation path of the movable block 2, the movable block 2 reciprocates on the track rail 1. Note that, in FIG. 1, for easy understanding of the internal structure of the movable block 2, a part thereof is illustrated as cut out.The track rail 1 is formed with a substantially rectangular cross section, and two ball rolling surfaces 11 on which the balls 3 roll are formed in each side surface of the track rail 1 along its longitudinal direction. Further, the track rail 1 has insertion holes 12 formed therethrough at respective intervals in the longitudinal direction. Fastening screws are inserted through the insertion holes 12 to fasten the running rail 1 to a fastening portion such as a bed or a column of various mechanical devices. After the screws are fastened to a fastening portion, caps (not shown) are inserted into the insertion holes 12 so as to prevent accumulation of foreign matter. Note that the track rail 1 of this embodiment has four ball rolling surfaces 11 formed therein, but the number of the ball rolling surfaces 11 and the arrangement thereof may be adjusted and changed accordingly depending on the application of the motion guide device and the amount of applied load.On the other hand, the movable block 2 comprises a block main body 21 and a pair of lid members 22 fixed to both front and rear end surfaces of the block main body 21. The block main body 21 has load rolling surfaces facing the rolling surfaces 11 of the track rail 1 to form load ball tracks and ball return tracks 21a for circulating the balls 3 for the balls 3.FIGS. 2 and 3 illustrate the lid member 22, FIG. 2 illustrates a surface of the lid member 22 abutting on the main body 21 of the ingot, and FIG. 3 is a cross section taken along the line III-III of FIG. 2, the lid member 22 has directional changeover paths 22 aformed therein so as to collect the balls 3 rolling through the load ball path upon application of a load, and supply the balls 3 to the ball return path 21 aof the main body 21 of the ingot, and supply the balls 3 rolling through the ball return path 21 ain a no-load state to the load ball path. That is, the pair of lid members 22 are fixed to both end surfaces of the block main body 21, and thus the endless circulation path for the balls 3 in the movable block 2 is completed. Note that the adjacent balls 3 located in the endless circulation path are retained by a synthetic resin belt 31 to maintain the aligned state of these balls 3 (see FIG. 1 ).Further, the lid member 22 is provided with an oil filler pipe 22 bfor supplying lubricating oil into the endless circulation path for the balls 3. Further, the surface of the lid member 22 adjacent to the block main body 21 has a recessed portion 23 formed therein, to which a terminal fitting of the inner gasket 5 to be described later is loosely mounted. On both sides of the recessed portion 23, a pair of insertion grooves 24 for inserting the leg portions of the inner gasket 5 to be described later along the moving direction of the movable block 2 (direction from the front side to the deep side in the drawing sheet of FIG. 2 ) are formed. Still further, in an outer surface of the lid member 22, that is, the surface opposite to the surface adjacent to the block main body 21, a receiving groove 25 to which the end seal 4 is fixed is formed.FIGS. 4 and 5 illustrate one of the pair of end seals 4 to be fixed to the lid member 22. FIG. 4 is a front view of the end seal 4, and FIG. 5 is a cross section taken along the line V - V of FIG. 4. the end seal 4 is fastened with a fastening bolt to the receiving groove 25 of each of the lid members 22 from the front or rear side in the moving direction of the movable block 2. Further, the end seal 4 has a guide groove having a cross section slightly larger than the cross section of the running rail 1, and a seal portion 41 coming into sliding contact with the surface of the running rail 1 is formed at the edge of the guide groove.The end seal 4 includes a seal plate 42 serving as a fixing plate with respect to the movable block 2, and a seal main body 43 fixedly attached to the seal plate 42. The seal portion 41 constitutes a part of the seal main body 43, and the seal plate 42 is made of a hard material such as a metal plate, and the seal main body 43 is made of an elastic material such as urethane rubber. The seal main body 43 is vulcanized and bonded to the seal plate 42. These seal plate 42 and seal main body 43 have through holes 42 aand 43 aformed to communicate with the oil filler pipe 22 bformed in the lid member 22, respectively. Further, at the outer edge of the seal main body 43, an elastically deformable fixing lip 43 bprotruding toward the outside of the seal main body 43 is formed.The seal portion 41 is brought into sliding contact with the top and side surfaces of the track rail 1 and into sliding contact with the ball rolling surfaces formed in the track rail. Further, at a contact end of the seal portion 41 coming into sliding contact with the running rail 1, seal lips 44 and 45 are provided which are arranged twice. The seal lip 44 disposed on the outer side with respect to the movable block 2 is a dust lip and functions mainly with respect to the cloths adhering on the running rail 1 in the traveling direction of the movable block 2, thereby removing the adhering cloths from the running rail 1 with the movement of the movable block 2. On the other hand, the seal lip 45 disposed in the vicinity of the movable block 2 is an oil lip and prevents lubricating oil or grease, which is filled in the movable block through the oil filling port 22 band flows out of the movable block 2, from adhering to the running rail 1.Each of the seal lips 44 and 45 has a tapered front end portion adjacent to the track rail 1, and the seal lips 44 and 45 are easily deformed. Thus, a higher surface pressure is prevented when the seal lip is brought into contact with the running rail 1. Further, a groove is formed between the dust lip 44 and the oil lip 45. The dust lip 44 and the oil lip 45 are independently brought into contact with the surface of the running rail 1. Further, the seal portion 41 has a smooth surface 46 formed therein, which is continuous with the oil lip 45 and cooperates with the seal plate 42 to form a surface facing the movable block 2.When each of the pairs of the end seals 4 arranged as described above is accommodated in the accommodation groove 25 provided in each of the lid members 22, the fixing lip 43 bprovided in the seal main body 43 is brought into abutment with an inner circumferential wall of the accommodation groove 25 of the lid member 22 to be elastically deformed. As a result, as illustrated in FIG. 6, when the end seal 4 is mounted in the accommodation groove 25 of the lid member 22, the fixing lip 43 bis brought into close contact with the inner circumferential wall of the accommodation groove 25 so as to tension the inner circumferential wall and ensure water tightness between the end seal 4 and the lid member 22. With this, it is possible to prevent foreign matter from entering the movable block 2 from the outside of the end seal 4.When the movable block 2 to which the end seal 4 is attached as described above is moved along the running rail 1, the seal portion 41 provided in the end seal 4 has a function of removing the matters adhering to the running rail 1, and the foreign matters adhering to the running rail 1 are collected on an outer side of the dust lip 44 of the seal portion 41.Next, an inner seal 5 integrated with the motion guidance device to which the present invention is applied will be described. FIGS. 7 and 8 illustrate the inner gasket 5, FIG. 7 is a plan view, and FIG. 8 is a view seen from the arrow A of FIG. 7. As shown in FIG. 1, the inner seal 5 is mounted on the lower surface of the movable block 2 at a position opposite to the upper surface of the track rail 1. The inner seal 5 includes a metal mounting plate 51 that functions as a mounting base and a pair of seal portions 52. The pair of seal portions 52 are provided along the long side of the fixing plate 51. The pair of seal portions 52 are made of an elastic material such as urethane rubber. The pair of seal portions 52 are molded and simultaneously vulcanized and bonded to the long sides of the fixing plate 51.The leg portions 51 aprotruding from both axial ends of the fixing plate 51 are formed in the fixing plate 51, and the leg portions 51 aprotrude in pairs from each end portion of the fixing plate 51. That is, a total of four leg portions 51 aare formed in the fixing plate 51. Further, a terminal 51b loosely fitted to the recessed portion 23 provided in the lid member 22 is formed between the pair of leg portions 51a provided at each end of the fixing plate 51.On the other hand, each of the seal portions 52 is provided from the above-mentioned one leg portion 51 ato the other leg portion 51 aalong the long side of the fixing plate 51. Further, each of the seal portions is provided along the ball rolling surface 11 of the track rail 1. Each of the seal portions 52 abuts on the upper surface of the running rail 1 provided with the insertion holes 12, and the insertion holes 12 of the running rail 1 are located between the pair of seal portions 52.Further, each of the seal portions 52 includes a pair of elongated seal portions 52 athat project from the end portions of the respective leg portions 51 ain the longitudinal direction of the fixing plate 51. The axial length of each seal portion 52 including the extended seal portions 52 ais set longer than the entire length of the fixing plate 51 including the pairs of leg portions 51 a. Further, the front end of each seal portion 52 coming into contact with the top surface of the running rail 1 is formed as a lip tapered portion 52b so that an increase in surface pressure is prevented when the front end comes into contact with the running rail 1. The seal lip portion 52 bis formed over the entire length of the seal portion 52 including the pair of the seal extended portions 52 a, and the seal lip portion 52 bis formed to have a uniform cross section over the entire length of the seal portion 52.Further, the end surface of the leg portion 51 aof the fixing plate 51 is covered with an extended end portion 52 cformed integrally with the seal extended portion 52 a, and the seal lip portion 52 bis not formed in the extended end portion 52 c. Note that, in the example illustrated in FIGS. 7 and 8, only the single seal lip portion 52 bis provided on the seal portion 52 and the seal extended portions 52 a. However, in order to further improve the dust preventing effect, a structure having double seal lips may be employed.In a state where the inner gasket 5 is mounted on the movable block 2 as described above, the terminal fittings 51 bprovided at both ends of the fixing plate 51 are loosely fitted to the recessed portions 23 provided in the lid members 22. By fixing the pair of lid members 22 to the block main body 21, both ends of the inner gasket 5 are supported by the pair of lid members 22. That is, the inner seal 5 is disposed to be clamped to the pair of lid members 22. In this case, when the axial length of the fixing plate 51, specifically, the axial length from one terminal 51 bto the other terminal 51 bis greater than the axial length from one lid member 22 to the other lid member 22, the inner seal 5 and the lid members 22 interfere with each other, and therefore, the pair of lid members 22 cannot be mounted on the main body 21 of the block. Therefore, considering that tolerances occur in the machining of the fixing plate 51 and the cover members 22, the machining tolerance of the axial length of the fixing plate 51 is set to a negative value. Therefore, in a state where the movable block 2 holds the inner gasket 5 by means of the lid members 22, there is a case where there is a slight gap between the fixing plate 51 and the lid member 22. In this case, in the direction of movement of the movable block 2, a slight displacement of the inner seal 5 with respect to the movable block 2 is permitted.Further, in a state where the terminal fittings 51 bof the inner gasket 5 are attached to the recessed portions 23 of the lid members 22 as described above, as illustrated in FIG. 6, each leg portion 51 athat constitutes the inner gasket 5 and the sealing portion 52 firmly connected to the leg portion 51 aare located inside the insertion groove 24 formed in the lid member 22, and the seal extended portion 52 aextending continuously with the sealing portion 52 and the seal extended portion 52 cthat covers the end portion of the leg portion 51 aare arranged so as to come into close contact with the end gasket 4.In this case, in consideration of the machining tolerance of the axial length of the block main body 21, the machining tolerance of the axial length of each of the lid members 22, and the machining tolerance of the axial length of the fixing plate 51 including the pairs of leg portions 51 a, an axial length L (see FIG. 7 ) of each of the seal extended portion 52 aand the end extended portion 52 cis set larger than the total value of these machining tolerances.Therefore, as illustrated in FIG. 6, when the pair of end seals 4 are fixed to the movable block 2 with the inner seal 5 mounted thereon, the seal extended portion 52 aand the end extended portion 52 c,which is vulcanized and bonded to the leg portion 51 aof the inner seal 5, are brought into close contact with the smooth surface 46 and the metal surface of the seal plate 42 provided in the end seal 4. That is, by fixing the end seal 4 to the movable block 2, the seal extended portion 52 aand the end extended portion 52 care compressed, so that the seal portion 52 of the inner seal 5 is brought into close contact with the seal portion 41 of the end seal 4 reliably and without any gaps.On the other hand, the motion guide apparatus to which the present invention is applied is not always used in the manner that the running rail 1 is mounted on a horizontal surface. The running rail 1 is used such that the running rail 1 is installed on a wall surface in many cases. In these cases, waste and coolant adhere to the side surfaces of the running rail 1 in which the ball rolling surfaces 11 are formed, and these adhered substances can enter the moving block 2 through gaps between the moving block 2 and the side surfaces of the running rail 1. In such a use environment, it is therefore preferable, as illustrated in FIG. 1, that a side seal 6 for closing the gap between the side surface of the running rail 1 and the movable block 2 be provided along the longitudinal direction of the running rail 1. When this side seal 6 is provided, it is possible to prevent materials adhering to the side surface of the running rail from entering the movable block 2.The side seal 6 has a structure similar to that of the inner seal 5. As illustrated in FIG. 9, the side seal 6 includes a metal fixing plate 61 serving as a ground, and a seal portion 62 provided along the long side of the fixing plate 61. The seal portion 62 is made of an elastic material such as urethane rubber, and is molded and simultaneously vulcanized and bonded to the long sides of the fixing plate 61. An elongated seal portion 62a for closing the gap between the side seal 6 and the end seal 4 is formed in the seal portion 62 of the side seal 6 in a similar manner to the seal portion 52 of the inner seal 5. Further, an extended end portion 62b formed integrally with the extended seal portion 62a covers each of the two longitudinal end surfaces.In a state where the side seal 6 constructed as described above is disposed between the pair of end seals 4, the seal extended portion 62 aand the end extended portion 62 bare compressed to come into close contact with the smooth surface 46 and the metal surface of the seal plate 42 provided in the end seal 4, thus eliminating the gap between the end seal 4 and the side seal 6. That is, the side seal 6 and the above-mentioned inner seal 5 are a member corresponding to a second seal member of the present invention.When the side seal 6 and the end seal 4 are joined together as described above, a seal structure can be provided together with the above-described joint structure between the inner seal 5 and the end seal 4 to enclose the load rolling surfaces of the movable block 2. That is, an area where the balls 3 roll on the track rail 1 is surrounded by the end seals 4, the inner seal 5, and the side seals 6 which are brought into close contact with each other. In this way, substances adhering to the running rail 1 are prevented from entering the rolling region.FIG. 10 is a schematic view illustrating a motion guidance device of the related art. In the execution of such a motion guidance device of the related art, it is necessary to make the entire length of the movable block 2 including the block main body 21 and the pair of lid members 22 equal to the axial length of the inner seal 5 so as to prevent the generation of gaps between the inner seal 5 and the pair of end seals 4. However, there are tolerances in the machining of the block main body 21 and the lid members 22, and therefore, when the cumulative value of the machining tolerances is a negative value for the entire length of the movable block 2, both ends of the inner seal mounting plate 5 slightly project from the movable block when the movable block is assembled. Therefore, due to interference with the fixing plate, it may become impossible to mount the end seals 4 to the movable block 2. In order to avoid such a situation, in the motion guidance device of the related art, the machining tolerance of the axial length of the inner seal 5 is set to a negative value.When the machining tolerance of the axial length of the inner seal 5 is set to a negative value, the mounting of the movable block 2 is enabled even for the reason described above. However, there is a case where the entire length of the inner seal 5 becomes smaller than that of the movable block 2, and as illustrated in FIG. 10, gaps are likely to form between the pair of end seals 4 and both longitudinal ends of the inner seal 5.In a case where these gaps are present and the movable block 2 moves along the track rail 1 in the arrow direction indicated in FIG. 10, almost all the foreign matters adhering to the surface of the track rail 1 are wiped by the end seal 4 (end seal 4 on the left side in FIG. 10 ) disposed on the front side in the traveling direction of the movable block 2 and cannot enter the movable block 2. On the other hand, fine foreign matter that accumulates at a boundary between the insertion hole 12 and the cap closing the insertion hole 12 may come under the end seal 4 and adhere to the oil lip 45 of the other end seal 4 (end seal 4 on the right side in FIG. 10 ) that is on the back side in the traveling direction of the movable block 2, and may gradually accumulate over a long time with the use of the motion guidance device.In this state, when the use time of the motion guidance device increases, the foreign matters accumulated on the oil lip 45 can finally enter the movable block 2 through the gap between the inner seal 5 and the end seal 4 shown on the right side in FIG. 10. This may also occur between the inner seal 5 and the end seal 4 shown on the left side in FIG. 10 when the movable block 2 moves in a direction opposite to the direction of the arrow indicated in FIG. 10. Note that in FIG. 10, for easier understanding of the gap between the end seal 4 and the seal portion 52 constituting the inner seal 5, the arrangement of the inner seal 5 and the end seal 4 is illustrated by solid lines, and the seal portion 52 and the end seal 4 are shaded. On the other hand, a configuration other than that of the seal portion 52 and the end seal 4 is represented by transverse ribs.In contrast, in the motion guidance device to which the present invention is applied, as illustrated in FIG. 11, the seal extended portions 52 aare formed at both ends of the seal portion 52 of the inner seal 5, and in a state where the pair of end seals 4 are fixed to the lid members 22 of the movable block 2, the seal extended portions 52 aare compressed and brought into close contact with the end seals 4. As a result, the gap between the inner seal 5 and the end seal 4 is completely eliminated. Note that, also in FIG. 11, similarly to FIG. 10, for easy understanding of the close contact relationship between the end seal 4 and the seal extended portion 52 aof the inner seal 5, the arrangement of the inner seal 5 and the end seal 4 is illustrated by solid lines, and the seal extended portion 52 aand the end extended portion 52 cof the inner seal 5, the seal portion 52 coming into sliding contact with the surface of the running rail 1, and the end seal 4 are shaded. On the other hand, a configuration other than that of the seal extended portion 52 a, the end extended portion 52 c, the seal portion 52, and the end seal 4 is represented by cross ribs.When the movable block 2 moves along the track rail 1 in the arrow direction indicated in FIG. 11, the foreign matters adhering to the surface of the track rail 1 accumulate on the end seal 4 (end seal 4 on the left side in FIG. 11 ) disposed on the front side in the traveling direction of the movable block 2. On the other hand, fine foreign matters accumulated at a boundary between the insertion hole 12 and the cap may come under the end seal 4 disposed on the front side in the traveling direction of the movable block 2, and adhere to the oil lip 45 of the other end seal 4 (end seal 4 on the right side in FIG. 11 ) disposed on the back side in the traveling direction of the movable block 2, and gradually accumulate over a long time with the use of the motion guidance device.In this state, when the use time of the motion guidance device increases, although foreign matters accumulate in a space defined by the end seal 4 on the right side in FIG. 11 and the seal portions 52 of the inner seal 5, the extended seal portions 52 aof the inner seal 5 are brought into close contact with the smooth surface 46 of the end seal 4, and therefore there is no gap through which foreign matters can enter between the inner seal 5 and the end seal 4. In this way, it is possible to prevent foreign matter adhering to the surface of the slide rail 1 from entering the movable block 2, that is, from entering a region where the balls 3 roll through a gap between the inner seal 5 and the end seal 4. Of course, even if the movable block 2 moves in a direction opposite to the arrow direction indicated in FIG. 11, it is possible to prevent materials adhering to the running rail 1 from entering the movable block 2.As a result, it is possible to prevent substances adhering to the running rail 1, particularly fine foreign matters accumulated in a gap between the cap and the insertion hole 12 of the running rail 1, from entering the movable block 2. As a result, it is possible to prevent abrasion and damage on the ball rolling surface 11 of the track rail 1, the load rolling surface of the movable block 2, or the ball 3 itself. In this way, smooth movement of the movable block 2 with respect to the running rail 1 can be achieved.Further, in the motion guide device to which the present invention is applied, both longitudinal ends of the inner seal 5, particularly, the end surfaces of the leg portions 51 aof the fixing plate 51 are covered by the extended end portions 52 c, and therefore, when the end seals 4 are attached to the movable block 2, the extended end portions can be reliably compressed between the leg portions 51 aof the fixing plate 51 and the seal plates 42 of the end seals 4. With this, the gap between the inner seal 5 and the end seal 4 can be further reliably eliminated, and thus it is possible to prevent foreign matter from entering the movable block 2.Further, the extended end portion 52 cis integrally provided with the seal extended portion 52 a, and therefore the extended end portion 52 calso has the function of reinforcing the seal extended portion 52 a. Therefore, when the seal extended portion 52a is compressed between the fixing plate 51 and the end seal 4, the seal extended portion 52a is prevented from being bent due to the presence of the end extended portion 52c. Therefore, even when the seal extended portion 52 ais brought into close contact with the end seal 4 to be compressed, the sliding contact state of the seal lip portion 52 bprovided in the seal extended portion 52 awith respect to the surface of the running rail 1 is maintained, and thus the sealing performance of the inner seal 5 with respect to the running rail 1 can be ensured.On the other hand, also in the motion guidance device to which the present invention is applied, from the viewpoint of eliminating assembly errors in the motion guidance device due to the tolerance in machining the fixing plate 51, the machining tolerance of the axial length of the fixing plate 51 is set to a negative value. Depending on the actual machining accuracy, a slight gap may be formed between the fixing plate 51 of the inner seal 5 and the pair of lid members 22 for fixing the inner seal 5 with respect to the movable block 2. As a result, the fixing plate 51 of the inner seal 5 can be slightly displaceable with respect to the movable block 2.However, when the pair of end seals 4 are fixed to the front and rear sides of the movable block in the direction of movement thereof, the seal extended portion 52a and the end extended portion 52c of the inner seal 5 are brought into close contact with the smooth surface 46 and the seal plate 42 formed in the end seal 4 to be compressed. Therefore, even if a negative machining allowance occurs in the actual machining of the mounting plate 51, no gap is generated between the inner seal 5 and the end seal 4, and it is possible to reliably prevent foreign matter from entering the movable block 2.Further, in the motion guidance device to which the present invention is applied, when the end seal 4 is fixed to the movable block 2, the seal extended portion 52 aand the end extended portion 52 cof the inner seal 5 are compressed to come into close contact with the end seal. Therefore, it can be recognized that this seal extended portion and the end extended portion neutralize the machining tolerances in the movable block and the inner seal, and even if tolerances occur in machining the inner seal 5 and the block main body 21 as well as the lid members 22 constituting the movable block 2, the movable block can be easily assembled.Note that, in the motion guidance device to which the present invention according to the above-mentioned embodiment is applied, an example in which a ball is used as a rolling element will be described, but a motion guidance device using a roller or the like as a rolling element is also applicable.In the motion guide device according to the above-mentioned embodiment, from the standpoint of preventing the abrasion and damage of the ball rolling surface 11 of the track rail 1, on the load rolling surface of the movable block 2, or on the ball 3 itself, it is necessary to lubricate the balls 3 and the rolling surfaces accordingly according to the use conditions, and the lubrication of these balls 3 and the rolling surfaces is accomplished in many cases by a device for supplying lubricating oil as illustrated in FIG. 12.The above-mentioned lubricating oil supply device 7 includes a housing 71 mounted on the lid member 22 of the movable block 2, and application members 72 stored in the housing 71 and abutting against the ball rolling surfaces 11 of the track rail 1 to supply lubricating oil to the track rail 1. In the application members 72, application parts 72 aare formed to apply the lubricating oil stored in the application members 72 to the ball rolling surfaces 11 of the running rail 1.The lubricating oil supply device 7 arranged as described above is mounted to the lid member 22 of the movable block 2 from the outer side in the moving direction of the movable block 2 as illustrated in FIG. 13. The end seal 4 is fixed to the lubricating oil supply device 7 from the outer side in the moving direction of the movable block 2.In this case, when a gap is formed between the seal extended portion 52 aof the inner seal 5 and the lubricating oil supply device 7, foreign matters adhering to the running rail 1 may enter the movable block 2 through the gap. Therefore, when the lubricating oil supply device 7 is used, it is preferable, as illustrated in FIG. 12, that a pair of the elongated inner seals 8 be connected to the elongated seal portion 52 aand the elongated end portion 52 cof the inner seal 2 to be provided on a lower surface of the lubricating oil supply device 7, that is, at a position opposite to the upper surface of the running rail 1.Each of the elongated inner seals 8 is provided along the ball rolling surface 11 formed on the track rail 1, and includes a mounting plate 81 and a seal portion 82 fixedly attached to the mounting plate 81. Further, an end surface of the seal portion 82 on the end seal 4 side has a similar arrangement to that of the seal extended portion 52 aand the seal extended portion 52 cof the inner seal 5, and a seal extended portion 82 athat protrudes longitudinally from the fixing plate 81 and an end extended portion 82 bthat covers an axial end surface of the fixing plate 81 are formed. Between the pair of elongated inner gaskets 8 arranged as described above are the insertion holes 12 of the slide rail 1.When the lubricating oil supply device 7 arranged as described above is mounted on the lid member 22 of the movable block 2, the seal extended portion 52 aand the end extended portion 52 cof the inner seal 5 are compressed to come into close contact with the end surface of the movable block side extended inner seal 8 provided in the lubricating oil supply device 7, and thus the gap between the extended inner seal 8 and the inner seal 5 is eliminated. When the end seal 4 is mounted on the lubricating oil supply device 7, on the other hand, the extended seal portion 82 aand the extended end portion 82 bof the extended inner seal 8 are compressed and brought into close contact with the smooth surface 46 and the metal surface of the sealing plate 42 of the end seal 4, and thus the gap between the extended inner seal 8 and the end seal 4 is eliminated.With such an arrangement of the elongated inner seal 8 of the lubricating oil supply device 7, a gap can be prevented from being formed between the inner seal 5 and the end seal 4. As a result, foreign matter can be prevented from entering the movable block 2. That is, the elongated inner seal 8 provided for the lubricating oil supply device 7 is joined to the inner seal 5 to form a single inner seal.

Claims

A motion guide device comprising: a running rail (1) having a rolling surface (11) for rolling elements (3) formed along a longitudinal direction thereof; a movable block (2) mounted on the running rail (1) by interposing a large number of rolling elements (3) and having an endless circulation path for the rolling elements (3), the movable block (2) being freely movable along the running rail (1); a pair of first seal members (4) mounted on both end surfaces of the movable block (2) in a moving direction thereof and coming into sliding contact with a surface of the running rail (1) so as to close a gap between the running rail (1) and the movable block (2); a second seal member provided along the rolling surface (11) of the running rail (1) and coming into sliding contact with the surface of the running rail (1) so as to close the gap between the running rail (1) and the moving block (2), the second seal member (5) comprising: a fixing base (51) locked to the moving block (2); and a seal portion (52) fixedly connected to the fixing base (51) along the rolling surface (11) of the running rail (1), the seal portion (52) comprising a seal lip portion (52b) coming into sliding contact with the surface of the running rail (1), the seal portion (52) having both longitudinal ends coming into close contact with the pair of the first seal members (4) in a state, wherein the pair of first sealing members (4) are fixed to the movable block (2), the sealing portion (52) further comprises a pair of elongated sealing portions (52a) protruding in a longitudinal direction of the fixing base (51) from both longitudinal ends of the fixing base (51), and the pair of elongated sealing portions (52a) are compressed in a state where the pair of first sealing members (4) are fixed to the movable block (2), the sealing portion (52) is formed integrally with the pair of elongated sealing portions (52a), and the sealing portion (52) further comprises an elongated end portion (52c) formed to cover an end portion of the fixing base (51) from the longitudinal direction of the fixing base (51).The motion guide device according to claim 1, wherein the movable block (2) comprises: a movable block main body (21) having a rolling element load rolling surface formed therein and a rolling element return hole, wherein the rolling element load rolling surface faces the rolling surface (11) formed in the track rail (1) so as to form a rolling element load path, and wherein the rolling element return hole is disposed so that the rolling elements (3) can rotate; and a pair of lid members (22) fixed to both end surfaces of the movable block main body (21) in a moving direction thereof, and wherein the fixing base (51) is locked to the pair of lid members (22) from both longitudinal ends thereof when the pair of lid members (22) is fixed to the movable block main body (21).

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