Conveyors: power-driven – Conveyor section – Reciprocating conveying surface
Reexamination Certificate
2002-10-30
2004-06-15
Bidwell, James R. (Department: 3651)
Conveyors: power-driven
Conveyor section
Reciprocating conveying surface
C198S750100
Reexamination Certificate
active
06749057
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sliding unit having a guide rail member and a slider fit in the guide member for back-and forth movement with respect to the guide member, and more particularly sealing means for the sliding unit to keep contaminants including debris, metal cuttings, oil mists and so on, which might occur owing to the back-and-forth movement of the slider, against escape outside the sliding units, and also isolate the sliding unit from foreign materials such as oil mists, dust and dirt which might otherwise enter into the sliding unit.
2. Description of the Prior Art
Sliding units constructed as shown in
FIGS. 8 and 9
are conventionally known to work on a diversity of fields including semiconductor manufacturing apparatus, machine tools, various assembling equipments, testing instruments and so on, most of which is expected to work in controlled atmosphere as in a clean room. The prior sliding unit is primarily comprised of an elongated track rail
2
upward opened to have an U-shaped traverse cross-section, a slider
3
B accommodated for lengthwise movement in an U-shaped recess
5
opened upward at
27
of the track rail
2
, a recirculating-ball screw shaft
4
mating with the slider
3
B, and a motor
9
for driving the recirculating-ball screw shaft
4
to turn about its own axis. The recirculating-ball screw shaft
4
is supported for rotation on the track rail
2
at both of a first bearing member
11
installed in an lengthwise end near the motor
9
and a second bearing member
12
installed in the lengthwise opposite end of the track rail
2
, which is fastened to any basement by means of suitable fastener means such as screws. The slider
3
B fits in the track rail
2
for linear movement through rolling elements running through between the slider
3
B and the track rail
2
. A bottom
6
and a pair of upright side walls
7
A define in combination the recess
5
in the track rail
2
. The side walls
7
A are provided on their sidewise opposing inner surfaces with raceway grooves
8
while the slider
3
B has raceway grooves confronting the raceway grooves
8
on the side walls
7
A to define load raceways between them. Rolling elements may run through the load raceway defined between the raceway grooves
8
on the side walls
7
A and the raceway grooves on the slider
3
B, thereby allowing the slider
3
B to move smoothly on the track rail
2
.
The slider
3
B has a pair of widthwise opposing flanges
13
, which are angled upwards to rest thereon an object such as a workpiece table, not shown. The flanges
13
are made with threaded holes
14
for fixture means such as bolts to hold any object thereto. A dustproof cover
15
B is attached to the forward and aft bearing members
11
,
12
so as to shield the track rail
2
with the exception of sidewise clearances
33
where the flanges
13
are allowed to extend sidewise to move back and forth through there. Thus, the dustproof cover
15
B is arranged above the slider
3
B and the recirculating-ball screw shaft
4
, which constitute in combination a torque-to-thrust conversion system for the sliding unit, thereby keeping the contaminants such as dust and debris against entering into and also coming from inside the track rail
2
. The upright flanges
13
of the slider
3
B, on which the object to be carried is loaded, extend widthwise outwardly of the tack rail
2
and then turn upwardly so as to be unobstructed with the dustproof cover
15
B. The slider
3
B has a nut
17
made therein with an internal helical groove that will mate with an external helical groove provided around the recirculating-ball screw shaft
4
. The mating of the screw shaft
4
with the nut
17
constitutes a torque-to-thrust conversion system in which the rotation of the screw shaft
4
allows the nut
17
to move linearly lengthwise of the track rail
2
. The forward and aft bearing members
11
,
12
are mounted on railheads
20
of the upright side walls
7
A of the track rail
2
. The railheads
20
are finished in parallel with the raceway grooves
8
of the track rail
2
.
Sensor rails
22
are disposed on sidewise outsides of the upright side walls
7
A of the track rail
2
, one to each side wall
7
A. The sensor rails
22
are each provided with a limit sensor
23
at any preselected place to sense the associated flange
13
during back-and-forth movement, followed by issuing the detected signal to a controller through a lead wire
24
and a sensor connector
25
. The motor
9
is energized depending on any control signal applied through a motor connector
28
to produce a torque transmitted to the recirculating-ball screw shaft
4
via a coupling
30
. A fore-and-aft range over which the slider
3
B is allowed to travel is defined with stoppers
31
,
32
that are secured to the bearing member
11
,
12
, one to each bearing member.
In Japanese Patent Laid-Open No. 325070/1999, for example, there is disclosed a sealing construction for the sliding unit constructed as stated earlier, in which bellows-like sealing means are installed at the sidewise clearances
33
to keep foreign matter such as dust, debris and so on against entering into and coming from inside the sliding unit through the sidewise clearances
33
. The bellows-like sealing means are each composed of at least one sealing member expansible owing to its own elasticity, which is secured to anyone of the confronting lengthwise edges of the upright side wall
7
A of the track rail
2
and the dustproof cover
15
B to close the associated clearance
33
. When the slider
3
B travels with respect to the track rail
2
along the clearances
33
, the sealing members are easily subject to the elastic expansile and collapsed deformation and thus thrust aside by the action of the moving flanges
13
.
Another example of the sealing constructions for the sliding unit made as stated earlier is disclosed in Japanese Patent Laid-Open No. 27235/2001, which is the senior application of the present applicant. With this prior sealing construction, the expansible sealing members are arranged in gaps between the track rail and the dustproof cover in a manner allowing the flanges to travel along the gaps as the slider moves relatively to the track rail. Each expansible sealing member is composed of upper and lower sealing parts that are urged elastically against each other to close the associated gap. When the flange travels along the associated gap, the upper and lower sealing parts are shoved apart from each other at only a region closely neighboring the moving flange to allow it to travel between the sealing parts, with keeping a sliding contact with the opposite surfaces of the moving flange. At the residual regions before and after the moving flange, however, the upper and lower sealing parts are kept in abutment against each other due to their own elasticity. The lower sealing part is made greater in elastic force than the upper sealing part to compensate the influence of gravity. Moreover, the upper and lower sealing parts are made in an elongated configuration that is attached at one lengthwise side thereof to any one edge of the gap and abutted against the counterpart with their own elasticity.
There are also known a conveying system with dust proofing means of the type disclosed in, for example, Japanese Patent Laid-Open No. 187906/2001. The conveying system is made of a rodless cylinder that includes a cylinder tube and a table moving in and out along the cylinder tube. A mounting stage is fastened to the table while a covering member is attached to the cylinder tube. A dustproof member is held between an inside surface of the covering member and any one of side surfaces of the cylinder tube and the mounting stage. The dustproof member may be subjected to elastic deformation in a sidewise direction that is perpendicular to a direction along which the table moves in and out.
With most prior sliding units constructed as stated earlier, nevertheless, any sidewise slits or clearances are left uncovered between
Bidwell James R.
Browdy and Neimark
Nippon Thompson Co. Ltd.
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