U.S. patent application number 14/955276 was filed with the patent office on 2016-04-21 for linear motion bearing system with self-aligning rail.
The applicant listed for this patent is Thomson Industries, Inc.. Invention is credited to ALISON NG.
Application Number | 20160108956 14/955276 |
Document ID | / |
Family ID | 44511522 |
Filed Date | 2016-04-21 |
United States Patent
Application |
20160108956 |
Kind Code |
A1 |
NG; ALISON |
April 21, 2016 |
LINEAR MOTION BEARING SYSTEM WITH SELF-ALIGNING RAIL
Abstract
A linear motion bearing system that includes a rolling element
retainer structure having at least a portion of a plurality of open
axial rolling element tracks formed therein. The rolling element
tracks includes an open load-bearing portion, an open return
portion and turnarounds interconnecting the load bearing and return
portions. Bearing rolling elements are disposed in the rolling
element tracks. Load bearing outer races are axially positioned
adjacent the rolling element retainer structure for receiving load
from the rolling elements disposed in the load-bearing portion of
the rolling element tracks. An outer housing sleeve is effective to
hold the rolling element retainer structure. A rail is effective to
mate with the rolling element retainer structure, the rail
including at least one recess sized and shaped so as to be mateable
with at least one of the bearing rolling elements.
Inventors: |
NG; ALISON; (New York,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Thomson Industries, Inc. |
Amherst |
NY |
US |
|
|
Family ID: |
44511522 |
Appl. No.: |
14/955276 |
Filed: |
December 1, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13812608 |
Apr 5, 2013 |
9217466 |
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PCT/US11/45478 |
Jul 27, 2011 |
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14955276 |
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61368404 |
Jul 28, 2010 |
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Current U.S.
Class: |
384/43 |
Current CPC
Class: |
F16C 19/54 20130101;
Y10T 29/49696 20150115; F16C 29/0685 20130101; F16C 43/04 20130101;
F16C 23/06 20130101 |
International
Class: |
F16C 29/06 20060101
F16C029/06 |
Claims
1. A linear motion bearing system comprising: a rolling element
retainer structure having at least a portion of a plurality of open
axial rolling element tracks formed therein, said rolling element
tracks including an open load bearing portion, an open return
portion and turnarounds interconnecting the load bearing and return
portions; a plurality of bearing rolling elements disposed in the
rolling element tracks; a plurality of load bearing outer races
axially positioned adjacent the rolling element retainer structure,
the load bearing outer races effective to receive load from the
rolling elements disposed in the load bearing portion of the
rolling element tracks; an outer housing sleeve effective to hold
the plurality of load bearing outer races; and a rail effective to
mate with the rolling element retainer structure, the rail
including at least one recess sized and shaped so as to be mateable
with the rolling element retainer structure.
2. The linear motion bearing system as recited in claim 1, wherein
the rail includes a base portion effective to mate with the rolling
element retainer structure.
3. The linear motion bearing system as recited in claim 2, wherein
the base portion is a rectangular solid.
4. The linear motion bearing system as recited in claim 1, wherein
the recess has a half-cylinder shape.
5. The linear motion bearing system as recited in claim 1, wherein
the rail has a hollow interior effective to receive at least a
portion of the rolling element retainer structure.
6. The linear motion bearing system as recited in claim 1, further
comprising a bearing outer race to housing intermediary load
structure, the bearing outer race to housing intermediary load
structure comprising a plurality of pieces and defining at least
two spaces in between the pieces, the bearing outer race to housing
intermediary load structure extending circumferentially around the
outer housing sleeve.
7. The linear motion bearing system as recited in claim 6, wherein
the rail has a hollow interior effective to receive at least a
portion of the rolling element retainer structure; and the bearing
outer race to housing intermediate load structure is placed at an
inner race portion of the interior.
8. The linear motion bearing system as recited in claim 6, wherein
the rail has a hollow interior effective to receive at least a
portion of the rolling element retainer structure; and the bearing
outer race to housing intermediate load structure is placed on an
exterior of the rail.
9. A linear motion bearing system comprising: a rolling element
retainer structure having at least a portion of a plurality of open
axial rolling element tracks formed therein, said rolling element
tracks including an open load bearing portion, an open return
portion and turnarounds interconnecting the load bearing and return
portions; a plurality of bearing rolling elements disposed in the
rolling element tracks; a plurality of load bearing outer races
axially positioned adjacent the rolling element retainer structure,
the load bearing outer races effective to receive load from the
rolling elements disposed in the load bearing portion of the
rolling element tracks; an outer housing sleeve effective to hold
the rolling element retainer structure; and a rail effective to
mate with the rolling element retainer structure, the rail
including at least one recess sized and shaped so as to be mateable
with at least one of the bearing rolling elements and a base
portion effective to mate with the rolling element retainer
structure, wherein the base portion includes at least one of a
rectangular solid, a diamond cross-section, an hourglass
cross-section, a cylindrical configuration, or a spline
configuration; the recess has a half-circle cross-section and
extends along a length of the rail; the radius and circumference of
the recess corresponds to a radius and circumference of the bearing
rolling elements; and the recess has a half-cylinder shape.
10. The linear motion bearing system as recited in claim 9, further
comprising a bearing outer race to housing intermediary load
structure, the bearing outer race to housing intermediary load
structure comprising a plurality of pieces and defining at least
two spaces in between the pieces, the bearing outer race to housing
intermediary load structure extending circumferentially around the
outer housing sleeve; wherein the rail has a hollow interior
effective to receive at least a portion of the rolling element
retainer structure; and the bearing outer race to housing
intermediate load structure is placed at an inner race portion of
the interior.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of prior application Ser.
No. 13/812,608, filed Apr. 5, 2013, which is a national stage of
PCT Application No. PCT/US92011/045478, filed Jul. 27, 2011, which
claims priority to provisional application number 61/368,404 filed
Jul. 28, 2010, the contents of each of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] This disclosure relates to a linear bearing and rail.
[0003] In a linear motion bearing, a generally cylindrical housing
is designed to move relative to a rail. The housing includes a
rolling element retaining structure comprising a plurality of
rolling element-retaining segments. Each rolling element-retaining
segment includes a plurality of bearing rolling elements moveable
in a track. The segments are mounted within the housing so that
movement of the housing wi.sub.th respect to the shaft is
effectuated through engagement of the bearings with the rail. As
the housing moves, the bearing rolling elements move in respective
tracks. This disclosure describes an improvement on these prior art
systems.
SUMMARY OF THE INVENTION
[0004] One embodiment of the invention is a linear motion bearing
system. The linear motion bearing system may comprise a rolling
element retainer structure having at least a portion of a plurality
of open axial rolling element tracks formed therein, said rolling
element tracks including an open load bearing portion, an open
return portion and turnarounds interconnecting the load bearing and
return portions. The linear motion bearing system may further
comprise a plurality of bearing rolling elements disposed in the
rolling element tracks. The linear motion bearing system may
further comprise a plurality of load bearing outer races axially
positioned adjacent the rolling element retainer structure, the
load bearing outer races effective to receive load from the rolling
elements disposed in the load bearing portion of the rolling
element tracks. The linear motion bearing system may further
comprise an outer housing sleeve effective to hold the rolling
element retainer structure. The linear motion bearing system may
further comprise a rail effective to mate with the rolling element
retainer structure, the rail including at least one recess sized
and shaped so as to be mateable with at least one of the bearing
rolling elements.
[0005] Another embodiment of the invention is a linear motion
bearing system. The linear motion bearing system may comprise a
rolling element retainer structure having at least a portion of a
plurality of open axial rolling element tracks formed therein, said
rolling element tracks including an open load bearing portion, an
open return portion and turnarounds interconnecting the load
bearing and return portions. The linear motion bearing system may
further comprise a plurality of bearing rolling elements disposed
in the rolling element tracks. The linear motion bearing system may
further comprise a plurality of load bearing outer races axially
positioned adjacent the rolling element retainer structure, the
load bearing outer races effective to receive load from the rolling
elements disposed in the load bearing portion of the rolling
element tracks. The linear motion bearing system may further
comprise an outer housing sleeve effective to hold the rolling
element retainer structure. The linear motion bearing system may
further comprise a rail effective to mate with the rolling element
retainer structure, the rail including at least one recess sized
and shaped so as to be mateable with at least one of the bearing
rolling elements and a base portion effective to mate with the
rolling element retainer structure. The base portion may include at
least one of a rectangular solid, a diamond cross-section, an
hourglass cross-section, a cylindrical configuration, or a spline
configuration. The recess may have a half-circle cross-section and
extend along a length of the rail. The radius and circumference of
the recess may correspond to a radius and circumference of the
bearing rolling elements. The recess may have a half-cylinder
shape.
[0006] Another embodiment of the invention is a method for
assembling a linear motion bearing system. The method may comprise
placing an outer housing sleeve circumferentially around a rolling
element retainer structure, the rolling element retainer structure
having at least a portion of a plurality of open axial rolling
element tracks formed therein, the rolling element tracks including
an open load bearing portion, an open return portion and
turnarounds interconnecting the load bearing and return portions.
The method may further comprise placing a plurality of bearing
rolling elements in the rolling element tracks. The method may
further comprise placing a plurality of load bearing outer races
axially adjacent the rolling element retainer structure, the load
bearing outer races effective to receive a load from the rolling
elements disposed in the load bearing portion of the rolling
element tracks. The method may further comprise mating the rolling
element retainer structure with a rail, the rail including at least
one recess sized and shaped so as to be mateable with at least one
of the bearing rolling elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The drawings constitute a part of the specification and
include exemplary embodiments of the present invention and
illustrate various objects and features thereof.
[0008] FIG. 1 is an exploded perspective view of a linear motion
bearing assembly;
[0009] FIG. 2 is a perspective view of a rolling element retainer
segment;
[0010] FIG. 3A is a perspective view of a sleeve portion of the
outer housing of the linear motion bearing assembly of FIG. 1.
[0011] FIG. 3B is a side view of the sleeve portion of FIG. 3A.
[0012] FIG. 3C is a cross-sectional view taken along line 3C-3C in
FIG. 3B of the sleeve portion of FIG. 3A.
[0013] FIG. 4 is a perspective view of the load bearing outer race
in accordance with the linear motion bearing assembly of FIG.
1.
[0014] FIG. 5 is a cross-sectioned view of the bearing outer race
to housing intermediary structure taken along line 5-5 of FIG.
1.
[0015] FIG. 6 is a perspective view of the assembled linear motion
bearing assembly of FIG. 1.
[0016] FIG. 7 is a perspective view of a linear motion bearing
assembly.
[0017] FIG. 8 is an exploded perspective view of a bearing outer
race to housing intermediary load structure.
[0018] FIG. 9 is a perspective view of an interlock structure of a
linear motion bearing assembly.
[0019] FIG. 10 is a perspective view of an interlock structure of a
linear motion bearing assembly.
[0020] FIGS. 11A, 11B and 11C are perspective views of rails, which
could be used in accordance with an embodiment of the
disclosure.
[0021] FIG. 12A is a plan view of a rail and linear motion bearing
assembly and FIG. 12B is a perspective view of a rail and linear
motion bearing assembly in accordance with an embodiment of the
disclosure.
[0022] FIG. 13 is a perspective view of a rail, which could be used
in accordance with an embodiment of the disclosure.
[0023] FIG. 14 is a perspective view of a rail, which could be used
in accordance with an embodiment of the disclosure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0024] Various embodiments of the invention are described
hereinafter with reference to the figures. Elements of like
structures or function are represented with like reference numerals
throughout the figures. The figures are only intended to facilitate
the description of the invention or as a guide on the scope of the
invention. In addition, an aspect described in conjunction with a
particular embodiment of the invention is not necessarily limited
to that embodiment and can be practiced in conjunction with any
other embodiments of the invention.
[0025] Referring to FIGS. 1-6, there is shown a linear motion
open-type bearing assembly 40. The bearing assembly includes
rolling element retainer structure, shown generally at 42,
load-bearing outer races 44, bearing rolling elements 46, outer
housing sleeves 48, 50 and a bearing outer race to housing
intermediary load structure 52. Rolling elements 46 could include,
for example, balls, rollers (cylindrical, spherical, concavex,
etc.), ellipsoids, diamond shaped rollers, etc. Outer race 44 could
be conformal or non-conformal.
[0026] Focusing on FIG. 2, rolling element retainer structure 42,
in one example, comprises four rolling element retainer segments
54, each operatively associated with adjacent rolling element
retainer segments along longitudinal sides thereof to form a
polygonally shaped rolling element retainer structure having a bore
there through for receiving a shaft 70. Each rolling element
retainer segment 54 includes an outer radial surface 56 and an
inner radial surface 58. Axial rolling element tracks 60 are formed
in the outer radial surface 56 of each rolling element retainer
segment 54 and include load bearing portions 62, return portions 64
and turnarounds 66. The load bearing and return portions of the
rolling element tracks in this embodiment are undercut to
facilitate loading and retention of the bearing rolling elements 46
therein. This also eliminates the need for a separate retainer
structure to keep the bearing rolling elements in the rolling
element tracks. A longitudinal bore 68 in the inner radial surface
58 of the rolling element retainer segment 54 extends substantially
the length of the load bearing portions 62 and accesses shaft 70.
Although shaft 70 is illustrated as a substantially cylindrical
shaft, support members of other configurations may also be
used.
[0027] A plurality of bearing rolling elements 46 are disposed in
the rolling element tracks 60 with those bearing rolling elements
46 in the load bearing tracks 62 extending at least partially into
longitudinal bores 68 to contact support shaft 70. In this
embodiment, a pair of axial rolling element tracks 60 are formed in
each outer radial surface 56 of the rolling element retainer
segment with the corresponding load bearing tracks being oriented
in substantially parallel adjacent relation. This orientation
facilitates enhanced load capacity and maximizes space utilization
for a more compact and efficient bearing rolling element
arrangement. A locking structure in the form of locking clips 72
are formed on opposing longitudinal ends of each rolling element
retainer segment 54 to facilitate assembly with outer housing
sleeves 48, 50, discussed in greater detail herein below.
[0028] Referring now to FIGS. 1 and 3A-C, the linear motion bearing
assembly in accordance with one preferred embodiment includes a
pair of outer housing sleeves 48, 50 which, when assembled serve to
close and protect the exposed outer radial surfaces 56 of rolling
element retainer structure 42.
[0029] The outer radial surface 74 of sleeves 48, 50 are preferably
of a smooth cylindrical shape and are configured and dimensioned to
fit within a mounting bore of a tool carriage (not shown). The
inner radial surface 76 of sleeves 48, 50 include mounting surfaces
78 which are configured to receive at least a portion of load
bearing outer races 44 therein. These mounting surfaces 78 further
include extension portions 80 which define a mounting space for
bearing outer race to housing intermediary load structure 52,
described in greater detail below. Mounting surfaces 78 may be
recessed from outer radial surface 74 by a distance approximating
the cross-sectional radial thickness of bearing outer race to
housing intermediary load structure 52. In this manner, the outer
housing sleeves 48, 50 and the bearing outer race to housing
intermediary load structure 52 combine to form a relatively smooth
and uniform outer radial surface of the linear motion bearing
assembly 40. See, FIG. 6.
[0030] In this embodiment, mounting surfaces 78 are configured to
fit the shape of individual rolling element retainer segments 54. A
plurality of locking bores 82 are formed in respective ends of
sleeves 48, 50 in alignment with locking clips 72 of rolling
element retainer segments 54. Thus, when the rolling element
retainer segments 54 are assembled into the sleeves 48, 50, locking
clip 72 extends into respective locking bores 82 and assists in
holding linear motion bearing assembly 40 together.
[0031] Referring now to FIGS. 1 and 4, a plurality of individual
load bearing outer races 44 are incorporated into the linear motion
bearing assembly 40 and serve to receive load from the bearing
rolling elements 46 in contact with shaft 70. In the embodiment of
FIG. 4, load bearing outer race 44 is elongated along the
longitudinal axis of the bearing assembly and includes an outer
radial surface 84, an inner radial surface 86, and a pair of side
wall surfaces 88. The outer radial surface 84 is substantially
accurate and may include a crown portion 90 disposed on the outer
radial surface 84 in a medial position. Crown portion 90 is
configured and dimensioned to permit the load bearing outer races
44 to rock both circumferentially and longitudinally into and out
of parallelism with the axes of the rolling element retainer
structure 42.
[0032] The inner radial surface 86 of the load bearing outer race
is advantageously provided with a pair of axial grooves, which
serve as the upper surface of load bearing portions 62 of rolling
element tracks 60. By providing a single load bearing outer race 44
for each pair of load bearing portions 62 in each outer radial
surface 56, the linear motion bearing assembly 40 is easier to
fabricate and assemble. Further, the bearing assembly has a high
load bearing capacity.
[0033] In this embodiment, a longitudinal groove 92 is formed in
each sidewall surface 88 of load bearing outer races 44. These
grooves 92 make up a sidewall of the axial rolling element tracks
60 and guide bearing rolling elements 46 as they move through the
return portion thereof.
[0034] Referring now to FIGS. 1, 5 and 6, bearing outer race to
housing intermediary load structure 52 is illustrated in a C-ring
configuration having an outer radial surface 94 conforming
substantially in dimension to the outer radial surface 74 of
sleeves 48, 50. In this embodiment, the inner radial surface 96 is
arcuate to the outer radial surface and is configured and
dimensioned, when assembled, to contact crown portion 90 of load
bearing outer races 44. In an example, the radius of curvature of
the crown portion 90 in the transverse direction is smaller than
the radius of curvature of the inner radial surface of the bearing
outer race to housing intermediary load structure 52. This
configuration allows the outer races to rock circumferentially with
respect to the inner surface of the bearing outer race to housing
intermediary load structure 52. In other examples, crown portion 90
is substantially flat as shown in FIG. 4.
[0035] Further, referring to FIGS. 1 and 6, the bearing outer race
to housing intermediary load structure 52 encompasses and engages
extension portions 80 of sleeve 48, 50 to assist in enclosing and
protecting rolling element retainer structure 42. Although shown in
a narrow width, the bearing outer race to housing intermediary load
structure 52 may extend substantially the entire longitudinal
length of the bearing assembly. The bearing outer race to housing
intermediary load structure may be formed of a hard abrasion
resistant material such as, for example, stainless steel or
ceramic. Alternatively, a softer material such as bronze or
aluminum may also be used.
[0036] FIGS. 7 and 8 are perspective view drawings of another
bearing outer race to housing intermediary load structure 152.
Bearing outer race to housing intermediary load structure 54 in
FIGS. 1-6 was substantially one piece and monolithic. Bearing outer
race to housing intermediary load structure 152 is comprised of at
least two discrete pieces 154 with spaces 158 in between pieces
154. Five pieces 154a, 154b, 154c, 154d, 154e are shown in FIG. 8
though any number of pieces could be used. Pieces 154 may be
cylinders, spheres, flattened cylinders, spheroids, concavex
diamonds, ellipsoids, pyramids, etc. An odd number of pieces may
make it easier to tune bearing outer race to housing intermediary
load structure 152. Pieces 154 may be distributed around a
circumference of sleeve 48, 50 so that each space 158 between each
piece 154 is of the same size. Sleeve 48, 50 may comprise multiple
pieces or a single piece.
[0037] Each piece 154 has an internal arc with a radius of
curvature 162 (FIG. 8) that corresponds to or is slightly larger
than a radius of curvature 160 of outer housing sleeve 48, 50. The
inventor has discovered that the tolerance accuracy needed to
manufacture monolithic bearing outer race to housing intermediary
load structure 52 (FIGS. 1-6), is quite high and therefore
expensive to produce. In fact, a high percentage of manufactured
pieces may need to be discarded because of the high necessary
tolerance accuracies. If bearing outer race to housing intermediary
load structure 52 includes dimensions too far removed from defined
tolerances, excess unbalanced pressure may be placed on outer
housing sleeve 48, 50 and then on bearing rolling elements 46 (FIG.
1).
[0038] In contrast, tolerance accuracy requirements are lower for
bearing outer race to housing intermediary load structure 152
having multiple pieces 154. Each piece 154 requires less tolerance
accuracy, which results in faster, less expensive manufacturing.
Pieces 154 are less sensitive to twisting forces applied to outer
housing sleeve 48, 50. Bearing outer race to housing intermediary
load structure 152 is less sensitive to out of "roundness" from
each piece 154. Less material is used for bearing outer race to
housing intermediary load structure 152 and more manufacturing
methods are available. Powder metal could be used to manufacture
pieces 154.
[0039] A retention member 156 (best seen in FIG. 8) may be used to
affix bearing outer race to housing intermediary load structure 152
to outer housing sleeve 48, 50. Retention member 156 could be, for
example, a flare from each piece 154, a male extension, a female
extension, etc. A corresponding mating retention member 164 may be
disposed in outer housing sleeve 48, 50. Mating retention member
164 could be, for example, a recess, a female extension, a male
extension etc. Each piece 154 may be pliant and biased toward the
position shown in the figures. In this way, to assemble, each piece
154 may be pinched and inserted into recesses 164 of outer housing
sleeve 48, 50 so that flares 156 are bent inwardly. The bias causes
piece 154 to resume the position shown to mate with recesses
158.
[0040] Reference now may be made to FIG. 9 where there is shown
another structure that could be used to hold together linear motion
bearing assembly 40. As shown, an interlock structure 170 may be
formed on outer housing sleeves 48, 50 or on other sleeves used in
a linear motion bearing assembly. One sleeve 48, 50 is shown in
FIG. 9 for simplicity. Interlock structure 170 may be
hermaphroditic including both male and female type structures. One
interlock structure 170 may be formed on outer housing sleeve 48
and a second interlock structure 170 may be formed on outer housing
sleeve 50. In this way, when outer housing sleeve 48 is moved along
a longitudinal axis of linear motion bearing assembly 40, into
engagement with outer housing sleeve 50, first interlock structure
170 is placed over and mates with second interlock structure 170
thereby holding linear motion bearing assembly 40 together.
Interlock structures 170 may be placed around pieces 154a, 154b, of
bearing outer race to housing intermediary load structure 152
discussed above so that pieces 154a, 154b may be disposed in a
space 176 defined by walls of interlock structure 170.
[0041] FIG. 10 shows another structure that could be used to hold
together linear motion bearing assembly 40. As shown, an interlock
structure 180 may be formed on outer housing sleeves 48, 50 or on
other sleeves used in a linear motion bearing assembly. Interlock
structure 180 may include a tab 182, a cylindrical protrusion 184,
and a recess 186. Tab 182 may be, for example, rectangular in
cross-section. Outer housing sleeve 48 may include one tab 182a and
outer housing sleeve 50 may include a second tab 182b. In this way,
when outer housing sleeve 48 is brought into engagement with outer
housing sleeve 50, first interlock structure 180 is placed over
second interlock structure 180, and tab 182a can be overlapped with
tab 182b. Protrusion 184a can be placed into recess 186b and
protrusion 184b can be placed into recess 186a thereby holding
linear motion bearing assembly 40 together.
[0042] Interlock structure 170 and interlock structure 180 could
both be used in a single linear motion bearing assembly 40--for
example, on diametrically opposed sides. As interlock structure 170
includes the same structure on both outer housing sleeve 48 and 50,
the production of linear motion bearing assembly 40 may be
simplified. Only a single type of sleeve may be produced as the
sleeves are interchangeable. Interlock structures 170, 180 prevent
linear motion bearing assembly 40 from being pulled apart due to
forces extending longitudinally outward away from a center of
linear motion bearing assembly 40. Locking clips 72 (discussed
above with reference to FIGS. 1-6) likely would not be able to
resist such forces without interlock structures 170, 180. Interlock
structures 170, 180 thus improve an integrity of linear motion
bearing assembly 40.
[0043] Referring to FIGS. 11A, 11B and 11C, there is shown a rail
200a/200b/200c which could be used in accordance with an embodiment
of the disclosure. Rail 200a/200b/200c could be used with any of
the linear motion bearing assembly structures mentioned above. Rail
200a/200b/200c includes a base portion 206a/206b/206c upon which a
linear motion bearing assembly may be mated. Base portions
206a/206b/206c with a rectangular solid cross-section 206a, a
diamond cross-section 206b and an hourglass cross-section 206c are
shown. Base portion 206a/206b/2060c includes recesses
202a/202b/202c having a substantially half-circle cross-section and
which extend along a length of rail 200a/200b/200c. Recesses
202a/202b/202c thus have a half-cylinder shape with a radius and
circumference corresponding to, or slightly larger than, a radius
and circumference of bearing rolling elements 224a/224b/224c of a
linear motion bearing assembly. Any number of recesses
202a/202b/202c may be used. Rail 200a/200b/200c may have a hollow
interior to allow for receipt of a linear motion bearing assembly
(shown in FIGS. 12A and 12B). Recesses 202a/202b/202c, with a
radius and circumference corresponding to a radius and
circumference of bearing rolling elements 224a/224b/224c, thus
provide a self-aligning functionality. When a linear motion bearing
assembly is mated with rail 200a/200b/200c, the bearing assembly is
easily aligned with rail 200a/200b/200c.
[0044] FIG. 12A shows an example of linear motion bearing system
250, including rail 200 mated with a linear motion bearing assembly
220 and FIG. 12B shown an example of the linear motion bearing
assembly 220. For simplicity, in the figures, only some elements of
linear motion bearing assembly 220 are shown. Any of the features
discussed in the above linear motion bearing assemblies may be used
with linear motion bearing assembly 220. For example, bearing outer
race to housing intermediary load structures 222 may be used.
Bearing outer race to housing intermediary load structures 222 may
be placed at an inner race potion in hollow interior 204 of rail
200 as shown at 222b, or outer housing sleeve 248 exterior to rail
200 as shown at 222a, or at both locations.
[0045] Linear motion bearing assembly 220 includes bearing rolling
elements 224 in a track 226. Bearing rolling elements 224 mate with
recesses 202 of rail 200. In this way, linear motion bearing
assembly 220 is easily and efficiently aligned with rail 200.
Recesses 202 in rail 200 provide more give or flexibility in rail
200. Prior art systems are typically either very rigid and do not
provide for self-alignment or are too flexible which detracts from
accuracy. As shown in FIGS. 12A and 12B, races (both inner and
outer) can self-align using outer race to housing intermediary load
structures. This makes the product easier to use and more tolerant
of mis-alignments without any significant loss of capability. The
structure may also provide an improved performance over
non-self-aligning designs. This self-alignment design, with outer
race to housing intermediate load structures, can also be
configured in the various rail shapes, layouts and configurations
shown and described.
[0046] FIG. 13 shows another rail 250 which could be used in
accordance with the disclosure. Rail 250, like rail 200 may be used
with any of the linear motion bearing assemblies mentioned above.
Rail 250 is in a spline configuration and includes a base 252 that
is substantially cylindrical in shape. Base 252 includes recesses
254 having a substantially circle cross-section and which extend
along a length of rail 250. Recesses 252 thus have a half-cylinder
shape with a radius and circumference corresponding to a radius and
circumference of bearing rolling elements 224 of a linear motion
bearing assembly. Four recesses 254 are generally shown though any
number may be used. Recesses 254, with a radius and circumference
corresponding to a radius and circumference of bearing rolling
elements, thus provide a self-aligning functionality. When a linear
motion bearing assembly is mated with rail 250, the bearing
assembly is easily aligned with rail 250.
[0047] FIG. 14 shows another rail 260 which could be used in
accordance with the disclosure. Rail 260, like rail 200 may be used
with any of the linear motion bearing assemblies mentioned above.
Rail 260 includes a base 262 that is a substantially a rectangular
solid and includes hooked portions 264 which define substantially
cylindrical defining recesses 268. Recesses 268 extend along a
length of rail 260. Recesses 260 have a radius and circumference
corresponding to a radius and circumference of bearing rolling
elements 266 of a linear motion bearing assembly. Four recesses 268
are generally shown though any number may be used. Recesses 268,
with a radius and circumference corresponding to a radius and
circumference of bearing rolling elements 268, thus provide a
self-aligning functionality. When a linear motion bearing assembly
is mated with rail 260, the bearing assembly is easily aligned with
rail 260.
[0048] While the invention has been described with reference to a
number of exemplary embodiments, it will be understood by those
skilled in the art that various changes can be made and equivalents
can be substituted for elements thereof without departing from the
scope of the invention. In addition, many modifications can be made
to adapt a particular situation or material to the teachings of the
invention without departing from essential scope thereof.
Therefore, it is intended that the invention not be limited to any
particular exemplary embodiment disclosed herein.
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