Bearings – Linear bearing – Recirculating
Reexamination Certificate
2001-10-11
2003-03-18
Footland, Lenard A. (Department: 3682)
Bearings
Linear bearing
Recirculating
Reexamination Certificate
active
06533458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear motion guide unit including therein recirculating passages in which rolling elements are allowed to run along the recirculating passages, and separators are each arranged between any two adjoining rolling elements and joined together with each other by means of chain couplers.
2. Description of the Prior Art
Conventionally a linear motion guide unit of the type as shown in
FIG. 21
is well-known in which only rolling elements such as balls, rollers and so on are installed in a recirculating passage. The prior linear motion guide unit comprises an elongated track rail
2
having raceway grooves
4
on lengthwise side surfaces thereof, and a slider
1
having raceway grooves
9
confronting the raceway grooves
4
of the track rail
1
. The slider
2
fits over and conforms to the track rail
2
for sliding movement with respect to the track rail
2
. The slider
2
will move along the track rail
1
by virtue of rolling elements
7
such as balls, which are allowed to run in load raceways
16
defined between the confronting raceway grooves
4
and
9
. The track rail
2
has openings
13
boring through from an upper surface
14
to a bottom surface thereof at locations spaced lengthwise from each other. The track rail
2
will be fastened to the mounting base
20
, such as a bed, machine base, work table or the like, by screwing bolts through the openings
13
of the track rail
2
into threaded holes in the mounting base
20
.
The slider
1
has a carriage
5
movable relatively to the track rail
2
, and end caps
6
secured to the opposite ends of the carriage
5
, each to each end. Provided on the upper surface of the carriage
5
are openings
19
for mounting the slider
1
to other appliances, parts, chucks, grasping jaws or the like. The end caps
6
are attached on the lengthwise opposing end surfaces of the carriage
5
by means of more than one bolt
25
. Both of the carriage
5
and the end caps
6
are made with recesses
10
that are opened downwards such that the carriage
5
and the end caps
6
are allowed to fit over and conform to the track rail
2
for sliding movement relatively to the track rail
2
. The carriage
5
is also provided therein with return passages
12
extending in parallel with the raceway grooves
9
. The end caps
6
are provided therein with claws for scooping the rolling elements
7
out of the load raceways
16
defined between the confronting raceway grooves
4
and
9
, and turnaround passages, given the reference numeral
15
in
FIG. 13
, for recirculation of the rolling elements
7
.
In the linear motion guide unit described earlier, retainer bands
18
are provided in the carriage
5
to hold the rolling elements
7
, thereby preventing the rolling elements
7
from falling out of the carriage
5
. Bottom seals
8
are secured to the lower surfaces of the carriage
5
and the end caps
6
to thereby close clearances between the track rail
2
and the slider
1
. Also mounted on the outside end faces of the end caps
6
are end seals
17
, each to each end cap, for keeping sealing function between the track rail
2
and the lengthwise opposing ends of slider
1
.
The rolling elements
7
run along the load areas, that is, the load raceway
18
defined between the raceway grooves
4
of the track rail
2
and the raceway grooves
9
of the carriage
5
, and then come in the turnaround passages
15
in any one of the end caps
6
. The rolling elements
7
further run from the turnaround passages
15
to the return passages
12
that are formed in the carriage
5
in parallel with the load raceway grooves
9
. Subsequently the rolling elements
7
return to the load areas of the raceways
16
through the turnaround passages
15
in the other one of the end caps
6
. It will be thus understood that the rolling elements
7
may run in a recirculating manner though recirculating passages given the reference numeral
21
in
FIG. 13
, which are composed of the load raceways
16
, turnaround passages and return passages
12
, thereby helping ensure the smooth movement of the slider
1
relatively to the track rail
2
. Installed on any one of the forward and aft end seals
17
is a grease nipple
11
through which lubricant is supplied into the carriage
5
to lubricate the raceway grooves
4
and
9
along which run the rolling elements
7
.
With the conventional linear motion guide units constructed as stated earlier, any separator is interposed between any two adjoining rolling elements to keep the rolling elements against coming into rolling collision with one another, which might cause any contact force opposite in direction. Moreover, various other linear motion guide units have been devised heretofore, which are called the chain-type linear motion guide unit because of their specific construction in which the separators are joined together with each other by endless chains of couplers. Disclosed in Japanese Patent Laid-Open No. 247855/1999 is a linear motion guide unit in which the rolling elements or balls running through a recirculating passage are spaced apart from each other by separators that are each interposed between any two adjoining balls and interconnected with each other through strings in such an individually replaceable manner. Each separator is comprised of a major body made at forward and aft faces thereof with ball-contact surfaces for carrying the associated balls thereon, and webs formed integrally with the major body and extended fore-and-aft along the running direction over the spherical surfaces of the balls, and the webs being each provided therein with channels. The separators arranged in the recirculating passage with being each interposed between any two adjoining balls are interconnected with one another by using a string threading through the channels in the webs.
Further, Japanese Patent No. 2607993 discloses a linear motion guide unit having incorporated with a chain of balls, which is comprised of a series of balls running through a recirculating passage, ball retainers each interposed between any two adjoining balls, and a flexible coupler member for joining together the balls and retainers in a tandem array. The ball retainers are each made concaved at forward and aft faces thereof so as to fit snugly over the associated balls in a manner allowing the ball retainer to move relatively to the associated balls. Thus, a series of balls may be made in an endless form by bending the flexible coupler member in a loop. With the ball chain recited earlier, however, there is some tendency in which the concaved surfaces of the ball retainer, when running through the turnaround, are drawn radially inwardly of a curvature of locus of rolling-contact point between the ball retainer and the associated ball, thus causing much deformation in the ball retainer at the area between the concaved surfaces that are opposite sides of the ball retainer. As a result, there is a possibility that the flexible coupler member might be much subject to deformation at the area between the concaved surfaces because the flexible coupler member is less in thickness at the area between the concaved surfaces.
Disclosed in Japanese Patent Laid-Open No. 89358/1998 is another linear motion guide unit, in which the balls fit in the flexible coupler member with being positioned at regular intervals in tandem along their moving direction. In need of repair or replacement of the ball, any ball may be removed from the coupler member by only pressing out the ball towards any raceway groove of the load raceway where the balls run through there.
Another Japanese Patent Laid-Open No. 351255/1999 discloses a coupler arrangement for a series of rolling elements, which is comprised of a carrier strip of flexible element made therein with a series of openings to accommodate therein rolling elements, and holder elements to keep in position the rolling elements fit in the openings. The carrier strip is composed of sidewise opposing lengthwise edges and tra
Browdy and Neimark , P.L.L.C.
Footland Lenard A.
Nippon Thompson Co. Ltd.
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