JPH1046505A - Rail device for carrying equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rail device by which assembling of respective rails through a yoke member can be easily, quickly and accurately performed. SOLUTION: Connection of an upper rail 11 is performed by screw-fitting a nut body 14 to a stud bolt 12 after the stud bolt 12 is inserted into a yoke material 20 side hole. Connection of a lower rail 15 is performed by operating a fixing tool 18 after a hole of the lower rail 15 is communicated with the yoke member 20 side hole. Connection of the respective rails 11 and 15 through the yoke member is easily and quickly performed by operation of the nut body 14 and the fixing tool 18. Erection of the stud bolt 12 in the upper rail 11, the formation of the hole in the lower rail 15 and the formation of the hole in the yoke member 20 are accurately and easily performed on the aboveground side by using respective ones as a single product, and accuracy of an assembled rail device 10 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rail device for a transport facility used in a suspended transport facility for transporting a vehicle body on a fixed path on a ceiling side, for example, in an automobile assembly factory.

[0002]

2. Description of the Related Art Conventionally, as this type of transfer equipment, there has been provided a structure as disclosed, for example, in Japanese Utility Model Publication No. 58-44044. That is, a power rail made of an I-shaped material,
A pair of free rails, which are made of a C-shaped member and whose open portions are opposed to each other, are provided, and these rails are connected by a connection frame at required intervals. Both free rails support and guide the carrier via a free trolley, and a chain-type power trolley that applies a moving force to the carrier side is supported and guided by the power rail.

[0003]

However, according to the above-mentioned conventional type, each rail and the connection frame are connected by welding, and welding with high accuracy between the rails cannot be easily performed. Also, the accuracy between the rails cannot be easily achieved as desired.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rail device for a transportation facility which can easily, quickly and accurately assemble each rail via a yoke material. It is.

Another object of the present invention is to provide a rail device for a transportation facility which can further improve the accuracy.

[0006]

In order to achieve the above-mentioned object, according to the present invention, a rail device for a transport facility according to the first aspect of the present invention comprises an upper rail, a pair of lower rails, and a space between each rail. It is a rail device for transport equipment comprising a gate-shaped yoke material provided at a predetermined position in a rail length direction for coupling, wherein the upper rail is a stud bolt that is erected from the upper surface of the upper rail. The lower rail is connected to the yoke material via a fixing tool penetrating through the lower rail.

Therefore, according to the first aspect of the present invention, before assembling the rail device, stud bolts are erected on the upper surface of the upper rail at the predetermined position on the upper plate portion, and the stud bolts are fixed on the side plate portions of the lower rail at the predetermined position. To form a hole,
Holes for stud bolts and fixtures are formed at predetermined locations on the connecting piece on the yoke material side. To assemble the rail device, the upper rail can be connected by passing a stud bolt through the hole on the yoke material side from below, and then screwing a nut body into a protruding portion of the stud bolt. The connection of the left and right lower rails can be performed by connecting the holes of the lower rails to the holes on the yoke material side and then applying a fixing tool.

At this time, the connection of the rails via the yoke material can be easily and quickly performed by a screwing operation of the nut body. In addition, the stud bolts on the upper rail, the holes on the lower rail, the holes on the yoke material, etc. can be easily and accurately made on the ground side as a single item. Will be good.

According to a second aspect of the present invention, there is provided a rail device for a transport facility according to the first aspect.
The yoke material is integrally provided with an upper connecting piece and a pair of lower connecting pieces along the rail length direction, and the upper connecting piece is connected to the upper rail and the lower connecting piece is connected to the lower rail. It is characterized by the following.

Therefore, according to the second aspect of the invention, the yoke member is provided integrally with the upper connecting piece and the lower connecting piece by bending. The upper rail can be connected to the yoke material side via a stud bolt or an upper connecting piece, and the left and right lower rails can be connected to the yoke material side via a fixture, a lower connecting piece, or the like. Moreover, the bending of each connecting piece in the yoke material can be easily and accurately performed on the ground side using this yoke material as a single item.

According to a third aspect of the present invention, there is provided a rail device for a transport facility according to the first aspect of the present invention, wherein the upper connecting member and the pair of lower connecting members are fixed to the yoke member by a fixing tool. The upper rail is connected to the upper rail through stud bolts, and the lower rail is connected to the lower rail through a fixture.

Therefore, according to the third aspect of the present invention, by fixing both rails to the yoke member via the upper connecting member and the lower connecting member, the shape of the yoke member can be simplified and the two connecting members can be connected to each other. The connection with the yoke material can be easily and quickly performed, for example, via a bolt-nut type fixing device.

According to a fourth aspect of the present invention, there is provided a rail device for a transport facility according to the first aspect of the present invention, wherein the rail device is provided between the upper rail and the yoke material side and between the lower rail and the yoke material side. , Characterized in that a position adjusting material is interposed at a required position.

Therefore, according to the fourth aspect of the present invention, when assembling the rail device, a relative position between the upper rail and the lower rail can be obtained by appropriately interposing a position adjusting member having a required thickness (required amount). The vertical distance and the relative horizontal distance between both lower rails can be adjusted with high precision.

According to a fifth aspect of the present invention, there is provided a rail device for a transport facility according to the first aspect of the present invention, wherein the lower rail guides and supports the moving body, and applies a moving force to the moving body. The transfer device is characterized in that the driving body using the chain is supported and guided by the upper rail.

Therefore, according to the fifth aspect of the present invention, at the time of operation after the intended assembling of the rail device and the assembling of the transport device, the moving body moves on a fixed path by receiving the moving force of the driving body. I can do it. At that time, the moving body is fitted and supported and guided by the lower rail, and is guided between the lower rails, so that it can be prevented from contacting the exposed portion of the fixture due to swing, Thus, the vehicle can stably move on a fixed route. In addition, even if the driving body vibrates (runs) in the vertical direction within the regulation range when being moved while being supported and guided by the upper rail, a stud bolt which is not exposed to the inside is used as a connecting means of the upper rail. By doing so, the roller can move smoothly without contacting other objects such as connecting means.

According to a sixth aspect of the present invention, there is provided a rail device for a transfer facility according to the first aspect of the present invention.
The upper rail is made of I-shaped material, and a pair of lower rails is
The open portion is made of opposed C-shaped members.

Therefore, according to the sixth aspect of the present invention, the most suitable rail device for a transport facility can be assembled with high accuracy.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
A description will be given, with reference to FIGS. 1 to 3, of a state adopted in a suspended transfer facility (an example of a transfer facility) for transferring a conveyed object on a fixed path on the ceiling side. The suspended transfer equipment 1 includes a rail device 10 and a transfer device supported and guided by the rail device 10.
Consists of 30

The rail device 10 includes an upper rail 11 made of an I-shaped member, a pair of lower rails 15 made of a C-shaped member and having open portions opposed to each other, and a connection between the rails 11 and 15. It is composed of a gate-shaped yoke member 20 provided at a predetermined position in the rail length direction.

The yoke member 20 is in the form of a gate-shaped plate, and an upper connecting piece 21 along the rail length direction is integrally provided from the lower edge at the center of the upper plate portion by bending in a right angle direction. The upper connecting piece 21 has a pair of left and right (single or plural) upper bolt holes 22. Further, from the inner edge of the lower part of the both side plate portions of the yoke material 20, lower connecting pieces 23 along the rail length direction are integrally provided by bending in a right angle direction, and four (single or (A plurality of) lower bolt holes 24 are formed.

The upper rail 11 is connected to the upper connecting piece 21. That is, a pair of left and right (single or plural) stud bolts 12 are erected by crimp welding on the upper surface of a predetermined portion of the upper plate of the upper rail 11. Then insert the stud bolt 12 into the upper bolt hole 22
After passing through the stud bolts 12
The upper rail 11 is connected to the yoke member 20 via the stud bolt 12 and the upper connecting piece 21 by fitting the nut 13 outside and screwing the nut body 14.

The lower rail 15 is passed through the lower connecting piece 23, and a fixing tool, that is, a round head bolt is inserted through the lower rail 15.
It is configured to be connected via a fixture 18 including a caulking nut 17 and the like. For that, lower rail 15
The four (single or plural) connection holes 19 are formed in the side plate portion at the predetermined location. And connection holes
After connecting 19 to the lower bolt hole 24, the round head bolt 16 is passed through the connection hole 19 side, and the caulking nut 17 is screwed into the protruding part of the round head bolt 16 to be caulked. 15 is connected to the yoke member 20 side via a fixture 18 and a lower connecting piece 23.

A connection hole 25 is formed in the upper plate portion of the yoke member 20 or the like. Above 11 ~ 25 by rail equipment
10 are configured. The yoke member 20 is connected to a bracket 27 from, for example, a ceiling structure (not shown) via a connector 28 such as a bolt and a nut.

The rail device 10 constructed as described above
In, the lower rail 15 guides the moving body,
The upper rail 11 supports and guides a driving body using a chain that applies a moving force to the moving body.

That is, a trolley device 31 which is an example of a moving body
Is a front trolley 32, a free trolley 33, a rear trolley 34, a connecting rod 35 connecting the front trolley 32 and the free trolley 33, a free trolley 33 and a rear trolley.
It is composed of a connecting frame 37 for connecting between trunnion pins 36 continuously provided from 34. And each trolley 32, 3
3 and 34, a guide wheel 38 fitted and supported on the lower rail 15 and a run-out preventing wheel 39 guided between the end faces of the lower plate portions of both lower rails 15 are provided. Each is provided.

The front trolley 32 has a passive body 40 which can be disengaged from a transmission (described later) from the driving body.
Is provided so as to be able to move up and down, and an operation lever 42 attached to the middle so as to be able to swing up and down via a horizontal shaft 41 is extended forward, and a rear end of the operation lever 42 and a lower end of the passive body 40 are Are connected via pins. Therefore, the operating lever 42 and the passive body 40 are linked so that the passive body 40 descends when the front end of the operating lever 42 moves upward.

At the upper end of the front trolley 32,
In the position behind 40, when the transmission and the passive body 40 are engaged,
A runaway preventing body (hold dog) 43 for preventing the passive body 40 from running away forward is provided. The runaway preventing body 43 is configured to be swingable back and forth via a pin, and normally, its upper end is urged by a weight portion so as to protrude into the moving path of the transmission. The other rear trolley 33 has a cam tail 44 extending rearward to move the operation lever 42 upward.

The trolley device 31 is provided with a support device 45 for a transferred object. That is, the supporting device 45 includes a C neck 46 attached to the lower ends of the trunnion pins 36,
An arm 47 attached to the lower portion of the C-neck 46 and extending downward, and a support portion 48 provided horizontally at the lower end of the arm 47
Etc. Numeral 75 indicates a transferred object.

A driving body 50 using a chain that is supported and guided by the upper rail 11 and applies a moving force to the trolley device 31.
Is a link chain 51 arranged along the upper rail 11.
A trolley portion 52 provided at a predetermined position in the chain length direction of the link chain 51;
Is disposed near the link chain 51, and the passive body 40 is constituted by a disengageable transmission body 56 and the like.

The trolley part 52 is connected to the link chain 51
A pair of left and right trolley bodies 53 provided at the center link of the trolley, and one end (upper part) of these trolley bodies 53
The upper rail 11 is supported and guided on the upper surface of the lower plate of the upper rail 11 by rollers 55 freely rotatably provided through the roller 54 and the like. The link chain
Reference numeral 51 is linked to a drive unit (not shown by a motor or the like).

The operation of the above embodiment will be described below. Before assembling the rail device 10, the upper rail
A stud bolt 12 is provided upright on the upper surface of a predetermined portion of the upper plate portion 11 by crimp welding. The lower rail 15 has a connecting hole 19 formed in a side plate portion at a predetermined position. Further, the yoke member 20 is formed in a gate-shaped plate shape, and the upper connecting piece 21 and the lower connecting piece 23 are integrally provided by bending, and bolt holes 22 and 24 are formed at predetermined positions of these connecting pieces 21 and 23. ing.

To assemble the rail device 10,
For the upper rail 11, insert the stud bolt 12 into the upper bolt hole.
After passing through the stud bolt 12 from below, the washer 13 is externally fitted to the protruding portion of the stud bolt 12, and the nut body 14 is screwed into the stud bolt 12, whereby the stud bolt 12 is connected to the yoke member 20 via the upper connecting piece 21 and the like. After connecting the connection hole 19 to the lower bolt hole 24, the left and right lower rails 15 pass the round head bolt 16 from the connection hole 19 side, and the caulking nut 17 is screwed into the protruding portion of the round head bolt 16. By caulking together, it is connected to the yoke member 20 via the fixture 18 and the lower connecting piece 23.

At this time, each rail through the yoke member 20
Connection of 11 and 15 is performed by screwing nut body 14 and caulking nut
By screwing 17 and caulking, it can be done easily and quickly. Moreover, the stud bolts 12 are erected on the upper rail 11,
The formation of the connection holes 19 in the lower rail 15, the bending of the connection pieces 21, 23 in the yoke material 20, the formation of the bolt holes 22,
The formation and the like of 24 can be performed individually and easily with high accuracy on the ground side, and thus the assembled rail device 10 has high accuracy.

Before or after assembling the rail device 10, the yoke member 20 is connected to a bracket 27 from the ceiling structure side via a connecting member 28 such as a bolt and a nut. Is installed on the ceiling side.

Desired assembly and transport device of rail device 10
At the time of operation after installation of 30 etc., the trolley device
The movement of 31 is performed on a fixed path by engaging the power transmitting body 56 with the passive body 40 and receiving the moving force of the driving body 50.
At this time, the operation lever 42 has its front end moved downward. When the trolley device 31 attempts to run away during such movement, the runaway preventing body 43 comes into contact with the rear surface of the transmission 56, so that runaway is prevented.

During the operation as described above, the trolley device 31 is supported and guided by the guide wheel 38 fitted on the lower rail 15, and the anti-vibration wheel 39 is connected to the end surface of the lower plate of the lower rail 15. By being guided in the middle, it is possible to prevent the guide wheel 38 from coming into contact with the exposed round head of the round head bolt 16 due to the run-out, thereby being stably moved on a fixed path.

The driving body 50 is moved while its rollers 55 are supported and guided by the upper rail 11. At this time, even if the driving body 50 vibrates (vibrates) in the vertical direction within the restricted range, the driving rail 50 moves. By using the stud bolts 12 which are not exposed to the inside as the connecting means, the roller 55 is smoothly moved without contacting other objects such as the connecting means.

Next, another embodiment of the present invention will be described with reference to FIG.
A description will be given based on FIG. The yoke member 60 has a gate-shaped plate shape, and an upper connector 65 is fixed to a central portion of the upper plate portion via a fixture 68, and a lower connector 70 is provided at a lower portion of both side plate portions with a fixture 73, respectively. Has been fixed through. That is, a pair of left and right (single or plural) upper connection holes 61 are formed at the center of the upper plate portion of the yoke member 60, and a pair of upper and lower (single or plural) upper and lower portions are formed at the lower portions of both side plate portions. A lower connection hole 62 is formed.

Each of the connecting members 65 and 70 is made of a short L-shaped member, and a pair of left and right (single or plural) upper connecting holes 66 and upper bolt holes 67 are formed on both sides of the upper connecting member 65, respectively. Are formed. A pair of upper and lower (single or plural) lower connecting holes 71 is formed on one side of the lower connecting body 70, and four (single or plural) lower bolt holes 72 are formed on the other side. I have.

The upper connector 65 has a hole for the upper connector.
After the 66 is communicated with the upper connection hole 61 of the yoke member 60, a fixing member 68 made of a bolt and a nut is acted between the two holes 66 and 61, so that the yoke member 60 has an L-shaped side view. Fixed. Further, after the lower connecting body 70 communicates the lower connecting hole 71 with the lower connecting hole 62 of the yoke material 60,
By applying a fixing member 70 composed of a bolt and a nut between the first and the second 62, the fixing member 70 is fixed to the yoke member 60 in an L shape in plan view.

Further, the stud bolt 12 is inserted into the upper bolt hole 67.
After passing through the stud bolts 12
The upper rail 11 is connected to the yoke member 60 via the stud bolt 12 and the upper connecting body 65 by fitting the nut 13 outside and screwing the nut body 14. Also, after connecting the connecting hole 19 to the lower bolt hole 72, the round head bolt is connected from the connecting hole 19 side.
16 and screw the nut into the protruding part of this round head bolt 16
By screwing 17 and caulking, the lower rails 15 on the left and right
The yoke member 60 is connected to the yoke member 60 via the fixture 18 and the lower connector 70.

When the connection is made via the stud bolts 12 and the fixtures 18 as described above, the upper rail 11 and the upper connecting body are connected.
Between 65 (on the yoke member 60 side) and between the lower rail 15 and the lower connecting member 70 (on the yoke member 60 side), position adjusting members 69 and 74 are interposed at required locations.

According to this alternative embodiment, the upper link
By fixing the rails 11 and 15 to the yoke member 60 via the lower connecting member 65 and the lower connecting member 70, the shape of the yoke member 60 can be simplified, and the connection between the two connecting members 65 and the yoke member 60 can be simplified. Can be easily and quickly carried out, for example, via bolts and nuts 68, 73. Then, when assembling the rail device 10, the position adjusting material 69,
With the interposition of 74, the relative vertical distance between upper rail 11 and lower rail 15, and the relative horizontal distance between lower rails 15 can be adjusted with high accuracy.

Next, still other various embodiments of the present invention will be described with reference to FIGS. That is, FIG.
In A, an upper rail 11 made of an I-shaped member is connected by stud bolts 12, and a pair of lower rails 15A made of an L-shaped member are connected by a fixture 18. In FIG. 6B, the upper rail 11 made of an I-shaped member is connected by a stud bolt 12, and a pair of lower rails 15B made of an inverted L-shaped member are connected by a fixture 18.

In FIG. 6C, the upper rail 11A made of a wide C-shaped member is connected by the stud bolt 12,
A pair of lower rails 15 made of a C-shaped member are connected by a fixture 18. Further, in FIG. 6D, upper rails 11B made of narrow C-shaped members are connected by stud bolts 12, and a pair of lower rails 15 made of C-shaped members are connected by fixtures 18.

In FIG. 6E, an upper rail 11A made of a wide C-shaped member is connected by a stud bolt 12, and
A pair of lower rails 15A made of a letter-shaped material are connected by a fixture 18. In FIG. 6F, upper rails 11A made of wide C-shaped members are connected by stud bolts 12, and a pair of lower rails 15B made of inverted L-shaped members are fixed.
Connected by 18. In E and F of FIG. 6, FIG.
Upper rail 11B made of narrow C-shaped material as shown by D
May be connected by stud bolts 12.

Further, in FIG. 6G, a pair of upper rails 11C made of a C-shaped member, whose open portions are opposed to each other, are connected by stud bolts 12, and a pair of lower rails 15 made of a C-shaped member are fixed to fixtures 18. Are connected by FIG. 6
6G, a pair of lower rails 15A made of an L-shaped member and a pair of lower rails 15B made of an inverted L-shaped member may be connected by a fixture 18, as shown in FIGS. 6A and 6B.

In the above-described embodiment, the fixing tool 18 penetrating through the lower rail 15 and connecting the lower rail 15 to the yoke member 20 is constituted by the round head bolt 16 and the caulking nut 17. However, this may be a normal bolt nut or rivet.

In the above-described embodiment, the type in which the driving body 50 using a chain is supported and guided by the upper rail 11 is shown. This is because the trolley device 31 is supported by the self-propelled body supported and guided by the upper rail 11. May be provided in a form that imparts a moving force to the vehicle.

In the embodiment described above, the passive body 40 is engaged and disengaged with respect to the transmission body 56. However, this may be a configuration in which the transmission body 56 is engaged and disengaged with respect to the passive body 40. . In another embodiment described above, the upper rail 11 and the upper connector 65
And between the lower rail 15 and the lower connector 70, the position adjusting members 69 and 74 are interposed. In the embodiment, this is between the upper rail 11 and the upper connecting piece 21, The type in which the position adjusting members 69 and 74 are interposed between the lower rail 15 and the lower connecting piece 23 may be used.

[0052]

According to the first aspect of the present invention, the connection of the rails via the yoke material can be easily and quickly performed by a screwing operation of the nut body. Moreover,
Standing of stud bolts on the upper rail, formation of various holes in the lower rail, formation of various holes in the yoke material, etc. can be performed individually and easily with high precision on the ground side. The device can be of high precision.

According to the second aspect of the present invention,
The yoke material can be provided integrally by bending the upper connecting piece and the lower connecting piece. The upper rail can be connected to the yoke material side via stud bolts or upper connection pieces, and the left and right lower rails can be connected to the yoke material side via fixtures or lower connection pieces. In addition, the bending of each connecting piece in the yoke material can be easily and accurately performed on the ground side using this yoke material as a single item.

According to the third aspect of the present invention, the two rails are fixed to the yoke member via the upper connector and the lower connector, whereby the shape of the yoke can be simplified. The connection between the connecting body and the yoke material can be easily and quickly performed via a fixing device of a bolt-nut type, for example.

Further, according to the fourth aspect of the present invention, when assembling the rail device, by appropriately interposing a position adjusting material having a required thickness (required amount), the upper rail and the lower rail can be connected to each other. The relative vertical distance and the relative horizontal distance between both lower rails can be adjusted with high accuracy, and the assembling accuracy of each rail via the yoke material can be further improved.

Further, according to the fifth aspect of the present invention, the moving body is supported and guided by being fitted to the lower rail, and is guided by being positioned between the lower rails.
It is possible to prevent the fixture from coming into contact with the exposed portion of the fixture due to the run-out, and thus it is possible to stably move on a fixed path. Further, even when the driving body is vibrated (runs) in the vertical direction within the regulation range when moving while being supported and guided by the upper rail, a stud bolt which is not exposed to the inside is used as the connecting means, so that the connecting means is used. It can move smoothly without touching other things.

According to claim 6 of the present invention,
The most suitable rail device for transport equipment can be assembled with high accuracy.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of the present invention and is a perspective view of a main part of a rail device for transport equipment.

FIG. 2 is a partially cutaway front view of a main part of the rail device for the transport facility.

FIG. 3 is a side view of a main part of the transport equipment.

FIG. 4 shows another embodiment of the present invention, and is a partially cutaway front view of a main part of a rail device for transport equipment.

FIG. 5 is a side view of a main part in the rail device for the transport equipment.

FIG. 6 illustrates still other various embodiments of the present invention from AG
It is a schematic front view of the rail apparatus for conveyance facilities shown by.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hanging conveyance equipment (transportation equipment) 10 Rail device 11 Upper rail 12 Stud bolt 14 Nut body 15 Lower rail 16 Round head bolt 17 Caulking nut 18 Fixture 20 Yoke material 21 Upper connection piece 23 Lower connection piece 30 Transfer device 31 Trolley Equipment (moving body) 38 Guide wheel 39 Wheel for preventing run-out 40 Passive body 45 Supporting device 50 Drive unit using chain 55 Roller 56 Transmission body 60 Yoke material 65 Upper linking body 68 Fixture 69 Position adjusting material 70 Lower linking body 73 Fixture 74 Position adjustment material

Claims (6)

[Claims] 1. A rail device for a transport facility comprising an upper rail, a pair of lower rails, and a gate-shaped yoke material provided at a predetermined position in a rail length direction for connecting the rails. The upper rail is connected to the yoke material via stud bolts erected from the upper surface of the upper rail, and the lower rail is connected to the yoke material via a fixture penetrated through the lower rail. A rail device for a transport facility, characterized in that: 2. The yoke member is provided with an upper connecting piece and a pair of lower connecting pieces along the rail length direction. The upper connecting piece is connected to the upper rail and the lower connecting piece is connected to the lower connecting piece. The rail is connected, The rail is connected.
A rail device for the transport equipment described. 3. The yoke member has an upper connecting body and a pair of lower connecting bodies fixed to each other via a fixture, and an upper rail is connected to the upper connecting body via stud bolts.
The rail device according to claim 1, wherein the lower rail is connected to the lower link via a fixture. 4. The transport equipment according to claim 1, wherein a position adjusting member is interposed between the upper rail and the yoke member side and between the lower rail and the yoke member side at a required position. Rail device. 5. The lower rail guides and supports the moving body,
The rail device for a transport facility according to claim 1, wherein the transport device is configured by supporting and guiding a chain-type driving member that imparts a moving force to the movable member on an upper rail. 6. The rail device according to claim 1, wherein the upper rail is made of an I-shaped member, and the pair of lower rails is made of a C-shaped member whose open portions are opposed to each other.